Showing papers by "University of Colorado Denver published in 2023"

SGLT2 inhibitors mitigate kidney tubular metabolic and mTORC1 perturbations in youth-onset type 2 diabetes

Abstract: The molecular mechanisms of sodium-glucose cotransporter-2 (SGLT2) inhibitors (SGLT2i) remain incompletely understood. Single-cell RNA sequencing and morphometric data were collected from research kidney biopsies donated by young persons with type 2 diabetes (T2D), aged 12 to 21 years, and healthy controls (HCs). Participants with T2D were obese and had higher estimated glomerular filtration rates and mesangial and glomerular volumes than HCs. Ten T2D participants had been prescribed SGLT2i (T2Di[+]) and 6 not (T2Di[-]). Transcriptional profiles showed SGLT2 expression exclusively in the proximal tubular (PT) cluster with highest expression in T2Di(-) patients. However, transcriptional alterations with SGLT2i treatment were seen across nephron segments, particularly in the distal nephron. SGLT2i treatment was associated with suppression of transcripts in the glycolysis, gluconeogenesis, and tricarboxylic acid cycle pathways in PT, but had the opposite effect in thick ascending limb. Transcripts in the energy-sensitive mTORC1-signaling pathway returned toward HC levels in all tubular segments in T2Di(+), consistent with a diabetes mouse model treated with SGLT2i. Decreased levels of phosphorylated S6 protein in proximal and distal tubules in T2Di(+) patients confirmed changes in mTORC1 pathway activity. We propose that SGLT2i treatment benefits the kidneys by mitigating diabetes-induced metabolic perturbations via suppression of mTORC1 signaling in kidney tubules.

Cross-platform normalization enables machine learning model training on microarray and RNA-seq data simultaneously

Abstract: Abstract Large compendia of gene expression data have proven valuable for the discovery of novel biological relationships. Historically, most available RNA assays were run on microarray, while RNA-seq is now the platform of choice for many new experiments. The data structure and distributions between the platforms differ, making it challenging to combine them directly. Here we perform supervised and unsupervised machine learning evaluations to assess which existing normalization methods are best suited for combining microarray and RNA-seq data. We find that quantile and Training Distribution Matching normalization allow for supervised and unsupervised model training on microarray and RNA-seq data simultaneously. Nonparanormal normalization and z-scores are also appropriate for some applications, including pathway analysis with Pathway-Level Information Extractor (PLIER). We demonstrate that it is possible to perform effective cross-platform normalization using existing methods to combine microarray and RNA-seq data for machine learning applications.

Research Priorities of Individuals and Caregivers With Lewy Body Dementia

Abstract: Lewy body dementia (LBD) is common, yet under-recognized and under-researched. To plan studies with the highest impact, engagement of the community personally affected by these conditions is essential.A web-based survey of people living with LBD and current and former caregivers of people with LBD queried research priorities through forced ranking and exploration of burden of LBD symptoms. Specific caregiving needs in LBD and perceptions of research participation were also investigated.Between April 7, 2021 and July 1, 2021, 984 responses were recorded. Top research priorities included disease-modifying therapies and improved disease detection and staging. People with LBD were interested in pathophysiology and more bothered by motor symptoms; caregivers were interested in risk factors and symptomatic therapies and more bothered by neuropsychiatric symptoms. Few available LBD treatments and resources were rated as helpful, and many valuable services were never received. Previous participation in LBD research was infrequent, but interest was high.People with LBD and caregivers highlighted the need for research across all aspects of LBD, from pathophysiology and disease modification to prognosis, education, symptomatic treatments, and caregiver support. Funders should increase support for all aspects of LBD research to target the many needs identified by individuals and families living with LBD.

Mass Spectrometry-Based Atlas of Extracellular Matrix Proteins across 25 Mouse Organs

Abstract: The extracellular matrix (ECM) is a critical non-cellular component of multicellular organisms containing a variety of proteins, glycoproteins, and proteoglycans which have been implicated in a wide variety of essential biological processes, including development, wound healing, and aging. Due to low solubility, many ECM proteins have been underrepresented in previous proteomic datasets. Using an optimized three-step decellularization and ECM extraction method involving chaotrope extraction and digestion via hydroxylamine hydrochloride, we have generated coverage of the matrisome across 25 organs. We observe that the top 100 most abundant proteins from the ECM fractions of all tissues are generally present in all tissues, indicating that tissue matrices are principally composed of a shared set of ECM proteins. However, these proteins vary up to 4000-fold between tissues, resulting in highly unique matrix profiles even with the same primary set of proteins. A data reduction approach was used to reveal related networks of expressed ECM proteins across varying tissues, including basement membrane and collagen subtypes.

Maternal Western diet is associated with distinct preclinical pediatric NAFLD phenotypes in juvenile nonhuman primate offspring

Abstract: Export Pediatric NAFLD has distinct and variable pathology, yet causation remains unclear. We have shown that maternal Western-style diet (mWSD) compared with maternal chow diet (CD) consumption in nonhuman primates produces hepatic injury and steatosis in fetal offspring. Here, we define the role of mWSD and postweaning Western-style diet (pwWSD) exposures on molecular mechanisms linked to NAFLD development in a cohort of 3-year-old juvenile nonhuman primates offspring exposed to maternal CD or mWSD followed by CD or Western-style diet after weaning. We used histologic, transcriptomic, and metabolomic analyses to identify hepatic pathways regulating NAFLD. Offspring exposed to mWSD showed increased hepatic periportal collagen deposition but unchanged hepatic triglyceride levels and body weight. mWSD was associated with a downregulation of gene expression pathways underlying HNF4α activity and protein, and downregulation of antioxidant signaling, mitochondrial biogenesis, and PPAR signaling pathways. In offspring exposed to both mWSD and pwWSD, liver RNA profiles showed upregulation of pathways promoting fibrosis and endoplasmic reticulum stress and increased BiP protein expression with pwWSD. pwWSD increased acylcarnitines and decreased anti-inflammatory fatty acids, which was more pronounced when coupled with mWSD exposure. Further, mWSD shifted liver metabolites towards decreased purine catabolism in favor of synthesis, suggesting a mitochondrial DNA repair response. Our findings demonstrate that 3-year-old offspring exposed to mWSD but weaned to a CD have periportal collagen deposition, with transcriptional and metabolic pathways underlying hepatic oxidative stress, compromised mitochondrial lipid sensing, and decreased antioxidant response. Exposure to pwWSD worsens these phenotypes, triggers endoplasmic reticulum stress, and increases fibrosis. Overall, mWSD exposure is associated with altered expression of candidate genes and metabolites related to NAFLD that persist in juvenile offspring preceding clinical presentation of NAFLD.

Economic Impact of a Change in Medicaid Coverage Policy for Dialysis Care of Undocumented Immigrants

Abstract: Undocumented immigrants comprise an estimated 11 million of the US population. Access to health care for this community is limited; nearly 50%–70% lack health care insurance.1 Undocumented immigrants can receive primary care through safety-net clinics, such as federally qualified health centers, and they can receive emergency medical treatment as mandated by the Emergency Medical Treatment and Active Labor Act (EMTALA). There are medical conditions, however, with treatments that do not fall into primary care or emergency medical care, as strictly defined by EMTALA. This is the case for undocumented immigrants with kidney failure. There are an estimated six to 9000 undocumented immigrants with kidney failure across the United States.2 The 1972 Medicare ESKD entitlement program provides health care coverage of all kidney replacement therapy options for US citizens and permanent residents present for 5 years, regardless of age.2 Undocumented immigrants are not eligible for this Medicare benefit. In 2019, 12 states provided state-wide access to outpatient thrice-weekly hemodialysis through Medicaid or Emergency Medicaid. In the other 38 states, undocumented immigrants did not have uniform state-wide access to kidney replacement therapy through Medicaid or Emergency Medicaid; in those states, many relied on emergency only hemodialysis (dialysis only after presenting critically ill to an emergency department). The costs of emergency-only hemodialysis are likely different than providing routine thrice-weekly hemodialysis sessions or home dialysis. Providing care to a growing number of patients who may need treatment may generate concern about costs. Before 2019 in Colorado, undocumented immigrants could only receive dialysis approximately every 7 days and if they met hospital-based criteria qualifying as a medical emergency, as mandated by EMTALA. Under EMTALA, uninsured individuals can only receive health care coverage if treatment is for an emergency medical condition “such that absence of immediate medical attention could reasonably be expected to result in placing the patient's health in serious jeopardy, serious impairment to the bodily functions, or serious dysfunction of any bodily organ or part” (Social Security Act 1903; https://www.ssa.gov/OP_Home/ssact/title19/1903.htm). Research demonstrated that undocumented immigrants who rely on emergency-only hemodialysis and their family caregivers (who are often US citizens) experience psychosocial distress from weekly near-death experiences.3,4 Their treating clinicians report drivers of burnout from witnessing needless suffering and moral distress from providing care on the basis of nonmedical factors, such as immigration and health insurance status.5 In addition, compared with undocumented immigrants who receive routine thrice-weekly hemodialysis, these patients have a 5- and 14-fold higher 1- and 5-year mortality rates, respectively, as well as higher resource utilization.6,7 Under EMTALA, the services and conditions that qualify as an emergency and are reimbursed under Emergency Medicaid are decided at the state level. In 1997, the Office of the Inspector General affirmed the state's role in defining an emergency medical condition: “Centers for Medicare and Medicaid Services allows each state to identify which conditions qualify as emergencies” (Office of the Inspector General Report on New Jersey's Program A-02-07-01038; https://oig.hhs.gov/oas/reports/region2/20701038.pdf). Before 2019, undocumented immigrants in Colorado qualified for Emergency Medicaid health care coverage for emergency dialysis. This health care coverage included emergency department visit and hospitalization; outpatient-related services (e.g., medications and surgeries) were not included. In 2019, Colorado decided to include the diagnosis of kidney failure as a qualifying condition for Emergency Medicaid, thereby expanding health care coverage to outpatient thrice-weekly hemodialysis, home dialysis, as well as health care coverage of dialysis-related medications and surgeries for undocumented immigrants with kidney failure.8 Undocumented immigrants who transition from emergency to routine thrice-weekly hemodialysis in Colorado reported an improvement in quality of life and symptom burden and felt that their humanity had been restored.9 Research demonstrates that, in general, undocumented immigrants with kidney failure are more likely to work because they do not receive federal benefits. With this health care policy change, undocumented immigrants are able to work and contribute a tax surplus to the US financing system, helping to subsize the health care of US residents.10 The health care policy change in Colorado reimbursing outpatient dialysis centers at Medicaid rates took effect on February 1, 2019. Data from the Colorado Department of Health Care Policy and Financing show that the annual Emergency Medicaid Service (EMS) dialysis expenditures for all undocumented immigrants with kidney failure undergoing emergency-only hemodialysis in 2017 and 2018 (n=81 and n=78 per month, respectively) was almost $20,000,000, with an average monthly EMS dialysis patient expenditure of $20,000 (Figure 1). After the health care policy change, in 2019 and 2020, total annual and monthly expenditures decreased almost three-fold and by 2021, total monthly expenditures decreased four-fold. In 2021, total annual expenditures increased to over $9,000,000, with an increase in the number of patients served (n=135 per month); however, the average monthly patient expenditure remained lower at $5574. While the number of undocumented immigrants with kidney failure has increased, the Medicaid program in Colorado is paying less than half of what it paid before the health care policy change. Evaluation over time is needed to know whether the cost savings can be sustained if care is extended to more patients. In addition, states that may similarly benefit would be those similar to Colorado, where Emergency Medicaid pays for the emergency department visit and hospitalization related to emergency dialysis. Finally, our findings are similar to a Houston, Texas, study that assessed 1-year cost savings among undocumented immigrants with kidney failure who transitioned from emergency dialysis to scheduled dialysis after enrolling into private health insurance. They estimated a net savings of nearly $6000 per person per month or $720,000 per person per year.7Figure 1.: Medicaid dialysis expenditures for undocumented immigrants before and after change in state Medicaid policy.There are several explanations for the increase in the number of undocumented immigrants with kidney failure in the state. There may be concern that more undocumented patients with kidney failure are being attracted to the state by the change in health care coverage policy. However, as patients transitioned to standard outpatient dialysis, their risk of mortality likely decreased as shown in prior studies.6,7 Likely, newly diagnosed patients with kidney failure add to the number of existing patients who are living longer. It is possible that changes in risk factors of kidney failure (e.g., coronavirus disease 2019 and diabetes), which disproportionately burden the undocumented immigrant community, could contribute to increases in the kidney failure incidence. The National Kidney Foundation and the American Society of Nephrology have urged state Medicaid directors to expand access to kidney replacement therapy, including kidney transplantation, for undocumented immigrants in a letter that was supported by several physician organizations, including the Society of General Internal Medicine, the American Society of Nephrology, and the Society of Hospital Medicine. Clinician and advocacy groups have engaged in changing access to kidney replacement therapy for undocumented immigrants in their states. Indeed, a Colorado team of clinicians, community organizations, and state Medicaid employees described the Medicaid policy strategy to inform other states similarly interested in expanding this access.8 In addition, a national approach to expanding access to kidney replacement therapy may be more effective and may address concerns regarding the movement of undocumented immigrants to states where there is adequate health care coverage. This economic analysis demonstrates that states seeking to control Medicaid program costs should consider expanding access to care for undocumented immigrants with kidney failure. Doing so, not only helps contain costs but also benefits patients, caregivers, and providers challenged by the provision of emergency-only hemodialysis care for kidney failure.

Revisiting the “starved gut” hypothesis in inflammatory bowel disease

Abstract: Active episodes of inflammatory bowel disease (IBD), which include ulcerative colitis and Crohn’s disease, coincide with profound shifts in the composition of the microbiota and host metabolic energy demand. Intestinal epithelial cells (IEC) that line the small intestine and colon serve as an initial point for contact for the microbiota and play a central role in innate immunity. In the 1980s, Roediger et al proposed the hypothesis that IBD represented a disease of diminished mucosal nutrition and energy deficiency (“starved gut”) that strongly coincided with the degree of inflammation. These studies informed the scientific community about the important contribution of microbial-derived metabolites, particularly short-chain fatty acids (SCFA) such as butyrate, to overall energy homeostasis. Decades later, it is appreciated that disease-associated shifts in the microbiota, termed dysbiosis, places inordinate demands on energy acquisition within the mucosa, particularly during active inflammation. Here, we review the topic of tissue energetics in mucosal health and disease from the original perspective of that proposed by the starved gut hypothesis.

Cerebellar associative learning underlies skilled reach adaptation

Abstract: The cerebellum is hypothesized to refine movement through online adjustments. We examined how such predictive control may be generated using a mouse reach paradigm, testing whether the cerebellum uses within-reach information as a predictor to adjust reach kinematics. We first identified a population-level response in Purkinje cells that scales inversely with reach velocity, pointing to the cerebellar cortex as a potential site linking kinematic predictors and anticipatory control. Next, we showed that mice can learn to compensate for a predictable reach perturbation caused by repeated, closed-loop optogenetic stimulation of pontocerebellar mossy fiber inputs. Both neural and behavioral readouts showed adaptation to position-locked mossy fiber perturbations and exhibited aftereffects when stimulation was removed. Surprisingly, position-randomized stimulation schedules drove partial adaptation but no opposing aftereffects. A model that recapitulated these findings suggests that the cerebellum may decipher cause-and-effect relationships through time-dependent generalization mechanisms.

Operative Management of Stress-Positive Minimally Displaced Lateral Compression Type 1 (LC1) Pelvic Ring Injuries: Analysis of Outcomes Before and After Implementation of a Departmental Stress Protocol

Abstract: Objectives: To compare the hospital course of patients with minimally displaced (<1 cm) lateral compression type 1 injuries treated before and after implementation of lateral stress radiographs (LSRs) to determine management. Design: Retrospective comparative cohort. Setting: Urban level 1 trauma center. Patients/Participants: Isolated lateral compression type 1 injuries managed before (n = 33) and after implementation of LSRs (n = 40) to determine management. Intervention: Patients in a prestress cohort managed nonoperatively versus patients in an LSR cohort managed operatively if stress positive (≥1 cm displacement on LSRs). Main Outcome Measurements: Physical therapy clearance before discharge, discharge location, hospital length of stay, and inpatient opioid morphine milligram equivalents were measured. Results: The prestress and LSR protocol groups were similar in demographic/injury characteristics (age, sex, mechanism, American Society of Anesthesiologists score, Nakatani classification, bilateral/unilateral injury, Denis zone, sacral fracture completeness, and sacral comminution). Forty-five percent of LSR protocol patients were stress-positive (n = 18) and managed operatively. The LSR protocol group was more likely to clear physical therapy by discharge (97.5% vs. 75.8%, PD: 21.7%, 95% CI: 5.1%–36.8%, P = 0.009), less likely to discharge to a rehabilitation facility (2.5% vs. 18.2%, PD: −15.7%, CI: −30.0% to −0.5%, P = 0.04), and had no difference in length of stay (MD: 0.0, CI:-1.0 to 1.0, P = 0.57) or inpatient opioid morphine milligram equivalents (MD: 9.0, CI: −60.0 to 101.0, P = 0.71). Conclusion: Implementation of an LSR protocol to determine management of minimally displaced stress-positive lateral compression type 1 injuries was associated with increased rates of operative management, physical therapy clearance by discharge, and a reduction in the number of patients discharging to rehabilitation facilities. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Ornamentation diversified faster than eco-morphology across Nearctic dragonflies

Abstract: Abstract Eco-morphology and ornamentation are two phenotypic dimensions along which co-existing species often diverge, yet theory makes contrasting predictions about how these phenotypes diversify relative to each other. Some theory predicts that intense reproductive demands cause more pronounced divergence in ornamentation than in eco-morphology. Other theory predicts that preferences for condition-dependent ornamentation in species encountering divergent ecological conditions will facilitate rapid divergence in eco-morphology but not ornamentation. We evaluated these conflicting predictions in Nearctic Libelluloidea dragonflies by testing if the diversification of a condition-dependent ornament, male wing melanization, was slower and less pronounced between species than the diversification of two key eco-morphological traits, body size and relative wing size. We found that male wing melanization evolved much faster than either body size or relative wing size. Furthermore, in contrast to the patterns for either eco-morphological trait, the best-supported models of diversification in male wing melanization indicate that the majority of divergence arose between the most closely related species. These results reveal that the primary axis of divergence between closely related Libelluloidea dragonflies is ornamentation rather than eco-morphology. Our study therefore suggests that evolutionary responses to disparate reproductive demands may be fundamental to the persistence and co-existence of closely related species.

An emergent temporal basis set robustly supports cerebellar time-series learning

Abstract: During movement, mossy fiber inputs to the cerebellum relay time-varying information with strong intrinsic relationships to ongoing movement. Are such mossy fibers signals sufficient to support Purkinje signals and learning? In a model, we show how the GCL greatly improves Purkinje learning of complex, temporally dynamic signals relative to mossy fibers alone. Learning-optimized GCL population activity was moderately dense, which retained intrinsic input variance while also performing pattern separation.

Evaluation and management of abnormal liver enzymes in the liver transplant recipient: When, why, and what now?

Abstract: INTRODUCTION Among patients who have undergone liver transplantation, liver enzymes (aminotransferases, bilirubin, and alkaline phosphatase) provide an important indicator of graft function, anatomic and biliary complications, and immunologic response. The pattern of elevation in conjunction with the timing and clinical context can offer insight into the mechanism of injury.1 Frequently, an elevation in liver enzymes is the first indicator of graft pathology, providing an opportunity to intervene clinically to preserve allograft function. PATTERNS OF LIVER ENZYME ELEVATION Across the lifetime of a post-transplant patient, complications directly affecting the liver allograft typically fall into several broad categories: early operative injury, vascular and biliary complications, immune-mediated injury, drugs, infectious complications, and recurrence of primary liver disease (Tables 1–3). Cholestatic and hepatocellular liver enzyme patterns can be suggestive of specific diagnoses, but, in many cases, post-transplant complications demonstrate a relatively nonspecific mixed liver enzyme pattern.2 Management of patients, therefore, often relies on a careful clinical history and a nuanced understanding of symptoms, culture data, serologic tests, and imaging. Ultrasound with Doppler, cross-sectional imaging, endoscopic retrograde cholangiopancreatography, and liver biopsy are among the most frequent tools used in the evaluation of post-transplant elevated liver enzymes. In addition, the rate of rise in liver enzymes often portends more potential harm to the liver allograft and can require rapid diagnostic evaluation to guide appropriate intervention. Dynamic physiological and immunologic changes, particularly early post-transplant, can often lead to co-occurring processes that can complicate the identification of otherwise characteristic liver enzyme pattern presentations.3 Therefore, while the pattern of liver enzyme elevation and rate of rise is important, these changes must also be interpreted in a clinical context to allow prompt diagnosis. TABLE 1 - Perioperative, vascular, and biliary causes of abnormal liver enzymes after LT Category Diagnosis Definition Timing Pattern Risk factors Evaluation Treatment Perioperative complications Ischemia reperfusion injury/preservation injury Hepatocellular graft damage that results from perioperative cold and warm ischemic time as well as reperfusion of the donor liver Post-transplant rise in liver enzymes; typically peaks in the first 2–7 d and spontaneously regresses AST/ALT 5-20X ULN Delayed rise in total bilirubin can occur Typically seen to varying degrees in all patients after transplant None Observation PNF Widespread hepatocellular necrosis and hemorrhage, evolving into post-transplant liver failure. PNF Defined as: 1.AST > 3000 2.INR > 2.5 3.Within 7 d of transplantation Within first 7 d AST >3000 IU/ML and INR > 2.5 within 7 d post-LT DCD allograft >12 h cold ischemic time >90 min warm ischemic time Imaging to rule out vascular obstruction Retransplant (listed status 1A) Fluid collection, abscess Perioperative fluid collections can become infected in the absence of source control First 1–2 wk post-transplant Mild liver enzyme pattern, cholestasis of sepsis Hematoma or biloma formation Reoperation/take-back Cross-sectional imaging, labs Drainage of collection Vascular complications Early HAT Acute thrombosis of the hepatic artery associated with a wide range of clinical manifestations including fever, sudden liver enzyme rise, fulminant hepatic failure Median 7 d, within first 2–3 wk after transplantation Acute ischemic injury with sharp rise in ALT and AST typically >10× ULN Arterial reconstruction Delayed reperfusion Multiple anastomoses Urgent duplex ultrasound or CT angiogram Endovascular intervention, occasionally retransplant Late HAT Narrowing of the transverse diameter of HA by 50%, with resistive index <0.5, peak systolic velocity >400 Can be early or late post-transplant, often insidious. Median 3 mo post-transplant Cholestatic pattern due to diffuse biliary stricturing with elevation in AP +/− TB Intraoperative factors (clamp injury, intimal dissection) and donor anatomy Doppler ultrasound Endovascular intervention Surgical revision Biliary complications Biliary stricture (anastomotic and diffuse type) Focal stricturing at the biliary anastomoses or the diffuse stricturing of large intrahepatic or extrahepatic bile ducts of the donor liver. Within first 2–3 wk after transplantation AP 2–5× ULN with elevated TB (predominantly direct) Surgical technique, ischemic time, hypotension ERCP Endoscopic stenting or balloon dilation. May require revision to Roux-en-y. Bile leak Biliary anastomotic leak, typically producing a fluid collection. Reduced drainage from biliary drain. Most commonly within 30 d Tbili elevation No specific risk factors CT to evaluate collection ERCP vs IR guided stenting and drainage Acute cholangitis Rising bilirubin related to obstruction and infection in the bile ducts, often related to stricturing Any time, often within 1–2 wk Tbili and alk phos predominant rise, leukocytosis Duct anastomosis without drain LDLT MRCP ERCP or PTBD tube Drug related complications DILI Multiple postoperative drug exposures including antibiotics, steroids, TPN, and IS (cyclosporine and azathioprine) Following drug administration cholestatic injury common, less common hepatocellular injury but state dependent on agent Drug exposures Liver biopsy, but nonspecific Removal of causative drug Abbreviations: ALT, alanine aminotransferase; AP, alkaline phosphatase; AST, aspartate aminotransferase; ERCP, endoscopic retrograde cholangiopancreatography; HA, hepatic artery; HAT, hepatic artery thrombosis; INR, international normalized ratio; IR, interventional radiology; IS, immunosuppression; LDLT, living donor liver transplantation; LT, liver transplantation; MRCP, magnetic resonance cholangiopancreatography; PNF, primary nonfunction; PTBD, percutaneous transhepatic biliary drainage; TB, total bilirubin; TPN, total parenteral nutrition; ULN, upper limit of normal. TABLE 2 - Immune-mediated causes of abnormal liver enzymes after LT Category Diagnosis Definition Timing Pattern Risk factors Evaluation Treatment T-cell mediated complications Acute T-cell mediated rejection T-cell mediated inflammatory infiltrate causing damage to the bile ducts, portal tract, and endothelium (endotheliitis), not associated with low IS levels Later episodes typically occur in the setting of inadequate IS Median 7–10 d post-transplant, most commonly within the first 90 d AST/ALT typically 5–15× ULN Mild elevation in AP 2–5× ULN Elevation in bilirubin only seen in severe ACR Immune-mediated liver disease Inadequate IS Infection, viremia Liver biopsy Short term increase in IS +/− steroid burst depending on severity Chronic T-cell mediated rejection Destruction and loss of bile ducts (vanishing bile duct) with obliteration of the small hepatic arteries. Often preceded by ACR which does not respond to increased IS. 6 wk–6 m after LT AP elevation to 2–5× ULN +/− elevation in TB Inadequate IS levels or compliance Liver biopsy Increased IS Antibody-mediated complications Acute AMR Rapid graft failure caused by preformed circulating antibodies directed against donor antigens. Causes endothelial damage and necrosis. Rare in liver transplant. Typically only if ABO mismatch. 4 pathologic criteria for diagnosis: microvascular inflammation and portal edema, elevated DSA, C4d deposition, exclusion of other liver diseases Usually within first 3–4 wk post-transplant AST/ALT typically 5–15× ULN Mild elevation in AP 2–5× ULN Elevation in bilirubin only seen in severe ACR ABO mismatch Serum evaluation for DSA Liver biopsy with staining for C4d IVIG treatment Rituximab Plasmapheresis Bortezumib Chronic AMR Can be associated with graft injury and/or advanced fibrosis, abnormal liver enzymes after weaning IS Pathologic features: mild portal inflammation, mild interface hepatitis, dense portal fibrosis. Positive DSA within 3 mo of biopsy. Focal C4d positivity ( >10% portal tracts). Exclusion of other causes Any time after the first month after transplantation Similar to early AMR but typically more subtle ABO mismatch Serum evaluation for DSA Liver biopsy with staining for C4d Retransplant Other rejection Plasma cell rich rejection A manifestation of allograft rejection with positive C4d staining of portal capillaries. Rapid progression of fibrosis resistant to IS. Any time after transplant AP elevation Unknown C4d staining of portal capillaries Retransplant Abbreviations: ACR, acute cellular rejection; ALT, alanine aminotransferase; AMR, antibody-mediated rejection; AP, alkaline phosphatase; AST, aspartate aminotransferase; DSA, donor-specific antigen; IS, immunosuppression; IVIG, intravenous immunoglobulin; LT, liver transplantation; TB, total bilirubin; ULN, upper limit of normal. TABLE 3 - Infectious causes of abnormal liver enzymes after LT Category Diagnosis Findings Timing Pattern Risk factors Evaluation Treatment Viral infections CMV infection Fever, leukopenia, elevated liver enzymes, diarrhea Most common in the first 1–6 mo after transplantation AST/ALT 5–15× ULN Most common in CMV D + /R− combinations Serum CMV PCR Colonoscopy with biopsies PPX: valganciclovir Treatment: valganciclovir HBV (donor-derived or reactivation) Mild elevation in liver enzymes, fever, or asymptomatic Transmission within 3–5 d AST/ALT 1–3× ULN Known infections in donor Day 3 PCR, Day 7 PCR, weekly thereafter Entecavir or Tenofovir for suppression Donor-derived HCV Mild elevation in liver enzymes, fever, or asymptomatic Transmission most commonly 3–5 d, can occur in 3–6 mo AST/ALT 1–3× ULN Known infections in donor Day 3 PCR, Day 7 PCR, weekly thereafter Early initiation of DAA HSV Fever, fatigue, severely elevated liver enzymes, leukopenia; note that rash is not required Most common in the first 3 mo after transplantation AST/ALT 5–15× ULN Most common in new HSV acquisition HSV serum PCR Valacyclovir SARS-CoV-2 Fever, liver injury, upper respiratory symptoms Anytime AST/ALT 1–3× ULN Metabolic syndrome SARS-CoV-2 PCR Monoclonal antibody Remdesivir, prednisone Bacterial infections CDI Diarrhea, fulminant colitis Higher risk in the first 3 mo Elevation in liver enzymes only if severe colitis, dehydration present Exposure to multiple antimicrobial agents, prior CDI C.diff EIA and toxin Fidaxomicin PO Vancomycin Metronidazole Liver abscess Abdominal pain, fevers, intrahepatic collections Anytime Alk phos/ Tbili 5–10× ULN Ischemic injury, bile leak CT or MRI IR drainage and IV antibiotics Ascending cholangitis Abdominal pain, fevers, biliary stricture and biliary dilatation Anytime Alk phos/ Tbili 5–10× ULN Anastomotic stricture MRCP or ERCP ERCP vs percutaneous drainage Cholestasis of sepsis Hypotension, tachycardia, localizing infectious symptoms Anytime Alk phos/ Tbili 5-10x ULN Sepsis of any kind (urinary, SSTI, abscess, PNA) None Treatment of underlying source infection Fungal infections Invasive candidal infections Candidemia (sepsis) line infection, peritonitis, endophthalmitis First 3 mo Typically elevations are associated with cholestasis of sepsis CMV infection Line and blood cultures, fluid culture Fluconazole (mild-moderate infection, CNI interaction) Echinocandin (moderate-severe infection) Aspergillus CT chest: nodular opacity with halo sign, 50% of the time aspergillus becomes invasive First 30 d Typically elevations are associated with cholestasis of sepsis Pretransplant colonization Sputum culture Chest imaging B-D-glucan Galactomannan Voriconazole Endemic Mycoses (Histoplasmosis, Coccidiomycosis, Blastomycosis) Pneumonia, 30% with disseminated disease: hepatosplenomegaly, GI involvement, sepsis First 3 mo Elevation of Tbili/Alk phos related to hepatic parenchymal invasion or cholestasis of sepsis Pretransplant exposure through endemic location or donor-derived infection Serologic testing Cross-sectional imaging Itraconazole Amphotericin B Abbreviations: ALT, alanine aminotransferase; AST, aspartate aminotransferase; CDI, Clostridium Difficile infection; CMV, cytomegalovirus; CNI, calcineurin inhibitor; DAA, direct-acting antiviral; EIA, enzyme immunoassay; ERCP, endoscopic retrograde cholangiopancreatography; GI, gastrointestinal; HSV, Herpes simplex virus; IR, interventional radiology; LT, liver transplantation; MRCP, magnetic resonance cholangiopancreatography; PO, per os; PPX, prophylaxis; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; ULN, upper limit of normal. TIMING OF LIVER ENZYME ELEVATION The length of time since transplant is among the most distinguishing features of post-transplant elevated liver enzymes (Figure 1). Although several complications, such as DILI and infection, can occur at any time, a majority of the presentations occur within a very specific window post-transplant.4 Findings can be categorized as immediate (first week), early (first month), intermediate (1–12 mo), and late complications (>1 y).FIGURE 1: Causes of liver enzyme elevations over the post-transplant period. The causes of liver enzyme elevations post-transplant are shown relative to the time from transplant, during which these causes are most likely to occur. Abbreviations: CMV, cytomegalovirus; HAT, hepatic artery thrombosis; HSV, Herpes simplex virus; IS, immunosuppression; LT, liver transplantation.IMMEDIATE PERIOD (DAYS 0–7) During the first week after the transplant, almost all patients experience a transient elevation in liver enzymes. This is attributed to a combination of operative “preservation injury” and ischemic reperfusion injury – injury to the donor liver resulting from cold and warm ischemic time and vascular reperfusion.5 Classically, preservation injury is an AST/ALT predominant pattern, which rises steadily over ~7 days to 5–20x the ULN, often with a delayed elevation in bilirubin.5 The challenge in the immediate postoperative period is to distinguish preservation injury from other more acute complications requiring urgent intervention: primary nonfunction, hepatic artery thrombosis, biliary complications, and early acute cellular rejection (ACR) (Tables 1, 2). Early Doppler ultrasound to evaluate vascular patency is appropriate in the first 24 hours after transplant and after any acute change in graft function.6 Improving the international normalized ratio distinguishes rising liver enzymes of preservation injury from graft-threatening complications, including primary nonfunction and hepatic artery thrombosis.7 Other immediate complications include biliary leaks, which occur in 2%–25% of patients after transplant.6 An early isolated bilirubin elevation, often in combination with abdominal pain, leukocytosis, and fevers should prompt cross-sectional imaging to look for fluid collections requiring endoscopic or percutaneous drainage. Hemodynamic complications, including bleeding and volume overload, can also lead to mixed elevations in liver enzymes driven by perioperative hypotension, ischemia, and hepatic congestion. In addition, resorption of hematomas and transfusion of red blood cells can result in transient rises in indirect bilirubin that does not reflect allograft dysfunction. Because of the complex physiological changes that occur in the first-week post-transplant, empiric treatment of complications is not uncommon (eg, escalation of glucocorticoids for empiric treatment of ACR). EARLY PERIOD (<1 MONTH) ACR most frequently occurs in the first 30 days after transplant with a mixed elevation in liver enzymes. Liver enzymes that do not decline after the first postoperative week or rise again after a period of improvement should prompt evaluation for ACR with liver biopsy. Attempts to identify serum biomarkers for ACR are in the early stages, and liver biopsy remains the gold standard. A 2022 study by Levitsky et al8 demonstrated the validity of a 59-gene biomarker, which succeeds in distinguishing transplant recipients with acute rejection. Since the introduction of tacrolimus-based regimens, published estimates of the incidence of ACR range from 15% to 45%.4,9,10 A 2016 prospective study by Shindoh et al11 observed a median time to ACR of 17 days (range 5–83 d) after transplantation. Early ACR, most commonly defined as occurring within the first 6 weeks post-transplant, occurs in an estimated 30%–35% of patients.12 Early ACR is treated effectively with a burst of steroids or escalation of immunosuppression (IS).13,14 While initial studies demonstrated that ACR had no impact on patient and graft survival, more recent data refute that assertion. A 2019 study by Jadlowiec et al, however, demonstrated that 17% of patients experienced late ACR episodes after the first 6 weeks post-transplant.12 Episodes of late ACR were associated with a higher rate of chronic rejection and graft failure.15,16 In addition, Levitsky et al10 demonstrated that, in 2 large national databases, biopsy-proven ACR was associated with an increased risk of both graft loss and death in the 12 months after diagnosis. The incidence of ACR is substantially higher in individuals with autoimmune etiology of liver disease, and it is important to recognize that early ACR is not prevented by adequate serum IS levels.4 In patients refractory to treatment, antibody-mediated rejection and plasma-cell–rich rejection should be considered with additional diagnostic testing to include donor-specific antigen testing and C4d liver tissue staining (in addition to routine hematoxylin and eosin liver tissue staining). Because IS takes some time to reach maximum efficacy, the first postoperative month is the highest risk for ACR and lowest risk for opportunistic infections. During the early postoperative period, a majority of infections are bacterial complications of the operation and hospitalization itself: wound infections, acute cholangitis, abdominal fluid collections, urinary infections, and Clostridium difficile colitis.2 Other early complications include anastomotic biliary stricture and obstructive jaundice, with or without acute cholangitis.6 If there is a high degree of suspicion for stricture, cross-sectional imaging with CT or MRI is typically followed by endoscopic retrograde cholangiopancreatography for endoscopic stenting. Some patients may ultimately require revision to roux-en-y anatomy to achieve long-term resolution of obstruction. INTERMEDIATE PERIOD (1–12 MONTHS) Beginning at ~2–3 months post-transplant, antimicrobial prophylaxis and immunosuppressive regimens begin to be weaned. This phase of post-transplant management demands careful attention to the balance between the simultaneous risks of infection and rejection, requiring an individualized approach guided by patient response. Stepwise de-escalation of IS should be combined with careful monitoring of liver enzymes. During this phase, late-onset ACR often occurs in patients who are young, female, or have an autoimmune history.4 In contrast to early ACR, late rejection is associated with immunosuppressive levels and should be suspected if even very mild elevations in liver enzymes develop after a change in immunosuppressive medication dosing. At the same time, the risk of developing an opportunistic infection increases with the tapering of prophylaxis. Viral infections, particularly cytomegalovirus, carry an important risk of activating the host's innate immune response and triggering an episode of ACR. Elevations in liver enzymes during this phase should, therefore, also prompt consideration of cytomegalovirus and other viral infections depending on the clinical context. Candidiasis, aspergillosis, P. jirovecii pneumonia, and endemic mycoses are other important causes of post-transplant opportunistic infection but present typically with pulmonary or tissue-invasive disease and so are less likely to increase a patient’s liver enzymes in the absence of disseminated disease.2 Finding a careful balance between immune-mediated and infectious complications is critical to long-term graft survival Early disease recurrence, particularly NASH, is also common; liver biopsy may be required to distinguish this from rejection. Biliary complications frequently arise during this time period and include both anastomotic and nonanastomotic strictures. LATE PERIOD (>12 MONTHS) After ~12 months post-transplant, elevations in liver enzymes become less common as the patient’s immune response and immunosuppressive dosing stabilize. In patients with chronically low IS, ductopenic rejection causes rising bilirubin with progressive bile duct loss on liver biopsy, often irreversible. Chronic rejection involves the loss of at least 50% of portal tracts and classic foam cell obliterative arteriopathy.15 This type of immune-mediated duct loss is irreversible and occurs in an estimated 2%–5% of transplant recipients.17 Given advances in immunosuppressants, chronic rejection is frequently associated with poor medication adherence and should, therefore, prompt evaluation of medication-related issues, such as access and affordability.15 In addition to rejection, post-transplant alcohol use and weight gain represent a significant risk to allograft function. Studies suggest that about 10% of patients use alcohol heavily after transplant, regardless of whether the patient’s original liver disease was alcohol-associated.18 Elevated liver enzymes of unclear etiology post-transplant should, therefore, prompt additional substance use history and alcohol biomarker testing. It is important to educate patients in advance that both alcohol use and recurrent NASH can cause the rapid development of allograft cirrhosis.19 Autoimmune liver diseases may also reoccur or develop de-novo in a post-transplant patient. Autoantibody testing is not reliable due to IS, so identifying autoimmune liver disease requires a high index of clinical suspicion and judicious use of liver biopsy for confirmation.20 PSC, in particular, is associated with an increased risk of severe recurrence; an estimated 30% of those with recurrent PSC will ultimately require re-transplantation.21 As patients progress into the second and third decades after transplant, the risks of graft dysfunction decrease, allowing for lower levels of IS and reduced frequency of lab monitoring over time. CONCLUSION Liver enzymes provide the most reliable noninvasive method for evaluating clinical status after liver transplantation. Regular monitoring is required throughout the lifetime of a liver transplant recipient. It is critical that clinicians managing post-transplant patients recognize the most common presentations of liver enzyme elevations and the appropriate first steps in evaluation, diagnosis, and treatment to preserve long-term allograft function.

Machine Learning-Based Automated Irrigation for Indoor: Review and a Case Study

Abstract: Smart agriculture is one of the most essential industries. Since fertile land becomes more limited and fresh water is harder to manage, indoor agriculture will become increasingly more important due to the ability to grow anywhere with verticality. Many of the Internet of Things (IoT) systems researched focus on outdoor farming, but completely overlook the need for indoor farming. The purpose is to explore the tools used to develop a smart indoor irrigation system and utilize studies to explore the novelty of our work by reviewing pre-existing IoT irrigation projects. The systems explored range from simple thresholding to well-developed machine learning (ML) models. In this paper, we present a simple IoT system explored before scaling to bigger IoT system. We know that ML-based systems are more robust while outperforming classical computational methods. We found that prototyping is best with the simplest WiFi IoT system and hardware where focus should be on a well-developed ML model.

Incidence of Cochlear Implantation Among Adult Candidates in the United States

Abstract: To investigate the associations of age and year of cochlear implantation (CI) with CI incidence among adults 20 years and older residing in the US.Deidentified cochlear implant data were acquired from prospective patient registries from two cochlear implant manufacturers (Cochlear Americas and Advanced Bionics), which supply an estimated 85% of cochlear implants in the US. Population estimates for severe-to-profound sensorineural hearing loss by age group were extracted from Census and National Health and Nutrition Examination Survey data.US CI centers.Adults 20 years and older who underwent CI.CI.CI incidence.The study cohort included 30,066 adults 20 years and older who underwent CI from 2015 to 2019. When combining actual and estimated data from all three manufacturers, the annual number of cochlear implants increased 5,406 in 2015 to 8,509 in 2019. Overall, the incidence of CI among adult traditional (bilateral severe-to-profound hearing loss) CI candidates increased from 244 per 100,000 person-years in 2015 to 350 in 2019 ( p < 0.001). Although the elderly (80 years and older) population had the lowest incidence of CI, this cohort experienced the largest growth from an incidence of 105 per 100,000 person-years to 202 during the study period.Despite growing incidence among those with qualifying hearing loss, cochlear implants remain widely underutilized. Elderly adults continue to exhibit the lowest relative cochlear implant utilization rates; however, trends over the last half-decade suggest a shift has occurred, resulting in improved access among this underserved subset.

Designing a Shortened Preclinical Basic Science Curriculum: Expert-Derived Recommendations

Abstract: Purpose: To generate an expert-derived list of recommendations for how medical schools should approach decisions about the placement of basic science topics within shortened preclinical curricula, which allow for early clinical immersion. Method: A modified Delphi process was used to develop consensus on recommendations (March–November 2021). The authors performed semistructured interviews with national undergraduate medical education (UME) experts from institutions that previously underwent curricular reforms involving shortened preclinical curricula to elicit perspectives on how decisions were made at their institutions. The authors condensed the findings into a preliminary list of recommendations and distributed this list in 2 survey rounds to a larger group of national UME experts (from institutions that previously underwent curricular reforms or held positions of authority within national UME organizations) to gauge their level of agreement with each recommendation. Recommendations were revised based on participant comments, and those with at least 70% somewhat or strong agreement after the second survey were included in the final comprehensive list of recommendations. Results: Interviews were conducted with 9 participants and resulted in 31 preliminary recommendations that were then sent via survey to the 40 recruited participants. Seventeen/40 (42.5%) participants completed the first survey, after which 3 recommendations were removed, 5 were added, and 5 were revised based on comments—resulting in 33 recommendations. Twenty-two/38 (57.9%) participants responded to the second survey, after which all 33 recommendations met inclusion criteria. The authors removed 3 recommendations that did not directly address the curriculum reform process and consolidated the final 30 recommendations into 5 succinct, actionable takeaways. Conclusions: This study generated 30 recommendations (summarized by the authors in 5 succinct takeaways) for medical schools designing a shortened preclinical basic science curriculum. These recommendations reinforce the importance of vertically integrating basic science instruction with explicit clinical relevance into all curricular phases.

Lipid mediators in the regulation of innate and adaptive immunity

Abstract: Life depends on lipids as the major structural components of membranes. Lipids are also crucial sources of energy in animals and humans. Fascinatingly, lipids have a diversity of additional roles in the immune system that range from acting as intercellular and intracellular signaling molecules to being modulators of membrane protein function, which influences tissue physiology in health and disease. How lipids are processed and metabolized has significant impact on cell and tissue function. In this issue of the journal, a series of reviews highlight the diverse ways lipids have been shown to serve as modulators of immunity. Murakami et al.1 provide a comprehensive overview of secreted phospholipase A2 (sPLA2) family members, which hydrolyze phospholipids at the sn-2 position to produce lysophospholipids and fatty acids. These liberated fatty acids are often further modified to produce bioactive lipids such as eicosanoids, prostaglandins (PGs) (also see the review in this issue by Honda et al.), and leukotrienes (also see the review in this issue by Yokomizo and Shimizu) that further influence immunity in diverse manners. These phospholipid substrates are not only found in plasma membranes but also include phospholipids present in extracellular vesicles, microbial membranes, surfactants, and dietary phospholipids. The review begins with general considerations of sPLA2 biology and then focuses on individual classical sPLA2 families. The authors include findings from mouse models of over-expression as well as genetically engineered deficiencies in specific sPLA2 family members, and considers the defined (and potential) physiological and pathophysiological contributions of sPLA2 family members to immunity. Importantly, the authors address the dual positive/negative nature of many sPLA2 activities. Beyond their roles in immunity, the authors highlight the participation of individual sPLA2s to pain, fertility, cardiovascular disease, cancer, and obesity, as well as providing a current account of sPLA2 inhibitors under investigation. As such, this review will be a valuable resource for an immunological audience. The importance of PGs in inflammation is widely appreciated because of the activities of nonsteroidal anti-inflammatory drugs (NSAIDs) that inhibit the cyclooxygenase (COX) enzymes needed for PG production. However, the full details of PG and PG receptor biology are still being elucidated. In their review, Honda et al.2 explore the broad functions of PGs and a related set of arachidonic acid derived mediators, leukotrienes (LTs), in tissue physiology and disease. They describe the enzymes involved in PG and LT synthesis, and the 13 GPCRs that they engage. The authors then provide an in-depth description of the multiple contributions of PGs and LTs to events associated with skin inflammation. This includes promoting dendritic cell (DC) migration, promoting neutrophil and eosinophil recruitment, augmenting effector T cell differentiation in draining lymph nodes, and contributing to skin-associated lymphoid tissue (iSALT) formation. The multi-faceted influences of PGs and LTs on the development of atopic dermatitis, a Type 2 immune hypersensitivity condition, and in psoriasis, a Th17-associated condition, are discussed. PGs and LTs are derived from omega-6 fatty acids (unsaturated bond at the sixth position in the hydrocarbon chain). Honda et al. also review skin immune functions of the less studied omega-3 fatty acid-derived metabolites. Both omega-6 and omega-3 fatty acids are essential fatty acids that mammals must acquire from their diet. The authors review the suppressive influence of certain omega-3 fatty acid metabolites on allergic dermatitis. In the case of one set of metabolites, these actions are mediated by GPR40, and for another, retinoid X receptor alpha (RXRa), a nuclear receptor that is further discussed in the review by Czimmerer and Nagy. They end on the topic of how dietary saturated fatty acids (SFAs) can influence psoriatic inflammation, discussing connections between high-fat diets (that are rich in SFAs) and elevated IL-17 responses. In summary, this review provides a rich description of current knowledge of the actions of omega-6, omega-3, and unsaturated fatty acid-derived metabolites in the immune system, helping the reader parse conditions where their actions may be inflammatory versus resolving. The next review by Yokomizo and Shimizu3 in this issue focuses on one class of LT, LTB4, and receptors BLT1 and BLT2. This review is from the investigators who first cloned BLT1 and BLT2 as high- and low-affinity LTB4 receptors, and the reader is provided with an in-depth historical perspective of these discoveries. The cloning of BLT1 using a subtractive hybridization approach was a landmark study, and BLT1 is now widely known as a prominent chemotactic receptor, especially on neutrophils. This article explains that while BLT2 was identified as a second LTB4 receptor, the low affinity for LTB4 led these investigators and their coworkers to assume there would be other higher affinity ligands for BLT2. Screening of lipid libraries led to their identification of 12-hydroxyheptadecatrienoic acid (12-HHT) as a high affinity ligand. The biosynthetic pathways of LTB4 and 12-HHT from arachidonic acid are detailed, with LTB4 production depending on 5-lipoxygenase (5-LO) while 12-HTT requires COX enzymes. This review provides a helpful summary of LTB4 actions in asthma, bone resorption, arthritis, and atherosclerosis, and more broadly in the immune and nervous systems. The actions in asthma are of disease significance in humans since a 5-lipoxygenase (5-LO) inhibitor is approved as an anti-asthma therapeutic. The authors describe platelet production of large amounts of 12-HHT, adding to the many other mediators released by activated platelets, as summarized in the review by De Giovanni et al. 12-HHT in damaged skin acts on BLT2 in keratinocytes to promote wound repair. The authors also detail their recent discovery of BLT1 as a sub-setting marker for DCs with different migration properties. They conclude with a discussion of the status of preclinical and clinical trials of LTB4 receptor antagonists for treatment of inflammatory disease, and speculation that the newly available structure of BLT1 should enable development of improved therapeutic agents. A fundamental mechanism by which lipids impact immune function is by influencing structural and metabolic properties of immune cells. A prominent lipid of this class is cholesterol, which makes up approximately 20% of the plasma membrane and undergoes interactions with many plasma membrane proteins, including T and B cell antigen receptors (TCR and BCR). Cholesterol is one of the products of the mevalonate pathway and Kennewick and Bensinger,4 provide a concise introduction to this pathway and the functions of key products, including how cholesterol abundance may be altered in different T cell states to influence the organization of signaling molecules, and to allosterically regulate TCR triggering. They explain the tight regulatory control that exists over flux through the mevalonate pathway and its branches. Crucial products of one branch of the pathway are isoprenoids, including farnesyl pyrophosphate and geranylgeranyl pyrophosphate. These hydrocarbon chains are attached to many of the small GTP-binding proteins in cells, and some other membrane-associated proteins. Their highly controlled availability is crucial for proper immune cell function. Kennewick and Bensinger detail the key activity of sterol regulatory element-binding proteins (SREBPs) in driving transcription of mevalonate pathway enzymes, and how SREBP activity is controlled by negative feedback mediated by cholesterol and cholesterol metabolites. The role of SREBPs downstream of the mTOR complex in supporting the anabolic needs of activated T cells is discussed. Fascinatingly, they detail how enzymes distal in the cholesterol synthetic branch, such as those involved in isoprenoid production, are not SREBP regulated and are controlled by other still poorly defined mechanisms. The authors present a discussion of the flux diversion hypothesis of Faust, Goldstein and Brown, exploring how immune cells can differentially adjust outputs of the mevalonate pathway depending on product requirements. In a further section, the authors describe the amplified importance of flux through the mevalonate pathway in activated compared to quiescent lymphocytes, as perhaps first revealed most clearly through the Bensinger lab's study of SCAP-deficient T cells. This review provides a great entry point for anyone interested in understanding how the mevalonate pathway impinges on T cell biology, and immunology more generally. Lipid droplets (LDs) are major lipid storage organelles present in most cells. Their presence often reflect cellular metabolic and nutrient status. Accordingly, many pathogens have evolved mechanisms to induce LD formation and exploit their lipid content for colonization. Conversely, LDs have also been shown to possess antibiotic activity and thus can serve both beneficial and detrimental roles towards diverse pathogens. The Safi et al.5 review provides a fascinating and comprehensive account of LD organelles and their dynamic remodeling and interaction with pathogens. Notably, this review emphasizes the emerging consideration that LDs are a potential strategic chokepoint for organizing a defensive line against certain pathogens. Accordingly, the authors categorize LDs into defensive LDs (d-LDs) and fasting-LDs (f-LDs) to signify LDs that act to subvert pathogens, versus LDs that serve as a source of lipid energy and contribute to cell metabolism. Pulmonary surfactants are important complexes of lipid and protein produced by Type II alveolar epithelial cells that regulate alveoli surface tension thus preventing lung collapse. The review by Numata et al.6 provides a detailed account of work by this team over the last dozen years defining anti-inflammatory and anti-viral properties by the specific pulmonary surfactant lipids, palmitoyl-oleoyl phosphatidylglycerol and phosphatidylinositol. More precisely, this review covers in vitro experiments with cell lines and primary human cells, demonstrating the ability of these surfactant phospholipids to potently inhibit TLR signaling and proinflammatory cytokine production. They also discuss in vivo mouse (and ferret) models that show the ability of these lipids to limit viral infections. Notably, the authors highlight the strong rationale for the need for novel therapeutics to address acute respiratory distress syndrome and viral infections (RSV, influenza A and SARS-CoV-2) and provide compelling evidence that these pulmonary surfactant lipids may provide one avenue to reach this goal. Another mode of lipid action in the immune system is via engagement of nuclear hormone receptors. Czimmerer and Nagy7 review this topic with a particular focus on their studies of gene regulation in macrophages mediated by retinoid X receptor (RXR) heterodimerizing receptors. They point out that while some nuclear hormone receptors are activated by high-affinity ligands such as all-trans retinoic acid for RARs and vitamin D3 for VDR, others have low affinity and more promiscuous binding of lipid classes including oxysterols for liver X receptors (LXRs), fatty acids for Peroxisome Proliferator Activated Receptors (PPARs), and bile acids for farnesoid X receptors (FXRs). Complexes bound without ligand are explained to interact with corepressor complexes and repress transcription, while ligand binding induces corepressor-coactivator exchange leading to transcription activation. Moreover, they highlight how next-generation sequencing-based methods have greatly expanded understanding of the binding sites for RXR heterodimers. They explain how their findings indicate the RXR cistrome in macrophages may not be regulated by exogenous ligands. Their review then focuses on an IL-4 orchestrated STAT6, EGR1, and PPARy containing transcription factor network that controls gene expression in macrophages, driving alternative (Type-2) polarization. The important role of PPARγ in macrophage polarization is reviewed and it is proposed that rather than acting as sensors of the extracellular or intracellular lipid microenvironment, PPARγ/RXR heterodimers may act as epigenetic bookmarking factors. This review gives the reader a framework for considering when a nuclear hormone receptor regulated cell behavior may be lipid ligand-dependent versus independent. The review by De Giovanni et al.8 focuses on the function of the receptor, GPR35, in the immune system. GPR35 has been suggested to respond to a diverse group of ligands, including lipids, though the best validated ligands are tryptophan metabolites, including kynurenic acid (KynA) and 5-hydroxyindoleacetic acid (5-HIAA). GPR35 is highly expressed by activated neutrophils and it supports migration and adhesion of these cells in response to 5-HIAA. The authors summarize their work providing evidence that 5-HIAA release by activated platelets and mast cells cooperates in promoting neutrophil transmigration from blood into inflamed tissue. Zooming out, they summarize the broader contributions of platelets and mast cells, and the wide diversity of mediators they release to neutrophil recruitment. Since 5-HIAA is a breakdown product of serotonin, De Giovanni et al. provide a concise review of ways in which serotonin from activated platelets and mast cells engages with the vasculature and likely other cell types to augment cell recruitment and inflammatory events. They also summarize the surprisingly diverse set of actions that have been reported for GPR35 in tissues ranging from the epithelium to the heart to neurons. This review also makes clear that while genetic studies have provided support for 5-HIAA as a ligand for GPR35, the receptor has a broad ligand binding profile, and there are sure to be additional physiologically relevant ligands, likely including some made by the microbiome. In summary, this review will be useful to readers interested in GPR35 and 5-HIAA biology, and in platelet and mast cell actions during cell recruitment to sites of inflammation. In the review by Yaginuma et al.,9 the authors provide an overview of bioactive lysophospholipids and their G-protein coupled receptors (GPCRs) with a particular emphasis on the described roles of lysophosphatidylserine-(LysoPS) induced GPCR signaling in immune modulation. This balanced review includes a general overview of (the often varied) routes of lysophospholipid synthesis and the phospholipases that contribute to their production. The authors nicely introduce and discuss the concept that lysophospholipid activity as a lipid mediator is typically autocoidal and is distinguished from, for example, S1P activity, which acts more hormone-like due to higher constitutive concentrations of S1P compared to the other lysophospholipids. Finally, the authors report interesting findings that include analysis of RNAseq data highlighting the LysoPS GPCRs that are expressed by different immune cell populations under homeostatic conditions. They further provide a general analysis of CD4 T cell and B cell numbers after immunization in wild-type and mouse strains deficient in either Lps1/Gpr34, Lps2/P2y10, or Lps3 Gpr174. These latter findings suggest that Lps1/GPR34 may positively regulate lymphocyte activation whereas Lps2/P2Y10 may play a negative role. In summary, this review summarizes the current understanding on lysophospholipid GPCR signaling with an emphasis on LysoPS and its Lps1, Lps2, and Lps3 cognate receptors and will be useful for an immunological audience. The review by Torres et al.10 provides an overview of the work by this group characterizing how lysophosphatidic acid (LPA) signaling via the LPA5 GPCR inhibits T and B lymphocyte function. Starting with their initial observation that LPA can suppress TCR and BCR-induced calcium release from intracellular stores, the authors review their biochemical and cell biological studies that identify the LPA5 signaling axis as not only interfering with TCR-induced IP3 receptor-mediated intracellular calcium release but also CD8 T cell—target cell immunological synapse formation. The ability of endogenous systemic levels of LPA to signal in vivo via LPA5 to impede lymphocyte function is demonstrated in several contexts including cytotoxic CD8 T cell antigen-specific killing of target cells and, importantly, melanoma tumors in a mouse model. More recent observations covered in this review include results revealing that LPA-LPA5 signaling also rewires cytotoxic CD8 T cell metabolic activity to promote fatty acid oxidation. Thus showing that LPA5 can also influence T cell function independent of regulating TCR signaling. Finally, the authors present provocative findings that implicate plasma LPA levels as prognostic for successful immune checkpoint blockade therapy. From our initial understanding almost two decades ago that S1PR1 was essential for thymocytes to exit the thymus and join the peripheral pool of mature antigen-responsive T cells, there has been great interest in better understanding how the sphingosine-1-phosphate lysophospholipid and its cognate S1P GPCRs orchestrate immune cell trafficking and migration in health and disease. In their review, Hallisey and Schwab11 provide an update on key areas in S1P biology as they relate to T cell trafficking in and out of lymphoid and non-lymphoid organs not only in homeostasis but particularly during inflammatory settings. This review includes a thoughtful consideration on the implications of altered T cell trafficking in lymphoid organs for T cell immunity. Notably, the authors highlight interesting work from their laboratory on the regulation of S1PR1 expression by T cells and formation of S1P gradients noting areas that still require a more thorough understanding. DCs are a key cell type that serves to communicate between the innate and adaptive arms of immunity. Important DC functions that encompass development, activation and homeostasis are regulated by the metabolism of lipids, and specifically fatty acid synthesis, oxidation and storage. In their contribution, You and Chi12 begin with a description of DC subset classification and activity, and proceed to provide a comprehensive review and account of fatty acid metabolism and lipid metabolites as they relate to in vitro and in vivo DC differentiation and function. Notably, this review of the literature focuses on the role of fatty acid and cholesterol metabolism in DC biology highlighting consistencies and discrepancies between different published studies and models. Areas of lipid biology that need further clarification and resolution with regard to DC function are also discussed. The authors declare no competing interests. Data sharing is not applicable to this article as no new data were created or analyzed in this study.

Data from Systemic Chemotherapies Retain Antitumor Activity in Desmoid Tumors Independent of Specific Mutations in &lt;i&gt;CTNNB1&lt;/i&gt; or &lt;i&gt;APC&lt;/i&gt;: A Multi-institutional Retrospective Study

Abstract: <div>AbstractPurpose:<p>Determine whether specific <i>CTNNB1</i> or <i>APC</i> mutations in patients with desmoid tumor were associated with differences in clinical responses to systemic treatments.</p>Experimental Design:<p>We established a multi-institutional dataset of previously treated patients with desmoid tumor across four U.S. sarcoma centers, including demographic and clinicopathologic characteristics, treatment regimens, and clinical and radiographic responses. <i>CTNNB1</i> or <i>APC</i> mutation status was determined from prior pathology records, or archival tissue was requested and analyzed by Sanger sequencing and/or next-generation sequencing. Evaluable patients with mutation results were analyzed to determine clinical progression-free survival (cPFS), RECIST 1.1 PFS (rPFS), time to next treatment (TTNT), and overall survival (OS). Kaplan–Meier analysis and Cox proportional hazards regression were performed to identify differences in cPFS, rPFS, TTNT, and OS by mutation subtype, desmoid tumor location, and treatment regimen.</p>Results:<p>A total of 259 evaluable patients were analyzed for at least one of the survival outcomes, with 177 patients having mutation data. First- and second-line cPFS, rPFS, and TTNT were not significantly affected by mutation subtype; however, <i>APC</i>-mutant desmoid tumors demonstrated nonstatistically significant inferior outcomes. Extremity/trunk desmoid tumor location and treatment with doxorubicin-based, methotrexate/vinca alkaloids and sorafenib regimens were associated with better clinical outcomes compared with surgery or “other” therapies, including estrogen-receptor blockade and imatinib. OS was significantly worse with <i>APC</i> or <i>CTNNB1</i> negative/other mutations.</p>Conclusions:<p>Mutation subtype did not affect responses to specific systemic therapies. <i>APC</i> mutations and nonextremity desmoid tumor locations remain prognostic for worse outcomes, and earlier initiation of systemic therapy for these higher-risk desmoid tumors should be prospectively evaluated.</p><p><i><a href="https://aacrjournals.org/clincancerres/article/doi/10.1158/1078-0432.CCR-22-0620" target="_blank">See related commentary by Greene and Van Tine, p. 3911</a></i></p></div>

Analysis of Postoperative Complications Related to Cannabis and Tobacco Usage in Patients Undergoing Mandible Facial Fracture Surgeries

Abstract: Background Cannabis is the third most used controlled substance in the world. Despite its widespread use, there is minimal research investigating cannabis usage in patients undergoing facial fracture surgeries. The purpose of this study was to evaluate patterns of postoperative complications related to cannabis and tobacco usage following mandible fracture surgeries. Materials and Methods PearldiverTM, a commercially available healthcare database, was used to identify patients endorsing use of cannabis, tobacco, or both who underwent mandible fracture surgeries for a cross-sectional analysis. The study population was categorized into groups using ICD-9, ICD-10, and CPT codes. A chi-square analysis was performed to assess the influence of cannabis and tobacco use on postoperative complications. Results A total of 8,288 patients met inclusion criteria with 72 patients with cannabis only diagnosis, 914 patients with cannabis and tobacco diagnosis, 3,236 patients with tobacco only diagnosis, and 4,066 in the control group. For patients with cannabis only diagnosis, there was not an increased risk of developing post operative complications compared to the control population. Patients with a concurrent cannabis and tobacco diagnoses, as well as those with tobacco only diagnosis had in increased risk of developing surgical site infection, facial nonunion, facial abscess, debridement, and malocclusion following surgical repair of mandibular facial fracture. Conclusion A tobacco only, as well as, a cannabis and tobacco diagnosis caused an increased risk of all complications, except malocclusion, compared to a cannabis only diagnosis. Based on the results of this study, it is recommended that healthcare providers consider a patient's history of tobacco use when planning and performing surgical treatment for traumatic mandible fractures. Cannabis is the third most used controlled substance in the world. Despite its widespread use, there is minimal research investigating cannabis usage in patients undergoing facial fracture surgeries. The purpose of this study was to evaluate patterns of postoperative complications related to cannabis and tobacco usage following mandible fracture surgeries. PearldiverTM, a commercially available healthcare database, was used to identify patients endorsing use of cannabis, tobacco, or both who underwent mandible fracture surgeries for a cross-sectional analysis. The study population was categorized into groups using ICD-9, ICD-10, and CPT codes. A chi-square analysis was performed to assess the influence of cannabis and tobacco use on postoperative complications. A total of 8,288 patients met inclusion criteria with 72 patients with cannabis only diagnosis, 914 patients with cannabis and tobacco diagnosis, 3,236 patients with tobacco only diagnosis, and 4,066 in the control group. For patients with cannabis only diagnosis, there was not an increased risk of developing post operative complications compared to the control population. Patients with a concurrent cannabis and tobacco diagnoses, as well as those with tobacco only diagnosis had in increased risk of developing surgical site infection, facial nonunion, facial abscess, debridement, and malocclusion following surgical repair of mandibular facial fracture. A tobacco only, as well as, a cannabis and tobacco diagnosis caused an increased risk of all complications, except malocclusion, compared to a cannabis only diagnosis. Based on the results of this study, it is recommended that healthcare providers consider a patient's history of tobacco use when planning and performing surgical treatment for traumatic mandible fractures.

Coarse particulate matter air quality in East Asia: implications for fine particulate nitrate

Abstract: Abstract. Air quality network data in China and South Korea show very high year-round mass concentrations of coarse particulate matter (PM), as inferred by difference between PM10 and PM2.5. Coarse PM concentrations in 2015 averaged 52 μg m-3 in the North China Plain (NCP) and 23 μg m-3 in the Seoul Metropolitan Area (SMA), contributing nearly half of PM10. Strong daily correlations between coarse PM and carbon monoxide imply a dominant source from anthropogenic fugitive dust. Coarse PM concentrations in the NCP and the SMA decreased by 21 % from 2015 to 2019 and further dropped abruptly in 2020 due to COVID-19 reductions in construction and vehicle traffic. Anthropogenic coarse PM is generally not included in air quality models but scavenges nitric acid to suppress the formation of fine particulate nitrate, a major contributor to PM2.5 pollution. GEOS-Chem model simulation of surface and aircraft observations from the KORUS-AQ campaign over the SMA in May–June 2016 shows that consideration of anthropogenic coarse PM largely resolves the previous model overestimate of fine particulate nitrate. The effect is smaller in the NCP which has a larger excess of ammonia. Model sensitivity simulations show that decreasing anthropogenic coarse PM over 2015–2019 directly increases PM2.5 nitrate in summer, offsetting half the effect of other emission controls, while in winter it increases the sensitivity of PM2.5 nitrate to ammonia and sulfur dioxide emissions. Decreasing coarse PM helps to explain the flat wintertime PM2.5 nitrate trends observed in the NCP and the SMA despite decreases in nitrogen oxides and ammonia emissions. The continuing decrease of coarse PM from abating fugitive dust pollution will require more stringent nitrogen oxides and ammonia emission controls to successfully decrease PM2.5 nitrate.