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

OBJECTIVE: 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.

METHODS: 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.

RESULTS: 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 Rho  = 0.35, 0.20, and 0.20 for CRP, IL-6, and TNF-α, respectively), whereas the respective correlations with adiponectin were negative (pooled Rho  = -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.

CONCLUSIONS: 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.