Jun-ichiro Miyagawa

Production of adiponectin, an anti-inflammatory protein, in mesenteric adipose tissue in Crohn’s disease

Background and aims: A characteristic feature of Crohn’s disease (CD) is mesenteric adipose tissue hypertrophy. Mesenteric adipocytes or specific proteins secreted by them may play a role in the pathogenesis of CD. We recently identified adiponectin as an adipocyte specific protein with anti-inflammatory properties. Here we report on expression of adiponectin in mesenteric adipose tissue of CD patients. Methods and results: Mesenteric adipose tissue specimens were obtained from patients with CD (n = 22), ulcerative colitis (UC) (n = 8) and, for controls, colon carcinoma patients (n = 28) who underwent intestinal resection. Adiponectin concentrations were determined by enzyme linked immunosorbent assay, and adiponectin mRNA levels were determined by real time quantitative reverse transcription-polymerase chain reaction. Tissue concentrations and release of adiponectin were significantly increased in hypertrophied mesenteric adipose tissue of CD patients compared with normal mesenteric adipose tissue of CD patients (p = 0.002, p = 0.040, respectively), UC patients (p = 0.002, p = 0.003), and controls (p<0.0001, p<0.0001). Adiponectin mRNA levels were significantly higher in hypertrophied mesenteric adipose tissue of CD patients than in paired normal mesenteric adipose tissue from the same subjects (p = 0.024). Adiponectin concentrations in hypertrophied mesenteric adipose tissue of CD patients with an internal fistula were significantly lower than those of CD patients without an internal fistula (p = 0.003). Conclusions: Our results suggest that adipocytes in hypertrophied mesenteric adipose tissue produce and secrete significant amounts of adiponectin, which could be involved in the regulation of intestinal inflammation associated with CD.

Macrophages and dendritic cells infiltrating islets with or without beta cells produce tumour necrosis factor-α in patients with recent-onset type 1 diabetes

Aims/hypothesisType 1A diabetes results from autoimmune destruction of pancreatic beta cells. We examined the involvement of TNF-α and IL-1β, as well as of T cells, macrophages and dendritic cells, in the destruction of beta cells in patients with recent-onset type 1 diabetes.Materials and methodsWe obtained pancreatic biopsy specimens from six patients with recent-onset type 1 diabetes and analysed these by immunohistochemistry.ResultsT cell infiltration was less common in islets without beta cells (12.5 [0–33.3]%) than in those with beta cells (46.0 [17.4–83.3]%), while macrophages and dendritic cells showed a similar extent of infiltration into islets both with or without beta cells. TNF-α was detected in 25.0 (4.3–46.9)% of macrophages and 11.8 (0–40.0)% of dendritic cells infiltrating the islets in samples from each patient, but not at all in T cells. IL-1β was detected in 1.8 (0–11.3)% of T cells infiltrating the islets with beta cells, while it was found in 19.2 (0–35.3)% of macrophages or 10.7 (0–31.3)% of dendritic cells infiltrating the islets in samples from each patient (all values median [range]).Conclusions/interpretationMacrophages and dendritic cells infiltrate the islets and produce inflammatory cytokines (TNF-α and IL-1β) during the development of type 1A diabetes.

The tetraspanin CD9 modulates epidermal growth factor receptor signaling in cancer cells

CD9 is a member of the tetraspanins, and has been shown to be involved in a variety of cellular activities such as migration, proliferation, and adhesion. In addition, it has been known that CD9 can associate with other proteins. Here we demonstrated the physical and functional association of CD9 with epidermal growth factor receptor (EGFR) on MKN‐28 cells. Double‐immunofluorescent staining and immunoprecipitation demonstrated the complex formation of CD9‐EGFR and CD9‐β1 integrin, and that both complexes are colocalized on the cell surface especially at the cell–cell contact site. Anti‐CD9 monoclonal antibody ALB6 induced a dotted or patch‐like aggregation pattern of both CD9‐EGFR and CD9‐β1 integrin. The internalization of EGFR after EGF‐stimulation was significantly enhanced by the treatment with ALB6. CD9 can associate with EGFR in hepatocellular carcinoma cells (HepG2/CD9) and Chinese hamster ovary cancer cells (CHO‐HER/CD9), which were transfected with pTJ/human EGFR/CD9. Furthermore expression of CD9 specifically attenuated EGFR signaling in CHO‐HER/CD9 cells through the down regulation of surface expression of EGFR. These results suggest that CD9 might have an important role that attenuates EGFR signaling. Therefore, CD9 not only associates EGFR but also a new regulator, which may affect EGF‐induced signaling in cancer cells. J. Cell. Physiol. 216: 135–143, 2008.

New strategy for the treatment of type 2 diabetes mellitus with incretin-based therapy

Incretin-based therapy was first made available for the treatment of type 2 diabetes mellitus (T2DM) in the US in 2006 and in Japan in 2009. Four DPP-4 inhibitors and two GLP-1 analog/receptor agonists are currently available. The effects of incretin-based therapy are assumed to be exerted mainly through the hormonal and neuronal actions of one of the incretins, GLP-1, which is secreted from L cells localized in the small intestine. The benefits of this therapy over conventional sulfonylureas or insulin injections, such as fewer hypoglycemic events and reduced body weight gain, derive from the glucose-dependent insulinotropic effect. The protective effects of this therapy on vulnerable pancreatic β-cells and against micro/macroangiopathy in T2DM are also most welcome. Indications and/or contraindications for incretin-based therapy should be clarified by prospectively studying the experiences of Japanese T2DM patients undergoing this therapy in the clinical setting.

Evaluation of a Minimally Invasive System for Measuring Glucose Area under the Curve during Oral Glucose Tolerance Tests: Usefulness of Sweat Monitoring for Precise Measurement:

Aims: We developed a system for measuring glucose area under the curve (AUC) using minimally invasive interstitial fluid extraction technology (MIET). Sweat contamination during interstitial fluid glucose (IG) extraction affects the accuracy of glucose AUC measurement, because this technology uses extracted sodium ion levels as an internal standard. Therefore, we developed a sweat monitoring patch to reduce this effect and investigated its efficacy in volunteers undergoing oral glucose tolerance tests (OGTTs). Materials and Methods: Fifty diabetes mellitus inpatients and 10 healthy subjects undergoing the 75 g OGTT were included. Two sites on the forearm were pretreated with microneedle arrays, then hydrogels for interstitial fluid extraction were placed on the treated sites. Simultaneously, hydrogels for sweat monitoring were placed on untreated sites near the treated sites. Plasma glucose (PG) levels were measured every 30 min for 2 h to calculate reference AUC values. Using MIET, IG AUC was calculated from extracted glucose and sodium ion levels after attachment of the hydrogel for 2 h. Results: Good correlation between IG AUC measurements using MIET and reference AUCs measured using PG levels was confirmed over a wide AUC range (202–610 mg/h/dl) after correction for the sweat-induced error detected by the hydrogel patches on the nonpretreated skin. Strong correlation between IG AUC and peak glucose levels indicates that glucose spikes can be easily detected by this system. Conclusion: We confirmed the effectiveness of a sweat monitoring patch for precise AUC measurement using MIET. This novel, easy-to-use system has potential for glucose excursion evaluation in daily clinical practice.

Effects of the naturally-occurring disaccharides, palatinose and sucrose, on incretin secretion in healthy non-obese subjects.

Incretins might play some pathophysiological role in glucose metabolism in diabetes and obesity; it is not clear whether or not the amount and the pattern of incretin secretion vary with different types of sugars. To evaluate the effect of two types of disaccharides on glucose metabolism and the kinetics of incretin secretion, plasma levels were measured after palatinose or sucrose ingestion in non‐obese healthy participants.

Asymmetric dimethylarginine, a biomarker of cardiovascular complications in diabetes mellitus

Cardiovascular (CV) complications are an essential causal element of prospect in diabetes mellitus (DM), with carotid atherosclerosis being a common risk factor for prospective crisis of coronary artery diseases and/or cerebral infarction in DM subjects. From another point of view, asymmetric dimethylarginine (ADMA) has been established as an inhibitor of endogenous nitric oxide synthesis and the relationship between ADMA and arteriosclerosis has been reported. In our study with 87 type 2 DM (T2DM) patients, we have examined whether ADMA and other CV risk factors are the useful predictors of DMCV complications. After the measurement of the respective CV risk factors, we have followed the enrolled T2DM patients for 5 years. We have finally analyzed 77 patients. DMCV complications developed in 15 cases newly within 5 years, and 4 cases recurred. The concentrations of ADMA in plasma were markedly more elevated in 19 DM patients with CV complications than in 58 DM patients without CV complications. Urinary albumin (U-Alb), mean intimal-medial thickness (IMT) and ankle brachial index (ABI) were also higher in patients with CV complications. Multiple regression analyses showed that U-Alb had an influence on the high level of ADMA (standardized β = 6.59, P = 0.00014) independently of age, systolic BP, fibrinogen, mean IMT, plaque score, and ABI. The review indicates what is presently known regarding plasma ADMA that might be a new and meaningful biomarker of CV complications in DM subjects.

Effects of gliclazide on platelet aggregation and the plasminogen activator inhibitor type 1 level in patients with type 2 diabetes mellitus

Vascular complications are a common factor determining morbidity and mortality of diabetic patients. In vitro studies have revealed that gliclazide has antiplatelet activities. To clinically assess this action, we measured the effects of gliclazide on platelet activities and abnormal fibrinolysis in patients with type 2 diabetes mellitus. We studied 14 patients aged 38 to 72 years (9 men and 5 women) with type 2 diabetes mellitus who have been treated with glibenclamide in our hospital for more than 6 months. We switched from glibenclamide to gliclazide using the average ratio of the respective doses, 2.5 vs 40 mg. We titrated the dose of gliclazide to keep the glycemic control at the same level as the previous (glibenclamide) treatment. We measured 10 micromol/L serotonin-induced or 0.5 micromol/L adenosine diphosphate (ADP)-induced platelet aggregate formation by particle counting using light scattering at baseline and up to 6 months after the switch. After switching to gliclazide, platelet aggregate formation induced by serotonin was significantly reduced (P < .05, compared with the levels observed after glibenclamide treatment). The body mass index, fasting plasma glucose, immunoreactive insulin, homeostasis model assessment of insulin resistance, hemoglobin A(1c) (HbA(1c)), total cholesterol, triglycerides, high-density lipoprotein cholesterol, prothrombin time, activated partial thromboplastin time, fibrinogen, thrombin-antithrombin III complex, plasmin-alpha2-plasmin inhibitor complex, and plasma plasminogen activator inhibitor type 1 (PAI-1) were not changed. In the group with improved HbA(1c) (n = 5), ADP-induced platelet aggregate formation and plasma PAI-1 level were significantly reduced (P < .05, compared with the group with aggravated HbA(1c), n = 9). Multiple regression analysis showed that percentage change of ADP-induced platelet aggregate formation (standardized beta = 0.540, P < .05) was independently associated with percentage change of plasma PAI-1 level in addition to percentage change of HbA(1c) (standardized beta = 0.657, P < .05) (R = 0.939, P < .05) after switching to gliclazide. The other independent variants, like the final dose of gliclazide, homeostasis model assessment of insulin resistance, percentage change of prothrombin time, activated partial thromboplastin time, and total cholesterol, were not significantly associated with the percentage change of plasma PAI-1 level. These results indicate that gliclazide inhibits platelet aggregation via the serotonin pathway, independently of the metabolic control per se. Furthermore, in the patients with improved glycemic control, gliclazide could inhibit ADP-induced platelet aggregation and reduce PAI-I level. Taken together, the results show that gliclazide may be more useful for the prevention of diabetic vascular complications than glibenclamide.

Estimation of HbA1c response to sitagliptin by change in glycated albumin level for 2 weeks

Aims/Introduction:  Since glycated albumin (GA) reflects shorter‐term (about 2 weeks) control of plasma glucose levels compared with HbA1c, GA is thought to be a useful glycemic control indicator for the early period following commencement of the treatment of diabetes. In this study, we attempted to estimate HbA1c using the change in GA level before and after the first 2 weeks (ΔGA2w) of administration of sitagliptin, a dipeptidyl peptidase‐4 (DPP‐4) inhibitor.

Response of incretins (GIP and GLP-1) to an oral glucose load in female and male subjects with normal glucose tolerance

The aim of this study was to analyze the blood glucose profile and the response of incretins in healthy young subjects by the 75 g oral glucose tolerance test (OGTT). We first reported that plasma glucose and GIP levels were higher in males during the early phase of the OGTT.