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Curing HIV infection will require the elimination of a reservoir of infected CD4(+) T cells that persists despite HIV-specific cytotoxic T cell (CTL) responses. Although viral latency is a critical factor in this persistence, recent evidence also suggests a role for intrinsic resistance of reservoir-harboring cells to CTL killing. This resistance may have contributed to negative outcomes of clinical trials, where pharmacologic latency reversal has thus far failed to drive reductions in HIV reservoirs. Through transcriptional profiling, we herein identified overexpression of the prosurvival factor B cell lymphoma 2 (BCL-2) as a distinguishing feature of CD4(+) T cells that survived CTL killing. We show that the inducible HIV reservoir was disproportionately present in BCL-2(hi) subsets in ex vivo CD4(+) T cells. Treatment with the BCL-2 antagonist ABT-199 was not sufficient to drive reductions in ex vivo viral reservoirs when tested either alone or with a latency-reversing agent (LRA). However, the triple combination of strong LRAs, HIV-specific T cells, and a BCL-2 antagonist uniquely enabled the depletion of ex vivo viral reservoirs. Our results provide rationale for novel therapeutic approaches targeting HIV cure and, more generally, suggest consideration of BCL-2 antagonism as a means of enhancing CTL immunotherapy in other settings, such as cancer.

McCann et al. describe the development and characterization of a new mouse model for studying HIV-specific T cell responses and testing various immunotherapeutic strategies, which they validate by demonstrating enhanced therapeutic effects of autologous HIV-specific T cells augmented with cytokine-loaded nanogels., HIV-specific CD8+ T cells partially control viral replication and delay disease progression, but they rarely provide lasting protection, largely due to immune escape. Here, we show that engrafting mice with memory CD4+ T cells from HIV+ donors uniquely allows for the in vivo evaluation of autologous T cell responses while avoiding graft-versus-host disease and the need for human fetal tissues that limit other models. Treating HIV-infected mice with clinically relevant HIV-specific T cell products resulted in substantial reductions in viremia. In vivo activity was significantly enhanced when T cells were engineered with surface-conjugated nanogels carrying an IL-15 superagonist, but it was ultimately limited by the pervasive selection of a diverse array of escape mutations, recapitulating patterns seen in humans. By applying mathematical modeling, we show that the kinetics of the CD8+ T cell response have a profound impact on the emergence and persistence of escape mutations. This “participant-derived xenograft” model of HIV provides a powerful tool for studying HIV-specific immunological responses and facilitating the development of effective cell-based therapies.

SummaryGut microbial diurnal oscillations are important diet-dependent drivers of host circadian rhythms and metabolism that ensure optimal energy balance. Yet, the interplay between diet, microbes, and host factors that sustain intestinal oscillations is complex and poorly understood. Here, we report the host C-type lectin antimicrobial peptideReg3γworks with key ileal microbes to orchestrate these interactions in a bi-directional manner, independent from the intestinal core circadian clock. High fat diet diminishes physiologically relevant microbial oscillators essential for host metabolic homeostasis, resulting in arrhythmic hostReg3γexpression and increased abundance and oscillation ofReg3γ-independent gut microbes. This illustrates a transkingdom co-evolved biological rhythm involving reciprocating, sensor-effector signals between key host and microbial components that ultimately drive metabolism, but are also heavily influenced by diet. Restoring the gut microbiota’s capacity to sense and transduce dietary signals mediated by specific host factors such asReg3γcould be harnessed to improve metabolic dysfunction.

Gut microbial diurnal oscillations are important diet-dependent drivers of host circadian rhythms and metabolism that ensure optimal energy balance. Yet, the interplay between diet, microbes, and host factors that sustain intestinal oscillations is complex and poorly understood. We report the host C-type lectin antimicrobial peptide REG3γ works with key ileal microbes to orchestrate these interactions in a bi-directional manner, independent from the intestinal core circadian clock. High fat diet diminishes physiologically relevant microbial oscillators essential for host metabolic homeostasis, resulting in arrhythmic host REG3γ expression and increased abundance and oscillation of REG3γ-independent gut microbes. This illustrates a transkingdom co-evolved biological rhythm involving reciprocating, sensor-effector signals between key host and microbial components that ultimately drive metabolism, but are also heavily influenced by diet. Restoring the gut microbiota’s capacity to sense and transduce dietary signals mediated by specific host factors such as REG3γ could be harnessed to improve metabolic dysfunction.

Curing HIV infection will require the elimination of a reservoir of infected CD4+ T-cells that persists despite HIV-specific CTL responses. While viral latency is a critical factor in this persistence, recent evidence also suggests a role for intrinsic resistance of reservoir-harboring cells to CTL killing. We explored the hypothesis that this resistance is mediated by BCL-2 family proteins, which can antagonize CTL-induced apoptosis. We show that the reactivatable HIV reservoir is disproportionately present in BCL-2hi CD4+ T-cells, which are relatively resistant to CTL. BCL-2/BCL-XL antagonists were sufficient for inducing the elimination of HIV-infected cells from a primary-cell model of latency, but did not drive reductions in ex vivo viral reservoirs when tested either alone or with a latency reversing agent (LRA). The triple combination of LRAs, HIV-specific T-cells, and a BCL-2 antagonist uniquely enabled depletions in ex vivo viral reservoirs, providing rationale for novel therapeutic approaches targeting HIV cure.

SummaryCircadian clocks and metabolism are inextricably intertwined, where central and hepatic circadian clocks coordinate metabolic events in response to light-dark and sleep-wake cycles. We reveal an additional key element involved in maintaining host circadian rhythms, the gut microbiome. Despite persistence of light-dark signals, germ-free mice fed low or high-fat diets exhibit markedly impaired central and hepatic circadian clock gene expression and do not gain weight compared to conventionally raised counterparts. Examination of gut microbiota in conventionally raised mice showed differential diurnal variation in microbial structure and function dependent upon dietary composition. Additionally, specific microbial metabolites induced under low- or high-fat feeding, particularly short-chain fatty acids, but not hydrogen sulfide, directly modulate circadian clock gene expression within hepatocytes. These results underscore the ability of microbially derived metabolites to regulate or modify central and hepatic circadian rhythm and host metabolic function, the latter following intake of a Westernized diet.

Abstract 3005 Graft-versus-host disease (GVHD) primarily affects the epithelial compartments of skin, liver, and gut and is thought to display tissue tropism for two main reasons: the conditioning regimen can selectively damage these epithelial cell compartments due to rapid cell turnover; and these epithelial organs have high exposure to host commensals and their products that promote tissue-specific inflammation. To understand how commensals mediate GVHD, we first tested the hypothesis that the disruption of the MyD88 signaling pathway, which is critical for host-microbe interaction, would alter GVHD outcomes. We created bone marrow chimeras that received a second allogeneic bone marrow transplant (BMT) and showed that MyD88 deficiency in recipient hematopoietic cells reduced BMT mortality, while deficiency in the non-hematopoietic cells (NHC) increased BMT mortality (p Disclosures: No relevant conflicts of interest to declare.