Sle Bone Marrow Mscs Abnormal Expression Ccl2 Regulation Function And Mechanism Of B Cell Research

Background:Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by multiorgan involvement. Allogenic mesenchymal stem cells (MSCs) transplantation has become a new therapeutic option for refractory SLE. We have demonstrated that SLE bone marrow derived MSCs were defective in gene expression, cytoskeleton, osteogenic differentiation as well as apoptosis and senescence when compared with those from normal controls.Objective:This study aimed to assess whether inhibition on B cell proliferation and differentiation by lupus bone marrow MSCs was impaired and the underlying molecular mechanisms involved in this process.Methods:MRL/lpr mice were divided into control group, normal MSCs-treated group and lupus MSCs-treated group. Blood was collected to measure serum levels of antinuclear antibody (ANA), anti-double-stranded DNA (anti-dsDNA) antibody, Interleukin (IL)-4, IL-10and transforming growth factor (TGF)-β1by enzyme linked immunosorbent assay (ELISA). Twenty-four-hour urine was collected to measure levels of proteinuria by Coomassi brilliant blue method. The expression of TGF-(31in kidney was detected by immunohistochemistry assay. And the histopathology of the kidneys was observed. In vitro bone marrow MSCs were isolated and expanded from C57BL/6mice, or MRL/lpr mice, or SLE patients, or healthy subjects. The effects of MSCs on the proliferation and differentiation to plasma cells of normal splenic B cells isolated from C57BL/6mice were evaluated in vitro by flow cytometry. The content of IgG and IgM from the culture supernatants was detected by ELISA. And the differential expression of CCL2on bone marrow MSCs from C57BL/6mice, or MRL/lpr mice, or SLE patients, or healthy subjects was detected. Then the effects of CCL2overexpression by CCL2expression vector or knockdown by CCL2siRNA on the B-cell proliferation and differentiation regulated by MSCs were determined by flow cytometry.Results:The survival rate of MRL/lpr mice did not differ significantly between lupus and normal bone marrow MSCs treated groups; the extent of the24h urine protein decreased in the lupus bone marrow MSCs treated group significantly less than normal bone marrow MSCs treated group; the extent of the serum levels of ANA and anti-dsDNA antibody titer and IL-4, IL-10levels decreased in the lupus bone marrow MSCs treated group significantly less than normal bone marrow MSCs treated group; the extent of the serum levels of TGF-β1levels and the expression of TGF-β1in kidney changed in the lupus bone marrow MSCs treated group significantly less than normal bone marrow MSCs treated group; the extent of the severity of renal damage improved in the lupus bone marrow MSCs treated group significantly less than normal bone marrow MSCs treated group.Bone marrow MSCs from C57BL/6mice inhibited the proliferation and differentiation to plasma cells of B cells in vitro. This inhibitory effect was mediated by soluble factors, including CCL2, as neutralizing CCL2could abolish the suppressive effect on B cells mediated by normal MSCs. The addition of processed CCL2significantly inhibited B-cell proliferation and differentiation. This inhibitory effect by MSCs from MRL/lpr mice was impaired, partially resulted from down-regulated expression of CCL2. The inhibition on B-cell proliferation and differentiation by bone marrow MSCs was markedly elevated through CCL2overexpression or reduced by CCL2knockdown.Conclusion:The curative effect of lupus bone marrow MSCs transplantation in MRL/lpr mice is worse than normal bone marrow MSCs transplantation, which may be correlated with impaired inhibition on B-cell proliferation and differentiation by lupus bone marrow MSCs. And the inhibitory effects of MSCs on B-cell are mediated by soluble factors including CCL2. Impaired inhibition of lupus bone marrow MSCs on B-cell may attribute to the down-regulation of CCL2expression, which may play an important role in the pathogenesis of SLE.