Genetic association of nonsynonymous variants of the IL23R with familial and sporadic inflammatory bowel disease in women

Sex-related differences in profiles and clinical outcomes of Inflammatory bowel disease: a systematic review and meta-analysis

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic and idiopathic condition that includes both Crohn's disease (CD) and ulcerative colitis (UC). The impact of sex on the disease course and the clinical outcomes not fully understood. Our systematic review and meta-analysis aims to explore the differences in the clinical outcomes in IBD.

METHOD

A systematic review and meta-analysis was done by searching in the PubMed /MEDLINE, Embase, and Scopus databases. We used the Random-Effects model to estimate risk ratios (RR) for binary outcomes and mean difference and hedges' g for continuous outcomes.

RESULT

A total of 44 unique studies were included. Our analysis revealed distinct sex differences in various outcomes of IBD. Anxiety was more prevalent in females (RR: 0.73; 95% CI [0.64, 0.82]) and females in the CD subgroup (RR: 0.76; 95% CI [0.62, 0.93]; p = 0.01. While depression was diagnosed more frequently in females (RR: 0.80; 95% CI [0.66, 0.97] in the total population of the study, subgroup analysis showed no sex difference. Additionally, quality of life scores were worse in females in the total population (Hedges' g: 0.24; 95% CI [0.05, 0.42]) with no significant difference in subgroup analyses. A significantly higher mortality risk was estimated in males (RR: 1.26; 95% CI [1.07, 1.48]) and in subgroup analysis for males with UC (RR: 1.48; 95% CI [1.19, 1.84]; p = 0.00) with no significant difference in CD. Regarding disease location, male patients were less likely to present with proctitis (RR: 0.67; 95% CI [0.50, 0.91]) when compared to females. Males had more frequent indications for surgery (RR: 1.10; 95% CI [1.01, 1.20]), however, no significant difference was found in subgroup analyses for CD or UC. Also, males were older at the time of admission (MD: 1.39 years; 95% CI [0.10, 2.68]). No significant sex differences were found in terms of hospitalization rates or disease behavior.

CONCLUSION

In conclusion, our meta-analysis shows that males face higher risks of early mortality and require more IBD surgeries, whereas females experience greater levels of anxiety and depression. These findings emphasize the need to consider sex disparities in IBD management.

Sex-Related Differences in the Phenotype and Course of Inflammatory Bowel Disease: SEXEII Study of ENEIDA

BACKGROUND & AIMS

The impact of patient sex on the presentation of inflammatory bowel disease (IBD) has been poorly evaluated. Our aims were to assess potential disparities in IBD phenotype and progression between sexes.

METHODS

We performed an observational multicenter study that included patients with Crohn's disease (CD) or ulcerative colitis from the Spanish Estudio Nacional en Enfermedad Inflamatoria intestinal sobre Determinantes genéticos y Ambientales registry. Data extraction was conducted in July 2021.

RESULTS

A total of 51,595 patients with IBD were included, 52% were males and 25,947 had CD. The median follow-up period after diagnosis was 9 years in males and 10 years in females. In CD, female sex was an independent risk factor for medium disease onset (age, 17-40 y) (relative risk ratio, 1.45; 95% CI, 1.31-1.62), later disease onset (age, >40 y) (relative risk ratio, 1.55; 95% CI, 1.38-1.73), exclusive colonic involvement (odds ratio, 1.24; 95% CI, 1.14-1.34), inflammatory behavior (odds ratio, 1.14; 95% CI, 1.07-1.21), and extraintestinal manifestations (odds ratio, 1.48; 95% CI, 1.38-1.59). However, female sex was a protective factor for upper gastrointestinal involvement (odds ratio, 0.84; 95% CI, 0.79-0.90), penetrating behavior (odds ratio, 0.76; 95% CI, 0.70-0.82), perianal disease (odds ratio, 0.77; 95% CI, 0.71-0.82), and complications (odds ratio, 0.73; 95% CI, 0.66-0.80). In ulcerative colitis, female sex was an independent risk factor for extraintestinal manifestations (odds ratio, 1.48; 95% CI, 1.26-1.61). However, female sex was an independent protective factor for disease onset from age 40 onward (relative risk ratio, 0.76; 95% CI, 0.66-0.87), left-sided colonic involvement (relative risk ratio, 0.72; 95% CI, 0.67-0.78), extensive colonic involvement (relative risk ratio, 0.59; 95% CI, 0.55-0.64), and abdominal surgery (odds ratio, 0.78; 95% CI, 0.69-0.88).

CONCLUSIONS

There is sexual dimorphism in IBD. The patient's sex should be taken into account in the clinical management of the disease.

Sex-Dimorphic Analyses Identify Novel and Sex-Specific Genetic Associations in Inflammatory Bowel Disease

BACKGROUND

Sex is an integral variable often overlooked in complex disease genetics. Differences between sexes have been reported in natural history, disease complications, and age of onset in inflammatory bowel disease (IBD). While association studies have identified >230 IBD loci, there have been a limited number of studies investigating sex differences underlying these genetic associations.

METHODS

We report the first investigation of sex-dimorphic associations via meta-analysis of a sex-stratified association study (34 579 IBD cases, 39 125 controls). In addition, we performed chromosome (chr) X-specific analyses, considering models of X inactivation (XCI) and XCI escape. Demographic and clinical characteristics were also compared between sexes.

RESULTS

We identified significant differences between sexes for disease location and perianal complication in Crohn's disease and disease extent in ulcerative colitis. We observed genome-wide-significant sex-dimorphic associations (P < 5 × 10-8) at loci not previously reported in large-scale IBD genetic studies, including at chr9q22, CARMIL1, and UBASH3A. We identified variants in known IBD loci, including in chr2p15 and within the major histocompatibility complex on chr6, exhibiting sex-specific patterns of association (P < 5 × 10-7 in one sex only). We identified 3 chrX associations with IBD, including a novel Crohn's disease susceptibility locus at Xp22.

CONCLUSIONS

These analyses identified novel IBD loci, in addition to characterizing sex-specific patterns of associations underlying sex-dimorphic associations. By elucidating the role of sex in IBD genetics, our study will help enhance our understanding of the differences between the sexes in IBD biology and underscores a need to move beyond conventional sex-combined analyses to appreciate the genetic architecture of IBD more comprehensively.

Impact of Female Gender in Inflammatory Bowel Diseases: A Narrative Review

Inflammatory bowel diseases show a gender bias, as reported for several other immune-mediated diseases. Female-specific differences influence disease presentation and activity, leading to a different progression between males and females. Women show a genetic predisposition to develop inflammatory bowel disease related to the X chromosome. Female hormone fluctuation influences gastrointestinal symptoms, pain perception, and the state of active disease at the time of conception could negatively affect the pregnancy. Women with inflammatory bowel disease report a worse quality of life, higher psychological distress, and reduced sexual activity than male patients. This narrative review aims to resume the current knowledge of female-related features in clinical manifestations, development, and therapy, as well as sexual and psychological implications related to inflammatory bowel disease. The final attempt is to provide gastroenterologists with a roadmap of female-specific differences, to improve patients' diagnosis, management, and treatment.

Intermittent antibiotic treatment accelerated the development of colitis in IL-10 knockout mice

BACKGROUND AND AIMS

Many epidemiological studies suggest an association between antibiotic exposure and the development of inflammatory bowel disease [IBD]. However, the majority of these studies are observational and still the question remains, "Does the specific antibiotic administration regimen play a role in the development of colitis?" This study aimed to compare the possible effects of continuous and intermittent antibiotic exposure on the development of colitis using a colitis-susceptible IL-10 knockout [IL-10-/-] mouse model.

METHODS

IL-10-/- mice [C57BL/6] were randomly assigned to a non-antibiotic group, continuous antibiotic group and intermittent antibiotic group, and observed for 30 weeks. The antibiotic cocktail was given via the drinking water. The differential response to antibiotics was assessed.

RESULTS

Intermittent antibiotic treatment resulted in severe colitis with early disease onset in IL-10-/- mice. Higher unit colon weight and spleen weight were observed in intermittent antibiotic-treated mice but not in the continuous antibiotic group. Moreover, intermittent antibiotic treatment aggravated epithelial damage and colonic inflammation, mucosal barrier dysfunction and colonic allergic sensitization in IL-10-/- mice, whereas continuous antibiotic treatment ameliorated these symptoms. Male IL-10-/- mice with intermittent antibiotic exposure were more susceptible to colonic inflammation and allergic response than females.

CONCLUSIONS

In summary, intermittent antibiotic exposure accelerated the development of severe colitis more than continuous antibiotic exposure in IL-10-/- male mice. In addition to the colonic damage and impaired barrier function, stimulation of allergic response may play a role in accelerating the development of colitis in genetically susceptible mice.

Sex-based differences in inflammatory bowel diseases: a review

Sex-based differences in inflammatory bowel disease (IBD) pathogenesis, disease course, and response to therapy have been increasingly recognized, however, not fully understood. Experimental and translational models have been leveraged to investigate hypothesized mechanisms for these observed differences, including the potential modifying role of sex hormones and sex-dependent (epi)genetic and gut microbiome changes. The primary objective of this review is to comprehensively describe sex-based differences in IBD including epidemiology, pathogenesis, phenotypic differences, therapeutic response, and outcomes.

Genetic profile of patients with early onset inflammatory bowel disease

Inflammatory Bowel disease (IBD) is a widespread pathological condition with clinical heterogeneity and with different levels of severity. Although IBD usually occurs in young adults, onset in childhood and infancy are described in patients within the 10th and second year of age. By genome-wide association studies and meta-analysis, several genetic loci have been identified associated with an increased risk of developing IBD in Western populations with variants that may alter the normal mucosal immunity in the gastrointestinal tract. The clinical complexity and the heterogeneity of the IBD phenotype probably reflect the presence of genetic heterogeneity where different genes or combinations of them may be involved, together with environmental factors. We hypothesized that patients with early onset IBD could have either more severe genetic variants in genes associated with IBD or multiple variants in different genes. Under the multifactorial diseases is crucial to consider the small contribution of a single variant in all not only to other small variations in the same gene but also in different genes belonging to the same pathway. We performed direct gene sequencing looking for 94 variations in NOD2, ATG16L1, IL23R, IL10R, IL10 and XIAP genes previously shown as correlated with IBD both in multifactorial and in Mendelian models. All variants identified are known in literature as being associated with IBD except for three variants in the genes NOD2, IL10 and IL10RB that even though present in online databases have never been involved in association studies on IBD patients. Moreover, we coupled genetic variants identification with an accurate "in silico" analysis to verify their predictive impact on the protein structure and function. The in-silico prediction of these variants results as benign therefore even if they exhibit a very low frequency in control population being benign, they cannot be considered pathogenic as monogenic disease but fall within the multifactorial range. The variants identified in our study partially reflect the association data described in the literature but there are no significant differences with the onset of disease (VEO vs EO-IBD).

Insights into IL-23 biology: From structure to function

Interleukin (IL-)23 is a central cytokine controlling TH17 development. Overshooting IL-23 signaling contribute to autoimmune diseases. Moreover, GWAS studies have identified several SNPs within the IL-23 receptor, which are associated with autoimmune diseases. IL-23 is a member of the IL-12-type cytokine family and consists of IL-23p19 and p40. Within the IL-12 family, IL-12 and IL-23 share the p40 cytokine subunit and the IL-12Rβ1 as one chain of the receptor complex. For signaling, IL-23 triggers heterodimerization of IL-12Rβ1 and the IL-23R. Subsequently, signal transduction pathways including JAK/STAT, MAPK and PI3K are activated. Most studies have investigated the biological relevance of IL-23 in the development of TH17 cells and autoimmunity, whereas less is known about the molecular context of IL-23 biology. Therefore, we focused on IL-23 receptor complex assembly, signal transduction and functional relevance of IL-23R SNPs in the context of IL-23-inhibitory principles.

IL23R and ATG16L1 variants in Moroccan patients with inflammatory bowel disease

BACKGROUND

Inflammatory bowel diseases (IBD) are chronic diseases of the gastrointestinal tract. Although their pathogenesis is unclear, the combination of genetic predisposition and environmental components are believed to be the main cause of these diseases. Recently, many variants in interleukin 23 receptor (IL23R) and autophagy-related 16-like 1 (ATG16L1) genes have been associated with the disease. Our objective was to assess the frequency of ATG16L1 (T300A) and IL23R (L310P) variants in Moroccan IBD (Crohn's disease and Ulcerative Colitis) patients and to evaluate a possible effect of these variants on disease's phenotype and clinical course.

METHODS

96 Moroccan IBD patients and 114 unrelated volunteers were genotyped for ATG16L1 (T300A) and IL23R (L310P) variants by PCR-restriction fragment length polymorphism.

RESULTS

This is the first report on the prevalence of ATG16L1 (T300A) and IL23R (L310P) variants in a Moroccan group. We found that IL23R (L310P) variant conferred a protective effect for crohn's disease (CD) but not ulcerative colitis (UC) patients. The presence of ATG16L1 (T300A) mutated alleles was associated with CD type but not with disease onset. In addition, the carriage of T300A variant alleles conferred a protective effect in UC.

CONCLUSION

Our results showed that the prevalence of ATG16L1 and IL23R variants was not significantly different between patients and controls. However a possible role of ATG16L1 (T300A) on CD phenotype was suggested.

Maternal imprinting and female predominance in familial Crohn's disease

BACKGROUND AND AIM

Although the genetic risk factors for familial and sporadic inflammatory bowel disease (IBD) seem identical, the relative risk for contracting IBD in the familial setting is larger as that seen in the population at large, suggesting an important role of epi- and/or paragenetic factors in familial IBD. Epidemiological data indicate a female predominance in IBD, but how this relates to familial IBD has not been assessed.

METHODS

Familial IBD patients (N=608) were compared with a cohort of 415 sporadic IBD patients with regards to the patterns of sex and disease type distribution. The imprinting pattern in 87 families in which both a parent and a child had IBD was tested using Galton binominal statistics.

RESULTS

The percentage of females in familial IBD population was significantly higher (61%; female/male ratio 1.5) compared with sporadic IBD (54%; female/male ratio 1.2; p=0.011). The analysis of offspring sex distribution pattern revealed significantly higher female to female transmission compared with female to male transmission rate (36 vs. 18, respectively; p=0.02). A significantly higher number of mother to child transmissions (55 vs. 32 of father to child transmissions) was observed (p=0.018). The female imprinting was specifically related to Crohn's disease (31 vs. 14 mother vs. father to child transmissions, respectively; p=0.016).

CONCLUSION

We propose that a female sex-specific epigenetic inheritance pattern for Crohn's disease is a major contributing factor in the family-specific risk in Crohn's disease. Sex-specific manifestation of familial Crohn's disease can partly explain the epidemiologically observed increased relative risk for females for contracting IBD.

Clinical predictors of inflammatory bowel disease in a genetically well-defined Caucasian population

Background

Crohn's disease (CD) and ulcerative colitis (UC), the two main types of inflammatory bowel disease (IBD), are multifactorial conditions of unknown etiology. The objective of this study is to examine the combined gene-environment interactions influencing IBD susceptibility in a well-defined Caucasian cohort in rural mid-America.

Methods

Patients were diagnosed to have CD or UC using conventional radiologic, endoscopic, and/or histopathologic findings. Histological diagnosis was made by a single specialist gastrointestinal pathologist with a particular interest in IBD. Information regarding cigarette smoke exposure was obtained by administration of the Behavioral Risk Factor Surveillance System Survey (BRFSS) to all patients. Genomic DNA was extracted from peripheral blood leukocytes, and polymerase chain reaction (PCR) amplification and genotyping were performed for 11 Single Nucleotide Polymorphisms (SNP) in NOD2, IL23r, OCTN1 genes along with IGR.

Results

Our cohort consists of 1196 patients: 435 controls, 485 CD patients, and 276 UC patients. Only patients with genotype data for at least 7 of 11 SNPs were included in our data analysis. The control groups for all 11 SNPs were in Hardy-Weinberg Equilibrium. In genotype-association SNP analysis, all NOD2 SNPs (rs5743293, rs2066844, rs2066845) and the IL23r SNP (rs11465804) showed a significant association to IBD (p < 0.03). A multiple gene-interaction analysis showed an association between NOD2 and IL23r with UC (p = 0.04). There were no associations between any OCTN1 and IGR SNPs and IBD in this cohort. A multivariable logistic regression analysis showed that female gender, "current" or "former" smoking status, family history of IBD, and NOD2 SNP minor alleles were associated with CD.

Conclusion

IBD remains to be challenging to properly diagnose, characterize, and treat. Our study proposes a combined genetic, phenotypic, and environmental approach in an attempt to better understand IBD. Previously demonstrated associations between OCTN1 and IGR and IBD were not confirmed.

OCTN1 variant L503F is associated with familial and sporadic inflammatory bowel disease

PURPOSE

A two-allele haplotype of TC (OCTN1 rs1050152 and OCTN2 -207G→C) is associated with Crohn's disease (CD). The association has been replicated in different populations, but also failed in some studies. The present study is to replicate the association of OCTN1 rs1050152 and examine another variant rs272879 with familial and sporadic inflammatory bowel disease (IBD) in a cohort from central Pennsylvania, USA.

METHODS

The study samples (n=465) included 212 inflammatory bowel disease patients (CD=115, UC=97), including 103 familial (CD=55, UC=46) and 111 sporadic (CD=60, UC=51) IBD, 139 non-IBD family members from a familial IBD registry, and 114 unrelated healthy controls. A total of 12 OCTN1 variants within exonic sequences were examined. Two nonsynonymous SNPs, rs1050152 (L503F) and rs272879 (L395V) were genotyped by a PCR-based RFLP/cRFLP method and statistically analyzed. These samples with an additional 141 unrelated healthy samples were also genotyped for rs1050152 using the SNPlex™ Genotyping System.

RESULTS

The OCTN1 rs1050152 is associated with CD (OR=1.745, 95% CI=1.019-2.990, χ²=4.129, p=0.042) and with IBD (OR=1.68, 95% CI=1.052-2.676, χ²=4.732, p=0.030); while the variant rs272879 is not associated with IBD, CD or ulcerative colitis (UC). The distribution of the rs1050152 variant showed a high level of the T allele in male UC (OR=2.585, 95% CI=1.139-5.869, p=0.023) and IBD (OR=2.039, 95% CI=1.024-4.059, p=0.042) patients, and in female CD patients (OR=2.329, 95% CI=1.038-5.226, ρ value=0.039).

CONCLUSION

The present results replicated the association of the OCTN1 rs1050152 (L503F) variant with CD and IBD overall. A weak gender-specific effect of rs1050152 (L503F) on male UC and female CD was observed.

Genome-wide association studies - A summary for the clinical gastroenterologist

Genome-wide association studies (GWAS) have been applied to various gastrointestinal and liver diseases in recent years. A large number of susceptibility genes and key biological pathways in disease development have been identified. So far, studies in inflammatory bowel diseases, and in particular Crohn’s disease, have been especially successful in defining new susceptibility loci using the GWAS design. The identification of associations related to autophagy as well as several genes involved in immunological response will be important to future research on Crohn’s disease. In this review, key methodological aspects of GWAS, the importance of proper cohort collection, genotyping issues and statistical methods are summarized. Ways of addressing the shortcomings of the GWAS design, when it comes to rare variants, are also discussed. For each of the relevant conditions, findings from the various GWAS are summarized with a focus on the affected biological systems.