Increased Frequency and Compromised Function of T Regulatory Cells in Systemic Sclerosis (SSc) Is Related to a Diminished CD69 and TGFβ Expression

Abstract

BackgroundRegulatory T cells (Tregs) are essential in the control of tolerance. Evidence implicates Tregs in human autoimmune conditions. Here we investigated their role in systemic sclerosis (SSc).Methods/Principal FindingsPatients were subdivided as having limited cutaneous SSc (lcSSc, n = 20) or diffuse cutaneous SSc (dcSSc, n = 48). Further subdivision was made between early dcSSc (n = 24) and late dcSSc (n = 24) based upon the duration of disease. 26 controls were studied for comparison. CD3+ cells were isolated using FACS and subsequently studied for the expression of CD4, CD8, CD25, FoxP3, CD127, CD62L, GITR, CD69 using flow cytometry. T cell suppression assays were performed using sorted CD4CD25highCD127- and CD4CD25lowCD127high and CD3+ cells. Suppressive function was correlated with CD69 surface expression and TGFβ secretion/expression. The frequency of CD4+CD25+ and CD25highFoxP3highCD127neg T cells was highly increased in all SSc subgroups. Although the expression of CD25 and GITR was comparable between groups, expression of CD62L and CD69 was dramatically lower in SSc patients, which correlated with a diminished suppressive function. Co-incubation of Tregs from healthy donors with plasma from SSc patients fully abrogated suppressive activity. Activation of Tregs from healthy donors or SSc patients with PHA significantly up regulated CD69 expression that could be inhibited by SSc plasma.Conclusions/SignificanceThese results indicate that soluble factors in SSc plasma inhibit Treg function specifically that is associated with altered Treg CD69 and TGFβ expression. These data suggest that a defective Treg function may underlie the immune dysfunction in systemic sclerosis.

Preterm neonates show marked leukopenia and lymphopenia that are associated with increased regulatory T-cell values and diminished IL-7

“…This fact could explain the presence of high values of Tregs in neonates and the negative correlation between Treg frequency and GA. In fact, we observed that absolute counts and percentage of Tregs in both preterm and full-term infants are higher than the values reported in the literature for children (17) and adults (35). The presence of increased values of Tregs in preterm infants would play a protective role in maternal-fetal tolerance but could have a secondary effect by which Tregs inhibit the survival and proliferation of lymphocytes and other immune cells.…”

Peripheral blood regulatory T cells in patients with diffuse systemic sclerosis (SSc) before and after autologous hematopoietic SCT: a pilot study

“…In SSc patients, few studies investigated the various Treg subsets and their suppressive function, these also with conflicting results, showing either reduced, 20-22 increased 23,24 or the same [25][26][27] number of circulating Treg cells in peripheral blood as compared with controls. These discrepancies might be mostly due to variations in study techniques, with setting analysis of either CD4 þ CD25 þ , 21,23 CD4 þ CD25 high , 12,25,26 20,24,26 CD25 þ Foxp3 þ CD127 -23 or CD4 þ CD25 high CD127 low subsets. 22 Despite these controversies, in most of these studies of SSc patients' samples, 22,23,26 impaired Treg-suppressive function was associated with SSc disease severity.…”

“…These discrepancies might be mostly due to variations in study techniques, with setting analysis of either CD4 þ CD25 þ , 21,23 CD4 þ CD25 high , 12,25,26 20,24,26 CD25 þ Foxp3 þ CD127 -23 or CD4 þ CD25 high CD127 low subsets. 22 Despite these controversies, in most of these studies of SSc patients' samples, 22,23,26 impaired Treg-suppressive function was associated with SSc disease severity. Of interest, Klein 1 et al 26 reported that there was a reduction in Treg within the skin, but not in the peripheral blood of SSc patients.…”

The autoimmune disease-associated IL2RA locus is involved in the clinical manifestations of systemic sclerosis

“…18,19 Although the aetiology of SSc is not yet understood, there are evidences strongly suggesting that misregulation of T regs may underlie the immune dysfunction in the progression of this disease. 20,21 Interestingly, it has been proposed that skin-specific T reg anomalies could be crucial in the SSc pathogenesis. 21 As IL2RA has an important role in T reg regulation, 2 genetic alteration of its encoding gene could have serious consequences in the function of this cell type by altering the IL2/IL2R signalling.…”