Journal of immunology最新文献

IFN regulatory factors (IRFs) are transcription factors that mediate homeostatic mechanisms of host defense against pathogens. In addition to IRF1-9, which are conserved across vertebrates, teleost fishes have two other IRFs, IRF10 and IRF11. In zebrafish (Danio rerio), IRF10 represses the expression of IFNφ1 and IFNφ3, whereas IRF11 exerts the opposite effect. In this study, we found IRF10 could significantly inhibit the expression of IFNφ1 and IFNφ3 induced by IFN11 to synergistically regulate type I IFN expression. To clarify the synergistically regulatory mechanism of IRF10 and IRF11 in type I IFN expression, we determined and analyzed the crystal structures of the DNA-binding domains (DBDs) of zebrafish IRF10 and IRF11 bound to DNA, as well as IRF11 DBD in apo form. The interactions of IRF10-DBD and IRF11-DBD with DNA backbone were elaborated in detail. Further analysis showed that IRF10 and IRF11 have the same binding patterns and comparable affinities with the IFN-sensitive response elements of IFNφ1 and IFNφ3 promoters. Therefore, IRF10 could function as a controlling factor for IRF11 by competitive binding of the IFN-sensitive response elements to coregulate the host IFN response. Accordingly, similar to IRF1 and IRF2 in mammals, IRF10 and IRF11 act as another pair of negative and positive regulators to balance the antiviral responses in fish.

Endometriosis, affecting 10% of women, is defined as implantation, survival, and growth of endometrium-like/endometriotic tissue outside the uterine cavity, causing inflammation, infertility, pain, and susceptibility to ovarian cancer. Despite extensive studies, its etiology and pathogenesis are poorly understood and largely unknown. The prevailing view is that the immune system of endometriosis patients fails to clear ectopically disseminated endometrium from retrograde menstruation. Exosomes are small extracellular vesicles that exhibit immunomodulatory properties. We studied the role of endometriotic tissue-secreted exosomes in the pathophysiology of endometriosis. Two exosome-mediated mechanisms known to impair the immune response were investigated: 1) downregulation of NKG2D-mediated cytotoxicity and 2) FasL- and TRAIL-induced apoptosis of activated immune cells. We showed that secreted endometriotic exosomes isolated from supernatants of short-term explant cultures carry the NKG2D ligands MICA/B and ULBP1-3 and the proapoptotic molecules FasL and TRAIL on their surface, i.e., signature molecules of exosome-mediated immune suppression. Acting as decoys, these exosomes downregulate the NKG2D receptor, impair NKG2D-mediated cytotoxicity, and induce apoptosis of activated PBMCs and Jurkat cells through the FasL- and TRAIL pathway. The secreted endometriotic exosomes create an immunosuppressive gradient at the ectopic site, forming a "protective shield" around the endometriotic lesions. This gradient guards the endometriotic lesions against clearance by a cytotoxic attack and creates immunologic privilege by induction of apoptosis in activated immune cells. Taken together, our results provide a plausible, exosome-based mechanistic explanation for the immune dysfunction and the compromised immune surveillance in endometriosis and contribute novel insights into the pathogenesis of this enigmatic disease.

The role of ICOS in antitumor T cell responses and overall tumor progression has been controversial. In this study, we compared tumor progression in mice lacking ICOS selectively in regulatory T (Treg) cells or in all T cells. Using an experimental melanoma lung metastasis model, we found that Treg cell-specific ICOS knockout reduces the overall tumor burden compared with Cre control mice, with increased CD4+-to-Treg cell and CD8+-to-Treg cell ratios in the tumor. In contrast, there was no difference in the tumor burden in mice lacking ICOS in all of the T cell compartments. This suggests a dual role of ICOS costimulation in promoting protumor and antitumor T cell responses. Consistent with reduced tumor burden, we found that Treg cell-specific deletion of ICOS leads to an increase of CD8+ CTLs that express high levels of granzyme B and perforin. Moreover, single-cell transcriptome analysis revealed an increase of Ly108+Eomeshi CD8+ T cells at the cost of the Ly108+T-bethi subset in Treg cell-specific knockout mice. These results suggest that ICOS-expressing Treg cells suppress the CTL maturation process at the level of Eomes upregulation, a critical step known to drive perforin expression and cytotoxicity. Collectively, our data imply that cancer immunotherapies using ICOS agonist Abs may work better in Treg cell-low tumors or when they are combined with regimens that deplete tumor-infiltrating Treg cells.

Activation of β-catenin in CD4+CD8+ double-positive (DP) thymocytes halts development before the thymic selection stage and predisposes to transformation. Leukemogenesis, but not the developmental block, depends on TCF-1, β-catenin's DNA-binding partner. In this study, we show that β-catenin activation directs the DNA-binding protein HEB to block DP thymocyte development. Conditional loss of HEB in DP thymocytes with stabilized β-catenin restores the frequencies of postselection TCRβhi/CCR7+ and TCRβhi/CD69+ DPs and their cell-cycle profile. This recovery is associated with significant reversal of β-catenin-induced expression changes, particularly those related to the CD69+ DP cell signature and to cell-cycle pathways. Stabilizing β-catenin in DP thymocytes directs HEB binding to ≈11,000 novel DNA sites throughout the genome. Novel HEB sites mark most CD69+ DP cell signature genes that change expression upon activation of β-catenin and then revert after loss of HEB. Moreover, many of the novel HEB sites occupy promoter regions of genes enriched in mitotic cell cycle pathways. HEB binding to those regions correlates with downregulation of the associated genes, and HEB inactivation restores expression to physiologic levels. These findings highlight a molecular interplay between HEB and β-catenin that can impair thymic development.

Top Reads. 2024. J. Immunol. 213:245. A third summary for the article titled "Obesity inhibits alveolar macrophage responses to Pseudomonas aeruginosa pneumonia via upregulation of PGE2 in male, but not female mice" by Gabrielle P. Entrup, Aayush Unadkat, Helen I. Warheit-Niemi, Brooke Thomas, Stephen J. Gurczynski, Yuxiao Cui, Andrew M. Smith, Katherine A. Gallagher, Bethany B. Moore, and Kanakadurga Singer was inadvertently excluded from the Top Reads' summary in the August 1, 2024 issue and appears below. Obesity Inhibits Alveolar Macrophage Responses to Pneumonia Obesity is associated with increased morbidity and mortality during bacterial pneumonia. Cyclooxygenase-2 (COX-2) and PGE2 have been shown to be upregulated in patients who are obese. In this study, we investigated the role of obesity and PGE2 in bacterial pneumonia and how inhibition of PGE2 improves antibacterial functions of macrophages. C57BL/6J male and female mice were fed either a normal diet (ND) or high-fat diet (HFD) for 16 wk. After this time, animals were infected with Pseudomonas aeruginosa in the lung. In uninfected animals, alveolar macrophages were extracted for either RNA analysis or to be cultured ex vivo for functional analysis. HFD resulted in changes in immune cell numbers in both noninfected and infected animals. HFD animals had increased bacterial burden compared with ND animals; however, male HFD animals had higher bacterial burden compared with HFD females. Alveolar macrophages from HFD males had decreased ability to phagocytize and kill bacteria and were shown to have increased cyclooxygenase-2 and PGE2. Treating male, but not female, alveolar macrophages with PGE2 leads to increases in cAMP and decreased bacterial phagocytosis. Treatment with lumiracoxib-conjugated nanocarriers targeting alveolar macrophages improves bacterial phagocytosis and clearance in both ND and HFD male animals. Our study highlights that obesity leads to worse morbidity during bacterial pneumonia in male mice because of elevated PGE2. In addition, we uncover a sex difference in both obesity and infection, because females produce high basal PGE2 but because of a failure to signal via cAMP do not display impaired phagocytosis. This has been corrected in the online version of the article, which now differs from the print version as originally published.

The Nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome has been the most distinctive polymer protein complex. After recognizing the endogenous and exogenous danger signals, NLRP3 can cause inflammation by pyroptosis and secretion of mature, bioactive forms of IL-1β and IL-18. The NLRP3 inflammasome is essential in the genesis and progression of infectious illnesses. Herein, we provide a comprehensive review of the NLRP3 inflammasome in infectious diseases, focusing on its two-sided effects. As an essential part of host defense with a protective impact, abnormal NLRP3 inflammasome activation, however, result in a systemic high inflammatory response, leading to subsequent damage. In addition, scientific evidence of small molecules, biologics, and phytochemicals acting on the NLRP3 inflammasome has been reviewed. We believe that the NLRP3 inflammasome helps us understand the pathological mechanism of different stages of infectious diseases and that inhibitors targeting the NLRP3 inflammasome will become a new and valuable research direction for the treatment of infectious diseases.

Neutrophils accumulate early in tissue injury. However, the cellular and functional heterogeneity of neutrophils during homeostasis and in response to tissue damage remains unclear. In this study, we use larval zebrafish to understand neutrophil responses to thermal injury. Single-cell transcriptional mapping of myeloid cells during a 3-d time course in burn and control larvae revealed distinct neutrophil subsets and their cell-cell interactions with macrophages across time and conditions. The trajectory formed by three zebrafish neutrophil subsets resembles human neutrophil maturation, with varying transition patterns between conditions. Through ligand-receptor cell-cell interaction analysis, we found that neutrophils communicate more in burns in a pathway and temporal manner. Finally, we identified the correlation between zebrafish myeloid signatures and human burn severity, establishing GPR84+ neutrophils as a potential marker of early innate immune response in burns. This work builds a comparative single-cell transcriptomic framework to identify neutrophil markers of tissue damage using model organisms.

Granulomas are an important hallmark of Mycobacterium tuberculosis infection. They are organized and dynamic structures created when immune cells assemble around the sites of infection in the lungs that locally restrict M. tuberculosis growth and the host's inflammatory responses. The cellular architecture of granulomas is traditionally studied by immunofluorescence labeling of surface markers on the host cells. However, very few Abs are available for model animals used in tuberculosis research, such as nonhuman primates and rabbits, and secreted immunological markers such as cytokines cannot be imaged in situ using Abs. Furthermore, traditional phenotypic surface markers do not provide sufficient resolution for the detection of the many subtypes and differentiation states of immune cells. Using single-molecule fluorescence in situ hybridization (smFISH) and its derivatives, amplified smFISH and iterative smFISH, we developed a platform for imaging mRNAs encoding immune markers in rabbit and macaque tuberculosis granulomas. Multiplexed imaging for several mRNA and protein markers was followed by quantitative measurement of the expression of these markers in single cells. An analysis of the combinatorial expressions of these markers allowed us to classify the cells into several subtypes, and to chart their densities within granulomas. For one mRNA target, hypoxia-inducible factor-1α, we imaged its mRNA and protein in the same cells, demonstrating the specificity of the probes. This method paves the way for defining granular differentiation states and cell subtypes from transcriptomic data, identifying key mRNA markers for these cell subtypes, and then locating the cells in the spatial context of granulomas.

Monocytes and macrophages (Mos/Mϕs) play diverse roles in wound healing by adopting a spectrum of functional phenotypes; however, the regulation of such heterogeneity remains poorly defined. We enhanced our previously published Bayesian inference TF activity model, incorporating both single-cell RNA sequencing and single-cell ATAC sequencing data to infer transcription factor (TF) activity in Mos/Mϕs during skin wound healing. We found that wound Mos/Mϕs clustered into early-stage Mos/Mϕs, late-stage Mϕs, and APCs, and that each cluster showed differential chromatin accessibility and differential predicted TF activity that did not always correlate with mRNA or protein expression. Network analysis revealed two highly connected large communities involving a total of 19 TFs, highlighting TF cooperation in regulating wound Mos/Mϕs. This analysis also revealed a small community populated by NR4A1 and NFKB1, supporting a proinflammatory link between these TFs. Importantly, we validated a proinflammatory role for NR4A1 activity during wound healing, showing that Nr4a1 knockout mice exhibit decreased inflammatory gene expression in early-stage wound Mos/Mϕs, along with delayed wound re-epithelialization and impaired granulation tissue formation. In summary, our study provides insight into TF activity that regulates Mo/Mϕ heterogeneity during wound healing and provides a rational basis for targeting Mo/Mϕ TF networks to alter phenotypes and improve healing.

The cyclic GMP-AMP synthase (cGAS)-stimulator of IFN genes (STING) pathway is instrumental to antitumor immunity, yet the underlying molecular and cellular mechanisms are complex and still unfolding. A new paradigm suggests that cancer cells' cGAS-synthesized cGAMP can be transferred to tumor-infiltrating immune cells, eliciting STING-dependent IFN-β response for antitumor immunity. Nevertheless, how the tumor microenvironment may shape this process remains unclear. In this study, we found that extracellular ATP, an immune regulatory molecule widely present in the tumor microenvironment, can potentiate cGAMP transfer, thereby boosting the STING signaling and IFN-β response in murine macrophages and fibroblasts. Notably, genetic ablation or chemical inhibition of murine volume-regulation anion channel LRRC8/volume-regulated anion channel (VRAC), a recently identified cGAMP transporter, abolished ATP-potentiated cGAMP transfer and STING-dependent IFN-β response, revealing a crucial role of LRRC8/VRAC in the cross-talk of extracellular ATP and cGAMP. Mechanistically, ATP activation of the P2X family receptors triggered Ca2+ influx and K+ efflux, promoting reactive oxygen species production. Moreover, ATP-evoked K+ efflux alleviated the phosphorylation of VRAC's obligate subunit LRRC8A/SWELL1 on S174. Mutagenesis studies indicated that the phosphorylation of S174 on LRRC8A could act as a checkpoint for VRAC in the steady state and a rheostat of ATP responsiveness. In an MC38-transplanted tumor model, systemically blocking CD39 and ENPP1, hydroxylases of extracellular ATP and cGAMP, respectively, elevated antitumor NK, NKT, and CD8+ T cell responses and restrained tumor growth in mice. Altogether, this study establishes a crucial role of ATP in facilitating LRRC8/VRAC transport cGAMP in the tumor microenvironment and provides new insight into harnessing cGAMP transfer for antitumor immunity.