BACKGROUND: Regulatory dendritic cell (DCreg) subset exhibits a unique capacity for inducing immune tolerance among the variety subsets of dendritic cells (DCs) within gut-associated lymphoid tissues (GALTs). Fms-like tyrosine kinase 3 ligand (FLT3L) is involved in the differentiation of DCregs and the subsequent expansion of regulatory T-cells (Tregs) mediated by DCregs, though the precise mechanism remains poorly understood. This study aimed to explore the expansion mechanism of Treg induced by DCreg and the role of FLT3L in this process. METHODS: DCregs were distinguished from other DC subsets isolated from GALTs of BALB/c mice through a mixed lymphocyte reaction assay. The functions and mechanisms by which FLT3L promoted Treg expansion via DCregs were investigated in vitro through co-culture experiments involving DCregs and either CD4 + CD25 - T-cells or CD4 + CD25 + T-cells. Additionally, an in vivo experiment was conducted using a dextran sulfate sodium (DSS)-induced colitis model in mice. RESULTS: CD103 + CD11b + DC exhibited DCreg-like functionality and was identified as DCreg for subsequent investigation. Analysis of Foxp3 + Treg percentages within a co-culture system of CD4 + CD25 - T-cells and DCregs, with or without FLT3L, demonstrated the involvement of the FLT3/FLT3L axis in driving the differentiation of precursor T-cells into Foxp3 + Tregs induced by DCregs. Cell migration and co-culture assays revealed that the FLT3/FLT3L axis enhanced DCreg migration toward Tregs via the Rho pathway. Additionally, it was observed that DCregs could promote Treg proliferation through the Notch pathway, as inhibition of Notch signaling by DAPT (N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester) suppressed Treg expansion within the co-culture system of DCregs and CD4 + T-cells or CD4 + CD25 + T-cells. Furthermore, the FLT3/FLT3L axis influenced JAG1 expression in DCregs, indirectly modulating Treg expansion. In vivo experiments further established that FLT3L promoted DCreg expansion and restored Treg balance in DSS-induced colitis models, thereby ameliorating colitis symptoms in mice. CONCLUSION The FLT3/FLT3L axis is integral to the maintenance of DCreg function in Treg expansion.
Animals ; T-Lymphocytes, Regulatory/immunology* ; Dendritic Cells/immunology* ; Mice ; Mice, Inbred BALB C ; Membrane Proteins/metabolism* ; Receptors, Notch/metabolism* ; Lymphoid Tissue/metabolism* ; Signal Transduction/physiology* ; Coculture Techniques ; Flow Cytometry

BACKGROUND: Immunosuppression is closely related to the pathogenesis of sepsis, but the underlying mechanisms have not yet been fully elucidated. In this study, we aimed to examine the role of the Sterile Alpha Motif, Src Homology 3 domain and nuclear localization signal 1 (SAMSN1) in sepsis and elucidate its potential molecular mechanism in sepsis induced immunosuppression. METHODS: RNA sequencing databases were used to validate SAMSN1 expression in sepsis. The impact of SAMSN1 on sepsis was verified using gene knockout mice. Flow cytometry was employed to delineate how SAMSN1 affects immunity in sepsis, focusing on immune cell types and T cell functions. Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-mediated gene editing in RAW264.7 macrophages enabled interrogation of SAMSN1 's regulatory effects on essential macrophage functions, including cell proliferation and phagocytic capacity. The mechanism of SAMSN1 in the interaction between macrophages and T cells was investigated using the RAW264.7 cell line and primary cell lines. RESULTS: SAMSN1 expression was significantly increased in patients with sepsis and was positively correlated with sepsis mortality. Genetic deletion of Samsn1 in murine sepsis model improved T cell survival, elevated T cell cytolytic activity, and activated T cell signaling transduction. Concurrently, Samsn1 knockout augmented macrophage proliferation capacity and phagocytic efficiency. In macrophage, SAMSN1 binds to Kelch-like epichlorohydrin-associated protein 1 (KEAP1), causing nuclear factor erythroid 2-related factor 2 (NRF2) to dissociate from the KEAP1-NRF2 complex and translocate into the nucleus. This promotes the transcription of the coinhibitory molecules CD48/CD86/carcinoembryonic antigen related cell adhesion molecule 1 (CEACAM1), which bind to their corresponding receptors natural killer cell receptor 2B4/CD152/T cell immunoglobulin and mucin domain-containing protein 3 (TIM3) on the surface of T cells, inducing T-cell exhaustion. CONCLUSIONS SAMSN1 deletion augmented adaptive T cell immunity and macrophage phagocytic-proliferative dual function. Furthermore, it mediates the KEAP1-NRF2 axis, which affects the expression of coinhibitory molecules on macrophages, leading to T-cell exhaustion. This novel immunosuppression mechanism potentially provides a candidate molecular target for sepsis immunotherapy.
Animals ; NF-E2-Related Factor 2/metabolism* ; Mice ; Macrophages/immunology* ; Sepsis/metabolism* ; Kelch-Like ECH-Associated Protein 1/genetics* ; T-Lymphocytes/immunology* ; Humans ; Signal Transduction/physiology* ; RAW 264.7 Cells ; Mice, Knockout ; Mice, Inbred C57BL ; Male ; Flow Cytometry ; T-Cell Exhaustion

Hepatitis B virus (HBV)-specific CD8⁺ T cells play a central role in controlling HBV infection; however, their function is impaired during chronic HBV infection, manifesting as a state of dysfunction. Recent studies have revealed that CD8⁺ T cell dysfunction in chronic HBV infection differs from the classical exhaustion observed in other viral infections or tumors. In 2024, several pivotal studies further elucidated novel mechanisms underlying CD8⁺ T cell dysfunction in chronic HBV infection and identified new therapeutic targets, including 4-1BB and transforming growth factor-beta (TGF-β). This review, while elucidating the dysfunction of CD8⁺ T cells in chronic HBV infection and its underlying mechanisms, focuses on summarizing the key findings from these latest studies and explores their translational value and clinical significance.
Humans ; Hepatitis B, Chronic/virology* ; CD8-Positive T-Lymphocytes/immunology* ; Hepatitis B virus/physiology* ; Animals ; Transforming Growth Factor beta/immunology*

Immune thrombocytopenia (ITP) is a hemorrhagic autoimmune disease characterized by antibody-mediated platelet injury. ITP has complicated immunopathological mechanisms that need further elucidation. It is well known that the costimulatory molecules OX40 ligand (OX40L) and OX40 play essential roles in the immunological mechanisms of autoimmune diseases. Previously, we discovered that the expression of OX40L and OX40 is significantly increased in the peripheral blood mononuclear cells (PBMCs) of ITP patients. In our present study, OX40L-induced follicular helper T (Tfh) cells exhibited an activated phenotype with elevated expression of inducible T-cell costimulator (ICOS), programmed cell death protein-1 (PD-1), and cluster of differentiation 40 ligand (CD40L) in vitro. Moreover, aberrant OX40L‒OX40 expression might promote the Tfh1-to-Tfh2 shift in vivo, inducing the generation of autoantibodies by enhancing the helper function of Tfh cells for B lymphocytes in a mouse model, which might accelerate the progression of ITP. Additionally, signal transduction through the OX40L‒OX40 axis might be related to the activation of tumor necrosis factor receptor-associated factor (TRAF)‒nuclear factor-κB (NF-κB) and Janus kinase (JAK)‒signal transducer and activator of transcription (STAT) signaling pathways. Overall, OX40L‒OX40 signaling is proposed as a potential novel therapeutic target for ITP.
Animals ; OX40 Ligand/physiology* ; Purpura, Thrombocytopenic, Idiopathic/immunology* ; Cell Differentiation ; Mice ; T-Lymphocytes, Helper-Inducer/cytology* ; T Follicular Helper Cells/cytology* ; Signal Transduction ; Receptors, OX40 ; Mice, Inbred C57BL ; Humans ; Female

The ongoing pandemic of Coronavirus disease 19 (COVID-19) is caused by a newly discovered β Coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). How long the adaptive immunity triggered by SARS-CoV-2 can last is of critical clinical relevance in assessing the probability of second infection and efficacy of vaccination. Here we examined, using ELISA, the IgG antibodies in serum specimens collected from 17 COVID-19 patients at 6-7 months after diagnosis and the results were compared to those from cases investigated 2 weeks to 2 months post-infection. All samples were positive for IgGs against the S- and N-proteins of SARS-CoV-2. Notably, 14 samples available at 6-7 months post-infection all showed significant neutralizing activities in a pseudovirus assay, with no difference in blocking the cell-entry of the 614D and 614G variants of SARS-CoV-2. Furthermore, in 10 blood samples from cases at 6-7 months post-infection used for memory T-cell tests, we found that interferon γ-producing CD4
Adaptive Immunity/physiology* ; Adult ; Aged ; Antibodies, Neutralizing/blood* ; COVID-19/immunology* ; Cohort Studies ; Female ; Humans ; Immunoglobulin G/blood* ; Male ; Middle Aged ; SARS-CoV-2/immunology* ; T-Lymphocytes/physiology* ; Time Factors ; Viral Proteins/immunology*

This special feature contains three review articles that summarize recent advances pertaining to tumor immunobiology. Normalization of antitumor immunity through checkpoint inhibitors has achieved significant clinical success and benefited many cancer patients. However, not all cancer patients respond to these treatments, and among the responders, some may develop resistance and others may suffer autoimmunity that requires intervention. Tumor immunotherapy holds promise for further improving the survival of cancer patients, but deeper understanding of immunological networks that regulate anti- and pro-tumor immunity is needed. The review papers collected in this issue cover a few topics that may stimulate future interest in the relevant research field.
Humans ; Immunotherapy, Adoptive/methods* ; Lymphatic Vessels/physiology* ; MicroRNAs/physiology* ; Neoplasms/therapy* ; Receptors, Chimeric Antigen/immunology* ; T-Lymphocytes/immunology*

The 2019 novel coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has occurred in China and around the world. SARS-CoV-2-infected patients with severe pneumonia rapidly develop acute respiratory distress syndrome (ARDS) and die of multiple organ failure. Despite advances in supportive care approaches, ARDS is still associated with high mortality and morbidity. Mesenchymal stem cell (MSC)-based therapy may be an potential alternative strategy for treating ARDS by targeting the various pathophysiological events of ARDS. By releasing a variety of paracrine factors and extracellular vesicles, MSC can exert anti-inflammatory, anti-apoptotic, anti-microbial, and pro-angiogenic effects, promote bacterial and alveolar fluid clearance, disrupt the pulmonary endothelial and epithelial cell damage, eventually avoiding the lung and distal organ injuries to rescue patients with ARDS. An increasing number of experimental animal studies and early clinical studies verify the safety and efficacy of MSC therapy in ARDS. Since low cell engraftment and survival in lung limit MSC therapeutic potentials, several strategies have been developed to enhance their engraftment in the lung and their intrinsic, therapeutic properties. Here, we provide a comprehensive review of the mechanisms and optimization of MSC therapy in ARDS and highlighted the potentials and possible barriers of MSC therapy for COVID-19 patients with ARDS.
Adoptive Transfer ; Alveolar Epithelial Cells ; pathology ; Animals ; Apoptosis ; Betacoronavirus ; Body Fluids ; metabolism ; CD4-Positive T-Lymphocytes ; immunology ; Clinical Trials as Topic ; Coinfection ; prevention & control ; therapy ; Coronavirus Infections ; complications ; immunology ; Disease Models, Animal ; Endothelial Cells ; pathology ; Extracorporeal Membrane Oxygenation ; Genetic Therapy ; methods ; Genetic Vectors ; administration & dosage ; therapeutic use ; Humans ; Immunity, Innate ; Inflammation Mediators ; metabolism ; Lung ; pathology ; physiopathology ; Mesenchymal Stem Cell Transplantation ; methods ; Mesenchymal Stem Cells ; physiology ; Multiple Organ Failure ; etiology ; prevention & control ; Pandemics ; Pneumonia, Viral ; complications ; immunology ; Respiratory Distress Syndrome, Adult ; immunology ; pathology ; therapy ; Translational Medical Research

Astragalus membranaceus may be a potential therapy for childhood asthma but its driving mechanism remains elusive. The main components of A. membranaceus were identified by HPLC. The children with asthma remission were divided into two combination group (control group, the combination of budesonide and terbutaline) and A. membranaceus group (treatment group, the combination of budesonide, terbutaline and A. membranaceus). The therapeutic results were compared between two groups after 3-month therapy. Porcine peripheral blood mononuclear cells (PBMCs) were isolated from venous blood by using density gradient centrifugation on percoll. The levels of FoxP3, EGF-β, IL-17 and IL-23 from PBMCs and serum IgE were measured. The relative percentage of Treg/Th17 cells was determined using flow cytometry. The main components of A. membranaceus were calycosin-7-O-glucoside, isoquercitrin, ononin, calycosin, quercetin, genistein, kaempferol, isorhamnetin and formononetin, all of which may contribute to asthma therapy. Lung function was significantly improved in the treatment group when compared with a control group (P < 0.05). The efficacy in preventing the occurrence of childhood asthma was higher in the treatment group than the control group (P < 0.05). The levels of IgE, IL-17 and IL-23 were reduced significantly in the treatment group when compared with the control group, while the levels of FoxP3 and TGF-β were increased in the treatment group when compared with the control group (P < 0.05). A. membranaceus increased the percentage of Treg cells and reduced the percentage of Th17 cells. A. membranaceus is potential natural product for improving the therapeutic efficacy of combination therapy of budesonide and terbutaline for the children with asthma remission by modulating the balance of Treg/Th17 cells.
Animals ; Asthma ; drug therapy ; immunology ; Astragalus propinquus ; chemistry ; Budesonide ; administration & dosage ; Cells, Cultured ; Child ; Child, Preschool ; Cytokines ; metabolism ; Drugs, Chinese Herbal ; administration & dosage ; pharmacology ; Female ; Humans ; Immunologic Factors ; administration & dosage ; pharmacology ; Leukocytes, Mononuclear ; drug effects ; metabolism ; Lung ; drug effects ; physiology ; Male ; Swine ; T-Lymphocytes, Regulatory ; cytology ; drug effects ; Terbutaline ; administration & dosage ; Th17 Cells ; cytology ; drug effects ; Treatment Outcome

Objective The aim of this study was to evaluate the diagnostic performance of T-SPOT.TB for tuberculous lymphadenitis. Methods Suspected tuberculous lymphadenitis patients between September 2010 and September 2018 who had both peripheral blood T-SPOT.TB test and lymph node biopsy were retrospectively enrolled in this study. The cutoff value of T-SPOT.TB test for peripheral blood was set as 24 spot forming cell (SFC)/10 ⁶ periphreral blood monocyte cell (PBMC) according to the instruction of testing kits. The gold standard for diagnosis of TBL was the combination of microbiology results, histopathology results and patient's response to anti-TB treatment. Diagnostic efficacy of T-SPOT.TB was evaluated, including sensitivity, specificity, accuracy, predictive values, and likelihood ratio. Results Among 91 patients who met the inclusion criteria, we excluded 8 cases with incomplete clinical information and 6 cases who lost to follow-up. According to the gold standard, there were 37 cases of true TBL (9 confirmed TBL and 28 probable TBL), 30 cases of non-TBL, and 10 cases of clinically indeterminate diagnosis who were excluded from the final analyses. The T-SPOT.TB tests yielded 43 cases of positive response and 24 cases of negative response. The sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (PLR) and negative likelihood ratio (NLR) of peripheral blood T-SPOT.TB for diagnosing TBL were 89.2%, 66.7%, 79.1%, 76.7%, 83.3%, 2.68 and 0.16, respectively. The number of SFCs of T-SPOT.TB in TBL patients [432(134-1264)/10 ⁶ PBMCs] was higher than that in non-TBL patients [0 (0-30) /10 ⁶PBMCs] with a significant difference (Z=-5.306, P <0.001). Conclusion T-SPOT.TB is a rapid and simple diagnostic test for TBL with a high sensitivity and negative predictive value.
Adolescent ; Adult ; Aged ; Female ; Humans ; Interferon-gamma Release Tests ; Male ; Middle Aged ; Mycobacterium tuberculosis/physiology* ; T-Lymphocytes/immunology* ; Tuberculosis, Lymph Node/diagnosis* ; Young Adult

OBJECTIVETo study the relationship between the expression of peripheral blood HLA-DR, CD4CD25 regulatory T cells, IL-17 and IL-27 with liver damage in children with human cytomegalovirus (HCMV) infection.

METHODSTwenty-one HCMV children with liver damage and twenty-one HCMV children without liver damage were enrolled in this study. The expression of peripheral blood HLA-DR and CD4CD25 regulatory T cells was detected by flow cytometry. Plasma levels of IL-17 and IL-27 were measured using ELISA.

RESULTSThe plasma levels of IL-17 and IL-27 in children with liver damage were significantly higher than in those without liver damage, while the expression of peripheral blood CD4CD25 regulatory T cells was lower than in those without liver damage (P<0.05). Plasma IL-17 and IL-27 levels were negatively correlated with the expression of peripheral blood CD4CD25 regulatory T cells (P<0.01).

CONCLUSIONSImmune imbalance mediated by CD4CD25 regulatory T cells and over-expression of IL-17 and IL-27 may be involved in the pathogenesis of liver damage in children with HCMV infection.

CD4 Antigens ; immunology ; Cytomegalovirus ; physiology ; Cytomegalovirus Infections ; blood ; complications ; genetics ; Female ; Flow Cytometry ; HLA-DR Antigens ; genetics ; immunology ; Humans ; Infant ; Interleukin-17 ; blood ; genetics ; Interleukin-2 Receptor alpha Subunit ; immunology ; Interleukins ; blood ; genetics ; Liver ; injuries ; metabolism ; Liver Diseases ; blood ; etiology ; immunology ; Male ; T-Lymphocytes, Regulatory ; immunology