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Multiple sclerosis (MS) is a complex disease of the CNS thought to require an environmental trigger. Gut dysbiosis is common in MS, but specific causative species are unknown. To address this knowledge gap, we used sensitive and quantitative PCR detection to show that people with MS were more likely to harbor and show a greater abundance of epsilon toxin-producing (ETX-producing) strains of C. perfringens within their gut microbiomes compared with individuals who are healthy controls (HCs). Isolates derived from patients with MS produced functional ETX and had a genetic architecture typical of highly conjugative plasmids. In the active immunization model of experimental autoimmune encephalomyelitis (EAE), where pertussis toxin (PTX) is used to overcome CNS immune privilege, ETX can substitute for PTX. In contrast to PTX-induced EAE, where inflammatory demyelination is largely restricted to the spinal cord, ETX-induced EAE caused demyelination in the corpus callosum, thalamus, cerebellum, brainstem, and spinal cord, more akin to the neuroanatomical lesion distribution seen in MS. CNS endothelial cell transcriptional profiles revealed ETX-induced genes that are known to play a role in overcoming CNS immune privilege. Together, these findings suggest that ETX-producing C. perfringens strains are biologically plausible pathogens in MS that trigger inflammatory demyelination in the context of circulating myelin autoreactive lymphocytes.

The pancreatic islets are composed of discrete hormone-producing cells that orchestrate systemic glucose homeostasis. Here we identify subsets of beta cells using a single-cell transcriptomic approach. One subset of beta cells marked by high CD63 expression is enriched for the expression of mitochondrial metabolism genes and exhibits higher mitochondrial respiration compared with CD63lo beta cells. Human and murine pseudo-islets derived from CD63hi beta cells demonstrate enhanced glucose-stimulated insulin secretion compared with pseudo-islets from CD63lo beta cells. We show that CD63hi beta cells are diminished in mouse models of and in humans with type 2 diabetes. Finally, transplantation of pseudo-islets generated from CD63hi but not CD63lo beta cells into diabetic mice restores glucose homeostasis. These findings suggest that loss of a specific subset of beta cells may lead to diabetes. Strategies to reconstitute or maintain CD63hi beta cells may represent a potential anti-diabetic therapy.

Tumour-specific CD8 T cell dysfunction is a differentiation state that is distinct from the functional effector or memory T cell states.sup.1-6. Here we identify the nuclear factor TOX as a crucial regulator of the differentiation of tumour-specific T (TST) cells. We show that TOX is highly expressed in dysfunctional TST cells from tumours and in exhausted T cells during chronic viral infection. Expression of TOX is driven by chronic T cell receptor stimulation and NFAT activation. Ectopic expression of TOX in effector T cells in vitro induced a transcriptional program associated with T cell exhaustion. Conversely, deletion of Tox in TST cells in tumours abrogated the exhaustion program: Tox-deleted TST cells did not upregulate genes for inhibitory receptors (such as Pdcd1, Entpd1, Havcr2, Cd244 and Tigit), the chromatin of which remained largely inaccessible, and retained high expression of transcription factors such as TCF-1. Despite their normal, 'non-exhausted' immunophenotype, Tox-deleted TST cells remained dysfunctional, which suggests that the regulation of expression of inhibitory receptors is uncoupled from the loss of effector function. Notably, although Tox-deleted CD8 T cells differentiated normally to effector and memory states in response to acute infection, Tox-deleted TST cells failed to persist in tumours. We hypothesize that the TOX-induced exhaustion program serves to prevent the overstimulation of T cells and activation-induced cell death in settings of chronic antigen stimulation such as cancer. The nuclear factor TOX is highly expressed in antigen-specific dysfunctional T cells in tumours and exhausted T cells during chronic viral infection and is a crucial regulator of the differentiation of tumour-specific T cells., Author(s): Andrew C. Scott [sup.1] [sup.2] , Friederike Dündar [sup.3] [sup.4] , Paul Zumbo [sup.3] [sup.4] , Smita S. Chandran [sup.5] [sup.6] , Christopher A. Klebanoff [sup.5] [sup.6] [sup.7] [sup.8] [...]

Background Most Crohn's disease [CD] patients require surgery. Ileitis recurs after most ileocolectomies and is a critical determinant for outcomes. The impacts of ileocolectomy-induced bile acid [BA] perturbations on intestinal microbiota and inflammation are unknown. We characterized the relationships between ileocolectomy, stool BAs, microbiota and intestinal inflammation in inflammatory bowel disease [IBD]. Methods Validated IBD clinical and endoscopic assessments were prospectively collected. Stool primary and secondary BA concentrations were compared based on ileocolectomy and ileitis status. Primary BA thresholds for ileitis were evaluated. Metagenomic sequencing was use to profile microbial composition and function. Relationships between ileocolectomy, BAs and microbiota were assessed. Results In 166 patients, elevated primary and secondary BAs existed with ileocolectomy. With ileitis, only primary BAs [795 vs 398 nmol/g, p  = 0.009] were higher compared to without ileitis. The optimal primary BA threshold [≥228 nmol/g] identified ileitis on multivariable analysis [odds ratio = 2.3, p  = 0.04]. Microbial diversity, Faecalibacterium prausnitzii and O -acetylhomoserine aminocarboxypropyltransferase [MetY] were decreased with elevated primary BAs. Amongst ileocolectomy patients, only those with elevated primary BAs had diversity, F. prausnitzii and MetY reductions. Those with both ileocolectomy and intermediate [ p  = 0.002] or high [≥228 nmol/g, p  = 9.1e-11]] primary BA concentrations had reduced F. prausnitzii compared to without ileocolectomy. Those with ileocolectomy and low [<29.2 nmol/g] primary BA concentrations had similar F. prausnitzii to those without ileocolectomy [ p  = 0.13]. MetY was reduced with ileitis [ p  = 0.02]. Conclusions Elevated primary BAs were associated with ileitis, and reduced microbial diversity, F. prausnitzii abundance and enzymatic abundance of MetY [acetate and l -methionine-producing enzyme expressed by F. prausnitzii ], and were the only factors associated with these findings after ileocolectomy. [ABSTRACT FROM AUTHOR]

Efforts to cure HIV have focused on reactivating latent proviruses to enable elimination by CD8+ cytotoxic T-cells. Clinical studies of latency reversing agents (LRA) in antiretroviral therapy (ART)-treated individuals have shown increases in HIV transcription, but without reductions in virologic measures, or evidence that HIV-specific CD8+ T-cells were productively engaged. Here, we show that the SARS-CoV-2 mRNA vaccine BNT162b2 activates the RIG-I/TLR – TNF – NFκb axis, resulting in transcription of HIV proviruses with minimal perturbations of T-cell activation and host transcription. T-cells specific for the early gene-product HIV-Nef uniquely increased in frequency and acquired effector function (granzyme-B) in ART-treated individuals following SARS-CoV-2 mRNA vaccination. These parameters of CD8+ T-cell induction correlated with significant decreases in cell-associated HIV mRNA, suggesting killing or suppression of cells transcribing HIV. Thus, we report the observation of an intervention-induced reduction in a measure of HIV persistence, accompanied by precise immune correlates, in ART-suppressed individuals. However, we did not observe significant depletions of intact proviruses, underscoring challenges to achieving (or measuring) HIV reservoir reductions. Overall, our results support prioritizing the measurement of granzyme-B-producing Nef-specific responses in latency reversal studies and add impetus to developing HIV-targeted mRNA therapeutic vaccines that leverage built-in LRA activity. Here, the authors show in a cohort of people with HIV, COVID mRNA vaccination is followed by a transient boost in a particular profile of HIV-specific T-cell responses and a corresponding decrease in residual HIV RNA – suggesting productive immune engagement with infected cells. [ABSTRACT FROM AUTHOR]

Multiple sclerosis (MS) is a complex disease of the CNS thought to require an environmental trigger. Gut dysbiosis is common in MS, but specific causative species are unknown. To address this knowledge gap, we used sensitive and quantitative PCR detection to show that people with MS were more likely to harbor and show a greater abundance of epsilon toxin-producing (ETX-producing) strains of C. perfringens within their gut microbiomes compared with individuals who are healthy controls (HCs). Isolates derived from patients with MS produced functional ETX and had a genetic architecture typical of highly conjugative plasmids. In the active immunization model of experimental autoimmune encephalomyelitis (EAE), where pertussis toxin (PTX) is used to overcome CNS immune privilege, ETX can substitute for PTX. In contrast to PTX-induced EAE, where inflammatory demyelination is largely restricted to the spinal cord, ETX-induced EAE caused demyelination in the corpus callosum, thalamus, cerebellum, brainstem, and spinal cord, more akin to the neuroanatomical lesion distribution seen in MS. CNS endothelial cell transcriptional profiles revealed ETX-induced genes that are known to play a role in overcoming CNS immune privilege. Together, these findings suggest that ETX-producing C. perfringens strains are biologically plausible pathogens in MS that trigger inflammatory demyelination in the context of circulating myelin autoreactive lymphocytes. [ABSTRACT FROM AUTHOR]

HIV persists, despite immune responses and antiretroviral therapy, in viral reservoirs that seed rebound viremia if therapy is interrupted. Previously, we showed that the BCL-2 protein contributes to HIV persistence by conferring a survival advantage to reservoir-harboring cells. Here, we demonstrate that many of the BCL-2 family members are overexpressed in HIV-infected CD41 T cells, indicating increased tension between proapoptotic and prosurvival family members--and suggesting that inhibition of prosurvival members may disproportionately affect the survival of HIV-infected cells. Based on these results, we chose to study BCL-XL due to its consistent overexpression and the availability of selective antagonists. Infection of primary CD41 T cells with HIV resulted in increased BCL-XL protein expression, and treatment with two selective BCL-XL antagonists, A-1155463 and A-1551852, led to selective death of productively infected CD41 T cells. In a primary cell model of latency, both BCL-XL antagonists drove reductions in HIV DNA and in infectious cell frequencies both alone and in combination with the latency reversing agent bryostatin-1, with little off-target cytotoxicity. However, these antagonists, with or without bryostatin-1 or in combination with the highly potent latency reversing agent combination phorbol myristate acetate (PMA) 1 ionomycin, failed to reduce total HIV DNA and infectious reservoirs in ex vivo CD41 T cells from antiretroviral therapy (ART)-suppressed donors. Our results add to growing evidence that bona fide reservoir-harboring cells are resistant to multiple "kick and kill" modalities--relative to latency models. We also interpret our results as encouraging further exploration of BCL-XL antagonists for cure, where combination approaches, including with immune effectors, may unlock the ability to eliminate ex vivo reservoirs. [ABSTRACT FROM AUTHOR]