The Abnormal Activation Of TLR4 Mediates The Senescence Of BM-MSCs In The Pathogenesis Of SLE

Objective Systemic lupus erythematosus(SLE)is chronic multisystem immune-mediated inflammatory disease characterized by multi-organ involvement.Senescence of bone marrow-mesenchymal stem cells from systemic lupus erythematosus patients participated in the development of SLE.Previous studies revealed that Inflammatory microenvironment played an important role in cellular senescence.The aim of this study was to investigate whether "Inflammatory microenvironment" could lead to senescence BM-MSCs from SLE patients and its possible mechanism.Methods Tewelve female SLE patients and healthy subjects were enrolled in the study.All patients were females,and their age distribution was similar to that of the cases.Bone marrow supernatant and serum from SLE patients and healthy controls was collected to analyzed the levels of HMGB1(High mobility group box 1).All BM-MSCs were isolated by density gradient centrifugation.Bone marrow supernatant stimulated normal BM-MSCs,then observing the activity of ?-gal of cells,the changes of cytoskeletal structure by F-actin staining and the distribution of cell cycle by flow cytometry and detecting expression of TLR4/NF-?B signaling pathway by Western Blotting.HMGB-1(the endogenous ligand of TLR4)stimulated normal BM-MSCs,then observing senescence signs and detecting expression of TLR4/NF-?B signaling pathway by WB.Lastly,WB was used to distinguish the difference of expression of TLR4/NF-?B signaling pathway between normal group and SLE group.We used small interfering RNA(siRNA)to interfere the expression of TLR4 and observing senescence signs.Results Compared with control groups,many kinds of inflammatory factors in bone marrow supernatant of SLE patients were abnormal,including HMGB1.The expression of HMGB1 in SLE bone marrow supernatant and serum was higher than that of normal control.After stimulation of bone marrow supernatant from SLE patients HMGB1 in normal MSCs,the cell volume and the number of SA-?-gal positive in SLE BM-MSCs was increased.The organization of cytoskeleton was neatly disordered.The rate of cell proliferation was decreased.And,TLR4 signaling was activated.After stimulation of HMGB1 in normal BM-MSCs,BM-MSCs present senescence signs.And,TLR4 signaling was activated.BM-MSCs from SLE patients showed abnormal activation of TLR4 signaling transduction,high level of p-IRAK1 and p-p65,low level of I?B?.Small interfering RNA(siRNA)of TLR4 can significantly reverse the senescence.Conclusion HMGB-1,binded to TLR4,promoted NF-?B signal transduction,thereby affected the expression of cell cycle-related proteins,and then resulted in senescence of MSCs from SLE patients.