Search

The duodenal epithelium plays a pivotal role in the uptake and transport of dietary nutrients while simultaneously acting as physical and biochemical barrier to protect against harmful bacteria and antigens. In the case of functional dyspepsia (FD), the duodenum is of particular interest, due to observed local immune involvement and the proximity to the stomach and exposure to acidopeptic secretions. Recent observations in FD pathophysiology, including those reported by Beeckmans et al in this issue of the journal, have identified a loss of barrier function in the duodenal epithelium, an altered duodenal microbiome and alterations in intestinal bile acid pools. Because FD symptoms coincide with food intake and, thus, secretion of bile acids, these findings may indicate loss or imbalance of bile‐acid‐microbiota‐epithelial homeostasis as a process driving FD. Here, we review the evidence linking these observations to FD symptoms. [ABSTRACT FROM AUTHOR]

Visceral pain in inflammatory and functional gastrointestinal conditions is a major clinical problem. The exact mechanisms underlying the development of pain, during and after visceral inflammation are unknown. However, clinical and pre-clinical evidence suggests plasticity within the spinal cord dorsal horn is a contributing factor. Here we use an in vivo preparation and patch-clamp electrophysiology to test whether the synaptic and intrinsic properties of superficial dorsal horn (SDH) neurons are altered 5 days after the induction of mild colitis in adult male mice (i.e. during acute inflammation of the colon). Whole-cell recordings were made from lumbosacral (L6-S1) superficial dorsal horn neurons (SDH), in animals under isoflurane anesthesia. Noxious colorectal distension (CRD) was used to identify SDH neurons with colonic inputs, while stimulation of the hind paw and tail was employed to assess convergent cutaneous input. Following inflammation, a significantly increased proportion of SDH neurons received both colonic and cutaneous inputs, compared to neurons in naïve animals. In addition, the nature and magnitude of responses to CRD and cutaneous stimulation differed in inflamed animals, as was spontaneous excitatory synaptic drive. Conversely, several measures of intrinsic excitability were altered in a manner that would decrease SDH network excitability following colitis. We propose that during inflammation, sensitization of colonic afferents results in increased signaling to the SDH. This is accompanied by plasticity in SDH neurons whereby their intrinsic properties are changed to compensate for altered afferent activity. [ABSTRACT FROM AUTHOR]

Gastrointestinal conditions may be broadly classified into two: organic and functional disease, with functional disorders accounting for the majority of patients with chronic gastrointestinal symptoms. Functional gastrointestinal disorders (FGIDs) present with no obvious pathology or well-accepted biochemical mechanism and, as such, treatment strategies are limited and focus on symptoms rather than cure. Irritable bowel syndrome and functional dyspepsia are the most widely recognised FGIDs, and there is a growing body of evidence to suggest an underlying inflammatory phenotype in subsets with these conditions. Here, we discuss the current knowledge of immune involvement in FGIDs and the commonalities between the different manifestations of FGIDs and propose a new hypothesis, potentially defining an underlying immunopathological basis of these conditions. [ABSTRACT FROM AUTHOR]

The transport of fluid, nutrients and electrolytes to and from the intestinal lumen is a primary function of epithelial cells. Normally, the intestine absorbs approximately 9 l of fluid and 1 kg of nutrients daily, driven by epithelial transport processes that consume large amounts of cellular energy and O2. The epithelium exists at the interface of the richly vascularised mucosa, and the anoxic luminal environment and this steep O2 gradient play a key role in determining the expression pattern of proteins involved in fluid, nutrient and electrolyte transport. However, the dynamic nature of the splanchnic circulation necessitates that the epithelium can evoke co-ordinated responses to fluctuations in O2 availability, which occur either as a part of the normal digestive process or as a consequence of several pathophysiological conditions. While it is known that hypoxia-responsive signals, such as reactive oxygen species, AMP-activated kinase, hypoxia-inducible factors, and prolyl hydroxylases are all important in regulating epithelial responses to altered O2 supply, our understanding of the molecular mechanisms involved is still limited. Here, we aim to review the current literature regarding the role that O2 plays in regulating intestinal transport processes and to highlight areas of research that still need to be addressed. [ABSTRACT FROM AUTHOR]

Background: Functional dyspepsia (FD) is a common and debilitating gastrointestinal disorder attributed to altered gut‐brain interactions. While the etiology of FD remains unknown, emerging research suggests the mechanisms are likely multifactorial and heterogenous among patient subgroups. Small bowel motor disturbances, visceral hypersensitivity, chronic microinflammation, and increased intestinal tract permeability have all been linked to the pathogenesis of FD. Recently, alterations to the gut microbiome have also been implicated to play an important role in the disease. Changes to the duodenal microbiota may either trigger or be a consequence of immune and neuronal disturbances observed in the disease, but the mechanisms of influence of small intestinal flora on gastrointestinal function and symptomatology are unknown. Purpose: This review summarizes and synthesizes the literature on the link between the microbiota, low‐grade inflammatory changes in the duodenum and FD. This review is not intended to provide a complete overview of FD or the small intestinal microbiota, but instead outline some of the key conceptual advances in understanding the interactions between altered gastrointestinal bacterial communities; dietary factors; host immune activation; and stimulation of the gut–brain axes in patients with FD versus controls. Current and emerging treatment approaches such as dietary interventions and antibiotic or probiotic use that have demonstrated symptom benefits for patients are reviewed, and their role in modulating the host–microbiota is discussed. Finally, suggested opportunities for diagnostic and therapeutic improvements for patients with this condition are presented. [ABSTRACT FROM AUTHOR]

Background/Aims: Methods: The intestinal epithelial layer can switch from a net absorptive state to one of net secretion in the presence of luminal toxins and pathogens. This suggests an innate defence role for regulated secretion of mucus, electrolytes and water. We hypothesised that chloride-led fluid secretion across the mucus-covered intestinal epithelium alters barrier properties by influencing the overlying mucous-gel layer. Results: We demonstrated that chloride-led disruption of the epithelial-associated mucus-gel covering HT29-MTX-E12 (E12) human colonic epithelial monolayers, a goblet-cell like line derived from parental HT29 cells, resulted in reduction of associated mucus as well as a reduction in mucous-gel density and barrier properties. Changes in epithelial secretory state were accompanied by increased water transport, and the resulting loss of gel integrity reduced Salmonella typhimuriuminvasion of epithelia in both E12 monolayers and of isolated rat ileal mucosae. However, neither chloride secretion nor mucus disruption altered numbers of adhering bacteria. Conclusion: These data suggest a role for chloride led fluid secretion in the shedding of the adherent mucous-gel layer, possibly as a rate-limiting innate defence mechanism, and offer evidence for 'enteric tears' in intestinal host defence. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Tissues of the mucosa are lined by an epithelium that provides barrier and transport functions. It is now appreciated that inflammatory responses in inflammatory bowel diseases are accompanied by striking shifts in tissue metabolism. In this paper, we examined global metabolic consequences of mucosal inflammation using both in vitro and in vivo models of disease. Initial analysis of the metabolic signature elicited by inflammation in epithelial models and in colonic tissue isolated from murine colitis demonstrated that levels of specific metabolites associated with cellular methylation reactions are significantly altered by model inflammatory systems. Furthermore, expression of enzymes central to all cellular methylation, S-adenosylmethionine synthetase and S-adenosylhomocysteine hydrolase, are increased in response to inflammation. Subsequent studies showed that DNA methylation is substantially increased during inflammation and that epithelial NF-κB activity is significantly inhibited following treatment with a reversible S-adenosylhomocysteine hydrolase inhibitor, DZ2002. Finally, these studies demonstrated that inhibition of cellular methylation in a murine model of colitis results in disease exacerbation while folate supplementation to promote methylation partially ameliorates the severity of murine colitis. Taken together, these results identify a global change in methylation, which during inflammation, translates to an overall protective role in mucosal epithelia. [ABSTRACT FROM AUTHOR]

Because of localized vascular damage and increased tissue oxygen demand, wound healing occurs in a relatively hypoxic microenvironment. These features are particularly relevant to wound healing and fibrosis in chronic inflammatory conditions, such as Crohn's disease and ulcerative colitis. In these studies, we sought to identify the contribution of hypoxia to mechanisms of wound repair in a model of the intestinal submucosa. Initial studies revealed that hypoxia promotes wound healing, as modeled by an increase in intestinal fibroblast-mediated collagen gel contraction. Guided by results from transcriptional profiling, we identified the selective induction of fibroblast integrin β1 (ITGB1) by hypoxia. Further analysis revealed that hypoxia, as well as pharmacological activators of hypoxia-inducible factor (HIF), induce fibroblast β1 integrin mRNA, protein, and function by as much as 4-fold. Cloning and analysis of the β1 integrin gene promoter revealed a 10 ± 0.8-fold increase in promoter activity in response to hypoxia, and subsequent studies identified a functional DNA binding region for HIF in the ITGB1 gene promoter. Mutational analysis of the HIF binding site within the ITGB1 promoter resulted in a significant loss of ITGB1 hypoxia-inducibility. As proof of principle, studies in a murine model of colitis revealed a correlation between colitic disease severity and tissue ITGBI expression (R²=0.80). Taken together, these results demonstrate that hypoxia induces fibroblast ITGB1 expression and function by transcriptional mechanisms dependent on HIF. [ABSTRACT FROM AUTHOR]

Abstract: The mucoadhesive polymer, poly(dimethylamino)ethyl methacrylate, (pDMAEMA), was synthesised by living radical polymerisation and subsequently conjugated by quaternisation reaction to a functionalised anti-inflammatory corticosteroid dexamethasone, to separately yield two conjugates with either 9:1 or 18:1 molar ratios of dexamethasone:polymer respectively. The hypothesis was to test whether the active agent maintained in vitro bioactivity when exposed to the apical side of human intestinal epithelial monolayers, Caco-2 and mucos-covered HT29-MTX-E12 (E12). HPLC analysis indicated high conjugate purity. Similar to pDMAEMA, fluorescently-labelled dexamethasone–pDMAEMA conjugates were bioadhesive to Caco-2 and mucoadhesive to E12. Apical addition of conjugates suppressed mRNA expression of the inflammatory markers, NURR1 and ICAM-1 in E12 following stimulation by PGE2 and TNF-α, respectively. Conjugates also suppressed TNF-α stimulated cytokine secretion to the basolateral side of Caco-2 monolayers. Measurement of dexamethasone permeability from conjugates across monolayers suggested that conjugation reduced permeability compared to free dexamethasone. LDH assay indicated that conjugates were not cytotoxic to monolayers. Anti-inflammatory agents can therefore be successfully conjugated to polymers and they retain adhesion and bioactivity and have potential to be formulated for topical administration. [Copyright &y& Elsevier]

Eosinophils are commonly associated with Th2 cell-driven inflammation. In this issue of Immunity , Griseri et al. (2015) identify a new GM-CSF-dependent role for eosinophils in the pathogenesis of IL-23-Th17 cell-induced colitis. [ABSTRACT FROM AUTHOR]

Background: Irritable bowel syndrome (IBS) is considered a disorder of gut-brain interaction (DGBI), presenting as chronic abdominal pain and altered defaecation. Symptoms are often food related. Much work in the field has focused on identifying physiological, immune and microbial abnormalities in the colon of patients; however, evidence of small intestinal immune activation and microbial imbalance has been reported in small studies. The significance of such findings has been largely underappreciated despite a growing body of work implicating small intestinal homeostatic imbalance in the pathogenesis of DGBIs.Main Text: Small intestinal mechanosensation is a characteristic feature of IBS. Furthermore, altered small intestinal barrier functions have been demonstrated in IBS patients with the diarrhoea-predominant subtype. Small intestinal bacterial overgrowth and increased populations of small intestinal mast cells are frequently associated with IBS, implicating microbial imbalance and low-grade inflammation in the pathogenesis of IBS. Furthermore, reports of localised food hypersensitivity responses in IBS patients implicate the small intestine as the site of immune-microbial-food interactions.Conclusions: Given the association of IBS symptoms with food intake in a large proportion of patients and the emerging evidence of immune activation in these patients, the current literature suggests the pathogenesis of IBS is not limited to the colon but rather may involve dysfunction of the entire intestinal tract. It remains unclear if regional variation in IBS pathology explains the various symptom phenotypes and further work should consider the intestinal tract as a whole to answer this question. [ABSTRACT FROM AUTHOR]

Aim: The gastrointestinal bile acid (BA)/microbiota axis has emerged as a potential mediator of health and disease, particularly in relation to pathologies such as inflammatory bowel disease (IBD) and colorectal cancer. Whilst it presents an exciting new avenue for therapies, it has not yet been characterized in surgical resection of the ileum, where BA reabsorption occurs. The identification of BA/microbiota signatures may provide future therapies with perioperative personalized medicine. In this work we conduct a systematic review with the aim of investigating the microbiome and BA changes that are associated with resection of the ileum. Method: The databases included were MEDLINE, EMBASE, Web of Science and Cochrane libraries. The outcomes of interest were faecal microbiome and BA signatures after ileal resection. Results: Of the initial 3106 articles, three studies met the inclusion/exclusion criteria for data extraction. A total of 257 patients (46% surgery, 54% nonsurgery controls) were included in the three studies. Two studies included patients with short bowel syndrome and the other included patients with IBD. Large‐scale microbiota changes were reported. In general, alpha diversity had decreased amongst patients with ileal surgery. Phylum‐level changes included decreased Bacteroidetes and increased Proteobacteria and Fusobacteria in patients with an intestinal resection. Surgery was associated with increased total faecal BAs, cholic acid and chenodeoxycholic acid. There were decreases in deoxycholic acid and glycine and taurine conjugated bile salts. Integrated BA and microbiota data identified correlations with several bacterial families and BA. Conclusion: The BA/microbiota axis is still a novel area with minimal observational data in surgery. Further mechanistic research is necessary to further explore this and identify its role in improving perioperative outcomes. [ABSTRACT FROM AUTHOR]

In this study, the intestinal permeability of metal(loid)s (MLs) such as arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg) was examined, as influenced by gut microbes and chelating agents using an in vitro gastrointestinal/Caco-2 cell intestinal epithelium model. The results showed that in the presence of gut microbes or chelating agents, there was a significant decrease in the permeability of MLs (As-7.5%, Cd-6.3%, Pb-7.9% and Hg-8.2%) as measured by apparent permeability coefficient value (Papp), with differences in ML retention and complexation amongst the chelants and the gut microbes. The decrease in ML permeability varied amongst the MLs. Chelating agents reduce intestinal absorption of MLs by forming complexes thereby making them less permeable. In the case of gut bacteria, the decrease in the intestinal permeability of MLs may be associated to a direct protection of the intestinal barrier against the MLs or indirect intestinal ML sequestration by the gut bacteria through adsorption on bacterial surface. Thus, both gut microbes and chelating agents can be used to decrease the intestinal permeability of MLs, thereby mitigating their toxicity. [ABSTRACT FROM AUTHOR]

Objectives This study aims to determine what pathologic and clinical factors differentiate Brachyspira species that may be useful to clinicians and pathologists. Methods We identified 21 studies of Brachyspira infection with individual patient information (n = 113) and conducted a pooled analysis comparing each species. Results There were differences in the pathologic and clinical profiles of each Brachyspira species. Patients infected with Brachyspira pilosicoli infection were more likely to have diarrhea, fever, HIV, and immunocompromised conditions. Those patients infected with Brachyspira aalborgi were more likely to have lamina propria inflammation. Conclusions Our novel data provide potential insights into the pathogenic mechanism(s) and the specific risk factor profile of Brachyspira species. This may be clinically useful when assessing and managing patients. [ABSTRACT FROM AUTHOR]

Background: Surgical Site Infection (SSI) of the abdominal incision is a dreaded complication following colorectal surgery. Identifying the intraoperative surgical site microbes may provide clarity in the pathogenesis of SSIs. Genomic sequencing has revolutionized the ability to identify microbes from clinical samples. Utilization of 16S rRNA amplicon sequencing to characterize the intraoperative surgical site may provide the critical information required to predict and prevent infection in colorectal surgery. Methods: This is a pilot, prospective observational study of 50 patients undergoing elective colorectal resection. At completion of surgery, prior to skin closure, swabs were taken from the subcutaneous tissue of the abdominal incision to investigate the microbial profile. Dual swabs were taken to compare standard culture technique and 16S rRNA sequencing to establish if a microbial profile was associated with postoperative SSI. Results: 8/50 patients developed an SSI, which was more likely in those undergoing open surgery (5/15 33.3% versus 3/35, 8.6%; P = 0.029). 16S rRNA amplicon sequencing was more sensitive in microbial detection compared to traditional culture. Both culture and 16S rRNA demonstrated contamination of the surgical site, predominantly with anaerobes. Culture was not statistically predictive of infection. 16S rRNA amplicon sequencing was not statistically predictive of infection, however, it demonstrated patients with an SSI had an increased biodiversity (not significant) and a greater relative abundance (not significant) of pathogens such as Bacteroidacaea and Enterobacteriaceae within the intraoperative site. Conclusions: 16S rRNA amplicon sequencing has demonstrated a potential difference in the intraoperative microbial profile of those that develop an infection. These findings require validation through powered experiments to determine the overall clinical significance. [ABSTRACT FROM AUTHOR]

Background: Acute myeloid leukaemia (AML) is a deadly disease characterised by the uncontrolled proliferation of immature myeloid cells within the bone marrow. Altered regulation of DNA methylation is an important epigenetic driver of AML, where the hypoxic bone marrow microenvironment can help facilitate leukaemogenesis. Thus, interactions between epigenetic regulation and hypoxia signalling will have important implications for AML development and treatment. Main body: This review summarises the importance of DNA methylation and the hypoxic bone marrow microenvironment in the development, progression, and treatment of AML. Here, we focus on the role hypoxia plays on signalling and the subsequent regulation of DNA methylation. Hypoxia is likely to influence DNA methylation through altered metabolic pathways, transcriptional control of epigenetic regulators, and direct effects on the enzymatic activity of epigenetic modifiers. DNA methylation may also prevent activation of hypoxia-responsive genes, demonstrating bidirectional crosstalk between epigenetic regulation and the hypoxic microenvironment. Finally, we consider the clinical implications of these interactions, suggesting that reduced cell cycling within the hypoxic bone marrow may decrease the efficacy of hypomethylating agents. Conclusion: Hypoxia is likely to influence AML progression through complex interactions with DNA methylation, where the therapeutic efficacy of hypomethylating agents may be limited within the hypoxic bone marrow. To achieve optimal outcomes for AML patients, future studies should therefore consider co-treatments that can promote cycling of AML cells within the bone marrow or encourage their dissociation from the bone marrow. [ABSTRACT FROM AUTHOR]

Aims: Eosinophils contribute to tissue homeostasis, damage, and repair. The mucosa of colonic diverticula has not been evaluated for eosinophils by quantitative histology. We aimed to investigate whether mucosal eosinophils and other immune cells are increased in colonic diverticula. Methods: Hematoxylin and eosin stained sections from colonic surgical resections (n = 82) containing diverticula were examined. Eosinophils, neutrophils, and lymphocytes, in five high power fields in the lamina propria were counted at the base, neck, and ostia of the diverticulum and counts compared to non‐diverticula mucosa. The cohort was further subgrouped by elective and emergency surgical indications. Results: Following an initial review of 10 surgical resections from patients with diverticulosis, a total of 82 patients with colonic resections containing diverticula from the descending colon were evaluated (median age 71.5, 42 M/40F). Eosinophil counts for the entire cohort were increased in the base and neck (median 99 and 42, both P = <0.001) compared with the control location (median 16). Eosinophil counts remained significantly increased in the diverticula base (both P = <0.001) and neck (P = 0.01 and <0.001, respectively) in both elective and emergency cases. Lymphocytes were also significantly increased at the diverticula base compared to controls in both elective and emergency subgroups. Conclusion: Eosinophils are significantly and most strikingly increased within the diverticulum in resected colonic diverticula. While these observations are novel, the role of eosinophil and chronic inflammation is as yet unclear in the pathophysiology of colonic diverticulosis and diverticular disease. [ABSTRACT FROM AUTHOR]

Background and Aims: The role of the microbiota in diverticulosis and diverticular disease is underexplored. This systematic review aimed to assess all literature pertaining to the microbiota and metabolome associations in asymptomatic diverticulosis, symptomatic uncomplicated diverticular disease (SUDD), and diverticulitis pathophysiology. Methods: Seven databases were searched for relevant studies published up to September 28, 2022. Data were screened in Covidence and extracted to Excel. Critical appraisal was undertaken using the Newcastle Ottawa Scale for case/control studies. Results: Of the 413 papers screened by title and abstract, 48 full‐text papers were reviewed in detail with 12 studies meeting the inclusion criteria. Overall, alpha and beta diversity were unchanged in diverticulosis; however, significant changes in alpha diversity were evident in diverticulitis. A similar Bacteroidetes to Firmicutes ratio compared with controls was reported across studies. The genus‐level comparisons showed no relationship with diverticular disease. Butyrate‐producing microbial species were decreased in abundance, suggesting a possible contribution to the pathogenesis of diverticular disease. Comamonas species was significantly increased in asymptomatic diverticulosis patients who later developed diverticulitis. Metabolome analysis reported significant differences in diverticulosis and SUDD, with upregulated uracil being the most consistent outcome in both. No significant differences were reported in the mycobiome. Conclusion: Overall, there is no convincing evidence of microbial dysbiosis in colonic diverticula to suggest that the microbiota contributes to the pathogenesis of asymptomatic diverticulosis, SUDD, or diverticular disease. Future research investigating microbiota involvement in colonic diverticula should consider an investigation of mucosa‐associated microbial changes within the colonic diverticulum itself. [ABSTRACT FROM AUTHOR]

Background: Surgical site infection remains a significant cause of morbidity and mortality. Traditionally, the causation has been inferred from the organism(s) detected in the post-operative setting. However, the intra-operative surgical site and the bacteria it harbors have been scarcely studied. Compared with culture-dependent methods, the development of genomic technology provides a new sensitive tool that could aid in characterizing the bacteria within the surgical site. The purpose of this literature review is to establish if there is a predictive role of sampling the intra-operative surgical site. Methods: A systematic literature review was conducted identifying relevant literature reporting on studies that sampled the intra-operative surgical site of any specialty, using either traditional culture or a culture-independent genomic sequencing-based technique and correlation with infection was attempted. The review identified studies between 1959 and 2021 in MEDLINE, EMBASE and Cochrane. Results: The initial search identified 7,835 articles; 36 remained after screening. Thirty-one articles focused on culture-dependent techniques, five on culture-independent. Subgroup meta-analysis demonstrates that a positive intra-operative culture carries a risk of downstream infection with an odds ratio of 8.6, however limited by a high false-positive and inability to correlate the intra-operative culture with the post-operative infection. In contrast, culture-independent studies through genomic sequencing are not predictive but suggest that the surgical incision is a complex microbial community with a shift toward dysbiosis in certain patients. Conclusion: The intra-operative surgical site clearly harbors bacteria. Both techniques give rise to separate explanations underpinning the role of bacteria in surgical site infection. It is possible there is a more complex dynamic community within the incision that makes a patient susceptible to infection. Characterizing this microbial community in large scale studies, including patients with infections may enhance our ability to predict and prevent incisional surgical site infections in patients undergoing surgical procedures. [ABSTRACT FROM AUTHOR]

Eosinophilic esophagitis (EoE) is an atopic disease of the esophagus that has shown a significant increase in incidence and prevalence in the last 20 years. The etiology of EoE is unclear, and few studies explore the esophageal microbiota in EoE. The local microbiome has been implicated in the pathogenesis of several allergic and inflammatory diseases, such as asthma and eczema. In this study, we performed a systematic review to evaluate differences in the microbiota profile of patients with EoE compared with controls. MEDLINE, Embase, Cochrane Library, Scopus, and CINAHL (Cumulative Index to Nursing and Allied Health Literature) databases were searched to identify studies investigating the microbiota composition in EoE. Three reviewers screened the articles for eligibility and quality. Seven articles underwent full‐text review, and a narrative synthesis was undertaken. The microbiota of the mouth and esophagus are correlated. Patients with active EoE present increased esophageal microbial load and increased abundance in particular species, such as Haemophilus and Aggregatibacter. On the other hand, EoE patients present a decrease in Firmicutes. High microbial load and abundance of Haemophilus are observed in EoE patients, but little evidence exists to demonstrate their influence on inflammation and disease. Understanding microbial signatures in EoE might contribute to the development of novel therapeutic strategies. [ABSTRACT FROM AUTHOR]

Human colonic spirochetosis (CS) is usually due toBrachyspira pilosicolior Brachyspira aalborgiinfection. While traditionally considered to be commensal bacteria, there are scattered case reports and case series of gastrointestinal (GI) symptoms in CS and reports of colonic polyps with adherent spirochetes. We performed a systematic review and meta‐analysis investigating the association between CS and GI symptoms and conditions including the irritable bowel syndrome (IBS) and colonic polyps. Following PRISMA 2020 guidelines, a systematic search of Medline, CINAHL, EMBASE, and Web of Science was performed using specific keywords for CS and GI disease. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random‐effects model. Of 75 studies identified in the search, 8 case–control studies met the inclusion criteria for meta‐analysis and 67 case series studies met the inclusion criteria for pooled prevalence analysis. CS was significantly associated with diarrhea (n = 141/127, cases/controls, OR: 4.19, 95% CI: 1.72–10.21, P = 0.002) and abdominal pain (n = 64/65, OR: 3.66, 95% CI: 1.43–9.35, P = 0.007). CS cases were significantly more likely to have Rome III‐diagnosed IBS (n = 79/48, OR: 3.84, 95% CI: 1.44–10.20, P = 0.007), but not colonic polyps (n = 127/843, OR: 8.78, 95% CI: 0.75–103.36, P = 0.084). In conclusion, we found evidence of associations between CS and both diarrhea and IBS, but not colonic polyps. CS is likely underestimated due to suboptimal diagnostic methods and may be an overlooked risk factor for a subset of IBS patients with diarrhea. [ABSTRACT FROM AUTHOR]

Functional gastrointestinal disorders (FGIDs) encompass a range of complex conditions with similar clinical characteristics and no overt pathology. Recent recognition of sub‐clinical pathologies in FGIDs, in conjunction with physiological and biochemical abnormalities including increased intestinal permeability, microbial profile alterations, differences in metabolites and extra‐intestinal manifestations of disease, call into question the designation of these conditions as 'functional'. This is despite significant heterogeneity in both symptom profile and specifics of reported physiological abnormalities hampering efforts to determine defined mechanisms that drive onset and chronicity of symptoms. Instead, the literature demonstrates these conditions are disorders of homeostatic imbalance, with disruptions in both host and microbial function and metabolism. This imbalance is also associated with extraintestinal abnormalities including psychological comorbidities and fatigue that may be a consequence of gastrointestinal disruption. Given the exploitation of such abnormalities will be crucial for improved therapeutic selection, an enhanced understanding of the relationship between alterations in function of the gastrointestinal tract and the response of the immune system is of interest in identifying mechanisms that drive FGID onset and chronicity. Considerations for future research should include the role of sex hormones in regulating physiological functions and treatment responses in patients, as well as the importance of high‐level phenotyping of clinical, immune, microbial and physiological parameters in study cohorts. There is opportunity to examine the functional contribution of the microbiota and associated metabolites as a source of mechanistic insight and targets for therapeutic modulation. [ABSTRACT FROM AUTHOR]

In intact mucosal tissues, epithelial cells are anatomically positioned in proximity to a number of subepithelial cell types, including endothelia. A number of recent studies have suggested that imbalances between energy supply and demand can result in "inflammatory hypoxia." Given these associations, we hypothesized that endothelial-derived, hypoxia-inducible mediators might infuence epithelial function. Guided by cDNA microarray analysis of human microvascular endothelial cells (HMEC-1 line) subjected to hypoxia (pO2 20 torr, 8 h), we identified adrenomedullin (ADM) as a prominent hypoxia-inducible factor (HIF) that acts on epithelial cells through cell surface receptors. We assessed the functional ability for exogenous ADM to signal in human intestinal Caco2 cells in vitro by demonstrating a dose-dependent induction of Erk1/2phosphorylation. Further analysis revealed that ADM deneddylates cullin-2 (Cul2), whose action has been demonstrated to control the activity of HIF. Caco2 cells stably expressing a hypoxic response element (HRE)-driven luciferase promoter confirmed that ADM activates the HIF signaling pathway. Extensions of these studies revealed an increase in canonical HIF-1- dependent genes following stimulation with ADM. To define physiological relevance, we investigated the effect of ADM in a DSS model of murine colitis. Administration of ADMresulted in reduced inflammatory indices and less severe histological inflammation compared to vehicle controls. Analysis of tissue and serum cytokines showed a marked and significant inhibition of colitis-associated TNF-α, IL-1β, and KC. Analysis of circulating ADM demonstrated an increase in serum ADM in murine models of colitis. Taken together, these results identify ADM as an endogenously generated vascular mediator that functions as a mucosal protective factor through fine tuning of HIF activity. [ABSTRACT FROM AUTHOR]

Summary: Background: Psychological distress, strongly associated with functional gastrointestinal disorders (FGIDS), likely plays a central role in the pathophysiology. The role of sleep disturbances in FGIDs is unclear, and an association with psychological factors is uncertain. Aim: To determine whether sleep disturbances are associated with irritable bowel syndrome (IBS) and functional dyspepsia (FD) and if a potential association is explained by psychological distress. Methods: Adult sample randomly selected from a region in New South Wales, Australia in 2015 who returned a follow‐up mail survey in 2018 (response rate, 60.5%) that contained questions on IBS, FD, sleep (MOS‐Sleep Scale) and psychological distress (Kessler 6 scale). Results: Among this population, 10.4% (95% CI 8.8‐12.2) and 17.9% (95% CI 15.9‐20.1) met Rome III criteria for IBS and FD, respectively. The prevalence of any sleep disturbance at least most of the time was common, with a significantly higher prevalence in FGID (IBS and/or FD) compared with the remaining population (41.8% vs 32.2%, P = 0.003). The total sleep problem index was significantly higher for IBS (OR = 1.71 [95% CI 1.29‐2.27], P < 0.0001) (IBS‐diarrhoea predominant and IBS‐mixed but not IBS‐constipation) and FD (OR = 1.80 [1.43‐2.26], P < 0.0001) (both epigastric pain syndrome and postprandial distress syndrome) even after adjusting for age, sex and psychological distress. Conclusion: Both IBS and FD, and most of their major subtypes except IBS‐C, are associated with a range of sleep disturbances. These sleep problems do not appear to be explained by psychological factors and may play an independent role in the pathophysiology. [ABSTRACT FROM AUTHOR]

Intestinal epithelia are critical for maintaining gastrointestinal homeostasis. Epithelial barrier injury, causing inflammation and vascular damage, results in inflammatory hypoxia, and thus, healing occurs in an oxygen-restricted environment. The transcription factor hypoxia-inducible factor (HIF)-1 regulates genes important for cell survival and repair, including the cell adhesion protein b1-integrin. Integrins function as αβ-dimers, and α-integrin-matrix binding is critical for cell migration. We hypothesized that HIF-1 stabilization accelerates epithelial migration through integrin-dependent pathways. We aimed to examine functional and posttranslational activity of α-integrins during HIF-1-mediated intestinal epithelial healing. Wound healing was assessed in T84 monolayers over 24 h with/without prolyl-hydroxylase inhibitor (PHDi) (GB-004), which stabilizes HIF-1α. Gene and protein expression were measured by RT-PCR and immunoblot, and α-integrin localization was assessed by immunofluorescence. α-integrin function was assessed by antibody-mediated blockade, and integrin α6 regulation was determined by HIF-1α chromatin immunoprecipitation. Models of mucosal wounding and 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis were used to examine integrin expression and localization in vivo. PHDi treatment accelerated wound closure and migration within 12 h, associated with increased integrin α2 and α6 protein, but not α3. Functional blockade of integrins α2 and α6 inhibited PHDi-mediated accelerated wound closure. HIF-1 bound directly to the integrin α6 promoter. PHDi treatment accelerated mucosal healing, which was associated with increased α6 immunohistochemical staining in wound-associated epithelium and wound-adjacent tissue. PHDi treatment increased α6 protein levels in colonocytes of TNBS mice and induced a6 staining in regenerating crypts and reepithelialized inflammatory lesions. Together, these data demonstrate a role for HIF-1 in regulating both integrin α2 and α6 responses during intestinal epithelial healing. [ABSTRACT FROM AUTHOR]

The prevalence of chronic immune and metabolic disorders is increasing rapidly. In particular, inflammatory bowel diseases, obesity, diabetes, asthma and chronic obstructive pulmonary disease have become major healthcare and economic burdens worldwide. Recent advances in microbiome research have led to significant discoveries of associative links between alterations in the microbiome and health, as well as these chronic supposedly noncommunicable, immune/metabolic disorders. Importantly, the interplay between diet, microbiome and the mucous barrier in these diseases has gained significant attention. Diet modulates the mucous barrier via alterations in gut microbiota, resulting in either disease onset/exacerbation due to a "poor" diet or protection against disease with a "healthy" diet. In addition, many mucosa‐associated disorders possess a specific gut microbiome fingerprint associated with the composition of the mucous barrier, which is further influenced by host‐microbiome and inter‐microbial interactions, dietary choices, microbe immigration and antimicrobials. Our review focuses on the interactions of diet (macronutrients and micronutrients), gut microbiota and mucous barriers (gastrointestinal and respiratory tract) and their importance in the onset and/or progression of major immune/metabolic disorders. We also highlight the key mechanisms that could be targeted therapeutically to prevent and/or treat these disorders. [ABSTRACT FROM AUTHOR]

Summary: Background: Small intestinal bacterial overgrowth may play a role in gastrointestinal and non‐gastrointestinal diseases. Aims: To use quantitative polymerase chain reaction (qPCR) to determine and compare bacterial loads of duodenal biopsies in asymptomatic controls, and patients with functional gastrointestinal disorders (FGIDs) and inflammatory bowel disease (IBD) including ulcerative colitis (UC) and Crohn's disease (CD). To define effects of gastric acid inhibition on bacterial load, explore links of bacterial load and gastrointestinal symptoms in response to a standardised nutrient challenge and compare bacterial load with glucose breath test results. Methods: In 237 patients (63 controls, 84 FGID and 90 IBD), we collected mucosal samples under aseptic conditions during endoscopy extracted and total DNA. Bacterial load metric was calculated utilising qPCR measurements of the bacterial 16S rRNA gene, normalised to human beta‐actin expression. Standard glucose breath test and nutrient challenge test were performed. Results: The duodenal microbial load was higher in patients with FGID (0.22 ± 0.03) than controls (0.07 ± 0.05; P = 0.007) and patients with UC (0.01 ± 0.05) or CD (0.02 ± 0.09), (P = 0.0001). While patients treated with proton pump inhibitors (PPI) had significantly higher bacterial loads than non‐users (P < 0.05), this did not explain differences between patient groups and controls. Bacterial load was significantly (r = 0.21, P < 0.016) associated with the symptom response to standardised nutrient challenge test. Methane, but not hydrogen values on glucose breath test were associated with bacterial load measured utilising qPCR. Conclusions: Utilising qPCR, a diagnosis of FGID and treatment with PPI were independently associated with increased bacterial loads. Increased bacterial loads are associated with an augmented symptom response to a standardised nutrient challenge. [ABSTRACT FROM AUTHOR]

Liver inflammation is a common extraintestinal manifestation in inflammatory bowel disease (IBD), yet, the mechanisms driving gut‐liver axis inflammation remain poorly understood. IBD leads to a breakdown in the integrity of the intestinal barrier causing an increase in portal and systemic gut‐derived antigens, which challenge the liver. Here, we examined the role of platelet activating factor receptor (PAFR) in colitis‐associated liver damage using dextran sulfate sodium (DSS) and anti‐CD40‐induced colitis models. Both DSS and anti‐CD40 models exhibited liver inflammation associated with colitis. Colitis reduced global PAFR protein expression in mouse livers causing an exclusive re‐localization of PAFR to the portal triad. The global decrease in liver PAFR was associated with increased sirtuin 1 while relocalized PAFR expression was limited to Kupffer cells (KCs) and co‐localized with toll‐like receptor 4. DSS activated the NLRP3‐inflammasome and increased interleukin (IL)‐1β in the liver. Antagonism of PAFR amplified the inflammasome response by increasing NLRP3, caspase‐1, and IL‐1β protein levels in the liver. LPS also increased NLRP3 response in human hepatocytes, however, overexpression of PAFR restored the levels of NLPR3 and caspase‐1 proteins. Interestingly, KCs depletion also increased IL‐1β protein in mouse liver after DSS challenge. These data suggest a protective role for PAFR‐expressing KCs during colitis and that regulation of PAFR is important for gut‐liver axis homeostasis. [ABSTRACT FROM AUTHOR]

Anastomotic leak rates have not improved over several decades despite improvements in surgical techniques and patient care. The gut microbiome has been implicated in the development of leaks. The exact mechanisms by which tissue oxygenation affects gut microbial composition and anastomotic healing physiology are unclear. Also, commonly used carbon dioxide (CO 2) is a known vasodilator that improves tissue oxygen tension. We performed a systematic review to determine the influence of hyperoxia, hypoxia, and hypercapnia on the gut microbiome and anastomotic healing. A literature search was performed in MEDLINE, EMBASE, and COCHRANE to identify studies investigating the effects of hyperoxia, hypoxia, and hypercapnia on anastomotic healing and gut microbiota published between 1998 and 2018. Two reviewers screened the articles for eligibility and quality. Fifty-three articles underwent full text review, and a narrative synthesis was undertaken. Hyperoxia is associated with better anastomotic healing, increased gastrointestinal oxygen tension, and may reduce gut anaerobes. Hypoxia is associated with poor healing and increased gut anaerobes. However, it is unclear if hypoxia is the most important predictor of anastomotic leaks. Low pressure CO 2 pneumoperitoneum and mild systemic hypercapnia are both associated with increased gastrointestinal oxygen tension and may improve anastomotic healing. We found no studies which investigated the effect of hypercapnia on gut microbiota in the context of anastomotic healing. Tissue oxygenation influences gut anastomotic healing, but little evidence exists to demonstrate the influence on the gut microbiome in the context of healing. Further studies are needed to determine if anastomotic microbiome changes with altered tissue oxygenation and if this affects healing and leak rates. If confirmed, altering tissue oxygenation through hyperoxia or hypercapnia could be feasible means of altering the microbiome such that anastomotic leak rates reduce. [ABSTRACT FROM AUTHOR]

Background: Glutathione S‐transferases omega class 1 (GSTO1‐1) is a unique member of the GST family regulating cellular redox metabolism and innate immunity through the promotion of LPS/TLR4/NLRP3 signalling in macrophages. House dust mite (HDM) triggers asthma by promoting type 2 responses and allergic inflammation via the TLR4 pathway. Although linked to asthma, the role of GSTO1‐1 in facilitating type 2 responses and/or HDM‐driven allergic inflammation is unknown. Objective: To determine the role of GSTO1‐1 in regulating HDM‐induced allergic inflammation in a preclinical model of asthma. Methods: Wild‐type and GSTO1‐1‐deficient mice were sensitized and aeroallergen challenged with HDM to induce allergic inflammation and subsequently hallmark pathophysiological features characterized. Results: By contrast to HDM‐challenged WT mice, exposed GSTO1‐1‐deficient mice had increased numbers of eosinophils and macrophages and elevated levels of eotaxin‐1 and ‐2 in their lungs. M1 macrophage‐associated factors, such as IL‐1β and IL‐6, were decreased in GSTO1‐1‐deficient mice. Conversely, M2 macrophage factors such as Arg‐1 and Ym1 were up‐regulated. HIF‐1α expression was found to be higher in the absence of GSTO1‐1 and correlated with the up‐regulation of M2 macrophage markers. Furthermore, HIF‐1α was shown to bind and activate the eotaxin‐2 promotor. Hypoxic conditions induced significant increases in the levels of eotaxin‐1 and ‐2 in GSTO1‐deficient BMDMs, providing a potential link between inflammation‐induced hypoxia and the regulation of M2 responses in the lung. Collectively, our results suggest that GSTO1‐1 deficiency promotes M2‐type responses and increased levels of nuclear HIF‐1α, which regulates eotaxin (s)‐induced eosinophilia and increased disease severity. Conclusion & Clinical Implication: We propose that GSTO1‐1 is a novel negative regulator of TLR4‐regulated M2 responses acting as an anti‐inflammatory pathway. The discovery of a novel HIF‐1α‐induced eotaxin pathway identifies an unknown connection between hypoxia and the regulation of the severity of allergic inflammation in asthma. [ABSTRACT FROM AUTHOR]

COPD is a seriously disabling respiratory condition that inexorably progresses to disability and mortality. It affects approximately 10% of the population globally with a greater prevalence at advanced ages. Airway bacterial infections complicate the disease course in most COPD patients, leading to increased symptoms, more rapid decline in lung function, acute exacerbations and reduced quality of life. With increasing bacterial resistance to antibiotics and adverse effects of conventional treatments, new effective non‐antibiotic antimicrobial therapies are urgently needed to manage COPD. Hypoxia‐inducible factor (HIF)‐1α is an important transcriptional regulator of cellular responses to hypoxia, oxidants and inflammation, and is overexpressed in the lungs of COPD patients. Recent evidence shows that increased HIF‐1α expression can upregulate the platelet‐activating factor receptor (PAFR) on the airway epithelial surface that is increased in smokers and particularly COPD patients. The receptor is utilized by PAFR‐dependent bacteria (Streptococcus pneumoniae, Haemophilus influenzae and Pseudomonas aeruginosa) to induce infection in both the respiratory and gastrointestinal (GI) tracts. However, the importance and mechanism of HIF‐1α in augmenting PAFR‐dependent bacterial infections in COPD are poorly understood. Here, we review the evidence for the roles of local tissue hypoxia‐induced inflammation, HIF‐1α and PAFR in facilitating bacterial infections in COPD. Blocking PAFR may provide a novel antimicrobial approach to manage bacterial infections in COPD. [ABSTRACT FROM AUTHOR]

The authors conducted a systematic review and meta-analysis to assess the effect of antibiotic therapy in primary sclerosing cholangitis (PSC). Effect of antibiotic therapy on Mayo PSC Risk Score (MRS), serum alkaline phosphatase (ALP), total serum bilirubin (TSB), and adverse events (AEs) rates were calculated and expressed as standardized difference of means or proportions. Five studies including 124 PSC patients who received antibiotics were included. Overall, antibiotic treatment was associated with a statistically significant reduction in ALP, MRS, and TSB by 33.2, 36.1, and 28.8%, respectively. ALP reduction was greatest for vancomycin (65.6%, p  < 0.002) and smallest with metronidazole (22.7%, p  = 0.18). Overall, 8.9% (95% confidence interval: 3.9–13.9) of patients had AEs severe enough to discontinue antibiotic therapy. In PSC patients, antibiotic treatment results in a significant improvement in markers of cholestasis and MRS. Antibiotics, particularly vancomycin, may have a positive effect on PSC either via direct effects on the microbiome or via host-mediated mechanisms. [ABSTRACT FROM AUTHOR]

Asthma is a common, heterogeneous and serious disease with high prevalence globally. Poorly controlled, steroid-resistant asthma is particularly important as there are no effective therapies and it exerts substantial healthcare and societal burden. The role of microbiomes, particularly in chronic diseases has generated considerable interest in recent times. Existing evidence clearly demonstrates an association between asthma initiation and the microbiome, both respiratory and gastro-intestinal, although its' roles are poorly understood when assessing the asthma progression or heterogeneity (i.e. phenotypes/endotypes) across different geographical locations. Moreover, modulating microbiomes could be preventive and/or therapeutic in patients with asthma warrants urgent attention. Here, we review recent advances in assessing the role of microbiomes in asthma and present the challenges associated with the potential therapeutic utility of modifying microbiomes in management. [ABSTRACT FROM AUTHOR]

Summary: Background: The pathogenesis of functional GI disorders (FGIDs) is uncertain. However, underlying immune activation and psychological distress has been documented in irritable bowel syndrome (IBS) and functional dyspepsia (FD). Epidemiological data from the UK suggest that FGIDs are linked to atopy and certain autoimmune diseases but this has not been confirmed. Aim: To test if allergic or autoimmune diseases are independently associated with FGIDs, irrespective of psychological distress in a large population based study. Methods: A total of 3542 people (mean age 57.9 years and 52.7% females) randomly selected from the Australian population, returned a mail survey (response rate = 43%). The survey asked about a physician diagnosis of autoimmune disease (scleroderma, psoriasis, rheumatoid arthritis and diabetes mellitus) or allergic conditions (asthma, food, pollen and/or animal allergy). The questionnaire assessed psychological distress and Rome III criteria for FD and IBS. Results: Asthma, food, pollen and animal allergies, psoriasis and rheumatoid arthritis were univariately significantly associated with IBS and FD. Food allergy (OR = 1.66; 95% CI = 1.15‐2.40, P = 0.007), psoriasis (OR = 1.81; 95% CI = 1.19‐2.74, P = 0.006) and rheumatoid arthritis (OR = 1.68; 95% CI = 1.15‐2.4, P = 0.007) were independent risk factors for IBS, controlling for age, gender and psychological distress. In FD, asthma (OR = 1.32; 95% CI = 1.04‐1.68, P = 0.025) and food allergy (OR = 1.78; 95% CI = 1.28‐2.49, P = 0.001) were independent predictors, controlling for age, sex and psychological distress. Conclusions: There is evidence that both atopic and autoimmune diseases are risk factors for FGIDs, independent of psychological distress, differing in IBS and FD. This provides evidence that different peripheral pathways may be involved in the pathogenesis of certain FGIDs. [ABSTRACT FROM AUTHOR]

OBJECTIVES: Wheat avoidance in the absence of celiac disease (CD) is common but occurrence of concurrent functional gastrointestinal disorders (FGIDs) in this group is uncertain. The aims of this study were to determine the prevalence of self-reported wheat or gluten sensitivity and doctor diagnosed CD in an Australian population, define the associated gastrointestinal (GI) symptoms and FGIDs, and determine the relationship between self-reported wheat sensitivity, demographic and medical factors.Methods: A total of 3542 people randomly selected from the Australian population returned a mail survey which contained questions on wheat avoidance, GI symptoms, demographic, medical, and lifestyle factors. We defined self-reported wheat sensitivity as people who reported gastrointestinal symptoms on ingestion of wheat based foods, but did not suffer from celiac disease, inflammatory bowel disease or colorectal cancer. Functional dyspepsia (FD) and irritable bowel syndrome (IBS) were diagnosed by Rome III criteria. CD status was self-reported.Results: The prevalence of self-reported wheat sensitivity in this cohort was 14.9% (95% CI 13.7-16.2). The prevalence of CD was 1.2% (95%CI 0.8-1.6). Doctor diagnosed CD was significantly associated with a diagnosis of FD (OR 3.35, 95%CI 1.72-6.52) and IBS (OR 2.28, 95%CI 1.08-4.81). Those with self-reported wheat sensitivity were more likely to report multiple abdominal symptoms (of the 18 assessed) than those without (3.9 symptoms with self-reported wheat sensitivity vs. 1.6 without, p = 0.0001). In a multivariate analysis, self-reported wheat sensitivity was independently associated with IBS (OR 3.55, 95%CI 2.71-4.65) and FD (1.48, 95%CI 1.13-1.94).Conclusions: Self-reported wheat sensitivity is common, with a prevalence of 14.9% in this cohort. There is a strong association between both celiac disease and self-reported wheat sensitivity, and chronic gastrointestinal symptoms, as well as a diagnosis of FD and IBS. [ABSTRACT FROM AUTHOR]

The intestinal epithelium constitutes an innate barrier which, upon injury, undergoes self-repair processes known as restitution. Although bile acids are known as important regulators of epithelial function in health and disease, their effects on wound healing processes are not yet clear. Here we set out to investigate the effects of the colonic bile acids, deoxycholic acid (DCA) and ursodeoxycholic acid (UDCA), on epithelial restitution. Wound healing in T84 cell monolayers grown on transparent, permeable supports was assessed over 48 h with or without bile acids. Cell migration was measured in Boyden chambers. mRNA and protein expression were measured by RT-PCR and Western blotting. DCA (50–150 µM) significantly inhibited wound closure in cultured epithelial monolayers and attenuated cell migration in Boyden chamber assays. DCA also induced nuclear accumulation of the farnesoid X receptor (FXR), whereas an FXR agonist, GW4064 (10 µM), inhibited wound closure. Both DCA and GW4064 attenuated the expression of CFTR Cl− channels, whereas inhibition of CFTR activity with either CFTR-inh-172 (10 µM) or GlyH-101 (25 µM) also prevented wound healing. Promoter/reporter assays revealed that FXR-induced downregulation of CFTR is mediated at the transcriptional level. In contrast, UDCA (50–150 µM) enhanced wound healing in vitro and prevented the effects of DCA. Finally, DCA inhibited and UDCA promoted mucosal healing in an in vivo mouse model. In conclusion, these studies suggest bile acids are important regulators of epithelial wound healing and are therefore good targets for development of new drugs to modulate intestinal barrier function in disease treatment. NEW & NOTEWORTHY The secondary bile acid, deoxycholic acid, inhibits colonic epithelial wound healing, an effect which appears to be mediated by activation of the nuclear bile acid receptor, FXR, with subsequent downregulation of CFTR expression and activity. In contrast, ursodeoxycholic acid promotes wound healing, suggesting it may provide an alternative approach to prevent the losses of barrier function that are associated with mucosal inflammation in IBD patients. [ABSTRACT FROM AUTHOR]

Inflammatory bowel diseases (IBD) comprise a group of common and debilitating chronic intestinal disorders for which currently available therapies are often unsatisfactory. The naturally occurring secondary bile acid, ursodeoxycholic acid (UDCA), has well-established anti-inflammatory and cytoprotective actions and may therefore be effective in treating IBD. We aimed to investigate regulation of colonic inflammatory responses by UDCA and to determine the potential impact of bacterial metabolism on its therapeutic actions. The anti-inflammatory efficacy of UDCA, a nonmetabolizable analog, 6α-methyl-UDCA (6-MUDCA), and its primary colonic metabolite lithocholic acid (LCA) was assessed in the murine dextran sodium sulfate (DSS) model of mucosal injury. The effects of bile acids on cytokine (TNF-α, IL-6, Il-1β, and IFN-γ) release from cultured colonic epithelial cells and mouse colonic tissue in vivo were investigated. Luminal bile acids were measured by gas chromatography-mass spectrometry. UDCA attenuated release of proinflammatory cytokines from colonic epithelial cells in vitro and was protective against the development of colonic inflammation in vivo. In contrast, although 6-MUDCA mimicked the effects of UDCA on epithelial cytokine release in vitro, it was ineffective in preventing inflammation in the DSS model. In UDCA-treated mice, LCA became the most common colonic bile acid. Finally, LCA treatment more potently inhibited epithelial cytokine release and protected against DSS-induced mucosal inflammation than did UDCA. These studies identify a new role for the primary metabolite of UDCA, LCA, in preventing colonic inflammation and suggest that microbial metabolism of UDCA is necessary for the full expression of its protective actions. [ABSTRACT FROM AUTHOR]

R4272 --> 865.5 --> Background: Emerging evidence suggests there is a specific duodenal mucosal associated microbiota (MAM) signature for functional dyspepsia (FD), although study numbers are low and consensus on biomarkers have not been reached. Additionally, we now know that FD is associated with high duodenal eosinophil counts and this site‐specific immune response is likely interacting or responding to the MAM. As duodenal biopsies for research can be difficult to obtain, we investigated formalin‐fixed paraffin‐embedded (FFPE) biopsies, routinely collected for pathology, to sequence the MAM and compared them to the MAM profiles of matched RNAlater preserved biopsies. Methods: Duodenal biopsies (n=4) stored in RNAlater were homogenized for 3 mins at 5,0000 rpm using the Precellys 24 homogenizer after removal from RNAlater solution. The total DNA was then extracted and purified with the Promega Maxwell automated DNA recovery system following manufacturer's instructions. DNA from matched FFPE sections (40 µm) were extracted with Qiagen deparaffinization solution and FFPE DNA extraction kit following manufacturer's instructions. 16S amplicon sequencing was completed targeting the V6‐V8 region. Reads were processed with QIIME2/DADA2 and referenced against the SILVA SSU r138 database. Analysis of microbiota diversity was performed in R packages and Calypso (http://cgenome.net). Data was transformed using Cumulative Sum Scaling + log2. Results: The mean sequencing depth of RNAlater biopsies was 4115 and FFPE was 20170. The alpha diversity was significantly greater for FFPE sequenced samples when compared to whole biopsies (Chao1 P=0.029, Figure 1). Additionally, RDA multivariate analysis demonstrated significant clustering (P=0.024) of FFPE communities compared to the patient matched whole biopsy extracts. Permutational multivariate analysis of variance (adonis function) and ANOSIM Bray‐Curtis were also both significant when comparing the MAM of each extraction type (P=0.0297 and 0.023 (R =1), respectively). There were also fewer "unknown" taxonomic assignments for FFPE samples compared to the matched biopsies. Conclusions: Here we have shown that MAM 16S sequencing from FFPE tissue sections (tested 2‐4yrs old) is a viable option and means that single biopsies can be multi‐functional (histopathology and viable DNA recovery). The viability of MAM sequence amplification from FFPE provides a tantalising opportunity as the historical catalogue of samples where there were previously no specific biopsies collected for microbial analysis is extensive and would substantially contribute to the integration of FD associated MAM profiles. [ABSTRACT FROM AUTHOR]

R4338 --> 865.6 --> Background: There is comorbidity between anxiety disorders and gastrointestinal disorders, with both linked to adverse early life events. The microbiome gut‐brain‐axis (MGBA), a bidirectional communication system, is plastic throughout the neonatal period and we hypothesised that disruption of the MGBA development through inflammation and infection mediates this relationship. Here, we used a well‐established neonatal rodent immune activation model to investigate the long‐term effect of neonatal lipopolysaccharide (LPS) exposure on adult behaviour and the relationship to microbiome composition. Methods: Wistar rats were injected with LPS (0.05mg/kg) or saline (equivolume) on postnatal days 3 and 5. In adulthood, behavioural tests were performed to assess anxiety‐like behaviour, and microbiota sequencing was performed on stool samples. Results: There were distinctly different behavioural phenotypes for LPS‐exposed males and females. LPS‐exposed males displayed typical anxiety‐like behaviours with significantly decreased social interaction and increased defecation relative to controls. LPS‐exposed females displayed a different behavioural phenotype with significantly increased social interaction and exploration compared to controls. With respect to microbiota profiling data, there were distinct beta diversity clusters for each group which were distinct for each sex. Bacteroidota was significantly increased for LPS‐exposed females and Proteobacteria was decreased for LPS‐exposed rats of both sexes versus controls. Additionally, alterations in predicted functional pathways for neurotransmitters were observed based on LPS‐ exposure and sex. A significant decrease in the relative abundance of D‐glutamine and D‐glutamate metabolism was found in LPS exposed females compared to control females, while no change was observed in males. Conclusions: These results indicate that neonatal immune activation alters both adult behaviour and microbiota communities in sex‐specific ways. These findings highlight the importance of sex in determining the impact of early life immune activation events on the development of anxiety‐like behaviours and suggests a potential moderating effect of the gut brain axis. These findings may begin to explain the underlying biology to sex prevalence in anxiety disorders and disorders of the gut. [ABSTRACT FROM AUTHOR]

R4289 --> 867.3 --> BACKGROUND: Human colonic spirochetosis (CS) is an infection caused by the Brachyspira genus. Although Brachyspira have been considered commensal, recent evidence suggests they are associated with low grade inflammation and irritable bowel syndrome. Increased eosinophils, mast cells and lymphocyte aggregates have been reported in CS, however, little is known about immune cell localization. We hypotheses that CS infection is associated with a distinct mucosal immune signature and we aim to characterize the distribution of these immune cells during spirochete infection. METHOD: Paraffin‐embedded colonic biopsy samples from 20 CS patients (mean age 45.7, 70% male), 20 age/sex‐matched control patients (mean age 45.6, 70% male) without CS, and 13 healthy controls (mean age 39.8, 31% male) were examined. CS positive and negative areas of CS patient biopsies were identified by Treponema pallidum IHC staining. Intra‐epithelial lymphocyte (IEL) was identified by H&E staining, eosinophil was identified by congo‐red staining, mast cell was identified by CD117 IHC staining. Tissue sections were visualised using Aperio AT2 digital scanner. Peak numbers of eosinophil and mast cell were counted in 3 fields of intra‐epithelial and lamina propria area. RESULTS: Intra‐epithelial eosinophils and mast cells were significantly higher in CS patients compared to matched controls (p=0.043, p=0.022) and healthy controls (p=0.023, p=0.032) Lamina propria mast cells were significantly higher in CS patients compared to matched controls (p=0.009) and healthy controls (p=0.004). In addition, IELs were significantly higher in CS patients compared to matched controls (p=0.002) and healthy controls (p<0.0001). Upon examining the localisation of these immune cells we found that, CS positive areas of CS patient biopsies had significantly higher intra‐epithelial eosinophils, compared to healthy controls (p=0.049), but not matched controls, or CS negative areas of CS patient biopsies. For intra‐epithelial mast cells, there were no differences between CS positive areas and CS negative areas compared to healthy controls, while CS negative areas had significantly higher intra‐epithelial mast cells compared to matched controls (p=0.009). Lamina propria mast cells were significantly higher in CS positive and negative areas compared to matched controls (CS+ p=0.02, CS‐ p=0.03) and healthy controls (CS+ p=0.01, CS‐ p=0.01), while there were no differences between these areas. Finally, IELs were significantly higher in CS positive areas compared with CS negative areas (p=0.0171), while there were no differences between CS negative areas, matched and healthy controls. CONCLUSION: Increased IELs are associated with spirochete positive areas, suggests that IELs actively respond to spirochete infection. Increased intra‐epithelial eosinophils and mast cells in CS patients compared to controls suggests that these cells actively migrate towards spirochetes colonizing the mucosal epithelium. These data suggest that intestinal spirochetes provoke mucosal immune responses and may be an underappreciated intestinal pathogen. [ABSTRACT FROM AUTHOR]

Resolvin-El (RvE1) has been demonstrated to promote inflammatory resolution in numerous disease models. Given the importance of epithelial cells to coordination of mucosal inflammation, we hypothesized that RvE1 elicits an epithelial resolution signature. Initial studies revealed that the RvE1-receptor (ChemR23) is expressed on intestinal epithelial cells (IECs) and that microarray profiling of cells exposed to RvE1 revealed regulation of inflammatory response gene expression. Notably, RvE1 induced intestinal alkaline phosphatase (ALPI) expression and significantly enhanced epithelial ALPI enzyme activity. One role recently attributed to ALPI is the detoxification of bacterial LPS. In our studies, RvE1-exposed epithelia detoxified LPS (assessed by attenuation of NF-κB signaling). Further- more, in epithelial-bacterial interaction assays, we determined that ALPI retarded the growth of Escherichia coli. To define these features in vivo, we used a murine dextran sulfate sodium (DS5) model of colitis. Compared with vehicle controls, administration of RvE1 resulted in significant improvement of disease activity indices (e.g., body weight, colon length) concomitant with increased ALPI expression in the intestinal epithelium. Moreover, inhibition of ALPI activity resulted in increased severity of colitis in DSS-treated animals and partially abrogated the protective influence of RvE1. Together, these data implicate a previously unappreciated role for ALPI in RvE1-mediated inflammatory resolution. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of 3-, 5- and 8-arm dimethylaminoethyl methacrylate star polymers are reported, final M n (PDI)=12.2K (1.09), 18.9K (1.10) and 38.4K (1.11), respectively. The synthesis of 3-arm methyl methacrylate and dimethylaminoethyl methacrylate block co-polymer stars is also described. Living polymerisation occurred in all cases providing well defined stars with predictable molecular weights and narrow polydispersity. A fluorescent tag, 2-(8-methacryloyloy-3,6-dioxaoctyl)thioxantheno[2,1,9-dej]isoquinoline-1,3-dione, derived from a commercially available pigment, was incorporated into the star polymers. The fluorescence spectra of the polymers prepared were recorded over a range of pH and the peak emission frequency and intensity have been reported, λ ex =462nm. All of the multi-arm polymers exhibit fluorescence across a broad pH range with maximum emission at pH 4. A 3-arm star polymer has been demonstrated to show good bioadhesion in rat tissue. A reduced adhesion in epithelial tissues not covered by a viscoelastic mucus gel indicates an increased tendency for mucoadhesion over bioadhesion. [Copyright &y& Elsevier]

Linked Content This article is linked to McIlroy et al paper. To view these article visit https://doi.org/10.1111/apt.14384. [ABSTRACT FROM AUTHOR]