CXCL10 chemokine regulates heterogeneity of the CD8+ T cell response and viral set point during chronic infection

Lymphatic chain gradients regulate the magnitude and heterogeneity of T cell responses to vaccination

Upon activation, T cells proliferate and differentiate into diverse populations, including highly differentiated effector and memory precursor subsets. Initial diversification is influenced by signals sensed during T cell priming within lymphoid tissues. However, the rules governing how cellular heterogeneity is spatially encoded in vivo remain unclear. Here, we show that immunization establishes concentration gradients of antigens and inflammation across interconnected chains of draining lymph nodes (IC-LNs). While T cells are activated at all sites, individual IC-LNs elicit divergent responses: proximal IC-LNs favor the generation of effector cells, whereas distal IC-LNs promote formation of central memory precursor cells. Although both proximal and distal sites contribute to anamnestic responses, T cells from proximal IC-LNs preferentially provide early effector responses at inflamed tissues. Conversely, T cells from distal IC-LNs demonstrate an enhanced capacity to generate long-lasting responses to chronic antigens in cancer settings, including after checkpoint blockade therapy. Therefore, formation of spatial gradients across lymphatic chains following vaccination regulates the magnitude, heterogeneity, and longevity of T cell responses.

Transient inhibition of type I interferon enhances CD8+ T cell stemness and vaccine protection

Developing vaccines that promote CD8+ T cell memory is a challenge for infectious disease and cancer immunotherapy. TCF-1+ stem cell-like memory CD8+ T (TSCM) cells are important determinants of long-lived memory. Yet, the developmental requirements for TSCM cell formation are unclear. Here, we identify the temporal window for type I interferon receptor (IFNAR) blockade to drive TSCM cell generation following viral infection and mRNA-lipid nanoparticle vaccination. We reveal a reversible developmental trajectory where transcriptionally distinct TSCM cells emerged from a transitional precursor of exhausted T cellular state concomitant with viral clearance. TSCM cell differentiation correlated with T cell retention within the lymph node paracortex due to disrupted CXCR3 chemokine gradient formation. These effects were linked to increased antigen load and a counterintuitive increase in IFNγ, which controlled cell location. Vaccination with the IFNAR blockade promoted TSCM cell differentiation and enhanced protection against chronic infection. These findings propose an approach to vaccine design whereby modulation of inflammation promotes memory formation and function.

The mechanism of EZH2/H3K27me3 downregulating CXCL10 to affect CD8+ T cell exhaustion to participate in the transformation from myelodysplastic syndrome to acute myeloid leukaemia

Myelodysplastic syndromes (MDS) and acute myeloid leukaemia (AML) link to unfavourable prognoses. We explored the mechanism of enhancer of zeste homologue 2/histone H3 of lysine 27 (EZH2/H3K27me3) downregulating C-X-C motif chemokine 10 (CXCL10) to affect CD8+ T-cell exhaustion, participating in MDS-to-AML transformation. NHD13 mice were treated with GSK126 (EZH2 inhibitor) and CXCL10 neutralizing antibody, with transformation time, blood cell counts and CD8+ T cell determined. SKM-1 cells treated with short hairpin-EZH2, overexpressing-EZH2, GSK126 and CXCL10 were co-cultured with CD8+ T cells. EZH2, CXCL10, H3K27me3 and EZH2 levels and EZH2 enzyme activity were assessed. CD8+ T-cell cytotoxicity, exhaustion, apoptosis and SKM-1 cell malignant behaviours were evaluated. In vivo, EZH2 inhibition upregulated CXCL10, decelerating MDS to AML transformation and delaying CD8+ T-cell exhaustion. EZH2 inhibition elevated peripheral blood cells, alleviated splenomegaly, reduced CD8+ T cells, elevated CD8+ T cytotoxicity and abated CD8+ T-cell exhaustion in NHD13 mice. CXCL10 neutralizing antibody accelerated AML transformation by inhibiting CD8+ T-cell exhaustion via EZH2. In vitro, EZH2 overexpression facilitated CD8+ T-cell exhaustion and SKM-1 cell malignant behaviours. EZH2-mediated H3K27me3 curbed CXCL10 transcription and secretion. Collectively, EZH2/H3K27me3 downregulates CXCL10 to facilitate CD8+ T-cell exhaustion, accelerating transformation from MDS to AML.

Loss of OBSCN expression promotes bladder cancer progression but enhances the efficacy of PD-L1 inhibitors

BACKGROUND

As the objective overall response rate to immune checkpoint inhibitors (ICIs) is less than 30% in late stage or metastatic bladder cancer (BLCA), elucidating the intrinsic mechanisms of immune evasion is of great importance for the discovery of predictive and prognostic biomarkers and the exploration of novel targets for intervention. Recent studies have shown that OBSCN and the cytoskeletal protein it encodes, obscurin, play an important role in tumour progression. However, no studies have reported the role of OBSCN in BLCA.

METHODS

RNA sequencing and clinical data were downloaded from multiple public databases including The Cancer Genome Atlas and the Gene Expression Omnibus. Immunohistochemistry (IHC) was performed on tissue microarrays including 80 BLCA patients from Shuguang Hospital. Kaplan-Meier curves with log-rank test, univariate and multivariate COX regression were performed to evaluate the prognostic efficacy of OBSCN expression. In vitro experiments were conducted to determine the role of OBSCN deficiency in promoting BLCA progression. Pan-cancer tumour immune microenvironment (TIME) analysis was performed to explore the potential correlation between OBSCN deficiency and immune evasion.

RESULTS

Pan-cancers and single-cell sequencing analysis revealed that the expression level and proportion of OBSCN was significantly decreased in BLCA cells compared to normal urothelium. Survival curves showed that BLCA patients with low OBSCN expression had a worse prognosis, yet a better clinical response to PD-L1 ICIs. Gene set variation analysis and Gene set enrichment analysis revealed that epithelial-mesenchymal transition (EMT) and immune-related processes were significantly enriched in BLCA samples with low OBSCN expression. In vitro experiments identified that OBSCN-deficient BLCA cells enhanced invasion, migration and EMT. Pan-cancer analysis of TIME revealed that neoantigen, tumor mutation burden, CD8+T cells and immune checkpoints were significantly negatively associated with OBSCN expression. IHC and Western blot assay identified that BLCA samples with low OBSCN expression had more CD8+ T-cell infiltration and higher PD-L1 expression.

CONCLUSIONS

This study confirmed that BLCA patients with low OBSCN expression had a worse prognosis but a superior response to ICIs, providing a reference for individualised treatment of BLCA patients.

Targeted delivery of CCL3 reprograms macrophage antigen presentation and enhances the efficacy of immune checkpoint blockade therapy in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related deaths worldwide, especially in advanced stages where limited treatment options result in poor prognosis. The immunosuppressive tumor immune microenvironment (TIME), characterized by low immune cell infiltration and exhaustion, limits immunotherapy efficacy. To address this, our study investigates the role of C-C motif chemokine ligand 3 (CCL3) in modulating the HCC TIME.

METHODS

We analyzed CCL3 expression in human HCC samples from The Cancer Genome Atlas database, focusing on its correlation with inflammatory gene signatures and immune cell infiltration. High-dimensional single-cell RNA sequencing (scRNA-seq), flow cytometry, and multiplex immunofluorescence were used to investigate CCL3's effects on macrophage function and T cell activation. The biological impact of CCL3 on macrophages was assessed using co-culture systems, confocal imaging, metabolite detection, and inhibition assays. Preclinical HCC models and ex vivo tumor fragment assays further explored how CCL3 modulates immune responses and enhances immune checkpoint blockade efficacy.

RESULTS

Our study shows that CCL3 is suppressed in the tumor microenvironment and positively correlates with immune infiltration and inflammatory responses. Targeted liver delivery of rAAV-Ccl3 reprograms the immune microenvironment in HCC, promoting immune cell recruitment and tertiary lymphoid structure formation, thus suppressing tumor growth via immune engagement. Through scRNA-seq, flow cytometry, and multiplex immunofluorescence, we found that CCL3 enhances macrophage antigen uptake and activates cytotoxic T cells. In vivo and in vitro experiments confirmed that CCL3 facilitates T cell infiltration and upregulates MHC II expression on macrophages, enhancing antigen presentation. The CCL3-CCR5 pathway also boosts macrophage metabolism, increasing lysosomal activity and antigen uptake, thereby strengthening adaptive immune responses and increasing sensitivity to immune checkpoint blockade therapies in preclinical models.

CONCLUSIONS

This study highlights the pivotal role of CCL3 in reshaping the TIME and enhancing antitumor immunity in HCC. By promoting immune cell recruitment and enhancing antigen presentation, CCL3 demonstrates significant potential to improve the efficacy of immunotherapy, particularly in combination with immune checkpoint inhibitors. Targeting CCL3 may help to overcome the immunosuppressive TIME in HCC and improve patient outcomes.

Inflammation switches the chemoattractant requirements for naive lymphocyte entry into lymph nodes

Sustained lymphocyte migration from blood into lymph nodes (LNs) is important for immune responses. The CC-chemokine receptor-7 (CCR7) ligand CCL21 is required for LN entry but is downregulated during inflammation, and it has been unclear how recruitment is maintained. Here, we show that the oxysterol biosynthetic enzyme cholesterol-25-hydroxylase (Ch25h) is upregulated in LN high endothelial venules during viral infection. Lymphocytes become dependent on oxysterols, generated through a transcellular endothelial-fibroblast metabolic pathway, and the receptor EBI2 for inflamed LN entry. Additionally, Langerhans cells are an oxysterol source. Ch25h is also expressed in inflamed peripheral endothelium, and EBI2 mediates B cell recruitment in a tumor model. Finally, we demonstrate that LN CCL19 is critical in lymphocyte recruitment during inflammation. Thus, our work explains how naive precursor trafficking is sustained in responding LNs, identifies a role for oxysterols in cell recruitment into inflamed tissues, and establishes a logic for the CCR7 two-ligand system.

Transcriptomics and microbiome insights reveal the protective mechanism of mulberry-derived postbiotics against inflammation in LPS-induced mice

Background

Natural food-derived bioactive compounds have garnered increasing attention for their potential to modulate immune responses and promote gut health. In particular, compounds like mulberry-derived postbiotics (MDP) may offer novel therapeutic strategies to address inflammation, a key driver of many metabolic disorders.

Methodology

This study examines the protective effects of MDP against inflammation in LPS-induced mice, using transcriptomic and microbiome analyses to explore underlying mechanisms.

Results

MDP pretreatment alleviates LPSinduced villous atrophy and intestinal barrier damage, promoting recovery of intestinal morphology. Transcriptomic profiling revealed significant changes in gene expression, with 983 upregulated and 1220 downregulated genes in the NC vs LPS comparison, and 380 upregulated and 204 downregulated genes in the LPS vs LPS+MDP comparison. Enrichment analysis using GO and KEGG pathways revealed significant associations with transcriptional regulatory activity, and the NOD-like receptor signaling pathway among the differentially expressed genes. Protein-protein interaction analysis identified key genes involved in inflammation and immune regulation, with hub genes like IL6, CXCL10, and MYD88 in the LPS group and CD74, CIITA, and H2-AB1 in the MDP-treated group.

Conclusion

Microbiome analysis suggested MDP may also influence gut microbiota composition, supporting systemic immune regulation. These findings highlight MDP's potential as a food additive for immune modulation and gut health.

Stem-like memory and precursors of exhausted T cells share a common progenitor defined by ID3 expression

Stem-like T cells are attractive immunotherapeutic targets in patients with cancer given their ability to proliferate and differentiate into effector progeny. Thus, identifying T cells with enhanced stemness and understanding their developmental requirements are of broad clinical and therapeutic interest. Here, we demonstrate that during acute infection, the transcriptional regulator inhibitor of DNA binding 3 (ID3) identifies stem-like T cells that are uniquely adapted to generate precursors of exhausted T (Tpex) cells in response to chronic infection or cancer. Expression of ID3 itself enables Tpex cells to sustain T cell responses in chronic infection or cancer, whereas loss of ID3 results in impaired maintenance of CD8 T cell immunity. Furthermore, we demonstrate that interleukin-1 (IL-1) family members, including IL-36β and IL-18, promote the generation of ID3+ T cells that mediate superior tumor control. Overall, we identify ID3 as a common denominator of stem-like T cells in both acute and chronic infections that is specifically required to sustain T cell responses to chronic stimulation.

Gene Expression Signatures of Porcine Bone Marrow-Derived Antigen-Presenting Cells Infected with Classical Swine Fever Virus

For a better understanding of classical swine fever (CSF) pathogenesis, a transcriptomic analysis was performed using porcine bone marrow (BM)-derived antigen-presenting cells (APCs) infected ex vivo with two different cDNA-derived classical swine fever virus (CSFV) strains, the low-virulence Pinar de Rio (vPdR-36U) or the lethal vPdR-H30K-5U. The transcriptomic profile of vPdR-36U- or vPdR-H30K-5U-infected versus noninfected cells revealed 946 and 2643 differentially expressed genes (DEGs), respectively. The upregulation of ISG15, CXCL-10, ADAM8, and CSF1 was found after infection with vPdR-36U, which could contribute to the generation of mild CSF forms. In contrast, cells infected with the lethal vPdR-H30K-5U overexpressed the immune checkpoint molecules PD-L1, CD276, and LAG3, which are involved in T-cell exhaustion and could be associated with adaptive immunity impairment. vPdR-H30K-5U also induced increased expression of PPBP, IL-8, IL-6, ECE1, and Rab27b, which are mediators of inflammatory responses that can be involved in cytokine storms. The TNF signaling pathway, which is related to the activation and proliferation of different subsets of immune cells, including CD4+ T cells, was notably upregulated in response to the low-pathogenicity virus. The Th17, Th1, and Th2 differentiation pathways were downregulated by the highly pathogenic virus only, supporting the role of T-cell-mediated immunity in protecting against CSFV.

Tomatidine relieves neuronal damage in spinal cord injury by inhibiting the inflammatory responses and apoptosis through blocking the NF-κB/CXCL10 pathway activation

Background

Spinal cord injury (SCI) is a neurological disease characterized by high disability and mortality rates. Tomatidine, a natural steroid alkaloid, has been evidenced to have neuroprotective properties. However, the underlying mechanisms of tomatidine in treating SCI remain ambiguous. This study aimed to illustrate the molecular mechanisms of tomatidine in modulating the inflammatory response and promoting functional rehabilitation after SCI.

Methods

Sprague-Dawley (SD) rats were used to construct an in vivo SCI model and were intraperitoneally injected with tomatidine (5, 10, or 20 mg/kg) for 7 days, followed by treatment with the nuclear factor-κB (NF-κB) pathway agonist (PMA). In addition, lipopolysaccharide (LPS)-induced PC-12 cells were used to establish an SCI cell model and were stimulated with tomatidine, PMA, or a CXCL10 inhibitor. The pathophysiological changes and neurological function were evaluated using blood-brain barrier (BBB) scoring, water content determination, hematoxylin and eosin (H&E) staining, and TUNEL assay. Levels of inflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, were measured. Cell proliferation, apoptosis, and the expression of C-X-C motif chemokine ligand 10 (CXCL10) were determined. Moreover, the expression of cleaved-caspase 3, caspase 3, CXCL10, p-p65, and p65 were analyzed.

Results

Our data revealed that tomatidine promoted neuronal damage recovery, reduced histopathological changes, elevated cell proliferation, and inhibited the apoptosis and inflammatory factor levels in spinal cord tissues and LPS-induced PC-12 cells. Moreover, tomatidine decreased the expression of CXCL10 in vitro and in vivo, which was accompanied by the regulation of the NF-κB pathway. However, the NF-κB pathway agonist PMA reversed the protective effect of tomatidine in vitro. PMA also enhanced the CXCL10 expression and stimulated the activation of the NF-κB pathway, as demonstrated by the upregulation of phosphorylated p65. The CXCL10 inhibitor had effects similar to tomatidine on cleaved-caspase 3 expression, CXCL10 expression, and the NF-κB pathway.

Conclusion

Tomatidine can alleviate neuronal damage in SCI by inhibiting apoptosis and inflammation through the NF-κB/CXCL10 pathway. Our findings provide a novel therapeutic target and candidate for the treatment of SCI.

Epigenetics behind CD8+ T cell activation and exhaustion

CD8+ T cells play a critical role in specific immunity. In recent years, cell therapy has been emerging rapidly. The specific cytotoxic capabilities of these cells enable them to precisely identify and kill cells presenting specific antigens. This has demonstrated promise in the treatment of autoimmune diseases and cancers, with wide-ranging applications and value. However, in some diseases, such as tumors and chronic infections, T cells may adopt an exhausted phenotype, resulting in a loss of cytotoxicity and limiting their further application. Epigenetics plays a significant role in the differentiation and regulation of gene expression in cells. There is extensive evidence indicating that epigenetic remodeling plays an important role in T cell exhaustion. Therefore, further understanding its role in CD8+ T cell function can provide insights into the programmatic regulation of CD8+ T cells from a genetic perspective and overcome these diseases. We attempted to describe the relationship between the activation, function, and exhaustion mechanisms of CD8+ T cells, as well as epigenetics. This understanding makes it possible for us to address the aforementioned issues.

Poly I:C vaccination drives transient CXCL9 expression near B cell follicles in the lymph node through type-I and type-II interferon signaling

Subunit vaccines drive immune cell-cell interactions in the lymph node (LN), yet it remains unclear how distinct adjuvants influence the chemokines responsible for this interaction in the tissue. Here, we tested the hypothesis that classic Th1-polarizing vaccines elicit a unique chemokine signature in the LN compared to other adjuvants. Polyinosinic:polycytidylic acid (Poly I:C) vaccination resulted in dynamic upregulation of CXCL9 that was localized in the interfollicular region, a response not observed after vaccination with alum or a combination of alum and poly I:C. Experiments using in vivo mouse models and live ex vivo LN slices revealed that poly I:C vaccination resulted in a type-I IFN response in the LN that led to the secretion of IFNγ, and type-I IFN and IFNγ were required for CXCL9 expression in this context. CXCL9 expression in the LN was correlated with an IgG2c antibody polarization after vaccination; however, genetic depletion of the receptor for CXCL9 did not prevent the development of this polarization. Additionally, we measured secretion of CXCL9 from ex vivo LN slices after stimulation with a variety of adjuvants and confirmed that adjuvants that induced IFNγ responses also promoted CXCL9 expression. Taken together, these results identify a CXCL9 signature in a suite of Th1-polarizing adjuvants and determined the pathway involved in driving CXCL9 in the LN, opening avenues to target this chemokine pathway in future vaccines.

Open-Source Throttling of CD8+ T Cells in Brain with Low-Intensity Focused Ultrasound-Guided Sequential Delivery of CXCL10, IL-2, and aPD-L1 for Glioblastoma Immunotherapy

Improving clinical immunotherapy for glioblastoma (GBM) relies on addressing the immunosuppressive tumor microenvironment (TME). Enhancing CD8+ T cell infiltration and preventing its exhaustion holds promise for effective GBM immunotherapy. Here, a low-intensity focused ultrasound (LIFU)-guided sequential delivery strategy is developed to enhance CD8+ T cells infiltration and activity in the GBM region. The sequential delivery of CXC chemokine ligand 10 (CXCL10) to recruit CD8+ T cells and interleukin-2 (IL-2) to reduce their exhaustion is termed an "open-source throttling" strategy. Consequently, up to 3.39-fold of CD8+ T cells are observed with LIFU-guided sequential delivery of CXCL10, IL-2, and anti-programmed cell death 1 ligand 1 (aPD-L1), compared to the free aPD-L1 group. The immune checkpoint inhibitors (ICIs) therapeutic efficacy is substantially enhanced by the reversed immunosuppressive TME due to the expansion of CD8+ T cells, resulting in the elimination of tumor, prolonged survival time, and long-term immune memory establishment in orthotopic GBM mice. Overall, LIFU-guided sequential cytokine and ICIs delivery offers an "open-source throttling" strategy of CD8+ T cells, which may present a promising strategy for brain-tumor immunotherapy.

Oral administration of garlic-derived nanoparticles improves cancer immunotherapy by inducing intestinal IFNγ-producing γδ T cells

Gamma-delta (γδ) T cell-based cancer immunotherapies represent a promising avenue for cancer treatment. However, their development is challenged by the limited expansion and differentiation of the cells ex vivo. Here we induced the endogenous expansion and activation of γδ T cells through oral administration of garlic-derived nanoparticles (GNPs). We found that GNPs could significantly promote the proliferation and activation of endogenous γδ T cells in the intestine, leading to generation of large amount of interferon-γ (IFNγ). Moreover GNP-treated mice showed increased levels of chemokine CXCR3 in intestinal γδ T cells, which can drive their migration from the gut to the tumour environment. The translocation of γδ T cells and IFNγ from the intestine to extraintestinal subcutaneous tumours remodels the tumour immune microenvironment and synergizes with anti-PD-L1, inducing robust antitumour immunity. Our study delineates mechanistic insight into the complex gut-tumour interactome and provides an alternative approach for γδ T cell-based immunotherapy.

Identification of the Hub Genes Linked to Lead (IV)-Induced Spleen Toxicity Using the Rat Model

Exposure to lead (Pb) has harmful effects on the organs of both humans and animals, particularly the spleen. However, the precise mechanisms through which Pb (IV) exposure leads to spleen toxicity remain unclear. Hence, this study aimed to identify the key genes and signaling pathways involved in spleen toxicity caused by Pb (IV) incubation. We obtained the dataset GSE59925 from the Gene Expression Omnibus, which included spleen samples treated with lead tetraacetate (PbAc4) as well as control samples on the 1st and 5th day. Through differential expression analysis, we identified 607 and 704 differentially expressed genes (DEGs) in the spleens on the 1st and 5th day following PbAc4 treatment, respectively, with 245 overlapping DEGs between the two time points. Gene ontology analysis revealed that the commonly shared DEGs were primarily involved in signal transduction, drug response, cell proliferation, adhesion, and migration. Pathway analysis indicated that the common DEGs were primarily associated with MAPK, TNF, cAMP, Hippo, and TGF-β signaling pathways. Furthermore, we identified the hub genes such as CXCL10, PARP1, APOE, and VDR contributing to PbAc4-induced spleen toxicity. This study enhances our understanding of the molecular mechanisms underlying Pb (IV) toxicity in the spleen.

Palmatine ameliorates N-methyl-N'-nitrosoguanidine-induced chronic atrophic gastritis through the STAT1/CXCL10 axis

Chronic atrophic gastritis (CAG) is a prevalent preneoplastic condition of the stomach. Palmatine (PAL), an isoquinoline alkaloid isolated from Rhizoma Coptidis (RC), has significant anti-inflammatory properties and is often used to treat gastrointestinal disorders. However, the mechanism of PAL on CAG remains unclear. In this study, N-methyl-N'-nitrosoguanidine (MNNG) was used to induce CAG inflammatory disease models in vivo and in vitro. The efficacy of five alkaloids in RC and the dose-dependent effects of the most effective PAL in CAG mice were evaluated in two animal experiments. RNA-seq and western blot revealed that PAL significantly improved IL-17, TNF, and NF-kappa B inflammation-related signaling pathways. Further hub gene prediction and experimental validation revealed that PAL modulated the STAT1/CXCL10 axis, thereby exerting attenuation of CAG through the regulation of IL-17, TNF-α, and p-p65 expression. In conclusion, PAL was proposed to mitigate MNNG-induced CAG, potentially through the inhibition of oxidative stress and inflammatory responses via the STAT1/CXCL10 axis. This approach is an effective complement to the use of PAL in the treatment of CAG.

Hepatocyte-specific Smad4 deficiency inhibits hepatocarcinogenesis by promoting CXCL10/CXCR3-dependent CD8+- T cell-mediated anti-tumor immunity

Rationale: Sma mothers against decapentaplegic homologue 4 (Smad4) is a key mediator of the transforming growth factor β (TGF-β) pathway and plays complex and contradictory roles in hepatocellular carcinoma (HCC). However, the specific role of Smad4 in hepatocytes in regulating hepatocarcinogenesis remains poorly elucidated. Methods: A diethylnitrosamine/carbon tetrachloride-induced HCC model was established in mice with hepatocyte-specific Smad4 deletion (AlbSmad4-/-) and liver tumorigenesis was monitored. Immune cell infiltration was examined by immunofluorescence and fluorescence activated cell sorting (FACS). Cytokine secretion, glycolysis, signal pathway, and single-cell RNA sequencing were analysed for mechanism. Results: AlbSmad4-/- mice exhibited significantly fewer and smaller liver tumor nodules, less fibrosis, reduced myeloid-derived suppressor cell infiltration and increased CD8+ T cell infiltration. Smad4 deletion in hepatocytes enhanced C-X-C motif ligand 10 (CXCL10) secretion, promoting tumor necrosis factor-α (TNF-α) production in CD8+ T cells. The loss of Smad4 activated the CXCL10/mammalian target of rapamycin (mTOR)/lactate dehydrogenase A (LDHA) pathway, which increased glycolytic activity in CD8+ T cells. HCC patients with high Smad4 expression exhibited decreased CD8+ T cell infiltration and altered glycolysis. Conclusion: Our results demonstrate that Smad4 in hepatocytes promotes hepatocarcinogenesis and is a potential and candidate target for the prevention and therapy of HCC.

Defining the niche for stem-like CD8+ T cell formation and function

TCF-1+ CD8+ T cell populations have emerged as critical determinants for long-lived immunological memory. This cell population has stem-like properties and is implicated in improved disease outcomes by driving sustained killing of infected cells and maintaining the immune-cancer equilibrium. During an immune response, several factors, including antigen deposition and affinity, the inflammatory milieu, and T cell priming dynamics, aggregate to skew CD8+ T cell differentiation. Although these mechanisms are altered between acute and chronic disease settings, phenotypically similar stem-like TCF-1+ CD8+ T cell states are formed in each of these settings. Here, we characterize the specialized microenvironments within lymph nodes and the tumor microenvironment, which foster the generation or re-activation of stem-like TCF-1+ CD8+ T cell populations. We highlight the potential for targeting the stem-like CD8+ T cell niche to enhance vaccination and cancer immunotherapy and to track the trajectory of stem-like CD8+ T cells as biomarkers of therapeutic efficacy.

Chemokine receptor PET imaging: Bridging molecular insights with clinical applications

Chemokine receptors are important components of cellular signaling and play a critical role in directing leukocytes during inflammatory reactions. Their importance extends to numerous pathological processes, including tumor differentiation, angiogenesis, metastasis, and associations with multiple inflammatory disorders. The necessity to monitor the in vivo interactions of cellular chemokine receptors has been driven the recent development of novel positron emission tomography (PET) imaging agents. This imaging modality provides non-invasive localization and quantitation of these receptors that cannot be provided through blood or tissue-based assays. Herein, we provide a review of PET imaging of the chemokine receptors that have been imaged to date, namely CXCR3, CXCR4, CCR2, CCR5, and CMKLR1. The quantification of these receptors can aid in understanding various diseases, including cancer, atherosclerosis, idiopathic pulmonary fibrosis, and acute respiratory distress syndrome. The development of specific radiotracers targeting these receptors will be discussed, including promising results for disease diagnosis and management. However, challenges persist in fully translating these imaging advancements into practical therapeutic applications. Given the success of CXCR4 PET imaging to date, future research should focus on clinical translation of these approaches to understand their role in the management of a wide variety of diseases.

Transient inhibition of type I interferon enhances CD8 + T cell stemness and vaccine protection

Developing vaccines that promote CD8 + T cell memory is a challenge for infectious disease and cancer immunotherapy. TCF-1 + stem cell-like memory T (T SCM ) cells are important determinants of long-lived memory. Yet, the developmental requirements for T SCM formation are unclear. Here, we identify the temporal window for type I interferon (IFN-I) receptor (IFNAR) blockade to drive T SCM cell generation. T SCM cells were transcriptionally distinct and emerged from a transitional precursor of exhausted (T PEX ) cellular state concomitant with viral clearance. T SCM differentiation correlated with T cell retention within the lymph node paracortex, due to increased CXCR3 chemokine abundance which disrupted gradient formation. These affects were due a counterintuitive increase in IFNψ, which controlled cell location. Combining IFNAR inhibition with mRNA-LNP vaccination promoted specific T SCM differentiation and enhanced protection against chronic infection. These finding propose a new approach to vaccine design whereby modulation of inflammation promotes memory formation and function.

HIGHLIGHTS

Early, transient inhibition of the type I interferon (IFN) receptor (IFNAR) during acute viral infection promotes stem cell-like memory T (T SCM ) cell differentiation without establishing chronic infection. T SCM and precursor of exhausted (T PEX ) cellular states are distinguished transcriptionally and by cell surface markers. Developmentally, T SCM cell differentiation occurs via a transition from a T PEX state coinciding with viral clearance. Transient IFNAR blockade increases IFNψ production to modulate the ligands of CXCR3 and couple T SCM differentiation to cell retention within the T cell paracortex of the lymph node. Specific promotion of T SCM cell differentiation with nucleoside-modified mRNA-LNP vaccination elicits enhanced protection against chronic viral challenge.

Discovery of a Novel CSF-1R Inhibitor with Highly Improved Pharmacokinetic Profiles and Superior Efficacy in Colorectal Cancer Immunotherapy

Blocking CSF-1/CSF-1R pathway has emerged as a promising strategy to remodel tumor immune microenvironment (TME) by reprogramming tumor-associated macrophages (TAMs). In this work, a novel CSF-1R inhibitor C19 with a highly improved pharmacokinetic profile and in vivo anticolorectal cancer (CRC) efficiency was successfully discovered. C19 could effectively reprogram M2-like TAMs to M1 phenotype and reshape the TME by inducing the recruitment of CD8+ T cells into tumors and reducing the infiltration of immunosuppressive Tregs/MDSCs. Deeper mechanistic studies revealed that C19 facilitated the infiltration of CD8+ T cells by enhancing the secretion of chemokine CXCL9, thus significantly potentiating the anti-CRC efficiency of PD-1 blockade. More importantly, C19 combined with PD-1 mAb could induce durable antitumor immune memory, effectively overcoming the recurrence of CRC. Taken together, our findings suggest that C19 is a promising therapeutic option for sensitizing CRC to anti-PD-1 therapy.

CXCL family-related classification predicts prognosis and response to immunotherapy in patients with head and neck squamous cell carcinoma based on TCGA and GEO databases

Background

Head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent malignant cancer worldwide. The cysteine X cysteine (CXC) chemokine family contains 17 members, which are reportedly crucial for the growth, invasion, metastasis, and microenvironment of tumor cells. Although the precise functions of CXC ligands (CXCLs) in HNSCC are unclear, these proteins may play important roles in controlling tumor growth and forming the tumor immune environment.

Methods

We downloaded the RNA sequencing and matched clinicopathological data of 379 patients with HNSCC as the training set from The Cancer Genome Atlas and two datasets from the Gene Expression Omnibus for use as validation sets.

Results

Through consensus clustering, we identified two subtypes of HNSCC associated with the CXCL family, named cluster1 and cluster2. Patients with the cluster1 subtype showed favourable clinical outcomes, significant immune cell infiltration, and improved immune response signalling pathway modulation. We also developed a nomogram of CXCL family scores for therapeutic use and for predicting the overall survival (OS) of patients with HNSCC. Patients with lower scores showed longer OS and higher immune cell infiltration in their tissues.

Conclusions

We developed a new classification method for HNSCC using the CXCL gene family, which can be used clinically to evaluate the prognosis and response to immunotherapy in patients with HNSCC.

Eosinophils promote CD8+ T cell memory generation to potentiate anti-bacterial immunity

Memory CD8+ T cell generation is crucial for pathogen elimination and effective vaccination against infection. The cellular and molecular circuitry that underlies the generation of memory CD8+ T cells remains elusive. Eosinophils can modulate inflammatory allergic responses and interact with lymphocytes to regulate their functions in immune defense. Here we report that eosinophils are required for the generation of memory CD8+ T cells by inhibiting CD8+ T cell apoptosis. Eosinophil-deficient mice display significantly impaired memory CD8+ T cell response and weakened resistance against Listeria monocytogenes (L.m.) infection. Mechanistically, eosinophils secrete interleukin-4 (IL-4) to inhibit JNK/Caspase-3 dependent apoptosis of CD8+ T cells upon L.m. infection in vitro. Furthermore, active eosinophils are recruited into the spleen and secrete more IL-4 to suppress CD8+ T cell apoptosis during early stage of L.m. infection in vivo. Adoptive transfer of wild-type (WT) eosinophils but not IL-4-deficient eosinophils into eosinophil-deficient mice could rescue the impaired CD8+ T cell memory responses. Together, our findings suggest that eosinophil-derived IL-4 promotes the generation of CD8+ T cell memory and enhances immune defense against L.m. infection. Our study reveals a new adjuvant role of eosinophils in memory T cell generation and provides clues for enhancing the vaccine potency via targeting eosinophils and related cytokines.

Treatment of secondary CNS lymphoma using CD19-targeted chimeric antigen receptor (CAR) T cells

BACKGROUND

Aggressive B cell lymphoma with secondary central nervous system (CNS) involvement (SCNSL) carries a dismal prognosis. Chimeric antigen receptor (CAR) T cells (CAR-T) targeting CD19 have revolutionized the treatment for B cell lymphomas; however, only single cases with CNS manifestations successfully treated with CD19 CAR-T have been reported.

METHODS

We prospectively enrolled 4 patients with SCNSL into our study to assess clinical responses and monitor T cell immunity.

RESULTS

Two of four SNCSL patients responded to the CD19-targeted CAR-T. Only one patient showed a substantial expansion of peripheral (PB) CAR-T cells with an almost 100-fold increase within the first week after CAR-T. The same patient also showed marked neurotoxicity and progression of the SNCSL despite continuous surface expression of CD19 on the lymphoma cells and an accumulation of CD4+ central memory-type CAR-T cells in the CNS. Our studies indicate that the local production of chemokine IP-10, possibly through its receptor CXCR3 expressed on our patient's CAR-T, could potentially have mediated the local accumulation of functionally suboptimal anti-tumor T cells.

CONCLUSIONS

Our results demonstrate expansion and homing of CAR-T cells into the CNS in SNCSL patients. Local production of chemokines such as IP-10 may support CNS infiltration by CAR-T cells but also carry the potential of amplifying local toxicity. Future studies investigating numbers, phenotype, and function of CAR-T in the different body compartments of SNSCL patients receiving CAR-T will help to improve local delivery of "fit" and highly tumor-reactive CAR-T with low off-target reactivity into the CNS.

NFAT signaling is indispensable for persistent memory responses of MCMV-specific CD8+ T cells

Cytomegalovirus (CMV) induces a unique T cell response, where antigen-specific populations do not contract, but rather inflate during viral latency. It has been proposed that subclinical episodes of virus reactivation feed the inflation of CMV-specific memory cells by intermittently engaging T cell receptors (TCRs), but evidence of TCR engagement has remained lacking. Nuclear factor of activated T cells (NFAT) is a family of transcription factors, where NFATc1 and NFATc2 signal downstream of TCR in mature T lymphocytes. We show selective impacts of NFATc1 and/or NFATc2 genetic ablations on the long-term inflation of MCMV-specific CD8+ T cell responses despite largely maintained responses to acute infection. NFATc1 ablation elicited robust phenotypes in isolation, but the strongest effects were observed when both NFAT genes were missing. CMV control was impaired only when both NFATs were deleted in CD8+ T cells used in adoptive immunotherapy of immunodeficient mice. Transcriptome analyses revealed that T cell intrinsic NFAT is not necessary for CD8+ T cell priming, but rather for their maturation towards effector-memory and in particular the effector cells, which dominate the pool of inflationary cells.

CircMAPK1 promoted CD8 + T cell infiltration in LUAD by improving the IGF2BP1 dependent CCL5 upregulation

Lung adenocarcinoma (LUAD) is the most common pathological subtype of lung cancer and has a poor prognosis. Immune Checkpoint Blockage (ICB) have been shown to improve the survival of LUAD in the last decade. CD8 + T cell infiltration is significantly related to LUAD prognosis and plays a critical role in ICB response efficiency. Chemokines expressed and secreted by tumor and microenvironment cells regulate the recruitment of CD8 + T cells. A cytoplasm-dominant circRNA, termed circMAPK1, was found to be down-regulated in LUAD and dramatically suppressed the growth of LUAD upon circMAPK1 overexpression in immunocompetent mice. Meanwhile, it was found that circMAPK1 significantly promoted the CD8 + T cell intratumoral infiltration in vitro and in vivo. CircMAPK1 was identified as binding IGF2BP1 in the cytoplasm and inducing IGF2BP1 to occupy the 3'UTR of CCL5 mRNA, resulting in retained stability of CCL5 mRNA. In general, circMAPK1 is a microenvironment-associated circRNA that recruits CD8 + T cells in LUAD. CircMAPK1 is an effective microenvironment regulator and a potential nucleic acid drug that can be combined with ICB to improve immunotherapy response efficiency.

Immune Cells in the Spleen of Mice Mediate the Inflammatory Response Induced by Mannheimia haemolytica A2 Serotype

(1) Background: Mannheimia haemolytica (M. haemolytica) is an opportunistic pathogen and is mainly associated with respiratory diseases in cattle, sheep, and goats. (2) Methods: In this study, a mouse infection model was established using a M. haemolytica strain isolated from goats. Histopathological observations were conducted on various organs of the mice, and bacterial load determination and RNA-seq analysis were specifically performed on the spleens of the mice. (3) Results: The findings of this study suggest that chemokines, potentially present in the spleen of mice following a M. haemolytica challenge, may induce the migration of leukocytes to the spleen and suppress the release of pro-inflammatory factors through a negative feedback regulation mechanism. Additionally, an interesting observation was made regarding the potential of hematopoietic stem/progenitor cells congregating in the spleen to differentiate into immune cells, which could potentially collaborate with leukocytes in their efforts to counteract M. haemolytica invasion. (4) Conclusions: This study revealed the immune regulation mechanism induced by M. haemolytica in the mouse spleen, providing valuable insights into host-pathogen interactions and offering a theoretical basis for the prevention, control, and treatment of mannheimiosis.

Obesity-related Plasma CXCL10 Drives CX3CR1-dependent Monocytic Secretion of Macrophage Migration Inhibitory Factor

Obesity is characterized by excessive body fat accumulation and comorbidities such as diabetes mellitus, cardiovascular disease, and obstructive sleep apnea syndrome (OSAS). Both obesity and OSAS are associated with immune disturbance, alterations of systemic inflammatory mediators, and immune cell recruitment to metabolic tissues. Chemokine CXCL10 is an important regulator of proinflammatory immune responses and is significantly increased in patients with severe obesity. This research project aims to investigate the impact of CXCL10 on human monocytes in patients with obesity. We studied the distribution of the CD14/CD16 monocyte subsets as well as their CX3CR1 expression patterns in whole-blood measurements from 92 patients with obesity and/or OSAS with regard to plasma CXCL10 values and individual clinical parameters. Furthermore, cytokine secretion by THP-1 monocytes in response to CXCL10 was analyzed. Data revealed significantly elevated plasma CXCL10 in patients with obesity with an additive effect of OSAS. CXCL10 was found to drive monocytic secretion of macrophage migration inhibitory factor via receptor protein CX3CR1, which significantly correlated with the individual body mass index. Our data show, for the first time, to our knowledge, that CX3CR1 is involved in alternative CXCL10 signaling in human monocytes in obesity-related inflammation. Obesity is a multifactorial disease, and further investigations regarding the complex interplay between obesity-related inflammatory mediators and systemic immune balances will help to better understand and improve the individual situation of our patients.

Features of immune reactivity of the spleen and mechanisms of organ damage under the influence of animal venom toxins including scorpions (review)

OBJECTIVE

Aim: To establish features of immune reactivity of the spleen and mechanisms of organ damage under the influence of animal venom toxins including scorpions.

PATIENTS AND METHODS

Materials and Methods: A thorough literature analysis was conducted on the basis of PubMed, Google Scholar, Web of Science, and Scopus databases. When processing the search results, we chose the newest publications up to 5 years old or the most thorough publications that vividly described the essence of our topic.

CONCLUSION

Conclusions: Spleen plays a leading role in the implementation of the body's defense processes, the elimination of structural elements affected by toxins, and the restoration of immune homeostasis. Its participation in the formation of the immune response can be accompanied by qualitative and quantitative changes in histological organization. Morpho-functional changes in the spleen under the action of animal venom toxins currently require careful study, because from the information available in the literature today, it is not possible to clearly construct a complete picture of lesions of certain components of the organ at the microscopic or submicroscopic levels. Therefore, this direction of research in the medical field is currently relevant, taking into account the existence of a large number of poisonous animals, including scorpions.

How chemokines organize the tumour microenvironment

For our immune system to contain or eliminate malignant solid tumours, both myeloid and lymphoid haematopoietic cells must not only extravasate from the bloodstream into the tumour tissue but also further migrate to various specialized niches of the tumour microenvironment to functionally interact with each other, with non-haematopoietic stromal cells and, ultimately, with cancer cells. These interactions regulate local immune cell survival, proliferative expansion, differentiation and their execution of pro-tumour or antitumour effector functions, which collectively determine the outcome of spontaneous or therapeutically induced antitumour immune responses. None of these interactions occur randomly but are orchestrated and critically depend on migratory guidance cues provided by chemokines, a large family of chemotactic cytokines, and their receptors. Understanding the functional organization of the tumour immune microenvironment inevitably requires knowledge of the multifaceted roles of chemokines in the recruitment and positioning of its cellular constituents. Gaining such knowledge will not only generate new insights into the mechanisms underlying antitumour immunity or immune tolerance but also inform the development of biomarkers (or 'biopatterns') based on spatial tumour tissue analyses, as well as novel strategies to therapeutically engineer immune responses in patients with cancer. Here we will discuss recent observations on the role of chemokines in the tumour microenvironment in the context of our knowledge of their physiological functions in development, homeostasis and antimicrobial responses.

Prior viral infection primes cross-reactive CD8+ T cells that respond to mouse heart allografts

Introduction

Significant evidence suggests a connection between transplant rejection and the presence of high levels of pre-existing memory T cells. Viral infection can elicit viral-specific memory T cells that cross-react with allo-MHC capable of driving allograft rejection in mice. Despite these advances, and despite their critical role in transplant rejection, a systematic study of allo-reactive memory T cells, their specificities, and the role of cross-reactivity with viral antigens has not been performed.

Methods

Here, we established a model to identify, isolate, and characterize cross-reactive T cells using Nur77 reporter mice (C57BL/6 background), which transiently express GFP exclusively upon TCR engagement. We infected Nur77 mice with lymphocytic choriomeningitis virus (LCMV-Armstrong) to generate a robust memory compartment, where quiescent LCMV-specific memory CD8+ T cells could be readily tracked with MHC tetramer staining. Then, we transplanted LCMV immune mice with allogeneic hearts and monitored expression of GFP within MHC-tetramer defined viral-specific T cells as an indicator of their ability to cross-react with alloantigens.

Results

Strikingly, prior LCMV infection significantly increased the kinetics and magnitude of rejection as well as CD8+ T cell recruitment into allogeneic, but not syngeneic, transplanted hearts, relative to non-infected controls. Interestingly, as early as day 1 after allogeneic heart transplant an average of ~8% of MHC-tetramer+ CD8+ T cells expressed GFP, in contrast to syngeneic heart transplants, where the frequency of viral-specific CD8+ T cells that were GFP+ was <1%. These data show that a significant percentage of viral-specific memory CD8+ T cells expressed T cell receptors that also recognized alloantigens in vivo. Notably, the frequency of cross-reactive CD8+ T cells differed depending upon the viral epitope. Further, TCR sequences derived from cross-reactive T cells harbored distinctive motifs that may provide insight into cross-reactivity and allo-specificity.

Discussion

In sum, we have established a mouse model to track viral-specific, allo-specific, and cross-reactive T cells; revealing that prior infection elicits substantial numbers of viral-specific T cells that cross-react to alloantigen, respond very early after transplant, and may promote rapid rejection.

FEN1 inhibitor SC13 promotes CAR-T cells infiltration into solid tumours through cGAS-STING signalling pathway

It is well known that chimeric antigen receptor T-cell immunotherapy (CAR-T-cell immunotherapy) has excellent therapeutic effect in haematological tumours, but it still faces great challenges in solid tumours, including inefficient T-cell tumour infiltration and poor functional persistence. Flap structure-specific endonuclease 1 (FEN1), highly expressed in a variety of cancer cells, plays an important role in both DNA replication and repair. Previous studies have reported that FEN1 inhibition is an effective strategy for cancer treatment. Therefore, we hypothesized whether FEN1 inhibitors combined with CAR-T-cell immunotherapy would have a stronger killing effect on solid tumours. The results showed that low dose of FEN1 inhibitors SC13 could induce an increase of double-stranded broken DNA (dsDNA) in the cytoplasm. Cytosolic dsDNA can activate the cyclic GMP-AMP synthase-stimulator of interferon gene signalling pathway and increase the secretion of chemokines. In vivo, under the action of FEN1 inhibitor SC13, more chemokines were produced at solid tumour sites, which promoted the infiltration of CAR-T cells and improved anti-tumour immunity. These findings suggest that FEN1 inhibitors could enable CAR-T cells to overcome poor T-cell infiltration and improve the treatment of solid tumours.

Splenic stromal niches in homeostasis and immunity

The spleen is a gatekeeper of systemic immunity where immune responses against blood-borne pathogens are initiated and sustained. Non-haematopoietic stromal cells construct microanatomical niches in the spleen that make diverse contributions to physiological spleen functions and regulate the homeostasis of immune cells. Additional signals from spleen autonomic nerves also modify immune responses. Recent insight into the diversity of the splenic fibroblastic stromal cells has revised our understanding of how these cells help to orchestrate splenic responses to infection and contribute to immune responses. In this Review, we examine our current understanding of how stromal niches and neuroimmune circuits direct the immunological functions of the spleen, with a focus on T cell immunity.

Profile and clinical significance of interferon gamma-inducible protein-10 (IP-10) and its receptor in patients with hepatocellular carcinoma

BACKGROUND

Chemokines play a vital role in tumor progression, metastasis and prognosis; however, the profile and clinical significance of gamma interferon-inducible protein-10 (IP-10) and its receptor (CXCR3) in patients with hepatocellular carcinoma (HCC) have not been well evaluated.

METHODS

Liquid-phase chip technology was used to detect the serum IP-10 in 85 patients with HBV-related HCC, 50 patients with chronic hepatitis B (CHB) and 50 liver cirrhosis subjects (CS); simultaneously, the CXCR3 and Alpha fetoprotein (AFP) were determined. Additionally, their mRNA or protein expression levels in peripheral blood mononuclear cells (PBMC), liver tumor and paracancerous tissues were quantified using qRT-PCR or ELISA. Moreover, the IP-10 and CXCR3 expression was verified by the online data from Gene Expression Omnibus. Furthermore, the relationships of serum IP-10, CXCR3 and AFP levels with their overall survival rate were also analyzed.

RESULTS

The levels of IP-10 and CXCR3 in HCC group were significantly higher than those in CHB and CS groups, and their mRNA of PBMC is significantly positive correlation with those in their liver tissues or HBV DNA load (P < 0.0001), respectively. The serum IP-10 and CXCR3 in HCC were significantly correlated with tumor differentiation, metastases staging and distant metastasis (P < 0.05), but not related to gender, age and tumor size (P > 0.05, except IP-10 based on age).

CONCLUSIONS

The serum IP-10 (142.6 pg/mL) and CXCR3 (241.2 pg/mL) could be differential diagnostic surrogates that distinguish HCC from CS, and the lower IP-10 level may be conducive to the postoperative survival of HCC patients. Moreover, the IP-10 and CXCR3 would be related to anti-tumor immunity in HCC patients and be a potential target for treatment of HCC.

Quantitative analyses of T cell motion in tissue reveals factors driving T cell search in tissues

T cells are required to clear infection, and T cell motion plays a role in how quickly a T cell finds its target, from initial naive T cell activation by a dendritic cell to interaction with target cells in infected tissue. To better understand how different tissue environments affect T cell motility, we compared multiple features of T cell motion including speed, persistence, turning angle, directionality, and confinement of T cells moving in multiple murine tissues using microscopy. We quantitatively analyzed naive T cell motility within the lymph node and compared motility parameters with activated CD8 T cells moving within the villi of small intestine and lung under different activation conditions. Our motility analysis found that while the speeds and the overall displacement of T cells vary within all tissues analyzed, T cells in all tissues tended to persist at the same speed. Interestingly, we found that T cells in the lung show a marked population of T cells turning at close to 180o, while T cells in lymph nodes and villi do not exhibit this "reversing" movement. T cells in the lung also showed significantly decreased meandering ratios and increased confinement compared to T cells in lymph nodes and villi. These differences in motility patterns led to a decrease in the total volume scanned by T cells in lung compared to T cells in lymph node and villi. These results suggest that the tissue environment in which T cells move can impact the type of motility and ultimately, the efficiency of T cell search for target cells within specialized tissues such as the lung.

BRAF D594A mutation defines a unique biological and immuno-modulatory subgroup associated with functional CD8+ T cell infiltration in colorectal cancer

BACKGROUND

BRAF non-V600 mutation occupies a relatively small but critical subset in colorectal cancer (CRC). However, little is known about the biological functions and impacts of BRAF class III mutation in CRC. Here, we aim to explore how D594A mutation impacts on biological behaviors and immune related signatures in murine CRC cells.

METHODS

BRAF V600E (class I), G469V (class II) and D594A (class III) mutant cell lines were established based on MC38 cells. The biological behaviors of cells were evaluated in respect of cell growth, cell proliferation, cell apoptosis, cell migration and invasion by the methods of colony-forming assay, CCK-8 assay, Annexin V/PI staining and transwell assay. The concentrations of soluble cytokines were detected by ELISA. The membrane expression of immuno-modulatory molecules and the pattern of tumor infiltrating lymphocyte were evaluated by flow cytometry. The molecular mechanism was explored by RNA sequencing. Immunohistochemistry (IHC) staining was used for the detection of CD8α in tumor tissues. qRT-PCR and western blot were performed to assess the mRNA and protein expression. Anti-PD-L1 treatment and cytokines neutralization experiments were conducted in in vivo models.

RESULTS

D594A mutant cells displayed lower grade malignancy characteristics than V600E (class I) and G469V (class II) mutant cells. Meanwhile, D594A mutation led to evident immuno-modulatory features including upregulation of MHC Class I and PD-L1. In vivo experiments displayed that the frequency of infiltrated CD8+ T cells was significantly high within D594A mutant tumors, which may provide potential response to anti-PD-L1 therapy. RNA sequencing analysis showed that D594A mutation led to enhanced expression of ATF3 and THBS1, which thus facilitated CXCL9 and CXCL10 production upon IFN-γ treatment. In addition, CXCL9 or CXCL10 neutralization reduced the infiltration of CD8+ T cells into THBS1-overexpressing tumors.

CONCLUSIONS

D594A mutant CRC exhibited lower aggressiveness and immune-activated phenotype. ATF3-THBS1-CXCL9/CXCL10 axis mediated functional CD8+ T cells infiltration into the microenvironment of D594A mutant CRC. Our present study is helpful to define this mutation in CRC and provide important insights in designing effective immunotherapeutic strategies in clinic.

Infiltrating CD8+ T cells exacerbate Alzheimer's disease pathology in a 3D human neuroimmune axis model

Brain infiltration of peripheral immune cells and their interactions with brain-resident cells may contribute to Alzheimer's disease (AD) pathology. To examine these interactions, in the present study we developed a three-dimensional human neuroimmune axis model comprising stem cell-derived neurons, astrocytes and microglia, together with peripheral immune cells. We observed an increase in the number of T cells (but not B cells) and monocytes selectively infiltrating into AD relative to control cultures. Infiltration of CD8+ T cells into AD cultures led to increased microglial activation, neuroinflammation and neurodegeneration. Using single-cell RNA-sequencing, we identified that infiltration of T cells into AD cultures led to induction of interferon-γ and neuroinflammatory pathways in glial cells. We found key roles for the C-X-C motif chemokine ligand 10 (CXCL10) and its receptor, CXCR3, in regulating T cell infiltration and neuronal damage in AD cultures. This human neuroimmune axis model is a useful tool to study the effects of peripheral immune cells in brain disease.

Cellular and molecular waypoints along the path of T cell exhaustion

Thirty years of foundational research investigating molecular and cellular mechanisms promoting T cell exhaustion are now enabling rational design of T cell-based therapies for the treatment of chronic infections and cancer. Once described as a static cell fate, it is now well appreciated that the developmental path toward exhaustion is composed of a heterogeneous pool of cells with varying degrees of effector potential that ultimately converge on a terminally differentiated state. Recent description of the developmental stages along the differentiation trajectory of T cell exhaustion has provided insight into past immunotherapeutic success and future opportunities. Here, we discuss the hallmarks of distinct developmental stages occurring along the path to T cell dysfunction and the impact of these discrete CD8+ T cell fates on cancer immunotherapy.

Aging modifies endometrial dendritic cell function and unconventional double negative T cells in the human genital mucosa

BACKGROUND

Immune function in the genital mucosa balances reproduction with protection against pathogens. As women age, genital infections, and gynecological cancer risk increase, however, the mechanisms that regulate cell-mediated immune protection in the female genital tract and how they change with aging remain poorly understood. Unconventional double negative (DN) T cells (TCRαβ + CD4-CD8-) are thought to play important roles in reproduction in mice but have yet to be characterized in the human female genital tract. Using genital tissues from women (27-77 years old), here we investigated the impact of aging on the induction, distribution, and function of DN T cells throughout the female genital tract.

RESULTS

We discovered a novel site-specific regulation of dendritic cells (DCs) and unconventional DN T cells in the genital tract that changes with age. Human genital DCs, particularly CD1a + DCs, induced proliferation of DN T cells in a TFGβ dependent manner. Importantly, induction of DN T cell proliferation, as well as specific changes in cytokine production, was enhanced in DCs from older women, indicating subset-specific regulation of DC function with increasing age. In human genital tissues, DN T cells represented a discrete T cell subset with distinct phenotypical and transcriptional profiles compared to CD4 + and CD8 + T cells. Single-cell RNA and oligo-tag antibody sequencing studies revealed that DN T cells represented a heterogeneous population with unique homeostatic, regulatory, cytotoxic, and antiviral functions. DN T cells showed relative to CD4 + and CD8 + T cells, enhanced expression of inhibitory checkpoint molecules and genes related to immune regulatory as well as innate-like anti-viral pathways. Flow cytometry analysis demonstrated that DN T cells express tissue residency markers and intracellular content of cytotoxic molecules. Interestingly, we demonstrate age-dependent and site-dependent redistribution and functional changes of genital DN T cells, with increased cytotoxic potential of endometrial DN T cells, but decreased cytotoxicity in the ectocervix as women age, with implications for reproductive failure and enhanced susceptibility to infections respectively.

CONCLUSIONS

Our deep characterization of DN T cell induction and function in the female genital tract provides novel mechanistic avenues to improve reproductive outcomes, protection against infections and gynecological cancers as women age.

Pellino Proteins in Viral Immunity and Pathogenesis

Pellino proteins are a family of evolutionarily conserved ubiquitin ligases involved in intracellular signaling in a wide range of cell types. They are essential for microbe detection and the initiation of innate and adaptive immune responses. Some viruses specifically target the Pellino proteins as part of their immune evasion strategies. Through studies of mouse models of viral infections in the central nervous system, heart, lungs, and skin, the Pellino proteins have been linked to both beneficial and detrimental immune responses. Only in recent years have some of the involved mechanisms been identified. The objective of this review is to highlight the many diverse aspects of viral immunity and pathogenesis that the Pellino proteins have been associated with, in order to promote further research into their functions. After a brief introduction to the cellular signaling mechanisms involving Pellino proteins, their physiological roles in the initiation of immune responses, pathogenesis through excess inflammation, immune regulation, and cell death are presented. Known viral immune evasion strategies are also described. Throughout, areas that require more in-depth investigation are identified. Future research into the functions of the Pellino protein family may reveal fundamental insights into how our immune system works. Such knowledge may be leveraged in the fight against viral infections and their sequala.

The First Transcriptomic Atlas of the Adult Lacrimal Gland Reveals Epithelial Complexity and Identifies Novel Progenitor Cells in Mice

The lacrimal gland (LG) secretes aqueous tears. Previous studies have provided insights into the cell lineage relationships during tissue morphogenesis. However, little is known about the cell types composing the adult LG and their progenitors. Using scRNAseq, we established the first comprehensive cell atlas of the adult mouse LG to investigate the cell hierarchy, its secretory repertoire, and the sex differences. Our analysis uncovered the complexity of the stromal landscape. Epithelium subclustering revealed myoepithelial cells, acinar subsets, and two novel acinar subpopulations: Tfrchi and Car6hi cells. The ductal compartment contained Wfdc2+ multilayered ducts and an Ltf+ cluster formed by luminal and intercalated duct cells. Kit+ progenitors were identified as: Krt14+ basal ductal cells, Aldh1a1+ cells of Ltf+ ducts, and Sox10+ cells of the Car6hi acinar and Ltf+ epithelial clusters. Lineage tracing experiments revealed that the Sox10+ adult populations contribute to the myoepithelial, acinar, and ductal lineages. Using scRNAseq data, we found that the postnatally developing LG epithelium harbored key features of putative adult progenitors. Finally, we showed that acinar cells produce most of the sex-biased lipocalins and secretoglobins detected in mouse tears. Our study provides a wealth of new data on LG maintenance and identifies the cellular origin of sex-biased tear components.

The development of CD8 T-cell exhaustion heterogeneity and the therapeutic potentials in cancer

CD8⁺ T cells are essential lymphocytes with cytotoxic properties for antitumor immunotherapy. However, during chronic infection or tumorigenesis, these cells often become dysfunctional with a gradually depleted ability to release cytokines and the exhibition of reduced cytotoxicity, the state referred to as "T-cell exhaustion" (Tex). This unique state was characterized by the increasing expression of inhibitory checkpoint receptors, and interventions targeting immune checkpoint blockades (ICBs) have been considered as a promising strategy to stimulate T-cell killing. Recent investigations have demonstrated that exhausted T cells not only display functional, metabolic, transcriptional, and epigenetic differences but also comprise a heterogeneous group of cells. In this review, we summarize the current findings on dynamic differentiation process during Tex heterogeneity development in cancer and chronic infection. We discuss how the responses to immunotherapy are determined by these distinct subsets and highlight prospective approaches for improving the efficacy of ICB therapy for cancer by leveraging the heterogeneity of T cells.

XCR1+ DCs are critical for T cell-mediated immunotherapy of chronic viral infections

The contribution of cross-presenting XCR1+ dendritic cells (DCs) and SIRPα+ DCs in maintaining T cell function during exhaustion and immunotherapeutic interventions of chronic infections remains poorly characterized. Using the mouse model of chronic LCMV infection, we found that XCR1+ DCs are more resistant to infection and highly activated compared with SIRPα+ DCs. Exploiting XCR1+ DCs via Flt3L-mediated expansion or XCR1-targeted vaccination notably reinvigorates CD8+ T cells and improves virus control. Upon PD-L1 blockade, XCR1+ DCs are not required for the proliferative burst of progenitor exhausted CD8+ T (TPEX) cells but are indispensable to sustain the functionality of exhausted CD8+ T (TEX) cells. Combining anti-PD-L1 therapy with increased frequency of XCR1+ DCs improves functionality of TPEX and TEX subsets, while increase of SIRPα+ DCs dampened their proliferation. Together, this demonstrates that XCR1+ DCs are crucial for the success of checkpoint inhibitor-based therapies through differential activation of exhausted CD8+ T cell subsets.

Hepatitis B and Hepatitis D Viruses: A Comprehensive Update with an Immunological Focus

Hepatitis B virus (HBV) and hepatitis delta virus (HDV) are highly prevalent viruses estimated to infect approximately 300 million people and 12-72 million people worldwide, respectively. HDV requires the HBV envelope to establish a successful infection. Concurrent infection with HBV and HDV can result in more severe disease outcomes than infection with HBV alone. These viruses can cause significant hepatic disease, including cirrhosis, fulminant hepatitis, and hepatocellular carcinoma, and represent a significant cause of global mortality. Therefore, a thorough understanding of these viruses and the immune response they generate is essential to enhance disease management. This review includes an overview of the HBV and HDV viruses, including life cycle, structure, natural course of infection, and histopathology. A discussion of the interplay between HDV RNA and HBV DNA during chronic infection is also included. It then discusses characteristics of the immune response with a focus on reactions to the antigenic hepatitis B surface antigen, including small, middle, and large surface antigens. This paper also reviews characteristics of the immune response to the hepatitis D antigen (including small and large antigens), the only protein expressed by hepatitis D. Lastly, we conclude with a discussion of recent therapeutic advances pertaining to these viruses.

Lymphoid tissue residency: A key to understand Tcf-1+PD-1+ T cells

During chronic antigen exposure, a subset of exhausted CD8+ T cells differentiate into stem cell-like or progenitor-like T cells expressing both transcription factor Tcf-1 (T cell factor-1) and co-inhibitory receptor PD-1. These Tcf-1+ stem-like or progenitor exhausted T cells represent the key target for immunotherapies. Deeper understanding of the biology of Tcf-1+PD-1+ CD8+ T cells will lead to rational design of future immunotherapies. Here, we summarize recent findings about the migratory and resident behavior of Tcf-1+ T cells. Specifically, we will focus on TGF-β-dependent lymphoid tissue residency program of Tcf-1+ T cells, which may represent a key to understanding the differentiation and maintenance of Tcf-1+ stem-like CD8+ T cells during persistent antigen stimulation.

CXCL10 Chemokine: A Critical Player in RNA and DNA Viral Infections

Chemokines constitute a group of small, secreted proteins that regulate leukocyte migration and contribute to their activation. Chemokines are crucial inflammatory mediators that play a key role in managing viral infections, during which the profile of chemokine expression helps shape the immune response and regulate viral clearance, improving clinical outcome. In particular, the chemokine ligand CXCL10 and its receptor CXCR3 were explored in a plethora of RNA and DNA viral infections. In this review, we highlight the expression profile and role of the CXCL10/CXCR3 axis in the host defense against a variety of RNA and DNA viral infections. We also discuss the interactions among viruses and host cells that trigger CXCL10 expression, as well as the signaling cascades induced in CXCR3 positive cells.

Type 1 conventional dendritic cells maintain and guide the differentiation of precursors of exhausted T cells in distinct cellular niches

Reinvigoration of exhausted CD8⁺ T (Tex) cells by checkpoint immunotherapy depends on the activation of precursors of exhausted T (Tpex) cells, but the local anatomical context of their maintenance, differentiation, and interplay with other cells is not well understood. Here, we identified transcriptionally distinct Tpex subpopulations, mapped their differentiation trajectories via transitory cellular states toward Tex cells, and localized these cell states to specific splenic niches. Conventional dendritic cells (cDCs) were critical for successful αPD-L1 therapy and were required to mediate viral control. cDC1s were dispensable for Tpex cell expansion but provided an essential niche to promote Tpex cell maintenance, preventing their overactivation and T-cell-mediated immunopathology. Mechanistically, cDC1s insulated Tpex cells via MHC-I-dependent interactions to prevent their activation within other inflammatory environments that further aggravated their exhaustion. Our findings reveal that cDC1s maintain and safeguard Tpex cells within distinct anatomical niches to balance viral control, exhaustion, and immunopathology.