Elevated circulating CD4+ ICOS+ Foxp3+ T cells contribute to overproduction of IL-10 and are correlated with disease severity in patients with systemic lupus erythematosus

In this work, we aimed to investigate the frequency, possible categories and clinical significance of circulating CD4+ ICOS+ FoxP3+ T cells in patients with systemic lupus erythematosus (SLE). The frequency of circulating CD4+ ICOS+ FoxP3+ T cells was analysed by flow-cytometric analysis in 32 SLE patients, 10 rheumatoid arthritis patients and 32 healthy controls. Production of IL-10 and mTGF-β by different CD4+ T-cell populations was determined by intracellular cytokine staining. Plasma levels of IL-10 and TGF-β were determined by enzyme-linked immunosorbent assay (ELISA). The frequency of circulating CD4+ ICOS+ FoxP3+ T cells was significantly increased in SLE patients as compared with control groups. The elevated frequency of CD4+ ICOS+ FoxP3+ T cells had a positive correlation with SLE Disease Activity Index (SLEDAI) scores and serum anti-dsDNA but a negative correlation with serum C3. Additionally, the CD4+ ICOS+ Foxp3+ T cells contained significantly higher percentages of IL-10-producing cells than CD4+ ICOS- Foxp3+ T cells. A significant positive correlation was also observed between the frequency of CD4+ ICOS+ Foxp3+ T cells and the plasma level of IL-10 in SLE patients. In conclusion, an increased frequency of circulating CD4+ ICOS+ Foxp3+ T cells was observed in patients with SLE, suggesting its potential importance in the immunopathogenesis of SLE. Analysis of the CD4+ ICOS+ FoxP3+ T-cell population may be useful for the evaluation of lupus disease severity.     

Expression and function of inducible costimulator on peripheral blood T cells in patients with systemic lupus erythematosus

OBJECTIVE: To investigate the role of inducible costimulator (ICOS) in the pathogenesis of SLE, we assessed its expression on peripheral blood CD4 and CD8 T cells and functional roles in patients with systemic lupus erythematosus (SLE). METHODS: Expression of ICOS on peripheral blood CD4 and CD8 T cells and ICOS ligand (ICOSL) on peripheral blood CD19 B cells from patients with SLE, patients with rheumatoid arthritis (RA) and healthy volunteers were determined by two-colour flow cytometry. The functional costimulatory effects of ICOS on peripheral blood mononuclear cells (PBMC) were assessed by T-cell proliferative responses, cytokines, anti-double-stranded DNA (anti-dsDNA) antibody and total IgG production. RESULTS: Peripheral blood CD4 and CD8 T cells expressing ICOS were significantly increased in patients with SLE compared with patients with RA and healthy subjects. Peripheral blood CD19 B cells expressing ICOSL in SLE were markedly reduced compared with RA. Proliferative responses of anti-CD3/ICOS costimulation were significantly higher than those of anti-CD3/hamster IgG (HIgG) in healthy subjects, but not in patients with SLE. Anti-CD3/ICOS-stimulated SLE PBMC secreted similar levels of IL-10 and IFN-gamma but a significantly lower level of IL-2 than healthy PBMC. Anti-CD3/ICOS-mediated costimulation significantly enhanced the production of anti-dsDNA antibodies and total IgG in patients with SLE. CONCLUSION: Hyperexpression of ICOS on peripheral blood CD4 and CD8 T cells from patients with SLE contributed to the dysregulated T-cell proliferation, T-cell activation and pathogenic autoantibody production, which showed that the abnormality of ICOS costimulation may play an immunopathological role(s) in the pathogenesis of SLE.     

Increased frequency of CD4(+)CD25(high) Treg cells inhibit BCG-specific induction of IFN-gamma by CD4(+) T cells from TB patients

Cell-mediated immunity plays a considerable role in the protection against Mycobacterium tuberculosis infection. The immune response to tuberculosis (TB) was dominated by both CD4(+) T cells with the T helper 1 type cytokines and CD8(+) T cells. Recent studies have suggested that the circumstances in which protective or tissue-damaging T cell responses to microbes are affected by the activity of Treg (CD4(+)CD25(high)) cells. In the present study, we demonstrated that the frequencies of CD4(+)CD25(+) and CD4(+)CD25(high) T cells in TB patients were significantly higher compared to normal individuals. These Treg cells expressed CTLA-4 and Foxp3 at protein level and displayed activation and memory phenotypes as assessed by flow cytometric analysis. The frequencies of CD4(+)CD25(high)CTLA-4(+) and CD4(+)CD25(high)Foxp3(+) T cells within the total CD4(+) T cell population were significantly increased in the blood of TB patients compared to healthy donors. Moreover, the expression of GITR on Treg cells was higher in TB patients than in normal donors. The phenotypic analysis demonstrated that CD4(+)CD25(high) Treg expressed higher levels of CD45RO and HLA-DR, and lower levels of CD45RA compared to CD4(+)CD25(low) and CD4(+)CD25(-) T cells. The addition of CD4(+)CD25(high) T cells back to cultures could significantly suppress the antigen-specific production of IFN-gamma induced by BCG-stimulated CD4(+)CD25(-) T cells, suggesting that Treg might play a key role in the control of cellular immune responses in TB infection.     

Decreased CD161+CD8+ T cells in the peripheral blood of patients suffering from rheumatic diseases

OBJECTIVES: Although it has been reported that the numbers of both CD4(-)CD8(-) and CD4(+) natural killer T (NKT) cells are selectively decreased in the peripheral blood of patients with rheumatic diseases, there have been no reports concerning a novel subpopulation of CD8(+) NKT cells. To examine whether CD161(+)CD8(+) T cells, which are closely related to CD8(+) NKT cells, are also decreased in patients with rheumatic diseases, we have investigated the expression of CD161, together with that of CD28, CD25 and CD62L, on T cells in the peripheral blood of these patients. METHODS: The rheumatic diseases evaluated in this study were systemic lupus erythematosus (SLE) (n= 54), mixed connective-tissue disease (MCTD) (n= 15), systemic sclerosis (SSc) (n= 14), polymyositis/dermatomyositis (PM/DM) (n= 13) and rheumatoid arthritis (RA) (n= 24). Healthy donors were examined as controls (n= 18). The expression of CD161, CD28, CD25 and CD62L on T cells was analysed by flow cytometry. RESULTS: Both the frequency of CD161 expression on CD8(+) cells and the absolute number of CD161(+)CD8(+) cells were significantly decreased in patients with SLE, MCTD, SSc and PM/DM. Only the absolute number of CD161(+)CD8(+) T cells was significantly decreased in RA. CD161 expression on CD28(-)CD8(+) T cells was significantly decreased in SLE, MCTD and SSc. The absolute number of CD161(+)CD8(+)CD62L(-) T cells was significantly decreased in SLE, MCTD and SSc. CONCLUSIONS: Both the frequency and the absolute number of CD161(+)CD8(+) T cells were decreased in the peripheral blood of patients suffering from SLE, MCTD, SSc and PM/DM. This result suggests that there is also an abnormality of NKT cells in the CD8(+) population.     

Expression of inducible co-stimulator on peripheral blood T lymphocytes in patients with lupus nephritis

Systemic lupus erythematosus (SLE) is a complex autoimmune disease and lupus nephritis (LN) represents a major clinical manifestation. Studies have shown that elevated inducible co-stimulator (ICOS) in SLE. The purpose of the study was to investigate the expression of ICOS on T cells in patients with LN. Flow cytometry (FCM) was used to analyze the expression of ICOS on peripheral blood T lymphocytes in LN patients, SLE patients without nephritis, and healthy controls. The expression of ICOS on CD4 + CD45RO + and CD8 + CD4RO + T cells was significantly increased in SLE patients when compared with healthy controls (P < 0.001). In addition, ICOS expression in patients with nephritis was higher than those without nephritis (P < 0.01). Taken together, our results suggest that ICOS co-stimulatory pathway is important in the pathogenesis of LN; blockade of the pathway might represent a novel therapeutic strategy for the treatment of LN.     

Interactions between NKT cells and Tregs are required for tolerance to combined bone marrow and organ transplants

We used a model of combined bone marrow and heart transplantation, in which tolerance and stable chimerism is induced after conditioning with fractionated irradiation of the lymphoid tissues and anti-T-cell antibodies. Graft acceptance and chimerism required host CD4(+)CD25(+) Treg production of IL-10 that was in-turn enhanced by host invariant natural killer (NK) T-cell production of IL-4. Up-regulation of PD-1 on host Tregs, CD4(+)CD25(-) conventional T (Tcon) cells, and CD8(+) T cells was also enhanced by NKT cell production of IL-4. Up-regulated PD-1 expression on Tregs was linked to IL-10 secretion, on CD8(+) T cells was linked to Tim-3 expression, and on CD4(+) Tcon cells was associated with reduced IFNγ secretion. Changes in the expression of PD-1 were induced by the conditioning regimen, and declined after bone marrow transplantation. In conclusion, NKT cells in this model promoted changes in expression of negative costimulatory receptors and anti-inflammatory cytokines by Tregs and other T-cell subsets in an IL-4-dependent manner that resulted in tolerance to the bone marrow and organ grafts.     

Intratumoral CD4+CD25+ regulatory T-cell-mediated suppression of infiltrating CD4+ T cells in B-cell non-Hodgkin lymphoma

Most non-Hodgkin lymphomas (NHLs) are of B-cell origin, but the tumor tissue can be variably infiltrated with T cells. In the present study, we have identified a subset of CD4(+)CD25(+) T cells with high levels of CTLA-4 and Foxp3 (intratumoral T(reg) cells) that are overrepresented in biopsy specimens of B-cell NHL (median of 17% in lymphoma biopsies, 12% in inflammatory tonsil, and 6% in tumor-free lymph nodes; P = .001). We found that these CD4(+)CD25(+) T cells suppressed the proliferation and cytokine (IFN-gamma and IL-4) production of infiltrating CD4(+)CD25(-) T cells in response to PHA stimulation. PD-1 was found to be constitutively and exclusively expressed on a subset of infiltrating CD4(+)CD25(-) T cells, and B7-H1 could be induced on intratumoral CD4(+)CD25(+) T cells in B-cell NHL. Anti-B7-H1 antibody or PD-1 fusion protein partly restored the proliferation of infiltrating CD4(+)CD25(-) T cells when cocultured with intratumoral T(reg) cells. Finally, we found that CCL22 secreted by lymphoma B cells is involved in the chemotaxis and migration of intratumoral T(reg) cells that express CCR4, but not CCR8. Taken together, our results suggest that T(reg) cells are highly represented in the area of B-cell NHL and that malignant B cells are involved in the recruitment of these cells into the area of lymphoma.     

Apoptosis-induced decrease of intrathyroidal CD4(+)CD25(+) regulatory T cells in autoimmune thyroid diseases.

BACKGROUND: We previously showed that the proportion of CD4(+) T cells was lower and both the proportion and intensity of Fas expression on intrathyroidal CD4(+) T cells were higher in the thyroid than in the peripheral blood of patients with autoimmune thyroid disease (AITD). OBJECTIVE: To clarify whether the intrathyroidal CD4(+)CD25(+) regulatory T (Treg) cells are decreased by Fas-mediated apoptosis in patients with AITD. DESIGN: We examined intrathyroidal and peripheral lymphocytes in 20 patients with AITD (15 patients with Gravesa disease and five patients with Hashimotoas disease) and peripheral lymphocytes in 10 healthy volunteers by three-color flow cytometry. MAIN OUTCOME: The proportion of CD4(+)CD25(+) cells was lower in the thyroid of patients with AITD than in the peripheral blood of the same patients or the peripheral blood of the healthy subjects. The proportions of CD4(+)CD25(+)CD69() cells and Forkhead box P3 (Foxp3)(+)CD4(+)CD25(+) cells, which constitute more specific Treg subsets than CD4(+)CD25(+) cells, were also lower in the thyroid than in the peripheral blood of patients with AITD. The proportion of apoptotic cells was higher among intrathyroidal CD4(+) cells than among peripheral CD4(+) cells and higher among intrathyroidal CD4(+)CD25(+) cells than among intrathyroidal CD4(+)CD25() cells. CONCLUSION: These results indicate that intrathyroidal Treg cells are decreased in response to apoptosis in patients with AITD. This decrease in Treg cells may contribute to the incomplete regulation of autoreactive T cells in AITD.     

Phenotypic Characteristics of PD-1 and CTLA-4 Expression in Symptomatic Acute Hepatitis A

Background/Aims

The immunoregulatory molecules programmed death 1 (PD-1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) are associated with the dysfunction of antiviral effector T-cells, which leads to T-cell exhaustion and persistent viral infection in patients with chronic hepatitis C and chronic hepatitis B. Little is known about the role of PD-1 and CTLA-4 in patients with symptomatic acute hepatitis A (AHA).

Methods

Peripheral blood mononuclear cells were isolated from seven patients with AHA and from six patients with nonviral acute toxic hepatitis (ATH) during the symptomatic and convalescent phases of the respective diseases; five healthy subjects acted as controls. The expression of PD-1 and CTLA-4 on T-cells was measured by flow cytometry.

Results

PD-1 and CTLA-4 expression during the symptomatic phase was significantly higher in the T-cells of AHA patients than in those of ATH patients or healthy controls (PD-1: 18.3% vs 3.7% vs 1.6%, respectively, p<0.05; CTLA-4: 23.5% vs 6.1% vs 5.9%, respectively, p<0.05). The levels of both molecules decreased dramatically during the convalescent phase of AHA, whereas a similar pattern was not seen in ATH.

Conclusions

Our findings are consistent with a viral-protective effect of PD-1 and CTLA-4 as inhibitory molecules that suppress cytotoxic T-cells and thereby prevent the destruction of virus-infected hepatocytes in AHA.     

The CD28 family: a T-cell rheostat for therapeutic control of T-cell activation

The CD28 family of receptors (CD28, cytotoxic T-lymphocyte-associated antigen 4 [CTLA-4], inducible costimulator [ICOS], program death-1 [PD-1], and B- and T-lymphocyte attenuator [BTLA]) plays a critical role in controlling the adaptive arm of the immune response. While considerable information is available regarding CD28 and CTLA-4, the function of the more recently discovered members of the CD28 family is less well understood. This review will highlight recent findings regarding the CD28 family with special emphasis on effects the CD28 family has on immunopathology, the discovery of costimulatory antibodies with superagonist function, and the status of clinical trials using various strategies to augment or block T-cell costimulation.     

Natural killer T cells in families of patients with systemic lupus erythematosus: their possible role in regulation of IGG production

OBJECTIVE: To determine whether there is a link between the frequency of natural killer T (NKT) cells and high levels of IgG in patients with systemic lupus erythematosus (SLE) and their relatives. METHODS: Blood samples were obtained from patients with SLE, their first-degree relatives, patients with rheumatoid arthritis (RA), and healthy control subjects. The frequency of NKT cells (defined as CD56+ T cells) was expressed as a percentage of total blood lymphocytes. Plasma levels of total IgG and IgM, and IgG antibodies to double-stranded DNA (dsDNA) were determined. RESULTS: The frequency of NKT cells was lower in patients with SLE than in control subjects. No such decrease was observed in the relatives of patients with SLE or in patients with RA. High levels of IgG were observed in both patients with SLE and their relatives, while low levels of IgM were observed in these same groups. In relatives of patients with SLE, an inverse correlation between the frequency of NKT cells and IgG levels was observed. Moreover, raised levels of IgG in patients with SLE and their relatives and high levels of IgG anti-dsDNA in patients were associated with low frequencies of NKT cells. CONCLUSION: These results suggest that NKT cells have an important role in the regulation of IgG production, although NKT cells with invariant T cell receptors may not necessarily be involved. NKT cells in the setting of SLE could lack the cytokine stimulus from NK or other cells that is needed to exert control on IgG production. Enhancement of NKT cell activity may provide a novel basis for therapy in SLE.     

CD4+ PD-1+ T cells accumulate as unique anergic cells in rheumatoid arthritis synovial fluid

OBJECTIVE: The PD-1 receptor, whose deficiency in mice causes autoimmune diseases such as arthritis, is considered to be a negative regulator of activated T cells and to play a crucial role in peripheral tolerance. To clarify the involvement of the PD-1 system in rheumatoid arthritis (RA), we investigated PD-1 expression on synovial fluid (SF) T cells from patients with RA. METHODS: FACS analysis for PD-1 was performed on SF T cells from 44 patients with RA and 6 with osteoarthritis (OA), and also on peripheral blood (PB) T cells from 12 RA patients and 7 healthy controls. Two-color analysis of cell surface PD-1 expression and the intracellular concentration of cytokine production was used to investigate CD4+ T cells from SF of patients with RA and PB from controls. RESULTS: Scarcely any PD-1 expression was detected on control PB T or OA SF T cells. In contrast, PD-1+ cells made up 20.9 +/- 8.6% (mean +/- SD) of RA SF T cells. In RA SF, PD-1 was expressed more predominantly on CD4+ T cells than on CD8+ T cells. As well as expressing CD45RO and CXCR3, CD4+ PD-1+ T cells were mostly CTLA-4 positive and CD26 negative, and were enriched in CD45RB(low) cells. Intracellular cytokine staining revealed that CD4+ PD-1+, but not CD4+ PD-1-, T cells produced interleukin 10 (IL-10), and that CD4+ PD-1+ T cells produced less IL-2 than CD4+ PD-1- T cells. CONCLUSION: PD-1+ T cells in RA SF are enriched, and phenotypic analysis suggests that these cells constitute a unique anergic T cell subset in RA SF.     

滤泡性辅助性T细胞与HCV感染的相关性

目的检测慢性HCV感染者外周血CD4＋T细胞中滤泡性辅助性T细胞（Tfh）所占比例,ICOS及负性调控因子PD-1、Tim-3在Tfh细胞上的表达。方法以31例HCV感染者、9例HCV感染自愈者（SR-HCV患者）及12例健康志愿者作为研究对象,应用流式细胞术分析外周血中CD4＋CXCR5＋Tfh细胞在CD4＋T细胞中所占比率,同时检测其ICOS、PD-1及Tim-3分子表达,通过酶联免疫吸附法测定血浆中白细胞介素（IL）21及HCV抗体水平,实时定量PCR检测HCV RNA滴度;多组数据比较采用单因素方差分析,双变量之间相关性采用Spearman秩相关分析。结果与健康对照组相比,HCV感染者及自愈者外周血CD4＋T细胞比率升高（P〈0.05）;HCV感染者CD4＋CXCR5＋Tfh细胞比率高于自愈及健康对照（P〈0.05）;HCV感染及自愈者CD4＋CX-CR5＋Tfh细胞ICOS、PD-1、Tim-3显著高于健康对照（P〈0.05）;血清IL-21水平HCV感染者与健康对照无统计学差异（P〉0.05）;HCV感染者HCV RNA载量与Tfh细胞比例呈负相关。结论 CD4＋CXCR5＋Tfh可能参与了抗HCV感染免疫应答。     

T lymphocyte subsets and PD-1 expression on lymphocytes in peripheral blood of patients with non-small cell lung cancer

The incidence rate and mortality rate of lung cancer (LC) are very high. This study aimed to analyze the T lymphocyte subsets and programmed death-1 (PD-1) expression on lymphocytes in the peripheral blood of non-small cell lung cancer (NSCLC) patients and explore whether there were changes in cellular immunity in NSCLC. Peripheral blood samples were collected from newly diagnosed NSCLC patients and healthy individuals. The T lymphocyte subsets and PD-1 expression were evaluated using flow cytometry. Single-sample gene set enrichment analysis (ssGSEA) was performed to explore the correlations of PD-1 expression with infiltration patterns for tumor-infiltrating T immune cells. By flow cytometry, two populations of lymphocytes in NSCLC patients were observed. Apart from a population of normal volume lymphocytes (Lym1), the other population had larger volume and more particles (Lym2). Compared with the healthy group, the proportion of CD4+ T cells and PD-1 expression on Lym1 was higher, and that of CD8+ T cells was lower in the NSCLC group. In the NSCLC group, the proportions of CD3+ T cells, CD8+ T cells, CD4+CD8+ T (DPT) cells, and PD-1 expression were higher on Lym2 than those on Lym1 (P < .05). ssGSEA showed that tumor infiltrating immune T cells were positively correlated with PD-1 expression. The PD-1 expression on lymphocytes increased in recurrent patients who treated with PD-1 inhibitor. Lym2 may be tumor-infiltrating lymphocytes (TILs) which upregulated PD-1 expression in NSCLC. PD-1 expression on lymphocytes may be used as a recurrence indicator for NSCLC patients treated with PD-1 inhibitors.     

Age-associated up-regulation of a negative co-stimulatory receptor PD-1 in mouse CD4 T cells

To explore whether any co-stimulatory receptor(s) for TCR signaling is involved in the age-associated decline in T-cell function, we analyzed changes in these receptors in freshly isolated mouse CD4⁺ T cells during aging. Both the mRNA and protein expression levels of CTLA-4 and PD-1, negative co-stimulatory receptors, increase with aging. No such changes are observed for CD28, a positive regulatory receptor. PD-1 is highly expressed on the surface of old, but not young, mouse T cells, while the level of surface-expressed CTLA-4 is very low regardless of age. PD-1 is preferentially expressed on the surface of effector-memory (CD44^hiCD62L^lo) T cells, a subset that increases with aging. CD4⁺PD-1⁺ T cells from old mice exhibit proliferative hyporesponsiveness. These results suggest that the up-regulation of surface-expressed PD-1 may cause the age-dependent functional decline in effector-memory T cells.     

B7-H1 expression is associated with expansion of regulatory T cells in colorectal carcinoma

AIM: To investigate the expression of B7-H1 in human colorectal carcinoma (CRC) to define its regulating effects on T cells in tumor microenvironment.METHODS: One hundred and two paraffin blocks and 33 fresh samples of CRC tissues were subject to this study. Immunohistochemistry was performed for B7-H1 and CD3 staining in CRC tissues. Ficoll-Hypaque density gradient centrifugation was used to isolate peripheral blood mononuclear cells of fresh CRC tissues; flow cytometry and immunofluorescence staining were used for detection of regulatory T cells. Data was analyzed with statistical software.RESULTS: Costimulatory molecule B7-H1 was found strongly expressed in CRC tissues, localized in tumor cell membrane and cytoplasm, while weak or none expression of B7-H1 was detected in pared normal colorectal tissues. Meanwhile, CD3 positive T cells were found congregated in CRC tumor nest and stroma. Statistic analysis showed that B7-H1 expression level was negatively correlated to the total T cell density in tumor nest (P < 0.0001) and tumor stroma (P = 0.0200) of 102 cases of CRC tissues. Among the total T cells, a variable amount of regulatory T cells with a clear Foxp3⁺ (forkhead box P3) staining could be detected in CRC tissues and patients’ blood. Interestingly, in the 33 samples (15 cases of B7-H1^high CRC tissues and 18 cases of B7-H1^low CRC tissues) of freshly isolated mononuclear cells from CRC tissues, the percentages of CD4⁺Foxp3⁺ and CD8⁺Foxp3⁺ regulatory T cells were found remarkably higher in B7-H1^high CRC tissues than in B7-H1^low CRC tissues (P = 0.0024, P = 0.0182), indicating that B7-H1 expression was involved in proliferation of regulatory T cell. No significant difference was found in CRC peripheral blood (P = 0.0863, P = 0.0678). PD-1 is the specific ligand for B7-H1 pathway transferring inhibitory signal to T cell, which is expressed by activated T cell. Our further analysis of PD-1 expression on T cells in CRC tissues showed that conventional T cells (CD4⁺Foxp3^-/CD8⁺Foxp3^-), which was thought to contribute to the anti-tumor immune response, highly expressed PD-1; while regulatory T cells (CD4⁺Foxp3⁺/CD8⁺Foxp3^-) almost failed to express PD-1. The average percentage of PD-1 expression on regulatory T cells was significantly higher than the percentage of PD-1 on conventional T cells (CD4⁺Foxp3^- T cell, P < 0.0001; CD8⁺Foxp3^- T cell, P < 0.0001). The diverse expression of PD-1 might lead to different fate of T cell subsets in B7-H1 over-expression CRC tumor microenvironment.CONCLUSION: B7-H1 expression in tumor cells can inhibit the conventional T cell proliferation in tumor microenvironment through the PD-1 expression on conventional T cells.     

Ribavirin downmodulates inducible costimulator on CD4+ T cells and their interleukin-10 secretion to assist in hepatitis C virus clearance

Background and Aim: The immunological mechanism by which ribavirin (RBV) polarizes the T‐helper (Th) 1/2 balance toward Th1 predominancy is not fully understood. We therefore examined whether RBV affects costimulatory signaling, which is known to be essential for regulating the Th1/2 balance. Methods: The expression of costimulatory molecules and their ligands, and levels of various cytokines, released from CD4⁺ T cells obtained from healthy individuals or patients with chronic hepatitis C virus (HCV) infection were analyzed. Results: In CD4⁺ T cells, RBV selectively downmodulates the expression of inducible costimulator (ICOS), a ligand for B7–H2 on dendritic cells, which mainly differentiates Th0 into Th2 cells. Moreover, the levels of interleukin‐10 (IL‐10) released from RBV‐stimulated CD4⁺ T cells also decreased, indicating that the downmodulation of ICOS induced by RBV might be correlated with the decrease in IL‐10 released from Th cells, leading to the inhibition of Th2 activity. An analysis of the association between ICOS kinetics and hepatitis C virus (HCV) elimination in hepatitis C patients receiving combined pegylated interferon and RBV indicated that HCV elimination tended to occur more frequently in patients showing ICOS downmodulation with RBV treatment. A decrease in IL‐10 production by CD4⁺ T cells was also observed in association with ICOS downregulation in patients who succeeded in HCV elimination. Conclusions: The downmodulation of ICOS in correlation with a reduction in IL‐10 produced by CD4⁺ T cells is possibly the immunological mechanism of action of RBV, which polarizes the Th1/2 balance toward a Th1 cytokine profile, thus contributing to the elimination of cells chronically infected with HCV.     

Associations of circulating CXCR3–PD-1+CD4+T cells with disease activity of systemic lupus erythematosus

Abstract

Objectives: Which helper CD4⁺ T cell subset contributes to autoantibodies generation and severity of end-organ involvement in lupus patients remains to be explored. Our research aims to investigate the roles of circulating Tfh (cTfh) cell subsets and corresponding CXCR5^– Th cells in lupus patients and their correlation with SLE disease activity index 2000 (SLEDAI).

Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from blood of systemic lupus erythematosus (SLE) patients as well as healthy donors. The proportion of Th cell subsets classified from cell surface markers (CD45RO, CXCR5, CXCR3, CCR6, PD-1, ICOS, and CCR7) is detected by flow cytometry.

Results: We found no difference in the frequency of CD45RO⁺CXCR5⁺CD4⁺ T cells between SLE patients and health controls. As previously reported, SLE patients showed an increase in the percentage of CXCR5⁺PD-1⁺, CXCR5⁺ICOS⁺PD-1⁺ and CXCR5⁺CCR7^loPD-1^hi cTfh subset, however, none of these populations had correlation with SLEDAI. Therefore, we further investigated the CXCR5^– subsets, and surprisingly we found that the frequency of CXCR3^–PD-1⁺ subset was correlated with SLEDAI, ds-DNA IgG, anti-nucleosome antibody, C3, and C4 independent of CXCR5. Consistently, CXCR3^–PD-1⁺CD45RO⁺CD4⁺T cells expressed factors associated with B-cell-help for the autoantibody production.

Conclusion: CXCR3^–PD-1⁺CD4⁺T cells are a sensitive indicator to assess SLE disease activity and might contribute B cell help and the generation of autoantibodies in patients.