CCL2 deficient mesenchymal stem cells fail to establish long-lasting contact with T cells and no longer ameliorate lupus symptoms

Abstract

Systemic lupus erythematosus (SLE) is a multi-organ autoimmune disease characterized by autoantibody production. Mesenchymal stem cells (MSCs) ameliorate SLE symptoms by targeting T cells, whereas the mechanisms of their efficacy remain incompletely understood. In this study, we show that transfer of human MSCs increased MRL.Faslpr mouse survival, decreased T cell infiltration in the kidneys, and reduced T cell cytokine expression. In vitro, allogeneic mouse MSCs inhibited MRL.Faslpr T cell proliferation and cytokine production. Time-lapse imaging revealed that MSCs recruited MRL.Faslpr T cells establishing long-lasting cellular contacts by enhancing T cell VCAM-1 expression in a CCL2-dependent manner. In contrast, CCL2 deficient MSCs did not induce T cell migration and VCAM-1 expression, resulting in insufficient cell-cell contact. Consequently, CCL2 deficient MSCs did not inhibit IFN-γ production by T cells and upon transfer no longer prolonged survival of MRL.Faslpr mice. Taken together, our imaging study demonstrates that CCL2 enables the prolonged MSC–T cell interactions needed for sufficient suppression of autoreactive T cells and helps to understand how MSCs ameliorate symptoms in lupus-prone MRL.Faslpr mice.

Effect of Human Mesenchymal Stem Cells on Xenogeneic T and B Cells Isolated from Lupus-Prone MRL.Faslpr Mice

“…Several preclinical studies have demonstrated that hMSCs ameliorate SLE progression in MRL.Fas lpr mice. Lee et al [14] showed that the transfer of hMSCs increased MRL.Fas lpr mouse survival, decreased T cell infiltration in the kidneys, and reduced T cell cytokine expression. Lee et al [24] also showed that hMSCs in combination with prednisone or mycophenolate mofetil had a better therapeutic effect than single therapy in MRL.Fas lpr mice; the following readouts were used in this study: prolongation of survival, decrease in anti-dsDNA and total IgG levels in serum, decrease in cytokine gene expression in spleen cells, and decrease in inflammatory cell infiltration into the kidney.…”

“…Mice were housed in specific pathogen-free conditions at 21-24°C and 40-60% relative humidity under a 12 h light/dark cycle. Female MRL.Fas lpr mice were injected intravenously with PBS (vehicle, n = 6) or 4 × 10 5 hMSCs/mouse (n = 6) once at the age of 12 weeks [14]. Survival rate and body weight were examined every week.…”

“…Various concentrations of chemokines or MSCs were added to the lower wells in 600 μl of complete RPMI 1640 medium. The number of B cells that had migrated to the lower well over 1.5 h was counted using a flow cytometer [14].…”

“…To measure B cell proliferation, purified B cells (1 × 10 5 cells/well) and MSCs (0:01 -0:1 × 10 5 cells/well) were mixed in 96-well plates. In some experiments, MSCs were cultured in the upper well and B cells in the lower well of transwell plates (Corning) to avoid cell-cell contact [14]. B cells were activated with lipopolysaccharide (LPS, 1 μg/ml) on day 0 [19].…”

“…Systemic lupus erythematosus (SLE) is characterized by the production of autoantibodies to ubiquitous self-antigens [13]. In preclinical studies, the transfer of human MSCs (hMSCs) to lupus-prone MRL/MpJ-Fas lpr (called MRL.Fas lpr hereafter) mice increased their survival and decreased the anti-dsDNA antibody level and nephritis [14]. However, it is still unclear whether hMSCs inhibit mouse T and B cells in this xenogeneic animal model.…”