A gut-vascular barrier controls the systemic dissemination of bacteria

Berberine decreases S100B generation to regulate gut vascular barrier permeability in mice with burn injury

Context: Berberine (BBR) can regulate enteric glial cells (EGCs) and the gut vascular barrier (GVB).Objective: To explore whether BBR regulates GVB permeability via the S100B pathway.Materials and methods: GVB hyperpermeability in C57BL/6J mice was induced by burns or S100B enema. BBR (25 or 50 mg/kg/d, 3 d) was gavaged preburn. S100B monoclonal antibody (S100BmAb) was i.v. injected postburn. Mouse intestinal microvascular endothelial cells (MIMECs) were treated with S100B, S100B plus BBR, or Z-IETD-FMK. GVB permeability was assayed by FITC-dextran, S100B by ELISA, caspase-8, β-catenin, occludin and PV-1 by immunoblot.Results: Burns elevated S100B in serum and in colonic mucosa to a peak (147.00 ± 4.95 ng/mL and 160.30 ± 8.50 ng/mg, respectively) at 36 h postburn, but BBR decreased burns-induced S100B in serum (126.20 ± 6.30 or 90.60 ± 3.78 ng/mL) and in mucosa (125.80 ± 12.40 or 91.20 ± 8.54 ng/mg). Burns raised GVB permeability (serum FITC-dextran 111.40 ± 8.56 pg/mL) at 48 h postburn, but BBR reduced GVB permeability (serum FITC-dextran 89.20 ± 6.98 or 68.60 ± 5.50 ng/mL). S100B enema (1 μM) aggravated burns-raised GVB permeability (142.80 ± 8.07 pg/mL) and PV-1, but the effect of S100B was antagonized by BBR. Z-IETD-FMK (5 μM) increased S100B-induced permeability to FITC-dextran (205.80 ± 9.70 to 263.80 ± 11.04 AUs) while reducing β-catenin in MIMECs. BBR (5 μM) reduced S100B-induced permeability (104.20 ± 9.65 AUs) and increased caspase-8, β-catenin and occludin.Discussion and conclusion: BBR decreases burns-induced GVB hyperpermeability via modulating S100B/caspase-8/β-catenin pathway and may involve EGCs.

Sympathetic neuropeptide Y protects from obesity by sustaining thermogenic fat

Human mutations in neuropeptide Y (NPY) have been linked to high body mass index but not altered dietary patterns1. Here we uncover the mechanism by which NPY in sympathetic neurons2,3 protects from obesity. Imaging of cleared mouse brown and white adipose tissue (BAT and WAT, respectively) established that NPY+ sympathetic axons are a smaller subset that mostly maps to the perivasculature; analysis of single-cell RNA sequencing datasets identified mural cells as the main NPY-responsive cells in adipose tissues. We show that NPY sustains the proliferation of mural cells, which are a source of thermogenic adipocytes in both BAT and WAT4-6. We found that diet-induced obesity leads to neuropathy of NPY+ axons and concomitant depletion of mural cells. This defect was replicated in mice with NPY abrogated from sympathetic neurons. The loss of NPY in sympathetic neurons whitened interscapular BAT, reducing its thermogenic ability and decreasing energy expenditure before the onset of obesity. It also caused adult-onset obesity of mice fed on a regular chow diet and rendered them more susceptible to diet-induced obesity without increasing food consumption. Our results indicate that, relative to central NPY, peripheral NPY produced by sympathetic nerves has the opposite effect on body weight by sustaining energy expenditure independently of food intake.

Cellular and molecular basis of proximal small intestine disorders

The proximal part of the small intestine, including duodenum and jejunum, is not only dedicated to nutrient digestion and absorption but is also a highly regulated immune site exposed to environmental factors. Host-protective responses against pathogens and tolerance to food antigens are essential functions in the small intestine. The cellular ecology and molecular pathways to maintain those functions are complex. Maladaptation is highlighted by common immune-mediated diseases such as coeliac disease, environmental enteric dysfunction or duodenal Crohn's disease. An expanding spectrum of more than 100 rare monogenic disorders inform on causative molecular mechanisms of nutrient absorption, epithelial homeostasis and barrier function, as well as inflammatory immune responses and immune regulation. Here, after summarizing the architectural and cellular traits that underlie the functions of the proximal intestine, we discuss how the integration of tissue immunopathology and molecular mechanisms can contribute towards our understanding of disease and guide diagnosis. We propose an integrated mechanism-based taxonomy and discuss the latest experimental approaches to gain new mechanistic insight into these disorders with large disease burden worldwide as well as implications for therapeutic interventions.

Gut microbiota metabolite trimethylamine N-oxide promoted NAFLD progression by exacerbating intestinal barrier disruption and intrahepatic cellular imbalance

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide, with the gut microbiota and its metabolites are important regulators of its progression. Trimethylamine N-oxide (TMAO), a metabolite of the gut microbiota, has been closely associated with various metabolic diseases, but its relationship with NAFLD remains to be elucidated. In this study, we found that fecal TMAO levels correlated with NAFLD severity. Moreover, TMAO promoted lipid deposition in HepG2 fatty liver cells and exacerbated hepatic steatosis in NAFLD rats. In the colon, TMAO undermined the structure and function of the intestinal barrier at various levels, further activated the TLR4/MyD88/NF-κB pathway, and inhibited the WNT/β-catenin pathway. In the liver, TMAO induced endothelial dysfunction with capillarization of liver sinusoidal endothelial cells, while modulating macrophage polarization. In conclusion, our study suggests that gut microbiota metabolite TMAO promotes NAFLD progression by impairing the gut and liver and that targeting TMAO could be an alternative therapeutic strategy for NAFLD.

Opening the doors of precision medicine: novel tools to assess intestinal barrier in inflammatory bowel disease and colitis-associated neoplasia

Mounting evidence underscores the pivotal role of the intestinal barrier and its convoluted network with diet and intestinal microbiome in the pathogenesis of inflammatory bowel disease (IBD) and colitis-associated colorectal cancer (CRC). Moreover, the bidirectional association of the intestinal barrier with the liver and brain, known as the gut-brain axis, plays a crucial role in developing complications, including extraintestinal manifestations of IBD and CRC metastasis. Consequently, barrier healing represents a crucial therapeutic target in these inflammatory-dependent disorders, with barrier assessment predicting disease outcomes, response to therapy and extraintestinal manifestations.New advanced technologies are revolutionising our understanding of the barrier paradigm, enabling the accurate assessment of the intestinal barrier and aiding in unravelling the complexity of the gut-brain axis. Cutting-edge endoscopic imaging techniques, such as ultra-high magnification endocytoscopy and probe-based confocal laser endomicroscopy, are new technologies allowing real-time exploration of the 'cellular' intestinal barrier. Additionally, novel advanced spatial imaging technology platforms, including multispectral imaging, upconversion nanoparticles, digital spatial profiling, optical spectroscopy and mass cytometry, enable a deep and comprehensive assessment of the 'molecular' and 'ultrastructural' barrier. In this promising landscape, artificial intelligence plays a pivotal role in standardising and integrating these novel tools, thereby contributing to barrier assessment and prediction of outcomes.Looking ahead, this integrated and comprehensive approach holds the promise of uncovering new therapeutic targets, breaking the therapeutic ceiling in IBD. Novel molecules, dietary interventions and microbiome modulation strategies aim to restore, reinforce, or modulate the gut-brain axis. These advancements have the potential for transformative and personalised approaches to managing IBD.

Neuroimmune and neuroinflammation response for traumatic brain injury

Traumatic brain injury (TBI) is one of the major diseases leading to mortality and disability, causing a serious disease burden on individuals' ordinary lives as well as socioeconomics. In primary injury, neuroimmune and neuroinflammation are both responsible for the TBI. Besides, extensive and sustained injury induced by neuroimmune and neuroinflammation also prolongs the course and worsens prognosis of TBI. Therefore, this review aims to explore the role of neuroimmune, neuroinflammation and factors associated them in TBI as well as the therapies for TBI. Thus, we conducted by searching PubMed, Scopus, and Web of Science databases for articles published between 2010 and 2023. Keywords included "traumatic brain injury," "neuroimmune response," "neuroinflammation," "astrocytes," "microglia," and "NLRP3." Articles were selected based on relevance and quality of evidence. On this basis, we provide the cellular and molecular mechanisms of TBI-induced both neuroimmune and neuroinflammation response, as well as the different factors affecting them, are introduced based on physiology of TBI, which supply a clear overview in TBI-induced chain-reacting, for a better understanding of TBI and to offer more thoughts on the future therapies for TBI.

Perivascular B cells link intestinal angiogenesis to immunity and to the gut-brain axis during neuroinflammation

Disruption of gut barrier function and intestinal immune cell homeostasis are increasingly considered critical players in pathogenesis of extra-intestinal inflammatory diseases, including multiple sclerosis (MS) and its prototypical animal model, the experimental autoimmune encephalomyelitis (EAE). Breakdown of epithelial barriers increases intestinal permeability and systemic dissemination of microbiota-derived molecules. However, whether the gut-vascular barrier (GVB) is altered during EAE has not been reported. Here, we demonstrate that endothelial cell proliferation and vessel permeability increase before EAE clinical onset, leading to vascular remodeling and expansion of intestinal villi capillary bed during disease symptomatic phase in an antigen-independent manner. Concomitant to onset of angiogenesis observed prior to neurological symptoms, we identify an increase of intestinal perivascular immune cells characterized by the surface marker lymphatic vessel endothelial hyaluronic acid receptor 1 (LYVE-1). LYVE-1+ is expressed more frequently on B cells that show high levels of CD73 and have proangiogenic properties. B cell depletion was sufficient to mitigate enteric blood endothelial cell proliferation following immunization for EAE. In conclusion, we propose that altered intestinal vasculature driven by a specialized LYVE-1+ B cell subset promotes angiogenesis and that loss of GVB function is implicated in EAE development and autoimmunity.

Dihydroartemisinin Modulates Enteric Glial Cell Heterogeneity to Alleviate Colitis

The precise mechanism underlying the therapeutic effects of dihydroartemisinin (DHA) in alleviating colitis remains incompletely understood. A strong correlation existed between the elevation of glial fibrillary acidic protein (GFAP)+/S100 calcium binding protein B (S100β)+ enteric glial cells (EGCs) in inflamed colonic tissues and the disruption of the intestinal epithelial barrier (IEB) and gut vascular barrier (GVB) observed in chronic colitis. DHA demonstrated efficacy in restoring the functionality of the dual gut barrier while concurrently attenuating intestinal inflammation. Mechanistically, DHA inhibited the transformation of GFAP+ EGCs into GFAP+/S100β+ EGCs while promoting the differentiation of GFAP+/S100β+ EGCs back into GFAP+ EGCs. Furthermore, DHA induced apoptosis in GFAP+/S100β+ EGCs by inducing cell cycle arrest at the G0/G1 phase. The initial mechanism is further validated that DHA regulates EGC heterogeneity by improving dysbiosis in colitis. These findings underscore the multifaceted therapeutic potential of DHA in ameliorating colitis by improving dysbiosis, modulating EGC heterogeneity, and preserving gut barrier integrity, thus offering promising avenues for novel therapeutic strategies for inflammatory bowel diseases.

Microbiota alterations associated with vascular diseases: postbiotics as a next-generation magic bullet for gut-vascular axis

The intestinal microbiota represents a key element in maintaining the homeostasis and health conditions of the host. Vascular pathologies and other risk factors such as aging have been recently associated with dysbiosis. The qualitative and quantitative alteration of the intestinal microbiota hinders correct metabolic homeostasis, causing structural and functional changes of the intestinal wall itself. Impairment of the intestinal microbiota, combined with the reduction of the barrier function, worsen the pathological scenarios of peripheral tissues over time, including the vascular one. Several experimental evidence, collected in this review, describes in detail the changes of the intestinal microbiota in dysbiosis associated with vascular alterations, such as atherosclerosis, hypertension, and endothelial dysfunction, the resulting metabolic disorders and how these can impact on vascular health. In this context, the gut-vascular axis is considered, for the first time, as a merged unit involved in the development and progression of vascular pathologies and as a promising target. Current approaches for the management of dysbiosis such as probiotics, prebiotics and dietary modifications act mainly on the intestinal district. Postbiotics, described as preparation of inanimate microorganisms and/or their components that confers health benefits on the host, represent an innovative strategy for a dual management of intestinal dysbiosis and vascular pathologies. In this context, this review has the further purpose of defining the positive effects of the supplementation of bacterial strains metabolites (short‑chain fatty acids, exopolysaccharides, lipoteichoic acids, gallic acid, and protocatechuic acid) restoring intestinal homeostasis and acting directly on the vascular district through the gut-vascular axis.

The gut microbiota and diabetes: research, translation, and clinical applications - 2023 Diabetes, Diabetes Care, and Diabetologia Expert Forum

This article summarises the state of the science on the role of the gut microbiota (GM) in diabetes from a recent international expert forum organised by Diabetes, Diabetes Care, and Diabetologia, which was held at the European Association for the Study of Diabetes 2023 Annual Meeting in Hamburg, Germany. Forum participants included clinicians and basic scientists who are leading investigators in the field of the intestinal microbiome and metabolism. Their conclusions were as follows: (1) the GM may be involved in the pathophysiology of type 2 diabetes, as microbially produced metabolites associate both positively and negatively with the disease, and mechanistic links of GM functions (e.g. genes for butyrate production) with glucose metabolism have recently emerged through the use of Mendelian randomisation in humans; (2) the highly individualised nature of the GM poses a major research obstacle, and large cohorts and a deep-sequencing metagenomic approach are required for robust assessments of associations and causation; (3) because single time point sampling misses intraindividual GM dynamics, future studies with repeated measures within individuals are needed; and (4) much future research will be required to determine the applicability of this expanding knowledge to diabetes diagnosis and treatment, and novel technologies and improved computational tools will be important to achieve this goal.

Intestinal organ chips for disease modelling and personalized medicine

Alterations in intestinal structure, mechanics and physiology underlie acute and chronic intestinal conditions, many of which are influenced by dysregulation of microbiome, peristalsis, stroma or immune responses. Studying human intestinal physiology or pathophysiology is difficult in preclinical animal models because their microbiomes and immune systems differ from those of humans. Although advances in organoid culture partially overcome this challenge, intestinal organoids still lack crucial features that are necessary to study functions central to intestinal health and disease, such as digestion or fluid flow, as well as contributions from long-term effects of living microbiome, peristalsis and immune cells. Here, we review developments in organ-on-a-chip (organ chip) microfluidic culture models of the human intestine that are lined by epithelial cells and interfaced with other tissues (such as stroma or endothelium), which can experience both fluid flow and peristalsis-like motions. Organ chips offer powerful ways to model intestinal physiology and disease states for various human populations and individual patients, and can be used to gain new insight into underlying molecular and biophysical mechanisms of disease. They can also be used as preclinical tools to discover new drugs and then validate their therapeutic efficacy and safety in the same human-relevant model.

Non-human peptides revealed in blood reflect the composition of intestinal microbiota

BACKGROUND

The previously underestimated effects of commensal gut microbiota on the human body are increasingly being investigated using omics. The discovery of active molecules of interaction between the microbiota and the host may be an important step towards elucidating the mechanisms of symbiosis.

RESULTS

Here, we show that in the bloodstream of healthy people, there are over 900 peptides that are fragments of proteins from microorganisms which naturally inhabit human biotopes, including the intestinal microbiota. Absolute quantitation by multiple reaction monitoring has confirmed the presence of bacterial peptides in the blood plasma and serum in the range of approximately 0.1 nM to 1 μM. The abundance of microbiota peptides reaches its maximum about 5 h after a meal. Most of the peptides correlate with the bacterial composition of the small intestine and are likely obtained by hydrolysis of membrane proteins with trypsin, chymotrypsin and pepsin - the main proteases of the gastrointestinal tract. The peptides have physicochemical properties that likely allow them to selectively pass the intestinal mucosal barrier and resist fibrinolysis.

CONCLUSIONS

The proposed approach to the identification of microbiota peptides in the blood, after additional validation, may be useful for determining the microbiota composition of hard-to-reach intestinal areas and monitoring the permeability of the intestinal mucosal barrier.

Fenestrated Endothelial Cells across Organs: Insights into Kidney Function and Disease

In the human body, the vascular system plays an indispensable role in maintaining homeostasis by supplying oxygen and nutrients to cells and organs and facilitating the removal of metabolic waste and toxins. Blood vessels-the key constituents of the vascular system-are composed of a layer of endothelial cells on their luminal surface. In most organs, tightly packed endothelial cells serve as a barrier separating blood and lymph from surrounding tissues. Intriguingly, endothelial cells in some tissues and organs (e.g., choroid plexus, liver sinusoids, small intestines, and kidney glomerulus) form transcellular pores called fenestrations that facilitate molecular and ionic transport across the vasculature and mediate immune responses through leukocyte transmigration. However, the development and unique functions of endothelial cell fenestrations across organs are yet to be fully uncovered. This review article provides an overview of fenestrated endothelial cells in multiple organs. We describe their development and organ-specific roles, with expanded discussions on their contributions to glomerular health and disease. We extend these discussions to highlight the dynamic changes in endothelial cell fenestrations in diabetic nephropathy, focal segmental glomerulosclerosis, Alport syndrome, and preeclampsia, and how these unique cellular features could be targeted for therapeutic development. Finally, we discuss emerging technologies for in vitro modeling of biological systems, and their relevance for advancing the current understanding of endothelial cell fenestrations in health and disease.

Bacteriocins sourced from traditional fermented foods for ensuring food safety: the microbial guards

Concerns about food safety have consistently driven the exploration of potent antimicrobials with probiotic origins. Identification of probiotic-derived bacteriocins as robust alternatives to antibiotics has gained traction following the COVID-19 pandemic. Additionally, the global market is witnessing an increasing preference for minimally processed food products free from chemical additives. Another contributing factor to the search for potent antimicrobials is the escalating number of infections caused by antibiotic-resistant bacteria and the need to mitigate the significant damage inflicted on the commensal human microbiota by broad-spectrum antibiotics. As an alternative bio-preservation strategy, there is substantial enthusiasm for the use of bacteriocins or starter cultures producing bacteriocins in preserving a variety of food items. This review specifically focuses on bacteriocins originating from lactic acid bacteria associated with fermented foods and explores their technological applications as nanobiotics. The food-grade antibiotic alternatives, whether utilized independently or in combination with other antimicrobials and administered directly or encapsulated, are anticipated to possess qualities of safety, stability and non-toxicity suitable for application in the food sector. © 2024 Society of Chemical Industry.

Inflammation, oxidative stress and gut microbiome perturbation: A narrative review of mechanisms and treatment of the alcohol hangover

Alcohol is the most widely abused substance in the world, the leading source of mortality in 15-49-year-olds, and a major risk factor for heart disease, liver disease, diabetes, and cancer. Despite this, alcohol is regularly misused in wider society. Consumers of excess alcohol often note a constellation of negative symptoms, known as the alcohol hangover. However, the alcohol hangover is not considered to have long-term clinical significance by clinicians or consumers. We undertook a critical review of the literature to demonstrate the pathophysiological mechanisms of the alcohol hangover. Hereafter, the alcohol hangover is re-defined as a manifestation of sickness behavior secondary to alcohol-induced inflammation, using the Bradford-Hill criteria to demonstrate causation above correlation. Alcohol causes inflammation through oxidative stress and endotoxemia. Alcohol metabolism is oxidative and increased intake causes relative tissue hypoxia and increased free radical generation. Tissue damage ensues through lipid peroxidation and the formation of DNA/protein adducts. Byproducts of alcohol metabolism such as acetaldehyde and congeners, sleep deprivation, and the activation of nonspecific inducible CYP2E1 in alcohol-exposed tissues exacerbate free radical generation. Tissue damage and cell death lead to inflammation, but in the intestine loss of epithelial cells leads to intestinal permeability, allowing the translocation of pathogenic bacteria to the systemic circulation (endotoxemia). This leads to a well-characterized cascade of systemic inflammation, additionally activating toll-like receptor 4 to induce sickness behavior. Considering the evidence, it is suggested that hangover frequency and severity may be predictors of the development of later alcohol-related diseases, meriting formal confirmation in prospective studies. In light of the mechanisms of alcohol-mediated inflammation, research into gut permeability and the gut microbiome may be an exciting future therapeutic avenue to prevent alcohol hangover and other alcohol-related diseases.

Impacts of PFOS, PFOA and their alternatives on the gut, intestinal barriers and gut-organ axis

With the restricted use of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), a number of alternatives to PFOS and PFOA have attracted great interest. Most of the alternatives are still characterized by persistence, bioaccumulation, and a variety of toxicity. Due to the production and use of these substances, they can be detected in the atmosphere, soil and water body. They affect human health through several exposure pathways and especially enter the gut by drinking water and eating food, which results in gut toxicity. In this review, we summarized the effects of PFOS, PFOA and 9 alternatives on pathological changes in the gut, the disruption of physical, chemical, biological and immune barriers of the intestine, and the gut-organ axis. This review provides a valuable understanding of the gut toxicity of PFOS, PFOA and their alternatives as well as the human health risks of emerging contaminants.

Distal Immunization and Systemic Cytokines Establish a Transient Immune Alert State in the Intestine

Conventionally, immune responses are studied in the context of inflamed tissues and their corresponding draining lymph nodes (LNs). However, little is known about the effects of systemic inflammatory signals generated during local inflammation on distal tissues and nondraining LNs. Using a mouse model of cutaneous immunization, we found that systemic inflammatory stimuli triggered a rapid and selective distal response in the small intestine and the mesenteric LN (mesLN). This consisted of increased permeability of intestinal blood vessels and lymphatic drainage of bloodborne solutes into the mesLN, enhanced activation and migration of intestinal dendritic cells, as well as amplified T cell responses in the mesLNs to systemic but not orally derived Ags. Mechanistically, we found that the small intestine endothelial cells preferentially expressed molecules involved in TNF-α signaling and that TNF-α blockade markedly diminished distal intestinal responses to cutaneous immunization. Together, these findings reveal that the intestinal immune system is rapidly and selectively activated in response to inflammatory cues regardless of their origin, thus identifying an additional layer of defense and enhanced surveillance of a key barrier organ at constant risk of pathogen encounter.

Haematococcus pluvialis polysaccharides improve microbiota-driven gut epithelial and vascular barrier and prevent alcoholic steatohepatitis development

Algal polysaccharides possess many biological activities and health benefits, such as antioxidant, anti-tumor, anti-coagulant, and immunomodulatory potential. Gut microbiota has emerged as one of the major contributor in mediating the health benefits of algal polysaccharides. In this study we showed that Haematococcus pluvialis polysaccharides (HPP) decreased serum transaminase levels and hepatic triglyceride content, alleviated inflammation and oxidative stress in the liver of chronic and binge ethanol diet-fed mice. Furthermore, HPP reduced endotoxemia, improved gut microbiota dysbiosis, inhibited epithelial barrier disruption and gut vascular barrier (GVB) damage in ethanol diet-fed mice. Co-housing vehicle-fed mice with HPP-fed mice alleviated ethanol-induced liver damage and endotoxemia. Moreover, fecal microbiota transplantation from HPP-fed mice into antibiotic-induced microbiota-depleted recipients also alleviated ethanol-induced liver injury and improved gut epithelial and vascular barrier. Our study demonstrated that HPP ameliorated ethanol-induced gut epithelial and vascular barrier dysfunction through alteration of gut microbiota, therefore preventing alcoholic liver damage.

Quantitative PET imaging and modeling of molecular blood-brain barrier permeability

Blood-brain barrier (BBB) disruption is involved in the pathogenesis and progression of many neurological and systemic diseases. Non-invasive assessment of BBB permeability in humans has mainly been performed with dynamic contrast-enhanced magnetic resonance imaging, evaluating the BBB as a structural barrier. Here, we developed a novel non-invasive positron emission tomography (PET) method in humans to measure the BBB permeability of molecular radiotracers that cross the BBB through different transport mechanisms. Our method uses high-temporal resolution dynamic imaging and kinetic modeling to jointly estimate cerebral blood flow and tracer-specific BBB transport rate from a single dynamic PET scan and measure the molecular permeability-surface area (PS) product of the radiotracer. We show our method can resolve BBB PS across three PET radiotracers with greatly differing permeabilities, measure reductions in BBB PS of 18F-fluorodeoxyglucose (FDG) in healthy aging, and demonstrate a possible brain-body association between decreased FDG BBB PS in patients with metabolic dysfunction-associated steatotic liver inflammation. Our method opens new directions to efficiently study the molecular permeability of the human BBB in vivo using the large catalogue of available molecular PET tracers.

Role of blood metabolites in mediating the effect of gut microbiome on the mutated-RAS/BRAF metastatic colorectal cancer-specific survival

BACKGROUND

Recent studies have linked alterations in the gut microbiome and metabolic disruptions to the invasive behavior and metastasis of colorectal cancer (CRC), thus affecting patient prognosis. However, the specific relationship among gut microbiome, metabolite profiles, and mutated-RAS/BRAF metastatic colorectal cancer (M-mCRC) remains unclear. Furthermore, the potential mechanisms and prognostic implications of metabolic changes induced by gut microbiome alterations in patients with M-mCRC still need to be better understood.

METHODS

We conducted Mendelian randomization (MR) to evaluate the causal relationship of genetically predicted 196 gut microbiome features and 1400 plasma metabolites/metabolite ratios on M-mCRC-specific survival. Additionally, we identified significant gut microbiome-metabolites/metabolite ratio associations based on M-mCRC. Metabolite information was annotated, and functional annotation and pathway enrichment analyses were performed on shared proteins corresponding to significant metabolite ratios, aiming to reveal potential mechanisms by which gut microbiome influences M-mCRC prognosis via modulation of human metabolism.

RESULTS

We identified 11 gut microbiome features and 49 known metabolites/metabolite ratios correlated with M-mCRC-specific survival. Furthermore, we identified 17 gut microbiome-metabolite/metabolite ratio associations specific to M-mCRC, involving eight lipid metabolites and three bilirubin degradation products. The shared proteins corresponding to significant metabolite ratios were predominantly localized within the integral component of the membrane and exhibited enzymatic activities such as glucuronosyltransferase and UDP-glucuronosyltransferase, crucial in processes such as glucuronidation, bile secretion, and lipid metabolism. Moreover, these proteins were significantly enriched in pathways related to ascorbate and aldarate metabolism, pentose and glucuronate interconversions, steroid hormone biosynthesis, and bile secretion.

CONCLUSION

Our study offers novel insights into the potential mechanisms underlying the impact of the gut microbiome on the prognosis of M-mCRC. These findings serve as a meaningful reference for exploring potential therapeutic targets and strategies in the future.

Intestinal barrier permeability: the influence of gut microbiota, nutrition, and exercise

The intestinal wall is a selectively permeable barrier between the content of the intestinal lumen and the internal environment of the body. Disturbances of intestinal wall permeability can potentially lead to unwanted activation of the enteric immune system due to excessive contact with gut microbiota and its components, and the development of endotoxemia, when the level of bacterial lipopolysaccharides increases in the blood, causing chronic low-intensity inflammation. In this review, the following aspects are covered: the structure of the intestinal wall barrier; the influence of the gut microbiota on the permeability of the intestinal wall via the regulation of functioning of tight junction proteins, synthesis/degradation of mucus and antioxidant effects; the molecular mechanisms of activation of the pro-inflammatory response caused by bacterial invasion through the TLR4-induced TIRAP/MyD88 and TRAM/TRIF signaling cascades; the influence of nutrition on intestinal permeability, and the influence of exercise with an emphasis on exercise-induced heat stress and hypoxia. Overall, this review provides some insight into how to prevent excessive intestinal barrier permeability and the associated inflammatory processes involved in many if not most pathologies. Some diets and physical exercise are supposed to be non-pharmacological approaches to maintain the integrity of intestinal barrier function and provide its efficient operation. However, at an early age, the increased intestinal permeability has a hormetic effect and contributes to the development of the immune system.

Inflammatory Gene Panel Guiding the Study of Genetics in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a complex disease that develops through a sequence of molecular events that are still poorly defined. This process is driven by a multitude of context-dependent genes that play different roles based on their environment. The complexity and multi-faceted nature of these genes make it difficult to study the genetic basis of IBD. The goal of this article is to review the key genes in the pathophysiology of IBD and highlight new technology that can be used in further research. This paper examines Nanostring RNA probe technology, which uses tissue analyzed without the use of enzymes, transcription, or amplification. Nanostring offers several panels of genes to test, including an inflammation panel of 234 genes. This article analyzes this panel and reviews the literature for each gene's effect in IBD for use as a framework to review the pathophysiology of the disease. The panel was narrowed to 26 genes with significant evidence of mechanistic potential in IBD, which were then categorized into specific areas of pathogenesis. These include gut barrier breakdown, inappropriate recognition of commensal bacteria, immune cell activation, proinflammatory cytokine release, and subsequent impairment of the anti-inflammatory response. The eventual goal of this paper is the creation of a customized panel of IBD genes that can be used to better understand the genetic mechanism of IBD and aid in the development of future therapies in IBD.

The relevance of intestinal barrier dysfunction, antimicrobial proteins and bacterial endotoxin in metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a leading cause of end-stage liver disease associated with increased mortality and cardiovascular disease. Obesity and diabetes are the most important risk factors of MASLD. It is well-established that obesity-associated insulin resistance leads to a situation of tissue lipotoxicity characterized by an accumulation of excess fat in non-fat tissues such as the liver, promoting the development of MASLD, and its progression into metabolic dysfunction-associated steatohepatitis.

METHODS

Here, we aimed to review the impact of disrupted intestinal permeability, antimicrobial proteins and bacterial endotoxin in the development and progression of MASLD.

RESULTS AND CONCLUSION

Recent studies demonstrated that obesity- and obesogenic diets-associated alterations of intestinal microbiota along with the disruption of intestinal barrier integrity, the alteration in antimicrobial proteins and, in consequence, an enhanced translocation of bacterial endotoxin into bloodstream might contribute to this pathological process through to impacting liver metabolism and inflammation.

Epidemiological and Molecular Characteristics of Hypermucoviscous and Hypervirulent Klebsiella pneumoniae Isolates in Community Patients in Shanghai, China

Background

The occurrence and dissemination of hypermucoviscous and hypervirulent Klebsiella pneumoniae (hm-hvKp) isolates in clinical settings are a critical public health problem in the world. However, the data on these isolates in community populations are limited. This study aims to understand the prevalence and molecular characteristics of hm-hvKp isolates in community patients in Shanghai, China.

Methods

In 2018, an active surveillance system focused on hm-hvKp in community diarrhoeal cases was implemented in Pudong New Area, Shanghai, China, involving 12 sentinel hospitals. The antimicrobial susceptibility of hm-hvKp isolates from fecal samples was tested, and whole-genome sequencing (WGS) was performed to predict the serotypes and sequence types and to identify antimicrobial resistance determinants, virulence determinants, and phylogenetic clusters.

Results

The overall prevalence of hm K. pneumoniae isolates was 2.48% (31/1252), with the proportions of 1.76% (22/1252) for hm-hvKp and 0.72% (9/1252) for hm not hv K. pneumoniae. The prevalence of hm-hvKp isolates among different age groups and different months was statistically significant. All the 22 hm-hvKp isolates were susceptible to 20 antimicrobial agents and only carried bla SHV gene, and KL1 and KL2 accounted for eight (36.36%) cases and seven (31.82%) cases, respectively. The eight ST23/KL1 isolates belonged to the predominant CG23-I clade, which typically possessed the virulence determinants profile of rmpA/rmpA2-iro-iuc-ybt-irp-clb. The five ST86/KL2 isolates were assigned to the global clusters ST86/KL2-1 (n=2), ST86/KL2-2 (n=2), ST86/KL2-3 (n=1), all lack of the clb gene. Shanghai ST23/KL1 and ST86/KL2 isolates were closely related to the global isolates from liver abscesses, blood, and urine.

Conclusion

Hm-hvKp is carried by the community population of Shanghai, with ST23/KL1 and ST86/KL2 isolates predominant. Hm-hvKp isolates of different continents, different sources, and different virulence levels were closely related. Ongoing surveillance of hm-hvKp isolates in the community population is warranted.

Role of the afferent lymph as an immunological conduit to analyze tissue antigenic and inflammatory load

The lymphatic fluid is the conduit by which part of the tissue "omics" is transported to the draining lymph node for immunosurveillance. Following cannulation of the pre-nodal cervical and mesenteric afferent lymphatics, herein we investigate the lymph proteomic composition, uncovering that its composition varies according to the tissue of origin. Tissue specificity is also reflected in the dendritic cell-major histocompatibility complex class II-eluted immunopeptidome harvested from the cervical and mesenteric nodes. Following inflammatory disruption of the gut barrier, the lymph antigenic and inflammatory loads are analyzed in both mice and subjects with inflammatory bowel diseases. Gastrointestinal tissue damage reflects the lymph inflammatory and damage-associated molecular pattern signatures, microbiome-derived by-products, and immunomodulatory molecules, including metabolites of the gut-brain axis, mapped in the afferent mesenteric lymph. Our data point to the relevance of the lymphatic fluid to probe the tissue-specific antigenic and inflammatory load transported to the draining lymph node for immunosurveillance.

Genetic evidence for a causal link between gut microbiota and arterial embolism and thrombosis: a two-sample Mendelian randomization study

Background

Previous research has hinted at a crucial link between gut microbiota and arterial embolism and thrombosis, yet the causal relationship remains enigmatic. To gain a deeper understanding, we aimed to comprehensively explore the causal relationship and elucidate the impact of the gut microbiota on the risk through a two-sample Mendelian randomization (MR) study.

Methods

Genetic instrumental variables for gut microbiota were identified from a genome-wide association study (GWAS) of 18,340 participants. Summary statistics for IBS were drawn from a GWAS including 1,076 cases and 381,997 controls. We used the inverse-variance weighted (IVW) method as the primary analysis. To test the robustness of our results, we further performed the weighted median method, MR-Egger regression, and MR pleiotropy residual sum and outlier test.

Results

We identified three bacterial traits that were associated with the risk of arterial embolism and thrombosis: odds ratio (OR): 1.58, 95% confidence interval (CI): 1.08-2.31, p = 0.017 for genus Catenibacterium; OR: 0.64, 95% CI: 0.42-0.96, p = 0.031 for genus Dialister; and OR: 2.08, 95% CI: 1.25-3.47, p = 0.005 for genus Odoribacter. The results of sensitivity analyses for these bacterial traits were consistent (P<0.05).

Conclusion

Our systematic analyses provided evidence to support a potential causal relationship between several gut microbiota taxa and the risk of arterial embolism and thrombosis. More studies are required to show how the gut microbiota affects the development of arterial embolism and thrombosis.

Multifocal fluorescence video-rate imaging of centimetre-wide arbitrarily shaped brain surfaces at micrometric resolution

Fluorescence microscopy allows for the high-throughput imaging of cellular activity across brain areas in mammals. However, capturing rapid cellular dynamics across the curved cortical surface is challenging, owing to trade-offs in image resolution, speed, field of view and depth of field. Here we report a technique for wide-field fluorescence imaging that leverages selective illumination and the integration of focal areas at different depths via a spinning disc with varying thickness to enable video-rate imaging of previously reconstructed centimetre-scale arbitrarily shaped surfaces at micrometre-scale resolution and at a depth of field of millimetres. By implementing the technique in a microscope capable of acquiring images at 1.68 billion pixels per second and resolving 16.8 billion voxels per second, we recorded neural activities and the trajectories of neutrophils in real time on curved cortical surfaces in live mice. The technique can be integrated into many microscopes and macroscopes, in both reflective and fluorescence modes, for the study of multiscale cellular interactions on arbitrarily shaped surfaces.

Prebiotics, probiotics, synbiotics and postbiotics to adolescents in metabolic syndrome

The prevalence of childhood and adolescent obesity has globally reached alarming dimensions and many adolescents affected by obesity already present one or more obesity-related comorbidities. In recent years, emerging evidence supporting the role of gut microbiota in the pathophysiology of metabolic diseases has been reported and the use of prebiotics, probiotics, synbiotics and postbiotics as a strategy to manipulate gut microbiota has become popular. The aim of this review is to explore the relationship between gut microbiota and metabolic syndrome in adolescents and to discuss the potential use of prebiotics, probiotics, synbiotics and postbiotics for the prevention and treatment of this clinical picture in adolescence. According to the most recent literature, prebiotics, probiotics and synbiotics have no clear effect on MetS, but a possible modulation of anthropometric parameters has been observed after synbiotic supplementation. Only one study has examined the role of postbiotics in alleviating metabolic complications in children with obesity but not in adolescents. More extensive research is needed to support the conclusions drawn so far and to develop effective microbiome-based interventions that may help improving the quality of life of children and adolescents exposed to the increasing prevalence of MetS.

Gut-liver axis: Potential mechanisms of action of food-derived extracellular vesicles

Food-derived extracellular vesicles (FEVs) are nanoscale membrane vesicles obtained from dietary materials such as breast milk, plants and probiotics. Distinct from other EVs, FEVs can survive the harsh degrading conditions in the gastrointestinal tract and reach the intestines. This unique feature allows FEVs to be promising prebiotics in health and oral nanomedicine for gut disorders, such as inflammatory bowel disease. Interestingly, therapeutic effects of FEVs have recently also been observed in non-gastrointestinal diseases. However, the mechanisms remain unclear or even mysterious. It is speculated that orally administered FEVs could enter the bloodstream, reach remote organs, and thus exert therapeutic effects therein. However, emerging evidence suggests that the amount of FEVs reaching organs beyond the gastrointestinal tract is marginal and may be insufficient to account for the significant therapeutic effects achieved regarding diseases involving remote organs such as the liver. Thus, we herein propose that FEVs primarily act locally in the intestine by modulating intestinal microenvironments such as barrier integrity and microbiota, thereby eliciting therapeutic impact remotely on the liver in non-gastrointestinal diseases via the gut-liver axis. Likewise, drugs delivered to the gastrointestinal system through FEVs may act via the gut-liver axis. As the liver is the main metabolic hub, the intestinal microenvironment may be implicated in other metabolic diseases. In fact, many patients with non-alcoholic fatty liver disease, obesity, diabetes and cardiovascular disease suffer from a leaky gut and dysbiosis. In this review, we provide an overview of the recent progress in FEVs and discuss their biomedical applications as therapeutic agents and drug delivery systems, highlighting the pivotal role of the gut-liver axis in the mechanisms of action of FEVs for the treatment of gut disorders and metabolic diseases.

Hepatic interoception in health and disease

The liver is a large organ with crucial functions in metabolism and immune defense, as well as blood homeostasis and detoxification, and it is clearly in bidirectional communication with the brain and rest of the body via both neural and humoral pathways. A host of neural sensory mechanisms have been proposed, but in contrast to the gut-brain axis, details for both the exact site and molecular signaling steps of their peripheral transduction mechanisms are generally lacking. Similarly, knowledge about function-specific sensory and motor components of both vagal and spinal access pathways to the hepatic parenchyma is missing. Lack of progress largely owes to controversies regarding selectivity of vagal access pathways and extent of hepatocyte innervation. In contrast, there is considerable evidence for glucose sensors in the wall of the hepatic portal vein and their importance for glucose handling by the liver and the brain and the systemic response to hypoglycemia. As liver diseases are on the rise globally, and there are intriguing associations between liver diseases and mental illnesses, it will be important to further dissect and identify both neural and humoral pathways that mediate hepatocyte-specific signals to relevant brain areas. The question of whether and how sensations from the liver contribute to interoceptive self-awareness has not yet been explored.

An overview on the cellular mechanisms of anthocyanins in maintaining intestinal integrity and function

Structural and functional changes of the intestinal barrier, as a consequence of a number of (epi)genetic and environmental causes, have a main role in penetrations of pathogens and toxic agents, and lead to the development of inflammation-related pathological conditions, not only at the level of the GI tract but also in other extra-digestive tissues and organs. Anthocyanins (ACNs), a subclass of polyphenols belonging to the flavonoid group, are well known for their health-promoting properties and are widely distributed in the human diet. There is large evidence about the correlation between the human intake of ACN-rich products and a reduction of intestinal inflammation and dysfunction. Our review describes the more recent advances in the knowledge of cellular and molecular mechanisms through which ACNs can modulate the main mechanisms involved in intestinal dysfunction and inflammation, in particular the inhibition of the NF-κB, JNK, MAPK, STAT3, and TLR4 proinflammatory pathways, the upregulation of the Nrf2 transcription factor and the expression of tight junction proteins and mucins.

Insights into the Mechanisms of Action of Akkermansia muciniphila in the Treatment of Non-Communicable Diseases

This comprehensive review delineates the extensive roles of Akkermansia muciniphila in various health domains, spanning from metabolic and inflammatory diseases to neurodegenerative disorders. A. muciniphila, known for its ability to reside in the mucous layer of the intestine, plays a pivotal role in maintaining gut integrity and interacting with host metabolic processes. Its influence extends to modulating immune responses and potentially easing symptoms across several non-communicable diseases, including obesity, diabetes, inflammatory bowel disease, and cancer. Recent studies highlight its capacity to interact with the gut-brain axis, suggesting a possible impact on neuropsychiatric conditions. Despite the promising therapeutic potential of A. muciniphila highlighted in animal and preliminary human studies, challenges remain in its practical application due to stability and cultivation issues. However, the development of pasteurized forms and synthetic mediums offers new avenues for its use in clinical settings, as recognized by regulatory bodies like the European Food Safety Authority. This narrative review serves as a crucial resource for understanding the broad implications of A. muciniphila across different health conditions and its potential integration into therapeutic strategies.

Parvimonas micra can translocate from the subgingival sulcus of the human oral cavity to colorectal adenocarcinoma

Oral and intestinal samples from a cohort of 93 colorectal cancer (CRC) patients and 30 healthy controls (non-CRC) were collected for microbiome analysis. Saliva (28 non-CRC and 94 CRC), feces (30 non-CRC and 97 CRC), subgingival fluid (20 CRC), and tumor tissue samples (20 CRC) were used for 16S metabarcoding and/or RNA sequencing (RNAseq) approaches. A differential analysis of the abundance, performed with the ANCOM-BC package, adjusting the P-values by the Holm-Bonferroni method, revealed that Parvimonas was significantly over-represented in feces from CRC patients (P-value < 0.001) compared to healthy controls. A total of 11 Parvimonas micra isolates were obtained from the oral cavity and adenocarcinoma of CRC patients. Genome analysis identified a pair of isolates from the same patient that shared 99.2% identity, demonstrating that P. micra can translocate from the subgingival cavity to the gut. The data suggest that P. micra could migrate in a synergistic consortium with other periodontal bacteria. Metatranscriptomics confirmed that oral bacteria were more active in tumor than in non-neoplastic tissues. We suggest that P. micra could be considered as a CRC biomarker detected in non-invasive samples such as feces.

Periportal macrophages protect against commensal-driven liver inflammation

The liver is the main gateway from the gut, and the unidirectional sinusoidal flow from portal to central veins constitutes heterogenous zones, including the periportal vein (PV) and the pericentral vein zones1-5. However, functional differences in the immune system in each zone remain poorly understood. Here intravital imaging revealed that inflammatory responses are suppressed in PV zones. Zone-specific single-cell transcriptomics detected a subset of immunosuppressive macrophages enriched in PV zones that express high levels of interleukin-10 and Marco, a scavenger receptor that sequesters pro-inflammatory pathogen-associated molecular patterns and damage-associated molecular patterns, and consequently suppress immune responses. Induction of Marco+ immunosuppressive macrophages depended on gut microbiota. In particular, a specific bacterial family, Odoribacteraceae, was identified to induce this macrophage subset through its postbiotic isoallolithocholic acid. Intestinal barrier leakage resulted in inflammation in PV zones, which was markedly augmented in Marco-deficient conditions. Chronic liver inflammatory diseases such as primary sclerosing cholangitis (PSC) and non-alcoholic steatohepatitis (NASH) showed decreased numbers of Marco+ macrophages. Functional ablation of Marco+ macrophages led to PSC-like inflammatory phenotypes related to colitis and exacerbated steatosis in NASH in animal experimental models. Collectively, commensal bacteria induce Marco+ immunosuppressive macrophages, which consequently limit excessive inflammation at the gateway of the liver. Failure of this self-limiting system promotes hepatic inflammatory disorders such as PSC and NASH.

Macrophage niche imprinting as a determinant of macrophage identity and function

Macrophage niches are the anatomical locations within organs or tissues consisting of various cells, intercellular and extracellular matrix, transcription factors, and signaling molecules that interact to influence macrophage self-maintenance, phenotype, and behavior. The niche, besides physically supporting macrophages, imposes a tissue- and organ-specific identity on the residing and infiltrating monocytes and macrophages. In this review, we give examples of macrophage niches and the modes of communication between macrophages and surrounding cells. We also describe how macrophages, acting against their immune defensive nature, can create a hospitable niche for pathogens and cancer cells.

How gut microbiota may impact ocular surface homeostasis and related disorders

Changes in the bacterial flora in the gut, also described as gut microbiota, are readily acknowledged to be associated with several systemic diseases, especially those with an inflammatory, neuronal, psychological or hormonal factor involved in the pathogenesis and/or the perception of the disease. Maintaining ocular surface homeostasis is also based on all these four factors, and there is accumulating evidence in the literature on the relationship between gut microbiota and ocular surface diseases. The mechanisms involved are mostly interconnected due to the interaction of central and peripheral neuronal networks, inflammatory effectors and the hormonal system. A better understanding of the influence of the gut microbiota on the maintenance of ocular surface homeostasis, and on the onset or persistence of ocular surface disorders could bring new insights and help elucidate the epidemiology and pathology of ocular surface dynamics in health and disease. Revealing the exact nature of these associations could be of paramount importance for developing a holistic approach using highly promising new therapeutic strategies targeting ocular surface diseases.

Fecal microbiota transplantation from female donors restores gut permeability and reduces liver injury and inflammation in middle-aged male mice exposed to alcohol

Background

Alcohol misuse, binge drinking pattern, and gender-specific effects in the middle-aged population has been clearly underestimated. In the present study, we focused on understanding gender-specific effects of alcohol exposure on the gut-liver axis and the role of gut microbiota in modulating gender-specific responses to alcohol consumption.

Methods

Fifty-two-week-old female and male C57BL/6 mice were fasted for 12 h, and then administered a single oral dose of ethanol (EtOH) (6 g/kg). Controls were given a single dose of PBS. Animals were sacrificed 8 h later. Alternatively, fecal microbiota transplantation (FMT) was performed in 52-week-old male mice from female donors of the same age. Permeability of the large intestine (colon), gut microbiota, liver injury, and inflammation was thoroughly evaluated in all groups.

Results

Middle-aged male mice exposed to EtOH showed a significant increase in gut permeability in the large intestine, evaluated by FITC-dextran assay and ZO-1, OCCLUDIN and MUCIN-2 immuno-staining, compared to PBS-treated animals, whilst female mice of the same age also increased their gut permeability, but displayed a partially maintained intestinal barrier integrity. Moreover, there was a significant up-regulation of TLRs and markers of hepatocellular injury, cell death (AST, TUNEL-positive cells) and lipid accumulation (ORO) in male mice after EtOH exposure. Interestingly, FMT from female donors to male mice reduced gut leakiness, modified gut microbiota composition, ameliorated liver injury and inflammation, TLR activation and the senescence phenotype of middle-aged mice.

Conclusion

Our findings highlighted the relevance of gender in middle-aged individuals who are exposed to alcohol in the gut-liver axis. Moreover, our study revealed that gender-specific microbiota transplantation might be a plausible therapy in the management of alcohol-related disorders during aging.

Salmonella manipulates macrophage migration via SteC-mediated myosin light chain activation to penetrate the gut-vascular barrier

The intestinal pathogen Salmonella enterica rapidly enters the bloodstream after the invasion of intestinal epithelial cells, but how Salmonella breaks through the gut-vascular barrier is largely unknown. Here, we report that Salmonella enters the bloodstream through intestinal CX3CR1+ macrophages during early infection. Mechanistically, Salmonella induces the migration/invasion properties of macrophages in a manner dependent on host cell actin and on the pathogen effector SteC. SteC recruits host myosin light chain protein Myl12a and phosphorylates its Ser19 and Thr20 residues. Myl12a phosphorylation results in actin rearrangement, and enhanced migration and invasion of macrophages. SteC is able to utilize a wide range of NTPs other than ATP to phosphorylate Myl12a. We further solved the crystal structure of SteC, which suggests an atypical dimerization-mediated catalytic mechanism. Finally, in vivo data show that SteC-mediated cytoskeleton manipulation is crucial for Salmonella breaching the gut vascular barrier and spreading to target organs.

Gut-Liver Axis Dysregulation in Portal Hypertension: Emerging Frontiers

Portal hypertension (PH) is a complex clinical challenge with severe complications, including variceal bleeding, ascites, hepatic encephalopathy, and hepatorenal syndrome. The gut microbiota (GM) and its interconnectedness with human health have emerged as a captivating field of research. This review explores the intricate connections between the gut and the liver, aiming to elucidate how alterations in GM, intestinal barrier function, and gut-derived molecules impact the development and progression of PH. A systematic literature search, following PRISMA guidelines, identified 12 original articles that suggest a relationship between GM, the gut-liver axis, and PH. Mechanisms such as dysbiosis, bacterial translocation, altered microbial structure, and inflammation appear to orchestrate this relationship. One notable study highlights the pivotal role of the farnesoid X receptor axis in regulating the interplay between the gut and liver and proposes it as a promising therapeutic target. Fecal transplantation experiments further emphasize the pathogenic significance of the GM in modulating liver maladies, including PH. Recent advancements in metagenomics and metabolomics have expanded our understanding of the GM's role in human ailments. The review suggests that addressing the unmet need of identifying gut-liver axis-related metabolic and molecular pathways holds potential for elucidating pathogenesis and directing novel therapeutic interventions.

Gastrointestinal and brain barriers: unlocking gates of communication across the microbiota-gut-brain axis

Crosstalk between gut and brain has long been appreciated in health and disease, and the gut microbiota is a key player in communication between these two distant organs. Yet, the mechanisms through which the microbiota influences development and function of the gut-brain axis remain largely unknown. Barriers present in the gut and brain are specialized cellular interfaces that maintain strict homeostasis of different compartments across this axis. These barriers include the gut epithelial barrier, the blood-brain barrier and the blood-cerebrospinal fluid barrier. Barriers are ideally positioned to receive and communicate gut microbial signals constituting a gateway for gut-microbiota-brain communication. In this Review, we focus on how modulation of these barriers by the gut microbiota can constitute an important channel of communication across the gut-brain axis. Moreover, barrier malfunction upon alterations in gut microbial composition could form the basis of various conditions, including often comorbid neurological and gastrointestinal disorders. Thus, we should focus on unravelling the molecular and cellular basis of this communication and move from simplistic framing as 'leaky gut'. A mechanistic understanding of gut microbiota modulation of barriers, especially during critical windows of development, could be key to understanding the aetiology of gastrointestinal and neurological disorders.

1,25(OH)2D3 supplementation alleviates gut-vascular barrier disruption via inhibition of S100B/ADAM10 pathway

Gut-vascular barrier (GVB) is the second barrier in mucosa to control systemic dissemination of gut bacteria. Severe burns induce enteroglial cells to produce S100B and endothelial cells to generate ADAM10 and cause vitamin D3 insufficiency/deficiency and GVB disruption. It is not clear whether vitamin D3 supplementation attenuates GVB damage via regulation of S100B/ADAM10 pathway. Here, GVB disruption was induced by 30% of total body surface area scalds. Rats were treated with 1,25(OH)2D3 (0.05, 0.5 or 5 μg/kg) or S100B monoclonal antibody (S100BmAb, 10 μg/kg) or GI254023X (ADAM10 inhibitor, 100 mg/kg). Rat enteric glial cell-line CRL2690 and rat intestinal microvascular endothelial cells (RIMECs) were treated with S100B (5 μM) or plus 1,25(OH)2D3 (0.05, 0.5 or 5 μM) or GI254023X (5 μM). S100B, TNF-α, 25(OH)D3 and 1,25(OH)2D3 in serum and gut mucosa were determined by enzyme-linked immunosorbent assay. The endothelial permeability was measured using FITC-dextran 70 kDa. ADAM10 and β-catenin expression was assayed by Western blot. The results showed that 1,25(OH)2D3 and 25(OH)D3 concentration in serum reduced whereas TNF-α and S100B in serum and gut mucosa increased in burned rats. S100BmAb, GI254023X and 1,25(OH)2D3 treatment lowered burns-increased GVB permeability. 1,25(OH)2D3 also decreased S100B concentration in serum and gut mucosa. 1,25(OH)2D3 inhibited S100B release from TNF-α-treated CRL2690 and raised β-catenin while decreasing ADAM10 protein in S100B-treated RIMECs. 1,25(OH)2D3 and GI254023X also decreased the endothelial permeability of S100B-treated RIMECs. Collectively, these findings provide evidence that severe burns lower serum 25(OH)D3 and 1,25(OH)2D3 concentration. 1,25(OH)2D3 supplementation alleviates burns-elicited GVB disruption via inhibition of S100B/ADAM10 signaling.

The missing hallmark of health: psychosocial adaptation

The eight biological hallmarks of health that we initially postulated (Cell. 2021 Jan 7;184(1):33-63) include features of spatial compartmentalization (integrity of barriers, containment of local perturbations), maintenance of homeostasis over time (recycling & turnover, integration of circuitries, rhythmic oscillations) and an array of adequate responses to stress (homeostatic resilience, hormetic regulation, repair & regeneration). These hallmarks affect all eight somatic strata of the human body (molecules, organelles, cells, supracellular units, organs, organ systems, systemic circuitries and meta-organism). Here we postulate that mental and socioeconomic factors must be added to this 8×8 matrix as an additional hallmark of health ("psychosocial adaptation") and as an additional stratum ("psychosocial interactions"), hence building a 9×9 matrix. Potentially, perturbation of each of the somatic hallmarks and strata affects psychosocial factors and vice versa. Finally, we discuss the (patho)physiological bases of these interactions and their implications for mental health improvement.

The effect of adding wheat and corn gluten to the diet of rats on the autoimmune and histopathological parameters in the intestine and liver

This study investigated the histopathological and immunohistochemical effect on the intestine and liver tissues with addition of the soybean meal (SBM), wheat Gluten meal (WGM) and Corn gluten meal (CGM) to rat diet. A total of 24 average twenty–day–old male rats (Wistar albino) were used in the study. The rats were randomly divided into 3 groups with 8 animals in each group (Control, Wheat and Corn groups). The diet provided to all three groups contained proteins, which were SBM, WGM and CGM in the Control, Wheat and Corn groups, respectively. In the study, the group fed with SBM was used as the Control group. Rats were fed a diet containing 22% crude protein and 2,598 kcal·kg-1 metabolic energy throughout the experimental period. The feeding trial was continued for a period of 50 days. Degenerative changes of varying severity in intestinal epithelial cells and atrophy in villi were observed. Similarly, the degenerative changes, especially vacuolar or hydropic degeneration were determined in hepatocytes. It was determined that the CD4 level were statistically significantly increased in the Wheat and Corn groups compared to the Control group (P<0.01) on intestine tissue. Also, it was determined that the IgA level was statistically significantly increased of the Wheat and Corn groups in liver tissue. (P<0.05). As a result, it was observed that the histopathological and immunohistochemical parameters of the intestine and liver tissues of the rats fed with diets containing highly WGM and CGM were limitedly affected.

Bovine Colostrum Supplementation in Rabbit Diet Modulates Gene Expression of Cytokines, Gut-Vascular Barrier, and Red-Ox-Related Molecules in the Gut Wall

Rabbits, pivotal in the EU as livestock, pets, and experimental animals, face bacterial infection challenges, prompting a quest for alternatives to curb antibiotic resistance. Bovine colostrum (BC), rich in immunoregulatory compounds, antimicrobial peptides, and growth factors, is explored for disease treatment and prevention. This study assesses BC diet supplementation effects on rabbit intestines, examining gene expression. Thirty female New Zealand White rabbits at weaning (35 days) were divided into three experimental groups: control (commercial feed), 2.5% BC, and 5% BC. The diets were administered until slaughtering (81 days). BC-upregulated genes in the jejunum included IL-8, TGF-β, and CTNN-β1 at 5% BC, while PLVAP at 2.5% BC. Antioxidant-related genes (SOD1, GSR) were downregulated in the cecum and colon with 2.5% BC. BC 5% promoted IL-8 in the jejunum, fostering inflammation and immune cell migration. It also induced genes regulating inflammatory responses (TGF-β) and gastrointestinal permeability (CTNN-β1). BC 5% enhanced antioxidant activity in the cecum and colon, but no significant impact on anti-myxo antibody production was observed. These results suggest that BC has significant effects on the rabbit gastrointestinal tract's inflammatory and antioxidant response, but further research is required to fully understand its histological and physiological impact.

The gut-brain axis: Correlation of choroid plexus volume and permeability with inflammatory biomarkers in Crohn's disease

BACKGROUND

The dysregulation of the gut-brain axis in chronic inflammatory bowel diseases can cause neuro-psychological disturbances, but the underlying mechanisms are still not fully understood. The choroid plexus (CP) maintains brain homeostasis and nourishment through the secretion and clearance of cerebrospinal fluid. Recent research has demonstrated the existence of a CP vascular barrier in mice which is modulated during intestinal inflammation. This study investigates possible correlations between CP modifications and inflammatory activity in patients with Crohn's disease (CD).

METHODS

In this prospective study, 17 patients with CD underwent concomitant abdominal and brain 3 T MRI. The volume and permeability of CP were compared with levels of C-reactive protein (CRP), fecal calprotectin (FC), sMARIA and SES-CD scores.

RESULTS

The CP volume was negatively correlated with CRP levels (R = -0.643, p-value = 0.024) and FC (R = -0.571, p-value = 0.050). DCE metrics normalized by CP volume were positively correlated with CRP (K-trans: R = 0.587, p-value = 0.045; Vp: R = 0.706, p-value = 0.010; T1: R = 0.699, p-value = 0.011), and FC (Vp: R = 0.606, p-value = 0.037).

CONCLUSIONS

Inflammatory activity in patients with CD is associated with changes in CP volume and permeability, thus supporting the hypothesis that intestinal inflammation could affect the brain through the modulation of CP vascular barrier also in humans.

Adipose tissue macrophage dysfunction is associated with a breach of vascular integrity in NASH

BACKGROUND & AIMS

In non-alcoholic fatty liver disease (NAFLD), monocytes infiltrate visceral adipose tissue promoting local and hepatic inflammation. However, it remains unclear what drives inflammation and how the immune landscape in adipose tissue differs across the NAFLD severity spectrum. We aimed to assess adipose tissue macrophage (ATM) heterogeneity in a NAFLD cohort.

METHODS

Visceral adipose tissue macrophages from lean and obese patients, stratified by NAFLD phenotypes, underwent single-cell RNA sequencing. Adipose tissue vascular integrity and breaching was assessed on a protein level via immunohistochemistry and immunofluorescence to determine targets of interest.

RESULTS

We discovered multiple ATM populations, including resident vasculature-associated macrophages (ResVAMs) and distinct metabolically active macrophages (MMacs). Using trajectory analysis, we show that ResVAMs and MMacs are replenished by a common transitional macrophage (TransMac) subtype and that, during NASH, MMacs are not effectively replenished by TransMac precursors. We postulate an accessory role for MMacs and ResVAMs in protecting the adipose tissue vascular barrier, since they both interact with endothelial cells and localize around the vasculature. However, across the NAFLD severity spectrum, alterations occur in these subsets that parallel an adipose tissue vasculature breach characterized by albumin extravasation into the perivascular tissue.

CONCLUSIONS

NAFLD-related macrophage dysfunction coincides with a loss of adipose tissue vascular integrity, providing a plausible mechanism by which tissue inflammation is perpetuated in adipose tissue and downstream in the liver.

IMPACT AND IMPLICATIONS

Our study describes for the first time the myeloid cell landscape in human visceral adipose tissue at single-cell level within a cohort of well-characterized patients with non-alcoholic fatty liver disease. We report unique non-alcoholic steatohepatitis-specific transcriptional changes within metabolically active macrophages (MMacs) and resident vasculature-associated macrophages (ResVAMs) and we demonstrate their spatial location surrounding the vasculature. These dysfunctional transcriptional macrophage states coincided with the loss of adipose tissue vascular integrity, providing a plausible mechanism by which tissue inflammation is perpetuated in adipose tissue and downstream in the liver. Our study provides a theoretical basis for new therapeutic strategies to be directed towards reinstating the endogenous metabolic, homeostatic and cytoprotective functions of ResVAMs and MMacs, including their role in protecting vascular integrity.

Escherichia coli NF73-1 disrupts the gut-vascular barrier and aggravates high-fat diet-induced fatty liver disease via inhibiting Wnt/β-catenin signalling pathway

BACKGROUND & AIMS

Gut-vascular barrier (GVB) dysfunction has been shown to be a prerequisite for nonalcoholic fatty liver disease (NAFLD) development. However, the causes of GVB disruption and the underlying mechanisms are still elusive. Here, we explored whether and how Escherichia coli (E. coli) NF73-1, a pathogenic E. coli strain isolated from nonalcoholic steatohepatitis patients, contributes to NAFLD by modulating the GVB.

METHODS

C57BL/6J mice were fed with high-fat diet (HFD) or normal diet in the presence or absence of E. coli NF73-1 for the indicated time periods. Intestinal barrier function and infiltration of immune cells were evaluated in these mice. Endothelial cells were exposed to E. coli NF73-1 for barrier integrity analysis.

RESULTS

HFD-induced GVB disruption preceded the damage of intestinal epithelial barrier (IEB) as well as intestinal and hepatic inflammatory changes and can be reversed by vascular endothelial growth factor A blockade. Antibiotic treatment prevented mice from HFD-induced liver steatosis by restoration of the GVB. Notably, E. coli NF73-1 caused a more conspicuous damage of GVB than that of the IEB and contributed to NAFLD development. Mechanistically, E. coli NF73-1 dismantled the GVB by inhibiting the Wnt/β-catenin signalling pathway. Activation of Wnt/β-catenin improved the GVB and impeded the translocation of E. coli NF73-1 into the liver in vitro and in vivo.

CONCLUSIONS

E. coli NF73-1 disrupts GVB and aggravates NAFLD via inhibiting the Wnt/β-catenin signalling pathway. Targeting E. coli NF73-1 or selectively enhancing the GVB may act as potential avenues for the prevention and treatment of NAFLD.