Artificial Intelligence for Real-Time Prediction of the Histology of Colorectal Polyps by General Endoscopists.

BACKGROUND: Real-time prediction of histologic features of small colorectal polyps may prevent resection and/or pathologic evaluation and therefore decrease colonoscopy costs. Previous studies showed that computer-aided diagnosis (CADx) was highly accurate, though it did not outperform expert endoscopists. OBJECTIVE: To assess the diagnostic performance of histologic predictions by general endoscopists before and after assistance from CADx in a real-life setting. DESIGN: Prospective, multicenter, single-group study. (ClinicalTrials.gov: NCT04437615). SETTING: 6 centers across the United States. PARTICIPANTS: 1252 consecutive patients undergoing colonoscopy and 49 general endoscopists with variable experience in real-time prediction of polyp histologic features. INTERVENTION: Real-time use of CADx during routine colonoscopy. MEASUREMENTS: The primary end points were the sensitivity and specificity of CADx-unassisted and CADx-assisted histologic predictions for adenomas measuring 5 mm or less. For clinical purposes, additional estimates according to location and confidence level were provided. RESULTS: The CADx device made a diagnosis for 2695 polyps measuring 5 mm or less (96%) in 1252 patients. There was no difference in sensitivity between the unassisted and assisted groups (90.7% vs. 90.8%; P = 0.52). Specificity was higher in the CADx-assisted group (59.5% vs. 64.7%; P < 0.001). Among all 2695 polyps measuring 5 mm or less, 88.2% and 86.1% (P < 0.001) in the CADx-assisted and unassisted groups, respectively, could be resected and discarded without pathologic evaluation. Among 743 rectosigmoid polyps measuring 5 mm or less, 49.5% and 47.9% (P < 0.001) in the CADx-assisted and unassisted groups, respectively, could be left in situ without resection. LIMITATION: Decision making based on CADx might differ outside a clinical trial. CONCLUSION: CADx assistance did not result in increased sensitivity of optical diagnosis. Despite a slight increase, the specificity of CADx-assisted diagnosis remained suboptimal. PRIMARY FUNDING SOURCE: Olympus America Corporation served as the clinical study sponsor.

A Novel Approach toward Less Invasive Multiomics Gut Analyses: a Pilot Study.

Newer 'omics approaches, such as metatranscriptomics and metabolomics, allow functional assessments of the interaction(s) between the gut microbiome and the human host. However, in order to generate meaningful data with these approaches, the method of sample collection is critical. Prior studies have relied on expensive and invasive means toward sample acquisition, such as intestinal biopsy, while other studies have relied on easier methods of collection, such as fecal samples that do not necessarily represent those microbes in contact with the host. In this pilot study, we attempt to characterize a novel, minimally invasive method toward sampling the human microbiome using mucosal cytology brush sampling compared to intestinal gut biopsy samples on 5 healthy participants undergoing routine screening colonoscopy. We compared metatranscriptomic analyses between the two collection methods and identified increased taxonomic evenness and beta diversity in the cytology brush samples and similar community transcriptional profiles between the two methods. Metabolomics assessment demonstrated striking differences between the two methods, implying a difference in bacterial-derived versus human-absorbed metabolites. Put together, this study supports the use of microbiome sampling with cytology brushes, but caution must be exercised when performing metabolomics assessment, as this represents differential metabolite production but not absorption by the host. IMPORTANCE In order to generate meaningful metabolomic and microbiome data, the method of sample collection is critical. This study utilizes and compares two methods for intestinal tissue collection for evaluation of metabolites and microbiomes, finding that using a brush to sample the microbiome provides valuable data. However, for metabolomics assessment, biopsy samples may still be required.

Delays Related to Prior Authorization in Inflammatory Bowel Disease.

BACKGROUND: Delays in advancing to biologic therapies are associated with adverse outcomes in inflammatory bowel disease (IBD). Insurer-mandated prior authorizations have been linked to prolonged medication initiation times. We hypothesized that prior authorizations are associated with prolonged biologic initiation time and increased IBD-related healthcare utilization among children with IBD. METHODS: We performed a retrospective cohort study of 190 pediatric patients with IBD initiating biologics at a tertiary care hospital to measure the association between prior authorization, biologic initiation time (physician recommendation to first dose), and healthcare utilization (hospitalization, surgery, or emergency department visit). Demographic, insurance, and disease severity-related covariables were collected. Multivariable linear regression was used to measure the association between prior authorization and biologic initiation time. Propensity score methods were used to measure the associations between prior authorization and IBD-related healthcare utilization within 180 days and corticosteroid dependence at 90 days, with adjustment for insurance type, demographics, and disease severity-related characteristics. RESULTS: Median biologic initiation time was 21 days. Prior authorization and complicated prior authorizations (requiring appeal, step therapy, or peer-to-peer review) were associated with 10.2-day (95% confidence interval [CI] 8.2 to 12.3) and 24.6-day (95% CI 16.4 to 32.8) increases in biologic initiation time, respectively. Prior authorizations increased the likelihood of IBD-related healthcare utilization within 180 days by 12.9% (95% CI 2.5 to 23.4) and corticosteroid dependence at 90 days by 14.1% (95% CI 3.3 to 24.8). CONCLUSIONS: Prior authorizations are associated with prolonged biologic initiation time and increased IBD-related healthcare utilization. Minimizing prior authorization-related delays may expedite biologic delivery and reduce the risk of IBD-related healthcare utilization.

Circulating mature granzyme B+ T cells distinguish Crohn's disease-associated axial spondyloarthritis from axial spondyloarthritis and Crohn's disease.

BACKGROUND: Axial spondyloarthritis (axSpA) has strong connections with intestinal inflammation as occurs in Crohn's disease (CD). However, the immunologic mechanisms that distinguish axSpA, CD, and those with features of both diseases (CD-axSpA) are unknown. This study aimed to address this question by initial unbiased single cell RNA-sequencing (scRNAseq) on a pilot cohort followed by validating findings using flow cytometry and ELISA in a larger cohort. METHODS: Two individuals each with CD, axSpA, CD-axSpA, and healthy controls (HC) were recruited for a pilot discovery scRNAseq cohort, and the validation cohort consisted of 18 axSpA, 24 CD, 13 CD-axSpA, and 17 HC that was evaluated by flow cytometry on PBMCs and ELISAs for plasma cytokines. RESULTS: Uniquely, PBMCs from subjects with CD-axSpA demonstrated a significant increase in granzyme B+ T cells of both CD4+ and CD8+ lineages by both scRNAseq and flow cytometry. T cell maturation was also greater in those with CD-axSpA, particularly the CD4+ granzyme B+ population. Pathway analysis suggested increased interferon response genes in all immune cell populations within CD-axSpA. Although IFN-γ was elevated in the plasma of a subset of subjects with CD-axSpA, IL-6 was also significantly elevated. CONCLUSIONS: Our findings support the presence of a chronic interferonopathy in subjects with CD-axSpA characterized by interferon signaling by pathway analysis and an expansion of mature, cytotoxic T cells. These data indicate fundamental immunological differences between CD-axSpA and both of the putative "parent" conditions, suggesting that it is a distinct disease with unique natural history and treatment needs.

Multi 'Omics Analysis of Intestinal Tissue in Ankylosing Spondylitis Identifies Alterations in the Tryptophan Metabolism Pathway.

Intestinal microbial dysbiosis, intestinal inflammation, and Th17 immunity are all linked to the pathophysiology of spondyloarthritis (SpA); however, the mechanisms linking them remain unknown. One potential hypothesis suggests that the dysbiotic gut microbiome as a whole produces metabolites that influence human immune cells. To identify potential disease-relevant, microbiome-produced metabolites, we performed metabolomics screening and shotgun metagenomics on paired colon biopsies and fecal samples, respectively, from subjects with axial SpA (axSpA, N=21), Crohn's disease (CD, N=27), and Crohn's-axSpA overlap (CD-axSpA, N=12), as well as controls (HC, N=24). Using LC-MS based metabolomics of 4 non-inflamed pinch biopsies of the distal colon from subjects, we identified significant alterations in tryptophan pathway metabolites, including an expansion of indole-3-acetate (IAA) in axSpA and CD-axSpA compared to HC and CD and indole-3-acetaldehyde (I3Ald) in axSpA and CD-axSpA but not CD compared to HC, suggesting possible specificity to the development of axSpA. We then performed shotgun metagenomics of fecal samples to characterize gut microbial dysbiosis across these disease states. In spite of no significant differences in alpha-diversity among the 4 groups, our results confirmed differences in gene abundances of numerous enzymes involved in tryptophan metabolism. Specifically, gene abundance of indolepyruvate decarboxylase, which generates IAA and I3Ald, was significantly elevated in individuals with axSpA while gene abundances in HC demonstrated a propensity towards tryptophan synthesis. Such genetic changes were not observed in CD, again suggesting disease specificity for axSpA. Given the emerging role of tryptophan and its metabolites in immune function, altogether these data indicate that tryptophan metabolism into I3Ald and then IAA is one mechanism by which the gut microbiome potentially influences the development of axSpA.

Vedolizumab Concentrations in Breast Milk: Results from a Prospective, Postmarketing, Milk-Only Lactation Study in Nursing Mothers with Inflammatory Bowel Disease.

BACKGROUND AND OBJECTIVES: The safety of inflammatory bowel disease medications during lactation is of significant relevance to women of childbearing potential. Available data regarding the transfer of biologic agents for inflammatory bowel disease via breast milk are limited to case reports. The objective of this prospective postmarketing lactation study was to assess vedolizumab concentrations in breast milk from lactating vedolizumab-treated women with inflammatory bowel disease. METHODS: Breast milk was serially collected throughout the dosing interval from 11 patients receiving established intravenous vedolizumab 300-mg maintenance therapy every 8, 6, or 4 weeks. Maternal safety was also assessed. RESULTS: Vedolizumab was detectable in ~90% of milk samples collected from all patients. Following the day 1 dose, vedolizumab milk concentrations increased with a median of 3-4 days to peak concentration, and subsequently decreased exponentially. For the nine patients receiving vedolizumab every 8 weeks, the average relative infant dose was 20.9%. Using a mean trough serum concentration of 11.2 µg/mL from historical studies, the ratio of mean vedolizumab milk-to-serum concentration was ~ 0.4 to 2.2%, consistent with published data on vedolizumab and other monoclonal antibody therapeutics for inflammatory bowel disease. The maternal safety profile was similar to that observed in previous vedolizumab studies. Published vedolizumab studies also showed no adverse findings for infants breastfed by vedolizumab-treated mothers. CONCLUSIONS: Vedolizumab was present in human breast milk at a low level. The decision to use vedolizumab should balance the benefit of therapy to the mother and the potential risks to the infant. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02559713; registered 24 September, 2015.

Bile acids modulate colonic MAdCAM-1 expression in a murine model of combined cholestasis and colitis.

Primary sclerosing cholangitis (PSC) is a progressive fibrosing cholestatic liver disease that is strongly associated with inflammatory bowel disease (IBD). PSC-associated IBD (PSC-IBD) displays a unique phenotype characterized by right-side predominant colon inflammation and increased risk of colorectal cancer compared to non-PSC-IBD. The frequent association and unique phenotype of PSC-IBD suggest distinctive underlying disease mechanisms from other chronic liver diseases or IBD alone. Multidrug resistance protein 2 knockout (Mdr2-/-) mice develop spontaneous cholestatic liver injury and fibrosis mirroring human PSC. As a novel model of PSC-IBD, we treated Mdr2-/- mice with dextran sulfate sodium (DSS) to chemically induce colitis (Mdr2-/-/DSS). Mdr2-/- mice demonstrate alterations in fecal bile acid composition and enhanced colitis susceptibility with increased colonic adhesion molecule expression, particularly mucosal addressin-cell adhesion molecule 1 (MAdCAM-1). In vitro, ursodeoxycholic acid (UDCA) co-treatment resulted in a dose dependent attenuation of TNF-α-induced endothelial MAdCAM-1 expression. In the combined Mdr2-/-/DSS model, UDCA supplementation attenuated colitis severity and downregulated intestinal MAdCAM-1 expression. These findings suggest a potential mechanistic role for alterations in bile acid signaling in modulating MAdCAM-1 expression and colitis susceptibility in cholestasis-associated colitis. Together, our findings provide a novel model and new insight into the pathogenesis and potential treatment of PSC-IBD.

Identification of the Most Effective Position for Ustekinumab in Treatment Algorithms for Crohn's Disease.

BACKGROUND & AIMS: Ustekinumab is a monoclonal antibody against interleukin 12 and interleukin 23 that has been approved by the Food and Drug Administration for treatment of Crohn's disease (CD). We sought to identify the ideal position for ustekinumab in treatment algorithms for CD. METHODS: We constructed a Markov model to identify an optimal treatment sequence for CD that included ustekinumab for 1 year or more. The base case was a 35-year old male with moderate to severe CD who had not previously received biologic or immunomodulator therapy. The standard of care treatment algorithm was defined as initial therapy with infliximab and azathioprine, followed by adalimumab and azathioprine, vedolizumab, and lastly surgical resection. The model assessed positions for ustekinumab before standard of care, ustekinumab after infliximab and azathioprine but before the remaining treatments, after infliximab, azathioprine, and adalimumab but before vedolizumab and surgery, or after the other biologics but before surgery. We derived transition probabilities and quality adjusted life years (QALYs) from relevant trials, observational studies, and time trade-off analyses. Primary analyses consisted of first order Monte Carlo simulation of 100 trials of cohorts of 100,000 individuals. RESULTS: Ustekinumab as first-line therapy yielded the greatest QALYs (incremental effectiveness, 0.016-0.020 QALYs), resulting in 10% more patients in remission or response, and 2% fewer surgeries at 1 year, compared with other algorithms. The model was not sensitive to 25% variation in transition probabilities. CONCLUSIONS: In a simulation based on a 35-year old male patient with moderate to severe CD, we found that ustekinumab as the first-line biologic therapy yields greater QALYs at the end of 1 year than compared with use later in the CD treatment algorithm.

Markers of Hypoxia Correlate with Histologic and Endoscopic Severity of Colitis in Inflammatory Bowel Disease.

BACKGROUND: Inflammation results in significant shifts in tissue metabolism. Recent studies indicate that inflammation and hypoxia occur concomitantly. We examined whether circulating and tissue markers of hypoxia could serve as surrogate indicators of disease severity in adult and pediatric patients with inflammatory bowel disease (IBD). METHODS: Serum and colonic biopsies were obtained from pediatric subjects with active IBD colitis and adult subjects with active and inactive ulcerative colitis, along with healthy non-colitis controls of all ages. Disease activity was evaluated by endoscopy and histopathology. Levels of serum hypoxia markers (macrophage inflammatory protein-3α [MIP-3α], vascular endothelial growth factor [VEGF], and erythropoietin [EPO]) were measured. RESULTS: Children with active IBD colitis had higher levels of serum MIP-3α and VEGF compared to non-colitis controls (p<0.01 and p<0.05, respectively). In adult subjects with endoscopically active ulcerative colitis, serum MIP-3α and EPO were significantly elevated compared to non-colitis controls (both p<0.01). In parallel, analysis of colon tissue MIP-3α mRNA and protein in pediatric subjects revealed increased expression in those with IBD colitis compared to controls (p<0.05 and p<0.01 for mRNA and protein, respectively). Serum MIP-3α and VEGF significantly increased with histology grade. CONCLUSION: Peripheral blood hypoxia markers may be useful indicators of disease activity for pediatric and adult IBD patients.

Can gut microbiota of men who have sex with men influence HIV transmission?

Gaining a complete understanding of transmission risk factors will assist in efforts to reduce new HIV infections, especially within the disproportionally affected population of men who have sex with men (MSM). We recently reported that the fecal microbiota of MSM elevates immune activation in gnotobiotic mice and enhances HIV infection in vitro over that of fecal microbiota from men who have sex with women. We also demonstrated elevation of the gut homing marker CD103 (integrin αE) on CD4+ T cells by MSM-microbiota. Here we provide additional evidence that the gut microbiota is a risk factor for HIV transmission in MSM by showing elevated frequencies of the HIV co-receptor CCR5 on CD4+ T cells in human rectosigmoid colon biopsies. We discuss our interest in specific MSM-associated bacteria and propose the influx of CD103+ and CCR5+ CD4+ T cells into the colon as a potential link between the MSM microbiota and HIV transmission.

Identification of the Most Cost-effective Position of Vedolizumab Among the Available Biologic Drugs for the Treatment of Ulcerative Colitis.

BACKGROUND AND AIMS: There are limited data on the most cost-effective sequencing of biologics for ulcerative colitis [UC]. METHODS: We used Markov modelling to identify the most cost-effective position for vedolizumab among biologics for steroid-dependent UC, with a base-case of a 35-year-old male. We assessed three treatment algorithms, with vedolizumab use: prior to an initial anti-tumour necrosis factor alpha [anti-TNFα] and azathioprine [Algorithm 1]; prior to a second anti-TNF and azathioprine [Algorithm 2]; and prior to colectomy [Algorithm 3]. The initial anti-TNF could be either infliximab or adalimumab. Transition probabilities, costs, and quality-adjusted life-year estimates were derived from published estimates, Medicare, and the Nationwide Inpatient Sample. Primary analyses included 100 trials of 100 000 individuals over 1 year, with a willingness-to-pay threshold of US$100,000. Multiple sensitivity analyses were conducted to assess our findings. RESULTS: From a population perspective, when both infliximab and adalimumab are available, vedolizumab was preferred as the first biologic if ≥14% of initial anti-TNF use was adalimumab. If infliximab is the primary biologic, vedolizumab use after infliximab [Algorithm 2] and prior to adalimumab was the most cost-effective strategy. All models were sensitive to biologic pricing. CONCLUSIONS: This simulation demonstrated that the most cost-effective strategy in UC depends on the proportion of patients using adalimumab as the initial anti-TNF. If adalimumab was ≥14%, vedolizumab was preferred as the first biologic. When only infliximab was available for first-line therapy, the most cost-effective position of vedolizumab was prior to cycling to adalimumab.

Adaptation to inflammatory acidity through neutrophil-derived adenosine regulation of SLC26A3.

Acute intestinal inflammation includes the early accumulation of neutrophils (PMN). Based on recent evidence that PMN infiltration "imprints" changes in the local tissue environment through local oxygen depletion and the release of adenine nucleotides, we hypothesized that the interaction between transmigrating PMN and intestinal epithelial cells (IECs) results in inflammatory acidification of the tissue. Using newly developed tools, we revealed that active PMN transepithelial migration (TEM) significantly acidifies the local microenvironment, a decrease of nearly 2 pH units. Using unbiased approaches, we sought to define acid-adaptive pathways elicited by PMN TEM. Given the significant amount of adenosine (Ado) generated during PMN TEM, we profiled the influence of Ado on IECs gene expression by microarray and identified the induction of SLC26A3, the major apical Cl-/HCO3- exchanger in IECs. Utilizing loss- and gain-of-function approaches, as well as murine and human colonoids, we demonstrate that Ado-induced SLC26A3 promotes an adaptive IECs phenotype that buffers local pH during active inflammation. Extending these studies, chronic murine colitis models were used to demonstrate that SLC26A3 expression rebounds during chronic DSS-induced inflammation. In conclusion, Ado signaling during PMN TEM induces an adaptive tissue response to inflammatory acidification through the induction of SLC26A3 expression, thereby promoting pH homeostasis.

Cholestatic liver disease results increased production of reactive aldehydes and an atypical periportal hepatic antioxidant response.

Cholangiopathies such as primary sclerosing cholangitis (PSC) are chronic liver diseases characterized by increased cholestasis, biliary inflammation and oxidative stress. The objective of this study was to elucidate the impact of cholestatic injury on oxidative stress-related factors. Using hepatic tissue and whole cell liver extracts (LE) isolated from 11-week old C57BL/6J (WT) and Mdr2KO mice, inflammation and oxidative stress was assessed. Concurrently, specific targets of carbonylation were assessed in LE prepared from murine groups as well as from normal and human patients with end-stage PSC. Identified carbonylated proteins were further evaluated using bioinformatics analyses. Picrosirius red staining revealed extensive fibrosis in Mdr2KO liver, and fibrosis colocalized with increased periportal inflammatory cells and both acrolein and 4-HNE staining. Western blot analysis revealed elevated periportal expression of antioxidant proteins Cbr3, GSTµ, Prdx5, TrxR1 and HO-1 but not GCLC, GSTπ or catalase in the Mdr2KO group when compared to WT. From immunohistochemical analysis, increased periportal reactive aldehyde production colocalized with elevated staining of Cbr3, GSTµ and TrxR1 but surprisingly not with Nrf2. Mass spectrometric analysis revealed an increase in carbonylated proteins in the Mdr2KO and PSC groups compared to respective controls. Gene ontology and KEGG pathway analysis of carbonylated proteins revealed a propensity for increased carbonylation of proteins broadly involved in metabolic processes as well more specifically in Rab-mediated signal transduction, lysosomes and the large ribosomal subunit in human PSC. Western blot analysis of Rab-GTPase expression revealed no significant differences in Mdr2KO mice when compared to WT livers. In contrast, PSC tissue exhibited decreased levels of Rabs 4, 5 and increased abundance of Rabs 6 and 9a protein. Results herein reveal that cholestasis induces stage-dependent increases in periportal oxidative stress responses and protein carbonylation, potentially contributing to pathogenesis in Mdr2KO. Furthermore, during early stage cholestasis, there is cell-specific upregulation of some but not all, antioxidant proteins.

Functional intraepithelial lymphocyte changes in inflammatory bowel disease and spondyloarthritis have disease specific correlations with intestinal microbiota.

BACKGROUND: Dysbiosis occurs in spondyloarthritis (SpA) and inflammatory bowel disease (IBD), which is subdivided into Crohn's disease (CD) and ulcerative colitis (UC). The immunologic consequences of alterations in microbiota, however, have not been defined. Intraepithelial lymphocytes (IELs) are T cells within the intestinal epithelium that are in close contact with bacteria and are likely to be modulated by changes in microbiota. We examined differences in human gut-associated bacteria and tested correlation with functional changes in IELs in patients with axial SpA (axSpA), CD, or UC, and in controls. METHODS: We conducted a case-control study to evaluate IELs from pinch biopsies of grossly normal colonic tissue from subjects with biopsy-proven CD or UC, axSpA fulfilling Assessment of SpondyloArthritis International Society (ASAS) criteria and from controls during endoscopy. IELs were harvested and characterized by flow cytometry for cell surface markers. Secreted cytokines were measured by ELISA. Microbiome analysis was by 16S rRNA gene sequencing from rectal swabs. Statistical analyses were performed with the Kruskal-Wallis and Spearman's rank tests. RESULTS: The total number of IELs was significantly decreased in subjects with axSpA compared to those with IBD and controls, likely due to a decrease in TCRß+ IELs. We found strong, significant negative correlation between peripheral lymphocyte count and IEL number. IELs secreted significantly increased IL-1ß in patients with UC, significantly increased IL-17A and IFN-γ in patients with CD, and significantly increased TNF-α in patients with CD and axSpA as compared to other cohorts. For each disease subtype, IELs and IEL-produced cytokines were positively and negatively correlated with the relative abundance of multiple bacterial taxa. CONCLUSIONS: Our data indicate differences in IEL function among subjects with axSpA, CD, and UC compared to healthy controls. We propose that the observed correlation between altered microbiota and IEL function in these populations are relevant to the pathogenesis of axSpA and IBD, and discuss possible mechanisms. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02389075 . Registered on 17 March 2015.

Inflammatory Bowel Disease: Influence and Implications in Reproduction.

The incidence and prevalence of inflammatory bowel disease (IBD) continues to rise with time, signifying its emergence as a global disease. Clinical onset of IBD, comprising Crohn's disease and ulcerative colitis, typically occurs before or at peak reproductive age. Although active disease in female patients is associated with reduced fertility and adverse obstetric outcomes in pregnancy, the molecular mechanisms underlying this altered reproductive course, and its impact on IBD transmission to offspring, remain poorly understood. Clinical and experimental studies have now begun to elucidate the hormonal, environmental, and microbial factors that modulate immune-reproductive cross talk in IBD and define their impact on maternal health, fetal development, and heritability of disease risk. Evolving insight into maternal-fetal imprinting in IBD has important implications for patient counseling and disease management during pregnancy and may help predict clinical outcomes for both mother and child.

HIF-dependent regulation of AKAP12 (gravin) in the control of human vascular endothelial function.

Hypoxia has been widely implicated in many pathological conditions, including those associated with inflammation and tumorigenesis. A number of recent studies have implicated hypoxia in the control of vasculogenesis and permeability, the basis for which is not fully understood. Here we examine the transcriptional regulation of angiogenesis and permeability by hypoxia in endothelial cells. Guided by a global profiling approach in cultured endothelial cells, these studies revealed the selective induction of human gravin (protein kinase A anchoring protein 12) by hypoxia. Analysis of the cloned gravin promoter identified a functional hypoxia-responsive region including 2 binding sites for hypoxia-inducible factor (HIF). Site-directed mutagenesis identified the most distal HIF-binding site as essential for the induction of gravin by hypoxia. Further studies examining gravin gain and loss of function confirmed strong dependence of gravin in control of microvascular endothelial tube formation, wherein gravin functions as a "braking" system for angiogenesis. Additional studies in confluent endothelia revealed that gravin functionally couples to control endothelial barrier function in response to protein kinase A (PKA) agonists. Taken together, these results demonstrate transcriptional coordination of gravin by HIF-1α and amplified PKA-dependent endothelial responses. These findings provide an important link between hypoxia and metabolic conditions associated with inflammation and angiogenesis.

Adenosine and gastrointestinal inflammation.

Nucleosides such as adenosine (Ado) influence nearly every aspect of physiology and pathophysiology. Extracellular nucleotides liberated at local sites of inflammation are metabolized through regulated phosphohydrolysis by a series of ecto-nucleotidases including ectonucleoside triphosphate diphosphohydrolase-1 (CD39) and ecto-5'-nucleotidase (CD73), found on the surface of a variety of cell types. Once generated, Ado is made available to bind and activate one of four G protein-coupled Ado receptors. Recent in vitro and in vivo studies implicate Ado in a broad array of tissue-protective mechanisms that provide new insight into adenosine actions. Studies in cultured cells and murine tissues have indicated that Ado receptors couple to novel posttranslational protein modifications, including Cullin deneddylation, as a new anti-inflammatory mechanism. Studies in Ado receptor-null mice have been revealing and indicate a particularly important role for the Ado A2B receptor in animal models of intestinal inflammation. Here, we review contributions of Ado to cell and tissue stress responses, with a particular emphasis on the gastrointestinal mucosa.

Can colonoscopy remain cost-effective for colorectal cancer screening? The impact of practice patterns and the Will Rogers phenomenon on costs.

OBJECTIVES: The adenoma detection rate (ADR) in screening colonoscopy is higher than original cost-effectiveness models estimated. Future colorectal cancer (CRC) risk is decreased once the ADR is 20%, but it is unclear how much additional protection is provided with higher ADRs. We modeled the impact of a high ADR on future CRC risk and surveillance colonoscopy burden. METHODS: We created three hypothetical scenarios for 100,000 average-risk individuals undergoing screening colonoscopy at age 50: (i) 20% ADR with 30% future CRC risk reduction; (ii) 50% ADR with 30% future CRC risk reduction; and (iii) 50% ADR with 50% future CRC risk reduction. After colonoscopy, patients could have high-risk or low-risk adenomas, or no adenomas. RESULTS: When the ADR increases from 20% to 50% but no additional CRC cases are prevented, future CRC risk for each group is still reduced, because lower-risk patients migrate into apparently higher-risk groups (the Will Rogers phenomenon). Future risk is further reduced if a 50% ADR leads to greater protection from CRC. However, despite the reductions in group-specific and overall future CRC risk, 34,635 additional surveillance colonoscopies are performed before the cohort is 60 years old when the ADR is 50% compared with 20%. CONCLUSIONS: If current surveillance practices continue along with high ADRs, screening colonoscopy may not remain cost-effective.

Hypoxia-inducible factor-dependent regulation of platelet-activating factor receptor as a route for gram-positive bacterial translocation across epithelia.

Mucosal surfaces, such as the lung and intestine, are lined by a monolayer of epithelia that provides tissue barrier and transport function. It is recently appreciated that a common feature of inflammatory processes within the mucosa is hypoxia (so-called inflammatory hypoxia). Given the strong association between bacterial translocation and mucosal inflammatory disease, we hypothesized that intestinal epithelial hypoxia influences bacterial translocation. Initial studies revealed that exposure of cultured intestinal epithelia to hypoxia (pO(2), 20 torr; 24-48 h) resulted in a increase of up to 40-fold in the translocation of some strains of Gram-positive bacteria, independently of epithelial barrier function. A screen of relevant pathway inhibitors identified a prominent role for the platelet-activating factor receptor (PAFr) in hypoxia-associated bacterial translocation, wherein pharmacologic antagonists of PAFr blocked bacterial translocation by as much as 80 +/- 6%. Extensions of these studies revealed that hypoxia prominently induces PAFr through a hypoxia-inducible factor (HIF)-dependent mechanism. Indeed, HIF and PAFr loss of function studies (short hairpin RNA) revealed that apically expressed PAFr is central to the induction of translocation for the Gram-positive bacteria Enterococcus faecalis. Together, these findings reveal that some strains of Gram-positive bacteria exploit HIF-regulated PAFr as a means for translocation through intestinal epithelial cells.