Host-bacterial symbiosis in health and disease

Okra extract alleviates lipopolysaccharide-induced inflammation response through the regulation of bile acids, the receptor-mediated pathway, and gut microbiota

BACKGROUND

Okra contains flavonoids and vitamin C as antioxidants and it contains polysaccharides as immunomodulators. Flavonoids regulate the inflammatory response in mice and may be related to gut microbiota. This study therefore aimed to investigate the impact of okra extract (OE) on inflammation in mice and to elucidate its underlying mechanism.

METHOD

Forty male Kunming (KM) mice were categorized into four groups: the control (CON) group, the lipopolysaccharide stimulation (LPS) group, the 5 mg mL-1 OE intervention (LPS + OE) group, and the 5 mg mL-1 OE supplementation plus mixed antibiotics (LPS + OE + ABX) group.

RESULTS

The results showed that, compared with the OE group, the expression of inflammatory signaling pathway genes was upregulated and gut barrier genes were inhibited in the OE + ABX group. The Fxr receptor was activated and the abundance of Akkermansia was increased after OE supplementation, whereas the effect was reversed in the OE + ABX group. Meanwhile, Fxr was correlated positively with Akkermansia.

CONCLUSION

The OE supplementation alleviated the inflammatory response in mice under LPS stimulation, accompanied by changes in gut microbiota and bile acid receptors, whereas the addition of antibiotics caused a disturbance to the gut microbiota in the OE group, thus reducing the effect of OE in alleviating the inflammatory response. © 2024 Society of Chemical Industry.

Lactobacillus rhamnosus HN001 facilitates the efficacy of dual PI3K/mTOR inhibition prolonging cardiac transplant survival and enhancing antitumor effect

Solid organ transplantation is a crucial treatment for patients who have reached the end stage of heart, lung, kidney, or liver failure. However, the likelihood of developing cancer post-transplantation increases. Additionally, primary malignant tumors remain a major obstacle to the long-term survival of transplanted organs. Therefore, it is essential to investigate effective therapies that can boost the immune system's ability to combat cancer and prevent allograft rejection. We established a mouse orthotopic liver tumor model and conducted allogeneic heterotopic heart transplantation. Various treatments were administered, and survival curves were generated using the Kaplan-Meier method. We also collected graft samples and measured inflammatory cytokine levels in the serum using an inflammatory array. The specificity of the histochemical techniques was tested by staining sections. We administered a combination therapy of phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) dual inhibitor BEZ235 and Lactobacillus rhamnosus HN001 to primary liver cancer model mice with cardiac allografts. Consistent with our prior findings, L. rhamnosus HN001 alleviated the intestinal flora imbalance caused by BEZ235. Our previous research confirmed that the combination of BEZ235 and L. rhamnosus HN001 significantly prolonged cardiac transplant survival.

IMPORTANCE

We observed that the combination of phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) dual inhibitor BEZ235 and Lactobacillus rhamnosus HN001 notably prolonged cardiac transplant survival while also inhibiting the progression of primary liver cancer. The combination therapy was efficacious in treating antitumor immunity and allograft rejection, as demonstrated by the efficacy results. We also found that this phenomenon was accompanied by the regulation of inflammatory IL-6 expression. Our study presents a novel and effective therapeutic approach to address antitumor immunity and prevent allograft rejection.

Microbiome and pregnancy: focus on microbial dysbiosis coupled with maternal obesity

Obesity is becoming a worldwide pandemic with over one billion people affected. Of women in the United States, who are of childbearing age, two-thirds of them are considered overweight/obese. Offspring of women with obesity have a greater likelihood of developing cardiometabolic disease later in life, therefore making obesity a transgenerational issue. Emerging topics such as maternal microbial dysbiosis with altered levels of bacterial phyla and maternal obesity programming offspring cardiometabolic disease are a novel area of research discussed in this review. In the authors' opinion, beneficial therapeutics will be developed from knowledge of bacterial-host interactions at the most specific level possible. Although there is an abundance of obesity-related microbiome research, it is not concise, readily available, nor easy to interpret at this time. This review details the current knowledge regarding the relationship between obesity and the gut microbiome, with an emphasis on maternal obesity.

The intestinal microbial metabolite acetyl l-carnitine improves gut inflammation and immune homeostasis via CADM2

Intestinal symbiotic bacteria play a key role in the regulation of immune tolerance in inflammatory bowel disease (IBD) hosts. However, the bacterial strains directly involved in this regulation and their related metabolites are largely unknown. We sought to investigate the effects of intestinal microbial metabolites on intestinal epithelium and to elucidate their therapeutic potential in regulating intestinal mucosal inflammation and immune homeostasis. Here, we used metagenomic data from Crohn's disease (CD) patients to analyze the composition of intestinal flora and identify metabolite profiles associated with disease behavior, and used the mouse model of dextran sodium sulfate (DSS)-induced colitis to characterize the therapeutic effects of the flora metabolite acetyl l-carnitine (ALC) on DSS-induced colitis. We found that intraperitoneal injection of ALC treatment could significantly alleviate the symptoms of DSS-induced colitis in mice, including prevention of weight loss, reduction in disease activity index (DAI) scores, increasing of colonic length, reduction in histological scores, and improvement in intestinal barrier function. Further, transcriptome sequencing analysis and gene silencing experiments revealed that the absence of CADM2 abolished the inhibitory effect of ALC on the TLR-MyD88 pathway in colonic epithelial cells, thereby reducing the release of inflammatory factors in colon epithelial cells. And we confirmed a significant downregulation of CADM2 expression in intestinal tissues of CD patients compared to healthy people in a population cohort. In addition, we also found that ALC increased the ratio of Treg cells in colon, and decreased the ratio of Th17 cells and macrophages, thereby improving the immune tolerance of the organism. The proposed study could be a potential approach for the treatment of CD.

New Perspectives on the Risks of Hydroxylated Polychlorinated Biphenyl (OH-PCB) Exposure: Intestinal Flora α-Glucosidase Inhibition

Polychlorinated biphenyls (PCBs) are a group of colorless and odorless environmental pollutants with a wide range of toxic effects. Some PCBs, especially less chlorinated ones, will rapidly undergo phase I metabolism after entering the body, and hydroxylated polychlorinated biphenyls (OH-PCBs) are the main metabolites of PCBs. Intestinal flora α-glucosidase is a common carbohydrate-active enzyme which is ubiquitous in human intestinal flora. It can convert complex dietary polysaccharides into monosaccharides, assisting the body in degrading complex carbohydrates and providing energy for the survival and growth of bacterial flora. The present study aims to investigate the inhibition of the activity of intestinal flora α-glucosidase by OH-PCBs. 4-Nitrophenyl-α-D-glucopyranoside (PNPG) was used as a probe substrate for α-glucosidase, and in vitro incubation experiments were conducted to study the inhibition of 26 representative OH-PCBs on α-glucosidase. Preliminary screening of in vitro incubation was performed with 100 μM of OH-PCBs. The results showed that 26 OH-PCBs generally exhibited strong inhibition of α-glucosidase. The concentration-dependent inhibition and half inhibition concentrations (IC50s) of OH-PCBs on α-glucosidase were determined. 4'-OH-PCB 86 and 4'-OH-PCB 106 were chosen as representative OH-PCBs, and the inhibition kinetic parameters (Kis) of inhibitors for α-glucosidase were determined. The inhibition kinetic parameters (Kis) of 4'-OH-PCB 86 and 4'-OH-PCB 106 for α-glucosidase are 1.007 μM and 0.538 μM, respectively. The silico docking method was used to further analyze the interaction mechanism between OH-PCBs and α-glucosidase. All these results will help us to understand the risks of OH-PCB exposure from a new perspective.

A guide to germ-free and gnotobiotic mouse technology to study health and disease

The intestinal microbiota has major influence on human physiology and modulates health and disease. Complex host-microbe interactions regulate various homeostatic processes, including metabolism and immune function, while disturbances in microbiota composition (dysbiosis) are associated with a plethora of human diseases and are believed to modulate disease initiation, progression and therapy response. The vast complexity of the human microbiota and its metabolic output represents a great challenge in unraveling the molecular basis of host-microbe interactions in specific physiological contexts. To increase our understanding of these interactions, functional microbiota research using animal models in a reductionistic setting are essential. In the dynamic landscape of gut microbiota research, the use of germ-free and gnotobiotic mouse technology, in which causal disease-driving mechanisms can be dissected, represents a pivotal investigative tool for functional microbiota research in health and disease, in which causal disease-driving mechanisms can be dissected. A better understanding of the health-modulating functions of the microbiota opens perspectives for improved therapies in many diseases. In this review, we discuss practical considerations for the design and execution of germ-free and gnotobiotic experiments, including considerations around germ-free rederivation and housing conditions, route and timing of microbial administration, and dosing protocols. This comprehensive overview aims to provide researchers with valuable insights for improved experimental design in the field of functional microbiota research.

Effects of supplemental bacteriophage on the gut microbiota and nutrient digestibility of ileal-cannulated pigs

This study measured the potential changes of the microbiota in the gastrointestinal tract and energy and nutrient digestibility by supplemental bacteriophages in pigs. Twelve castrated male pigs (initial mean body weight = 29.5 ± 2.3 kg) were surgically cannulated using T-cannula. The animals were housed individually in pens equipped with a feeder and a nipple waterer. The pigs were allotted to 1 of 3 experimental diets in a quadruplicated 3 × 2 Latin square design with 3 experimental diets, 2 periods, and 12 pigs resulting in 8 replicates per diet. The 3 diets were a control mainly based on corn and soybean meal with no antibiotics or bacteriophages, a diet containing 0.1% antibiotics, and a diet containing 0.2% bacteriophages. On day 5 of the experimental period, feces were collected and on days 6 and 7, ileal digesta were collected. Genomic DNA for bacteria were extracted from the ileal digesta and feces and the V4 region of the 16S rRNA gene was amplified. The ileal and fecal digestibility of energy, dry matter, organic matter, crude protein, and fiber was unaffected by dietary antibiotics or bacteriophages. At the phylum level, the supplemental antibiotic or bacteriophage tended to result in a higher proportion of Firmicutes (p = 0.059) and a lower proportion of Bacteroidetes (p = 0.099) in the ileal digesta samples compared with the control group with no difference between the antibiotic and bacteriophage groups. At the genus level, the supplemental antibiotic or bacteriophage tended to result in a higher proportion of Lactobacillus (p = 0.062) and a lower proportion of Bacteroides (p = 0.074) and Streptococcus (p = 0.088) in the ileal digesta compared with the control group with no difference between the antibiotic and bacteriophage groups. In the feces, supplemental antibiotics or bacteriophages reduced the proportion of Bifidobacterium compared with the control group (p = 0.029) with no difference between the antibiotic and bacteriophage groups. Overall, supplemental antibiotics and bacteriophages showed positive effect on the microbiota of in the ileal digesta without largely affecting energy or nutrient digestibility, with no differences between the antibiotic and bacteriophage groups in growing pigs.

Carboxymethylated Abrus cantoniensis polysaccharide prevents CTX-induced immunosuppression and intestinal damage by regulating intestinal flora and butyric acid content

As a Chinese folk health product, Abrus cantoniensis exhibits good immunomodulatory activity because of its polysaccharide components (ACP), and carboxymethylation of polysaccharides can often further improve the biological activity of polysaccharides. In this study, we explored the impact of prophylactic administration of carboxymethylated Abrus cantoniensis polysaccharide (CM-ACP) on immunosuppression and intestinal damage induced by cyclophosphamide (CTX) in mice. Our findings demonstrated that CM-ACP exhibited a more potent immunomodulatory activity compared to ACP. Additionally, CM-ACP effectively enhanced the abundance of short-chain fatty acid (SCFA)-producing bacteria in immunosuppressed mice and regulated the gene expression of STAT6 and STAT3 mediated pathway signals. In order to further explore the relationship among polysaccharides, intestinal immunity and intestinal flora, we performed a pseudo-sterile mouse validation experiment and fecal microbiota transplantation (FMT) experiment. The findings suggest that CM-FMT and butyrate attenuate CTX-induced immunosuppression and intestinal injury. CM-FMT and butyrate show superior immunomodulatory ability, and may effectively regulate intestinal cell metabolism and repair the damaged intestine by activating STAT6 and STAT3-mediated pathways. These findings offer new insights into the mechanisms by which CM-ACP functions as functional food or drug, facilitating immune response regulation and maintaining intestinal health.

Disease- and stage-specific alterations of the oral and fecal microbiota in Alzheimer's disease

Microbial communities in the intestinal tract are suggested to impact the ethiopathogenesis of Alzheimer's disease (AD). The human microbiome might modulate neuroinflammatory processes and contribute to neurodegeneration in AD. However, the microbial compositions in patients with AD at different stages of the disease are still not fully characterized. We used 16S rRNA analyses to investigate the oral and fecal microbiota in patients with AD and mild cognitive impairment (MCI; n = 84), at-risk individuals (APOE4 carriers; n = 17), and healthy controls (n = 50) and investigated the relationship of microbial communities and disease-specific markers via multivariate- and network-based approaches. We found a slightly decreased diversity in the fecal microbiota of patients with AD (average Chao1 diversity for AD = 212 [SD = 66]; for controls = 215 [SD = 55]) and identified differences in bacterial abundances including Bacteroidetes, Ruminococcus, Sutterella, and Porphyromonadaceae. The diversity in the oral microbiota was increased in patients with AD and at-risk individuals (average Chao1 diversity for AD = 174 [SD = 60], for at-risk group = 195 [SD = 49]). Gram-negative proinflammatory bacteria including Haemophilus, Neisseria, Actinobacillus, and Porphyromonas were dominant oral bacteria in patients with AD and MCI and the abundance correlated with the cerebrospinal fluid biomarker. Taken together, we observed a strong shift in the fecal and the oral communities of patients with AD already prominent in prodromal and, in case of the oral microbiota, in at-risk stages. This indicates stage-dependent alterations in oral and fecal microbiota in AD which may contribute to the pathogenesis via a facilitated intestinal and systemic inflammation leading to neuroinflammation and neurodegeneration.

Gut microbiota perturbations during larval stages in Bufo gargarizans tadpoles after Cu exposure with or without the presence of Pb

Cu and Pb are ubiquitous environmental contaminants, but there is limited information on their potential impacts on gut microbiota profile in anuran amphibians at different developmental stages during metamorphosis. In this study, Bufo gargarizans tadpoles were chronically exposed to Cu alone or Cu combined with Pb from Gs26 throughout metamorphosis. Morphology of tadpoles, histological characteristic and bacterial community of intestines were evaluated at three developmental stages: Gs33, Gs36, and Gs42. Results showed that Cu and Cu + Pb exposure caused various degrees of morphological and histological changes in guts at tested three stages. In addition, bacterial richness and diversity in tadpoles especially at Gs33 and Gs42 were disturbed by Cu and Cu + Pb. Beta diversity demonstrated that the bacterial community structures were influenced by both heavy metals exposure and developmental stages. Alterations in taxonomic composition were characterized by increased abundance of Proteobacteria and Firmicutes, reduction of Fusobacteriota, as well as decreased Cetobacterium and increased C39 at all three stages. Overall, response of gut bacterial diversity and composition to Cu stress depends on the developmental stage, while the altered patterns of bacterial community at Cu stress could be modified further by the presence of Pb. Moreover, predicted metabolic disorders were associated with shifts in bacterial community, but needs integrated information from metagenomic and metatranscriptomic analyses. These results contribute to the growing body of research about potential ecotoxicological effects of heavy metals on amphibian gut microbiota during metamorphosis.

Kruppel-like factor 2+ CD4 T cells avert microbiota-induced intestinal inflammation

Intestinal colonization by antigenically foreign microbes necessitates expanded peripheral immune tolerance. Here we show commensal microbiota prime expansion of CD4 T cells unified by the Kruppel-like factor 2 (KLF2) transcriptional regulator and an essential role for KLF2+ CD4 cells in averting microbiota-driven intestinal inflammation. CD4 cells with commensal specificity in secondary lymphoid organs and intestinal tissues are enriched for KLF2 expression, and distinct from FOXP3+ regulatory T cells or other differentiation lineages. Mice with conditional KLF2 deficiency in T cells develop spontaneous rectal prolapse and intestinal inflammation, phenotypes overturned by eliminating microbiota or reconstituting with donor KLF2+ cells. Activated KLF2+ cells selectively produce IL-10, and eliminating IL-10 overrides their suppressive function in vitro and protection against intestinal inflammation in vivo. Together with reduced KLF2+ CD4 cell accumulation in Crohn's disease, a necessity for the KLF2+ subpopulation of T regulatory type 1 (Tr1) cells in sustaining commensal tolerance is demonstrated.

Effects of leucism on organ development and molecular mechanisms in Northern snakehead (Channa argus) beyond pigmentation alterations

Leucism, a widespread occurrence observed in Northern snakehead (Channa argus), bestows a striking white jade-like body coloration upon affected individuals and has gained substantial popularity in commercial breeding. While the visible manifestation of leucism in snakeheads is primarily limited to body coloration, it is crucial to explore the potential influence of leucism on organ development and elucidate the underlying molecular mechanisms. Through a comparative analysis of growth differences, our study revealed that at 150 days post-fertilization, the white variety exhibited an 8.5% higher liver index and intestinal index, but experienced a 20% and 38% decreased in spleen index and renal interstitial index, respectively, suggesting an enlarged digestive area but relatively smaller immune tissues. Nonetheless, no significant differences were observed in the intestinal flora between the two varieties, suggesting the exclusion of any exogenous impacts from symbiotic flora on the growth and development of the white variety. Importantly, transcriptome analysis demonstrated that the white variety exhibited higher expression levels of innate immune genes. Furthermore, annotation of the gene sets expressed in the liver and spleen revealed 76 and 35 genes respectively, with the white variety displaying lower expression in genes associated with "Viral protein interaction with cytokine and cytokine receptor", "Protein processing in endoplasmic reticulum", and "TNF signaling pathway", while exhibiting higher expression in "Estrogen signaling pathway". Notably, three genes, namely pcdhf 4, nlrc3 card 15-like, and a pol-like were identified in both the liver and spleen, indicating their potential involvement in altering the development and innate immunity of the white variety. This study reveals the systemic impact of leucism that extends beyond mere pigmentation alterations, highlighting the prominent characteristics of this phenotype and providing a foundation for future molecular breeding programs aimed at enhancing this variety.

Complex relationship between gut microbiota and thyroid dysfunction: a bidirectional two-sample Mendelian randomization study

Background

Many studies have reported the link between gut microbiota and thyroid dysfunction. However, the causal effect of gut microbiota on thyroid dysfunction and the changes in gut microbiota after the onset of thyroid dysfunction are not clear.

Methods

A two-sample Mendelian randomization (MR) study was used to explore the complex relationship between gut microbiota and thyroid dysfunction. Data on 211 bacterial taxa were obtained from the MiBioGen consortium, and data on thyroid dysfunction, including hypothyroidism, thyroid-stimulating hormone alteration, thyroxine deficiency, and thyroid peroxidase antibodies positivity, were derived from several databases. Inverse variance weighting (IVW), weighted median, MR-Egger, weighted mode, and simple mode were applied to assess the causal effects of gut microbiota on thyroid dysfunction. Comprehensive sensitivity analyses were followed to validate the robustness of the results. Finally, a reverse MR study was conducted to explore the alteration of gut microbiota after hypothyroidism onset.

Results

Our bidirectional two-sample MR study revealed that the genera Intestinimonas, Eubacterium brachy group, Ruminiclostridium5, and Ruminococcaceae UCG004 were the risk factors for decreased thyroid function, whereas the genera Bifidobacterium and Lachnospiraceae UCG008 and phyla Actinobacteria and Verrucomicrobia were protective. The abundance of eight bacterial taxa varied after the onset of hypothyroidism. Sensitivity analysis showed that no heterogeneity or pleiotropy existed in the results of this study.

Conclusion

This novel MR study systematically demonstrated the complex relationship between gut microbiota and thyroid dysfunction, which supports the selection of more targeted probiotics to maintain thyroid-gut axis homeostasis and thus to prevent, control, and reverse the development of thyroid dysfunction.

Effects of dietary fiber in gestating sow diets - A review

The objective of this review was to provide an overview of the effects of dietary fiber (DF) on reproductive performance in gestating sows. Dietary fibers have been suggested to modulate microbiota in the intestine and the immune system of gestating sows and to improve gut health. Thus, DF may help alleviate the adverse effects of the stressful production cycle of gestating sows. These benefits may subsequently result in improved reproductive performance of sows. Previous studies have reported changes in microbiota by providing gestating sows with DF, and the responses of microbiota varied depending on the source of DF. The responses by providing DF to gestating sows were inconsistent for antioxidative capacity, hormonal response, and inflammatory response among the studies. The effects of DF on reproductive performance were also inconsistent among the previous studies. Potential reasons contributing to these inconsistent results would include variability in reproductive performance data, insufficient replication, influence of other nutrients contained in the DF diets, characteristics of DF, and experimental periods. The present meta-analysis suggests that increasing the total DF concentration by 10 percentage units (e.g., 12% to 22% as-fed basis) in gestating sow diets compared to the control group improves the litter born alive by 0.49 pigs per litter. However, based on the present review, questions remain regarding the benefits of fibers in gestating sow diets. Further research is warranted to clarify the mode of action of fibers and the association with subsequent reproductive performance in gestating sows.

Effects of temperature on the interaction between amphibian skin bacteria and Batrachochytrium dendrobatidis

Symbiotic relationships between animals and microbes are important for a range of functions, from digestion to protection from pathogens. However, the impact of temperature variation on these animal-microbe interactions remains poorly understood. Amphibians have experienced population declines and even extinctions on a global scale due to chytridiomycosis, a disease caused by chytrid fungi in the genus Batrachochytrium. Variation in susceptibility to this disease exists within and among host species. While the mechanisms generating differences in host susceptibility remain elusive, differences in immune system components, as well as variation in host and environmental temperatures, have been associated with this variation. The symbiotic cutaneous bacteria of amphibians are another potential cause for variation in susceptibility to chytridiomycosis, with some bacterial species producing antifungal metabolites that prevent the growth of Bd. The growth of both Bd and bacteria are affected by temperature, and thus we hypothesized that amphibian skin bacteria may be more effective at preventing Bd growth at certain temperatures. To test this, we collected bacteria from the skins of frogs, harvested the metabolites they produced when grown at three different temperatures, and then grew Bd in the presence of those metabolites under those same three temperatures in a three-by-three fully crossed design. We found that both the temperature at which cutaneous bacteria were grown (and metabolites produced) as well as the temperature at which Bd is grown can impact the ability of cutaneous bacteria to inhibit the growth of Bd. While some bacterial isolates showed the ability to inhibit Bd growth across multiple temperature treatments, no isolate was found to be inhibitive across all combinations of bacterial incubation or Bd challenge temperatures, suggesting that temperature affects both the metabolites produced and the effectiveness of those metabolites against the Bd pathogen. These findings move us closer to a mechanistic understanding of why chytridiomycosis outbreaks and related amphibian declines are often limited to certain climates and seasons.

Acupuncture as multi-targeted therapy for the multifactorial disease obesity: a complex neuro-endocrine-immune interplay

The prevalence of obesity has reached pandemic dimensions. It is associated with multiple comorbidities and is becoming a clinical and public health threat. Obesity is a multifactorial disease with a complex pathophysiology and interplay of various systems. A strong interplay exists between the neuro-endocrine system, the immune system with systemic chronic low-grade inflammation, and microbiome dysbiosis that can lead to the development of obesity, which in turn can exacerbate each of these factors, hence creating a vicious cycle. The conventional treatment with lifestyle modifications such as diet, physical exercise, pharmacotherapy, and bariatric surgery does not always result in sufficient weight control thus paving the way for other strategies. As one such strategy, acupuncture is increasingly used worldwide to treat obesity. This narrative review outlines the evidence for this neuro-endocrine-immune interplay in the pathophysiology of obesity. Furthermore, the existing experimental and clinical evidence of acupuncture as a multi-targeted therapy for obesity is explained and future research perspectives are discussed.

Segmented filamentous bacteria-based treatment to elicit protection against Enterobacteriaceae in Layer chickens

Introduction

Gut microbes like segmented filamentous bacteria (SFB) play a key role in gut maturation during early life, as demonstrated in humans and mice. Our previous study demonstrated oral inoculation of ileum-spores containing SFB to chickens after hatch increases early SFB gut colonization, which increases immune maturation and resistance to bacteria, like Salmonella, as tested in vitro; however, more studies are needed for treatment optimization and in vivo testing. The objectives of this study were to (1) test a treatment that includes both spores and filamentous SFB, (2) validate antimicrobial ability of the treatment in layer hens in vivo, and (3) elucidate its molecular mechanism.

Methods

One-day-old specific pathogen-free layers (n = 12 per group) were orally treated with either PBS (CON) or SFB-based treatment (SFB). At 4 days post-inoculation (DPI), both CON and SFB groups were orally challenged with Salmonella Typhimurium. Total Enterobacteriaceae and Salmonella were examined by plating and enumeration in feces at 7,10 and 14 dpi; and in the ileum, cecum, and spleen at 16 dpi in euthanized birds. The presence and levels of SFB were determined from ilea scrapings via microscopy and qPCR, respectively. Relative gene expression of host-derived antimicrobial peptides and cytokines in the distal ileum was determined by RT-qPCR.

Results

At 10 and 14 dpi, a significant decrease in total Enterobacteriaceae was observed in the feces of the SFB group. At necropsy, the level of SFB was significantly higher in the SFB group than in the CON group, while a significant decrease in total Enterobacteriaceae and Salmonella was observed in the ceca of the SFB group. RT-qPCR revealed increased expression of β-defensin 14, and cytokines IL-10 and IFNγ.

Discussion

The introduction of SFB at hatch as a prophylactic treatment may benefit commercial partners as well as consumers by reducing the incidence of Enterobacteriaceae in food animals. Reduction of these bacteria in animals would, in turn, increase animal health, productivity, and safety for consumers. Studies to optimize the treatment for poultry industry applications are ongoing in our lab.

Circulating circRNA: a social butterfly in tumors

Circular RNAs (circRNAs) are a class of single-stranded non-coding RNAs that form circular structures through irregular splicing or post-splicing events. CircRNAs are abnormally expressed in many cancers and regulate the occurrence and development of tumors. Circulating circRNAs are cell-free circRNAs present in peripheral blood, they are considered promising biomarkers due to their high stability. In recent years, more and more studies have revealed that circulating circRNAs participate in various cellular communication and regulate the occurrence and development of tumors, which involve many pathological processes such as tumorigenesis, tumor-related immunity, tumor angiogenesis, and tumor metastasis. Understanding the role of cell communication mediated by circulating circRNAs in tumor will further reveal the value and significance behind their use as biomarkers and potential therapeutic targets. In this review, we summarize the recent findings and provide an overview of the cell-cell communication mediated by circulating circRNAs, aiming to explore the role and application value of circulating circRNAs in tumors.

Comparison of the gut microbiota and metabolites between Diannan small ear pigs and Diqing Tibetan pigs

Objective

Host genetics and environment participate in the shaping of gut microbiota. Diannan small ear pigs and Diqing Tibetan pigs are excellent native pig breeds in China and live in different environments. However, the gut microbiota of Diannan small ear pigs and Diqing Tibetan pigs were still rarely understood. Therefore, this study aimed to analyze the composition characteristics of gut microbiota and metabolites in Diannan small ear pigs and Diqing Tibetan pigs.

Methods

Fresh feces of 6 pigs were randomly collected from 20 4-month-old Diannan small ear pigs (DA group) and 20 4-month-old Diqing Tibetan pigs (TA group) for high-throughput 16S rRNA sequencing and liquid chromatography-mass spectrometry (LC-MS) non-targeted metabolome analysis.

Results

The results revealed that Firmicutes and Bacteroidetes were the dominant phyla in the two groups. Chao1 and ACE indices differed substantially between DA and TA groups. Compared with the DA group, the relative abundance of Prevotellaceae, and Ruminococcus was significantly enriched in the TA group, while the relative abundance of Lachnospiraceae, Actinomyces, and Butyricicoccus was significantly reduced. Cholecalciferol, 5-dehydroepisterol, stigmasterol, adrenic acid, and docosahexaenoic acid were significantly enriched in DA group, which was involved in the steroid biosynthesis and biosynthesis of unsaturated fatty acids. 3-phenylpropanoic acid, L-tyrosine, phedrine, rhizoctin B, and rhizoctin D were significantly enriched in TA group, which was involved in the phenylalanine metabolism and phosphonate and phosphinate metabolism.

Conclusion

We found that significant differences in gut microbiota composition and metabolite between Diannan small ear pigs and Diqing Tibetan pigs, which provide a theoretical basis for exploring the relationship between gut microbiota and pig breeds.

Characterization of gut microbiota in adults with coronary atherosclerosis

Background

Cardiovascular disease, which is mainly caused by coronary atherosclerosis, is one of the leading causes of death and disability worldwide. Gut microbiota likely play an important role in coronary atherosclerosis. This study aims to investigate the microbiota profile of adults with coronary atherosclerosis to provide a theoretical basis for future research.

Methods

Fecal samples were collected from 35 adult patients diagnosed with coronary atherosclerosis and 32 healthy adults in Nanjing, China, and the V3-V4 region of 16S rDNA genes was sequenced using high-throughput sequencing. Differences in alpha diversity, beta diversity, and gut microbiota composition between the two groups were then compared.

Results

A beta diversity analysis revealed significant differences between adults with coronary atherosclerosis and controls, but there was no statistical difference in alpha diversity between the two groups. There were also differences in the composition of the gut microbiota between the two groups. The genera, Megamonas, Streptococcus, Veillonella, Ruminococcus_torques_group, Prevotella_2, Tyzzerella_4, were identified as potential biomarkers for coronary atherosclerosis.

Conclusion

There are some differences in the gut microbiota of adults with coronary atherosclerosis compared to healthy adults. The insights from this study could be used to explore microbiome-based mechanisms for coronary atherosclerosis.

Role of microbial dysbiosis in the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is the leading cause of dementia in the elderly and detected during the advanced stages where the chances of reversal are minimum. The gut-brain axis mediates a bidirectional communication between the gut and brain, which is dependent on bacterial products such as short chain fatty acids (SCFA) and neurotransmitters. Accumulating lines of evidence suggests that AD is associated with significant alteration in the composition of gut microbiota. Furthermore, transfer of gut microbiota from healthy individuals to patients can reshape the gut microbiota structure and thus holds the potential to be exploited for the treatment of various neurodegenerative disease. Moreover, AD-associated gut dysbiosis can be partially reversed by using probiotics, prebiotics, natural compounds and dietary modifications, but need further validations. Reversal of AD associated gut dysbiosis alleviate AD-associated pathological feature and therefore can be explored as a therapeutic approach in the future. The current review article will describe various studies suggesting that AD dysbiosis occurs with AD and highlights the causal role by focussing on the interventions that hold the potential to reverse the gut dysbiosis partially.

Butyrate driven raft disruption trots off enteric pathogen invasion: possible mechanism of colonization resistance

The gut microbiome derived short chain fatty acids perform multitude of functions to maintain gut homeostasis. Here we studied how butyrate stymie enteric bacterial invasion in cell using a simplistic binary model. The surface of the mammalian cells is enriched with microdomains rich in cholesterol that are known as rafts and act as entry points for pathogens. We showed that sodium butyrate treated RAW264.7 cells displayed reduced membrane cholesterol and less cholera-toxin B binding coupled with increased membrane fluidity compared to untreated cells indicating that reduced membrane cholesterol caused disruption of lipid rafts. The implication of such cellular biophysical changes on the invasion of enteric pathogenic bacteria was assessed. Our study showed, in comparison to untreated cells, butyrate-treated cells significantly reduced the invasion of Shigella and Salmonella, and these effects were found to be reversed by liposomal cholesterol treatment, increasing the likelihood that the rafts' function against bacterial invasion. The credence of ex vivo studies found to be in concordance in butyrate fed mouse model as evident from the significant drift towards a protective phenotype against virulent enteric pathogen invasion as compared to untreated mice. To produce a cytokine balance towards anti-inflammation, butyrate-treated mice produced more of the gut tissue anti-inflammatory cytokine IL-10 and less of the pro-inflammatory cytokines TNF-α, IL-6, and IFN-γ. In histological studies of Shigella infected gut revealed a startling observation where number of neutrophils infiltration was noted which was correlated with the pathology and was essentially reversed by butyrate treatment. Our results ratchet up a new dimension of our understanding how butyrate imparts resistance to pathogen invasion in the gut.

Role of microbial microbes in arsenic bioaccumulation and biotransformation in mice

Although gut microbes can affect the accumulation and metabolism of arsenic (As), the microbes contributing to these processes remain largely unknown. Therefore, this study aimed to investigate the bioaccumulation and biotransformation of arsenate [As(V)] and arsenobetaine (AsB) in mice with a disordered gut microbiome. We used cefoperazone (Cef) to construct a mouse model of gut microbiome disruption along with 16S rRNA sequencing to elucidate the effect of gut microbiome destruction on the biotransformation and bioaccumulation of As(V) and AsB. This revealed the role of specific bacteria in As metabolism. Gut microbiome destruction increased the bioaccumulation of As(V) and AsB in various organs and reduced the excretion of As(V) and AsB in the feces. Further, gut microbiome destruction was found to be important for the biotransformation of As(V). Interference with Cef can significantly decrease Blautia and Lactobacillus while increasing Enterococcus, leading to increase As accumulation in mice and enhanced methylation. We also identified Lachnoclostridium, Erysipelatoclostridium, Blautia, Lactobacillus, and Enterococcus as biomarkers involved in As bioaccumulation and biotransformation. In conclusion, specific microbes can increase As accumulation in the host, exacerbating its potential health risks.

Spinal Cord-Gut-Immune Axis and its Implications Regarding Therapeutic Development for Spinal Cord Injury

Spinal cord injury (SCI) affects ∼1,300,000 people living in the United States. Most research efforts have been focused on reversing paralysis, as this is arguably the most defining feature of SCI. The damage caused by SCI, however, extends past paralysis and includes other debilitating outcomes including immune dysfunction and gut dysbiosis. Recent efforts are now investigating the pathophysiology of and developing therapies for these more distal manifestations of SCI. One exciting avenue is the spinal cord-gut-immune axis, which proposes that gut dysbiosis amplifies lesion inflammation and impairs SCI recovery. This review will highlight the most recent findings regarding gut and immune dysfunction following SCI, and discuss how the central nervous system (CNS), gut, and immune system all coalesce to form a bidirectional axis that can impact SCI recovery. Finally, important considerations regarding how the spinal cord-gut-immune axis fits within the larger framework of therapeutic development (i.e., probiotics, fecal transplants, dietary modifications) will be discussed, emphasizing the lack of interdepartmental investigation and the missed opportunity to maximize therapeutic benefit in SCI.

Fecal microbiota transplantation attenuates Escherichia coli infected outgrowth by modulating the intestinal microbiome

BACKGROUND

Given the crucial role of gut microbiota in animal and human health, studies on modulating the intestinal microbiome for therapeutic purposes have grasped a significant attention, of which the role of fecal microbiota transplantation (FMT) has been emphasized.

METHODS

In the current study, we evaluated the effect of FMT on gut functions in Escherichia coli (E. coli) infection by using mice model. Moreover, we also investigated the subsequently dependent variables of infection, i.e., body weight, mortality, intestinal histopathology, and the expression changes in tight junction proteins (TJPs).

RESULTS

The FMT effectively decreased weight loss and mortality to a certain extent with the restoration of intestinal villi that resulted in high histological scores for jejunum tissue damage (p < 0.05). The effect of FMT on alleviating the reduction of intestinal TJPs was also proved by immunohistochemistry analysis and mRNA expression levels. Moreover, the abundance of health-threatening bacteria, belonging to phylum Proteobacteria, family Enterobacteriaceae and Tannerellaceae, genus Escherichia-Shigella, Sphingomonas, Collinsella, etc., were significantly increased, whereas beneficial bacteria, belonging to phylum Firmicutes, family Lactobacillaceae, genus Lactobacillus were decreased in the gut of infected mice. Furthermore, we sought to investigate the association of clinical symptoms with FMT treatment with modulation in gut microbiota. According to beta diversity, the microbial community of gut microbiota results reflected the similarities between non-infected and FMT groups. The improvement of the intestinal microbiota in FMT group was characterized by the significant high level of beneficial microorganisms with the synergistic decrease of Escherichia-Shigella, Acinetobacter, and other taxa.

CONCLUSION

The findings suggest a beneficial host-microbiome correlation following fecal microbiota transplanatation for controlling gut infections and pathogens-associated diseases.

The Bacterial DNA Profiling of Chorionic Villi and Amniotic Fluids Reveals Overlaps with Maternal Oral, Vaginal, and Gut Microbiomes

The in utero microbiome hypothesis has been long debated. This hypothesis will change our comprehension of the pioneer human microbiome if proved correct. In 60 uncomplicated pregnancies, we profiled the microbiome of chorionic villi (CV) and amniotic fluids (AF) in relation to maternal saliva, rectum, and vagina and the soluble cytokines cascade in the vagina, CV and AF. In our series, 12/37 (32%) AF and 10/23 (44%) CV tested positive for bacterial DNA. CV and AF harbored bacterial DNA of Streptococcus and Lactobacillus, overlapping that of the matched oral and vaginal niches, which showed a dysbiotic microbiome. In these pregnant women, the immune profiling revealed an immune hyporesponsiveness in the vagina and a high intraamniotic concentration of inflammatory cytokines. To understand the eventual role of bacterial colonization of the CV and AF and the associated immune response in the pregnancy outcome, further appropriate studies are needed. In this context, further studies should highlight if the hematogenous route could justify the spread of bacterial DNA from the oral microbiome to the placenta and if vaginal dysbiosis could favor the likelihood of identifying CV and AF positive for bacterial DNA.

Effects of Losartan, Atorvastatin, and Aspirin on Blood Pressure and Gut Microbiota in Spontaneously Hypertensive Rats

Many studies have shown that alterations in the gut microbiota are associated with hypertension. Our study aimed to observe the characteristics of the gut microbiota in hypertension and to further explore whether drug molecules can play a therapeutic role in hypertension by interfering with the gut microbiota. We evaluated the differences in the composition of the gut microbiota in spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). Meanwhile, three first-line cardiovascular disease (CVD) drugs, losartan, atorvastatin, and aspirin, were used to treat the SHR in order to observe their effects on the gut microbiota in SHR. The 16S rDNA results showed that the diversity and richness of the gut microbiota in SHR were significantly reduced compared with that of the WKY, the Firmicutes/Bacteroidetes ratio was increased, the abundances of Bifidobacterium and short chain fatty acids (SCFAs)-producing bacteria decreased, and the abundance of lactate-producing bacteria increased. In addition to lowering the blood pressure, losartan increased the abundances of Alistipes, Bacteroides, and Butyricimonas in SHR, reduced the abundances of Ruminococcaceae, Streptococcus, and Turicibacter, reduced the Firmicutes/Bacteroidetes ratio, and rebalanced the gut microbiota. Losartan also increased the abundances of Bifidobacterium and SCFAs-producing bacteria and reduced the abundance of lactate-producing bacteria. However, atorvastatin and aspirin had no significant effect on the gut microbiota in SHR. The above results showed that losartan could change the characteristics of the gut microbiota in hypertension and rebalance the gut microbiota, which may be related to lowering the blood pressure. Atorvastatin and aspirin have no significant influence on the gut microbiota in SHR.

Gut microbiota, an emergent target to shape the efficiency of cancer therapy

It is now well-acknowledged that microbiota has a profound influence on both human health and illness. The gut microbiota has recently come to light as a crucial element that influences cancer through a variety of mechanisms. The connections between the microbiome and cancer therapy are further highlighted by a number of preclinical and clinical evidence, suggesting that these complicated interactions may vary by cancer type, treatment, or even by tumor stage. The paradoxical relationship between gut microbiota and cancer therapies is that in some cancers, the gut microbiota may be necessary to maintain therapeutic efficacy, whereas, in other cancers, gut microbiota depletion significantly increases efficacy. Actually, mounting research has shown that the gut microbiota plays a crucial role in regulating the host immune response and boosting the efficacy of anticancer medications like chemotherapy and immunotherapy. Therefore, gut microbiota modulation, which aims to restore gut microbial balance, is a viable technique for cancer prevention and therapy given the expanding understanding of how the gut microbiome regulates treatment response and contributes to carcinogenesis. This review will provide an outline of the gut microbiota's role in health and disease, along with a summary of the most recent research on how it may influence the effectiveness of various anticancer medicines and affect the growth of cancer. This study will next cover the newly developed microbiota-targeting strategies including prebiotics, probiotics, and fecal microbiota transplantation (FMT) to enhance anticancer therapy effectiveness, given its significance.

Effects of waterborne Pb/Cu mixture on Chinese toad, Bufo gargarizans tadpoles: morphological, histological, and intestinal microbiota assessment

Coexistence of heavy metals in aquatic environments exert complex effects on amphibians. Here, the adverse effects of Pb (0.14 μM) combined with Cu at concentrations of 0, 0.25, and 1.0 μM were investigated in Bufo gargarizans tadpoles. Tadpoles were chronically exposed from Gosner stage (Gs) 26 to Gs 38, and morphology of tadpoles as well as intestinal histology and bacterial community were assessed. Our results indicated that Pb+Cu1.0 exposure induced significant retardation of somatic mass, total length, intestine mass, and intestine length as well as intestinal histological alterations. Pb+Cu0.25 and Pb+Cu1.0 exposure were associated with the loss of gut bacterial diversity. Proteobacteria and Bacteroidetes were two dominant phyla in tadpoles independently of heavy metal exposure, but the abundance of Proteobacteria increased significantly in Pb+Cu1.0 group and Bacteroidetes decreased significantly in all treatment groups. Furthermore, functional prediction indicated that metabolic disorders were associated with Pb+Cu0.25 and Pb+Cu1.0 exposure. Overall, relative limited shifts in intestinal bacterial diversity, composition, and functionality caused by Pb+Cu0 exposure, while coexistence of Pb and Cu induced gut dysbiosis and might further cause disturbance of metabolic homeostasis. The findings of this study provide insights into the effects of Pb and Cu coexistence on the health of amphibians.

Gut Microbiota and Tumor Immune Escape: A New Perspective for Improving Tumor Immunotherapy

The gut microbiota is a large symbiotic community of anaerobic and facultative aerobic bacteria inhabiting the human intestinal tract, and its activities significantly affect human health. Increasing evidence has suggested that the gut microbiome plays an important role in tumor-related immune regulation. In the tumor microenvironment (TME), the gut microbiome and its metabolites affect the differentiation and function of immune cells regulating the immune evasion of tumors. The gut microbiome can indirectly influence individual responses to various classical tumor immunotherapies, including immune checkpoint inhibitor therapy and adoptive immunotherapy. Microbial regulation through antibiotics, prebiotics, and fecal microbiota transplantation (FMT) optimize the composition of the gut microbiome, improving the efficacy of immunotherapy and bringing a new perspective and hope for tumor treatment.

Systems to model the personalized aspects of microbiome health and gut dysbiosis

The human gut microbiome is a complex and dynamic microbial entity that interacts with the environment and other parts of the body including the brain, heart, liver, and immune system. These multisystem interactions are highly conserved from invertebrates to humans, however the complexity and diversity of human microbiota compositions often yield a context that is unique to each individual. Yet commonalities remain across species, where a healthy gut microbiome will be rich in symbiotic commensal biota while an unhealthy gut microbiota will be experiencing abnormal blooms of pathobiont bacteria. In this review we discuss how omics technologies can be applied in a personalized approach to understand the microbial crosstalk and microbial-host interactions that affect the delicate balance between eubiosis and dysbiosis in an individual gut microbiome. We further highlight the strengths of model organisms in identifying and characterizing these conserved synergistic and/or pathogenic host-microbe interactions. And finally, we touch upon the growing area of personalized therapeutic interventions targeting gut microbiome.

Lactobacillus rhamnosus HN001 Ameliorates BEZ235-Induced Intestinal Dysbiosis and Prolongs Cardiac Transplant Survival

Cardiac allograft rejection remains a major factor limiting long-term engraftment after transplantation. A novel phosphoinositide 3-kinase (PI3K)/mTOR dual inhibitor, BEZ235, prolonged cardiac allograft survival by effectively suppressing activation of the PI3K/serine/threonine kinase (AKT)/mTOR pathway. However, long-term usage of pharmacological immunosuppressant drugs can cause intestinal microbiota dysbiosis. We established mouse models of allogeneic heterotopic heart transplantation with different treatments. Fecal samples were collected and subjected to 16S rRNA sequencing and targeted fecal metabolomic analysis. Graft samples were taken for immune cell detection by flow cytometry. Inflammatory cytokines in serum were quantified by enzyme-linked immunosorbent assay (ELISA). Compared to single-target approaches (IC-87114 and rapamycin), BEZ235 more efficiently prolongs cardiac transplant survival. Interestingly, BEZ235 reduces the diversity and abundance of the intestinal microbiota community. We demonstrated that Lactobacillus rhamnosus HN001 rescues the intestinal microbiota imbalance induced by BEZ235. IMPORTANCE Our data confirmed that the combination of BEZ235 and Lactobacillus rhamnosus HN001 significantly prolongs cardiac transplant survival. A main metabolic product of Lactobacillus rhamnosus HN001, propionic acid (PA), enriches regulatory T (Treg) cells and serves as a potent immunomodulatory supplement to BEZ235. Our study provides a novel and efficient therapeutic strategy for transplant recipients.

Epidemiological Studies of Children's Gut Microbiota: Validation of Sample Collection and Storage Methods and Microbiota Analysis of Toddlers' Feces Collected from Diapers

The composition of human gut microbiota influences human health and disease over the long term. Since the flora in specimens can easily change at ambient temperature outside the body, epidemiological studies need feasible methods of stool specimen collection and storage to be established. We aimed to validate two methods: feces frozen-stored in tubes containing guanidine thiocyanate solution for two months after collection (Method B), and feces excreted in diapers and frozen-stored (Method C). Validation was by comparison with a gold standard Method A. Bacterial flora of five adults were sampled and stored by all three methods. Bacterial composition was examined by amplicon sequencing analysis. Bland-Altman analyses showed that Methods B and C might change relative abundances of certain bacterial flora. Thereafter, we analyzed the bacterial flora of 76 toddlers (two age groups) in stools sampled and processed by Method C. The diversity indices of toddlers' flora were less than those of adults. The relative abundance of some bacteria differed significantly between children aged 1.5 and 3 years. The specimen collection and storage methods validated in this study are worth adopting in large-scale epidemiological studies, especially for small children, provided the limited accuracy for some specific bacteria is understood.

Machine Learning Algorithms Highlight tRNA Information Content and Chargaff’s Second Parity Rule Score as Important Features in Discriminating Probiotics from Non-Probiotics

Simple Summary

Probiotics are a group of beneficial microorganisms that are symbionts of the human gut microbiome. The identification of new probiotics is therefore of paramount importance from both public health and commercial perspectives. In this study, we show for the first time that Artificial Intelligence algorithms can identify novel probiotics and also discriminate them from pathogenic organisms in the human gut. We were also able to determine the information content within tRNA sequences as the key genomic features capable of characterizing probiotics.

Abstract

Probiotic bacteria are microorganisms with beneficial effects on human health and are currently used in numerous food supplements. However, no selection process is able to effectively distinguish probiotics from non-probiotic organisms on the basis of their genomic characteristics. In the current study, four Machine Learning algorithms were employed to accurately identify probiotic bacteria based on their DNA characteristics. Although the prediction accuracies of all algorithms were excellent, the Neural Network returned the highest scores in all the evaluation metrics, managing to discriminate probiotics from non-probiotics with an accuracy greater than 90%. Interestingly, our analysis also highlighted the information content of the tRNA sequences as the most important feature in distinguishing the two groups of organisms probably because tRNAs have regulatory functions and might have allowed probiotics to evolve faster in the human gut environment. Through the methodology presented here, it was also possible to identify seven promising new probiotics that have a higher information content in their tRNA sequences compared to non-probiotics. In conclusion, we prove for the first time that Machine Learning methods can discriminate human probiotic from non-probiotic organisms underlining information within tRNA sequences as the most important genomic feature in distinguishing them.

Gut microbiome and neurocritically ill patients

Since the times of Rokitansky and Cushing, we have been fascinated by the connections between the gut and the brain. Recent advances in next-generation sequencing techniques have shown that this relationship is even more complex and integral to our sense of self than previously imagined. As these techniques refine our understanding of the abundance and diversity of the gut bacterial microbiome, the relationship between the gut and the brain has been redefined. Now, this is understood as a complex symbiotic network with bidirectional communication, the gut-brain axis. The implication of this communication involves an intense focus of research on a variety of chronic psychiatric, neurological, neurodegenerative, and neuro-oncological diseases. Recently, the gut-brain axis has been studied in neurologically ill patients requiring intensive care. Preliminary studies have shown that acute brain injury changes the bacterial phenotype from one that is symbiotic with the host human to one that is pathologic, termed the “pathobiome.” This can contribute to nosocomial pneumonia and sepsis. The first studies in neurologically ill patients in the neurointensive care unit (NeuroICU) demonstrated changes in the gut microbiome between neuroICU patients and healthy matched subjects. Specifically, a decrease in short-chain fatty acid-producing bacteria and increase in harmful gut microbes have been associated with mortality and decreased function at discharge. Although these preliminary findings are exciting and have opened a new field of research in the complex NeuroICU population, there are several limitations and challenges. Further investigation is needed to confirm these correlations and understand their implications on patients in a complex intensive care environment.

Small nucleolar RNAs and SNHGs in the intestinal mucosal barrier: Emerging insights and current roles

BACKGROUND

Previous studies have focused on the involvement of small nucleolar RNAs (snoRNAs) and SNHGs in tumor cell proliferation, apoptosis, invasion, and metastasis via multiple pathways, including phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT), Wnt/β catenin, and mitogen-activated protein kinase (MAPK). These molecular mechanisms affect the integrity of the intestinal mucosal barrier.

AIM OF REVIEW

Current evidence regarding snoRNAs and SNHGs in the context of the mucosal barrier and modulation of homeostasis is fragmented. In this review, we collate the established information on snoRNAs and SNHGs as well as discuss the major pathways affecting the mucosal barrier.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Intestinal mucosal immunity, microflora, and the physical barrier are altered in non-neoplastic diseases such as inflammatory bowel diseases. Dysregulated snoRNAs and SNHGs may impact the intestinal mucosal barrier to promote the pathogenesis and progression of multiple diseases. SnoRNAs or SNHGs has been shown to be associated with poor disease behaviors, indicating that they may be exploited as prognostic biomarkers. Additionally, clarifying the complicated interactions between snoRNAs or SNHGs and the mucosal barrier may provide novel insights for the therapeutic treatment targeting strengthen the intestinal mucosal barrier.

Analysis of Gut Microbiota and Metabolites in Diannan Small Ear Sows at Diestrus and Metestrus

The physiological state of the host affects the gut microbes. The estrus cycle is critical to the reproductive cycle of sows. However, the association between gut microbes and animal estrus is poorly understood. Here, high-throughput 16S rRNA sequencing and liquid chromatography-mass spectrometry (LC-MS) non-targeted metabolome technology were used to study the estrous cycles in Diannan small ear pigs. Significantly different gut microbiota and metabolites of sows at estrous and diestrus were screened out and the correlation was analyzed. We found that the intestinal microbial composition and microbial metabolism of Diannan small ear sows were significantly different at diestrus and metestrus. The abundances of Spirochaetes, Spirochaetia, Spirochaetales, Spirochaetaceae, Deltaproteobacteria, unidentified_Alphaproteobacteria, Ruminococcus_sp_YE281, and Treponema_berlinense in intestinal microorganisms of Diannan small ear sows at metestrus are significantly higher than that at diestrus. Propionic acid, benzyl butyrate, sucrose, piperidine, and 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) were significantly enriched at metestrus compared with diestrus, which were involved in the energy metabolism-related pathways and activated protein kinase (AMPK) signaling pathway. At diestrus and metestrus, differential microbiota of unidentified_Alphaproteobacteria, Intestinimonas, Peptococcus, Terrisporobacter, and differential metabolites of piperidine, propionic acid, and benzyl butyrate, sucrose, 4-methyl catechol, and AICAR exist a certain degree of correlation. Therefore, unidentified_Alphaproteobacteria, Ruminococcus_sp_YE281, and Treponema_berlinense may have a potential role at metestrus of the Diannan small ear sows. AICAR may be apotential marker of estrus Diannan small ear sows feces, but further studies about the specific mechanism are needed. These findings provide a new perspective for sows production management and improving sows reproductive performance.

Glioma and the Gut-Brain Axis: Opportunities and Future Perspectives

The gut–brain axis has presented a valuable new dynamic in the treatment of cancer and central nervous system (CNS) diseases. However, little is known about the potential role of this axis in neuro-oncology. The goal of this review is to highlight potential implications of the gut–brain axis in neuro-oncology, in particular gliomas, and future areas of research. The gut–brain axis is a well-established biochemical signaling axis that has been associated with various CNS diseases. In neuro-oncology, recent studies have described gut microbiome differences in tumor-bearing mice and glioma patients compared to controls. These differences in the composition of the microbiome are expected to impact the metabolic functionality of each microbiome. The effects of antibiotics on the microbiome may affect tumor growth and modulate the immune system in tumor-bearing mice. Preliminary studies have shown that the gut microbiome might influence PD-L1 response in glioma-bearing mice, as previously observed in other non-CNS cancers. Groundbreaking studies have identified intratumoral bacterial DNA in several cancers including high-grade glioma. The gut microbiome and its manipulation represent a new and relatively unexplored area that could be utilized to enhance the effectiveness of therapy in glioma. Further mechanistic studies of this therapeutic strategy are needed to assess its clinical relevance.

Nocturnal Acidification: A Coordinating Cue in the Euprymna scolopes-Vibrio fischeri Symbiosis

The Vibrio fischeri–Euprymna scolopes symbiosis has become a powerful model for the study of specificity, initiation, and maintenance between beneficial bacteria and their eukaryotic partner. In this invertebrate model system, the bacterial symbionts are acquired every generation from the surrounding seawater by newly hatched squid. These symbionts colonize a specialized internal structure called the light organ, which they inhabit for the remainder of the host’s lifetime. The V. fischeri population grows and ebbs following a diel cycle, with high cell densities at night producing bioluminescence that helps the host avoid predation during its nocturnal activities. Rhythmic timing of the growth of the symbionts and their production of bioluminescence only at night is critical for maintaining the symbiosis. V. fischeri symbionts detect their population densities through a behavior termed quorum-sensing, where they secrete and detect concentrations of autoinducer molecules at high cell density when nocturnal production of bioluminescence begins. In this review, we discuss events that lead up to the nocturnal acidification of the light organ and the cues used for pre-adaptive behaviors that both host and symbiont have evolved. This host–bacterium cross talk is used to coordinate networks of regulatory signals (such as quorum-sensing and bioluminescence) that eventually provide a unique yet stable environment for V. fischeri to thrive and be maintained throughout its life history as a successful partner in this dynamic symbiosis.

An anxious relationship between Autism Spectrum Disorder and Gut Microbiota: A tangled chemistry?

Autism spectrum disorder (ASD) is a serious multifactorial neurodevelopmental disorder often accompanied by strained social communication, repetitive behaviour, immune dysregulation, and gastrointestinal (GI) issues. Recent studies have recorded a link between dysbiosis in the gut microbiota (gm) and the primary stages of ASD. A bidirectional connection (also called microbiota-gut-brain-axis) exchanges information between the gut bacteria and central nervous system. When the homeostasis of the microenvironment of the gut is dysregulated, it causes oxidative stress, affecting neuronal cells and neurotransmitters, thereby causing neurodevelopmental disorders. Studies have confirmed a difference in the constitution of gut bacteria among ASD cases and their controls. Numerous studies on animal models of ASD have shown altered gm and its association with abnormal metabolite profile and altered behaviour phenotype. This process happens due to an abnormal metabolite production in gm, leading to changes in the immune system, especially in ASD. Hence, this review aims to question the current knowledge on gm dysbiosis and its related GI discomforts and ASD behavioural symptoms and shed light on the possible therapeutic approaches available to deal with this situation. Thereby, though it is understood that more research might be needed to prove an association or causal relationship between gm and ASD, therapy with the microbiome may also be considered as an effective strategy to combat this issue.

How Gut Microbes Nurture Intestinal Stem Cells: A Drosophila Perspective

Host-microbiota interactions are key modulators of host physiology and behavior. Accumulating evidence suggests that the complex interplay between microbiota, diet and the intestine controls host health. Great emphasis has been given on how gut microbes have evolved to harvest energy from the diet to control energy balance, host metabolism and fitness. In addition, many metabolites essential for intestinal homeostasis are mainly derived from gut microbiota and can alleviate nutritional imbalances. However, due to the high complexity of the system, the molecular mechanisms that control host-microbiota mutualism, as well as whether and how microbiota affects host intestinal stem cells (ISCs) remain elusive. Drosophila encompasses a low complexity intestinal microbiome and has recently emerged as a system that might uncover evolutionarily conserved mechanisms of microbiota-derived nutrient ISC regulation. Here, we review recent studies using the Drosophila model that directly link microbiota-derived metabolites and ISC function. This research field provides exciting perspectives for putative future treatments of ISC-related diseases based on monitoring and manipulating intestinal microbiota.

Drivers of gut microbiome variation within and between groups of a wild Malagasy primate

BACKGROUND

Various aspects of sociality can benefit individuals' health. The host social environment and its relative contributions to the host-microbiome relationship have emerged as key topics in microbial research. Yet, understanding the mechanisms that lead to structural variation in the social microbiome, the collective microbial metacommunity of an animal's social network, remains difficult since multiple processes operate simultaneously within and among animal social networks. Here, we examined the potential drivers of the convergence of the gut microbiome on multiple scales among and within seven neighbouring groups of wild Verreaux's sifakas (Propithecus verreauxi) - a folivorous primate of Madagascar.

RESULTS

Over four field seasons, we collected 519 faecal samples of 41 animals and determined gut communities via 16S and 18S rRNA gene amplicon analyses. First, we examined whether group members share more similar gut microbiota and if diet, home range overlap, or habitat similarity drive between-group variation in gut communities, accounting for seasonality. Next, we examined within-group variation in gut microbiota by examining the potential effects of social contact rates, male rank, and maternal relatedness. To explore the host intrinsic effects on the gut community structure, we investigated age, sex, faecal glucocorticoid metabolites, and female reproductive state. We found that group members share more similar gut microbiota and differ in alpha diversity, while none of the environmental predictors explained the patterns of between-group variation. Maternal relatedness played an important role in within-group microbial homogeneity and may also explain why adult group members shared the least similar gut microbiota. Also, dominant males differed in their bacterial composition from their group mates, which might be driven by rank-related differences in physiology and scent-marking behaviours. Links to sex, female reproductive state, or faecal glucocorticoid metabolites were not detected.

CONCLUSIONS

Environmental factors define the general set-up of population-specific gut microbiota, but intrinsic and social factors have a stronger impact on gut microbiome variation in this primate species. Video abstract.

Gut Microbiota and Psychiatric Disorders: A Two-Sample Mendelian Randomization Study

Evidence supports the observational associations of gut microbiota with a variety of psychiatric disorders, but the causal nature of such associations remains obscure. Aiming to comprehensively investigate their causal relationship and to identify specific causal microbe taxa for psychiatric diseases, we conducted a two-sample Mendelian randomization (MR) analysis of gut microbiome with 15 psychiatric diseases. Specifically, the microbiome genome-wide association study (GWAS) in 18,473 individuals from the MiBioGen study was used as exposure sample, and the GWAS for 15 psychiatric diseases was used as outcome samples. One-hundred ninety bacterial taxa from six levels were available for analysis. At a multiple-testing corrected significance level (phylum P < 5.56 × 10^–3, class P < 3.33 × 10^–3, order P < 2.63 × 10^–3, family P < 1.67 × 10^–3, genus P < 4.90 × 10^–4, and species P < 3.33 × 10^–3), the following eight causal associations from seven bacterial features (one phylum + three classes + one order + one family + one species) were identified: family Prevotellaceae with autism spectrum disorder (P = 5.31 × 10^–4), class Betaproteobacteria with bipolar disorder (P = 1.53 × 10^–3), class Actinobacteria with schizophrenia (P = 1.33 × 10^–3), class Bacteroidia and order Bacteroidales with Tourette syndrome (P = 2.51 × 10^–3 and 2.51 × 10^–3), phylum Actinobacteria and class Actinobacteria with extroversion (P = 8.22 × 10^–4 and 1.09 × 10^–3), and species Clostridium innocuum with neuroticism (P = 8.92 × 10^–4). Sensitivity analysis showed no evidence of reverse causality, pleiotropy, and heterogeneity. Our findings offered novel insights into the gut microbiota–mediated development mechanism of psychiatric disorders.

Why Do These Microbes Like Me and How Could There Be a Link with Cardiovascular Risk Factors?

Cardiovascular diseases are the most common causes of hospitalization, death, and disability in Europe. Due to high prevalence and ensuing clinical complications, they lead to very high social and economic costs. Despite the knowledge of classical cardiovascular risk factors, there is an urgent need for discovering new factors that may play a role in the development of cardiovascular diseases or potentially influence prognosis. Recently, particular attention has been drawn to the endogenous microflora of the human body, mostly those inhabiting the digestive system. It has been shown that bacteria, along with their host cells, create an interactive ecosystem of interdependencies and relationships. This interplay could influence both the metabolic homeostasis and the immune processes of the host, hence leading to cardiovascular disease development. In this review, we attempt to describe, in the context of cardiovascular risk factors, why particular microbes occur in individuals and how they might influence the host’s cardiovascular system in health and disease.

Gut microbiota in patients with Alzheimer's disease spectrum: a systematic review and meta-analysis

CONTEXT

Gut dysbiosis has been proposed as one of pathologies in patients with Alzheimer's disease (AD) spectrum. Despite such enthusiasm, the relevant results remain substantially controversial.

OBJECTIVE

A systematic review and meta-analysis were performed to investigate the differences of gut microbiota (GM) between patients with AD spectrum (including mild cognitive impairment [MCI] and AD) and healthy controls (HC).

DATA SOURCES

PubMed, MEDLINE, Scopus, and Cochrane Library from January 2000 to August 2021. Eligibility criteria for study selection: Observational trials and pre-intervention data of intervention trials that investigated the abundance of GM in patients with AD spectrum and HC.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently identified articles, extracted data, and evaluated the risk of bias. The effect sizes were performed by a random-effect, inverse-variance weighted model. The effects of different countries and of clinical stages on GM abundance were also examined.

RESULTS

11 studies consisting of 378 HC and 427 patients with AD spectrum were included in the meta-analysis. Patients with AD, but not MCI, showed significantly reduced GM diversity as compared to HC. We also found more abundance of Proteobacteria, Bifidobacterium and Phascolarctobacterium, but less abundance of Firmicutes, Clostridiaceae, Lachnospiraceae and Rikenellaceae in patients with AD spectrum as compared with HC. The profiles of abundance of Alistipes and Bacteroides in HC and AD spectrum were differentially affected by countries. Finally, when considering clinical stage as a moderator, the comparisons of abundance in Clostridiaceae and Phascolarctobacterium showed large effect sizes, with gradient changes from MCI to AD stage.

LIMITATIONS

The inclusion of studies originating only from China and the U.S. was a possible limitation.

CONCLUSIONS

Patients with AD spectrum demonstrated altered GM abundance, which was differentially mediated by countries and clinical stages.

Phages in the Gut Ecosystem

Phages, short for bacteriophages, are viruses that specifically infect bacteria and are the most abundant biological entities on earth found in every explored environment, from the deep sea to the Sahara Desert. Phages are abundant within the human biome and are gaining increasing recognition as potential modulators of the gut ecosystem. For example, they have been connected to gastrointestinal diseases and the treatment efficacy of Fecal Microbiota Transplant. The ability of phages to modulate the human gut microbiome has been attributed to the predation of bacteria or the promotion of bacterial survival by the transfer of genes that enhance bacterial fitness upon infection. In addition, phages have been shown to interact with the human immune system with variable outcomes. Despite the increasing evidence supporting the importance of phages in the gut ecosystem, the extent of their influence on the shape of the gut ecosystem is yet to be fully understood. Here, we discuss evidence for phage modulation of the gut microbiome, postulating that phages are pivotal contributors to the gut ecosystem dynamics. We therefore propose novel research questions to further elucidate the role(s) that they have within the human ecosystem and its impact on our health and well-being.