Kouichi Asano

A genome-wide association study identifies three new susceptibility loci for ulcerative colitis in the Japanese population

Ulcerative colitis is one of the principal forms of inflammatory bowel disease with complex manifestations. Although previous studies have indicated that there is a genetic contribution to the pathogenesis of ulcerative colitis, the genes influencing susceptibility to the disease have not been fully determined. To identify genetic factors conferring risk of ulcerative colitis, here we conducted a two-stage genome-wide association study and subsequent replication study using 1,384 Japanese individuals with ulcerative colitis and 3,057 control subjects. In addition to the expected strong association with the major histocompatibility complex (MHC) region, we identified three new susceptibility loci: the immunoglobulin receptor gene FCGR2A (rs1801274, P = 1.56 × 10−12), a locus on chromosome 13q12 (rs17085007, P = 6.64 × 10−8) and the glycoprotein gene SLC26A3 (rs2108225, P = 9.50 × 10−8). rs1801274 is a nonsynonymous SNP of FCGR2A that is reported to have a critical effect on receptor binding affinity for IgG and to be associated with other autoimmune diseases. Our findings provide insight into the molecular pathogenesis of ulcerative colitis.

Long-term effect of Helicobacter pylori eradication on the development of metachronous gastric cancer after endoscopic resection of early gastric cancer.

BACKGROUND A prospective, randomized trial proved that Helicobacter pylori eradication significantly reduces the incidence of metachronous gastric cancer during a 3-year follow-up. OBJECTIVE To investigate the long-term effect of H pylori eradication on the incidence of metachronous gastric cancer after endoscopic resection of early gastric cancer. DESIGN Retrospective, multicenter study. SETTING Kyushu University Hospital and 6 other hospitals in Fukuoka Prefecture, Japan. PATIENTS AND INTERVENTIONS Follow-up data for 268 H pylori-positive patients who had undergone endoscopic resection of early gastric cancer were retrospectively investigated. A total of 177 patients underwent successful H pylori eradication (eradicated group), whereas 91 had persistent H pylori infection (persistent group). MAIN OUTCOME MEASUREMENTS The incidence of metachronous gastric cancer was compared in these 2 groups. RESULTS When the follow-up period was censored at 5 years, the incidence rate in the eradicated group was lower than that observed in the persistent group (P = .007). During the overall follow-up period ranging from 1.1 to 11.1 years (median 3.0 years), metachronous gastric cancer developed in 13 patients (14.3%) in the persistent group and in 15 patients (8.5%) in the eradicated group (P = .262, log-rank test). Based on a multivariate logistic regression analysis, baseline severe mucosal atrophy and a follow-up of more than 5 years were found to be independent risk factors for the development of metachronous gastric cancer. LIMITATIONS Retrospective study. CONCLUSIONS H pylori eradication does not reduce the incidence of metachronous gastric cancer. H pylori eradication should be performed before the progression of gastric mucosal atrophy.

Meta‐analysis of published studies identified eight additional common susceptibility loci for Crohn's disease and ulcerative colitis

Background: Both ulcerative colitis (UC) and Crohns disease (CD) have a complex etiology involving multiple genetic and environmental factors. Many genome‐wide association studies (GWAS) and subsequent replication studies revealed that both diseases share some of the susceptibility loci; however, common genetic factors for both diseases are not fully elucidated. This study is aimed to identify the common genetic factors for CD and UC by a meta‐analysis of published studies. Methods: We first reviewed the 10 GWAS for CD to select candidate single nucleotide polymorphisms (SNPs). Next, we performed a PubMed literature search up to June 30, 2010 and carried out a systemic review of published studies that examined the association of CD susceptibility loci in UC patients. Meta‐analysis was carried out using the inverse variance‐weighted method or the DerSimonian‐Laird method after estimating the heterogeneity among the studies. The data for highly linked SNPs were combined. Finally, we performed a meta‐analysis of 43 published studies in 45 SNPs located at 33 loci by using a total of 4852 to 31,125 subjects. Results: We confirmed the association of 17 reported common susceptibility loci. Moreover, we found associations at eight additional loci: GCKR, ATG16L1, CDKAL1, ZNF365, LRRK2‐MUC19, C13orf31, PTPN2, and SBNO2. The genetic risk of each locus was modest (odds ratios ranged from 1.05–1.22) except IL23R. Conclusions: These results indicate that CD and UC share many susceptibility loci with small genetic effect. Our data provide further understanding of the common pathogenesis between CD and UC.

Impact of serum total cholesterol on the incidence of gastric cancer in a population‐based prospective study: The Hisayama study

The results of prospective studies that have examined the association between serum cholesterol levels and the incidence of gastric cancer remain controversial. To examine this issue in a general population, a total of 2,604 subjects aged 40 years or older were followed up prospectively for 14 years. During the follow‐up period, gastric cancer developed in 97 subjects. The age‐ and sex‐adjusted incidence of gastric cancer by quartiles of serum cholesterol level, namely, <4.06, 4.06–5.32, 5.33–6.04 and ≥6.05 mmol/L, were 3.9, 3.3, 3.1 and 2.1 per 1,000 person–years, respectively. The risk of gastric cancer increased with decreasing cholesterol level (age‐ and sex‐adjusted hazard ratio [HR], 1.22; 95% confidence interval [CI], 1.01–1.49; p = 0.04 for a decrease of 1 mmol/L in serum cholesterol level). This inverse association remained unchanged even after adjustment for other confounding factors, namely, Helicobacter pylori infection, atrophic gastritis, family history of malignant neoplasm, smoking habits, body mass index, hemoglobin A1c, white blood cell count and dietary factors (adjusted HR, 1.28; 95% CI, 1.03–1.58; p = 0.02). This association was significant for intestinal‐type gastric cancers, but not for diffuse‐type. As regards cancer stage, the inverse cholesterol‐cancer association was marginally significant for early gastric cancer after multivariate‐adjustment (adjusted HR, 1.25; 95% CI, 0.97–1.61; p = 0.09), but was not for advanced gastric cancer probably due to the small number of cases. In conclusion, our findings suggest that low serum cholesterol levels are an independent risk factor for developing gastric cancer, especially intestinal‐type gastric cancer.

A Hereditary Enteropathy Caused by Mutations in the SLCO2A1 Gene, Encoding a Prostaglandin Transporter

Previously, we proposed a rare autosomal recessive inherited enteropathy characterized by persistent blood and protein loss from the small intestine as chronic nonspecific multiple ulcers of the small intestine (CNSU). By whole-exome sequencing in five Japanese patients with CNSU and one unaffected individual, we found four candidate mutations in the SLCO2A1 gene, encoding a prostaglandin transporter. The pathogenicity of the mutations was supported by segregation analysis and genotyping data in controls. By Sanger sequencing of the coding regions, 11 of 12 other CNSU patients and 2 of 603 patients with a diagnosis of Crohn’s disease were found to have homozygous or compound heterozygous SLCO2A1 mutations. In total, we identified recessive SLCO2A1 mutations located at seven sites. Using RT-PCR, we demonstrated that the identified splice-site mutations altered the RNA splicing, and introduced a premature stop codon. Tracer prostaglandin E2 uptake analysis showed that the mutant SLCO2A1 protein for each mutation exhibited impaired prostaglandin transport. Immunohistochemistry and immunofluorescence analyses revealed that SLCO2A1 protein was expressed on the cellular membrane of vascular endothelial cells in the small intestinal mucosa in control subjects, but was not detected in affected individuals. These findings indicate that loss-of-function mutations in the SLCO2A1 gene encoding a prostaglandin transporter cause the hereditary enteropathy CNSU. We suggest a more appropriate nomenclature of “chronic enteropathy associated with SLCO2A1 gene” (CEAS).

Serum microRNA levels in patients with Crohn's disease during induction therapy by infliximab

microRNAs (miRNAs) have been suggested to be candidates for biomarkers in various diseases including Crohns disease (CD). To identify possible biomarkers predictive of the therapeutic effect of infliximab in CD, we investigated serum miRNA levels during the induction therapy by the medication.

NAD(P)H oxidase p22phox C242T polymorphism and ischemic stroke in Japan: the Fukuoka Stroke Registry and the Hisayama study.

The C242T polymorphism of p22phox, a component of NAD(P)H oxidase, may have an impact on cardiovascular diseases; however, the association between this polymorphism and brain infarction is not fully understood. Here, we investigate the relationship between the C242T polymorphism and brain infarction in Japan. We recruited 1055 patients with brain infarction and 1055 control subjects. A chi‐squared test revealed that the T‐allele frequency was lower in patients with cardioembolic infarction (5.6%) than in control subjects (11.0%, P < 0.001); however, allele frequencies in patients with lacunar and atherothrombotic infarction (11.2%) were not significantly different from those in control subjects (11.0%). A multivariate‐adjusted conditional logistic regression analysis also revealed no association between CT + TT genotype, and lacunar and atherothrombotic infarction (odds ratio = 0.97, 95% confidence interval: 0.72–1.32). To investigate the functional effects of the C242T polymorphism, we examined superoxide production in COS‐7 cells cotransfected with Nox4 and p22phox of each genotype. The superoxide‐producing activity in those cells expressing p22phox with the T allele was not significantly different from that in cells expressing p22phox with the C allele. The present results suggest that the p22phox C242T polymorphism may have a protective effect against cardioembolic infarction, but is not related to lacunar and atherothrombotic infarction in Japan.

Comparison of the therapeutic efficacy and safety between tacrolimus and infliximab for moderate-to-severe ulcerative colitis: a single center experience

Abstract Objective Both tacrolimus (Tac) and infliximab (IFX) are effective for moderate-to-severe ulcerative colitis (UC). The aim of this study was to compare the therapeutic efficacy and safety of both drugs. Materials and methods We performed a retrospective analysis of 46 patients with moderate-to-severe UC who were treated either by Tac (n = 21) or IFX (n = 25). We compared the remission and response rates for 10 weeks between the two groups. In patients who achieved a clinical response, the subsequent relapse rate was compared. The overall adverse events were also compared between the two groups. Results The remission and response rates at week 10 did not differ between patients treated with Tac (67% and 86%, respectively) and patients treated with IFX (76% and 92%, respectively). Among 41 patients showing a clinical response, eight of 23 patients treated with IFX and eight of 18 patients treated with Tac showed a subsequent relapse. The risk of relapse was not different between the two groups. While no serious adverse events were observed, the incidence of adverse events was higher in patients treated with Tac than in those treated with IFX. Conclusion Tac and IFX may be equally efficacious for the induction and maintenance of remission in patients with UC while minor adverse events are more frequent with the former treatment.

Impact of allele copy number of polymorphisms in FCGR3A and FCGR3B genes on susceptibility to ulcerative colitis.

Background: Polymorphisms in the Fc&ggr; receptor genes have been implicated in several autoimmune diseases, including ulcerative colitis (UC). However, most of these reports had not taken into account the effect of copy number variation at this region. Methods: We investigated the combined effect of allele and gene copy number of FCGR3A-158F/V and FCGR3B-NA1/NA2 on susceptibility to UC. Study subjects were composed of a total of 752 Japanese patients with UC and 2062 Japanese control subjects. To estimate allele copy number of the 2 polymorphisms, we integrated the results of PCR-based real-time Invader assay (PCR-RETINA) that measures the allelic ratio and Taqman assay that detects the total copy number. We analyzed the associations of allele copy number with UC using logistic regression model. Results: Gene and allele copy numbers of FCGR3A and FCGR3B were successfully determined in more than 99.5% of the study subjects. Allele copy number of FCGR3A-158F/V demonstrated significant association with susceptibility to UC (P = 0.02), although each single-nucleotide polymorphism and copy number variation alone did not show significant association. Although allele copy number of FCGR3B-NA1/NA2 (P = 0.002) also showed significant association with UC susceptibility, this association seemed to reflect the effect of FCGR3B gene copy number. Subsequent haplotype analyses revealed a strong association of a haplotype FCGR2A-131H/R and copy number of FCGR3B gene (P = 6.5 × 10−9). Conclusions: Allele copy number of FCGR3A-158F/V and FCGR3B gene copy number were associated with UC susceptibility. Our results suggest that organizing handling of immune complex by FCGR3A, FCGR3B, and FCGR2A may play a crucial role in the pathogenesis of UC.

Therapeutic Strategy for Crohn's Disease with a Loss of Response to Infliximab: A Single-Center Retrospective Study

Background/Aims: Infliximab (IFX) is an effective treatment for maintaining clinical remission in patients with initially moderate-to-severe Crohns disease (CD). However, a certain number of patients become unresponsive to IFX, subsequently requiring intensified therapy. The aim of this study was to compare the short- and long-term therapeutic efficacy of intensified regimens in CD patients who fail to respond to IFX. Methods: The clinical courses of 33 CD patients who failed to respond to treatment with IFX were investigated retrospectively. An intensified regimen involving doubling the dose of IFX was chosen in 13 patients (DD group) versus shortening the IFX interval in 13 patients (SI group) and switching to adalimumab (ADA) in 7 patients (SA group). Results: The clinical response and rate of clinical remission at 4 weeks were 62 and 54% in the DD group, 77 and 62% in the SI group and 57 and 43% in the SA group, respectively (p = 0.59 for clinical response, p = 0.90 for clinical remission). The rate of sustained remission at 48 weeks was 44% in the DD group, 54% in the SI group and 33% in the SA group (p = 0.88). Conclusion: The short- and long-term efficacy of doubling the dose of IFX, shortening the interval of IFX or switching to ADA is similar for CD patients who no longer respond to IFX.