👤 Martin Chopra

Few HIV-specific epitopes restricted by non-classical HLA-E have been described, and even less is known about the functional profile of responding CD8+ T cells (CD8s). This study evaluates the functional characteristics of CD8s targeting the Gag epitope KF11 (KAFSPEVIPMF) restricted by either HLA-E (E-CD8s) or HLA-B57 (B57-CD8s). CD8s from 8 people with HIV (PWH) were cocultured with KF11 peptide presented by cell lines expressing HLA-B*57:01, HLA-E*01:01, or HLA-E*01:03. CD8 responses were analyzed using single-cell RNA and TCR sequencing. Supernatants were also assessed for soluble protein profiling. HLA-I multimers were developed to identify CD8s restricted by HLA-B57 and/or HLA-E ex vivo. B57-CD8s secreted higher levels of cytotoxic cytokines such as IFN-γ, whereas E-CD8s produced more chemotactic cytokines, including RANTES, CXCL10 (IP-10), and IL-27, findings that were corroborated through single-cell RNA sequencing. TCR clonotypes stimulated by KF11 were cross-restricted by HLA-B*57 and HLA-E*01:03 as demonstrated by in vitro T cell reporter assays and ex vivo multimer screening. Ex vivo CD8s were singly restricted by HLA-B57 and HLA-E, with dual restriction only observed in PWH with lower viral load. These findings demonstrate that certain HIV-specific CD8s in PWH exhibit dual restriction by HLA-B*57 and HLA-E*01:03, leading to functionally distinct immune responses depending on the restricting allele(s). Show less

Major depressive disorder (MDD) continues to be a primary cause of disability globally, with a significant number of patients exhibiting resistance to standard pharmacological and psychotherapeutic interventions. In recent years, non-invasive brain stimulation techniques, especially transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), have emerged as promising therapies for treatment-resistant MDD. A comprehensive search was performed in PubMed, which included all studies published over the last ten years. Eligible studies encompassed both animal models and clinical investigations. This review provides a comparative overview of transcranial electrical stimulation modalities, with a focus on their mechanisms of action, clinical efficacy, and underlying neurobiological mechanisms. We pay particular attention to the role of the neurotrophin system, specifically brain-derived neurotrophic factor (BDNF), in mediating the treatment effects of transcranial stimulation. Recent findings indicate that neuromodulation could improve neuroplasticity by increasing BDNF levels and associated signaling pathways, which may help stabilize mood and enhance the improvement of individuals with MDD. A more profound understanding of these mechanisms could lead to more precise, biomarker-driven interventions. Further research is essential to elucidating the long-term effects of brain stimulation on neurotrophin levels and to creating more individualized treatment strategies. Show less

Hypertrophic cardiomyopathy (HCM) is characterized by thickening of the left ventricular wall, diastolic dysfunction, and fibrosis, and is associated with mutations in genes encoding sarcomere proteins. While in vitro studies have used human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to study HCM, these models have not examined the multicellular interactions involved in fibrosis. Using engineered cardiac microtissues (CMTs) composed of HCM-causing Show less

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in combination with CRISPR/Cas9 genome editing provide unparalleled opportunities to study cardiac biology and disease. However, sarcomeres, the fundamental units of myocyte contraction, are immature and nonlinear in hiPSC-CMs, which technically challenge accurate functional interrogation of contractile parameters in beating cells. Furthermore, existing analysis methods are relatively low-throughput, indirectly assess contractility, or only assess well-aligned sarcomeres found in mature cardiac tissues. We aimed to develop an analysis platform that directly, rapidly, and automatically tracks sarcomeres in beating cardiomyocytes. The platform should assess sarcomere content, contraction and relaxation parameters, and beat rate. We developed SarcTrack, a MatLab software that monitors fluorescently tagged sarcomeres in hiPSC-CMs. The algorithm determines sarcomere content, sarcomere length, and returns rates of sarcomere contraction and relaxation. By rapid measurement of hundreds of sarcomeres in each hiPSC-CM, SarcTrack provides large data sets for robust statistical analyses of multiple contractile parameters. We validated SarcTrack by analyzing drug-treated hiPSC-CMs, confirming the contractility effects of compounds that directly activate (CK-1827452) or inhibit (MYK-461) myosin molecules or indirectly alter contractility (verapamil and propranolol). SarcTrack analysis of hiPSC-CMs carrying a heterozygous truncation variant in the myosin-binding protein C ( MYBPC3) gene, which causes hypertrophic cardiomyopathy, recapitulated seminal disease phenotypes including cardiac hypercontractility and diminished relaxation, abnormalities that normalized with MYK-461 treatment. SarcTrack provides a direct and efficient method to quantitatively assess sarcomere function. By improving existing contractility analysis methods and overcoming technical challenges associated with functional evaluation of hiPSC-CMs, SarcTrack enhances translational prospects for sarcomere-regulating therapeutics and accelerates interrogation of human cardiac genetic variants. Show less

The inflammatory bowel diseases (IBD) ulcerative colitis (UC) and Crohn's disease (CD) cause significant morbidity and are increasing in prevalence among all populations, including African Americans. More than 200 susceptibility loci have been identified in populations of predominantly European ancestry, but few loci have been associated with IBD in other ethnicities. We performed 2 high-density, genome-wide scans comprising 2345 cases of African Americans with IBD (1646 with CD, 583 with UC, and 116 inflammatory bowel disease unclassified) and 5002 individuals without IBD (controls, identified from the Health Retirement Study and Kaiser Permanente database). Single-nucleotide polymorphisms (SNPs) associated at P < 5.0 × 10 We detected SNPs at HLA-DRB1, and African-specific SNPs at ZNF649 and LSAMP, with associations of genome-wide significance for UC. We detected SNPs at USP25 with associations of genome-wide significance for IBD. No associations of genome-wide significance were detected for CD. In addition, 9 genes previously associated with IBD contained SNPs with significant evidence for replication (P < 1.6 × 10 We performed a genome-wide association study of African Americans with IBD and identified loci associated with UC in only this population; we also replicated IBD, CD, and UC loci identified in European populations. The detection of variants associated with IBD risk in only people of African descent demonstrates the importance of studying the genetics of IBD and other complex diseases in populations beyond those of European ancestry. Show less

Embryonic organs attain their final dimensions through the generation of proper cell number and size, but the control mechanisms remain obscure. Here, we establish Gridlock (Grl), a Hairy-related basic helix-loop-helix (bHLH) transcription factor, as a negative regulator of cardiomyocyte proliferative growth in zebrafish embryos. Mutations in grl cause an increase in expression of a group of immediate-early growth genes, myocardial genes, and development of hyperplastic hearts. Conversely, cardiomyocytes with augmented Grl activity have diminished cell volume and fail to divide, resulting in a marked reduction in heart size. Both bHLH domain and carboxyl region are required for Grl negative control of myocardial proliferative growth. These Grl-induced cardiac effects are counterbalanced by the transcriptional activator Gata5 but not Gata4, which promotes cardiomyocyte expansion in the embryo. Biochemical analyses show that Grl forms a complex with Gata5 through the carboxyl region and can repress Gata5-mediated transcription via the bHLH domain. Hence, our studies suggest that Grl regulates embryonic heart growth via opposing Gata5, at least in part through their protein interactions in modulating gene expression. Show less

The MEK family of protein kinases plays key roles in regulating cellular responses to mitogens as well as environmental stress. Inappropriate activation of these kinases contributes to tumorigenesis. In contrast, anthrax lethal factor, the principal virulence factor of anthrax toxin, has been demonstrated to selectively inactivate MEKs. In this article we will discuss recent advances in our understanding of molecular aspects of the pathogenesis of anthrax, emphasizing the potential role of MEK signalling in this disease, and outline novel strategies to use anthrax lethal toxin in the treatment of cancer. Show less