Tissue metabolism and host-microbial interactions in the intestinal mucosa

Hypoxic Functional Regulation Pathways in the GI Tract: Focus on the HIF-1α and Microbiota's Crosstalk

Hypoxia is an essential gastrointestinal (GI) tract phenomenon that influences both physiologic and pathologic states. Hypoxia-inducible factors (HIFs), the primary drivers of cell adaptation to low-oxygen environments, have been identified as critical regulators of gut homeostasis: directly, through the induction of different proteins linked to intestinal barrier stabilization (ie, adherent proteins, tight junctions, mucins, integrins, intestinal trefoil factor, and adenosine); and indirectly, through the regulation of several immune cell types and the modulation of autophagy and inflammatory processes. Furthermore, hypoxia and HIF-related sensing pathways influence the delicate relationship existing between bacteria and mammalian host cells. In turn, gut commensals establish and maintain the physiologic hypoxia of the GI tract and HIF-α expression. Based on this premise, the goals of this review are to (1) highlight hypoxic molecular pathways in the GI tract, both in physiologic and pathophysiologic settings, such as inflammatory bowel disease; and (2) discuss a potential strategy for ameliorating gut-related disorders, by targeting HIF signaling, which can alleviate inflammatory processes, restore autophagy correct mechanisms, and benefit the host-microbiota equilibrium.

Pharmacological benefits of Acacia against metabolic diseases: intestinal-level bioactivities and favorable modulation of gut microbiota

CONTEXT

Obesity-associated chronic metabolic disease is a leading contributor to mortality globally. Plants belonging to the genera Acacia are routinely used for the treatment of diverse metabolic diseases under different ethnomedicinal practices around the globe.

OBJECTIVE

The current review centres around the pharmacological evidence of intestinal-level mechanisms for metabolic health benefits by Acacia spp.

RESULTS

Acacia spp. increase the proportions of gut commensals (Bifidobacterium and Lactobacillus) and reduces the population of opportunistic pathobionts (Escherichia coli and Clostridium). Acacia gum that is rich in fibre, can also be a source of prebiotics to improve gut health. The intestinal-level anti-inflammatory activities of Acacia are likely to contribute to improvements in gut barrier function that would prevent gut-to-systemic endotoxin translocation and limit "low-grade" inflammation associated with metabolic diseases.

CONCLUSION

This comprehensive review for the first time has emphasised the intestinal-level benefits of Acacia spp. which could be instrumental in limiting the burden of metabolic disease.

Effects of grain-based diets on the rumen and fecal bacterial communities of the North American bison (Bison bison)

To overcome the challenges of pasture-finishing of bison, producers commonly feed them with higher energy, grain-based diets to reach the desired market weight. However, decades of research on domesticated ruminants have shown that such diets can have profound effects on the composition of gut microbial communities. To gain further insight, the 16S rRNA gene-based study described in this report aimed to compare the composition of ruminal and fecal bacterial communities from two herds of bison heifers (n = 20/herd) raised on different ranches that were both transitioned from native pasture to a grain-based, free-choice diet for ~100 days prior to slaughter. Comparative analyses of operational taxonomic unit (OTU) composition, either by alpha diversity indices, principal coordinate analysis (PCoA), or on the most abundant individual OTUs, showed the dramatic effect of a diet on the composition of both rumen and fecal bacterial communities in bison. Indeed, feeding a grain-based diet resulted in a lower number of rumen and fecal bacterial OTUs, respectively, compared to grazing on pasture (p < 0.05). PCoA revealed that the composition of the rumen and fecal bacterial communities from the two herds was more similar when they were grazing on native pastures compared to when they were fed a grain-based, free-choice diet. Finally, a comparative analysis of the 20 most abundant OTUs from the rumen and fecal communities further showed that the representation of all these species-level bacterial groups differed (p < 0.05) between the two dietary treatments. Together, these results provide further insights into the rumen and fecal microbiomes of grazing bison and their response to grain-based diet regimens commonly used in intensive ruminant production systems.

Role of hyperbaric oxygen therapy in patients with inflammatory bowel disease

PURPOSE OF REVIEW

Hypoxia is a known contributor to inflammation in inflammatory bowel diseases (IBD), and a growing interest has emerged in pharmacologically targeting hypoxia response pathways to treat IBD. The most basic form of treatment for hypoxia is delivering higher amounts of oxygen to the intestinal mucosa. In this review, we summarize the evidence in support of hyperbaric oxygen therapy (HBOT), a mechanism to deliver high amounts of oxygen to tissue, for treating IBD.

RECENT FINDINGS

Two phase 2 clinical trials in hospitalized ulcerative colitis patients suffering from moderate-to-severe flares have demonstrated that HBOT improves responsiveness to steroids and avoidance of rescue medical and surgical therapy. Outpatient cohort studies in perianal fistulizing Crohn's disease and fistulizing complications of the pouch have demonstrated improved healing, particularly for complex fistulae. Several systematic reviews have now been completed, and HBOT has been observed to be well tolerated with low rates of adverse events.

SUMMARY

HBOT may be considered as an adjunctive treatment for hospitalized ulcerative colitis flares and Crohn's disease-related fistulae. Higher quality trials are needed to confirm efficacy.

Hypoxia-inducible factor as a bridge between healthy barrier function, wound healing, and fibrosis

The healthy mammalian intestine is lined by a single layer of epithelial cells. These cells provide a selectively permeable barrier to luminal contents and normally do so in an efficient and effective manner. Barrier function in the healthy mucosa is provided via several mechanisms including epithelial junctional complexes, mucus production, as well as mucosal-derived antimicrobial proteins. As tissue metabolism is central to the maintenance of homeostasis in the mucosa, intestinal [Formula: see text] levels are uniquely low due to counter-current blood flow and the presence of the microbiota, resulting in the stabilization of the transcription factor hypoxia-inducible factor (HIF). Ongoing studies have revealed that HIF molds normal intestinal metabolism and is central to the coordination of barrier regulation during both homeostasis and active disease. During acute inflammation, HIF is central to controlling the rapid restitution of the epithelium consistent with normal wound healing responses. In contrast, HIF may also contribute to the fibrostenotic response associated with chronic, nonresolving inflammation. As such, HIF may function as a double-edged sword in the overall course of the inflammatory response. Here, we review recent literature on the contribution of HIF to mucosal barrier function, wound healing, and fibrosis.

Nitric oxide stimulates type IV MSHA pilus retraction in Vibrio cholerae via activation of the phosphodiesterase CdpA

All organisms sense and respond to their environments. One way bacteria interact with their surroundings is by dynamically extending and retracting filamentous appendages from their surface called pili. While pili are critical for many functions, such as attachment, motility, and DNA uptake, the factors that regulate their dynamic activity are poorly understood. Here, we describe how an environmental signal induces a signaling pathway to promote the retraction of mannose-sensitive hemagglutinin pili in Vibrio cholerae. The retraction of these pili promotes the detachment of V. cholerae from a surface and may provide a means by which V. cholerae can respond to changes in its environment.

Bacteria use surface appendages called type IV pili to perform diverse activities including DNA uptake, twitching motility, and attachment to surfaces. The dynamic extension and retraction of pili are often required for these activities, but the stimuli that regulate these dynamics remain poorly characterized. To address this question, we study the bacterial pathogen Vibrio cholerae, which uses mannose-sensitive hemagglutinin (MSHA) pili to attach to surfaces in aquatic environments as the first step in biofilm formation. Here, we use a combination of genetic and cell biological approaches to describe a regulatory pathway that allows V. cholerae to rapidly abort biofilm formation. Specifically, we show that V. cholerae cells retract MSHA pili and detach from a surface in a diffusion-limited, enclosed environment. This response is dependent on the phosphodiesterase CdpA, which decreases intracellular levels of cyclic-di-GMP to induce MSHA pilus retraction. CdpA contains a putative nitric oxide (NO)–sensing NosP domain, and we demonstrate that NO is necessary and sufficient to stimulate CdpA-dependent detachment. Thus, we hypothesize that the endogenous production of NO (or an NO-like molecule) in V. cholerae stimulates the retraction of MSHA pili. These results extend our understanding of how environmental cues can be integrated into the complex regulatory pathways that control pilus dynamic activity and attachment in bacterial species.

The intestinal 3M (microbiota, metabolism, metabolome) zeitgeist - from fundamentals to future challenges

The role of the intestine in human health and disease has historically been neglected and was mostly attributed to digestive and absorptive functions. In the past two decades, however, discoveries related to human nutrition and intestinal host-microbe reciprocal interaction have established the essential role of intestinal health in the pathogenesis of chronic diseases and the overall wellbeing. That transfer of gut microbiota could be a means of disease phenotype transfer has revolutionized our understanding of chronic disease pathogenesis. This narrative review highlights the major concepts related to intestinal microbiota, metabolism, and metabolome (3M) that have facilitated our fundamental understanding of the association between the intestine, and human health and disease. In line with increased interest of microbiota-dependent modulation of human health by dietary phytochemicals, we have also discussed the emerging concepts beyond the phytochemical bioactivities which emphasizes the integral role of microbial metabolites of parent phytochemicals at extraintestinal tissues. Finally, this review concludes with challenges and future prospects in defining the 3M interactions and has emphasized the fact that, it takes 'guts' to stay healthy.

Regulation of Oxygen Homeostasis at the Intestinal Epithelial Barrier Site

The unique biology of the intestinal epithelial barrier is linked to a low baseline oxygen pressure (pO₂), characterised by a high rate of metabolites circulating through the intestinal blood and the presence of a steep oxygen gradient across the epithelial surface. These characteristics require tight regulation of oxygen homeostasis, achieved in part by hypoxia-inducible factor (HIF)-dependent signalling. Furthermore, intestinal epithelial cells (IEC) possess metabolic identities that are reflected in changes in mitochondrial function. In recent years, it has become widely accepted that oxygen metabolism is key to homeostasis at the mucosae. In addition, the gut has a vast and diverse microbial population, the microbiota. Microbiome–gut communication represents a dynamic exchange of mediators produced by bacterial and intestinal metabolism. The microbiome contributes to the maintenance of the hypoxic environment, which is critical for nutrient absorption, intestinal barrier function, and innate and/or adaptive immune responses in the gastrointestinal tract. In this review, we focus on oxygen homeostasis at the epithelial barrier site, how it is regulated by hypoxia and the microbiome, and how oxygen homeostasis at the epithelium is regulated in health and disease.

Gut microbiota variations in patients diagnosed with major depressive disorder-A systematic review

OBJECTIVE

The etiology of major depressive disorder (MDD) is multi-factorial and has been associated with a perturbed gut microbiota. Thus, it is therefore of great importance to determine any variations in gut microbiota in patients with MDD.

METHODS

A systematic literature search was conducted including original research articles based on gut microbiota studies performed in patients with MDD. Demographic and clinical characteristics, applied methodology and observed gut microbiota composition were compared between included studies.

RESULTS

Seventeen studies were included with a total of 738 patients with MDD and 782 healthy controls using different DNA purification methods, sequencing platforms and data analysis models. Four studies found a reduced α-diversity in patients with MDD, while gut microbiota compositions clustered separately according to β-diversity between patients and controls in twelve studies. Additionally, there was an increase in relative abundance of Eggerthella, Atopobium, and Bifidobacterium and a decreased relative abundance of Faecalibacterium in patients with MDD compared with healthy controls.

CONCLUSION

Gut microbiota differs significantly when comparing patients with MDD and healthy controls, though inconsistently across studies. The heterogeneity in gut microbiota compositions between the studies may be explained by variations in study design.

Investigating the Effects of a Phytobiotics-Based Product on the Fecal Bacterial Microbiome of Weaned Pigs

The transition to a solid diet, as well as environmental and social stress, have a direct impact on swine gut physiology during weaning, affecting host gastrointestinal functions, as well as resident symbiotic microbial communities. While plant-derived bioactive products, such as phytobiotics, have shown great potential to mitigate these challenges, providing benefits such as antimicrobial, antioxidant, and anti-inflammatory activities, their mechanisms of action remain largely unexplored. To gain more insight, a 21 day trial is conducted to investigate the effects of LiveXtract, a commercial plant-based product, using fecal samples as a proxy for gut bacteria in weaned pigs. High-throughput sequencing of amplicons targeting the V1-V3 region of the 16S rRNA gene is used to determine bacterial composition at days 1 (pre-treatment), 4, 10, and 21 postweaning. Our results show that Lactobacillaceae and Peptostreptococcaceae are both higher in the supplemented group at D4 (p < 0.05), while Streptococcaceae are significantly lower in the treated group at D10 and D21. At D10, Erysipelotrichaceae are lower, and Veillonellaceae are higher in the treated samples than the control group (p < 0.05). Of the thirteen abundant Operational Taxonomic Units (OTUs) that have different representation between treated and control pigs (p < 0.05), six are predicted to be lactate producers (affiliation to Lactobacillus or Streptococcus), and one is predicted to be a lactate utilizer, based on its high identity to Megasphaera elsdenii. Together, these data suggest that phytobiotics may provide a favorable metabolic equilibrium between lactate production and utilization. Lactate is considered a critical microbial end product in gut environments, as it can inhibit pathogens or be metabolized to propionate for utilization by host cells.

Therapeutic Opportunities for Intestinal Angioectasia- Targeting PPARγ and Oxidative Stress

Recurrent and acute bleeding from intestinal tract angioectasia (AEC) presents a major challenge for clinical intervention. Current treatments are empiric, with frequent poor clinical outcomes. Improvements in understanding the pathophysiology of these lesions will help guide treatment. Using data from the US Food and Drug Administration (FDA)'s Adverse Event Reporting System (FAERS), we analyzed 12 million patient reports to identify drugs inversely correlated with gastrointestinal bleeding and potentially limiting AEC severity. FAERS analysis revealed that drugs used in patients with diabetes and those targeting PPARγ-related mechanisms were associated with decreased AEC phenotypes (P < 0.0001). Electronic health records (EHRs) at University of Cincinnati Hospital were analyzed to validate FAERS analysis. EHR data showed a 5.6% decrease in risk of AEC and associated phenotypes in patients on PPARγ agonists. Murine knockout models of AEC phenotypes were used to construct a gene-regulatory network of candidate drug targets and pathways, which revealed that wound healing, vasculature development and regulation of oxidative stress were impacted in AEC pathophysiology. Human colonic tissue was examined for expression differences across key pathway proteins, PPARγ, HIF1α, VEGF, and TGFβ1. In vitro analysis of human AEC tissues showed lower expression of PPARγ and TGFβ1 compared with controls (0.55 ± 0.07 and 0.49 ± 0.05). National Center for Biotechnology Information (NCBI) Gene Expression Omnibus (GEO) RNA-Seq data was analyzed to substantiate human tissue findings. This integrative discovery approach showing altered expression of key genes involved in oxidative stress and injury repair mechanisms presents novel insight into AEC etiology, which will improve targeted mechanistic studies and more optimal medical therapy for AEC.

Targeting gut barrier dysfunction with phytotherapies: Effective strategy against chronic diseases

The intestinal epithelial layer serves as a physical and functional barrier between the microbe-rich lumen and immunologically active submucosa; it prevents systemic translocation of microbial pyrogenic products (e.g. endotoxin) that elicits immune activation upon translocation to the systemic circulation. Loss of barrier function has been associated with chronic 'low-grade' systemic inflammation which underlies pathogenesis of numerous no-communicable chronic inflammatory disease. Thus, targeting gut barrier dysfunction is an effective strategy for the prevention and/or treatment of chronic disease. This review intends to emphasize on the beneficial effects of herbal formulations, phytochemicals and traditional phytomedicines in attenuating intestinal barrier dysfunction. It also aims to provide a comprehensive understanding of intestinal-level events leading to a 'leaky-gut' and systemic complications mediated by endotoxemia. Additionally, a variety of detectable markers and diagnostic criteria utilized to evaluate barrier improving capacities of experimental therapeutics has been discussed. Collectively, this review provides rationale for targeting gut barrier dysfunction by phytotherapies for treating chronic diseases that are associated with endotoxemia-induced systemic inflammation.

Adaptation of Vibrio cholerae to Hypoxic Environments

Bacteria can colonize virtually any environment on Earth due to their remarkable capacity to detect and respond quickly and adequately to environmental stressors. Vibrio cholerae is a cosmopolitan bacterium that inhabits a vast range of environments. The V. cholerae life cycle comprises diverse environmental and infective stages. The bacterium is found in aquatic ecosystems both under free-living conditions or associated with a wide range of aquatic organisms, and some strains are also capable of causing epidemics in humans. In order to adapt between environments, V. cholerae possesses a versatile metabolism characterized by the rapid cross-regulation of energy-producing pathways. Low oxygen concentration is a key environmental factor that governs V. cholerae physiology. This article reviews the metabolic plasticity that enables V. cholerae to thrive on low oxygen concentrations and its role in environmental and host adaptation.

Gut microbiota in phytopharmacology: A comprehensive overview of concepts, reciprocal interactions, biotransformations and mode of actions

The dynamic and delicate interactions amongst intestinal microbiota, metabolome and metabolism dictates human health and disease. In recent years, our understanding of gut microbial regulation of intestinal immunometabolic and redox homeostasis have evolved mainly out of in vivo studies associated with high-fat feeding induced metabolic diseases. Techniques utilizing fecal transplantation and germ-free mice have been instrumental in reproducibly demonstrating how the gut microbiota affects disease pathogenesis. However, the pillars of modern drug discovery i.e. evidence-based pharmacological studies critically lack focus on intestinal microflora. This is primarily due to targeted in vitro molecular-approaches at cellular-level that largely overlook the etiology of disease pathogenesis from the physiological perspective. Thus, this review aims to provide a comprehensive understanding of the key notions of intestinal microbiota and dysbiosis, and highlight the microbiota-phytochemical bidirectional interactions that affects bioavailability and bioactivity of parent phytochemicals and their metabolites. Potentially by focusing on the three major aspects of gut microbiota i.e. microbial abundance, diversity, and functions, I will discuss phytochemical-microbiota reciprocal interactions, biotransformation of phytochemicals and plant-derived drugs, and pre-clinical and clinical efficacies of herbal medicine on dysbiosis. Additionally, in relation to phytochemical pharmacology, I will briefly discuss the role of dietary-patterns associated with changes in microbial profiles and review pharmacological study models considering possible microbial effects. This review therefore, emphasize on the timely and critically needed evidence-based phytochemical studies focusing on gut microbiota and will provide newer insights for future pre-clinical and clinical phytopharmacological interventions.

Green tea extract prevents obesity in male mice by alleviating gut dysbiosis in association with improved intestinal barrier function that limits endotoxin translocation and adipose inflammation

Gut-derived endotoxin translocation provokes obesity by inducing TLR4/NFκB inflammation. We hypothesized that catechin-rich green tea extract (GTE) would protect against obesity-associated TLR4/NFκB inflammation by alleviating gut dysbiosis and limiting endotoxin translocation. Male C57BL/6J mice were fed a low-fat (LF) or high-fat (HF) diet containing 0% or 2% GTE for 8 weeks. At Week 7, fluorescein isothiocyanate (FITC)-dextran was administered by oral gavage before assessing its serum concentrations as a gut permeability marker. HF-feeding increased (P<.05) adipose mass and adipose expression of genes involved in TLR4/NFκB-dependent inflammation and macrophage activation. GTE attenuated HF-induced obesity and pro-inflammatory gene expression. GTE in HF mice decreased serum FITC-dextran, and attenuated portal vein and circulating endotoxin concentrations. GTE in HF mice also prevented HF-induced decreases in the expression of intestinal tight junction proteins (TJPs) and hypoxia inducible factor-1α while preventing increases in TLR4/NFκB-dependent inflammatory genes. Gut microbial diversity was increased, and the Firmicutes:Bacteroidetes ratio was decreased, in HF mice fed GTE compared with HF controls. GTE in LF mice did not attenuate adiposity but decreased endotoxin and favorably altered several gut bacterial populations. Serum FITC-dextran was correlated with portal vein endotoxin (P<.001; r_P=0.66) and inversely correlated with colonic mRNA levels of TJPs (P<.05; r_P=-0.38 to -0.48). Colonic TJPs mRNA were inversely correlated with portal endotoxin (P<.05; r_P=-0.33 to -0.39). These data suggest that GTE protects against diet-induced obesity consistent with a mechanism involving the gut-adipose axis that limits endotoxin translocation and consequent adipose TLR4/NFκB inflammation by improving gut barrier function.

Probiotics and sports: A new magic bullet?

The use of probiotics in sports has been growing in the past years focusing on the attenuation of upper respiratory tract (URS) and gastrointestinal (GI) symptoms commonly present in endurance athletes. Researches shown different results and this may related to the probiotic strain, dose, period consumption or even the form of administration (capsules, sachets or fermented milk). These four factors directly influence in the probiotic's outcome and this question still remains unclear. Thus, the goal of this review is to clarify how these factors may influence the outcomes, approaching the major differences among studies, mechanisms by which the probiotic may contribute in sports field and applied conclusions. It was used 'probiotics', 'athletes', 'sports', 'exercise', 'athletes performance', 'immune response', 'intestinal symptoms' as keywords and its combinations and 20 original articles were selected for our purpose. All the articles were performed in healthy physically active people and/or athletes. Putting together, it was observed that athletes may benefit from probiotics consumption. It seems that multi strain ingested via sachet or fermented food and a larger period of consumption may shown better results at minimizing URS and GI symptoms. Also, specific species appears to have a role in exercise recovery. Therefore, the beneficial effect of probiotics in sports field is strictly dependent on the four factors abovementioned. The molecular mechanisms behind the probiotics effectiveness have not yet been elucidated and perhaps the biological assessments performed in the studies as well the few number of studies published did not answer the question yet.

Dietary Nondigestible Polysaccharides Ameliorate Colitis by Improving Gut Microbiota and CD4+ Differentiation, as Well as Facilitating M2 Macrophage Polarization

BACKGROUND

The aim of this study was to investigate the therapeutic mechanism of a specific multifiber mix diet (MF) designed to match the fiber content of a healthy diet in interleukin-10 knockout (IL-10^-/- ) mice with spontaneous chronic colitis displaying similar characteristics to those of human Crohn's disease (CD).

METHODS

Sixteen-week-old IL-10^-/- mice were used for the experiments with MF diet for 4 weeks. Severity of colitis, the composition of the fecal microbiota, expression of Th1/Th17 cells, myeloperoxidase (MPO) concentrations, and inflammatory cytokines and chemokines (tumor necrosis factor-α [TNF-α], IL-6, macrophage inflammatory protein [MIP]-2, monocyte chemoattractant protein-1 [MCP-1], and MIP-1α), as well as arginase 1 (Arg1) and signal transducers and activators of transcription 6 (STAT6) proteins, were measured at the end of the experiment. In addition, the corresponding metabolites (short-chain fatty acids) of MF on CD4⁺ CD25⁺ Foxp3⁺ regulatory T cells (Tregs) were also detected in vivo and in vitro.

RESULTS

MF treatment significantly ameliorated colitis associated with decreased lamina propria frequency of Th1/Th17 cells, MPO concentrations, and inflammatory cytokines and chemokines (TNF-α, IL-6, MIP-2, MCP-1, and MIP-1α). An increase in gut microbial diversity was observed after MF treatment compared with IL-10^-/- mice, including a significant increase in bacteria belonging to the Firmicutes phylum and a significant decrease in bacteria belonging to the Proteobacteria phylum. Moreover, MF treatment increased the differentiation of CD4⁺ CD25⁺ Foxp3⁺ Tregs mainly by microbial metabolites butyrate. In addition, Arg1 and STAT6 proteins were also significantly increased after MF treatment.

CONCLUSIONS

These results shed light on the contribution of MF treatment to the CD mouse model and suggest that MF has potential as a therapeutic strategy for enhancing efficacy in inducing remission in patients with active CD.

Hyperbaric oxygen therapy is well tolerated and effective for ulcerative colitis patients hospitalized for moderate-severe flares: a phase 2A pilot multi-center, randomized, double-blind, sham-controlled trial

BACKGROUND

Hyperbaric oxygen therapy (HBOT) markedly increases tissue oxygen delivery. Case series suggest it may have a potential therapeutic benefit in ulcerative colitis (UC). We investigated the therapeutic potential of HBOT as an adjunct to steroids for UC flares requiring hospitalization.

METHODS

The study was terminated early due to poor recruitment with 18 of the planned 70 patients enrolled. UC patients hospitalized for moderate-severe flares (Mayo score ≥6, endoscopic sub-score ≥2) were block randomized to steroids + daily HBOT (n = 10) or steroids + daily sham hyperbaric air (n = 8). Patients were blinded to study assignment, and assessments were performed by a blinded gastroenterologist. Primary outcome was the clinical remission rate at study day 5 (partial Mayo score ≤2 with no sub-score >1). Key secondary outcomes were: clinical response (reduction in partial Mayo score ≥2, rectal bleeding sub-score of 0-1) and progression to second-line therapy (colectomy or biologic therapy) during the hospitalization.

RESULTS

A significantly higher proportion of HBOT-treated patients achieved clinical remission at study day 5 and 10 (50 vs. 0%, p = 0.04). HBOT-treated patients less often required progression to second-line therapy during the hospitalization (10 vs. 63%, p = 0.04). The proportion requiring in-hospital colectomy specifically as second-line therapy for medically refractory UC was lower in the HBOT group compared to sham (0 vs. 38%, p = 0.07). There were no serious adverse events.

CONCLUSION

In this small, proof-of-concept, phase 2A trial, the use of HBOT as an adjunctive therapy to steroids for UC patients hospitalized for moderate-severe flares resulted in higher rates of clinical remission, and a reduction in rates of progression to second-line therapy during the hospitalization. Larger well-powered trials are needed, however, to provided definitive evidence of therapeutic benefit.

Circulating lipopolysaccharide-binding protein and carotid intima-media thickness in obstructive sleep apnea

Circulating lipopolysaccharide-binding protein (LBP), a metabolic endotoxemia marker, was identified as an independent predictor of atherosclerosis. Although increases in carotid intima-media thickness (CIMT) were repeatedly reported in obstructive sleep apnea (OSA), neither the role of OSA in metabolic endotoxemia nor of LBP in early atherosclerosis were explored in patients with OSA. At a tertiary university hospital we investigated the relationships between OSA, LBP and CIMT in 117 men who underwent full polysomnography and CIMT assessment by B-mode ultrasound. Circulating LBP concentrations and average CIMT increased from patients without OSA to those with mild-moderate and severe OSA (from 32.1+/-10.3 to 32.3+/-10.9 to 38.1+/-10.3 microg.ml(-1), p=0.015; from 0.52+/-0.09 to 0.58+/-0.06 to 0.62+/-0.10 mm, p=0.004, respectively). Oxygen desaturation index (ODI) was a predictor of serum LBP levels independent of age, waist-to-hip ratio (WHR), smoking, hypertension, HDL cholesterol, triglycerides and fasting glucose [p (ANOVA)=0.002, r(2)=0.154], with no independent effect of the ODI*WHR interaction term on LBP. Furthermore, serum LBP predicted CIMT independently of known risk factors of atherosclerosis including obesity (p<0.001, r(2)=0.321). Our results suggest that OSA severity contributes to metabolic endotoxemia in patients with OSA independently of obesity, and that LBP might represent a contributing factor promoting early atherosclerosis in such patients.