PERK Pathway Mediates The Ameliorative Effect Of Hydrogen Sulfide On Vascular Calcification

Objective:We aimed to confirm the regulatory role of hydrogen sulfide（H₂S）in the calcification of vascular PERK pathway and the effect of inhibition of PERK pathway on vascular calcification（VC）.Methods:Intramuscular injection of vitamin D3 combined with gavage of nicotine to establish rat vascular calcification model.Arterial blood pressure was measured by carotid artery catheterization;HE and alizarin red staining was performed on aortic sections;calcium content in aortic arch was measured;alkaline phosphatase activity in aortic arch and plasma was detected;expression levels of related proteins were detected by Western blot,including the phenotypic markers of the cells（RUNX2 and BMP2）,the contractile phenotypic marker proteins（SM22αand calponin-1）,the endoplasmic reticulum stress（ERS）marker proteins（CHOP and GRP78）,PERK,phosphorylated PERK,IRE-1 and ATF-6.Results:Compared with the control rats,the calcium content of the aorta,plasma ALP activity and carotid blood pressure were significantly increased in the vascular calcification group.HE staining and Alizarin red staining show that the thoracic aortic medial structure is disordered and the elastic plate is thickened.The expression levels of SM22a and calponin-1 in the aortic tissue were significantly reduced,while RUNX2 and BMP2 expression levels were significantly elevated.Intraperitoneal injection of Na HS（56μmol/kg）in the rats with vascular calcification significantly improved the above parameters.In addition,the expression levels of the ERS-related proteins CHOP and GRP78 in the vascular tissue of the vascular calcification group were significantly up-regulated,and NaHS significantly inhibited the up-regulation of ERS-related proteins,such as up-regulation of PERK expression,down-regulated the expression of IRE-1 and ATF-6.The PERK signaling pathway inhibitor ISRIB（0.25 mg/kg/week）had a similar improvement effect on vascular calcification with NaHS,including decrease of rat aortic calcium content,plasma ALP activity,improves the disorder of thoracic aortic medial structures and thickening of elastic plates.At the same time,the expressions of SM22α,RUNX2 and GRP78 were up-regulated,the expressions of calponin-1,BMP2 and CHOP were down-regulated,and the expression of p-PERK/PERK of endoplasmic reticulum stress PERK signaling pathway was down-regulated.Conclusions:PERK signaling pathway may mediate the role of hydrogen sulfide in inhibiting endoplasmic reticμLum stress to improve vascular calcification.PERK might be the new target for the therapy of vascular calcification.