Lung Altered Expression of IL-1β mRNA and Its Signaling Pathway Molecules in Obese-asthmatic Male Wistar Rats

Abstract

Epidemiological and clinical studies indicate a close relationship between obesity and asthma. Here, we determined the impact of diet-induced obesity on the expression levels of IL-1β, IRAK-1 and TRAF-6 mRNA as well as IL-1β protein level and pathological changes in male Wistar rat's lung after sensitization with ovalbumin (OVA). Twenty male Wistar rats divided into four groups, control with normal diet (C+ND), OVA-sensitized with normal diet (S+ND), control with high-fat diet (C+HFD), and OVA-sensitized with high-fat diet (S+HFD). All rats fed for 12 weeks with standard pellets or high-fat diet while sensitization and challenging with OVA or saline were done for groups in the last month. In the end of intervention, lung was isolated and tested for the expression levels of IL-1β, IRAK-1 and TRAF-6 mRNA with real time-PCR method, and pathological changes were determined. Diet-induced obesity groups showed increased weight, obesity indexes and lipid profiles The expression levels of IL-1β mRNA in OVA-sensitization groups (S+ND and S+HFD) showed a significant increase compared with other groups. Also in S+HFD group, expression level of IRAK-1 and TRAF-6 mRNA were markedly higher than other groups (p<0.001). The pathological changes were marked in sensitized groups compared to non-sensitized groups; with marked increase in obese sensitized rat. The results showed that high fat diet caused overexpression of IL-1β, IRAK-1 and TRAF-6 mRNA as well as IL-1β protein in an experimental model of asthma. Our results suggest that obese-asthmatic conditions may lead to the local production and activation of pro-inflammatory agents.

Keywords: Asthma; IL-1β; IRAK-1; Lung; Obesity; TRAF-6.