Leukocyte Calpain Deficiency Reduces Angiotensin II–Induced Inflammation and Atherosclerosis But Not Abdominal Aortic Aneurysms in Mice

Abstract

Objective Angiotensin II (AngII)-infusion profoundly increases activity of calpains, calcium-dependent neutral cysteine proteases, in mice. Pharmacological inhibition of calpains attenuates AngII-induced aortic medial macrophage accumulation, atherosclerosis, and abdominal aortic aneurysm in mice. However, the precise functional contribution of leukocyte-derived calpains in AngII-induced vascular pathologies has not been determined. The purpose of this study was to determine whether calpains expressed in bone marrow (BM)-derived cells contribute to AngII-induced atherosclerosis and aortic aneurysms in hypercholesterolemic mice. Approach and Results To study whether leukocyte calpains contributed to AngII-induced aortic pathologies, irradiated male LDL receptor −/− mice were repopulated with BM-derived cells that were either wild-type(WT) or overexpressed calpastatin (CAST), the endogenous inhibitor of calpains. Mice were fed a fat-enriched diet and infused with AngII (1,000 ng/kg/min) for 4 weeks. Overexpression of CAST in BM-derived cells significantly attenuated AngII-induced atherosclerotic lesion formation in aortic arches, but had no effect on aneurysm formation. Using either BM-derived cells from calpain-1 deficient mice or mice with leukocyte-specific calpain-2 deficiency generated using cre-loxP recombination technology, further studies demonstrated that independent deficiency of either calpain-1 or -2 in leukocytes modestly attenuated AngII-induced atherosclerosis. CAST overexpression significantly attenuated AngII-induced inflammatory responses in macrophages and spleen. Furthermore, calpain inhibition suppressed migration and adhesion of macrophages to endothelial cells in vitro. Calpain inhibition also significantly decreased hypercholesterolemia-induced atherosclerosis in the absence of AngII. Conclusions The present study demonstrates a pivotal role for BM-derived calpains in mediating AngII-induced atherosclerosis by influencing macrophage function.

Calpain inhibitor I attenuates atherosclerosis and inflammation in atherosclerotic rats through eNOS/NO/NF-κB pathway

“…Accumulative studies reported that the increase in production of endothelial NO protected animals against atherosclerosis (De Caterina et al 1995;Momi et al 2012;Zeiher et al 1995). Regarding the roles of calpain-1 and calpain-2 in the formation of atherosclerosis, both calpain-1 and calpain-2 are reportedly expressed in macrophages in angiotensin II-infused athero-prone aorta, and are associated with their inflammatory responses (Howatt et al 2016). In addition, calpain-2 appears to be upregulated in vascular endothelium during atherogenesis, and is contributed to endothelial barrier dysfunction (Miyazaki et al 2011).…”

Emerging roles of calpain proteolytic systems in macrophage cholesterol handling

“…Subramanian et al also showed that atherosclerotic lesion progression in angiotensin II-infused Ldlr -/-mice is impaired by the calpain inhibitor BDA-410 [50]. Transgenic overexpression of calpastatin appears to significantly attenuate angiotensin IIor hypercholesterolemia-induced atherosclerotic development in Ldlr -/-mice, while abdominal aneurysmal formation was unchanged [51]. In mice, either myeloid calpain-1 or leukocyte calpain-2 are involved in angiotensin II-induced atherosclerosis [51].…”

“…Transgenic overexpression of calpastatin appears to significantly attenuate angiotensin IIor hypercholesterolemia-induced atherosclerotic development in Ldlr -/-mice, while abdominal aneurysmal formation was unchanged [51]. In mice, either myeloid calpain-1 or leukocyte calpain-2 are involved in angiotensin II-induced atherosclerosis [51]. Thus, it is likely that conventional calpains are involved in pro-atherogenic regulation of EC and leukocytes.…”

Recent Advances in the Genetics of Atherothrombotic Disease and Its Determinants

“…93 Furthermore, compared with nonmanipulated Ldlr-null mice, atherosclerosis was increased with concurrent deficiency of the sheddase, a disintegrin and metalloproteinase 17, 94 96 and also decreased (together with decreased aortic aneurysm development) in mice with leukocyte-specific calpain 2 deficiency. 97 Newer genetically manipulated mouse models have also contributed valuable pieces of information to the overall puzzle of atherosclerosis. For instance, high expression levels of telomerase reverse transcriptase in mice induce atherosclerosis-like smooth muscle cell morphology, whereas deletion of TERT decreases neointima formation through epigenetic regulation of proliferative gene expression.…”