Hyperlipidaemia and IFNgamma/TNFalpha Synergism are associated with cholesterol crystal formation in Endothelial cells partly through modulation of Lysosomal pH and Cholesterol homeostasis

Abstract

Background Inflammation plays an important role in the development of cardiovascular disease (CVD). Patients with chronic inflammation diseases have high levels of inflammation and early fatal myocardial infarction due to early, unstable coronary plaques. Cholesterol crystals (CC) play a key role in atherogenesis. However, the underlying mechanisms of endothelial cell (EC)-derived CC formation are not well understood in chronic inflammation. Methods We utilized a combination of a mouse psoriasis model ( K14-Rac1V12 mouse model) and human psoriasis patients to study the effect of inflammatory cytokines on CC formation in ECs. Lysosomal pH, alterations in lipid load and inflammatory proteins were evaluated as potential mechanisms linking inflammatory cytokines to CC formation. Coronary CT angiography was performed (n = 224) to characterize potential IFNγ and TNFα synergism on vascular diseases in vivo . Findings We detected CC presence in the aorta of K14-Rac1V12 mice on chow diet. IFNγ and TNFα were found to synergistically increase LDL-induced CC formation by almost 2-fold. There was an increase in lysosomal pH accompanied by a 28% loss in pH-dependent lysosomal signal and altered vATPaseV1E1 expression patterns. In parallel, we found that LDL+IFNγ/TNFα treatments increased free cholesterol content within EC and led to a decrease in SOAT-1 expression, an enzyme critically involved cholesterol homeostasis. Finally, the product of IFNγ and TNFα positively associated with early non-calcified coronary burden in patients with psoriasis (n = 224; β = 0.28, p < 0.001). Interpretation Our results provide evidence that IFNγ and TNFα accelerate CC formation in endothelial cells in part by altering lysosomal pH and free cholesterol load. These changes promote early atherogenesis and contribute to understanding the burden of CVD in psoriasis. Funding Funding was provided by the Intramural Research Program at NIH (NNM) and the National Psoriasis Foundation (NNM and YB).

Cholesterol crystals use complement to increase NLRP3 signaling pathways in coronary and carotid atherosclerosis

“…Herein we show that CC induced marked IL-1α release in carotid plaques in the presence of C5a, while TNF and C5a priming increased IL-1α release in presence of CC in PBMC from ACS patients and controls. Baumer et al recently suggested that TNF may also play an earlier role in CC formation [32] . We observed that neutrophils were present in lesions and these cells are potential sources for CC-induced IL-1α release.…”

Social Determinants modulate NK cell activity via obesity, LDL, and DUSP1 signaling

“…LDL has previously been shown to alter lysosomal function and induce lysosomal damage in endothelial cells and macrophages. 52, 86, 87 In inflammation-induced cardiomyopathy, DUSP1 also regulates mitophagy 88 , a process of selective autophagy similar to lysophagy. DUSP1 can also inhibit mast cell degranulation 89 , further supporting a potential role in repressing NK cell degranulation.…”

Formation and Cellular Impact of Cholesterol Crystals in Health and Disease

“…Concerning the intracellular mechanism, several cell types have been shown to be capable of CC formation including macrophages, endothelial cells, hepatocytes, and smooth muscle cells upon treatment with various lipids, such as LDL, oxLDL, and acLDL. [ 4,5,11,60,66–71 ]…”

“…visualized oxLDL‐derived CCs within lysosomal structures in macrophages, linking inefficient lysosomal function and disturbed lipid homeostasis to CC formation. [ 69 ] In our own studies, we show that inflammatory CC formation by endothelial cells under hyperlipidemic conditions is accompanied by increased lysosomal pH and decreased ACAT1 activity, potentially leading to endothelial CC formation in chronic inflammatory diseases like psoriasis, [ 4 ] a disease known to carry enhanced risk for CVD in humans and mouse models. [ 67,72,73 ] Cholesterol accumulation within lysosomes has been reported to influence lysosomal pH and function in macrophages, [ 74,75 ] subsequently triggering an inflammatory response.…”

“…summarized observations on the “morphology of lipid‐based substances”. [ 14 ] Since then, CCs have been implicated in a variety of diseases, including atherosclerosis, [ 1–3 ] psoriasis‐related cardiovascular disease (CVD), [ 4,5 ] myocardial infarction, [ 6 ] abdominal aortic aneurism, [ 7 ] transfusion‐related acute lung injury (TRALI), [ 8 ] gall stone formation, [ 9 ] embolism, [ 10 ] non‐alcoholic steatohepatitis (NASH), [ 11 ] age‐related macular degeneration, [ 12 ] or have been connected to defective regeneration in the central nervous system. [ 13 ] In this review we aim to highlight the current knowledge on CC‐related pathologies, and pathways potentially impacting CC formation.…”