Takeo Naito

A coding variant in FTO confers susceptibility to thiopurine-induced leukopenia in East Asian patients with IBD

Objective Myelosuppression is a life-threatening complication of thiopurine therapy, and the incidence of thiopurine-induced myelosuppression is higher in East Asians than in Europeans. We investigated genetic factors associated with thiopurine-induced leukopenia in patients with IBD. Design A genome-wide association study (GWAS) was conducted in thiopurine-treated patients with IBD, followed by high-throughput sequencing of genes identified as significant in the GWAS or those involved in thiopurine metabolism (n=331). Significant loci associated with thiopurine-induced leukopenia were validated in two additional replication cohorts (n=437 and n=330). Functional consequences of FTO (fat mass and obesity-associated) variant were examined both in vitro and in vivo. Results The GWAS identified two loci associated with thiopurine-induced leukopenia (rs16957920, FTO intron; rs2834826, RUNX1 intergenic). High-throughput targeted sequencing indicated that an FTO coding variant (rs79206939, p.A134T) linked to rs16957920 is associated with thiopurine-induced leukopenia. This result was further validated in two replication cohorts (combined p=1.3×10−8, OR=4.3). The frequency of FTO p.A134T is 5.1% in Koreans but less than 0.1% in Western populations. The p.A134T variation reduced FTO activity by 65% in the nucleotide demethylase assay. In vivo experiments revealed that Fto−/− and Fto+/− mice were more susceptible to thiopurine-induced myelosuppression than wild-type mice. Conclusions The results suggest that the hypomorphic FTO p.A134T variant is associated with thiopurine-induced leukopenia. These results shed light on the novel physiological role of FTO and provide a potential pharmacogenetic biomarker for thiopurine therapy.

LRRK2 but not ATG16L1 is associated with Paneth cell defect in Japanese Crohn’s disease patients

BACKGROUND. Morphological patterns of Paneth cells are a prognostic biomarker in Western Crohns disease (CD) patients, and are associated with autophagy-associated ATG16L1 and NOD2 variants. We hypothesized that genetic determinants of Paneth cell phenotype in other ethnic CD cohorts are distinct but also involved in autophagy. METHODS. We performed a hypothesis-driven analysis of 56 single nucleotide polymorphisms (SNPs) associated with CD susceptibility or known to affect Paneth cell function in 110 Japanese CD patients who underwent ileal resection. We subsequently performed a genome-wide association analysis. Paneth cell phenotype was determined by defensin-5 immunofluorescence. Selected genotype-Paneth cell defect correlations were compared to a Western CD cohort (n = 164). RESULTS. The average percentage of abnormal Paneth cells in Japanese CD was similar to Western CD (P = 0.87), and abnormal Paneth cell phenotype was also associated with early recurrence (P = 0.013). In contrast to Western CD, ATG16L1 T300A was not associated with Paneth cell defect in Japanese CD (P = 0.20). Among the 56 selected SNPs, only LRRK2 M2397T showed significant association with Paneth cell defect (P = 3.62 × 10-4), whereas in the Western CD cohort it was not (P = 0.76). Pathway analysis of LRRK2 and other candidate genes with P less than 5 × 10-4 showed connections with known CD susceptibility genes and links to autophagy and TNF-α networks. CONCLUSIONS. We found dichotomous effects of ATG16L1 and LRRK2 on Paneth cell defect between Japanese and Western CD. Genes affecting Paneth cell phenotype in Japanese CD were also associated with autophagy. Paneth cell phenotype also predicted prognosis in Japanese CD. FUNDING. Helmsley Charitable Trust, Doris Duke Foundation (grant 2014103), Japan Society for the Promotion of Science (KAKENHI grants JP15H04805 and JP15K15284), Crohns and Colitis Foundation grant 274415, NIH (grants 1R56DK095820, K01DK109081, and UL1 TR000448).

De novo Crohn's disease following orthotopic liver transplantation: a case report and literature review.

The development of de novo Crohns disease (CD) after orthotopic liver transplantation (OLT) is rare, possibly due to the continuous use of immunosuppressive treatment. Although several cases of CD following OLT have been reported worldwide, there are currently so such cases in Japan. We herein report the case of a patient who newly developed CD after undergoing OLT for congenital biliary atresia. The patient subsequently underwent ileocecal resection and has since maintained clinical remission. This is the first report of this condition in Japan. We also review the literature concerning cases of de novo inflammatory bowel disease (IBD) developing after OLT, and discuss the causes of and role of immunosuppressive agents in treating IBD.

Tacrolimus Dose Optimization Strategy for Refractory Ulcerative Colitis Based on the Cytochrome P450 3A5 Polymorphism Prediction Using Trough Concentration after 24 Hours.

Background: In the tacrolimus treatment for refractory ulcerative colitis (UC), dose adjustment is necessary because the required doses to keep appropriate drug concentrations are significantly different among individuals. Cytochrome P450 (CYP) 3A5 polymorphism affects tacrolimus blood concentrations. However, it is difficult to obtain genetic information in real clinical practice. In the present study, we investigated possible factors that may predict CYP3A5 polymorphism and proposed a dose optimization strategy based on the obtained predicting factors. Summary: We retrospectively analyzed 41 patients who underwent remission induction therapy with tacrolimus for UC in our hospital. First, we performed a correlation analysis of CYP3A5 polymorphism and pharmacokinetics. In the CYP3A5 non-expressers, the dose of tacrolimus (mg/kg) was lower and dose-adjusted trough levels (ng/mL per mg/kg) were higher compared with those in expressers. Next, we investigated factors that could predict CYP3A5 polymorphism. Trough concentration 24 h following tacrolimus administration was extracted as a significant factor. When the trough cutoff value at 24 h was set to 2.6 ng/mL, sensitivity and specificity for estimation of CYP3A5 polymorphism were 63 and 96% respectively. Therefore, when the trough concentration 24 h after administration is ≤2.6 ng/mL, the patient can be estimated as a CYP3A5 expresser and an increase in dose should be proposed. Key Message: The trough concentration 24 h after the first tacrolimus administration appears to be a useful predictor of CYP3A5 polymorphism. Performing dose optimization strategy based on the prediction of CYP3A5 polymorphism can lead to earlier and safer remission induction.

Allele-specific DNA methylation of disease susceptibility genes in Japanese patients with inflammatory bowel disease

Background Inflammatory bowel disease (IBD) has an unknown etiology; however, accumulating evidence suggests that IBD is a multifactorial disease influenced by a combination of genetic and environmental factors. The influence of genetic variants on DNA methylation in cis and cis effects on expression have been demonstrated. We hypothesized that IBD susceptibility single-nucleotide polymorphisms (SNPs) regulate susceptibility gene expressions in cis by regulating DNA methylation around SNPs. For this, we determined cis-regulated allele-specific DNA methylation (ASM) around IBD susceptibility genes in CD4+ effector/memory T cells (Tem) in lamina propria mononuclear cells (LPMCs) in patients with IBD and examined the association between the ASM SNP genotype and neighboring susceptibility gene expressions. Methods CD4+ effector/memory T cells (Tem) were isolated from LPMCs in 15 Japanese IBD patients (ten Crohns disease [CD] and five ulcerative colitis [UC] patients). ASM analysis was performed by methylation-sensitive SNP array analysis. We defined ASM as a changing average relative allele score (ΔRAS¯) >0.1 after digestion by methylation-sensitive restriction enzymes. Among SNPs showing ΔRAS¯ >0.1, we extracted the probes located on tag-SNPs of 200 IBD susceptibility loci and around IBD susceptibility genes as candidate ASM SNPs. To validate ASM, bisulfite-pyrosequencing was performed. Transcriptome analysis was examined in 11 IBD patients (seven CD and four UC patients). The relation between rs36221701 genotype and neighboring gene expressions were analyzed. Results We extracted six candidate ASM SNPs around IBD susceptibility genes. The top of ΔRAS¯ (0.23) was rs1130368 located on HLA-DQB1. ASM around rs36221701 (ΔRAS¯ = 0.14) located near SMAD3 was validated using bisulfite pyrosequencing. The SMAD3 expression was significantly associated with the rs36221701 genotype (p = 0.016). Conclusions We confirmed the existence of cis-regulated ASM around IBD susceptibility genes and the association between ASM SNP (rs36221701) genotype and SMAD3 expression, a susceptibility gene for IBD. These results give us supporting evidence that DNA methylation mediates genetic effects on disease susceptibility.

Clinical and genetic risk factors for decreased bone mineral density in Japanese patients with inflammatory bowel disease: Risk factors of low BMD in Japanese IBD

Patients with inflammatory bowel disease (IBD) are at a high risk of low bone mineral density (BMD). Reportedly, clinical and genetic factors cause low BMD in Caucasians; however, studies in non‐Caucasian populations remain scarce.

NUDT15 codon 139 is the best pharmacogenetic marker for predicting thiopurine-induced severe adverse events in Japanese patients with inflammatory bowel disease: a multicenter study

BackgroundDespite NUDT15 variants showing significant association with thiopurine-induced adverse events (AEs) in Asians, it remains unclear which variants of NUDT15 or whether additional genetic variants should be tested to predict AEs. To clarify the best pharmacogenetic test to be used clinically, we performed association studies of NUDT15 variants and haplotypes with AEs, genome-wide association study (GWAS) to discover additional variants, and ROC analysis to select the model to predict severe AEs.MethodsOverall, 2630 patients with inflammatory bowel disease (IBD) were enrolled and genotyped for NUDT15 codon 139; 1291 patients were treated with thiopurines. diplotypes were analyzed in 970 patients, and GWASs of AEs were performed with 1221 patients using population-optimized genotyping array and imputation.ResultsWe confirmed the association of NUDT15 p.Arg139Cys with leukopenia and alopecia (p = 2.20E−63, 1.32E−69, OR = 6.59, 12.1, respectively), and found a novel association with digestive symptoms (p = 6.39E−04, OR = 1.89). Time to leukopenia was significantly shorter, and when leukopenia was diagnosed, thiopurine doses were significantly lower in Arg/Cys and Cys/Cys than in Arg/Arg. In GWASs, no additional variants were found to be associated with thiopurine-induced AEs. Despite strong correlation of leukopenia frequency with estimated enzyme activities based on the diplotypes (r2 = 0.926, p = 0.0087), there were no significant differences in the AUCs of diplotypes from those of codon 139 to predict severe AEs (AUC = 0.916, 0.921, for acute severe leukopenia, AUC = 0.990, 0.991, for severe alopecia, respectively).ConclusionsGenotyping of NUDT15 codon 139 was sufficient to predict acute severe leukopenia and alopecia in Japanese patients with IBD.

Effective and less invasive diagnostic strategy for gastrointestinal GVHD

Background and study aims  Rectosigmoidoscopy with biopsy has been regarded to be a useful procedure to diagnose gastrointestinal graft-versus-host disease (GVHD). However, little is known about the specific colonoscopic features of gastrointestinal GVHD. In this study, we focused on the 4 unique colonoscopic findings – orange peel appearance, spotty redness, small mucosal sloughing, and diffuse mucosal defect – which are possible specific findings of gastrointestinal GVHD. We aimed to estimate the usefulness of these four unique colonoscopic findings in the rectosigmoid portion to diagnose gastrointestinal GVHD. Patients and methods  Seventy patients who were histologically diagnosed with gastrointestinal GVHD at our institute were retrospectively enrolled. Colonoscopic findings were reviewed, focusing on the four characteristic findings. The percentage of the positive cases for the characteristic findings was calculated. The final scoping portion and the number of cases showing any of the four characteristic findings in the rectosigmoid portion were also evaluated. The relationships between biopsy sites and the histological findings were also evaluated. Results  Orange peel appearance was observed in 66 cases (94.3 %). Spotty redness was observed in 45 cases (64.3 %). Small mucosal sloughing was observed in 49 cases (70.0 %). Diffuse mucosal defect was observed in six cases (8.6 %). The number of cases that were concurrently positive for one, two, and three findings were 16 (20.8 %), 20 (26.0 %), and 34 (48.6 %), respectively. Fifty-eight cases (82.9 %) were investigated up to the rectosigmoid portion, and 12 (17.1 %) were investigated beyond the sigmoid colon. All of the cases showed at least 1 of the 4 characteristics in the rectosigmoid portion. The percentage of crypt apoptosis in the biopsy specimen from orange peel appearance, spotty redness, small mucosal sloughing, and diffuse mucosal defect were 87.5 %, 83.3 %, 87.2 %, and 88.9 %, respectively. Conclusion  Orange peel appearance, spotty redness, small mucosal sloughing, and diffuse mucosal defect are the characteristic colonoscopic findings useful for diagnosis of gastrointestinal GVHD. These findings are frequently observed in the rectosigmoid portion. The histological detection rates for crypt cell apoptosis from these findings are high. Identifying the four characteristic findings on rectosigmoidoscopy and taking biopsies from these areas could be essential for the diagnostic strategy for gastrointestinal GVHD.

Mo1743 Genotyping of NUDT15 R139c Could Be a Companion Diagnostic Test for Thiopurine-Induced Leucopenia and Hair Loss in Japanese Patients With IBD

G A A b st ra ct s differentiated Caco-2 cells, treatment with either IL-6 or OSM showed no effect on ferritin, ferroportin or DMT-1-mRNA expression. Conclusion: Our studies data show that the proinflammatory cytokines IL-6 and OSM induce hepcidin promoter activity and mRNA level in HepG2 cells, both by means of the STAT3 pathway. Significant differences were seen in HepG2 cells regarding the inhibition of the iron transporters DMT-1 and ferroportin where IL-6 was inactive. These data indicate that OSM may be the more potent cytokine in terms of interfering in iron regulation. Further research is necessary to tighten up these data. (1) Sanchez-Infantes D et al (2014);J Clin Endocrinol Metab 99: E217-E225. (2) Beigel F et al (2014); PLoS One 7;9(4)