Calpain inhibitor prevents atherosclerosis in apolipoprotein E knockout mice by regulating mRNA expression of genes related to cholesterol uptake and efflux

PPARs in atherosclerosis: The spatial and temporal features from mechanism to druggable targets

BACKGROUND

Atherosclerosis is a chronic and complex disease caused by lipid disorder, inflammation, and other factors. It is closely related to cardiovascular diseases, the chief cause of death globally. Peroxisome proliferator-activated receptors (PPARs) are valuable anti-atherosclerosis targets that showcase multiple roles at different pathological stages of atherosclerosis and for cell types at different tissue sites.

AIM OF REVIEW

Considering the spatial and temporal characteristics of the pathological evolution of atherosclerosis, the roles and pharmacological and clinical studies of PPARs were summarized systematically and updated under different pathological stages and in different vascular cells of atherosclerosis. Moreover, selective PPAR modulators and PPAR-pan agonists can exert their synergistic effects meanwhile reducing the side effects, thereby providing novel insight into future drug development for precise spatial-temporal therapeutic strategy of anti-atherosclerosis targeting PPARs.

KEY SCIENTIFIC

Concepts of Review: Based on the spatial and temporal characteristics of atherosclerosis, we have proposed the importance of stage- and cell type-dependent precision therapy. Initially, PPARs improve endothelial cells' dysfunction by inhibiting inflammation and oxidative stress and then regulate macrophages' lipid metabolism and polarization to improve fatty streak. Finally, PPARs reduce fibrous cap formation by suppressing the proliferation and migration of vascular smooth muscle cells (VSMCs). Therefore, research on the cell type-specific mechanisms of PPARs can provide the foundation for space-time drug treatment. Moreover, pharmacological studies have demonstrated that several drugs or compounds can exert their effects by the activation of PPARs. Selective PPAR modulators (that specifically activate gene subsets of PPARs) can exert tissue and cell-specific effects. Furthermore, the dual- or pan-PPAR agonist could perform a better role in balancing efficacy and side effects. Therefore, research on cells/tissue-specific activation of PPARs and PPAR-pan agonists can provide the basis for precision therapy and drug development of PPARs.

Deficiency of Calpain-1 attenuates atherosclerotic plaque and calcification and improves vasomotor dysfunction in Apolipoprotein E knockout mice through inhibiting inflammation

PURPOSE

Atherosclerosis (AS) and atherosclerotic calcification (AC) are closely related to the cardiovascular diseases, largely due to its induction of vasomotor dysfunction. We previously reported that Calpain-1 inhibitor attenuated AS and AC. The present study was designed to investigate the effects and potential mechanisms of Calpain-1 knockout (Calpain-1 KO) in Apolipoprotein E KO (ApoE KO) mice on AS, AC, aortic vasomotor function as well as the liver dysfunction.

METHODS

We hybridized ApoE KO mice with Calpain-1 KO mice to obtain ApoE/Calpain-1 double KO (A × C DKO) mice. The formation of AS and AC was evaluated and liver function was determined. Aortic vasomotor function was assessed. Contents of TNF-α, IL-6, IL-18, IL-1β and NO and the activity of AST, ALT, ALP and eNOS in serum were quantified. The mRNA expression of CD68, SR-A, CD36, PPAR-γ, LXR-α, ABCA1, BMP-2, OPN, ALP and Runx2 in aorta and/or liver were measured.

RESULTS

The results showed that in comparison to C57 mice, ApoE KO mice demonstrated the significant increases in the areas of AS and AC, the increases in the mRNA expression of CD68 in the aorta, the increases in the AST, ALT and ALP activity in serum. ApoE KO mice also showed the dysfunction of the aortic contraction induced by phenylephrine and of the relaxation induced by acetylcholine. However, compared with ApoE KO mice, A × C DKO mice exhibited the significant attenuation of AS and AC and the downregulation of mRNA expression of CD68 in aorta. A × C DKO mice revealed the reduction of AST, ALT and ALP activity in serum, the improvements in aortic contraction and relaxation as well as the increases in eNOS activity and NO content in serum. A × C DKO mice also showed the decreases in the contents of TNF-α, IL-6, IL-18 and IL-1β in serum. The mRNA expression of CD68 in aorta, SR-A and CD36 in both aorta and liver of A × C DKO mice was downregulated, while that of PPAR-γ, LXR-α, and ABCA1 was upregulated in comparison of ApoE KO mice. In addition, the mRNA expression of BMP-2, OPN, ALP and Runx2 in aorta of A × C DKO mice was downregulated in comparison of ApoE KO mice.

CONCLUSION

The results suggested that deficiency of Calpain-1 attenuated the formation of AS and AC and improved vasomotor and liver dysfunction in ApoE KO mice through anti-inflammation, and modulation of the mRNA expression of genes related to AS and AC.

Targeting PPARs for therapy of atherosclerosis: A review

Atherosclerosis, a chief pathogenic factor of cardiovascular disease, is associated with many factors including inflammation, dyslipidemia, and oxidative stress. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors and are widely expressed with tissue- and cell-specificity. They control multiple genes that are involved in lipid metabolism, inflammatory response, and redox homeostasis. Given the diverse biological functions of PPARs, they have been extensively studied since their discovery in 1990s. Although controversies exist, accumulating evidence have demonstrated that PPAR activation attenuates atherosclerosis. Recent advances are valuable for understanding the mechanisms of action of PPAR activation. This article reviews the recent findings, mainly from the year of 2018 to present, including endogenous molecules in regulation of PPARs, roles of PPARs in atherosclerosis by focusing on lipid metabolism, inflammation, and oxidative stress, and synthesized PPAR modulators. This article provides information valuable for researchers in the field of basic cardiovascular research, for pharmacologists that are interested in developing novel PPAR agonists and antagonists with lower side effects as well as for clinicians.