Estrogen-mediated gut microbiome alterations influence sexual dimorphism in metabolic syndrome in mice

High-fat diet and estrogen modulate the gut microbiota in a sex-dependent manner in mice

A high-fat diet can lead to gut microbiota dysbiosis, chronic intestinal inflammation, and metabolic syndrome. Notably, resulting phenotypes, such as glucose and insulin levels, colonic crypt cell proliferation, and macrophage infiltration, exhibit sex differences, and females are less affected. This is, in part, attributed to sex hormones. To investigate if there are sex differences in the microbiota and if estrogenic ligands can attenuate high-fat diet-induced dysbiosis, we used whole-genome shotgun sequencing to characterize the impact of diet, sex, and estrogenic ligands on the microbial composition of the cecal content of mice. We here report clear host sex differences along with remarkably sex-dependent responses to high-fat diet. Females, specifically, exhibited increased abundance of Blautia hansenii, and its levels correlated negatively with insulin levels in both sexes. Estrogen treatment had a modest impact on the microbiota diversity but altered a few important species in males. This included Collinsella aerofaciens F, which we show correlated with colonic macrophage infiltration. In conclusion, male and female mice exhibit clear differences in their cecal microbial composition and in how diet and estrogens impact the composition. Further, specific microbial strains are significantly correlated with metabolic parameters.

The role of the sex hormone-gut microbiome axis in tumor immunotherapy

Accumulating evidence suggested that both gut microbiome and sex play a critical role in the efficacy of immune checkpoint blockade therapy. Considering the reciprocal relationship between sex hormones and gut microbiome, the sex hormone-gut microbiome axis may participate in the regulation of the response to immune checkpoint inhibitors (ICIs). In this review, it was attempted to summarize the current knowledge about the influences of both sex and gut microbiome on the antitumor efficacy of ICIs and describe the interaction between sex hormones and gut microbiome. Accordingly, this review discussed the potential of enhancing the antitumor efficacy of ICIs through regulating the levels of sex hormones through manipulation of gut microbiome. Collectively, this review provided reliable evidence concerning the role of the sex hormone-gut microbiome axis in tumor immunotherapy.

Changes in Gut Microbiome upon Orchiectomy and Testosterone Administration in AOM/DSS-Induced Colon Cancer Mouse Model

PURPOSE

Sex hormones are known to affect the gut microbiota. Previously, we reported that endogenous and exogenous testosterone are associated with colorectal cancer (CRC) development and submucosal invasion. In the present study, we investigated whether the gut microbiota is affected by orchiectomy (ORX) and testosterone propionate (TP) administration using an azoxymethane/dextran sulfate sodium (AOM/DSS)-induced CRC mouse model.

MATERIALS AND METHODS

Gut microbiota was evaluated by means of 16S rRNA gene sequencing of stool DNA extracted from feces that were obtained at 13 weeks after AOM injection (from 22-week-old animals) and stored in a gas-generating pouch.

RESULTS

The increase in microbial diversity (Chao1 and Phylogenetic Diversity index) and Firmicutes/Bacteroidetes (F/B) ratio upon AOM/DSS treatment in ORX mice was significantly decreased by TP supplementation. The ratio of commensal bacteria to opportunistic pathogens was lower in the TP-administered females and ORX mice than in the AOM/DSS group. Opportunistic pathogens (Mucispirillum schaedleri or Akkermansia muciniphila) were identified only in the TP group. In addition, microbial diversity and F/B ratio were higher in male controls than in female and ORX controls. Flintibacter butyricus, Ruminococcus bromii, and Romboutsia timonensis showed similar changes in the male control group as those in the female and ORX controls.

CONCLUSION

In conclusion, testosterone determines the dysbiosis of gut microbiota, which suggests that it plays a role in the sex-related differences in colorectal carcinogenesis.

Improvement in ovarian function following fecal microbiota transplantation from high-laying rate breeders

The underlying mechanism between the gut microbiota and reproductive function is not yet well-known. This study was conducted to investigate the effect of the administration of fecal microbiota transplantation (FMT) from highly laying rate donors on the cecal microbiota, intestinal health and ovarian function in broiler breeders. A total of 60 broiler breeders (53 wk of age) were selected by their laying rate [high (HP, 90.67 ± 0.69%; n = 10) and low (LP, 70.23 ± 0.87%; n = 20)]. The LP breeders were then be transplanted with fecal microbiota from HP hens (FMTHP; n = 10) or the same dosage of PBS (FMTCON; n = 10) for 28 d. The results revealed that FMT from HP donors increased egg-laying rate and serum hormone levels [17β-estradiol (E2), anti-Müller hormone], also decreased proinflammatory cytokine levels (interleukin-6, interleukin-8, tumor necrosis factor-α) of LP breeders (P < 0.05). The FMTHP group breeders had higher villus height, villus height/crypt depth ratio, and upregulated mRNA expression of jejunum barrier-related gene (ZO-2 and mucin-2) and estrogen, follicle-stimulating hormone (FSH) and anti-Müller hormone (AMH) receptor genes (ESR1, ESR2, FSHR, AMHR) (P < 0.05) than FMTCON group. FMT from HP donors led to higher mRNA expression of Bcl2 and sirtuin1 (SIRT1), while it downregulated the proapoptotic genes (Bax, caspase-3, caspase-8, and caspase-9) mRNA expressions in ovary compared with the FMTCON breeders (P < 0.05), and this pattern was also observed in HP donors. Also, HP breeder had higher observed_species and alpha-diversity indexes (Chao1 and ACE) than FMTCON group, while FMTHP can increase observed_species and alpha-diversity indexes (Chao1 and ACE) than FMTCON group (P < 0.05). The bacteria enrichment of Firmicutes (phylum), Bacteroidetes (phylum), Lactobacillus (genus), Enterococcus (genus), and Bacteroides (genus) were increased by FMTHP treatment. The genera Butyricicoccus, Enterococcus, and Lactobacillus were positively correlated with egg-laying rate. Therefore, cecal microbiomes of breeders with high egg-laying performance have more diverse activities, which may be related to the metabolism and health of the host; and FMT from high-yield donors can increase the hormone secretion, intestinal health, and ovarian function to improve egg-laying performance and the SIRT1-related apoptosis and cytokine signaling pathway were involved in this process.

Efficacy of Yougui pill combined with Buzhong Yiqi decoction in alleviating the sexual dysfunction in female rats through modulation of the gut microbiota

CONTEXT

Yougui pill combined with Buzhong Yiqi decoction (YPBYD) is used to relieve sexual dysfunction in clinical practice.

OBJECTIVE

To investigate changes in microbial composition caused by sexual dysfunction and identify dominant bacteria related to YPBYD treatment.

MATERIALS AND METHODS

Female Sprague-Dawley rats were randomly divided into four groups (n = 6): one group underwent Sham operation (Sham group), while three groups underwent ovariectomy (one model and two treatment groups). The ovariectomized (OVX) rats received oestradiol benzoate (250 µg/kg/week) or YPBYD (3.6 mL/d) via oral gavage for 4 weeks. Vaginal smear assay was performed; the serum levels of cyclic adenosine monophosphate (cAMP) and oestradiol (E2) were measured, followed by collection of stool samples for 16S rRNA sequencing.

RESULTS

After YPBYD treatment, the levels of E2 and cAMP in OVX rats significantly increased (E2: from 20.45 ± 1.60 ng/L to 24.38 ± 1.70 ng/L; cAMP: from 261.41 ± 9.21 pg/mL to 373.75 ± 17.37 pg/mL). OVX treatment decreased diversity of gut microbiota and YPBYD treatment restored gut microbiota composition. Compared with Sham group, the abundance of Romboutsia significantly increased, while those of Proteobacteria and Staphylococcus markedly decreased in OVX group (all p < 0.05); meanwhile, the abundance of these microbes showed an opposite trend after YPBYD treatment. These microbiotas were involved in tyrosine and tryptophan biosynthesis and fatty acid metabolism.

DISCUSSION AND CONCLUSIONS

These findings are the first to indicate YPBYD can alleviate female sexual dysfunction by modulating gut microbiota in OVX rats, which will help enhance the understanding on potential mechanism of YPBYD against sexual dysfunction.

Early life Western diet-induced memory impairments and gut microbiome changes in female rats are long-lasting despite healthy dietary intervention

OBJECTIVE

Western diet consumption during adolescence results in hippocampus (HPC)-dependent memory impairments and gut microbiome dysbiosis. Whether these adverse outcomes persist in adulthood following healthy dietary intervention is unknown. Here we assessed the short- and long-term effects of adolescent consumption of a Western diet enriched with either sugar or both sugar and fat on metabolic outcomes, HPC function, and gut microbiota.

METHODS

Adolescent female rats (PN 26) were fed a standard chow diet (CHOW), chow with access to 11% sugar solution (SUG), or a junk food cafeteria-style diet (CAF) containing various foods high in fat and/or sugar. During adulthood (PN 65+), metabolic outcomes, HPC-dependent memory, and gut microbial populations were evaluated. In a subsequent experiment, these outcomes were evaluated following a 5-week dietary intervention where CAF and SUG groups were maintained on standard chow alone.

RESULTS

Both CAF and SUG groups demonstrated impaired HPC-dependent memory, increased adiposity, and altered gut microbial populations relative to the CHOW group. However, impaired peripheral glucose regulation was only observed in the SUG group. When examined following a healthy dietary intervention in a separate experiment, metabolic dysfunction was not observed in either the CAF or SUG group, whereas HPC-dependent memory impairments were observed in the CAF but not the SUG group. In both groups the composition of the gut microbiota remained distinct from CHOW rats after the dietary intervention.

CONCLUSIONS

While the metabolic impairments associated with adolescent junk food diet consumption are not present in adulthood following dietary intervention, the HPC-dependent memory impairments and the gut microbiome dysbiosis persist.

A Chinese herbs complex ameliorates gut microbiota dysbiosis induced by intermittent cold exposure in female rats

Cold is a common source of stress in the alpine areas of northern China. It affects the microbial community, resulting in the invasion of pathogenic microorganisms and intestinal diseases. In recent years, studies have reported that Chinese herbal extracts and their fermentation broth have a significant beneficial effect on gut microbiota. This study aimed to investigate the probiotic effect of a self-designed Chinese herbs complex on the gut microbiota of rats exposed to cold. The rats were treated with intermittent cold exposure and Chinese herbs complex for 14 days, and the gut microbiota composition and other parameters were assayed. The 16s ribosomal DNA high-throughput sequencing and analysis confirmed that the Chinese herbs complex positively improved the gut microbiota. We found that cold exposure could lead to significant changes in the composition of gut microbiota, and affect the intestinal barrier and other physiological functions. The relative abundance of some probiotics in the genus such as Roseburia, Parasutterella, and Elusimicrobium in rats treated with Chinese herbs complex was significantly increased. Serum D-lactic acid (D-LA) and lipopolysaccharide (LPS) were increased in the cold exposure group and decreased in the Chinese herbs complex-treated group. Moreover, the Chinese herbs complex significantly increased the protein expression of occludin. In conclusion, the Chinese herbs complex is effective in restoring the gut microbiota caused by cold exposure, improving the function of the intestinal barrier, and may act as a prebiotic in combatting gut dysbiosis.

New Insights into the Gut Microbiota in Neurodegenerative Diseases from the Perspective of Redox Homeostasis

An imbalance between oxidants and antioxidants in the body can lead to oxidative stress, which is one of the major causes of neurodegenerative diseases. The gut microbiota contains trillions of beneficial bacteria that play an important role in maintaining redox homeostasis. In the last decade, the microbiota-gut-brain axis has emerged as a new field that has revolutionized the study of the pathology, diagnosis, and treatment of neurodegenerative diseases. Indeed, a growing number of studies have found that communication between the brain and the gut microbiota can be accomplished through the endocrine, immune, and nervous systems. Importantly, dysregulation of the gut microbiota has been strongly associated with the development of oxidative stress-mediated neurodegenerative diseases. Therefore, a deeper understanding of the relationship between the gut microbiota and redox homeostasis will help explain the pathogenesis of neurodegenerative diseases from a new perspective and provide a theoretical basis for proposing new therapeutic strategies for neurodegenerative diseases. In this review, we will describe the role of oxidative stress and the gut microbiota in neurodegenerative diseases and the underlying mechanisms by which the gut microbiota affects redox homeostasis in the brain, leading to neurodegenerative diseases. In addition, we will discuss the potential applications of maintaining redox homeostasis by modulating the gut microbiota to treat neurodegenerative diseases, which could open the door for new therapeutic approaches to combat neurodegenerative diseases.

Modulation of microbiome diversity and cytokine expression is influenced in a sex-dependent manner during aging

The microbiome and immune system have a unique interplay, which influences homeostasis within the organism. Both the microbiome and immune system play important roles in health and diseases of the aged including development of cancer, autoimmune disorders, and susceptibility to infection. Various groups have demonstrated divergent changes in the gut microbiota during aging, yet the compounding factor of biological sex within the context of aging remains incompletely understood, and little is known about the effect of housing location in the composition of gut microbiota in the context of both sex and age. To better understand the roles of sex, aging, and location in influencing the gut microbiome, we obtained normal healthy BALB/cByJ mice from a single source and aged male and female mice in two different geographical locations. The 16S rRNA was analyzed from fecal samples of these mice and cytokine levels were measured from serum.16S rRNA microbiome analysis indicated that both age and sex play a role in microbiome composition, whereas location plays a lesser role in the diversity present. Interestingly, microbiome changes occurred with alterations in serum expression of several different cytokines including IL-10 and IL-6, which were also both differentially regulated in context to sex and aging. We found both IL-10 and IL-6 play a role in the constitutive expression of pSTAT-3 in CD5+ B-1 cells, which are known to regulate the microbiome. Additionally, significant correlations were found between cytokine expression and significantly abundant microbes. Based on these results, we conclude aging mice undergo sex-associated alterations in the gut microbiome and have a distinct cytokine profile. Further, there is significant interplay between B-1 cells and the microbiome which is influenced by aging in a sex-dependent manner. Together, these results illustrate the complex interrelationship among sex, aging, immunity, housing location, and the gut microbiome.

Sex hormones, intestinal inflammation, and the gut microbiome: Major influencers of the sexual dimorphisms in obesity

Obesity is defined as the excessive accumulation of body fat and is associated with an increased risk of developing major health problems such as cardiovascular disease, diabetes and stroke. There are clear sexual dimorphisms in the epidemiology, pathophysiology and sequelae of obesity and its accompanying metabolic disorders, with females often better protected compared to males. This protection has predominantly been attributed to the female sex hormone estrogen and differences in fat distribution. More recently, the sexual dimorphisms of obesity have also been attributed to the differences in the composition and function of the gut microbiota, and the intestinal immune system. This review will comprehensively summarize the pre-clinical and clinical evidence for these sexual dimorphisms and discuss the interplay between sex hormones, intestinal inflammation and the gut microbiome in obesity. Major gaps and limitations of this rapidly growing area of research will also be highlighted in this review.

The effects of microbiota on reproductive health: A review

Reproductive issues are becoming an increasing global problem. There is increasing interest in the relationship between microbiota and reproductive health. Stable microbiota communities exist in the gut, reproductive tract, uterus, testes, and semen. Various effects (e.g., epigenetic modifications, nervous system, metabolism) of dysbiosis in the microbiota can impair gamete quality; interfere with zygote formation, embryo implantation, and embryo development; and increase disease susceptibility, thus adversely impacting reproductive capacity and pregnancy. The maintenance of a healthy microbiota can protect the host from pathogens, increase reproductive potential, and reduce the rates of adverse pregnancy outcomes. In conclusion, this review discusses microbiota in the male and female reproductive systems of multiple animal species. It explores the effects and mechanisms of microbiota on reproduction, factors that influence microbiota composition, and applications of microbiota in reproductive disorder treatment and detection. The findings support novel approaches for managing reproductive diseases through microbiota improvement and monitoring. In addition, it will stimulate further systematic explorations of microbiota-mediated effects on reproduction.

Sex as a Biological Variable in Nutrition Research: From Human Studies to Animal Models

Biological sex is a fundamental source of phenotypic variability across species. Males and females have different nutritional needs and exhibit differences in nutrient digestion and utilization, leading to different health outcomes throughout life. With personalized nutrition gaining popularity in scientific research and clinical practice, it is important to understand the fundamentals of sex differences in nutrition research. Here, we review key studies that investigate sex dimorphism in nutrition research: sex differences in nutrient intake and metabolism, sex-dimorphic response in nutrient-restricted conditions, and sex differences in diet and gut microbiome interactions. Within each area above, factors from sex chromosomes, sex hormones, and sex-specific loci are highlighted.

Metabolic protection by the dietary flavonoid 7,8-dihydroxyflavone requires an intact gut microbiome

Background

7,8-dihydroxyflavone (DHF) is a naturally occurring flavonoid found in Godmania, Tridax, and Primula species that confers protection against high-fat diet (HFD) induced metabolic pathologies selectively in female mice. We have previously reported that this metabolic protection is associated with early and stable remodeling of the intestinal microbiome, evident in female but not male DHF-supplemented mice. Early changes in the gut microbiome in female DHF-fed mice were highly predictive of subsequent metabolic protection, suggesting a causative association between the gut microbiome and the metabolic effects of DHF.

Objective

To investigate a causal association between the gut microbiome and the metabolic effects of DHF using a model of antibiotic-induced gut microbiome ablation.

Materials and methods

Age-matched male and female C57Bl6/J mice were given ad libitum access to HFD and drinking water containing vehicle or DHF for 12 weeks. For antibiotic (Abx) treatment, female mice were given drinking water containing a cocktail of antibiotics for 2 weeks prior to HFD feeding and throughout the feeding period. Metabolic phenotyping consisted of longitudinal assessments of body weights, body composition, food, and water intake, as well as measurement of energy expenditure, glucose tolerance, and plasma and hepatic lipids. Protein markers mediating the cellular effects of DHF were assessed in brown adipose tissue (BAT) and skeletal muscle.

Results

Metabolic protection conferred by DHF in female HFD-fed mice was only apparent in the presence of an intact gut microbiome. Abx-treated mice were not protected from HFD-induced obesity by DHF administration. Further, tissue activation of the tropomyosin-related kinase receptor B (TrkB) receptor, which has been attributed to the biological activity of DHF, was lost upon gut microbiome ablation, indicating a requirement for microbial “activation” of DHF for its systemic effects. In addition, we report for the first time that DHF supplementation significantly activates TrkB in BAT of female, but not male, mice uncovering a novel target tissue of DHF. DHF supplementation also increased uncoupling protein 1 (UCP1) and AMP-activated protein kinase (AMPK) protein in BAT, consistent with protection from diet-induced obesity.

Conclusion

These results establish for the first time a requirement for the gut microbiome in mediating the metabolic effects of DHF in female mice and uncover a novel target tissue that may mediate these sexually-dimorphic protective effects.

Attention-Deficit/Hyperactivity Disorder and the Gut Microbiota–Gut–Brain Axis: Closing Research Gaps through Female Inclusion in Study Design

The gastrointestinal tract harbors a densely populated community of microbes that exhibits sexual dimorphism. Dysbiosis of this community has been associated with chronic human disease states ranging from metabolic diseases to neuropsychiatric disorders (NPDs). The gut microbiota–gut–brain axis (GMGBA) is a bi-directional pathway that facilitates the interaction of the gut microflora with host physiological functions. Recently, research surrounding the potential roles of the GMGBA in the development of NPDs (e.g., depression, anxiety, and autism spectrum disorders (ASDs)) has increased. However, the role of the GMGBA in attention-deficit/hyperactivity disorder (ADHD), an NPD that affects an estimated 8.4% of children (5.1% of female and 11.5% of male children) and 4% of adults (with a male–female odds ratio of 1.6) in the United States, remains understudied. Herein, we synthesize the current literature regarding the GMGBA, ADHD, and the potentially relevant intersections between the GMGBA and ADHD. Recommendations are presented for pathways of future research into the role(s) of the GMGBA in ADHD etiology and symptomatology. Particular focus is given to the potential for the variable of host sex to act as an outcome modifier of the relationship between the GMGBA and ADHD.

Spotlight on the Gut Microbiome in Menopause: Current Insights

The gut microbiome is an important contributor to human health, shaped by many endogenous and exogenous factors. The gut microbiome displays sexual dimorphism, suggesting influence of sex hormones, and also has been shown to change with aging. Yet, little is known regarding the influence of menopause - a pivotal event of reproductive aging in women - on the gut microbiome. Here, we summarize what is known regarding the interrelationships of female sex hormones and the gut microbiome, and review the available literature on menopause, female sex hormones, and the gut microbiome in humans. Taken together, research suggests that menopause is associated with lower gut microbiome diversity and a shift toward greater similarity to the male gut microbiome, however more research is needed in large study populations to identify replicable patterns in taxa impacted by menopause. Many gaps in knowledge remain, including the role the gut microbiome may play in menopause-related disease risks, and whether menopausal hormone therapy modifies menopause-related change in the gut microbiome. Given the modifiable nature of the gut microbiome, better understanding of its role in menopause-related health will be critical to identify novel opportunities for improvement of peri- and post-menopausal health and well-being.

Sex differences associate with late microbiome alterations after murine surgical sepsis

BACKGROUND

Sepsis-induced gut microbiome alterations contribute to sepsis-related morbidity and mortality. Given evidence for improved postsepsis outcomes in females compared with males, we hypothesized that female mice maintain microbiota resilience versus males.

METHODS

Mixed-sex C57BL/6 mice underwent cecal ligation and puncture (CLP) with antibiotics, saline resuscitation, and daily chronic stress and were compared with naive (nonsepsis/no antibiotics) controls. For this work, the results of young (3-5 months) and old (18-22 months) adult mice were analyzed by sex, independent and dependent of age. Mice were sacrificed at days 7 and 14, and 16S rRNA gene sequencing was performed on fecal bacterial DNA. α and β diversity were determined by Shannon index and Bray-Curtis with principal coordinate analysis, respectively. False discovery rate (FDR) correction was implemented to account for potential housing effect.

RESULTS

In control mice, there was no difference in α or β diversity between male and female mice (FDR, 0.76 and 0.99, respectively). However, male mice that underwent CLP with daily chronic stress had a decrease in microbiota α diversity at 7 days post-CLP (Shannon FDR, 0.005), which was sustained at 14 days post-CLP (Shannon FDR, 0.001), compared with baseline. In addition, male mice maintained differences in β diversity even at day 14 compared with controls (FDR, <0.0001). In contrast, female mice had a decreased microbiota α diversity (Shannon FDR, 0.03) and β diversity (FDR, 0.02) 7 days post-CLP but recovered their α and β diversity by post-CLP day 14 (Shannon FDR, 0.5, and FDR, 0.02, respectively). Further analysis of females revealed that only young female mice were not different (β diversity) post-CLP day 14 to controls.

CONCLUSION

Although sepsis-induced perturbations of the intestinal microbiota occur initially in both male and female C57BL/6 mice, females demonstrate different microbiota by day 14. This may be seen primarily in younger females. This difference in recovery may play a role in outcome differences between sexes after sepsis.

Sex Differences in Cardiovascular Impact of Early Metabolic Impairment: Interplay between Dysbiosis and Adipose Inflammation

The evolving view of gut microbiota has shifted toward describing the colonic flora as a dynamic organ in continuous interaction with systemic physiologic processes. Alterations of the normal gut bacterial profile, known as dysbiosis, has been linked to a wide array of pathologies. Of particular interest is the cardiovascular-metabolic disease continuum originating from positive energy intake and high-fat diets. Accumulating evidence suggests a role for sex hormones in modulating the gut microbiome community. Such a role provides an additional layer of modulation of the early inflammatory changes culminating in negative metabolic and cardiovascular outcomes. In this review, we will shed the light on the role of sex hormones in cardiovascular dysfunction mediated by high-fat diet-induced dysbiosis, together with the possible involvement of insulin resistance and adipose tissue inflammation. Insights into novel therapeutic interventions will be discussed as well. SIGNIFICANCE STATEMENT: Increasing evidence implicates a role for dysbiosis in the cardiovascular complications of metabolic dysfunction. This minireview summarizes the available data on the sex-based differences in gut microbiota alterations associated with dietary patterns leading to metabolic impairment. A role for a differential impact of adipose tissue inflammation across sexes in mediating the cardiovascular detrimental phenotype following diet-induced dysbiosis is proposed. Better understanding of this pathway will help introduce early approaches to mitigate cardiovascular deterioration in metabolic disease.

Saccharomyces boulardii, a yeast probiotic, inhibits gut motility through upregulating intestinal serotonin transporter and modulating gut microbiota

Saccharomyces boulardii (Sb) is a widely used fungal probiotic in treating various digestive diseases, including irritable bowel syndrome (IBS). However, the specific mechanisms of Sb relieving IBS remain unclear. The abnormal serotonin transporter (SERT) / 5-hydroxytryptamine (5-HT) system could cause disordered gastrointestinal sensation and motility, which closely related to IBS pathogenesis. The aim of this study was to explore the effects and mechanisms of Sb on regulating gut motility. Sb supernatant (SbS) was administered to intestinal epithelial cells and mice. SbS upregulated SERT expression via enhancing heparin-binding epidermal growth factor (HB-EGF) release to activate epidermal growth factor receptor (EGFR). EGFR kinase inhibitor treatment or HB-EGF siRNA transfection in cells blocked SbS upregulating SERT. Consistently, SbS-treated mice presented inhibited gut motility, and EGFR activation and SERT upregulation were found. Moreover, 16 S rDNA sequence presented an evident decrease in Firmicutes / Bacteroidetes ratio in SbS group. In genus level, SbS reduced Escherichia_Shigella, Alistipes, Clostridium XlVa, and Saccharibacteria_genera_incertae_sedis, meanwhile, increased Parasutterella. The abundance of Saccharibacteria_genera_incertae_sedis positively correlated with defecation parameters and intestinal 5-HT content. Fecal microbiota transplantation showed that SbS could modulate gut microbiota to influence gut motility. Interestingly, elimination of gut microbiota with antibiotic cocktail did not entirely block SbS regulating gut motility. Furthermore, SbS administration to IBS-D mice significantly upregulated SERT and inhibited gut motility. In conclusion, SbS could upregulate SERT by EGFR activation, and modulate gut microbiota to inhibit gut motility. This finding would provide more evidence for the application of this yeast probiotic in IBS and other diarrheal disorders.

Menopause Is Associated with an Altered Gut Microbiome and Estrobolome, with Implications for Adverse Cardiometabolic Risk in the Hispanic Community Health Study/Study of Latinos

Menopause is a pivotal period during which loss of ovarian hormones increases cardiometabolic risk and may also influence the gut microbiome. However, the menopause-microbiome relationship has not been examined in a large study, and its implications for cardiometabolic disease are unknown. In the Hispanic Community Health Study/Study of Latinos, a population with high burden of cardiometabolic risk factors, shotgun metagenomic sequencing was performed on stool from 2,300 participants (295 premenopausal women, 1,027 postmenopausal women, and 978 men), and serum metabolomics was available on a subset. Postmenopausal women trended toward lower gut microbiome diversity and altered overall composition compared to premenopausal women, while differing less from men, in models adjusted for age and other demographic/behavioral covariates. Differentially abundant taxa for post- versus premenopausal women included Bacteroides sp. strain Ga6A1, Prevotella marshii, and Sutterella wadsworthensis (enriched in postmenopause) and Escherichia coli-Shigella spp., Oscillibacter sp. strain KLE1745, Akkermansia muciniphila, Clostridium lactatifermentans, Parabacteroides johnsonii, and Veillonella seminalis (depleted in postmenopause); these taxa similarly differed between men and women. Postmenopausal women had higher abundance of the microbial sulfate transport system and decreased abundance of microbial β-glucuronidase; these functions correlated with serum progestin metabolites, suggesting involvement of postmenopausal gut microbes in sex hormone retention. In postmenopausal women, menopause-related microbiome alterations were associated with adverse cardiometabolic profiles. In summary, in a large U.S. Hispanic/Latino population, menopause is associated with a gut microbiome more similar to that of men, perhaps related to the common condition of a low estrogen/progesterone state. Future work should examine similarity of results in other racial/ethnic groups. IMPORTANCE The menopausal transition, marked by declining ovarian hormones, is recognized as a pivotal period of cardiometabolic risk. Gut microbiota metabolically interact with sex hormones, but large population studies associating menopause with the gut microbiome are lacking. Our results from a large study of Hispanic/Latino women and men suggest that the postmenopausal gut microbiome in women is slightly more similar to the gut microbiome in men and that menopause depletes specific gut pathogens and decreases the hormone-related metabolic potential of the gut microbiome. At the same time, gut microbes may participate in sex hormone reactivation and retention in postmenopausal women. Menopause-related gut microbiome changes were associated with adverse cardiometabolic risk in postmenopausal women, indicating that the gut microbiome contributes to changes in cardiometabolic health during menopause.

Estrogen-gut microbiota interactions and irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder with a complex pathogenesis that has a serious impact on the quality of life of patients. Abnormal visceral sensation, disordered gut motility, dysregulated immunity, and damaged intestinal barrier are thought to be involved in the pathogenesis of IBS. Female predisposition to IBS strongly suggests that sex hormones such as estrogen are involved in the development of IBS. In addition, dysbiosis of the intestinal flora is closely related to IBS. The interaction between estrogen and gut microbiota in IBS has not been fully elucidated. This review summarizes and evaluates the progress of related studies. Based on the new findings and shortcomings of current studies, we discuss the directions and issues that need to be resolved in future research.

Gut Steroids and Microbiota: Effect of Gonadectomy and Sex

Sex steroids, derived mainly from gonads, can shape microbiota composition; however, the impact of gonadectomy and sex on steroid production in the gut (i.e., gut steroids), and its interaction with microbiota composition, needs to be clarified. In this study, steroid environment and gut steroidogenesis were analysed by liquid chromatography tandem mass spectrometry and expression analyses. Gut microbiota composition as branched- and short-chain fatty acids were determined by 16S rRNA gene sequence analysis and gas chromatography flame ionisation detection, respectively. Here, we first demonstrated that levels of pregnenolone (PREG), progesterone (PROG), and isoallopregnanolone (ISOALLO) were higher in the female rat colon, whereas the level of testosterone (T) was higher in males. Sexual dimorphism on gut steroidogenesis is also reported after gonadectomy. Sex, and more significantly, gonadectomy, affects microbiota composition. We noted that a number of taxa and inferred metabolic pathways were associated with gut steroids, such as positive associations between Blautia with T, dihydroprogesterone (DHP), and allopregnanolone (ALLO), whereas negative associations were noted between Roseburia and T, ALLO, PREG, ISOALLO, DHP, and PROG. In conclusion, this study highlights the novel sex-specific association between microbiota and gut steroids with possible relevance for the gut-brain axis.

Dietary regulations for microbiota dysbiosis among post-menopausal women with type 2 diabetes

Type 2 diabetes (T2D) and T2D-associated comorbidities, such as obesity, are serious universally prevalent health issues among post-menopausal women. Menopause is an unavoidable condition characterized by the depletion of estrogen, a gonadotropic hormone responsible for secondary sexual characteristics in women. In addition to sexual dimorphism, estrogen also participates in glucose-lipid homeostasis, and estrogen depletion is associated with insulin resistance in the female body. Estrogen level in the gut also regulates the microbiota composition, and even conjugated estrogen is actively metabolized by the estrobolome to maintain insulin levels. Moreover, post-menopausal gut microbiota is different from the pre-menopausal gut microbiota, as it is less diverse and lacks the mucolytic Akkermansia and short-chain fatty acid (SCFA) producers such as Faecalibacterium and Roseburia. Through various metabolites (SCFAs, secondary bile acid, and serotonin), the gut microbiota plays a significant role in regulating glucose homeostasis, oxidative stress, and T2D-associated pro-inflammatory cytokines (IL-1, IL-6). While gut dysbiosis is common among post-menopausal women, dietary interventions such as probiotics, prebiotics, and synbiotics can ease post-menopausal gut dysbiosis. The objective of this review is to understand the relationship between post-menopausal gut dysbiosis and T2D-associated factors. Additionally, the study also provided dietary recommendations to avoid T2D progression among post-menopausal women.

Intestinal Flora Mediates Antiobesity Effect of Rutin in High-Fat-Diet Mice

SCOPE

Intestinal flora plays a critical role in the development of . Rutin is a natural flavonoid with potential prebiotic effects on regulating the intestinal flora composition that is beneficial for host health. Therefore, this study hypothesizes that rutin supplementation has beneficial effects on high-fat-diet (HFD)-induced obesity and metabolic disorder through the modulation of intestinal flora in mice.

METHODS AND RESULTS

The obesity-alleviating property of rutin using 6-week-old C57BL/6J male mice fed on HFD with or without rutin supplementation for 16 weeks is investigated. Rutin supplementation effectively reduces body-weight gain, insulin resistance, and acted favorably on the intestinal barrier, thereby reducing endotoxemia and systemic inflammation. Sequencing of 16S rRNA genes from fecal samples indicate that rutin exerted modulatory effects on HFD-induced intestinal flora disorders (e.g., rutin decreased Firmicutes abundance and increased Bacteroidetes and Verrucomicrobia abundance). Antibiotic treatment and fecal microbiota transplantation further demonstrate that the salutary effects of rutin on obesity control are strongly dependent on the intestinal flora.

CONCLUSION

Rutin can be considered as a prebiotic agent for improving intestinal flora disorders and obesity-associated metabolic perturbations in obese individuals.

Decreased Tissue Omega-6/Omega-3 Fatty Acid Ratio Prevents Chemotherapy-Induced Gastrointestinal Toxicity Associated with Alterations of Gut Microbiome

Gastrointestinal toxicity (GIT) is a debilitating side effect of Irinotecan (CPT-11) and limits its clinical utility. Gut dysbiosis has been shown to mediate this side effect of CPT-11 by increasing gut bacterial β-glucuronidase (GUSB) activity and impairing the intestinal mucosal barrier (IMB). We have recently shown the opposing effects of omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFA) on the gut microbiome. We hypothesized that elevated levels of tissue n-3 PUFA with a decreased n-6/n-3 PUFA ratio would reduce CPT-11-induced GIT and associated changes in the gut microbiome. Using a unique transgenic mouse (FAT-1) model combined with dietary supplementation experiments, we demonstrate that an elevated tissue n-3 PUFA status with a decreased n-6/n-3 PUFA ratio significantly reduces CPT-11-induced weight loss, bloody diarrhea, gut pathological changes, and mortality. Gut microbiome analysis by 16S rRNA gene sequencing and QIIME2 revealed that improvements in GIT were associated with the reduction in the CPT-11-induced increase in both GUSB-producing bacteria (e.g., Enterobacteriaceae) and GUSB enzyme activity, decrease in IMB-maintaining bacteria (e.g., Bifidobacterium), IMB dysfunction and systemic endotoxemia. These results uncover a host–microbiome interaction approach to the management of drug-induced gut toxicity. The prevention of CPT-11-induced gut microbiome changes by decreasing the tissue n-6/n-3 PUFA ratio could be a novel strategy to prevent chemotherapy-induced GIT.

Interplay of gut microbiota and oxidative stress: Perspective on neurodegeneration and neuroprotection

Background

Recent research on the implications of gut microbiota on brain functions has helped to gather important information on the relationship between them. Pathogenesis of neurological disorders is found to be associated with dysregulation of gut-brain axis. Some gut bacteria metabolites are found to be directly associated with the increase in reactive oxygen species levels, one of the most important risk factors of neurodegeneration. Besides their morbid association, gut bacteria metabolites are also found to play a significant role in reducing the onset of these life-threatening brain disorders.

Aim of Review

Studies done in the recent past raises two most important link between gut microbiota and the brain: "gut microbiota-oxidative stress-neurodegeneration" and gut microbiota-antioxidant-neuroprotection. This review aims to gives a deep insight to our readers, of the collective studies done, focusing on the gut microbiota mediated oxidative stress involved in neurodegeneration along with a focus on those studies showing the involvement of gut microbiota and their metabolites in neuroprotection.

Key Scientific Concepts of Review

This review is focused on three main key concepts. Firstly, the mounting evidences from clinical and preclinical arenas shows the influence of gut microbiota mediated oxidative stress resulting in dysfunctional neurological processes. Therefore, we describe the potential role of gut microbiota influencing the vulnerability of brain to oxidative stress, and a budding causative in Alzheimer's and Parkinson's disease. Secondly, contributing roles of gut microbiota has been observed in attenuating oxidative stress and inflammation via its own metabolites or by producing secondary metabolites and, also modulation in gut microbiota population with antioxidative and anti-inflammatory probiotics have shown promising neuro resilience. Thirdly, high throughput in silico tools and databases also gives a correlation of gut microbiome, their metabolites and brain health, thus providing fascinating perspective and promising new avenues for therapeutic options.

Longitudinal analysis of the impact of oral contraceptive use on the gut microbiome

Introduction. Evidence has linked exogenous and endogenous sex hormones with the human microbiome.Hypothesis/Gap statement. The longitudinal effects of oral contraceptives (OC) on the human gut microbiome have not previously been studied.Aim. We sought to examine the longitudinal impact of OC use on the taxonomic composition and metabolic functions of the gut microbiota and endogenous sex steroid hormones after initiation of OC use.Methodology. We recruited ten healthy women who provided blood and stool samples prior to OC use, 1 month and 6 months after starting OC. We measured serum levels of sex hormones, including estradiol, progesterone, sex hormone-binding globulin (SHBG), and total testosterone. Shotgun metagenomic sequencing was performed on DNA extracted from faecal samples. Species and metabolic pathway abundances were determined using MetaPhlAn2 and HUMAnN2. Multivariate association with linear models was used to identify microbial species and metabolic pathways associated with OC use and endogenous levels of sex hormones.Results. The percentage variance of the microbial community explained by individual factors ranged from 9.9 % for age to 2.7 % for time since initiation of OC use. We observed no changes in the diversity or composition of the gut microbiome following OC initiation. However, the relative abundance of the biosynthesis pathways of peptidoglycan, amino acids (lysine, threonine, methionine, and tryptophan), and the NAD salvage pathway increased after OC initiation. In addition, serum levels of estradiol and SHBG were positively associated with Eubacterium ramulus, a flavonoid-degrading bacterium. Similarly, microbes involving biosynthesis of l-lysine, l-threonine, and l-methionine were significantly associated with lower estradiol, SHBG, and higher levels of total testosterone.Conclusion. Our study provides the first piece of evidence supporting the association between exogenous and endogenous sex hormones and gut microbiome composition and function.

Bacterial Atlas of Mouse Gut Microbiota

Background. Mouse model is one of the most widely used animal models for exploring the roles of human gut microbiota, a complex system involving in human immunity and metabolism. However, the structure of mouse gut bacterial community has not been explored at a large scale. To address this concern, the diversity and composition of the gut bacteria of 600 mice were characterized in this study. Results. The results showed that the bacteria belonging to 8 genera were found in the gut microbiota of all mouse individuals, indicating that the 8 bacteria were the core bacteria of mouse gut microbiota. The dominant genera of the mouse gut bacteria contained 15 bacterial genera. It was found that the bacteria in the gut microbiota were mainly involved in host’s metabolisms via the collaborations between the gut bacteria. The further analysis demonstrated that the composition of mouse gut microbiota was similar to that of human gut microbiota. Conclusion. Our study presented a bacterial atlas of mouse gut microbiota, providing a solid basis for investing the bacterial communities of mouse gut microbiota.

16S rRNA Gene Sequencing Revealed Changes in Gut Microbiota Composition during Pregnancy and Lactation in Mice Model

The gut microbiota play a vital role in regulating endocrine-mediated metabolism, immunity, and energy metabolism. However, little is known about the gut microbiota and metabolite composition and development throughout pregnancy and lactation. Here, we used amplicon sequencing to analyze the gut microbiota composition of 35 female mice in five stages of pregnancy and lactation, namely, non-receptive (NR) stages, sexually-receptive (SR) stages, at day 15 of pregnancy (Pre_D15), at the day of birth (Del), and at day 10 of lactation (Lac_D10). The results revealed that the α diversity of gut microbiota was significantly increased during pregnancy and lactation. In addition, the principal coordinate analysis (PCoA) conducted on the amplicon sequence variants’ (ASVs’) distribution of the 16S rRNA amplicons indicated that the microbiota composition was significantly different among the five groups. Based on a random forest analysis, Oscillospira, Dehalobacterium, and Alistipes were the most important microbiota. The abundance of Allobaculum, Oscillospira, and Ruminococcus were negatively correlated with the serum progesterone concentration, while the abundance of Oscillospira was positively correlated with the propionate and valerate concentration in the caecal contents. Moreover, the concentration of acetate and propionate in the Del and Lac_D10 stages was significantly lower than in the SR and Pre_D15 stages. Our findings indicate that some gut microbes and metabolites vary considerably at the different stages of pregnancy and during lactation stages, which can potentially be used as microbial biomarkers. These results provide information on the potential use of the identified microbes as probiotics to maintain a healthy pregnancy and lactation.

Cross-talk between the infant/maternal gut microbiota and the endocrine system: a promising topic of research

The infant gut microbiota is the set of microorganisms colonizing the baby's intestine. This complex ecosystem appears to be related to various physiological conditions of the host and it has also been shown to act as one of the most crucial determinants of infant's health. Furthermore, the mother's endocrine system, through its hormones, can have an effect on the composition of the newborn's gut microbiota. In this perspective, we summarize the recent state of the art on the intricate relationships involving the intestinal microbiota and the endocrine system of mother/baby to underline the need to study the molecular mechanisms that appear to be involved.

Bisphenol A (BPA) Leading to Obesity and Cardiovascular Complications: A Compilation of Current In Vivo Study

BPA is one of the most common endocrine disruptors that is widely being manufactured daily nationwide. Although scientific evidence supports claims of negative effects of BPA on humans, there is also evidence suggesting that a low level of BPA is safe. However, numerous in vivo trials contraindicate with this claim and there is a high possibility of BPA exposure could lead to obesity. It has been speculated that this does not stop with the exposed subjects only, but may also cause transgenerational effects. Direct disruption of endocrine regulation, neuroimmune and signaling pathways, as well as gut microbiata, has been identified to be interrupted by BPA exposure, leading to overweight or obesity. In these instances, cardiovascular complications are one of the primary notable clinical signs. In regard to this claim, this review paper discusses the role of BPA on obesity in the perspective of endocrine disruptions and possible cardiovascular complications that may arise due to BPA. Thus, the aim of this review is to outline the changes in gut microbiota and neuroimmune or signaling mechanisms involved in obesity in relation to BPA. To identify potentially relevant articles, a depth search was done on the databases Nature, PubMed, Wiley Online Library, and Medline & Ovid from the past 5 years. According to Boolean operator guideline, selected keywords such as (1) BPA OR environmental chemical AND fat OR LDL OR obese AND transgenerational effects or phenocopy (2) Endocrine disruptors OR chemical AND lipodystrophy AND phenocopy (3) Lipid profile OR weight changes AND cardiovascular effect (4) BPA AND neuroimmune OR gene signaling, were used as search terms. Upon screening, 11 articles were finalized to be further reviewed and data extraction tables containing information on (1) the type of animal model (2) duration and dosage of BPA exposure (3) changes in the lipid profile or weight (4) genes, signaling mechanism, or any neuroimmune signal involved, and (5) transgenerational effects were created. In toto, the study indicates there are high chances of BPA exposure affecting lipid profile and gene associated with lipolysis, leading to obesity. Therefore, this scoping review recapitulates the possible effects of BPA that may lead to obesity with the evidence of current in vivo trials. The biomarkers, safety concerns, recommended dosage, and the impact of COVID-19 on BPA are also briefly described.

The intestine and the microbiota in maternal glucose homeostasis during pregnancy

It is now well established that, beyond its role in nutrient processing and absorption, the intestine and its accompanying gut microbiome constitute a major site of immunological and endocrine regulation that mediates whole-body metabolism. Despite the growing field of host-microbe research, few studies explore what mechanisms govern this relationship in the context of pregnancy. During pregnancy, significant maternal metabolic adaptations are made to accommodate the additional energy demands of the developing fetus and to prevent adverse pregnancy outcomes. Recent data suggest that the maternal gut microbiota may play a role in these adaptations, but changes to maternal gut physiology and the underlying intestinal mechanisms remain unclear. In this review, we discuss selective aspects of intestinal physiology including the role of the incretin hormone, glucagon-like peptide 1 (GLP-1), and the role of the maternal gut microbiome in the maternal metabolic adaptations to pregnancy. Specifically, we discuss how bacterial components and metabolites could mediate the effects of the microbiota on host physiology, including nutrient absorption and GLP-1 secretion and action, and whether these mechanisms may change maternal insulin sensitivity and secretion during pregnancy. Finally, we discuss how these pathways could be altered in disease states during pregnancy including maternal obesity and diabetes.

Soy consumption, cognitive function, and dementia

PURPOSE OF REVIEW

With the rising number of people living with dementia, the interest in modifiable risk factors including dietary intake for dementia is increasing. Although there is a growing body of evidence investigating soy's health effects, the direction and strength of the association between soy consumption and risk of dementia and cognitive decline are still uncertain. Thus, we aimed to review the evidence linking soy consumption to dementia and cognitive function.

RECENT FINDINGS

Some studies showed that higher intake of total soy products was associated with a lower risk or prevalence of cognitive impairment. Some studies pointed to an inverse association between higher tofu consumption and cognitive function, whereas a higher intake of soybean was associated with better cognitive function.

SUMMARY

Previous studies are scarce and have provided contradictory results. Soy is a high-protein alternative to red meat and processed meat. Further studies are needed to clarify the safety and potential preventive effects particularly in healthy populations before clinical disease manifestation and irreversible injury have occurred.

Dynamic Alteration of the Gut Microbiota Associated with Obesity and Intestinal Inflammation in Ovariectomy C57BL/6 Mice

OBJECTIVE

Estrogen is a critical hormone that is mainly produced by the ovary in females. Estrogen deficiency leads to various syndromes and diseases, partly due to gut microbiota alterations. Previous studies have shown that estrogen deficiency affects the gut microbiota at 6-8 weeks after ovariectomy, but the immediate effect of estrogen deficiency on the gut microbiota remains poorly understood.

METHODS

To investigate the short time and dynamic effects of decreased estrogen levels on the gut microbiota and their potential impact on estrogen deficiency-related diseases, we performed metagenomic sequencing of 260 fecal samples from 50 ovariectomy (OVX) and 15 control C57BL/6 female mice at four time points after surgery.

RESULTS

We found that seven gut microbiota species, including E. coli, Parabacteroides unclassified, Lachnospiraceae bacterium 8_1_57FAA, Bacteroides uniformis, Veillonella unclassified, Bacteroides xylanisolvens, and Firmicutes bacterium M10_2, were abundant in OVX mice. The abundance of these species increased with time after OVX surgery. The relative abundance of the opportunistic pathogen E. coli and the Crohn's disease-related Veillonella spp. was significantly correlated with mouse weight gain in the OVX group. Butyrate production and the Entner-Doudoroff pathway were significantly enriched in the control mouse group, while the degradation of glutamic acid and aspartic acid was enriched in the OVX mouse group. As the time after OVX surgery increased, the bacterial species and metabolic pathways significantly changed and tended to suggest an inflammatory environment, indicating a subhealthy state of the gut microbiota in the OVX mouse group.

CONCLUSIONS

Taken together, our results show that the dynamic gut microbiota profile alteration caused by estrogen deficiency is related to obesity and inflammation, which may lead to immune and metabolic disorders. This study provides new clues for the treatment of estrogen deficiency-related diseases.

Distinct gut microbiomes in two polar bear subpopulations inhabiting different sea ice ecoregions

Gut microbiomes were analyzed by 16S rRNA gene metabarcoding for polar bears (Ursus maritimus) from the southern Beaufort Sea (SB), where sea ice loss has led to increased use of land-based food resources by bears, and from East Greenland (EG), where persistent sea ice has allowed hunting of ice-associated prey nearly year-round. SB polar bears showed a higher number of total (940 vs. 742) and unique (387 vs. 189) amplicon sequence variants and higher inter-individual variation compared to EG polar bears. Gut microbiome composition differed significantly between the two subpopulations and among sex/age classes, likely driven by diet variation and ontogenetic shifts in the gut microbiome. Dietary tracer analysis using fatty acid signatures for SB polar bears showed that diet explained more intrapopulation variation in gut microbiome composition and diversity than other tested variables, i.e., sex/age class, body condition, and capture year. Substantial differences in the SB gut microbiome relative to EG polar bears, and associations between SB gut microbiome and diet, suggest that the shifting foraging habits of SB polar bears tied to sea ice loss may be altering their gut microbiome, with potential consequences for nutrition and physiology.

The impact of the gut microbiota on the reproductive and metabolic endocrine system

As the gut microbiota exerts various effects on the intestinal milieu which influences distant organs and pathways, it is considered to be a full-fledged endocrine organ. The microbiota plays a major role in the reproductive endocrine system throughout a woman's lifetime by interacting with estrogen, androgens, insulin, and other hormones. Imbalance of the gut microbiota composition can lead to several diseases and conditions, such as pregnancy complications, adverse pregnancy outcomes, polycystic ovary syndrome (PCOS), endometriosis, and cancer; however, research on the mechanisms is limited. More effort should be concentrated on exploring the potential causes and underlying the mechanisms of microbiota-hormone-mediated disease, and providing novel therapeutic and preventive strategies.As the gut microbiota exerts various effects on the intestinal milieu which influences distant organs and pathways, it is considered to be a full-fledged endocrine organ. The microbiota plays a major role in the reproductive endocrine system throughout a woman's lifetime by interacting with estrogen, androgens, insulin, and other hormones. Imbalance of the gut microbiota composition can lead to several diseases and conditions, such as pregnancy complications, adverse pregnancy outcomes, polycystic ovary syndrome (PCOS), endometriosis, and cancer; however, research on the mechanisms is limited. More effort should be concentrated on exploring the potential causes and underlying the mechanisms of microbiota-hormone-mediated disease, and providing novel therapeutic and preventive strategies.

Mink (Neovison vison) fecal microbiomes are influenced by sex, temperature, and time postdefecation

Gut microbiomes encode myriad metabolic functions critical to mammalian ecology and evolution. While fresh fecal samples provide an efficient, noninvasive method of sampling gut microbiomes, collecting fresh feces from elusive species is logistically challenging. Nonfresh feces, however, may not accurately represent the gut microbiome of the host due to succession of gut microbial consortia postdefecation as well as colonization by microbes from the surrounding environment. Using American mink (Neovison vison) as a model species, we examined postdefecation microbial community succession to learn how ambient temperature and temporal sampling constraints influence the reliability of nonfresh feces to represent host gut microbiomes. To achieve our goal, we analyzed fresh mink feces (n = 5 females; n = 5 males) collected at the time of defecation from captive mink at a farm in the Upper Peninsula of Michigan and we subsequently subsampled each fecal specimen to investigate microbial community succession over five days, under both warm (21°C) and cold (–17°C to –1°C) temperature treatments. We found that both temperature and time influenced fecal microbiome composition; and we also detected significant sexual dimorphism in microbial community structures, with female mink microbiomes exhibiting significantly greater variation than males’ when exposed to the warm temperature treatment. Our results demonstrate that feces from unknown individuals can be a powerful tool for examining carnivore gut microbiomes, though rigorous study design is required because sex, ambient temperature, and time since defecation drive significant microbial variation and the sample size requirements necessary for detecting statistically significant differences between target populations is an important consideration for future ecologically meaningful research.

Multiple statistical models reveal specific volatile organic compounds affect sex hormones in American adult male: NHANES 2013-2016

BACKGROUND

Some VOCs are identified as endocrine-disrupting chemicals (EDCs), interfering with the effect of sex hormones. However, no studies focused on the common spectrum of environmental VOCs exposure affecting sex hormones in the average male population.

OBJECTIVES

We aimed to explore the association between VOCs and sex hormones in American adult males using multiple statistical models.

METHODS

The generalized linear (GLM), eXtreme Gradient Boosting (XGBoost), weighted quantile sum (WQS), Bayesian kernel machine regression (BKMR) and stratified models were used to evaluate the associations between Specific Volatile Organic Compounds and sex hormones in American adult male from NHANES 2013-2016.

RESULTS

Pearson correlation model revealed the potential co-exposure pattern among VOCs. XGBoost algorithm models and the WQS model suggested the relative importance of VOCs. BKMR models reveal that co-exposure to the VOCs was associated with increased Testosterone (TT), Estradiol (E₂), SHBG and decreased TT/E₂. GLM models revealed specific VOC exposure as an independent risk factor causing male sex hormones disorders. Stratified analysis identified the high-risk group on the VOCs exposures. We found Blood 2,5-Dimethylfuran in VOCs was the most significant effect on sex hormones in male. Testosterone increased by 213.594 (ng/dL) (124.552, 302.636) and estradiol increased by 7.229 (pg/mL) for each additional unit of blood 2,5-Dimethylfuran (ng/mL).

CONCLUSION

This study is an academic illustration of the association between VOCs exposure and sex hormones, suggesting that exposure to VOCs might be associated with sex hormone metabolic disorder in American adult males.

Gut feelings: the microbiota-gut-brain axis on steroids

The intricate connection between central and enteric nervous systems is well established with emerging evidence linking gut microbiota function as a significant new contributor to gut-brain axis signaling. Several microbial signals contribute to altered gut-brain communications, with steroids representing an important biological class that impacts central and enteric nervous system function. Neuroactive steroids contribute pathologically to neurological disorders, including dementia and depression, by modulating the activity of neuroreceptors. However, limited information is available on the influence of neuroactive steroids on the enteric nervous system and gastrointestinal function. In this review, we outline how steroids can modulate enteric nervous system function by focusing on their influence on different receptors that are present in the intestine in health and disease. We also highlight the potential role of the gut microbiota in modulating neuroactive steroid signaling along the gut-brain axis.

Differential effects of Akkermansia-enriched fecal microbiota transplant on energy balance in female mice on high-fat diet

Estrogens protect against weight gain and metabolic disruption in women and female rodents. Aberrations in the gut microbiota composition are linked to obesity and metabolic disorders. Furthermore, estrogen-mediated protection against diet-induced metabolic disruption is associated with modifications in gut microbiota. In this study, we tested if estradiol (E2)-mediated protection against obesity and metabolic disorders in female mice is dependent on gut microbiota. Specifically, we tested if fecal microbiota transplantation (FMT) from E2-treated lean female mice, supplemented with or without Akkermansia muciniphila, prevented high fat diet (HFD)-induced body weight gain, fat mass gain, and hyperglycemia in female recipients. FMT from, and cohousing with, E2-treated lean donors was not sufficient to transfer the metabolic benefits to the E2-deficient female recipients. Moreover, FMT from lean donors supplemented with A. muciniphila exacerbated HFD-induced hyperglycemia in E2-deficient recipients, suggesting its detrimental effect on the metabolic health of E2-deficient female rodents fed a HFD. Given that A. muciniphila attenuates HFD-induced metabolic insults in males, the present findings suggest a sex difference in the impact of this microbe on metabolic health.

Sexual dimorphism in glucose metabolism is shaped by androgen-driven gut microbiome

Males are generally more susceptible to impaired glucose metabolism and type 2 diabetes (T2D) than females. However, the underlying mechanisms remain to be determined. Here, we revealed that gut microbiome depletion abolished sexual dimorphism in glucose metabolism. The transfer of male donor microbiota into antibiotics-treated female mice led the recipients to be more insulin resistant. Depleting androgen via castration changed the gut microbiome of male mice to be more similar to that of females and improved glucose metabolism, while reintroducing dihydrotestosterone (DHT) reversed these alterations. More importantly, the effects of androgen on glucose metabolism were largely abolished when the gut microbiome was depleted. Next, we demonstrated that androgen modulated circulating glutamine and glutamine/glutamate (Gln/Glu) ratio partially depending on the gut microbiome, and glutamine supplementation increases insulin sensitivity in vitro. Our study identifies the effects of androgen in deteriorating glucose homeostasis partially by modulating the gut microbiome and circulating glutamine and Gln/Glu ratio, thereby contributing to the difference in glucose metabolism between the two sexes.

The gut microbiome as a biomarker of differential susceptibility to SARS-CoV-2

Coronavirus disease 2019 (COVID-19) continues to exact a devastating global toll. Ascertaining the factors underlying differential susceptibility and prognosis following viral exposure is critical to improving public health responses. We propose that gut microbes may contribute to variation in COVID-19 outcomes. We synthesise evidence for gut microbial contributions to immunity and inflammation, and associations with demographic factors affecting disease severity. We suggest mechanisms potentially underlying microbially mediated differential susceptibility to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). These include gut microbiome-mediated priming of host inflammatory responses and regulation of endocrine signalling, with consequences for the cellular features exploited by SARS-CoV-2 virions. We argue that considering gut microbiome-mediated mechanisms may offer a lens for appreciating differential susceptibility to SARS-CoV-2, potentially contributing to clinical and epidemiological approaches to understanding and managing COVID-19.

Surgical Menopause and Estrogen Therapy Modulate the Gut Microbiota, Obesity Markers, and Spatial Memory in Rats

Menopause in human females and subsequent ovarian hormone deficiency, particularly concerning 17β-estradiol (E2), increase the risk for metabolic dysfunctions associated with obesity, diabetes type 2, cardiovascular diseases, and dementia. Several studies indicate that these disorders are also strongly associated with compositional changes in the intestinal microbiota; however, how E2 deficiency and hormone therapy affect the gut microbial community is not well understood. Using a rat model, we aimed to evaluate how ovariectomy (OVX) and subsequent E2 administration drive changes in metabolic health and the gut microbial community, as well as potential associations with learning and memory. Findings indicated that OVX-induced ovarian hormone deficiency and E2 treatment had significant impacts on several health-affecting parameters, including (a) the abundance of some intestinal bacterial taxa (e.g., Bifidobacteriaceae and Porphyromonadaceae), (b) the abundance of microbial short-chain fatty acids (SCFAs) (e.g., isobutyrate), (c) weight/BMI, and (d) high-demand spatial working memory following surgical menopause. Furthermore, exploratory correlations among intestinal bacteria abundance, cognition, and BMI underscored the putative influence of surgical menopause and E2 administration on gut-brain interactions. Collectively, this study showed that surgical menopause is associated with physiological and behavioral changes, and that E2-linked compositional changes in the intestinal microbiota might contribute to some of its related negative health consequences. Overall, this study provides novel insights into interactions among endocrine and gastrointestinal systems in the post-menopausal life stage that collectively alter the risk for the development and progression of cardiovascular, metabolic, and dementia-related diseases.

Gut and Vagina Microbiota Associated With Estrus Return of Weaning Sows and Its Correlation With the Changes in Serum Metabolites

More and more studies have indicated that gut microbiota takes part in the biosynthesis and metabolism of sex hormones. Inversely, sex hormones influence the composition of gut microbiota. However, whether microbiota in the gut and vagina is associated with estrus return of weaning sows is largely unknown. Here, using 16S rRNA gene sequencing in 158 fecal and 50 vaginal samples, we reported the shifts in the gut and vaginal microbiota between normal return and non-return sows. In fecal samples, Lactobacillus and S24-7 were enriched in normal return sows, while Streptococcus luteciae, Lachnospiraceae, Clostridium, and Mogibacterium had higher abundance in non-return sows. In vaginal swabs, the operational taxonomic units (OTUs) annotated to Clostridiales, Ruminoccaceae, and Oscillospira were enriched in normal return sows, while those OTUs annotated to Campylobacter, Anaerococcus, Parvimonas, Finegoldia, and Dorea had higher abundances in non-return sows. Co-abundance group (CAG) analysis repeated the identification of the bacterial taxa associated with the estrus return of weaning sows. The predicted functional capacities in both gut and vaginal microbiome were changed between normal return and non-return sows. Serum metabolome profiles were determined by non-targeted metabolome analysis in seven normal return and six non-return sows. The metabolite features having higher abundance in normal return sows were enriched in the pathways Steroid hormone biosynthesis, Starch and sucrose metabolism, Galactose metabolism, and Vitamin B6 metabolism, while the metabolite features belonging to organic acids and derivatives, indoles and derivatives, sulfoxides, and lignans and neolignans had significantly higher abundance in non-return sows. Correlation analysis found that the changes in gut microbiota were associated with the shifts of serum metabolites and suggested that certain bacteria might affect estrus return of weaning sow through serum metabolites. These findings may provide new insights for understanding the role of the gut and vaginal microbiota in sow return to estrus after weaning.

Low Crude Protein Diet Affects the Intestinal Microbiome and Metabolome Differently in Barrows and Gilts

Low protein diets are commonly used in the growing-finishing pig stage of swine production; however, the effects of low dietary protein on the intestinal microbiota and their metabolites, and their association with pig sex, remain unclear. The present study aimed to assess the impact of a low crude protein (CP) diet on the gut microbiome and metabolome, and to reveal any relationship with sex. Barrows and gilts (both n = 24; initial body = 68.33 ± 0.881 kg) were allocated into two treatments according to sex. The four groups comprised two pairs of gilts and barrows fed with a high protein diet (CP 17% at stage I; CP 13% at stage II) and a low protein diet (CP 15% at stage I; CP 11% at stage II), respectively, for 51 d. Eight pigs in each group were slaughtered and their colon contents were collected. Intestinal microbiota and their metabolites were assessed using 16S rRNA sequencing and tandem mass spectrometry, respectively. The low protein diet increased intestinal microbiota species and richness indices (P < 0.05) in both sexes compared with the high protein diet. The sample Shannon index was different (P < 0.01) between barrows and gilts. At the genus level, unidentified Clostridiales (P < 0.05), Neisseria (P < 0.05), unidentified Prevotellaceae (P < 0.01) and Gracilibacteria (P < 0.05) were affected by dietary protein levels. The relative abundance of unidentified Prevotellaceae was different (P < 0.01) between barrows and gilts. The influence of dietary protein levels on Neisseria (P < 0.05), unidentified Prevotellaceae (P < 0.01) and Gracilibacteria (P < 0.05) were associated with sex. Metabolomic profiling indicated that dietary protein levels mainly affected intestinal metabolites in gilts rather than barrows. A total of 434 differentially abundant metabolites were identified in gilts fed the two protein diets. Correlation analysis identified that six differentially abundant microbiota communities were closely associated with twelve metabolites that were enriched for amino acids, inflammation, immune, and disease-related metabolic pathways. These results suggested that decreasing dietary protein contents changed the intestinal microbiota in growing-finishing pigs, which selectively affected the intestinal metabolite profiles in gilts.

Gut and vaginal microbiomes on steroids: implications for women's health

This review discusses the interactions of steroids with the gut and vaginal microbiomes within each life phase of adult women and the implications for women's health. Each phase of a woman's life is characterized by distinct hormonal states which drive overall physiology of both host and commensal microbes. These host-microbiome interactions underlie disease pathology in disorders that affect women across their lifetime, including bacterial vaginosis, gestational diabetes, polycystic ovary syndrome (PCOS), anxiety, depression, and obesity. Although many associations between host health and microbiome composition are well defined, the mechanistic role of the microbiome in women's health outcomes is largely unknown. This review addresses potential mechanisms by which the microbiota influences women's health and highlights gaps in current knowledge.

Distinct Changes in Gut Microbiota Are Associated with Estradiol-Mediated Protection from Diet-Induced Obesity in Female Mice

A decrease in ovarian estrogens in postmenopausal women increases the risk of weight gain, cardiovascular disease, type 2 diabetes, and chronic inflammation. While it is known that gut microbiota regulates energy homeostasis, it is unclear if gut microbiota is associated with estradiol regulation of metabolism. In this study, we tested if estradiol-mediated protection from high-fat diet (HFD)-induced obesity and metabolic changes are associated with longitudinal alterations in gut microbiota in female mice. Ovariectomized adult mice with vehicle or estradiol (E2) implants were fed chow for two weeks and HFD for four weeks. As reported previously, E2 increased energy expenditure, physical activity, insulin sensitivity, and whole-body glucose turnover. Interestingly, E2 decreased the tight junction protein occludin, suggesting E2 affects gut epithelial integrity. Moreover, E2 increased Akkermansia and decreased Erysipleotrichaceae and Streptococcaceae. Furthermore, Coprobacillus and Lactococcus were positively correlated, while Akkermansia was negatively correlated, with body weight and fat mass. These results suggest that changes in gut epithelial barrier and specific gut microbiota contribute to E2-mediated protection against diet-induced obesity and metabolic dysregulation. These findings provide support for the gut microbiota as a therapeutic target for treating estrogen-dependent metabolic disorders in women.

Accessing Dietary Effects on the Rumen Microbiome: Different Sequencing Methods Tell Different Stories

The current study employed both amplicon and shotgun sequencing to examine and compare the rumen microbiome in Angus bulls fed with either a backgrounding diet (BCK) or finishing diet (HG), to assess if both methods produce comparable results. Rumen digesta samples from 16 bulls were subjected for microbial profiling. Distinctive microbial profiles were revealed by the two methods, indicating that choice of sequencing approach may be a critical facet in studies of the rumen microbiome. Shotgun-sequencing identified the presence of 303 bacterial genera and 171 archaeal species, several of which exhibited differential abundance. Amplicon-sequencing identified 48 bacterial genera, 4 archaeal species, and 9 protozoal species. Among them, 20 bacterial genera and 5 protozoal species were differentially abundant between the two diets. Overall, amplicon-sequencing showed a more drastic diet-derived effect on the ruminal microbial profile compared to shotgun-sequencing. While both methods detected dietary differences at various taxonomic levels, few consistent patterns were evident. Opposite results were seen for the phyla Firmicutes and Bacteroidetes, and the genus Selenomonas. This study showcases the importance of sequencing platform choice and suggests a need for integrative methods that allow robust comparisons of microbial data drawn from various omic approaches, allowing for comprehensive comparisons across studies.

Independent and combined associations of urinary heavy metals exposure and serum sex hormones among adults in NHANES 2013-2016

Accumulating evidences indicated that heavy metals may disrupt human sex hormones. However, the combined effects of heavy metals on sex hormones remain to be clarified. To explore the independent and combined associations between heavy metal exposure and serum sex hormones among adults, data of 2728 adults from the National Health and Nutrition Examination Survey (NHANES) was applied. We examined independent and combined associations of fourteen urinary heavy metals and three serum sex steroid hormones (total testosterone (TT), estradiol (E2) and sex hormone-binding globulin (SHBG)). Multivariate linear regression was used to evaluate the independent associations between metal exposure and sex hormone alterations. Principle component analysis -weighted quantile sum regression (PCA-WQSR) model was performed to estimate the combined associations in our individuals. In the co-exposure model, we determined that weighted quantile sum (WQS) index of industrial pollutants was negatively associated with E2 in females (WQS Percent change_8-metal = -20.6%; 95% CI: -30.1%, -9.96%), while in males WQS index of water pollutants was negatively related to SHBG (WQS Percent change_8-metal = -5.35%; 95% CI: -9.88%, -0.598%). Cadmium (Cd), tin (Sn) and lead (Pb) were the dominating metals of female E2-negative association while Ba was the leading contributor related to male SHBG reduction, which was consistent with the results of multivariate linear regression. Additionally, in postmenopausal women, the associations of E2 decrease with heavy metal co-exposure remained significant while Cd and monomethylarsonic acid (MMA) were identified as hazardous metals in the mixture. We concluded that the exposure to heavy metals was associated with human sex hormone alterations in independent or combined manners. Considering the design of NHANES study, further studies from other national-representative surveys are necessary.

Changes in Microbial Community Composition Related to Sex and Colon Cancer by Nrf2 Knockout

The frequency of azoxymethane/dextran sulfate sodium (AOM/DSS)-induced carcinogenesis in male mice is higher than that in female mice. Previous studies have reported that 17β-estradiol inhibits tumorigenesis in males by modulating nuclear factor-erythroid 2-related factor 2 (Nrf2). This study aimed to investigate the changes in mouse gut microbiome composition based on sex, AOM/DSS-induced colorectal cancer (CRC), and Nrf2 genotype. The gut microbiome composition was determined by 16S rRNA gene sequencing fecal samples obtained at week 16 post-AOM administration. In terms of sex differences, our results showed that the wild-type (WT) male control mice had higher alpha diversity (i.e. Chao1, Shannon, and Simpson) than the WT female control mice. The linear discriminant analysis effect size (LEfSe) results revealed that the abundances of Akkermansia muciniphila and Lactobacillus murinus were higher in WT male control mice than in WT female controls. In terms of colon tumorigenesis, the alpha diversity of the male CRC group was lower than that of the male controls in both WT and Nrf2 KO, but did not show such changes in females. Furthermore, the abundance of A. muciniphila was higher in male CRC groups than in male controls in both WT and Nrf2 KO. The abundance of Bacteroides vulgatus was higher in WT CRC groups than in WT controls in both males and females. However, the abundance of L. murinus was lower in WT female CRC and Nrf2 KO male CRC groups than in its controls. The abundance of A. muciniphila was not altered by Nrf2 KO. In contrast, the abundances of L. murinus and B. vulgatus were changed differently by Nrf2 KO depending on sex and CRC. Interestingly, L. murinus showed negative correlation with tumor numbers in the whole colon. In addition, B. vulgatus showed positive correlation with inflammatory markers (i.e. myeloperoxidase and IL-1β levels), tumor numbers, and high-grade adenoma, especially, developed mucosal and submucosal invasive adenocarcinoma at the distal part of the colon. In conclusion, Nrf2 differentially alters the gut microbiota composition depending on sex and CRC induction.