Analysis of CD95 and CCR7 expression on circulating CD4+ lymphocytes revealed disparate immunoregulatory potentials in systemic lupus erythematosus

Abstract

Emerging data have implicated a critical role for CD4 in the pathogenesis of systemic lupus erythematosus (SLE). This study was designed to delineate the contribution of CD4+ T cells in the pathogenesis of SLE disease. Forty-four patients (3 male: 41 female) and 20 healthy volunteers (4 male: 16 female) were included in the study. CD4+ lymphocytes analysis was done using three-color flow cytometry with antibodies against human-CD95, a prototype cell death receptor, and the chemokine receptor-7 (CCR7) after gating for lymphocytes based on the forward and side scatter. Serum levels of IL-6, IL-12, IL-17, TNF-α and IL-10 cytokines were assayed using ELISA. Disease activity was assessed using the SLE disease activity index (SLEDAI). Based on the expression of CCR7 and CD95, CD4+ lymphocytes were subdivided into three particular subsets; CD4+CD95+CCR7+ cells, CD4+CD95−CCR7+ cells and CD4+CD95+CCR7− cells. Percentage of CD4+CD95+CCR7+ cell subset was significantly higher in patients with SLE with active disease (SLEDAI>6) and inactive (SLEDAI<6) as compared with controls (P=0.005), and it showed a significant positive correlation with ANA titer (P=0.01), and a negative correlation with WBCs count (P=0.001). CD4+CD95+CCR7− cell subset was significantly higher in active SLE patients in comparison to patients with inactive disease and controls (P=0.05, P=0.005 respectively), and it correlates positively with SLEDAI, IL-6 and IL-17 levels (P=0.001, 0.05, 0.01 respectively), and negatively with blood WBCs counts (P=0.001). The third CD4+CD95−CCR7+cell subset was found significantly lower in SLE patients compared with controls, and it was found negatively correlated with IL-10, IL-6, and IL-17. The results show that CD4+CD95+subset lacking expression of CCR7 is associated with cell mediated inflammatory response as manifested by its correlation with signs of inflammation, inflammatory cytokines and disease activity index. Whereas, CD4+CD95+CCR7+ correlate more with antibody immune responses as manifested by association with serum ANA. These data suggest disparate roles of these cell subsets in the pathophysiology of SLE. A better understanding of the characteristics of CD4 cell subsets may shed light on the pathogenesis of autoimmune diseases, particularly SLE.