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As a result of the critical analysis of the taxonomy of the genus Anemone L. during a lot of years, we accepted this genus as includes 16 subgenera, 18 sections, 5 subsections, 27 series and 118 species. Within the genus Anemone we firstly proposed 7 genus, 1 subgenus, 2 section, and 13 series, and we re-examined the status of about 30 species and intraspecific taxa. We presented here the annotated conspect of the genus Anemone.

Here we re-examined the literature on the genus Anemone L. taxonomy as the largest and most complicated within the family Ranunculaceae Juss. because its state, species content and intergeneric structure (dividing on sections and other taxa) were debatable during a lot of years. As a result of our critical examination of the characters being in use for Anemone taxonomy (approximately 25 ones) and the own analyse of ca. 70 characters of fruits, flowers, leaves, aboveground and underground shoots and roots, we selected the characters the most essential for the taxonomy of the genus Anemone which we revised in the next parts of our manuscript.

The hemagglutinating virus of Japan envelope (HVJ-E) is an inactivated Sendai virus particle with antitumor effect and inducing antitumor immunity. However, its dosage and efficacy have not been verified. We conducted a phase I clinical study on chemotherapy-resistant malignant pleural mesothelioma (MPM) aiming to determine the recommended dosage for a phase II study through dose-limiting toxicity and evaluate HVJ-E's preliminary efficacy. HVJ-E was administered intratumorally and subcutaneously to the patients with chemotherapy-resistant MPM. While no serious adverse events occurred, known adverse events of HVJ-E were observed. In the preliminary antitumor efficacy using modified response evaluation criteria in solid tumors (RECIST) criteria, three low-dose patients exhibited progressive disease, while all high-dose patients achieved stable disease, yielding disease control rates (DCRs) of 0% and 100%, respectively. Furthermore, the dose-dependent effect of HVJ-E revealed on DCR modified by RECIST and the baseline changes in target lesion size (by CT and SUL-peak; p < 0.05). Comparing targeted lesions receiving intratumoral HVJ-E with non-injected ones, while no clear difference existed at the end of the study, follow-up cases suggested stronger antitumor effects with intratumoral administration. Our findings suggest that HVJ-E could be safely administered to patients with chemotherapy-resistant MPM at both study doses. HVJ-E exhibited some antitumor activity against chemotherapy-resistant MPM, and higher doses tended to have stronger antitumor effects than lower doses. Consequently, a phase II clinical trial with higher HVJ-E doses has been conducted for MPM treatment. Trial registration number: UMIN Clinical Trials Registry (#UMIN000019345)., (© 2024. The Author(s).)

Activin A promotes the development of endometriotic lesions in a murine model of endometriosis, and the immunohistochemical localization of phosphorylated suppressor of mothers against decapentaplegic homolog 2/3 (pSMAD2/3) complex in endometriotic lesions has been reported. Activin may therefore be involved in the development and proliferation of endometriotic cells via the SMAD signaling pathway. However, few detailed reports exist on SMAD7 expression in endometriosis. The purpose of this study was to investigate the expression of pSMAD2/3 or pSMAD3 and SMAD7 in the orthotopic human endometrium, ovarian endometriosis, and endometriotic lesions in a murine model and the effect of activin A on pSMAD2/3 and SMAD7 expression. We established an endometriosis murine model via the intraperitoneal administration of endometrial tissue and blood from donor mice. Activin A was intraperitoneally administered to the activin group. We immunohistochemically evaluated orthotopic endometria, ovarian endometriotic tissues, and endometriotic lesions in the murine model followed by western blotting. We found that pSMAD3 and SMAD7 were expressed in ovarian endometriosis and orthotopic endometria from patients with and without endometriosis. In the murine model, endometriotic lesions expressed pSMAD2/3 and SMAD7 in the activin and control groups, and higher SMAD7 expression was found in the activin group. To the best of our knowledge, this study is the first to show that SMAD7 expression is upregulated in endometriosis. In conclusion, these results suggest that activin A activates the SMAD signaling pathway and promotes the development of endometriotic lesions, thus identifying SMAD7 as a potential therapeutic target for endometriosis.

Cell-surface receptors play pivotal roles in many biological processes, including immunity, development, and reproduction, across diverse organisms. How cell-surface receptors evolve to become specialised in different biological processes remains elusive. To shed light on the immune-specificity of cell-surface receptors, we analyzed more than 200,000 genes encoding cell-surface receptors from 350 genomes and traced the evolutionary origin of immune-specific leucine-rich repeat receptor-like proteins (LRR-RLPs) in plants. Surprisingly, we discovered that the motifs crucial for co-receptor interaction in LRR-RLPs are closely related to those of the LRR-receptor-like kinase (RLK) subgroup Xb, which perceives phytohormones and primarily governs growth and development. Functional characterisation further reveals that LRR-RLPs initiate immune responses through their juxtamembrane and transmembrane regions, while LRR-RLK-Xb members regulate development through their cytosolic kinase domains. Our data suggest that the cell-surface receptors involved in immunity and development share a common origin. After diversification, their ectodomains, juxtamembrane, transmembrane, and cytosolic regions have either diversified or stabilised to recognise diverse ligands and activate differential downstream responses. Our work reveals a mechanism by which plants evolve to perceive diverse signals to activate the appropriate responses in a rapidly changing environment., (© 2024. The Author(s).)

Perception of pathogen-associated molecular patterns (PAMPs) by surface-localized pattern recognition receptors activates RESPIRATORY BURST OXIDASE HOMOLOG D (RBOHD) through direct phosphorylation by BOTRYTIS-INDUCED KINASE 1 (BIK1) and induces the production of reactive oxygen species (ROS). RBOHD activity must be tightly controlled to avoid the detrimental effects of ROS, but little is known about RBOHD downregulation. To understand the regulation of RBOHD, we used co-immunoprecipitation of RBOHD with mass spectrometry analysis and identified PHAGOCYTOSIS OXIDASE/BEM1P (PB1) DOMAIN-CONTAINING PROTEIN (PB1CP). PB1CP negatively regulates RBOHD and the resistance against the fungal pathogen Colletotrichum higginsianum. PB1CP competes with BIK1 for binding to RBOHD in vitro. Furthermore, PAMP treatment enhances the PB1CP-RBOHD interaction, thereby leading to the dissociation of phosphorylated BIK1 from RBOHD in vivo. PB1CP localizes at the cell periphery and PAMP treatment induces relocalization of PB1CP and RBOHD to the same small endomembrane compartments. Additionally, overexpression of PB1CP in Arabidopsis leads to a reduction in the abundance of RBOHD protein, suggesting the possible involvement of PB1CP in RBOHD endocytosis. We found PB1CP, a novel negative regulator of RBOHD, and revealed its possible regulatory mechanisms involving the removal of phosphorylated BIK1 from RBOHD and the promotion of RBOHD endocytosis., (© 2023 The Authors New Phytologist © 2023 New Phytologist Foundation.)

Probiotics such as bifidobacteria have been given to low-birth-weight neonates (LBWNs) at risk for a disrupted gut microbiota leading to the development of serious diseases such necrotizing enterocolitis. Recently prebiotics such as lactulose are used together with bifidobacteria as synbiotics. However, faster and more powerful bifidobacteria growth is desired for better LBWN outcomes. The prebiotic 1-kestose has a higher selective growth-promoting effect on bifidobacteria and lactic acid bacteria in vitro among several oligosaccharides. Twenty-six premature neonates (less than 2,000 g) admitted to a neonatal intensive care unit (NICU) were randomly assigned to receive Bifidobacterium breve M16-V with either 1-kestose or lactulose once a day for four weeks from birth. A 16S rRNA gene analysis revealed similar increases in alpha-diversity from 7 to 28 days in both groups. The most dominant genus on both days was Bifidobacterium in both groups, with no significant difference between the two groups. Quantitative PCR analysis revealed that the number of Staphylococcus aureus tended to be lower in the 1-kestose group than in the lactulose group at 28 days. The number of Escherichia coli was higher in the 1-kestose group at 7 days. The copy number of total bacteria in the 1-kestose group was significantly higher than that in the lactulose group at 3 time points, 7, 14, and 28 days. No severe adverse events occurred in either group during the study period. l-Ketose may offer an alternative option to lactulose as a prebiotic to promote the development of gut microbiota in LBWNs., Competing Interests: M. Takahashi, Y. Kadota, and T. Tochio are employed by B Food Science Co., Ltd., which produces the 1-kestose used in the present study. This study was funded by B Food Science Co., Ltd., (©2024 BMFH Press.)

Chronic inflammation in adipose tissue is thought to contribute to insulin resistance, which involves the gut microbiota. Our previous studies have demonstrated that ingestion of 1-kestose can alter the gut microbiota composition, increase cecal butyrate levels, and improve insulin resistance in Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Additionally, we found that 1-kestose supplementation ameliorated insulin resistance in obese rat models fed a high-fat diet (HFD), although the effects of 1-kestose on the abundance of inflammation-related gene in adipose tissue and gut microbiota composition in these rats were not explored. This study aimed to investigate the impact of 1-kestose on these parameters in HFD-fed rats, compared to OLETF rats. Male Sprague-Dawley rats were divided into two dietary groups, control or HFD, for 19 wk. Each group was further subdivided to receive either tap water or tap water supplemented with 2% (w/v) 1-kestose throughout the study. We evaluated gene expression in adipose tissue, as well as short-chain fatty acids (SCFAs) levels and microbial composition in the cecum contents. 1-Kestose intake restored the increased relative abundance of tumor necrosis factor (Tnf) mRNA in adipose tissue and the reduced level of butyrate in the cecum contents of HFD-fed rats to those observed in control diet-fed rats. Additionally, 1-kestose consumption changed the composition of the gut microbiota, increasing Butyricicoccus spp., decreasing UGC-005 and Streptococcus spp., in the cecum contents of HFD-fed rats. Our findings suggest that 1-kestose supplementation reduces adipose tissue inflammation and increases butyrate levels in the gut of HFD-fed rats, associated with changes in the gut microbiota composition, distinct from those seen in OLETF rats.

1-Kestose (KES), a dietary fiber and prebiotic carbohydrate, benefits various physiological functions. This study aimed to examine whether diets supplemented with KES over three consecutive generations could significantly affect some host physiological aspects, including behavioral phenotypes and gut microbial ecology. Mice that received KES-supplemented diets for three generations demonstrated increased activity compared with those fed diets lacking KES. Furthermore, the KES group showed increased striatal dopamine (DA) and serotonin (5-HT) levels. The observed increase in DA levels within the striatum was positively correlated with locomotor activity in the KES group but not in the control (CON) group. The α-diversities were significantly lower in the KES group compared to the CON group. The three-dimensional principal coordinate analysis revealed a substantial distinction between the KES and CON groups across each generation. At the genus level, most gut microbiota genera exhibited lower abundances in the KES group than in the CON group, except for Bifidobacteria and Akkermansia. Spearman's rank-order analysis indicated significant negative correlations between the striatal DA levels and α-diversity values. These findings suggest that prolonged supplementation with KES may stimulate increased locomotor activity along with elevated striatal DA levels, which are potentially associated with KES-induced alterations in the gut microbiota., (© 2023 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Introduction: Perioperative treatment in NSCLC has gained marked attention with the introduction of immune checkpoint inhibitors. Such a paradigm shift has given us additional opportunities to evaluate potential biomarkers in patients with these curable disease stages., Methods: This study (WJOG12319LTR) was designed as a biomarker study to evaluate whether soluble immune markers were prognostic or predictive on relapse-free survival in patients with stage II to IIIA NSCLC who underwent complete resection and adjuvant chemotherapy with cisplatin plus S-1, which is an oral fluoropyrimidine formulation that consists of tegafur, gimeracil, and oteracil, or S-1 alone in the previous WJOG4107 study. Archived plasma samples were assayed for soluble (s) forms of programmed cell death protein 1 (sPD-1), programmed death-ligand 1(sPD-L1), and CTLA-4 (sCTLA-4) with the highly sensitive HISCL system. Using time-dependent receiver operating characteristic curve analysis, the area under the curves were derived and optimal cutoff values were determined. Using the cutoff values, whether the marker was prognostic or predictive was assessed by survival analysis., Results: A total of 150 patients were included in the study. The time-dependent receiver operating characteristics analysis revealed that the area under the curves for sPD-1, sPD-L1, and sCTLA-4 were 0.54, 0.51, and 0.58, respectively. The survival analysis did not reject that hazard ratios were 1 in terms of the soluble immune marker and the treatment-marker interaction for all three markers., Conclusions: There was no proof that circulating concentrations of sPD-1, sPD-L1, and sCTLA-4 were prognostic or predictive factors of the outcome for adjuvant chemotherapy after complete resection in patients with NSCLC., (© 2023 The Authors.)

A single-arm study was conducted with 10 children aged 2-12 years with severe cow's milk allergy (CMA) requiring complete allergen elimination. Subjects were administered kestose, a prebiotic, at 1 or 2 g/day for 12 weeks. Results of a subsequent oral food challenge (OFC) showed a statistically significant increase in the total dose of cow's milk ingestion (1.6 ml vs. 2.7 ml, p = 0.041). However, the overall evaluation of the OFC results, TS/Pro (total score of Anaphylaxis Scoring Aichi (ASCA)/cumulative dose of protein), showed no statistically significant improvement, although the values were nominally improved in seven out of 10 subjects. The 16S rDNA analysis of fecal samples collected from the subjects revealed a statistically significant increase in the proportion of Faecalibacterium spp. (3.8 % vs. 6.8%, p = 0.013), a type of intestinal bacterium that has been reported to be associated with food allergy. However, no statistically significant correlation was found between Faecalibacterium spp. abundance and the results of the OFC., (© 2023 Shohei Kubota et al., published by Sciendo.)

Background: Interventions targeting the gut microbiota for treating food allergy (FA) have been gaining much attention. Although several studies have examined the effects of probiotics, few have verified the effects of prebiotic intervention on FA in humans., Methods: We conducted a preliminary open-label, parallel-group comparison trial in children diagnosed with severe cow's milk allergy (CMA) who were instructed to ingest baked milk (BM; bread or cookies) daily. The subjects either received or did not receive the prebiotic 1-kestose (kestose) daily for 6 months. CMA symptoms and the threshold dose for milk protein were evaluated by oral food challenge with heated milk or BM. Blood and fecal samples were also collected for investigations of the antigen-specific immunoglobulin (Ig) E levels and microbiota composition., Results: Kestose treatment significantly increased the threshold dose for milk protein, and decreased the milk- and casein-specific IgE levels in serum. In those treated with kestose, the abundance of Fusicatenibacter spp. significantly increased in the feces, and a significant inverse correlation was seen between the abundance of Fusicatenibacter spp. and the milk- and casein-specific IgE levels., Conclusion: Kestose treatment induced some tolerance to milk protein via changes in the gut microbiota composition in children with FA., Impact: A 6-month treatment with the prebiotic kestose increased the threshold dose for milk protein, and decreased the serum levels of milk- and casein-specific IgE in children diagnosed with cow's milk allergy. The kestose treatment increased the abundance of Fusicatenibacter spp. in the gut, which was inversely correlated with the antigen-specific IgE levels. This is the first study to demonstrate that a prebiotic intervention induced some tolerance to an allergen in children with food allergy., (© 2023. The Author(s), under exclusive licence to the International Pediatric Research Foundation, Inc.)

Constipation is common in children and can significantly affect quality of life. Prebiotics are reportedly helpful for constipation in adults, but few studies have examined their use in young children. In this study, the effect of 1-kestose (kestose), which has excellent bifidobacterial growth properties, on constipation in kindergarten children ( n = 11) was compared with that of maltose ( n = 12) in a randomized, double-blind study. Three grams of kestose per day for 8 weeks did not affect stool properties, but significantly increased the number of defecations per week (Median; 3 → 4 times/week, p = 0.017, effect size = 0.53). A significant decrease in Intestinibacter , a trend toward increased bifidobacteria, and a trend toward decreased Clostridium sensu stricto were observed after kestose ingestion, while concentrations of short-chain fatty acids in stools were unchanged.

Background: Ulcerative colitis involves an excessive immune response to intestinal bacteria. Whether administering prebiotic 1-kestose is effective for active ulcerative colitis remains controversial., Aims: This randomised, double-blind, placebo-controlled pilot trial investigated the efficacy of 1-kestose against active ulcerative colitis., Methods: Forty patients with mild to moderate active ulcerative colitis were randomly treated with 1-kestose (N = 20) or placebo (maltose, N = 20) orally for 8 weeks in addition to the standard treatment. The Lichtiger clinical activity index and Ulcerative Colitis Endoscopic Index of Severity were determined. Faecal samples were analysed to evaluate the gut microbiome and metabolites., Results: The clinical activity index at week 8 was significantly lower in the 1-kestose group than in the placebo group (3.8 ± 2.7 vs. 5.6 ± 2.1, p = 0.026). Clinical remission and response rates were higher in the 1-kestose group than in the placebo group (remission: 55% vs. 20%, p = 0.048; response: 60% vs. 25%, p = 0.054). The Ulcerative Colitis Endoscopic Index of Severity at week 8 was not significantly different (2.8 ± 1.6 vs. 3.5 ± 1.6, p = 0.145). Faecal analysis showed significantly reduced alpha-diversity in the 1-kestose group, with a decreased relative abundance of several bacteria, including Ruminococcus gnavus group. The short-chain fatty acid levels were not significantly different between the groups. The incidence of adverse events was comparable between the groups., Discussion: Oral 1-kestose is well tolerated and provides clinical improvement for patients with mild to moderate ulcerative colitis through modulation of the gut microbiome., (© 2023 John Wiley & Sons Ltd.)

Metallothionein (MT) 1 and 2 are ubiquitously expressed cysteine-rich, low molecular weight proteins. MT expression is upregulated in skeletal muscle during aging. MTs also play role in multiple types of skeletal muscle atrophy. Meanwhile, it has been reported that MT1 and MT2 gene deficiency increases myogenesis in MT knockout (MTKO) mice. However, little is known about the effect of MTs on muscle formation and atrophy. In this study, we investigated the effect of MT1 and MT2 gene knock-out using the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (CRISPR-Cas9) system in an in vitro skeletal muscle differentiation model (C2C12 cell line). MT deficiency promoted myogenic differentiation and myotube formation in C2C12 cells. Muscle-specific transcription factors MyoD and myogenin were found to be upregulated at the late stage of myotube differentiation in MTKO cells. Furthermore, the fast-twitch myosin heavy chain (MyHC) protein expression was similar in MTKO and mock-transfected myotubes, but slow-MyHC expression was higher in MTKO cells than in mock cells. The MT gene deletion did not affect the number of fast MyHC-positive myotubes but increased the number of slow MyHC-positive myotubes. Treatment with the antioxidant N-acetylcysteine (NAC) inhibited the increase in the number of slow MyHC-positive myotubes as well as slow-MyHC expression in MTKO cells. In contrast, NAC treatment did not alter the number of fast MyHC-positive myotubes or the expression of fast-MyHC in MTKO cells. These results suggest that the antioxidant effects of MTs may be involved in slow-twitch myofiber formation in skeletal muscle.

By comparing germ-free mice and specific pathogen-free mice, we recently demonstrated that the presence of gut commensals upregulates microRNA-200 family members in lamina propria leukocytes (LPL) of the murine large intestine. The present study tested whether the consumption of 1-kestose (KES), an indigestible oligosaccharide that alters gut microbiota composition, influences the microRNA expression in the LPL. Supplementation of KES (4%) in drinking water for 2 wk increased the levels of miR-182-5p, -205-5p, -290a-5p, miR-200 family members (miR-141-3p, -200a-3p, -200b-3p, -200c-3p, and -429-3p) as well as miR-192/215 family members (miR-192-5p, -194-5p, and -215-5p) as determined by microarray analysis in large intestinal LPL of C57BL/6 mice. Quantitative reverse transcription-PCR further confirmed the increase in miR-192-5p, -194-5p, -200a-3p, -200b-3p, -200c-3p, -205-5p, and 215-5p. KES consumption significantly increased Bifidobacterium pseudolongum in the cecal contents. In a separate experiment, intragastric administration of B. pseudolongum (10 9 CFU/d) for 7 d increased the levels of miR-182-5p, -194-5p, and -200a-3p and tended to increase the levels of miR-200b-3p, -215-5p, and -429-3p. These results suggest that dietary KES influences miRNA expression in the large intestinal LPL, which may be associated with the increased population of B. pseudolongum.

Objective: The mesoderm-specific transcript (Mest) is an imprinted gene that is transcribed from the paternal allele. It is a marker of adipose tissue expansion; however, it is uncertain whether Mest expression promotes or suppresses adipogenic differentiation. To elucidate the effects of Mest expression on adipogenic differentiation, we transfected an expression vector or siRNA for mouse Mest into 3T3-L1 mouse preadipocyte cell line., Results: In differentiated 3T3-L1 adipocytes, Mest overexpression decreased lipid accumulation. Conversely, gene silencing of Mest increased the accumulation of lipid droplets in adipocytes. These results demonstrate that Mest negatively regulates adipocyte differentiation. Further, Mest induced trans-differentiation of 3T3-L1 cells into hepatocytes, and its overexpression induced the expression of hepatocyte marker genes, including albumin and α-fetoprotein. In the presence of dexamethasone, the forced expression of the Mest caused morphological changes in 3T3-L1 cells. Cells were flat and polygonal shapes, with an increased accumulation of intracellular glycogen and other features that are typical of hepatocytes. Therefore, Mest inhibits adipogenic differentiation of 3T3-L1 preadipocytes by inducing hepatocyte trans-differentiation., (© 2022. The Author(s).)

Although the pathogenesis of chronic obstructive pulmonary disease (COPD) is not yet fully understood, recent studies suggest that the disruption of the intracellular balance of oxidative (such as reactive oxygen species (ROS)) and antioxidant molecules plays an important role in COPD development and progression. Metallothionein is an endogenous metal-binding protein with reported ROS scavenging activity. Although there have been many publications on the protective effects of metallothionein in the kidney and liver, its role in COPD models such as elastase- or cigarette smoke (CS)-induced lung injury is unknown. Thus, in the present study, we analyzed the elastase-induced lung injury model using metallothionein-knockout (MT-KO; MT-1 and -2 gene deletion) mice. The expression of MT-1 and MT-2 in the lungs of MT-KO mice was markedly lower compared with that in the lungs of wildtype (WT) mice. Porcine pancreatic elastase (PPE)-induced lung injury (alveolar enlargement and respiratory impairment) was significantly exacerbated in MT-KO mice compared with WT mice. Additionally, PPE-induced increases in the number of inflammatory cells, inflammatory cytokines, and cell death in lung tissue were significantly more pronounced in MT-KO mice compared with WT mice. Finally, using an in vivo imaging system, we also found that PPE-induced ROS production in the lungs was enhanced in MT-KO mice compared with WT mice. These results suggest that metallothionein may act as an inhibitor against elastase-induced lung injury by suppressing ROS production. These results suggest that metallothionein protein, or compounds that can induce metallothionein, could be useful in the treatment of COPD.

Introduction: The prognosis of non-small cell lung cancer greatly depends on the presence of lymph node metastasis, which limits the need for surgery and adjuvant therapy for advanced cancer. One-step nucleic acid amplification of cytokeratin19 (CK19) mRNA was used to detect lymph node metastasis. Automated Gene Amplification Detector RD-200 and the LYNOAMP CK19 gene amplification reagent as components of the new one-step nucleic acid amplification system, which has increased gene amplification efficiency by improving the reagent composition, have shorter preprocessing and measurement times than conventional systems. We aimed to compare the clinical performance of the new system with that of histopathology and the conventional system., Materials and Methods: 199 lymph nodes from 58 non-small cell lung cancer patients who underwent lymph node dissection were examined intraoperatively using the new system, conventional system, and histopathology., Results: Lymph node metastasis was diagnosed in 32, 42, and 44 patients using histopathological analysis, the new system, and the conventional system, respectively. Compared with histopathological analysis, the concordance rate, sensitivity, specificity, positive predictive value, and negative predictive value of the new system were 92.0%, 90.6%, 92.2%, 69.0%, and 98.1%, respectively, and compared with the conventional system, the values were 95.0%, 86.4%, 97.4%, 90.5%, and 96.2%, respectively., Conclusion: The clinical performance of the new one-step nucleic acid amplification system in detecting lymph node metastasis of lung cancer is comparable to that of histopathology and the conventional system; its performance was sufficient for determining the appropriate clinical treatment. The new rapid system can be effectively utilized during lung cancer treatment intraoperatively and postoperatively., Competing Interests: Naoko Ose, Yasushi Shintani, Yukiyasu Takeuchi, Yasushi Sakamaki and Yoshihisa Kadota had grant support from Sysmex Corp. and Mayuko Noguchi is an employee of Sysmex Corp. Hiromi Tsuji, Kunimitsu Kawahara and Kenji Urasaki declare no conflicts of interest. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

SCFA increase serotonin (5-hydroxytryptamine, 5-HT) synthesis and content in the colon in vitro and ex vivo, but little is known in vivo. We tested whether dietary indigestible saccharides, utilised as a substrate to produce SCFA by gut microbiota, would increase colonic 5-HT content in mice. Male C57BL/6J mice were fed a purified diet and water supplemented with 4 % (w/v) 1-kestose (KES) for 2 weeks. Colonic 5-HT content and enterochromaffin (EC) cell numbers were lower in mice supplemented with KES than those without supplementation, while monoamine oxidase A activity and mRNA levels of tryptophan hydroxylase 1 (Tph1), chromogranin A (Chga), Slc6a4 and monoamine oxidase A (Maoa) genes in the colonic mucosa, serum 5-HT concentration and total 5-HT content in the colonic contents did not differ between groups. Caecal acetate concentration and Bifidobacterium pseudolongum population were higher in KES-supplemented mice. Similar trends were observed in mice supplemented with other indigestible saccharides, that is, fructo-oligosaccharides, inulin and raffinose. Intragastric administration of live B. pseudolongum (108 colony-forming units/d) for 2 weeks reduced colonic 5-HT content and EC cell numbers. These results suggest that changes in synthesis, reuptake, catabolism and overflow of 5-HT in the colonic mucosa are not involved in the reduction of colonic 5-HT content by dietary indigestible saccharides in mice. We propose that gut microbes including B. pseudolongum could contribute to the reduction of 5-HT content in the colonic mucosa via diminishing EC cells.