[Effects of fasudil on the expression of Rho kinase-1 and airway inflammation in a mouse model of asthma.].

OBJECTIVE: To explore the role of Rho kinase-1 (ROCK-1) in airway inflammation of asthma by observing the effects of fasudil, a specific inhibitor of ROCK-1, on the expression of Rho kinase-1 and airway inflammation in a mouse model of asthma.

METHODS: Twenty-four female BALB/c mice were randomly divided into 3 groups (n = 8 each): a control group, an asthmatic group and a treatment group. Mice in the asthmatic and the treatment groups were sensitized by intraperitoneal injection of OVA (25 microg) precipitated with 1 mg of alum in 200 microl of saline on days 1 and 15, and subsequently challenged by nebulization of 2% OVA on days 22-26. Mice in the control group were sensitized with Al(OH)3 saline and challenged with saline instead of OVA. Mice of the treatment group were injected intraperitoneally with fasudil (10 mg/kg) 1 h before each OVA challenge. All the mice were killed 24 h after the final challenge, and bronchoalveolar lavage fluid (BALF) was collected for counting total inflammatory cells and eosinophils (EOS). Cytokines and chemokines in BALF were measured by ELISA. The lung tissue slides were examined histologically. The protein and mRNA expression of ROCK-1 were measured by immunohistochemistry and RT-PCR respectively.

RESULTS: (1) OVA challenge in mice of the asthmatic group caused a marked increase in the number of the total cells and eosinophils in BALF (q = 25.909, 35.002, respectively, all P < 0.01). When fasudil was applied, both the total cell counts and the eosinophil numbers were significantly decreased. The total cell number was decreased from (1.45 +/- 0.12) x 10(9)/L to (0.89 +/- 0.09) x 10(9)/L (q = 16.676, P < 0.01), and the number of eosinophils was decreased from (0.52 +/- 0.06) x 10(9)/L to (0.20 +/- 0.04) x 10(9)/L (q = 21.537, P < 0.01). (2) Compared with the control group, OVA challenge in mice of the asthmatic group induced eotaxin, IL-5 and IL-13 release into BALF (q = 18.246, 23.009, 25.826, respectively, all P < 0.01). The eotaxin, IL-5 and IL-13 levels in BALF after OVA challenge were (45 +/- 8) ng/L, (157 +/- 23) ng/L and (429 +/- 46) ng/L, respectively. Application of fasudil resulted in inhibition of the augmented levels of eotaxin, IL-5 and IL-13 in BALF, decreased to (20 +/- 5) ng/L, (57 +/- 14) ng/L and (254 +/- 28) ng/L, respectively (q = 13.119, 17.503, 8.449, respectively, all P < 0.01). (3) Mice in the control group showed no detectable inflammatory response in the lung, whereas OVA-challenged mice induced infiltration of inflammatory cells around airways and blood vessels. The majority of the infiltrated inflammatory cells were eosinophils. Application of fasudil significantly reduced the infiltration of inflammatory cells in the peribronchial areas compared with the asthmatic mice. (4) The expression levels of ROCK-1 mRNA and protein in mice of the asthmatic group (0.67 +/- 0.05 and 1.09 +/- 0.06) were much higher than those of the control group (0.26 +/- 0.05 and 0.87 +/- 0.09) (q = 25.614, 8.156, all P < 0.01). When fasudil was administered, the expression levels of ROCK-1 mRNA and protein were significantly attenuated to 0.35 +/- 0.04 and 0.98 +/- 0.08, compared with those of the asthmatic group (q = 20.379, 4.135, all P < 0.01). (5) The expression level of ROCK-1 mRNA was positively correlated with the number of eosinophils and the levels of eotaxin, IL-5 and IL-13 in BALF (r = 0.709, 0.600, 0.613, 0.650, all P < 0.01).

CONCLUSION: Airway inflammation of bronchial asthma was improved by inhibiting expression and activity of ROCK-1 by fasudil, suggesting that ROCK-1 may be involved in asthmatic airway inflammation induced by OVA challenge.