Joshua R. Korzenik

Dysfunction of the intestinal microbiome in inflammatory bowel disease and treatment

BackgroundThe inflammatory bowel diseases (IBD) Crohns disease and ulcerative colitis result from alterations in intestinal microbes and the immune system. However, the precise dysfunctions of microbial metabolism in the gastrointestinal microbiome during IBD remain unclear. We analyzed the microbiota of intestinal biopsies and stool samples from 231 IBD and healthy subjects by 16S gene pyrosequencing and followed up a subset using shotgun metagenomics. Gene and pathway composition were assessed, based on 16S data from phylogenetically-related reference genomes, and associated using sparse multivariate linear modeling with medications, environmental factors, and IBD status.ResultsFirmicutes and Enterobacteriaceae abundances were associated with disease status as expected, but also with treatment and subject characteristics. Microbial function, though, was more consistently perturbed than composition, with 12% of analyzed pathways changed compared with 2% of genera. We identified major shifts in oxidative stress pathways, as well as decreased carbohydrate metabolism and amino acid biosynthesis in favor of nutrient transport and uptake. The microbiome of ileal Crohns disease was notable for increases in virulence and secretion pathways.ConclusionsThis inferred functional metagenomic information provides the first insights into community-wide microbial processes and pathways that underpin IBD pathogenesis.

International guidelines for the diagnosis and management of hereditary haemorrhagic telangiectasia

Background HHT is an autosomal dominant disease with an estimated prevalence of at least 1/5000 which can frequently be complicated by the presence of clinically significant arteriovenous malformations in the brain, lung, gastrointestinal tract and liver. HHT is under-diagnosed and families may be unaware of the available screening and treatment, leading to unnecessary stroke and life-threatening hemorrhage in children and adults. Objective The goal of this international HHT guidelines process was to develop evidence-informed consensus guidelines regarding the diagnosis of HHT and the prevention of HHT-related complications and treatment of symptomatic disease. Methods The overall guidelines process was developed using the AGREE framework, using a systematic search strategy and literature retrieval with incorporation of expert evidence in a structured consensus process where published literature was lacking. The Guidelines Working Group included experts (clinical and genetic) from eleven countries, in all aspects of HHT, guidelines methodologists, health care workers, health care administrators, HHT clinic staff, medical trainees, patient advocacy representatives and patients with HHT. The Working Group determined clinically relevant questions during the pre-conference process. The literature search was conducted using the OVID MEDLINE database, from 1966 to October 2006. The Working Group subsequently convened at the Guidelines Conference to partake in a structured consensus process using the evidence tables generated from the systematic searches. Results The outcome of the conference was the generation of 33 recommendations for the diagnosis and management of HHT, with at least 80% agreement amongst the expert panel for 30 of the 33 recommendations.

Liver Disease in Patients with Hereditary Hemorrhagic Telangiectasia

BACKGROUND Hereditary hemorrhagic telangiectasia, or Rendu-Osler-Weber disease, is an autosomal dominant disorder characterized by angiodysplastic lesions (telangiectases and arteriovenous malformations) that affect many organs. Liver involvement in patients with this disease has not been fully characterized. METHODS We studied the clinical findings and results of hemodynamic, angiographic, and imaging studies in 19 patients with hereditary hemorrhagic telangiectasia and symptomatic liver involvement. RESULTS We evaluated 14 women and 5 men who ranged in age from 34 to 74 years. All but one of the patients had a hyperdynamic circulation (cardiac index, 4.2 to 7.3 liters per minute per square meter of body-surface area). In eight patients, the clinical findings were consistent with the presence of high-output heart failure. The cardiac index and pulmonary-capillary wedge pressure were elevated in the six patients in whom these measurements were performed. After a median period of 24 months, the condition of three of the eight patients had improved, four were in stable condition with medical therapy, and one had died. Six patients had manifestations of portal hypertension such as ascites or variceal bleeding. The hepatic sinusoidal pressure was elevated in the four patients in whom it was measured. After a median period of 19 months, the condition of two of the six patients had improved, and the other four had died. Five patients had manifestations of biliary disease, such as an elevated alkaline phosphatase level and abnormalities on bile duct imaging. After a median period of 30 months, the condition of two of the five had improved, the condition of one was unchanged, heart failure had developed in one, and one had died after an unsuccessful attempt at liver transplantation. CONCLUSIONS In patients with hereditary hemorrhagic telangiectasia and symptomatic liver-involvement, the typical clinical presentations include high-output heart failure, portal hypertension, and biliary disease.

Impact of Hospital Volume on Postoperative Morbidity and Mortality Following a Colectomy for Ulcerative Colitis

BACKGROUND & AIMS Postoperative morbidity and mortality following a colectomy for ulcerative colitis (UC) has been primarily reported from tertiary care referral centers that perform a high volume of operations; however, the postoperative outcomes among nonselected hospitals are not known. We set out to evaluate postoperative morbidity and mortality using a nationally representative database and to determine the factors that influenced outcomes. METHODS We analyzed the 1995-2005 Nationwide Inpatient Sample to identify 7108 discharges for UC patients who underwent a total abdominal colectomy. The effects of hospital volume on postoperative morbidity and mortality were evaluated in logistic regression models adjusting for demographic and clinical factors. RESULTS Postoperative mortality and morbidity rates were 2.3% and 30.8%, respectively. Most operations were performed in low-volume hospitals that had an increased risk of death (adjusted odds ratio [aOR], 2.42; 95% confidence interval [CI]: 1.26-4.63). In-hospital mortality was increased in patients who were admitted emergently (aOR, 5.40; 95% CI: 3.48-8.40), aged 60-80 years (aOR, 8.70; 95% CI: 3.30-22.92), and those with Medicaid (aOR, 4.29; 95% CI: 2.13-8.66). Emergently admitted UC patients whose surgery was performed 6 days after their admission had significantly increased likelihood of in-hospital death (aOR, 2.12; 95% CI: 1.13-3.97). CONCLUSIONS Postoperative mortality was lowest in hospitals that performed the highest volume of operations. Increasing the proportion of total colectomies performed in high-volume hospitals may improve clinical outcomes for patients with UC.

LRRK2 Is Involved in the IFN-γ Response and Host Response to Pathogens

LRRK2 was previously identified as a defective gene in Parkinson’s disease, and it is also located in a risk region for Crohn’s disease. In this study, we aim to determine whether LRRK2 could be involved in immune responses. We show that LRRK2 expression is enriched in human immune cells. LRRK2 is an IFN-γ target gene, and its expression increased in intestinal tissues upon Crohn’s disease inflammation. In inflamed intestinal tissues, LRRK2 is detected in the lamina propria macrophages, B-lymphocytes, and CD103-positive dendritic cells. Furthermore, LRRK2 expression enhances NF-κB–dependent transcription, suggesting its role in immune response signaling. Endogenous LRRK2 rapidly translocates near bacterial membranes, and knockdown of LRRK2 interferes with reactive oxygen species production during phagocytosis and bacterial killing. These observations indicate that LRRK2 is an IFN-γ target gene, and it might be involved in signaling pathways relevant to Crohn’s disease pathogenesis.

Treatment of active Crohn's disease with recombinant human granulocyte-macrophage colony-stimulating factor

Treatment for Crohns disease is aimed at immunosuppression. Yet inherited disorders associated with defective innate immunity often lead to development of a Crohns-like disease. We performed an open-label dose-escalation trial (4-8 microg/kg per day) to investigate the safety and possible benefit of granulocyte-macrophage colony-stimulating factor (GM-CSF) in the treatment of 15 patients with moderate to severe Crohns disease. No patients had worsening of their disease. Adverse events were negligible and included minor injection site reactions and bone pain. Patients had a significant decrease in mean Crohns disease activity index (CDAI) score during treatment (p<0.0001). After 8 weeks of treatment, mean CDAI had fallen by 190 points. Overall, 12 patients had a decrease in CDAI of more than 100 points, and eight achieved clinical remission. Retreatment was effective, and treatment was associated with increased quality-of-life measures. GM-CSF may offer an alternative to traditional immunosuppression in treatment of Crohns disease.

Evolving knowledge and therapy of inflammatory bowel disease

With recent advances in the understanding of its pathophysiology, inflammatory bowel disease has become a very active area for the development of novel therapeutic agents. New targets for biologics include cytokines involved in T-cell activation, with antibodies directed against IL-12 and interferon-γ. Selective adhesion molecule blockade has produced promising, though mixed, results. Recombinant human granulocyte–macrophage colony-stimulating factor might be effective in active Crohns disease, presumably through stimulation of intestinal innate immune responses. With increasing evidence for a crucial role for luminal flora in maintaining the health of the bowel, strategies to manipulate intestinal bacteria using probiotics and prebiotics are being actively investigated as well.

Infliximab and other immunomodulating drugs in patients with inflammatory bowel disease and the risk of serious bacterial infections

Background  There remain concerns about the safety of infliximab therapy in patients with inflammatory bowel disease (IBD).

Psoriasis associated with anti-tumour necrosis factor therapy in inflammatory bowel disease: a new series and a review of 120 cases from the literature

Aliment Pharmacol Ther 2011; 34: 1318–1327

Non-invasive mapping of the gastrointestinal microbiota identifies children with inflammatory bowel disease.

Background Pediatric inflammatory bowel disease (IBD) is challenging to diagnose because of the non-specificity of symptoms; an unequivocal diagnosis can only be made using colonoscopy, which clinicians are reluctant to recommend for children. Diagnosis of pediatric IBD is therefore frequently delayed, leading to inappropriate treatment plans and poor outcomes. We investigated the use of 16S rRNA sequencing of fecal samples and new analytical methods to assess differences in the microbiota of children with IBD and other gastrointestinal disorders. Methodology/Principal Findings We applied synthetic learning in microbial ecology (SLiME) analysis to 16S sequencing data obtained from i) published surveys of microbiota diversity in IBD and ii) fecal samples from 91 children and young adults who were treated in the gastroenterology program of Children’s Hospital (Boston, USA). The developed method accurately distinguished control samples from those of patients with IBD; the area under the receiver-operating-characteristic curve (AUC) value was 0.83 (corresponding to 80.3% sensitivity and 69.7% specificity at a set threshold). The accuracy was maintained among data sets collected by different sampling and sequencing methods. The method identified taxa associated with disease states and distinguished patients with Crohn’s disease from those with ulcerative colitis with reasonable accuracy. The findings were validated using samples from an additional group of 68 patients; the validation test identified patients with IBD with an AUC value of 0.84 (e.g. 92% sensitivity, 58.5% specificity). Conclusions/Significance Microbiome-based diagnostics can distinguish pediatric patients with IBD from patients with similar symptoms. Although this test can not replace endoscopy and histological examination as diagnostic tools, classification based on microbial diversity is an effective complementary technique for IBD detection in pediatric patients.