Riboflavin Reduces Pro-Inflammatory Activation of Adipocyte-Macrophage Co-culture. Potential Application of Vitamin B2 Enrichment for Attenuation of Insulin Resistance and Metabolic Syndrome Development.

Due to the progressive increase in the incidence of obese and overweight individuals, cardiometabolic syndrome has become a worldwide pandemic in recent years. Given the immunomodulatory properties of riboflavin, the current study was performed to investigate the potency of riboflavin in reducing obesity-related inflammation, which is the main cause of insulin resistance, diabetes mellitus 2 or arteriosclerosis. We determined whether pretreatment with a low dose of riboflavin (10.4-1000 nM) affected the pro-inflammatory activity of adipocyte-macrophage co-culture (3T3 L1-RAW 264.7) following lipopolysaccharide stimulation (LPS; 100 ng/mL) which mimics obesity-related inflammation. The apoptosis of adipocytes and macrophages as well as tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), interleukin 1beta (IL-1β), monocyte chemotactic protein 1 (MCP-1), high-mobility group box 1 (HMGB1), transforming growth factor-beta 1 (TGFβ), interleukin 10 (IL-10), inducible nitric oxide synthase (iNOS), nitric oxide (NO), matrix metalloproteinase 9 (MMP-9), tissue inhibitor of metalloproteinases-1 (TIMP-1) expression and release, macrophage migration and adipokines (adiponectin and leptin) were determined. Our results indicated an efficient reduction in pro-inflammatory factors (TNFα, IL-6, MCP-1, HMGB1) upon culture with riboflavin supplementation (500-1000 nM), accompanied by elevation in anti-inflammatory adiponectin and IL-10. Moreover, macrophage migration was reduced by the attenuation of chemotactic MCP-1 release and degradation of the extracellular matrix by MMP-9. In conclusion, riboflavin effectively inhibits the pro-inflammatory activity of adipocyte and macrophage co-cultures, and therefore we can assume that its supplementation may reduce the likelihood of conditions associated with the mild inflammation linked to obesity.