InVivoMAb anti-mouse CD3ε

Immune checkpoint blockade (ICB) faces limitations owing to high cost and restricted efficacy. This study identifies SNX17 as a key mediator of ICB resistance. Elevated SNX17 correlates with poor anti-PD-1 response in humans and mice. SNX17 deletion in tumor cells inhibits tumor growth via CD8+ T cell-dependent mechanisms. SNX17 reduces uridine in the tumor microenvironment (TME), suppressing IFN-γ and upregulating PD1 in CD8+ T cells. Exogenous uridine shows antitumor efficacy comparable to anti-PD-1/PD-L1 in low-SNX17 tumors and overcomes resistance in high-SNX17 models. Uridine enhances CD8+ T cell function by promoting CD45 N-glycosylation and LCK phosphorylation. Mechanistically, SNX17 stabilizes RUNX2, promoting UPP1 transcription and uridine degradation in the TME. These findings position SNX17 as an ICB response biomarker and nominate uridine as a cost-effective immunotherapeutic strategy.

Interferon-induced transmembrane protein 1 (IFITM1) restricts virus infection. IFITM proteins are involved in Th2 cell differentiation in allergic asthma. The epithelial‒mesenchymal transition (EMT) regulates allergic airway remodeling. We sought to explore the functional contributions and underlying mechanisms of IFITM1 in the EMT associated with allergic asthma.

Background: Immune checkpoint inhibitors are ineffective in the majority of colorectal cancers (CRCs) that are microsatellite stable. However, the underlying reasons for their unresponsiveness and mechanisms of immune evasion are poorly understood. In the present study, we aimed to elucidate the mechanisms underlying the immune evasion driven by CRC cells. Methods: We performed single-cell RNA sequencing of tumor tissues from 30 CRC patients and syngeneic mice implanted with transformation-related protein 53 (Trp53) knockout CT26 cells. Gene expression and correlations of individual tumor microenvironment (TME) components were analyzed, and their functional significance was investigated using syngeneic mouse models and cell line co-culture experiments. Results: CCAAT enhancer-binding protein beta (CEBPB) expression was increased in tumor protein 53 (TP53)-mutated CRCs. We confirmed that wild-type TP53 negatively regulated CEBPB expression in CRC cell lines. CEBPB expression was associated with decreased intratumoral T cell infiltration and negatively impacted survival in CRC patients. In the intercellular correlation analysis of gene expression, tumor epithelial cell CEBPB expression was significantly correlated with cytotoxic T-lymphocyte associated protein 4 (CTLA4) expression in T cells, especially in regulatory and exhausted T cells. Cebpb overexpression promoted tumor growth in the immunocompetent syngeneic mouse models, which was accompanied by increased CTLA-4 expression in tumor-infiltrating CD4+ T cells. In vitro co-culture experiments also showed that tumor cell CEBPB overexpression increased CTLA4 in T cells. Conclusions: Tumor cell CEBPB expression, up-regulated by TP53 mutation, can increase CTLA4 expression in T cells and negatively affect patient outcomes. These findings suggested a central role of tumor cell CEBPB in shaping an immunosuppressive TME.

Immune cell infiltration into the central nervous system is increasingly recognized as a driver of neurodegeneration, yet its role in Huntington's disease remains unresolved. Addressing this question requires models that replicate the selective vulnerability of striatal neurons observed in patients, a challenge unmet by rodent systems. Here we use a previously established and genetically engineered pig model carrying the human huntingtin mutation with an expanded cytosine-adenine-guanine repeat, enabling investigation of immune-neural interactions in a physiologically relevant context. Using single-nucleus and spatial transcriptomics, integrated with immunohistochemistry and T cell receptor sequencing, we constructed a cellular map of the striatum. We identified an interferon-responsive microglial state that secretes chemokine ligand eight, recruiting cytotoxic CD8-positive T cells that release perforin and granzyme, thereby accelerating neuronal loss. Functional experiments confirmed the pathogenic role of chemokine ligand eight and demonstrated that its neutralization mitigates neurodegeneration. These findings uncover a species-dependent immune mechanism in Huntington's disease and nominate chemokine ligand eight-mediated T cell infiltration as a therapeutic target.

Chronic low-grade inflammation is a hallmark of atherosclerosis and cardiovascular diseases, with monocytes playing a central role in sustaining this pathological state. In this study, we demonstrate that prolonged exposure to oxidized low-density lipoprotein (oxLDL) or cholesterol reprograms murine bone marrow-derived monocytes into a persistent pro-inflammatory phenotype. This is characterized by elevated surface markers (CD49d, CD74, CD38, CD86), enhanced endothelial and T cell interactions, and sustained activation of the Src-SYK-mTORC1-STAT3/5 signaling axis. Notably, the inflammatory state persisted even after stimulus withdrawal, suggesting the establishment of an immune memory-like phenotype. Mechanistically, we defined the membrane clustering of Src is responsible for the generation of intra-cellular stress signaling and sustained monocyte activation, which can be alleviated by the administration of fumagillin, a selective inhibitor of protein myristoylation and Src membrane clustering. Our findings uncover mechanistic insights into the generation of sustained monocyte low-grade inflammatory memory and pinpoint potential therapeutic strategies in erasing low-grade inflammation related to chronic diseases.

The involvement of intestinal microbiota in the process of neutrophil-mediated colorectal cancer liver metastasis (CRCLM) is not yet fully understood. Here, we show that Escherichia coli (E. coli) is prevalent in CRC tissues with LM using 2bRAD-M-Seq and is linked to the release of neutrophil extracellular traps (NETs). Utilizing multi-omics and molecular techniques, we establish that E. coli recruits RIPK2, which promotes the binding of HNRNPK to the Atf3/Relb promoters in neutrophils, thereby enhancing their transcription. This process results in the upregulation of Ncf4, which triggers p-MLKL-mediated NET formation. NETs, in turn, increase the expression of TRPC1 and NFATC3 in CRC cells, promoting the calcium-dependent assembly of the STAT3/S100A8/9 heterotrimer. This trimer stabilizes STAT3-enhancer-promoter loops (EPLs), thereby reinforcing the Tns1 transcription and facilitating CRCLM. Our findings elucidate the mechanism by which E. coli-induced NETs promote CRCLM through epigenetic modifications, offering an insight into the role of EPLs in immune regulation and tumor progression.

An adaptive immune response to cancer requires three main signals: antigen presentation and recognition ("signal 1"), costimulation ("signal 2"), and secreted immunostimulatory cytokines ("signal 3"). Expression of these signals in tumors via non-viral gene delivery represents a promising strategy to reprogram the tumor microenvironment (TME) and prime antitumor immunity.

Multiple sclerosis (MS) is a neurodegenerative autoimmune disease primarily mediated by T helper 17 (TH17) cells. We previously showed that Itch/WWP2 double knockout (DKO) T cells produce high levels of type 2 cytokines, driving spontaneous autoinflammation. Here, we report that DKO TH2-high carrying autoantigen-specific TCR (2D2) develop atypical spontaneous experimental autoimmune encephalomyelitis (EAE), with CD4+ T cells simultaneously producing IL-4 and GM-CSF, directly causing neuroinflammation. Unexpectedly, IL-4 deletion in DKO TH2-high 2D2 mice exacerbates TH17-driven classical EAE, indicating a TH2 to TH17 conversion. Furthermore, we show that the JAK3/STAT5 signaling pathway is critical for maintaining TH2 lineage stability by modulating Blimp1 and c-Maf thereby suppressing TH17 differentiation. Importantly, we find that this phenomenon can also be observed in dupilumab-treated patients with atopic dermatitis who develop psoriasis. Thus, our findings uncover the molecular antagonism and plasticity in the TH2 and TH17 cell programs and identify potential therapeutic targets for modulating TH2 and TH17 cell responses in autoimmune diseases.

DF6215 is a rationally engineered interleukin-2 (IL-2) Fc-fusion protein developed to overcome efficacy and safety limitations of traditional IL-2 cancer immunotherapy. Unlike non-alpha (non-α) IL-2 variants that eliminate CD25 binding and underperform clinically, DF6215 retains moderate IL-2 receptor α (IL-2Rα) affinity while enhancing IL-2Rβγ signaling and extending the half-life via an engineered immunoglobulin (Ig)G1 Fc domain. This design preferentially expands cytotoxic CD8+ T cells and natural killer cells over regulatory T cells, resulting in favorable effector-to-regulatory cell ratios, enhanced immune activation, and robust tumor regression in mouse models. In poorly immunogenic tumors, DF6215 synergized with PD-1 blockade to achieve durable responses without added toxicity. Cynomolgus monkey studies confirm DF6215's pharmacodynamics and favorable safety profile, with no signs of vascular leak syndrome or cytokine release syndrome. These findings position DF6215 as a differentiated IL-2 capable of modulating the tumor microenvironment and achieving potent anti-tumor immunity with improved tolerability, supporting its advancement into clinical trials for solid tumors.

CCR6 is a G-protein-coupled receptor that binds to its ligand CCL20. Th17 and Foxp3+CD4+ T cells express CCR6, enabling their migration to inflamed tissues with unique metabolic environments. The factors that regulate their metabolic adaptation and functional roles in these tissues remain unclear. Using inflammatory bowel disease patient samples and experimental colitis models in mice, we demonstrated that the intrinsic signaling of CCL20-CCR6 in CD4+ T cells promotes the differentiation of inflammatory Th1-like Th17 cells (T-bet+RORγt+) during colitis. This signaling induces the rapamycin-sensitive phosphorylation of PI3K, Akt, mTORC1, and STAT3 in a CCR6-dependent manner. RNA-seq and proteomics analysis revealed that the addition of CCL20 during Th17 differentiation affects several metabolic pathways, including energy metabolism. CCL20 significantly increased glycolysis and inhibited oxidative phosphorylation, thereby driving the differentiation of pathogenic Th17 cells. Our findings suggest that alterations in CCR6-induced changes in Th17 metabolism offer an interesting therapeutic target for gut inflammation and autoimmunity.

The AMPA receptor (AMPAR) is an ionotropic glutamate receptor that is essential for neuronal communication, yet its role in the immune system remains poorly understood. Here, using a CD4Cre selective deletion mouse model, we provide the first functional characterization of AMPAR deficient T cells. We demonstrate that AMPAR deletion in T cells significantly protects against severe paralysis in an experimental autoimmune encephalomyelitis (EAE) model, and this protection is associated with increased regulatory T cell (Treg) presence within the spinal cord. In vitro studies reveal that the deletion of the AMPAR intrinsically promotes Treg generation. Mechanistically, AMPAR deletion increases IL2 signaling and activates the mTORC1 pathway, supporting Treg development and function. These novel findings suggest that a function of the AMPAR in CD4 T cells is to limit immune suppression by restricting Treg differentiation. Targeting AMPARs on T cells could offer a novel therapeutic approach for the treatment of autoimmune disease.

FOXP3 is a lineage-defining transcription factor (TF) for immune-suppressive regulatory T cells (Treg cells). Although mice exclusively express FOXP3 in Treg cells, stimulated conventional CD4+ T cells (Tconv cells) also transiently express FOXP3 in humans. Mechanisms governing these distinct expression patterns need elucidation. Here, we performed CRISPR screens tiling the FOXP3 locus and targeting TFs in human Treg and Tconv cells to identify cis-regulatory elements (CREs) and trans-regulators of FOXP3. Tconv cell FOXP3 expression depended on a subset of Treg cell CREs, as well as Tconv-cell-selective positive (NS+) and negative (NS-) CREs. Combinatorial silencing of Tconv cell CREs revealed their epistatic logic. These CREs are occupied and regulated by TFs that we identified as FOXP3 regulators. Finally, mutagenesis of murine NS- CRE revealed its essentiality for restricting FOXP3 expression to Treg cells. We map CRE and TF circuitry to reveal distinct cell- and species-specific regulation of FOXP3 expression.

Antibiotics influence both gut microbial composition and immune regulation, but the detailed mechanisms are still undefined. Shifts in the microbiome caused by antibiotic exposure can modulate immune activity through various pathways. Therefore, we aimed to explore how antibiotics affect immune-inflammation by regulating Th17 cells through the gut microbiota of mice with experimental autoimmune prostatitis (EAP). Antibiotic-driven shifts in gut microbial communities and metabolite profiling in EAP mice were performed by integrating 16S rRNA sequencing with mass spectrometry-driven metabolomic analysis. Antibiotic cocktail (ABX) therapy mitigated EAP, modified the gut microbiome composition, and influenced bile acid metabolism. Fecal microbiota transplantation (FMT) using microbiota from ABX-treated feces into EAP mice effectively altered gut microbiome composition and alleviated disease symptoms, indicating that microbiome intervention reduces autoimmune inflammation and decreases deoxycholic acid (DCA) in mice. Subsequent experiments demonstrated that DCA suppresses farnesol X receptor (FXR) expression which can inhibit the NLRP3‒ IL17A axis, thus promoting Th17 cell development and exacerbating inflammatory cell infiltration of the prostate. Our initial clinical examination of patients with prostatitis and antibiotic treatment indicated that bile acid metabolism and Th17 cell development are affected by antibiotic therapy. This work revealed that antibiotic-induced gut microbiota dysbiosis decreases the bile acid metabolite DCA, further restraining Th17 cell differentiation via the FXR‒NLRP3 axis to alleviate autoimmune prostatitis. Our results reveal new perspectives regarding the interconnected dynamics of antibiotics, gut microbiota, bile acid metabolism, and immune regulation, with potential relevance for therapies targeting immune-mediated diseases.

Monocyte exhaustion is a dysfunctional state characterized by prolonged pathogenic inflammation and immune suppression, commonly observed in chronic infections and sepsis. However, the mechanisms underlying the generation and propagation of exhausted monocytes remain poorly understood. In this study, we investigate the impacts of exhausted monocytes on neighboring naïve monocytes, endothelial cells, and T cell function. Using an in vitro co-culture system, we demonstrate that exhausted monocytes induced by prolonged LPS stimulation propagate the exhaustion phenotype to neighboring naïve monocytes. Meanwhile these exhausted monocytes can promote endothelial apoptosis, upregulate adhesion molecules ICAM-1 and VCAM-1, and enhance monocyte transmigration, contributing to endothelial dysfunction. Pharmacological inhibition of CD38, a key marker of monocyte exhaustion, significantly mitigates these effects, highlighting its critical role in monocyte-driven endothelial alterations. Furthermore, we show that exhausted monocytes suppress T cell proliferation and activation, a process reversed by CD38 inhibition. We also identify mTOR signaling as a key regulator of monocyte exhaustion and its propagation, with mTOR inhibition partially restoring monocyte functionality by downregulating exhaustion markers and STAT1/STAT3/S6K signaling. Collectively, our findings highlight the CD38-mTOR axis as a central driver of monocyte exhaustion and its pathological consequences, offering potential therapeutic targets for reversing immune dysfunction in inflammatory diseases.

Tumor necrosis factor (TNF)-induced RIPK1-mediated cell death is implicated in various human diseases. However, the mechanisms RIPK1-mediated cell death is regulated by metabolic processes remain unclear. Here, we identify hexokinase 2 (HK2), a critical regulator of glycolysis, as a suppressor of TNF-induced RIPK1 kinase-dependent cell death through its non-metabolic function. HK2 inhibits RIPK1 kinase activity through constitutively phosphorylation at serine 32 of RIPK1. Inhibition of RIPK1 S32-phosphorylation results in RIPK1 kinase activation and subsequent cell death in response to TNFα stimulation. We further show that HK2 is elevated under pathological conditions including liver ischemia-reperfusion (IR) injury and hepatocellular carcinoma (HCC) via the transcriptional factor HMGA1. Moreover, the upregulation of HK2 in the liver confers protection against liver IR injury mediated by RIPK1 kinase, while depleting HK2 in HCC cells enhances TNFα-induced cell death and synergistically improves the efficacy of anti-PD1 therapy in an HCC model. Thus, the findings reveal a potential therapeutic avenue for RIPK1-related diseases through manipulating HK2 non-metabolic function.

Sepsis contributes substantially to mortality rates worldwide, yet clinical trials that have focused on its underlying pathogenesis have failed to demonstrate benefits. Recently, enhancing self-defense has been regarded as an emerging therapeutic approach. Autophagy is a self-defense mechanism that protects septic mice, but its regulatory factor is still unknown. Moreover, the role of interferon regulatory factor 7 (IRF7) in sepsis has been debated. Here, we showed that Irf7 deficiency increased mortality during polymicrobial sepsis. Furthermore, IRF7 drove macrophages to protect against sepsis. Mechanistically, IRF7 is a transcription factor that upregulates the expression of autophagy-related genes responsible for autophagosome formation and autolysosome maturation, induces autophagic killing of bacteria, and ultimately reduces septic organ injury. Recombinant adeno-associated virus 9-Irf7-mediated IRF7 overexpression promoted the autophagic clearance of pathogens and improved sepsis outcomes, which may be the mechanism underlying the observed improvement in bacterial clearance. These findings provide evidence that IRF7 is the underlying regulatory factor that drives autophagy to eliminate pathogens in macrophages during sepsis. Collectively, IRF7 overexpression represents a potential host-directed therapeutic strategy for preclinical sepsis models, operating independently of antibiotic mechanisms.

Sepsis is a life-threatening disease caused by a dysfunctional host response to infection. During sepsis, inflammation-related immunosuppression is the critical factor causing secondary infection and multiple organ dysfunction syndrome. The regulatory mechanisms underlying Treg differentiation and function, which significantly contribute to septic immunosuppression, require further clarification. In this study, we found that neutrophil extracellular traps (NETs) participated in the development of sepsis-induced immunosuppression by enhancing Treg differentiation and function via direct interaction with CD4+ T cells. Briefly, NETs anchored enolase 1 (ENO1) on the membrane of CD4+ T cells through its key protein myeloperoxidase (MPO) and subsequently recruited interferon-induced transmembrane protein 2 (IFITM2). IFITM2 acted as a DNA receptor that sensed NET-DNA and activated intracellular RAS-associated protein 1B (RAP1B) and its downstream ERK signaling pathway to promote Treg differentiation and function. ENO1 inhibition significantly attenuated NET-induced Treg differentiation and alleviated sepsis in mice. Overall, we demonstrated the role of NETs in sepsis-induced immunosuppression by enhancing Treg differentiation, identified ENO1 as an anchor of NET-MPO, and elucidated the downstream molecular mechanism by which IFITM2-RAP1B-ERK regulates Treg differentiation. These findings improve our understanding of the immunopathogenesis of sepsis and provide potential therapeutic targets for sepsis-induced immunosuppression.

Regulatory T (Treg) cells, expressing the transcription factor Foxp3, are obligatory gatekeepers of immune responsiveness, yet the mechanisms by which Foxp3 governs the Treg transcriptional network remain incompletely understood. Using a novel chemogenetic system of inducible Foxp3 protein degradation in vivo, we found that while Foxp3 was indispensable for the establishment of transcriptional and functional programs of newly generated Treg cells, Foxp3 loss in mature Treg cells resulted in minimal functional and transcriptional changes under steady state. This resilience of the Foxp3-dependent program in mature Treg cells was acquired over an unexpectedly long timescale; however, in settings of severe inflammation, Foxp3 loss led to a pronounced perturbation of Treg cell transcriptome and fitness. Furthermore, tumoral Treg cells were uniquely sensitive to Foxp3 degradation, which led to impairment in their suppressive function and tumor shrinkage in the absence of pronounced adverse effects. These studies demonstrate a context-dependent differential requirement for Foxp3 for Treg transcriptional and functional programs.

Mechanisms of T cell aging involve cell-intrinsic alterations and interactions with immune and stromal cells. Here we found that splenic T cells exhibit greater functional decline than lymph node T cells within the same aged mouse, prompting investigation into how the aged spleen contributes to T cell aging. Proteomic analysis revealed increased expression of heme detoxification in aged spleen-derived lymphocytes. Exposure to the heme- and iron-rich aged splenic microenvironment induced aging phenotypes in young T cells, including reduced proliferation and CD39 upregulation. T cells survived this hostile niche by maintaining a low labile iron pool, at least in part, via IRP2 downregulation to resist ferroptosis but failed to induce sufficient iron uptake for activation. Iron supplementation enhanced antigen-specific T cell responses in aged mice. This study identifies the aged spleen as a source of hemolytic signals that systemically impair T cell function, underscoring a trade-off between T cell survival and function and implicating iron metabolism in immune aging.