Erratum to: Decreased glucagon levels and decreased insulin secretion after sitagliptin versus mitiglinide administration with similar glycemic levels following an oral glucose load: a randomized crossover pharmaceutical mechanistic study.

[This corrects the article DOI: 10.1007/s13340-015-0207-1.].

Decreased glucagon levels and decreased insulin secretion after sitagliptin versus mitiglinide administration with similar glycemic levels following an oral glucose load: a randomized crossover pharmaceutical mechanistic study.

AIMS: Both sitagliptin (SIT) and mitiglinide (MIT) can lower postprandial hyperglycemia. The purpose of this study was to examine differences in insulin and glucagon secretion after SIT or MIT administration when similar levels of plasma glucose (PG) were achieved for both agents following an oral glucose load. PATIENTS AND METHODS: We directly compared the effects of these two agents in 16 type-2 diabetic patients (M/F = 10/6, age 66 ± 3 years old, HbA1c 6.6 ± 0.5 %). Patients received SIT (50 mg qd for 1 week and 100 mg qd for an additional week) or MIT (10 mg tid for 2 weeks). After 2 weeks, patients crossed over to the other treatment. 75-g oral glucose tolerance tests were conducted before the study and after interventions. RESULTS: The area under the curve (AUC) up to 180 min for the PG response was similar for both agents. While basal insulin secretion rates (ISR) were similar, incremental AUC of ISR was significantly lower in the SIT treatment (522 ± 108 vs 702 ± 288 pmol/min min, p < 0.01), although the difference between the SIT and MIT treatments in the Matsuda index-which reflects insulin sensitivity-remained nonsignificant. Glucose-stimulated insulin secretion was similarly increased by the MIT and SIT treatments. Suppression of the AUC for glucagon was observed in the SIT treatment, while MIT treatment failed to suppress the glucagon concentration (-432 ± 2322 vs MIT 1116 ± 2520 pg/ml min, p < 0.05). The basal proinsulin/insulin ratio was lower in the SIT treatment (0.23 ± 0.04 vs MIT 0.26 ± 0.36, p < 0.05). CONCLUSIONS: Although either SIT or MIT can be employed to reduce postprandial hyperglycemia, SIT induces changes in hormonal profiles that are more favorable to islet functions than MIT does.

A genome-wide association study for diabetic retinopathy in a Japanese population: potential association with a long intergenic non-coding RNA.

Elucidation of the genetic susceptibility factors for diabetic retinopathy (DR) is important to gain insight into the pathogenesis of DR, and may help to define genetic risk factors for this condition. In the present study, we conducted a three-stage genome-wide association study (GWAS) to identify DR susceptibility loci in Japanese patients, which comprised a total of 837 type 2 diabetes patients with DR (cases) and 1,149 without DR (controls). From the stage 1 genome-wide scan of 446 subjects (205 cases and 241 controls) on 614,216 SNPs, 249 SNPs were selected for the stage 2 replication in 623 subjects (335 cases and 288 controls). Eight SNPs were further followed up in a stage 3 study of 297 cases and 620 controls. The top signal from the present association analysis was rs9362054 in an intron of RP1-90L14.1 showing borderline genome-wide significance (Pmet = 1.4×10(-7), meta-analysis of stage 1 and stage 2, allele model). RP1-90L14.1 is a long intergenic non-coding RNA (lincRNA) adjacent to KIAA1009/QN1/CEP162 gene; CEP162 plays a critical role in ciliary transition zone formation before ciliogenesis. The present study raises the possibility that the dysregulation of ciliary-associated genes plays a role in susceptibility to DR.

A low-frequency GLIS3 variant associated with resistance to Japanese type 1 diabetes.

The role of low-frequency variants in type 1 diabetes (T1D) susceptibility still remains to be clarified. In the present study, we analyzed low-frequency variants of the T1D candidate genes in Japanese. We first screened for protein-changing variants of 24 T1D candidate genes in 96 T1D patients and 96 control subjects, and then the association with T1D was tested in 706 T1D patients and 863 control subjects recruited from the collaborating institutions in Japan. In total, 56 protein-changing variants were discovered; among them, 34 were low-frequency variants (allele frequency < 5%). The association analysis of the low-frequency variants revealed that only the A908V variant of GLIS3 was strongly associated with resistance to T1D (Haldane's odds ratio = 0.046, p = 8.21 × 10(-4), and pc=2.22 × 10(-2)). GLIS3 is a zinc finger transcription factor that is highly expressed in pancreatic beta cells, and regulates beta cell development and insulin gene expression. GLIS3 mRNA is also moderately expressed in the human thymus. The precise mechanism responsible for the association is unclear at present, but the A908V variant may affect autoimmunity to the GLIS3 protein itself; the 908V containing epitope may induce central or peripheral tolerance more efficiently than that of 908A.

Meloxicam ameliorates motor dysfunction and dopaminergic neurodegeneration by maintaining Akt-signaling in a mouse Parkinson's disease model.

A series of oxicam non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to be neuroprotective against 1-methyl-4-phenyl pyridinium in human neuroblastoma SH-SY5Y cells via the phosphatidylinositol 3-kinase (PI3K)/Akt pathway independent of cyclooxygenase (COX) inhibition. The present study endeavored to establish this novel effect of meloxicam (MLX), an oxicam NSAID, in a mouse Parkinson's disease (PD) model using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Male C57BL/6 mice, which received MPTP (30 mg/kg/day; s.c.) for 5 consecutive days (chronic model) with 10-day follow-up saline administrations, showed significant motor dysfunction in the pole test due to reduced tyrosine hydroxylase (TH) protein levels in the brain on day 16 after MPTP/saline treatment. Daily coadministrations of MLX (10mg/kg/day; i.p.) and MPTP for the first 5 days and follow-up 10 days with MLX administrations alone (MPTP/MLX treatment) significantly ameliorated MPTP-induced behavioral abnormalities in mice. Concomitant decreases of TH protein levels in the striatum and midbrain of MPTP/MLX-treated mice were not only significantly (p<0.01 and p<0.05, respectively) ameliorated but phosphorylated Akt (pAkt473) expression in the midbrain was also significantly (p<0.01) increased in the midbrain when compared with MPTP/saline-treated mice. These results suggest that MLX, an oxicam NSAID, attenuated dopaminergic neuronal death in the experimental MPTP-PD model by maintenance of the Akt-signaling. Oxicam NSAIDs may serve as potential drugs for PD treatment via a novel mechanism of action.

Oxicam structure in non-steroidal anti-inflammatory drugs is essential to exhibit Akt-mediated neuroprotection against 1-methyl-4-phenyl pyridinium-induced cytotoxicity.

In the treatment of Parkinson's disease, potent disease-modifying drugs are still needed to halt progressive dopaminergic neurodegeneration. We have previously shown that meloxicam, an oxicam non-steroidal anti-inflammatory drug (NSAID), elicits a potent neuroprotective effect against 1-methyl-4-phenyl pyridinium (MPP(+))-induced toxicity in human dopaminergic SH-SY5Y neuroblastoma cells. This cyclooxygenase-independent neuroprotection of meloxicam is mediated via the phosphatidylinositol 3-kinase (PI3K)/Akt pathway; however, the specific chemical structure involved in inducing neuroprotection remains unresolved. In this study, we therefore investigated the structure-specific for eliciting the neuroprotective effect by examining a series of NSAIDs against MPP(+) toxicity in SH-SY5Y cells. Three oxicam-bearing NSAIDs showed potent neuroprotective effects, although none of the other 10 oxicam-nonbearing NSAIDs (3 salicylates, 6 coxibs and 1 polyphenol) or 3 piroxicam analogs (including ampiroxicam, a precursor of piroxicam) exerted any neuroprotection. Tenoxicam and piroxicam prevented MPP(+)-induced reduction of phosphorylated Akt levels in cells: a protective mechanism similar to that of meloxicam. Therefore, the oxicam structure was likely to be responsible for exhibiting the neuroprotection by sustaining survival-signaling in dopaminergic cells. The present results raise the possibility that the oxicam-bearing NSAIDs may serve as potential therapeutic drugs to retard or terminate progression of Parkinson's disease via a novel mechanism.

Analysis of the HLA and non-HLA susceptibility loci in Japanese type 1 diabetes.

BACKGROUND: We previously reported the associations of human leukocyte antigen (HLA) (DRB1 and DQB1), INS, CTLA4, IL2RA, ERBB3 and CLEC16A with Japanese type 1 diabetes (T1D). In this study, we jointly analysed these loci in addition to IFIH1 and IL7R. METHODS: A maximum of 790 T1D patients and 953 control subjects were analysed. HLA was determined by sequencing-based typing. Seven non-HLA single nucleotide polymorphisms were genotyped using TaqMan assay. RESULTS: HLA DRB1*0405, DRB1*0901 and DRB1*0802-DQB1*0302 haplotypes were positively associated with T1D, while the DRB1*15 haplotypes were negatively associated. Non-HLA single nucleotide polymorphisms, INS, IL2RA, ERBB3, CLEC16A and IL7R were associated with T1D. By a prediction model using the HLA loci alone (HLA model) or the non-HLA loci alone (non-HLA model), it was revealed that the cumulative effect of the non-HLA model was much weaker than that of the HLA model (average increase in odds ratio: 1.17 versus 3.14). Furthermore, the area under the receiver operating characteristic curve of the non-HLA model was also much smaller than that of the HLA model (0.65 versus 0.81, p<10(-11)). Finally, a patient-only analysis revealed the susceptible HLA haplotypes and the risk allele of INS to be negatively associated with slower onset of the disease. In addition, the DRB1*0901 haplotype and the risk alleles of ERBB3, CLEC16A and CTLA4 were positively associated with the co-occurrence of thyroid autoimmunity. CONCLUSIONS: Although several non-HLA susceptibility genes in Japanese were confirmed trans-racially and appear to contribute to the heterogeneity of the clinical phenotypes, the cumulative effect on the ability to predict the development of T1D was weak.

Meloxicam protects cell damage from 1-methyl-4-phenyl pyridinium toxicity via the phosphatidylinositol 3-kinase/Akt pathway in human dopaminergic neuroblastoma SH-SY5Y cells.

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by dopaminergic neuronal death in the substantia nigra pars compacta. There is growing interest in the effects of nonsteroidal antiinflammatory drugs (NSAIDs) against PD progression. In this study, we investigated the neuroprotective effect of NSAIDs on neuronal damage induced by 1-methyl-4-phenyl pyridinium (MPP(+)) in human dopaminergic SH-SY5Y neuroblastoma cells. Of the NSAIDs tested, only meloxicam indicated protective effect on MPP(+)-induced neurotoxicity in SH-SY5Y cells, although such an effect was not established with indomethacin, ibuprofen and cyclooxygenase (COX)-2 selective inhibitors (NS-398 and CAY-10404). The neuroprotective effect of meloxicam against MPP(+) toxicity was specific, as toxicities induced by other cytotoxic agents (such as rotenone, MG-132, tunicamycin and ethacrynic acid) were not attenuated by meloxicam. The neuroprotective effect of meloxicam on MPP(+)-induced apoptosis was abolished by a phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002, but not by a MEK inhibitor, PD98059. The Akt phosphorylation levels were predominantly suppressed 4h after MPP(+) incubation (i.e. when the cell toxicity was not apparently observed yet). Meloxicam completely prevented the Akt phosphorylation suppression caused by MPP(+) exposure, while meloxicam per se did not promote the Akt phosphorylation. These results strongly suggest that the neuroprotective effect of meloxicam is mediated by the maintenance of cell survival signaling in the PI3K/Akt pathway, but not by COX-2 inhibition. Therefore, meloxicam may have therapeutic potential in preventing development or delaying progress of PD.

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.

Functional VEGF C-634G polymorphism is associated with development of diabetic macular edema and correlated with macular retinal thickness in type 2 diabetes.

Since vascular endothelial growth factor (VEGF) has a strong effect on induction of vascular permeability, VEGF is an attractive candidate gene for development of diabetic macular edema (ME). Among the 378 patients with type 2 diabetes studied, 203 patients had no retinopathy, 93 had non-proliferative diabetic retinopathy (NPDR), and 82 had proliferative diabetic retinopathy (PDR). ME was present in 16 patients with NPDR and 47 patients with PDR. We genotyped three VEGF polymorphisms: C-2,578A, G-1,154A, and C-634G. Genotype and allele distribution of C-634G, but not C-2,578A or G-1,154A, were significantly different between patients with and without diabetic retinopathy. Logistic regression analysis revealed that the C-634G genotype was a risk factor for DR (p = 0.002), and furthermore for ME (p = 0.047), independently from severity of DR, with the -634C allele increasing the risk. Macular thickness measured by optical coherence tomography was correlated with the C-634G genotype, with the trend increasing with the presence of more -634C alleles (p = 0.006). Stepwise regression analysis showed that duration of diabetes and presence of the C-634G genotype were independent predictors of macular thickness. In addition, basic transcriptional activity levels associated with the -634C allele were greater compared to those seen with the -634G allele in human glioma and lymphoblastic T-lymphocyte cells. These results demonstrate that the VEGF C-634G polymorphism is a genetic risk factor for ME as well as DR.

Pro12Ala substitution in peroxisome proliferator-activated receptor gamma 2 is associated with low adiponectin concentrations in young Japanese men.

Peroxisome proliferator-activated receptor gamma (PPAR gamma) has been shown to play an important role in adipocyte differentiation. A Pro12Ala substitution in PPAR gamma 2 has been reported to decrease receptor activity in vitro and to be associated with a decreased risk of type 2 diabetes in the general population. Recently, a PPAR response element (PPRE) was identified in the adiponectin promoter, suggesting that decreased PPAR gamma activity may lead to lower adiponectin levels. In the present study, serum adiponectin concentrations and the PPAR gamma Pro12Ala polymorphism were analyzed to determine whether this polymorphism is associated with lower serum adiponectin concentrations in young healthy Japanese subjects. Serum adiponectin concentrations were significantly lower in men with than in those without the Ala12 allele, whereas body mass index (BMI), homeostasis model assessment (HOMA)-beta, HOMA-IR, the insulin sensitivity index during oral glucose tolerance test (ISI [composite]), and serum leptin did not differ significantly between subjects with and without the Ala12 allele. Stepwise regression demonstrated BMI and the Ala12 allele to be independent predictors of serum adiponectin concentrations in men. In conclusion, the Pro12Ala substitution in PPAR gamma 2 may reduce serum adiponectin concentrations in young Japanese men.

Endothelial nitric oxide synthase gene is associated with diabetic macular edema in type 2 diabetes.

OBJECTIVE: We examined the endothelial nitric oxide (eNOS) gene polymorphisms to assess its possible association with diabetic retinopathy and macular edema. RESEARCH DESIGN AND METHODS: A total of 226 patients with type 2 diabetes and 186 healthy subjects were studied. Type 2 diabetic patients consisted of 110 patients without retinopathy, 46 patients with nonproliferative diabetic retinopathy, and 71 patients with proliferative diabetic retinopathy. Diabetic macular edema was present in 48 patients. Three polymorphisms of the eNOS gene were determined: T-786C in the promoter region, 27-bp repeat in intron 4, and Glu298Asp in exon 7. RESULTS: Close linkage disequilibrium was observed between the T-786C polymorphism and the 27-bp repeat, as has been previously reported, but Glu298Asp was not in linkage disequilibrium with the other two polymorphisms. The eNOS gene polymorphisms were not significantly associated with the presence of retinopathy or with retinopathy severity or type 2 diabetes itself. However, by both association study and multiple logistic regression analysis, the T-786C and 27-bp repeat polymorphisms were significantly associated with a risk of developing macular edema with the -786C allele and the "a" allele increasing the risk. CONCLUSIONS: The present study suggests that the eNOS gene is a novel genetic risk factor for diabetic macular edema. The eNOS gene polymorphisms may contribute to the development of macular edema by impairing basal eNOS expression and resulting in the breakdown of the blood-retina barrier.

A common polymorphism in the 5'-untranslated region of the VEGF gene is associated with diabetic retinopathy in type 2 diabetes.

Vascular endothelial growth factor (VEGF), a major mediator of vascular permeability and angiogenesis, may play a pivotal role in mediating the development and progression of diabetic retinopathy. In the present study, we examined the genetic variations of the VEGF gene to assess its possible relation to diabetic retinopathy in type 2 diabetic patients. Among seven common polymorphisms in the promoter region, 5'-untranslated region (UTR) and 3'UTR of the VEGF gene, genotype distribution of the C(-634)G polymorphism differed significantly (P = 0.011) between patients with (n = 150) and without (n = 118) retinopathy, and the C allele was significantly increased in patients with retinopathy compared with those without retinopathy (P = 0.0037). The odds ratio (OR) for the CC genotype of C(-634)G to the GG genotype was 3.20 (95% CI 1.45-7.05, P = 0.0046). The -634C allele was significantly increased in patients with nonproliferative diabetic retinopathy (non-PDR) (P = 0.0026) and was insignificantly increased in patients with proliferative diabetic retinopathy (PDR) (P = 0.081) compared with patients without retinopathy, although frequencies of the allele did not differ significantly between the non-PDR and PDR groups. Logistic regression analysis revealed that the C(-634)G polymorphism was strongly associated with an increased risk of retinopathy (P = 0.0018). Furthermore, VEGF serum levels were significantly higher in healthy subjects with the CC genotype of the C(-634)G polymorphism than in those with the other genotypes. These data suggest that the C(-634)G polymorphism in the 5'UTR of the VEGF gene is a novel genetic risk factor for diabetic retinopathy.