BACKGROUND: T cell dysfunction, which includes exhaustion, anergy, and senescence, is a distinct T cell differentiation state that occurs after antigen exposure. Although T cell dysfunction has been a cornerstone of cancer immunotherapy, its potential in transplant research, while not yet as extensively explored, is attracting growing interest. Interferon regulatory factor 4 (IRF4) has been shown to play a pivotal role in inducing T cell dysfunction. METHODS: A novel ultra-low-dose combination of Trametinib and Rapamycin, targeting IRF4 inhibition, was employed to investigate T cell proliferation, apoptosis, cytokine secretion, expression of T-cell dysfunction-associated molecules, effects of mitogen-activated protein kinase (MAPK) and mammalian target of rapamycin (mTOR) signaling pathways, and allograft survival in both in vitro and BALB/c to C57BL/6 mouse cardiac transplantation models. RESULTS: In vitro , blockade of IRF4 in T cells effectively inhibited T cell proliferation, increased apoptosis, and significantly upregulated the expression of programmed cell death protein 1 (PD-1), Helios, CD160, and cytotoxic T lymphocyte-associated antigen (CTLA-4), markers of T cell dysfunction. Furthermore, it suppressed the secretion of pro-inflammatory cytokines interferon (IFN)-γ and interleukin (IL)-17. Combining ultra-low-dose Trametinib (0.1 mg·kg -1 ·day -1 ) and Rapamycin (0.1 mg·kg -1 ·day -1 ) demonstrably extended graft survival, with 4 out of 5 mice exceeding 100 days post-transplantation. Moreover, analysis of grafts at day 7 confirmed sustained IFN regulatory factor 4 (IRF4) inhibition, enhanced PD-1 expression, and suppressed IFN-γ secretion, reinforcing the in vivo efficacy of this IRF4-targeting approach. The combination of Trametinib and Rapamycin synergistically inhibited the MAPK and mTOR signaling network, leading to a more pronounced suppression of IRF4 expression. CONCLUSIONS Targeting IRF4, a key regulator of T cell dysfunction, presents a promising avenue for inducing transplant immune tolerance. In this study, we demonstrate that a novel ultra-low-dose combination of Trametinib and Rapamycin synergistically suppresses the MAPK and mTOR signaling network, leading to profound IRF4 inhibition, promoting allograft acceptance, and offering a potential new therapeutic strategy for improved transplant outcomes. However, further research is necessary to elucidate the underlying pharmacological mechanisms and facilitate translation to clinical practice.
Animals ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Interferon Regulatory Factors/metabolism* ; Heart Transplantation/methods* ; T-Lymphocytes/immunology* ; Sirolimus/therapeutic use* ; Pyridones/therapeutic use* ; Graft Survival/drug effects* ; Pyrimidinones/therapeutic use* ; Cell Proliferation/drug effects* ; Apoptosis/drug effects* ; Male ; Signal Transduction/drug effects*

BACKGROUND: Peripheral helper T (T PH ) cells are uniquely positioned within pathologically inflamed non-lymphoid tissues to stimulate B-cell responses and antibody production. However, the phenotype, function, and clinical relevance of T PH cells in hepatocellular carcinoma (HCC) are currently unknown. METHODS: Blood, tumor, and peritumoral liver tissue samples from 39 HCC patients (Sep 2016-Aug 2017) and 101 HCC patients (Sep 2011-Dec 2012) at the Third Affiliated Hospital of Sun Yat-sen University were used. Flow cytometry was used to quantify the expression, phenotype, and function of T PH cells. Log-rank tests were performed to evaluate disease-free survival and overall survival in samples from 39 patients and 101 patients with HCC. T PH cells, CD19 + B cells, and T follicular helper (T FH ) cells were cultured separately in vitro or isolated from C57/B6L mice in vivo for functional assays. RESULTS: T PH cells highly infiltrated tumor tissues, which was correlated with tumor size, early recurrence, and shorter survival time. The tumor-infiltrated T PH cells showed a unique ICOS hi CXCL13 + IL-21 - MAF + BCL-6 - phenotype and triggered naïve B-cell differentiation into regulatory B cells. Triggering programmed cell death protein 1 (PD-1) induced the production of C-X-C motif chemokine ligand 13 (CXCL13) by T PH cells, which then suppressed tumor-specific immunity and promoted disease progression. CONCLUSION Our study reveals a novel regulatory mechanism of T PH cell-regulatory B-cell-mediated immunosuppression and provides an important perspective for determining the balance between the differentiation of protumorigenic T PH cells and that of antitumorigenic T FH cells in the HCC microenvironment.
Carcinoma, Hepatocellular/metabolism* ; Liver Neoplasms/metabolism* ; Humans ; T-Lymphocytes, Helper-Inducer/metabolism* ; Animals ; Mice ; Male ; Female ; Mice, Inbred C57BL ; Middle Aged ; B-Lymphocytes, Regulatory/metabolism* ; Flow Cytometry ; Interleukin-21 ; Aged ; Chemokine CXCL13/metabolism*

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

This article reviews the role of different types of T lymphocyte subpopulations in pathological cardiac fibrosis remodeling. T helper 17 (Th17) cells are implicated in promoting the development of pathological cardiac fibrosis remodeling, while regulatory T (Treg) cells exert an immunosuppressive functions as negative regulators, attributing to their interleukin-10 (IL-10) secretion and functional phenotype. Th1 and Th2 cells are involved in different stages of the inflammatory response in pathological cardiac fibrosis remodeling, and their influence varies according to the pathological mechanisms of different cardiac diseases. In addition, CD8⁺ T cells regulate the activation and polarization of macrophages, promote the secretion of granzyme B, induce cardiomyocyte apoptosis, and aggravate cardiac fibrosis post-myocardial infarction. Considering the limitation of cytokine modulation in clinical therapy of heart failure, targeting T-cell co-stimulatory molecules emerges as a promising strategy for treating pathologic cardiac remodeling. Future research will explore chimeric antigen receptor modified T cells (CAR-T cells) technology and targeted regulation of Treg cells quantity and phenotype, for both of which have the potential to become effective methods for treating heart disease.
Humans ; Fibrosis ; T-Lymphocytes, Regulatory/immunology* ; Ventricular Remodeling/immunology* ; Myocardium/immunology* ; Animals ; Th17 Cells/immunology* ; Interleukin-10/metabolism* ; Th1 Cells/immunology* ; Th2 Cells/immunology*

Asthma is a chronic inflammatory disease involving multiple inflammatory cells and cytokines. Its pathogenesis is complex, involving various cells and cytokines. Traditional Chinese medicine(TCM) theory suggests that the pathogenesis of asthma is closely related to the dysfunction of internal organs such as the lungs, spleen, and kidneys. In contrast, modern immunological studies have revealed the central role of T helper 1(Th1)/T helper 2(Th2) and T helper 17(Th17)/regulatory T(Treg) cellular immune imbalance in the pathogenesis of asthma. Th1/Th2 imbalance is manifested as hyperfunction of Th2 cells, which promotes the synthesis of immunoglobulin E(IgE) and the activation of eosinophil granulocytes, leading to airway hyperresponsiveness and inflammation.Meanwhile, Th17/Treg imbalance exacerbates the inflammatory response in the airways, further contributing to asthma pathology.Currently, therapeutic strategies for asthma are actively exploring potential targets for regulating the balance of Th1/Th2 and Th17/Treg immune responses. These targets include cytokines, transcription factors, key proteins, and non-coding RNAs. Precisely regulating the expression and function of these targets can effectively modulate the activation and differentiation of immune cells. In recent years,traditional Chinese medicine active ingredients have shown unique potential and prospects in the field of asthma treatment. Based on this, the present study systematically summarizes the efficacy and specific mechanisms of TCM active ingredients in treating asthma by regulating Th1/Th2 and Th17/Treg immune balance through literature review and analysis. These active ingredients, including flavonoids, terpenoids, polysaccharides, alkaloids, and phenolic acids, exert their effects through various mechanisms, such as inhibiting the activation of inflammatory cells, reducing the release of cytokines, and promoting the normal differentiation of immune cells. This study aims to provide a solid foundation for the widespread application and in-depth development of TCM in asthma treatment and to offer new ideas for clinical research and drug development of asthma.
Asthma/genetics* ; Humans ; Drugs, Chinese Herbal/chemistry* ; Th2 Cells/drug effects* ; Th17 Cells/drug effects* ; T-Lymphocytes, Regulatory/drug effects* ; Th1 Cells/drug effects* ; Animals ; Cytokines/immunology* ; Medicine, Chinese Traditional

This study investigated the therapeutic effects of Yiguanjian on dry eye in rats and its mechanisms involving the T helper cell 17(Th17)/regulatory T cell(Treg) balance. The rat model of dry eye was established by administrating 0.2% benzalkonium chloride solution in eye drops. After successful modeling, the rats were treated with Yiguanjian for 4 consecutive weeks. The Schirmer test was carried out to assess the lacrimal gland function, corneal fluorescence staining to detect corneal injury, hematoxylin-eosin staining to observe corneal histopathology, enzyme-linked immunosorbent assay to measure serum levels of interleukin(IL)-6, IL-8, IL-17A, IL-21, and tumor necrosis factor-α(TNF-α), RT-qPCR to analyze mRNA levels of retinoic acid receptor-related orphan receptor gamma t(RORγt) and forkhead box protein p3(Foxp3) in the corneal tissue, immunofluorescence double staining to evaluate RORγt and Foxp3 expression in the lacrimal gland tissue, and Western blot to quantify the protein levels of signal transducer and activator of transcription 3(STAT3), phosphorylated STAT3(p-STAT3), Janus kinase 2(Jak2), phosphorylated Jak2(p-Jak2), RORγt, and Foxp3 in the corneal tissue. The results demonstrated that Yiguanjian increased tear secretion(P<0.01), alleviated corneal damage and pathological changes, and lowered the serum levels of IL-6, IL-8, IL-17A, IL-21, and TNF-α(P<0.05) in model rats. Additionally, Yiguanjian decreased the ratio of RORγt to Foxp3 in the corneal and lacrimal gland tissue(P<0.01), downregulated the protein levels of STAT3, Jak2, and RORγt(P<0.05), upregulated the protein level of Foxp3(P<0.05), and inhibited phosphorylation of STAT3 and Jak2(P<0.01). These findings indicate that Yiguanjian ameliorates ocular surface dysfunction in dry eye rats by restoring Th17/Treg balance in the corneal and lacrimal gland tissue and suppressing systemic inflammatory cytokine release, thus mitigating ocular surface inflammation.
Animals ; Rats ; T-Lymphocytes, Regulatory/immunology* ; Drugs, Chinese Herbal/administration & dosage* ; Th17 Cells/immunology* ; Male ; Rats, Sprague-Dawley ; Dry Eye Syndromes/genetics* ; Nuclear Receptor Subfamily 1, Group F, Member 3/immunology* ; Lacrimal Apparatus/immunology* ; Humans ; STAT3 Transcription Factor/immunology*

Objective This study investigated the regulatory effect of high mobility group protein B1 (HMGB1) in the peripheral blood of patients with primary immune thrombocytopenia (ITP) on myeloid dendritic cells (mDC) and Th17/regulatory T cells (Treg) balance. Methods The study enrolled 30 newly diagnosed ITP patients and 30 healthy controls.Flow cytometry was used to measure the proportion of mDC, Th17, and Treg cells in the peripheral blood of ITP patients and healthy controls. ELISA was conducted to quantify the serum levels of HMGB1, interleukin 6 (IL-6), IL-23, IL-17, and transforming growth factor β(TGF-β). The mRNA levels of retinoic acid-related orphan receptor γt(RORγt) and forehead box P3(FOXP3) were detected by real-time PCR. The correlation between the abovementioned cells, cytokines, and platelet count was assessed using Pearson linear correlation analysis. Results The proportion of Th17 cells and the expression levels of HMGB1, IL-6, IL-23, IL-17 and the level of RORγt mRNA in the peripheral blood of ITP patients were higher than those in healthy controls. However, the Treg cell proportion and TGF-β level were lower in ITP patients than those in healthy controls. In patients with ITP, the proportion of mDC and the level of FOXP3 mRNA did not show significant changes. The proportion of mDC cells was significantly correlated with the expression of IL-6 and IL-23. Moreover, the expression of HMGB1 showed a significant correlation with the expression of mDC, IL-6, IL-23, RORγt mRNA, and IL-17. Notably, both the proportion of mDC cells and the expression of HMGB1 were negatively correlated with platelet count. Conclusion The high expression of HMGB1 in peripheral blood of ITP patients may induce Th17/Treg imbalance by promoting the maturation of mDC and affecting the secretion of cytokines, thereby potentially playing a role in the immunological mechanism of ITP.
Humans ; Th17 Cells/cytology* ; HMGB1 Protein/genetics* ; T-Lymphocytes, Regulatory/cytology* ; Female ; Male ; Dendritic Cells/metabolism* ; Adult ; Middle Aged ; Purpura, Thrombocytopenic, Idiopathic/genetics* ; Nuclear Receptor Subfamily 1, Group F, Member 3/genetics* ; Young Adult ; Interleukin-23/blood* ; Interleukin-17/blood* ; Interleukin-6/blood* ; Forkhead Transcription Factors/genetics* ; Myeloid Cells/cytology* ; Aged

Cytotoxic CD4⁺ T cells (CD4⁺ CTLs) represent a novel subset of T cells with cytotoxic effects. They recognize target cells in an antigen-specific manner, relying on class II major histocompatibility complex (MHC-II) interactions. CD4⁺ CTLs exert cytotoxic effects on target cells by secreting cytotoxic molecules such as granzymes, perforin, and granulysin. Recent studies have revealed their significant roles in various autoimmune diseases. This review focuses on the differentiation, phenotypic characteristics, and roles of CD4⁺ CTLs in different types of autoimmune disorders, aiming to provide new insights for the prevention and treatment of these diseases.
Humans ; Autoimmune Diseases/immunology* ; CD4-Positive T-Lymphocytes/immunology* ; Animals ; T-Lymphocytes, Cytotoxic/immunology* ; Perforin/immunology* ; Granzymes/immunology*

Objective Zinc finger protein 335 (Zfp335) plays a crucial role in the early development of thymic T cells and the differentiation of peripheral T cell subpopulations. The objective of this study is to investigate the role and underlying mechanisms of Zfp335 in the regulation of regulatory T cell (Treg) within tumor immunity. Methods The Zfp335 gene was specifically knocked out in Treg using tamoxifen (Zfp335^fl/fl FOXP3^creERT2), and the MC38 tumor model was established. On the 7th day after tumor inoculation, tumor size was observed and measured. Tumor size was monitored and recorded daily starting from day 7 post-inoculation. On day 12, tumors were harvested, and the proportions of CD4⁺ T cells, CD8⁺ T cells, and Treg were analyzed by flow cytometry. Additionally, the mitochondrial function of effector regulatory T cell (eTreg) was assessed. Results From day 10 post-tumor inoculation, tumor volume in the Zfp335^CKO group was significantly reduced compared to that of the wild-type (WT) group. Furthermore, the infiltration of CD4⁺ and CD8⁺ T cells, along with their respective effector cells, was significantly higher in the Zfp335^CKO group than in the WT group. The proportions of CD4⁺ and CD8⁺ T cells producing interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) were also significantly increased in the Zfp335^CKO group compared to that of the WT group. In addition, the percentage of CD8⁺ T cells secreting granzyme B (GzmB) was significantly higher in the Zfp335^CKO group than that in the WT group. In contrast, the proportion of Treg and inducible T cell co-stimulator (ICOS)⁺ Treg in the Zfp335^CKO group was significantly lower than that in the WT group. Finally, the expression level of Mitotracker Deep Red in eTreg from the Zfp335^CKO group was significantly reduced compared to that in the WT group. Conclusion During tumorigenesis, the specific deletion of Zfp335 impairs Treg activation, which is related to decreased mitochondrial function in eTreg. In Zfp335^CKO mice. Tumors exhibit increased infiltration of effector T cells, accompanied by elevated levels of cytotoxic cytokines, ultimately enhancing resistance to tumor progression.
Animals ; T-Lymphocytes, Regulatory/metabolism* ; Mice ; CD8-Positive T-Lymphocytes/immunology* ; Neoplasms/genetics* ; Cell Line, Tumor ; Mice, Inbred C57BL ; Mice, Knockout ; DNA-Binding Proteins/genetics* ; Female

Objective To investigate the therapeutic effects of interleukin 23p19(IL-23p19) monoclonal antibody in the MRL/lpr lupus-like mouse model. Methods A total of 36 female MRL/lpr mice aged 8 weeks were randomly divided into 6 groups: PBS group (blank control), IgG group (isotype IgG), dexamethasone (DEX) group (positive control), and three IL-23p19 monoclonal antibody treatment groups with different dose gradients: low dose (LD, 1 mg/kg), medium dose (MD, 3 mg/kg), and high dose (HD, 10 mg/kg). Drug intervention began at 12 weeks of age via tail vein injection. Urine protein levels were measured using urine protein test strips; serum anti-dsDNA antibody levels were detected by ELISA; serum creatinine and blood urea nitrogen levels were measured using an automatic biochemical analyzer; renal histopathological changes were analyzed by H&E and PAS staining; immunofluorescence was used to assess IgG and C3 immune complex deposition in kidney tissues; flow cytometry was employed to examine the expression of T helper 1(Th1), Th2, Th17, T follicular helper (Tfh), and regulatory T cells(Treg) cell subsets in the spleen; and RT-qPCR was used to detect the expression of related transcription factors in the spleen. Results IL-23p19 monoclonal antibody reduced urine protein levels, alleviated splenomegaly, improved renal function, and decreased anti-dsDNA antibody levels in MRL/lpr mice. It also mitigated glomerulonephritis and reduced renal immune complex deposition. Furthermore, IL-23p19 monoclonal antibody significantly suppressed the proportion of Th1 and Th17 cells while upregulating Treg cell proportion in the spleen. Additionally, it downregulated T-bet and retinoic acid receptor-related orphan receptor γt (RORγt) mRNA levels and upregulated forkhead box P3(FOXP3) mRNA levels in the spleen. Conclusions IL-23p19 monoclonal antibody demonstrates significant therapeutic effects in MRL/lpr mice, likely through modulation of the Th17/Treg cell balance.
Animals ; Female ; Mice, Inbred MRL lpr ; T-Lymphocytes, Regulatory/drug effects* ; Th17 Cells/drug effects* ; Antibodies, Monoclonal/therapeutic use* ; Interleukin-23 Subunit p19/immunology* ; Mice ; Lupus Nephritis/drug therapy* ; Kidney/drug effects* ; Antibodies, Antinuclear/blood*