Risk Genes of Inflammatory Bowel Disease in Asia: What Are the Most Important Pathways Affected?

Molecular Foundations of Inflammatory Diseases: Insights into Inflammation and Inflammasomes

Inflammatory diseases are a global health problem affecting millions of people with a wide range of conditions. These diseases, including inflammatory bowel disease (IBD), rheumatoid arthritis (RA), osteoarthritis (OA), gout, and diabetes, impose a significant burden on patients and healthcare systems. A complicated interaction between genetic variables, environmental stimuli, and dysregulated immune responses shows the complex biological foundation of various diseases. This review focuses on the molecular mechanisms underlying inflammatory diseases, including the function of inflammasomes and inflammation. We investigate the impact of environmental and genetic factors on the progression of inflammatory diseases, explore the connection between inflammation and inflammasome activation, and examine the incidence of various inflammatory diseases in relation to inflammasomes.

Artificial intelligence and inflammatory bowel disease

With the development of artificial intelligence (AI) and its gradual application in the medical field, AI has brought new ideas to the medical development. The research and application of AI in inflammatory l bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease (CD), are increasing. Selecting appropriate models and methods through machine learning can help diagnose, treat, and predict the prognosis of IBD. In recent years, AI combined with endoscopy has made an appearance in the diagnosis of IBD and achieved satisfactory results. At the same time, AI plays an important role in the process of disease prediction and treatment evaluation for patients with IBD. However, we should also be aware that there are still some problems with AI. This paper gives a brief review of the practical application value of AI in IBD.

UK Patients of Bangladeshi Descent with Crohn's Disease Respond Less Well to TNF Antagonists Than Caucasian Patients

BACKGROUND

Patients with inflammatory bowel disease are currently managed with the assumption that trial data are applicable to all ethnic groups. Previous studies demonstrate differences in disease severity and phenotype of Asian patients with Crohn's disease (CD), including Bangladeshi Asians within the UK. No study has evaluated the impact of ethnicity on response to anti-TNFs.

AIM

Our primary endpoint was a comparison of failure-free survival on first prescribed anti-TNF (anti-tumor necrosis factor) therapy in UK Bangladeshi and Caucasian patients with CD. Our secondary aims were to evaluate disease phenotype, indication for anti-TNF prescription, and duration from diagnosis until first anti-TNF prescribed between groups.

METHODS

The records of consecutive outpatient appointments over a 12-month period were used to identify Caucasian and Bangladeshi patients prescribed an anti-TNF for CD. Information on patient demographics, ethnicity, disease phenotype, immunomodulator use, outcome from first biologic, duration of therapy, and reason for cessation was recorded.

RESULTS

In total, 224 Caucasian and Bangladeshi patients were prescribed an anti-TNF for CD. Bangladeshi patients started an anti-TNF 4.3 years earlier after diagnosis than Caucasian patients (3.9 years vs. 8.2 years: p < 0.01). Bangladeshi patients experienced shorter failure-free survival than Caucasian patients (1.8 vs. 4.8 years p < 0.01). By 2 years, significantly more Bangladeshi patients had stopped anti-TNF due to loss of response (OR 6.35, p < 0.01).

CONCLUSIONS

This is the first study to suggest that Bangladeshi patients resident in the UK with CD respond less well to treatment with TNF antagonists than Caucasian patients.

Polymorphisms of the TNF Gene and Three Susceptibility Loci Are Associated with Crohn's Disease and Perianal Fistula Crohn's Disease: A Study among the Han Population from South China

Background

Although 90 susceptibility loci of Crohn’s disease (CD) have been confirmed in the Asian population, susceptibility genes for perianal fistula of CD (pCD) in this population remain unknown. This study explored susceptibility genes for CD and pCD in the Han population from South China.

Material/Methods

In total, 490 patients diagnosed with CD between July 2012 and June 2016 at the Sixth Affiliated Hospital of Sun Yat-sen University were included and divided into the CD group (n=240) and the pCD group (n=250). The healthy control group was composed of 260 volunteers. Peripheral blood samples were taken, and single nucleotide polymorphism (SNP) locus sequencing was used to screen for susceptibility loci. SNPs were sequenced using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Results

Nine SNPs in TNFSF1 on chromosome 9 were associated with CD. Among them, the rs6478106 locus is a risk locus for CD. The distribution frequency of the T allele of the rs6478106 SNP was significantly different between cases and controls (32.49% versus 18.27%, P<0.001). Rs72553867, located in the IRGM gene on chromosome 5, rs4409764, located in the NKX2–3 gene on chromosome 10, and rs3731772, located in the AOX1 gene on chromosome 2, were susceptibility factors for pCD. Nine SNPs located in TNFSF15 on chromosome 9 were related to CD in Han individuals from Southern China.

Conclusions

The rs6478106 T allele is associated with the risk of CD in the investigated population. SNPs rs72553867 (IRGM gene), rs4409764 (NKX2–3 gene), and rs3731772 (AOX1 gene) increase the risk of pCD.

Genetic Studies of Inflammatory Bowel Disease-Focusing on Asian Patients

The pathogenesis of inflammatory bowel disease (IBD) is not well-understood; however, increased and persistent intestinal inflammation, due to inappropriate immune responses that are caused by interactions between genetic factors, gut microbiota, and environmental factors, are thought to lead to IBD. Various studies have identified more than 240 genetic variants related to IBD. These genetic variants are involved in innate and adaptive immunity, autophagy, defective bacterial handing, interleukin-23 and 10 signaling, and so on. According to several epidemiological and clinical studies, the phenotypes and clinical course of IBD differ between Asians and Europeans. Although the risk loci for IBD typically overlap between Asians and Westerners, genetic heterogeneity has been detected in many loci/genes, such as NOD2/CARD15, TNFSF15 and human leukocyte antigen, contributing to the risk of IBD. Thus, although common pathways exist between Westerners and Asians in the development of IBD, their significance may differ for individual pathways. Although genetic studies are not universally applicable in the clinical field, they may be useful for diagnosing and categorizing IBD, predicting therapeutic responses and toxicity to drugs, and assessing prognosis by risk modeling, thereby enabling precision medicine for individual patients.

Genetic associations of inflammatory bowel disease in a South Asian population

AIM

To estimate prevalence and phenotypic associations of selected inflammatory bowel disease (IBD)-associated genetic variants among Sri Lankan patients.

METHODS

A case study of histologically confirmed ulcerative colitis (UC) or Crohn’s disease (CD) patients with ≥ 1 year disease duration, who were compared to unrelated, gender-matched, healthy individuals as controls, was conducted at four major centers in Sri Lanka. Phenotypic data of the cases were obtained and all participants were genotyped for 16 selected genetic variants: IL12B:rs1045431, IL23R:rs11805303, ARPC2:rs12612347, IRGM:rs13361189, IL26/IL22:rs1558744, CDH1:rs1728785, IL10:rs3024505, FCGR2A:rs3737240, PTGER4:rs4613763, IL17REL/PIM3:rs5771069, HNF4a:rs6017342, STAT3:rs744166, SMURF1:rs7809799, LAMB1:rs886774, HLA-DRB5, DQA1, DRB1, DRA:rs9268853, MST1, UBA7, and APEH:rs9822268. The genotypes of all variants were in Hardy-Weinberg Equilibrium (P > 10⁻³). To account for multiple hypothesis testing, P-values < 0.003 were considered significant.

RESULTS

A total of 415 patients and 465 controls were recruited. Out of the single nucleotide polymorphisms (SNPs) tested, the majority were not associated with IBD in Sri Lankans. Significant positive associations were noted between rs886774 (LAMB1-gene) and UC (odds ratio (OR) = 1.42, P = 0.001). UC patients with rs886774 had mild disease (OR = 1.66, P < 0.001) and remained in remission (OR = 1.48, P < 0.001). A positive association was noted between rs10045431 (IL 12B gene) and upper gastrointestinal involvement in CD (OR = 4.76, P = 0.002).

CONCLUSION

This confirms the heterogeneity of allelic mutations in South Asians compared to Caucasians. Most SNPs and disease associations reported here have not been described in South Asians.

Population-specific genome-wide mapping of expression quantitative trait loci in the colon of Han Chinese

OBJECTIVE

To establish the colonic expression quantitative trait locus map in Han Chinese population and provide a functional reference for interpreting genetic associations of diseases such as inflammatory bowel disease (IBD).

METHODS

Colonic mucosal biopsies and peripheral blood samples were obtained from 48 Chinese Han individuals (24 ulcerative colitis patients and 24 healthy controls). Transcription profiling was performed using human whole genome expression array. Genotyping was done using a population-specific genotype array. Imputation was performed using IMPUTE2. Association between genotypes and gene expression was analyzed using a Matrix Expression Quantitative Trait Loci (eQTL) R package to identify eQTL. We used ChIPpeakAnno R package for annotation of the eQTL. Linkage disequilibrium between the eQTL and IBD risk loci was also investigated.

RESULTS

We identified 6 377 single nucleotide polymorphism-transcript interactions (cis-eQTL) in the colon of the Chinese participants. Most of the eQTL located near the transcription starting sites and overlapped with histone modification marks on the genome. A significant proportion of the eQTL were found to be within transcription factor-binding sites. Two IBD risk loci were found to be colon cis-eQTL in Chinese individuals, and 51 cis-eQTL were identified in another 18 IBD risk loci.

CONCLUSIONS

This study defined a population-specific catalogue of colon eQTL in the Chinese population. Potential functional variants of IBD association signals were identified. We provided a useful reference dataset for fine mapping IBD risk loci and identifying causal variants in the Chinese Han population.