Prenatal Maternal Stress Exacerbates Experimental Colitis of Offspring in Adulthood

Long-Term Implicit Epigenetic Stress Information in the Enteric Nervous System and its Contribution to Developing and Perpetuating IBS

Psychiatric and mood disorders may play an important role in the development and persistence of irritable bowel syndrome (IBS). Previously, we hypothesized that stress-induced implicit memories may persist throughout life via epigenetic processes in the enteric nervous system (ENS), independent of the central nervous system (CNS). These epigenetic memories in the ENS may contribute to developing and perpetuating IBS. Here, we further elaborate on our earlier hypothesis. That is, during pregnancy, maternal prenatal stresses perturb the HPA axis and increase circulating cortisol levels, which can affect the maternal gut microbiota. Maternal cortisol can cross the placental barrier and increase cortisol-circulating levels in the fetus. This leads to dysregulation of the HPA axis, affecting the gut microbiota, microbial metabolites, and intestinal permeability in the fetus. Microbial metabolites, such as short-chain fatty acids (which also regulate the development of fetal ENS), can modulate a range of diseases by inducing epigenetic changes. These mentioned processes suggest that stress-related, implicit, long-term epigenetic memories may be programmed into the fetal ENS during pregnancy. Subsequently, this implicit epigenetic stress information from the fetal ENS could be conveyed to the CNS through the bidirectional microbiota-gut-brain axis (MGBA), leading to perturbed functional connectivity among various brain networks and the dysregulation of affective and pain processes.

Interleukin-1 family cytokines at the crossroads of microbiome regulation in barrier health and disease

Recent advances in understanding how the microbiome can influence both the physiology and the pathogenesis of disease in humans have highlighted the importance of gaining a deeper insight into the complexities of the host-microbial dialogue. In tandem with this progress, has been a greater understanding of the biological pathways which regulate both homeostasis and inflammation at barrier tissue sites, such as the skin and the gut. In this regard, the Interleukin-1 family of cytokines, which can be segregated into IL-1, IL-18 and IL-36 subfamilies, have emerged as important custodians of barrier health and immunity. With established roles as orchestrators of various inflammatory diseases in both the skin and intestine, it is now becoming clear that IL-1 family cytokine activity is not only directly influenced by external microbes, but can also play important roles in shaping the composition of the microbiome at barrier sites. This review explores the current knowledge surrounding the evidence that places these cytokines as key mediators at the interface between the microbiome and human health and disease at the skin and intestinal barrier tissues.

Comparative characterization of the infant gut microbiome and their maternal lineage by a multi-omics approach

The human gut microbiome establishes and matures during infancy, and dysregulation at this stage may lead to pathologies later in life. We conducted a multi-omics study comprising three generations of family members to investigate the early development of the gut microbiota. Fecal samples from 200 individuals, including infants (0-12 months old; 55% females, 45% males) and their respective mothers and grandmothers, were analyzed using two independent metabolomics platforms and metagenomics. For metabolomics, gas chromatography and capillary electrophoresis coupled to mass spectrometry were applied. For metagenomics, both 16S rRNA gene and shotgun sequencing were performed. Here we show that infants greatly vary from their elders in fecal microbiota populations, function, and metabolome. Infants have a less diverse microbiota than adults and present differences in several metabolite classes, such as short- and branched-chain fatty acids, which are associated with shifts in bacterial populations. These findings provide innovative biochemical insights into the shaping of the gut microbiome within the same generational line that could be beneficial in improving childhood health outcomes.

Maternal immune activation mediated prenatal chronic stress induces Th17/Treg cell imbalance may relate to the PI3K/Akt/NF-κB signaling pathway in offspring rats

Maternal immune activation (MIA), defined as elevated levels of inflammatory markers beyond the normal range, can occur due to psychological stress, infection, and other disruptions during pregnancy. MIA affects the immune system development in offspring and increases the risk of immune-related disorders. Limited studies have investigated the effects of prenatal stress on offspring's immune system. In this study, pregnant rats were exposed to chronic unpredictable mild stress (CUMS) during pregnancy, involving seven different stressors. We examined the impact of prenatal stress stimuli on the offspring's immune system and observed activation of the PI3K/Akt/NF-κB signaling pathway, resulting in an imbalance of Th17/Treg cells in the offspring's spleen. Our findings revealed increased plasma levels of corticosterone, IL-1β, and IL-6 in female rats exposed to prenatal stress, as well as elevated serum levels of IL-6 and TNF-α in the offspring. Furthermore, we identified a correlation between cytokine levels in female rats and their offspring. Transcriptome sequencing and qPCR experiments indicated differentially expressed mRNAs in offspring exposed to prenatal stress, which may contribute to the imbalance of Th17/Treg cells through the activation of the Gng3-related PI3K/Akt/NF-κB pathway.

Long-term and trimester-specific effects of prenatal stress on the child gut microbiota

OBJECTIVE

Stress is common among pregnant individuals and is associated with an altered gut microbiota composition in infants. It is unknown if these compositional changes persist into the preschool years when the gut microbiota reaches an adult-like composition. This study aimed to investigate if indicators of prenatal stress (i.e., psychological distress and stress-related physiology) are associated with children's gut microbiota composition and metabolites at 3-4 years of age.

METHODS

Maternal-child pairs (n = 131) were from the Alberta Pregnancy Outcomes and Nutrition (APrON) cohort. Each trimester, psychological distress was measured as symptoms of anxiety (Symptom Checklist-90-R) and depressed mood (Edinburgh Postnatal Depression Scale), whereas salivary cortisol was quantified as a measure of stress-related physiology. Child stool samples were collected at 3-4 years to evaluate gut microbiota composition using 16S rRNA gene sequencing and fecal metabolome using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Associations between prenatal distress and cortisol with the gut microbiota were determined using Pearson and Spearman correlations and corrected for multiple testing. Associations between prenatal distress and cortisol with the fecal metabolome were assessed using Metaboanalyst.

RESULTS

Symptoms of depressed mood during the 2nd and 3rd trimesters and anxiety during the 2nd trimester of pregnancy were associated with increased alpha diversity of the child's gut microbiota. Cortisol levels during the 1st trimester were also associated with increased Faith PD diversity (r = 0.32), whereas cortisol levels during the 2nd trimester were associated with reduced Shannon diversity (r = -0.27). Depression scores during the 2nd and 3rd trimesters were associated with reductions in the relative abundances of Eggerthella, Parasutterella, and increases in Ruminococcaceae (rs = -0.28, rs = -0.32, rs = 0.32, respectively), as well as the fecal metabolome (e.g., branched-chain amino acid metabolism). Cortisol levels during the 2nd trimester correlated with 7 bacterial taxa, whereas 1st-trimester cortisol levels were associated with the child's fecal metabolome.

CONCLUSIONS

Prenatal distress and cortisol were associated with both child gut microbiota composition and fecal metabolome at preschool age. Understanding these associations may allow for the identification of microbiota-targeted interventions to support child developmental outcomes affected by prenatal stress.

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.

Early life adverse exposures in irritable bowel syndrome: new insights and opportunities

Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disorder worldwide. Extensive research has identified multiple factors contributing to its development, including genetic predisposition, chronic infection, gut dysbiosis, aberrant serotonin metabolism, and brain dysfunction. Recent studies have emphasized the critical role of the early life stage as a susceptibility window for IBS. Current evidence suggests that diet can heighten the risk of IBS in offspring by influencing the microbiota composition, intestinal epithelium structure, gene expression, and brain-gut axis. The use of antibiotics during pregnancy and the neonatal period disrupts the normal gut microbiota structure, aligning it with the characteristics observed in IBS patients. Additionally, early life stress impacts susceptibility to IBS by modulating TLR4, NK1, and the hypothalamic-pituitary-adrenal (HPA) axis while compromising the offspring's immune system. Formula feeding facilitates the colonization of pathogenic bacteria in the intestines, concurrently reducing the presence of probiotics. This disruption of the Th1 and Th2 cell balance in the immune system weakens the intestinal epithelial barrier. Furthermore, studies suggest that delivery mode influences the occurrence of IBS by altering the composition of gut microbes. This review aims to provide a comprehensive summary of the existing evidence regarding the impact of adverse early life exposures on IBS during pregnancy, intrapartum, and neonatal period. By consolidating this knowledge, the review enhances our understanding of the direct and indirect mechanisms underlying early life-related IBS and offers new insights and research directions from childhood to adulthood.

Desulfovibrio in the Gut: The Enemy within?

Desulfovibrio (DSV) are sulfate-reducing bacteria (SRB) that are ubiquitously present in the environment and as resident commensal bacteria within the human gastrointestinal tract. Though they are minor residents of the healthy gut, DSV are opportunistic pathobionts that may overgrow in the setting of various intestinal and extra-intestinal diseases. An increasing number of studies have demonstrated a positive correlation between DSV overgrowth (bloom) and various human diseases. While the relationship between DSV bloom and disease pathology has not been clearly established, mounting evidence suggests a causal role for these bacteria in disease development. As DSV are the most predominant genera of SRB in the gut, this review summarizes current knowledge regarding the relationship between DSV and a variety of diseases. In this study, we also discuss the mechanisms by which these bacteria may contribute to disease pathology.

Effects of compound prebiotics as prophylactic and therapeutic supplementation in a mouse model of acute colitis

Compound prebiotics (CP) have been explored in modulation of intestinal microbiota and remission of inflammatory responses in the acute colitis (AC). Yet, research on the roles of simultaneous prophylactic and therapeutic CP intervention in relation to AC remains lacking. Here, CP were pre-fed to examine preventive effects. CP, CP combined with mesalazine (5-aminosalicylic acid) (CPM), and mesalazine were used to evaluate therapeutic effects on the dextran sulfate sodium (DSS)-induced AC. Results showed that prophylactic CP and therapeutic CPM alleviated AC, evidenced by variations of body weight, colon length, spleen index, disease activity index score, histological score, and intestinal mucosa. Ruminococcus and Bifidobacterium were detected in significant abundance in the prophylactic CP and therapeutic CPM groups, respectively. Phylogenetic ecological network analysis revealed that therapeutic CPM probably had the strongest coupling between microbes in changing intestinal microbiota to influence treatment. However, changes in short-chain fatty acids (SCFAs) seemed to have no persuasive results, probably due to reduced SCFA level in feces and variability in transit, absorption, and utilization. Furthermore, therapeutic CP exerted higher value in terms of observed species and Shannon diversity, as well as a more concentrated distribution by principal coordinates analysis. Together, the favorable roles of CP in colitis provide directions for prebiotics in designing effective prophylactic functional diets and treatment strategies. KEY POINTS: • Prebiotics as prophylactic intervention effectively inhibited acute colitis. • Prebiotics as prophylactic and therapeutic interventions had distinct effects on gut microbiota. • Prebiotics combined with drug intervention had higher efficacy in treating acute colitis.

Understanding the Connection between Gut Homeostasis and Psychological Stress

Long-term exposure to adverse life events that provoke acute or chronic psychological stress (hereinafter "stress") can negatively affect physical health and even increase susceptibility to psychological illnesses, such as anxiety and depression. As a part of the hypothalamic-pituitary-adrenal axis, corticotropin-releasing factor (CRF) released from the hypothalamus is primarily responsible for the stress response. Typically, CRF disrupts the gastrointestinal system and leads to gut microbiota dysbiosis, thereby increasing risk of functional gastrointestinal diseases, such as irritable bowel syndrome. Furthermore, CRF increases oxidative damage to the colon and triggers immune responses involving mast cells, neutrophils, and monocytes. CRF even affects the differentiation of intestinal stem cells (ISCs), causing enterochromaffin cells to secrete excessive amounts of 5-hydroxytryptamine (5-HT). Therefore, stress is often accompanied by damage to the intestinal epithelial barrier function, followed by increased intestinal permeability and bacterial translocation. There are multi-network interactions between the gut microbiota and stress, and gut microbiota may relieve the effects of stress on the body. Dietary intake of probiotics can provide energy for ISCs through glycolysis, thereby alleviating the disruption to homeostasis caused by stress, and it significantly bolsters the intestinal barrier, alleviates intestinal inflammation, and maintains endocrine homeostasis. Gut microbiota also directly affect the synthesis of hormones and neurotransmitters, such as CRF, 5-HT, dopamine, and norepinephrine. Moreover, the Mediterranean diet enhances the stress resistance to some extent by regulating the intestinal flora. This article reviews recent research on how stress damages the gut and microbiota, how the gut microbiota can improve gut health by modulating injury due to stress, and how the diet relieves stress injury by interfering with intestinal microflora. This review gives insight into the potential role of the gut and its microbiota in relieving the effects of stress via the gut-brain axis.

Postnatal exposure to low-dose tetrabromobisphenol A increases the susceptibility of mammal testes to chemical-induced spermatogenic stress in adulthood

There is increasing data showing that some environmental chemicals can increase susceptibility to follow-up stress or injuries, possibly thereby contributing to certain clinical and subclinical diseases. Previous studies reported that tetrabromobisphenol A (TBBPA), one of the most used brominated flame retardants, exerted little male reproductive toxicity in terms of conventional endpoints but affected testis development and thereby caused testicular alterations at the molecular and cellular levels. Here, we aimed to reveal whether developmental exposure to TBBPA can increase testicular susceptibility to follow-up stress in adulthood. For this purpose, newborn mice were exposed to 50 or 500 μg/kg/d TBBPA for 56 days to confirm adverse effects on testes, followed by a single intraperitoneal injection of 3 mg/kg busulfan (BSF) to induce spermatogenic stress. Four weeks after BSF injection, TBBPA-treated mice exhibited severe pathological alterations, including reduced testis weight, damaged testicular histological structure, declined sperm count, apoptosis of spermatogenic cells, while no remarkable damage was observed in mice without historical exposure to TBBPA. These results demonstrate that historical exposure to TBBPA, either 50 or 500 µg/kg/d, increased the susceptibility of mouse testes to BSF-induced spermatogenic stress, resulting in severe adverse reproductive outcomes. Further analysis indicates that TBBPA-caused microtubule and microfilament damage, along with spermatogonia and spermatocyte reduction, could contributed to the increased susceptibility of testes, suggesting that these non-conventional reproductive lesions caused by chemicals should not be ignored. This is the first study to investigate the reproductive hazard of chemicals from the perspective of testicular susceptibility to stress, thereby opening a new avenue to identify environmental chemicals possibly contributing to male infertility and subfertility.

Psychological stress in inflammatory bowel disease: Psychoneuroimmunological insights into bidirectional gut–brain communications

Inflammatory bowel disease (IBD), mainly including ulcerative colitis (UC) and Crohn’s disease (CD), is an autoimmune gastrointestinal disease characterized by chronic inflammation and frequent recurrence. Accumulating evidence has confirmed that chronic psychological stress is considered to trigger IBD deterioration and relapse. Moreover, studies have demonstrated that patients with IBD have a higher risk of developing symptoms of anxiety and depression than healthy individuals. However, the underlying mechanism of the link between psychological stress and IBD remains poorly understood. This review used a psychoneuroimmunology perspective to assess possible neuro-visceral integration, immune modulation, and crucial intestinal microbiome changes in IBD. Furthermore, the bidirectionality of the brain–gut axis was emphasized in the context, indicating that IBD pathophysiology increases the inflammatory response in the central nervous system and further contributes to anxiety- and depression-like behavioral comorbidities. This information will help accurately characterize the link between psychological stress and IBD disease activity. Additionally, the clinical application of functional brain imaging, microbiota-targeted treatment, psychotherapy and antidepressants should be considered during the treatment and diagnosis of IBD with behavioral comorbidities. This review elucidates the significance of more high-quality research combined with large clinical sample sizes and multiple diagnostic methods and psychotherapy, which may help to achieve personalized therapeutic strategies for IBD patients based on stress relief.

Prenatal chronic stress impairs the learning and memory ability via inhibition of the NO/cGMP/PKG pathway in the Hippocampus of offspring

Numerous clinical and animal studies have found that antenatal chronic stress can lead to pathological changes the hippocampal development from embryos to adult, but the mechanisms are not well understood. Proteomic analyses provide a new insight to explore the potential mechanisms of this impairment. In this study, gestating rats were subjected to chronic unpredictable mild stress (CUMS) during pregnant days using nine different stimulations, and the changes of the learning and memory performance and the expression of proteins in the hippocampus of offspring were measured. It was found that prenatal chronic stress led to growth retardation, impaired spatial learning and memory ability in the offspring. Furthermore, prenatal stress caused various degrees of damage to neurons, Nissl body, mitochondria and synaptic structures in hippocampal CA3 region of offspring. In addition, 26 significantly different expressed proteins (DEPs) were found between the two groups by using isoquantitative tag-based relative and absolute quantification (iTRAQ) proteomics analysis. Further analyses of these DEPs showed that involved with different molecular functions and several biological processes, such as biological regulation and metabolic processes. Among these, the KEGG pathway enrichment showed that learning and memory impairment was mainly associated with the cyclic guanosine monophosphate protein kinase G (cGMP-PKG) pathway. At the same time, compared with OPC group, the NO, nNOS and cGMP level were significantly decreased, and the expression of PKG protein was also dropped. All of these results suggested that pregnant rats exposed to chronic psychological stress might impair spatial learning and memory ability of offspring, by disturbing the NO/cGMP/PKG signaling pathway.

Contribution of hippocampal BDNF/CREB signaling pathway and gut microbiota to emotional behavior impairment induced by chronic unpredictable mild stress during pregnancy in rats offspring

Background

Numerous studies have shown that exposure to prenatal maternal stress (PMS) is associated with various psychopathological outcomes of offspring. The accumulating evidence linking bacteria in the gut and neurons in the brain (the microbiota-gut-brain axis) has been aconsensus; however, there is a lack of research on the involvement mechanism of gut microbiota in the regulation of the BDNF/CREB signaling pathway in the hippocampus of prenatally stressed offspring.

Methods

Pregnant rats were subjected to chronic unpredictable mild stress (CUMS) to establish the prenatal maternal stress model. The body weight was measured and the behavioral changes were recorded. Offspring were tested to determine emotional state using sucrose preference test (SPT), open-field test (OFT) and suspended tail test (STT). Gut microbiota was evaluated by sequencing the microbial 16S rRNA V3-V4 region, and the interactive analysis of bacterial community structure and diversity was carried out. The expression of hippocampal BDNF, TrkB and CREB mRNA and proteins were respectively measured using RT-PCR and Western blotting.

Results

Prenatal maternal stress increased maternal plasma corticosterone levels, slowed maternal weight gain and caused depression-like behaviors (all P < 0.05). In offspring, prenatal maternal stress increased plasma corticosterone levels (P < 0.05) and emotional behavior changes (depression-like state) were observed (P < 0.05). The species abundance, diversity and composition of the offspring's gut microbiota changed after the maternal stress during pregnancy (P < 0.05). Compared with the control group's offspring, the species abundance of Lactobacillaceae was dropped, while the abundance of the Muribaculaceae species abundance was risen. Concurrent, changes in the hippocampal structure of the offspring and decreases in expression of BDNF/CREB signaling were noted (P < 0.05).

Conclusions

Prenatal maternal stress leads to high corticosterone status and abnormal emotion behavior of offspring, which may be associated with the abnormal BDNF/CREB signaling in hippocampus of offspring caused by the change of gut microbiota composition.

Dysbiosis of Gut Microbiota and Intestinal Barrier Dysfunction in Pigs with Pulmonary Inflammation Induced by Mycoplasma hyorhinis Infection

Lung inflammation induced by Mycoplasma hyorhinis infection accounts for significant economic losses in the swine industry. Increasing evidence suggests that there is cross talk between the lungs and the gut, but little is known about the effect of the lung inflammation caused by M. hyorhinis infection on gut microbiota and intestinal barrier function. Here, we investigated changes in the fecal microbiotas of pigs with M. hyorhinis infection and the microbial regulatory role of such infection in intestinal barrier function. We infected pigs with M. hyorhinis and performed 16S rRNA gene sequencing analyses of fecal samples, data-independent acquisition (DIA) quantitative proteomic analyses of intestinal mucosa, and analyses of barrier dysfunction indicators in serum. We found that pigs with M. hyorhinis infection exhibit lung and systemic inflammation, as reflected by the histopathological changes and activation of the TLR4/MyD88/NF-κB p65 signaling pathway in lung tissue, as well as the increased concentrations of serum inflammatory cytokines. Gut microbiotas tended to become disturbed, as evidenced by the enrichment of opportunistic pathogens. The increased diamine oxidase activities and d-lactate concentrations in serum and the decreased relative mRNA expression of Occludin, ZO-1, and Mucin2 indicated the impairment of intestinal barrier function. Quantitative proteomic analyses showed a variety of altered proteins involved in immunomodulatory and inflammatory functions. There was a positive correlation between the abundance of opportunistic pathogens and inflammatory-cytokine concentrations, as well as intestinal immunomodulatory proteins. Our results suggest that lung inflammation induced by M. hyorhinis infection can contribute to the dysbiosis of gut microbiota and intestinal barrier dysfunction, and dysbiosis of gut microbiota was associated with systemic inflammation and intestinal immune status.

IMPORTANCE Cumulative evidence suggests that bacterial pneumonia may contribute to the dysbiosis of the gut microbiota and other gastrointestinal symptoms. Our experiment has demonstrated that lung inflammation induced by M. hyorhinis infection was associated with gut microbiota dysbiosis and intestinal barrier dysfunction, which may provide a theoretical basis for exploring the gut-lung axis based on M. hyorhinis infection.