The gut microbiota is associated with psychiatric symptom severity and treatment outcome among individuals with serious mental illness

Gastrointestinal Symptoms During Depressive Episodes in 3256 Patients with Major Depressive Disorders: Findings from the NSSD

BACKGROUND

Little is known how often depressive episodes are accompanied by gastrointestinal symptoms in major depressive disorders (MDD). The authors sought to determine the frequency and clinical correlates of gastrointestinal symptoms during episodes of depressive disorder.

METHODS

3,256 MDD patients from the National Survey on Symptomatology of Depression (NSSD), which was designed to investigate the magnitude of symptoms of current major depressive episodes in China, were enrolled and assessed for gastrointestinal symptoms in this study. Illness characteristics were compared in patients with a different frequency of gastrointestinal symptoms. Pearson correlation analysis and multiple linear regression analysis were employed to investigate the associations between gastrointestinal symptoms and psychological characteristics in the patients.

RESULTS

More than 70% of the subjects with depressive episodes had concomitant gastrointestinal symptoms. A higher frequency of gastrointestinal symptoms was associated with an increased risk of suicide ideation, suicide attempts, anxious mood, depressed mood, insomnia, feeling a failure, poor concentration, body pain, hopelessness, anger, and irritability. Pearson correlation analysis indicated moderate but significant associations between gastrointestinal symptoms and psychological characteristics (p<0.001). Multiple linear regression analysis showed that suicide ideation (β=0.161, p<0.001), anxiety mood (β=0.166, p = 0.006), insomnia (β =0.262, p<0.001), anger (β=0.144, p<0.001), feeling a failure (β =0.365, p<0.001), and body pain (β=0.581 p<0.001) were independently associated with gastrointestinal symptoms in MDD patients.

CONCLUSION

Gastrointestinal symptoms were one of the most prevalent clinical presentations of MDD. The associations between gastrointestinal symptoms and psychological characteristics may prove useful in expanding our understanding of how gastrointestinal symptoms contributes to MDD.

The Influence of Probiotic Supplementation on Depressive Symptoms, Inflammation, and Oxidative Stress Parameters and Fecal Microbiota in Patients with Depression Depending on Metabolic Syndrome Comorbidity-PRO-DEMET Randomized Study Protocol

There is a huge need to search for new treatment options and potential biomarkers of therapeutic response to antidepressant treatment. Depression and metabolic syndrome often coexist, while a pathophysiological overlap, including microbiota changes, may play a role. The paper presents a study protocol that aims to assess the effect of probiotic supplementation on symptoms of depression, anxiety and stress, metabolic parameters, inflammatory and oxidative stress markers, as well as fecal microbiota in adult patients with depressive disorders depending on the co-occurrence of metabolic syndrome. The trial will be a four-arm, parallel-group, prospective, randomized, double-blind, controlled design that will include 200 participants and will last 20 weeks (ClinicalTrials.gov identifier: NCT04756544). The probiotic preparation will contain Lactobacillus helveticus Rosell^®-52, Bifidobacterium longum Rosell^®-175. We will assess the level of depression, anxiety and stress, quality of life, blood pressure, body mass index and waist circumference, white blood cells count, serum levels of C-reactive protein, high-density lipoprotein (HDL) cholesterol, triglycerides, fasting glucose, fecal microbiota composition and the level of some fecal microbiota metabolites, as well as serum inflammatory markers and oxidative stress parameters. The proposed trial may establish a safe and easy-to-use adjunctive treatment option in a subpopulation of depressive patients only partially responsive to pharmacologic therapy.

Analysis of gut microbiota and intestinal integrity markers of inpatients with major depressive disorder

Previous studies have reported on the relationship between gut microbiota and major depressive disorder (MDD). However, there remain gaps in literature concerning the role of the intestinal barrier and microflora in the pathogenesis of depression. This study analyzes the potential causative relationship between gut microbiota and inflammatory and gut integrity markers and clinical symptoms in inpatients with depressive episodes. Sixteen inpatients (50% females) being treated with escitalopram (5-20 mg daily) in standardized conditions were included in the study. The composition of fecal microbiota was evaluated at baseline and endpoint using 16S rRNA sequencing. A significant correlation between depression severity was found, as measured with HDRS24 (Hamilton Depression Rating Scale-24 item), and the following abundance in bacteria: positive correlation with Paraprevotella (r = 0.80, q = 0.012), strong, negative correlations with Clostridiales (r = -0.70, q = 0.016), Clostridia (r = -0.71, q = 0.026), Firmicutes (r = -0.67. q = 0.032), and the RF32 order (r = -0.70, p = 0.016) in the Alphaproteobacteria (r = -0.66, q = 0.031). After six weeks of treatment, clinical outcomes were found to have a negative correlation with levels of plasma intestinal fatty acid-binding protein (IFABP) at the beginning of the study. Still they had a positive correlation with changes in fecal calprotectin during hospitalization. In conclusion, gut microbiota was associated with the severity of depressive symptoms. However, these findings do not serve as predictors of symptomatic improvement during antidepressant treatment in inpatient treatment for MDD. In turn, intestinal integrity and inflammation markers were associated with the response to treatment of patients with MDD and symptom severity. Additional studies are needed to confirm and extend these findings.

Major Depressive Disorder and gut microbiota - Association not causation. A scoping review

One very promising hypothesis of Major Depressive Disorder (MDD) pathogenesis is the gut-brain axis (GBA) dysfunction, which can lead to subclinical inflammation, hypothalamic-pituitary (HPA) axis dysregulation, and altered neural, metabolic and endocrine pathways. One of the most important parts of GBA is gut microbiota, which was shown to regulate different functions in the central nervous system (CNS). The purpose of this scoping review was to present the current state of research on the relationship between MDD and gut microbiota and extract causal relationships. Further, we presented the relationship between the use of probiotics and antidepressants, and the microbiota changes. We evaluated the data from 27 studies aimed to investigate microbial fingerprints associated with depression phenotype. We abstracted data from 16 and 11 observational and clinical studies, respectively; the latter was divided into trials evaluating the effects of psychiatric treatment (n = 3) and probiotic intervention (n = 9) on the microbiome composition and function. In total, the data of 1187 individuals from observational studies were assessed. In clinical studies, there were 490 individuals analysed. In probiotic studies, 220 and 218 patients with MDD received the intervention and non-active study comparator, respectively. It was concluded that in MDD, the microbiota is altered. Although the mechanism of this relationship is unknown, we hypothesise that the taxonomic changes observed in patients with MDD are associated with bacterial proinflammatory activity, reduced Schort Chain Fatty Acids (SCFAs) production, impaired intestinal barrier integrity and neurotransmitter production, impaired carbohydrates, tryptophane and glutamate metabolic pathways. However, only in few publications this effect was confirmed by metagenomic, metabolomic analysis, or by assessment of immunological parameters or intestinal permeability markers. Future research requires standardisation process starting from patient selection, material collection, DNA sequencing, and bioinformatic analysis. We did not observe whether antidepressive medications influence on gut microbiota, but the use of psychobiotics in patients with MDD has great prospects; however, this procedure requires also standardisation and thorough mechanistic research. The microbiota should be treated as an environmental element, which considers the aetiopathogenesis of the disease and provides new possibilities for monitoring and treating patients with MDD.

Gut microbiota dysbiosis in depressed women: The association of symptom severity and microbiota function

BACKGROUND

The association between abnormal gut microbiome composition and depression is well established. However, the composition and functional capacity of the gut microbiota regarding depressed women has been poorly addressed.

METHODS

Stool samples from 62 female patients with major depressive disorder (MDD) and 46 healthy controls (Con) were analyzed by 16S rRNA gene sequencing; Twenty fecal samples from the patient group and 21 fecal samples from the Con group were further analyzed by shotgun metagenomic sequencing. Psychiatric symptoms and psychological, social, and professional functioning was also assessed.

RESULTS

Phylum Bacteroidetes, proteobaeteria, and Fusobacteria were greatly enriched in patients with MDD, while the Firmicutes and Actinobacteria phyla were consistently higher in Con. Notably, 18 microbial markers were identified on a random forest model and achieve an area under the curve of 0.92 between patients with MDD and the Con group. Forty-five species and their associated function were identified with statistically significant differences between patients with MDD and the Con group.

LIMITATIONS

The number of recruited samples, especially samples enrolled for shotgun metagenomic sequencing was relatively small, and the stool samples were collected only at baseline, making it difficult to establish a causal association between changes in gut microbiota compositions and disease remission.

CONCLUSIONS

This study characterizes the gut microbiota and their related function in female MDD. The gut microbiota-based biomarkers may be helpful in diagnosis and the altered gut microbial metabolites may contribute to the pathogenesis of MDD in women, representing potential microbial targets.

Crosstalk between Gut and Brain in Alzheimer's Disease: The Role of Gut Microbiota Modulation Strategies

The gut microbiota (GM) represents a diverse and dynamic population of microorganisms and about 100 trillion symbiotic microbial cells that dwell in the gastrointestinal tract. Studies suggest that the GM can influence the health of the host, and several factors can modify the GM composition, such as diet, drug intake, lifestyle, and geographical locations. Gut dysbiosis can affect brain immune homeostasis through the microbiota-gut-brain axis and can play a key role in the pathogenesis of neurodegenerative diseases, including dementia and Alzheimer's disease (AD). The relationship between gut dysbiosis and AD is still elusive, but emerging evidence suggests that it can enhance the secretion of lipopolysaccharides and amyloids that may disturb intestinal permeability and the blood-brain barrier. In addition, it can promote the hallmarks of AD, such as oxidative stress, neuroinflammation, amyloid-beta formation, insulin resistance, and ultimately the causation of neural death. Poor dietary habits and aging, along with inflammatory responses due to dysbiosis, may contribute to the pathogenesis of AD. Thus, GM modulation through diet, probiotics, or fecal microbiota transplantation could represent potential therapeutics in AD. In this review, we discuss the role of GM dysbiosis in AD and potential therapeutic strategies to modulate GM in AD.

Gut Microbiome Composition Associated With Major Depressive Disorder and Sleep Quality

The microbiota-gut-brain axis plays a critical role in the pathogenesis of major depressive disorder (MDD) and related subclinical symptoms. However, studies on the gut microbiota in MDD are inconsistent, and data on MDD's effects on sleep are lacking. This study aimed to analyze the gut microbiota composition and sleep quality of patients with MDD. We performed 16S rRNA sequencing of stool samples from 36 patients with MDD and 45 healthy controls (HC). Sleep quality was assessed using the Pittsburgh Sleep Quality Index, depressive severity with the Hamilton Depression Scale, and insomnia severity using the Insomnia Severity Index. Forty-eight microbiota targets showed significant differences between MDD and HC. In MDD, six microbiota targets were associated with the severity of depression, 11 with sleep quality, and 3 with sleep severity. At the genus level, Dorea was simultaneously related to depression and sleep quality, while Intestinibacter was more closely related to sleep problems. Coprococcus and Intestinibacter were associated with sleep quality independent of the severity of depression. In conclusion, the present findings enable a better understanding of the relationship between gut microbiota and MDD-related symptoms. Gut microbiota alterations may become potential biomarkers and/or treatment targets for sleep quality in MDD.

Impact of Diabetes on the Gut and Salivary IgA Microbiomes

Mucosal surfaces like those present in the lung, gut, and mouth interface with distinct external environments. These mucosal gateways are not only portals of entry for potential pathogens but also homes to microbial communities that impact host health. Secretory immunoglobulin A (SIgA) is the single most abundant acquired immune component secreted onto mucosal surfaces and, via the process of immune exclusion, shapes the architecture of these microbiomes. Not all microorganisms at mucosal surfaces are targeted by SIgA; therefore, a better understanding of the SIgA-coated fraction may identify the microbial constituents that stimulate host immune responses in the context of health and disease. Chronic diseases like type 2 diabetes are associated with altered microbial communities (dysbiosis) that in turn affect immune-mediated homeostasis. 16S rRNA gene sequencing of SIgA-coated/uncoated bacteria (IgA-Biome) was conducted on stool and saliva samples of normoglycemic participants and individuals with prediabetes or diabetes (n = 8/group). These analyses demonstrated shifts in relative abundance in the IgA-Biome profiles between normoglycemic, prediabetic, or diabetic samples distinct from that of the overall microbiome. Differences in IgA-Biome alpha diversity were apparent for both stool and saliva, while overarching bacterial community differences (beta diversity) were also observed in saliva. These data suggest that IgA-Biome analyses can be used to identify novel microbial signatures associated with diabetes and support the need for further studies exploring these communities. Ultimately, an understanding of the IgA-Biome may promote the development of novel strategies to restructure the microbiome as a means of preventing or treating diseases associated with dysbiosis at mucosal surfaces.

Identification of a Signaling Mechanism by Which the Microbiome Regulates Th17 Cell-Mediated Depressive-Like Behaviors in Mice

OBJECTIVE

Microbiota dysbiosis has been linked to major depressive disorder, but the mechanisms whereby the microbiota modulates mood remain poorly understood. The authors tested whether specific changes in the microbiome modulate depressive-like behaviors.

METHODS

Stools from learned helpless, non-learned helpless, and non-shocked mice were analyzed by V4 16S RNA sequencing to identify gut bacteria associated with learned helplessness and to quantify the level of the quorum-sensing molecule autoinducer-2 (AI-2). T cells were analyzed by flow cytometry, and serum amyloid proteins (SAA) were analyzed by quantitative real-time polymerase chain reaction. Fecal transfer approach and administration of oleic acid and AI-2 were used to determine the effects of the microbiome and quorum-sensing molecules on depressive-like behaviors.

RESULTS

Mice deficient in segmented filamentous bacteria (SFB) were resilient to the induction of depressive-like behavior, and were resensitized when SFB was reintroduced in the gut. SFB produces the quorum-sensing AI-2 and promotes the production of SAA1 and SAA2 by the host, which increases T helper 17 (Th17) cell production. Th17 cells were required to promote depressive-like behaviors by AI-2, as AI-2 administration did not promote susceptibility to depressive-like behaviors or SAA1 and SAA2 production in Th17-deficient mice after stress. Oleic acid, an AI-2 inhibitor, exhibited antidepressant properties, reducing depressive-like behavior, intestinal SAA1 and SAA2 production, and hippocampal Th17 cell accumulation. Stool samples from 10 people with current depressive symptoms and 10 matched healthy control subjects were analyzed as well. Patients with current major depressive disorder exhibited increased fecal interleukin 17A, SAA, and SFB levels.

CONCLUSIONS

The study results reveal a novel mechanism by which bacteria alter mood.

The Bidirectional Relationship of Depression and Inflammation: Double Trouble

Depression represents the number one cause of disability worldwide and is often fatal. Inflammatory processes have been implicated in the pathophysiology of depression. It is now well established that dysregulation of both the innate and adaptive immune systems occur in depressed patients and hinder favorable prognosis, including antidepressant responses. In this review, we describe how the immune system regulates mood and the potential causes of the dysregulated inflammatory responses in depressed patients. However, the proportion of never-treated major depressive disorder (MDD) patients who exhibit inflammation remains to be clarified, as the heterogeneity in inflammation findings may stem in part from examining MDD patients with varied interventions. Inflammation is likely a critical disease modifier, promoting susceptibility to depression. Controlling inflammation might provide an overall therapeutic benefit, regardless of whether it is secondary to early life trauma, a more acute stress response, microbiome alterations, a genetic diathesis, or a combination of these and other factors.

Microbiota-Orientated Treatments for Major Depression and Schizophrenia

Background and significance. There is a need to develop new hypothesis-driven treatment for both both major depression (MD) and schizophrenia in which the risk of depression is 5 times higher than the general population. Major depression has been also associated with poor illness outcomes including pain, metabolic disturbances, and less adherence. Conventional antidepressants are partly effective, and 44% of the subjects remain unremitted under treatment. Improving MD treatment efficacy is thus needed to improve the SZ prognosis. Microbiota-orientated treatments are currently one of the most promising tracks. Method. This work is a systematic review synthetizing data of arguments to develop microbiota-orientated treatments (including fecal microbiota transplantation (FMT)) in major depression and schizophrenia. Results. The effectiveness of probiotic administration in MD constitutes a strong evidence for developing microbiota-orientated treatments. Probiotics have yielded medium-to-large significant effects on depressive symptoms, but it is still unclear if the effect is maintained following probiotic discontinuation. Several factors may limit MD improvement when using probiotics, including the small number of bacterial strains administered in probiotic complementary agents, as well as the presence of a disturbed gut microbiota that probably limits the probiotics’ impact. FMT is a safe technique enabling to improve microbiota in several gut disorders. The benefit/risk ratio of FMT has been discussed and has been recently improved by capsule administration. Conclusion. Cleaning up the gut microbiota by transplanting a totally new human gut microbiota in one shot, which is referred to as FMT, is likely to strongly improve the efficacy of microbiota-orientated treatments in MD and schizophrenia and maintain the effect over time. This hypothesis should be tested in future clinical trials.