Blebbistatin ameliorates pneumonic injury after high common bile duct ligation in rats

To investigate the protective effect of blebbistatin, a non-muscle myosin Ⅱ (NMⅡ) inhibitor, on inflammatory injury of lung tissue after chronic common bile duct ligation (CBDL) in rats.

A total of 55 SPF male SD rats (200~220 g) were randomly divided into 3 groups, namely control group (Sham, n=11), high CBDL group (model group, n=22) and blebbistatin treatment after high CBDL group (treatment group, n=22). The treatment group was intraperitoneally injected with blebbistatin at a dose of 5 mg/kg once a day for a week, while the model group was only given the solvent (PEG-300∶saline=1∶1). The changes of lung tissue were observed with HE staining. Western blotting was performed to detect the expression of myeloperoxidase (MPO), IL-6, TNF-α, and superoxide dismutase (SOD3) in the lung tissues. The expression levels of MPO, IL-6, IL-1β, TNF-α, LY6B, CD163, and vascular endothelium related factor CD31 were also determined by immunohistochemical assay.

The lung injury at the 3rd week after CBDL presented a large number of inflammatory cells infiltration, accompanied by local alveolar space and pulmonary interstitial hemorrhage. Immunohistochemical results demonstrated that the numbers of MPO positive cells, LY6B positive cells and CD163 positive cells were all increased significantly in the model group as compared with the Sham group (P<0.01), with enhanced expression of IL-1β and TNF-α (P<0.01). Western blotting results confirmed the up-regulated levels of MPO, IL-6 and SOD3 in the model group than the sham group (P<0.05). In comparison with the model group, the treatment group showed decreased numbers of MPO positive cells, LY6B positive cells, and CD163 positive cells (P<0.01), and declined levels of inflammatory factors IL-1β, IL-6, and TNF-α (P<0.01). Western blotting indicated as well that the expression of MPO, IL-6 and TNF-α in the treatment group was reduced greatly (P<0.05). Moreover, at the 5th week after surgery, the lung injury mainly manifested as pulmonary microvascular dilation, which was more severe in the model group than the Sham group (P<0.01), while the severity of pulmonary microvascular dilatation was remarkably milder after treatment (P<0.01).

Blebbistatin can effectively inhibit the infiltration of inflammatory cells in lung tissue, reduce pneumonia injury and alleviate pulmonary microvascular dilatation after CBDL.