Role of adiponectin and other inflammatory biomarkers in COPD patients

Adiponectin (APN) is a secretory protein synthesized by adipocytes and plays a potential role in regulating the inflammatory response by many of autocrine or paracrine. The mechanism of APN participation in the inflammation of COPD remains unknown. So, we investigated serum and induced sputum adiponectin as a biomarker of systemic inflammatory response and to find its relation with other inflammatory biomarkers like, IL-8, IL-6 and TNF-α. The aim of the work was also to find out its role in the pathogenesis of cachexia in COPD patients. The study included 80 subjects including 60 COPD patients (20 stable and 40 exacerbated) and 20 age and sex-matched healthy control subjects. The adiponectin, interleukin-8, interleukin-6 and tumor necrosis factor-alpha levels were measured in serum, induced sputum by enzyme-linked immunosorbent assay. Serum CRP level was measured using the nephelometric method. Body mass index (BMI) was estimated for COPD patients and its relation to the inflammatory biomarkers was studied. Adiponectin levels in COPD patients were significantly higher than those in control subjects (P < 0.001). CRP, APN, IL-8, IL-6, TNF-α were significantly higher in the exacerbated COPD patients compared to the stable group (P < 0.001, P < 0.001, P < 0.001, P < 0.001 and P < 0.001, respectively). The ratio of APN level in serum to induced sputum was (3.1) in AECOPD patients and (2.4) in stable COPD patients while for IL-8, IL-6 & TNF-α the ratios were all <(1). Adiponectin could play a role as a biomarker of systemic inflammatory response in COPD patients. Also, its rise in the exacerbation period denotes that this may also be a biomarker of the exacerbation phase. While IL-8, IL-6, TNF-α could be used to reflect the airway inflammation in induced sputum. Adiponectin serum level is higher in underweight COPD patients which may reflect its role in the pathogenesis of cachexia in COPD patients.