HSP60 knockdown exerts differential response in endothelial cells and monocyte derived macrophages during atherogenic transformation

Abstract

Ectopic expression of HSP60 in vascular cells is known to activate auto-immune response that is critical to atherogenic initiation. However, the pathogenic relevance of the aberrant HSP60 upregulation in intracellular signaling pathways associated with atherogenic consequences in vascular cells remains unclear. The aim of the present study was to determine the role of endogenous HSP60 in atherogenic transformation of endothelial cells and macrophages. After generating primary evidence of oxidized low density lipoprotein (OxLDL) induced HSP60 upregulation in human umbilical vein endothelial cells (HUVEC), its physiological relevance in high fat high fructose (HFHF) induced early atherogenic remodelling was investigated in C57BL/6J mice. Prominent HSP60 expression was recorded in tunica intima and media of thoracic aorta that showed hypertrophy, lumen dilation, elastin fragmentation and collagen deposition. Further, HSP60 overexpression was found to be prerequisite for its surface localization and secretion in HUVEC. eNOS downregulation and MCP-1, VCAM-1 and ICAM-1 upregulation with subsequent macrophage accumulation provided compelling evidences on HFHF induced endothelial dysfunction and activation that were also observed in OxLDL treated- and HSP60 overexpressing-HUVEC. OxLDL induced concomitant reduction in NO production and monocyte adhesion were prevented by HSP60 knockdown, implying towards HSP60 mediated possible regulation of the said genes. OxLDL induced HSP60 upregulation and secretion was also recorded in THP-1 derived macrophages (TDMs). HSP60 knockdown in TDMs accounted for higher OxLDL accumulation that correlated with altered scavenger receptors (SR-A1, CD36 and SR-B1) expression further culminating in M1 polarization. Collectively, the results highlight HSP60 upregulation as a critical vascular alteration that exerts differential regulatory role in atherogenic transformation of endothelial cells and macrophages.

The role and mechanism of tetramethylpyrazine for atherosclerosis in animal models: A systematic review and meta-analysis

“…TMP may reduce ox-LDL uptake and increase cholesterol expulsion in macrophage-derived foam cells. The primary receptors for OX-LDL uptake are CD36 and SR-A, while the principal receptors for cholesterol efflux are ABCG1 and ABCA1 [ 35 ]. Inactivating PI3K signaling by TMP decreased CD36 and SR-A expression and OX-LDL uptake [ 18 ].…”

Systemic deficiency of vitronectin is associated with aortic inflammation and plaque progression in ApoE‐Knockout mice

“…The paraffin‐embedded tissue sections were cut into 5‐micron size and stained with hematoxylin and eosin 17 . The intima‐media thickness (IMT) was measured using ImageJ software by an investigator blinded to group assignment 18 . To access the aortic inflammation, slides were numbered randomly and given to blind investigators for evaluation.…”

“… 17 The intima‐media thickness (IMT) was measured using ImageJ software by an investigator blinded to group assignment. 18 To access the aortic inflammation, slides were numbered randomly and given to blind investigators for evaluation. The score was given from 0–4 as described previously.…”

Recognition of Oxidized Lipids by Macrophages and Its Role in Atherosclerosis Development

“…Interaction of oxLDL with monocytes and endothelial cells upregulates the expression of HSP60 [ 73 , 74 ], a molecular chaperone that is predominantly involved in mitochondrial protein folding and is increased upon mitochondrial stress. The increase of HSP60 level leads to its membrane translocation and secretion [ 74 ]. Despite being endogenous proteins, HSPs may be antigenic due to the molecular mimicry with bacterial HSPs [ 75 ].…”

“…First, HSP60 induces endothelial cells activation, which may be relevant for early atherosclerotic lesion formation. Atherogenic activation of endothelial cells as a result of exposure to oxLDL with upregulation of adhesion molecules, such as intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin and chemokines (MCP-1), was clearly shown to be HSP60-dependent [ 74 ]. Second, HSP60-specific T lymphocytes are abundant in early atherosclerotic lesions in humans [ 76 ], and their presence in circulation potentiates atherosclerosis development in hyperlipidemic mouse model [ 75 ].…”