Gut microbiota and gut tissue metabolites involved in development and prevention of depression

Characteristics of gut microbiota and metabolic phenotype in patients with major depressive disorder based on multi-omics analysis

Depression is a chronic, relapsing mental illness, often accompanied by loss of appetite, increased fatigue, insomnia and poor concentration. Here, we performed serum and urine metabolomics and fecal 16S rDNA sequencing studies on 57 unmedicated patients with major depressive disorder (MDD) and 57 healthy controls to characterize the metabolic and flora profile of MDD patients. We observed significant differences in serum and urinary metabolome between MDD patients and healthy individuals. Specifically, glycerophospholipid metabolism, primary bile acid biosynthesis and linoleic acid metabolism were significantly disordered in serum, and aminoacyl-tRNA biosynthesis, arginine biosynthesis, purine metabolism, phenylalanine metabolism, alanine, aspartate and glutamate metabolism, and pyrimidine metabolism were significantly impaired in urine. On this basis, we identified four potential diagnostic biomarkers for carnitine and four fatty acid classes in serum and urine, respectively. In addition, we observed significant disturbances of the gut microbiota in MDD patients. Spearman correlation analysis showed that imbalances in the gut microbiota were associated with metabolic disturbances, suggesting an important role of the gut microbiota in the pathogenesis of MDD. Our study provides a theoretical basis for further understanding of the pathogenesis of depression and for future clinical diagnosis and screening, as well as a basis for targeting the gut flora to optimize its structure for the prevention and treatment of depression.

The role of the gut-microbiota-brain axis via the subdiaphragmatic vagus nerve in chronic inflammatory pain and comorbid spatial working memory impairment in complete Freund's adjuvant mice

Chronic inflammatory pain (CIP) is a common public medical problem, often accompanied by memory impairment. However, the mechanisms underlying CIP and comorbid memory impairment remain elusive. This study aimed to examine the role of the gut-microbiota-brain axis in CIP and comorbid memory impairment in mice treated with complete Freund's adjuvant (CFA). 16S rRNA analysis showed the altered diversity of gut microbiota from day 1 to day 14 after CFA injection. Interestingly, fecal microbiota transplantation (FMT) from healthy naive mice ameliorated comorbidities, such as mechanical allodynia, thermal hyperalgesia, spatial working memory impairment, neuroinflammation, and abnormal composition of gut microbiota in the CFA mice. Additionally, subdiaphragmatic vagotomy (SDV) blocked the onset of these comorbidities. Interestingly, the relative abundance of the bacterial genus or species was also correlated with these comorbidities after FMT or SDV. Therefore, our results suggest that the gut-microbiota-brain axis via the subdiaphragmatic vagus nerve is crucial for the development of CIP and comorbid spatial working memory impairment in CFA mice.

From-Toilet-to-Freezer: A Review on Requirements for an Automatic Protocol to Collect and Store Human Fecal Samples for Research Purposes

The composition, viability and metabolic functionality of intestinal microbiota play an important role in human health and disease. Studies on intestinal microbiota are often based on fecal samples, because these can be sampled in a non-invasive way, although procedures for sampling, processing and storage vary. This review presents factors to consider when developing an automated protocol for sampling, processing and storing fecal samples: donor inclusion criteria, urine-feces separation in smart toilets, homogenization, aliquoting, usage or type of buffer to dissolve and store fecal material, temperature and time for processing and storage and quality control. The lack of standardization and low-throughput of state-of-the-art fecal collection procedures promote a more automated protocol. Based on this review, an automated protocol is proposed. Fecal samples should be collected and immediately processed under anaerobic conditions at either room temperature (RT) for a maximum of 4 h or at 4 °C for no more than 24 h. Upon homogenization, preferably in the absence of added solvent to allow addition of a buffer of choice at a later stage, aliquots obtained should be stored at either -20 °C for up to a few months or -80 °C for a longer period-up to 2 years. Protocols for quality control should characterize microbial composition and viability as well as metabolic functionality.

Antibiotic-induced gut dysbiosis and cognitive, emotional, and behavioral changes in rodents: a systematic review and meta-analysis

There are previous epidemiological studies reporting associations between antibiotic use and psychiatric symptoms. Antibiotic-induced gut dysbiosis and alteration of microbiota-gut-brain axis communication has been proposed to play a role in this association. In this systematic review and meta-analysis, we reviewed published articles that have presented results on changes in cognition, emotion, and behavior in rodents (rats and mice) after antibiotic-induced gut dysbiosis. We searched three databases-PubMed, Web of Science, and SCOPUS to identify such articles using dedicated search strings and extracted data from 48 articles. Increase in anxiety and depression-like behavior was reported in 32.7 and 40.7 percent of the study-populations, respectively. Decrease in sociability, social novelty preference, recognition memory and spatial cognition was found in 18.1, 35.3, 26.1, and 62.5 percent of the study-populations, respectively. Only one bacterial taxon (increase in gut Proteobacteria) showed statistically significant association with behavioral changes (increase in anxiety). There were no consistent findings with statistical significance for the potential biomarkers [Brain-derived neurotrophic factor (BDNF) expression in the hippocampus, serum corticosterone and circulating IL-6 and IL-1β levels]. Results of the meta-analysis revealed a significant association between symptoms of negative valence system (including anxiety and depression) and cognitive system (decreased spatial cognition) with antibiotic intake (p < 0.05). However, between-study heterogeneity and publication bias were statistically significant (p < 0.05). Risk of bias was evaluated to be high in the majority of the studies. We identified and discussed several reasons that could contribute to the heterogeneity between the results of the studies examined. The results of the meta-analysis provide promising evidence that there is indeed an association between antibiotic-induced gut dysbiosis and psychopathologies. However, inconsistencies in the implemented methodologies make generalizing these results difficult. Gut microbiota depletion using antibiotics may be a useful strategy to evaluate if and how gut microbes influence cognition, emotion, and behavior, but the heterogeneity in methodologies used precludes any definitive interpretations for a translational impact on clinical practice.

Eucommiae cortex polysaccharides attenuate gut microbiota dysbiosis and neuroinflammation in mice exposed to chronic unpredictable mild stress: Beneficial in ameliorating depressive-like behaviors

BACKGROUND

Chronic stress alters gut microbiota composition, as well as induces inflammatory responses and behavioral deficits. Eucommiae cortex polysaccharides (EPs) have been reported to remodel gut microbiota and ameliorate obesogenic diet-induced systemic low-grade inflammation, but their role in stress-induced behavioral and physiological changes is poorly understood.

METHODS

Male Institute of Cancer Research (ICR) mice were exposed to chronic unpredictable stress (CUMS) for 4 weeks and then supplemented with EPs at a dose of 400 mg/kg once per day for 2 weeks. Behavioral test-specific antidepressant and anxiolytic effects of EPs were assessed in FST, TST, EPM, and OFT. Microbiota composition and inflammation were detected using 16S ribosomal RNA (rRNA) gene sequencing, quantitative RT-PCR, western blot, and immunofluorescence.

RESULTS

We found that EPs ameliorated gut dysbiosis caused by CUMS, as evidenced by increasing the abundance of Lactobacillaceae and suppressing the expansion of the Proteobacteria, thereby mitigating intestinal inflammation and barrier derangement. Importantly, EPs reduced the release of bacterial-derived lipopolysaccharides (LPS, endotoxin) and inhibited the microglia-mediated TLR4/NFκB/MAPK signaling pathway, thereby attenuating the pro-inflammatory response in the hippocampus. These contributed to restoring the rhythm of hippocampal neurogenesis and alleviating behavioral abnormalities in CUMS mice. Correlation analysis showed that the perturbed-gut microbiota was strongly correlated with behavioral abnormalities and neuroinflammation.

LIMITATIONS

This study did not clarify the causal relationship between EPs remodeling the gut microbiota and improved behavior in CUMS mice.

CONCLUSIONS

EPs exert ameliorative effects on CUMS-induced neuroinflammation and depression-like symptoms, which may be strongly related to their beneficial effects on gut microbial composition.

Gut microbiota and its roles in the pathogenesis and therapy of endocrine system diseases

A new field of microbial research is the relationship between microorganisms and multicellular hosts. It is known that gut microbes can cause various endocrine system diseases, such as diabetes and thyroid disease. Changes in the composition or structure and the metabolites of gut microbes may cause gastrointestinal disorders, including ulcers or intestinal perforation and other inflammatory and autoimmune diseases. In recent years, reports on the interactions between intestinal microorganisms and endocrine system diseases have been increasingly documented. In the meantime, the treatment based on gut microbiome has also been paid much attention. For example, fecal microbiota transplantation is found to have a therapeutic effect on many diseases. As such, understanding the gut microbiota-endocrine system interactions is of great significance for the theranostic of endocrine system diseases. Herein, we summarize the relations of gut microbiome with endocrine system diseases, and discuss the potentials of regulating gut microbiome in treating those diseases. In addition, the concerns and possible solutions regarding the gut microbiome-based therapy are discussed.

Advances in stress and depression research

PURPOSE OF REVIEW

Stress plays a central role in the onset and course of depression. However, only a subset of people who encounter stressful life events go on to experience a depressive episode. The current review highlights recent advances in understanding when, why, and for whom the stress-depression link occurs, and we identify avenues for future research.

RECENT FINDINGS

In the last 18 months, researchers have taken a more nuanced perspective on the biopsychosocial mechanisms critical to the stress-depression link. For example, examination of specific facets of emotion regulation, including emotion regulation flexibility and interpersonal emotion regulation, has been critical to understanding its role in depression. Similarly, refined investigations of social support allowed researchers to identify distinct - and occasionally opposite - outcomes depending on the context or manner in which the support was provided. Researchers also documented that the stress-depression link was enhanced by dysregulation of several stress-sensitive biological systems, such as the immune system, microbiome, endocrine system, and neuroanatomical substrates.

SUMMARY

Recent studies highlight the importance of adopting a nuanced understanding of mechanisms and moderators that explain the stress-depression link. We also encourage continued engagement in collaborative, open science that uses multiple methods to study the full breadth of human diversity.

Acupuncture treatment for post-stroke depression: Intestinal microbiota and its role

Stroke-induced depression is a common complication and an important risk factor for disability. Besides psychiatric symptoms, depressed patients may also exhibit a variety of gastrointestinal symptoms, and even take gastrointestinal symptoms as the primary reason for medical treatment. It is well documented that stress may disrupt the balance of the gut microbiome in patients suffering from post-stroke depression (PSD), and that disruption of the gut microbiome is closely related to the severity of the condition in depressed patients. Therefore, maintaining the balance of intestinal microbiota can be the focus of research on the mechanism of acupuncture in the treatment of PSD. Furthermore, stroke can be effectively treated with acupuncture at all stages and it may act as a special microecological regulator by regulating intestinal microbiota as well. In this article, we reviewed the studies on changing intestinal microbiota after acupuncture treatment and examined the existing problems and development prospects of acupuncture, microbiome, and poststroke depression, in order to provide new ideas for future acupuncture research.

Association between Depression, Anxiety Symptoms and Gut Microbiota in Chinese Elderly with Functional Constipation

This study aimed to investigate the relationship between anxiety, depression, and gut microbiota in elderly patients with FC.

METHODS

in this cross-sectional study, a total of 198 elderly participants (85 male and 113 female) aged over 60 years were recruited. The study was conducted in Changsha city, China. The participants completed an online questionnaire, including The Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), The Patient Assessment of Symptoms (PAC-SYM), and The Patient Assessment of Quality of Life (PAC-QoL). We selected the 16S rDNA V3 + V4 region as the amplification region and sequenced the gut microbiota using the Illumina Novaseq PE250 high-throughput sequencing platform.

RESULTS

in total, 30.3% of patients with constipation had depression, while 21.3% had anxiety. The relative abundance of intestinal microbiota in the normal group was higher than that in the anxiety and depression group. According to LEfSe analysis, the relative abundance of g_Peptoniphilus and g_Geobacter in the people without depression and anxiety was higher. The relative abundance of g_Pseudoramibacter-Eubacterium and g_Candidatus-Solibacter in the depression group was lower, and the relative abundance of g_Bacteroides and g_Paraprevotella, g_Cc_115 in the anxiety group was higher. In addition, according to the correlation analysis, g_Aquicella and g_Limnohabitans were negatively correlated with constipation symptoms, anxiety, and depression.

CONCLUSIONS

this study found that gut microbiota composition may be associated with a higher incidence of anxiety and depression in patients with FC, thus providing insight into the mechanisms that ameliorate mood disorders in patients with FC.

Gut microbiome and fecal metabolic alteration in systemic lupus erythematosus patients with depression

Background

Mental health disorders in systemic lupus erythematosus (SLE) are gradually getting recognized; however, less is known regarding the actual structure and compositional alterations in gut microbiome and metabolism and the mechanisms of how they affect depression development in SLE patients.

Methods

Twenty-one SLE patients with depression (SLE-d), 17 SLE patients without depression (SLE-nd), and 32 healthy controls (HC) were included in this study. Fecal samples were collected for 16S rRNA gene sequencing and ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) based metabolomics.

Results

The structure of gut microbiome in the SLE-d group changed compared with that in the other two groups. The microbiome composition of SLE-d group showed decreased species richness indices, characterized by low ACE and Chao1 indices, a decrease in the ratio of phylum Firmicutes to Bacteroidetes, genus Faecalibacterium and Roseburia. A downregulation of the metabolite fexofenadine involved in bile secretion was positively correlated with the genus Faecalibacterium, Subdoligranulum and Agathobacter. Compared with the SLE-nd group, the SLE-d group had elevated serum levels of IL-2 and IL-6 and decreased BDNF. Interestingly, abundance of the genus Faecalibacterium and Roseburia was negatively correlated with IL-6, abundance of the genus Roseburia was negatively correlated with IL-2, and abundance of the genus Bacteroides was positively correlated with IL-2.

Conclusion

This study identified specific fecal microbes and their metabolites that may participate in the development of SLE-d. Our findings provide a new perspective for improving depression in SLE patients by regulating the gut-brain axis.

Acupuncture ameliorates breast cancer-related fatigue by regulating the gut microbiota-gut-brain axis

Cancer-related fatigue (CRF) is the most common side effect of chemotherapy for breast cancer (BC). Acupuncture treatment has an anti-fatigue effect and can regulate gut microbiota disturbance in fatigue patients. Related studies have shown that the gut microbiota-gut-brain axis is closely related to the occurrence of CRF. In this study, we first investigated the alterations of acupuncture on fatigue-like behavior, gut microbiota, gut inflammation and neuroinflammation response, gut barriers, HPA axis, and serum metabolomics in CRF mice after BC chemotherapy. Then, the correlation analysis of gut microbiota and other indicators was discussed. Our results showed that acupuncture treatment could exert an anti-fatigue effect and ameliorate the gut barrier, gut inflammation, neuroinflammation, and dysfunction of the HPA axis in CRF mice after chemotherapy for BC. 16S rRNA sequencing showed that acupuncture treatment could enhance the abundance of Candidatus Arthromitus, Lactobacillus, and Clostridia_UCG-014_unclassified and decrease the abundances of Escherichia-Shigella, Burkholderia-Caballeronia-Paraburkholderia, and Streptococcus. Serum metabolomics analysis showed that acupuncture treatment could regulate the differential metabolites N-methylnicotinamide, beta-glycerophosphoric acid, geranyl acetoacetate, serotonin and phenylalanine, tyrosine and tryptophan biosynthesis, taurine and hypotaurine, and beta-alanine metabolic pathways. Correlation analysis indicated that there are certain correlations between gut microbiota and gut inflammation, neuroinflammation, gut barrier, HPA axis function and serum metabolites. In conclusion, our findings revealed that the anti-fatigue mechanism of acupuncture treatment may be closely related to the gut microbiota-gut-brain axis. This study also provided a new reference for basic and clinical research on CRF after breast cancer chemotherapy.

Salidroside Affects Gut Microbiota Structure in db/db Mice by Affecting Insulin, Blood Glucose and Body Weight

PURPOSE

The purpose of this study was to investigate the regulatory effect of salidroside on the intestinal flora of mice with type 2 diabetes (T2DM) and its protective effect in the body.

PATIENTS AND METHODS

We acclimated 8-week-old mice for 7 days, divided them into 4 groups, and continued dosing for 8 weeks. We recorded weekly blood glucose levels and body weight for each mouse. After the completion of the feeding cycle, the 16S rRNA of the intestinal flora in the mice was sequenced, and the insulin and C-peptide levels in each group of mice were measured. Four samples were taken from each group for liver and kidney section staining.

RESULTS

Our results showed that gut microbiota diversity and function were significantly different between the diabetic mice and healthy mice and that insulin levels, body weight, and blood glucose levels could significantly influence gut microbiota changes at the genus level. The gut microbiota diversity and function of db/db mice were also altered after salidroside administration. Salidroside could attenuate inflammatory damage, lipid accumulation and inflammatory changes in the diabetic liver, as well as diabetic kidney damage. Candidatus arthromitus and Odoribacter are important species of the microbiota during diabetes and may serve as potential therapeutic targets.

CONCLUSION

Our investigation of the associated pathological conditions and fecal microbiota in db/db mice provides new insights into the pathogenesis of T2DM and provides implications for the diagnosis and treatment of T2DM.