HBx promotes glomerular podocyte-induced immune cell responses.

BACKGROUND: Podocytes, as intrinsic renal cells, can also express MHC-II and costimulatory molecules under inflammatory conditions, suggesting that they may act as antigen-presenting cells (APCs) to activate immune cell responses and then lead to immune-mediated renal injury. They are already recognized as main targets in the pathogenic mechanism of hepatitis B virus (HBV)-associated glomerulonephritis (HBV-GN). Previous studies also have indicated that inflammatory cells infiltration and immune-mediated tissue injury are evident in the kidney samples of patients with HBV-GN. However, the role of podocytes immune disorder in the pathogenic mechanism of HBV-GN remains unclear. METHODS: Renal function and inflammatory cells infiltration were measured in HBV transgenic (HBV-Tg) mice. In vitro, podocytes/CD4+ T cells or macrophages co-culture system was established. Then, the expression of HBx, CD4, and CD68 was determined by immunohistochemistry, while the expression of MHC-II, CD40, and CD40L was determined by immunofluorescence. Co-stimulatory molecules expression was examined by flow cytometry. The levels of inflammatory factors were detected by ELISA. RESULTS: In vivo, renal function was obviously impaired in HBV-Tg mice. HBx was significantly upregulated and immune cells infiltrated in the glomerulus of HBV-Tg mice. Expression of MHC-II and costimulatory molecule CD40 increased in the podocytes of HBV-Tg mice; CD4+ T cells exhibited increased CD40L expression in glomerulus. In vitro, CD40 expression was markedly elevated in HBx-podocytes. In co-culture systems, HBx-podocytes stimulated CD4+ T cells activation and caused the imbalance between IFN-γ and IL-4. HBx-podocytes also enhanced the adhesion ability of macrophages and induced the release of proinflammatory mediators. CONCLUSION: Taken together, these podocyte-related immune disorder may be involved in the pathogenic mechanism of HBV-GN.

Obesity influences T CD4 lymphocytes subsets profiles in children and adolescent's immune response.

PURPOSE: Evidence shows that CD4+ T cells are altered in obesity and play a significant role in the systemic inflammation occurring in adults with the disease. Since the profile of these cells is poorly understood in the pediatric population, the present study aims to investigate the profile of CD4+ T lymphocytes and the plasma levels of cytokines in this population. METHODS: Using flow cytometry, we compared the expression profile of lymphocyte markers, master transcription factors, cytokines and molecules involved in the regulation of the immune response in CD4+ T cells from children and adolescents with obesity (OB group, n=20) to those with eutrophy (EU group, n=16). Plasma levels of cytokines in both groups were determined by CBA. RESULTS: The OB group presents a lower frequency of CD3+ T cells, as well as a decreased frequency of CD4+ T cells expressing CD28, IL-4, and FOXP3, but an increased frequency of CD4+IL-17A+ cells compared to the EU group. The frequency of CD28 is increased in Th2 and Treg cells in the OB group, while CTLA-4 is decreased in all subpopulations compared to the EU group. Furthermore, Th2, Th17 and Treg profiles can differentiate the EU and OB groups. IL-10 plasma levels are reduced in the OB group and negatively correlated with adiposity and inflammatory parameters. CONCLUSION: CD4+ T cells have an altered pattern of expression in children and adolescents with obesity, contributing to the inflammatory state and clinical characteristics of these patients.

Single-Cell Analysis Identifies Distinct Populations of Cytotoxic CD4+ T Cells Linked to the Therapeutic Efficacy of Immune Checkpoint Inhibitors in Metastatic Renal Cell Carcinoma.

Background: The involvement of cytotoxic CD4+ T cells (CD4+ CTLs) and their potential role in dictating the response to immune checkpoint inhibitors (ICIs) in patients with metastatic renal cell carcinoma (mRCC) remains an unexplored area of research. Methods: Utilizing single-cell RNA sequencing, we analyzed the immunophenotype and expression patterns of CD4+ T lymphocyte subtypes in mRCC patients, followed by preliminary validation via multi-immunofluorescent staining. In addition, we obtained a comprehensive immunotherapy dataset encompassing single-cell RNA sequencing datasets and bulk RNA-seq cohorts from the European Genome-Phenome Archive and ArrayExpress database. Utilizing the CIBERSORTx deconvolution algorithms, we derived a signature score for CD4+ CTLs from the bulk-RNA-seq datasets of the CheckMate 009/025 clinical trials. Results: Single-cell analysis of CD4+ T lymphocytes in mRCC reveals several cancer-specific states, including diverse phenotypes of regulatory T cells. Remarkably, we observe that CD4+ CTLs cells constitute a substantial proportion of all CD4+ T lymphocyte sub-clusters in mRCC patients, highlighting their potential significance in the disease. Furthermore, within mRCC patients, we identify two distinct cytotoxic states of CD4+ T cells: CD4+GZMK+ T cells, which exhibit a weaker cytotoxic potential, and CD4+GZMB+ T cells, which demonstrate robust cytotoxic activity. Both regulatory T cells and CD4+ CTLs originate from proliferating CD4+ T cells within mRCC tissues. Intriguingly, our trajectory analysis indicates that the weakly cytotoxic CD4+GZMK+ T cells differentiate from their more cytotoxic CD4+GZMB+ counterparts. In comparing patients with lower CD4+ CTLs levels to those with higher CD4+ CTLs abundance in the CheckMate 009 and 25 immunotherapy cohorts, the latter group exhibited significantly improved OS and PFS probability. Conclusion: Our study underscores the pivotal role that intratumoral CD4+ CTLs may play in bolstering anti-tumor immunity, suggesting their potential as a promising biomarker for predicting response to ICIs in patients with mRCC.

Polygenic TB control and the sequence of innate/adaptive immune responses to infection: MHC-II alleles determine the size of the S100A8/9-producing neutrophil population.

Among several quantitative trait loci involved in tuberculosis (TB) control in mice, one was mapped within the chromosome 17 segment occupied by the H2 complex and another within the chromosome 3 segment comprising the S100A8/9 genes, which encode neutrophil inflammatory factor S100A8/9. Previously, we developed a panel of H2-congenic mouse strains differing by small segments of the major histocompatibility complex Class II (MHC-II) region from TB-susceptible H2j mice transferred onto the genetic background of the TB-resistant C57BL/6 (H2b) strain. Susceptible B6.I-9.3 mice differ from B6 progenitors by the alleles of their only classical MHC-II H2-Aß gene. The goals of the present study were to: (i) comprehensively characterise the differences in TB-related phenotypes between mice of the two strains and (ii) decipher interactions between the H2-Aß and S100A8/9 genes. Here, we describe the dynamics of TB-related phenotypes differentiating B6.I-9.3 and B6 mice (colony forming units counts, histopathology, lung immune cell infiltration and cytokine profiles). We show that disproportionally diminished CD4+ T-cell population, an enlarged S100A8/9-positive neutrophil population and higher S100A8/9 serum levels in B6.I-9.3 mice collectively form the 'susceptible' phenotype before infection. An increase in IL-17 and a decrease in intrferon-gamma production by CD4+ T-cells in these mice provide a mechanistic explanation of this phenotype. Using F2 segregation analysis, we show that the number of S100A8/9-producing neutrophils in lungs and spleens and the proportion of Th17 CD4+ T-cells in lungs are significantly lower in the presence of the MHC-II dominant 'resistant' b allele compared to the recessive 'susceptible' j/j genotype. This provides direct genetic evidence that MHC-II-regulated CD4+ T-cell landscapes determine neutrophil abundance before infection, an important pathogenic factor in TB immunity.

Theabrownin from Pu-erh Tea Improves DSS-Induced Colitis via Restoring Gut Homeostasis and Inhibiting TLR2&4 Signaling Pathway.

BACKGROUND: Theabrownin (TB) is a dark brown pigment from Pu-erh tea or other dark teas. It is formed by further oxidization of theaflavins and thearubigins, in combination with proteins, polysaccharides, and caffeine etc. TB is a characteristic ingredient and bioactive substance of Pu-erh tea. However, the effects of TB on ulcerative colitis (UC) remains unclear. PURPOSE: This study aims to elucidate the mechanism of TB on UC in terms of recovery of intestinal homeostasis and regulation of toll-like receptor (TLR) 2&4 signaling pathway. METHODS: The colitis models were established by administering 5% dextran sulfate sodium (DSS) to C57BL/6 mice for 5 days to evaluate the therapeutic and preventive effects of TB on UC. Mesalazine was used as a positive control. H&E staining, complete blood count, enzyme-linked immunosorbent assay, immunohistochemistry, flow cytometry, and 16S rRNA sequencing were employed to assess histological changes, blood cells analysis, content of cytokines, expression and distribution of mucin (MUC)2 and TLR2&4, differentiation of CD4+T cells in lamina propria, and changes in intestinal microbiota, respectively. Western blot was utilized to study the relative expression of tight junction proteins and the key proteins in TLR2&4-mediated MyD88-dependent MAPK, NF-κB, and AKT signaling pathways. RESULTS: TB outstanding alleviated colitis, inhibited the release of pro-inflammatory cytokines, reduced white blood cells while increasing red blood cells, hemoglobin, and platelets. TB increased the expression of occludin, claudin-1 and MUC2, effectively restored intestinal barrier function. TB also suppressed differentiation of Th1 and Th17 cells in the colon's lamina propria, increased the fraction of Treg cells, and promoted the balance of Treg/Th17 to tilt towards Tregs. Moreover, TB increased the Firmicutes to Bacteroides (F/B) ratio, as well as the abundance of Akkermansia, Muribaculaceae, and Eubacterium_coprostanoligenes_group at the genus level. In addition, TB inhibited the activation of TLR2&4-mediated MAPK, NF-κB, and AKT signaling pathways in intestinal epithelial cells of DSS-induced mice. CONCLUSION: TB acts in restoring intestinal homeostasis and anti-inflammatory in DSS-induced UC, and exhibiting a preventive effect after long-term use. In a word, TB is a promising beverage, health product and food additive for UC.

Immunometabolic alteration of CD4+ T cells in the pathogenesis of primary Sjögren's syndrome.

Primary Sjögren's syndrome (pSS) is a prevalent autoimmune disorder wherein CD4+ T cells play a pivotal role in its pathogenesis. However, the underlying mechanisms driving the hyperactivity of CD4+ T cells in pSS remain poorly understood. This study aimed to investigate the potential role of immunometabolic alterations in driving the hyperactivity of CD4+ T cells in pSS. We employed Seahorse XF assay to evaluate the metabolic phenotype of CD4+ T cells, conducted flow cytometry to assess the effector function and differentiation of CD4+ T cells and measured the level of intracellular reactive oxygen species (ROS). Additionally, transcriptome sequencing, PCR, and Western blotting were utilized to examine the expression of glycolytic genes. Our investigation revealed that activated CD4+ T cells from pSS patients exhibited elevated aerobic glycolysis, rather than oxidative phosphorylation, resulting in excessive production of IFN-γ and IL-17A. Inhibition of glycolysis by 2-Deoxy-D-glucose reduced the expression of IFN-γ and IL-17A in activated CD4+ T cells and mitigated the differentiation of Th1 and Th17 cells. Furthermore, the expression of glycolytic genes, including CD3E, CD28, PIK3CA, AKT1, mTOR, MYC, LDHA, PFKL, PFKFB3, and PFKFB4, was upregulated in activated CD4+ T cells from pSS patients. Specifically, the expression and activity of LDHA were enhanced, contributing to an increased level of intracellular ROS. Targeting LDHA with FX-11 or inhibiting ROS with N-acetyl-cysteine had a similar effect on reversing the dysfunction of activated CD4+ T cells from pSS patients. Our study unveils heightened aerobic glycolysis in activated CD4+ T cells from pSS patients, and inhibition of glycolysis or its metabolite normalizes the dysfunction of activated CD4+ T cells. These findings suggest that aerobic glycolysis may be a promising therapeutic target for the treatment of pSS.

Mitochondrial Transplantation Promotes Protective Effector and Memory CD4+ T Cell Response During Mycobacterium Tuberculosis Infection and Diminishes Exhaustion and Senescence in Elderly CD4+ T cells.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb), is a major global health concern, particularly affecting those with weakened immune systems, including the elderly. CD4+ T cell response is crucial for immunity against M.tb, but chronic infections and aging can lead to T cell exhaustion and senescence, worsening TB disease. Mitochondrial dysfunction, prevalent in aging and chronic diseases, disrupts cellular metabolism, increases oxidative stress, and impairs T-cell functions. This study investigates the effect of mitochondrial transplantation (mito-transfer) on CD4+ T cell differentiation and function in aged mouse models and human CD4+ T cells from elderly individuals. Mito-transfer in naïve CD4+ T cells is found to promote protective effector and memory T cell generation during M.tb infection in mice. Additionally, it improves elderly human T cell function by increasing mitochondrial mass and altering cytokine production, thereby reducing markers of exhaustion and senescence. These findings suggest mito-transfer as a novel approach to enhance aged CD4+ T cell functionality, potentially benefiting immune responses in the elderly and chronic TB patients. This has broader implications for diseases where mitochondrial dysfunction contributes to T-cell exhaustion and senescence.

Dietary pectin and inulin: a promising adjuvant supplement for collagen-induced arthritis through gut microbiome restoration and CD4+ T cell reconstitution.

Dietary strategies rich in fiber have been demonstrated to offer benefits to individuals afflicted with rheumatoid arthritis (RA). However, the specific mechanisms through which a high-fiber diet (HFD) mitigates RA's autoimmunity remain elusive. Herein, we investigate the influence of pectin- and inulin-rich HFD on collagen-induced arthritis (CIA). We establish that HFD significantly alleviates arthritis in CIA mice by regulating the Th17/Treg balance. The rectification of aberrant T cell differentiation by the HFD is linked to the modulation of gut microbiota, augmenting the abundance of butyrate in feces. Concurrently, adding butyrate to the drinking water mirrors the HFD's impact on ameliorating CIA, encompassing arthritis mitigation, regulating intestinal barrier integrity, and restoring the Th17/Treg equilibrium. Butyrate reshapes the metabolic profile of CD4+ T cells in an AMPK-dependent manner. Our research underscores the importance of dietary interventions in rectifying gut microbiota for RA management and offers an explanation of how diet-derived microbial metabolites influence RA's immune-inflammatory-reaction.

Tridecylcyclohexane in incomplete Freund's adjuvant is a critical component in inducing experimental autoimmune diseases.

Incomplete Freund's adjuvant (IFA) has been used for many years to induce autoimmune diseases in animal models, including experimental autoimmune encephalitis and collagen-induced arthritis. However, it remains unclear why it is necessary to emulsify autoantigen and heat-killed Mycobacterium tuberculosis (HKMtb) with IFA to induce experimental autoimmune diseases. Here, we found that immunization with self-antigen and HKMtb was insufficient to induce autoimmune diseases in mice. Furthermore, IFA or one of its components, mineral oil, but not mannide monooleate, was required for the development of experimental autoimmune disease. Immunization with autoantigen and HKMtb emulsified in mineral oil facilitated innate immune activation and promoted the differentiation of pathogenic CD4+ T cells, followed by their accumulation in neuronal tissues. Several water-soluble hydrocarbon compounds were identified in mineral oil. Of these, immunization with HKMtb and autoantigen emulsified with the same amount of hexadecane or tridecylcyclohexane as mineral oil induced the development of experimental autoimmune encephalitis. In contrast, immunization with HKMtb and autoantigen emulsified with tridecylcyclohexane, but not hexadecane, at doses equivalent to those found in mineral oil, resulted in neuronal dysfunction. These data indicate that tridecylcyclohexane in mineral oil is a critical component in the induction of experimental autoimmune disease.

Identification of the differentially expressed activated memory CD4+ T-cells-related genes and ceRNAs in oral lichen planus.

Background: Oral lichen planus (OLP) is a common chronic oral mucosal disease with 1.4 % malignant transformation rate, and its etiology especially immune pathogenesis remains unclear. This study was aimed at investigating the immune cells related molecular underlying the pathophysiology of OLP through bioinformatics analysis. Methods: The dataset GSE52130 obtained from the Gene Expression Omnibus (GEO) database was conducted a comprehensive analysis in this study. The CIBERSORTx was used for investigating immune cells infiltration. The gene set enrichment analysis (GSEA) and gene ontology (GO) enrichment were performed for exploring the biological functions and gene annotation. The protein-protein interactions (PPI) were constructed by STRING database and visualized by Cytoscape software. The cytohubba plugin was utilized for screening hub genes. The receiver operating characteristic (ROC) was performed for evaluating diagnostic value of hub genes. The miRNAs, lncRNAs and drugs were respectively predicted by NetworkAnalyst, miRTarbase, ENCORI, and DGIdb database. Results: This study identified 595 differentially expressed genes (DEGs). The GSEA indicated keratinization, innate immune system and biological oxidation were involved in OLP. GO analysis showed extracellular matrix and keratinocyte were mainly enriched. And we found the activated memory CD4+ T cells were lowly infiltrated in OLP. We identified 101 activated memory CD4+ T-cells-related DEGs. Three hub genes (APP, IL1B, TF) were selected. APP and IL1B were significantly up-regulated, whereas TF was down-regulated in OLP. The three hub genes show high diagnostic value in OLP. Additionally, they were involved in MAPK signal, NF-kappaB signal and iron metabolism in OLP. What's more, NEAT1/XIST - miR - 15a - 5p/miR - 155-5p - APP/IL1B signal axis was focused in competing endogenous RNA (ceRNA) network. In addition, 35 drugs were predicted for OLP. Conclusion: Three activated memory CD4+ T-cells-related DEGs were identified by integrative analysis. It may provide novel insight into the pathogenesis of OLP and suggest potential therapeutic targets for OLP.

Dihydroartemisinin ameliorates experimental autoimmune myasthenia gravis by regulating CD4+ T cells and modulating gut microbiota.

BACKGROUND: Dihydroartemisinin (DHA), a derivative and active metabolite of artemisinin, possesses various immunomodulatory properties. However, its role in myasthenia gravis (MG) has not been clearly explored. Here, we investigated the role of DHA in experimental autoimmune myasthenia gravis (EAMG) and its potential mechanisms. METHODS: The AChR97-116 peptide-induced EAMG model was established in Lewis rats and treated with DHA. Flow cytometry was used to assess the release of Th cell subsets and Treg cells, and 16S rRNA gene amplicon sequence analysis was applied to explore the relationship between the changes in the intestinal flora after DHA treatment. In addition, network pharmacology and molecular docking were utilized to explore the potential mechanism of DHA against EAMG, which was further validated in the rat model by immunohistochemical and RT-qPCR for further validation. RESULTS: In this study, we demonstrate that oral administration of DHA ameliorated clinical symptoms in rat models of EAMG, decreased the expression level of Th1 and Th17 cells, and increased the expression level of Treg cells. In addition, 16S rRNA gene amplicon sequence analysis showed that DHA restored gut microbiota dysbiosis in EAMG rats by decreasing Ruminococcus abundance and increasing the abundance of Clostridium, Bifidobacterium, and Allobaculum. Using network pharmacology, 103 potential targets of DHA related to MG were identified, and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that PI3K-AKT signaling pathway was related to the treatment of DHA on EAMG. Meanwhile, molecular docking verified that DHA has good binding affinity to AKT1, CASP3, EGFR, and IGF1. Immunohistochemical staining showed that DHA treatment significantly inhibited the phosphorylated expression of AKT and PI3K in the spleen tissues of EAMG rats. In EAMG rats, RT-qPCR results also showed that DHA reduced the mRNA expression levels of PI3K and AKT1. CONCLUSIONS: DHA ameliorated EAMG by inhibiting the PI3K-AKT signaling pathway, regulating CD4+ T cells and modulating gut microbiota, providing a novel therapeutic approach for the treatment of MG.

The role of regulatory T cells in vitiligo and therapeutic advances: a mini-review.

BACKGROUND: Regulatory T cells (Tregs) play vital roles in controlling immune reactions and maintaining immune tolerance in the body. The targeted destruction of epidermal melanocytes by activated CD8+T cells is a key event in the development of vitiligo. However, Tregs may exert immunosuppressive effects on CD8+T cells, which could be beneficial in treating vitiligo. METHODS: A comprehensive search of PubMed and Web of Science was conducted to gather information on Tregs and vitiligo. RESULTS: In vitiligo, there is a decrease in Treg numbers and impaired Treg functions, along with potential damage to Treg-related signaling pathways. Increasing Treg numbers and enhancing Treg function could lead to immunosuppressive effects on CD8+T cells. Recent research progress on Tregs in vitiligo has been summarized, highlighting various Treg-related therapies being investigated for clinical use. The current status of Treg-related therapeutic strategies and potential future directions for vitiligo treatment are also discussed. CONCLUSIONS: A deeper understanding of Tregs will be crucial for advancing Treg-related drug discovery and treatment development in vitiligo.

Intergenic risk variant rs56258221 skews the fate of naive CD4+ T cells via miR4464-BACH2 interplay in primary sclerosing cholangitis.

Primary sclerosing cholangitis (PSC) is an immune-mediated liver disease of unknown pathogenesis, with a high risk to develop cirrhosis and malignancies. Functional dysregulation of T cells and association with genetic polymorphisms in T cell-related genes were previously reported for PSC. Here, we genotyped a representative PSC cohort for several disease-associated risk loci and identified rs56258221 (BACH2/MIR4464) to correlate with not only the peripheral blood T cell immunophenotype but also the functional capacities of naive CD4+ T (CD4+ TN) cells in people with PSC. Mechanistically, rs56258221 leads to an increased expression of miR4464, in turn causing attenuated translation of BACH2, a major gatekeeper of T cell quiescence. Thereby, the fate of CD4+ TN is skewed toward polarization into pro-inflammatory subsets. Clinically, people with PSC carrying rs56258221 show signs of accelerated disease progression. The data presented here highlight the importance of assigning functional outcomes to disease-associated genetic polymorphisms as potential drivers of diseases.

Association between CD4+ T cells ATP levels and disease progression in patients with non­small cell lung cancer.

Introducing the exploration of stimulated CD4+ cells adenosine triphosphate (sATPCD4) levels for immune monitoring post non-small cell lung cancer (NSCLC) chemotherapy, the present study aimed to investigate its efficacy in gauging the potential risk of disease progression (PD) in patients with NSCLC. Therefore, a total of 89 patients with advanced NSCLC, who underwent chemotherapy between August 15 2022 and August 30 2023 at the Fifth Affiliated Hospital of Guangzhou Medical University (Guangzhou, China), were retrospectively studied. Patients were divided into the PD (n=21) and disease stability (non-PD; n=68) groups and their clinical data were compared. The thresholds for predicting PD were identified using receiver operating characteristics (ROC) curves. Multivariate logistic regression analysis was carried out to assess the association between peripheral blood markers and the incidence of PD. Therefore, post-chemotherapy, significant differences in white blood cell count, non-stimulated CD4+ cells ATP and sATPCD4 levels were obtained between patients in the PD and non-PD groups (P<0.05). In addition, sATPCD4 levels were notably decreased in the PD group compared with the non-PD group. Furthermore, ROC analysis revealed that the predictive threshold for PD was 224.5 ng/ml [area under the curve=0.887; 95% confidence interval, 0.811-0.963]. Additionally, patients with low immunity (ATP <224.5 ng/ml) exhibited a higher risk of PD compared with the high-immunity group (ATP >224.5 ng/ml; P<0.0001). Finally, multivariate logistic regression analysis suggested that sATPCD4 could serve as an independent factor for predicting NSCLC progression. Overall, the current study predicted that immune function could be possibly associated with the risk of PD in patients with NSCLC.

Topical Application of Nitrate Ameliorates Skin Fibrosis by Regulating ST2+CD4+ T Cells in Systemic Sclerosis Mouse Model.

Systemic sclerosis (SSc) is characterized by intractable multiorgan fibrosis caused by vascular and immune dysfunction. Currently, effective therapeutic options for patients with SSc are limited. Nitrate, an abundant nutrient in the diet, has been demonstrated to be preventative and therapeutic for several diseases. To determine whether nitrate can slow or reverse SSc progression, topical application of nitrate delivered by dissolving microneedles was used to treat a bleomycin (BLM)-induced dermal fibrosis mouse model. In this study, nitrate considerably attenuated dermal thickness, stiffness, and collagen deposition. Bulk RNA sequencing of skin revealed that Cd4 was a key hub gene in SSc nitrate therapy. Additionally, BLM-induced cytokines and chemokines were inhibited by nitrate, and CD4+ T cells infiltration markedly declined. Il4, Il6, Il13, and Tgfb expression in CD4+ T cells isolated from skin biopsies also significantly decreased. Mechanistically, Il1rl1, a type2 immune response inducer, was markedly repressed in isolated CD4+ T cells and dermal tissues after nitrate treatment. Remarkably, compared with wild type mice, mice lacking Il1rl1 showed impaired transcriptional profiles after intradermal BLM injection. Adoptive transfer of ST2+CD4+ T cells promoted bleomycin-induced Rag2-/- mice dermal fibrosis. Collectively, these findings demonstrate that nitrate targeting ST2+CD4+ T cells is an effective therapeutic option for SSc.

New expression of PD-L1 on activated CD4+ T cells opens up new opportunities for cell interactions and signaling.

Surface expression of programmed death-ligand 1 (PD-L1) is mainly observed on antigen presenting cells (APC) such as monocytes or dendritic cells (DCs). Our results showing a high expression of PD-L1 on human naïve CD4+ effector T-cells (TEFFs) and CD4+ regulatory T cells (TREGs) after activation with human DCs, allow us to propose a new role for PD-L1 and its ligands and their potential impact on new signaling pathways. Indeed, expression of PD-L1 on activated CD4+T cells could allow cis interaction with its ligands such as PD-1 and CD80, thus disrupting interactions with other signaling receptors, such as cytotoxic T-lymphocyte antigen-4 (CTLA-4) or CD28, which interact with CD80. The ability to compete with hypothetical configuration modifications that may cause a change in affinity/avidity for the trans and cis interactions between these proteins expressed on T cells and/or DCs is discussed. As the study of cancer is strongly influenced by the role of the PD-L1/PD-1 pathway and CD4+T cells, new interactions, cis and/or trans, between TEFFs, TREGs and tumor cells are also proposed. The presence of PD-L1 on activated CD4+ T cells could influence the quality of the cytotoxic T lymphocyte response during priming to provide other help signals.

The immune checkpoint TIGIT is upregulated on T cells during bacterial infection and is a potential target for immunotherapy.

Antibiotic resistance is a major public health threat, and alternatives to antibiotic therapy are urgently needed. Immunotherapy, particularly the blockade of inhibitory immune checkpoints, is a leading treatment option in cancer and autoimmunity. In this study, we used a murine model of Salmonella Typhimurium infection to investigate whether immune checkpoint blockade could be applied to bacterial infection. We found that the immune checkpoint T-cell immunoglobulin and ITIM domain (TIGIT) was significantly upregulated on lymphocytes during infection, particularly on CD4+ T cells, drastically limiting their proinflammatory function. Blockade of TIGIT in vivo using monoclonal antibodies was able to enhance immunity and improve bacterial clearance. The efficacy of anti-TIGIT was dependent on the capacity of the antibody to bind to Fc (fragment crystallizable) receptors, giving important insights into the mechanism of anti-TIGIT therapy. This research suggests that targeting immune checkpoints, such as TIGIT, has the potential to enhance immune responses toward bacteria and restore antibacterial treatment options in the face of antibiotic resistance.

Reactive Oxygen Species Modulate Th17/Treg Balance in Chlamydia psittaci Pneumonia via NLRP3/IL-1ß/Caspase-1 Pathway Differentiation.

Chlamydia psittaci pneumonia (CPP) is a lung disease caused by the infection with the Chla-mydia psittaci bacterium, which can lead to severe acute respiratory distress syndrome and systemic symptoms. This study explored the specific mechanisms underlying the impact of reactive oxygen species (ROS) on the Th17/Treg balance in CPP. The levels of ROS and the differentiation ratio of Th17/Treg in the peripheral blood of healthy individuals and CPP patients were measured using ELISA and flow cytometry, respectively. The association between the ROS levels and Th17/Treg was assessed using Pearson correlation analysis. The ROS levels and the Th17/Treg ratio were measured in CD4+ T cells following H2O2 treatment and NLRP3 inhibition. The effects of H2O2 treatment and NLRP3 inhibition on the NLRP3/IL-1ß/caspase-1 pathway were observed using immunoblotting. Compared to the healthy group, the CPP group exhibited increased levels of ROS in the peripheral blood, an elevated ratio of Th17 differentiation, and a decreased ratio of Treg differentiation. ROS levels were positively correlated with the Th17 cell proportion but negatively correlated with the Treg cell proportion. The ROS levels and NLRP3/IL-1ß/caspase-1 expression were up-regulated in CD4+ T cells after H2O2 treatment. Furthermore, there was an increase in Th17 differentiation and a decrease in Treg differentiation. Conversely, the NLRP3/IL-1ß/caspase-1 pathway inhibition reversed the effects of H2O2 treatment, with no significant change in the ROS levels. ROS regulates the Th17/Treg balance in CPP, possibly through the NLRP3/IL-1ß/caspase-1 pathway. This study provides a new perspective on the development of immunotherapy for CPP.

In Situ Characterization of Human Follicular Helper CD4 T Cells.

The development of an effective humoral response to pathogens and immunogens is a multiphase biological process, which is mediated by the coordinated function of specialized immune cell types in secondary lymphoid organs and particularly in T cell and follicular areas. More specifically, within the follicular/germinal center area, the orchestrated interplay between B cells, follicular helper CD4 T cells (Tfh), and stromal cells triggers a cascade of immune reactions leading to the development of memory B cells and plasma cells able to generate effective, antigen-specific antibodies. The role of Tfh cells in this process is critical. Given the need for vaccines capable to induce antibodies of high affinity, neutralizing activity, and durability, understanding the cellular and molecular mechanisms regulating Tfh cell development is of great importance. Here, we describe novel approaches for the comprehensive understanding of these cells and possible implications for future studies in vaccine development and the understanding of the pathogenesis of relevant diseases.