The association between water supply and inflammatory bowel disease based on a 1990-1993 cohort study in southeastern Norway

Research progress of ferroptosis and inflammatory bowel disease

Inflammatory bowel disease (IBD) is a non-specific chronic inflammatory disorder of the gastrointestinal tract, imposing significant burdens on both society and individuals. As a new type of regulated cell death (RCD), ferroptosis is different from classic RCDs such as apoptosis and necrosis in cell morphology, biochemistry and genetics. The main molecular mechanisms of ferroptosis include dysregulation of iron metabolism, impaired antioxidant capacity, mitochondrial dysfunction, accumulation of lipid-associated super-oxides, and membrane disruption. In recent years, increasing evidence has shown that ferroptosis is involved in the pathophysiology of inflammatory bowel disease. However, the exact roles and underlying molecular mechanisms have not been fully elucidated. This article reviews the mechanism of ferroptosis in the occurrence and development of inflammatory bowel disease, in order to provide new ideas for the pathophysiological research of inflammatory bowel disease. Additionally, we discuss potential strategies for the prevention and treatment of inflammatory bowel disease by targeting ferroptosis.

Epidemiology of Pediatric Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), including subtypes Crohn disease and ulcerative colitis is a chronic inflammatory disorder most often diagnosed in young adulthood. The incidence and prevalence of pediatric-onset IBD is increasing globally. IBD is likely caused by an interplay of multiple environmental factors resulting in a dysregulated mucosal response to the commensal intestinal microbiota in genetically predisposed individuals. This article provides an overview of pediatric IBD epidemiology and environmental risk factors associated with its development, such as the Hygiene Hypothesis, air pollution, greenspace and blue space, neonatal factors, antibiotics, and diet.

Drinking water quality and inflammatory bowel disease: a prospective cohort study

Environmental factors, such as drinking water and diets, play an important role in the development of inflammatory bowel disease (IBD). This study aimed to investigate the associations of metal elements and disinfectants in drinking water with the risk of inflammatory bowel disease (IBD) and to assess whether diet influences these associations. We conducted a prospective cohort study including 22,824 participants free from IBD from the Yinzhou cohort study in the 2016-2022 period with an average follow-up of 5.24 years. The metal and disinfectant concentrations were measured in local pipeline terminal tap water samples. Cox regression models adjusted for multi-level covariates were used to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (95% CIs). During an average follow-up period of 5.24 years, 46 cases of IBD were identified. For every 1 standard deviation (SD) increase in the concentration of manganese, mercury, selenium, sulfur tetraoxide (SO₄)_, chlorine, and nitrate nitrogen (NO₃_N) were associated with a higher risk of IBD with the HRs of 1.45 (95% CI: 1.14 to 1.84), 1.51 (95% CI: 1.24-1.82), 1.29 (95% CI: 1.03-1.61), 1.52 (95% CI: 1.26-1.83), 1.26 (95% CI: 1.18-1.34), and 1.66 (95% CI: 1.32-2.09), whereas zinc and fluorine were inversely associated with IBD with the HRs of 0.42 (95% CI: 0.24 to 0.73) and 0.68 (95% CI: 0.54-0.84), respectively. Stronger associations were observed in females, higher income groups, low education groups, former drinkers, and participants who never drink tea. Diets have a moderating effect on the associations of metal and nonmetal elements with the risk of IBD. We found significant associations between exposure to metals and disinfectants and IBD. Diets regulated the associations to some extent.

New insights into the role of metal(loid)s in the development of ulcerative colitis: a systematic review

The relationship between heavy metals and ulcerative colitis (UC) was investigated in several studies, but their results were not consistent. Therefore, in this systematic review study, the positive and negative effects of metal(loid)s (Zn, Cu, Fe, Se, Pb, Ni, and As) on UC disease were investigated. In this systematic search, 13 original articles from 1993 to 2021 were identified in Google Scholar, Science Direct, Scopus, PubMed, and the Web of Science databases. In included studies, the concentrations of heavy metals and essential elements were measured in the blood, serum, intestinal biopsies, and hair samples of the patients. Some studies have also examined the heavy metal concentration in UC patients' diet and their drinking water. In the serum samples, Pb (220 ± 108 mg/L) and Cu (401.5 ± 104 µg/L) had the maximum concentrations among the other elements, as well as Zn and Fe had the highest levels in hair and intestinal tissue samples, respectively. In light of the selected articles, there is a possibility of a preventive role for Se and Zn in UC development. Moreover, exposure to Fe can exacerbate the symptoms of the disease. In conclusion, this review reveals that toxic metals, as ubiquitous environmental pollutants, can contribute to the exacerbation of inflammatory intestinal symptoms, and consumption of essential elements can play a vital role in the control of UC, and it is important to pay attention to them in health decisions.

Association between water source and chronic gastrointestinal diseases in Chinese: A cross-sectional and longitudinal study

Background

Gastrointestinal health is closely associated with the quality of the water supply. However, long-term associations between the water supply type and chronic gastrointestinal disease (CGD) are unclear.

Method

The water supply was categorized as "tap-water" or "non-tap water" use. Changes in water source use were categorized into four types: "non-tap water both at baseline and in follow-ups," "non-tap water at baseline and tap-water in follow-ups," "tap-water at baseline and non-tap water in follow-ups," or "tap-water at baseline and in follow-ups." We explored the association between tap-water use (and changes therein) and the risk of CGD in a cross-sectional and longitudinal population study based on national cohort data from 2011 to 2018.

Results

After the inclusion and exclusion process, 13,332 and 9,688 participants were included in the cross-sectional and longitudinal analyses, respectively. Tap-water use was associated with fewer CGD cases at baseline (OR = 0.98, 95% CI: 0.90, 1.07). Tap-water use at baseline was associated with significantly lower incidence of CGD in follow-ups (HR = 0.70, 95% CI: 0.70, 0.90). Compared with consistent non-tap water use in both baseline and follow-ups, switching from non-tap water to tap-water use in follow-ups was associated with a lower risk of CGD (HR = 0.79, 95% CI: 0.64, 0.97), tap water use at both baseline and in follow-ups was associated with a lower risk of CGD (HR = 0.72, 95% CI: 0.59, 0.88). The decreased risk of CGD followed a linear trend (P _fortrend < 0.01). Adjustment for indoor solid fuel use and outdoor air pollution exposure to PM_2.5 did not change the association between tap water use and CGD.

Conclusion

Tap water use was associated with a reduced risk of incident CGD. The results from this study should aid in effect assessment for water purification strategies and public decision support for gastrointestinal health management.

Environmental Pollutants Are Associated With Irritable Bowel Syndrome in a Commercially Insured Cohort of California Residents

BACKGROUND AND AIMS

Prior studies have linked environmental pollutants with gastrointestinal (GI) diseases. Here, we quantify the relationships between 7 pollutants and the zip code-level incidence of irritable bowel syndrome (IBS), functional dyspepsia, inflammatory bowel diseases (IBDs), and eosinophilic esophagitis (EoE) in California.

METHODS

Claims in Optum's Clinformatics Data Mart were linked with environmental exposures in California, derived from CalEnviroScreen 3.0. We identified adult patients with new diagnoses of each GI disease, and estimated claims-derived, zip code-level disease incidence rates. Two study periods were considered: 2009-2014 (International Classification of Diseases-Ninth Revision era) and 2016-2019 (International Classification of Diseases-Tenth Revision [ICD-10] era). Multivariable negative binomial regression models were used to test associations between 7 pollutants (ozone, particulate matter <2.5 μm [PM2.5], diesel emissions, drinking water contaminants, pesticides, toxic releases from industrial facilities, traffic density) and zip code-level incidence of the GI diseases along with a negative control outcome, adjusting for numerous potential confounders.

RESULTS

Zip code-level IBS incidence was associated with PM2.5 (P < .001 in both eras) and airborne toxic releases from facilities (P < .001 in both eras). An increase of 1 μg/m³ in PM2.5 or 1% in toxic releases translates to an increase in the IBS incidence rate of about 0.02 cases per 100 person-years. Traffic density and drinking water contaminant exposures were also associated with increasing IBS incidence, but these associations were not significant in both eras. Similarly, exposure to PM2.5, drinking water contaminants and airborne toxic releases from facilities were associated with functional dyspepsia incidence, though not in both eras. No significant associations were noted between pollutants and IBD or EoE incidence.

CONCLUSION

Exposure to PM2.5 and airborne toxic releases from facilities are associated with higher IBS incidence among a cohort of commercially insured Californians. Environmental pollutant exposure was not associated with the incidence of IBDs and EoE in this cohort.

Evidence-based pathogenesis and treatment of ulcerative colitis: A causal role for colonic epithelial hydrogen peroxide

In this comprehensive evidence-based analysis of ulcerative colitis (UC), a causal role is identified for colonic epithelial hydrogen peroxide (H₂O₂) in both the pathogenesis and relapse of this debilitating inflammatory bowel disease. Studies have shown that H₂O₂ production is significantly increased in the non-inflamed colonic epithelium of individuals with UC. H₂O₂ is a powerful neutrophilic chemotactic agent that can diffuse through colonic epithelial cell membranes creating an interstitial chemotactic molecular “trail” that attracts adjacent intravascular neutrophils into the colonic epithelium leading to mucosal inflammation and UC. A novel therapy aimed at removing the inappropriate H₂O₂ mediated chemotactic signal has been highly effective in achieving complete histologic resolution of colitis in patients experiencing refractory disease with at least one (biopsy-proven) histologic remission lasting 14 years to date. The evidence implies that therapeutic intervention to prevent the re-establishment of a pathologic H₂O₂ mediated chemotactic signaling gradient will indefinitely preclude neutrophilic migration into the colonic epithelium constituting a functional cure for this disease. Cumulative data indicate that individuals with UC have normal immune systems and current treatment guidelines calling for the suppression of the immune response based on the belief that UC is caused by an underlying immune dysfunction are not supported by the evidence and may cause serious adverse effects. It is the aim of this paper to present experimental and clinical evidence that identifies H₂O₂ produced by the colonic epithelium as the causal agent in the pathogenesis of UC. A detailed explanation of a novel therapeutic intervention to normalize colonic H₂O₂, its rationale, components, and formulation is also provided.

The Role of the Urban Exposome in the Increasing Global Rates of Pediatric Inflammatory Bowel Disease

Pediatric inflammatory bowel disease (IBD) is becoming increasingly common around the world, rapidly accelerating in regions undergoing rapid economic development. IBD is more common among those living in cities, and the association between the urban environment and IBD incidence is strongest in children. The "urban exposome" is defined as the totality of environmental exposures associated with urban living: air pollution, water contamination, green and blue space, nighttime light, noise, and availability of pre-processed and packaged foods. Investigation of the role of the urban exposome and IBD is in its infancy. Existing research has reached heterogeneous conclusions, and most studies have focused specifically on adult-onset disease and environmental exposures in isolation rather than the interaction between exposures. By better understanding the impact of the urban exposome on pediatric IBD, we can work to minimize these exposures and decrease the future burden of IBD in children.

Exploring Links Between Industrialization, Urbanization, and Chinese Inflammatory Bowel Disease

Background: Evidence is emerging that the incidence of inflammatory bowel diseases (IBD) is dramatically increased in China, but with a geographic variation. Objectives: We performed a review to summarize the link of accelerated industrialization, urbanization to changing trends in the incidence of IBD over the last three decades. Methods: An electronic database search was performed in PubMed, Medline, EMBASE and Google Scholar (for English literature) and the China Science Periodical Database in Wanfang Data (for Chinese literature) from January 1990 to June 2020. Results: By systematically analyzing the changing trends of gross domestic product (GDP) or GDP per capita, population migration from rural areas to cities and increasing incidence of IBD in parallel in different Chinese regions, an association between accelerated industrialization and urbanization and rising rate of IBD was shown. In which, rates of IBD incidence were higher in provinces with a high value of GDP per capita than those provinces with a low value of GDP per capita. Analysis of available epidemiological data revealed that the incidence of IBD was rising in parallel with increasing trends of both gross products of industry and urban population in Yunnan Province in a 14-year interval. Further evidence suggested that industrialization- and urbanization-induced subsequent changes in environmental factors, e.g., Westernized dietary habits and obesity, and work-related stress, might contribute to the increased risk of IBD in China. In addition, the preliminary results showed that urbanization and Westernized dietary habits might induce significant changes in gut microbiota profile that are possibly to increase the risk for IBD in Chinese. Conclusions: Existing evidence to suggest that accelerated industrialization/urbanization is associated with the increasing incidence of IBD in China, which provides novel insights to study the possible mechanisms for the recent increasing incidence of IBD in newly industrialized and urbanized developing countries. In the future, the interaction between relevant environmental factors e.g., air/water pollution and IBD susceptibility genes in Chinese should be examined.

The Association between Drinking Water Quality and Inflammatory Bowel Disease-A Study in Eastern Croatia

The incidence rate of inflammatory bowel disease (IBD) is becoming a global health problem that could be caused by changes in environmental and lifestyle habits. The study aimed to identify the association between the quality of drinking water, i.e., physiochemical and biological aspects of the phenotype and activity of IBD in Eastern Croatia. The study included 312 patients (63.4% ulcerative colitis, UC, and 36.6% Crohn's disease, CD) from the area of Eastern Croatia. The data were collected by questionnaires and the analysis of the water safety, based on 65 samples of drinking water by the patient's water supply method (public supply, rural water supply, and private well). IBD was active in 38.0% patients (34.0% CD and 40.0% UC). Significant differences (p = 0.001) were observed in the distribution of patients, according to counties in which they lived in. The largest deviation was noted in coliform bacteria, Escherichia coli, and enterococci bacteria, Fe, Al, and nitrate in rural water supply and private wells, although, without significant impact on IBD phenotype and activity. The hazard quotient (HQ) simulations showed that children are a sensitive group, regarding exposure to nitrates in drinking water over a long period of time, so there is a need for further monitoring and analysis of this issue.

Crohn's disease and environmental contamination: Current challenges and perspectives in exposure evaluation

Although the incidence of Crohn's disease has increased worldwide over the past 30 years, the disorder's exact causes and physiological mechanisms have yet to be determined. Given that genetic determinants alone do not explain the development of Crohn's disease, there is growing interest in "environmental" determinants. In medical science, the term "environment" refers to both the ecological and social surroundings; however, most published studies have focused on the latter. In environmental and exposure sciences, the term "environment" mostly relates to contamination of the biotope. There are many unanswered questions on how environmental hazards might contribute to the pathogenesis of Crohn's disease. Which pollutants should be considered? Which mechanisms are involved? And how should environmental contamination and exposure be evaluated? The objective was to perform a systematic review of the literature on Crohn's disease and environmental contamination. We searched the PubMed, Google Scholar, Scopus, ISI Web of Science and Prospero databases. We considered all field studies previous to April 2019 conducted on human health indicators, and evaluating exposure to all type of physical, biological and chemical contamination of the environment. The lack of clear answers to date can be ascribed to the small total number of field studies (n = 16 of 39 publications, most of which were conducted by pioneering medical scientists), methodological differences, and the small number of contaminants evaluated. This make it impossible to conduct a coherent and efficient meta-analysis. Based on individual analysis of available studies, we formulated five recommendations on improving future research: (i) follow up the currently identified leads - especially metals and endocrine disruptors; (ii) explore soil contamination; (iii) gain a better knowledge of exposure mechanisms by developing transdisciplinary studies; (iv) identify the most plausible contaminants by developing approaches based on the source-to-target distance; and (v) develop registries and cohort-based analyses.

A food pyramid, based on a review of the emerging literature, for subjects with inflammatory bowel disease

Emerging literature suggests that diet plays an important modulatory role in inflammatory bowel disease (IBD) through the management of inflammation and oxidative stress. The aim of this narrative review is to evaluate the evidence collected up till now regarding optimum diet therapy for IBD and to design a food pyramid for these patients. The pyramid shows that carbohydrates should be consumed every day (3 portions), together with tolerated fruits and vegetables (5 portions), yogurt (125ml), and extra virgin olive oil; weekly, fish (4 portions), white meat (3 portions), eggs (3 portions), pureed legumes (2 portions), seasoned cheeses (2 portions), and red or processed meats (once a week). At the top of the pyramid, there are two pennants: the red one means that subjects with IBD need some personalized supplementation and the black one means that there are some foods that are banned. The food pyramid makes it easier for patients to decide what they should eat.

Causal associations of iron status with gout and rheumatoid arthritis, but not with inflammatory bowel disease

BACKGROUND & AIMS

We conducted a two-sample Mendelian randomization study to assess the associations of iron homeostasis with the risk of gout, rheumatoid arthritis and inflammatory bowel disease.

METHODS

Single-nucleotide polymorphisms for iron status were selected at the genome-wide significance level from a large genome-wide association study of 48 972 European-descent individuals. Summary-level data for gout, rheumatoid arthritis and inflammatory bowel disease were obtained from The Global Urate Genetics Consortium and two large genome-wide association studies, respectively. Inverse-variance weighted method with random-effects and sensitivity analyses were performed.

RESULTS

Genetic predisposition to high iron status was causally associated with higher odds of gout, lower odds of rheumatoid arthritis, but not associated with inflammatory bowel disease. The odds ratios of gout were 1.35 (95% confidence interval (CI), 1.00, 1.81; p = 0.047), 2.07 (95% CI, 1.23, 3.50; p = 0.006), 1.27 (95% CI, 1.07, 1.50; p = 0.007) and 0.69 (95% CI, 0.54, 0.90; p = 0.005) per one standard deviation increment of serum iron, ferritin, transferrin saturation, and transferrin levels, respectively. For rheumatoid arthritis, the corresponding odds ratios were 0.79 (95% CI, 0.65, 0.94; p = 0.010), 0.59 (95% CI, 0.40, 0.86; p = 0.007), 0.84 (95% CI, 0.75, 0.94; p = 0.003) and 1.28 (95% CI, 1.06, 1.55; p = 0.012).

CONCLUSIONS

Based on consistent findings for four iron biomarkers, genetically high iron status was positively associated with gout and inversely associated with rheumatoid arthritis. There was limited MR evidence supporting a causal association between iron status and inflammatory bowel disease.

Marked regional variations in the prevalence of inflammatory bowel disease in a limited geographical region are not associated with compounds in the drinking water

Objective: The incidence of autoimmune diseases, especially inflammatory bowel disease (IBD), has increased substantially. Globally, there are vast differences varying from 0.2/10⁵ in some Asian countries to over 80/10⁵ in the Faroe Islands. Environmental factors have been suggested as triggers. The aim was to investigate the incidence and prevalence of IBD in the 33 municipalities in the county Scania in Southern Sweden, an area comprising 100 × 100 km with 1,274,069 inhabitants. Furthermore, we wanted to explore whether compounds in the drinking water could contribute to IBD; one report from Norway has suggested that iron in drinking water could contribute to UC.Methods: Patients with CD and UC were identified through the ICD-10 diagnosis database during the period 2000-2013. Water analyses for pH, alkaline, nitrate, sulphate, iron, magnesium and calcium were based on established methods and compared with the prevalence of IBD using Student's t-test.Results: A total number of 8925 patients were identified. The incidence for CD and UC were high (mean 16.4/10⁵, range 13.6-17.9 and 25.3/10⁵, range 21.3-28.0, respectively). The prevalence varied substantially (p < .0001 for both; CD mean 0.30%, range 0.15-0.42 and UC mean 0.42%, range 0.32-0.56). No correlation between IBD and the chemical compounds in the drinking water could be shown.Conclusions: The incidence rates of both CD and UC were high. The prevalence varied from 200% to 300% between the municipalities, despite the limited geographical area indicating that local conditions are of importance. However, chemical compounds in the water were not associated with this variation.

Iron Treatment May Be Difficult in Inflammatory Diseases: Inflammatory Bowel Disease as a Paradigm

Iron plays a key role in many physiological processes; cells need a very exact quantity of iron. In patients with inflammatory bowel disease, anaemia is a unique example of multifactorial origins, frequently being the result of a combination of iron deficiency and anaemia of chronic disease. The main cause of iron deficiency is the activity of the disease. Therefore, the first aim should be to reach complete clinical remission. The iron supplementation route should be determined according to symptoms, severity of anaemia and taking into account comorbidities and individual risks. Oral iron can only be used in patients with mild anaemia, whose disease is inactive and who have not been previously intolerant to oral iron. Intravenous iron should be the first line treatment in patients with moderate-severe anaemia, in patients with active disease, in patients with poor tolerance to oral iron and when erythropoietin agents or a fast response is needed. Erythropoietin is used in a few patients with anaemia to overcome functional iron deficiency, and blood transfusion is being restricted to refractory cases or acute life-threatening situations.

Current, experimental, and future treatments in inflammatory bowel disease: a clinical review

Inflammatory bowel diseases (IBDs) may result from dysregulated mucosal immune responses directed toward the resident intestinal microbiota. This review describes the hallmark immunobiology of Crohn's disease and ulcerative colitis as well as therapeutic targets and mechanisms of action for current, experimental, and future treatments in IBD. Conventional therapies include 5-aminosalicylic acid, glucocorticosteroids, thiopurines, and methotrexate. Since 1997, monoclonal antibodies have gained widespread use. These consist of antibodies directed against pro-inflammatory cytokines such as tumor necrosis factor α, interleukin (IL)-12, and IL-23, or anti-homing antibodies directed against α4β7 integrin. Emerging oral therapies include modulators of intracellular signal transduction such as Janus kinase inhibitors. Vitamin D may help to regulate innate and adaptive immune responses. Modulation of the intestinal microbiota, using live microorganisms (probiotics), substrates for the colonic microbiota (prebiotics), or fecal microbiota transplantation (FMT), is in development. Dietary supplements are in widespread use, but providing evidence for their benefit is challenging. Stem cell treatment and nervous stimulation are promising future treatments.

Lipocalin 2 prevents intestinal inflammation by enhancing phagocytic bacterial clearance in macrophages

Lipocalin 2 (Lcn2), also called neutrophil gelatinase B-associated lipocalin (NGAL), is an anti-microbial peptide originally identified in neutrophil granules. Although Lcn2/NGAL expression is increased in the inflamed intestinal tissues of patients with inflammatory bowel disease, the role of Lcn2/NGAL in the development of intestinal inflammation remains unclear. Here we investigated the role of Lcn2/NGAL in intestinal inflammation using a spontaneous mouse colitis model, interleukin-10 knock out (IL-10 KO) mice. Lcn2 expression in the colonic tissues of IL-10 KO mice increased with the development of colitis. Lcn2/IL-10 double-KO mice showed a more rapid onset and development of colitis compared to IL-10 KO mice. Lcn2 enhanced phagocytic bacterial clearance in macrophages in vitro after infection with Escherichia coli. Transfer of Lcn2-repleted macrophages prevented the development of colitis in Lcn2/IL-10 double-KO mice in vivo. Our findings revealed that Lcn2 prevents the development of intestinal inflammation. One crucial factor seems to be the enhancement of phagocytic bacterial clearance in macrophages by Lcn2.

Fluoride: a risk factor for inflammatory bowel disease?

Although the association between inflammatory bowel disease (IBD) and oral hygiene has been noticed before, there has been little research on prolonged fluoride exposure as a possible risk factor. In the presented cases, exposure to fluoride seems indirectly associated with higher incidence of IBD. Fluoride toxicology and epidemiology documents frequent unspecific chronic gastrointestinal symptoms and intestinal inflammation. Efflux genes that confer resistance to environmental fluoride may select for IBD associated gut microbiota and therefore be involved in the pathogenesis. Together these multidisciplinary results argue for further investigation on the hypothesis of fluoride as a risk factor for IBD.

Incidence of Pediatric Inflammatory Bowel Disease in Finland: An Environmental Study

OBJECTIVES

The aim of this study was to explore possible environmental factors behind the regional differences in the incidence of pediatric inflammatory bowel disease (IBD).

METHODS

All of the patients diagnosed with IBD who were aged 0 to 14 years in Finland between 1987 and 2003 were identified from the Social Insurance Institution database. Finland was divided into squares of 250 × 250 m, and spatial variations of incidence rates were evaluated accordingly. The role of the environmental determinants (pediatric population density, agricultural industry, chemical contaminants of tap water and proximity to the sea or paper mills) in the geographic variations of the incidence rates was evaluated.

RESULTS

During the study period, the overall incidence of pediatric IBD was 6.5 of 100,000 (95% confidence interval [CI] 6.1-6.9). The incidence in very sparsely populated areas (≤10 person-years per 250 × 250 m) was 9.2 of 100,000 (95% CI 6.3-13.1) and 5.6 of 100,000 (95% CI 4.8-6.4) in the districts with the highest population density (>800 person-years per 250 × 250 m). A nonsignificant trend toward the same direction was also seen for ulcerative colitis (trend P = 0.09). Chemical contaminant concentrations of tap water, residence near the seaside, or proximity to paper mills were not associated with the incidence of pediatric IBD.

CONCLUSIONS

Our findings suggest higher incidence rates of pediatric IBD in the districts with low compared with high density of child population, but the differences cannot be explained by variations in the environmental exposures evaluated here.

Microbiome profiling of drinking water in relation to incidence of inflammatory bowel disease

The etiology of inflammatory bowel disease (IBD) is unknown; current research is focused on determining environmental factors. One consideration is drinking water: water systems harbour considerable microbial diversity, with bacterial concentrations estimated at 10(6)-10(8) cells/L. Perhaps differences in microbial ecology of water sources may impact differential incidence rates of IBD. Regions of Manitoba were geographically mapped according to incidence rates of IBD and identified as high (HIA) or low (LIA) incidence areas. Bulk water, filter material, and pipe wall samples were collected from public buildings in different jurisdictions and their population structure analyzed using 16S rDNA sequencing. At the phylum level, Proteobacteria were observed significantly less frequently (P = 0.02) in HIA versus LIA. The abundance of Proteobacteria was also found to vary according to water treatment distribution networks. Gammaproteobacteria was the most abundant class of bacteria and was observed more frequently (P = 0.006) in LIA. At the genus level, microbes found to associate with HIA include Bradyrhizobium (P = 0.02) and Pseudomonas (P = 0.02). Particular microbes were found to associate with LIA or HIA, based on sample location and (or) type. This work lays out a basis for further studies exploring water as a potential environmental source for IBD triggers.

Reciprocal interaction of diet and microbiome in inflammatory bowel diseases

PURPOSE OF REVIEW

Diet is an emerging but poorly defined disease modulator in inflammatory bowel diseases (IBDs). Dietary factors exert direct effects on epithelial and immune cells and indirectly modulate immune homeostasis by shaping the intestinal microbiota.

RECENT FINDINGS

The increase in IBD prevalence in industrialized countries is associated with lifestyle changes including diets rich in energy, saturated fats, meat and sugar. Despite the fact that the intestinal ecosystem shows high stability and resilience to short-term perturbations, long-term dietary habits have profound effects on composition and function eventually leading to dysbiosis, that is changes in microbial composition associated with deleterious effects to the host. High-throughput sequencing data generated deeper insights of the intestinal ecosystems related to health and disease. However, the available cohort-studies establish associative relationships between microbiota changes and disease, rather than causality. New mouse models of intestinal inflammation and the possibility to transfer disease-associated microbial consortia state an essential tool to unravel the potential of diet-induced microbial shifts.

SUMMARY

This review will discuss new insights of how nutrition or single dietary factors shape the intestinal ecosystem. Furthermore, we want to provide perspectives for clinical translation of this knowledge to treat or prevent IBD.

Inflammatory Bowel Disease: Historical Perspective, Epidemiology, and Risk Factors

Inflammatory bowel disease (IBD) describes a group of closely related yet heterogeneous predominantly intestinal disease processes that are a result of an uncontrolled immune mediated inflammatory response. It is estimated that approximately one and a half million persons in North America have IBD. Pathogenesis of IBD involves an uncontrolled immune mediated inflammatory response in genetically predisposed individuals to a still unknown environmental trigger that interacts with the intestinal flora. There continues to be an enormous amount of information emanating from epidemiological studies providing expanded insight into the occurrence, distribution, determinants, and mechanisms of inflammatory bowel disease.

Epidemiology and risk factors for IBD

IBD, comprising Crohn's disease and ulcerative colitis, is a chronic immunologically mediated disease at the intersection of complex interactions between genetics, environment and gut microbiota. Established high-prevalence populations of IBD in North America and Europe experienced the steepest increase in incidence towards the second half of the twentieth century. Furthermore, populations previously considered 'low risk' (such as in Japan and India) are witnessing an increase in incidence. Potentially relevant environmental influences span the spectrum of life from mode of childbirth and early-life exposures (including breastfeeding and antibiotic exposure in infancy) to exposures later on in adulthood (including smoking, major life stressors, diet and lifestyle). Data support an association between smoking and Crohn's disease whereas smoking cessation, but not current smoking, is associated with an increased risk of ulcerative colitis. Dietary fibre (particularly fruits and vegetables), saturated fats, depression and impaired sleep, and low vitamin D levels have all been associated with incident IBD. Interventional studies assessing the effects of modifying these risk factors on natural history and patient outcomes are an important unmet need. In this Review, the changing epidemiology of IBD, mechanisms behind various environmental associations and interventional studies to modify risk factors and disease course are discussed.

Effect of mesalamine and prednisolone on TNBS experimental colitis, following various doses of orally administered iron

BACKGROUND

Experimental data suggest that oral iron (I.) supplementation can worsen colitis in animals.

AIM

To investigate the influence of various concentrations of orally administered I. in normal gut mucosa and mucosa of animals with TNBS colitis, as well as the influence of Mesalamine (M.) and Prednisolone (P.) on the severity of TNBS colitis following orally administered I.

METHODS AND MATERIALS

156 Wistar rats were allocated into 10 groups. Colitis was induced by TNBS. On the 8th day, all animals were euthanatized. Activity of colitis and extent of tissue damage were assessed histologically. The levels of tissue tumor necrosis factor- α (t-TNF- α ) and tissue malondialdehyde (t-MDA) were estimated in all animal groups.

RESULTS

Moderate and high I. supplementation induced inflammation in the healthy colon and increased the activity of the experimentally induced TNBS colitis. Administration of M. on TNBS colitis following moderate iron supplementation (0.3 g/Kg diet) resulted in a significant improvement in the overall histological score as well as in two individual histological parameters. M. administration, however, did not significantly reduce the t-TNF- α levels (17.67 ± 4.92 versus 14.58 ± 5.71, P = 0.102), although it significantly reduced the t-MDA levels (5.79 ± 1.55 versus 3.67 ± 1.39, P = 0.000). Administration of M. on TNBS colitis following high iron supplementation (3.0 g/Kg diet) did not improve the overall histological score and the individual histological parameters, neither reduced the levels of t-TNF- α (16.57 ± 5.61 versus 14.65 ± 3.88, P = 0.296). However, M. significantly reduced the t-MDA levels (5.99 ± 1.37 versus 4.04 ± 1.41, P = 0.000). Administration of P. on TNBS colitis after moderate iron supplementation resulted in a significant improvement in the overall histological score as well as in three individual histological parameters. P. also resulted in a significant reduction in the t-TNF- α levels (17.67 ± 4.92 versus 12.64 ± 3.97, P = 0.003) and the t-MDA levels (5.79 ± 1.54 versus 3.47 ± 1.21, P = 0.001). Administration of P on TNBS colitis after high I. supplementation resulted in a significant improvement of the overall histological score and three individual histological parameters and significantly reduced the levels of t-TNF- α (16.6 ± 5.6 versus 11.85 ± 1.3, P = 0.001).

CONCLUSION

I. can induce colonic inflammation and aggravate TNBS colitis. M. and P. can significantly improve the inflammatory process in the colonic mucosa in TNBS colitis aggravated by orally administered I. P. has a stable anti-TNF- α effect. These findings suggest that the harmful.

Can temperature explain the latitudinal gradient of ulcerative colitis? Cohort of Norway

Background

Incidence and prevalence of ulcerative colitis follow a north–south (latitudinal) gradient and increases northwards at the northern hemisphere or southwards at the southern hemisphere. The disease has increased during the last decades. The temporal trend has been explained by the hygiene hypothesis, but few parallel explanations exist for the spatial variability. Many factors are linked to latitude such as climate. Our purpose was to investigate the association between variables governing the climate and prospectively identified patients.

Methods

In this study, we used a subset of the population-based Cohort of Norway (n = 80412) where 370 prevalent cases of ulcerative colitis were identified through self-reported medication. The meteorological and climatic variables temperature, precipitation, and altitude were recorded from weather stations of the Norwegian Meteorological Institute. Summer temperature was used to capture environmental temperature.

Results

Summer temperature was significantly related to the prevalence of ulcerative colitis. For each one-degree increase in temperature the odds for ulcerative colitis decreased with about 9% (95% CI: 3%-15%). None of the other climatic factors were significantly associated to the risk of ulcerative colitis. Contextual variables did not change the association to the prevalence of ulcerative colitis.

Conclusions

The present results show that the prevalence of ulcerative colitis is associated to summer temperature. Our speculation is that summer temperature works as an instrumental variable for the effect of microbial species richness on the development of ulcerative colitis. Environmental temperature is one of the main forces governing microbial species richness and the microbial composition of the commensal gut flora is known to be an important part in the process leading to ulcerative colitis.

Intravenous iron in inflammatory bowel diseases

PURPOSE OF REVIEW

Anemia and iron deficiency are the most common extraintestinal complications of inflammatory bowel diseases (IBDs) and are often undertreated. We review the evidence on intravenous (i.v.) iron overcoming the limitations of oral iron in IBD.

RECENT FINDINGS

Recent reports demonstrate that i.v. iron is at least as effective, quicker, and better tolerated than oral iron. Moreover, experimental data confirm that oral and parenteral iron have divergent effects on intestinal mucosa: oral iron severely increasing inflammation. Observational and randomized studies prove that i.v. iron is not only effective but also well tolerated with no negative influence in the activity of IBD. A new formulation, iron carboxymaltose, which permits higher individual doses, has been shown more effective and less costly than standard iron sucrose. Another formulation, iron isomaltoside, shows promising in in-vitro and small clinical studies, but data from large trials are not available yet.

SUMMARY

Oral iron is not an ideal option for treating anemia and iron deficiency in IBD. i.v. iron should be preferred at least in five scenarios: intolerance to oral iron, severe anemia, failure of oral therapy, need for a quick recovery, and use of erythropoietin. Direct evidence in IBD patients not only confirms the effectiveness of i.v. iron, but also demonstrates that new, more convenient preparations probably will become the standard in the near future.

Environmental factors and risk of developing paediatric inflammatory bowel disease -- a population based study 2007-2009

BACKGROUND AND AIMS

To identify environmental risk factors for developing inflammatory bowel disease (IBD) in children <15 years of age.

METHODS

IBD patients and randomly selected healthy controls from a well defined geographical area in Denmark were prospectively recruited in the period 1.1.2007-31.12.2009. Data regarding socioeconomic status, area of residence, living conditions, infections and diet were obtained by a questionnaire.

RESULTS

A total of 118 IBD patients (59 Crohn's disease (CD), 56 ulcerative colitis (UC) and 3 IBD unclassified (IBDU)) and 477 healthy controls filled out the questionnaire. The response rates were 91% in patients and 45% in controls, respectively. Several risk factors for IBD were identified: IBD in first degree relatives (IBD: OR (odds ratio): 6.1 (95%CI: 2.5-15.0), CD (OR: 6.8 (2.3-20.2)) and UC (OR: 6.1 (2.3-16.0))); bedroom sharing (IBD: OR: 2.1 (1.0-4.3), CD (OR: 3.6 (1.3-9.4))); high sugar intake (IBD: OR: 2.5 (1.0-6.2), CD (OR: 2.9 (1.0-8.5))); prior admission to a hospital for gastrointestinal infections (IBD: 7.7 (3.1-19.1), CD (7.9 (2.5-24.9)) and UC (7.4 (2.5-21.6))); stressful events (IBD: 1.7 (1.0-2.9)). Protective factors were daily vs. less than daily vegetable consumption (CD: 0.3 (0.1-1.0), UC (0.3 (0.1-0.8))) and whole meal bread consumption (IBD: OR: 0.5 (0.3-0.9), CD (0.4 (0.2-0.9))). An increased risk of diagnosis of CD compared to UC was shown for patients living in more urban areas (OR: 1.3 (1.1-1.6)).

CONCLUSION

We identified several risk and protective factors for developing IBD. Studies on the influence of environmental factors are important in our understanding of aetiology and phenotypes of paediatric IBD.

Crohn's disease

Crohn's disease is a relapsing systemic inflammatory disease, mainly affecting the gastrointestinal tract with extraintestinal manifestations and associated immune disorders. Genome wide association studies identified susceptibility loci that--triggered by environmental factors--result in a disturbed innate (ie, disturbed intestinal barrier, Paneth cell dysfunction, endoplasmic reticulum stress, defective unfolded protein response and autophagy, impaired recognition of microbes by pattern recognition receptors, such as nucleotide binding domain and Toll like receptors on dendritic cells and macrophages) and adaptive (ie, imbalance of effector and regulatory T cells and cytokines, migration and retention of leukocytes) immune response towards a diminished diversity of commensal microbiota. We discuss the epidemiology, immunobiology, amd natural history of Crohn's disease; describe new treatment goals and risk stratification of patients; and provide an evidence based rational approach to diagnosis (ie, work-up algorithm, new imaging methods [ie, enhanced endoscopy, ultrasound, MRI and CT] and biomarkers), management, evolving therapeutic targets (ie, integrins, chemokine receptors, cell-based and stem-cell-based therapies), prevention, and surveillance.

Diet and risk of inflammatory bowel disease

BACKGROUND

A better understanding of the environmental factors leading to inflammatory bowel disease should help to prevent occurrence of the disease and its relapses.

AIM

To review current knowledge on dietary risk factors for inflammatory bowel disease.

METHODS

The PubMed, Medline and Cochrane Library were searched for studies on diet and risk of inflammatory bowel disease.

RESULTS

Established non-diet risk factors include family predisposition, smoking, appendectomy, and antibiotics. Retrospective case-control studies are encumbered with methodological problems. Prospective studies on European cohorts, mainly including middle-aged adults, suggest that a diet high in protein from meat and fish is associated with a higher risk of inflammatory bowel disease. Intake of the n-6 polyunsaturated fatty acid linoleic acid may confer risk of ulcerative colitis, whereas n-3 polyunsaturated fatty acids may be protective. No effect was found of intake of dietary fibres, sugar, macronutrients, total energy, vitamin C, D, E, Carotene, or Retinol (vitamin A) on risk of ulcerative colitis. No prospective data was found on risk related to intake of fruits, vegetables or food microparticles (titanium dioxide and aluminium silicate).

CONCLUSIONS

A diet high in protein, particular animal protein, may be associated with increased risk of inflammatory bowel disease and relapses. N-6 polyunsaturated fatty acids may predispose to ulcerative colitis whilst n-3 polyunsaturated fatty acid may protect. These results should be confirmed in other countries and in younger subjects before dietary counselling is recommended in high risk subjects.

Exposure to multiple metals from groundwater-a global crisis: geology, climate change, health effects, testing, and mitigation

This paper presents an overview of the global extent of naturally occurring toxic metals in groundwater. Adverse health effects attributed to the toxic metals most commonly found in groundwater are reviewed, as well as chemical, biochemical, and physiological interactions between these metals. Synergistic and antagonistic effects that have been reported between the toxic metals found in groundwater and the dietary trace elements are highlighted, and common behavioural, cultural, and dietary practices that are likely to significantly modify health risks due to use of metal-contaminated groundwater are reviewed. Methods for analytical testing of samples containing multiple metals are discussed, with special attention to analytical interferences between metals and reagents. An overview is presented of approaches to providing safe water when groundwater contains multiple metallic toxins.

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.

Geographical variation of Crohn's disease residual incidence in the Province of Quebec, Canada

Background

Crohn's disease (CD) is clinically expressed as a chronic affection of the gastrointestinal tract currently known to have a multifactorial etiology involving a complex pathophysiological host response modulated by genetic susceptibilities, demographic determinants and environmental factors. With more than 20 cases per 100,000 person-years, the province of Quebec, Canada is among regions of the world with highest reported occurrence of CD in relation to other places where comparable estimates are available. This ecological study was designed to provide a medium-scale spatial exploration of CD incidence after accounting for the influence of known population and regional determinants. Health records of consulting patients in southern Quebec were compiled from 1995 to 2000 and used to estimate age and sex standardized rates per health area (n = 156). Various statistical models taking into account the regional effect of Jewish ethnicity, aboriginal ancestry, material deprivation, prescription for oral contraceptives, reportable enteric infection incidence, smoking as well as latitude and longitude locations were fitted.

Results

The final regression model presented a coefficient of determination of 22.8% and there was evidence of an eastern trend in the residual incidence (p = 0.018). Overall, the smoothed residual incidence presented a heterogeneous spatial pattern with evidence of patches (multiple health areas) of high, low and contrasting values. Health areas with most extreme incidence residuals where also distributed over the whole province including one area in the metropolitan area of Montreal and others in surrounding areas.

Conclusions

These findings suggest that known populational and regional factors derived through census information only explain a limited fraction of the geographical variation of CD incidence and lead to speculate that the effects of these factors may be incompletely captured (imperfect construction of proxy variables) or that other important factors remain unmeasured. In this view, markers of genetic profiles of homogeneous sub-populations, and other factors linked to agroenvironmental microbial exposure should be further investigated. Once accounting for known factors, it would also be worth comparing adjacent geographical areas demonstrating abrupt changes in residual incidence rates to further explore effect linked to regional factors from those resulting from various reporting systems.

Natural history and complications of IBD

Inflammatory bowel diseases (IBD), mainly ulcerative colitis and Crohn's disease, are chronic, heterogenic, lifelong illnesses with young age of onset and a great potential for disability. The natural history of these diseases is influenced by multiple factors of environmental and genetic origin. Multidisciplinary research has increased our knowledge of the mechanisms involved during the development and outcome of the diseases, including disease complications. Immunomodulatory treatment has demonstrated greatly improved efficacy in moderate to severe disease activity. The long-term effect on the natural course of disease and sustained reduced burden on society over many years require study. This article summarizes recent knowledge on factors influencing the natural history of IBD, including the impact of treatment. Increased understanding of disease mechanisms is needed as a basis for new treatment strategies in the future.

[Inflammatory bowel disease: genetic or environmental diseases?]

Pathophysiology of inflammatory bowel diseases depends on the interaction between genetic susceptibility and environmental factors leading to a deregulated immune intestinal response resulting in bowel lesions. Epidemiologic variations of inflammatory bowel diseases with time (incidence, prevalence) and space suggest a role for risk environmental factors, but so far only smoking habits and appendectomy have been identified as influencing the risk of occurrence and the course of the diseases. Studies of monozygotic and dizygotic twins and the existence of familial aggregation are strong evidence for an important, but not exclusive, role for genetic susceptibility. Since the discovery of NOD2/CARD15 mutations, numerous genes have been associated with inflammatory bowel diseases, some of them involved in the regulation of innate immunity and cellular clearance of infectious agents (autophagy). Thus, new hypothesis include a key role of mucosal human microbiota which could be partly influenced by environmental factors generated by modern life. The improvement of life hygiene, the change of food composition and habits, the industrial pollution in developed countries, may influence, directly or by the way of modifying intestinal human microbiota, inflammatory bowel diseases risk occurrence.