Expression Levels of Predominant Adipokines and Activations of STAT3, STAT6 in an Experimental Mice Model of Obese Asthma

Abstract

Obese asthma is a new asthma phenotype. The underlying mechanisms are not clearly understood. Leptin and adiponectin are two predominant adipokines produced by adipose tissue. Studies have demonstrated a role of leptin on regulating the Janus kinase/signal transducer and ativator of transcription protein (JAK/STAT) signaling pathway and STAT3, STAT6 were known to have essential role on inflammatory cytokines production. However, whether STAT3 and STAT6 are activated and related to leptin merit further investigation. The aim of this study was to investigate the expression levels of leptin/adiponectin ratio and the activations of STAT3 and STAT6 in the lungs of obese asthma mice.

Experiments were carried out on male C57/B6J mice. The proteins in bronchoalveolar lavage fluid (BALF) were measured using ELISA. The expression levels of the transcriptional and translational factors in the lungs were examined using Quantitative Reverse Transcriptase Polymerase Chain reaction (qRT-PCR) and western blot.

The expression levels of leptin in the BALF of normal weight group, asthma group, obese group and obese asthma group were 2.032±0.133, 5.375±0.123, 5.418±0.165 and 7.486±0.168, respectively. The expression of leptin in obese asthma group was the highest (p<0.05) ，while the expression of adiponectin the lowest (p<0.05). The expression level of P-STAT3 in the obese asthma group was 0.9244±0.014, and was significantly higher than three other groups (p<0.05). The expressions of P-STAT6 in three other groups were all significantly higher than normal weight group (p<0.05).

Our data suggest that the function of leptin on the pulmonary inflammation of obese asthma may be partly through activating the STAT3 signaling pathway.