Increased expression of IL12B mRNA transcribed from the risk haplotype for Crohn's disease is a risk factor for disease relapse in Japanese patients

IL12B rs6887695 polymorphism and interaction with alcohol intake in the risk of ulcerative colitis in Japan

BACKGROUND

The interleukin (IL)-23/Th17 pathway plays a critical role in ulcerative colitis (UC). The IL-12p40 subunit, which is shared by IL-23 and IL-12, is encoded by the IL12B gene. The current case-control study investigated the association between IL12B SNP rs6887695 and the UC risk.

METHODS

There were 384 cases within 4 years of UC diagnosis and 661 controls who were enrolled. Adjustments were made for sex, age, pack-years of smoking, alcohol consumption, history of appendicitis, family history of UC, education level, and body mass index.

RESULTS

Subjects with the GG IL12B SNP rs6887695 genotype had a significantly increased risk of UC compared with those with the CC genotype (adjusted odds ratio [AOR], 1.60; 95% confidence interval [CI], 1.08-2.36). This positive association was also significant using the additive and recessive models (AOR, 1.25; 95% CI, 1.03-1.52; AOR, 1.50; 95% CI, 1.08-2.09, respectively). An independent inverse relationship was observed between ever alcohol consumption and the UC risk in those with the CC genotype while no significant association was found in those with at least one G allele (P for interaction = 0.0008).

CONCLUSIONS

IL12B SNP rs6887695 was significantly associated with UC. The influence of alcohol consumption might rely on rs6887695.

Interleukin-12B gene rs6887695 and rs2288831 polymorphisms are associated with an increased risk of ulcerative colitis development in Chinese Han population: A case-control study

Background

The association of the interleukin (IL)‐12B gene rs6887695 and rs2288831 polymorphisms with ulcerative colitis (UC) risk has been extensively investigated, but results are conflicting. In this study, we investigated potential link between the IL‐12B gene rs6887695 and rs2288831 polymorphisms and UC development in Chinese Han population.

Material and Methods

Genotyping was performed in 367 patients and 456 controls through polymerase chain reaction‐restriction fragment length polymorphism analysis. Plasma levels of IL‐12B were tested using an enzyme‐linked immunosorbent assay.

Results

We found that the IL‐12B gene rs6887695 and rs2288831 polymorphisms were related to a significantly increased risk of UC. Subgroup analyses revealed significant associations of the IL‐12B gene rs6887695 and rs2288831 polymorphisms with UC risk among females, consumers of alcohol, and those aged <40 years. Additionally, the rs6887695 and rs2288831 polymorphisms were associated with lesion location and UC treatment. Last, we found that these two polymorphisms were associated with IL‐12B levels.

Conclusions

The IL‐12B gene rs6887695 and rs2288831 polymorphisms were associated with a higher risk, and the clinical characteristics, of UC.

A Genome-wide Association Study Identifying RAP1A as a Novel Susceptibility Gene for Crohn's Disease in Japanese Individuals

BACKGROUND AND AIMS

Genome-wide association studies [GWASs] of European populations have identified numerous susceptibility loci for Crohn's disease [CD]. Susceptibility genes differ by ethnicity, however, so GWASs specific for Asian populations are required. This study aimed to clarify the Japanese-specific genetic background for CD by a GWAS using the Japonica array [JPA] and subsequent imputation with the 1KJPN reference panel.

METHODS

Two independent Japanese case/control sets (Tohoku region [379 CD patients, 1621 controls] and Kyushu region [334 CD patients, 462 controls]) were included. GWASs were performed separately for each population, followed by a meta-analysis. Two additional replication sets [254 + 516 CD patients and 287 + 565 controls] were analysed for top hit single nucleotide polymorphisms [SNPs] from novel genomic regions.

RESULTS

Genotype data of 4 335 144 SNPs from 713 Japanese CD patients and 2083 controls were analysed. SNPs located in TNFSF15 (rs78898421, Pmeta = 2.59 × 10-26, odds ratio [OR] = 2.10), HLA-DQB1 [rs184950714, pmeta = 3.56 × 10-19, OR = 2.05], ZNF365, and 4p14 loci were significantly associated with CD in Japanese individuals. Replication analyses were performed for four novel candidate loci [p <1 × 10-6], and rs488200 located upstream of RAP1A was significantly associated with CD [pcombined = 4.36 × 10-8, OR = 1.31]. Transcriptome analysis of CD4+ effector memory T cells from lamina propria mononuclear cells of CD patients revealed a significant association of rs488200 with RAP1A expression.

CONCLUSIONS

RAP1A is a novel susceptibility locus for CD in the Japanese population.

Clinical importance of IL-22 cascade in IBD

IL-22 is a relatively new cytokine that is characterized by several unique biological properties. In the intestines, the effect of IL-22 is restricted mainly to non-lymphoid cells such as epithelial cells. Interestingly, the expression pattern and major cellular source of IL-22 have distinct difference between large and small intestines. IL-22 possesses an ability to constitutively activate STAT3 for promoting epithelial cell regeneration and reinforcing mucosal barrier integrity through stimulating the expression of anti-bacterial peptide and mucins. Of note, IL-22 is characterized as a two-faced cytokine that can play not only protective but also deleterious roles in the intestinal inflammation depending on the cytokine environment such as the expression levels of IL-23, T-bet, and IL-22 binding protein. Most importantly, clinical relevance of IL-22 to inflammatory bowel disease has been well highlighted. Mucosal healing, which represents the current therapeutic goal for IBD, can be induced by IL-22. Indeed, indigo naturalis, which can activate IL-22 pathway through Ahr, has been shown in a clinical trial to exhibit a strong therapeutic effect on ulcerative colitis. Despite the beneficial effect of IL-22, continuous activation of the IL-22 pathway increases the risk of colitis-associated cancer, particularly in patients with an extended history of IBD. This review article discusses how IL-22 regulates colitis, how beneficial versus deleterious effects of IL-22 is determined, and why IL-22 represents a promising target for IBD therapy.