Regulatory T (Treg) cells are a special immunosuppressive subset of cluster of differentiation 4-positive (CD4^+‍)‍-T lymphocytes and play a pivotal role in the establishment of immune homeostasis in vivo (Zhang et al., 2021). The transcription factor forkhead box protein P3 (Foxp3) is the master marker of Treg cells, which is highly expressed in Treg cells and is also essential for their suppressive function (Hori et al., 2003). In addition to Foxp3, other regulators of Treg cells have been discovered (Wu et al., 2017, 2022; Wu and Sun, 2023a, 2023b); however, a deeper understanding of the regulation of these cells is required.
T-Lymphocytes, Regulatory ; Gene Expression Regulation ; Forkhead Transcription Factors/metabolism*

OBJECTIVETo review the current research into Foxp3(+) regulatory T cells (Treg) cell surface molecules, plasticity of Treg cells and mechanisms of Treg cell suppression and to explore the possibilities to interfere in Treg cell suppression of anti-tumor immunity.

DATA SOURCESA literature search of all English articles was performed on the online electronic PubMed database dated 1995 to 2010. The keywords searched included: CD4(+)CD25(+)Foxp3(+) regulatory T lymphocytes, cancer, and immunotherapy. After finding relevant articles within these search limits, a manual search was conducted through the references from these articles.

STUDY SELECTIONArticles regarding the role of Treg cells in tumor immunity and the utility of Treg cells in tumor immunotherapy.

RESULTSThe results show that significant numbers of Treg cells are found in many tumors and it has been shown that the number of tumor infiltrating Treg cells correlates with adverse clinic outcomes. Treg cells are emerging as a key component of acquired tolerance to tumors.

CONCLUSIONSSeveral mechanisms of immunosuppression can be mediated by Treg cell function. Distinct immunosuppressive molecules expressed by Treg cells or diverse molecules related to Treg induction or migration represent potential drug targets for cancer immunotherapy.

Forkhead Transcription Factors ; metabolism ; Humans ; Immunosuppression ; methods ; Immunotherapy ; methods ; Neoplasms ; immunology ; therapy ; T-Lymphocytes, Regulatory ; metabolism

BACKGROUNDSystemic sclerosis (SSc) is an autoimmune disease that has three major components: inflammation, fibrosis, and vasculopathy. T-helper 17 cell (Th17) and regulatory T cell (Treg) are considered to be critical for autoimmune disease pathogenesis. The role of Th17 and Treg in SSc is still unclear. The aim of this study was to detect the presence of Th17s and CD4(+)CD25(+) Tregs in peripheral blood samples from SSc patients and to investigate the possible roles of these two T cell subsets in SSc pathogenesis.

METHODSTh17s (CD4 and IL-17 positive) and CD4(+)CD25(+) Tregs (CD4, CD25 and Foxp3 positive) in the peripheral blood mononuclear cells of 53 SSc patients and 27 healthy controls were counted by flow cytometry. The differences between SSc and control patients were analyzed. Clinical parameters, including disease duration, duration of the second symptoms, Modified Rodnan Skin Score (MRSS), anti-topoisomerase I antibody, anti-U1 ribonucleoprotein (RNP) antibody, systemic involvements, pulmonary function test (PFT) and high resolution computed tomography (HRCT) score were prospectively collected following EUSTAR (EULAR scleroderma trial and research group) protocols. The correlations between the experimental and clinical data were investigated.

RESULTSThe ratio of Th17 in SSc patients was significantly elevated compared to healthy controls (8.74% vs. 4.41%, P < 0.001). The amount of Th17 was positively correlated with disease duration (R = 0.531, P = 0.013) and duration of the second symptoms (R = 0.505, P = 0.023). The ratio of CD4(+)CD25(+) Treg in SSc patients also significantly differed from the healthy controls (3.04% vs. 2.24%, P = 0.018). Elevated Tregs were more frequently observed in patients with a high interstitial lung disease (ILD) score on computed tomography (24/36) compared with patients with normal ILD scores (4/12, P = 0.043). Elevated Tregs were also more often observed in patients with low carbon monoxide diffusing capacity (DLCO) (24/34) compared with patients with normal DLCO (4/11, P = 0.042).

CONCLUSIONST cell abnormalities are remarkable in systemic sclerosis. Th17s proliferate and their numbers increase with lengthened disease duration. Th17s might participate in both inflammation and fibrosis by secreting IL-17. CD4(+)CD25(+) Tregs also proliferate in SSc and may play important roles in promoting fibrosis.

CD4-Positive T-Lymphocytes ; metabolism ; Cells, Cultured ; Flow Cytometry ; Humans ; Interleukin-2 Receptor alpha Subunit ; metabolism ; Scleroderma, Systemic ; immunology ; metabolism ; T-Lymphocytes, Regulatory ; immunology ; metabolism ; Th17 Cells ; metabolism

This study aimed to investigate the anti-inflammatory effect of astragaloside Ⅳ in mice with ulcerative colitis(UC) and its effect on the percentage of peripheral blood T helper(Th17) cells. Following the establishment of UC mouse model with 2% sodium dextran sulfate(DSS), mice in the positive control group and low-and high-dose astragaloside Ⅳ groups were treated with corresponding drugs by gavage. Disease activity index(DAI) was calculated, and serum interleukin-17(IL-17), tumor necrosis factor-α(TNF-α), and transforming growth factor-β(TGF-β) levels were assayed by ELISA. The pathological changes in colon tissue were observed by HE staining, and Th17/regulatory T cells(Treg) ratio in the peripheral blood was determined by flow cytometry. Western blot was conducted for detecting the relative protein expression levels of forkhead box protein P3(Foxp3) and retinoic acid-related orphan nuclear receptor γT(ROR-γt). The findings demonstrated that in normal mice, the colonic structure was intact. The goblet cells were not reduced and the glands were neatly arranged, with no mucosal erosion, bleeding, or positive cell infiltration. In the model group, the colonic mucosal structure was seriously damaged, manifested as disordered arrangement or missing of glands, vascular dilatation, congestion, and massive inflammatory cell infiltration. The pathological injury of colon tissue was alleviated to varying degrees in drug treatment groups. Compared with the normal group, the model group exhibited elevated percentage of Th17 cells, increased IL-17 and TNF-α content, up-regulated relative ROR-γt protein expression, lowered TGF-β, reduced percentage of Treg cells, and down-regulated relative Foxp3 protein expression. The comparison with the model group showed that DAI score, pathological score, percentage of Th17 cells, IL-17 and TNF-α content, and relative ROR-γt protein expression in the positive control group, low-dose astragaloside Ⅳ group, and high-dose astragaloside Ⅳ group were decreased, while TGF-β content, percentage of Treg cells, and relative Foxp3 protein expression were increased. The DAI score, pathological score, percentage of Th17 cells, IL-17 and TNF-α content, and relative ROR-γt protein expression in the low-dose astragaloside Ⅳ group were higher than those in the positive control group, whereas the content of TGF-β, percentage of Treg cells, and relative Foxp3 protein expression were lower. DAI score, pathological score, percentage of Th17 cells, IL-17 and TNF-α content, relative ROR-γt protein expression in the high-dose astragaloside Ⅳ group declined in contrast to those in the low-dose astragaloside Ⅳ group, while the TGF-β content, percentage of Treg cells, and relative Foxp3 protein expression rose. There was no significant difference between the positive control group and the high-dose astragaloside Ⅳ group. Astragaloside Ⅳ is able to inhibit inflammatory response and diminish the percentage of Th17 cells in mice with UC.
Animals ; Colitis, Ulcerative/metabolism* ; Mice ; Saponins/pharmacology* ; T-Lymphocytes, Regulatory ; Th17 Cells ; Triterpenes/pharmacology*

This study aims to investigate the regulatory effect of Sishen Pills(SSP) and its split prescriptions Ershen Pills(EP) and Wuweizi Powder(WP) on T follicular helper(Tfh) cell subset in the dextran sodium sulfate(DSS)-induced colitis mice and the mechanism. A total of 60 male SPF BALB/c mice were used, 10 of which were randomly selected as the normal group. The rest 50 were induced with 3% DSS solution for colitis modeling. After modeling, they were randomized into 5 groups: model group, SSP group, EP group, WP group, and mesalazine group. Body mass, colon mass, colon mass index, colon length, and unit colon mass index in each group were observed. After hematoxylin-eosin(HE) staining, the pathological injury of colon tissue was scored. The expression levels of molecules related to the STAT/SOCS signaling pathway in colon tissues were analyzed by Western blot. Differentiation levels of Tfh cells such as CD4~+CXCR5~+IL-9~+(Tfh9), CD4~+CXCR5~+IL-17~+(Tfh17), and CD4~+CXCR5~+Foxp3~+(Tfr) in peripheral blood of mice were detected by flow cytometry. The results showed each treatment group demonstrated significant increase in body mass and colon length, decrease in colon mass, colon mass index, unit colon mass index, and histopathological score(P<0.05, P<0.01), reduction of the expression of p-STAT3, STAT3, p-STAT6, and STAT6(P<0.05, P<0.01), rise of the expression of SOCS1 and SOCS3(P<0.05, P<0.01), decrease of Tfh9 and Tfh17 cells, and increase of Tfr cells(P<0.05, P<0.01) compared with the model group. These results indicated that SSP and the split EP and WP may alleviate ulcerative colitis by inhibiting the activation of STAT/SOCS signaling pathway and regulating the balance of Tfr/Tfh9/Tfh17 cells.
Animals ; Colitis/genetics* ; Colitis, Ulcerative/metabolism* ; Male ; Mice ; Mice, Inbred BALB C ; Prescriptions ; T-Lymphocytes, Regulatory

The notion that obesity-induced inflammation mediates the development of insulin resistance in animal models and humans has been gaining strong support. It has also been shown that immune cells in local tissues, in particular in visceral adipose tissue, play a major role in the regulation of obesity-induced inflammation. Specifically, obesity increases the numbers and activation of proinflammatory immune cells, including M1 macrophages, neutrophils, Th1 CD4 T cells, and CD8 T cells, while simultaneously suppressing anti-inflammatory cells such as M2 macrophages, CD4 regulatory T cells, regulatory B cells, and eosinophils. Recently, however, new cell types have been shown to participate in the development of obesity-induced inflammation and insulin resistance. Some of these cell types also appear to regulate obesity. These cells are natural killer (NK) cells and innate lymphoid cells (ILCs), which are closely related, and invariant natural killer T (iNKT) cells. It should be noted that, although iNKT cells resemble NK cells in name, they are actually a completely different cell type in terms of their development and functions in immunity and metabolism. In this review, we will focus on the roles that these relatively new players in the metabolism field play in obesity-induced insulin resistance and the regulation of obesity.
B-Lymphocytes, Regulatory ; Diabetes Mellitus, Type 2 ; Eosinophils ; Humans ; Inflammation* ; Insulin Resistance* ; Insulin* ; Intra-Abdominal Fat ; Killer Cells, Natural* ; Lymphocytes ; Macrophages ; Metabolism ; Models, Animal ; Natural Killer T-Cells* ; Neutrophils ; Obesity ; T-Lymphocytes ; T-Lymphocytes, Regulatory

CD4(+)CD25(+)CD127(dim/-) regulatory T cells (Tregs) have been implicated in suppressing T cell immune responses to hepatitis B virus (HBV), but the inhibition mechanism has not being clear yet. This study investigated the effects of soluble FGL2 (sFGL2) secreted by Tregs on immune suppression in chronic HBV-infected patients. We verified that sFGL2 protein and mRNA were highly expressed in Tregs. The separated Tregs by using magnetic beads from peripheral blood mononuclear cells (PBMCs) in 20 patients with chronic hepatitis B were co-cultured with PBMCs at a ratio of 1:3 with anti-CD3 stimulating antibody or FGL2 blocking antibody. The proliferation index of CD8(+)T cells after blocking FGL2 was higher than that in blank group (3.58±0.18 vs. 3.28±0.17, P=0.034) in 18 of 20 samples, and lower than that in CD3 stimulation group (3.82±0.19, P=0.026) in 16 of 20 samples. The IFN-γ secreted in the mixed culture in the absence of Tregs was higher than that in the culture in the presence of Tregs, but it could be abolished by FGL2 blocking antibody. These results suggest that sFGL2 protein secreted by Tregs suppresses the proliferation and function of CD8(+) T cells in chronic hepatitis B.
CD8-Positive T-Lymphocytes ; immunology ; metabolism ; Cells, Cultured ; Fibrinogen ; immunology ; metabolism ; Hepatitis B, Chronic ; immunology ; metabolism ; Humans ; T-Lymphocytes, Regulatory ; immunology ; metabolism

To explore the effectiveness and safety of a Chinese medicinal decoction Wuwei Xiaodu Drink (WWXDD) in inhibiting chronic osteomyelitis via regulatory T cells signaling. The effective constitutes of WWXDD and osteomyelitis related genes were screened. Target proteins were cross-validated using the Venny database. GO function and KEGG pathway analysis were performed for target proteins, while pharmacological network was constructed. The bone properties were analyzed by HE staining and the concentrations of immune factors were measured by ELISA. The expression of CTLA-4 and Foxp3 mRNA and STAT5, p-STAT5, CTLA-4 and Foxp3 protein were detected using Real-time PCR and Western blot, respectively. FACS was used to analyze the percentages of cells. A total of 117 genes overlapped between 785 target genes of the active compounds of WWXDD and 912 osteomyelitis related genes. Inflammation-related genes, including IL-6, TNFα, IL-1β and IL-2 showed high connection degree in the drug-compound-disease-target network. GO function and KEGG pathway analysis revealed that 117 intersection genes mainly enriched in virus infection related pathways, immune related pathways and chemokine signaling pathway. Furthermore, the development of chronic osteomyelitis was suppressed in model rats after treatment with WWXDD. Meanwhile, the concentrations of IL-2 and CD4⁺CD25⁺Foxp3 Treg percentages together with the levels of p-STAT5, CTLA-4 and Foxp3 were also down-regulated. Furthermore, IL-2 and WWXDD drug-containing serum exhibited opposite effects on regulating IL-2, IL-10, TGF-β1, Foxp3, CTLA4 and STAT5. In addition, a STAT5 phosphorylation inhibitor suppressed the expression of Foxp3 and CTLA-4. WWXDD can treat chronic osteomyelitis through suppressing the main regulating factors of Tregs and interfere its immunodepression. Our results bring a new solution for chronic osteomyelitis.
Animals ; Forkhead Transcription Factors/metabolism* ; Interleukin-2/metabolism* ; Osteomyelitis/metabolism* ; Rats ; STAT5 Transcription Factor/metabolism* ; Signal Transduction ; T-Lymphocytes, Regulatory

OBJECTIVE: To explore the effects of bone marrow mesenchymal stem cells (BMSCs) in different concentrations on the balance of regulatory T cell/T-helper cell 17 (Treg/Th17). METHODS: BMSCs were isolated from SPF grade male Wistar rats with age of 3 weeks old and weight of 50 g. BMSCs were cultured and identified when they were expanded to the 4th generation. CD4⁺ T lymphocytes were isolated from SPF grade male Wistar rat with age of 6 weeks old and weight of 200 g and assayed for cell purity by flow cytometry. BMSCs were divided into 0.5-fold concentration group, basal concentration group, 2-fold concentration group and 4-fold concentration group by their concentrations of 1×10⁵/well, 2×10⁵/well, 4×10⁵/well and 8×10⁵/well, which were cultured with CD4⁺ T lymphocytes for 72 hours, respectively. Then the proportion of Treg cells and Th17 cells in each group was detected by flow cytometry, and cytokines were detected by cytometric bead array. RESULTS: The purities of BMSCs and CD4⁺ T lymphocytes were both higher than 95%. In the co-culture of BMSCs and CD4⁺ T lymphocytes, the proportions of Treg cells were statistically different among different concentration groups of BMSCs (F = 10.071, P = 0.001), in which BMSCs in 2-fold concentration group had the strongest ability to promote the Treg cells proliferation. The proportion of Treg cells in 2-fold concentration group was significantly higher than that in 0.5-fold concentration group, basal concentration group and 4-fold concentration group [(9.24±2.68)% vs. (3.87±0.38)%, (5.16±1.69)%, (3.86±0.36)%, all P < 0.01]. The level of interleukin-10 (IL-10) was lowest in 0.5-fold concentration group, and it was significantly lower than that in basal concentration group, 2-fold concentration group and 4-fold concentration group (ng/L: 39.80±14.48 vs. 148.43±64.49, 156.40±59.27, 126.92±42.95, all P < 0.05). Transforming growth factor-β (TGF-β) was the highest in basal concentration group, and it was significantly higher than that in 0.5-fold concentration group, 2-fold concentration group and 4-fold concentration group [ng/L: 3.17 (1.88, 5.74) vs. 0.71 (0.32, 1.38), 1.22 (0.47, 2.97), 0.52 (0.37, 1.23), all P < 0.05]. The proportions of Th17 cells were statistically different among the different concentration groups (F = 21.069, P = 0.000), with the highest proportion in basal concentration group which was significantly higher than that in 0.5-fold concentration group or 4-fold concentration group [(0.89±0.08)% vs. (0.64±0.15)%, (0.37±0.10)%, both P < 0.01], but no significant difference was found as compared with 2-fold concentration group [(0.83±0.06)%, P > 0.05]. However, the expressions of IL-17 and IL-6 were not different among the different concentration groups respectively (IL-17: χ² = 0.550, P = 0.760; IL-6: χ² = 0.010, P = 0.995). CONCLUSIONS BMSCs in moderate concentrations [(2-4)×10⁵/well] could promote proliferation both in Treg cells and Th17 cells, but no change could be found in higher concentrations of BMSCs (8×10⁵/well). However, the changes in related cytokines were not synchronized with Treg/Th17 cells.
Animals ; Cytokines/metabolism* ; Male ; Mesenchymal Stem Cells/metabolism* ; Rats ; Rats, Wistar ; T-Lymphocytes, Regulatory/metabolism* ; Th17 Cells/metabolism*

OBJECTIVE: To investigate the effect of circulating exosomes (EXO) on T cell function in patients with sepsis. METHODS: Plasma EXO were obtained by ultracentrifugation from 10 patients with sepsis admitted to the emergency intensive care unit of Guangdong Provincial People's Hospital Affiliated to Southern Medical University. Transmission electron microscopy observation, nanoparticle tracking analysis (NTA), and Western blotting were used to detect EXO markers to identify their characteristics. Furthermore, peripheral blood mononuclear cells (PBMC) were isolated from the peripheral blood of 5 healthy volunteers, primary T cells were sorted by magnetic beads and expanded in vitro. After 24 hours of intervention with different doses (0, 1, 2.5, 5, 10 mg/L) of circulating EXO in patients with sepsis, T-cell activity was assessed using a cell counting kit-8 (CCK-8). The expression of T cell activation indicators CD69 and CD25 were observed using flow cytometry. Additional evaluations were performed on immunosuppressive indicators including the expression of programmed cell death 1 (PD-1) in CD4⁺ T cells and the proportion of regulatory T cell (Treg). RESULTS: The identification results confirmed that the successful isolation of EXO from the plasma of sepsis patients. The expression level of circulating EXO in sepsis patients was higher than that in healthy control group (mg/L: 48.78±5.14 vs. 22.18±2.25, P < 0.01). After 24 hours of intervention with 5 mg/L of plasma EXO from sepsis patients, T cells activity began to show suppression [(85.84±0.56)% vs. (100.00±0.00)%, P < 0.05]. As the dosage increased, after 24 hours of intervention with 10 mg/L of EXO, T cells activity was significantly suppressed [(72.44±2.36)% vs. (100.00±0.00)%, P < 0.01]. Compared with the healthy control group, after T cells intervention with plasma EXO from sepsis patients, the expression of early activation marker CD69 was significantly reduced [(52.87±1.29)% vs. (67.13±3.56)%, P < 0.05]. Meanwhile, there was an upregulation of PD-1 expression in T cells [(57.73±3.06)% vs. (32.07±0.22)%, P < 0.01] and an increase in the proportion of Treg [(54.67±1.19)% vs. (24.60±3.51)%, P < 0.01]. However, the expression of the late activation marker CD25 remained stable [(84.77±3.44)% vs. (85.93±2.32)%, P > 0.05]. CONCLUSIONS Circulating EXO in sepsis patients induce T cell dysfunction, which may be a novel mechanism lead to immunosuppression in sepsis.
Humans ; Leukocytes, Mononuclear ; Exosomes/metabolism* ; Programmed Cell Death 1 Receptor/metabolism* ; T-Lymphocytes, Regulatory/metabolism* ; Sepsis/metabolism*