Inflammatory bowel disease: review from the aspect of genetics

Inflammatory and Microbiota-Related Regulation of the Intestinal Epithelial Barrier

The intestinal epithelial barrier (IEB) is one of the largest interfaces between the environment and the internal milieu of the body. It is essential to limit the passage of harmful antigens and microorganisms and, on the other side, to assure the absorption of nutrients and water. The maintenance of this delicate equilibrium is tightly regulated as it is essential for human homeostasis. Luminal solutes and ions can pass across the IEB via two main routes: the transcellular pathway or the paracellular pathway. Tight junctions (TJs) are a multi-protein complex responsible for the regulation of paracellular permeability. TJs control the passage of antigens through the IEB and have a key role in maintaining barrier integrity. Several factors, including cytokines, gut microbiota, and dietary components are known to regulate intestinal TJs. Gut microbiota participates in several human functions including the modulation of epithelial cells and immune system through the release of several metabolites, such as short-chain fatty acids (SCFAs). Mediators released by immune cells can induce epithelial cell damage and TJs dysfunction. The subsequent disruption of the IEB allows the passage of antigens into the mucosa leading to further inflammation. Growing evidence indicates that dysbiosis, immune activation, and IEB dysfunction have a role in several diseases, including irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and gluten-related conditions. Here we summarize the interplay between the IEB and gut microbiota and mucosal immune system and their involvement in IBS, IBD, and gluten-related disorders.

Toll-Interacting Protein Regulates Immune Cell Infiltration and Promotes Colitis-Associated Cancer

Expression of Toll-interacting protein (Tollip), a potent TLR modulator, decreases in patients with inflammatory bowel diseases (IBD), whereas Tollip^−/− mice are susceptible to colitis. Tollip expression was shown to be reduced in sporadic adenoma . In contrast, we found variable Tollip expression in patients with colitis-associated adenomas. In Tollip^−/− mice challenged to develop colitis-associated cancer (CAC), tumor formation was significantly reduced owing to decreased mucosal proliferative and apoptotic indexes. This protection was associated with blunt inflammatory responses without significant changes in microbial composition. mRNA expression of Cd62l and Ccr5 homing receptors was reduced in colons of untreated Tollip^−/− mice, whereas CD62L⁺ CD8⁺ T cells accumulated in the periphery. In Tollip-deficient adenomas Ctla-4 mRNA expression and tumor-infiltrating CD4⁺ Foxp3⁺ regulatory T cell (Treg) were decreased. Our data show that protection from CAC in Tollip-deficient mice is associated with defects in lymphocyte accumulation and composition in colitis-associated adenomas.

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Tollip protects from colitis but promotes colitis-associated cancer onset

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Tollip-deficient tumors demonstrate decreased cell turnover and inflammation

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Tollip ablation favors naive CD8⁺ T cell accumulation in peripheral lymphoid organs

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Regulatory T cell accumulation is aberrant in Tollip-deficient tumors

Potential role of regulatory B cells in immunological diseases

Regulatory B cells (Bregs) are immune-modulating cells that affect the immune system by producing cytokines or cellular interactions. These cells have immunomodulatory effects on the immune system by cytokine production. The abnormalities in Bregs could be involved in various disorders such as autoimmunity, chronic infectious disease, malignancies, allergies, and primary immunodeficiencies are immune-related scenarios. Ongoing investigation could disclose the biology and the exact phenotype of these cells and also the assigned mechanisms of action of each subset, as a result, potential therapeutic strategies for treating immune-related anomalies. In this review, we collect the findings of human and mouse Bregs and the therapeutic efforts to change the pathogenicity of these cells in diverse disease.

A Direct Effect of Sex Hormones on Epithelial Barrier Function in Inflammatory Bowel Disease Models

BACKGROUND

Pregnancy is often described as an immune-tolerant state, and a disease modulatory role for pregnancy on inflammatory bowel disease (IBD) has been suggested. The direct effect of estrogen and progesterone on the intestinal epithelial barrier is underexplored. We investigated the direct consequences of these pregnancy hormones on barrier cells and their function.

METHODS

We used IBD patient-derived inflammatory organoid models and 2D cell lines models. Epithelial barrier function was analyzed by measuring transepithelial electrical resistance; wound closure was determined by scratch assay; and cell viability was measured by MTT assays. Pro-inflammatory cytokine production was determined by enzyme-linked immunosorbent assays. Molecular modulation of endoplasmic reticulum (ER) stress induced by tunicamycin was studied by western blot analysis of the ER stress markers GRP78, CHOP and p-IRE1.

RESULTS

Progesterone and estrogen improved wound healing and epithelial barrier function in intestinal epithelial cells via upregulation of tight junction proteins. Furthermore, these sex hormones significantly reduced ER-stress and reduce pro-inflammatory cytokine production in intestinal epithelial models.

CONCLUSION

Our study shows that estrogen and progesterone alleviate ER stress, decrease pro-inflammatory cytokine production, stimulate wound healing, and increase barrier function of epithelial cells. Combined, these data suggest that pregnancy hormones can have beneficial effects on disease activity by positively modulating the intestinal epithelial lining.

Beneficial effects of dual TORC1/2 inhibition on chronic experimental colitis

BACKGROUND AND AIM

AZD8055, a new immunosuppressive reagent, a dual TORC1/2 inhibitor, had been used successfully in animal models for heart transplantation. The aim of this study was to evaluate the effects and mechanisms of AZD8055 on chronic intestinal inflammation.

METHODS

Dextran sulfate sodium (DSS) - induced chronic colitis was used to investigate the effects of AZD8055 on the development of colitis. Colitis activity was monitored by body weight assessment, colon length, histology and cytokine profile analysis.

RESULTS

AZD8055 treatment significantly alleviated the severity of colitis, as assessed by colonic length and colonic damage. In addition, AZD8055 treatment decreased the colonic CD4+ T cell numbers and reduced both Th1 and Th17 cell activation and cytokine production. The percentages of Treg cells in the colon were also expanded by AZD8055 treatment. Furthermore, AZD8055 effectively inhibited mTOR downstream proteins and signal transducer and activator of transcription related proteins in CD4+ T cells of intestinal lamina propria.

CONCLUSIONS

These findings increased our understanding of DSS-induced colitis and shed new lights on mechanisms of digestive tract chronic inflammation. Dual TORC1/2 inhibition showed potent anti-inflammatory and immune regulation effects by targeting critical signaling pathways. The results supported the strategy of using dual mTOR inhibitor to treat inflammatory bowel disease.

Heme Oxygenase-1 as a Modulator of Intestinal Inflammation Development and Progression

Heme Oxygenase 1 (HMOX1) is an enzyme that catalyzes the reaction that degrades the heme group contained in several important proteins, such as hemoglobin, myoglobin, and cytochrome p450. The enzymatic reaction catalyzed by HMOX1 generates Fe2+, biliverdin and CO. It has been shown that HMOX1 activity and the by-product CO can downmodulate the damaging immune response in several models of intestinal inflammation as a result of pharmacological induction of HMOX1 expression and the administration of non-toxic amounts of CO. Inflammatory Bowel Diseases, which includes Crohn's Disease (CD) and Ulcerative Colitis (UC), are one of the most studied ailments associated to HMOX1 effects. However, microbiota imbalances and infections are also important factors influencing the occurrence of acute and chronic intestinal inflammation, where HMOX1 activity may play a major role. As part of this article we discuss the immune modulatory capacity of HMOX1 during IBD, as well during the infections and interactions with the microbiota that contribute to this inflammatory disease.

Analysis of the association of single nucleotide polymorphisms of interleukin-23 receptor (IL-23R) and inflammatory bowel disease in a Chinese Han cohort

Inflammatory bowel disease (IBD) is a chronic, complex genetic disease with rapidly increasing prevalence in China. The interactions of genetic, environmental, and microbial factors contribute to the development of IBD, however, the precise etiologies of IBD are not well understood yet. Interleukin-23 receptor (IL-23R) encodes a subunit of receptor for IL-23, which is an important proinflammatory cytokine. In this study, we investigated the relationship between the single nucleotide polymorphism (SNP) of IL-23R gene and IBD in Chinese Han population. We genotyped three nonsynonymous IL-23R SNPs with amino acid changes (rs11209026, p.Arg381Gln; rs41313262 p.Val362Ile and rs11465797 p.Thr175Asn) in 198 patients with IBD (124 UC and 74 CD) and 100 healthy controls. The prevalence of the A allele in IL-23R Arg381Gln of CD appeared less than controls, but it was not statistically significant (2.70% vs. 6.00%, p > 0.05). There was no statistical difference between UC and controls (5.65% vs. 6.00%, p = 0.91). The p.Val362Ile variant was present in 2.42% of UC patients, in 2.70% of CD patients, which was similar in the control (2.00%). There was no statistical difference among these three groups. We did not detect Thr175Asn (rs11465797 c.524 C>A) in all the three groups. In conclusion, our study demonstrated that the p.Val362Ile and Arg381Gln were not associated with susceptibility to IBD in Chinese Han population.

A Potential Role of Salmonella Infection in the Onset of Inflammatory Bowel Diseases

Inflammatory bowel disease (IBD) includes a set of pathologies that result from a deregulated immune response that may affect any portion of the gastrointestinal tract. The most prevalent and defined forms of IBD are Crohn’s disease and ulcerative colitis. Although the etiology of IBD is not well defined, it has been suggested that environmental and genetic factors contribute to disease development and that the interaction between these two factors can trigger the pathology. Diet, medication use, vitamin D status, smoking, and bacterial infections have been proposed to influence or contribute to the onset or development of the disease in susceptible individuals. The infection with pathogenic bacteria is a key factor that can influence the development and severity of this disease. Here, we present a comprehensive review of studies performed in human and mice susceptible to IBD, which supports the notion that infection with bacterial pathogens, such as Salmonella, could promote the onset of IBD due to permanent changes in the intestinal microbiota, disruption of the epithelial barrier and alterations of the intestinal immune response after infection.

The role of B-1 cells in inflammation

B-1 lymphocytes exhibit unique phenotypic, ontogenic, and functional characteristics that differ from the conventional B-2 cells. B-1 cells spontaneously secrete germline-like, repertoire-skewed polyreactive natural antibody, which acts as a first line of defense by neutralizing a wide range of pathogens before launching of the adaptive immune response. Immunomodulatory molecules such as interleukin-10, adenosine, granulocyte-macrophage colony-stimulating factor, interleukin-3, and interleukin-35 are also produced by B-1 cells in the presence or absence of stimulation, which regulate acute and chronic inflammatory diseases. Considerable progress has been made during the past three decades since the discovery of B-1 cells, which has improved not only our understanding of their phenotypic and ontogenic uniqueness but also their role in various inflammatory diseases including influenza, pneumonia, sepsis, atherosclerosis, inflammatory bowel disease, autoimmunity, obesity and diabetes mellitus. Recent identification of human B-1 cells widens the scope of this field, leading to novel innovations that can be implemented from bench to bedside. Among the vast number of studies on B-1 cells, we have carried out a literature review highlighting current trends in the study of B-1 cell involvement during inflammation, which may result in a paradigm shift toward sustainable therapeutics in various inflammatory diseases.

Downregulation of serotonin reuptake transporter gene expression in healing colonic mucosa in presence of remaining low-grade inflammation in ulcerative colitis

BACKGROUND AND AIM

The serotonin reuptake transporter (SERT) terminates serotonin activity by removing it from interstitial space. Downregulated colonic SERT expression has been reported in irritable bowel disease (IBS), and symptoms resembling IBS occur in cases of inflammatory bowel disease (IBD) in remission; thus, a common pathogenesis for IBS and IBD is possible. However, little is known regarding SERT expression in colonic mucosa of IBD patients during healing.

METHODS

Twenty-two ulcerative colitis (UC) patients underwent colonoscopy examinations, during which inflamed mucosa was distinguished from that undergoing healing. Healing mucosa was classified into regular and irregular vessel patterns by narrowband imaging magnifying colonoscopy. Expressions of SERT and various inflammation-related genes in biopsy samples were assessed using a polymerase chain reaction array system and real-time polymerase chain reaction. Colitis model mice were established by administration of dextran sodium sulfate or transfer of CD4(+) T cells isolated from SAMP1 mice, then time-course changes of SERT and inflammatory gene expressions were observed in colonic mucosa.

RESULTS

In UC patients, SERT expression in inflamed mucosa was significantly lower than in healing mucosa. SERT expression was decreased in healing mucosa with an irregular vessel pattern with mildly increased levels of inflammatory gene expression. In mice, SERT expression was suppressed in inflamed mucosa and continuously observed with low-grade mucosal inflammation during colitis healing.

CONCLUSIONS

Sserotonin reuptake transporter expression is downregulated in healing colonic mucosa of UC patients and that suppression may be dependent on the presence of remaining low-grade colonic inflammation.

Preventing Overheating: Tight Control of Gut Innate Immunity in Health and Disease

Innate immune responses are key to maintain adequate host-microbial interactions. However, those signals are needed to efficiently trigger rapid and targeted antimicrobial responses in case of pathogen encounter. Several molecules have evolved to regulate intensity and coordinate signaling to avoid detrimental consequences to the host. Regulation can occur at the cell surface, within the cytoplasm, and at the transcriptional level. Innate immune regulation seems to be equally important than stimulation, as disruption of immunoregulatory molecules modulates the risk for several diseases. This is the case for colitis and inflammatory bowel disease but also colorectal cancer and intestinal infections. In this review, we recapitulate the molecular mechanisms underlying regulation of innate immune signals and mention their implications in several disease states including inflammatory bowel disease.

Berberine ameliorates TNBS induced colitis by inhibiting inflammatory responses and Th1/Th17 differentiation

Th1 and Th17 cells, and their associated cytokines, have been associated with the pathogenesis of Crohn's disease. Berberine (BBR), a compound long used in traditional Chinese medicines, has been reported to have therapeutic effects in treating experimental colitis. In this study, we show that BBR had a protective effect on mice with TNBS-induced colitis. BBR inhibited levels of IFN-γ, IL-17, IL-6, IL-1β and TNF-α both in the local colon and sera, and transiently increased levels of IL-22. BBR also markedly increased sIgA expression in the colon. BBR had pronounced effects on macrophage populations. Treatment with BBR adjusted the M2/M1 ratio. In addition, BBR exerted effects on adaptive immunity by suppressing numbers of Th1 and Th17 cells, as well as expression levels of their associated cytokines and transcriptional factors. BBR downregulated STAT3 and STAT1 phosphorylation, and inhibited phosphorylation of NF-kB. In vitro experiments showed that BBR inhibited the differentiation of Th17 and, to a lesser degree, Th1 cells, without affecting regulatory T cells. Therefore, we conclude that BBR plays a regulatory role in modulating the balance of immune responses in TNBS-induced colitis. Our study will help us understand the regulatory mechanisms exerted by BBR in the treatment of IBD.

Inflammatory bowel disease in pediatric and adolescent patients: A biomolecular and histopathological review

Crohn’s disease (CD) and ulcerative colitis (UC) are the two main forms of inflammatory bowel disease (IBD) with both overlapping and distinct clinical, pathological and biomolecular features. It has been suggested that pediatric IBD is a distinct disease entity, with probably different disease subtypes.The aim of this study is to review and summarize the evolution of the current concept of pediatric IBD. The results of this review reinforce the idea that pediatric CD and UC may be further classified in various clinicopathologic entities. For clinicians and pathologists convenience, practical algorithms for the distinction of the various subphenotypes of pediatric IBD are also provided.

Genomic ATG16L1 risk allele-restricted Paneth cell ER stress in quiescent Crohn's disease

OBJECTIVE

Although genome wide association studies have partly uncovered the genetic basis of Crohn's disease (CD), it remains a challenge to link genetic polymorphisms to functional intestinal phenotypes. Paneth cells are specialised antimicrobial epithelial cells localised to the small-intestinal crypt-base. Here, we investigate whether genomic variations in ATG16L1 affect Paneth cell function.

DESIGN

Genomic variation of ATG16L1 (T300A, rs2241880) was determined in DNA from 78 patients with CD and 12 healthy controls. Paraffin-embedded ileal biopsies from patients with genotype AA (n=17), GA (n=38) and patients with the GG allele (n=23) were stained for GRP78, phospho-EIF2α, lysozyme, cleaved-caspase 3, phosphohistone H3, phospho-IκB, p65, phospho-p38MAPK and PHLDA1. Microbial composition of biopsies was assessed by PCR. Disease phenotype was scored.

RESULTS

In patients with quiescent disease but with an ATG16L1 risk allele, the endoplasmic reticulum (ER) stress markers GRP78 and pEIF2α were highly expressed in Paneth cells. Other CD risk gene variations did not correlate with Paneth cell ER stress. Functionally, patients with ER-stressed Paneth cells showed no changes in intestinal epithelial cells proliferation or apoptosis, Paneth cell or stem cell numbers, p65, phospho-IκB and phospho-p38 staining. However, a significantly increased presence of adherent-invasive Escherichia coli was observed in biopsies from patients with ER-stressed Paneth cells. Phenotypically, patients with GRP78 positive Paneth cells have relatively less colonic disease over ileal disease (-21%, p=0.04), more fistulas (+21%, p=0.05) and an increased need for intestinal surgery (+38%, p=0.002).

CONCLUSIONS

The ATG16L1 T300A polymorphism defines a specific subtype of patients with CD, characterised by Paneth cell ER stress even during quiescent disease. Paneth cell ER stress correlates with bacterial persistence, and is thus likely to modulate antimicrobial functionality of this cell type in patients with CD.

Tollip or not Tollip: what are the evolving questions behind it?

Tollip plays an important role in the interleukin-1 receptor IL-1R and Toll pathways. As a modulator of the immune pathway, it indirectly controls the amount of antimicrobial peptides. This could indicate a vital step in maintaining animal immune systems and preventing infection. Evolutionary questions are crucial to understanding the conservation and functioning of the biochemical pathways like the Tollip-mediated one. Through an analysis of 36 sequences of the Tollip protein from different animal taxa, downloaded from Kyoto Encyclopedia of Genes and Genomes (KEGG) databank, we inferred diverse evolutionary parameters, such as molecular selection and structure conservation, by analyzing residue by residue, beyond the canonical parameters to this type of study, as maximum likelihood trees. We found that Tollip presented different trends in its evolving history. In primates, the protein is becoming more unstable, just the opposite is observed in the arthropod group. The most interesting finding was the concentration of positively selected residues at amino terminal ends. Some observed topological incongruences in maximum likelihood trees of complete and curated Tollip data sets could be explained through horizontal transfers, evidenced by recombination detection. These results suggest that there is more to be researched and understood about this protein.

Role of regulatory B cells in chronic intestinal inflammation: association with pathogenesis of Crohn's disease

The role of regulatory B cells (Bregs) producing interleukin (IL)-10 in the pathogenesis of inflammatory bowel diseases remains unknown. We investigated IL-10 production in B cells from patients with inflammatory bowel diseases and immunoregulatory functions of Bregs in experimental colitis mouse models. CpG DNA-induced IL-10 production in peripheral blood B cells isolated from patients with inflammatory bowel diseases and control subjects was examined. CD19 and CD1d were used for evaluating possible cell surface markers of Bregs. Colitis models of severe combined immunodeficiency mice were established by adoptive transfer of whole CD4 T cells or regulatory T cell (Treg)-depleted T cells (CD4CD25) isolated from SAMP1/Yit mice and the function of Bregs in intestinal inflammation was elucidated by evaluating the effects of cotransfer of whole or Breg-depleted B cells. CpG DNA-induced IL-10 production was significantly decreased in B cells from patients with Crohn's disease (CD), as compared with those from healthy controls, whereas Bregs were found to be enriched in a population of CD19 and CD1d B cells isolated from both human and mouse samples. The severity of intestinal inflammation was significantly increased in the Breg-depleted mice, with similar results also found in adoptive transfer colitis model mice even after Treg depletion. Our findings show that Bregs, characterized by the cell surface markers CD19 and CD1d, significantly reduced experimental colitis regardless of the presence or absence of Tregs. These results suggest that a deficiency or decrease of Bregs function exacerbates intestinal inflammation, which may be associated with the pathogenesis of CD.

The winding road to understanding the neonatal origins of inflammatory gastrointestinal disorders

Beginning with the observation that birth weight correlates with increased risk of cardiovascular disease, the concept of neonatal programming, that the environmental influence on fetal and neonatal development results in modification of the risk profile for adult disease, has begun to emerge as an important component to understanding the origin of chronic diseases of many different organ systems. Until recently, the gastrointestinal system has not been considered. Our understanding of the pathogenesis of many intestinal inflammatory disorders is still incomplete; however, a brief review of what is known reveals several opportunities for the early intraluminal environment to affect the development of the intestinal immune system. Early clinical observations such as the increased risk of celiac disease observed in those born by cesarean section and the protective effect of breast-feeding against inflammatory bowel disease and celiac disease support the role of neonatal programming in the development of chronic inflammatory gastrointestinal disease. Additional, more robust clinical studies are needed to confirm this role. Furthermore, examination of the possible mechanisms of immune phenotype modification is necessary.

Sirolimus ameliorates inflammatory responses by switching the regulatory T/T helper type 17 profile in murine colitis

Inflammatory bowel disease is characterized by dysregulated immune responses in inflamed intestine, with dominance of interleukin-17 (IL-17)--producing cells and deficiency of regulatory T (Treg) cells. The aim of this study was to investigate the effect and mechanisms of sirolimus, an inhibitor of the mammalian target of rapamycin, on immune responses in a murine model of Crohn's disease. Murine colitis was induced by intrarectal administration of 2,4,6-trinitrobenzene sulphonic acid at day 0. Mice were then treated intraperitoneally with sirolimus daily for 3 days. The gross and histological appearances of the colon and the numbers, phenotype and cytokine production of lymphocytes were compared with these characteristics in a control group. Sirolimus treatment significantly decreased all macroscopic, microscopic and histopathological parameters of colitis that were analysed. The therapeutic effects of sirolimus were associated with a down-regulation of pro-inflammatory cytokines tumour necrosis factor-α, IL-6 and IL-17A. Intriguingly, sirolimus administration resulted in a prominent up-regulation of the regulatory cytokine transforming growth factor-β. Supporting the hypothesis that sirolimus directly affects the functional activity of CD4+ CD25+ Treg cells, we observed a remarkable enhancement of FoxP3 expression in colon tissues and isolated CD4+ T cells of sirolimus-treated mice. Simultaneously, sirolimus treatment led to a significant reduction in the number of CD4+ IL-17A+ T cells in the mesenteric lymph node cells as well as IL-17A production in mesenteric lymph node cells. Therefore, sirolimus may offer a promising new therapeutic strategy for the treatment of inflammatory bowel disease.

Case-control study and mRNA expression analysis reveal the MyD88 gene is associated with digestive disorders in rabbit

As in humans, significant associations between Toll-like receptor 4 (TLR4) and digestive disorders have been identified in rabbit and dog. However, as an essential adaptor downstream of TLR4, the genetic variation of myeloid differentiating factor 88 (MyD88) and its association with digestive disorders have remained unknown. In this study, we detected 10 single nucleotide polymorphisms (SNPs) in the entire genomic region of rabbit MyD88. The genetic variation in susceptibility to digestive disorders for the only coding SNP (synonymous c.699T>C) was studied in Yaan (183 cases and 142 controls) and Chengdu populations (145 cases and 140 controls). A case-control association study revealed that individuals with the C allele had significant protection against digestive disorders in the Yaan population (OR = 0.71; 95% CI, 0.51-0.99; P < 0.05), the Chengdu population (OR = 0.55; 95% CI, 0.39-0.78; P < 0.01) and for joint analysis (OR = 0.62; 95% CI, 0.49-0.79; P < 0.01). We also experimentally induced digestive disorders by feeding a fiber-deficient diet and found that increased susceptibility was significantly associated with higher MyD88 mRNA expression (P < 0.05). The lowest MyD88 mRNA expression was observed in individuals carrying the protective CC genotype. These results suggest that MyD88 is one of the most plausible candidate genes in relation to digestive disorders in rabbit. Further studies are required to explore the biological implications of MyD88 in the pathogenesis of digestive disorders.

Eosinophil associated genes in the inflammatory bowel disease 4 region: Correlation to inflammatory bowel disease revealed

AIM: To study the association between inflammatory bowel disease (IBD) and genetic variations in eosinophil protein X (EPX) and eosinophil cationic protein (ECP).

METHODS: DNA was extracted from ethylene diamine tetraacetic acid blood of 587 patients with Crohn’s disease (CD), 592 with ulcerative colitis (UC) and 300 healthy subjects. The EPX405 (G > C, rs2013109), ECP434 (G > C, rs2073342) and ECP562 (G > C, rs2233860) gene polymorphisms were analysed, by the 5’-nuclease allelic discrimination assay. For determination of intracellular content of EPX and ECP in granulocytes, 39 blood samples was collected and extracted with a buffer containing cetyltrimethylammonium bromide. The intracellular content of EPX was analysed using an enzyme-linked immunosorbent assay. The intracellular content of ECP was analysed with the UniCAP^® system as described by the manufacturer. Statistical tests for calculations of results were χ² test, Fisher’s exact test, ANOVA, Student-Newman-Keuls test, and Kaplan-Meier survival curve with Log-rank test for trend, the probability values of P < 0.05 were considered statistically significant.

RESULTS: The genotype frequency for males with UC and with an age of disease onset of ≥ 45 years (n = 57) was for ECP434 and ECP562, GG = 37%, GC = 60%, CC = 4% and GG = 51%, GC = 49%, CC = 0% respectively. This was significantly different from the healthy subject’s genotype frequencies of ECP434 (GG = 57%, GC = 38%, CC = 5%; P = 0.010) and ECP562 (GG = 68%, GC = 29%,CC = 3%; P = 0.009). The genotype frequencies for females, with an age of disease onset of ≥ 45 years with CD (n = 62), was for the ECP434 and ECP562 genotypes GG = 37%, GC = 52%, CC = 11% and GG = 48%, GC = 47% and CC = 5% respectively. This was also statistically different from healthy controls for both ECP434 (P = 0.010) and ECP562 (P = 0.013). The intracellular protein concentration of EPX and ECP was calculated in μg/10⁶ eosinophils and then correlated to the EPX 405 genotypes. The protein content of EPX was highest in the patients with the CC genotype of EPX405 (GG = 4.65, GC = 5.93, and CC = 6.57) and for ECP in the patients with the GG genotype of EPX405 (GG = 2.70, GC = 2.47 and CC = 1.90). ANOVA test demonstrated a difference in intracellular protein content for EPX (P = 0.009) and ECP (P = 0.022). The age of disease onset was linked to haplotypes of the EPX405, ECP434 and ECP562 genotypes. Kaplan Maier curve showed a difference between haplotype distributions for the females with CD (P = 0.003). The highest age of disease onset was seen in females with the EPX405CC, ECP434GC, ECP562CC haplotype (34 years) and the lowest in females with the EPX405GC, ECP434GC, ECP562GG haplotype (21 years). For males with UC there was also a difference between the highest and lowest age of the disease onset (EPX405CC, ECP434CC, ECP562CC, mean 24 years vs EPX405GC, ECP434GC, ECP562GG, mean 34 years, P = 0.0009). The relative risk for UC patients with ECP434 or ECP562-GC/CC genotypes to develop dysplasia/cancer was 2.5 (95%CI: 1.2-5.4, P = 0.01) and 2.5 (95%CI: 1.1-5.4, P = 0.02) respectively, compared to patients carrying the GG-genotypes.

CONCLUSION: Polymorphisms of EPX and ECP are associated to IBD in an age and gender dependent manner, suggesting an essential role of eosinophils in the pathophysiology of IBD.

Genetics in diagnosing and managing inflammatory bowel disease

We believe the future clinical application of genomic information in IBD will lie in the use of a combination of “gene-chips” designed specifically for variation relevant to IBD and ultimately in the cataloging of an individual’s entire collection of genomic variation through whole-genome sequencing. In the short term, the expansion of pharmacogenomic tests and biomarker assessments are likely to have the most significant influence on prescribed IBD treatment therapies and disease management. Moreover, these pharmacogenomic and biomarker data are likely to benefit greatly from the ongoing genomic analyses, as they can begin to put these data in the proper genetic context as they relate to monitoring and assessing these effects across different ethnic and racial populations. Although mentioned only briefly in this review, a clearer understanding of environmental triggers of IBD will be of utmost importance to furthering our understanding of the genetic factors and the complex interactions that are likely to exist between genes and environment. The successful identification of genetic factors influencing IBD risk has been accelerating over the last few years and is likely to continue. Currently, these genetic factors provide no direct bearing on clinical treatments or therapies. Instead, these findings aid in our understanding of disease pathogenesis and indirectly to potential for development of novel therapeutics. In the near term, they may be able to provide some additional utility in distinguishing CD cases from UC cases. Future use of genomic information and its role in diagnosing and managing IBD patients is promising but not yet mature. The search for the so-called missing heritability in IBD will undoubtedly continue to uncover novel genes, biological pathways, and the likely interplay between genetic variation and environmental factors. The creation of a customized gene-chip (allowing for the creation of a patient-specific cataloging of IBD relevant genetic information), for use in clinical practice, is an almost certainty. Although this information will likely provide significant aid to diagnostics and treatment, it is doubtful that it could ever fully stand alone. It must be accompanied by thorough clinical evaluation and data, a more complete characterization of a patient’s potential environmental triggers, and integration with other known pharmacogenomic and molecular biomarker information.

Serpin B1 protects colonic epithelial cell via blockage of neutrophil elastase activity and its expression is enhanced in patients with ulcerative colitis

Serpin B1 is a monocyte neutrophil elastase (NE) inhibitor and is one of the most efficient inhibitors of NE. In the present study, we investigated the role of serpin B1 in the pathogenesis of ulcerative colitis by using clinical samples and an experimental model. The colonic expression of serpin B1 was determined by real-time polymerase chain reaction (PCR), Western blot analysis, and immunohistological studies in both normal and inflamed mucosa from patients with ulcerative colitis. Serpin B1 mRNA expression was determined by real-time PCR in the mouse dextran sodium sulfate (DSS)-induced colitis model. Young adult mouse colonic epithelial (YAMC) cells were used to determine the role of serpin B1. Serpin B1 gene transfected YAMC cells were treated with H(2)O(2) to measure cell viability. The expression of NE was determined in YAMC cells treated with H(2)O(2). NE-silenced YAMC cells were also treated with H(2)O(2) and then measured for viability. Upregulated expression of serpin B1 in colonic mucosa was confirmed from patients with active ulcerative colitis. Immunohistochemical studies showed that serpin B1 expression was localized not only in inflammatory infiltration cells but also in epithelial cells. Serpin B1 mRNA expression was also increased in colonic mucosa of mouse DSS-induced colitis. Serpin B1-transfected YAMC cells were resistant against the treatment of H(2)O(2). H(2)O(2) treatment significantly induced NE in YAMC cells, and NE-silenced YAMC cells were also resistant against the treatment of H(2)O(2). These results suggest that serpin B1 may be a novel marker of active ulcerative colitis and may play an important role in the pathogenesis of inflammatory bowel disease.

Carbohydrate Elimination or Adaptation Diet for Symptoms of Intestinal Discomfort in IBD: Rationales for "Gibsons' Conundrum"

Therapeutic use of carbohydrates in inflammatory bowel diseases (IBDs) is discussed from two theoretical, apparent diametrically opposite perspectives: regular ingestion of prebiotics or withdrawal of virtually all carbohydrate components. Pathogenesis of IBD is discussed connecting microbial flora, host immunity, and genetic interactions. The best studied genetic example, NOD2 in Crohn's disease, is highlighted as a model which encompasses these interactions and has been shown to depend on butyrate for normal function. The role of these opposing concepts in management of irritable bowel syndrome (IBS) is contrasted with what is known in IBD. The conclusion reached is that, while both approaches may alleviate symptoms in both IBS and IBD, there is insufficient data yet to determine whether both approaches lead to equivalent bacterial effects in mollifying the immune system. This is particularly relevant in IBD. As such, caution is urged to use long-term carbohydrate withdrawal in IBD in remission to control IBS-like symptoms.

Down-regulation of single immunoglobulin interleukin-1R-related molecule (SIGIRR)/TIR8 expression in intestinal epithelial cells during inflammation

Single immunoglobulin (Ig) interleukin-1R-related molecule (SIGIRR) is an Ig-like membrane protein critical for negative regulation of Toll-like receptor (TLR)-4-mediated signalling. We investigated SIGIRR expression and its regulation mechanism in intestinal epithelial cells (IECs) during inflammation. Endoscopic biopsy specimens were obtained from active and inactive colonic mucosa of ulcerative colitis (UC) patients, then SIGIRR expression was examined using real-time polymerase chain reaction (PCR) and immunohistochemistry (IH). Mice experimental colitis models were established by administrations of sulphonic acid (TNBS) and dextran sodium sulphate (DSS), and epithelial expression of SIGIRR was examined using real-time PCR, IH and flow cytometry. The effects of lipopolysaccharide (LPS) and tumour necrosis factor (TNF)-α on SIGIRR expression were evaluated in vitro using cultured IECs. To elucidate SIGIRR expression regulation in IECs, binding ability of the transcription factor SP1 at the responsive element of the SIGIRR promoter was examined using gel-shift and chromatin immunoprecipitation (ChIP) assays. In human colonic samples, SIGIRR was expressed mainly in IECs at levels significantly higher in inactive compared to active mucosa. In the mice, SIGIRR colonic expression decreased rapidly after colitis development and returned gradually to basal levels. Experimental colitis-mediated down-regulation of SIGIRR in IECs was also confirmed by IH and flow cytometry results. Further, inflammatory conditions induced by TLR ligands and TNF-α caused significant down-regulation of SIGIRR expression in IECs, which was dependent upon decreased SP1 binding at the responsive element of the SIGIRR promoter. We found that SIGIRR is expressed in IECs and serves as a negative regulator to maintain gut innate immunity, which is down-regulated during inflammation by inhibition of an SP1-mediated pathway.

Importance of disrupted intestinal barrier in inflammatory bowel diseases

The current paradigm of inflammatory bowel diseases (IBD), both Crohn's disease (CD) and ulcerative colitis (UC), involves the interaction between environmental factors in the intestinal lumen and inappropriate host immune responses in genetically predisposed individuals. The intestinal mucosal barrier has evolved to maintain a delicate balance between absorbing essential nutrients while preventing the entry and responding to harmful contents. In IBD, disruptions of essential elements of the intestinal barrier lead to permeability defects. These barrier defects exacerbate the underlying immune system, subsequently resulting in tissue damage. The epithelial phenotype in active IBD is very similar in CD and UC. It is characterized by increased secretion of chloride and water, leading to diarrhea, increased permeability via both the transcellular and paracellular routes, and increased apoptosis of epithelial cells. The main cytokine that seems to drive these changes is tumor necrosis factor alpha in CD, whereas interleukin (IL)-13 may be more important in UC. Therapeutic restoration of the mucosal barrier would provide protection and prevent antigenic overload due to intestinal "leakiness." Here we give an overview of the key players of the intestinal mucosal barrier and review the current literature from studies in humans and human systems on mechanisms underlying mucosal barrier dysfunction in IBD.

Decreased production of interleukin-10 and transforming growth factor-β in Toll-like receptor-activated intestinal B cells in SAMP1/Yit mice

A unique subset of B cells expressing interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) plays an essential role in preventing inflammation and autoimmunity. We investigated the presence of this cell subset in intestines and its role in the pathogenesis of ileitis using SAMP1/Yit and age-matched control AKR/J mice. Mononuclear cells were isolated from mesenteric lymph nodes (MLNs) and the expressions of B220, CD1d, CD5, Toll-like receptor 4 (TLR4) and TLR9 in isolated cells were analysed. Purified B cells were stimulated with lipopolysaccharide (LPS) or CpG-DNA, then IL-10 and TGF-β(1) expressions were examined by enzyme immunoassay and flow cytometry. Production of IL-1β by TLR-mediated macrophages co-cultured with or without purified MLN B cells from SAMP1/Yit and AKR/J mice was evaluated. In addition, interferon-γ (IFN-γ) production in intestinal T cells co-cultured with MLN B cells were also assessed in SAMP1/Yit and AKR/J strains. The production levels of IL-10 and TGF-β(1) stimulated by LPS and CpG-DNA were significantly lower in B cells separated from MLNs from the SAMP1/Yit strain. B cells expressing IL-10 and TGF-β(1) were mainly located in a population characterized by the cell surface marker CD1d(+) . Interleukin-1β production by TLR-activated macrophages co-cultured with MLN B cells from SAMP1/Yit mice was significantly higher than that of those from AKR/J mice. Interestingly, IFN-γ production by T cells was noted only when they were co-cultured with SAMP1/Yit but not the AKR/J B cells. These results are the first to show that disorders of regulatory B-cell function under innate immune activation may cause disease pathogenesis in a murine model of Crohn's disease.

Inflammatory bowel disease in the dog: Differences and similarities with humans

Inflammatory bowel diseases (IBD) represent important chronic conditions affecting the gastrointestinal tract in man. However, similar disorders are found in several animal species and the IBD affecting dogs are particularly important. These are encompassed by an umbrella of probably several different entities with common symptoms, some of which seem to share striking similarities with human conditions. This review will focus on the actual knowledge of IBD in dogs, and attempt to identify differences and similarities with human IBD conditions.

The role of infection in the aetiology of inflammatory bowel disease

We have greatly increased our understanding of the genetics of inflammatory bowel disease (IBD) in the last decade; however, migrant studies highlight the importance of environment in disease risk. The possibility that IBD is an infection has been debated since the first description of Crohn's disease. Mycobacterium avium paratuberculosis was the first organism to be suggested as an IBD pathogen, and it has been argued that it fulfils Koch's postulates and could be designated the cause of Crohn's disease. Other organisms have been postulated as possible IBD pathogens, including various Helicobacter species, one of which has been identified in primate colitis;others are widely used in animal models of IBD. Adherent invasive Escherichia coli appear specific to ileal Crohn's disease and have been shown to induce the release of TNF-alpha, a key cytokine in IBD inflammation. The aim of this article is to give a concise overview of the infections postulated as being relevant to the onset of IBD. We will also briefly cover the immunology underpinning IBD, in addition to reviewing current knowledge regarding other microorganisms that are associated with modifying the risk of developing IBD. It may be that infectious organisms have an orchestrator role in the development of dysbiosis and subsequently IBD.