Cigarette smoke-induced inflammatory changes in rat heart in vivo

Abstract

Cigarette smoke (CS) is a well-established risk factor to cardiovascular health and the most preventable cause of death. Countless studies have demonstrated its harm to health and many more studies investigating its pathogenic mechanisms. While the CS-induced pathogenic mechanism of cardiovascular dysfunction has been mainly attributed to a combination of oxidative imbalance, vascular endothelial dysfunction, inflammation and modification of lipid profile, the focus of the current study was on the mediators of inflammation and the activation of signal pathways. In this study, we investigated the effects of CS on the pro-inflammatory/anti-inflammatory status in the heart and to elucidate the activation of specific signaling pathways in an in vivo rat model. Male Sprague-Dawley rats were divided into groups of CS exposure and sham air (SA) and exposed to 1 hour of respective CS and SA exposure daily for 56 days. The rats were then sacrificed and the ventricular homogenates were examined. Cardiac pro- inflammatory and anti-inflammatory mediators such as C-reactive protein (CRP), interleukin (IL)-6, cytokine-induced neutrophil chemoattractant (CINC-1), transforming growth factor (TGF)-β1, vascular endothelial growth factor (VEGF) and IL-10 were measured by enzyme-linked immunosorbent assay (ELISA) and the activation of specific signaling pathways was determined by Western blot analysis. CS caused suppression of cardiac CRP, IL-6, TGF-β1, and IL-10 and elevation of VEGF, revealing the imbalance of pro-inflammatory/anti-inflammatory status. Nuclear factor-κB (NF-κB) was also activated along with the activation of extracellular-regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK) but not p38 mitogen-activated protein kinase (MAPK) after 56 days of CS exposure. These data suggests the presence of a local adaptive mechanistic response to modulate cardiac pro-inflammatory/anti-inflammatory status via NF-κB/MAPK pathways after exposure to CS. These findings shed insight into the mechanistic pathways of CVD progression, allowing possible identification of selected mediators as biomarkers that could benefit early detection of CVD arisen from cigarette smoking.