Functional Improvement of Regulatory T Cells from Rheumatoid Arthritis Subjects Induced by Capsular Polysaccharide Glucuronoxylomannogalactan

Objective

Regulatory T cells (Treg) play a critical role in the prevention of autoimmunity, and the suppressive activity of these cells is impaired in rheumatoid arthritis (RA). The aim of the present study was to investigate function and properties of Treg of RA patients in response to purified polysaccharide glucuronoxylomannogalactan (GXMGal).

Methods

Flow cytometry and western blot analysis were used to investigate the frequency, function and properties of Treg cells.

Results

GXMGal was able to: i) induce strong increase of FOXP3 on CD4⁺ T cells without affecting the number of CD4⁺CD25⁺FOXP3⁺ Treg cells with parallel increase in the percentage of non-conventional CD4⁺CD25⁻FOXP3⁺ Treg cells; ii) increase intracellular levels of TGF-β1 in CD4⁺CD25⁻FOXP3⁺ Treg cells and of IL-10 in both CD4⁺CD25⁺FOXP3⁺ and CD4⁺CD25⁻FOXP3⁺ Treg cells; iii) enhance the suppressive activity of CD4⁺CD25⁺FOXP3⁺ and CD4⁺CD25⁻FOXP3⁺ Treg cells in terms of inhibition of effector T cell activity and increased secretion of IL-10; iv) decrease Th1 response as demonstrated by inhibition of T-bet activation and down-regulation of IFN-γ and IL-12p70 production; v) decrease Th17 differentiation by down-regulating pSTAT3 activation and IL-17A, IL-23, IL-21, IL-22 and IL-6 production.

Conclusion

These data show that GXMGal improves Treg functions and increases the number and function of CD4⁺CD25⁻FOXP3⁺ Treg cells of RA patients. It is suggested that GXMGal may be potentially useful for restoring impaired Treg functions in autoimmune disorders and for developing Treg cell-based strategies for the treatment of these diseases.     

Loss of Function of Intestinal IL-17 and IL-22 Producing Cells Contributes to Inflammation and Viral Persistence in SIV-Infected Rhesus Macaques

In HIV/SIV-infected humans and rhesus macaques (RMs), a severe depletion of intestinal CD4⁺ T-cells producing interleukin IL-17 and IL-22 associates with loss of mucosal integrity and chronic immune activation. However, little is known about the function of IL-17 and IL-22 producing cells during lentiviral infections. Here, we longitudinally determined the levels and functions of IL-17, IL-22 and IL-17/IL-22 producing CD4⁺ T-cells in blood, lymph node and colorectum of SIV-infected RMs, as well as how they recover during effective ART and are affected by ART interruption. Intestinal IL-17 and IL-22 producing CD4⁺ T-cells are polyfunctional in SIV-uninfected RMs, with the large majority of cells producing four or five cytokines. SIV infection induced a severe dysfunction of colorectal IL-17, IL-22 and IL-17/IL-22 producing CD4⁺ T-cells, the extent of which associated with the levels of immune activation (HLA-DR⁺CD38⁺), proliferation (Ki-67⁺) and CD4⁺ T-cell counts before and during ART. Additionally, Th17 cell function during ART negatively correlated with residual plasma viremia and levels of sCD163, a soluble marker of inflammation and disease progression. Furthermore, IL-17 and IL-22 producing cell frequency and function at various pre, on, and off-ART experimental points associated with and predicted total SIV-DNA content in the colorectum and blood. While ART restored Th22 cell function to levels similar to pre-infection, it did not fully restore Th17 cell function, and all cell types were rapidly and severely affected—both quantitatively and qualitatively—after ART interruption. In conclusion, intestinal IL-17 producing cell function is severely impaired by SIV infection, not fully normalized despite effective ART, and strongly associates with inflammation as well as SIV persistence off and on ART. As such, strategies able to preserve and/or regenerate the functions of these CD4⁺ T-cells central for mucosal immunity are critically needed in future HIV cure research.     

Decreases in Colonic and Systemic Inflammation in Chronic HIV Infection after IL-7 Administration

Despite antiretroviral therapy (ART), some HIV-infected persons maintain lower than normal CD4⁺ T-cell counts in peripheral blood and in the gut mucosa. This incomplete immune restoration is associated with higher levels of immune activation manifested by high systemic levels of biomarkers, including sCD14 and D-dimer, that are independent predictors of morbidity and mortality in HIV infection. In this 12-week, single-arm, open-label study, we tested the efficacy of IL-7 adjunctive therapy on T-cell reconstitution in peripheral blood and gut mucosa in 23 ART suppressed HIV-infected patients with incomplete CD4⁺ T-cell recovery, using one cycle (consisting of three subcutaneous injections) of recombinant human IL-7 (r-hIL-7) at 20 µg/kg. IL-7 administration led to increases of both CD4⁺ and CD8⁺ T-cells in peripheral blood, and importantly an expansion of T-cells expressing the gut homing integrin α4β7. Participants who underwent rectosigmoid biopsies at study baseline and after treatment had T-cell increases in the gut mucosa measured by both flow cytometry and immunohistochemistry. IL-7 therapy also resulted in apparent improvement in gut barrier integrity as measured by decreased neutrophil infiltration in the rectosigmoid lamina propria 12 weeks after IL-7 administration. This was also accompanied by decreased TNF and increased FOXP3 expression in the lamina propria. Plasma levels of sCD14 and D-dimer, indicative of systemic inflammation, decreased after r-hIL-7. Increases of colonic mucosal T-cells correlated strongly with the decreased systemic levels of sCD14, the LPS coreceptor - a marker of monocyte activation. Furthermore, the proportion of inflammatory monocytes expressing CCR2 was decreased, as was the basal IL-1β production of peripheral blood monocytes. These data suggest that administration of r-hIL-7 improves the gut mucosal abnormalities of chronic HIV infection and attenuates the systemic inflammatory and coagulation abnormalities that have been linked to it.     

The Ratio of Treg/Th17 Cells Correlates with the Disease Activity of Primary Immune Thrombocytopenia

Background

Primary immune thrombocytopenia (ITP) is an autoimmune heterogeneous disorder that is characterized by decreased platelet count. Regulatory T (Treg) cells and T helper type 17 (Th17) cells are two subtypes of CD4⁺ T helper (Th) cells. They play opposite roles in immune tolerance and autoimmune diseases, while they share a common differentiation pathway. The imbalance of Treg/Th17 has been demonstrated in several autoimmune diseases. In this study, we aimed to investigate the ratio of the number of Treg cells to the number of Th17 cells in ITP patients and evaluate the clinical implications of the alterations in this ratio.

Methods

Thirty adult patients with newly diagnosed ITP enrolled in this study. Twelve patients had been clinically followed up for 12 months. The percentages of CD4⁺CD25^hiFoxp3⁺ Treg cells and CD3⁺CD4⁺IL-17-producing Th17 cells in these patients and healthy controls (n = 17) were longitudinally analyzed by flow cytometry.

Results

The percentage of Treg cells in ITP patients was significantly lower than that of healthy controls, and the percentage of Th17 cells increased significantly at disease onset. The ratio of Treg/Th17 correlated with the disease activity.

Conclusion

The ratio of Treg/Th17 might be relevant to the clinical diversity of ITP patients, and this Treg/Th17 ratio might have prognostic role in ITP patients.     

Elevated Levels of CD4+CD25+FoxP3+ T Cells in Systemic Sclerosis Patients Contribute to the Secretion of IL-17 and Immunosuppression Dysfunction

Objective

Immune imbalance between regulatory T (Treg) and Th17 cells is a characteristic of systemic sclerosis (SSc). The functional heterogeneity among Treg can be elucidated by separating Treg into different subsets based on the expression of FoxP3 and CD45RA. The aim of this study was to investigate the role of Treg subsets in the immune imbalance in naïve SSc.

Methods

Peripheral blood mononuclear cells (PBMCs) of 31 SSc patients and 33 healthy controls were analyzed for the expression of CD4, CD25, CD45RA, CTLA-4, FoxP3, and IL-17 using flow cytometry. Treg immunesuppression capacity was measured in co-culture experiments. The expression of FoxP3, CTLA-4, IL-17A, and RORC mRNA was measured by real-time PCR.

Results

The frequency of CD4⁺CD25⁺FoxP3⁺ Treg cells was significantly elevated in patients with SSc (3.62±1.14 vs 1.97±0.75, p<0.001) with diminished immunosuppression capacity. In SSc, the proportion of FoxP3^highCD45RA⁻ activated Treg cells (aTreg) was decreased, the proportion of FoxP3^lowCD45RA⁻ T cells was increased, and the proportion of FoxP3^lowCD45RA⁺ resting Treg cells (rTreg) was decreased. The immune suppression capacity of aTreg and rTreg was diminished, while FoxP3^lowCD45RA⁻ T cells exhibited a lack of suppression capacity. The immune dysfunction of aTreg was accompanied by the abnormal expression of CTLA-4. Th17 cell numbers were elevated in SSc, FoxP3^lowCD45RA⁻ T cells produced IL-17, confirming their Th17 potential, which was consistent with the elevated levels of FoxP3⁺IL-17⁺ cells in SSc.

Conclusion

A decrease in aTreg levels, along with functional deficiency, and an increase in the proportion of FoxP3^lowCD45RA⁻ T cells, was the reason for the increase in dysfunctional Treg in SSc patients, potentially causing the immune imbalance between Treg and Th17 cells.     

肺炎支原体肺炎伴喘息儿童血清25(OH)D_3、Th17/Treg表达水平与肺功能的关系

目的:探讨肺炎支原体肺炎伴喘息儿童血清25羟基维生素D3[25(OH)D_3]、辅助性17细胞/调节性T细胞(Th17/Treg)表达水平与肺功能的关系。方法:将新疆医科大学第五附属医院收治的肺炎支原体肺炎伴喘息患儿26例作为肺炎伴喘息组,肺炎支原体肺炎不伴有喘息患儿54例作为肺炎不伴喘息组,另选取健康儿童30例作为对照组,比较各组血清25(OH)D_3、白细胞介素(IL)-10、IL-17、Th17细胞及Treg细胞占CD4+T细胞比例及肺功能,并分析其相关性。结果:肺炎伴喘息组血清25(OH)D_3、IL-10、Treg细胞占CD4+T细胞比例低于肺炎不伴喘息组、对照组,Th17细胞占CD4+T细胞比例、Th17/Treg、IL-17高于肺炎不伴喘息组、对照组(P0.05)。各组第一秒最大呼气量占用力肺活量百分比(FEV1/FVC)比较差异无统计学意义(P0.05),肺炎伴喘息组FEV1占预计值百分比(FEV1%pred)、峰值呼气流量(PEF)低于肺炎不伴喘息组、对照组(P0.05),肺炎不伴喘息组与对照组FEV1%pred、PEF比较无统计学意义(P0.05)。肺炎伴喘息组患儿血清25 (OH)D_3与Th17/Treg、IL-17呈负相关(P0.05),与IL-10、FEV1%pred、PEF呈正相关(P0.05),血清Th17/Treg与IL-10、FEV1%pred、PEF呈负相关(P0.05),与IL-17呈正相关(P0.05)。结论:肺炎支原体肺炎伴喘息儿童血清25(OH)D_3、Th17/Treg表达水平异常,肺功能下降,且25(OH)D_3、Th17/Treg表达水平与肺功能相关。     

Decreased expression of microRNA‐21 correlates with the imbalance of Th17 and Treg cells in patients with rheumatoid arthritis

The imbalance of Th17/Treg cell populations has been suggested to be involved in the regulation of rheumatoid arthritis (RA) pathogenesis; however, the mechanism behind this phenomenon remains unclear. Recent studies have shown how microRNAs (miRNAs) are important regulators of immune responses and are involved in the development of a variety of inflammatory diseases, including RA. In this study, we demonstrated that the frequencies of CD3⁺CD4⁺IL‐17⁺Th17 cells were significantly higher, and CD4⁺CD25⁺FOXP3⁺ Treg cells significantly lower in peripheral blood mononuclear cells from RA patients. Detection of cytokines from RA patients revealed an elevated panel of pro‐inflammatory cytokines, including IL‐17, IL‐6, IL‐1β, TNF‐α and IL‐22, which carry the inflammatory signature of RA and are crucial in the differentiation and maintenance of pathogenic Th17 cells and dysfunction of Treg cells. However, the level of miR‐21 was significantly lower in RA patients, accompanied by the increase in STAT3 expression and activation, and decrease in STAT5/pSTAT5 protein and Foxp3 mRNA levels. Furthermore, lipopolysaccharide stimulation up‐regulated miR‐21 expression from healthy controls, but down‐regulated miR‐21 expression from RA patients. Therefore, we speculate that miR‐21 may be part of a negative feedback loop in the normal setting. However, miR‐21 levels decrease significantly in RA patients, suggesting that this feedback loop is dysregulated and may contribute to the imbalance of Th17 and Treg cells. MiR‐21 may thus serve as a novel regulator in T‐cell differentiation and homoeostasis, and provides a new therapeutic target for the treatment of RA.     

Early Gag Immunodominance of the HIV-Specific T-Cell Response during Acute/Early Infection Is Associated with Higher CD8+ T-Cell Antiviral Activity and Correlates with Preservation of the CD4+ T-Cell Compartment

The important role of the CD8⁺ T-cell response on HIV control is well established. Moreover, the acute phase of infection represents a proper scenario to delineate the antiviral cellular functions that best correlate with control. Here, multiple functional aspects (specificity, ex vivo viral inhibitory activity [VIA] and polyfunctionality) of the HIV-specific CD8⁺ T-cell subset arising early after infection, and their association with disease progression markers, were examined. Blood samples from 44 subjects recruited within 6 months from infection (primary HIV infection [PHI] group), 16 chronically infected subjects, 11 elite controllers (EC), and 10 healthy donors were obtained. Results indicated that, although Nef dominated the anti-HIV response during acute/early infection, a higher proportion of early anti-Gag T cells correlated with delayed progression. Polyfunctional HIV-specific CD8⁺ T cells were detected at early time points but did not associate with virus control. Conversely, higher CD4⁺ T-cell set points were observed in PHI subjects with higher HIV-specific CD8⁺ T-cell VIA at baseline. Importantly, VIA levels correlated with the magnitude of the anti-Gag cellular response. The advantage of Gag-specific cells may result from their enhanced ability to mediate lysis of infected cells (evidenced by a higher capacity to degranulate and to mediate VIA) and to simultaneously produce IFN-γ. Finally, Gag immunodominance was associated with elevated plasma levels of interleukin 2 (IL-2) and macrophage inflammatory protein 1β (MIP-1β). All together, this study underscores the importance of CD8⁺ T-cell specificity in the improved control of disease progression, which was related to the capacity of Gag-specific cells to mediate both lytic and nonlytic antiviral mechanisms at early time points postinfection.     

Imbalanced Frequencies of Th17 and Treg Cells in Acute Coronary Syndromes Are Mediated by IL-6-STAT3 Signaling

Aims

Extensive evidence suggests inflammatory components participate in the pathogenic processes of acute coronary syndromes (ACS). In this study, we aimed to elucidate the role and mechanism underlying the imbalance of Th17 and Treg cell peripheral populations in the pathogenesis of ACS.

Methods and Results

Using a flow cytometric analysis, we observed a significantly increased frequency of Th17 cells and a concurrently decreased CD4⁺CD25⁺Foxp3⁺ Treg cells in patients with ACS. To elucidate the mechanism of Th17/Treg imbalance in ACS, 22 inflammatory cytokines were measured using multiplexed immunobead-based assays. Of six elevated cytokines in ACS patients, only IL-6 was positively correlated with a higher Th17 cell level (r = 0.39, P<0.01). Relying on IL-6 stimulating and neutralizing studies, we demonstrated a direct role for IL-6 in sera from ACS patients with an increased frequency of Th17 cells. IL-6 induces the differentiation of Th17 cells from naïve CD4⁺ T cells through STAT3 activation and RORγt induction. However, we observed that high levels of TGF-β1 inhibited IL-6-dependent Th17 cell differentiation, indicating a complex interplay between the two cytokines in the control of Th17 and Treg cell populations.

Conclusions

Our results demonstrate the role of IL-6-STAT3 signaling in ACS through increased Th17 cell differentiation. These findings indicate that IL-6 neutralizing strategies could present novel therapeutic avenues in the treatment of ACS.     

CD26 Expression on T Helper Populations and sCD26 Serum Levels in Patients with Rheumatoid Arthritis

We studied dipeptidyl peptidase IV (DPP-IV, CD26) expression in different T helper cells and serum soluble DPP-IV/sCD26 levels in rheumatoid arthritis (RA) patients, correlated these with disease activity score (DAS), and examined how they were affected by different therapies, conventional or biological (anti-TNF, anti-CD20 and anti-IL6R or Ig-CTLA4). The percentage of CD4⁺CD45R0⁺CD26^- cells was greatly reduced in patients (up to 50%) when compared with healthy subjects. Three other subsets of CD4 cells, including a CD26high Th1-associated population, changed variably with therapies. Data from these subsets (frequency and staining density) significantly correlated with DAS28 or DAS28 components but different in each group of patients undergoing the different therapies. Th17 and Th22 subsets were implicated in RA as independent CCR4⁺ and CCR4^- populations each, with distinct CD26 expression, and were targeted with varying efficiency by each therapy. Serum DPP-IV activity rather than sCD26 levels was lower in RA patients compared to healthy donors. DPP-IV and sCD26 serum levels were found related to specific T cell subsets but not to disease activity. We conclude that, according to their CD26 expression, different cell subsets could serve to monitor RA course, and an uncharacterized T helper CD26^- subset, not targeted by therapies, should be monitored for early diagnosis.     

Relationship between FOXP3 positive populations and cytokine production in systemic lupus erythematosus

In this work we studied CD4⁺FOXP3⁺ populations in systemic lupus erythematosus (SLE) and the relationship with Th cytokine production. We found an increment in CD25^?FOXP3⁺ population in SLE associated with CD4⁺ downregulation and disease progression. CD25^low cells were also upregulated and showed increased percentages of FOXP3⁺ and CD127^?/low cells, supporting the activated status of SLE lymphocytes. Despite the normal levels of CD25^highFOXP3⁺ cells, the negative correlations observed in controls with the frequency of IFNγ, TNFα and IL-10 secreting cells were disrupted in patients, supporting a defective Treg function. Also, CD25^high cells showed an altered balance in the production of these cytokines. In addition, CD25^highFOXP3⁺ cells correlated directly with IL-17A and IL-8 but not with TGFβ in SLE. The increased proportion of IL-17⁺ cells among the CD25^high subset and the positive correlation between IL-17 levels and Treg cells suggest a trans-differentiation of Treg into Th17 cells in SLE.     

CXCR3 antagonist AMG487 suppresses rheumatoid arthritis pathogenesis and progression by shifting the Th17/Treg cell balance

Rheumatoid arthritis (RA) is an autoimmune disease that is characterized by uncontrolled joint inflammation and damage to bone and cartilage. Previous studies have shown that chemokine receptors have important roles in RA development, and that blocking these receptors effectively inhibits RA progression. Our study was undertaken to investigate the role of AMG487, a selective CXCR3 antagonist, in DBA/1J mice bearing collagen-induced arthritis (CIA). Following induction of CIA, animals were treated with 5 mg/kg AMG487 intraperitoneally every 48 h, starting from day 21 until day 41 and evaluated for clinical score, and histological hallmarks of arthritic inflammation. We further investigated the effect of AMG487 on Th1 (T-bet), Th17 (IL-17A, RORγt, STAT3), Th22 (IL-22), and T regulatory (Treg; Foxp3 and IL-10) cells in splenic CXCR3⁺ and CD4⁺ T cells using flow cytometry. We also assessed the effect of AMG487 on T-bet, RORγt, IL-17A, IL-22, Foxp3, and IL-10 at both mRNA and protein levels using RT-PCR and Western blot analyses of knee samples. The severity of clinical scores, and histological inflammatory damage decreased significantly in AMG487-treated compared with CIA control mice. Moreover, the percentage of Th1, Th17, and Th22 cells decreased significantly and that of Treg cells increased in AMG487-treated mice. We further observed that AMG487-treatment downregulated T-bet, IL-17A, RORγt, and IL-22, whereas it upregulated Foxp3 and IL-10 mRNA and protein levels. This study demonstrates the antiarthritic effects of AMG487 in CIA animal model and supports the development of CXCR3 antagonists as a novel strategy for the treatment of inflammatory and arthritic conditions.     

Assessment of Treg/Th17 axis role in immunopathogenesis of chronic injuries of mustard lung disease

Purpose: Sulfur mustard (SM) lung is a heterogeneous disease associated with abnormal inflammatory immune responses. The Th17/Treg axis imbalance is associated with the pathogenesis of chronic inflammatory pulmonary disease. We aimed to determine the distribution of different Th17 and Treg cells in patients with SM lung and chronic obstructive pulmonary disease (COPD) and evaluate the clinical implications in this homeostasis. Methods: In this analytical cross-sectional study, CD4?⁺?Foxp3^+?Treg and CD4⁺?IL-17^+?Th17 cells were measured in peripheral blood mononuclear cells (PBMCs) and transbronchial biopsy (TBB) samples of 15 SM-exposed patients, 12 COPD and 13 healthy controls (HCs). The potential correlation between the ratio of Th17/Tregs and lung function was evaluated with multivariate logistic regression (MLR) analysis. Results: The frequency of CD4?⁺?FoxP3⁺?Tregs and CD4?⁺?IL-17⁺?Th17 was increased ～1.7-fold (8.71/4.95) and ～2.7-fold (1.028/0.371) respectively, in the PBMC of SM patients compared with the health controls (p?<?0.001). The results indicated that there were increases in the frequency of Th17 and Tregs cells in the patients with COPD versus the HC, that is, ～2.6-fold (0.987/0.371) and ～1.4-fold (7.12/4.95), respectively; but they did not reach to SM level (p?≥?0.05). Moreover, in the TBB samples, the CD4?⁺?IL-17^+?Th17 and CD4⁺?FoxP3^+?Tregs numbers were significantly higher in SM and COPD patients than HC (p?<?0.05). The Th17 and Treg cells were inversely correlated with forced expiratory volume in 1s (FEV1%) (r?=??0.351, p =?0.001; r?=??0.344, p?=?0.021) and FEV1/FVC (r?=??0.44, p?=?0.001; r?=??0.302, p?=?0.011), respectively. Instead, positive correlations were found between Treg/Th17 ratios and forced FEV1%pred (r?=?0.156, p?=?0.007), as well as FEV1/FVC ratio (r?=?0.334, p?=?0.006). Conclusions: The imbalance of Th17/Treg has a key role in immunopathogenesis of chronic phase of mustard lung disease.     

良性前列腺增生患者外周血Th17和Treg细胞比率的变化

目的:探讨良性前列腺增生患者外周血Th17和Treg细胞比率的变化。方法:选择33例良性前列腺增生患者及19例正常对照者为研究对象,采用流式细胞术检测和比较其外周血中T淋巴细胞亚群及Th17和Treg细胞占CD4~+T细胞的比率。结果:良性前列腺增生患者外周血Th17和Treg细胞占CD4~+T细胞的比率分别为1.58±0.71和1.76±0.83,Th17/Treg的比率为0.89±0.42。正常健康对照者外周血Th17和Treg细胞占CD4~+T细胞的比率分别为0.75±0.46和1.83±0.75,Th17/Treg的比率为0.41±0.32。良性前列腺增生患者外周血Th17占CD4~+T细胞的比率和Th17/Treg的比率明显高于正常健康对照者(P0.05)。结论:良性前列腺增生患者体内Th17细胞比率升高,Th17/Treg比率失衡,可能与良性前列腺增生的发生、发展有关。     

Cyclosporin A inhibits the production of IL-17 by memory Th17 cells from healthy individuals and patients with rheumatoid arthritis

Recent evidence from several studies indicated that IL-17-producing Th17 cells can represent the key effector cells in the induction and development of autoimmune disorders. Cyclosporine A (CsA) is a commonly used immunosuppressant to treat lots of autoimmune diseases including rheumatoid arthritis (RA). Here, we demonstrated that PBMCs and purified CD4⁺ T cells from healthy individuals and patients with RA could be induced to produce large amounts of IL-17 after stimulation with anti-CD3 plus anti-CD28 mAbs. Phenotypic analysis indicated that the majority of IL-17-producing cells were Th17 cells with memory phenotype. The addition of CsA into cell cultures significantly inhibited the IL-17 production by Th17 cells at protein and at mRNA levels. Compared to the PBMCs from normal individuals, PBMCs from the patients with RA produced higher levels of IL-17 that was also significantly inhibited by CsA both at protein and at mRNA levels. The mechanism might be the effect of CsA on the T cells activation because the expression of CD69 and CD25 molecules on T cells was markedly reduced in the presence of CsA. Taken together, these results demonstrated that CsA suppressed the IL-17 production and inhibited the Th17 cells differentiation from both healthy individuals and patients with RA.     

B Cells Contribute to Heterogeneity of IL-17 Producing Cells in Rheumatoid Arthritis and Healthy Controls

Secretion of the proinflammatory cytokine Interleukin-17A (IL-17A) is the hallmark of a unique lineage of CD4 T cells designated Th17 cells, which may play a crucial role in the pathogenesis of rheumatoid arthritis (RA) and many autoimmune diseases. Recently, IL-17-producing cells other than T cells have been described, including diverse innate immune cells. Here, we show that the cellular sources of IL-17A in RA include a significant number of non-T cells. Multicolour fluorescence analysis of IL-17-expressing peripheral blood mononuclear cells (PBMC) revealed larger proportions of IL-17⁺CD3^- non-T cells in RA patients than in healthy controls (constitutive, 13.6% vs. 8.4%, and after stimulation with PMA/ionomycin 17.4% vs. 7.9% p < 0.001 in both cases). The source of IL-17 included CD3^-CD56⁺ NK cells, CD3^-CD14⁺ myeloid cells as well as the expected CD3⁺CD4⁺ Th17 cells and surprisingly a substantial number of CD3^-CD19⁺ B cells. The presence of IL-17A-expressing B cells was confirmed by specific PCR of peripheral MACS-sorted CD19⁺ B cells, as well as by the analysis of different EBV-transformed B cell lines. Here we report for the first time that in addition to Th17 cells and different innate immune cells B cells also contribute to the IL-17A found in RA patients and healthy controls.     

APL1, an altered peptide ligand derived from human heat-shock protein 60, increases the frequency of Tregs and its suppressive capacity against antigen responding effector CD4 + T cells from rheumatoid arthritis patients

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by a chronic relapsing-remitting joint inflammation. Perturbations in the balance between CD4?+?T cells producing IL-17 and CD4?+?CD25^highFoxP3?+?Tregs correlate with irreversible bone and cartilage destruction in RA. APL1 is an altered peptide ligand derived from a CD4+ T-cell epitope of human HSP60, an autoantigen expressed in the inflamed synovium, which increases the frequency of CD4?+?CD25^highFoxP3+ Tregs in peripheral blood mononuclear cells from RA patients. The aim of this study was to evaluate the suppressive capacity of Tregs induced by APL1 on proliferation of effector CD4+ T cells using co-culture experiments. Enhanced Treg-mediated suppression was observed in APL1-treated cultures compared with cells cultured only with media. Subsequent analyses using autologous cross-over experiments showed that the enhanced Treg suppression in APL1-treated cultures could reflect increased suppressive function of Tregs against APL1-responsive T cells. On the other hand, APL1-treatment had a significant effect reducing IL-17 levels produced by effector CD4+ T cells. Hence, this peptide has the ability to increase the frequency of Tregs and their suppressive properties whereas effector T cells produce less IL-17. Thus, we propose that APL1 therapy could help to ameliorate the pathogenic Th17/Treg balance in RA patients.     

TLR2 stimulation drives human naive and effector regulatory T cells into a Th17-like phenotype with reduced suppressive function

Naturally occurring CD4(+)CD25(+)FOXP3(+) regulatory T cells suppress the activity of pathogenic T cells and prevent development of autoimmune responses. There is growing evidence that TLRs are involved in modulating regulatory T cell (Treg) functions both directly and indirectly. Specifically, TLR2 stimulation has been shown to reduce the suppressive function of Tregs by mechanisms that are incompletely understood. The developmental pathways of Tregs and Th17 cells are considered divergent and mutually inhibitory, and IL-17 secretion has been reported to be associated with reduced Treg function. We hypothesized that TLR2 stimulation may reduce the suppressive function of Tregs by regulating the balance between Treg and Th17 phenotype and function. We examined the effect of different TLR2 ligands on the suppressive functions of Tregs and found that activation of TLR1/2 heterodimers reduces the suppressive activity of CD4(+)CD25(hi)FOXP3(low)CD45RA(+) (naive) and CD4(+)CD25(hi)FOXP3(hi)CD45RA(-) (memory or effector) Treg subpopulations on CD4(+)CD25(-)FOXP3(-)CD45RA(+) responder T cell proliferation while at the same time enhancing the secretion of IL-6 and IL-17, increasing RORC, and decreasing FOXP3 expression. Neutralization of IL-6 or IL-17 abrogated Pam3Cys-mediated reduction of Treg suppressive function. We also found that, in agreement with recent observations in mouse T cells, TLR2 stimulation can promote Th17 differentiation of human T helper precursors. We conclude that TLR2 stimulation, in combination with TCR activation and costimulation, promotes the differentiation of distinct subsets of human naive and memory/effector Tregs into a Th17-like phenotype and their expansion. Such TLR-induced mechanism of regulation of Treg function could enhance microbial clearance and increase the risk of autoimmune reactions.