The Effect Of MSCs On The Apoptosis Of B Cells In SLE Treament

Background:Cell apoptosis plays a role in the pathogenesis of systemic lupus erythematosus(SLE),the main feature of which is the increase of apoptosis of T cells and B cells.Mesenchymal stem cells(MSCs)has both strong immunoregulatory function and effects on the cell apoptosis.Transplantation of MSCs can alleviate the severity of SLE,but the detailed mechanisms regarding this remain unknown.Whether the regulatory function of MSCs on cell apoptosis contribute to the mechanism needs to be elucidated.Objective:To explore the effects and underlying mechanisms of MSCs on the B cells apoptosis in SLE patients and lupus mice.Methods:Flow cytometry was used to examine the apoptosis rates of B cells in the peripheral blood of healthy controls(HC)and patients with SLE.hUC-MSCs were isolated from human umbilical cord.hUC-MSCs were co-cultured with CD 19+cells isolated from peripheral blood by magnetic activated cell sorting(MACS)for 12 hours or 24 hours and then the apoptosis rates of B cells were examined by flow cytometry.Soluble TNF related apoptosis inducing ligand(sTRAIL)in plasma of SLE patients was detected by ELISA(Enzyme-linked immunosorbent assay)and Pearson correlation analysis was used to analysis the correlation of sTRAIL with clinical and laboratory parameters.Peripheral blood mononuclear cells(PBMCs)were isolated from peripheral blood of SLE patients and co-cultured with hUC-MSCs for 24 hours and then the mRNA levels of TRAIL,TRAIL receptor-1(TRAIL-R1)and TRAIL receptor-2(TRAIL-R2)were examined by quantitative real-time reverse transcription-polymerase chain reaction(qRT-PCR).Recombinant TRAIL(r-TRAIL)was used to co-culture with B cells for different hours and then the apoptosis rates were detected.10 weeks old lupus mice were breeding in the SPF room up to 16 weeks old and then all the lupus mice were randomly divided into four groups.1 × 106 hUC-MSCs were injected into the first and second group via tail vein and the same volume of PBS was injected into the other two groups.24 hours or 1 month later,the mice were sacrificed to detect the apoptosis rates of B cells of blood,lymph node and spleen by flow cytometry.Serum anti-dsDNA antibody was tested by ELISA,urine protein was measured by the method of coomassie brilliant blue.Histopathology of kidneys were observed by HE staining.500ul pristane was intraperitoneally injected into 10 weeks old female BABL/c mice for 72 hours to induce lymphocytes apoptosis in peritoneal cavity,1×106hUC-MSCs were injected into peritoneal cavity for 24 hours then the apoptosis rates of intraperitoneal B cells were detected by flow cytometry.Results:The apoptosis rates of CD19+B cells from the peripheral blood of SLE patients are significantly higher than those of HC.In vitro,hUC-MSCs inhibit the apoptosis of CD19+B cells isolated from SLE.The level of sTRAIL in the plasma of SLE is higher than healthy controls and is correlated with the level of urine protein.In vitro,hUC-MSCs inhibit TRAIL and TRAIL-R1 mRNA expression.hUC-MSCs suppress the apoptosis rates of B220+cells from the spleen of BABL/c mice.Translation of hUC-MSCs can downregulate the level of anti-dsDNA antibody and alleviate lymphocytes infiltration in the kidneys but has no significant effect on the apoptosis of B220+cells from blood,spleen and lymph node of MRL/lpr mice.Pristane can induce apoptosis of lymphocytes in peritoneal cavity of BABL/c mice and transplantation of hUC-MSCs could inhibit the apoptosis of B220+cells.Conclusions:hUC-MSCs inhibit the apoptosis of B cells may alleviate B cells lymphopenia in SLE.