Oral supplementation of Bifidobacterium longum strain BR-108 alters cecal microbiota by stimulating gut immune system in mice irrespectively of viability

Effect on cecal microbiota and gene expression of various cytokines in ileal Peyer’s patches and cecal tissues were compared between viable and heat-killed Bifidobacterium longum strain BR-108 (BR-108) using a mouse model. Irrespectively of viability, oral supplementation of BR-108 altered the cecal microbiota and stimulated gene expression of cytokines such as IL-6 and IL-10 in ileal Peyer’s patches and cecal tissue of mice. In addition, BR-108 supplementation significantly affected the relative abundance of bacterial genera and family, Oscillospira, Bacteroides and S24-7. The abundance of these bacterial genera and family strongly correlated with gene expression induced by BR-108. This study demonstrated that the effect of heat-killed BR-108 on the mouse cecal microbiota is similar to that of viable BR-108, most likely due to stimulation of the gut immune system by both heat-killed and viable BR-108 is also similar.     

Dietary intake of the citrus flavonoid hesperidin affects stress-resilience and brain kynurenine levels in a subchronic and mild social defeat stress model in mice

ABSTRACT

Depressive disorders are partly caused by chronic inflammation through the kynurenine (KYN) pathway. Preventive intervention using anti-inflammatory reagents may be beneficial for alleviating the risk of depression. In this study, we focused on the Japanese local citrus plant, Citrus tumida hort. ex Tanaka (C. tumida; CT), which contains flavonoids such as hesperidin that have anti-inflammatory actions. The dietary intake of 5% immature peels of CT fruits slightly increased stress resilience in a subchronic and mild social defeat (sCSDS) model in mice. Moreover, the dietary intake of 0.1% hesperidin significantly increased stress resilience and suppressed KYN levels in the hippocampus and prefrontal cortex in these mice. In addition, KYN levels in the hippocampus and prefrontal cortex were significantly correlated with the susceptibility to stress. In conclusion, these results suggest that dietary hesperidin increases stress resilience by suppressing the augmentation of KYN signaling under sCSDS.     

Expression of Human Paraoxonase 1 Decreases Superoxide Levels and Alters Bacterial Colonization in the Gut of Drosophila melanogaster

Paraoxonases (PON) are a family of proteins (PON1, 2 and 3) with multiple enzymatic activities. PON1 interferes with homoserine lactone-mediated quorum sensing in bacteria and with reactive oxygen species (ROS) in humans and mice. PON1 gene mutations have been linked to multiple traits, including aging, and diseases of the cardiovascular, nervous and gastrointestinal system. The overlapping enzymatic activities in the PON family members and high linkage disequilibrium rates within their polymorphisms confound animal and human studies of PON1 function. In contrast, arthropods such as Drosophila melanogaster have no PON homologs, resulting in an ideal model to study interactions between PON genotype and host phenotypes. We hypothesized that expression of PON1 in D. melanogaster would alter ROS. We found that PON1 alters expression of multiple oxidative stress genes and decreases superoxide anion levels in normal and germ-free D. melanogaster. We also found differences in the composition of the gut microbiota, with a remarkable increase in levels of Lactobacillus plantarum and associated changes in expression of antimicrobial and cuticle-related genes. PON1 expression directly decreased superoxide anion levels and altered bacterial colonization of the gut and its gene expression profile, highlighting the complex nature of the interaction between host genotype and gut microbiota. We speculate that the interaction between some genotypes and human diseases may be mediated by the presence of certain gut bacteria that can induce specific immune responses in the gut and other host tissues.     

Correction: N-3 Polyunsaturated Fatty Acids (PUFAs) Reverse the Impact of Early-Life Stress on the Gut Microbiota

Background

Early life stress is a risk factor for many psychiatric disorders ranging from depression to anxiety. Stress, especially during early life, can induce dysbiosis in the gut microbiota, the key modulators of the bidirectional signalling pathways in the gut-brain axis that underline several neurodevelopmental and psychiatric disorders. Despite their critical role in the development and function of the central nervous system, the effect of n-3 polyunsaturated fatty acids (n-3 PUFAs) on the regulation of gut-microbiota in early-life stress has not been explored.

Methods and Results

Here, we show that long-term supplementation of eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) (80% EPA, 20% DHA) n-3 PUFAs mixture could restore the disturbed gut-microbiota composition of maternally separated (MS) female rats. Sprague-Dawley female rats were subjected to an early-life stress, maternal separation procedure from postnatal days 2 to 12. Non-separated (NS) and MS rats were administered saline, EPA/DHA 0.4 g/kg/day or EPA/DHA 1 g/kg/day, respectively. Analysis of the gut microbiota in adult rats revealed that EPA/DHA changes composition in the MS, and to a lesser extent the NS rats, and was associated with attenuation of the corticosterone response to acute stress.

Conclusions

In conclusion, EPA/DHA intervention alters the gut microbiota composition of both neurodevelopmentally normal and early-life stressed animals. This study offers insights into the interaction between n-3 PUFAs and gut microbes, which may play an important role in advancing our understanding of disorders of mood and cognitive functioning, such as anxiety and depression.     

Enkephalin knockout male mice are resistant to chronic mild stress

Enhanced stress reactivity or sensitivity to chronic stress increases the susceptibility to mood pathologies such as major depression. The opioid peptide enkephalin is an important modulator of the stress response. Previous studies using preproenkephalin knockout (PENK KO) mice showed that these animals exhibit abnormal stress reactivity and show increased anxiety behavior in acute stress situations. However, the consequence of enkephalin deficiency in the reactivity to chronic stress conditions is not known. In this study, we therefore submitted wild‐type (WT) and PENK KO male mice to chronic stress conditions, using the chronic mild stress (CMS) protocol. Subsequently, we studied the CMS effects on the behavioral and hormonal level and also performed gene expression analyses. In WT animals, CMS increased the expression of the enkephalin gene in the paraventricular nucleus (PVN) of the hypothalamus and elevated the corticosterone levels. In addition, WT mice exhibited enhanced anxiety in the zero‐maze test and depression‐related behaviors in the sucrose preference and forced swim tests. Surprisingly, in PENK KO mice, we did not detect anxiety and depression‐related behavioral changes after the CMS procedure, and even measured a decreased hormonal stress response. These results indicate that PENK KO mice are resistant to the CMS effects, suggesting that enkephalin enhances the reactivity to chronic stress.     

Integrated analysis of miRNA and mRNA expression profiles in response to gut microbiota depletion in the abdomens of female Bactrocera dorsalis

Insect gut microbiota has been reported to participate in regulating host multiple biological processes including metabolism and reproduction. However, the corresponding molecular mechanisms remain largely unknown. Recent studies suggest that microRNAs (miRNAs) are involved in complex interactions between the gut microbiota and the host. Here, we used next-generation sequencing technology to characterize miRNA and mRNA expression profiles and construct the miRNA–gene regulatory network in response to gut microbiota depletion in the abdomens of female Bactrocera dorsalis. A total of 3016 differentially expressed genes (DEGs) and 18 differentially expressed miRNAs (DEMs) were identified. Based on the integrated analysis of miRNA and mRNA sequencing data, 229 negatively correlated miRNA–gene pairs were identified from the miRNA–mRNA network. Gene ontology enrichment analysis indicated that DEMs could target several genes involved in the metabolic process, oxidation–reduction process, oogenesis, and insulin signaling pathway. Finally, real-time quantitative polymerase chain reaction further verified the accuracy of RNA sequencing results. In conclusion, our study provides the profiles of miRNA and mRNA expressions under antibiotics treatment and provides an insight into the roles of miRNAs and their target genes in the interaction between the gut microbiota and its host.     

低聚果糖对慢性应激小鼠抑郁样行为及 肠道菌群的影响

目的探讨低聚果糖(FOS)对慢性应激小鼠的抑郁样行为及肠道菌群的影响。方法选取8周龄健康雄性ICR小鼠随机分成3组,C组小鼠每天给予正常护理,S组和SF组小鼠每天随机给予1～2种应激源,持续8周,SF组小鼠在应激造模的同时经食物补充FOS。在造模4周和8周后,分别通过强迫游泳、蔗糖偏好试验评估各组小鼠抑郁样行为。造模结束后通过Western blot试验检测小鼠大脑皮层内糖皮质激素受体(GR)的表达,并收集结肠内容物进行16SrDNA扩增子测序分析。结果应激造模8周后,C、S和SF三组小鼠的肠道菌群组成存在明显差异;与C组相比,S组小鼠强迫游泳的不动时间显著增加(t=3.970,P=0.0009),蔗糖偏好率显著降低(t=3.890,P=0.0011),脑内GR的表达显著降低(t=4.311,P=0.0125);与S组相比,SF组小鼠强迫游泳的不动时间显著缩短(t=3.495,P=0.0026),蔗糖偏好率和脑内GR表达有增加趋势。结论益生元FOS可调节肠道菌群,改善慢性应激诱发的精神情绪异常。     

Mind-altering with the gut: Modulation of the gut-brain axis with probiotics

It is increasingly evident that bidirectional interactions exist among the gastrointestinal tract, the enteric nervous system, and the central nervous system. Recent preclinical and clinical trials have shown that gut microbiota plays an important role in these gut-brain interactions. Furthermore, alterations in gut microbiota composition may be associated with pathogenesis of various neurological disorders, including stress, autism, depression, Parkinson’s disease, and Alzheimer’s disease. Therefore, the concepts of the microbiota-gut-brain axis is emerging. Here, we review the role of gut microbiota in bidirectional interactions between the gut and the brain, including neural, immune-mediated, and metabolic mechanisms. We highlight recent advances in the understanding of probiotic modulation of neurological and neuropsychiatric disorders via the gut-brain axis.     

Bifidobacterium longum supplementation improves age-related delays in fracture repair

Age-related delays in bone repair remains an important clinical issue that can prolong pain and suffering. It is now well established that inflammation increases with aging and that this exacerbated inflammatory response can influence skeletal regeneration. Recently, simple dietary supplementation with beneficial probiotic bacteria has been shown to influence fracture repair in young mice. However, the contribution of the gut microbiota to age-related impairments in fracture healing remains unknown. Here, we sought to determine whether supplementation with a single beneficial probiotic species, Bifidobacterium longum (B. longum), would promote fracture repair in aged (18-month-old) female mice. We found that B. longum supplementation accelerated bony callus formation which improved mechanical properties of the fractured limb. We attribute these pro-regenerative effects of B. longum to preservation of intestinal barrier, dampened systemic inflammation, and maintenance of the microbiota community structure. Moreover, B. longum attenuated many of the fracture-induced systemic pathologies. Our study provides evidence that targeting the gut microbiota using simple dietary approaches can improve fracture healing outcomes and minimize systemic pathologies in the context of aging.     

Fecal metabolite of a gnotobiotic mouse transplanted with gut microbiota from a patient with Alzheimer’s disease

ABSTRACT

Studies of Alzheimer’s disease are based on model mice that have been altered by transgenesis and other techniques to elicit pathogenesis. However, changes in the gut microbiota were recently suggested to diminish cognitive function in patients, as well as in model mice. Accordingly, we have created model mice of the human gut microbiota by transplanting germ-free C57BL/6N mice with fecal samples from a healthy volunteer and from an affected patient. These humanized mice were stably colonized and reproduced the bacterial diversity in donors. Remarkably, performance on Object Location Test and Object Recognition Test was significantly reduced in the latter than in the former at 55 weeks of age, suggesting that gut microbiota transplanted from an affected patient affects mouse behavior. In addition, metabolites related to the nervous system, including γ-aminobutyrate, taurine, and valine, were significantly less abundant in the feces of mice transplanted with microbiota from the affected patient.     

Decreased neuronal Na+, K+ -ATPase activity in Atp1a3 heterozygous mice increases susceptibility to depression-like endophenotypes by chronic variable stress

Unipolar depression and bipolar depression are prevalent and debilitating diseases in need of effective novel treatments. It is becoming increasingly evident that depressive disorders manifest from a combination of inherited susceptibility genes and environmental stress. Genetic mutations resulting in decreased neuronal Na(+) ,K(+) -ATPase (sodium-potassium adenosine triphosphatase) activity may put individuals at risk for depression given that decreased Na(+) ,K(+) -ATPase activity is observed in depressive disorders and animal models of depression. Here, we show that Na(+) ,K(+) -ATPase α3 heterozygous mice (Atp1a3(+/-) ), with 15% reduced neuronal Na(+) ,K(+) -ATPase activity, are vulnerable to develop increased depression-like endophenotypes in a chronic variable stress (CVS) paradigm compared to wild-type littermates (Atp1a3(+/+) ). In Atp1a3(+/+) mice CVS did not decrease Na(+) ,K(+) -ATPase activity, however led to despair-like behavior in the tail suspension test (TST), anhedonia in a sucrose preference test and a minimal decrease in sociability, whereas in Atp1a3(+/-) mice CVS decreased neuronal Na(+) ,K(+) -ATPase activity to 33% of wild-type levels, induced despair-like behavior in the TST, anhedonia in a sucrose preference test, anxiety in the elevated plus maze, a memory deficit in a novel object recognition task and sociability deficits in a social interaction test. We found that a mutation that decreases neuronal Na(+) ,K(+) -ATPase activity interacts with stress to exacerbate depression. Furthermore, we observed an interesting correlation between Na(+) ,K(+) -ATPase activity and mood that may relate to both unipolar depression and bipolar disorder. Pharmaceuticals that increase Na(+) ,K(+) -ATPase activity or block endogenous Na(+) , K(+) -ATPase inhibition may provide effective treatment for depressive disorders and preclude depression in susceptible individuals.     

Influence of dietary aconitine and nicotine on the gut microbiota of two lepidopteran herbivores

The gut microbiota plays an important role in pheromone production, pesticide degradation, vitamin synthesis, and pathogen prevention in the host animal. Therefore, similar to gut morphology and digestive enzyme activity, the gut microbiota may also get altered under plant defensive compound-induced stress. To test this hypothesis, Dendrolimus superans larvae were fed either aconitine- or nicotine-treated fresh leaves of Larix gmelinii, and Lymantria dispar larvae were fed either aconitine- or nicotine-treated fresh leaves of Salix matsudana. Subsequently, the larvae were sampled 72hr after diet administration and DNA extracted from larval enteric canals were employed for gut microbial 16S ribosomal RNA gene sequencing (338 F and 806 R primers). The sequence analysis revealed that dietary nicotine and aconitine influenced the dominant bacteria in the larval gut and determined their abundance. Moreover, the effect of either aconitine or nicotine on D. superans and L. dispar larvae had a greater dependence on insect species than on secondary plant metabolites. These findings further our understanding of the interaction between herbivores and host plants and the coevolution of plants and insects.     

Testosterone has antidepressant-like efficacy and facilitates imipramine-induced neuroplasticity in male rats exposed to chronic unpredictable stress

Hypogonadal men are more likely to develop depression, while testosterone supplementation shows antidepressant-like effects in hypogonadal men and facilitates antidepressant efficacy. Depression is associated with hypothalamic–pituitary–adrenal (HPA) axis hyperactivity and testosterone exerts suppressive effects on the HPA axis. The hippocampus also plays a role in the feedback regulation of the HPA axis, and depressed patients show reduced hippocampal neuroplasticity. We assessed the antidepressant-like effects of testosterone with, or without, imipramine on behavioral and neural endophenotypes of depression in a chronic unpredictable stress (CUS) model of depression. A 21-day CUS protocol was used on gonadectomized male Sprague–Dawley rats treated with vehicle, 1 mg of testosterone propionate, 10 mg/kg of imipramine, or testosterone and imipramine in tandem. Testosterone treatment reduced novelty-induced hypophagia following CUS exposure, but not under non-stress conditions, representing state-dependent effects. Further, testosterone increased the latency to immobility in the forced swim test (FST), reduced basal corticosterone, and reduced adrenal mass in CUS-exposed rats. Testosterone also facilitated the effects of imipramine by reducing the latency to immobility in the FST and increasing sucrose preference. Testosterone treatment had no significant effect on neurogenesis, though the combination of testosterone and imipramine increased PSA-NCAM expression in the ventral dentate gyrus. These findings demonstrate the antidepressant- and anxiolytic-like effects of testosterone within a CUS model of depression, and provide insight into the mechanism of action, which appears to be independent of enhanced hippocampal neurogenesis.     

Antidepressant-like Effect of Bacopaside I in Mice Exposed to Chronic Unpredictable Mild Stress by Modulating the Hypothalamic–Pituitary–Adrenal Axis Function and Activating BDNF Signaling Pathway

Preliminary studies conducted in our laboratory have confirmed that Bacopaside I (BS-I), a saponin compound isolated from Bacopa monnieri, displayed antidepressant-like activity in the mouse behavioral despair model. The present investigation aimed to verify the antidepressant-like action of BS-I using a mouse model of behavioral deficits induced by chronic unpredictable mild stress (CUMS) and further probe its underlying mechanism of action. Mice were exposed to CUMS for a period of 5 consecutive weeks to induce depression-like behavior. Then, oral gavage administrations with vehicle (model group), fluoxetine (12 mg/kg, positive group) or BS-I (5, 15, 45 mg/kg, treated group) once daily were started during the last two weeks of CUMS procedure. The results showed that BS-I significantly ameliorated CUMS-induced depression-like behaviors in mice, as characterized by an elevated sucrose consumption in the sucrose preference test and reduced immobility time without affecting spontaneous locomotor activity in the forced swimming test, tail suspension test and open field test. It was also found that BS-I treatment reversed the increased level of plasma corticosterone and decreased mRNA and protein expressions of glucocorticoid receptor induced by CUMS exposure, indicating that hypothalamic–pituitary–adrenal (HPA) axis hyperactivity of CUMS-exposed mice was restored by BS-I treatment. Furthermore, chronic administration of BS-I elevated expression levels of brain-derived neurotrophic factor (BDNF) (mRNA and protein) and activated the phosphorylation of extracellular signal-regulated kinase and cAMP response element-binding protein in the hippocampus and prefrontal cortex in mice subjected to CUMS procedure. Taken together, these results indicated that BS-I exhibited an obvious antidepressant-like effect in mouse model of CUMS-induced depression that was mediated, at least in part, by modulating HPA hyperactivity and activating BDNF signaling pathway.     

The Effects of Limosilactobacillus reuteri LR-99 Supplementation on Body Mass Index,Social Communication,Fine Motor Function,and Gut Microbiome Composition in Individuals with Prader–Willi Syndrome: a Randomized Double-Blinded Placebo-Controlled Trial

Prader–Willi syndrome (PWS) is a rare genetic disorder associated with developmental delay, obesity, and neuropsychiatric comorbidities. Limosilactobacillus reuteri (Lactobacillus reuteri, Lact. reuteri) has demonstrated anti-obesity and anti-inflammatory effects in previous studies. In the present study, we aim to evaluate the effects of Lact. reuteri supplementation on body mass index (BMI), social behaviors, and gut microbiota in individuals with PWS. We conducted a 12-week, randomized, double-blind, placebo-controlled trial in 71 individuals with PWS aged 6 to 264 months (64.4 ± 51.0 months). Participants were randomly assigned to either receive daily Lact. reuteri LR-99 probiotic (6 × 10¹⁰ colony forming units) or a placebo sachet. Groupwise differences were assessed for BMI, ASQ-3, and GARS-3 at baseline, 6 weeks, and 12 weeks into treatment. Gut microbiome data was analyzed with the QIIME2 software package, and predictive functional profiling was conducted with PICRUSt-2. We found a significant reduction in BMI for the probiotic group at both 6 weeks and 12 weeks relative to the baseline (P < 0.05). Furthermore, we observed a significant improvement in social communication and interaction, fine motor function, and total ASQ-3 score in the probiotics group compared to the placebo group (P < 0.05). Altered gut microbiota was observed in the probiotic group to favor weight loss and improve gut health. The findings suggest a novel therapeutic potential for Lact. reuteri LR-99 probiotic to modulate BMI, social behaviors, and gut microbiota in Prader–Willi syndrome patients, although further investigation is warranted.

Trial registration Chinese Clinical Trial Registry: ChiCTR1900022646