A Nutrient-Dense Diet with Optimal Protein Level Restores Goblet Cells and Alleviates Microbial Dysbiosis in a Mouse...

Chronic intestinal inflammation is a key driver of colitis-associated colorectal cancer. A mouse model with intestinal epithelial cell-specific knockout (KO) of heterogeneous nuclear ribonucleoprotein I (hnRNPI KO) spontaneously develops colitis and reduces goblet cell numbers, mimicking the pathological symptoms observed in humans with chronic intestinal inflammation, making the hnRNPI KO mouse an invaluable model of gut inflammation. Although higher dietary protein has been associated with lower inflammation and restoration of immune adaptation, the mechanisms remain unclear.

This study aimed to investigate the effects of optimized dietary protein on colonic goblet cell functions and on correcting gut dysbiosis in the hnRNPI KO mouse model.

Male wild type (WT) and hnRNPI KO mice were fed either a control protein diet (CON; 14.41% kcal protein) or a nutrient-dense modified diet (MOD; 28.83% kcal protein) for 22 wk. Body weight, food intake, and colon histology were assessed. Goblet cells and mucin content were quantified using Alcian Blue/periodic acid-Schiff staining. CD4⁺ T-cell subpopulations were measured by flow cytometry. Gut microbial composition was identified using 16S rRNA amplicon sequencing and analyzed using QIIME2 and phyloseq. Two-way analysis of variance with Tukey's multiple comparisons was used to assess diet and genotype interactions.

Feeding the MOD restored goblet cell numbers and mucin content in KO mice (P < 0.05). MOD-fed KO mice had significantly lower IL-17⁺ interferon-γ⁺ CD4⁺ T-cell subset in the colon than the WT-MOD mice (873 and 1885 cells, respectively, P < 0.05). Feeding KO mice MOD significantly increased fecal Dubosiella sp. (24% in MOD-KO; 12% in CON-KO; P < 0.05) and decreased Lachnospiraceae NK4A136 abundance (0.18% in MOD-KO; 2.3% in CON-KO; P < 0.05).

An optimized dietary protein restores colon goblet cells, modulates immune responses, and alleviates gut microbial dysbiosis. Our results highlight the benefits of optimized dietary protein in ameliorating intestinal inflammation and potentially enhancing gut health.