Association between ATG16L1 gene polymorphism and the risk of Crohn's disease

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.

Multi-omics in Crohn's disease: New insights from inside

Crohn's disease (CD) is an inflammatory bowel disease (IBD) with complex clinical manifestations such as chronic diarrhea, weight loss and hematochezia. Despite the increasing incidence worldwide, cure of CD remains extremely difficult. The rapid development of high-throughput sequencing technology with integrated-omics analyses in recent years has provided a new means for exploring the pathogenesis, mining the biomarkers and designing targeted personalized therapeutics of CD. Host genomics and epigenomics unveil heredity-related mechanisms of susceptible individuals, while microbiome and metabolomics map host-microbe interactions in CD patients. Proteomics shows great potential in searching for promising biomarkers. Nonetheless, single omics technology cannot holistically connect the mechanisms with heterogeneity of pathological behavior in CD. The rise of multi-omics analysis integrates genetic/epigenetic profiles with protein/microbial metabolite functionality, providing new hope for comprehensive and in-depth exploration of CD. Herein, we emphasized the different omics features and applications of CD and discussed the current research and limitations of multi-omics in CD. This review will update and deepen our understanding of CD from integration of broad omics spectra and will provide new evidence for targeted individualized therapeutics.

Effects of Herb-Partitioned Moxibustion on Autophagy and Immune Activity in the Colon Tissue of Rats with Crohn’s Disease

Objective

To investigate the mechanism of action of herb-partitioned moxibustion on CD from the perspective of autophagy and immunity.

Methods

The expression of microtubule-associated protein LC3II and SQSTM1/p62 in the colon tissues was detected by immunohistochemistry. Western blot was used to detect the expression of autophagic and immune-related proteins in the colon, such as LC3II, SQSTM1/p62, Beclin1, ATG16L1, NOD2, IRGM, IL-1β, IL-17, and TNF-β. mRNA levels of immune factors, such as IL-1β, IL-17, and TNF-β, and autophagy signaling molecules, such as PI3KC, AKT1, LKB1, and mTOR, were detected by RT-qPCR.

Results

Herb-partitioned moxibustion reduced the protein levels of ATG16L1, NOD2, IRGM, LC3II, and Beclin1 (P < 0.01) and both the protein and mRNA levels of IL-1β, IL-17, and TNF-β in CD rats (P < 0.01 or P < 0.05), and it also increased the expression of SQSTM1/p62 protein (P < 0.01). The modulatory effects of herb-partitioned moxibustion on ATG16L1, NOD2, IRGM, LC3II, TNF-β, and IL-17 protein and IL-1β protein and mRNA were better than those of mesalazine (P < 0.01 or P < 0.05). Herb-partitioned moxibustion also reduced colon PI3KC, AKT1, and LKB1 mRNA expressions in CD rats (P < 0.01 or P < 0.05) and increased mTOR protein expression (P < 0.05). And the modulatory effect of herb-partitioned moxibustion on AKT1 mRNA was better than that of mesalazine (P < 0.05).

Conclusion

Herb-partitioned moxibustion may inhibit excessively activated autophagy and modulate the expression of immune-related factors by regulating the LKB1-mTOR-PI3KC signal transduction networks, thereby alleviating intestinal inflammation in CD rats.

Microbial pathogenesis in inflammatory bowel diseases

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal system. Previously, it is considered the disease of the western world but now the incidence and prevalence of IBD are increasing globally with urbanization and modernization. Additionally, the major problem is the highest incidence of IBD among children and adolescents. The precise etiology of IBD is unknown and there is no cure for IBD, which is also the reason for increasing the number of cases worldwide. The IBD is a complex interplay of environment, immune system, and microbiota in a genetically susceptible host. Among these factors, the alteration in intestinal microbiota has been detected in IBD patients. The bacterial species associated with IBD include Mycobacterium paratuberculosis, adherent-invasive E. coli (AIEC), Helicobacter pylori, and Campylobacter concisus. Moreover, the efficacy of antibiotics and probiotics further suggests the role of microbes in IBD. However, no study confirmed the bacterial species as a cause of IBD as per Koch's postulates. Thus, still controversies exist regarding the role of microbes in IBD. Therefore, this paper aims to review the current literature to evaluate the role of microbes in IBD that would be a useful inventory of researchers working in this area.

Genetic association analysis of ATG16L1 rs2241880, rs6758317 and ATG16L2 rs11235604 polymorphisms with rheumatoid arthritis in a Chinese population

OBJECTIVE

This study was performed to test whether ATG16L1 rs2241880, rs6758317 and ATG16L2 rs11235604 polymorphisms were associated with RA and further examine the genetic interaction between ATG16L1 and ATG16L2 in RA among a Chinese population.

METHODS

A total of 594 RA patients and 604 healthy controls were included, and the genetic polymorphisms were genotyped based on HI-SNP technology.

RESULTS

Significant associations of ATG16L1 rs2241880 polymorphism with RA (T/T versus C/T + C/C, OR = 1.32, 95% CI 1.04-1.67, P = 0.02), cyclic citrullinated peptide (CCP)-positive RA (genotype comparison, P = 5.38 × 10^-3; T/T versus C/T + C/C, OR = 1.45, 95% CI 1.12-1.87, P = 4.86 × 10^-3) and rheumatoid factor (RF)-positive RA (genotype comparison, P = 0.03; T versus C, OR = 1.23, 95% CI 1.01-1.49, P = 0.04; T/T versus C/T + C/C, OR = 1.44, 95% CI 1.10-1.88, P = 7.62 × 10^-3) were found. Significant genetic interaction between ATG16L1 rs2241880 and ATG16L2 rs11235604 was associated RA (P = 0.03), and significant genetic interaction between ATG16L1 rs6758317 and ATG16L2 rs11235604 was associated with RA (P = 7.57 × 10^-3), CCP-positive RA (P = 0.01) and RF-positive RA (P = 0.01). Consistently, stratification analysis found that significant associations of RA with ATG16L1 rs2241880, rs6758317 polymorphisms were only detected among individuals carrying C/T genotype of the ATG16L2 rs11235604 polymorphism.

CONCLUSIONS

Our results indicated that ATG16L1 rs2241880 polymorphism was associated with RA in Chinese population, and provided evidence for genetic interaction between ATG16L1 and ATG16L2 in determing the development of RA, highlighting the involvement of autophagy in the pathogenesis of RA.