栃尾 巧

Psychiatric disorders such as major depressive disorder are closely linked to the intestinal environment, suggesting intestinal health may contribute to their prevention. Prebiotics, which enhance intestinal health, are promising candidates for preventing psychiatric disorders. 1-Kestose (kestose), a type of prebiotics, has shown potential, but its effects on psychiatric disorders remain unclear. In this study, we investigated whether kestose prevents abnormal behaviors induced by social isolation (SI) stress and which underlies mechanisms of preventive effects. C57BL/6J male mice (3 weeks old) were divided into two groups: individually housed (SI) group and housed five mice per cage (GH) group. Each group received either a normal diet or a kestose diet (5% kestose) for 5 weeks daily until the end of the behavioral testing. Kestose prevented the SI-induced abnormal behaviors including reduced sociality, impaired spatial recognition, and heightened anxiety, which were associated with suppressed microglial activation in the hippocampus. Kestose altered the diversity of gut microbiota and increased the abundance of Bacteroides sartorii. Furthermore, short-chain fatty acids (SCFAs) such as butyric acid, acetic acid, and propionic acid, produced by intestinal microbiota, were increased after kestose supplementation. Positive correlations were observed between B. sartorii abundance and SCFA levels, suggesting that B. sartorii contributes to SCFA production. Notably, both B. sartorii and SCFAs were strongly associated with the abnormal behaviors by SI. These findings suggest that kestose prevents SI-induced abnormal behaviors by modulating gut microbiota, particularly B. sartorii, through an increase of SCFA production. Taken together, kestose could be used as a promising prebiotic intervention for psychiatric disorders.

Background/Objectives: Nopalea cochenillifera (L.) Salm-Dyck cladodes are rich in dietary fiber, polyphenols, and minerals, which are known to exert antioxidant and immunomodulatory effects. However, the mechanisms and active constituents have not been fully elucidated. In this study, we investigated the effects of continuous N. cochenillifera consumption on lipid metabolism, immune function, and the gut microbiota in mice. Methods: The feed was made using freeze-dried and powdered cladodes of N. cochenillifera. Male C57BL/6J mice were assigned to four groups: control diet (C), control diet plus 10% N. cochenillifera (CN), high-fat diet (FC), and high-fat diet plus 10% N. cochenillifera (FN). Results: Cactus supplementation reduced the body and liver weights that were elevated by the high-fat diet. Serum total cholesterol and free fatty acids were increased in the FC group compared with the C group, while cactus intake lowered these levels and enhanced fecal cholesterol excretion. Cactus consumption also elevated fecal total IgA and mucin contents. IL-4 expression in Peyer's patches was significantly increased in the FN group compared with the FC group. Gut microbiota analysis showed significant differences in β-diversity, along with increased α-diversity and higher abundance of Lachnospiraceae, following cactus intake. Conclusions: These findings suggest that N. cochenillifera intake increases gut microbiota diversity, which enhances intestinal barrier function and thereby contributes to improved lipid metabolism and immune regulation.

BACKGROUND: Erythritol, a sugar alcohol, has been reported to suppress the in vitro growth of Staphylococcus pseudintermedius and Staphylococcus coagulans. OBJECTIVES: To determine whether erythritol suppresses the growth of Staphylococcus hyicus, a major pathogen causing porcine exudative epidermitis, and to investigate the molecular mechanisms involved in erythritol-induced S. hyicus growth suppression. MATERIALS AND METHODS: An in vitro turbidity assay was performed to assess the effect of erythritol on the growth of 26 S. hyicus strains, including a reference strain JCM 2423 and the 25 wild strains isolated from pigs. Differentially expressed genes in response to erythritol in JCM 2423 were identified by RNA-Seq and quantitative reverse transcription-PCR. The impact of trehalose, glucose and arginine supplementation on erythritol-induced growth suppression of the 25 S. hyicus wild strains was also investigated. RESULTS: Erythritol suppressed the in vitro growth of JCM 2423 and the 25 S. hyicus wild strains. Moreover, erythritol upregulated the transcription of multiple genes in JCM 2423, including those encoding ATP-binding cassette transporter enzymes (potB, potC and potD), arginine biosynthetic pathway enzymes (argF, argG and argH), l-arginine deiminase pathway enzymes (arcA, arcC and arcD), fatty acid metabolism pathway enzymes (fabH and fabF) and trehalose metabolism-related proteins (treC, treR and treP). Supplementation of trehalose or glucose in aerobic conditions or arginine supplementation in anaerobic conditions restored in vitro growth of the 25 S. hyicus wild strains treated by erythritol. CONCLUSIONS AND CLINICAL RELEVANCE: Erythritol suppresses the in vitro growth of S. hyicus by inhibiting intracellular sugar and arginine metabolism under aerobic and anaerobic conditions, respectively.

BACKGROUND: Ventilator-associated pneumonia (VAP) after tracheal intubation is a major infectious complication in patients in the intensive care unit (ICU), with an incidence of 8-28%. Oral care in the ICU is essential; however, the presence of an intubation tube and restricted mouth opening cause complications. A healthy commensal microflora in the oral cavity resists colonization by respiratory pathogens, and poor oral hygiene may increase the risk for VAP. In this study, we examined the effectiveness of oral care on oral bacterial counts and microbial diversity in patients admitted to the ICU. METHODS: Fifteen ICU patients were included in this study. Oral microbiome samples were collected by swabbing the surface of the tongue. Oral bacterial counts were measured at four time points: before and after oral care, both pre- and post-extubation. Additionally, microbiome analysis was conducted twice: once before oral care pre-extubation, and once before oral care post-extubation. Oral bacterial counts were assessed using a bacterial counter, and microbiome analysis was performed through 16S rRNA gene amplicon sequencing. RESULTS: Oral bacterial counts significantly decreased after oral care at both pre- and post-extubation time points. Microbiome analysis revealed significant differences in alpha diversity pre- and post-extubation samples. Samples post extubation were less diverse. CONCLUSIONS: This study demonstrates that oral care effectively reduces bacterial counts in ICU patients, both pre- and post-extubation. Microbiome analysis revealed shifts in microbial diversity, suggesting that the oral microbiota was disrupted during intubation. Given the risk of VAP, oral care may play an important role to prevent VAP in ICU settings.

INTRODUCTION: Gastrectomy considerably affects the gut microbiome; however, the association between dysbiosis and post-gastrectomy syndrome remains to be explored. This study prospectively explored fecal gut microbiota alterations before and 3 months after gastrectomy, investigating their potential association with weight loss. METHODS: The gut microbiome of 21 patients with gastric cancer scheduled for gastrectomy in April-October 2022 was analyzed using 16S rRNA gene Next-Generation Sequencing. Their microbiome profiles were compared to those of healthy controls. Bacterial taxa demonstrating significant changes were determined using the Linear Discriminant Analysis Effect Size algorithm and further analyzed for their relationship with weight loss in the gastrectomy cohort. RESULTS: Postoperative complications (≥grade 2) were observed in 14.3% of patients. Postoperative weight loss was －10.9%, with the following breakdown: distal (－7.0%), total (－13.5%), and proximal (－14.0%) gastrectomy (P = 0.003). Microbiota analysis demonstrated a significant incline in the abundance of the Streptococcus salivarius group and a decline in Bacteroides uniformis in patients with gastric cancer compared to healthy controls. The S. salivarius group exhibited a further increase, while B. uniformis showed signs of recovery after gastrectomy. Additionally, 5α-reductase gene levels, reported to decrease as several cancers progress, were found to elevate post-surgery. Furthermore, patients experiencing greater weight loss showed a significant reduction in Faecalibacterium prausnitzii levels, while lower serum prealbumin and zinc levels were associated with the abundance of Escherichia coli. CONCLUSION: Gastrectomy significantly alters the gut microbiome. Supporting microbiome health with prebiotics may help alleviate postoperative issues and improve patients' quality of life.