The mechanism of TDP-43 gene expression on inflammatory factors and the JNK and p38 MAPK signalling pathways in ischaemic hypoxic stress dependence

In this study, the mechanism of TDP-43 gene expression on inflammatory factors and Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) signalling pathways in ischaemic hypoxic stress dependence was investigated. Sixty SD rats were selected and divided into the control group, the osteoarthritis (OA) model group, and the TDP-43-mMSCs+OA group. In the OA model group and the TDP-43-mMSCs+OA group, OA was established by collagenase injection. Western blotting assays were used to detect the expression of TDP-43 in cartilage tissues of each rat. The secretion of tumour necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) in the serum of rats was determined by enzyme-linked immunosorbent assay (ELISA). The formation of cytoplasmic stress granules (SGs) and the expression of receptor for activated c-kinase 1 (RACK1) were detected by Western blotting assays in each group of rats. The expression of MTK1 and MAPKKK phosphorylation and changes in the JNK and p38 MAPK signalling pathways were detected by Western blotting assays. Compared with the control group, the expression of TDP-43 in the cartilage tissue of rats in the OA model group was significantly decreased. The expression of TDP-43 in the cartilage tissue of rats in the TDP-43-mMSCs+OA group was significantly higher than that of the control group and the OA model group, which indicates that TDP-43-mMSC transplantation was successful. Enzyme-linked immunosorbent assay results showed that the plasma TNF-alpha and IL-1 beta levels in the OA model group were significantly increased (P < 0.01) when compared with the control group. However, the secretion of TNF-alpha and IL-1 beta in the serum of the TDP-43-mMSCs+OA group was significantly lower than that of the model group (P < 0.01) but still higher than the control group. This indicates that overexpression of TDP-43 reduces the inflammatory response induced by OA. Western blotting assays showed that the amount of cytoplasmic SGs in the cartilage tissue of rats in the OA model group was significantly decreased when compared with the control group. The amount of SGs in the cartilage of rats in the TDP-43-mMSCs+OA group was significantly higher than that of the model group. The expression of RACK1 in the cartilage tissue of rats in the OA model group was significantly higher than that of the control group. Overexpression of the TDP-43 gene can interfere with the secretion of inflammatory factors and inhibit the activation of the JNK and p38 MAPK signalling pathways by ischaemic hypoxia stress. Thus, the molecular mechanism of chondrocytopathic lesions was reversed, which provided a new theoretical basis for the treatment of OA.