Takuya Awata

A Subtype of Diabetes Mellitus Associated with a Mutation of Mitochondrial DNA

BACKGROUND Several families have been described in which a mutation of mitochondrial DNA, the substitution of guanine for adenine (A-->G) at position 3243 of leucine transfer RNA, is associated with diabetes mellitus and deafness. The prevalence, clinical features, and pathophysiology of diabetes with this mutation are largely undefined. METHODS We studied 55 patients with insulin-dependent diabetes mellitus (IDDM) and a family history of diabetes (group 1), 85 patients with IDDM and no family history of diabetes (group 2), 100 patients with non-insulin-dependent diabetes mellitus (NIDDM) and a family history of diabetes (group 3), and 5 patients with diabetes and deafness (group 4) for the mutation. We also studied the prevalence and characteristics of diabetes in 39 patients with a syndrome consisting of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes who were known to have the mutation and 127 of their relatives (group 5). RESULTS We identified 16 unrelated patients with diabetes associated with the A-->G mutation: 3 patients from group 1 (6 percent), 2 patients from group 3 (2 percent), 3 patients from group 4 (60 percent), and 8 patients from group 5 (21 percent). We also identified 16 additional subjects who had diabetes and the mutation among 42 relatives of the patients with diabetes and the mutation in groups 1, 2, 3, and 4 and 20 affected subjects among the 127 relatives of the patients in group 5. Diabetes cosegregated with the mutation in a fashion consistent with maternal transmission, was frequently (in 61 percent of cases) associated with sensory hearing loss, and was generally accompanied by impaired insulin secretion. CONCLUSIONS Diabetes mellitus associated with the A-->G mutation at position 3243 of mitochondrial leucine transfer RNA represents a subtype of diabetes found in both patients with IDDM and patients with NIDDM in Japan.

Lipophilic HMG-CoA reductase inhibitor has an anti-inflammatory effect: Reduction of MRNA levels for interleukin-1β, interleukin-6, cyclooxygenase-2, and p22phox by regulation of peroxisome proliferator-activated receptor α (PPARα) in primary endothelial cells

We examined the effects of four 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (pravastatin, simvastatin, fluvastatin, and cerivastatin) on the production and expression of inflammatory cytokines and on enzyme expression involving prostaglandin and superoxide production in cultured human umbilical vein endothelial cells (HUVEC). All HMG-CoA reductase inhibitors significantly reduced interleukin-1beta and -6 mRNA expression and their protein levels in the culture medium, and also inhibited cyclooxygenase-2 mRNA expression and their protein levels. And these drugs induced peroxisome proliferator-activated receptor alpha (PPARalpha) and PPARgamma mRNA expression and their protein levels in HUVEC and hepatocyte. Moreover, the mRNA levels of p22phox, a 22-kD subunit and the protein levels of p47phox, a 47-kD subunit of nicotine adenine dinucleotide phosphate (NADPH) oxidase, was decreased by treatment with either simvastatin, fluvastatin or cerivastatin, and this effect was reversed by mevalonate, geranylgeraniol, farnesol, and cholesterol. The changes induced by HMG-CoA reductase inhibitors might be due to regulation of cellular cholesterol content level, cellular cholesterol metabolic pathway, and cellular PPARalpha activity, which was related with inflammation. This unique anti-inflammatory effect in addition to its hypolipidemic action, may be beneficial in preventing the vascular complications that are induced by hyperlipidemia.

Effect of New Oral Antidiabetic Agent CS-045 on Glucose Tolerance and Insulin Secretion in Patients with NIDDM

Objective To study the effects of CS-045, a newly developed thiazolidine analogue, on glucose tolerance and insulin response to oral glucose load in patients with non-insulin-dependent diabetes mellitus (NIDDM). Research Design and Methods Nineteen NIDDM patients (mean ± SD age 48.9 ± 9.4 yr) whose previous glycemic control on diet and/or sulfonylurea (SU) therapy was judged stable but unsatisfactory (> 7.8 mM) were selected for this study. CS-045 (400 mg/day p.o.) was given alone or together with the previous SU drugs for 12 wk. A 75-g oral glucose tolerance test (OGTT) was performed before and after CS-045 treatment. Results The following results were found after CS-045 treatment. 1) Fasting plasma glucose (FPG) and HbA1c decreased (n = 19, FPG, 11.0 ± 2.4 vs. 8.4 ± 2.7 mM [before vs. after], P < 0.001; HbA1c, 8.0 ± 1.1 vs. 7.4 ± 1.3%, P < 0.005), and glucose tolerance markedly improved. 2) Fasting insulin (immunoreactive insulin [IRI]) and insulin response during OGTT decreased (n = 19, fasting IRI, 77.4 ± 49.8 vs. 56.5 ± 24.6 pM [before vs. after], P < 0.05; area under the curve of IRI, 540.3 ± 350.5 vs. 426.4 ± 216.3 pM.h, P < 0.05). Conclusions CS-045 is effective in improving glucose tolerance without stimulation of insulin secretion in NIDDM, suggesting an effect in improving insulin sensitivity.

Systematic search for single nucleotide polymorphisms in a lymphoid tyrosine phosphatase gene (PTPN22): Association between a promoter polymorphism and type 1 diabetes in Asian populations

The protein tyrosine phosphatase, nonreceptor 22 gene (PTPN22) maps to human chromosome 1p13.3‐p13.1 and encodes an important negative regulator of T‐cell activation, lymphoid‐specific phosphatase (Lyp). Recently, the minor allele of a single‐nucleotide polymorphism (SNP) at nucleotide position 1858 (rs2476601, +1858C > T) was found to be associated with type 1 diabetes. However, the degree of the association is variable among ethnic populations, suggesting the presence of other disease‐associated variants in PTPN22. To examine this possibility, we carried out a systemic search for PTPN22 using direct sequencing of PCR‐amplified products in the Japanese population. Association and linkage studies were also conducted in 1,690 Japanese samples, 180 Korean samples, and 472 Caucasian samples from 95 nuclear families. We identified five novel SNPs, but not the +1858C > T SNP. Of these two frequent SNPs, −1123G > C, and +2740C > T were in strong linkage disequilibrium (LD), and the −1123G > C promoter SNP was associated with acute‐onset but not slow‐onset type 1 diabetes in the Japanese population (odds ratio [OR] = 1.42, 95% CI = 1.07–1.89, P = 0.015). This association was observed also in Korean patients with type 1 diabetes (Mantel–Haenszel χ2 = 6.543, P = 0.0105, combined OR = 1.41 95% CI = 1.09–1.82). Furthermore, the affected family‐based control (AFBAC) association test and the transmission disequilibrium analysis of multiplex families of European descent from the British Diabetes Association (BDA) Warren Repository indicated that the association was stronger in −1123G > C compared to +1858C > T. In conclusion, the type 1 diabetes association with PTPN22 is confirmed, but it cannot be attributed solely to the +1858C > T variant. The promoter −1123G > C SNP is a more likely causative variant in PTPN22.

High Frequency of Aspartic Acid at Position 57 of HLA-DQ β-Chain in Japanese IDDM Patients and Nondiabetic Subjects

The HLA-DQ β-chain (DQB1) genes of 72 Japanese patients with insulin-dependent diabetes mellitus (IDDM) and 85 control subjects were studied with polymerase chain-reaction (PCR) amplification and allele-specific oligonucleotide hybridization. DQw4 (DQBBIank) and DQw9 (DQB3.3) were increased in IDDM patients compared with the control subjects, and DQB1.2, DQB1.9, and DQw7 (DQB3.1) were decreased. Thirty-five (48.6%) IDDM patients had both alleles carrying an aspartic acid at position 57 of the DQ β-chain (Asp 57), 35 (48.6%) were Asp 57/non-Asp 57 heterozygous, and 2 (2.8%) had non-Asp 57 alleles only. Of 85 control subjects, the respective values for these three genotypes were 49 (57.6%), 29 (34.1%), and 7 (8.2%), respectively. The high frequency of Asp 57 alleles in both IDDM and control subjects contrasts with data for Whites. Therefore, the Asp 57 hypothesis that the presence of an aspartic acid at position 57 of DQ β-chain provides protection against developing IDDM is not tenable for Japanese IDDM patients. The DRB1 gene, particularly position 57 of the DR β-chain, may contribute to IDDM susceptibility in Japanese.

Bezafibrate has an antioxidant effect: Peroxisome proliferator-activated receptor α is associated with Cu2+, Zn2+-superoxide dismutase in the liver

Administration of bezafibrate in rats significantly reduced the levels of plasma thiobarbituric acid-reactive substances (TBARS) in comparison with those obtained in rats fed a soy or lard chow. Moreover, an elevation of in vitro conjugated diene production and linoleic acid levels in the high-density lipoproteins and low-density lipoproteins induced by a soy or lard chow, was reduced by bezafibrate administration. In addition, the liver Cu2+, Zn2+-superoxide dismutase (SOD) gene expression showed a significant positive correlation with the liver peroxisome proliferator-activated receptor alpha (PPARalpha) mRNA level (R=0.769, p<0.0001). This unique characteristic of bezafibrate, which possesses both a hypolipidemic effect and antioxidant activity, may be beneficial in preventing vascular complications in hyperlipidemia.

Phenotype and Genotype Characteristics of Age-related Macular Degeneration in a Japanese Population

PURPOSE To describe phenotype and genotype characteristics of age-related macular degeneration (AMD) in Japanese patients. DESIGN A case-control study. PARTICIPANTS A total of 550 case-control samples composed of 408 consecutive AMD cases and 142 controls. METHODS Clinical information assessing age, gender, affected eyes, fundus features, and fluorescein/indocyanine green angiograms were systematically evaluated. Four single nucleotide polymorphisms (SNPs; rs800292, rs1061170, rs1410996, rs2274700) in the complement factor H (CFH) gene, 1 SNP (rs11200638) in the high-temperature requirement factor A1 (HTRA1) gene, 3 SNPs (rs699947, rs1570360, rs2010963) in the vascular endothelial growth factor (VEGF) gene, and 4 SNPs (rs12150053, rs12948385, rs9913583, rs1136287) in the pigment epithelium-derived factor (PEDF) gene were assessed using TaqMan technology. MAIN OUTCOME MEASURES The clinical phenotype information and genotypes of CFH, HTRA1, VEGF, and PEDF polymorphisms. RESULTS Of Japanese patients with neovascular AMD (nAMD), 219 (58.7%) had typical nAMD and 154 (41.3%) had polypoidal choroidal vasculopathy (PCV). The frequency of bilateral exudative involvement was similar between typical nAMD (15.5%) and PCV (13.6%) (P = 0.613). Significant soft drusen were observed in the fellow eyes of 88 (47.6%) of 185 patients with unilateral typical nAMD and in 25 (18.8%) of 133 patients with unilateral PCV (P = 1.24x10(-7)). A serous pigment epithelium detachment was seen in 55 (25.1%) of 219 patients with typical nAMD and in 64 (41.6%) of 154 patients with PCV. A significant association was noted in CFH-rs800292, CFH-rs1410996, CFH-rs2274700, and HTRA1-rs11200638 with AMD development (P = 2.36x10(-5), 7.18x10(-5), 7.18x10(-5), 2.70x10(-7), respectively; population attributable risk = 57.3%, 57.8%, 57.8%, and 58.9%, respectively). We estimated the highest-risk group to have an approximately 70-fold greater risk of nAMD compared with the lowest-risk group when analyzing a combination of 4 SNPs in the CFH and HTRA1 genes. CONCLUSIONS The Japanese AMD phenotype is characterized by a higher frequency of PCV, male predominance, and lower frequency of bilateral presentation compared with Caucasian AMD. Genotype analyses demonstrate a significant population attributable risk for SNPs in the CFH and HTRA1 genes and demonstrate joint effects for both genes. Gene variants in both CFH and HTRA1 contribute significantly to the AMD phenotype in a Japanese population.

Association of polymorphism in the interferon ? gene with IDDM

SummaryCytokines may play importmant roles in the pathogenesis of insulin-dependent diabetes mellitus (IDDM). We analysed a dinucleotide repeat polymorphism within the first intron of the interferon γ (IFN-γ) gene in Japanese diabetic patients (175 IDDM and 145 non-insulin-dependent diabetes mellitus) and 267 control subjects. A significant difference was observed in the global allele distribution of the polymorphism between the IDDM and control groups (p=0.039). The difference from the control group was more evident in the patients whose insulin therapy started within 1 year from onset (p=0.006) or in the young-onset (<10 years) patients (p=0.0006). The alleles “3” and “6” were increased in the IDDM patients, and a significant increase in the frequency of the “3/6” genotype was observed in the IDDM patient group (9.1%, RR 2.9, p=0.010), in the patients with initial insulin therapy less than 1 year from onset (10.6%, RR 3.4, p=0.004), or in the young-onset patients (16.7%, RR 5.7, p=0.0003) in comparison to the control subjects (3.4%). There was a tendency towards frequent occurrence of clinical characteristics which reflect young or abrupt onset of diabetes or both, and depletion of insulin secretion capacity in the patients with “3/6” or “6/6” in comparison to the patients with other genotypes. These results suggest that the IFN-γ gene region may contribute to the pathogenesis of IDDM and could be a genetic marker for IDDM.

Complement Factor H and High-Temperature Requirement A-1 Genotypes and Treatment Response of Age-related Macular Degeneration

PURPOSE To determine whether there is an association between complement factor H (CFH), high-temperature requirement A-1 (HTRA1), vascular endothelial growth factor (VEGF), and pigment epithelium-derived factor (PEDF) genotypes and response to treatment with photodynamic therapy (PDT) for age-related macular degeneration (AMD) in a Japanese population. DESIGN Prospective, case-control study. PARTICIPANTS One hundred ten patients with exudative AMD treated by verteporfin PDT were recruited prospectively at the Department of Ophthalmology, Saitama Medical University Hospital, Saitama, Japan. METHODS The patients were genotyped for 4 single nucleotide polymorphisms (SNPs; rs800292, rs1061170, rs1410996, rs2274700) in the CFH gene, a rs11200638-SNP in the HTRA1 gene, 3 SNPs (rs699947, rs1570360, rs2010963) in the VEGF gene, and 4 SNPs (rs12150053, rs12948385, rs9913583, rs1136287) in the PEDF gene using a TaqMan assay. MAIN OUTCOME MEASURES The treatment outcomes and genotypes of CFH, HTRA1, VEGF, and PEDF polymorphisms. RESULTS Best-corrected visual acuity 1 year after PDT was significantly increased in patients with the HTRA1-rs11200638 GG genotype as compared with patients with the GA or AA genotypes (P = 2.9 × 10⁻², 7.0 × 10⁻⁴, respectively). The rate of recurrence in the 12-month period after PDT was also associated with HTRA1-rs11200638 genotype (P = 3.12 × 10⁻²). Patients with the AA genotype of HTRA1-rs11200638 had an approximately 6-fold greater risk of the recurrence than patients with the GG genotype (P = 5.58 × 10⁻³). Significant differences were demonstrated in the mean time interval from the initial treatment to the time of recurrence for the genotypes of CFH-rs1410996/-rs2274700 (P = 8.50 × 10⁻³). CONCLUSIONS The HTRA1-rs11200638 and CFH-rs1410996/-rs2274700 variants were associated with response to PDT in this study population. These variants may be used for genetic biomarkers to estimate visual outcomes and recurrences in the response to PDT with significant predictive power.

Association of the HTRA1 gene variant with age-related macular degeneration in the Japanese population

AbstractThe purpose of this investigation was to determine whether the high-temperature requirement A-1 (HTRA1) gene polymorphism is associated with age-related macular degeneration (AMD) in native, unrelated Japanese patients. A total of 123 patients with AMD and 133 control subjects without AMD were recruited for this study. The single-nucleotide polymorphism (SNP) rs11200638 in the HTRA1 gene was assessed using a TaqMan assay. The risk A allele frequencies in the AMD cases and control patients were 0.577 and 0.380, respectively, and were associated with a significant risk of developing AMD (p=7.75×10−6). The results were more significant in subtype analyses with wet AMD (p=5.96×10−7). We conclude that the rs11200638 variant in the HTRA1 gene is strongly associated with AMD in the Japanese population. This result supports the hypothesis that the HTRA1 gene may increase susceptibility to AMD development and can participate in a potential new molecular pathway for AMD pathogenesis by extending this association across diverse ethnicities.