Effects of various forms of lipopolysaccharide on the expression of inflammatory mediators and cardiac biomarkers in human cardiac fibroblasts and human coronary smooth muscle cells

Abstract

Inflammation is an important event in the development of vascular diseases such as hypertension, atherosclerosis, and restenosis. The stimulation of lipopolysaccharide (LPS) from bacteria induces the release of critical proinflammatory cytokines that activate potent immune responses which may cause injury of cells in vivo and in vitro. Upon cardiac cell death caused by inflammation, the apoptotic cardiac cells express higher amount of cardiac markers. In this study, the effect of various LPS on human cardiac fibroblasts (HCFs) and human coronary smooth muscle cells (HCSMCs) were evaluated. Various forms of LPS were applied to HCFs and HCSMCs for 24, 48, 72 and 96 h. Proliferation rate of these cells was evaluated after stimulation. The levels of lactate dehydrogenase (LDH), N-terminal pro B-type natriuretic peptide (pro-BNP) and the MB isoenzyme of creatine kinase (CK-MB) were measured by an automation system. Cytokine levels in culture supernatants and extracted protein of cells were mixed and measured with IL-1β, IL-6 and IL-10 ELISA kits. Significant increase in the proliferation of two cardiac cells (P<0.05) after incubation for 48 and 72 h was noted but not for 24 and 96 h (P>0.05). Cardiac markers and inflammatory cytokines were significantly higher than control at 48 and 72 h (P<0.05), which demonstrated that HCFs and HCMSCs were under inflammation leading to cell injury between 48 and 72 h. LPS is one of the factors giving rise to periodontal diseases, it is also involved in in vitro cardiac cell injury. Therefore, LPS may be used as a bio-marker to monitor local or systemic inflammation.

Key words: Lipopolysaccharide, human cardiac fibroblasts, human coronary smooth muscle cell, inflammatory cytokines, cardiac bio-marker.