Molecular mechanism of aortic dissection induced by GPR35 / 解放军医学杂志

ABSTRACT

Objective To investigate the function of G-protein-coupled receptor 35 (GPR35) in aortic dissection (AD) and its mechanism. Methods Thirty wild-type (WT) male mice were randomly divided into the WT+Sham group and WT+AD group (15 each), and 15 GPR35 knockout mice (GPR35-/-) were set as GPR35-/-+AD group. Mice in WT+AD group and GPR35-/-+AD group were back-subcutaneously implanted with angiotensin II [4.5 mg/(kg·24 h)] by miniosmotic pump, while in WT+Sham group received equivalent saline. Mice were sacrificed and the aortas were removed on the 14th postoperative day for further experiments. The mice aortic vascular smooth muscle cell lines (MOVAS) were divided into control group, aortic dissection group (AD group), GPR35 inhibitor group (CID group). The expressions of GPR35 in aorta and MOVAS were determined by q-PCR and Western blotting. The aortas were stained with HE and VVG to detect the formation of aortic dissection and elastic fiber structure. The infiltration of monocyte macrophage (CD68 positive cell) and expression of inflammatory factors (IL)-6 and (TNF)-α in aorta were detected with immunohistochemistry and q-PCR. The apoptosis of aortic smooth muscle was measured by TUNEL staining and flow cytometer. Results Compared with the WT+Sham group, the expression of GPR35 mRNA increased by (1.88±0.07) times and of GPR35 protein increased by (1.34±0.05) times in WT+AD group (P<0.05), and similar results were obtained in cell model; Compared with the WT+AD group, the incidence of AD decreased obviously in GPR35-/-+AD group (53.3% vs. 13.3%, P<0.05), meanwhile the aortic dilatation, media thickness and elastic fiber structure were attenuated evidently; Furthermore, the mononuclear macrophage infiltration (CD68 positive cells) were elevated in WT+AD group than in WT+Sham group and GPR35-/-+ AD group [(32.8±1.1)% vs. (5.1±0.9)% vs. (16.0±1.1)%] with statistical significance (P<0.05). The expression levels of IL-6 and TNF-α mRNA were higher in WT+AD group (2.6±0.1, 1.8±0.1) than in WT+Sham group (both 1.00±0.06) and GPR35-/-+ AD group (1.6±0.1, 1.4±0.1) with statistical significance (P<0.05); The number of apoptotic aortic smooth muscle cells in WT+AD group [(24.0±0.7)%] was more than that in WT+Sham group and GPR35-/-+AD group [(6.6±0.5)% and (11.2±0.9)%] with statistical significance (P<0.05). Meanwhile, the apoptosis rate of MOVAS was also significantly higher in AD group [(11.6±0.5)%] than in control group and CID group [(4.7±0.4)% and (7.6±0.4)%, P<0.05]. Conclusion Inhibition of GPR35 can protect aortic dissection by preventing aortic inflammation and smooth muscle apoptosis.