Socioeconomics of Crohn's disease: a review of epidemiology and an etiological hypothesis

Neighborhood Deprivation and Risks of Autoimmune Disorders: A National Cohort Study in Sweden

Background: No study to date, as far as we know, has analyzed the potential effect of neighborhood-level deprivation on autoimmune disorders (ADs), when adjusted for individual-level characteristics. Methods: A total of 5.4 million individuals from 8363 neighborhoods, comprising the whole Swedish population (ages 25–74 years), were followed for the period 1 January 2000, until admission due to diagnosis of ADs during the period of the study, or the conclusion of the study (31 December 2010). We used a neighborhood deprivation index, constructed from variables such as low education, low income, unemployment, and social welfare assistance, to assess the level of neighborhood deprivation. Multilevel logistic regression was used in the analysis with individual level characteristics at the first level and level of neighborhood deprivation at the second level. Results: A significant association between level of neighborhood deprivation and ADs was found. The crude odds were 1.32 (95% confidence interval 1.27–1.36) for those residing in the high-deprived neighborhoods compared to those living in low-deprivation neighborhoods. In the full model, where individual level characteristics were taken into account, the odds of ADs were 1.18 (1.14–1.22) in the most deprived neighborhoods. Certain Ads—angiitis hypersensitive (5.14), ankylosing spondylitis (1.66), celiac disease (1.65), Crohn’s disease (1.21), diabetes mellitus type 1 (1.45), Graves’s disease (1.13), Hashimoto thyroiditis (1.51), psoriasis (1.15), rheumatoid arthritis (1.15), sarcoidosis (1.20), and systemic sclerosis (1.27)—remained significantly associated with high level of neighborhood deprivation after adjustment for the individual-level variables. Conclusion: This study is the largest to date analyzing the potential influence of neighborhood deprivation on ADs. Our results indicate that neighborhood deprivation may affect risk of ADs, independent of individual level sociodemographic characteristics. For health care policies, both individual and neighborhood level approaches seem to be of importance.

Schistosoma mansoni Coinfection Attenuates Murine Toxoplasma gondii-Induced Crohn's-Like Ileitis by Preserving the Epithelial Barrier and Downregulating the Inflammatory Response

Background and aims: Mice orally infected with T. gondii develop Crohn's disease (CD)-like enteritis associated with severe mucosal damage and a systemic inflammatory response, resulting in high morbidity and mortality. Previously, helminthic infections have shown therapeutic potential in experimental colitis. However, the role of S. mansoni in T. gondii-induced CD-like enteritis has not been elucidated. Our study investigated the mechanisms underlying T. gondii-induced ileitis and the potential therapeutic effect of S. mansoni coinfection.

Methods: C57BL/6 mice were infected by subcutaneous injection of cercariae of the BH strain of S. mansoni, and 7–9 weeks later, they were orally infected with cysts of the ME49 strain of T. gondii. After euthanasia, the ileum was removed for histopathological analysis; staining for goblet cells; immunohistochemistry characterizing mononuclear cells, lysozyme expression, apoptotic cells, and intracellular pathway activation; and measuring gene expression levels by real-time PCR. Cytokine concentrations were measured in the serial serum samples and culture supernatants of the ileal explants, in addition to myeloperoxidase (MPO) activity.

Results:T. gondii-monoinfected mice presented dense inflammatory cell infiltrates and ulcerations in the terminal ileum, with abundant cell extrusion, apoptotic bodies, and necrosis; these effects were absent in S. mansoni-infected or coinfected animals. Coinfection preserved goblet cells and Paneth cells, remarkably depleted in T. gondii-infected mice. Densities of CD4- and CD11b-positive cells were increased in T. gondii- compared to S. mansoni-infected mice and controls. MPO was significantly increased among T. gondii-mice, while attenuated in coinfected animals. In T. gondii-infected mice, the culture supernatants of the explants showed increased concentrations of TNF-alpha, IFN-gamma, and IL-17, and the ileal tissue revealed increased expression of the mRNA transcripts for IL-1 beta, NOS2, HMOX1, MMP3, and MMP9 and activation of NF-kappa B and p38 MAPK signaling, all of which were counterregulated by S. mansoni coinfection.

Conclusion:S. mansoni coinfection attenuates T. gondii-induced ileitis by preserving mucosal integrity and downregulating the local inflammatory response based on the activation of NF-kappa B and MAPK. The protective function of prior S. mansoni infection suggests the involvement of innate immune mechanisms and supports a conceptually new approach to the treatment of chronic inflammatory diseases, including CD.

Risk of inflammatory bowel disease in first- and second-generation immigrants in Sweden: a nationwide follow-up study

BACKGROUND

The objective was to analyze whether there is an association between country of birth in first-generation immigrants and first hospitalization for an inflammatory bowel disease, and to study whether any such association remains in second-generation immigrants.

METHODS

In this follow-up study a nationwide research database at Lund University was used to identify all primary hospital diagnoses of Crohn's disease (CD) and ulcerative colitis (UC) in all first- and second-generation immigrants in Sweden between January 1, 1964, and December 31, 2007. Standardized incidence ratios (SIRs) with regard to age, gender, time period, geographical region, and socioeconomic status were estimated in first- and second-generation immigrants.

RESULTS

No increased but some decreased risks for CD and UC were found among first-generation immigrants. These decreased risks partly remained in the second generation. Moreover, second-generation immigrants of Danish, Eastern European, and Iraqi origin had higher risks of CD than the reference group. Second-generation immigrants of Finnish and Iranian origin had higher risks of UC.

CONCLUSIONS

Decreased risks of CD and UC found in some first-generation immigrant groups partly persisted in the second generation. For some immigrant groups, increased risks of CD or UC emerged in the second generation.

Educational level and occupation as risk factors for inflammatory bowel diseases: A nationwide study based on hospitalizations in Sweden

BACKGROUND

The aim of this study was to investigate possible associations between educational level, occupation, and hospitalization for inflammatory bowel disease.

METHODS

A nationwide database was constructed by linking the Swedish Census to the Hospital Discharge Register in order to obtain data on all first hospitalizations for Crohn's disease (CD) and ulcerative colitis (UC) in Sweden during the study period (1970-2004). Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated by educational level and occupation for men and women >or=30 years. Three cohorts were defined based on occupational titles recorded in the Swedish census data in 1970 and 1980.

RESULTS

Significantly decreased SIRs for CD were observed for both men and women who had an educational level of >12 years. Among men, significantly increased SIRs for CD were present in all 3 cohorts among "drivers." Male "religious, juridical, and other social-science-related workers," "textile workers," and "glass, ceramic, and tile workers," and female "clerical workers," "mechanics and iron and metalware workers," and "printers and related workers" had a significantly increased SIR for CD that was present in 1 of the 3 cohorts. For UC, male "postal and communication workers," "smelters and metal foundry workers," and "chemical process workers," and female "wood workers" had a significantly increased SIR for UC that was present in at least 1 of the 3 cohorts.

CONCLUSIONS

Educational level and occupation seem to have a minor effect on the population's likelihood of hospitalization for CD and UC.

Prevalence of Inflammatory Bowel Disease in the Canton of Vaud (Switzerland): A population-based cohort study

BACKGROUND AND AIMS

Because of the changing epidemiology of Inflammatory Bowel Diseases (IBD), we set out to characterize the population-based prevalence of Crohn's Disease (CD) and Ulcerative Colitis (UC) in a defined population of Switzerland.

METHODS

Adult IBD patients were identified by a cross-matched review of histological, hospital and gastroenterologist files throughout a geographical defined population (Canton of Vaud). Demographic factors statistically significantly associated with prevalence were evaluated using a stepwise Poisson regression analysis. Results were compared to IBD prevalence rates in other population-based studies and time trends were performed, based on a systematic literature review.

RESULTS

Age and sex-adjusted prevalence rates were 205.7 IBD (100.7 CD and 105.0 UC) cases per 10(5) inhabitants. Among 1016 IBD patients (519 CD and 497 UC), females outnumbered males in CD (p<0.001), but males were more represented in elderly UC patients (p=0.008). Thus, being a male was statistically associated with UC (Relative Risk (RR) 1.25; p=0.013), whereas being a female was associated with CD (RR 1.27; p=0.007). Living in an urban zone was associated with both CD and UC (RR 1.49; p<0.001, 1.63; p<0.001, respectively). From 1960 to 2005, increases in UC and CD prevalences of 2.4% (95%CI, 2.1%-2.8%; p<0.001) and 3.6% (95%CI, 3.1%-4.1%; p<0.001) per annum were found in industrialised countries.

CONCLUSIONS

Extrapolating our data to all of Switzerland yields an estimate of 12,000 IBD cases for the country, or 1 in 500 inhabitants. Our study gives support to an increase in IBD prevalence in Europe.

Gastrointestinal parasites: potential therapy for refractory inflammatory bowel diseases

Crohn's disease and ulcerative colitis are chronic relapsing inflammatory bowel diseases (IBDs). Different pharmacological agents are currently used in several combinations to control the inflammatory process. Recently, antibodies against the proinflammatory cytokine tumor necrosis factor-alpha appeared to be very effective in treating patients with Crohn's disease. However, due to the fact that the pathogen causing IBD is still unknown, no causative treatment is currently available that is able to make the disease disappear. Recently, the hygiene hypothesis of the development of immunological diseases was proposed, stating that raising children in extremely hygienic environments with less exposure to parasite infections may negatively affect the development of the immune system, predisposing them to immunologic diseases such as IBD. This hypothesis is supported by experimental data showing that helminthic parasites protect against T helper (TH) type 1 cell-mediated gastrointestinal inflammations like Crohn's disease. Both TH-2 cells and regulatory T cells may be involved in this immunomodulatory mechanism. Here, we review the experimental and clinical studies in favor of the hygiene hypothesis, opening perspectives on new therapies for IBD.

Crohn's disease and Mycobacterium avium subsp. paratuberculosis: current issues

Crohn's disease is a chronic debilitating inflammatory bowel disease of unknown etiology. Proposed causes include bacterial or viral infection, diet or exposure to tobacco smoke, genetic abnormality, and immune dysfunction. The bacterium Mycobacterium avium subsp. paratuberculosis (Map) has received much research attention as a potential cause of the disease. Map causes Johne's disease in ruminants. The pathology of Johne's disease superficially resembles that of Crohn's disease in humans. Some researchers have shown evidence of Map in intestinal tissues of Crohn's disease patients. Studies are in progress to investigate the possibility that Map exists in milk from infected cows and survives pasteurization. This is a controversial subject with the potential for media attention and public outcry. We examined the current literature and concluded that insufficient evidence exists at this time to implicate any one factor, including Map in milk, as the definitive cause of Crohn's disease. The high degree of uncertainty in this issue requires regulators to recognize the need for effective risk communication as ongoing research provides additional information about the disease.