Journal of immunology最新文献

Obexelimab is an investigational, bifunctional humanized monoclonal antibody that inhibits B-lineage cells by binding CD19 via its Fab region and simultaneously co-engaging the inhibitory receptor FcγRIIb through a modified Fc region. Interactions between B cells and T cells specific for the same Ag are essential for the development of germinal center (GC) B-cell responses and high-affinity antibodies. Mutant mice expressing human FcγRIIb and a mouse obexelimab surrogate (mObx) were used to determine if mObx inhibits these critical interactions between cognate B cells and T cells. In ex vivo experiments, mObx blocked B-cell receptor (BCR)-mediated uptake of Ag-coated beads by splenic follicular (Fo) and marginal zone (MZ) B cells and peritoneal cavity (PerC) B1 cells. Similarly, obexelimab treatment of human B cells significantly reduced BCR-mediated bead uptake ex vivo. mObx-treatment inhibited Ag presentation by splenic B cells to co-cultured T cells, as T-cell proliferation and expression of activation markers CD25 and CD44 were significantly reduced when mObx, but not control anti-CD19 antibody, was added to the co-culture. Finally, prophylactic treatment of mice with mObx effectively blocked the activation of human FcγRIIb-expressing B cells and the development of an Ag-specific GC response in vivo. Treatment after GC onset resulted in dissolution of the GC. Collectively, these data demonstrate that CD19/FcγRIIb co-engagement effectively suppresses processes essential to support T cell-dependent B-cell responses, which is consistent with the proposed mechanism of action of obexelimab.

Inflammation has enduring impacts on organismal immunity. However, the precise mechanisms by which tissue-restricted inflammation conditions systemic responses are poorly understood. Here, we leveraged a highly compartmentalized model of skin inflammation and identified a surprising type I interferon (IFN)-mediated activation of hematopoietic stem/progenitor cells (HSPCs) that results in profound changes to systemic host responses. Post-inflamed mice were protected from atherosclerosis and had worse outcomes following influenza virus infection. This IFN-mediated HSPC modulation was dependent on IFNAR signaling and could be recapitulated with the administration of recombinant IFN-α. Importantly, the transfer of post-inflamed HSPCs was sufficient to transmit the immune suppression phenotype. IFN modulation of HSPCs was rooted both in long-term changes in chromatin accessibility and the emergence of an IFN-responsive functional state from multiple progenitor populations. Collectively, our data reveal the profound and enduring effect of transient inflammation and more specifically type I IFN signaling and set the stage for a more nuanced understanding of HSPC functional modulation by peripheral immune signals.

Sarcoidosis is a granulomatous systemic inflammatory disease predominantly affecting the lungs. It shares histopathological, clinical, and immune features with tuberculosis (TB). There are currently no diagnostic tests to formally identify sarcoidosis; instead, there is a need first to rule out the presence of other diseases, including TB. We hypothesized that Mycobacterium tuberculosis (Mtb)-specific immune signatures differ between sarcoidosis and TB. We characterized T-cell and monocyte signatures after Mtb antigen in vitro stimulation in the blood of patients with sarcoidosis compared to patients with TB disease and Mtb-sensitized and nonsensitized healthy controls using flow cytometry and transcriptomics on bulk PBMCs and sorted CD4 memory T cells. We found that sarcoidosis was associated with (1) a marked reduction in frequencies of antigen-reactive T cells in response to both Mtb peptides and Mtb lysate, (2) increased frequencies of monocytes, and (3) increased expression of monocyte-associated phagocytic genes compared to TB disease and Mtb-sensitized and nonsensitized healthy cohorts. A combination of Mtb peptide-specific T-cell and monocyte gene or flow cytometry signatures in Mtb peptide-stimulated PBMCs distinguished sarcoidosis from TB disease with high accuracy (area under the curve [AUC] = 0.91 and 0.96 for gene and flow cytometry signatures, respectively) and also distinguished sarcoidosis from Mtb-sensitized and nonsensitized healthy controls combined (AUC = 0.91 and 0.90 for gene and flow cytometry signatures, respectively). These findings highlight biological features that effectively distinguish sarcoidosis from TB and healthy populations and can be considered for the development of an optimized diagnostic method for sarcoidosis.

Septic peritonitis (SP) is a severe infectious complication associated with high morbidity and mortality. The role of microRNAs, particularly endothelial progenitor cell-derived exosomal miRNA-31 (EPC-ExosmiR-31), in modulating inflammatory pathways in SP has garnered scholars' attention. However, its precise role and mechanism of action remain inadequately explored. Serum levels of miRNA-31 (miR-31) and soluble E-selectin (sSELE) were measured in patients with SP and healthy controls using qRT-PCR and ELISA. A colon ascendens stent peritonitis (CASP) mouse model was employed to replicate SP, and an in vitro sepsis model was induced via lipopolysaccharide (LPS) stimulation of mouse venous endothelial cells. The effects of EPC-ExosmiR-31 on cellular proliferation, apoptosis, and inflammatory markers were assessed through Giemsa and hematoxylin and eosin staining, qRT-PCR, Western blotting, and dual-luciferase reporter assay. Statistical analysis was conducted to evaluate the correlation among miR-31, sSELE, and sepsis severity. Patients with SP exhibited significantly lower serum miR-31 levels and elevated sSELE levels compared with healthy controls, and these changes were correlated with the severity of sepsis. In the CASP mouse model, extensive neutrophilic infiltration and inflammatory tissue damage were found in the lungs, liver, and colon. EPC-ExosmiR-31 administration significantly mitigated these effects by reducing SELE, caspase-3, and Bax expression levels, while increasing Bcl-2 expression level. In vitro, miR-31 enhanced cell proliferation and inhibited apoptosis in LPS-treated endothelial cells. The dual-luciferase reporter assay confirmed that miR-31 could directly target SELE. EPC-ExosmiR-31 alleviated SP by targeting SELE, thereby reducing endothelial dysfunction and systemic inflammation, reflecting a promising therapeutic approach for managing SP.

Mounting evidence supports a critical role for central nervous system (CNS) glial cells in neuroinflammation and neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's Disease (PD), Multiple Sclerosis (MS), as well as neurovascular ischemic stroke. Previously, we found that loss of the PD-associated gene leucine-rich repeat kinase 2 (Lrrk2) in macrophages, peripheral innate immune cells, induced mitochondrial stress and elevated basal expression of type I interferon (IFN) stimulated genes (ISGs) due to chronic mitochondrial DNA engagement with the cGAS/STING DNA sensing pathway. Here we report that loss of LRRK2 results in a paradoxical response in microglial cells, a CNS-specific macrophage population. In primary murine microglia and microglial cell lines, loss of Lrrk2 reduces tonic IFN signaling leading to a reduction in ISG expression. Consistent with reduced type I IFN, mitochondria from Lrrk2 KO microglia are protected from stress and have elevated metabolism. These protective phenotypes involve upregulation of NRF2, an important transcription factor in the response to oxidative stress and are restricted by LRRK2 kinase activity. Collectively, these findings illustrate a dichotomous role for LRRK2 within different immune cell populations and give insight into the fundamental differences between immune regulation in the CNS and the periphery.

Natural killer (NK) cells are pivotal innate lymphoid cells in anti-tumor immunity. However, the contribution of the Y chromosome-encoded epigenetic regulator UTY (also known as KDM6C) to male NK cell development and effector function remains poorly characterized. Here, we demonstrated that conditional deletion of UTY in NK cells (Ncr1-iCre) in male mice led to a statistically significant but modest increase in total NK cell numbers (P < 0.05) and an elevated frequency of terminally differentiated CD27-CD11b+ subset in the spleen. Strikingly, UTY-deficient NK cells displayed impaired cytotoxic function, with significantly reduced granzyme B expression (P < 0.05) and attenuated control of B16F10 melanoma pulmonary metastases in vivo (P < 0.05). Importantly, combined UTX-UTY deficiency exacerbated these phenotypes, causing further increase in NK cell abundance, and decline in CD27+CD11b+ subset proportions and granzyme B expression level compared with UTX single knockout in male mice. RNA-sequencing combined with qRT-PCR validation uncovered significant downregulation of key genes involved in NK cell maturation (Cd27), cytotoxicity (Gzmb), survival (Bax, Casp3) and transcriptional regulation (Socs3, Tcf7, Fos) in UTY-deficient NK cells. Notably, dual UTX-UTY depletion synergistically repressed Casp3 expression, potentially contributing to the altered NK cell abundance (P < 0.05). These findings establish UTY as a sex-specific epigenetic modulator that restricts NK cell maturation while promoting cytotoxic function. Our data further reveal a cooperative role for UTY and UTX in orchestrating NK cell development via transcriptional regulation.

Chronic graft-versus-host disease (cGVHD) develops with complex interactions between immune cells and cytokines, leading to irreversible fibrosis. Severe cGVHD impairs quality of life and is associated with nonrelapse mortality; however, effective treatments are limited. Recombinant human soluble thrombomodulin (rTM), a novel anticoagulant consisting of the extracellular domains of thrombomodulin, has shown efficacy in patients with transplantation-associated coagulation disorders and, recently, anti-inflammatory properties in animal studies. Here, we investigated the effects of rTM on cGVHD using a sclerodermatous cGVHD (Scl-cGVHD) mouse model. Prophylactic rTM administration suppressed the development of Scl-cGVHD skin lesions both clinically and histopathologically, prolonging event-free and overall survival. The rTM significantly reduced the infiltration of inflammatory cells, including activated T cells and transforming growth factor β1 (TGFβ1)-producing macrophages into the skin, while inflammation in the draining lymph nodes during priming phase and in spleen during chronic phase was unaffected. TGFβ1 expression in keratinocytes also decreased with rTM. Domain analysis suggested that these effects were mainly attributed to the N-terminal lectin-like domain (domain 1) of rTM, whose functions, including inhibition of inflammatory cell activation and recruitment related to interactions with endothelial cells, has recently been recognized in a limited number of preclinical studies. In conclusion, rTM prevented Scl-cGVHD development, likely by inhibiting the recruitment of inflammatory cells to the skin and subsequent TGFβ1 production by keratinocytes. The rTM may represent a novel prophylactic agent for cGVHD.

Germinal centers (GCs) are specialized sites in lymphoid tissues where antigen-specific B cells undergo proliferation, affinity maturation, and differentiation into high-affinity memory B cells and long-lived plasma cells following immunization or infection. The specific signals and mechanisms that are involved in GC B cell initiation, maintenance, and differentiation are not completely understood. Here, we investigated the expression and function of brain acid-soluble protein 1 (BASP1). Previously, no specific role for BASP1 in adaptive immunity has been established. BASP1 expression is induced in early GC B cells and increases over time as the GC progresses. We demonstrate, using short hairpin RNA knockdown and conditional deletion in mice, that BASP1 functions to maintain GC responses by promoting GC B cell survival and reducing memory B cells, and increasing plasma cell output. Finally, BASP1 induces a unique transcriptional program in GC B cells, enriched for interferon-γ- and interleukin-12-responsive genes. Thus, BASP1 regulates the survival and transcriptome of GC B cells as well as alters the nature of the memory B cell subset and plasma cell generation.

Influenza is a significant public health and economic threat around the world. Although pneumonia is the most common complication associated with influenza, there are several clinical reports showing an increased risk for cardiovascular disease. Studies have shown that influenza infection correlates with increased incidence of myocardial infarction. Atherosclerosis is a common cause of coronary artery disease including myocardial infarction, stroke, and heart failure. Here, we analyzed the effect of influenza infection in high-fat diet-induced atherosclerosis in Apoe-/- mice. We found increased weight loss and decreased survival, increased numbers of CD11b+Ly6C+ cells (inflammatory monocytes) and CD11b+Ly6G+ cells (neutrophils), increased levels of CCL3, CCL4, and CCL5, increased lung pathology, and increased atherosclerotic lesions in the aorta in influenza-infected Apoe-/- mice when compared to influenza-infected wild-type (WT) and control (PBS-treated) Apoe-/- mice. An increased percentage of RORγt+ and IL-17+ cells were identified in influenza-infected Apoe-/- mice compared with influenza-infected WT mice and PBS-treated Apoe-/- mice. Bone marrow macrophages from influenza-infected Apoe-/- mice showed increased expression of Th17 polarizing cytokines. Influenza-infected Color-flu (Venus)-positive cells were identified in inflammatory monocytes and neutrophils in the lungs, spleen, blood, aorta, and vascular endothelial cells. These results suggest that influenza infection increases arterial inflammation by directly infecting endothelial cells, and indirectly through recruitment of inflammatory monocytes and neutrophils. Increased Th17 responses in influenza-infected Apoe-/- mice may be a possible mechanism involved in increased lung pathology and exacerbation of high-fat diet-induced atherosclerosis.

Tristetraprolin (TTP) is an anti-inflammatory protein that mediates messenger RNA (mRNA) decay of certain transcripts, especially those encoding proinflammatory cytokines. TTP modulates various pathological outcomes in diverse inflammatory diseases; however, its role in ozone (O3)-induced acute lung injury (ALI) has never been tested. Here, we hypothesized that the loss of TTP would exacerbate O3-induced ALI and that the systemic overexpression of TTP would mitigate O3-induced ALI. Accordingly, TTP-knockout (TTPKO), airway epithelial cell-specific TTP-deficient (EpiKO), myeloid cell-specific TTP-deficient (MyeKO), and systemic TTP-overexpressing (TTPΔARE) adult male and female mice, along with their respective littermate control TTP-sufficient mice, were exposed to either O3 (3 ppm) or filtered air for 3 h. The endpoints, including bronchoalveolar lavage fluid cellularity, cytokine levels, and histopathological changes, were assessed 21 to 24 h after O3 or filtered air exposure. As compared with the O3-exposed TTP-sufficient mice, the O3-exposed TTPKO and O3-exposed cell-specific TTP-deficient mice exhibited a significant worsening of ALI outcomes (i.e., neutrophil infiltration, cytokine/chemokine production, and lung pathology). The severity of these outcomes was comparatively milder in O3-exposed EpiKO and O3-exposed MyeKO mice than in O3-exposed TTPKO mice. Conversely, the O3-exposed TTPΔARE mice were protected against O3-induced ALI, as indicated by relatively reduced levels of inflammatory cytokines/chemokines, reduced neutrophil infiltration, and mitigated lung pathology. Collectively, our data suggest that TTP is a critical regulator of inflammation in O3-induced ALI. These findings indicate that enhancing TTP expression could be a potential therapeutic strategy for simultaneously targeting multiple inflammatory cytokines in O3-induced ALI and possibly other inflammatory diseases.