A meta-analysis of the role of smoking in inflammatory bowel disease

Review article: diet and inflammatory bowel disease--epidemiology and treatment

BACKGROUND

Diet is thought to have an important role in the immunopathogenesis and treatment of inflammatory bowel disease (IBD).

AIM

To identify dietary constituents as risk factors for development of IBD and the therapeutic efficacy of dietary modifications or enteral nutrition in IBD.

METHODS

The Medline and the Cochrane Library were searched for clinical trials and meta-analyses in the scope of diet and nutrition in IBD.

RESULTS

There are many studies in small cohorts of patients that claim that intake of certain diet constituents like fat, refined sugar, fruits, vegetables and fibre affect the expression of IBD. These are often compromised by insufficient data or methodological limitations and do not provide unequivocal evidence to incriminate any particular dietary factor. Among various dietary interventions, none has shown striking efficacy with the possible exception of complete enteral nutrition. Enteral nutrition appears effective in both active and quiescent Crohn's disease (CD), but independent meta-analyses have shown enteral nutrition to be inferior to corticosteroids in the management of active CD, when assessed on an intention-to-treat basis.

CONCLUSIONS

The current levels of knowledge concerning dietary risk factors for IBD, and the therapeutic efficacy of dietary and nutritional interventions need to be supported by well-designed trials in large cohorts of patients.

Association between IL13 polymorphisms and psoriatic arthritis is modified by smoking

Genetic and environmental factors influence the development of psoriasis (Ps) and psoriatic arthritis (PsA). Recently, we reported that three IL13 polymorphisms, rs1800925, rs20541, and rs848, on chromosome 5q31 conferred the risk for Ps. IL13 encodes IL-13, a Th2 cytokine, and rs1800925 and rs20541 confer risk of asthma. Further, smoking may increase the risk of developing Ps. We examined the association between IL13 polymorphisms, smoking, and PsA in two Ps sample sets genotyped for rs1800925, rs20541, and rs848. We found that the minor alleles (rs1800925*T, rs20541*A, and rs848*A) were significantly associated with protection from PsA versus controls, and that no association with Ps is seen when the PsA cases are excluded. This effect was strongest with rs1800925*T (odds ratio (OR) 0.40, P(allelic) 0.000067). The prevalence of PsA in cases with the rs1800925*CT or TT genotype is about half that of those with the CC genotype (15.5 vs 32.1%, P=0.0002). However, smoking appears to abrogate this effect (CT/TT/non-smoker, prevalence of PsA 13%, OR 0.20, P=0.0001; CT/TT/smoker, prevalence 38%, OR 0.88, P=0.74, CC/non-smoker, prevalence 42% (reference), CC/smoker prevalence 47%, OR 1.21, P=0.47). This study suggests that IL13 polymorphisms associate most strongly with PsA and that smoking may modulate this effect.

Smoking behavior in liver transplant recipients

Long-term morbidity and survival after orthotopic liver transplantation (OLT) are to a large degree determined by cardiovascular disease and cancer. Tobacco use is a well-known risk factor for both. The aim of this study was to examine smoking behavior before and after OLT and to define groups at risk for resuming tobacco use after OLT. In addition, we looked for a relation between smoking and morbidity after OLT. All 401 adult patients with a follow-up of at least 2 years after OLT were included. Data were collected from the charts. A questionnaire about smoking habits at 4 time points before and after OLT was sent to all 326 patients alive, and 301 (92%) patients responded. Both before and after OLT, 53% of patients never used tobacco, and around 17% were active smokers. Of the active smokers during the evaluation for OLT, almost one-third succeeded in cessation, often during the waiting time for OLT. Twelve percent of former smokers restarted smoking, mainly after OLT. Tobacco use was the highest in patients with alcoholic liver disease (52% were active smokers before OLT, and 44% were after OLT) and the lowest in patients with primary sclerosing cholangitis (1.4% were active smokers before OLT). At 10 years, the cumulative rate of malignancies was 12.7% in active smokers versus 2.1% in nonsmokers (P = 0.019). No effect on skin cancer or cardiovascular disease was found. In conclusion, smoking is a serious problem after OLT and increases the risk for malignancy. Prevention programs should focus not only on active smokers but also on former smokers.

Effects of light smoking consumption on the clinical course of Crohn's disease

BACKGROUND

Cigarette smoking is associated with a more severe Crohn's disease (CD) course. However, the effect of light consumption is not known. Our aim was to characterize the effect of a light tobacco consumption on the course of CD.

METHODS

We analyzed the course of CD during the period 1995-2007 from data collected in 2795 consecutive patients in whom smoking habits were recorded. Patients were classified as nonsmokers (n = 1420), light smokers (1-10 cigarettes/day; n = 385), heavy smokers (>10 cigarettes/day; n = 638), and intermittent smokers (change in smoking habits; n = 352). Patient-years while smoking were compared to patient-years without smoking. The analyses considered patient-years regarding annual disease activity and therapeutic requirements.

RESULTS

The percentage of years with active disease was 37% in nonsmokers versus 46% in light smokers (P < 0.001; adjusted hazard ratio 1.30 [1.19-1.43]) and 48% in heavy smokers (P < 0.001; adjusted hazard ratio 1.68 [1.57-1.81]), despite an increased use of immunosuppressants in smokers. Hospitalization rates were also increased in both groups of smokers, with 12% in nonsmokers versus 15% in both groups of smokers (P < 0.001 for both comparisons). The annual rate of intestinal resection was 4.5% in nonsmokers, 5.1% in light smokers, and 5.5% in heavy smokers, with a significant difference observed between nonsmokers and heavy smokers only (P < 0.01).

CONCLUSIONS

Light smokers are doing worse than nonsmokers regarding disease activity and the need for immunosuppressants. Complete smoking cessation should be advised in all smokers with CD.

Advances in the pathogenesis and treatment of IBD

Crohn's disease and ulcerative colitis are chronic remitting and relapsing inflammatory bowel diseases. We present a typical case of Crohn's disease in a young woman and discuss potential treatment options. Crohn's disease and ulcerative colitis likely result from interaction of multiple genetic and environmental risk and protective factors. Both are diseases ultimately caused by immune dysregulation. Medical therapy is with mesalamine compounds, corticosteroids, immunomodulators and/or biologics that target TNFalpha signaling or alpha4-integrin-mediated trafficking. Investigational agents include those targeted against other cytokines and costimulatory molecules or designed to promote immune regulation such as exposure to helminths which is a focus of this review.

Breastfeeding and genetic factors in the etiology of inflammatory bowel disease in children

Inflammatory bowel disease is a chronic, debilitating disorder of the gastrointestinal tract. The etiology of inflammatory bowel disease has not been elucidated, but is thought to be multifactorial with both environ-mental and genetic influences. A large body of research has been conducted to elucidate the etiology of inflammatory bowel disease. This article reviews this literature, emphasizing the studies of breastfeeding and the studies of genetic factors, particularly NOD2 polymorphisms.

Helminths and the IBD hygiene hypothesis

Helminths are parasitic animals that have evolved over 100,000,000 years to live in the intestinal track or other locations of their hosts. Colonization of humans with these organisms was nearly universal until the early 20th century. More than 1,000,000,000 people in less developed countries carry helminths even today. Helminths must quell their host's immune system to successfully colonize. It is likely that helminths sense hostile changes in the local host environment and take action to control such responses. Inflammatory bowel disease (IBD) probably results from an inappropriately vigorous immune response to contents of the intestinal lumen. Environmental factors strongly affect the risk for IBD. People living in less developed countries are protected from IBD. The "IBD hygiene hypothesis" states that raising children in extremely hygienic environments negatively affects immune development, which predisposes them to immunological diseases like IBD later in life. Modern day absence of exposure to intestinal helminths appears to be an important environmental factor contributing to development of these illnesses. Helminths interact with both host innate and adoptive immunity to stimulate immune regulatory circuitry and to dampen effector pathways that drive aberrant inflammation. The first prototype worm therapies directed against immunological diseases are now under study in the United States and various countries around the world. Additional studies are in the advanced planning stage.

The risk of developing Crohn's disease after an appendectomy: a meta-analysis

BACKGROUND

Studies exploring the association between appendectomy and Crohn's disease (CD) have reported conflicting findings. We conducted a systematic review of the literature and a meta-analysis to assess the risk of CD following an appendectomy and determine the effect of time between appendectomy and CD diagnosis.

METHODS

MEDLINE was used to identify observational studies evaluating the association between appendectomy and CD. Authors were contacted when data were insufficient. Relative risks (RR) with 95% confidence intervals (CI) were calculated using a random effects model. Studies that analyzed their data by the interval between the appendectomy and the diagnosis of CD were assessed separately. The Woolf chi(2) statistic was used to test for homogeneity. Egger's test was used to evaluate publication bias.

RESULTS

The summary RR estimate for CD following an appendectomy was significantly elevated (RR 1.61, 95% CI 1.28-2.02), though heterogeneity was observed (P < 0.0001). The risk was elevated within the first year following the operation (RR 6.69, 95% CI 5.42-8.25). The risk of CD was also significantly increased 1-4 yr following an appendectomy (RR 1.99, 95% CI 1.66- 2.38); however, after 5 yr or more, the risk fell to baseline levels (RR 1.08, 95% CI 0.99-1.18). Publication bias was not detected (P = 0.2).

CONCLUSION

The meta-analysis demonstrated a significant risk of CD following an appendectomy, though heterogeneity was observed between the studies. The elevated risk early after an appendectomy, which diminishes thereafter, likely reflects diagnostic problems in patients with incipient CD.

New Insights into the Biological and Clinical Significance of Fecal Calprotectin in Inflammatory Bowel Disease

Nowadays, calprotectin, a cytoplasmatic protein, released by activated neutrophilic polymorphonuclear cells (PMN) and/or monocytes-macrophages (MØ), is considered a good indicator of inflammation in several diseases. Accordingly, fecal calprotectin represents a good predictor of clinical relapse in ulcerative colitis (UC) patients, whereas conflicting results have been reported in Crohn's disease (CD) patients. In our study, in 76 IBD patients (29 CD and 47 UC) fecal calprotectin has been evaluated by a commercial ELISA kit. Results demonstrate that levels of this protein in the stool are significantly more elevated in active CD and UC patients than in normal volunteers. In quiescent CD and UC a trend to higher levels of calprotectin than in the normal counterpart is, however, evident. These data suggest that a low-grade inflammation of the intestinal wall is always present in CD and UC patients, which may predict a clinical relapse risk. In the same group of patients calprotectin levels also were analyzed according to sex and age. A trend to higher values of calprotectin was present in male patients with active or quiescent CD than in their female counterparts. Only in UC patients in remission a trend to calprotectin increase was more marked in the male group than in the female counterpart. When CD and UC patients were divided up according to age, calprotectin positivity peaked between 30-39 years in active CD patients, while in quiescent CD maximum positivity was between 40 and 49 years. However, in both active and quiescent UC patients, calprotectin positivity increased with age. The more precocious detectability of fecal calprotectin in CD patients, as a marker of intestinal mucosa inflammation, may be related to the different histopathology of the two diseases (CD versus UC). However, reduced PMN and/or MØ trafficking from peripheral blood to intestinal mucosa with age by effects of chronic treatment should not be ignored in CD patients.

ATG16L1 T300A shows strong associations with disease subgroups in a large Australian IBD population: further support for significant disease heterogeneity

OBJECTIVES

Crohn's disease (CD) and ulcerative colitis (UC) are the two most common forms of inflammatory bowel disease (IBD), representing a significant health-care burden. A variant in the autophagy gene ATG16L1 (T300A) has been newly identified as a CD susceptibility locus by genome-wide association. Our aim was to assess the contribution of T300A in determining disease susceptibility and phenotype in two independent Australian IBD cohorts and explore the relationship between T300A and known CD risk factors (NOD2[nucleotide-binding oligomerization domain containing 2] status and smoking).

METHODS

In total, 669 CD and 543 UC cases, and 1,244 controls (study 1), 154 CD cases and 420 controls (study 2), and 702 unaffected parents from both groups were genotyped. We conducted case-control and family association analyses, and investigated relationships between T300A and disease subgroups and between NOD2 status and cigarette smoking (CD only).

RESULTS

The strong association between CD and T300A was confirmed (P < 0.001), with a two-fold increase in disease risk associated with the GG genotype (odds ratio [OR] 1.96, 95% confidence interval [CI] 1.49-2.58), while ileal CD risk was almost three-fold (OR 2.73, CI 1.87-4.0). ATG16L1 and NOD2 were found to contribute independently to CD risk. A greater than seven-fold increased CD risk was observed for current smokers with a GG genotype (vs nonsmoking AA genotype; P < 0.001, OR 7.65, CI 4.21-13.91). A significant inverse association was found between T300A and UC (P= 0.002). This was strongest for patients with extensive, severe disease.

CONCLUSIONS

We confirm the strong association between T300A and CD, specifically ileal subphenotype, and also report the first strong association of this variant with UC.

The risk of oral contraceptives in the etiology of inflammatory bowel disease: a meta-analysis

OBJECTIVES

Several environmental and genetic factors have been implicated to date in the development of Crohn's disease (CD) and ulcerative colitis (UC). The aim of this study was to provide a quantification of the risk of oral contraceptive pill (OCP) use in the etiology of inflammatory bowel disease.

METHODS

A literature search was performed to identify comparative studies reporting on the association of oral contraceptive use in the etiology of UC and CD between 1983 and 2007. A random-effect meta-analysis was used to compare the incidence of UC or CD between the patients exposed to the OCP and nonexposed patients. The results were adjusted for smoking.

RESULTS

A total of 75,815 patients were reported on by 14 studies, with 36,797 exposed to OCP and 39,018 nonexposed women. The pooled relative risk (RR) for CD for women currently taking the OCP was 1.51 (95% confidence interval [CI] 1.17-1.96, P= 0.002), and 1.46 (95% CI 1.26-1.70, P < 0.001), adjusted for smoking. The RR for UC in women currently taking the OCP was 1.53 (95% CI 1.21-1.94, P= 0.001), and 1.28 (95% CI 1.06-1.54, P= 0.011), adjusted for smoking. The RR for CD increased with the length of exposure to OCP. Moreover, although the RR did not reduce once the OCP was stopped, it was no longer significant once the OCP was stopped (CI contains 1), both for CD and for UC.

CONCLUSIONS

This study provides evidence of an association between the use of oral contraceptive agents and development of IBD, in particular CD. The study also suggests that the risk for patients who stop using the OCP reverts to that of the nonexposed population.

Nicotine primarily suppresses lung Th2 but not goblet cell and muscle cell responses to allergens

Allergic asthma, an inflammatory disease characterized by the infiltration and activation of various leukocytes, the production of Th2 cytokines and leukotrienes, and atopy, also affects the function of other cell types, causing goblet cell hyperplasia/hypertrophy, increased mucus production/secretion, and airway hyperreactivity. Eosinophilic inflammation is a characteristic feature of human asthma, and recent evidence suggests that eosinophils also play a critical role in T cell trafficking in animal models of asthma. Nicotine is an anti-inflammatory, but the association between smoking and asthma is highly contentious and some report that smoking cessation increases the risk of asthma in ex-smokers. To ascertain the effects of nicotine on allergy/asthma, Brown Norway rats were treated with nicotine and sensitized and challenged with allergens. The results unequivocally show that, even after multiple allergen sensitizations, nicotine dramatically suppresses inflammatory/allergic parameters in the lung including the following: eosinophilic/lymphocytic emigration; mRNA and/or protein expression of the Th2 cytokines/chemokines IL-4, IL-5, IL-13, IL-25, and eotaxin; leukotriene C(4); and total as well as allergen-specific IgE. Although nicotine did not significantly affect hexosaminidase release, IgG, or methacholine-induced airway resistance, it significantly decreased mucus content in bronchoalveolar lavage; interestingly, however, despite the strong suppression of IL-4/IL-13, nicotine significantly increased the intraepithelial-stored mucosubstances and Muc5ac mRNA expression. These results suggest that nicotine modulates allergy/asthma primarily by suppressing eosinophil trafficking and suppressing Th2 cytokine/chemokine responses without reducing goblet cell metaplasia or mucous production and may explain the lower risk of allergic diseases in smokers. To our knowledge this is the first direct evidence that nicotine modulates allergic responses.

Clinical course of ulcerative colitis

To provide a review of studies on prognosis in ulcerative colitis by reviewing the relevant population-based cohort studies. On the basis of incidence and population studies, ulcerative colitis has a favourable clinical course, with good quality of life, a chronic course characterized by at least one relapse, and a surgery rate of 30% after 10 years from diagnosis. Patients affected by severe ulcerative colitis have a higher risk of colectomy, and some clinical variables may predict the disease's clinical course. Most patients respond to steroids and only a low percentage become dependent, or non-responders to steroids. Patients who have a long-lasting ulcerative colitis (>10 years) or are affected by an extensive disease have an increased risk of developing colorectal cancer, while those treated with immunosuppressants for long period of time may have an increased risk of developing lymphomas. Data on mortality in ulcerative colitis patients are not homogeneous, but if a real risk exists it is in patients with extensive or severe disease. The evidence that patients with severe ulcerative colitis are often non-smokers may explain why in one study the mortality rate was lower.

Risk factors for ulcerative colitis: A population-based, case-control study in Spain

BACKGROUND

Environmental factors seem to be very important in the aetiology of Ulcerative Colitis (UC), with smoking, contraceptive use, and hygiene being the factors most commonly linked to disease.

AIM

To analyse the association between different risk factors and development of UC in our community.

PATIENTS AND METHODS

This is a case-control, population-based study. The UC population consists of an inception-case population of all cases diagnosed, using Lennard-Jones criteria, in our community from 1st February 1992 to 31st January 1995 that were prospectively included. Controls were selected from healthy population and matched with patients for age, sex and rural/urban habitat. We used the SPSS/PC+ software, EpiInfo and Statistix for statistical analysis, giving the rates as point estimates and 95% confidence intervals (95%CI) or as mean±standard deviation in quantitative variables. For multivariate analysis we used conditional logistic regression.

RESULTS

205 patients were diagnosed of UC. 38 patients (18.5%) with UC were smokers, compared with 84 (40.8%) controls (p<0.001). Smoking behaved as a protector factor for UC (OR=0.55 (CI 95% 0.33-0.92) and ex-smoker acted as a risk factor (OR=1.94 (CI 95% 1.14-3.34). After the multivariate analysis, both associations were maintained. We did not detect statistical differences in the analysis of previous appendectomy, childhood hygiene or oral contraceptive use. Five of the 12 cases with family aggregation had first-degree relatives and 7 of them second-degree relatives. None of the controls had previous IBD history (p=0.0002).

CONCLUSION

Ex-smoking and previous family history of inflammatory bowel disease appeared as risk factors for developing ulcerative colitis while current smoking behaved as a protective factor in this population.

Genetic and environmental factors as predictors of disease severity and extent at time of diagnosis in an inception cohort of inflammatory bowel disease, Copenhagen County and City 2003-2005

BACKGROUND AND AIMS

The etiology of the inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis (UC) remains unknown. We aimed to investigate the influence of genetic, serological, and environmental factors on phenotypic presentation of IBD at diagnosis in a population-based Danish inception cohort from 2003-2005.

METHODS

Three-hundred-forty-seven (62%) of 562 cohort patients were genotyped. ASCA and p/c-ANCA were determined and patients answered a questionnaire concerning environmental factors with possible influence on IBD.

RESULTS

Fourteen percent of CD patients vs. 11% of controls were positive for common CARD15 mutation (ns), whereas more CD patients than healthy controls were homozygous for the OCTN-TC haplotype (p=0.03). ASCA was more common in CD (22%) than UC (14%) (p=0.045) and was related to age and localization of CD. p-ANCA was more frequent in UC (p=0.00001) but was related to pure colonic CD (p=0.0001). Sugar consumption was significantly higher in CD patients than in UC patients (p=0.0001) and more CD patients than UC patients had undergone appendectomy prior to IBD diagnosis (p=0.03). A possible relation between tonsillectomy and disease severity in CD, and a relation between use of oral contraception and disease localization of UC to rectum/left-sided colon were found.

CONCLUSIONS

In this cohort of unselected IBD patients we found a very low frequency of mutations in IBD susceptibility genes and observed a greater impact of ASCA and ANCA than of genetic factors on disease phenotypes. In addition, several environmental factors seemed to influence disease occurrence and disease presentation in both UC and especially CD.

Increased risk of both ulcerative colitis and Crohn's disease in a population suffering from COPD

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation of the airways. In the majority of cases, the inflammation is triggered by tobacco smoke. Smoking also affects the pathogenesis of inflammatory bowel disease (IBD), protecting against ulcerative colitis (UC) and promoting development of Crohn's disease (CD). The present study was undertaken to investigate occurrence of IBD among COPD patients, indicating common inflammatory pathways and shared vulnerability on a genetic basis. The study was designed as a population-based cohort study. All individuals discharged with a diagnosis of COPD from 1987 to 2002 were identified in the Swedish Inpatient Register (n=180,239). Controls and first-degree relatives of both cases and controls were identified using the Multi-Generation Register. Finally, all individuals (n=1,174,557) were compared with the Inpatient Register, identifying discharges with a diagnosis of UC or CD. Hazard ratios (HR) for IBD were determined by Cox proportional hazards regression analysis. COPD patients had a significantly higher risk of both UC (HR 1.83; 95% CI 1.61-2.09) and CD (HR 2.72; 95% CI 2.33-3.18). Among first-degree relatives of COPD patients, there was also an overall increased risk of CD (HR 1.25; 95% CI 1.09-1.43) but not of UC (HR 1.09; 95% CI 0.96-1.23). The kinship of first-degree relatives displayed an increased risk of both UC and CD among siblings (HR 1.49; 95% CI 1.15-1.91 and HR 1.46; 95% CI 1.12-1.89, respectively). The results suggest that COPD and IBD may have inflammatory pathways in common, including genetic variants of genes predisposing for disease.

Evidence for the involvement of infectious agents in the pathogenesis of Crohn's disease

Many advances have been made in the understanding of Crohn's disease (CD) pathogenesis during the last decade. CD is currently seen as a predominantly T-lymphocyte-driven disease characterized by the presence of a complex cocktail of interacting cytokines, chemokines and other mediators produced by a variety of cell types. Prevailing theories of CD pathogenesis suggest that patients' T-lymphocytes are inappropriately activated in the setting of an immune imbalance, which is itself caused by an unfortunate confluence of genetic and environmental factors. The T-cell response then leads to the chronic inflammation characteristic for the disease. Various environmental factors may play a role in the development of CD, but microbes are most consistently implied. This theory is based on epidemiological, clinicopathological, genetic and experimental evidence. Despite the abundance of arguments for the implication of bacteria in the aetiopathogenesis of CD, the precise role of bacteria in this disease still remains elusive. Three not necessarily mutually exclusive theories have been proposed: (1) an unidentified persistent pathogen; (2) an abnormally permeable mucosal barrier leading to excessive bacterial translocation; and (3) a breakdown in the balance between putative "protective" versus "harmful" intestinal bacteria ("dysbiosis"). At present, one cannot exclude with certainty any of these three proposed hypotheses; they may all apply to CD to a certain extent.

Crohn's disease: a review of current treatment with a focus on biologics

Crohn's disease is a debilitating and expensive disease that is growing in incidence in both developing and developed countries. While conventional therapies, such as corticosteroids and immunosuppressants, continue to play a vital role in treating this condition, it is evident that many affected individuals do not respond to therapy or develop intolerable adverse effects. The addition of modern biological therapies to the Crohn's disease armamentarium is providing a change in expectations for disease outcome. Infliximab and adalimumab are currently the only biological agents approved for induction and maintenance treatment in adults (infliximab and adalimumab) and children (infliximab) with Crohn's disease. Furthermore, infliximab has a beneficial effect on perianal fistulas. Other tumour necrosis factor (TNF)-alpha inhibitors, such as certolizumab pegol, also demonstrate promising results in adults with moderate to severe active disease. In addition, adalimumab and certolizumab pegol have shown clinical efficacy in patients who are intolerant to or lose response to infliximab, suggesting that switching between agents may allow response to be maintained over time. The primary safety concerns with TNFalpha inhibitors include increased risk of serious infection (including reactivation of tuberculosis), malignancy (particularly lymphoma) and demyelinating disease. Other agents in development include recombinant human anti-inflammatory cytokines, agents that target pro-inflammatory cytokines and granulocyte-macrophage colony-stimulating factors. Further prospective studies will provide interesting insight into different mechanisms by which factors involved in the pathophysiology of Crohn's disease can be modulated.

Interaction of cigarette smoking with cyclooxygenase-2 on ulcerative colitis-associated neoplasia in mice

The interactions of cigarette smoking with COX-2 on colitis and colitis-associated adenoma formation were studied. Mice were induced with colitis and exposed to cigarette smoke (CS) and/or SC236 (a COX-2 inhibitor). Results indicated that CS did not alter acute colonic inflammation. Addition of SC236 abolished the induction of proliferation and oxidative damage by colitis. Chronic SC236 treatment abolished the promoting effect of CS on colonic adenoma formation, via suppression of COX-2- and VEGF-mediated proliferation and angiogenesis, and reversed bcl-2-mediated inhibition of apoptosis by CS. To conclude, COX-2 inhibitor could be an implication on cancer prevention in smokers with chronic colitis.

Smoking in inflammatory bowel diseases: good, bad or ugly?

Smoking is an important environmental factor in inflammatory bowel disease (IBD), having different effects in ulcerative colitis (UC) and Crohn's disease (CD). A recent meta-analysis partially confirmed previous findings that smoking was found to be protective against ulcerative colitis and, after onset of the disease, might improve its course, decreasing the need for colectomy. However, smoking increases the risk of developing CD and worsens its course, increasing the need for steroids, immunosuppressants and re-operations. Smoking cessation aggravates ulcerative colitis and improves CD. Data are however, largely conflictive as well as the potential mechanisms involved in this dual relationship are still unknown. In this review article, the authors review the role of smoking in inflammatory bowel diseases.

Smoking in inflammatory bowel diseases: good, bad or ugly?

Smoking is an important environmental factor in inflammatory bowel disease (IBD), having different effects in ulcerative colitis (UC) and Crohn's disease (CD). A recent meta-analysis partially confirmed previous findings that smoking was found to be protective against ulcerative colitis and, after onset of the disease, might improve its course, decreasing the need for colectomy. However, smoking increases the risk of developing CD and worsens its course, increasing the need for steroids, immunosuppressants and re-operations. Smoking cessation aggravates ulcerative colitis and improves CD. Data are however, largely conflictive as well as the potential mechanisms involved in this dual relationship are still unknown. In this review article, the authors review the role of smoking in inflammatory bowel diseases.

Strong protective effect of DR3 against ulcerative colitis in the Spanish population

OBJECTIVES

Ulcerative colitis (UC) is a chronic inflammatory disease affecting the colon. Major histocompatibility complex (MHC) on the short arm of human chromosome 6 has been thoroughly studied as a susceptibility locus. However, one of the strongest MHC associations found, that of HLA-DR3 with UC protection, has not been observed in all populations. Our aim in the present study was to evaluate this negative association in a large cohort of Spanish UC patients and controls, and to try to elucidate which, if any, of the diverse DR3 haplotypes (identified by TNFa and b microsatellites, located in the MHC class III region) is most tightly associated (negatively) with the disease.

METHODS

A total of 537 UC patients and 748 healthy controls from Spain were included in the present study. Low-resolution DR genotyping was performed by PCR and hybridization with allele-specific oligonucleotide probes. TNFa and b microsatellites were studied in a subset of samples (279 UC patients and 503 healthy controls) by PCR followed by capillary electrophoresis. DR-TNFa-TNFb haplotypes were estimated by the expectation-maximization algorithm and comparisons were performed by a chi2 test.

RESULTS

After a stepwise procedure, the only DR alleles significantly associated with the disease were DR3 (very strongly, protection) and DR4 (weakly, protection). The strong protective effect of DR3 was evenly distributed among the haplotypes DR3-TNFa1b5, DR3-TNFa2b3, and DR3-TNFother.

CONCLUSIONS

Our results confirm the strong protective effect of DR3 in our population, and suggest that the relevant protective gene is located centromeric to TNFa and TNFb markers in the MHC region.

The role of smoking in Crohn's disease as defined by clinical variables

The development of Crohn's disease (CD) is related to an interaction of genetic and environmental factors, with tobacco smoking being one of the most commonly studied environmental factors. In 1998, the Vienna classification was created to define CD by using three accepted clinical variables: age at diagnosis, disease behavior, and disease location. In this qualitative systematic review, articles examining the relationship between smoking and CD, using variables outlined in the Vienna classification, were identified utilizing multiple health databases. Current smoking was found to be associated with late-onset CD (> or =40 years old) and current smokers were more likely to progress to stricturing or penetrating type CD than were nonsmoking patients. Conflicting evidence exists regarding the relationship between smoking with respect to CD disease location. The Vienna classification is an important tool in permitting comparisons and predicting clinical course among CD cases, especially when smoking status is taken into account.

Appendectomy, smoking habits and the risk of developing ulcerative colitis: a case control study in private practice setting

OBJECTIVES

The strongest environmental factors identified for ulcerative colitis (UC) are cigarette smoking and appendectomy. However, most studies have been performed using case-controls from hospital-based populations. The purpose of this study was to compare the history of previous appendectomy and smoking habits in a group of patients with UC and a control group, followed by gastroenterologists in private practice.

METHODS

We performed a case control study in which 100 physicians recruited UC-patients and age and sex matched controls. Data were collected during a single visit. Based on a standardized questionnaire, UC patients and controls were divided into never, former or current smokers, and into subjects with or without a previous history of appendectomy.

RESULTS

One hundred and ninety eight age- and sex-matched pairs of UC patients and controls were included. The prevalence of appendectomy in the UC-patients and control group was 12% and 46%, respectively. The pairwise-matched OR of ulcerative colitis for previous appendectomy was 0.10 (95% CI, 0.05-0.21) (P<0.0001). The OR for former and never smokers versus current smokers was 2.40 (95% CI 1.31-4.38) (P=0.004). In UC-patients, the OR of family history of UC compared with controls was 2.80 (95% CI, 1.01-7.77) (P=0.048).

CONCLUSIONS

This case-control study confirmed a strong negative correlation between both appendectomy and tobacco smoking, and ulcerative colitis in patients followed-up by gastroenterological practitioners.

A prospective multivariate analysis of clinical factors associated with pouchitis after ileal pouch-anal anastomosis

BACKGROUND & AIMS

Although acute pouchitis (AP) after ileal pouch-anal anastomosis (IPAA) for UC is common and easily treated, chronic pouchitis (CP) remains a difficult management issue. The aim of this study was to identify important clinical risk factors associated with AP or CP.

METHODS

AP and CP were prospectively assessed, and demographic, disease, and treatment characteristics were tabulated. Univariate and multivariate analyses were performed to evaluate associations between AP or CP and potential risk factors.

RESULTS

Two hundred IPAA patients were followed for a median of 24 months (range, 3-117 months). Thirty-six patients (18%) developed AP, and 23 patients (12%) developed CP. On univariate analysis, the use of steroids before colectomy and smoking were associated with the development of AP. CP was associated with male gender, smoking, length of follow-up, extraintestinal manifestations, backwash ileitis, and elevated (450x10(9)/L) platelet count. On multivariate analysis, the following risk factors were found to be independently associated with AP: use of steroids before colectomy (odds ratio [OR], 3.7; 95% confidence interval [CI], 1.5-8.9; P = .004) and smoking (OR, 2.3; 95% CI, 1.1-5.3; P = .04). CP was directly associated with extraintestinal manifestations (OR, 3.5; 95% CI, 1.1-11.1; P = .03), elevated platelet count (OR, 3.1; 95% CI, 1.1-8.9; P = .03), and increased length of follow-up (OR, 1.3; 95% CI, 1.1-1.6; P = .002). Smoking reduced the incidence of CP (OR, 0.2; 95% CI, 0.05-0.74; P = .04).

CONCLUSIONS

Clinical factors associated with AP included use of steroids before colectomy and smoking. Factors directly related to CP were extraintestinal manifestations, elevated platelet count, and length of follow-up after IPAA. Smoking appears to protect against the development of CP.

Estimating risks of common complex diseases across genetic and environmental factors: the example of Crohn disease

BACKGROUND

Progress has been made in identifying mutations that confer susceptibility to complex diseases, with the prospect that these genetic risks might be used in determining individual disease risk.

AIM

To use Crohn disease (CD) as a model of a common complex disorder, and to develop methods to estimate disease risks using both genetic and environmental risk factors.

METHODS

The calculations used three independent risk factors: CARD15 genotype (conferring a gene dosage effect on risk), smoking (twofold increased risk for smokers), and residual familial risk (estimating the effect of unidentified genes, after accounting for the contribution of CARD15). Risks were estimated for high-risk people who are siblings, parents and offspring of a patient with CD.

RESULTS

The CD risk to the sibling of a patient with CD who smokes and carries two CARD15 mutations is approximately 35%, which represents a substantial increase on the population risk of 0.1%. In contrast, the risk to a non-smoking sibling of a patient with CD who carries no CARD15 mutations is 2%. Risks to parents and offspring were lower.

CONCLUSIONS

High absolute risks of CD disease can be obtained by incorporating information on smoking, family history and CARD15 mutations. Behaviour modification through smoking cessation may reduce CD risk in these people.

Smoking and inflammatory bowel disease: trends in familial and sporadic cohorts

BACKGROUND

Ulcerative colitis (UC) and Crohn's disease (CD) result from genetic and environmental factors. Never smoking and formerly smoking increase the risk of UC, whereas smoking exacerbates the course of CD. We sought to define the age-dependent effects of smoking on the development of UC and CD in familial and sporadic cohorts.

METHODS

University of Chicago patients diagnosed with UC or CD between 1990 and 2002 were surveyed about their tobacco use relative to their diagnosis. Smoking trends were used to estimate age-dependent odds ratios and the attributable risks of smoking in the IBD cohort compared to in the general population.

RESULTS

One thousands and thirteen patients were included in the study: 245 with sporadic UC; 216 with sporadic CD; 249 with familial UC; and 303 with familial CD. Being an ex-smoker conferred an increased risk for UC in the 25-44 age group in both the sporadic and familial cohorts, but not in the 45-64 age group in the familial UC cohort. Furthermore, there was no difference in tobacco use between patients with sporadic CD and the general population, although there was a significant increase in smoking in younger patients with familial CD.

CONCLUSIONS

Ex-smokers make up an increasing percentage of older patients diagnosed with UC, accounting for more than 35% of the attributable risk of late onset (>45 years) UC and a large component of the second peak in diagnosis. Current smokers account for a large percentage of patients diagnosed at a younger age with familial CD but not with sporadic CD. Families with IBD should be counseled that early tobacco use significantly increases the risk of developing CD or, if an ex-smoker, UC at a young age.

Effect of smoking on inflammatory bowel disease: Is it disease or organ specific?

Smoking is an important environmental factor in inflammatory bowel disease (IBD) with differing effects in ulcerative colitis (UC) and Crohn’s disease (CD). Never smoking and formerly smoking increase the risk of UC, whereas smoking exacerbates the course of CD. The potential mechanisms involved in this dual relationship are yet unknown. A reasonable assumption is that smoking has different effects on the small and large intestine. This assumption is based on animal and human studies that show that the effects of smoking/nicotine on CD and UC depend on the site of inflammation and not on the type of disease.

The complexity and challenges of genetic counseling and testing for inflammatory bowel disease

Inflammatory bowel disease (IBD) is an umbrella term referring to two chronic idiopathic intestinal diseases: ulcerative colitis (UC) and Crohn's disease (CD). Both UC and CD are characterized by immune activation that leads to symptoms, but the location, severity and behavior of the inflammation varies among individuals and in characteristic ways between UC and CD. A majority of patients with IBD are diagnosed in young adulthood, but the response to therapy is variable and difficult to predict, with some patients demonstrating a prompt and effective remission while others have continuous symptoms that do not respond to existing medical options. Surgery remains a frequent and necessary occurrence among patients with IBD, but in UC it is considered curative, while in CD only temporizing. Clinical observations, epidemiological studies, and molecular genetics have provided strong evidence that both genetic and environmental factors are important determinants for disease susceptibility. In recent years, a number of genes have been identified that associate with CD and UC, although the clinical utility of these discoveries in patients or in susceptible family members has not been determined. Nonetheless, it is hoped that these fundamental advances in our understanding of IBD will lead to better therapies for patients and prevention strategies for those who are susceptible. Effective incorporation of clinical genetic testing for IBD into practice will require appropriate education and counseling.

Risk factors for ulcerative colitis in a Chinese population: an age-matched and sex-matched case-control study

BACKGROUND AND AIMS

Cigarette smoking, alcohol use, appendectomy, and family history of inflammatory bowel disease (IBD) have all been shown to be associated with IBD, but there were no reports of risk factors for IBD in a Chinese population in which the incidence of IBD is increasing during the past decade. We conducted a case-control study to examine associations between previously reported environmental risk factors and development of ulcerative colitis (UC) in Wuhan city, central China.

METHODS

A total of 177 patients with UC and 177 age-matched and sex-matched controls were prospectively studied in Wuhan city from January 2004 to December 2004. An age-matched and sex-matched case-control study was conducted to assess the role of smoking, alcohol use, appendectomy, and other potential risk factors in the development of UC by a detailed questionnaire.

RESULTS

Smoking was a protective factor and exsmoking is a risk factor for UC [compared with nonsmokers, smokers: odds ratios (OR)=0.28, 95% confidence intervals (CI): 0.16-0.48, P=0.0001; exsmokers: OR=4.36, 95%CI: 1.46-13.04, P=0.008]. Positive family history of IBD was a risk factor (OR=4.35, 95%CI: 1.21-15.71, P=0.025) whereas appendectomy was a protective factor (OR=0.24, 95%CI: 0.07-0.86, P=0.028) for UC. There were no significant associations between UC and other factors examined.

CONCLUSIONS

Although the incidence of UC in Chinese is relatively lower than that in white, the same risk factors for UC that were reported in white populations were associated with Chinese UC patients. Specifically, smoking was a protective factor for UC and exsmoking was associated with an increase risk of UC in a Chinese population. Family history of IBD was shown to be a risk for UC, whereas appendectomy was associated with a low risk for UC.

Current therapy of inflammatory bowel disease in children

Ulcerative colitis (UC) and Crohn disease (CD) are chronic intestinal inflammatory diseases that can present as bloody diarrhea, abdominal pain, and malnutrition. Collectively, these disorders are referred to as inflammatory bowel disease (IBD). All patients with IBD share a common pathophysiology. However, there are a number of developmental, psychosocial, and physiologic issues that are unique to the approximate, equals 20% of patients that present during childhood or adolescence. These include the possibility of disease-induced delays in linear growth or physical development, differences in drug dosing, and the changes in social and cognitive development that occur as children move from school-age years into adolescence and early adulthood. Gastroenterologists caring for these children must therefore develop an optimal regimen of pharmacologic therapies, nutritional management, psychologic support, and properly timed surgery (when necessary) that will maintain disease remission, minimize disease and drug-induced adverse effects, and optimize growth and development. This article reviews current approaches to the management of patients with UC and CD and highlights issues specific to the treatment of children with IBD. The principal medical therapies used to induce disease remission in patients with UC are aminosalicylates (for mild disease), corticosteroids (for moderate disease), and cyclosporine (ciclosporin) (for severe disease). If a patient responds to the induction regimen, maintenance therapies that are used to prevent disease relapse include aminosalicylates, mercaptopurine, and azathioprine. Colectomy with creation of an ileal pouch anal anastomosis (J pouch) has become the standard of care for patients with severe or refractory colitis and results in an improved quality of life in most patients. Therefore, the risks associated with using increasingly potent immunosuppressant agents must be balanced in each case against a patient's desire to retain their colon and avoid a temporary or potentially permanent ileostomy. Decisions about drug therapy in the management of patients with CD are more complex and depend on both the location (e.g. gastroduodenal vs small intestinal vs colonic), as well as the behavior of the disease (inflammatory/mucosal vs stricturing vs perforating) in a given patient. Induction therapies for CD typically include aminosalicylates and antibiotics (for mild mucosal disease), nutritional therapy (including elemental or polymeric formulas), corticosteroids (for moderate disease), and infliximab (for corticosteroid-resistant or fistulizing disease). Aminosalicylates, mercaptopurine, azathioprine, methotrexate, and infliximab can be used as maintenance therapies. Because surgical treatment of CD is not curative, it is typically reserved for those patients either with persistent symptoms and disease limited to a small section of the intestine (e.g. the terminal ileum and cecum) or for the management of complications of the disease including stricture or abdominal abscess. When surgery is necessary, maintenance medications administered postoperatively will postpone recurrence. Patients with UC and CD are at risk for the development of micronutrient deficiencies (including folate, iron, and vitamin D deficiencies) and require close nutritional monitoring. In addition, patients with UC and CD involving the colon are at increased risk of developing colon cancer, and should be enrolled into a colonoscopy surveillance program after 8-10 years of disease duration.

Differences in yeast intolerance between patients with Crohn's disease and ulcerative colitis

PURPOSE

Alimentary factors, especially those modifying the intestinal flora, may influence the course of inflammatory bowel disease. It is known that T and B cells of patients with Crohn's disease can be stimulated with the yeast antigen, mannan. We evaluated the impact of eating habits with special respect to food containing yeast on the course of inflammatory bowel disease.

METHODS

Questionnaires were sent to 180 German-speaking patients of the Inflammatory Bowel Disease Outpatient Clinic at the University Hospital Bern, Switzerland. The following information was obtained by the questionnaires: (1) course of disease, (2) eating habits, (3) environmental data, and (4) inflammatory bowel disease questionnaire. The survey was anonymous.

RESULTS

A total of 145 patients (80.5 percent 95 with Crohn's disease, and 50 with ulcerative colitis) responded. Food items containing yeast were better tolerated by patients with ulcerative colitis than by patients with Crohn's disease. A significant difference between the two groups was observed concerning food containing raw yeast (dough, P = 0.04; and pastry, P = 0.001).

CONCLUSIONS

Food items containing raw yeast led to more frequent problems for patients with Crohn's disease than for patients with ulcerative colitis. This observation supports our previous data, which showed the stimulatory effect of the yeast antigen, mannan, on B and T cells of patients with Crohn's disease but not of controls.

Exploitation of the nicotinic anti-inflammatory pathway for the treatment of epithelial inflammatory diseases

Discoveries in the first few years of the 21st century have led to an understanding of important interactions between the nervous system and the inflammatory response at the molecular level, most notably the acetylcholine (ACh)-triggered, α7-nicotinic acetylcholine receptor (α7nAChR)-dependent nicotinic anti-inflammatory pathway. Studies using the α7nAChR agonist, nicotine, for the treatment of mucosal inflammation have been undertaken but the efficacy of nicotine as a treatment for inflammatory bowel diseases remains debatable. Further understanding of the nicotinic anti-inflammatory pathway and other endogenous anti-inflammatory mechanisms is required in order to develop refined and specific therapeutic strategies for the treatment of a number of inflammatory diseases and conditions, including periodontitis, psoriasis, sarcoidosis, and ulcerative colitis.

Influences of age, gender, smoking, and family history on autoimmune thyroid disease phenotype

CONTEXT

Both genetic and environmental factors contribute to susceptibility to Graves' disease (GD) and Hashimoto's thyroiditis (HT), as well as disease manifestations.

OBJECTIVE

The objective of the study was to define how endogenous/environmental factors contribute to variation in phenotype.

DESIGN/SETTING

This was a multicenter cohort study. PATIENTS/OUTCOME MEASURES: We prospectively collected clinical/biochemical data as part of the protocol for a United Kingdom DNA collection for GD and HT. We investigated, in 2805 Caucasian subjects, whether age at diagnosis, gender, family history (FH), smoking history, and presence of goiter influenced disease manifestations.

RESULTS

For 2405 subjects with GD, the presence of goiter was independently associated with disease severity (serum free T4 at diagnosis) (P < 0.001). Free T4 (P < 0.05) and current smoking (P < 0.001) were both independent predictors of the presence of ophthalmopathy. Approximately half of those with GD (47.4% of females, 40.0% of males) and HT (n = 400) (56.4% of females, 51.7% of males) reported a FH of thyroid dysfunction. In GD, a FH of hyperthyroidism in any relative was more frequent than hypothyroidism (30.1 vs. 24.4% in affected females, P < 0.001). In HT, a FH of hypothyroidism was more common than hyperthyroidism (42.1 vs. 22.8% in affected females, P < 0.001). For GD (P < 0.001) and HT (P < 0.05), a FH was more common in maternal than paternal relatives. The reporting of a parent with thyroid dysfunction (hyper or hypo) was associated with lower median age at diagnosis of both GD (mother with hyperthyroidism, P < 0.001) and HT (father with hypothyroidism, P < 0.05). In GD and HT, there was an inverse relationship between the number of relatives with thyroid dysfunction and age at diagnosis (P < 0.01).

CONCLUSIONS

Marked associations among age at diagnosis, disease severity, goiter, ophthalmopathy, smoking, and FH provide evidence for interactions between genetic and environmental/endogenous factors; understanding these may allow preventive measures or better tailoring of therapies.

Nicotine and serotonin in immune regulation and inflammatory processes: a perspective

Nicotine and serotonin modulate the innate and adaptive immune responses and the inflammatory states. Several nicotinic cholinergic and serotonergic receptor subtypes have been characterized in B and T lymphocytes, monocytes, macrophages, and dendritic cells. The use of knockout mice has allowed a better characterization of nicotinic receptors and their role in anti-inflammatory processes in these cells. Cytokines play a crucial role in controlling inflammatory reactions. Nicotine and serotonin have been reported to regulate cytokine release. Cholinergic mechanisms also play an important role in inflammation through endogenous acetylcholine. Nicotine mimics this effect by activating the cholinergic anti-inflammatory pathways. New concepts of reciprocal interactions between nicotine and serotonin are emerging. The role of nicotine as an anti-inflammatory agent has been established, whereas that of serotonin remains more controversial.

Helminths and mucosal immune modulation

Geographic and ethnic variations in ulcerative colitis and Crohn's disease frequency suggest that environmental factors affect disease risk. Prevention of parasitic worms (helminths) through improved hygiene may be one factor leading to the increased disease prevalence. Helminths alter host mucosal and systemic immunity. Animals exposed to helminths are protected from experimental colitis and other immunological diseases, and helminthic colonization can be used to treat ongoing murine and human disease. Helminths induce mucosal T cells to make Th2 and regulatory cytokines. Helminth-induced mucosal IL4, TGFbeta, and IL10 likely are part of the protective process. Helminths affect pathways of innate immunity like TLR4 expression and function. Worms also induce various regulatory-type T-cell subsets in the gut that limit effector T-cell growth and function. These effects of once ever-present helminths may have protected people from immune-mediated illnesses like inflammatory bowel disease.

Smoking and inflammatory bowel disease: a meta-analysis

OBJECTIVE

To assess whether there is a true effect of smoking on the 2 most prevalent forms of inflammatory bowel disease (IBD): Crohn disease (CD) and ulcerative colitis (UC).

METHODS

For this meta-analysis, we searched multiple health care databases, including MEDLINE and EMBASE (January 1980 to January 2006), to examine the relationship between smoking and IBD. Keywords searched included smoking, Inflammatory bowel disease, Crohn's disease, and ulcerative colitis. Data were abstracted using predefined inclusion and exclusion criteria. An odds ratio (OR) was recalculated for each study using the random-effects model, and a combined OR was calculated.

RESULTS

A total of 245 articles were obtained through an electronic search of health care databases. Thirteen studies examined the relationship between UC and smoking, whereas 9 examined the relationship between CD and smoking. We found evidence of an association between current smoking and CD (OR, 1.76; 95% confidence interval [CI], 1.40-2.22) and former smoking and UC (OR, 1.79; 95% CI, 1.37-2.34). Current smoking had a protective effect on the development of UC when compared with controls (OR, 0.58; 95% CI, 0.45-0.75).

CONCLUSION

This is the first meta-analysis, to our knowledge, to evaluate the relationship between smoking and IBD using accepted quality standards for meta-analysis reporting. Our meta-analyses confirm that smoking is an important environmental factor in IBD with differing effects in UC and CD. By using predefined inclusion criteria and testing for homogeneity, the current analysis provides an estimate of the effect of smoking on both these forms of IBD.

Medical management of left-sided ulcerative colitis and ulcerative proctitis: critical evaluation of therapeutic trials

BACKGROUND

The goal of this work was to critically evaluate the published studies on the treatment of ulcerative proctitis (UP) and left-sided ulcerative colitis (L-UC). The results of this review provided the content for the accompanying treatment guidelines, Clinical Guidelines for the Medical Management of Left-sided Ulcerative Colitis and Ulcerative Proctitis: Summary Statement.

METHODS

All English language articles published between 1995 and September 2005 were identified through a comprehensive literature search using OVID and PubMed. The quality of the data supporting or rejecting the use of specific therapies was categorized by a data quality grading scale. An "A+" grade was assigned to treatment supported by multiple high-quality randomized controlled trials with consistent results, whereas a "D" grade was given to therapy supported only by expert opinion. The therapeutic efficacy of a treatment was defined by its success in treating UP and L-UC compared with placebo. A medication was ranked as "excellent" if it was specifically studied for UP and L-UC and had consistently positive results compared with placebo or another agent. Quality and efficacy scores were agreed on by author consensus.

RESULTS

For the acute treatment of UP or L-UC, the rectally administered corticosteroids and mesalazine (5-ASA), either alone or in combination with oral 5-ASAs, are the most effective therapy: evidence quality, A+; efficacy, excellent. Only rectally administered 5-ASA received an A+/excellent rating for maintenance of remission. Infliximab received an A+ grade for induction and maintenance of remission but only a "good" rating because the studies were performed in all UC, not specifically UP or L-UC.

CONCLUSIONS

This critical evaluation of treatment provides a "report card" on medications available for the management of patients with UP and L-UC. The guidelines should provide a useful reference and supplement for physicians treating UC patients.

Environmental factors in inflammatory bowel disease: a co-twin control study of a Swedish-Danish twin population

BACKGROUND

Genetics and environmental factors are implicated in the etiology of inflammatory bowel disease (IBD). We studied environmental factors in a population-based Swedish-Danish twin cohort using the co-twin control method.

SUBJECTS AND METHODS

A questionnaire was sent to 317 twin pairs regarding markers of exposures in the following areas: infections/colonization and diet as well as smoking, appendectomy, and oral contraceptives. Odds ratios (OR) were calculated by conditional logistic regression. When confounding appeared plausible, multivariate conditional logistic regression was added. The questions were also divided into topic groups, and adjustment was made for multiple testing within each of the groups.

RESULTS

The response rate to the questionnaire was 83%. In consideration of the study design, only discordant pairs were included (Crohn's disease [CD], n = 102; ulcerative colitis [UC], n = 125). Recurrent gastrointestinal infections were associated with both UC (OR, 8.0; 95% confidence interval [CI], 1.0-64) and CD (OR, 5.5; 95% CI, 1.2-25). Hospitalization for gastrointestinal infections was associated with CD (OR, 12; 95% CI, 1.6-92). Smoking was inversely associated with UC (OR, 0.4; 95% CI, 0.2-0.9) and associated with CD (OR, 2.9; 95% CI, 1.2-7.1).

CONCLUSIONS

The observed associations indicate that markers of possible infectious events may influence the risk of IBD. Some of these effects might be mediated by long-term changes in gut flora or alterations in reactivity to the flora. The influence of smoking in IBD was confirmed.

Inflammatory bowel disease--environmental modification and genetic determinants

Inflammatory bowel disease (IBD) is a complex disease, controlled by multiple risk factors that evolve and interact together. In a genetically susceptible host, there are multiple processing steps controlled by the host and the environment, from environmental exposure to the clinical and biological expression of IBD-related phenotypes. This article discusses the recent genetic discoveries, along with the proposed environmental risk factors that have been implicated in IBD. Technical advances of the HapMap project and the promise of whole genome association scans have given hopes for clarifying gene-environmental interactions in IBD that ultimately lead to a clearer understanding of the pathogenesis.

Crohn's disease is associated with polymorphism of CARD15/NOD2 gene in a Hungarian population

Crohn's disease (CD) is commonly classified as an immune-mediated disorder, but genetic and environmental factors seem to be important in its pathogenesis. Mutations within the CARD15/NOD2 gene have been associated with CD in the Caucasian population. The aim of our work was to investigate the allele frequency and clinical impact of the three common mutations in Hungarian CD patients and healthy controls. Seventy-four CD patients and 107 controls were examined. The genotyping of the three common CARD15/NOD2 mutations (Arg702Trp, Gly908Arg, and Leu1007fsinsC) was carried out by restriction fragment length polymorphism (RFLP) and amplification refractory mutation system (ARMS) techniques. The demographic and clinical parameters were correlated with chi(2) analysis. The overall prevalence of CARD15/NOD2 mutations in the Hungarian CD patients (33.78%) was significantly higher than in healthy control individuals (16.23%) (P < 0.025). The allele frequency of the Gly908Arg mutation did not differ, but the Arg702Trp and Leu1007fsinsC mutation were more common in CD patients than in controls. The onset of CD occurs about three years earlier in CARD15/NOD2 carriers. Carriage of the Arg702Trp and Leu1007fsinsC allele within the CARD15/NOD2 gene is associated with CD. These data are in line with similar findings showing a role of the CARD15/NOD2 protein in the etiopathogenesis of CD. The genotyping of these mutations might be used to identify high-risk patients.

Acute gastroenteritis is followed by an increased risk of inflammatory bowel disease

BACKGROUND & AIMS

Bacterial intestinal infections have been implicated as a possible cause of exacerbation of inflammatory bowel disease (IBD). We explored the relationship between infectious gastroenteritis and the occurrence of IBD using data from the General Practice Research Database.

METHODS

A cohort of patients aged 20-74 years with an episode of acute infectious gastroenteritis (n = 43,013) was identified. From the same source population, an age-, sex-, and calendar time-matched control group free of gastroenteritis was sampled (n = 50,000). Both cohorts were followed up for a mean duration of 3.5 years.

RESULTS

The estimated incidence rate of IBD was 68.4 per 100,000 person-years after an episode of gastroenteritis and 29.7 per 100,000 person-years in the control cohort. The hazard ratio of IBD was 2.4 (95% confidence interval [CI], 1.7-3.3) in the gastroenteritis cohort compared with the control cohort, and the excess risk was greater during the first year after the infective episode (hazard ratio, 4.1; 95% CI, 2.2-7.4). The relative risk of developing Crohn's disease in the gastroenteritis cohort was greater than that of ulcerative colitis, especially during the first year after the infective episode (hazard ratio, 6.6; 95% CI, 1.9-22.4).

CONCLUSIONS

Our results are compatible with the hypothesis that infectious agents causing an episode of infectious gastroenteritis could play a role in the initiation and/or exacerbation of IBD.

Environment as a Critical Factor for the Pathogenesis and Outcome of Gastrointestinal Disease: Experimental and Human Inflammatory Bowel Disease and Helicobacter-Induced Gastritis

Environmental factors play an important role in the manifestation, course, and prognosis of diseases of the gastrointestinal tract such as inflammatory bowel disease (IBD) and Helicobacter pylori-induced gastritis. These two disease complexes were chosen for a discussion of the contribution of environmental factors to the disease outcome in humans and animal models. Dissecting complex diseases like IBD and Helicobacter-induced gastritis has shown that the outcome of disease depends on the allelic constellation of a host and the microbial and physical environments. Host alleles predisposing to a disease in one genomic and/or environmental milieu may not be deleterious in other constellations; on the other hand, microbes can have different effects in different hosts and under different environmental conditions. The impact of the complex interaction between host genetics and environmental factors, particularly microflora, also underlines the importance of a defined genetic background and defined environments in animal studies and is indicative of the difficulties in analyzing complex diseases in humans.

Role of the IBD5 susceptibility locus in the inflammatory bowel diseases

The field of inflammatory bowel disease genetics plays a leading role in the genetics of complex traits. One of the first genetic loci for a complex trait to be identified by genome-wide linkage scans and confirmed by multiple studies was IBD1 for Crohn's disease. Shortly after this initial success, a second susceptibility locus, the IBD5 risk haplotype, was discovered and unequivocally replicated. In this review, we examine the genetics and potential functional implications of the IBD5 locus on disease susceptibility, prognosis, classification, and treatment. In addition, we discuss the challenges faced when the region identified by association contains multiple genes that are not easily separated by recombination-the primary tool of the human geneticist.