Journal of immunology最新文献

Poliovirus receptor (PVR) ligands have gained attention as immunotherapy targets, yet their regulation remains unclear. Here, we examine the impact of PVR exposure on primary human CD8+ T cells. We used flow cytometry and Western blot analysis to quantify expression of PVR and its ligands in naïve and effector T cells and used adhesion assays and enzyme-linked immunosorbent assay (ELISA) to assess the impact of PVR on T cell adhesion and cytokine production. Stimulation with phytohemagglutinin P strongly increased DNAM-1 expression and caused a less robust and more variable increase in TIGIT expression. Exposure to PVR-Fc enhanced the CD8+ T cell adhesion to ICAM-1-coated plates in a dose-dependent manner, while exposure to PVR-expressing K32 cells mildly decreased CD8+ T cell interferon γ release. However, PVR exposure strongly decreased the expression of DNAM-1, TIGIT, and CD96. The reduction of DNAM-1, TIGIT, and CD96 induced by PVR was dominant to the increase caused by T cell receptor signaling. The impact of PVR on their expression was completely abolished by the Q63R and F128R point mutations of PVR, while DNAM-1 was partially rescued by inhibitors of Src and protein kinase C. Additionally, PVR exposure along with T cell receptor signaling promoted the transfer of surface proteins including PVR from K32 cells to CD8+ T cells. This PVR transfer was mediated by the IgV domain of PVR and CD96 on CD8+ T cells and required cellular contact. Our findings collectively demonstrate that PVR engagement has a mild antagonistic effect on interferon γ production but strongly impacts CD8+ T cell adhesion and protein expression.

The CD2-depleting drug alefacept (LFA3-Ig) preserved beta cell function in new-onset type 1 diabetes (T1D) patients. The most promising biomarkers of response were late expansion of exhausted CD8 T cells and rare baseline inflammatory islet-reactive CD4 T cells, neither of which can be used to measure responses to drug in the weeks after treatment. Thus, we investigated whether early changes in T cell immunophenotypes could serve as biomarkers of drug activity. We characterized T cell responses by flow cytometry and identified an exhausted-like population of CD2low CD4 effector memory T cells coexpressing TIGIT and PD1 that expanded by 11 wk after the start of treatment. This population was not entirely spared from alefacept-mediated depletion in vivo or in vitro but recovered through homeostatic proliferation of CD2low cells in vivo. Proliferation of TIGIT+PD1+ effector memory CD4 T cells increased with treatment, with a concomitant reduction of proinflammatory cytokine production. The persistent increase of TIGIT+PD1+ effector memory CD4 T cells was specific to alefacept treatment; 2 other T cell depleting therapies, teplizumab and anti-thymocyte globulin, induced only a transient increase in this CD4 population. Our data suggest that the expanding TIGIT+PD1+ effector memory CD4 T cell population represents a promising biomarker of early treatment effects of alefacept. The nondepleting effects on proliferation and cytokine production also suggest agonistic activity by this CD2 targeted therapy.

The von Hippel-Lindau (VHL) tumor suppressor gene VHL is a classic tumor suppressor that has been identified in family members with clear cell renal cell carcinomas, central nervous system and retinal hemangioblastomas, phaeochromocytomas, and pancreatic neuroendocrine tumors. The well-defined function of VHL is to mediate proteasomal degradation of hydroxylated hypoxia-inducible factor α proteins, resulting in the downregulation of hypoxia-responsive gene expression. Previously, we reported that VHL inhibits antiviral signaling by targeting mitochondrial antiviral signaling protein (MAVS) for proteasomal degradation. However, due to the lack of a viable animal model, the physiological role and underlying mechanism of VHL in antiviral immunity remains to be elucidated. In this study, we found that heterozygous vhl-deficient zebrafish have normal neutrophils and no gross phenotypic alterations. However, upon spring viremia of carp virus or grass carp reovirus infection, antiviral gene expression is induced in vhl+/- zebrafish compared with wild-type zebrafish. In addition, spring viremia of carp virus replication is suppressed in vhl+/- zebrafish, owing to the enhancement of antiviral ability. Furthermore, by crossing with mavs-/- zebrafish line, we observed that disruption of mavs in vhl+/- zebrafish abrogates the viral resistance exhibited in vhl+/- zebrafish. Thus, we reveal that heterozygous vhl deficiency enhances the antiviral ability of zebrafish against RNA virus infection, and we provide genetic evidence to support that zebrafish mavs serves as a mediator for the suppressive role of vhl in antiviral innate immunity.

Decoy receptor 3 (DcR3), a soluble receptor in the tumor necrosis factor receptor superfamily, regulates the functions of monocytes, macrophages, dendritic cells, and T cells. Previous studies have demonstrated that DcR3 suppresses B cell proliferation in vitro and ameliorates autoimmune diseases in animal models; however, whether and how DcR3 regulates antibody production is unclear. Using a DcR3 transgenic mouse model, we found that DcR3 impaired the T cell-dependent antigen-stimulated antibody response. The number of Ag-specific antibody-secreting cells was transiently reduced, but the concentration of specific antibodies continued to decrease in the DcR3 transgenic mice, implying a direct suppression of antibody production by DcR3. In vitro assays showed that the DcR3-Fc fusion protein attenuated T cell-dependent induced antibody production and reduced the expression of secretory Igh and Xbp1. We found that nuclear factor κB (NF-κB) activity was essential for the expression of Xbp1 in activated B cells. DcR3-Fc attenuated anti-CD40-induced NF-κB activity and Xbp1 promoter activity. Furthermore, DcR3-Fc decreased the expression of Xbp1 in Blimp1+ antibody-secreting cells. Restoration of spliced XBP1 (X-box binding protein 1) in DcR3-treated B cells increased the secretory Ighg1 transcript levels, suggesting that reducing XBP1 is one of the mechanisms by which DcR3 regulates antibody production both in vitro and in vivo. Collectively, these results indicate that in addition to blocking proliferation, DcR3 impairs NF-κB activation, subsequently decreasing the expression of Xbp1, eventually leading to a reduction in antibody secretion.

Current influenza vaccines are not effective in conferring protection against antigenic variants and pandemics. To improve cross-protection of influenza vaccination, we developed a 5xM2e messenger RNA (mRNA) vaccine encoding the tandem repeat conserved ectodomain (M2e) of ion channel protein M2 derived from human, swine, and avian influenza A viruses. The lipid nanoparticle (LNP)-encapsulated 5xM2e mRNA vaccine was immunogenic, eliciting high levels of M2e-specific IgG antibodies, IFN-γ+ T cells, T follicular helper cells, germinal center phenotypic B cells, and plasma cells. The mice with 5xM2e mRNA vaccination were broadly protected against lethal infection regardless of hemagglutinin (H1, H3, H5) subtypes by preventing severe weight loss. Injection of 5xM2e mRNA LNP vaccine induced acute innate responses recruiting monocytes, macrophages, and diverse subsets of dendritic cells. A single dose of combined 5xM2e mRNA LNP and split vaccines resulted in significantly enhanced and sustainable IgG antibody responses to viral antigens and protection against homologous and heterologous viruses. This study provides a new strategy of combined mRNA and seasonal vaccination, significantly enhancing vaccine protective efficacy.

ISG15, an IFN-stimulated gene, plays a crucial role in modulating immune responses during viral infections. Its upregulation is part of the host's defense mechanism against viruses, contributing to the antiviral state of cells. However, altered ISG15 expression can also lead to immune dysregulation and pathological outcomes, particularly during persistent viral infections. Understanding the balance of ISG15 in promoting antiviral immunity while avoiding immune-mediated pathology is essential for developing targeted therapeutic interventions against viral diseases. In this article, using Usp18-deficient, USP18 enzymatic-inactive and Isg15-deficient mouse models, we report that a lack of USP18 enzymatic function during persistent viral infection leads to severe immune pathology characterized by hematological disruptions described by reductions in platelets, total WBCs, and lymphocyte counts; pulmonary cytokine amplification; lung vascular leakage; and death. The lack of Usp18 in myeloid cells mimicked the pathological manifestations observed in Usp18-/- mice and required Isg15. Mechanistically, interrupting the enzymes that conjugate/deconjugate ISG15, using Uba7-/- or Usp18C61A mice, respectively, led to accumulation of ISG15 that was accompanied by inflammatory neutrophil accumulation, lung pathology, and death similar to that observed in Usp18-deficient mice. Moreover, myeloid cell depletion reversed pathological manifestations, morbidity, and mortality in Usp18C61A mice. Our results suggest that dysregulated ISG15 production and signaling during persistent lymphocytic choriomeningitis virus infection can produce lethal immune pathology and could serve as a therapeutic target during severe viral infections with pulmonary pathological manifestations.

IL-33 plays an important role in the early programming of CD8 T cells; however, its contribution to the differentiation of tissue-resident memory T cells in vivo remains poorly defined. After infection of mice with Yersinia pseudotuberculosis, IL-33 expression was increased in the intestinal tissue, and this coincided with the expression of ST2 on T cells infiltrating the intestinal epithelium and lamina propria. Blocking IL-33 signaling after T cell infiltration of the intestinal tissue did not significantly impact the number or phenotype of tissue-resident memory T cells generated. However, overexpression of ST2 on T cells was able to increase expression of TCF1 and T cell number in the intestine compared with the lymphoid organs during infection. We also observed that enhanced accumulation and maintenance of ST2-overexpressing cells in the intestine postinfection were resolved. This points to a role for IL-33 in increasing the number of T cells that commit to intestinal tissue residency in vivo.

Ubiquitination is a critical posttranslational modification that regulates host immune responses to pathogens. In this study, we investigated the ubiquitination of hemocyanin (PvHMC [Penaeus vannamei hemocyanin]) mediated by the mitochondrial E3 ubiquitin ligase (PvMulan) in shrimp Penaeus vannamei. We characterized distinct ubiquitination patterns of PvHMC in response to different pathogen challenges, both in vitro and in vivo. Specifically, we found that Vibrio parahaemolyticus infection led to an increase in PvMulan, which resulted in K48-linked ubiquitination and subsequent proteasomal degradation of PvHMC. In contrast, PvMulan primarily enhanced the SUMOylation of PvHMC, bolstering its immune functions against white spot syndrome virus challenges. Inhibition of PvMulan-mediated PvHMC ubiquitination significantly affected the proliferation of V. parahaemolyticus and the survival rate of infected shrimps. This study sheds light on the role of hemocyanin ubiquitination in immune regulation, illustrating its dual function in response to distinct pathogens.

Autophagy serves as a critical regulator of immune responses in sepsis. Macrophages are vital constituents of both innate and adaptive immunity. In this study, we delved into the intricate role of p120-catenin (p120) in orchestrating autophagy in macrophages in response to endotoxin stimulation. Depletion of p120 effectively suppressed LPS-induced autophagy in both J774A.1 macrophages and murine bone marrow-derived macrophages. LPS not only elevated the interaction between p120 and L chain 3 (LC3) I/II but also facilitated the association of p120 with mammalian target of rapamycin (mTOR). p120 depletion in macrophages by small interfering RNA reduced LPS-induced dissociation of mTOR and Unc-51-like kinase 1 (ULK1), leading to an increase in the phosphorylation of ULK1. p120 depletion also enhanced LPS-triggered macrophage apoptosis, as evidenced by increased levels of cleaved caspase 3, 7-aminoactinomycin D staining, and TUNEL assay. Notably, inhibiting autophagy reversed the decrease in apoptosis caused by LPS stimulation in macrophages overexpressing p120. Additionally, the ablation of p120 inhibited autophagy and accentuated apoptosis in alveolar macrophages in LPS-challenged mice. Collectively, our findings strongly suggest that p120 plays a pivotal role in fostering autophagy while concurrently hindering apoptosis in macrophages, achieved through modulation of the mTOR/ULK1 signaling pathway in sepsis. This underscores the potential of targeting macrophage p120 as an innovative therapeutic avenue for treating inflammatory disorders.

CMV infection and Th17 cells are independently associated with increased risk for late allograft loss after renal transplantation. Although CMV-specific Th17 cells are detectable in animal models and nontransplant clinical populations, evidence linking CMV and Th17 cells after renal transplantation remains unclear. This prospective observational study evaluated a cohort of renal transplant recipients during 12 mo posttransplant to assess the presence of CMV-specific Th17 cells in peripheral blood and their relationship to pretransplant CMV serostatus and CMV DNAemia. CMV-specific Th17 cells were identified among CMV serostatus donor (D)+ and/or recipient (R)+ recipients and expanded during both primary (D+/R-) and reactivated (D+/R+, D-/R+) CMV DNAemia. A subset of CMV-specific Th17 cells coexpressed IFN-γ, indicating a Th1/17 phenotype. These Th17 and Th1/17 cells expressed CCR6, CCR5, activation and terminal differentiation markers (CD95, OX40, HLA-DR, CD57), and a central/effector memory phenotype. CMV-specific Th1/17 cells expressed activating/inhibitory receptors (CD57, 4-1BB, CD160, CTLA-4, PD-1) at higher frequencies than Th17 cells. In contrast, staphylococcal enterotoxin B-induced Th17 cells did not expand during CMV DNAemia, did not differ between CMV serostatus groups over time, expressed CCR6, predominantly coexpressed TNF-α, and had lower expression of activating and inhibitory receptors than pp65-specific Th17 and Th1/17 cells. These data show that CMV-specific Th17 cells expand during episodes of CMV DNAemia among renal transplant recipients, and that these virus-specific Th17 and Th1/17 cells have distinct phenotypes from global circulating Th(1)/17 cells. These results suggest a potential proinflammatory pathway by which CMV-induced Th17 cells may contribute to allograft injury, increasing risk for late allograft loss.