Hiroko Abe

Gut Dysbiosis and Detection of “Live Gut Bacteria” in Blood of Japanese Patients With Type 2 Diabetes

OBJECTIVE Mounting evidence indicates that the gut microbiota are an important modifier of obesity and diabetes. However, so far there is no information on gut microbiota and “live gut bacteria” in the systemic circulation of Japanese patients with type 2 diabetes. RESEARCH DESIGN AND METHODS Using a sensitive reverse transcription–quantitative PCR (RT-qPCR) method, we determined the composition of fecal gut microbiota in 50 Japanese patients with type 2 diabetes and 50 control subjects, and its association with various clinical parameters, including inflammatory markers. We also analyzed the presence of gut bacteria in blood samples. RESULTS The counts of the Clostridium coccoides group, Atopobium cluster, and Prevotella (obligate anaerobes) were significantly lower (P < 0.05), while the counts of total Lactobacillus (facultative anaerobes) were significantly higher (P < 0.05) in fecal samples of diabetic patients than in those of control subjects. Especially, the counts of Lactobacillus reuteri and Lactobacillus plantarum subgroups were significantly higher (P < 0.05). Gut bacteria were detected in blood at a significantly higher rate in diabetic patients than in control subjects (28% vs. 4%, P < 0.01), and most of these bacteria were Gram-positive. CONCLUSIONS This is the first report of gut dysbiosis in Japanese patients with type 2 diabetes as assessed by RT-qPCR. The high rate of gut bacteria in the circulation suggests translocation of bacteria from the gut to the bloodstream.

Human IAPP–induced pancreatic β cell toxicity and its regulation by autophagy

Pancreatic islets in patients with type 2 diabetes mellitus (T2DM) are characterized by loss of β cells and formation of amyloid deposits derived from islet amyloid polypeptide (IAPP). Here we demonstrated that treatment of INS-1 cells with human IAPP (hIAPP) enhances cell death, inhibits cytoproliferation, and increases autophagosome formation. Furthermore, inhibition of autophagy increased the vulnerability of β cells to the cytotoxic effects of hIAPP. Based on these in vitro findings, we examined the pathogenic role of hIAPP and its relation to autophagy in hIAPP-knockin mice. In animals fed a standard diet, hIAPP had no toxic effects on β cell function; however, hIAPP-knockin mice did not exhibit a high-fat-diet-induced compensatory increase in β cell mass, which was due to limited β cell proliferation and enhanced β cell apoptosis. Importantly, expression of hIAPP in mice with a β cell-specific autophagy defect resulted in substantial deterioration of glucose tolerance and dispersed cytoplasmic expression of p62-associated toxic oligomers, which were otherwise sequestrated within p62-positive inclusions. Together, our results indicate that increased insulin resistance in combination with reduced autophagy may enhance the toxic potential of hIAPP and enhance β cell dysfunction and progression of T2DM.

Free fatty acids stimulate autophagy in pancreatic β-cells via JNK pathway

Recent studies have suggested that free fatty acids stimulate autophagy of pancreatic beta cells. The aim of this study was to verify the free fatty acids (FFA)-induced autophagy and investigate its molecular mechanism. As reported previously, palmitate strongly enhanced the conversion of light chain (LC)3-I to LC3-II, a marker of activation of autophagy in INS-1 beta cells. Palmitate-induced conversion of LC3-I to LC3-II was also observed in neuron-, muscle-, and liver-derived cells. In addition, palmitate induced the formation of typical autophagosomes and autolysosomes and enhanced the degradation rate of long-lived proteins. These results confirmed that palmitate activates autophagic flux in most of the cells. While FFAs reportedly activate several signal transduction pathways in beta cells, palmitate-induced autophagy was blocked by a JNK inhibitor. Although enhanced oxidative stress and endoplasmic reticulum (ER) stress are suspected to mediate FFA-induced activation of JNK1, the induction of autophagy was not associated with changes in molecular markers related to oxidative and endoplasmic reticulum stresses. On the other hand, phosphorylation of double stranded RNA-dependent protein kinase (PKR) paralleled JNK1 activation. Considered together, our study suggested that FFA stimulated functional autophagy possibly through the PKR-JNK1 pathway independent of ER or oxidative stress.

Exendin-4 Improves β-Cell Function in Autophagy-Deficient β-Cells

Autophagy is cellular machinery for maintenance of β-cell function and mass. The implication of autophagy failure in β-cells on the pathophysiology of type 2 diabetes and its relation to the effect of treatment of diabetes remains elusive. Here, we found increased expression of p62 in islets of db/db mice and patients with type 2 diabetes mellitus. Treatment with exendin-4, a glucagon like peptide-1 receptor agonist, improved glucose tolerance in db/db mice without significant changes in p62 expression in β-cells. Also in β-cell-specific Atg7-deficient mice, exendin-4 efficiently improved blood glucose level and glucose tolerance mainly by enhanced insulin secretion. In addition, we found that exendin-4 reduced apoptotic cell death and increased proliferating cells in the Atg7-deficient islets, and that exendin-4 counteracted thapsigargin-induced cell death of isolated islets augmented by autophagy deficiency. Our results suggest the potential involvement of reduced autophagy in β-cell dysfunction in type 2 diabetes. Without altering the autophagic state in β-cells, exendin-4 improves glucose tolerance associated with autophagy deficiency in β-cells. This is mainly achieved through augmentation of insulin secretion. In addition, exendin-4 prevents apoptosis and increases the proliferation of β-cells associated with autophagy deficiency, also without altering the autophagic machinery in β-cells.

Masked Hypertension, Endothelial Dysfunction, and Arterial Stiffness in Type 2 Diabetes Mellitus: A Pilot Study

BACKGROUNDnThe aim of this study was to assess the relationship between masked hypertension (MHT) and vascular damage in patients with type 2 diabetes.nnnMETHODSnThe study subjects were patients with type 2 diabetes who were normotensive based on blood pressure (BP) measurement in the clinic (n = 80) without antihypertensive drugs and free of retinopathy, macroalbuminuria, overt cardiovascular disease. Subjects underwent 24-h ambulatory blood pressure monitoring (ABPM), measurement of flow-mediated dilatation (FMD), and brachial-ankle pulse wave velocity (baPWV). Based on the results of ABPM, subjects with mean daytime systolic BP ≥135 and/or 85 mm Hg were defined as MHT and their clinical data were compared with those of normotensive patients (NT). The data were also compared with those of type 2 diabetic patients with hypertension (HT) as measured in the clinic (n = 32).nnnRESULTSnMHT was detected in 47.5% of the study subjects with normotension at clinic (n = 38). Impaired FMD (5.65 ± 2.00% for NT, 4.26 ± 1.88% for MHT, 3.90 ± 1.71% for HT, P < 0.001) and higher baPWV (1,514.2 ± 212.7 cm/s for NT, 1,749.9 ± 339.7 cm/s for MHT, and 1,768.6 ± 302.8 cm/s for HT, P < 0.001) were similarly noted in patients with MHT and HT compared with NT. Multivariate regression analysis indicated that daytime systolic BP measured by ABPM, the estimated duration of diabetes and serum triglycerides were significantly associated with FMD and daytime systolic BP measured by ABPM, not systolic BP at clinic, age, and HbA(1c) were significantly associated with baPWV.nnnCONCLUSIONSnGiven that patients with impaired FMD and higher baPWV are known to be at higher risk of cardiovascular disease, our data suggest that type 2 diabetic patients with MHT could be also at increased risk of cardiovascular disease.

Comparison of effects of pitavastatin and atorvastatin on glucose metabolism in type 2 diabetic patients with hypercholesterolemia

The distinct effects of different statins on glycemic control have not been fully evaluated. In this open‐label, prospective, cross‐over clinical trial, we compared the effects of pitavastatin and atorvastatin on glycemic control in type 2 diabetic patients with hypercholesterolemia.

Efficacy and safety of modified Yale insulin infusion protocol in Japanese diabetic patients after open-heart surgery

To our knowledge, there is currently no insulin infusion protocol for critically ill patients especially designed for Asian diabetics although many such protocols are used in Western countries. In this study, we modified the Yale insulin infusion protocol taking into consideration the characteristics of Japanese diabetics and hospital environment. We tested the modified protocol in 40 type 2 diabetic patients after elective open-heart surgery (MY group) comparing with 35 type 2 diabetic patients under empirical blood glucose control (EC group). Analyses of 1656 blood glucose measurements during insulin infusion revealed that percentage of samples that showed achievement of target blood glucose level (80-140 mg/dl) was higher under MY (78+/-15%, n=870) than EC (57+/-23%, n=786, p<0.0001). On the other hand, the percentage of samples in which blood glucose was less than 60 mg/dl was comparable in the two groups (MY: 0.5+/-5.9 per thousand, EC: 5.1+/-18.5 per thousand). None of the patients with hypoglycemia showed significant clinical adverse effects. In conclusion, our modified Yale insulin infusion protocol is effective and safe for tight blood glucose control in Japanese diabetic patients after open-heart surgery.

Therapeutic effectiveness of potassium iodine in drug-naïve patients with Graves' disease: a single-center experience.

AbstractnIodine is beneficial against Graves’ thyrotoxicosis, though its effects are short-lived. However, its long-term effectiveness as an initial therapy has not been fully elucidated. Here, we compared the effects of potassium iodine (KI) and methimazole (MMI) in Graves’ thyrotoxicosis and on thyrotropin receptor antibody (TRAb) levels. Between 2008 and 2011, 293 patients with untreated Graves’ disease visited the outpatient clinic of Juntendo University. Of these, 227 patients were treated with MMI and 30 treated with KI as the initial therapy. To compare the effects of KI and MMI, we identified patients with similar probabilities of receiving MMI or KI using propensity score (PS) analysis based on the observed clinical features. PS matching created 20 matched pairs of patients with Graves’ disease treated with MMI and KI. The baseline characteristics of post-matched patients treated with MMI were comparable to those treated with KI (FT3; 7.16xa0±xa02.30, 6.56xa0±xa01.85xa0pg/ml, FT4; 2.57xa0±xa00.79, 2.49xa0±xa00.70xa0ng/dl, respectively). The initial dose of MMI was 14.0xa0±xa08.2xa0mg/day and that of KI was 53.6xa0±xa011.7xa0mg/day. Three patients of the KI group did not respond to the monotherapy, requiring the inclusion of antithyroid drugs. One patient on MMI developed moderate skin eruption, but continued the treatment. Patients who continued the initial treatment showed significant and comparable reductions in FT4, FT3 and TRAb by MMI as well as by KI at the end of 12-month treatment. Although patients were limited to mild untreated Graves’ disease thyrotoxicosis, KI offers a possible alternative initial treatment for this condition.

Effect of maternal high-fat diet on pancreatic beta cells of the offspring

Whereas ample evidence suggests that maternal malnutrition reduces pancreatic beta-cell function, only a few studies have investigated the effect of high-fat diet during gestation and lactation on beta-cell function. Here we elucidate the effect of maternal high-fat diet on beta-cells in a mouse model. Pregnant C57BL/6J mice received 60xa0% high-fat diet for the duration of both gestation and lactation (HFGL), gestation only, or lactation only. Beta-cell function of the male offspring of each group at 6xa0weeks of age was compared with those under standard diet. Although body weight, insulin sensitivity judged by insulin tolerance test, and random glucose level were comparable among the groups, only offspring of the HFGL group showed glucose intolerance with impaired insulin secretion during intraperitoneal glucose tolerance test. A compensatory increase in pancreatic beta-cell mass was observed in the offspring of the HFGL group, and decreased glucose-stimulated insulin secretion from isolated islets was confirmed by batch-incubation and perifusion experiments. Our results demonstrated that high-fat diet consumed during gestation and lactation elicits beta-cell dysfunction in the offspring of C57BL/6J mice.

Increased expression of ERp57/GRP58 is protective against pancreatic beta cell death caused by autophagic failure.

Autophagy is a tightly regulated self-digestion system. As in other cell types, autophagy plays an essential role in the homeostasis of pancreatic beta cells. However, the mechanisms involved in the deterioration of beta cell function caused by autophagic failure have not yet been fully elucidated. To gain insight into its mechanisms, we compared the protein expression of islets from beta cell-specific Atg7-deficient mice (Atg7(Δβ-cell) mice) and their controls (Atg7(f/f) mice). Liquid chromatography/mass spectrometry after 1-dimensional electrophoresis identified the increased expression of ERp57/GRP58 in islets isolated from Atg7(Δβ-cell) mice compared with those from Atg7(f/f) mice. The expression level of ERp57 was also elevated in rat insulinoma INS-1 cells by inducible knock-down of the atg7-gene. In Atg7 knock-down INS-1 cells, the suppression of ERp57 expression by siRNA resulted in an increase in the level of cleaved Caspase-3 protein and a decrease in the number of live cells. Furthermore, cell cycle analyses demonstrated that the suppressed expression of ERp57 increased the sub-G1 population. These data reveal that increased expression of ERp57 may contribute to the protection from beta cell death caused by autophagic failure.