The role and mechanism of 1,25-dihydroxyvitamin D(3) in regulating the Rho-kinase signaling pathway in asthmatic rats.

BACKGROUND: Bronchial asthma (referred to as asthma in the present study) is the most common chronic airway inflammatory disease in childhood. The present study aimed to investigate the effect of 1,25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)] on VDR expression, which is closely associated with asthmatic airway smooth muscle cells (ASMCs), and explored its role and mechanism in the Rho-kinase signaling pathway. METHODS: The acute asthma model was induced by ovalbumin (OVA) and pertussis bacillus, and ASMCs obtained from asthmatic rats were cultured in vitro. These cells were randomly divided into five groups: control (N) group, TNF-α (TNF) group, 1,25-(OH)(2)D(3) (VD) group, dexamethasone (DXM) group, and 1,25-(OH)(2)D(3) + DXM (L) group. The protein expression levels of VDR, ROCK, MLC20 and P-MLC20 were detected by western blot, and the mRNA expression levels of VDR, ROCK, MLC20 and P-MLC20 were detected by real-time quantitative PCR. RESULTS: The expression of ROCK, MLC20 and P-MLC20 in each treatment group were significantly lower, when compared to the TNF group (P<0.05), but this remained stronger than (P<0.05) or similar to (P>0.05) that in the N group. CONCLUSIONS: The regulation mechanism of 1,25-(OH)(2)D(3) in alleviating asthma should be correlated to its regulation of the expression of related signaling molecules in the Rho-kinase signaling pathway, and this effect may be achieved by regulating the mRNA and protein expression of the VDR gene.