The relationship between heritability and smoking habits in Crohn's disease. Italian Cooperative Study Group

Ethnic Differences in the Smoking-related Risk of Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

BACKGROUND AND AIMS

The association between smoking and inflammatory bowel disease [IBD] relies on old meta-analyses including exclusively non-Jewish White populations. Uncertainty persists regarding the role of smoking in other ethnicities.

METHODS

We systematically searched Medline/PubMed, Embase, and Scopus for studies examining tobacco smoking and the risk of developing IBD, ie, Crohn's disease [CD] or ulcerative colitis [UC]. Two authors independently extracted study data and assessed each study's risk of bias. We examined heterogeneity and small-study effect, and calculated summary estimates using random-effects models. Stratified analyses and meta-regression were employed to study the association between study-level characteristics and effect estimates. The strength of epidemiological evidence was assessed through prespecified criteria.

RESULTS

We synthesised 57 studies examining the smoking-related risk of developing CD and UC. Non-Jewish White smokers were at increased risk of CD (29 studies; relative risk [RR]: 1.95, 95% confidence interval [CI]: 1.69‒2.24; moderate evidence). No association was observed in Asian, Jewish. and Latin-American populations [11 studies; RR: 0.97; 95% CI: 0.83-1.13], with no evidence of heterogeneity across these ethnicities. Smokers were at reduced risk of UC [51 studies; RR: 0.55, 95% CI: 0.48-0.64; weak evidence] irrespectively of ethnicity; however, cohort studies, large studies, and those recently published showed attenuated associations.

CONCLUSIONS

This meta-analysis did not identify any increased risk of CD in smokers in ethnicities other than non-Jewish Whites, and confirmed the protective effect of smoking on UC occurrence. Future research should characterise the genetic background of CD patients across different ethnicities to improve our understanding of the role of smoking in CD pathogenesis.

Risk factors for inflammatory bowel diseases according to the "hygiene hypothesis": a case-control, multi-centre, prospective study in Southern Italy

BACKGROUND

Ulcerative colitis (UC) and Crohn's disease (CD) are inflammatory bowel diseases (IBD) of unknown aetiology. The 'hygiene hypothesis' (HH) suggests that several hygiene-related factors may have contributed to the increased incidence of IBD. The aim of the study was to evaluate risk factors for IBD related to HH in a cohort of IBD patients from the south of Italy.

METHODS

We prospectively performed a one-year, questionnaire-based, case-control, multi-centre study focusing on the principal risk factors for IBD according to HH. We investigated the main surrogate markers of HH (helmintic infections and antibiotics in childhood; breastfeeding; family size/sibship;urban upbringing; personal and domestic hygiene in childhood) in UC and CD patients, in comparison with a control group of healthy subjects. In addition, the traditional risk factors for IBD were also recorded.

RESULTS

The study population included 527 cases of UC, 468 CD and 562 controls. None of the surrogate risk factors of HH was significantly associated with IBD. On the contrary, the traditional risk factors confirmed their statistical significance in this IBD population. Familial aggregation: OR 4.07 for UC; OR 4.83 for CD; smoking: OR 0.38 for UC; OR 1.40 for CD; appendectomy: OR 0.28 for UC; OR 1.61 for CD.

CONCLUSION

Even though risk factors associated to the HH have been proposed as a possible explanation for the increasing calendar trend of IBD incidence, their role does not appear to be statistically significant. Familial aggregation, smoking habits and appendectomy still remain the main risk factors associated with IBD.

Concordance for IBD among twins compared to ordinary siblings--a Norwegian population-based study

AIMS

Comparing the risk to develop concordant disease among twins with inflammatory bowel disease (IBD) to ordinary siblings. Moreover, clinical characteristics of IBD and the association between perinatal factors and IBD, were evaluated.

METHODS

Patients with IBD, enrolled from an incidence study between 1990 and 1994, and the twins were identified from the Norwegian national birth registry, which was established in 1967.

RESULTS

Eight monozygotic and 16 dizygotic pairs, in which at least one twin reported a positive history of IBD were compared to 84 patients with Crohn's disease (CD) and 87 patients with ulcerative colitis (UC) from the incidence study. The relative risks for concordant disease in monozygotic pairs were estimated to 95.4 (95% CI: 76.3, 114.6) and 49.5 (95% CI: 35.7, 63.3) for CD and UC, respectively. The corresponding risks in dizygotic pairs were 42.4 (95% CI: 29.6, 55.2) and 0.0. Among ordinary siblings of CD and UC the risks for concordance were 22.7 (95% CI: 13.3, 32.1) and 4.6 (95% CI: 0.4, 8.7), respectively. Stricturing disease was significantly higher in twins with CD compared to incidental cases. The first-born twin in pairs discordant for disease, 12 out of 19 (63.2%), tended to be affected by IBD (p=0.10).

CONCLUSION

Genetic factors influence the development of IBD and fibrostenotic disease in CD. The increased risk for concordant disease among dizygotic twins compared to ordinary siblings, at least in CD, might underscore the importance of shared environment in utero or in childhood.

Smoking and inflammatory bowel diseases: what in smoking alters the course?

Epidemiological studies provide strong evidence to confirm the correlation between cigarette smoking and inflammatory bowel diseases. This relationship is proved to be positive in Crohn's disease and negative in ulcerative colitis. What in smoking alters the course of inflammatory bowel diseases is still a mystery. Different smoking parts have different and may be opponent actions. Smoking has dual effects. Some of its activities are, sometimes, constructive as they are working in an antagonistic manner to the mechanism of the disease, such as reducing rectal blood flow and accordingly less recruitments of inflammatory mediators to the area of inflammation, enhancement of mucosal production, and consequently, strengthening the membranes, and inhibition of pro-inflammatory mediators' liberation and activity in subjects with ulcerative colitis. Yet the outcome of smoking actions may be affected by the existence of other cofactors. Odd factors, such as shortage of zinc in subjects with Crohn's disease, may facilitate liberation of pro-inflammatory mediators and their activities and accordingly exacerbates symptoms.

Is the personality characteristic "impulsive sensation seeking" correlated to differences in current smoking between ulcerative colitis and Crohn's disease patients?

BACKGROUND

Crohn's disease (CD) is associated with smoking, while ulcerative colitis (UC) is largely a disease of nonsmokers. We aimed to test whether the smoking-linked personality characteristic "impulsive sensation seeking" (ImpSS) is correlated to the differences in smoking in inflammatory bowel disease (IBD).

METHODS

In 185 IBD patients, the General Health Questionnaire and the Zuckerman-Kuhlman Personality Questionnaire (ZKPQ) were administered. The Fagerstrom Test for Nicotine Dependence was used to assess smokers' nicotine dependence.

RESULTS

CD patients were twice as likely to be active smokers than UC patients. CD patients presented higher ImpSS scores than UC patients, but the differences became nonsignificant after adjustment for age, gender, education and psychological distress. Multivariate analyses, however, showed that the relationship of ImpSS with current smoking was stronger in CD patients. Moderator analysis showed that the relationship of ImpSS with nicotine dependence was also greater in smokers with CD than in those with UC. No other ZKPQ subscale was correlated to disease type, current smoking or nicotine dependence.

CONCLUSION

ImpSS is associated with current smoking and nicotine dependence in IBD, and these associations are stronger in CD. These findings might be relevant to more effective interventions aiming at smoking cessation in CD patients.

Clustering in time of familial IBD separates ulcerative colitis from Crohn's disease

BACKGROUND

The aim was to compare clustering of time at diagnosis and phenotype of inflammatory bowel disease (IBD) between affected parents and children and to explore generational differences in age at diagnosis (AAD) as well as the concordance of clinical characteristics.

METHODS

Eighty-four affected pairs from 45 families were included from 5 counties in southeastern Norway between August 2003 and December 2006; 43 were sib-sib pairs and 39 parent-child pairs. Clinical data were obtained by phone interviews and by hospital records.

RESULTS

The difference in median AAD was 17.0 years (P < 0.001) and 2.0 years (P = 0.29) in parent-child and sib-sib pairs, respectively. When the time interval between diagnosis in parent and child was split into 2 groups, below and above 5 years, 64% of pairs with ulcerative colitis (UC) offspring were diagnosed within 5 years, compared to 24% of pairs with Crohn's disease (CD) offspring (odds ratio [OR] = 5.7, 95% confidence interval [CI]: 1.4, 23.8). Concordance for smoking habits was low in 26 pairs with mixed disease (κ = 0.15), whereas patients with CD tended to be current smokers.

CONCLUSIONS

Most of the children acquire their disease at an earlier time in life compared to their parents, suggesting genetic anticipation. The time interval between diagnosis of the parents and offspring was lower when the offspring developed UC compared to CD, which might reflect the influence of shared environment on the generational difference in AAD in UC families. This study confirmed the effect of smoking habits on IBD phenotype.

Changes in the epidemiology of inflammatory bowel diseases

Significant changes have been observed in the epidemiology of inflammatory bowel diseases (IBD) in the last two decades. Traditionally, the incidence of IBD was higher in the developed, industrialized countries, in contrast, nowadays it became more prevalent in the previously low incidence areas. In particular, the incidence of ulcerative colitis (UC) is similar to that observed in North America and Western Europe, while the incidence of Crohn’s disease (CD) in developing countries is still low, suggesting that the environmental factors may act faster or differently in UC than in CD. In Europe, the North to South gradient disappeared, and also the West to East gradient is diminishing. Smoking and appendectomy may be considered as important environmental factors in both UC and CD, however, with opposite effects. In addition, the use of oral contraceptives is associated to disease susceptibility in both diseases. The role of diet, perinatal events, stress and nonsteroidal anti-inflammatory drugs in the pathogenesis is still controversial.

Collagen in colon disease

The pathophysiology of wound healing in the bowel wall suggests that collagen and matrix metalloproteinases (MMPs) have an important role in the changes of the bowel wall seen in several colonic diseases. Several recent studies suggest that disturbances of the collagen texture and the extracellular matrix (ECM) metabolism are major factors leading to the onset of diverticular disease. Changes of the ECM also play a role in the development of inflammatory bowel diseases. Regarding the permanent remodeling of the bowel wall, any imbalance of the ECM could support the onset of chronic inflammation and the development of fistula formation, such as that seen in patients with Crohn's disease. Disturbances of the ECM play a role in the pathogenesis of anastomotic leakage after large bowel surgery and suggest the presence of a genetically defined risk population with disturbed wound healing mechanisms. This concept could explain the well known situation where an anastomotic breakdown is observed, despite the absence of other known risk factors and after a technically correct anastomosis.

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.

Reduced expression of collagen type I and increased expression of matrix metalloproteinases 1 in patients with Crohn's disease

Crohn's disease (CD) is a chronic inflammatory bowel disease of still unknown etiology. The aim of our study was to find out whether there are any changes in the colonic wall of CD patients that could give hints for a predisposing disorder concerning the extracellular matrix, especially the collagen metabolism. Eight samples of colonic tissue from patients with Crohn's disease were compared to 14 specimens from patients without Crohn's disease. We performed a sirius red test for the overall collagen content and immunohistochemical studies examining differentiation between" collagen type I and type III and the expression of MMP-1 and MMP-13. In the bowel sections of patients with Crohn's disease, decreased levels of mature collagen type I with a resulting lower ratio of collagen I/III compared to patients without Crohn's disease were found (1.12 +/- 0.29 vs. 1.59 i 0.31). The expression of MMP-1 was significantly increased in the CD group (9.21 i 6.02 vs.6.02 i 1.98), whereas expression of MMP-13 showed no difference in both groups. Our study gives the first indication that preexisting changes of the extracellular matrix in the colonic wall may play a role in the pathogenesis of CD. Further studies have to be done to elucidate these interesting aspect of the pathogenesis in Crohn's disease.

Inflammatory bowel disease and smoking: a review of epidemiology, pathophysiology, and therapeutic implications

The relationship between smoking behavior and inflammatory bowel disease (IBD) is complex. While Crohn's disease (CD) is associated with smoking and smoking has detrimental effects on the clinical course of the disease, ulcerative colitis (UC) is largely a disease of nonsmokers and former smokers. Furthermore, cigarette smoking may even result in a beneficial influence on the course of ulcerative colitis. The potential mechanisms involved in this dual relationship include changes in humoral and cellular immunity, cytokine and eicosanoid levels, gut motility, permeability, and blood flow, colonic mucus, and oxygen free radicals. Nicotine is assumed to be the active moiety. The differential therapeutic consequences comprise the cessation of smoking in CD and, so far, clinical trials using nicotine in different forms of application for UC. In this article, we review the relationship between cigarette smoking and IBD, considering epidemiological, pathogenetic, and clinical aspects.

Nasal manifestations of systemic illnesses

This article is focused on the nasal and sinusal manifestations of systemic diseases, such as infections, immunodeficiencies, chronic multisystemic disorders, inflammatory bowel diseases, deposition diseases, hematologic diseases, respiratory diseases, and smell and taste disorders. A concise review of some of the systemic diseases that commonly present complaints in the nose and paranasal sinuses, including their prevalence, sinonasal manifestations, diagnosis, and treatment, is provided.

Future directions in sarcoidosis research: summary of an NHLBI working group

Sarcoidosis is a systemic granulomatous disease of unknown etiology that primarily affects the lungs. The etiology remains unclear; however, environmental, genetic, ethnic, and familial factors probably modify expression of the disease. As an example, African Americans are at greater risk of mortality and morbidity than are white Americans, and more often have a family history of sarcoidosis. Most patients with sarcoidosis recover spontaneously, but some develop chronic, debilitating disease. Corticosteroids and other drugs, although effective at controlling disease activity, may not influence the overall course of disease. Because of the many uncertainties about the pathogenesis, course, and management of sarcoidosis, the National Heart, Lung, and Blood Institute convened a working group to identify future research directions and opportunities for sarcoidosis. These include developing a tissue bank, using novel methods to identify genetic factors, studying the immunopathogenesis with human tissue and animal models, exploring new approaches to diagnose and manage disease, and, finally, conducting randomized controlled trials to assess new therapies.