IL6 Receptor Facilitates Adipogenesis Differentiation of Human Mesenchymal Stem Cells through Activating P38 Pathway

Background and Objectives@#Mesenchymal stem cells (MSCs) have the multipotent capacity to differentiate into multiple tissue lineages as well as to self-renew, which is the main origin of adipocytes. IL6/IL6R pathway exerts a significant role in tissue regeneration and cell differentiation. Whereas, the underlying mechanism between IL6/IL6R pathway and MSCs adipogenesis differentiation remains elusive. @*Methods@#MSCs from healthy donors were cultured in adipogenesis differentiation medium for 0∼14 days, during which their adipogenesis differentiation degree was evaluated by Oil Red O staining. The expression of IL6R was detected in MSCs during adipogenesis differentiation. Knockdown and overexpression of IL6R were respectively performed using siRNA and lentivirus to investigate its effect on MSCs adipogenesis differentiation. The adipogenesis marker genes expression and MAPK pathway activation were detected by Western blotting. The role of P38 pathway in the adipogenesis differentiation of MSCs was determined using the specific inhibitor SB203580. @*Results@#The expression of IL6 and IL6R increased during adipogenesis differentiation in MSCs, which were positively correlated with Oil Red O quantification result. Knockdown and overexpression experiments demonstrated a positive correlation between the expressions of IL6R and MSCs adipogenesis differentiation, accompanied by same trend of P38 phosphorylation. Besides, the specific P38 inhibitor SB203580 markedly inhibited the adipogenesis differentiation potential of MSCs. @*Conclusions@#This study reveals IL6R facilitates the adiogenesis differentiation of MSCs via activating P38 pathway.

Elevated TRAF4 expression impaired LPS-induced autophagy in mesenchymal stem cells from ankylosing spondylitis patients

Ankylosing spondylitis (AS) is a type of autoimmune disease that predominantly affects the spine and sacroiliac joints. However, the pathogenesis of AS remains unclear. Some evidence indicates that infection with bacteria, especially Gram-negative bacteria, may have an important role in the onset and progression of AS. Recently, many studies have demonstrated that mesenchymal stem cells (MSCs) dysfunction may contribute to the pathogenesis of many rheumatic diseases. We previously demonstrated that MSCs from AS patients exhibited markedly enhanced osteogenic differentiation capacity in vitro under non-inflammatory conditions. However, the properties of MSCs from AS patients in an inflammatory environment have never been explored. Lipopolysaccharide (LPS), a proinflammatory substance derived from the outer membrane of Gram-negative bacteria, can alter the status and function of MSCs. However, whether MSCs from AS patients exhibit abnormal responses to LPS stimulation has not been reported. Autophagy is a lysosome-mediated catabolic process that participates in many physiological and pathological processes. The link between autophagy and AS remains largely unknown. The level of autophagy in ASMSCs after LPS stimulation remains to be addressed. In this study, we demonstrated that although the basal level of autophagy did not differ between MSCs from healthy donors (HDMSCs) and ASMSCs, LPS-induced autophagy was weaker in ASMSCs than in HDMSCs. Specifically, increased TRAF4 expression in ASMSCs impaired LPS-induced autophagy, potentially by inhibiting the phosphorylation of Beclin-1. These data may provide further insight into ASMSC dysfunction and the precise mechanism underlying the pathogenesis of AS.

Bone marrow mesenchymal stem cells derived from patients with ankylosing spondylitis show abnormal immunoregulation capability on macrophages / 中国组织工程研究

BACKGROUND:Ankylosing spondylitis is an autoimmune disease at high inflammatory state, and its pathogenesis is stil unclear. Besides, there is a lack of entirely satisfactory curative strategies. OBJECTIVE: To explore the immunoregulation capability of bone marrow mesenchymal stem cels from ankylosing spondylitis patients on macrophages and the potential therapeutic use of bone marrow mesenchymal stem cels from healthy donors on ankylosing spondylitis. METHODS: Bone marrow mesenchymal stem cels were extracted from 21 healthy donors and 25 ankylosing spondylitis patients respectively, and passage 4 cels were used in subsequent experiments. A human monocytic cel line was induced to differentiate into macrophages. The phenotypic markers of bone marrow mesenchymal stem cels and macrophages were detected by flow cytometry. Expressions of tumor necrosis factor-α and tumor necrosis factor-α-stimulated gene 6 (TSG-6) proteins in the supernatant of co-culture system were detected by ELISA. Quantitative real-time PCR was applied to detect the mRNA level of cytokines secreted by bone marrow mesenchymal stem cels and macrophages. RESULTS AND CONCLUSION:The typical mesenchymal stem cel surface markers were expressed in both bone marrow mesenchymal stem cels from healthy donors and patients with ankylosing spondylitis, and CD68 was detected positively in induced macrophages. The protein and mRNA levels of tumor necrosis factor-α secreted by macrophages co-cultured with bone marrow mesenchymal stem cels from patients with ankylosing spondylitis were obviously higher than those from healthy donors (P < 0.05). TSG-6 secreted by bone marrow mesenchymal stem cels from patients with ankylosing spondylitis was lower than that by bone marrow mesenchymal stem cels from healthy donors in both RNA transcriptional and protein levels (P < 0.05). Our study demonstrates that bone marrow mesenchymal stem cels from patients with ankylosing spondylitis shows abnormal immunoregulatory function on inhibiting the tumor necrosis factor-α secretion from macrophages, which reveals a mechanism of immune disorder in ankylosing spondylitis. The therapeutic mechanism of bone marrow mesenchymal stem cels from healthy donors may work by secreting enough TSG-6 to inhibit the activation of macrophages in patients with ankylosing spondylitis, and thereby to decrease the secretion of tumor necrosis factor-α. Cite this article:Sun SH, Wang P, Su CY, Xie ZY, Li YX, Li D, Wang S, Su HJ, Wu XH, Deng W, Wu YF, Shen HY. Bone marrow mesenchymal stem cels derived from patients with ankylosing spondylitis show abnormal immunoregulation capability on macrophages. Zhongguo Zuzhi Gongcheng Yanjiu. 2016;20(1):13-19.