Showing papers by "Charlie Norwood VA Medical Center published in 2017"

NADPH oxidase in brain injury and neurodegenerative disorders.

Abstract: Oxidative stress is a common denominator in the pathology of neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis, and multiple sclerosis, as well as in ischemic and traumatic brain injury. The brain is highly vulnerable to oxidative damage due to its high metabolic demand. However, therapies attempting to scavenge free radicals have shown little success. By shifting the focus to inhibit the generation of damaging free radicals, recent studies have identified NADPH oxidase as a major contributor to disease pathology. NADPH oxidase has the primary function to generate free radicals. In particular, there is growing evidence that the isoforms NOX1, NOX2, and NOX4 can be upregulated by a variety of neurodegenerative factors. The majority of recent studies have shown that genetic and pharmacological inhibition of NADPH oxidase enzymes are neuroprotective and able to reduce detrimental aspects of pathology following ischemic and traumatic brain injury, as well as in chronic neurodegenerative disorders. This review aims to summarize evidence supporting the role of NADPH oxidase in the pathology of these neurological disorders, explores pharmacological strategies of targeting this major oxidative stress pathway, and outlines obstacles that need to be overcome for successful translation of these therapies to the clinic.

The MLL1-H3K4me3 Axis-Mediated PD-L1 Expression and Pancreatic Cancer Immune Evasion.

Abstract: Background: Pancreatic cancer is one of the cancers where anti-PD-L1/PD-1 immunotherapy has been unsuccessful. What confers pancreatic cancer resistance to checkpoint immunotherapy is unknown. The aim of this study is to elucidate the underlying mechanism of PD-L1 expression regulation in the context of pancreatic cancer immune evasion. Methods: Pancreatic cancer mouse models and human specimens were used to determine PD-L1 and PD-1 expression and cancer immune evasion. Histone methyltransferase inhibitors, RNAi, and overexpression were used to elucidate the underlying molecular mechanism of PD-L1 expression regulation. All statistical tests were two-sided. Results: PD-L1 is expressed in 60% to 90% of tumor cells in human pancreatic carcinomas and in nine of 10 human pancreatic cancer cell lines. PD-1 is expressed in 51.2% to 52.1% of pancreatic tumor–infiltrating cytotoxic T lymphocytes (CTLs). Tumors grow statistically significantly faster in FasL-deficient mice than in wild-type mice (P = .03–.001) and when CTLs are neutralized (P = .03– Conclusions: The Fas-FasL/CTLs and the MLL1-H3K4me3-PD-L1 axis play contrasting roles in pancreatic cancer immune surveillance and evasion. Targeting the MLL1-H3K4me3 axis is an effective approach to enhance the efficacy of checkpoint immunotherapy against pancreatic cancer.

JAK-STAT-mediated chronic inflammation impairs cytotoxic T lymphocyte activation to decrease anti-PD-1 immunotherapy efficacy in pancreatic cancer

Abstract: Human pancreatic cancer does not respond to immune check point blockade immunotherapy. One key feature of pancreatic cancer is the association between its progression and chronic inflammation. Emerging evidence supports a key role for the JAK-STAT pathway in pancreatic cancer inflammation. We aimed at testing the hypothesis that sustained JAK-STAT signaling suppresses cytotoxic T lymphocyte (CTL) activation to counteract anti-PD-1 immunotherapy-induced CTL activity in pancreatic cancer. We show that human pancreatic carcinomas express high level of PD-L1 and exhibit low level of CTL infiltration. JAK-STAT inhibitor Ruxolitinib selectively inhibits STAT1 and STAT3 activation and increases CTL infiltration to induce a Tc1/Th1 immune response in the tumor microenvironment in an orthotopic pancreatic cancer mouse model. Ruxilitinib-mediated tumor suppressive efficacy diminishes in T-cell-deficient mice. Pancreatic tumor grows significantly faster in IFNγ-deficient mice. However, neutralizing IFNγ does not alter tumor growth but diminishes Ruxolitinib-induced tumor suppression in vivo, indicating that lymphocytes and IFNγ are essential for Ruxolitinib-induced host antitumor immune response. Both type I and type II interferons upregulate PD-L1 expression through the JAK-STAT signaling pathway in mouse pancreatic tumor cells. Tumor cells respond to activated T cells by activating STAT3. The inhibition of STAT3 downregulates immune suppressive cytokines production by tumor cells, resulting in increased T cell activation and effector function. Consequently, Ruxolitinib significantly improves the efficacy of anti-PD-1 immunotherapy. Our data demonstrate that Ruxolitinib is effective in the inhibition of systemic inflammation in the tumor microenvironment and therefore upregulates CTL infiltration and activation to overcome pancreatic cancer resistance to anti-PD-1 immunotherapy.

NADPH Oxidase 2 Regulates NLRP3 Inflammasome Activation in the Brain after Traumatic Brain Injury

Abstract: Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. After the initial primary mechanical injury, a complex secondary injury cascade involving oxidative stress and neuroinflammation follows, which may exacerbate the injury and complicate the healing process. NADPH oxidase 2 (NOX2) is a major contributor to oxidative stress in TBI pathology, and inhibition of NOX2 is neuroprotective. The NLRP3 inflammasome can become activated in response to oxidative stress, but little is known about the role of NOX2 in regulating NLRP3 inflammasome activation following TBI. In this study, we utilized NOX2 knockout mice to study the role of NOX2 in mediating NLRP3 inflammasome expression and activation following a controlled cortical impact. Expression of NLRP3 inflammasome components NLRP3 and apoptosis-associated speck-like protein containing a CARD (ASC), as well as its downstream products cleaved caspase-1 and interleukin-1β (IL-1β), was robustly increased in the injured cerebral cortex following TBI. Deletion of NOX2 attenuated the expression, assembly, and activity of the NLRP3 inflammasome via a mechanism that was associated with TXNIP, a sensor of oxidative stress. The results support the notion that NOX2-dependent inflammasome activation contributes to TBI pathology.

Hypoxia, HIF, and Associated Signaling Networks in Chronic Kidney Disease

Abstract: The pathogenesis of chronic kidney disease (CKD) is complex and apparently multifactorial. Hypoxia or decrease in oxygen supply in kidney tissues has been implicated in CKD. Hypoxia inducible factors (HIF) are a small family of transcription factors that are mainly responsive to hypoxia and mediate hypoxic response. HIF plays a critical role in renal fibrosis during CKD through the modulation of gene transcription, crosstalk with multiple signaling pathways, epithelial-mesenchymal transition, and epigenetic regulation. Moreover, HIF also contributes to the development of various pathological conditions associated with CKD, such as anemia, inflammation, aberrant angiogenesis, and vascular calcification. Treatments targeting HIF and related signaling pathways for CKD therapy are being developed with promising clinical benefits, especially for anemia. This review presents an updated analysis of hypoxia response, HIF, and their associated signaling network involved in the pathogenesis of CKD.

SETD1B Activates iNOS Expression in Myeloid-Derived Suppressor Cells.

Abstract: Inducible nitric oxide synthase (iNOS) generates nitric oxide (NO) in myeloid cells that acts as a defense mechanism to suppress invading microorganisms or neoplastic cells. In tumor-bearing mice, elevated iNOS expression is a hallmark of myeloid-derived suppressor cells (MDSC). MDSCs use NO to nitrate both the T-cell receptor and STAT1, thus inhibiting T-cell activation and the antitumor immune response. The molecular mechanisms underlying iNOS expression and regulation in tumor-induced MDSCs are unknown. We report here that deficiency in IRF8 results in diminished iNOS expression in both mature CD11b+Gr1− and immature CD11b+Gr1+ myeloid cells in vivo. Strikingly, although IRF8 was silenced in tumor-induced MDSCs, iNOS expression was significantly elevated in tumor-induced MDSCs, suggesting that the expression of iNOS is regulated by an IRF8-independent mechanism under pathologic conditions. Furthermore, tumor-induced MDSCs exhibited diminished STAT1 and NF-κB Rel protein levels, the essential inducers of iNOS in myeloid cells. Instead, tumor-induced MDSCs showed increased SETD1B expression as compared with their cellular equivalents in tumor-free mice. Chromatin immunoprecipitation revealed that H3K4me3, the target of SETD1B, was enriched at the nos2 promoter in tumor-induced MDSCs, and inhibition or silencing of SETD1B diminished iNOS expression in tumor-induced MDSCs. Our results show how tumor cells use the SETD1B–H3K4me3 epigenetic axis to bypass a normal role for IRF8 expression in activating iNOS expression in MDSCs when they are generated under pathologic conditions. Cancer Res; 77(11); 2834–43. ©2017 AACR.

Activation of Myeloid TLR4 Mediates T Lymphocyte Polarization after Traumatic Brain Injury

Abstract: Traumatic brain injury (TBI) is a major public health issue, producing significant patient mortality and poor long-term outcomes. Increasing evidence suggests an important, yet poorly defined, role for the immune system in the development of secondary neurologic injury over the days and weeks following a TBI. In this study, we tested the hypothesis that peripheral macrophage infiltration initiates long-lasting adaptive immune responses after TBI. Using a murine controlled cortical impact model, we used adoptive transfer, transgenic, and bone marrow chimera approaches to show increased infiltration and proinflammatory (classically activated [M1]) polarization of macrophages for up to 3 wk post-TBI. Monocytes purified from the injured brain stimulated the proliferation of naive T lymphocytes, enhanced the polarization of T effector cells (TH1/TH17), and decreased the production of regulatory T cells in an MLR. Similarly, elevated T effector cell polarization within blood and brain tissue was attenuated by myeloid cell depletion after TBI. Functionally, C3H/HeJ (TLR4 mutant) mice reversed M1 macrophage and TH1/TH17 polarization after TBI compared with C3H/OuJ (wild-type) mice. Moreover, brain monocytes isolated from C3H/HeJ mice were less potent stimulators of T lymphocyte proliferation and TH1/TH17 polarization compared with C3H/OuJ monocytes. Taken together, our data implicate TLR4-dependent, M1 macrophage trafficking/polarization into the CNS as a key mechanistic link between acute TBI and long-term, adaptive immune responses.

Screening for lipoprotein receptor-related protein 4-, agrin-, and titin-antibodies and exploring the autoimmune spectrum in myasthenia gravis.

Abstract: In autoimmune myasthenia gravis (MG), the identification of antibodies and characterization of serological subgroups is of great importance for diagnosis and management of the disease Our aims were to study the frequency of antibodies against lipoprotein-related protein 4 (LRP4), agrin, and titin using the most recent techniques, and to characterize corresponding clinical features and autoimmune diseases (AID) in 100 MG-patients The antibody frequencies in the 55 AChR-antibody positive patients were 7% LRP4, 5% agrin, 53% titin, and in the 45 AChR-antibody negative patients 2% MuSK, 2% LRP4, 2% agrin, and 27% titin LRP4-MG presented late-onset age, mild symptoms, good therapeutic response, and no thymic changes Agrin-MG showed early onset age, mild-to-severe symptoms, and moderate treatment response The phenotype of titin-MG depended on AChR-antibodies: AChR-antibody negative patients presented with mostly mild limb muscle weakness, whereas AChR-antibody positive patients showed more frequently severe symptoms, including myasthenic crisis, bulbar predominance, and thymoma Additional AID were detected in 32% of MG-patients, most frequently Hashimoto's thyroiditis (21%) Based on our data, we recommend the detection of LRP4-antibodies for at least AChR-antibody negative MG-patients and titin-antibodies for all MG-patients We propose taking an accurate medical history for typical symptoms of Hashimoto's thyroiditis in MG-patients

Epigenetic regulation of ganglioside expression in neural stem cells and neuronal cells

Abstract: The structural diversity and localization of cell surface glycosphingolipids (GSLs), including gangliosides, in glycolipid-enriched microdomains (GEMs, also known as lipid rafts) render them ideally suited to play important roles in mediating intercellular recognition, interactions, adhesion, receptor function, and signaling. Gangliosides, sialic acid-containing GSLs, are most abundant in the nerve tissues. The quantity and expression pattern of gangliosides in brain change drastically throughout development and these changes are mainly regulated through stage-specific expression of glycosyltransferase genes. We previously demonstrated for the first time that efficient histone acetylation of the glycosyltransferase genes in mouse brain contributes to the developmental alteration of ganglioside expression. We further demonstrated that acetylation of histones H3 and H4 on the N-acetylgalactosaminyltransferase I (GalNAcT, GA2/GM2/GD2/GT2-synthase; B4galnt1) gene promoter resulted in recruitment of trans-activation factors. In addition, we showed that epigenetic activation of the GalNAcT gene was detected and accompanied by an apparent induction of neuronal differentiation of neural stem cells (NSCs) responding to an exogenous supplement of ganglioside GM1. Most recently, we found that nuclear GM1 binds with acetylated histones on the promoters of the GalNAcT as well as on the NeuroD1 genes in differentiated neurons. Here, we will introduce epigenetic regulation of ganglioside synthase genes in neural development and neuronal differentiation of NSCs.

Ventral hippocampal neurons inhibit postprandial energy intake.

Abstract: Evidence suggests that the memory of a recently ingested meal limits subsequent intake. Given that ventral hippocampal (vHC) neurons are involved in memory and energy intake, the present experiment tested the hypothesis that vHC neurons contribute to the formation of a memory of a meal and inhibit energy intake during the postprandial period. We tested (1) whether pharmacological inactivation of vHC neurons during the period following a sucrose meal, when the memory of the meal would be undergoing consolidation, accelerates the onset of the next sucrose meal and increases intake and (2) whether sucrose intake increases vHC expression of the synaptic plasticity marker activity-regulated cytoskeletal-associated protein (Arc). Adult male Sprague-Dawley rats were trained to consume a 32% sucrose solution daily at the same time and location. On the experimental day, the rats were given intra-vHC infusions of the GABAA receptor agonist muscimol or vehicle after they finished their first sucrose meal. Compared to vehicle infusions, postmeal intra-vHC muscimol infusions decreased the latency to the next sucrose meal, increased the amount of sucrose consumed during that meal, increased the total number of sucrose meals and the total amount of sucrose ingested. In addition, rats that consumed sucrose had higher levels of Arc expression in both vHC CA1 and CA3 subfields than cage control rats. Collectively, these findings are the first to show that vHC neurons inhibit energy intake during the postprandial period and support the hypothesis that vHC neurons form a memory of a meal and inhibit subsequent intake. © 2016 Wiley Periodicals, Inc.

Modulation of long-term endothelial-barrier integrity is conditional to the cross-talk between Akt and Src signaling.

Abstract: Although numerous studies have implicated Akt and Src kinases in vascular endothelial growth factor (VEGF) and Angiopoietin-1 (Ang-1)-induced endothelial-barrier regulation, a link between these two pathways has never been demonstrated. We determined the long-term effects of Akt inhibition on Src activity and vice versa, and in turn, on the human microvascular endothelial cell (HMEC) barrier integrity at the basal level, and in response to growth factors. Our data showed that Akt1 gene knockdown increases gap formation in HMEC monolayer at the basal level. Pharmacological inhibition of Akt, but not Src resulted in exacerbated VEGF-induced vascular leakage and impaired Ang-1-induced HMEC-barrier protection in vitro at 24 hr. Whereas inhibition of Akt had no effect on VEGF-induced HMEC gap formation in the short term, inhibition of Src blunted this process. In contrast, inhibition of Akt disrupted the VEGF and Ang-1 stabilized barrier integrity in the long-term while inhibition of Src did not. Interestingly, both long-term Akt inhibition and Akt1 gene knockdown in HMECs resulted in increased Tyr416 phosphorylation of Src. Treatment of HMECs with transforming growth factor-β1 (TGFβ1) that inhibited Akt Ser473 phosphorylation in the long-term, activated Src through increased Tyr416 phosphorylation and decreased HMEC-barrier resistance. The effect of TGFβ1 on endothelial-barrier breakdown was blunted in Akt1 deficient HMEC monolayers, where endothelial-barrier resistance was already impaired compared to the control. To our knowledge, this is the first report demonstrating a direct cross-talk between Akt and Src in endothelial-barrier regulation.

PRKCD/PKCδ contributes to nephrotoxicity during cisplatin chemotherapy by suppressing autophagy.

Abstract: Nephrotoxicity is a major side effect during chemotherapy with cisplatin and related platinum compounds. Previous work unveiled a role of PRKCD/PKCδ (protein kinase C delta) in cisplatin-induced nephrotoxicity; however, the underlying mechanism was largely unknown. Our recent work showed that PRKCD may suppress macroautophagy/autophagy, a cytoprotective mechanism, to promote kidney tubule cell death during cisplatin treatment. Interestingly, PRKCD may do so by phosphorylating AKT, which further phosphorylates MTOR to repress ULK1.

A Review of Epidemiologic Studies of the Health of Gulf War Women Veterans.

Abstract: Introduction In the 25 years since the 1990-1991 Gulf War (GW), studies have evaluated Gulf War Illness (GWI), sometimes referred to as medically unexplained multi symptom illness, and other medical and neurological conditions in women GW veterans. Materials and methods In this article, we review epidemiologic studies of the health of women who served in the 1990-1991 GW based upon bibliographic searches in PubMed and CINAHL with relevant search terms through September 2015. Results A total of 56 articles were identified in the bibliographic searches. By screening abstracts or full-text articles, a total of 21 relevant studies were identified. Results from some studies, but not all, suggest that GWI is more common in women GW veterans than their male counterparts. Few studies of GW veterans focused on women's health. A small number of studies suggested excess rates of woman's health problems, e.g., breast cysts, abnormal Papanicolaou (Pap) smears, yeast infections, and bladder infections. Several studies have identified significantly elevated rates of birth defects and adverse reproductive outcomes among GW veterans. However, findings have varied with different study designs and sample sizes, with some studies showing elevated risks of stillbirths, miscarriages, and/or birth defects and others have not. In some studies, participants reported increased risks of ectopic pregnancies and spontaneous abortions. Conclusion Further research is needed to provide a comprehensive picture of the health of women GW veterans and to examine a broad range of women's health issues including adverse reproductive outcomes. Some deployment-related health problems only become apparent decades later and other conditions may worsen or improve over time. Assessments are needed of current health status, changes in health symptoms and conditions over time, and possible differences in health outcomes associated with specific experiences and exposures during the war. Future studies would be strengthened by assessing GWI symptom patterns that may be specific to women veterans, examine diagnosed medical conditions among women veterans, and evaluate changes in women's health over time, including changes potentially associated with menopause and age.

Deletion of TXNIP mitigates high-fat diet-impaired angiogenesis and prevents inflammation in a mouse model of critical limb ischemia

Abstract: Background: Previous work demonstrated that high-fat diet (HFD) triggered thioredoxin-interacting protein (TXNIP) and that silencing TXNIP prevents diabetes-impaired vascular recovery. Here, we examine the impact of genetic deletion of TXNIP on HFD-impaired vascular recovery using hind limb ischemia model. Methods: Wild type mice (WT, C57Bl/6) and TXNIP knockout mice (TKO) were fed either normal chow diet (WT-ND and TKO-ND) or 60% high-fat diet (WT-HFD and TKO-HFD). After four weeks of HFD, unilateral hind limb ischemia was performed and blood flow was measured using Laser doppler scanner at baseline and then weekly for an additional three weeks. Vascular density, nitrative stress, infiltration of CD68+ macrophages, and expression of inflammasome, vascular endothelial growth factor (VEGF), VEGF receptor-2 were examined by slot blot, Western blot and immunohistochemistry. Results: By week 8, HFD caused similar increases in weight, cholesterol and triglycerides in both WT and TKO. At week 4 and week 8, HFD significantly impaired glucose tolerance in WT and to a lesser extent in TKO. HFD significantly impaired blood flow and vascular density (CD31 labeled) in skeletal muscle of WT mice compared to ND but not in TKO. HFD and ischemia significantly induced tyrosine nitration, and systemic IL-1β and infiltration of CD68+ cells in skeletal muscle from WT but not from TKO. HFD significantly increased cleaved-caspase-1 and IL-1 β compared to ND. Under both ND, ischemia tended to increase VEGF expression and increased VEGFR2 activation in WT only but not TKO. Conclusion: Similar to prior observation in diabetes, HFD-induced obesity can compromise vascular recovery in response to ischemic insult. The mechanism involves increased TXNIP-NLRP3 (nucleotide-binding oligomerization domain-like receptor protein 3) inflammasome activation, nitrative stress and impaired VEGFR2 activation. Deletion of TXNIP restored blood flow, reduced nitrative stress and blunted inflammasome-mediated inflammation; however, it did not impact VEGF/VEGFR2 in HFD. Targeting TXNIP-NLRP3 inflammasome can provide potential therapeutic target in obesity-induced vascular complication.

Aquaporins in the Skin

Abstract: The skin is the largest organ of the body, serving as an important barrier between the internal milieu and the external environment. The skin is also one of the first lines of defense against microbial infection and other hazards, and thus, the skin has important immune functions. This organ is composed of many cell types, including immune-active dendritic cells (epidermal Langerhans cells and dermal dendritic cells), connective tissue-generating dermal fibroblasts and pigment-producing melanocytes. Comprising the outer skin layer are the epidermal keratinocytes, the predominant cell of this layer, the epidermis, which provides both a mechanical barrier and a water-permeability barrier. Recent data suggest that aquaporins, a family of barrel-shaped proteins surrounding internal pores that allow the passage of water and, in some family members, small solutes such as glycerol, play critical roles in regulating various skin parameters. The involvement of different aquaporin family members in skin function is discussed.

Moving forward with the neuromuscular junction.

Abstract: The neuromuscular junction (NMJ) is indispensable for survival. This synapse between motoneurons and skeletal muscle fibers allows posture, movement and respiration. Therefore, its dysfunction creates pathologies than can be lethal. The molecular mechanisms of NMJ development and maintenance are the subject of intensive studies. This mini-review focuses on some of the most recent discoveries. An unexpected role for a protein, rapsyn, which has been known for 40 years to aggregate acetylcholine receptors has emerged. A new cell partner at NMJ has been unmasked and is challenging our understanding of the functioning of this synapse. Toxins are now used as new tools to study degeneration/regeneration. The possibility of creating human NMJ in vitro is within reach with major consequences for drug screening. Wnts are secreted neurogenic factors that have been involved in vitro in acetylcholine receptor clustering, but their precise role in vivo remains to be clarified. All these data are raising new and exciting perspectives in the field and are discussed in this Review. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.

Netrin-1 is a novel regulator of vascular endothelial function in diabetes.

Abstract: Background Netrin-1, a secreted laminin-like protein identified as an axon guidance molecule, has been shown to be of critical importance in the cardiovascular system. Recent studies have revealed pro-angiogenic, anti-apoptotic and anti-inflammatory properties of netrin-1 as well as cardioprotective actions against myocardial injury in diabetic mice. Aim To examine the role of netrin-1 in diabetes-and high glucose (HG)-induced vascular endothelial dysfunction (VED) using netrin-1 transgenic mice (Tg3) and cultured bovine aortic endothelial cells (BAEC). Main outcome Overexpression of netrin-1 prevented diabetes-induced VED in aorta from diabetic mice and netrin-1 treatment attenuated HG-induced impairment of nitric oxide synthase (NOS) function in BAECs. Methods and results Experiments were performed in Tg3 and littermate control (WT) mice rendered diabetic with streptozotocin (STZ) and in BAECs treated with HG (25 mmol/L). Levels of netrin-1 and its receptor DCC, markers of inflammation and apoptosis and vascular function were assessed in aortas from diabetic and non-diabetic Tg3 and WT mice. Vascular netrin-1 in WT mice was reduced under diabetic conditions. Aortas from non-diabetic Tg3 and WT mice showed similar maximum endothelium-dependent relaxation (MEDR) (83% and 87%, respectively). MEDR was markedly impaired in aorta from diabetic WT mice (51%). This effect was significantly blunted in Tg3 diabetic aortas (70%). Improved vascular relaxation in Tg3 diabetic mice was associated with increased levels of phospho-ERK1/2 and reduced levels of oxidant stress, NFκB, COX-2, p16INK4A, cleaved caspase-3 and p16 and p53 mRNA. Netrin-1 treatment prevented the HG-induced decrease in NO production and elevation of oxidative stress and apoptosis in BAECs. Conclusions Diabetes decreases aortic levels of netrin-1. However, overexpression of netrin-1 attenuates diabetes-induced VED and limits the reduction of NO levels, while increasing expression of p-ERK1/2, and suppressing oxidative stress and inflammatory and apoptotic processes. Enhancement of netrin-1 function may be a useful therapeutic means for preventing vascular dysfunction in diabetes.

Implication of the neurotrophin receptor p75NTR in vascular diseases: beyond the eye.

Abstract: Introduction: The p75 neurotrophin receptor (p75NTR) is a member of TNF-α receptor superfamily that bind all neurotrophins, mainly regulating their pro-apoptotic actions. Ischemia is a common pathology in different cardiovascular diseases affecting multiple organs, however the contribution of p75NTR remains not fully addressed. The aim of this work is to review the current evidence through published literature studying the impact of p75NTR receptor in ischemic vascular diseases. Areas covered: In the eye, several ischemic ocular diseases are associated with enhanced p75NTR expression. Ischemic retinopathy including diabetic retinopathy, retinopathy of prematurity and retinal vein occlusion are characterized initially by ischemia followed by excessive neovascularization. Beyond the eye, cerebral ischemia, myocardial infarction and critical limb ischemia are ischemic cardiovascular diseases that are characterized by altered expression of neurotrophins and p75NTR expression. We surveyed both clinical...

Inhibition of androgen receptor promotes CXC-chemokine receptor 7-mediated prostate cancer cell survival

Abstract: The atypical C-X-C chemokine receptor 7 (CXCR7) has been implicated in supporting aggressive cancer phenotypes in several cancers including prostate cancer. However, the mechanisms driving overexpression of this receptor in cancer are poorly understood. This study investigates the role of androgen receptor (AR) in regulating CXCR7. Androgen deprivation or AR inhibition significantly increased CXCR7 expression in androgen-responsive prostate cancer cell lines, which was accompanied by enhanced epidermal growth factor receptor (EGFR)-mediated mitogenic signaling, promoting tumor cell survival through an androgen-independent signaling program. Using multiple approaches we demonstrate that AR directly binds to the CXCR7 promoter, suppressing transcription. Clustered regularly interspaced short palindromic repeats (CRISPR) directed Cas9 nuclease-mediated gene editing of CXCR7 revealed that prostate cancer cells depend on CXCR7 for proliferation, survival and clonogenic potential. Loss of CXCR7 expression by CRISPR-Cas9 gene editing resulted in a halt of cell proliferation, severely impaired EGFR signaling and the onset of cellular senescence. Characterization of a mutated CXCR7-expressing LNCaP cell clone showed altered intracellular signaling and reduced spheroid formation potential. Our results demonstrate that CXCR7 is a potential target for adjuvant therapy in combination with androgen deprivation therapy (ADT) to prevent androgen-independent tumor cell survival.

Osteoblastic Lrp4 promotes osteoclastogenesis by regulating ATP release and adenosine-A2AR signaling.

Abstract: Bone homeostasis depends on the functional balance of osteoblasts (OBs) and osteoclasts (OCs). Lrp4 is a transmembrane protein that is mutated in patients with high bone mass. Loss of Lrp4 in OB-lineage cells increases bone mass by elevating bone formation by OBs and reducing bone resorption by OCs. However, it is unclear how Lrp4 deficiency in OBs impairs osteoclastogenesis. Here, we provide evidence that loss of Lrp4 in the OB lineage stabilizes the prorenin receptor (PRR) and increases PRR/V-ATPase-driven ATP release, thereby enhancing the production of the ATP derivative adenosine. Both pharmacological and genetic inhibition of adenosine-2A receptor (A2AR) in culture and Lrp4 mutant mice diminishes the osteoclastogenic deficit and reduces trabecular bone mass. Furthermore, elevated adenosine-A2AR signaling reduces receptor activator of nuclear factor κB (RANK)-mediated osteoclastogenesis. Collectively, these results identify a mechanism by which osteoblastic Lrp4 controls osteoclastogenesis, reveal a cross talk between A2AR and RANK signaling in osteoclastogenesis, and uncover an unrecognized pathophysiological mechanism of high-bone-mass disorders.

Anti-Psoriatic Drug Monomethylfumarate Increases Nuclear Factor Erythroid 2-Related Factor 2 Levels and Induces Aquaporin-3 mRNA and Protein Expression.

Abstract: Oxidative stress contributes to inflammatory skin diseases, including psoriasis. Monomethylfumarate (MMF) is an antipsoriatic agent with a poorly understood mechanism of action. In other cell types MMF increases the expression of nuclear factor erythroid-derived 2-like 2 (Nrf2), a transcription factor that regulates cellular antioxidant responses, to reduce oxidative stress like that observed in inflammatory disorders such as multiple sclerosis. We tested the hypothesis that MMF enhances Nrf2 activity in keratinocytes, thereby improving their capacity to counteract environmental stresses. We used Western analysis, immunofluorescence, and real-time quantitative reverse-transcription polymerase chain reaction to examine the effect of MMF on the expression of Nrf2 and its targets. We also measured intracellular reactive oxygen species (ROS) levels following MMF treatment. Our data show that MMF increased total and nuclear Nrf2 levels in primary mouse keratinocytes and enhanced mRNA expression of several Nrf2-downstream effectors, including heme oxygenase-1 and peroxiredoxin-6. Moreover, MMF treatment attenuated the generation of ROS following hydrogen peroxide treatment. On the other hand, the expression and membranous localization of aquaporin-3 (AQP3), a glycerol channel implicated in keratinocyte differentiation, was stimulated by MMF, which also enhanced keratinocyte glycerol uptake. The Nrf2 activator sulforaphane also increased AQP3 levels, suggesting that AQP3 expression may be regulated by Nrf2. We show for the first time that MMF stimulates Nrf2 and AQP3 expression and function/activity in keratinocytes. This effect may account, in part, for the previously observed ability of MMF to inhibit proliferation and inflammatory mediator production and promote differentiation in keratinocytes and to treat psoriasis.

Double knockout of Bax and Bak from kidney proximal tubules reduces unilateral urethral obstruction associated apoptosis and renal interstitial fibrosis.

Abstract: Interstitial fibrosis, a common pathological feature of chronic kidney diseases, is often associated with apoptosis in renal tissues. To determine the associated apoptotic pathway and its role in renal interstitial fibrosis, we established a mouse model in which Bax and Bak, two critical genes in the intrinsic pathway of apoptosis, were deleted specifically from kidney proximal tubules and used this model to examine renal apoptosis and interstitial fibrosis following unilateral urethral obstruction (UUO). It was shown that double knockout of Bax and Bak from proximal tubules attenuated renal tubular cell apoptosis and suppressed renal interstitial fibrosis in UUO. The results indicate that the intrinsic pathway of apoptosis contributes significantly to the tubular apoptosis and renal interstitial fibrosis in kidney diseases.

Agrin to YAP in Cancer and Neuromuscular Junctions

Abstract: Agrin is utilized by motor neurons to stimulate the LRP4-MuSK receptor in muscles for neuromuscular junction (NMJ) formation. Recent studies of cancer have identified novel functions of the low-density lipoprotein receptor-related protein 4-muscle-specific kinase (LRP4-MuSK) pathway. Agrin may act as a mechanotransduction signal in the extracellular matrix (ECM) to coordinate the cross-talk between the LRP4-MuSK pathway and integrin-focal adhesion pathway. Ensuing Yes-associated protein (YAP) activation promotes hepatocellular carcinoma (HCC). Here, we discuss the implications of the converged pathways in NMJ formation and liver cancer.

cGMP Signaling Increases Antioxidant Gene Expression by Activating Forkhead Box O3A in the Colon Epithelium.

Abstract: Signaling through cGMP has therapeutic potential in the colon, where it has been implicated in the suppression of colitis and colon cancer. In this study, we tested the ability of cGMP and type 2 cGMP-dependent protein kinase (PKG2) to activate forkhead box O (FoxO) in colon cancer cells and in the colon epithelium of mice. We show that activation of PKG2 in colon cancer cells inhibited cell proliferation, inhibited AKT, and activated FoxO. Treatment of colon explants with 8Br-cGMP also activated FoxO target gene expression at both RNA and protein levels, and reduced epithelial reduction-oxidation (redox) stress. FoxO3a was the most prominent isoform in the distal colon epithelium, with prominent luminal staining. FoxO3a levels were reduced in Prkg2 −/− animals, and FoxO target genes were unaffected by 8Br-cGMP challenge in vitro . Treatment of mice with the phosphodiesterase-5 inhibitor vardenafil (Levitra) mobilized FoxO3a to the nucleus of luminal epithelial cells, which corresponded to increased FoxO target gene expression, reduced redox stress, and increased epithelial barrier integrity. Treatment of human colonic biopsy specimens with 8Br-cGMP also activated catalase and manganese superoxide dismutase expression, indicating that this pathway is conserved in humans. Taken together, these results identify a novel signaling pathway in the colon epithelium, where FoxO tumor suppressors could provide protection from redox stress. Moreover, this pathway is regulated by endogenous cGMP/PKG2 signaling, and can be targeted using phosphodiesterase-5 inhibitors.

In-bed patient motion and pose analysis using depth videos for pressure ulcer prevention

Abstract: We present a real-time depth based computer vision system for pressure ulcer prevention, in-bed patient care and monitoring. Our system can effectively determine whether or not a mobility-compromised patient has been correctly repo-sitioned at the required frequency. A depth sensor is used to detect and recognize patient movements, motion patterns, and pose positions. If the patient has stayed in an unchanged pose for too long and needs pressure releasing movements, our system can notify caregivers for repositioning or assistance. Privacy concerns are mitigated by removing the RGB components of the video stream from the camera capturing, and only processing depth measurements. We collaborated with clinical practitioners at the Charlie Norwood VA Medical Center for in-field data collection and experimental evaluation. A web portal front-end is developed such that all historical patient movements, pose positions, and repositioning data can be organized to support telehealth applications.