Hygiene hypothesis in inflammatory bowel disease: A criticalreview of the literature

The hygiene hypothesis is thought to be a significant contributor to the growing incidence of inflammatory bowel disease (IBD) around the world, although the evidence for specific factors that underlie the hygiene hypothesis in IBD is unclear. We aimed to systematically review the literature to determine which hygiene-related factors are associated with the development of IBD. Publications identified from a broad based MEDLINE and Current Contents search between 1966 and 2007 on key terms relevant to the 'hygiene hypothesis' and IBD including H pylori exposure, helminths, cold chain hypothesis, measles infection and vaccination, antibiotic use, breastfeeding, family size, sibship, urban upbringing, day care attendance and domestic hygiene were reviewed. The literature suggests that the hygiene hypothesis and its association with decreased microbial exposure in childhood probably plays an important role in the development of IBD, although the strength of the supporting data for each of the factors varies considerably. The most promising factors that may potentially be associated with development of IBD include H pylori exposure, helminths, breastfeeding and sibship. However, the vast majority of studies in this area are plagued by serious methodological shortcomings, particularly the reliance on retrospective recall of information making it difficult to truly ascertain the importance of a 'hygiene hypothesis' in IBD. The 'hygiene hypothesis' in IBD is an important area of research that may give clues to the aetiology of this disease. Directions for future research are recommended.

Dysregulation of innate immunity in ulcerative colitis patients who fail anti-tumor necrosis factor therapy

AIM To study the innate immune function in ulcerative colitis(UC) patients who fail to respond to anti-tumor necrosis factor(TNF) therapy.METHODS Effects of anti-TNF therapy, inflammation and medications on innate immune function were assessed by measuring peripheral blood mononuclear cell(PBMC) cytokine expression from 18 inflammatory bowel disease patients pre- and 3 mo post-anti-TNF therapy. Toll-like receptor(TLR) expression and cytokine production post TLR stimulation was assessed in UC "responders"(n = 12) and "non-responders"(n = 12) and compared to healthy controls(n = 12). Erythrocyte sedimentation rate(ESR) and C-reactive protein(CRP) levels were measured in blood to assess disease severity/activity and inflammation. Pro-inflammatory(TNF, IL-1β, IL-6), immuno-regulatory(IL-10), Th1(IL-12, IFNγ) and Th2(IL-9, IL-13, IL-17A) cytokine expression was measured with enzyme-linked immunosorbent assay while TLR cellular composition and intracellular signalling was assessed with FACS.RESULTS Prior to anti-TNF therapy, responders and nonresponders had similar level of disease severity and activity. PBMC's ability to respond to TLR stimulation was not affected by TNF therapy, patient's severity of the disease and inflammation or their medication use. At baseline, non-responders had elevated innate but not adaptive immune responses compared to responders(P < 0.05). Following TLR stimulation, nonresponders had consistently reduced innate cytokine responses to all TLRs compared to healthy controls(P < 0.01) and diminished TNF(P < 0.001) and IL-1β(P < 0.01) production compared to responders. This innate immune dysfunction was associated with reduced number of circulating plasmacytoid dendritic cells(p DCs)(P < 0.01) but increased number of CD4+ regulatory T cells(Tregs)(P = 0.03) as well as intracellular accumulation of IRAK4 in non-responders following TLR-2,-4 and-7 activation(P < 0.001). CONCLUSION Reduced innate immunity in non-responders may explain reduced efficacy to anti-TNF therapy. These serological markers may prove useful in predicting the outcome of costly anti-TNF therapy.

Associations between NOD2/CARD15 genotype andphenotype in Crohn’s disease-Are we there yet?

There have been multiple NOD2/CARD15 genotype- phenotype analyses undertaken in patients with Crohn’s disease since the gene’s discovery in 2001. This review focuses on the major published series based upon their size and on the presence of specific clinical and genetic information provided in the published material from 2001 to 2005. Twelve studies provided raw data to carry out comparisons of disease location while ten studies included analysis of NOD2/CARD15 genotypes. NOD2/CARD15 variant frequency in ileal disease did not differ significantly among studies, whereas a comparison of disease location demonstrated highly significant differences among studies. Meta-analysis confirmed significant associations between NOD2/CARD15 variants and both ileal and ileocolonic disease locations, and with both stricturing and penetrating forms of disease behavior. This review underlines the significant phenotypic differences that exist among populations, including similar ethnic groups, and has demonstrated the need for further studies of patients with long-term “inflammatory” Crohn’s disease.

Vedolizumab for ulcerative colitis: Real world outcomes from a multicenter observational cohort of Australia and Oxford

BACKGROUND Vedolizumab(VDZ),a humanised monoclonal antibody that selectively inhibits alpha4-beta7 integrins is approved for use in adult moderate to severe ulcerative colitis(UC)patients.AIM To assess the efficacy and safety of VDZ in the real-world management of UC in a large multicenter cohort involving two countries and to identify predictors of achieving remission.METHODS A retrospective review of Australian and Oxford,United Kingdom data for UC patients.Clinical response at 3 mo,endoscopic remission at 6 mo and clinical remission at 3,6 and 12 mo were assessed.Cox regression models and Kaplan Meier curves were performed to assess the time to remission,time to failure and the covariates influencing them.Safety outcomes were recorded.RESULTS Three hundred and three UC patients from 14 centres in Australia and United Kingdom,[60%n=182,anti-TNF naïve]were included.The clinical response was 79%at 3 mo with more Australian patients achieving clinical response compared to Oxford(83%vs 70%P=0.01).Clinical remission for all patients was 56%,62%and 60%at 3,6 and 12 mo respectively.Anti-TNF naive patients were more likely to achieve remission than exposed patients at all the time points(3 mo 66%vs 40%P<0.001,6 mo 73%vs 46%P<0.001,12 mo 66%vs 51%P=0.03).More Australian patients achieved endoscopic remission at 6 mo compared to Oxford(69%vs 43%P=0.01).On multi-variate analysis,anti-TNF naïve patients were 1.8(95%CI:1.3-2.3)times more likely to achieve remission than anti-TNF exposed(P<0.001).32 patients(11%)had colectomy by 12 mo.CONCLUSION VDZ was safe and effective with 60%of UC patients achieving clinical remission at 12 mo and prior anti-TNF exposure influenced this outcome.