Effect of docosahexaenoic acid as an anti-inflammatory for Caco-2 cells and modulating agent for gut microbiota in children with obesity (the DAMOCLE study)

Purpose: Docosahexaenoic acid (DHA) is a long-chain omega‐3 polyunsaturated fatty acid. We investigated the dual health ability of DHA to modulate gut microbiota in children with obesity and to exert anti-inflammatory activity on human intestinal Caco-2 cells. Methods: In a pilot study involving 18 obese children (8–14 years), participants received a daily DHA supplement (500 mg/day) and dietary intervention from baseline (T0) to 4 months (T1), followed by dietary intervention alone from 4 months (T1) to 8 months (T2). Fecal samples, anthropometry, biochemicals and dietary assessment were collected at each timepoint. At preclinical level, we evaluated DHA’s antioxidant and anti-inflammatory effects on Caco-2 cells stimulated with Hydrogen peroxide (H2O2) and Lipopolysaccharides (LPS), by measuring also Inducible nitric oxide synthase (iNOS) levels and cytokines, respectively. Results: Ten children were included in final analysis. No major changes were observed for anthropometric and biochemical parameters, and participants showed a low dietary compliance at T1 and T2. DHA supplementation restored the Firmicutes/Bacteroidetes ratio that was conserved also after the DHA discontinuation at T2. DHA supplementation drove a depletion in Ruminococcaceae and Dialisteraceae, and enrichment in Bacteroidaceae, Oscillospiraceae, and Akkermansiaceae. At genus level, Allisonella was the most decreased by DHA supplementation. In Caco-2 cells, DHA decreased H2O2-induced reactive oxygen species (ROS) and nitric oxide (NO) production via iNOS pathway modulation. Additionally, DHA modulated proinflammatory (IL-1β, IL-6, IFN-γ, TNF-α) and anti-inflammatory (IL-10) cytokine production in LPS-stimulated Caco-2 cells. Conclusion: An improvement in gut dysbiosis of children with obesity seems to be triggered by DHA and to continue after discontinuation. The ability to modulate gut microbiota, matches also with an anti-inflammatory effect of DHA on Caco-2 cells. Graphical abstract: (Figure presented.)