OR33-04 The Effect of Adiposity on the Fasting Serum Proteome in Normal Weight and Obese Men

In many individuals with obesity, adipose tissue is not only increased in mass but also exhibits altered function. Disordered adipokine secretion contributes to a pro-inflammatory milieu that may lead to obesity-related co-morbidities. Hypothesis-generating, high-throughput techniques can generate novel insights. Our objective was to identify proteome-wide alterations in serum proteins related to adiposity. We evaluated the fasting serum proteome in 25 men [13 normal weight (mean±SD body mass index (BMI 21.2±1.4 kg/m(2)) and 12 with obesity (BMI 31.5±4.8 kg/m(2))]. Blood was drawn at 0, 15, 30, and 55 minutes for proteomic analysis after an overnight fast (SOMAScan, SomaLogic, Inc.). The number of proteins and pathways that significantly differed between the two groups was determined across all time points during the fasting period. Normalized protein levels were compared between adiposity groups using rank product testing. Overrepresentation of protein constituents of established biological pathways was evaluated by hypergeometric test. P-values were adjusted using the Benjamini-Hockberg method, and those with an associated false discovery rate (FDR) of <0.05 were considered statistically significant. A total of 4,785 protein isoforms were robustly identified in serum of normal weight and men with obesity, of which 226 protein isoforms were significantly higher in obesity (vs. normal weight), and 178 were significantly lower in obesity (vs. normal weight). Higher levels of leptin and lower levels of IGFBP1 and IGFBP2 were observed in individuals with obesity during fasting (all FDR < 0.019). Functional annotation using Gene Ontology indicated that the following pathways differed most between obese vs. normal weight men: complement and coagulation cascade activation, amine metabolism, phosphatase activity, cellular response to nutrients (lipids, alcohol, and vitamin D), organic acid catabolism, and regulation of inflammatory responses. The protein isoforms identified in serum likely reflect systemic tissue-level changes in metabolism that may yield insights into the pathogenesis of obesity-related comorbidities and rational targets for intervention.