Berberine inhibits osteogenic differentiation of aortic valve interstitial cells by interfering Smad1/5/8 and NF-κB pathways.

AIMS: Calcified aortic valve disease (CAVD) is a cardiovascular disease with increasing morbidity and mortality. The pathogenetic cellular mechanism is the phenotypic transition of aortic valve interstitial cells (VICs). Here, we explored the effect of berberine (BBR) on the phenotypic transition of VICs and elucidated the underlying molecular mechanisms, providing a theoretical basis in finding novel clinical treatments for CAVD. METHODS AND RESULTS: Calcific aortic valves and normal controls were collected for western blot and the results demonstrated that osteogenic and inflammatory markers were significantly up-regulated in calcific aortic valves. BBR inhibited inflammation and osteogenic differentiation of VICs under osteogenic conditions, as well as alkaline phosphatase activity and calcified nodule formation. Mechanistically, BBR could inhibit the activation of Smad1/5/8 and NF-κB pathways under OM conditions. LDN193189 and BAY11-7082, the inhibitor of Smad1/5/8 and NF-κB respectively, were added for further verification. Similarly, the osteogenic and fibrotic markers of VICs induced by osteogenic induction medium were decreased by LDN193189 and BAY11-7082. Western blot was used to examine upstream receptors of Smad1/5/8, the results showed that BBR inhibited the activation of Smad1/5/8 by downregulating ALK2 and ALK3. CONCLUSION: BBR decreased the inflammatory factors and suppressed the osteogenic differentiation of VICs, which might be associated with the inhibition of Smad1/5/8 and NF-κB signaling pathways.

Characterization of a Type VI Secretion System vgrG2 Gene in the Pathogenicity of Burkholderia thailandensis BPM.

Burkholderia thailandensis is a clinically underestimated conditional pathogen in the genus Burkholderia, the pathogenicity of the infection caused by B. thailandensis remains poorly understood. According to previous studies, Type-VI secretion system (T6SS) is a protein secreting device widely existing in Gram-negative bacilli. Valine-glycine repeat protein G (VgrG) is not only an important component of T6SS, but also a virulence factor of many Gram-negative bacilli. In one of our previous studies, a unique T6SS vgrG gene (vgrG2 gene) was present in a virulent B. thailandensis strain BPM (BPM), but not in the relatively avirulent B. thailandensis strain E264 (E264). Meanwhile, transcriptome analysis of BPM and E264 showed that the vgrG2 gene was strongly expressed in BPM, but not in E264. Therefore, we identified the function of the vgrG2 gene by constructing the mutant and complemented strains in this study. In vitro, the vgrG2 gene was observed to be involved in the interactions with host cells. The animal model experiment showed that the deletion of vgrG2 gene significantly led to the decrease in the lethality of BPM and impaired its ability to trigger host immune response. In conclusion, our study provides a new perspective for studying the pathogenicity of B. thailandensis and lays the foundation for discovering the potential T6SS effectors.