ABSTRACT
BACKGROUND: Previous studies have found that matrine (MAT) effectively treated Ulcerative Colitis (UC). The purpose of this study is to explore its mechanism based on the HMGB1/NLRP3/Caspase-1 signaling pathway. METHODS: MAT was administered intragastrically to DSS-induced UC mice for 14 days. The Disease Activity Index (DAI) and histological staining were measured to detect histopathological changes in colon. The levels of IL-1ß, IL-6, and TNF-α in serum were measured by ELISA. The protein and mRNA expression of HMGB1/NLRP3/Caspase-1 in the colon were detected by immunohistochemistry, western Blotting or qRT-PCR. RESULTS: MAT improved the histological pathological changes of UC mice, as assessed by DAI, colonic length, and colonic mucosal injury. MAT also reduced colonic inflammatory damage by reducing the serum IL-1ß, IL-6, and TNF-α content and decreasing the expression of HMGB1, NLRP3, Caspase-1, and IL-1ß and proteins and mRNA in the colon. CONCLUSION: MAT could significantly alleviate DSS-induced UC symptoms by reducing the expressions of pro-inflammatory cytokines, such as IL-1ß, TNF-α, and IL-6, the mechanism of which is related to the inhibition of HMGB1/NLRP3/Caspase-1 signaling pathway.
ABSTRACT
Background Ventricular tachyarrhythmias are often preceded by short sequences of premature ventricular complexes. In a previous study, a restitution-based computational model predicted which sequences of stimulated premature complexes were most likely to induce ventricular fibrillation in canines in vivo. However, the underlying mechanism, based on discordant-alternans dynamics, could not be verified in that study. The current study seeks to elucidate the mechanism by determining whether the spatiotemporal evolution of action potentials and initiation of ventricular fibrillation in in vitro experiments are consistent with model predictions. Methods and Results Optical mapping voltage signals from canine right-ventricular tissue (n=9) were obtained simultaneously from the entire epicardium and endocardium during and after premature stimulus sequences. Model predictions of action potential propagation along a 1-dimensional cable were developed using action potential duration versus diastolic interval data. The model predicted sign-change patterns in action potential duration and diastolic interval spatial gradients with posterior probabilities of 91.1%, and 82.1%, respectively. The model predicted conduction block with 64% sensitivity and 100% specificity. A generalized estimating equation logistic-regression approach showed that model-prediction effects were significant for both conduction block ( P<1×10-15, coefficient 44.36) and sustained ventricular fibrillation ( P=0.0046, coefficient, 1.63) events. Conclusions The observed sign-change patterns favored discordant alternans, and the model successfully identified sequences of premature stimuli that induced conduction block. This suggests that the relatively simple discordant-alternans-based process that led to block in the model may often be responsible for ventricular fibrillation onset when preceded by premature beats. These observations may aid in developing improved methods for anticipating block and ventricular fibrillation.
