Journal of immunology最新文献

Endosomal toll-like receptors TLR7 and TLR8 are critical sensors of microbial RNA that initiate antiviral and antibacterial immune responses through type I interferon (IFN) and proinflammatory cytokine production. While TIRAP is traditionally associated with plasma membrane TLR signaling, recent evidence suggests that it also contributes to signaling via endosomal TLRs. Here, we examined the role of TIRAP in TLR7/8 signaling using P7-Pen, a novel SLAMF1-derived peptide that disrupts the TIRAP-MyD88 interaction. In primary human monocytes and a whole blood model, P7-Pen inhibited TLR7- and TLR8-induced expression and secretion of IRF5-regulated cytokines IFNβ, IL-12p40, and IL-12p70, without effect on TNF or IL-6. Mechanistically, P7-Pen blocked TIRAP recruitment to the TLR8-MyD88 complex, leading to reduced late-stage IRAK1 activation, Akt and IKKα/β phosphorylation, and downstream IRF5 dimerization and nuclear translocation. Inhibition of Staphylococcus aureus-induced cytokine production by P7-Pen was associated with reduced bacterial phagocytosis, impairing endosomal delivery of bacterial RNA. Notably, P7-Pen failed to inhibit murine TLR7 responses, which correlated with a lack of TIRAP recruitment to MyD88 in mouse macrophages following TLR7 ligand stimulation, highlighting species-specific differences in TLR signaling mechanisms. These findings support a noncanonical role for TIRAP in regulating IRF5-dependent signaling downstream of human TLR7 and TLR8, and demonstrate that selective disruption of TIRAP recruitment by a SLAMF1-derived peptide effectively attenuates IFNβ production. This strategy may hold therapeutic potential in diseases characterized by dysregulated type I IFN responses, such as systemic lupus erythematosus and chronic infections.

Since its approval in 2019, hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitors, like roxadustat, have been used for treatment of anemia in chronic kidney disease. However, the impact of HIF stabilization on circulating leukocytes remains largely unexplored. In this study, we examined how clinically relevant concentrations of roxadustat affect human PBMCs. We evaluated the effects of roxadustat on leukocyte viability, HIF pathway activation via protein and gene expression analysis, metabolic shifts through oxygen consumption and extracellular acidification, and immune subpopulation dynamics and activation through single-cell RNA sequencing. We also explored the effects of roxadustat combined with lipopolysaccharide to simulate conditions of inflammatory hypoxia. Roxadustat did not compromise PBMC viability, but triggered HIF-1α protein accumulation, glycolytic reprogramming, and cytokine gene expression. Single-cell RNA sequencing revealed shifts in leukocyte subpopulations, and a combined treatment with lipopolysaccharide showed an enhanced inflammatory response. We found roxadustat to be a modulator of immune activity, revealing its potential to activate specific leukocyte subpopulations and amplify inflammatory responses. Our study sheds new light on the immunological dimensions of HIF stabilization and its implications for patient care, urging further exploration of its therapeutic and safety profile.

The National Institutes of Health-funded IMPACC (IMmunoPhenotyping Assessment in a COVID-19 Cohort) evaluated longitudinal clinical and immunological features of human patients hospitalized for COVID-19. This study focuses on comparing the novel NULISAseq assay with the Olink platform using a subset of participants to assess their efficacy in predicting COVID-19 severity and understanding immune response dynamics. Our findings reveal that NULISAseq could provide superior detectability and dynamic range across various targets. Elastic net analysis demonstrated that specific proteins, including amphiregulin, effectively predict COVID-19 severity from sera at admission (samples drawn within 96 h of admission), with a test area under the curve of 0.84. Longitudinal analysis identified significant differences in multiple targets, including IL-5 and interferons, between low- and high-severity groups over time. Additionally, association rule mining suggested potential early markers predictive of later immune cell changes. These findings emphasize the potential of NULISAseq for comprehensive profiling, early prediction, and identification of targeted therapeutic interventions in COVID-19.

CD8 T cell exhaustion has been reported in mice susceptible to Toxoplasma gondii infection. While the differentiation of CD8 exhausted subsets has been extensively reported, most of these studies have been conducted in chronic viral and cancer models. During chronic T. gondii infection, phenotypic and transcriptomic analyses of the polyclonal antigen-specific CD8 T cell response characterize 4 populations based on KLRG1 and CD62L expression. Pop1 (KLRG1+CD62Llo) bears the attributes of a terminal effector subset, and pop2 (KLRG1-CD62Llo) is similar to effector memory CD8 T cells. Akin to chronic viral infection and cancer systems, pop3 (KLRG1-CD62Lhi) exhibits the characteristics of stem-like progenitor CD8 T cells (high Tcf7, Slamf6, and Cxcr5 expression), whereas pop4 (KLRG1+CD62Lhi) closely resembles a transitory subset (elevated Tbx21, low Tcf1, and Tox expression). During chronic viral infection, the stem-like progenitor CD8 T cells transition into a terminally differentiated exhausted subset via an intermediate population. However, in our system, pop3 (KLRG1-CD62Lhi) generates pop4 (KLRG1+CD62Lhi), which does not convert into a conventional terminally differentiated exhausted subset but instead transitions into effector pop1 (KLRG1+CD62Llo). Notably, during the chronic phase of the infection, pop1 cannot retain its functionality, irrespective of its origin, which may hamper its ability to control reactivation. Our observations emphasize that the differentiation of exhausted CD8 T cells in non-viral infections, like chronic toxoplasmosis, follows a different pattern than established models and highlights the need to develop new immune strategies better tailored for a broad range of pathogens.

Head and neck squamous cell carcinoma (HNSCC) constitutes 90% of head and neck cancers. HNSCC development is linked to chronic inflammation, while established HNSCC tumors are often immune suppressive. However, both occur through mechanisms that are not fully understood. The cytosolic double-stranded DNA sensor absent in melanoma 2 (AIM2) is an inflammasome-forming protein that also has inflammasome-distinct roles in restricting tumorigenesis by limited PI3K signaling. Here, we used an experimental mouse model of HNSCC, involving treatment of wild-type (WT) and Aim2-/- mice with the carcinogen 4NQO in drinking water. Compared with WT mice, 4NQO-treated Aim2-/- mice exhibited larger tumors and increased tissue dysplasia. 4NQO-treated WT and Aim2-/- mice displayed similar tongue Il6, Tnf, Il1b, Il12, and Il10 expression and no consistent differences in PI3K or inflammasome activation, suggesting AIM2 may not regulate these factors during HNSCC. Instead, Ifng and Irf1 was elevated in 4NQO-treated Aim2-/- mice, suggesting that AIM2 restricts IFN-γ. In line with this, RNA sequencing of total tongue RNA from 4NQO-treated mice revealed that Aim2-/- mice had enhanced expression of genes related to the major histocompatibility complex protein complex, cell killing, and T cell activation compared with WT mice. We also observed increased macrophage infiltration into the tongue epithelium of 4NQO-treated Aim2-/- mice and an increased M1:M2 macrophage ratio. Using Aim2-/-/Rag1-/- double-deficient animals, we found that the adaptive immune compartment was necessary for the enhanced tumorigenesis during AIM2 deficiency. These findings suggest that AIM2 limits the progression of oral tumor development partially through regulating IFN-γ and adaptive immune responses.

The tumor microenvironment (TME) plays a pivotal role in shaping immune responses and therapeutic outcomes in lung cancer, yet the diversity and functional specialization of tumor-associated macrophages (TAMs) remain poorly resolved. Here, we present a refined classification of TAM subtypes across large cohorts of cancer datasets using integrative analysis of single-cell RNA sequencing, spatial transcriptomics, and clinical datasets from lung adenocarcinoma and lung squamous cell carcinoma. By combining cell-based gene scoring with hierarchical classification, we defined 7 macrophage subtypes-each with distinct transcriptional programs and abundances. Notably, lipid-associated TAMs expand with disease progression and exhibit immunosuppressive and protumorigenic features, whereas tissue-resident macrophages decline. Spatial and survival analyses reveal that an increased lipid-associated to tissue-resident TAM ratio correlates with advanced disease and poor prognosis. Given that spatial transcriptomic assays rely on deconvolution techniques to infer cell type compositions, accurate gene expression signatures are essential, especially for fine-grained subpopulations of TAMs. Our refined subtype-specific signatures address this bottleneck and enhance the resolution of spatial mapping efforts. These findings offer new insights into macrophage heterogeneity and highlight lipid-associated TAMs as potential biomarkers and therapeutic targets in lung cancer.

Plasma cell survival is influenced by various factors, including soluble mediators, intrinsic and extrinsic signals as well as adhesion molecules defining the bone marrow microenvironment. The role of their induction, turnover and competition dynamics among different antigen-specific bone marrow plasma cell subsets is not well understood. This study addresses the co-expression of CD19 and CD56 on both antigen-specific and total human bone marrow plasma cells (BMPC) using multiparametric flow cytometry and data from a previous single-cell RNA sequencing (scRNA-seq) study. While the RNA-seq data reflects characteristics of total BMPC, flow cytometry data enables detailed comparison of antigen-specific subsets, such as tetanus toxoid (TT)- and receptor binding domain (RBD, a region of the SARS-CoV-2 spike protein)-specific BMPC. CD56 expression is enriched among CD19- BMPC, particularly on those expressing IgG. RBD-specific BMPC typically lack CD56 expression, while TT-specific BMPC exhibit a substantially enriched CD56+CD19- BMPC population. Phenotypic and transcriptional characteristics (CD19 and NCAM1 [CD56] co-expression) together with distinct transcriptional profiles (including cell-cell adhesion, endopeptidase activity) and IgG/IgA expression identified remarkable differences between RBD-specific and TT-specific BMPC. These findings suggest that CD56 likely facilitates tissue retention of rather long-lived BMPC lacking CD19 expression. Given the emerging potential of selective BMPC subsets, this study may provide a rational for optimized vaccination protocols, as well as for selective plasma-cell targeting in autoimmunity. In this context, CD56+CD19- BMPC emerge as potential candidates for a long-lived and stable compartment.

The transcriptional regulatory elements and epigenetic modifiers predominantly control the molecular pathways influencing the development of the immune system. Recently, microRNAs (miRNAs) have emerged as a new class of immune system regulators, playing an indispensable role in the ontogenesis, differentiation, activation, and function of lymphoid cells. In this review, we discuss recent advances in our understanding of how miRNAs shape the adaptive arms of immunity, focusing primarily on B-cell lymphopoiesis, activation, and antibody diversification. We also review an additional mode of RAG regulation by miRNAs in a developmental stage-specific manner. Furthermore, we discuss the use of miRNAs as biomarkers in cancer, given their aberrant and unique expression profiles in solid and liquid tumors, as well as in autoimmune disorders. Gaining deeper insights into miRNA biology will open up novel targeted therapies against dysregulated miRNAs in immunological disorders in the future.

Impaired phagocytosis of macrophages was observed in the salivary glands (SGs) of Sjogren's syndrome (SS). This study aims to investigate the dynamic changes of extracellular high mobility group box 1 (HMGB1) within these tissue microenvironments and its roles in macrophage function and subsequent gland dysfunction in SS. Our study detected a gradual increase in the expression and extracellular translocation of HMGB1 in the SGs of SS. Notably, this increased HMGB1 expression was negatively correlated with saliva associated AQP5 expression. Furthermore, elevated macrophages predominantly located around the duct, acinar, and infiltrate foci within the SGs expressed Toll-like receptor 4 and showed an M1 phenotype. Recombinant HMGB1 stimulation resulted in increased expression of major histocompatibility complex class II and a reduced phagocytic capacity of macrophages in vitro. Moreover, treatment with glycyrrhizin, a natural HMGB1 inhibitor, led to a significant improvement of saliva flow rates and a reduction of inflammatory cell infiltration and autoantibody levels when compared with phosphate-buffered saline-treated SS-like NOD/ShiLtJ mice. Our findings demonstrate that extracellular HMGB1 exacerbates the inflammatory-autoimmune microenvironments in SGs, suggesting that glycyrrhizin treatment may serve as a promising natural inhibitor for the management of SS.

Fibroblasts participate in inflammatory responses and play a critical role in the switch from acute to persistent inflammation. Whether fibroblast responses are modulated by signals from their microenvironment is not well established. Insulin signaling and insulin resistance modulate responsiveness of innate immune cells to inflammatory signals. Herein, we investigated whether fibroblast responsiveness is affected by the tissue microenvironment. As a source of fibroblasts, we used ligamentum flavum-derived fibroblasts, being a tissue that is inflamed in the context of ligamentum flavum hypertrophy. The results showed that fibroblasts from patients with ligamentum flavum hypertrophy were hyporesponsive to TLR2 signals. Since ligamentum flavum hypertrophy is associated with obesity, we utilized ligamentum flavum-derived fibroblasts from obese and lean mice. Fibroblasts from insulin-resistant obese mice expressed increased Collagen1a1 and produced more IL-6 in response to TLR2 and TLR4 signals. Insulin signaling was altered in ligamentum flavum-derived fibroblasts from obese mice, resulting in reduced insulin-induced AKT1 phosphorylation and increased insulin-induced AKT2 phosphorylation. Ligamentum flavum-derived fibroblasts from AKT2-deficient mice were hyporesponsive to TLR signals, in contrast to these from obese mice, suggesting that active AKT2 signaling is required to support responsiveness of fibroblasts. Basal respiration and stress-induced glycolysis were elevated in fibroblasts from AKT2-/- and obese mice, suggesting that even though their response to TLR signaling differs, they exhibited similar metabolic changes. The results suggest that responsiveness of fibroblasts is altered in the context of obesity and insulin resistance and is controlled by the balance of AKT1/AKT2 activation, which may be critical to the development of hypertrophy.