Atorvastatin Prevents Myocardial Fibrosis in Spontaneous Hypertension via Interleukin-6 (IL-6)/Signal Transducer and Activator of Transcription 3 (STAT3)/Endothelin-1 (ET-1) Pathway.

BACKGROUND Hypertension is a leading global disease, and myocardial fibrosis is an important adverse effect of hypertension, seriously threatening human health. The IL-6/STAT3 pathway and endothelin-1 (ET-1) were previously suggested to play a part in myocardial fibrosis. MATERIAL AND METHODS To investigate the role of Atorvastatin (Ato) in spontaneous hypertension, systolic blood pressure (SBP) and left ventricular mass index (LVMI) were measured, and Masson trichrome staining was performed. Furthermore, the relative protein levels of the IL-6/STAT3/ET-1 pathway were tested. RESULTS Ato prevented myocardial fibrosis in spontaneous hypertension rats, especially at the dosage of 50 mg/kg/d. The IL-6/STAT3 pathway was observed to be suppressed by Ato, and ET-1 level in myocardial tissues was also downregulated by Ato. The phosphorylation status of STAT3 was tested after Ato treatment, showing that Ato mainly stimulated the tyr-705 phosphorylation of STAT3. CONCLUSIONS Results of this study may help promote myocardial fibrosis therapy and provide insights into the IL-6/STAT3/ET-1-mediated mechanism in Ato-induced myocardial fibrosis inhibition.

Ectopic trypsin in the myocardium promotes dilated cardiomyopathy after influenza A virus infection.

We have previously reported that ectopic trypsin in the myocardium triggers acute myocarditis after influenza A virus (IAV) infection. As myocarditis is a common precursor to dilated cardiomyopathy (DCM), the aim of the present study was to investigate the influence of trypsin on the progression of DCM after IAV infection. IAV-infected mice treated with saline or trypsin inhibitor were euthanized on days 0, 9, 20, 40 and 60 postinfection. Trypsin expression colocalized with myocardial inflammatory loci and IAV-induced myocarditis peaked on day 9 postinfection and alleviated by day 20 but persisted until day 60 postinfection, even though replication of IAV was not detected from day 20 postinfection. Similar time courses were observed for the activation of pro-matrix metalloproteinase (pro-MMP)-9 and expression of the proinflammatory cytokines IL-6, IL-1ß, and TNF-α. Degradation of collagen type I, proliferation of ventricular interstitial collagen, and expression of collagen type I and III mRNA increased significantly during acute and chronic phases; collagen type III mRNA increased more significantly than collagen type I mRNA. Cardiac function progressively deteriorated with progressive left ventricular dilation. The trypsin inhibitor aprotinin suppressed pro-MMP-9 activation and cytokine release, alleviated myocardial inflammation, and restored collagen metabolism during acute and chronic phases of myocarditis. This effectively prevented ventricular dilation and improved cardiac function. These results suggest that ectopic trypsin in the myocardium promoted DCM through chronic activation of pro-MMP-9, persistent induction of cytokines, and mediation of collagen remodeling. Pharmacological inhibition of trypsin activity might be a promising approach for the prevention of viral cardiomyopathy.