Bacterial-metal interactions: the potential role of aluminum and other trace elements in the etiology of Crohn's disease

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.

Protocatechuic Acid Alleviates Dextran-Sulfate-Sodium-Induced Ulcerative Colitis in Mice via the Regulation of Intestinal Flora and Ferroptosis

Protocatechuic acid (PCA) is a natural component with multiple biological activities. However, the underlying mechanisms of the effects of PCA on anti-ulcerative colitis (UC) are unclear. A UC mouse model was established by allowing the mice to freely drink a dextran sulfate sodium solution. The mice were administered PCA intragastrically for 7 days. Histological pathology, intestinal flora, and ferroptosis regulators were determined in vivo. Additionally, ferroptotic Caco-2 cells were modeled to investigate the role of PCA in ferroptosis. Our results showed that PCA reduced the levels of the disease activity index, inflammatory factors, and histological damage in UC mice. We also found that the regulation of intestinal flora, especially Bacteroidetes, was one of the potential mechanisms underlying the protective effects of PCA anti-UC. Moreover, PCA downregulated the level of ferroptosis in the colon tissue, as evidenced by a reduced iron overload, decreased glutathione depletion, and a lower level of malondialdehyde production compared with the model group. Similar effects of PCA on ferroptosis were observed in Erastin-treated Caco-2 cells. The results obtained using reactive oxygen species assays and the changes in mitochondrial structure observed via scanning electron microscopy also support these results. Our findings suggested that PCA protected against UC by regulating intestinal flora and ferroptosis.

Phenolic Compounds Impact on Rheumatoid Arthritis, Inflammatory Bowel Disease and Microbiota Modulation

Non-communicable chronic diseases (NCDs) are nowadays the principal cause of death, especially in most industrialized nations. These illnesses have increased exponentially with the consumption of diets very high in fat and sugar, not to mention stress and physical inactivity among other factors. The potential impact of suboptimal diets on NCDs’ morbidity and mortality rates brings to the forefront the necessity for a new way of improving dietary habits. The literature provides extensive scientific work that presents evidence that phenolic compounds from diets have antioxidant, anti-inflammatory and antiproliferative activities that impact human health. Gut microbiota modulation by some phenolic compounds leads to favorable changes in abundance, diversity, and in the immune system. However, polyphenol’s limited bioavailability needs to be overcome, highlighting their application in new delivery systems and providing their health benefits in well-established ways such as health maintenance, treatment or adjuvant to conventional pharmacological treatments. In this context, novel dietary approaches, including new food supplements, have emerged to prevent diseases and preserve health.

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.

Metabolomic analysis reveals the mechanism of aluminum cytotoxicity in HT-29 cells

BACKGROUND

Aluminum (Al) is toxic to animals and humans. The most common sources of human exposure to Al are food and beverages. The intestinal epithelium is the first barrier against Al-induced toxicity. In this study, HT-29, a human colon cancer cell line, was selected as an in vitro model to evaluate the Al-induced alteration in metabolomic profiles and explore the possible mechanisms of Al toxicity.

METHODS

MTT assay was performed to determine the half-maximal inhibitory concentration of Al ions. Liquid chromatography-mass spectrometry (LC-MS) was used for metabolomic analysis, and its results were further confirmed using quantitative reverse transcription polymerase chain reaction (RT-qPCR) of nine selected genes.

RESULTS

Al inhibited the growth of the HT-29 cells, and its half-maximal dose for the inhibition of cell proliferation was found to be four mM. This dose was selected for further metabolomic analysis, which revealed that 81 metabolites, such glutathione (GSH), phosphatidylcholines, phosphatidylethanolamines, and creatine, and 17 metabolic pathways, such as the tricarboxylic acid cycle, pyruvate metabolism, and GSH metabolism, were significantly altered after Al exposure. The RT-qPCR results further confirmed these findings.

CONCLUSION

The metabolomics and RT-qPCR results indicate that the mechanisms of Al-induced cytotoxicity in HT-29 cells include cellular apoptosis, oxidative stress, and alteration of lipid, energy, and amino acid metabolism.

The Impact of Western Diet and Nutrients on the Microbiota and Immune Response at Mucosal Interfaces

Recent findings point toward diet having a major impact on human health. Diets can either affect the gut microbiota resulting in alterations in the host’s physiological responses or by directly targeting the host response. The microbial community in the mammalian gut is a complex and dynamic system crucial for the development and maturation of both systemic and mucosal immune responses. Therefore, the complex interaction between available nutrients, the microbiota, and the immune system are central regulators in maintaining homeostasis and fighting against invading pathogens at mucosal sites. Westernized diet, defined as high dietary intake of saturated fats and sucrose and low intake of fiber, represent a growing health risk contributing to the increased occurrence of metabolic diseases, e.g., diabetes and obesity in countries adapting a westernized lifestyle. Inflammatory bowel diseases (IBD) and asthma are chronic mucosal inflammatory conditions of unknown etiology with increasing prevalence worldwide. These conditions have a multifactorial etiology including genetic factors, environmental factors, and dysregulated immune responses. Their increased prevalence cannot solely be attributed to genetic considerations implying that other factors such as diet can be a major contributor. Recent reports indicate that the gut microbiota and modifications thereof, due to a consumption of a diet high in saturated fats and low in fibers, can trigger factors regulating the development and/or progression of both conditions. While asthma is a disease of the airways, increasing evidence indicates a link between the gut and airways in disease development. Herein, we provide a comprehensive review on the impact of westernized diet and associated nutrients on immune cell responses and the microbiota and how these can influence the pathology of IBD and asthma.

Gut: An underestimated target organ for Aluminum

Since World War II, several factors such as an impressive industrial growth, an enhanced environmental bioavailability and intensified food consumption have contributed to a significant amplification of human exposure to aluminum. Aluminum is particularly present in food, beverages, some drugs and airbone dust. In our food, aluminum is superimposed via additives and cooking utensils. Therefore, the tolerable intake of aluminum is exceeded for a significant part of the world population, especially in children who are more vulnerable to toxic effects of pollutants than adults. Faced with this oral aluminum influx, intestinal tract is an essential barrier, especially as 38% of ingested aluminum accumulates at the intestinal mucosa. Although still poorly documented to date, the impact of oral exposure to aluminum in conditions relevant to real human exposure appears to be deleterious for gut homeostasis. Aluminum ingestion affects the regulation of the permeability, the microflora and the immune function of intestine. Nowadays, several arguments are consistent with an involvement of aluminum as an environmental risk factor for inflammatory bowel diseases.

Inflammatory bowel disease

Scandinavian researchers have contributed to the present understanding of inflammatory bowel disease (IBD). Important epidemiological data and family risk factors have been reported from all the Nordic countries, original twin studies mainly from Denmark and Sweden, and relationships to cancer and surgery mostly from Sweden. In collaboration with the industry, development of medical compounds was for a long time in the front line of international research, and the Scandinavian countries participated in the clinical breakthrough of biologic treatment. At present, many Nordic centers are working in the forefront of IBD research. An increasing number of young investigators have entered the scene along with the extended distribution of University clinics and research laboratories in these countries. This presentation of IBD gives a brief overview in the fields of clinical epidemiology and molecular biology. Many areas are covered by International collaborations with partners from Nordic centers. IBD was a topic focused by the founders of Scandinavian Journal of Gastroenterology. After 50 years one may state that the journal's history reflects important pieces of scientific knowledge within these diseases. The early scope of Johannes Myren for IBD was shown through his work in the original World Association of Gastroenterology (OMG), and after 50 years we can clearly support the view that global perspectives in IBD are increasingly important.

Aluminum enhances inflammation and decreases mucosal healing in experimental colitis in mice

The increasing incidence of inflammatory bowel diseases (IBDs) in developing countries has highlighted the critical role of environmental pollutants as causative factors in their pathophysiology. Despite its ubiquity and immune toxicity, the impact of aluminum in the gut is not known. This study aimed to evaluate the effects of environmentally relevant intoxication with aluminum in murine models of colitis and to explore the underlying mechanisms. Oral administration of aluminum worsened intestinal inflammation in mice with 2,4,6-trinitrobenzene sulfonic acid- and dextran sodium sulfate-induced colitis and chronic colitis in interleukin 10-negative (IL10(-/-)) mice. Aluminum increased the intensity and duration of macroscopic and histologic inflammation, colonic myeloperoxidase activity, inflammatory cytokines expression, and decreased the epithelial cell renewal compared with control animals. Under basal conditions, aluminum impaired intestinal barrier function. In vitro, aluminum induced granuloma formation and synergized with lipopolysaccharide to stimulate inflammatory cytokines expression by epithelial cells. Deleterious effects of aluminum on intestinal inflammation and mucosal repair strongly suggest that aluminum might be an environmental IBD risk factor.

Iron supplementation promotes gut microbiota metabolic activity but not colitis markers in human gut microbiota-associated rats

The global prevalence of Fe deficiency is high and a common corrective strategy is oral Fe supplementation, which may affect the commensal gut microbiota and gastrointestinal health. The aim of the present study was to investigate the impact of different dietary Fe concentrations on the gut microbiota and gut health of rats inoculated with human faecal microbiota. Rats (8 weeks old, n 40) were divided into five (n 8 each) groups and fed diets differing only in Fe concentration during an Fe-depletion period (12 weeks) and an Fe-repletion period (4 weeks) as follows: (1) Fe-sufficient diet throughout the study period; (2) Fe-sufficient diet followed by 70 mg Fe/kg diet; (3) Fe-depleted diet throughout the study period; (4) Fe-depleted diet followed by 35 mg Fe/kg diet; (5) Fe-depleted diet followed by 70 mg Fe/kg diet. Faecal and caecal samples were analysed for gut microbiota composition (quantitative PCR and pyrosequencing) and bacterial metabolites (HPLC), and intestinal tissue samples were investigated histologically. Fe depletion did not significantly alter dominant populations of the gut microbiota and did not induce Fe-deficiency anaemia in the studied rats. Provision of the 35 mg Fe/kg diet after feeding an Fe-deficient diet significantly increased the abundance of dominant bacterial groups such as Bacteroides spp. and Clostridium cluster IV members compared with that of an Fe-deficient diet. Fe supplementation increased gut microbial butyrate concentration 6-fold compared with Fe depletion and did not affect histological colitis scores. The present results suggest that Fe supplementation enhances the concentration of beneficial gut microbiota metabolites and thus may contribute to gut health.

Human exposure to aluminium

Human activities have circumvented the efficient geochemical cycling of aluminium within the lithosphere and therewith opened a door, which was previously only ajar, onto the biotic cycle to instigate and promote the accumulation of aluminium in biota and especially humans. Neither these relatively recent activities nor the entry of aluminium into the living cycle are showing any signs of abating and it is thus now imperative that we understand as fully as possible how humans are exposed to aluminium and the future consequences of a burgeoning exposure and body burden. The aluminium age is upon us and there is now an urgent need to understand how to live safely and effectively with aluminium.

Nutrigenomics and nutrigenetics in inflammatory bowel diseases

Inflammatory bowel diseases (IBD) including ulcerative colitis and Crohn's disease are chronically relapsing, immune-mediated disorders of the gastrointestinal tract. A major challenge in the treatment of IBD is the heterogenous nature of these pathologies. Both, ulcerative colitis and Crohn's disease are of multifactorial etiology and feature a complex interaction of host genetic susceptibility and environmental factors such as diet and gut microbiota. Genome-wide association studies identified disease-relevant single-nucleotide polymorphisms in approximately 100 genes, but at the same time twin studies also clearly indicated a strong environmental impact in disease development. However, attempts to link dietary factors to the risk of developing IBD, based on epidemiological observations showed controversial outcomes. Yet, emerging high-throughput technologies implying complete biological systems might allow taking nutrient-gene interactions into account for a better classification of patient subsets in the future. In this context, 2 new scientific fields, "nutrigenetics" and "nutrigenomics" have been established. "Nutrigenetics," studying the effect of genetic variations on nutrient-gene interactions and "Nutrigenomics," describing the impact of nutrition on physiology and health status on the level of gene transcription, protein expression, and metabolism. It is hoped that the integration of both research areas will promote the understanding of the complex gene-environment interaction in IBD etiology and in the long-term will lead to personalized nutrition for disease prevention and treatment. This review briefly summarizes data on the impact of nutrients on intestinal inflammation, highlights nutrient-gene interactions, and addresses the potential of applying "omic" technologies in the context of IBD.

Juvenile ferric iron prevents microbiota dysbiosis and colitis in adult rodents

AIM: To assess whether juvenile chronic ferric iron ingestion limit colitis and dysbiosis at adulthood in rats and mice.

METHODS: Two sets of experiments were designed. In the first set, recently weaned mice were either orally administered ferrous (Fe²⁺) iron salt or ferric (Fe³⁺) microencapsulated iron for 6 wk. The last week of experiments trinitrobenzene sulfonic acid (TNBS) colitis was induced. In the second set, juvenile rats received the microencapsulated ferric iron for 6 wk and were also submitted to TNBS colitis during the last week of experiments. In both sets of experiments, animals were sacrificed 7 d after TNBS instillation. Severity of the inflammation was assessed by scoring macroscopic lesions and quantifying colonic myeloperoxidase (MPO) activity. Alteration of the microflora profile was estimated using quantitative polymerase chain reaction (qPCR) by measuring the evolution of total caecal microflora, Bacteroidetes, Firmicutes and enterobacteria.

RESULTS: Neither ferrous nor ferric iron daily exposures at the juvenile period result in any effect in control animals at adulthood although ferrous iron repeated administration in infancy limited weight gain. Ferrous iron was unable to limit the experimental colitis (1.71 ± 0.27 MPO U/mg protein vs 2.47 ± 0.22 MPO U/mg protein in colitic mice). In contrast, ferric iron significantly prevented the increase of MPO activity (1.64 ± 0.14 MPO U/mg protein) in TNBS-induced colitis. Moreover, this positive effect was observed at both the doses of ferric iron used (75 and 150 mg/kg per day po - 6 wk). In the study we also compared, in both rats and mice, the consequences of chronic repeated low level exposure to ferric iron (75 mg/kg per day po - 6 wk) on TNBS-induced colitis and its related dysbiosis. We confirmed that ferric iron limited the TNBS-induced increase of MPO activity in both the rodent species. Furthermore, we assessed the ferric iron incidence on TNBS-induced intestinal microbiota dysbiosis. At first, we needed to optimize the isolation and quantify DNA copy numbers using standard curves to perform by qPCR this interspecies comparison. Using this approach, we determined that total microflora was similar in control rats and mice and was mainly composed of Firmicutes and Bacteroidetes at a ratio of 10/1. Ferric juvenile administration did not modify the microflora profile in control animals. Total microflora numbers remained unchanged whichever experimental conditions studied. Following TNBS-induced colitis, the Firmicutes/Bacteroidetes ratio was altered resulting in a decrease of the Firmicutes numbers and an increase of the Bacteroidetes numbers typical of a gut inflammatory reaction. In parallel, the subdominant population, the enterobacteria was also increased. However, ferric iron supplementation for the juvenile period prevented the increase of Bacteroidetes and of enterobacteria numbers consecutive to the colitis in both the studied species at adulthood.

CONCLUSION: Rats and mice juvenile chronic ferric iron ingestion prevents colitis and dysbiosis at adulthood as assessed by the first interspecies comparison.

Aluminum as an adjuvant in Crohn's disease induction

Alum (AlK(SO(4))(2)) is an adjuvant commonly utilized in vaccines, and is a ubiquitous element used extensively in contemporary life. Food, air, water, waste, the earth's surface, and pharmaceuticals all represent pathways of aluminum (Al) exposure. Crohn's disease (CD) is a chronic relapsing intestinal inflammation in genetically susceptible individuals and is caused by yet unidentified environmental factors. Al is a potential factor for the induction of inflammation in CD, and its immune activities share many characteristics with the immune pathology of CD: many luminal bacterial or dietary compounds can be adsorbed to the metal surface and induce Th1 profile cytokines, shared cytokines/chemokines, co-stimulatory molecules, and intracellular pathways and stress-related molecular expression enhancement, affecting intestinal macrobiota, trans-mural granuloma formation, and colitis induction in an animal CD model. The inflammasome plays a central role in Al mode of action and in CD pathophysiology. It is suggested that Al adjuvant activity can fit between the aberrations of innate and adaptive immune responses occurring in CD. The CD mucosa is confronted with numerous inappropriate bacterial components adsorbed on the Al compound surface, constituting a pro-inflammatory supra-adjuvant. Al fits the diagnostic criteria of the newly described autoimmune/inflammatory syndrome induced by adjuvants. If a cause and effect relationship can be established, the consequences will greatly impact public health and CD prevention and management.

Debugging the intestinal microbiota in IBD

Besides its role in repelling enteropathogenic infections, the gastrointestinal tract is in intimate contact with commensal microbiota. Tremendous advances have been made in determining the pivotal role of the microbiota in both tissue homeostasis and metabolism, as well as in the initiation and maintenance of inflammatory lesions in inflammatory bowel diseases. A better understanding of human gut microbiota could provide innovative targets for treating and/or curing such common immunopathologies of the gastrointestinal tract.

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

Inflammatory bowel disease refers to a group of chronic diseases of unknown etiology related to both genetic and environmental factors. In this 1990-1993 study, the authors investigated associations between the content and quality of drinking water and the incidence of inflammatory bowel disease. They used data from a population-based cohort recruited in southeastern Norway and a registry of water quality derived from Norwegian waterworks that contained measurements of iron, aluminum, acidity (pH), color, turbidity, and coliform bacteria. The authors found that risk of developing inflammatory bowel disease, including ulcerative colitis and Crohn's disease, was associated with high iron content. The relative risk of developing inflammatory bowel disease increased by 21% (95% confidence interval: 9, 34) when the iron content in the drinking water increased by 0.1 mg/L. They found no association between the diseases and aluminum in the water, color of the water, and turbidity of the water. The authors suggest that the observations can be explained by 2 mechanisms. First, high iron concentration works as a catalyst for oxidative stress, which will cause inflammation and/or increase the rate of cell mutations. Second, iron content stimulates the growth of bacteria and increases the likelihood of inappropriate immune responses in genetically predisposed individuals.

Geographic distribution and ecological studies of inflammatory bowel disease in southeastern Norway in 1990-1993

BACKGROUND

The purpose was to study the spatial distribution of cases of inflammatory bowel disease (IBD) and characterize municipalities with high incidences in a search for environmental risk factors.

METHODS

Spatial clustering of patients diagnosed with IBD during 1990-1993 were studied in 4 counties in southeastern Norway, and an ecological analysis was conducted to study the relationship between risk of IBD in the municipalities and their characteristics such as population, health care, urban/rural change, and socioeconomic change.

RESULTS

One cluster consisting of 4 municipalities was identified for IBD in Østfold county (P = 0.011). The ecological analysis showed that the incidence rate of IBD was 33% (95% confidence interval [CI]: 2%-75%) higher in municipalities with the highest level of education compared to the lowest level of education and 35% (2%-78%) higher in urban than rural municipalities. The incidence rate was 11% (1%-20%) lower in municipalities with a high urban/rural change compared to municipalities with low urban/rural change. Individuals living in high-risk municipalities were 3 times (1.57-5.45) more likely to have a first-degree family member with IBD than individuals living in normal-risk municipalities.

CONCLUSIONS

The geographic distribution of cases with IBD is not uniformly distributed and is related to urbanization, level of education, and moving pattern. Geographic distribution may be explained by either changes in environment-host relationships or neurobiological mechanisms due to stress and economic frustration. These factors and genetic predisposition might also explain increased familial clustering. Spatial clustering was significant neither for Crohn's disease CD nor ulcerative colitis (UC) but showed a stronger tendency within the CD group.

Aluminum is a potential environmental factor for Crohn's disease induction: extended hypothesis

Aluminum (Al) is a common environmental compound with immune-adjuvant activity and granulomatous inflammation inducer. Al exposure in food, additives, air, pharmaceuticals, and water pollution is ubiquitous in Western culture. Crohn's disease (CD) is a chronic relapsing intestinal inflammation in genetically susceptible individuals and is influenced by yet unidentified environmental factors. It is hypothesized, in the present review, that Al is a potential factor for induction or maintaining the inflammation in CD. Epidemiologically, CD incidence is higher in urban areas, where microparticle pollution is prevalent. Al immune activities share many characteristics with the immune pathology of CD: increased antigen presentation and APCs activation, many luminal bacterial or dietary compounds can be adsorbed to the metal and induce Th1 profile activity, promotion of humoral and cellular immune responses, proinflammatory, apoptotic, oxidative activity, and stress-related molecule expression enhancement, affecting intestinal bacterial composition and virulence, granuloma formation, colitis induction in an animal model of CD, and terminal ileum uptake. The Al-bacterial interaction, the microparticles homing the intestine together with the extensive immune activity, put Al as a potential environmental candidate for CD induction and maintenance.

Mechanisms of disease: pathogenesis of Crohn's disease and ulcerative colitis

Crohn's disease and ulcerative colitis are idiopathic, chronic, relapsing, inflammatory conditions that are immunologically mediated. Although their exact etiologies remain uncertain, results from research in animal models, human genetics, basic science and clinical trials have provided important new insights into the pathogenesis of chronic, immune-mediated, intestinal inflammation. These studies indicate that Crohn's disease and ulcerative colitis are heterogeneous diseases characterized by various genetic abnormalities that lead to overly aggressive T-cell responses to a subset of commensal enteric bacteria. The onset and reactivation of disease are triggered by environmental factors that transiently break the mucosal barrier, stimulate immune responses or alter the balance between beneficial and pathogenic enteric bacteria. Different genetic abnormalities can lead to similar disease phenotypes; these genetic changes can be broadly characterized as causing defects in mucosal barrier function, immunoregulation or bacterial clearance. These new insights will help develop better diagnostic approaches that identify clinically important subsets of patients for whom the natural history of disease and response to treatment are predictable.

Low-dose oral ferrous fumarate aggravated intestinal inflammation in rats with DSS-induced colitis

BACKGROUND

Oral ferrous iron therapy may reinforce intestinal inflammation. One possible mechanism is by catalyzing the production of reactive oxygen species. We studied the effects of low-dose oral ferrous fumarate on intestinal inflammation and plasma redox status in dextran sulfate sodium (DSS)-induced colitis in rats.

METHODS

Forty male Wistar rats were divided into 5 groups: no intervention, sham gavage (distilled water), ferrous fumarate, DSS, and ferrous fumarate + DSS. Ferrous fumarate was dissolved in distilled water (0.60 mg Fe/kg per day) and administered by gavage on days 1 to 14. All rats were fed a standard diet. Colitis was induced by 5% DSS in drinking water on days 8 to 14. Rats were killed on day 16. Histologic colitis scores, fecal granulocyte marker protein, plasma malondialdehyde, plasma antioxidant vitamins, and plasma aminothiols were measured.

RESULTS

DSS significantly increased histologic colitis scores (P < 0.001) and fecal granulocyte marker protein (P < 0.01). Ferrous fumarate further increased histologic colitis scores (P < 0.01) in DSS-induced colitis. DSS + ferrous fumarate decreased plasma vitamin A compared with controls (P < 0.01). Otherwise, no changes were seen in plasma malondialdehyde, plasma antioxidant vitamins, or plasma aminothiols.

CONCLUSION

Low-dose oral ferrous iron enhanced intestinal inflammation in DSS-induced colitis in rats.