The Increase of pFAK and THBS1 Protein and Gene Expression Levels in Vascular Smooth Muscle Cells by Histamine-treated M1 Macrophages

Abstract

Atherosclerosis is developed due to the formation of atheroma plaques in the coronary arteries. In this process, M1 macrophages and vascular smooth muscle cells (VSMCs) are the main functional cells. Inflammatory mediators such as histamine may inflame M1 macrophages. The aim of this study was to determine the effect of M1 macrophage secretion contents on the gene and protein expression levels of focal adhesion kinase (FAK), vasodilator-stimulated phosphoprotein (VASP), and thrombospondin1 (THBS1).

Whole blood samples from the six healthy subjects (stenosis<5%), and six patients (stenosis>70%) were prepared and peripheral blood mononuclear cells (PBMCs) were isolated. Then monocytes were differentiated into M1 macrophages using 100 ng/mL granulocyte-macrophage colony stimulating factor (GM-CSF). The differentiated M1 macrophages were treated with histamine (10^-6 M), and their secretion contents were harvested and added to the culture medium of VSMCs. The FAK, VASP, and THBS1 gene expression and protein levels were measured using RT-qPCR and western blot techniques in VSMCs, respectively.

The FAK and THBS1 gene expression levels significantly increased in VSMCs after adding secretion contents obtained from histamine-treated M1 macrophages (p=0.023 and 0.05, respectively), while significant results were not observed for VASP gene (p=0.45). In converse with the phosphorylated VASP (pVASP) (p<0.34), the phosphorylated FAK (pFAK) and THBS1 protein levels increased in VSMCs (p<0.001).

We concluded that in inflammatory conditions, the immune events could affect the macrophages by histamine. The activated macrophages could locally activate signaling 

pathways via FAK and THBS1 genes that are effective in the proliferation and migration of VSMCs.