Abrogation of Treg function deteriorates rheumatoid arthritis

Dysfunctions, Molecular Mechanisms, and Therapeutic Strategies of Regulatory T Cells in Rheumatoid Arthritis

Regulatory T cells (Tregs) represent a distinct subpopulation of CD4⁺ T lymphocytes that promote immune tolerance and maintain immune system homeostasis. The dysfunction of Tregs is tightly associated with rheumatoid arthritis (RA). Although the complex pathogenic processes of RA remain unclear, studies on Tregs in RA have achieved substantial progress not only in fundamental research but also in clinical application. This review discusses the current knowledge of the characterizations, functions, and molecular mechanisms of Tregs in the pathogenesis of RA, and potential therapies for these disorders are also involved.

Daurinol Attenuates Autoimmune Arthritis via Stabilization of Nrp1-PTEN-Foxp3 Signaling in Regulatory T Cells

Optimizing Treg function and improving Treg stability are attractive treatment strategies for treating autoimmune rheumatoid arthritis (RA). However, the limited number of circulating Tregs and questions about the functional stability of in vitro-expanded Tregs are potential limitations of Treg-based cell therapy. The aim of this study was to analyze the regulatory effect of daurinol, a catalytic inhibitor of topoisomerase IIα, on Th cell differentiation and to evaluate their therapeutic potential in a preclinical experimental model of RA. We investigated the effect of daurinol on T cell differentiation by flow cytometry. Foxp3 stability and methylation were analyzed by suppression assays and bisulfite pyrosequencing. Daurinol was treated in the collagen-induced arthritis (CIA) model, and the effects in vivo were determined. We found that daurinol can promote Treg differentiation and reciprocally inhibit Th17 differentiation. This Treg-inducing property of daurinol was associated with decreased activity of Akt-mTOR and reciprocally increased activity of neuropilin-1 (Nrp1)-PTEN. Daurinol treatment inhibited aerobic glycolysis in Th17 conditions, indicating the metabolic changes by daurinol. We found that the daurinol increase the Treg stability was achieved by Foxp3 hypomethylation. In vivo daurinol treatment in CIA mice reduced the clinical arthritis severity and histological inflammation. The Treg population frequency increased and the Th17 cells decreased in the spleens of arthritis mice treated with daurinol. These results showed the anti-arthritic and immunoregulating properties of daurinol is achieved by increased differentiation and stabilization of Tregs. Our study provides first evidence for daurinol as a treatment for RA.

Glucocorticoid-induced tumour necrosis factor receptor-related protein: a key marker of functional regulatory T cells

Glucocorticoid-induced tumour necrosis factor receptor-related protein (GITR, TNFRSF18, and CD357) is expressed at high levels in activated T cells and regulatory T cells (Tregs). In this review, we present data from mouse and human studies suggesting that GITR is a crucial player in the differentiation of thymic Tregs (tTregs), and expansion of both tTregs and peripheral Tregs (pTregs). The role of GITR in Treg expansion is confirmed by the association of GITR expression with markers of memory T cells. In this context, it is not surprising that GITR appears to be a marker of active Tregs, as suggested by the association of GITR expression with other markers of Treg activation or cytokines with suppressive activity (e.g., IL-10 and TGF-β), the presence of GITR(+) cells in tissues where Tregs are active (e.g., solid tumours), or functional studies on Tregs. Furthermore, some Treg subsets including Tr1 cells express either low or no classical Treg markers (e.g., FoxP3 and CD25) and do express GITR. Therefore, when evaluating changes in the number of Tregs in human diseases, GITR expression must be evaluated. Moreover, GITR should be considered as a marker for isolating Tregs.

CD4(+)CD25(+) regulatory T cells as a therapeutic target in rheumatoid arthritis

CD4(+)CD25(+) T cells are regulatory T cells (CD4(+)CD25(+) Tregs), which can strengthen immune tolerance. They play a critical role in controlling the development of autoimmune diseases in animals and humans. Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects the peripheral joints and eventually leads to joint destruction. Although the pathogenesis of RA remains unknown, it is supposed to be affected by autoreactive T cells and antibodies. At the same time, to make the CD4(+)CD25(+) T cells active and to increase the number of the cells are responsible in the therapy of RA in recent studies. Now, many techniques about expansion of Tregs in vitro have been established to overcome the problem of their limited numbers in vivo. It is important to carry out a study of induction or amplification of Tregs in vitro. Here, we review our current understanding of CD4(+)CD25(+) T cells in RA and the targeting of these cells in RA therapy.

Treg/Th17 imbalance is associated with cardiovascular complications in uremic patients undergoing maintenance hemodialysis

Investigations of Treg/Th17 imbalance associated with cardiovascular complications in hemodialysis are limited. The aim of this study was to examine the association between Treg/Th17 balance and cardiovascular comorbidity in maintenance hemodialysis (MHD). Uremic patients included in the present study were divided into three groups: the WHD group comprising 30 patients with no cardiovascular complications or maintenance hemodialysis (MHD), the MHD1 group comprising 36 patients presenting with cardiovascular complications during MHD, and the MHD2 group comprising 30 patients with a lack of cardiovascular complications during MHD. The control group comprised 20 healthy volunteers. Th17 and Treg cells were measured by fluorescence-activated cell scanning (FACS). IL-6 and IL-10 levels were determined by enzyme-linked immunosorbent assay (ELISA). Monocyte surface expression of the costimulatory molecules CD80 and CD86 was assessed by FACS after the monocytes were cocultured with Th17 or Treg cells in the presence or absence of IL-17. Results revealed that the percentage of Th17 of total CD4(+) cells was significantly higher in the MHD1 (36.27±9.62% in) and WHD (35.98±8.85%) groups compared with the MHD2 (19.64±5.97%) and healthy (1.12±1.52%) groups. Elevated IL-6 levels were obtained in Th17 cells for the MHD1 and WHD groups, whereas a marked decrease was evident when IL-17 was blocked. However, no significant differences or cardiovascular complications were detected in the expression of CD80 and CD86 in the MHD group, whereas the expression of the uremic subgroups was statistically higher compared with the healthy controls. To the best of our knowledge, this is the first study to demonstrate that the Treg/Th17 imbalance may be associated with the pathogenesis of cardiovascular complications in uremic patients undergoing hemodialysis through the B7-independent upregulation of IL-6 induced by IL-17.