Dietary Application of the Microalga Lobosphaera incisa P127 Reduces Severity of Intestinal Inflammation, Modulates Gut-Associated Gene Expression, and Microbiome in the Zebrafish Model of IBD

Scope: Microalgae are an emerging nutritional resource of biomolecules with potential to alleviate gut inflammation. The study explores the anti-inflammatory and immunomodulatory potential of the microalga Lobosphaera incisa P127, which accumulates a rare omega-6 LC-PUFA dihomo-ɣ-linolenic acid (DGLA) under nitrogen starvation. The therapeutic potential of dietary supplementation with P127 is investigated in the zebrafish model of IBD (TNBS-induced colitis). Methods and results: Guts are sampled from zebrafish fed experimental diets for 4 weeks, before and 24 h after TNBS challenge. Diets containing 15% non-starved (Ns) and 7.5% and 15% N-starved (St) algal biomass significantly attenuate the severity of gut injury and goblet cell depletion. In contrast, diets containing 7.5% Ns and DGLA ethyl ester have no effect on gut condition. Fish fed 15% St, high-DGLA biomass, have the fewest individuals with pathological alterations in the gut. Dietary inclusion of Ns and St distinctly modulates gut-associated expression of the immune and inflammatory genes. Fish fed 15% Ns biomass display a coordinated boost in immune gene expression and show major changes in the gut microbiome prior challenge. Conclusion: Dietary inclusion of L. incisa biomass at two physiological states, ameliorates TNBS-induced gut inflammation, suggesting the synergistic beneficial effects of biomass components not limited to DGLA.