Excessive production of reactive oxygen species (ROS) and P2X7R activation induced by high glucose increases NLRP3 inflammasome activation, which contributes to the pathogenesis of diabetic cardiomyopathy. Although H3 relaxin has been shown to inhibit cardiac fibrosis induced by isoproterenol, the mechanism has not been well studied. Here, we demonstrated that high glucose (HG) induced the collagen synthesis by activation of the NLRP3 inflammasome, leading to caspase‐1 activation, interleukin‐1β (IL‐1β) and IL‐18 secretion in neonatal rat cardiac fibroblasts. Moreover, we used a high‐glucose model with neonatal rat cardiac fibroblasts and showed that the activation of ROS and P2X7R was augmented and that ROS‐ and P2X7R‐mediated NLRP3 inflammasome activation was critical for the collagen synthesis. Inhibition of ROS and P2X7R decreased NLRP3 inflammasome‐mediated collagen synthesis, similar to the effects of H3 relaxin. Furthermore, H3 relaxin reduced the collagen synthesis via ROS‐ and P2X7R‐mediated NLRP3 inflammasome activation in response to HG. These results provide a mechanism by which H3 relaxin alleviates NLRP3 inflammasome‐mediated collagen synthesis through the inhibition of ROS and P2X7R under HG conditions and suggest that H3 relaxin represents a potential drug for alleviating cardiac fibrosis in diabetic cardiomyopathy.

Increased vascular smooth muscle cell (VSMC) proliferation substantially contributes to the pathogenesis of atherosclerosis and intimal hyperplasia after vascular injury. The importance of inflammation in VSMC proliferation is now being recognized. Preventing the inflammatory response is one therapeutic strategy that can be used to inhibit atherosclerosis in the clinic. The present study, using RNA interference and gene transfer techniques, was conducted to investigate the effect of monocyte chemotactic protein-3 (MCP-3) on VSMC proliferation that is a result of TNF-α stimulation, and whether overexpression of the tissue factor pathway inhibitor (TFPI) gene could prevent VSMC proliferation by blocking the MCP-3/CC chemokine receptor 2 (CCR2) pathway. Mouse VSMCs were infected in vitro with recombinant adenoviruses containing either mouse MCP-3-shRNA (Ad-MCP-3-shRNA), the TFPI gene (Ad-TFPI), or the negative control, which was shRNA encoding the sequence for EGFP (Ad-EGFP) or DMEM only. The cells were then stimulated with TNF-α for different time periods on the third day after gene transfer. The data show that VSMC proliferation in the Ad-MCP-3-shRNA and Ad-TFPI groups was markedly decreased using BrdU ELISA and MTT assays; MCP-3-shRNA and TFPI inhibited the expression of MCP-3 and CCR2 after long-term stimulation and inhibited the phosphorylation of ERK1/2 and AKT after short-term stimulation, as shown by ELISA and western blot analysis. This study provides convincing evidence that clarifies the effect of the proinflammatory factor MCP-3 in promoting VSMC proliferation. Our data also show, for the first time, that TFPI has an anti-proliferative role in TNF-α stimulated-VSMCs at least partly by interfering with the MCP-3/CCR2 pathway and then via suppression of the ERK1/2 and PI3K/AKT signaling pathways. We conclude that TFPI gene transfer may be a safe and effective therapeutic tool for treating atherosclerosis and intimal hyperplasia. Increased vascular smooth muscle cell (VSMC) proliferation substantially contributes to the pathogenesis of atherosclerosis and intimal hyperplasia after vascular injury. 1-3 A preponderance of evidence from clinical and experimental studies supports the notion that inflammation has important roles in a wide range of cardiovascular diseases, such as atherosclerosis and intimal hyperplasia, as well as cell proliferation. 4,5 Current evidence has demonstrated that chemokines, which belong to proinflammatory factors, have a pivotal role in VSMC proliferation. Inhibition of chemokine activity is a possible therapeutic strategy for vascular proliferative disorders. 6 Monocyte chemotactic protein-3 (MCP-3), also known as CCL7, belongs to the MCP subfamily of the CC chemokines, which also includes MCP-1/CCL2. 7 MCP-1 is present in atherosclerotic lesions and it is crucial for the development of atherosclerotic plaques. 8 However, compared with MCP-1, little is known about the role of MCP-3 in vascular pathologies such as atherosclerosis and restenosis. A recent study revealed that MCP-3-...

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