Journal of Experimental Medicine最新文献

Insights into HIV-1 pathogenesis have come from studies of viral dynamics. However, there is little information on viral dynamics in lentiviral infections in which viral replication is naturally controlled in a subset of infected individuals. We evaluated the decay of simian immunodeficiency virus (SIV) RNA and cell-associated SIV genomes in a nonhuman primate (NHP) model in which replication of an engineered SIV variant is naturally controlled by cellular immune responses in most infected animals. This variant lacks a trafficking motif in the gp41 cytoplasmic tail. A trajectory of control was evident by 21 days after infection. In animals with natural control, we observed similar biphasic decay of intact proviruses in blood and lymph nodes, at rates close to those in animals that failed to control the virus and were put on antiretroviral therapy (ART). Both natural control and ART effectively blocked viral evolution, but not persistence. Thus, in this NHP model, natural control can be nearly as effective as ART in controlling viral replication.

T cell engagers (TCEs) are antibody-based constructs designed to transiently reprogram cytotoxic T lymphocytes for target cell elimination by simultaneously binding the T cell receptor and a specific surface antigen on the target cell. Over the past 12 years, 10 TCEs were approved by the US Food and Drug Administration, and an additional two by the European Medicines Agency. Nine TCEs treat hematologic malignancies, and three target solid tumors. Over 150 TCEs are being investigated in clinical trials, recently also in autoimmune diseases. Here, we discuss the learnings from the 12 approved TCEs. A surprising variety of molecular designs and biochemical characteristics appear suitable for approval. On the clinical side, we review targets, indications, dosing, schedules, side effects, mitigation strategies for adverse events, and efficacy. High flexibility in design and choice of target, scalability, high response rates as a monotherapy in hematologic malignancies, and emerging efficacy against solid tumors and in autoimmune diseases make TCEs an attractive therapeutic modality.

Resident memory CD8+ T cells (Trms) are essential for protecting barrier nonlymphoid tissues (NLTs) against reinfection, yet the involvement of dendritic cells (DCs) in this process and the nature of Trm-DC interactions within these tissues remain poorly understood. Our study demonstrates that upon reactivation, memory CD8+ T cells located in the skin-independently of circulating memory counterparts-initiate the infiltration and maturation of plasmacytoid DCs (pDCs) in the tissue. This, in turn, promotes the maturation of conventional type 1 DCs (cDC1s) through type I IFN (IFN-I) signaling in a pDC-dependent manner. Depletion of pDCs or blocking IFN-I signaling disrupts this axis, severely impairing Trm-driven protection against secondary infections with vaccinia virus (VACV) in the skin. Notably, this pDC-dependent, IFN-I-mediated pathway is also essential for Trm-mediated protection against secondary respiratory infections with influenza A virus (IAV). Our findings uncover a crucial collaboration between Trm, pDCs, and cDC1s, offering new insights for enhancing vaccines.

Respiratory viral infections establish tissue-resident memory T cells (TRM) in the lung, which provide optimal protection against subsequent infections, though the underlying mechanisms are incompletely understood. Here, we demonstrate in a mouse model of heterosubtypic influenza infection that lung TRM attenuate inflammation by macrophages during secondary versus primary responses, in part, through production of the immunoregulatory cytokine IL-10. During secondary infections, lung TRM were the predominant producers of early IL-10; inhibiting early IL-10 signaling resulted in increased macrophage-mediated inflammation, morbidity, and lung pathology. Moreover, lung TRM were shown to directly modulate lung macrophage responses and polarization in depletion experiments. Finally, IL-10 enhanced IFN-γ production by lung memory CD8+ T cells. Human influenza-specific TRM isolated from lungs recapitulated robust IL-10 expression associated with augmented effector responses of murine TRM. These data support a dual role of TRM in coordinating in situ secondary responses-augmenting effector responses for robust viral clearance while dampening inflammation to limit tissue damage.

Genetic variants in the FCRL3 gene are linked to autoimmune disorders. However, the functional properties of FCRL3-expressing T lymphocytes, and the regulation and functional impact of FCRL3 expression remain understudied. Here, we performed a multiomic and functional analysis of human T lymphocytes expressing FCRL3. FCRL3 expression correlated with reduced capacity of T cells to undergo activation and was accompanied by functional specialization toward a cytotoxic phenotype, resembling cytotoxic CD4+ T lymphocytes and CD8+ effector memory TEMRA cells. FCRL3 expression was induced upon repetitive TCR engagement, and sufficed to attenuate T cell responses, indicating a role as a negative regulator of the activation of differentiated T cell subsets with high cytotoxic capacity. Mechanistically, the cytoplasmic domain of FCRL3 engaged inhibitory molecules, suggesting a direct role in limiting activating signals. Overall, our study establishes FCRL3 as a functional immunoregulatory receptor that restrains the activation of highly specialized human memory T cells.

Polyglutamine (polyQ) diseases, caused by a CAG repeat expansion encoding a glutamine tract in nine distinct proteins, present a complex molecular puzzle in which each piece contributes to neurodegeneration. While each of the causative proteins has a distinct function, the downstream consequences of polyQ toxicity are often similar, including protein accumulation, transcriptional dysregulation, somatic CAG repeat instability, disrupted energy homeostasis, compromised synaptic function, and selective neuronal death. This review summarizes emerging insights into how proteins with an expanded polyQ tract disrupt distinct cellular functions, and we examine a multitude of discoveries that are inspiring and reshaping novel therapeutic strategies.

Myeloid cells, including dendritic cells (DCs) and macrophages, are essential for establishing central tolerance in the thymus by promoting T cell clonal deletion and regulatory T cell (Treg) generation. Previous studies suggest that the thymic DC pool consists of plasmacytoid DC (pDC), XCR1+ DC1, and SIRPα+ DC2. Yet the precise origin, development, and homeostasis, particularly of DC2, remain unresolved. Using single-cell transcriptomics and lineage-defining mouse models, we identify nine major populations of thymic myeloid cells and describe their lineage identities. What was previously considered to be "DC2" is actually composed of four distinct cell lineages. Among these are monocyte-derived DCs (moDCs) and monocyte-derived macrophages (moMacs), which are dependent on thymic IFN to upregulate MHCII and CD11c. We further demonstrate that conventional DC2 undergo intrathymic maturation through CD40 signaling. Finally, amongst DC2, we identify a novel thymic population of CX3CR1+ transitional DC (tDC), which represents transendothelial DCs positioned near thymic microvessels. Together, these findings reveal the thymus as a niche for diverse, developmentally distinct myeloid cells and elucidate their specific requirements for development and maturation.

Herpes simplex encephalitis (HSE) is a devastating disease with high mortality and serious sequelae. Genetic defects in the IFN-I pathway predispose individuals to HSE, but underlying mechanisms remain unclear. Using transgenic mice with the IRF3 R278Q mutation, ortholog to HSE-associated IRF3 R285Q, and iPSC-derived CNS cells from a pediatric patient carrying the variant, we investigated mechanisms in HSE. IRF3 R278Q transgenic mice exhibited aggravated HSV-1 brain disease and elevated CNS viral loads. Accordingly, microglia from the IRF3 R278Q mice showed reduced HSV-1-induced IFN-I expression. Surprisingly, unaltered Ifnb levels along with elevated levels of inflammatory cytokines were detected in infected transgenic mouse brains, correlating with higher viral load. This was successfully modeled in patient microglia. Multiomics-based immune profiling revealed an inflammatory monocyte population in the infected IRF3 R278Q mouse brain, which was enriched for NF-κB activation. NF-κB inhibition improved disease outcomes, surpassing the effect of acyclovir. These findings suggest that IFN-I defects lead to elevated levels of HSV-1 replication in the brain, which subsequently enables NF-κB-driven immunopathology, offering insights with therapeutic potential.

Inborn errors of immunity (IEI) impairing brain-intrinsic immune defenses can underlie herpes simplex virus encephalitis. By whole-exome sequencing of cohorts of herpesvirus-associated recurrent lymphocytic meningitis and acute retinal necrosis, we identified two patients heterozygous for variants in interferon (IFN) regulatory factor 7 (IRF7). The expression of the Q185X (patient 1, P1) and A86Rfs23X (P2) IRF7 variants in HEK293T cells resulted in truncated IRF7 proteins that lacked IFN-transactivating ability. Peripheral blood mononuclear cells from P1 exhibited reduced type I IFN responses to HSV-2 infection. Genetic knock-in of the IRF7 Q185X variant in THP-1 cells and stem cell-derived plasmacytoid dendritic cells (pDC) confirmed the disrupted IFN expression, resulting in impaired paracrine antiviral protection of meningeal fibroblasts. Strikingly, genetically heterozygous index patient pDC, but not those of healthy carrier family members, showed expression of only the pathogenic IRF7 Q185X allele, resulting in a homozygous transcriptotype. Collectively, this study identifies genetically heterozygous but transcriptionally homozygous IRF7 deficiency as an IEI underlying herpesvirus central nervous system infection.