Interleukin-2 in systemic autoimmunity hits the micro way

IL-2 Inhibition of Th17 Generation Rather Than Induction of Treg Cells Is Impaired in Primary Sjögren's Syndrome Patients

Objective

To investigate the role of IL-2 in the balance of Th17 and Tregs and elucidate the underlying mechanisms of enhanced Th17 differentiation in primary Sjögren’s syndrome (pSS) patients.

Methods

This study involved 31 pSS patients, 7 Sicca patients, and 31 healthy subjects. Th17 and Treg cells were determined by flow cytometry, and IL-17A was detected by immunohistochemistry. IL-2 and IL-6 levels were assessed by ELISA and qPCR. p-STAT5 and p-STAT3 in salivary glands (SGs) were evaluated by immunohistochemistry and flow cytometry. The binding of STAT5 and STAT3 to the Il17a gene locus was measured by chromatin immunoprecipitation.

Results

We found that the percentage of Th17 cells was increased in the periphery and SG of pSS patients when compared with healthy subjects, but the Treg cells was unchanged. Meanwhile, the IL-2 level was reduced, and the IL-6 and IL-17A level was increased in the plasma of pSS patients. The ratio of IL-2 and IL-6 level was also decreased and IL-2 level was negatively correlated with the level of IL-17A. The expression of Il6 and Il17a mRNA was significantly increased, whereas Foxp3, Tgfb1, Tnfa, and Ifng mRNA were comparable. Furthermore, the level of STAT5 phosphorylation (p-STAT5) was reduced and p-STAT3 was enhanced in the SGs and in peripheral CD4⁺ T cells of pSS patients. In vitro IL-2 treatment-induced STAT5 competed with STAT3 binding in human Il17a locus, leading to decreased Th17 differentiation, which was associated with the reduced transcription activation marker H3K4me3.

Conclusion

Our findings demonstrated a Treg-independent upregulation of Th17 generation in pSS, which is likely due to a lack of IL-2-mediated suppression of Th17 differentiation. This study identified a novel mechanism of IL-2-mediated immune suppression in pSS.

Regulatory T cells in acute and chronic kidney diseases

Foxp3-expressing CD4+ regulatory T cells (Tregs) make up one subset of the helper T cells (Th) and are one of the major mechanisms of peripheral tolerance. Tregs prevent abnormal activation of the immune system throughout the lifespan, thus protecting from autoimmune and inflammatory diseases. Recent studies have elucidated the role of Tregs beyond autoimmunity. Tregs play important functions in controlling not only innate and adaptive immune cell activation, but also regulate nonimmune cell function during insults and injury. Inflammation contributes to a multitude of acute and chronic diseases affecting the kidneys. This review examines the role of Tregs in pathogenesis of renal inflammatory diseases and explores the approaches for enhancing Tregs for prevention and therapy of renal inflammation.

Jieduquyuziyin prescription suppresses IL-17 production and Th17 activity in MRL/lpr mice by inhibiting expression of Ca(2+)/calmodulin-dependent protein kinase-4

Jieduquyuziyin prescription (JP) is a traditional Chinese medicinal (TCM) formula which has been demonstrated to be effective for systemic lupus erythematosus (SLE) treatment as an approved hospital prescription for many years in China. But its mechanism of action in combating this disease is largely unknown. Our previous studies showed that JP can slow disease progression without producing significant toxic side effects. We treated MRL/lpr mice with JP to ascertain if JP could improve SLE by the suppression of Ca(2+)/calmodulin-dependent protein kinase-4 (CaMK4) expression. We investigated the role of JP in a model of SLE in MRL/lpr mice, and identified the possible mechanism of action. Mice were divided randomly into four groups: control, model, and two treatment groups. Sections of renal tissue were stained with hematoxylin and eosin (H&E). Histopathologic changes in the kidney were evaluated by light microscopy. T-helper (Th)17 cells were analyzed by flow cytometry. mRNA levels of interleukin (IL)-17, CaMK4, and RORγt were measured by reverse transcription polymerase chain reaction (RT-PCR). CaMK4 expression was assessed by Western blotting. The results showed that the percentages of Th17, IL-17, and RORγt in mice treated with JP were decreased remarkably compared to the model group (p < 0.05). Interestingly, a high CaMK4 expression was observed in the SLE mice, which was inhibited by JP. These results suggest that CaMK4 activity was increased in T cells from MRL/lpr mice compared with the control group. Our findings support the conclusion that the effects of JP on MRL/lpr mice may involve the regulation of CaMK4 overexpression in MRL/lpr mice.