Interplay Between Human Gut Bacteria Escherichia coli and Lactobacillus mucosae in the Occurrence of Neuropsychiatric Disorders in Mice - PubMed (original) (raw)

Interplay Between Human Gut Bacteria Escherichia coli and Lactobacillus mucosae in the Occurrence of Neuropsychiatric Disorders in Mice

Jeon-Kyung Kim et al. Front Immunol. 2020.

Abstract

To understand the roles of human gut bacteria in the occurrence of neuropsychiatric disorders, we isolated inflammatory Escherichia coli K1 and anti-inflammatory Lactobacillus mucosae from healthy human feces and examined their effects on the occurrence of altered microbiota, cognitive decline, and depression in mice. Oral gavage of Escherichia coli K1 caused colitis, cognitive decline, and depression in mice in the elevated plus maze, tail suspension, and forced swimming tasks. However, NK41 treatment reduced K1-induced cognitive decline and anxiety/depression. Furthermore, NK41 treatment increased K1-suppressed brain-derived neurotrophic factor (BDNF) expression and BDNF+/NeuN+ cell population and suppressed K1-induced NF-κB activation and LPS+/Iba1+ and NF-κB+/Iba1+ (microglial) cell populations in the hippocampus. NK41 treatment also suppressed K1-induced TNF-α and LPS levels in the blood and TNF-α expression, myeloperoxidase activity, NF-κB+/CD11c+ and CD11b+/CD11c+ cell populations in the colon. Furthermore, NK41 treatment decreased K1-induced colonic MUC2 expression, gut Proteobacteria population, and fecal LPS levels and modified the bacterial abundance related to polysaccharide breaking and biosynthesis. In conclusion, the overgrowth of inflammatory bacteria such as Escherichia coli in the gastrointestinal tract can cause neuropsychiatric disorders with gut microbiota alteration and the superiority of anti-inflammatory bacteria such as Lactobacillus mucosae can alleviate neuropsychiatric disorders with the attenuation of altered microbiota.

Keywords: brain; colon; gut bacteria; inflammation; neuropsychiatric disorder.

Copyright © 2020 Kim, Lee, Lee, Jang and Kim.

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Figures

Figure 1

Figure 1

Effects of gut bacteria K1 and NK41 on the TNF-α expression and NF-κB activation in macrophages. (A) Effects of NK41 and K1 on TNF-α expression and NF-κB activation in macrophages. (B) Effects of NK41 on TNF-α expression and NF-κB activation in LPS-stimulated macrophages. (C) Effect of K1 on TNF-α expression and NF-κB activation in LPS-stimulated macrophages. (D) Effect of NK41 on NF-κB activation in K1-stimulated macrophages. Macrophage cells (1 × 106/mL) were incubated with K1 or NK41 (1 × 103 or 1 × 105 CFU/mL) in the absence or presence of LPS for 2 h (for NF-κB) or 20 h (for TNF-α). p-p65 and p65 (NF-κB) were measured by immunoblotting. TNF-α was measured by ELISA kit. Data values are indicated as mean ± SD (n = 4). #p < 0.05 vs. Con group treated with Vehicle alone. *p < 0.05 vs. group treated with K1 and LPS alone.

Figure 2

Figure 2

Effects of K1 and NK41 on the occurrence of neuropsychiatric disorders in mice. (A) Experimental protocol. (B) Effect of K1 on the time spent in open arms (OT) in EPM task. (C) Effect of K1 on the immobility in the forced swimming task. (D) Effect of K1 on memory impairment in Y-maze task. (E) Effect of K1 on the infiltration of Iba1+ cells into the hippocampus. (F) Effect of K1 on BDNF expression, CREB phosphorylation, and NF-κB activation in the hippocampus. (G) Effect of NK41 on the depression in EPM task. Effect of NK41 on the cogntive decline in the Y-maze (H) and Banes maze tasks (I). (J) Effect of NK41 on the infiltration of Iba1+ cells into the hippocampus. (K) Effect of NK41 on BDNF expression, CREB phosphorylation, and NF-κB activation in the hippocampus. Mice were exposed to K1 or NK41 (C, vehicle [1% maltose]; K7, 1 × 107 CFU/mouse/day of K1; K8, 1 × 108 CFU/mouse/day of K1; K9, 1 × 109 CFU/mouse/day of K1; NK8, 1 × 108 CFU/mouse/day of NK41; or NK9, 1 × 109 CFU/mouse/day of NK41) daily for 5 days and thereafter treated with vehicle for 5 days. Normal control group (Con), not exposed to gut bacteria, was treated with 1% maltose instead of gut bacteria. Data values were indicated as mean ± SD (n = 7). *p < 0.05 vs. Con group.

Figure 3

Figure 3

NK41 suppressed K1-induced altered microbiota in the feces mice. Effects on the composition of gut microbiota, analyzed by the pyrosequencing: phylum (A), principal coordinate analysis (PCoA) plot based on weighted pairwise Fast UniFrac analysis (B), and OTUs and Shannon (C). (D) Cladogram generated by LEfSE indicating significant differences in gut microbial (family) abundances among Con (blue), NK (purple), K (red), and KN (green) groups. Yellow nodes represent species with no significant difference. The threshold logarithmic score set at 2.0 in the family level and ranked. (E) Effects on fecal Escherichia coli and Lactobacillus mucosae, assessed by qPCR. (F) Effects on the fecal LPS level. LPS levels were assayed by ELISA kits. (G) The abundance of bacterial genes predicted using the method of PICRUSt. The difference was analyzed using the Kruskal-Wallis H test. (H) Effects on the MUC1 and MUC2 expression in the colon. (I) Histological examination of colons, stained with alcian blue. NK and K groups were exposed to Lactobacillus mucosae NK41 (1 × 109 CFU/mouse/day of NK41) and Escherichia coli K1 (1 × 109 CFU/mouse/day) daily for 5 days, respectively, and thereafter treated with vehicle (1% maltose) daily for 5 days. KN group was exposed to Escherichia coli K1 (1 × 109 CFU/mouse/day) daily for 5 days and thereafter treated with Lactobacillus mucosae NK41 (1 × 109 CFU/mouse/day of NK41) daily for 5 days. Con group was treated with vehicle instead of gut bacteria. Data values were indicated as mean ± SD (n = 5). #p < 0.05 vs. Con group. *p < 0.05 vs. K group.

Figure 4

Figure 4

NK41 signiticantly suppressed K1-induced gut inflammation in mice. Effects on colon length (A), myeloperoxidase (MPO) activity (B), and TNF-α (C) and IL-6 (D) expression in the colon. (E) Effects on occludin and claudin-1 expression and NF-kB activation (E) in the colon. Effects on CD11b+/CD11c+ (F) and NF-κB+/CD11c+ cell populations (G) in the colon. NK and K groups were exposed to Lactobacillus mucosae NK41 (1 × 109 CFU/mouse/day of NK41) and Escherichia coli K1 (1 × 109 CFU/mouse/day) daily for 5 days, respectively, and thereafter treated with vehicle (1% maltose) daily for 5 days. KN group was exposed to Escherichia coli K1 (1 × 109 CFU/mouse/day) daily for 5 days and thereafter treated with Lactobacillus mucosae NK41 (1 × 109 CFU/mouse/day of NK41) daily for 5 days. Con group was treated with vehicle instead of gut bacteria. Colonic p65, p-p65, and β-actin were analyzed by immunoblotting. TNF-α and IL-6 levels were assayed by ELISA kits. NF-κB+, CD11b+, and CD11c+ cells were measured using a confocal microscope. Arrows indicate postive cells. Data values were indicated as mean ± SD (n = 7). #p < 0.05 vs. Con group. *p < 0.05 vs. K group.

Figure 5

Figure 5

NK41 signiticantly suppressed K1-induced neuropsychiatric disorders in mice. (A) Experimental protocol. Effect on the cognition function in Y-maze (B), NOR (C), and Banes maze (D). Effect on the depressive behaviors in the forced swimming (E), EPM (F: OT, time spent in open arms; G: OE, open arm entries), and light-dark transition tasks (H: TL, time spent in the light dark compartment; I: NT, number of transitions into the light dark compartment). Effect on the infitration of NF-κB+/Iba1+ (J), LPS+/Iba1+ (K), and BDNF+/NeuN+ cells (L) into the hippocampus. Effects on IL-6 (M), TNF-α (N), and BDNF expression, CREB phosphorylation, and NF-κB activation (O). Effects on the LPS (P), IL-6 (Q), and TNF-α levels (R) in the blood. NK and K groups were exposed to Lactobacillus mucosae NK41 (1 × 109 CFU/mouse/day of NK41) and Escherichia coli K1 (1 × 109 CFU/mouse/day) daily for 5 days, respectively, and thereafter treated with vehicle (1% maltose) daily for 5 days. KN group was exposed to Escherichia coli K1 (1 × 109 CFU/mouse/day) daily for 5 days and thereafter treated with Lactobacillus mucosae NK41 (1 × 109 CFU/mouse/day of NK41) daily for 5 days. Con group was treated with vehicle instead of gut bacteria. TNF-α, IL-6, and LPS were assayed by ELISA. p65, p-p65, CREB, p-CREB, BDNF, and β-actin were analyzed by immunoblotting. Iba1+, NF-κB+, LPS+ and NeuN+ cells were measured using a confocal microscope). #p < 0.05 vs. Con group. *p < 0.05 vs. K group.

Figure 6

Figure 6

Interplay between Escherichia coli K1 and Lactobacillus mucosae NK41 on the occurrence of neuropsychotric disorders and altered microbiota.

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