Background: Activated T lymphocytes play an important role in the pathogenesis of rheumatic diseases (RD). Mesenchymal stem cells (MSCs) possess immunoregulatory activities but such functions of MSCs from bone marrow of systemic lupus erythematosus (SLE), systemic sclerosis (SSc), and ankylosing spondylitis (AS) patients are impaired. Adipose tissue-derived MSCs (ASCs) are an optional pool of therapeutically useful MSCs, but biology of these cells in RD is poorly known. This study aimed at investigating the effect of ASCs from RD patients and healthy donors (HD) on the expression of the key T-cell activation markers.
Methods: ASCs were isolated from subcutaneous abdominal fat from SLE (n = 16), SSc (n = 18), and AS (n = 16) patients, while five human ASCs lines from HD were used as a control. Untreated and cytokine (tumor necrosis factor α + interferon γ)-treated ASCs were co-cultured with allogenic, mitogen (phytohemagglutinin)-stimulated peripheral blood mononuclear cells (PBMCs) or purified anti-CD3/CD28-activated CD4+ T lymphocytes. Contacting and noncontacting ASCs-PBMCs co-cultures were performed. RD/ASCs were analyzed in co-cultures with both allogeneic and autologous PBMCs. Flow cytometry analysis was used to evaluate expression of CD25, HLA-DR, and CD69 molecules on CD4+ and CD8+ cells.
Results: In co-cultures with allogeneic, activated CD4+ T cells and PBMCs, HD/ASCs and RD/ASCs downregulated CD25 and HLA-DR, while upregulated CD69 molecules expression on both CD4+ and CD8+ cells with comparable potency. This modulatory effect was similar in contacting and noncontacting co-cultures. RD/ASCs exerted weaker inhibitory effect on CD25 expression on autologous than allogeneic CD4+ and CD8+ T cells.
Conclusion: RD/ASCs retain normal capability to regulate expression of activation markers on allogeneic T cells. Both HD/ASCs and RD/ASCs exert this effect independently of their activation status, mostly through the indirect pathway and soluble factors. However, autologous CD4+ and CD8+ T cells are partially resistant to RD/ASCs inhibition of CD25 expression, suggesting weaker control of T-cell activation in vivo.
Keywords: T-cell activation; adipose tissue–derived mesenchymal stem cells; ankylosing spondylitis; systemic lupus erythematosus; systemic sclerosis.