Association of ATG16L1 gene haplotype with inflammatory bowel disease in Indians

ATG16L1 rs2241880/T300A increases susceptibility to perianal Crohn's disease: An updated meta-analysis on inflammatory bowel disease risk and clinical outcomes

BACKGROUND

ATG16L1 plays a fundamental role in the degradative intracellular pathway known as autophagy, being a mediator of inflammation and microbial homeostasis. The variant rs2241880 can diminish these capabilities, potentially contributing to inflammatory bowel disease (IBD) pathogenesis.

OBJECTIVES

To perform an updated meta-analysis on the association between ATG16L1 rs2241880 and IBD susceptibility by exploring the impact of age, ethnicity, and geography. Moreover, to investigate the association between rs2241880 and clinical features.

METHODS

Literature searches up until September 2022 across 7 electronic public databases were performed for all case-control studies on ATG16L1 rs2241880 and IBD. Pooled odds ratios (ORP ) and 95% CI were calculated under the random effects model.

RESULTS

Our analyses included a total of 30,606 IBD patients, comprising 21,270 Crohn's disease (CD) and 9336 ulcerative colitis (UC) patients, and 33,329 controls. ATG16L1 rs2241880 was significantly associated with CD susceptibility, where the A allele was protective (ORP : 0.74, 95% CI: 0.72-0.77, p-value: <0.001), while the G allele was a risk factor (ORP : 1.23, 95% CI: 1.09-1.39, p-value: 0.001), depending on the minor allele frequencies observed in this multi-ancestry study sample. rs2241880 was predominantly relevant in Caucasians from North America and Europe, and in Latin American populations. Importantly, CD patients harbouring the G allele were significantly more predisposed to perianal disease (ORP : 1.21, 95% CI: 1.07-1.38, p-value: 0.003).

CONCLUSIONS

ATG16L1 rs2241880 (G allele) is a consistent risk factor for IBD in Caucasian cohorts and influences clinical outcomes. As its role in non-Caucasian populations remains ambiguous, further studies in under-reported populations are necessary.

Newly Diagnosed Crohn's Disease Patients in India and Israel Display Distinct Presentations and Serological Markers: Insights from Prospective Cohorts

Background: Crohn’s disease (CD) incidence is rising in India. However, features of newly diagnosed patients with CD in this population are largely unknown. The Indo-Israeli IBD GastroEnterology paRtnership (TiiiGER) aimed to investigate differences in presentation among patients with newly diagnosed CD in India and Israel, and to explore phenotype−serotype correlations. Methods: A prospective observational cohort study of consecutive adults (>18 years) conducted in two large referral centers in India and Israel (2014−2018). Clinical data, an antiglycan serological panel, and 20 CD-associated genetic variants were analyzed. Outcomes: complicated phenotype at diagnosis and early complicated course (hospitalizations/surgeries) within 2 years of diagnosis. Results: We included 260 patients (104, Indian (65.4%, male; age, 37.8); 156 Israeli (49.4%, male; 31.8, age)). Median lag time from symptoms onset to diagnosis was 10.5 (IQR 3−38) vs. 3 (IQR 1−8) months in Indian vs. Israeli patients (p < 0.001). Complicated phenotype at diagnosis was observed in 48% of Indian and 30% of Israeli patients (p = 0.003). Complicated phenotype was associated with higher anti-Saccharomyces cerevisiae antibody (ASCA) seropositivity rate among Israeli patients (p < 0.001), but not among Indian patients. Antiglycan serology did not correlate with the tested genetic variants. Early complicated course occurred in 28 (18%) Israeli and 13 (12.5%) Indian patients. The time from diagnosis to complication was comparable (log rank p = 0.152). Antiglycan serology did not correlate with a complicated early course in either cohort. Conclusions: There are significant differences in patients presenting with newly diagnosed CD in India and Israel, including phenotype and distinct biomarkers at diagnosis. These differences suggest different genetic and environmental disease modifiers.

Associations between ATG16L1 gene polymorphism and antineutrophil cytoplasmic antibody‐associated vasculitis in the Chinese Guangxi population: A case–control study

Background

Antineutrophil cytoplasmic antibody (ANCA)‐associated vasculitis (AAV) is an autoimmune disease often accompanied by rapidly progressive renal failure, and the genetic background is still unknown. Our study was performed to test whether autophagy‐related 16 like 1 (ATG16L1) rs4663402 and rs4663396 single nucleotide polymorphisms (SNPs) were associated with AAV in the Chinese Guangxi population.

Methods

One hundred seventy seven unrelated AAV patients and 216 healthy controls were included in this case–control study. Multiplex polymerase chain reaction combined with high‐throughput sequencing was used for typing, and SNPStats and SHEsis were used for association analysis, pairwise linkage disequilibrium, and haplotype analysis.

Results

rs4663402 and rs4663396 were in Hardy–Weinberg equilibrium in AAV and control groups. The frequencies of rs4663402 AA, AT, and TT genotypes were 82.5%, 16.9%, and 0.6%, respectively, in patients with AAV, and 83.5%, 16.2%, and 0.5%, respectively, in controls. The frequencies of rs4663396 CC, CT, and TT genotypes were 63.8%, 33.9%, and 2.3%, respectively, in patients with AAV, and 69.2%, 26.6%, and 4.2%, respectively, in controls. Haplotype analysis revealed two SNPs in a single haplotype block (D′ = 1.0). Our logistic regression adjusted for sex and age showed no association between rs4663402 and rs4663396 and the risk for AAV in genetic models (p > 0.05). However, ATG16L1 rs4663396 CC and CT + TT genotypes exhibited statistically significant differences in the incidence of arthralgia (p = 0.03).

Conclusions

Our results indicated that ATG16L1 rs4663402 and rs4663396 polymorphisms were not associated with AAV in the Chinese Guangxi population. ATG16L1 rs4663396 CT + TT genotype may be associated with arthralgia.

Curcumin ameliorates dextran sulfate sodium-induced colitis in mice via regulation of autophagy and intestinal immunity

BACKGROUND/AIMS

Inflammatory bowel disease (IBD) is regarded as a kind of chronic and unspecific intestinal inflammatory disorder. Its exact pathogenesis has not been elucidated. Curcumin, as an herbal drug, has been used in the treatment of IBD due to its immunoregulation. Autophagy has been reported to play an important role in the mechanism of IBD. In the present study, we focused on the autophagic regulation role of curcumin in the murine model of dextran sulfate sodium (DSS)-induced colitis.

MATERIALS AND METHODS

We investigated the effects of curcumin on the progress of DSS-induced acute colitis in mice by evaluating the disease activity index (DAI) and histopathological score. Meanwhile, the mRNA and protein expression of autophagy-related key genes from colon tissues comprising autophagy-related 5 (ATG5), LC3-phosphatidylethanolamine conjugate (LC-3II), beclin-1, and B cell lymphoma 2 (bcl-2) was examined by quantitative reverse transcription polymerase chain reaction and Western blot. Furthermore, the mRNA and protein expression of cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL) 6, IL-10, and IL-17A, was examined. Autophagosome was also examined under transmission electron microscopy.

RESULTS

Both DAI and histopathological score increased in mice with DSS-induced colitis and obviously decreased after curcumin intervention. The expression levels of TNF-α, IL-6, IL-17, ATG5, LC-3II, and beclin-1 were significantly higher in mice with colitis than in normal ones, whereas those of IL-10 and bcl-2 decreased accordingly. However, curcumin intervention adjusted the expression level of those factors toward normal level. The number of autophagosome in the colon epithelia increased after DSS stimulation and decreased after curcumin administration.

CONCLUSION

Curcumin could prevent the development of DSS-induced colitis through the inhibition of excessive autophagy and regulation of following cytokine networks.

ATG16L1 T300A polymorphism is associated with Crohn's disease in a Northwest Greek cohort, but ECM1 T130M and G290S polymorphisms are not associated with ulcerative colitis

Background:

Crohn’s disease (CD) and ulcerative colitis (UC) are well-described disease entities with unknown etiopathogenesis. Environmental, genetic, gut microbiota, and host immune response correlations have been implicated. The role of susceptibility gene polymorphisms, such as ATG16L1 T300A and ECM1 T130M and G290S, is well-described, although controversial findings have been reported.

Methods:

Two hundred five patients with inflammatory bowel disease (108 CD and 97 UC), and 223 healthy blood donors (control group) from the Northwest Greece region were genotyped for rs2241880 (T300A), rs3737240 (T130M) and rs13294 (G290S) single nucleotide polymorphisms. Genotyping was performed using the real-time polymerase chain reaction method.

Results:

The frequency of G allele was significantly higher in CD patients compared to the control group (P=0.029; odds ratio [OR] 1.45, 95% confidence interval [CI] 1.04-2.03). Carriers of two G alleles (T300A), compared to those carrying only one, were 1.3 times more susceptible to CD (P=0.022; OR 2.45, 95%CI 1.14-5.27). In CD patients, the presence of the T300A polymorphism indicates a possible protective effect against developing a penetrating (B3) phenotype, while in UC patients, presence of the T300A polymorphism, indicates a possible protective effect against developing joint-involving extraintestinal manifestations.

Conclusion:

Our study found a significant association of the T300A polymorphism with CD susceptibility, suggesting that CD occurrence in our population has a strong genetic background, with the T300A G allele having an additive effect.

Genetics of ulcerative colitis: putting into perspective the incremental gains from Indian studies

Ulcerative colitis (UC), one of the two clinical subtypes of inflammatory bowel disease is perceived as a potential 'sleeping giant' in the Indian subcontinent. Clinical manifestation is overall believed to be the same across ethnic groups but overwhelming genetics from large European and fewer non-European studies have revealed shared as well as unique disease susceptibly signaturesbetween them, pointing to population specific differences at genomic and environmental levels. A systematic recount of the four major eras in UC genetics spanning earliest linkage analysis, cherry picked candidate gene association studies, unbiased genomewide association studies, their logical extension in trans-ethnic setting (Immunochip study), lastly whole exome sequencing efforts forrare variant burden; and lessons learnt thereof in context of genetically distinct Indian population was attempted in this review. Genetic heterogeneity manifesting at allelic/locus level across these approaches has been the consistent finding through the range of pan India studies. On the other hand, these salient findings also highlight the limitations of even the best of these genetic leadsfor prognostic/clinical application. The imminent need, therefore, for the UC research community to adopt newer approaches/tools with improved study design to (i) gain better insight into genetic/mechanistic basis of disease; (ii) identify biomarkers of immediate translational value; and (iii) develop new/alternate therapeutic options is emphasized at the end.

MiRNAs and inflammatory bowel disease: An interesting new story

Inflammatory bowel disease (IBD), as a chronic and recurrent inflammatory disorder, is caused by a dysregulated and aberrant immune response to exposed environmental factors in genetically susceptible individuals. Despite huge efforts in determining the molecular pathogenesis of IBD, an increasing worldwide incidence of IBD has been reported. MicroRNAs (miRNAs) are a set of noncoding RNA molecules that are about 22 nucleotides long, and these molecules are involved in the regulation of the gene expression. By clarifying the important role of miRNAs in a number of diseases, their role was also considered in IBD; numerous studies have been performed on this topic. In this review, we attempt to summarize a number of studies and discuss some of the recent developments in the roles of miRNAs in the pathophysiology, diagnosis, and treatment of IBD.