Serpina3c deficiency aggravates vascular dysfunction and VSMC dysregulation through regulating adamts4 pathway activity in obese mice
Authors: Wu Y , Yao Y Y 
Published: October 2024

Abstract

Background
Obesity leads to arterial stiffness (AS), which is an independent risk factor for cardiovascular disease. Vascular smooth muscle cell (VSMC) dysfunction is a critical step in the development of AS. Adamts4 (a disintegrin and metalloproteinase with thrombospondin motifs 4) promoting the ECM remodeling can regulate VSMC differentiation. Serpina3c is a serine protease inhibitor that plays a key role in VSMC proliferation and metabolic diseases.

Purpose
The present study aimed to investigate the function of Serpina3c in high-fat diet (HFD)-induced AS and regulation of VSMC phenotypic switching and possible mechanisms.

Methods
8-week-old male Serpina3c-/- and C57BL/6 mice were fed normal diet (ND) or HFD for 12 weeks. The adipocyte-specific Serpina3c overexpression (AAV8-Serpina3c) were constructed and injected in situ into visceral or perivascular adipose tissue (AT) of Serpina3c-/- mice fed a 12-week HFD to test in vivo effect of AT-derived Serpina3c on arterial stiffness. In vivo vascular stiffness was analyzed by obtaining pulse wave velocity (PWV) measurements. Aortic rings were dissected to assess the ex-vivo effects of Serpina3c deprivation on vascular contractile and diastolic function. Elastin van Gieson (EVG) and Hematoxylin-eosin (H&E) staining were implemented to observe the pathological morphology of aortas. IP-Western analysis was performed for identifying Serpina3c-adamts4 interactions.

Results
The obese WT mice exhibited significantly increased PWV values, compared with ND-fed mice, which were further increased in HFD+Serpina3c-/- mice (Fig. 1A). Phenylephrine-induced vascular constriction was impaired in HFD fed mice and further deteriorated with Serpina3c deficiency (Fig. 1B). No differences were noted in the endothelial-dependent acetylcholine-mediated relaxation in HFD-fed mice. Notably, Serpina3c-/- mice exhibited poorer endothelium-independent sodium nitroprusside induced relaxation (Fig. 1C and D). The HFD+Serpina3c-/- mice showed an increased breakage of elastin fibres and medial thickness compared with the aortas of HFD+WT mice (Fig. 1E and F). Serpina3c deprivation aggravated collagen deposition and matrix metalloproteinases (MMPs, MMP2 and MMP9) accumulation. VSMC contractile gene α smooth muscle actin were upregulated and synthetic phenotype marker osteopontin were downregulated in HFD+WT mice. The effect was more pronounced in aortas with Serpina3c deficiency (Fig. 1G and H). Overexpression of serpina3c in both visceral and perivascular AT or adamts4 deprivation reversed the above phenotypes. Computer simulations and IP-Western results indicate that Serpina3c and adamts4 bind to and maintain the latter low-expression in response to obesity (Fig. 2).

Conclusion
Serpina3c interacts with adamts4 to maintain contractile phenotype of VSMC and suppress AS development in the context of nutrient excess. Serpina3c is a novel target for the prevention and treatment of obesity associated artery disease.Serpina3c maintains vascular functionSerpina3c interacts with adamts4