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. Microalgae are potent producers of biomolecules with health‐beneficial properties. We investigated the immunomodulatory and anti‐inflammatory potential of the mutant strain P127 of the microalga Lobosphaera incisa, which accumulates a rare long‐chain polyunsaturated fatty acid dihomo‐ɣ‐linolenic acid, in a zebrafish model of IBD. Microalgae‐supplemented diets alleviated chemically induced colitis, signifying the potential of microalgae in treating inflammatory gut conditions and diseases.