Association Between Peripheral Adipokines and Inflammation Markers: A Systematic Review and Meta-Analysis

Obesity-induced inflammation potentially promotes a variety of chronic conditions. This study aimed to summarize cross-sectional associations between adipose tissue-derived hormones (leptin and adiponectin) and inflammatory biomarkers (C-reactive protein [CRP], interleukin [IL]-6, and tumor necrosis factor [TNF]-α) by means of meta-analysis.

A systematic search of the databases EMBASE and MEDLINE (PubMed) up to January 2017 was conducted. Data were independently extracted and evaluated by two reviewers. Pooled effect sizes and 95% confidence intervals were calculated using random-effects models.

After the initial search, 5,907 publications were retrieved; of these, an overall 60 studies with 45,210 participants were deemed eligible for inclusion in the meta-analysis. Positive correlations with inflammatory biomarkers were observed for leptin (pooled R_ho  = 0.35, 0.20, and 0.20 for CRP, IL-6, and TNF-α, respectively), whereas the respective correlations with adiponectin were negative (pooled R_ho  = -0.18, -0.14, and -0.12 for CRP, IL-6, and TNF-α, respectively). Stratification by age showed that the observed correlations tended to be weaker with the increasing age of participants. No apparent differences were observed by sex and adiposity status.

This is the first quantitative synthesis of human studies on the association between circulating adipokines and inflammation biomarkers. Potential influence of age on these associations requires further evaluation.