Preventive Effects of Long-Term Intake of Plant Oils With Different Linoleic Acid/Alpha-Linolenic Acid Ratios on Acute Colitis Mouse Model

Abstract

Objective: To investigate the preventive effects of plant oils with different linoleic acid/alpha-linolenic acid (LA/ALA) ratios against colitis symptoms, and dysbiosis of gut microbiota in acute colitis mouse model.

Methods: Sixty male C57BL/6 mice were assigned into six groups (n = 10): three groups were fed low-fat diets with low, medium, and high LA/ALA ratios; and three groups were fed with high-fat diets with low, medium, and high LA/ALA ratios. After 3 months of diet, the mice were exposed to dextran sodium sulfate solution to induce acute colitis. The severity of colitis was estimated by disease activity index (DAI) and histopathological examination. 16S rRNA gene sequencing was used for the analysis of gut microbiota.

Results: Plant oils with a lower LA/ALA ratio showed higher alleviating effects on the symptoms of colitis, which were accompanied by the better prebiotic characteristics manifested as effectively inhibiting the abnormal expansion of phylum Proteobacteria and genus Escherichia-Shigella in the gut microbiota of colitis mouse models.

Conclusion: A potential IBD prevention strategy of reducing the LA/ALA ratio in the daily consumed plant oils was proposed in this study. Furthermore, based on the optimized LA/ALA ratio, this preventive effect might not be weakened by the high intake of plant oils.

Keywords: 16S rRNA gene sequencing; alpha-linolenic acid; colitis mouse model; gut microbiota; inflammation; linoleic acid.

FIGURE 1

(A) Illustration of experimental design and basic indices of mice during 3 months on different diets. (B) Curve of changes in body weights. (C) Fasting blood glucose levels after 3 months feeding on different diets. Asterisk indicates a significant difference between the high-fat diet groups and low-fat diets (LF-L + LF-M + LF-H vs. HF-L + HF-M + HF-H) and circle indicates a significant difference between the HF-M and other high fat diet groups.

FIGURE 2

Body physiological conditions and DAI scores. (A) Change curves of body weight and (B) DAI scores during DSS-induction. Comparison of (C) body weights and (D) DAI scores at the end of DSS-induction. Bars with the same letter indicate a non-significant difference (P > 0.05). Asterisk indicates a significant difference between the high fat diet groups and low fat diet groups; ^#indicates a significant difference between the mice from groups fed with the diets of different LA/ALA ratios.

FIGURE 3

(A) Colon lengths of the mice. (B) Spleen weights of mice. (C) Histopathological examination and (D) evaluation of histopathological severity scores of the colon tissue. Bars with the same letter indicate a non-significant difference (P > 0.05). Asterisk indicates a significant difference between the high fat diet groups and low fat diet groups; ^#indicates a significant difference between the mice from groups fed with the diets of different LA/ALA ratios.

FIGURE 4

(A) Bacterial richness of gut microbiota evaluated by Chao index. (B) Bacterial diversity of gut microbiota estimated by Shannon index. (C) Compositions of gut microbiota in different groups at phylum level, and (D) compositions of gut microbiota in different groups at genus level. Asterisk indicates a significant difference between the high fat diet groups and low fat diet groups.

FIGURE 5

Statistical comparisons of the relative abundances of the (A) top 7 main bacterial phyla and (B) top 7 main bacterial genera in the gut microbiota of mice from the groups fed with different diets. (C) Correlations between the relative abundance of genus Escherichia Shigella and DAI scores. (D) Correlations between the relative abundance of genus Helicobacter and DAI scores. Bars with the same letter indicate a non-significant difference (P > 0.05). Asterisk indicates a significant difference between the high fat diet groups and low fat diet groups; ^#indicates a significant difference between the mice from groups fed with the diets of different LA/ALA ratios.