Serine protease inhibitor E2 protects against cartilage tissue destruction and inflammation in osteoarthritis by targeting NF-κB signaling.

OBJECTIVE: Osteoarthritis (OA) is a chronic disease characterized by cartilage degeneration and inflammation, with no approved disease-modifying drugs. This study aimed to identify pathogenic genes and elucidate their mechanism in OA. METHODS: We systematically identified pathogenic genes combined sing-cell and bulk transcriptome profiles of cartilage tissues in OA. Adenovirus carrying the serpin peptidase inhibitor clade E member 2 (serpinE2) or exogenous serpinE2 was injected into monosodium iodoacetate (MIA)-induced OA-model rats. Histological analysis, immunohistochemistry, and Alcian blue staining were performed. In vitro, immunofluorescence, quantitative real-time PCR (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), and western blot assays were performed. RESULTS: SerpinE2 exhibited elevated expression and hypomethylation, showing a positive association with collagen pathway activities in patients with OA. Silencing serpinE2 aggravated MIA-induced knee cartilage degeneration in OA-model rats. Conversely, the intra-articular injection of exogenous serpinE2 ameliorated articular cartilage degeneration, reduced pain-related behavioral responses, and relieve synovitis in MIA-induced OA-model rats. Exogenous serpinE2 not only attenuated the elevation of NLRP3, IL-1ß, and caspase1 expression levels but also restored the reduction in cell viability induced by lipopolysaccharide (LPS) in chondrocytes. Mechanistically, we found that exogenous serpinE2 inhibited LPS-induced reactive oxygen species (ROS) release and NF-κB signalling activation. CONCLUSIONS: SerpinE2 plays a protective role in cartilage and synovium tissues, suggesting that serpinE2 gene transfer or molecules that upregulate serpinE2 expression could be therapeutic candidates for OA.

Neuroepithelial cell-transforming 1 promotes cardiac fibrosis via the Wnt/ß-catenin signaling pathway.

This study found that the level of neuroepithelial cell-transforming gene 1 protein (NET1) was significantly increased in a mouse cardiac fibrosis model. Moreover, the expression level of NET1 was increased in cardiac fibrosis induced by TGF-ß1, suggesting that NET1 was involved in the pathological process of cardiac fibrosis. Overexpression of NET1 promoted ß-catenin expression in the nucleus and significantly increased the proliferation and migration of cardiac fibroblasts. NET1 may form a complex with ß-catenin through GSK3ß. Knockdown of ß-catenin alleviated the effects of NET1 overexpression on collagen production and cell migration. In the heart of NET1 knockout mice, NET1 knockout can reduce the expression of ß-catenin, α-SMA, and collagen content induced by MI. In conclusion, NET1 may regulate the activation of Wnt/ß-catenin and TGF/Smads signaling pathway, promote collagen synthesis in fibroblasts, and participate in cardiac fibrosis. Thus, NET1 may be a potential therapeutic target in cardiac fibrosis.

Endocytosis of Peptidase Inhibitor SerpinE2 promotes Myocardial Fibrosis through activating ERK1/2 and ß-catenin Signaling Pathways.

Cardiac fibrosis is one of the common pathological processes in many cardiovascular diseases characterized by excessive extracellular matrix deposition. SerpinE2 is a kind of protein that inhibits peptidase in extracellular matrix and up-regulated tremendously in mouse model of cardiac fibrosis induced by pressure-overloaded via transverse aortic constriction (TAC) surgery. However, its effect on cardiac fibroblasts (CFs), collagen secretion and the underlying mechanism remains unclear. In this study, DyLight® 488 green fluorescent dye or His-tagged proteins were used to label the exogenous serpinE2 protein. It was showed that extracellular serpinE2 translocated into CFs by low-density lipoprotein receptor-related protein 1 (LRP1) and urokinase plasminogen activator receptor (uPAR) of cell membrane through endocytosis. Knockdown of LRP1 or uPAR reduced the level of serpinE2 in CFs and down-regulated the collagen expression. Inhibition of the endocytosis of serpinE2 could inhibit ERK1/2 and ß-catenin signaling pathways and subsequently attenuated collagen secretion. Knockdown of serpinE2 attenuates cardiac fibrosis in TAC mouse. We conclude that serpinE2 could be translocated into cardiac fibroblasts due to endocytosis through directly interact with the membrane protein LRP1 and uPAR, and this process activated the ERK1/2, ß-catenin signaling pathways, consequently promoting collagen production.