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

Genetic and Epigenetic Etiology of Inflammatory Bowel Disease: An Update

Inflammatory bowel disease (IBD) is a chronic disease with periods of exacerbation and remission of the disease. The etiology of IBD is not fully understood. Many studies point to the presence of genetic, immunological, environmental, and microbiological factors and the interactions between them in the occurrence of IBD. The review looks at genetic factors in the context of both IBD predisposition and pharmacogenetics.

Emerging Nanotechnologies and Microbiome Engineering for the Treatment of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is characterized by the chronic inflammation of the gastrointestinal tract and impacts almost 7 million people across the globe. Current therapeutics are effective in treating the symptoms, but they often do not address the root cause or selectively target areas of inflammation. Notably, self-assembled nanoparticles show great promise as drug delivery systems for the treatment of IBD. Nanoparticles can be designed to survive the harsh gastric conditions and reach inflamed areas of the gastrointestinal tract. Oral drug delivery with nanoparticles can localize drugs to the impacted inflamed region using active and/or passive targeting and promote a high rate of drug dispersion in local tissues, thus reducing potential off-target toxicities. Since a dysregulated gut microbiome is implicated in the development and progression of IBD, it is also important to develop nanoparticles and biomaterials that can restore symbiotic microbes while reducing the proliferation of harmful microbes. In this review, we highlight recent advances in self-assembled nanosystems designed for addressing inflammation and dysregulated gut microbiomes as potential treatments for IBD. Nanoparticles have a promising future in improving the delivery of current therapeutics, increasing patient compliance by providing an oral method of medication, and reducing side effects. However, remaining challenges include scale-up synthesis of nanoparticles, potential side effects, and financial obstacles of clinical trials. It would be in the patients' best interest to continue research on nanoparticles in the pursuit of more effective therapeutics for the treatment of IBD.

Genes vs environment in inflammatory bowel disease: an update

INTRODUCTION

Inflammatory bowel diseases (IBDs) are known to be caused by a combination of genetic and environmental factors that vary in their influence on the development of the disease. Environmental exposures seem to influence IBD susceptibility, whereas genetic background is thought to modulate the impact of the environment on disease course and phenotype.

AREAS COVERED

A broad review of the involvement of genes and the environment in IBD pathogenesis was performed, and information regarding the main genetic and environmental factors - categorized into lifestyle factors, drugs, diet, and microbes - was updated. Monogenic very early onset IBD (VEO-IBD) was also discussed.

EXPERT OPINION

In the upcoming years, better understanding of gene-environment interactions will contribute to the possibility of a better prediction of disease course, response to therapy, and therapy-related adverse events with the final goal of personalized and more efficient patient management.

UK IBD Twin Registry: Concordance and Environmental Risk Factors of Twins with IBD

BACKGROUND AND AIMS

Twin studies have long been used to infer heritability. Within the 'omics era, twin cohorts have even greater research potential. This study describes the formation of the UK IBD Twin Registry and analysis of concordance and environmental factors.

METHOD

Twin pairs with IBD were recruited by advertising via IBD charities and social media, re-tracing a dormant IBD database and clinician referral. Details of zygosity, concordance, disease history and environmental factors were assessed. Pair concordance was calculated, and environmental factors were analysed with logistic regression models adjusted for zygosity and concordance.

RESULTS

Ninety-one twin pairs were included in the analysis; forty-two with CD and forty-nine with UC. More MZ twin pairs with CD were concordant compared with DZ pairs, thus inferring heritability (Chi-sq. 15.6. P < 0.001). In UC, MZ concordance was also numerically greater. Cigarette smoking was predictive of CD (OR 2.66, 95% CI 1.16 to 6.07 P = 0.02); there may be an independent association with cannabis smoking (OR 2.59 95% CI 0.89 to 7.55 P = 0.08). Breastfeeding was protective against UC (OR 0.48, 95% CI 0.25-0.93, P = 0.03), but not CD. Self-reports of less occurrences of gastroenteritis than peers were protective against future UC onset (OR 0.33 95% CI 0.15 to 0.74, P = 0.01). Method of delivery, parental attitudes towards hygiene and recall of diet did not impact future IBD concordance.

CONCLUSIONS

This study supports the heritability of IBD. Twin study analysis was able to elucidate environmental factors associated with IBD.

State-of-the-art surgery for ulcerative colitis

Ulcerative colitis (UC) is an autoimmune-mediated colitis which can present in varying degrees of severity and increases the individual’s risk of developing colon cancer. While first-line treatment for UC is medical management, surgical treatment may be necessary in up to 25–30% of patients. With an increasing armamentarium of biologic therapies, patients are presenting for surgery much later in their course, and careful understanding of the complex interplay of the disease, its management, and the patient’s overall health is necessary when considering he appropriate way in which to address their disease surgically. Surgery is generally a total proctocolectomy either with pelvic pouch reconstruction or permanent ileostomy; however, this may need to be spread across multiple procedures given the complexity of the surgery weighed against the overall state of the patient’s health. Minimally invasive surgery, employing either laparoscopic, robotic, or transanal laparoscopic approaches, is currently the preferred approach in the elective setting. There is also some emerging evidence that appendectomy may delay the progression of UC in some individuals. Those who treat these patients surgically must also be familiar with the numerous potential pitfalls of surgical intervention and have plans in place for managing problems such as pouchitis, cuffitis, and anastomotic complications.

Intestinal flora differences between patients with ulcerative colitis of different ethnic groups in China

To determine the differences in intestinal flora between Uygur and Han patients with ulcerative colitis (UC).Microbial diversity and structural composition of fecal bacteria from patients with UC and their matched healthy spouses or first-degree relatives were analyzed using high-throughput sequencing technology.The fecal microbial diversity and abundance index of Uygur patients with UC (UUC) were significantly lower compared with the Uygur normal control group, while there was no significant difference between the Han UC patients (HUC) and the Han normal control group (HN). Compared with their respective control groups, Uygur UC patients and Han UC patients had a different main composition of human intestinal flora (P < .05). The abundance of Burkholderia, Caballeronia, Paraburkholderia in the UUC group were higher compared with the HUC group, while Faecalibacterium, Bifidobacterium, and Blautia in the HUC group were higher than those in the UUC group (P < .05). Veillonella in the UUC group was higher than that in the Uygur normal control group group, while Subdoligranulum and Ruminococcaceae_UCG-002 were significantly lower (P < .05). Prevotella_9 in the HUC group was significantly higher than that in HN group, while Blautia, Anaerostipes, and [Eubacterium]_hallii_group were significantly lower. Moreover, the top 6 species in order of importance were Christensenellaceae_R_7_group, Ruminococcae_ucg_005, Ruminococcae_ucg_010, Ruminococcae_ucg_013, Haemophilus, and Ezakiella.The difference in intestinal microflora structure may be one of the reasons for the clinical heterogeneity between Uygur and Han patients with UC. Christensenellaceae_R_7_group, Ruminococcae_ucg_005, Ruminococcae_ucg_010, Ruminococcae_ucg_013, Haemophilus, and Ezakiella could be used as potential biomarkers for predicting UC.

Concordance regarding disease type and phenotypic characteristics among patients with familial inflammatory bowel disease

BACKGROUND AND AIMS

The phenotypic concordance among familial cases of inflammatory bowel disease (IBD) has been rarely reported. Thus, the present study aimed to evaluate the concordance regarding disease type and phenotypic features in a large cohort of Korean patients with IBD.

METHODS

A total of 6647 patients with IBD who visited the Asan Medical Center between June 1989 and September 2016 were enrolled in the study. When at least two familial cases existed in our cohort, they were included in the concordance analysis (κ index). The concordance between younger and older members for IBD type [Crohn's disease (CD) and ulcerative colitis (UC)] and phenotypic characteristics such as disease extent and location, disease behavior, the use of medication, and need for surgery were evaluated.

RESULTS

A positive family history of IBD was noted in 216 patients with CD (7.0%) and in 238 patients with UC (6.7%). Of all patients, 167 consanguineous pairs in 146 families were identified. The crude concordance rate for IBD type was 82.6% with a κ index of 0.656 [95% confidence interval (CI): 0.545-0.768, good concordance]. There was mild concordance for disease location in CD (κ = 0.256; 95% CI: 0.007-0.505) and for the use of antitumor necrosis factor agents in UC (κ = 0.354; 95% CI: -0.049-0.757). The concordance for IBD type and several phenotypes in first-degree relative pairs was better than that in the entire pairs.

CONCLUSIONS

Disease type and phenotypic characteristics of patients with familial IBD may be anticipated.

Personalized Nutrition for Inflammatory Bowel Disease

A person’s diet may impact inflammatory bowel disease (IBD) risk. IBD is an inflammatory condition. We explore how certain foods may trigger, or indeed attenuate, inflammation in some IBD patients, but not others. Greater knowledge is needed underpinning personalized nutrition within effective medical management.

Familial and ethnic risk in inflammatory bowel disease

Familial aggregation in inflammatory bowel disease (IBD) has been established for several decades, reflecting shared genetic and environmental susceptibility. A positive family history remains the strongest recognizable risk factor for the development of IBD and is reported in around 8-12% of IBD patients. Crohn’s disease shows a more frequent familial pattern than ulcerative colitis. The risk of developing IBD in first-degree relatives of an affected proband is increased 4- to 8-fold. The risk for twins and children born from couples who both have IBD is also substantially higher; a cumulative effect of the number of family members affected has been described, with the highest incidence being described for families with three or more affected members. Herein, we review the available evidence regarding familial IBD, and briefly discuss the variation of IBD across different races and ethnicities, hoping to provide a useful update and a practical guide that can serve clinicians as a guide for counseling.

Lessons learned from twins in autoimmune and chronic inflammatory diseases

Autoimmunity and chronic inflammation recognize numerous shared factors and, as a result, the resulting diseases frequently coexist in the same patients or respond to the same treatments. Among the convenient truths of autoimmune and chronic inflammatory diseases, there is now agreement that these are complex conditions in which the individual genetic predisposition provides a rate of heritability. The concordance rates in monozygotic and dizygotic twins allows to estimate the weight of the environment in determining disease susceptibility, despite recent data supporting that only a minority of immune markers depend on hereditary factors. Concordance rates in monozygotic and dizygotic twins should be evaluated over an observation period to minimize the risk of false negatives and this is well represented by type I diabetes mellitus. Further, concordance rates in monozygotic twins should be compared to those in dizygotic twins, which share 50% of their genes, as in regular siblings, but also young-age environmental factors. Twin studies have been extensively performed in several autoimmune conditions and cumulatively suggest that some diseases, i.e. celiac disease and psoriasis, are highly genetically determined, while rheumatoid arthritis or systemic sclerosis have a limited role for genetics. These observations are necessary to interpret data gathered by genome-wide association studies of polymorphisms and DNA methylation in MZ twins. New high-throughput technological platforms are awaited to provide new insights into the mechanisms of disease discordance in twins beyond strong associations such as those with HLA alleles.

Danish cohort of monozygotic inflammatory bowel disease twins: Clinical characteristics and inflammatory activity

AIM: To describe the establishment of a Danish inflammatory bowel diseases (IBD) twin cohort with focus on concordance of treatment and inflammatory markers.

METHODS: We identified MZ twins, likely to be discordant or concordant for IBD, by merging information from the Danish Twin Register and the National Patient Register. The twins were asked to provide biological samples, questionnaires, and data access to patient files and public registries. Biological samples were collected via a mobile laboratory, which allowed for immediate centrifugation, fractionation, and storage of samples. The mean time from collection of samples to storage in the -80 °C mobile freezer was less than one hour. The diagnoses where validated using the Copenhagen diagnostic criteria.

RESULTS: We identified 159 MZ IBD twin pairs, in a total of 62 (39%) pairs both twins agreed to participate. Of the supposed 62 IBD pairs, the IBD diagnosis could be confirmed in 54 pairs. The cohort included 10 concordant pairs, whereof some were discordant for either treatment or surgery. The 10 concordant pairs, where both pairs suffered from IBD, included eight CD/CD pairs, one UC/UC pair and one UC/IBDU pair. The discordant pairs comprised 31 UC, 5 IBDU (IBD unclassified), and 8 CD discordant pairs. In the co-twins not affected by IBD, calprotectin was above 100 μg/g in 2 participants, and above 50 μg/g in a further 5 participants.

CONCLUSION: The presented IBD twin cohorts are an excellent resource for bioinformatics studies with proper adjustment for disease-associated exposures including medication and inflammatory activity in the co-twins.

Influence of urban/rural and coastal/inland environment on the prevalence, phenotype, and clinical course of inflammatory bowel disease patients from northwest of Spain: a cross-sectional study

BACKGROUND

Data on the influence of rural/urban and coastal/inland environment on inflammatory bowel disease (IBD) are either conflicting or lacking. Our aim was to analyze whether the environment has any influence on the prevalence, phenotype, and course of IBD.

MATERIALS AND METHODS

We carried out a multicenter retrospective study in 1194 IBD patients from Galicia, Spain. Urban areas were defined as those with over 25,000 inhabitants. Sex, age, family history, smoking, Montreal classification, extraintestinal manifestations, steroid dependence/refractoriness, and treatment were assessed. We used the Student's t-test/Mann-Whitney U tests to compare continuous variables and χ to compare categorical variables. Logistic regression was also used.

RESULTS

Living in urban municipalities was a risk factor for Crohn's disease [relative risk (RR) 1.47; 95% confidence interval (CI) 1.25-1.73; P<0.001]; living in coastal municipalities was a protective factor for ulcerative colitis (RR 0.71; 95% CI 0.60-0.85; P<0.001). Crohn's disease patients living on the coast had more frequent ileocolonic disease and needed immunosuppressives more frequently than inland patients (RR for inland 0.65; 95% CI 0.47-0.90; P=0.008). Urban Crohn's disease patients needed immunosuppressives more frequently than rural patients (RR 1.41; 95% CI 1.04-1.92; P=0.027). Urban ulcerative colitis patients had left-sided colitis less frequently. Coastal ulcerative colitis patients more frequently had extensive colitis.

CONCLUSION

Crohn's disease was found more frequently in urban and coastal areas and ulcerative colitis in inland municipalities. Place of residence may also influence phenotype and clinical course as patients living on the coast have more frequent ileocolonic Crohn's disease phenotype, extensive ulcerative colitis, and greater need for immunosuppressive therapy.

Heritability in inflammatory bowel disease: from the first twin study to genome-wide association studies

Since Tysk et al's pioneering analysis of the Swedish twin registry, twin and family studies continue to support a strong genetic basis of the inflammatory bowel diseases. The coefficient of heritability for siblings of inflammatory bowel disease probands is 25 to 42 for Crohn's disease and 4 to 15 for ulcerative colitis. Heritability estimates for Crohn's disease and ulcerative colitis from pooled twin studies are 0.75 and 0.67, respectively. However, this is at odds with the much lower heritability estimates from Genome-Wide Association Studies (GWAS). This "missing heritability" is likely due to shortfalls in both family studies and GWAS. The coefficient of heritability fails to account for familial shared environment. Heritability calculations from twin data are based on Falconer's method, with premises that are increasingly understood to be flawed. GWAS based heritability estimates may underestimate heritability due to incomplete linkage disequilibrium, and because some single nucleotide polypeptides (SNPs) do not reach a level of significance to allow detection. SNPs missed by GWAS include common SNPs with low penetrance and rare SNPs with high penetrance. All methods of heritability estimation regard genetic and environmental variance as separate entities, although it is now understood that there is a complex multidirectional interplay between genetic are environmental factors mediated by the microbiota, the epigenome, and the innate and acquired immune systems. Due to the limitations of heritability estimates, it is unlikely that a true value for heritability will be reached. Further work aimed at quantifying the variance explained across GWAS, epigenome-wide, and microbiota-wide association studies will help to define factors leading to inflammatory bowel disease.

Phenotypic concordance in familial inflammatory bowel disease (IBD). Results of a nationwide IBD Spanish database

BACKGROUND & AIMS

Disease outcome has been found to be poorer in familial inflammatory bowel disease (IBD) than in sporadic forms, but assessment of phenotypic concordance in familial IBD provided controversial results. We assessed the concordance for disease type and phenotypic features in IBD families.

METHODS

Patients with familial IBD were identified from the IBD Spanish database ENEIDA. Families in whom at least two members were in the database were selected for concordance analysis (κ index). Concordance for type of IBD [Crohn's disease (CD) vs. ulcerative colitis (UC)], as well as for disease extent, localization and behaviour, perianal disease, extraintestinal manifestations, and indicators of severe disease (i.e., need for immunosuppressors, biological agents, and surgery) for those pairs concordant for IBD type, were analyzed.

RESULTS

798 out of 11,905 IBD patients (7%) in ENEIDA had familial history of IBD. Complete data of 107 families (231 patients and 144 consanguineous pairs) were available for concordance analyses. The youngest members of the pairs were diagnosed with IBD at a significantly younger age (p<0.001) than the oldest ones. Seventy-six percent of pairs matched up for the IBD type (κ=0.58; 95%CI: 0.42-0.73, moderate concordance). There was no relevant concordance for any of the phenotypic items assessed in both diseases.

CONCLUSIONS

Familial IBD is associated with diagnostic anticipation in younger individuals. Familial history does not allow predicting any phenotypic feature other than IBD type.