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Steven David Brooks

Bio: Steven David Brooks is an academic researcher from National Institutes of Health. The author has contributed to research in topics: Vasodilation & Endothelial stem cell. The author has an hindex of 1, co-authored 3 publications receiving 1 citations.

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Journal ArticleDOI
TL;DR: This work comprehensively characterizes the clinical and transcriptomic progression of B. rossi infection in canines, thus establishing a large mammalian model of severe hemoprotozoal disease to facilitate the study of host-parasite biology and in which to test novel anti-disease therapeutics.
Abstract: Background Babesia rossi is a leading cause of morbidity and mortality among the canine population of sub-Saharan Africa, but pathogenesis remains poorly understood. Previous studies of B. rossi infection were derived from clinical cases, in which neither the onset of infection nor the infectious inoculum was known. Here, we performed controlled B. rossi inoculations in canines and evaluated disease progression through clinical tests and whole blood transcriptomic profiling. Results Two subjects were administered a low inoculum (104 parasites) while three received a high (108 parasites). Subjects were monitored for 8 consecutive days; anti-parasite treatment with diminazene aceturate was administered on day 4. Blood was drawn prior to inoculation as well as every experimental day for assessment of clinical parameters and transcriptomic profiles. The model recapitulated natural disease manifestations including anemia, acidosis, inflammation and behavioral changes. Rate of disease onset and clinical severity were proportional to the inoculum. To analyze the temporal dynamics of the transcriptomic host response, we sequenced mRNA extracted from whole blood drawn on days 0, 1, 3, 4, 6, and 8. Differential gene expression, hierarchical clustering, and pathway enrichment analyses identified genes and pathways involved in response to hemolysis, metabolic changes, and several arms of the immune response including innate immunity, adaptive immunity, and response to viral infection. Conclusions This work comprehensively characterizes the clinical and transcriptomic progression of B. rossi infection in canines, thus establishing a large mammalian model of severe hemoprotozoal disease to facilitate the study of host-parasite biology and in which to test novel anti-disease therapeutics. The knowledge gained from the study of B. rossi in canines will not only improve our understanding of this emerging infectious disease threat in domestic dogs, but also provide insight into the pathobiology of human diseases caused by Babesia and Plasmodium species.

6 citations

Posted ContentDOI
09 Apr 2021-medRxiv
TL;DR: Vardef et al. as mentioned in this paper investigated the role of endothelial alpha globin as a regulator of directed nitric oxide signaling across the myoendothelial junction, and found that alpha-1-adrenergic receptors on vascular smooth muscle cells triggering an influx of calcium (Ca++) and activating myosin light chain kinase (MLCK) to constrict muscle fibers across the lamina and constrict the artery.
Abstract: BackgroundIn small arteries, constriction of vascular smooth muscle triggers local release of nitric oxide from the adjacent endothelial cell. This feedback vasodilation is a homeostatic mechanism that opposes vasoconstriction. Here, we investigate the role of endothelial alpha globin as a regulator of directed nitric oxide signaling across the myoendothelial junction. MethodsHuman omental arteries 100-200{micro}m in diameter were microdissected from omentum samples obtained during clinically indicated abdominal operations on NIH protocol 13-C-0176 (NCT01915225). Each artery was cannulated, perfused free of blood, and preserved for analysis or subjected to pressure myography. Preserved arteries underwent RNA extraction for gene expression; protein extraction for co-immunoprecipitation and Western blot; or immunostaining for multiphoton microscopy. Bio-layer interferometry quantified the binding of alpha globin to endothelial nitric oxide synthase (eNOS). Ex vivo pressure myography characterized arterial vasoreactivity before and after disruption of eNOS-Hb binding with an alpha globin mimetic peptide. ResultsHBA1, HBA2, HBB, and NOS3 transcripts were abundant in RNA from the artery wall, and the blood cell gene SLC4A1 was not. Beta globin and eNOS co-immunoprecipitated with alpha globin in protein extracted from human omental artery segments, suggesting an eNOS-hemoglobin complex. Biolayer interferometry studies estimated alpha globin to bind to the oxidase domain of eNOS with an equilibrium dissociation constant of 1.3 x 10-6 M. Multiphoton microscopy of intact arteries revealed alpha globin, beta globin, and eNOS to co-localize within distinct punctates in a plane defined by the internal elastic lamina that separates endothelial cells from vascular smooth muscle. Forster resonance energy transfer confirmed close physical proximity of alpha globin to eNOS in situ. Omental arteries constricted to 39.1 {+/-} 3.2 % of baseline diameter in response to phenylephrine. After treatment with an alpha globin mimetic peptide, the same arteries constricted to 64.6 {+/-} 1.6% of baseline (p View larger version (39K): org.highwire.dtl.DTLVardef@ee9965org.highwire.dtl.DTLVardef@98f1dcorg.highwire.dtl.DTLVardef@12ed202org.highwire.dtl.DTLVardef@dda0af_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract. Hemoglobin binds to endothelial NOS in the myoendothelial junction where it regulates the diffusion of nitric oxide that is produced in response to alpha-1-adrenergic signaling. Phenylephrine (PE) engages alpha-1-adrenergic receptors (1) on vascular smooth muscle cells triggering an influx of calcium (Ca++) and activating myosin light chain kinase (MLCK) to constrict muscle fibers ({approx}) and constrict the artery. Calcium enters the endothelial cell via putative gap junctions where it activates endothelial nitric oxide synthase (NOS) via calmodulin (CM). Nitric oxide (NO) produced by NOS can diffuse into the smooth muscle cell where it activates myosin light chain phosphatase (MLCP) via soluble guanylate cyclase and cGMP (both not shown) to relax smooth muscle fibers and dilate the artery. Hemoglobin () bound to NOS prevents the diffusion of NO into the smooth muscle cell likely by catalyzing the reaction with oxygen (O2) to produce nitrate (NO3-), an anion that cannot diffuse across the cell membrane. When hemoglobin is displaced from NOS with a mimetic peptide (not shown), NO diffusion increases and counteracts vasoconstriction; when NOS is inhibited by L-NAME, the mimetic peptide has no effect. Thus hemoglobin limits the diffusion of NO across the myoendothelial junction in the setting of alpha-1-adrenergic stimulation. C_FIG

2 citations

Posted ContentDOI
20 Oct 2021-bioRxiv
TL;DR: In this paper, the authors sought to determine whether lisinopril or losartan, as monotherapies or in combination, change tissue levels of ACE2 in healthy male and female mice.
Abstract: Angiotensin-converting enzyme 2 (ACE2) is the established cellular receptor for SARS-CoV-2. However, it is unclear whether ACE1 inhibitors (e.g., lisinopril) or angiotensin receptor blockers (e.g., losartan) alter tissue ACE2 expression. This study sought to determine whether lisinopril or losartan, as monotherapies or in combination, change tissue levels of ACE2 in healthy male and female mice. Mice were treated for 21 days with drinking water containing lisinopril (10 mg/kg/day), losartan (10 mg/kg/day), or both. A control group was given water without drug. ACE2 protein index, the ratio of ACE2 protein to total protein, was determined on tissues from the small intestine, lung, kidney, and brain. Oral lisinopril increased ACE2 protein index across all tissues (p

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01 Nov 2015
TL;DR: In this article, the authors used single-cell RNA-seq to identify CD5L/AIM as a regulator expressed in non-pathogenic, but not in pathogenic Th17 cells.
Abstract: Summary Th17 cells play a critical role in host defense against extracellular pathogens and tissue homeostasis but can induce autoimmunity. The mechanisms implicated in balancing "pathogenic" and "non-pathogenic" Th17 cell states remain largely unknown. We used single-cell RNA-seq to identify CD5L/AIM as a regulator expressed in non-pathogenic, but not in pathogenic Th17 cells. Although CD5L does not affect Th17 differentiation, it is a functional switch that regulates the pathogenicity of Th17 cells. Loss of CD5L converts non-pathogenic Th17 cells into pathogenic cells that induce autoimmunity. CD5L mediates this effect by modulating the intracellular lipidome, altering fatty acid composition and restricting cholesterol biosynthesis and, thus, ligand availability for Rorγt, the master transcription factor of Th17 cells. Our study identifies CD5L as a critical regulator of the Th17 cell functional state and highlights the importance of lipid metabolism in balancing immune protection and disease induced by T cells.

229 citations

Journal ArticleDOI
TL;DR: In this article , the authors discuss the host's immune response to the Babesia parasite, vaccines being used to prevent babesiosis in animals, and lessons from malaria vaccine development efforts to inform the development of a human Babesiosis vaccine.

3 citations

Journal ArticleDOI
TL;DR: A review of the studies on the pathogenesis of anemia in canine babesiosis and related diseases, such as bovine or murine babesia and human or murinea malaria, and the role of pro-inflammatory cytokines and chemokines in the mechanisms leading to anemia of infected dogs is presented in this article .
Abstract: Canine babesiosis is a tick-borne protozoan disease caused by intraerythrocytic parasites of the genus Babesia. The infection may lead to anemia in infected dogs. However, anemia is not directly caused by the pathogen. The parasite’s developmental stages only have a marginal role in contributing to a decreased red blood cell (RBC) count. The main cause of anemia in affected dogs is the immune response to the infection. This response includes antibody production, erythrophagocytosis, oxidative damage of RBCs, complement activation, and antibody-dependent cellular cytotoxicity. Moreover, both infected and uninfected erythrocytes are retained in the spleen and sequestered in micro-vessels. All these actions are driven by pro-inflammatory cytokines and chemokines, especially IFN-γ, TNF-α, IL-6, and IL-8. Additionally, imbalance between the actions of pro- and anti-inflammatory cytokines plays a role in patho-mechanisms leading to anemia in canine babesiosis. This article is a review of the studies on the pathogenesis of anemia in canine babesiosis and related diseases, such as bovine or murine babesiosis and human or murine malaria, and the role of pro-inflammatory cytokines and chemokines in the mechanisms leading to anemia in infected dogs.

2 citations

Journal ArticleDOI
04 Feb 2022-PLOS ONE
TL;DR: It is suggested that genetic variation in alpha globin gene expression does not modify the risk of hypertension among Black American adults.
Abstract: BACKGROUND: Alpha globin is expressed in the endothelial cells of human resistance arteries where it binds to endothelial nitric oxide synthase and limits release of the vasodilator nitric oxide. Genomic deletion of the alpha globin gene (HBA) is common among Black Americans and could lead to increased endothelial nitric oxide signaling and reduced risk of hypertension. METHODS: Community-dwelling US adults aged 45 years or older were enrolled and examined from 2003 to 2007, followed by telephone every 6 months, and reexamined from 2013 to 2016. At both visits, trained personnel performed standardized, in-home blood pressure measurements and pill bottle review. Prevalent hypertension was defined as systolic blood pressure [≥] 140mmHg or diastolic blood pressure [≥] 90mmHg or anti-hypertensive medication use. Droplet digital PCR was used to determine HBA copy number. The associations of HBA copy number with prevalent hypertension, resistant hypertension, and incident hypertension were estimated using multivariable regression. RESULTS: Among 9,684 Black participants, 7,439 (77%) had hypertension at baseline and 1,044 of those had treatment-resistant hypertension. 1,000 participants were not hypertensive at baseline and participated in a follow up visit; 517 (52%) developed hypertension over median 9.2 years follow-up. Increased HBA copy number was not associated with prevalent hypertension (PR=1.00; 95%CI 0.98,1.02), resistant hypertension (PR=0.95; 95%CI 0.86,1.05), or incident hypertension (RR=0.96; 95%CI 0.86,1.07). CONCLUSIONS: There were no associations between increased HBA copy number and risk of hypertension. These findings suggest that genetic variation in alpha globin gene expression does not modify the risk of hypertension among Black American adults.

2 citations

Journal ArticleDOI
TL;DR: In this article , the authors assessed serum proteomic profiles from dogs with babesiosis and healthy dogs using a label-based proteomics approach and identified potential serum biomarkers for differentiation of disease severity in canine Babesiosis caused by B. rossi.
Abstract: Babesiosis is a disease of significant medically and veterinary importance with worldwide distribution. It is caused by intra-erythrocyte protozoal parasites, with Babesia rossi causing the most severe clinical signs of all the large Babesia parasites infecting dogs. The disease can be clinically classified into uncomplicated and complicated forms with a wide range of clinical presentations from a mild, subclinical illness to complicated forms and death. The aim of this study was to assess serum proteomic profiles from dogs with babesiosis and healthy dogs using a label-based proteomics approach. Altogether 32 dogs naturally infected with B. rossi (subdivided into 18 uncomplicated cases and 14 complicated cases of babesiosis) and 20 healthy dogs were included. There were 78 proteins with significantly different abundances between the three groups of dogs. Elucidation of proteins and pathways involved in canine babesiosis caused by B. rossi have revealed key differences associated with haemostasis, innate immune system, lipid metabolism and inflammation. Shotgun proteomic profiling allowed identification of potential serum biomarkers for differentiation of disease severity in canine babesiosis caused by B. rossi. These findings may be applicable to the study of host-parasite interactions and the development of novel therapeutic targets.