Yasunori Sera

Comparison of serum concentrations of soluble adhesion molecules in diabetic microangiopathy and macroangiopathy

Aims To clarify the correlation between serum concentrations of soluble adhesion molecules and diabetic microangiopathy or macroangiopathy in patients with Type 2 diabetes.

Serum concentrations of soluble adhesion molecules are related to degree of hyperglycemia and insulin resistance in patients with type 2 diabetes mellitus

To investigate the relationships between serum concentrations of soluble adhesion molecules and hyperglycemia, insulin resistance, or other conventional risk factors in type 2 diabetes, we measured soluble intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1), E-selectin (sE-selectin), insulin sensitivity, and conventional risk factors in 150 Japanese type 2 diabetic patients without apparent diabetic macroangiopathy. High serum concentrations of sVCAM-1 and sE-selectin were observed in patients with type 2 diabetes. Serum concentrations of soluble adhesion molecules were not significantly influenced by sex, hypertension, dyslipidemia, or microangiopathy. Spearman correlation showed that sVCAM-1 concentrations correlated significantly with fasting plasma glucose (FPG), fasting C-peptide, and insulin sensitivity [K index of the insulin tolerance test (K(ITT))] (rho=0.19,0.23, and -0.23, respectively). Soluble E-selectin concentrations correlated significantly with body mass index (BMI), FPG, fasting C-peptide, insulin sensitivity, and triglyceride (rho=0.33,0.42,0.26,-0.48, and 0.29, respectively). Multiple regression analysis showed that FPG, fasting C-peptide, and total cholesterol were independent factors that correlated with sVCAM-1 levels. BMI, FPG, and insulin sensitivity were independent factors that correlated with sE-selectin levels. Serum concentrations of sE-selectin significantly increased associated with clustering of conventional risk factors those obesity, hypertension, dyslipidemia, and current smoking (P<0.01). Thus, sVCAM-1 and sE-selectin levels are related to both hyperglycemia and insulin resistance. Soluble E-selectin levels may be related to obesity, hyperglycemia, and insulin resistance and may reflect the presence of a multiple risk factor clustering syndrome.

Inflammation and insulin resistance are independently related to all-cause of death and cardiovascular events in Japanese patients with type 2 diabetes mellitus.

Insulin resistance (IR)/hyperinsulinemia and low-grade inflammation (high-sensitivity C-reactive protein [hs-CRP]) can predict cardiovascular disease. However, because IR and inflammation (IF) have not been evaluated simultaneously, it is not known whether IR and IF are independently related to cardiovascular disease. Furthermore, the combined effect of IR and IF on the prediction of cardiovascular disease is presently unknown. Thus, we measured insulin sensitivity (K index of the insulin tolerance test; KITT) and hs-CRP in 350 Japanese patients with type 2 diabetes, and followed them for 1-7 years (mean, 4.5 years). During the follow-up, 33 patients died and 53 patients developed non-fatal coronary artery disease or stroke (endpoint). Age, systolic blood pressure, current smoking, past history of cardiovascular disease, KITT, and hs-CRP independently and significantly correlated with endpoint. One-S.D. difference was associated with a significant increase of relative risk in KITT (1.45; 95% CI 1.09-1.91) and hs-CRP (1.30; 1.04-1.67). When patients were subdivided to tertile, the relative risk in the highest tertile of KITT was 1.76 (95% CI 1.01-3.11) and hs-CRP was 2.00 (1.03-3.85) compared with the patients with lowest tertile. The relative risk in the highest tertile of both KITT and hs-CRP was 5.32 (1.18-24.0) compared with the lowest tertile of both values. In conclusion, low-grade IF and IR are independently related to all-cause of death and cardiovascular disease in Japanese patients with type 2 diabetes. Coexistence of low-grade IF and IR amplify this effect.

CTLA4 gene polymorphism correlates with the mode of onset and presence of ICA512 Ab in Japanese Type 1 diabetes

Recently, the association of CTLA4 gene polymorphism with type 1 diabetes and AITD has been reported in several populations. CTLA4 was originally reported to regulate T-cell activity and T-B cognate interaction. To investigate the role of CTLA4 in autoimmune diseases, we examined the correlation between CTLA4 gene polymorphism and the clinical characteristics of Japanese patients with type 1 diabetes, including the mode of onset of diabetes and presence of islet-specific autoantibodies (GAD, ICA 512 Ab) in the serum. We studied 111 patients with type 1 diabetes and 445 normal subjects. CTLA4 exon 1 position 49 (A/G: codon 17: Thr/Ala) polymorphism was defined, employing PCR-RFLP. Sixty-three (57%) patients had AITD. The allele frequencies of G and A in both 111 patients (G: 65%; A: 35%) and 63 patients (G: 62%; A: 38%) were not significantly different from the control subjects (G: 63%; A: 37%). Serum samples of 69 patients were obtained within a year after onset and used for pancreas specific autoantibodies analysis. These samples were also used for further analysis between CTLA4 gene polymorphism and clinical characteristics. The allele frequencies of G and A in patients who presented with diabetic ketoacidosis (DK+) (G: 75%; A: 25%) were significantly different from those in DK- patients (G: 50%, A: 50%, P = 0.003). Allele and genotype analyses showed significant differences between DK+ patients and control subjects (P = 0.014, P = 0.046, respectively). Allele frequencies of G and A were not significant between patients who were positive and negative for GAD Ab, but significant for ICA 512 Ab (G: 83%, A:17% versus G: 59%, A: 41%: positive patients versus negative patients, P = 0.004). Our results showed a significant correlation between CTLA4 gene polymorphism and ICA 512 Ab. Our results also indicated that CTLA4 gene polymorphism is associated with the onset mode of Japanese type 1 diabetes and the presence of ICA512 Ab. Further analysis of this polymorphism is necessary to fully understand the pathogenesis and progression of type 1 diabetes.

Antibodies to GAD in Japanese patients classified as Type 2 diabetes at diagnosis. High titre of GAD Ab is a predictive marker for early insulin treatment—report of west Japan (Kyushu, Yamaguchi, Osaka) study for GAD Ab(+) diabetes

Aim We evaluated the prevalence of GAD Ab in Japanese Type 2 diabetic patients treated with oral hypoglycaemic agents (OHA) and/or diet and followed GAD Ab(+) patients to assess the usefulness of GAD Ab as a marker for future insulin treatment prospectively.

Anti-insulin receptor autoantibodies in a patient with type B insulin resistance and fasting hypoglycemia.

Abstract We studied a patient with systemic lupus erythematosus and type B insulin resistance who showed almost complete normalization of postprandial plasma glucose in 3 months and a transient coccurrence of fasting hypoglycemia from day 35 (i. e. the 35th day of hospitalization) to day 77. To determine the clinical relevance of the biological ability of anti-insulin receptor antibodies (anti-IRAb), we made multiple preparations of the patients dialyzed serum and IgG. Dialyzed serum prepared on day 1 showed 95% inhibition of insulin binding. The binding inhibition was, however, decreased parallel to the normalization of insulin sensitivity. For 2DG uptake, 6.2 μM IgG purified on 3 different days (day 7, 35 and 78, designated IgG-NOV, -JAN, and -FEB, respectively) stimulated 2DG uptake into CHO-hIR at 3.4-, 3.1-, and 1.5-fold, respectively. Phosphotyrosine immunoblotting revealed that apparent insulin receptor autophosphorylation was visible only with IgG-NOV, not with the IgG-JAN or -FEB. Mutation of tyrosine-960 or lysine-1018 of the insulin receptor failed to transduce the IgGs stimulatory effect. IgG-NOV was not able to stimulate the autophosphorylation of the human IGF-I receptor. In the present study, the insulin binding inhibitory activities of the dialyzed sera prepared at different time points were shown to be altered parallel to insulin sensitivity in vivo. Stimulatory activities of the patients IgG were, however, discordant for the occurrence of fasting hypoglycemia observed in vivo. Other pathogenic factors or mechanisms in addition to the insulin-like action of the anti-IRAb may be also required to fully understant the development of fasting hypoglycemia in type B insulin resistance.

Insulin resistance and coronary risk factors in Japanese type 2 diabetic patients with definite coronary artery disease

Insulin resistance is known as an important risk factor for coronary artery disease (CAD). However, CAD-related mortality in Japanese type 2 diabetics is lower than in Caucasians. To investigate whether insulin resistance is related to CAD in Japanese type 2 diabetics, we measured insulin sensitivity and several coronary risk factors in Japanese patients with type 2 diabetes with and without CAD. Thirty-three patients with definite CAD and 33 age- and sex-matched patients without CAD (control) were studied. Insulin sensitivity was assessed by the K index of insulin tolerance test (KITT). Clinical characteristics, classical risk factors, lipoprotein (a), and insulin sensitivity were compared between the two groups. Patients with CAD had a significantly longer duration of diabetes (9.0 +/- 1.4 vs. 5.5 +/- 0.9 years, P < 0.05, respectively), were mostly hypertensive (69.7 vs. 39.4%, P < 0.05), and more likely to be treated with insulin (45.5 vs. 18.2%, P < 0.05) compared with the control. Concerning the metabolic parameters, patients with CAD had a significantly higher insulin resistance than control (2.40 +/- 0.15 vs. 3.23 +/- 0.17%/min, P < 0.01, respectively), higher triglyceride (1.39 +/- 0.10 vs. 1.05 +/- 0.05 mmol/l, P < 0.05), lower HDL cholesterol (1.05 +/- 0.05 vs. 1.28 +/- 0.06 mmol/l, P < 0.05), and higher lipoprotein (a) (27.5 +/- 4.3 vs. 17.4 +/- 2.0 mg/dl, P < 0.05). Multiple logistic regression analysis indicated that hypertension, insulin resistance, high lipoprotein (a) and triglyceride, and low HDL cholesterol were independently related to CAD. Our results suggest that insulin resistance per se is a significant risk factor for CAD in Japanese patients with type 2 diabetes.

No deterioration in insulin sensitivity, but impairment of both pancreatic β-cell function and glucose sensitivity, in Japanese women with former gestational diabetes mellitus

To identify the primary pathogenic factors involved in the development of Type 2 diabetes mellitus (DM), we studied Japanese women with former gestational diabetes mellitus (GDM) who are at risk for the later development of Type 2 DM. We used the minimal model analysis derived from frequently sampled intravenous glucose tolerance test (FSIGT). The subjects consisted of eight non‐obese women with a history of GDM and eight non‐obese normal women as control subjects. The 75 g oral glucose tolerance test (75 g OGTT) performed within 6 months of delivery confirmed that all the subjects with former GDM had a normal glucose tolerance. Insulin sensitivity (SI) derived from the minimal model analysis was not different between the two groups. Glucose effectiveness at zero insulin (GEZI), reflecting tissue glucose sensitivity, was significantly lower in former GDM patients than in control subjects (1.18 ± 0.34 vs 2.26 ± 0.29 × 10−2 min−1, p < 0.05). The early phase insulin secretion found in FSIGT was markedly reduced to 56 % of that observed in control subjects (1250 ± 187.4 vs 2223 ± 304.3 pmol l−1 min, p < 0.01). Our results indicate that in former GDM patients, who are Japanese and non‐obese, impairment of the acute insulin response to glucose and a decrease in tissue glucose sensitivity rather than insulin sensitivity are the primary pathogenic factors involved. Copyright

Distinct IA-2 autoantibody epitope recognition between childhood-onset and adult-onset type 1 diabetes.

Abstract: Different autoimmune mechanisms may be involved in childhood‐ and adult‐onset type 1 diabetes. Our aim was to explore the differences in IA‐2 autoantibody epitope recognition between childhood‐ and adult‐onset type 1 diabetes. Therefore, in vitro synthesized radiolabeled IA‐2ic (amino acid 601‐979), IA‐2JM (amino acid 557‐629), and IA‐2PTP (amino acid 630‐979) were used to analyze the IA‐2 autoantibody epitope specificities in 93 patients with new‐onset type 1 diabetes. Among 93 patients with type 1 diabetes the prevalences of autoantibodies to GAD, IA‐2ic, and insulin were 69.9%, 58.1%, and 45.2%, respectively. The prevalence of IA‐2ic autoantibodies in patients with childhood‐onset type 1 diabetes (aged ≤18 years, n= 60) was significantly higher than that in patients with adult‐onset diabetes (68.3 vs. 36.4%, P < 0.002). Ninety‐two percent of type 1 diabetic patients positive for IA‐2ic autoantibodies recognized the PTP domain of IA‐2, whereas 8% reacted with the JM region only. Among 60 patients with childhood‐onset type 1 diabetes, 2% recognized the JM region only, 48% bound the PTP domain of IA‐2 only, and 18% recognized both JM and PTP epitopes. Among 33 patients with adult‐onset diabetes, 9% recognized the IA‐2JM only, 18% bound the IA‐2PTP only, and 9% recognized both the IA‐2JM and the IA‐2PTP. IA‐2PTP autoantibodies were prevalent in patients with childhood‐onset type 1 diabetes. By contrast, the proportion of patients with the IA‐2JM autoantibody only in type 1 diabetes who were positive for IA‐2ic autoantibodies was significantly higher in adult‐onset than in childhood‐onset diabetes (P < 0.05). These results demonstrate that autoantibody recognition of the IA‐2 epitope is distinct in childhood‐onset and adult‐onset type 1 diabetes.

HEPATOCYTE NUCLEAR FACTOR-1α INHIBITS INSULIN PROMOTER FACTOR 1-DEPENDENT TRANSACTIVATION OF THE HUMAN INSULIN GENE

To investigate the regulational interaction of hepatocyte nuclear factor-1α (HNF-1α) and insulin promoter factor 1 (IPF1) on insulin gene expression, either or both of the expression vectors carrying each transcription factor were transiently transfected into HeLa cells, RINm5F cells and MIN6 cells together with the luciferase reporter construct driven by a human preproinsulin gene promoter (−1998 to +237) designated as pINS-1998/luc. IPF1-transfection into HeLa cells strongly stimulated the luciferase activity to 725 fold that of the basal level. In contrast, HNF-1α-transfection resulted in only a 6.7 fold increase. In co-transfection experiments, increasing the amount of HNF-1α resulted in an 84.5% and 74.4% decrease in IPF1-stimulated luciferase activity in HeLa and RINm5F cells, respectively. Deletion constructs designated as pINS-248/luc, pINS-213/luc and pINS-185/luc were transfected into RINm5F cells to determine the role of the A3 element and its 5′ flanking sequence in the inhibitory effect of HNF-1α. The results showed that the inhibiting effects of HNF-1α with pINS-213/luc and pINS-185/luc were significantly smaller than those with both pINS-1998/luc and pINS-248/luc. Transfection into MIN6 cells with pINS-1998/luc in the absence of IPF1 resulted in constitutional transactivation of the insulin gene, and this transactivation was abolished by the co-transfection with HNF-1α. The present data indicate that IPF1 rather than HNF-1α predominantly transactivates the insulin gene, and that HNF-1α inhibits IPF1-dependent insulin gene transactivation mediated through the 5′ flanking sequence of the A3 element. It is suggested that HNF-1α may be involved in insulin gene expression as a negative regulator.