Stressful events induce long-term gut microbiota dysbiosis and associated post-traumatic stress symptoms in healthcare workers fighting against COVID-19

Molecular mechanisms and therapeutic possibilities of short-chain fatty acids in posttraumatic stress disorder patients: a mini-review

This mini-review explores the role of short-chain fatty acids (SCFAs) in posttraumatic stress disorder (PTSD). Highlighting the microbiota-gut-brain axis, this study investigated the bidirectional communication between the gut microbiome and mental health. SCFAs, byproducts of gut microbial fermentation, have been examined for their potential impact on PTSD, with a focus on molecular mechanisms and therapeutic interventions. This review discusses changes in SCFA levels and bacterial profiles in individuals with PTSD, emphasizing the need for further research. Promising outcomes from clinical trials using probiotics and fermented formulations suggest potential avenues for PTSD management. Future directions involve establishing comprehensive human cohorts, integrating multiomics data, and employing advanced computational methods, with the goal of deepening our understanding of the role of SCFAs in PTSD and exploring microbiota-targeted interventions.

Rejuvenating fecal microbiota transplant enhances peripheral nerve repair in aged mice by modulating endoneurial inflammation

Peripheral nerve injury (PNI) resulting from trauma or neuropathies can cause significant disability, and its prognosis deteriorates with age. Emerging evidence suggests that gut dysbiosis and reduced fecal short-chain fatty acids (SCFAs) contribute to an age-related systemic hyperinflammation (inflammaging), which hinders nerve recovery after injury. This study thus aimed to evaluate the pro-regenerative effects of a rejuvenating fecal microbiota transplant (FMT) in a preclinical PNI model using aged mice. Aged C57BL/6 mice underwent bilateral crush injuries to their sciatic nerves. Subsequently, they either received FMT from young donors at three and four days after the injury or retained their aged gut microbiota. We analyzed gut microbiome composition and SCFA concentrations in fecal samples. The integrity of the ileac mucosal barrier was assessed by immunofluorescence staining of Claudin-1. Flow cytometry was utilized to examine immune cells and cytokine production in the ileum, spleen, and sciatic nerve. Various assessments, including behavioural tests, electrophysiological studies, and morphometrical analyses, were conducted to evaluate peripheral nerve function and repair following injury. Rejuvenating FMT reversed age-related gut dysbiosis by increasing Actinobacteria, especially Bifidobacteriales genera. This intervention also led to an elevation of gut SCFA levels and mitigated age-related ileac mucosal leakiness in aged recipients. Additionally, it augmented the number of T-helper 2 (Th2) and regulatory T (Treg) cells in the ileum and spleen, with the majority being positive for anti-inflammatory interleukin-10 (IL-10). In sciatic nerves, rejuvenating FMT resulted in increased M2 macrophage counts and a higher IL-10 production by IL-10+TNF-α- M2 macrophage subsets. Ultimately, restoring a youthful gut microbiome in aged mice led to improved nerve repair and enhanced functional recovery after PNI. Considering that FMT is already a clinically available technique, exploring novel translational strategies targeting the gut microbiome to enhance nerve repair in the elderly seems promising and warrants further evaluation.

A retrospective cohort study on early antibiotic use in vaccinated and unvaccinated COVID-19 patients

The bacteriophage behavior of SARS-CoV-2 during the acute and post-COVID-19 phases appears to be an important factor in the development of the disease. The early use of antibiotics seems to be crucial to inhibit disease progression-to prevent viral replication in the gut microbiome, and control toxicological production from the human microbiome. To study the impact of specific antibiotics on recovery from COVID-19 and long COVID (LC) taking into account: vaccination status, comorbidities, SARS-CoV-2 wave, time of initiation of antibiotic therapy and concomitant use of corticosteroids and nonsteroidal anti-inflammatory drugs (NSAIDs). A total of 211 COVID-19 patients were included in the study: of which 59 were vaccinated with mRNA vaccines against SARS-CoV-2 while 152 were unvaccinated. Patients were enrolled in three waves: from September 2020 to October 2022, corresponding to the emergence of the pre-Delta, Delta, and Omicron variants of the SARS-CoV-2 virus. The three criteria for enrolling patients were: oropharyngeal swab positivity or fecal findings; moderate symptoms with antibiotic intake; and measurement of blood oxygen saturation during the period of illness. The use of antibiotic combinations, such as amoxicillin with clavulanic acid (875 + 125 mg tablets, every 12 h) plus rifaximin (400 mg tablets every 12 h), as first choice, as suggested from the previous data, or azithromycin (500 mg tablets every 24 h), plus rifaximin as above, allows healthcare professionals to focus on the gut microbiome and its implications in COVID-19 disease during patient care. The primary outcome measured in this study was the estimated average treatment effect, which quantified the difference in mean recovery between patients receiving antibiotics and those not receiving antibiotics at 3 and 9 days after the start of treatment. In the analysis, both vaccinated and unvaccinated groups had a median illness duration of 7 days (interquartile range [IQR] 6-9 days for each; recovery crude hazard ratio [HR] = 0.94, p = 0.700). The median illness duration for the pre-Delta and Delta waves was 8 days (IQR 7-10 days), while it was shorter, 6.5 days, for Omicron (IQR 6-8 days; recovery crude HR = 1.71, p < 0.001). These results were confirmed by multivariate analysis. Patients with comorbidities had a significantly longer disease duration: median 8 days (IQR 7-10 days) compared to 7 days (IQR 6-8 days) for those without comorbidities (crude HR = 0.75, p = 0.038), but this result was not confirmed in multivariate analysis as statistical significance was lost. Early initiation of antibiotic therapy resulted in a significantly shorter recovery time (crude HR = 4.74, p < 0.001). Concomitant use of NSAIDs did not reduce disease duration and in multivariate analysis prolonged the disease (p = 0.041). A subgroup of 42 patients receiving corticosteroids for a median of 3 days (IQR 3-6 days) had a longer recovery time (median 9 days, IQR 8-10 days) compared to others (median 7 days, IQR 6-8 days; crude HR = 0.542, p < 0.001), as confirmed also by the adjusted HR. In this study, a statistically significant reduction in recovery time was observed among patients who received early antibiotic treatment. Early initiation of antibiotics played a crucial role in maintaining higher levels of blood oxygen saturation. In addition, it is worth noting that a significant number of patients who received antibiotics in the first 3 days and for a duration of 7 days, during the acute phase did not develop LC.

Potential causal association between gut microbiome and posttraumatic stress disorder

BACKGROUND

The causal effects of gut microbiome and the development of posttraumatic stress disorder (PTSD) are still unknown. This study aimed to clarify their potential causal association using mendelian randomization (MR).

METHODS

The summary-level statistics for gut microbiome were retrieved from a genome-wide association study (GWAS) of the MiBioGen consortium. As to PTSD, the Freeze 2 datasets were originated from the Psychiatric Genomics Consortium Posttraumatic Stress Disorder Working Group (PGC-PTSD), and the replicated datasets were obtained from FinnGen consortium. Single nucleotide polymorphisms meeting MR assumptions were selected as instrumental variables. The inverse variance weighting (IVW) method was employed as the main approach, supplemented by sensitivity analyses to evaluate potential pleiotropy and heterogeneity and ensure the robustness of the MR results. We also performed reverse MR analyses to explore PTSD's causal effects on the relative abundances of specific features of the gut microbiome.

RESULTS

In Freeze 2 datasets from PGC-PTSD, eight bacterial traits revealed a potential causal association between gut microbiome and PTSD (IVW, all P < 0.05). In addition, Genus.Dorea and genus.Sellimonas were replicated in FinnGen datasets, in which eight bacterial traits revealed a potential causal association between gut microbiome and the occurrence of PTSD. The heterogeneity and pleiotropy analyses further supported the robustness of the IVW findings, providing additional evidence for their reliability.

CONCLUSION

Our study provides the potential causal impact of gut microbiomes on the development of PTSD, shedding new light on the understanding of the dysfunctional gut-brain axis in this disorder. Our findings present novel evidence and call for investigations to confirm the association between their links, as well as to illuminate the underlying mechanisms.

Decoding the role of the gut microbiome in gut-brain axis, stress-resilience, or stress-susceptibility: A review

Increased exposure to stress is associated with stress-related disorders, including depression, anxiety, and neurodegenerative conditions. However, susceptibility to stress is not seen in every individual exposed to stress, and many of them exhibit resilience. Thus, developing resilience to stress could be a big breakthrough in stress-related disorders, with the potential to replace or act as an alternative to the available therapies. In this article, we have focused on the recent advancements in gut microbiome research and the potential role of the gut-brain axis (GBA) in developing resilience or susceptibility to stress. There might be a complex interaction between the autonomic nervous system (ANS), immune system, endocrine system, microbial metabolites, and bioactive lipids like short-chain fatty acids (SCFAs), neurotransmitters, and their metabolites that regulates the communication between the gut microbiota and the brain. High fiber intake, prebiotics, probiotics, plant supplements, and fecal microbiome transplant (FMT) could be beneficial against gut dysbiosis-associated brain disorders. These could promote the growth of SCFA-producing bacteria, thereby enhancing the gut barrier and reducing the gut inflammatory response, increase the expression of the claudin-2 protein associated with the gut barrier, and maintain the blood-brain barrier integrity by promoting the expression of tight junction proteins such as claudin-5. Their neuroprotective effects might also be related to enhancing the expression of brain-derived neurotrophic factor (BDNF) and glucagon-like peptide (GLP-1). Further investigations are needed in the field of the gut microbiome for the elucidation of the mechanisms by which gut dysbiosis contributes to the pathophysiology of neuropsychiatric disorders.

Noxious ramifications of cosmetic pollutants on gastrointestinal microbiome: A pathway to neurological disorders

On exposure to cosmetic pollutants, gastrointestinal dysbiosis, which is characterised by a disturbance in the gut microbiota, has come into focus as a possible contributor to the occurrence of neurotoxic consequences. It is normal practice to use personal care products that include parabens, phthalates, sulphates, triclosans/triclocarbans and micro/nano plastics. These substances have been found in a variety of bodily fluids and tissues, demonstrating their systemic dispersion. Being exposed to these cosmetic pollutants has been linked in recent research to neurotoxicity, including cognitive decline and neurodevelopmental problems. A vital part of sustaining gut health and general well-being is the gut flora. Increased intestinal permeability, persistent inflammation, and impaired metabolism may result from disruption of the gut microbial environment, which may in turn contribute to neurotoxicity. The link between gastrointestinal dysbiosis and the neurotoxic effects brought on by cosmetic pollutants may be explained by a number of processes, primarily the gut-brain axis. For the purpose of creating preventative and therapeutic measures, it is crucial to comprehend the intricate interactions involving cosmetic pollutants, gastrointestinal dysbiosis, and neurotoxicity. This review provides an in-depth understanding of the various hazardous cosmetic pollutants and its potential role in the occurrence of neurological disorders via gastrointestinal dysbiosis, providing insights into various described and hypothetical mechanisms regarding the complex toxic effects of these industrial pollutants.

The Gut-Brain Axis and the Microbiome in Anxiety Disorders, Post-Traumatic Stress Disorder and Obsessive-Compulsive Disorder

A large body of research supports the role of stress in several psychiatric disorders in which anxiety is a prominent symptom. Other research has indicated that the gut microbiome-immune system- brain axis is involved in a large number of disorders and that this axis is affected by various stressors. The focus of the current review is on the following stress-related disorders: generalized anxiety disorder, panic disorder, social anxiety disorder, post-traumatic stress disorder and obsessivecompulsive disorder. Descriptions of systems interacting in the gut-brain axis, microbiome-derived molecules and of pro- and prebiotics are given. Preclinical and clinical studies on the relationship of the gut microbiome to the psychiatric disorders mentioned above are reviewed. Many studies support the role of the gut microbiome in the production of symptoms in these disorders and suggest the potential for pro- and prebiotics for their treatment, but there are also contradictory findings and concerns about the limitations of some of the research that has been done. Matters to be considered in future research include longer-term studies with factors such as sex of the subjects, drug use, comorbidity, ethnicity/ race, environmental effects, diet, and exercise taken into account; appropriate compositions of pro- and prebiotics; the translatability of studies on animal models to clinical situations; and the effects on the gut microbiome of drugs currently used to treat these disorders. Despite these challenges, this is a very active area of research that holds promise for more effective, precision treatment of these stressrelated disorders in the future.

Gut Microbiota and Mitochondria: Health and Pathophysiological Aspects of Long COVID

The current understanding of long COVID (LC) is still limited. This review highlights key findings regarding the role of gut microbiota, mitochondria, and the main pathophysiological aspects of LC revealed by clinical studies, related to the complex interplay between infection, intestinal dysbiosis, dysfunctional mitochondria, and systemic inflammation generated in a vicious circle, reflecting the molecular and cellular processes from the "leaky gut" to the "leaky electron transport chain (ETC)" into a quantum leap. The heterogeneity of LC has hindered progress in deciphering all the pathophysiological mechanisms, and therefore, the approach must be multidisciplinary, with a special focus not only on symptomatic management but also on addressing the underlying health problems of the patients. It is imperative to further assess and validate the effects of COVID-19 and LC on the gut microbiome and their relationship to infections with other viral agents or pathogens. Further studies are needed to better understand LC and expand the interdisciplinary points of view that are required to accurately diagnose and effectively treat this heterogeneous condition. Given the ability of SARS-CoV-2 to induce autoimmunity in susceptible patients, they should be monitored for symptoms of autoimmune disease after contracting the viral infection. One question remains open, namely, whether the various vaccines developed to end the pandemic will also induce autoimmunity. Recent data highlighted in this review have revealed that the persistence of SARS-CoV-2 and dysfunctional mitochondria in organs such as the heart and, to a lesser extent, the kidneys, liver, and lymph nodes, long after the organism has been able to clear the virus from the lungs, could be an explanation for LC.

Association between microbiome and the development of adverse posttraumatic neuropsychiatric sequelae after traumatic stress exposure

Patients exposed to trauma often experience high rates of adverse post-traumatic neuropsychiatric sequelae (APNS). The biological mechanisms promoting APNS are currently unknown, but the microbiota-gut-brain axis offers an avenue to understanding mechanisms as well as possibilities for intervention. Microbiome composition after trauma exposure has been poorly examined regarding neuropsychiatric outcomes. We aimed to determine whether the gut microbiomes of trauma-exposed emergency department patients who develop APNS have dysfunctional gut microbiome profiles and discover potential associated mechanisms. We performed metagenomic analysis on stool samples (n = 51) from a subset of adults enrolled in the Advancing Understanding of RecOvery afteR traumA (AURORA) study. Two-, eight- and twelve-week post-trauma outcomes for post-traumatic stress disorder (PTSD) (PTSD checklist for DSM-5), normalized depression scores (PROMIS Depression Short Form 8b) and somatic symptom counts were collected. Generalized linear models were created for each outcome using microbial abundances and relevant demographics. Mixed-effect random forest machine learning models were used to identify associations between APNS outcomes and microbial features and encoded metabolic pathways from stool metagenomics. Microbial species, including Flavonifractor plautii, Ruminococcus gnavus and, Bifidobacterium species, which are prevalent commensal gut microbes, were found to be important in predicting worse APNS outcomes from microbial abundance data. Notably, through APNS outcome modeling using microbial metabolic pathways, worse APNS outcomes were highly predicted by decreased L-arginine related pathway genes and increased citrulline and ornithine pathways. Common commensal microbial species are enriched in individuals who develop APNS. More notably, we identified a biological mechanism through which the gut microbiome reduces global arginine bioavailability, a metabolic change that has also been demonstrated in the plasma of patients with PTSD.

The interactions between host genome and gut microbiome increase the risk of psychiatric disorders: Mendelian randomization and biological annotation

BACKGROUND

The correlation between human gut microbiota and psychiatric diseases has long been recognized. Based on the heritability of the microbiome, genome-wide association studies on human genome and gut microbiome (mbGWAS) have revealed important host-microbiome interactions. However, establishing causal relationships between specific gut microbiome features and psychological conditions remains challenging due to insufficient sample sizes of previous studies of mbGWAS.

METHODS

Cross-cohort meta-analysis (via METAL) and multi-trait analysis (via MTAG) were used to enhance the statistical power of mbGWAS for identifying genetic variants and genes. Using two large mbGWAS studies (7,738 and 5,959 participants respectively) and12 disease-specific studies from the Psychiatric Genomics Consortium (PGC), we performed bidirectional two-sample mendelian randomization (MR) analyses between microbial features and psychiatric diseases (up to 500,199 individuals). Additionally, we conducted downstream gene- and gene-set-based analyses to investigate the shared biology linking gut microbiota and psychiatric diseases.

RESULTS

METAL and MTAG conducted in mbGWAS could boost power for gene prioritization and MR analysis. Increases in the number of lead SNPs and mapped genes were witnessed in 13/15 species and 5/10 genera after using METAL, and MTAG analysis gained an increase in sample size equivalent to expanding the original samples from 7% to 63%. Following METAL use, we identified a positive association between Bacteroides faecis and ADHD (OR, 1.09; 95 %CI, 1.02-1.16; P = 0.008). Bacteroides eggerthii and Bacteroides thetaiotaomicron were observed to be positively associated with PTSD (OR, 1.11; 95 %CI, 1.03-1.20; P = 0.007; OR, 1.11; 95 %CI, 1.01-1.23; P = 0.03). These findings remained stable across statistical models and sensitivity analyses. No genetic liabilities to psychiatric diseases may alter the abundance of gut microorganisms.Using biological annotation, we identified that those genes contributing to microbiomes (e.g., GRIN2A and RBFOX1) are expressed and enriched in human brain tissues.

CONCLUSIONS

Our statistical genetics strategy helps to enhance the power of mbGWAS, and our genetic findings offer new insights into biological pleiotropy and causal relationship between microbiota and psychiatric diseases.

Repeated Social Defeat Stress Induces an Inflammatory Gut Milieu by Altering the Mucosal Barrier Integrity and Gut Microbiota Homeostasis

Background

Posttraumatic stress disorder (PTSD) is a mental health condition triggered by exposure to traumatic events in an individual's life. Patients with PTSD are also at a higher risk for comorbidities. However, it is not well understood how PTSD affects human health and/or promotes the risk for comorbidities. Nevertheless, patients with PTSD harbor a proinflammatory milieu and dysbiotic gut microbiota. Gut barrier integrity helps to maintain normal gut homeostasis and its dysregulation promotes gut dysbiosis and inflammation.

Methods

We used a mouse model of repeated social defeat stress (RSDS), a preclinical model of PTSD. Behavioral studies, metagenomics analysis of the microbiome, gut permeability assay (on mouse colon, using an Ussing chamber), immunoblotting, and immunohistochemical analyses were performed. Polarized intestinal epithelial cells and 3-dimensional crypt cultures were used for mechanistic analysis.

Results

The RSDS mice harbor a heightened proinflammatory gut environment and microbiota dysbiosis. The RSDS mice further showed significant dysregulation of gut barrier functions, including transepithelial electrical resistance, mucin homeostasis, and antimicrobial responses. RSDS mice also showed a specific increase in intestinal expression of claudin-2, a tight junction protein, and epinephrine, a stress-induced neurotransmitter. Treating intestinal epithelial cells or 3-dimensional cultured crypts with norepinephrine or intestinal luminal contents (fecal contents) upregulated claudin-2 expression and inhibited transepithelial electrical resistance.

Conclusions

Traumatic stress induces dysregulation of gut barrier functions, which may underlie the observed gut microbiota changes and proinflammatory gut milieu, all of which may have an interdependent effect on the health and increased risk of comorbidities in patients with PTSD.

The impact of acute and chronic stress on gastrointestinal physiology and function: a microbiota-gut-brain axis perspective

The physiological consequences of stress often manifest in the gastrointestinal tract. Traumatic or chronic stress is associated with widespread maladaptive changes throughout the gut, although comparatively little is known about the effects of acute stress. Furthermore, these stress-induced changes in the gut may increase susceptibility to gastrointestinal disorders and infection, and impact critical features of the neural and behavioural consequences of the stress response by impairing gut-brain axis communication. Understanding the mechanisms behind changes in enteric nervous system circuitry, visceral sensitivity, gut barrier function, permeability, and the gut microbiota following stress is an important research objective with pathophysiological implications in both neurogastroenterology and psychiatry. Moreover, the gut microbiota has emerged as a key aspect of physiology sensitive to the effects of stress. In this review, we focus on different aspects of the gastrointestinal tract including gut barrier function as well as the immune, humoral and neuronal elements involved in gut-brain communication. Furthermore, we discuss the evidence for a role of stress in gastrointestinal disorders. Existing gaps in the current literature are highlighted, and possible avenues for future research with an integrated physiological perspective have been suggested. A more complete understanding of the spatial and temporal dynamics of the integrated host and microbial response to different kinds of stressors in the gastrointestinal tract will enable full exploitation of the diagnostic and therapeutic potential in the fast-evolving field of host-microbiome interactions.

A Preliminary Study Exploring the Relationship between Occupational Health Hazards and Gut Microbiota among Firefighters

Firefighters are exposed to occupational hazards and have a higher prevalence of health issues. The gut microbiota plays a crucial role in the immune, endocrine, and neural systems, and disruptions in its composition can impact health outcomes. This pilot study aimed to investigate the potential association between occupational factors, changes in gut microbiota, and the development of adverse health outcomes in firefighters. To test this hypothesis, we recruited 15 firefighters and age/sex-matched controls to investigate the relationship between occupational environment and gut microbiota. Firefighters exhibit lower intestinal bacterial alpha diversity and a higher presence of pathogenic bacteria than the control. Moreover, unique gut bacterial taxa were observed in firefighters with high post-traumatic stress disorder (PTSD) scores, which could contribute to immune dysregulation and higher susceptibility to pathogen colonization. These preliminary findings suggest that occupational factors, including exposure to traumatic stressors and chemicals, may influence firefighters' health by modulating their gut microbiota. The observed changes in gut microbiota composition and the potential link to occupational hazards highlight the need for further research in larger sample-size studies. Understanding the role of gut microbiota in firefighter health may have implications for preventive measures and interventions to mitigate occupational health risks and improve overall well-being.

Psychological Stress and Gut Microbiota Composition: A Systematic Review of Human Studies

INTRODUCTION

The associations between psychological stress and gut microbiota composition are not fully understood. This study investigated associations between psychological stress and gut microbiota composition and examined the potential modifying effects of age, sex, and ethnicity on such associations.

METHODS

A systematic literature search was conducted using PubMed, Web of Science, PsycINFO, and Embase databases for studies published until November 2021 which examined associations between psychological stress and gut microbiota composition.

RESULTS

During the search process, 10,790 studies were identified, and after screening, 13 met the eligibility criteria and were included. The median sample size was 70, and the median age of participants was 28.0 years. Most of the included studies did not report associations between measures of alpha- and beta diversity of the gut microbiota composition and psychological stress. A few studies reported that the Shannon index, Chao 1, Simpson index, and weighted UniFrac were negatively associated with psychological stress. Significant reductions in several taxa at the phyla-, family-, and genus-levels were observed in participants with higher psychological stress. At the phylum level, the abundance of Proteobacteria and Verrucomicrobia were negatively associated with psychological stress. At the family-level, no more than two studies reported associations of the same microbiota with psychological stress. At the genus level, the following results were found in more than two studies; psychological stress was negatively associated with the abundance of Lachnospira, Lachnospiraceae, Phascolarctobacterium, Sutterella, and Veillonella, and positively associated with the abundance of Methanobrevibacter, Rhodococcus, and Roseburia. However, it was not possible to determine the influence of age, sex, or ethnicity due to the limited studies included.

CONCLUSION

Our findings provide evidence that psychological stress is associated with changes in the abundance of the gut microbiota. Larger sample longitudinal studies are needed to determine the causal relationship between psychological stress and the gut microbiota.

Stability of human gut microbiome: Comparison of ecological modelling and observational approaches

The gut microbiome plays a pivotal role in the human body, and perturbations in its composition have been linked to various disorders. Stability is an essential property of a healthy human gut microbiome, which allows it to maintain its functional richness under the external influences. This property has been explored through two distinct methodologies - mathematical modelling based on ecological principles and statistical analysis drawn from observations in interventional studies. Here we conducted a meta-analysis aimed to compare the two approaches utilising the data from 9 interventional and time series studies encompassing 3512 gut microbiome profiles obtained via 16S rRNA gene sequencing. By employing the previously published compositional Lotka-Volterra method, we modelled the dynamics of the microbial community and evaluated ecological stability measures. These measures were compared to those based on observed microbiome changes. There was a substantial correlation between the outcomes of the two approaches. Particularly, local stability assessed within the ecological paradigm was positively correlated with observational stability measures accounting for the compositional nature of microbiome data. Additionally, we were able to reproduce the previously reported inverse relationship between the community's robustness to microorganism loss and local stability, attributed to the distinct impacts of coefficient characterising the network decomposition on these two stability assessments. Our findings demonstrate harmonisation between the ecological and observational approaches to microbiome analysis, advancing the understanding of healthy gut microbiome concept. This paves the way to develop efficient microbiome-targeting interventions for disease prevention and treatment.

Social Isolation and Breast Cancer

Although the role of life stressors in breast cancer remains unclear, social isolation is consistently associated with increased breast cancer risk and mortality. Social isolation can be defined as loneliness or an absence of perceived social connections. In female mice and rats, social isolation is mimicked by housing animals 1 per cage. Social isolation causes many biological changes, of which an increase in inflammatory markers and disruptions in mitochondrial and cellular metabolism are commonly reported. It is not clear how the 2 traditional stress-induced pathways, namely, the hypothalamic-pituitary-adrenocortical axis (HPA), resulting in a release of glucocorticoids from the adrenal cortex, and autonomic nervous system (ANS), resulting in a release of catecholamines from the adrenal medulla and postganglionic neurons, could explain the increased breast cancer risk in socially isolated individuals. For instance, glucocorticoid receptor activation in estrogen receptor positive breast cancer cells inhibits their proliferation, and activation of β-adrenergic receptor in immature immune cells promotes their differentiation toward antitumorigenic T cells. However, activation of HPA and ANS pathways may cause a disruption in the brain-gut-microbiome axis, resulting in gut dysbiosis. Gut dysbiosis, in turn, leads to an alteration in the production of bacterial metabolites, such as short chain fatty acids, causing a systemic low-grade inflammation and inducing dysfunction in mitochondrial and cellular metabolism. A possible causal link between social isolation-induced increased breast cancer risk and mortality and gut dysbiosis should be investigated, as it offers new tools to prevent breast cancer.

Longitudinal Gut Microbiota Dysbiosis Underlies Olanzapine-Induced Weight Gain

Olanzapine is one of the most effective medicines available for stabilizing schizophrenia spectrum disorders. However, it has been reported to show the greatest propensity for inducing body weight gain and producing metabolic side effects, which cause a great burden in patients with psychiatric disorders. Since the gut microbiota has a profound impact on the initiation and development of metabolic diseases, we conducted a longitudinal study to explore its role in olanzapine-induced obesity and metabolic abnormalities. Female Sprague-Dawley rats were treated with different doses of olanzapine, and metabolic and inflammatory markers were measured. Olanzapine significantly induced body weight gain (up to a 2.1-fold change), which was accompanied by hepatic inflammation and increased plasma triglyceride levels (up to a 2.9-fold change), as well as gut microbiota dysbiosis. Subsequently, fuzzy c-means clustering was used to characterize three clusters of longitudinal trajectories for microbial fluctuations: (i) genera continuing to increase, (ii) genera continuing to decrease, and (iii) genera temporarily changing. Among them, Enterorhabdus (r = 0.38), Parasutterella (r = 0.43), and Prevotellaceae UCG-001 (r = 0.52) positively correlated with body weight gain. In addition, two MetaCyc metabolic pathways were identified as associated with olanzapine-induced body weight gain, including the superpathway of glucose and xylose degradation and the superpathway of l-threonine biosynthesis. In conclusion, we demonstrate that olanzapine can directly alter the gut microbiota and rapidly induce dysbiosis, which is significantly associated with body weight gain. This may suggest gut microbiota targets in future studies on metabolic abnormalities caused by olanzapine. IMPORTANCE Olanzapine is one of the most effective second-generation antipsychotics for stabilizing schizophrenia spectrum disorders. However, olanzapine has multiple drug-induced metabolic side effects, including weight gain. This study provides insight to the gut microbiota target in olanzapine-induced obesity. Specifically, we explored the longitudinal gut microbiota trajectories of female Sprague-Dawley rats undergoing olanzapine treatment. We showed that olanzapine treatment causes a dynamic alteration of gut microbiota diversity. Additionally, we identified three genera, Parasutterella, Enterorhabdus, and Prevotellaceae UCG-001, that may play an important role in olanzapine-induced obesity. In this case, the supply or removal of specific elements of the gut microbiota may represent a promising avenue for treatment of olanzapine-related metabolic side effects.

Microbiota revolution: How gut microbes regulate our lives

The human intestine is a natural environment ecosystem of a complex of diversified and dynamic microorganisms, determined through a process of competition and natural selection during life. Those intestinal microorganisms called microbiota and are involved in a variety of mechanisms of the organism, they interact with the host and therefore are in contact with the organs of the various systems. However, they play a crucial role in maintaining host homeostasis, also influencing its behaviour. Thus, microorganisms perform a series of biological functions important for human well-being. The host provides the microorganisms with the environment and nutrients, simultaneously drawing many benefits such as their contribution to metabolic, trophic, immunological, and other functions. For these reasons it has been reported that its quantitative and qualitative composition can play a protective or harmful role on the host health. Therefore, a dysbiosis can lead to an association of unfavourable factors which lead to a dysregulation of the physiological processes of homeostasis. Thus, it has pre-viously noted that the gut microbiota can participate in the pathogenesis of autoimmune diseases, chronic intestinal inflammation, diabetes mellitus, obesity and atherosclerosis, neurological disorders (e.g., neurological diseases, autism, etc.) colorectal cancer, and more.

The Role of Gut Microbiota in Anxiety, Depression, and Other Mental Disorders as Well as the Protective Effects of Dietary Components

The number of individuals experiencing mental disorders (e.g., anxiety and depression) has significantly risen in recent years. Therefore, it is essential to seek prevention and treatment strategies for mental disorders. Several gut microbiota, especially Firmicutes and Bacteroidetes, are demonstrated to affect mental health through microbiota-gut-brain axis, and the gut microbiota dysbiosis can be related to mental disorders, such as anxiety, depression, and other mental disorders. On the other hand, dietary components, including probiotics (e.g., Lactobacillus and Bifidobacterium), prebiotics (e.g., dietary fiber and alpha-lactalbumin), synbiotics, postbiotics (e.g., short-chain fatty acids), dairy products, spices (e.g., Zanthoxylum bungeanum, curcumin, and capsaicin), fruits, vegetables, medicinal herbs, and so on, could exert protective effects against mental disorders by enhancing beneficial gut microbiota while suppressing harmful ones. In this paper, the mental disorder-associated gut microbiota are summarized. In addition, the protective effects of dietary components on mental health through targeting the gut microbiota are discussed. This paper can be helpful to develop some dietary natural products into pharmaceuticals and functional foods to prevent and treat mental disorders.

Effects of Unconventional Work and Shift Work on the Human Gut Microbiota and the Potential of Probiotics to Restore Dysbiosis

The work environment is a factor that can significantly influence the composition and functionality of the gut microbiota of workers, in many cases leading to gut dysbiosis that will result in serious health problems. The aim of this paper was to provide a compilation of the different studies that have examined the influence of jobs with unconventional work schedules and environments on the gut microbiota of workers performing such work. As a possible solution, probiotic supplements, via modulation of the gut microbiota, can moderate the effects of sleep disturbance on the immune system, as well as restore the dysbiosis produced. Rotating shift work has been found to be associated with an increase in the risk of various metabolic diseases, such as obesity, metabolic syndrome, and type 2 diabetes. Sleep disturbance or lack of sleep due to night work is also associated with metabolic diseases. In addition, sleep disturbance induces a stress response, both physiologically and psychologically, and disrupts the healthy functioning of the gut microbiota, thus triggering an inflammatory state. Other workers, including military, healthcare, or metallurgy workers, as well as livestock farmers or long-travel seamen, work in environments and schedules that can significantly affect their gut microbiota.

Improved Assembly of Metagenome-Assembled Genomes and Viruses in Tibetan Saline Lake Sediment by HiFi Metagenomic Sequencing

With the development and reduced costs of high-throughput sequencing technology, environmental dark matter, such as novel metagenome-assembled genomes (MAGs) and viruses, is now being discovered easily. However, due to read length limitations, MAGs and viromes often suffer from genome discontinuity and deficiencies in key functional elements. Here, by applying long-read sequencing technology to sediment samples from a Tibetan saline lake, we comprehensively analyzed the performance of high-fidelity (HiFi) reads and the possibility of integration with short-read next-generation sequencing (NGS) data. In total, 207 full-length nonredundant 16S rRNA gene sequences and 19 full-length nonredundant 18S rRNA genes were directly obtained from HiFi reads, which greatly surpassed the retrieval performance of NGS technology. We carried out a cross-sectional comparison among multiple assembly strategies, referred to as 'NGS', 'Hybrid (NGS+HiFi)', and 'HiFi'. Two MAGs and 29 viruses with circular genomes were reconstructed using HiFi reads alone, indicating the great power of the 'HiFi' approach to assemble high-quality microbial genomes. Among the 3 strategies, the 'Hybrid' approach produced the highest number of medium/high-quality MAGs and viral genomes, while the ratio of MAGs containing 16S rRNA genes was significantly improved in the 'HiFi' assembly results. Overall, our study provides a practical metagenomic resolution for analyzing complex environmental samples by taking advantage of both the short-read and HiFi long-read sequencing methods to extract the maximum amount of information, including data on prokaryotes, eukaryotes, and viruses, via the 'Hybrid' approach. IMPORTANCE To expand the understanding of microbial dark matter in the environment, we did the first comparative evaluation of multiple assembly strategies based on high-throughput short-read and HiFi data from lake sediments metagenomic sequencing. The results demonstrated great improvement of the 'Hybrid' assembly method (short-read next-generation sequencing data plus HiFi data) in the recovery of medium/high-quality MAGs and viral genomes. Further analysis showed that HiFi data is important to retrieve the complete circular prokaryotic and viral genomes. Meanwhile, hundreds of full-length 16S/18S rRNA genes were assembled directly from HiFi data, which facilitated the species composition studies of complex environmental samples, especially for understanding micro-eukaryotes. Therefore, the application of the latest HiFi long-read sequencing could greatly improve the metagenomic assembly integrity and promote environmental microbiome research.

Anti-depressive-like and cognitive impairment alleviation effects of Gastrodia elata Blume water extract is related to gut microbiome remodeling in ApoE-/- mice exposed to unpredictable chronic mild stress

ETHNOPHARMACOLOGY RELEVANCE

Gastrodia elata Blume (GE) is a traditional Chinese dietary therapy used to treat neurological disorders. Gastrodia elata Blume water extract (WGE) has been shown to ameliorate inflammation and improve social frustration in mice in a chronic social defeat model. However, studies on the anti-depressive-like effects and cognitive impairment alleviation related to the impact of WGE on the gut microbiome of ApoE-/- mice remain elusive.

AIM OF THE STUDY

The present study aimed to investigate the anti-depressive-like effect and cognitive impairment alleviation and mechanisms of WGE in ApoE-/- mice subjected to unpredictable chronic mild stress (UCMS), as well as its impact on the gut microbiome of the mice.

MATERIALS AND METHODS

Sixty ApoE-/- mice (6 months old) were randomly grouped into six groups: control, UCMS, WGE groups [5, 10, 20 mL WGE/kg body weight (bw) + UCMS], and a positive group (fluoxetine 20 mg/kg bw + UCMS). After four weeks of the UCMS paradigm, the sucrose preference, novel object recognition, and open field tests were conducted. The neurotransmitters serotonin (5-HT), dopamine (DA) and their metabolites were measured in the prefrontal cortex. Serum was collected to measure corticosterone and amyloid-42 (Aβ-42) levels. Feces were collected, and the gut microbiome was analyzed.

RESULTS

WGE restored sucrose preference, exploratory behavior, recognition ability, and decreased the levels of serum corticosterone and Aβ-42 in ApoE-/- mice to alleviate depressive-like behavior and cognitive impairment. Furthermore, WGE regulated the monoamine neurotransmitter via reduced the 5-HT and DA turnover rates in the prefrontal cortex. Moreover, WGE elevated the levels of potentially beneficial bacteria such as Bifidobacterium, Akkermansia, Alloprevotella, Defluviitaleaceae_UCG-011, and Bifidobacterium pseudolongum as well as balanced fecal short-chain fatty acids (SCFAs).

CONCLUSION

WGE demonstrates anti-depressive-like effects, cognitive impairment alleviation, and gut microbiome and metabolite regulation in ApoE-/- mice. Our results support the possibility of developing a functional and complementary medicine to prevent or alleviate depression and cognitive decline using WGE in CVDs patients.

Alterations in Gut Microbiota Composition in Patients with COVID-19: A Pilot Study of Whole Hypervariable 16S rRNA Gene Sequencing

It is crucial to consider the importance of the microbiome and the gut-lung axis in the context of SARS-CoV-2 infection. This pilot study examined the fecal microbial composition of patients with COVID-19 following a 3-month recovery. Using for the first time metagenomic analysis based on all hypervariable regions (V1-V9) of the 16S rRNA gene, we have identified 561 microbial species; however, 17 were specific only for the COVID-19 group (n = 8). The patients' cohorts revealed significantly greater alpha diversity of the gut microbiota compared to healthy controls (n = 14). This finding has been demonstrated by operational taxonomic units (OTUs) richness (p < 0.001) and Chao1 index (p < 0.01). The abundance of the phylum Verrucomicrobia was 30 times higher in COVID-19 patients compared to healthy subjects. Accordingly, this disproportion was also noted at other taxonomic levels: in the class Verrucomicrobiae, the family Verrucomicrobiaceae, and the genus Akkermansia. Elevated pathobionts such as Escherichia coli, Bilophila wadsworthia, and Parabacteroides distasonis were found in COVID-19 patients. Considering the gut microbiota's ability to disturb the immune response, our findings suggest the importance of the enteric microbiota in the course of SARS-CoV-2 infection. This pilot study shows that the composition of the microbial community may not be fully restored in individuals with SARS-CoV-2 following a 3-month recovery.

Exiting the Anthropocene: Achieving personal and planetary health in the 21st century

Planetary health provides a perspective of ecological interdependence that connects the health and vitality of individuals, communities, and Earth's natural systems. It includes the social, political, and economic ecosystems that influence both individuals and whole societies. In an era of interconnected grand challenges threatening health of all systems at all scales, planetary health provides a framework for cross-sectoral collaboration and unified systems approaches to solutions. The field of allergy is at the forefront of these efforts. Allergic conditions are a sentinel measure of environmental impact on human health in early life-illuminating how ecological changes affect immune development and predispose to a wider range of inflammatory noncommunicable diseases (NCDs). This shows how adverse macroscale ecology in the Anthropocene penetrates to the molecular level of personal and microscale ecology, including the microbial systems at the foundations of all ecosystems. It provides the basis for more integrated efforts to address widespread environmental degradation and adverse effects of maladaptive urbanization, food systems, lifestyle behaviors, and socioeconomic disadvantage. Nature-based solutions and efforts to improve nature-relatedness are crucial for restoring symbiosis, balance, and mutualism in every sense, recognizing that both personal lifestyle choices and collective structural actions are needed in tandem. Ultimately, meaningful ecological approaches will depend on placing greater emphasis on psychological and cultural dimensions such as mindfulness, values, and moral wisdom to ensure a sustainable and resilient future.

Probiotics in the Management of Mental and Gastrointestinal Post-COVID Symptomes

Patients with “post-COVID” syndrome manifest with a variety of signs and symptoms that continue/develop after acute COVID-19. Among the most common are gastrointestinal (GI) and mental symptoms. The reason for symptom occurrence lies in the SARS-CoV-2 capability of binding to exact receptors, among other angiotensin converting enzyme 2 (ACE2) receptors in gastrointestinal lining and neuropilin-1 (NRP-1) in the nervous system, which leads to loss of gastrointestinal and blood-brain barriers integrity and function. The data are mounting that SARS-CoV-2 can trigger systemic inflammation and lead to disruption of gut-brain axis (GBA) and the development of disorders of gut brain interaction (DGBIs). Functional dyspepsia (FD) and irritable bowel syndrome (IBS) are the most common DGBIs syndromes. On the other hand, emotional disorders have also been demonstrated as DGBIs. Currently, there are no official recommendations or recommended procedures for the use of probiotics in patients with COVID-19. However, it can be assumed that many doctors, pharmacists, and patients will want to use a probiotic in the treatment of this disease. In such cases, strains with documented activity should be used. There is a constant need to plan and conduct new trials on the role of probiotics and verify their clinical efficacy for counteracting the negative consequences of COVID-19 pandemic. Quality control is another important but often neglected aspect in trials utilizing probiotics in various clinical entities. It determines the safety and efficacy of probiotics, which is of utmost importance in patients with post-acute COVID-19 syndrome.