Probiotic Lactobacillus fermentum strain JDFM216 improves cognitive behavior and modulates immune response with gut microbiota

Abstract

Increasing evidence indicates that alterations in gut microbiota are associated with mammalian development and physiology. The gut microbiota has been proposed as an essential player in metabolic diseases including brain health. This study aimed to determine the impact of probiotics on degenerative changes in the gut microbiota and cognitive behavior. Assessment of various behavioral and physiological functions was performed using Y-maze tests, wheel running tests, accelerated rotarod tests, balance beam tests, and forced swimming tests (FSTs), using adult mice after 50 weeks of administering living probiotic bacterium Lactobacillus fermentum strain JDFM216 or a vehicle. Immunomodulatory function was investigated using immune organs, immune cells and immune molecules in the mice, and gut microbiota was also evaluated in their feces. Notably, the L. fermentum JDFM216-treated group showed significantly better performance in the behavior tests (P < 0.05) as well as improved phagocytic activity of macrophages, enhanced sIgA production, and stimulated immune cells (P < 0.05). In aged mice, we observed decreases in species belonging to the Porphyromonadaceae family and the Lactobacillus genus when compared to young mice. While administering the supplementation of L. fermentum JDFM216 to aged mice did not shift the whole gut microbiota, the abundance of Lactobacillus species was significantly increased (P < 0.05). Our findings suggested that L. fermentum JDFM216 also provided beneficial effects on the regulation of immune responses, which has promising implications for functional foods. Taken together, L. fermentum JDFM216 could confer the benefit of improving health with enhanced cognition, physiological behavior, and immunity by modulating the gut microbiota.

Figure 1

Behavioral assessments of JDFM216-treated aged mice. (A) Representation of the study design. JDFM216 or vehicle (sterile water) was administered for a total period of 48 weeks to C57BL/6 mice. (B) Y-maze test. (C) Voluntary wheel-running test. (D) Accelerated rotarod test. (E) Beam-walking test. (F) Forced swimming test (FST). (G) The average weight and % weight loss of aged mice before and after the battery of behavioral tests (100 and 102 weeks). For all graphs, data are expressed as the means ± SD. n = 13–15 per group. Levels of significance determined by the Student’s t test are as follows: *P < 0.05; **P < 0.01; ***P < 0.001, compared with the aged mouse group.

Figure 2

Profiling of the immune response in JDFM216-treated aged mice. (A) Spleen indices of young and aged mice (Young Groups, Aged Groups or Aged + JDFM216 Groups). (B) Secretary immunoglobulin A (sIgA) production in the intestine. (C) Proliferation of splenocytes. The proliferation was measured at 48, 72, and 96 h of cultivation. (D) Pinocytosis of peritoneal macrophages. (E) CD11b and CD4 expression on the surface of dendritic cells. (F) Leukocyte respiratory burst activity. Cytokine IL-4 and chemokine CXCL1 levels. (G,H). The young mouse group was used at 8 weeks of age. Values are means ± SD. Asterisks represent statistically significant differences; one-way ANOVA was performed. *P < 0.05; **P < 0.01; ***P < 0.001, compared with the groups.

Figure 3

Comparison of gut microbiota between young mice (Young Groups at 8 weeks) and aged mice (Aged Groups at 100 weeks) based on principal component analysis (A) and operational taxonomic units (OTUs) with significantly different abundance (B). Corrected P values are shown on the right. The effect sizes and confidence intervals are provided to allow for critical assessment of the biological relevancy of the test results.

Figure 4

Comparison of gut microbiota between aged mice (Aged Groups) and aged mice fed Lactobacillus fermentum JDFM216 (Aged Groups + JDFM216) at 100 weeks based on principal component analysis (A) and operational taxonomic units (OTUs) with significantly different abundance (B). Corrected P values are shown on the right. The effect sizes and confidence intervals are provided to allow for critical assessment of the biological relevance of the test results. Significantly increased (A) and decreased OTUs (B) and by feeding JDFM216.