ABSTRACT:Objective To observe whether N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP)can inhibit rat silicotic fibrosis by regulating stimulatory G proteinα(Gαs)/inhibitory G proteinα(Gαi)signal.Methods Male Wistar rats were randomly divided into three groups (n=1 0 ):control 1 6-w group,silicosis 1 6-w group,and Ac-SDKP pre-treatment group.The pathological changes of the lung tissue was observed by HE staining;the expressions ofα-smooth muscle actin (α-SMA),Collagen Ⅰ,fibronectin (Fn),Gαs,Gαi2 ,Gαi3 and cAMP were detected by Western blot.Immunofluorescence was performed on lung tissue sections to detect the coexpression ofα-SMA/Gαi3 . Results Within silicosis 16-w group,HE staining showed that the silicotic nodule volume increased,nodule fusion and the formation of interstitial fibrosis could be seen,and cell fibrous nodules were visible.Immunofluorescence staining showed the enhanced coexpression ofα-SMA/Gαi3 in fibrosis area.Compared with those in control group, the expressions ofα-SMA,Collagen Ⅰ,Fn,Gαi2 and Gαi3 significantly increased in silicosis 1 6-w group,but the expressions of Gαs and cAMP decreased.Compared with silicosis 1 6-w group,Ac-SDKP pre-treatment group had alleviated lung injury and decreased coexpression ofα-SMA/Gαi3 .The expressions ofα-SMA,Collagen Ⅰ,Fn,Gαi2 and Gαi3 protein significantly decreased in Ac-SDKP pre-treatment group,while the expressions of Gαs and cAMP increased obviously.Conclusion Ac-SDKP can regulate the expressions of Gαs and Gαi and promote the formation of cAMP,thus playing an effective role against silicotic fibrosis.

OBJECTIVE: observe the changes of localization and expression of acetylated tubulin alpha( Ac-tubulin α) in fibroblasts of silicosis fibrosis. METHODS: i) A total of 22 autopsy case with coal workers' pneumoconiosis( CWP) was selected as CWP group( autopsy lesion lung tissue) and their adjacent normal lung tissues surrounding fibrotic regions were selected as the control group using typical sampling method. ii) Specific pathogens free healthy male rats were randomly divided into control group and 5 dust-exposed groups with 10 rats in each group. In dust-exposed group,the rats were exposed to 2 000 mg/m~3 of silica dust for 0,2,4,8,12 and 16 weeks respectively by dynamic inhalation. The rats in control group were given no treatment. iii) Primary cultured rat lung fibroblasts were induced by Ang Ⅱ at a concentration of 100 nmol/L at different time points( 0,5,15 and 30 min,1,3,6,12,24 and 48 hours). iv) The expression of Ac-tubulin α and α-smooth muscle actin( α-SMA) were detected by immunohistochemical staining. The expression of Ac-tubulinα/Vimentin and Ac-tubulin α/α-SMA were observed by immunofluorescence staining. The relative expression ofα-SMA and Ac-tubulin α protein was detected by Western blot. RESULTS: The positive expression of Ac-tubulin α in lung tissue of CWP group was down-regulated while that of α-SMA was up-regulated compared with the control group( P < 0. 01). Immunofluorescence results showed that Vimentin positive expression in the CWP group was significantly increased in the lesion fibrosis area,while Ac-tubulin α expression was absent. The co-expression of Ac-tubulin α and Vimentin was detected in normal lung tissue of control group. The animal experiment results showed that the expression of Ac-tubulin αin lung tissue of rats was down-regulated and that of α-SMA was up-regulated with the prolongation of dust exposure time( P < 0. 01). The Ang Ⅱ induced the differentiation of fibroblasts into myofibroblasts,and the expression of Ac-tubulin α in fibroblasts gradually decreased and the expression of α-SMA gradually increased with the prolongation of Ang Ⅱ induction time( P < 0. 05). CONCLUSION: The lack of expression of Ac-tubulin α may be involved in the occurrence and development of silicotic fibrosis.