Journal of immunology最新文献

Recruitment of immune cells to the injury site plays a pivotal role in the pathology of radiation-associated diseases. In this study, we investigated the impact of the chemokine CCL22 released from alveolar type II epithelial (AT2) cells after irradiation on the recruitment and functional changes of dendritic cells (DCs) in the development of radiation-induced lung injury (RILI). By examining changes in CCL22 protein levels in lung tissue of C57BL/6N mice with RILI, we discovered that ionizing radiation increased CCL22 expression in irradiated alveolar AT2 cells, as did MLE-12 cells after irradiation. A transwell migration assay revealed that CCL22 promoted the migration of CCR4-positive DCs to the injury site, which explained the migration of pulmonary CCR4-positive DCs in RILI mice in vivo. Coculture experiments demonstrated that, consistent with the response of regulatory T cells in the lung tissue of RILI mice, exogenous CCL22-induced DCs promoted regulatory T cell proliferation. Mechanistically, we demonstrated that Dectin2 and Nr4a2 are key targets in the CCL22 signaling pathway, which was confirmed in pulmonary DCs of RILI mice. As a result, CCL22 upregulated the expression of PD-L1, IL-6, and IL-10 in DCs. Consequently, we identified a mechanism in which CCL22 induced DC tolerance through the CCR4-Dectin2-PLC-γ2-NFATC2-Nr4a2-PD-L1 pathway. Collectively, these findings demonstrated that ionizing radiation stimulates the expression of CCL22 in AT2 cells to recruit DCs to the injury site and further polarizes them into a tolerant subgroup of CCL22 DCs to regulate lung immunity, ultimately providing potential therapeutic targets for DC-mediated RILI.

T cells producing IFN-γ have long been considered a stalwart for immune protection against Mycobacterium tuberculosis (Mtb), but their relative importance to pulmonary immunity has been challenged by murine studies that achieved protection by adoptively transferred Mtb-specific IFN-γ-/- T cells. Using IFN-γ-/- T cell chimeric mice and adoptive transfer of IFN-γ-/- T cells into TCRβ-/-δ-/- mice, we demonstrate that control of lung Mtb burden is in fact dependent on T cell-derived IFN-γ, and, furthermore, mice selectively deficient in T cell-derived IFN-γ develop exacerbated disease compared with T cell-deficient control animals, despite equivalent lung bacterial burdens. Deficiency in T cell-derived IFN-γ skews infected and bystander monocyte-derived macrophages to an alternative M2 phenotype and promotes neutrophil and eosinophil influx. Our studies support an important role for T cell-derived IFN-γ in pulmonary immunity against tuberculosis.

Metabolic dysfunction-associated steatohepatitis (MASH) is characterized by infiltration of monocyte-derived macrophages (MdMs) into the liver; however, the function of these macrophages is largely unknown. We previously demonstrated that a population of MdMs, referred to as hepatic lipid-associated macrophages (LAMs), assemble into aggregates termed hepatic crown-like structures in areas of liver fibrosis. Intriguingly, decreasing MdM recruitment resulted in increased liver fibrosis, suggesting that LAMs contribute to antifibrotic pathways in MASH. In this study, we determined that hepatic crown-like structures are characterized by intimate interactions between activated hepatic stellate cells (HSCs) and macrophages in a collagen matrix in a mouse model of MASH. MASH macrophages displayed collagen-degrading capacities, and HSCs derived from MASH livers promoted expression of LAM marker genes and acquisition of a collagen-degrading phenotype in naive macrophages. These data suggest that crosstalk between HSCs and macrophages may contribute to collagen degradation MASH.

Alveolar macrophages (AMs) and recruited monocyte-derived macrophages (MDMs) mediate early lung immune responses to Mycobacterium tuberculosis. Differences in the response of these distinct cell types are poorly understood and may provide insight into mechanisms of tuberculosis pathogenesis. The objective of this study was to determine whether M. tuberculosis induces unique and essential antimicrobial pathways in human AMs compared with MDMs. Using paired human AMs and 5-d MCSF-derived MDMs from six healthy volunteers, we infected cells with M. tuberculosis H37Rv for 6 h, isolated RNA, and analyzed transcriptomic profiles with RNA sequencing. We found 681 genes that were M. tuberculosis dependent in AMs compared with MDMs and 4538 that were M. tuberculosis dependent in MDMs, but not AMs (false discovery rate [FDR] < 0.05). Using hypergeometric enrichment of DEGs in Broad Hallmark gene sets, we found that type I and II IFN Response were the only gene sets selectively induced in M. tuberculosis-infected AM (FDR < 0.05). In contrast, MYC targets, unfolded protein response and MTORC1 signaling, were selectively enriched in MDMs (FDR < 0.05). IFNA1, IFNA8, IFNE, and IFNL1 were specifically and highly upregulated in AMs compared with MDMs at baseline and/or after M. tuberculosis infection. IFNA8 modulated M. tuberculosis-induced proinflammatory cytokines and, compared with other IFNs, stimulated unique transcriptomes. Several DNA sensors and IFN regulatory factors had higher expression at baseline and/or after M. tuberculosis infection in AMs compared with MDMs. These findings demonstrate that M. tuberculosis infection induced unique transcriptional responses in human AMs compared with MDMs, including upregulation of the IFN response pathway and specific DNA sensors.

The interactions between chemokines and their receptors, particularly in the context of inflammation, are complex, with individual receptors binding multiple ligands and individual ligands interacting with multiple receptors. In addition, there are numerous reports of simultaneous coexpression of multiple inflammatory chemokine receptors on individual inflammatory leukocyte subtypes. Overall, this has previously been interpreted as redundancy and proposed as a protective mechanism to ensure that the inflammatory response is robust. By contrast, we have hypothesized that the system is not redundant but exquisitely subtle. Our interests relate to the receptors CCR1, CCR2, CCR3, and CCR5, which, together, regulate nonneutrophilic myeloid cell recruitment to inflammatory sites. In this study, we demonstrate that although most murine monocytes exclusively express CCR2, there is a small subpopulation that is expanded during inflammation and coexpresses CCR1 and CCR2. Combinations of transcript and functional analysis demonstrate that this is not redundant expression and that coexpression of CCR1 and CCR2 marks a phenotypically distinct population of monocytes characterized by expression of genes otherwise typically associated with neutrophils. Single-cell RNA sequencing confirms this as a monodisperse population of atypical monocytes. This monocytic population has previously been described as having immunosuppressive activity. Overall, our data confirm combinatorial chemokine receptor expression by a subpopulation of monocytes but demonstrate that this is not redundant expression and marks a discrete monocytic population.

ATPase cation transporting 13A2 (ATP13A2) is an endolysosomal P-type ATPase known to be a polyamine transporter, explored mostly in neurons. As endolysosomal functions are also crucial in innate immune cells, we aimed to explore the potential role of ATP13A2 in the human immunocellular compartment. We found that human plasmacytoid dendritic cells (pDCs), the professional type I IFN-producing immune cells, especially have a prominent enrichment of ATP13A2 expression in endolysosomal compartments. ATP13A2 knockdown in human pDCs interferes with cytokine induction in response to TLR9/7 activation in response to bona fide ligands. ATP13A2 plays this crucial role in TLR9/7 activation in human pDCs by regulating endolysosomal pH and mitochondrial reactive oxygen generation. This (to our knowledge) hitherto unknown regulatory mechanism in pDCs involving ATP13A2 opens up a new avenue of research, given the crucial role of pDC-derived type I IFNs in protective immunity against infections as well as in the immunopathogenesis of myriad contexts of autoreactive inflammation.

Atopic dermatitis results in diminished barrier function and altered production of antimicrobial peptides. Dendritic epidermal T cells (DETCs) play an important role in the wound repair and inflammation process. Our previous work identified an IL-4-dependent loss of DETCs in Stat6VT mice and in the MC903-induced skin inflammation mouse model. However, the mechanisms through which IL-4 mediates the loss of DETCs are unclear. In this study, we show that IL-4Rα germline knockout mice (Il4ra-/-) have increased DETCs, faster wound healing, and increased epidermal differentiation complex gene and fibronectin expression. The absence of IL-4Rα minimized the MC903-induced loss of DETCs, and reciprocal bone marrow chimera experiments in Il4ra-/- and wild-type mice demonstrated structural nonhematopoietic IL-4-responsive cell-mediated DETC homeostasis. Skin keratinocyte-derived IL-15 decreased dramatically in the MC903 model, while injection of IL-15 rescued DETC loss by promoting DETC proliferation and limiting apoptosis. Conditional deletion of IL-4Rα from keratinocytes using Il4rafl/fl K14-Cre mice showed an increase of DETCs, increased IL-15 production, and diminished skin inflammation following wounding. These results suggest that IL-4-dependent effects on DETCs in allergic skin inflammation are mediated by the IL-4Rα receptor of keratinocytes.

Endogenous retroviruses (ERVs) are involved in autoimmune diseases such as type 1 diabetes (T1D). ERV gene products homologous to murine leukemia retroviruses are expressed in the pancreatic islets of NOD mice, a model of T1D. One ERV gene, Gag, with partial or complete open reading frames (ORFs), is detected in the islets, and it contains many sequence variants. An amplicon deep sequencing analysis was established by targeting a conserved region within the Gag gene to compare NOD with T1D-resistant mice or different ages of prediabetic NOD mice. We observed that the numbers of different Gag variants and ORFs are linked to T1D susceptibility. More importantly, these numbers change during the course of diabetes development and can be quantified to calculate the levels of disease progression. Sequence alignment analysis led to identification of additional markers, including nucleotide mismatching and amino acid consensus at specific positions that can distinguish the early and late stages, before diabetes onset. Therefore, the expression of sequence variants and ORFs of ERV genes, particularly Gag, can be quantified as biomarkers to estimate T1D susceptibility and disease progression.

High-dose (HD) IL-2 was the first immuno-oncology agent approved for treating advanced renal cell carcinoma and metastatic melanoma, but its use was limited because of substantial toxicities. Multiple next-generation IL-2 agents are being developed to improve tolerability. However, a knowledge gap still exists for the genomic markers that define the target pharmacology for HD IL-2 itself. In this retrospective observational study, we collected PBMC samples from 23 patients with metastatic renal cell carcinoma who were treated with HD IL-2 between 2009 and 2015. We previously reported the results of flow cytometry analyses. In this study, we report the results of our RNA-sequencing immunogenomic survey, which was performed on bulk PBMC samples from immediately before (day 1), during (day 3), and after treatment (day 5) in cycle 1 and/or cycle 2 of the first course of HD IL-2. As part of a detailed analysis of immunogenomic response to HD IL-2 treatment, we analyzed the changes in individual genes and immune gene signatures. By day 3, most lymphoid cell types had transiently decreased, whereas myeloid transcripts increased. Although most genes and/or signatures generally returned to pretreatment expression levels by day 5, certain ones representative of B cell, NK cell, and T cell proliferation and effector functions continued to increase, along with B cell (but not T cell) oligoclonal expansion. Regulatory T cells progressively expanded during and after treatment. They showed strong negative correlation with myeloid effector cells. This detailed RNA-sequencing immunogenomic survey of IL-2 pharmacology complements results of prior flow cytometry analyses. These data provide valuable pharmacological context for assessing PBMC gene expression data from patients dosed with IL-2-related compounds that are currently in development.