Colonic microbiota can promote rapid local improvement of murine colitis by thioguanine independently of T lymphocytes and host metabolism.

OBJECTIVE: Mercaptopurine (MP) and pro-drug azathioprine are 'first-line' oral therapies for maintaining remission in IBD. It is believed that their pharmacodynamic action is due to a slow cumulative decrease in activated lymphocytes homing to inflamed gut. We examined the role of host metabolism, lymphocytes and microbiome for the amelioration of colitis by the related thioguanine (TG). DESIGN: C57Bl/6 mice with or without specific genes altered to elucidate mechanisms responsible for TG's actions were treated daily with oral or intrarectal TG, MP or water. Disease activity was scored daily. At sacrifice, colonic histology, cytokine message, caecal luminal and mucosal microbiomes were analysed. RESULTS: Oral and intrarectal TG but not MP rapidly ameliorated spontaneous chronic colitis in Winnie mice (point mutation in Muc2 secretory mucin). TG ameliorated dextran sodium sulfate-induced chronic colitis in wild-type (WT) mice and in mice lacking T and B lymphocytes. Remarkably, colitis improved without immunosuppressive effects in the absence of host hypoxanthine (guanine) phosphoribosyltransferase (Hprt)-mediated conversion of TG to active drug, the thioguanine nucleotides (TGN). Colonic bacteria converted TG and less so MP to TGN, consistent with intestinal bacterial conversion of TG to so reduce inflammation in the mice lacking host Hprt. TG rapidly induced autophagic flux in epithelial, macrophage and WT but not Hprt-/- fibroblast cell lines and augmented epithelial intracellular bacterial killing. CONCLUSIONS: Treatment by TG is not necessarily dependent on the adaptive immune system. TG is a more efficacious treatment than MP in Winnie spontaneous colitis. Rapid local bacterial conversion of TG correlated with decreased intestinal inflammation and immune activation.

Low-dose azathioprine or mercaptopurine in combination with allopurinol can bypass many adverse drug reactions in patients with inflammatory bowel disease.

BACKGROUND: The thiopurine drugs, azathioprine and mercaptopurine (MP), are established treatments for IBD. However, therapeutic failure caused by adverse drug reactions occurs frequently. AIM: To study combination of allopurinol with reduced-dose thiopurine in an attempt to avoid adverse drug reactions in the treatment of IBD. METHODS: Patients with drug reactions to full-dose thiopurines were recruited for combination therapy in two IBD centres in this retrospective study. Dosing was guided by measuring thiopurine methyltransferase (for UK patients) or thioguanine nucleotides and methyl-6MP (Australian patients). Response was monitored by clinical activity indices. RESULTS: Of 41 patients, 25 had non-hepatic and 16 had hepatitic reactions. Clinical remission was achieved in 32 patients (78%) with a median follow-up of 41 weeks (range 0.5-400). Patients who did not respond to combination therapy tended to fail early with the same adverse reaction. The relative risk of having an adverse reaction with methyl-6MP in the top interquartile range was 2.7 (1.3-28) times that with methyl-6MP in the lower three quartiles (95% confidence interval). CONCLUSION: The combined experience from our centres is the largest reported experience of this combination therapy strategy in IBD, and the first to provide evidence for benefit in thiopurine and allopurinol co-therapy to avoid non-hepatitic adverse drug reactions.

Comparison of the efficacy and safety of Eudragit-L-coated mesalazine tablets with ethylcellulose-coated mesalazine tablets in patients with mild to moderately active ulcerative colitis.

BACKGROUND: There are no comparative studies of coated mesalazine. AIM: To compare the efficacy and tolerability of Eudragit-L- and ethylcellulose-coated mesalazine tablets in patients with mild to moderately active ulcerative colitis. METHODS: A double-blind, double-dummy, randomized parallel group trial was performed across 18 centres in Australia, and 20 in Eastern Europe. Patients were treated with 3 g mesalazine for 8 weeks with the primary efficacy end point being clinical remission. RESULTS: Of 215 patients, 69% achieved clinical remission in both treatment groups (P < 0.001; chi-square test) with no differences in frequency of adverse events. In the Australian cohort (n = 63), the Eudragit-L group had a higher remission rate (73% vs. 36%) and responded 13 days faster, compared with those in the European group (67% vs. 84%, and 2 days respectively). No clear reasons for differences in treatment responses were identified. CONCLUSIONS: Eudragit-L and ethylcellulose-coated mesalazine tablets are well tolerated and equally effective in achieving remission in mild-moderately active ulcerative colitis over 8 weeks.

Epidemiology of appendicectomy in primary sclerosing cholangitis and ulcerative colitis: its influence on the clinical behaviour of these diseases.

BACKGROUND AND AIMS: Appendicectomy and smoking are environmental factors that are known to influence ulcerative colitis (UC). The phenotype of UC is different in patients with coexistent primary sclerosing cholangitis (PSC). This study investigates the interaction of appendicectomy and PSC on the epidemiology and clinical behaviour of colitis. METHODS: Patients were from the Brisbane IBD Research Group database. Controls were from the Australian twin registry. Seventy eight PSC-inflammatory bowel disease (PSC-IBD) patients, 12 pure PSC, and 294 UC patients were matched with 1466 controls by sex and birth cohort that comprised randomly selected twins from each twin pair. The effects of appendicectomy, smoking, or PSC on the onset of disease, disease extent, disease severity (as identified by immunosuppression-colectomy or liver transplant), and disease related complications (high grade dysplasia, colorectal cancer, or cholangiocarcinoma) were investigated using univariate and multiple logistic regression analyses. RESULTS: PSC-IBD patients had a more extensive colitis than UC patients (p<0.0001) but required less immunosuppression (p = 0.007), which was independent of disease extent. They were more likely to have high grade dysplasia or colorectal cancer (p = 0.029) than UC patients. Appendicectomy rates in the PSC groups were not different from the control groups (p = 0.72, 0.76), which was in sharp contrast with UC where the rate was four times less (p = 0.0001). Prior appendicectomy appeared to be associated with an approximate five year delay in the onset of intestinal (PSC-IBD or UC) or hepatic (PSC) disease, which was independent of smoking. Appendicectomy did not independently alter the extent or severity of disease in PSC. In contrast, prior appendicectomy in UC was associated with more extensive disease but with a lesser requirement for immunosuppression or colectomy for the treatment of colitis (p = 0.004). There were trends for high grade dysplasia or colorectal cancer with appendicectomy in both PSC-IBD and UC. Although these trends were not statistically significant, colorectal cancer appeared more frequent with appendicectomy in a meta-analysis of the available UC data from this and another Australian study. CONCLUSIONS: In contradistinction to UC, appendicectomy did not significantly influence the prevalence of the PSC groups, or the extent of colitis in PSC-IBD, but as with UC, did appear to delay their onset. The extensive milder colitis, which is characteristic of PSC-IBD, relates to other poorly understood factors. Further prospective studies are required to determine any influence of appendicectomy on the extent of colitis in IBD and an associated dysplasia or colorectal cancer.

CCR5-Delta32 mutation is strongly associated with primary sclerosing cholangitis.

CCR5 plays a key role in the distribution of CD45RO+ T cells and contributes to generation of a T helper 1 immune response. CCR5-Delta32 is a 32-bp deletion associated with significant reduction in cell surface expression of the receptor. We investigated the role of CCR5-Delta32 on susceptibility to ulcerative colitis (UC), Crohn's disease (CD) and primary sclerosing cholangitis (PSC). Genotype and allelic association analyses were performed in 162 patients with UC, 131 with CD, 71 with PSC and 419 matched controls. There was a significant difference in CCR5 genotype (OR 2.27, P=0.003) between patients with sclerosing cholangitis and controls. Similarly, CCR5-Delta32 allele frequency was significantly higher in sclerosing cholangitis (17.6%) compared to controls (9.9%, OR 2.47, P=0.007) and inflammatory bowel disease patients without sclerosing cholangitis (11.3%, OR 1.9, P=0.027). There were no significant differences in CCR5 genotype or allele frequency between those with either UC or CD and controls. Genotypes with the CCR5-Delta32 variant were increased in patients with severe liver disease defined by portal hypertension and/or transplantation (45%) compared to those with mild liver disease (21%, OR 3.17, P=0.03). The CCR5-Delta32 mutation may influence disease susceptibility and severity in patients with PSC.

Molecular characterization of the microbial species that colonize human ileal and colonic mucosa by using 16S rDNA sequence analysis.

AIM: The aim of this study was to characterize the bacterial community adhering to the mucosa of the terminal ileum, and proximal and distal colon of the human digestive tract. METHODS AND RESULTS: Pinch samples of the terminal ileum, proximal and distal colon were taken from a healthy 35-year-old, and a 68-year-old subject with mild diverticulosis. The 16S rDNA genes were amplified using a low number of PCR cycles, cloned, and sequenced. In total, 361 sequences were obtained comprising 70 operational taxonomic units (OTU), with a calculated coverage of 82.6%. Twenty-three per cent of OTU were common to the terminal ileum, proximal colon and distal colon, but 14% OTU were only found in the terminal ileum, and 43% were only associated with the proximal or distal colon. The most frequently represented clones were from the Clostridium group XIVa (24.7%), and the Bacteroidetes (Cytophaga-Flavobacteria-Bacteroides) cluster (27.7%). CONCLUSION: Comparison of 16S rDNA clone libraries of the hindgut across mammalian species confirms that the distribution of phylogenetic groups is similar irrespective of the host species. Lesser site-related differences within groups or clusters of organisms, are probable. SIGNIFICANCE AND IMPACT: This study provides further evidence of the distribution of the bacteria on the mucosal surfaces of the human hindgut. Data contribute to the benchmarking of the microbial composition of the human digestive tract.

Protective role of appendicectomy on onset and severity of ulcerative colitis and Crohn's disease.

BACKGROUND AND AIMS: Recent studies on appendicectomy rates in ulcerative colitis and Crohn's disease have generally not addressed the effect of appendicectomy on disease characteristics. The aims of this study were to compare appendicectomy rates in Australian inflammatory bowel disease patients and matched controls, and to evaluate the effect of prior appendicectomy on disease characteristics. METHODS: Patients were ascertained from the Brisbane Inflammatory Bowel Disease database. Controls matched for age and sex were randomly selected from the Australian Twin Registry. Disease characteristics included age at diagnosis, disease site, need for immunosuppression, and intestinal resection. RESULTS: The study confirmed the significant negative association between appendicectomy and ulcerative colitis (odds ratio (OR) 0.23, 95% confidence interval (CI) 0.14-0.38; p<0.0001) and found a similar result for Crohn's disease once the bias of appendicectomy at diagnosis was addressed (OR 0.34, 95% CI 0.23-0.51; p<0.0001). Prior appendicectomy delayed age of presentation for both diseases and was statistically significant for Crohn's disease (p=0.02). In ulcerative colitis, patients with prior appendicectomy had clinically milder disease with reduced requirement for immunosuppression (OR 0.15, 95% CI 0.02-1.15; p=0.04) and proctocolectomy (p=0.02). CONCLUSIONS: Compared with patients without prior appendicectomy, appendicectomy before diagnosis delays disease onset in ulcerative colitis and Crohn's disease and gives rise to a milder disease phenotype in ulcerative colitis.