Published papers

High-fat diet (HFD) induces low-grade chronic inflammation and insulin resistance. However, little is known about the mechanism underlying HFD-induced chronic inflammation in peripheral insulin-responsive tissues. Here, we show that colonic pro-inflammatory macrophages regulate insulin sensitivity under HFD conditions. To investigate the pathophysiological role of colonic macrophages, we generated macrophage-specific chemokine (C-C Motif) receptor 2 (Ccr2) knockout (M-Ccr2KO) and intestinal epithelial cell-specific tamoxifen-inducible Ccl2 knockout (Vil-Ccl2KO) mice. Both strains exhibited similar body weight to control under HFD. However, they exhibited decreased infiltration of colonic pro-inflammatory macrophages, decreased intestinal permeability, and inactivation of the colonic inflammasome. Interestingly, they showed significantly improved glucose tolerance and insulin sensitivity with decreased chronic inflammation of adipose tissue. Therefore, inhibition of pro-inflammatory macrophage infiltration prevents HFD-induced insulin resistance and could be a novel therapeutic approach for type 2 diabetes.

AIM: Hyperlipidemia and diabetic retinopathy increase the risk of cardiovascular disease (CVD). The standard versus intEnsive statin therapy for hypercholesteroleMic Patients with diAbetic retinopaTHY (EMPATHY) study examines whether intensive lipid-lowering therapy is superior to standard therapy in reducing the incidence of cardiovascular events in patients with hyperlipidemia and diabetic retinopathy, but without a history of coronary artery disease. METHODS: Patients who had elevated low-density lipoprotein cholesterol (LDL-C) and diabetic retinopathy without a history of coronary artery disease were eligible for the study. Patients were randomly assigned in a 1:1 ratio to receive intensive or standard therapy. Patients are being treated with monotherapy with 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor (statin) for a maximum of 5.5 years to achieve the following LDL-C target: 70 mg/dL for the intensive therapy group or >/=100 and 120 mg/dL for the standard therapy group. The primary endpoint is a composite of incidence of CVD and death from CVD. RESULTS: Between May 2010 and October 2013, 5,995 patients were assessed for eligibility, and 5,144 were assigned to the study treatment (2,571 and 2,573 in the intensive and standard therapy groups, respectively), and baseline data were analyzed from 5,107 (2,550 in the intensive therapy group and 2,557 in the standard therapy group). CONCLUSIONS: This is the first study assessing the benefits of intensive statin therapy in patients with hypercholesterolemia and diabetic retinopathy in a primary prevention setting. Furthermore, this study evaluates the appropriateness of the treat-to-target approach because all patients are treated to achieve specific LDL-C targets by titrating statin therapy. CLINICAL TRIAL REGISTRATION NUMBER: UMIN000003486.

CONTEXT: The ethnic difference in beta-cell regenerative capacity in response to obesity may be attributable to different phenotypes of type 2 diabetes among ethnicities. OBJECTIVE: This study aimed to clarify the effects of diabetes and obesity on beta- (BCM) and alpha-cell mass (ACM) in the Japanese population. DESIGN, SETTING, AND PARTICIPANTS: We obtained the pancreases of 99 individuals who underwent pancreatic surgery and whose resected pancreas sample contained adequate normal pancreas for histological analysis. Questionnaires on a family history of diabetes and history of obesity were conducted in 59 patients. Pancreatic sections were stained for insulin or glucagon, and fractional beta- and alpha-cell area were measured. Islet size and density as well as beta-cell turnover were also quantified. RESULTS: In patients with diabetes, BCM was decreased by 46% compared with age- and body mass index-matched nondiabetic patients (1.48% +/- 1.08% vs 0.80% +/- 0.54%, P < .001), whereas there was no difference in ACM between the groups. There was no effect of obesity or history of obesity on BCM and ACM irrespective of the presence or absence of diabetes. There was a negative correlation between BCM, but not ACM, and glycated hemoglobin before and after pancreatic surgery. In addition, reduced BCM was observed in patients with pancreatic cancer compared with those with other pancreatic tumors. CONCLUSIONS: These findings suggest that the increase in BCM in the face of insulin resistance is extremely limited in the Japanese, and BCM rather than ACM has a major role in regulating blood glucose level in humans.

Mitochondrial dysfunction is associated with type 2 diabetes mellitus (T2DM). 5-Aminolevulinic acid (ALA), a natural amino acid produced only in the mitochondria, is a precursor of heme. Cytochromes that contain heme play an important role in aerobic energy metabolism. Thus, ALA may help reduce T2DM-associated hyperglycemia. In this study, we investigated the effect of ALA combined with sodium ferrous citrate (SFC) on hyperglycemia in Zucker diabetic fatty (ZDF) rats. We found that the gavage administration of ALA combined with SFC (ALA/SFC) for 6 weeks reduced plasma glucose and hemoglobin A1c (HbA1c) levels in rats without affecting plasma insulin levels. The glucose-lowering effect depended on the amount of ALA/SFC administered per day. Furthermore, the glucose tolerance was also significantly improved by ALA/SFC administration. Although food intake was slightly reduced in the rats administered ALA/SFC, there was no effect on their body weight. Importantly, ALA/SFC administration induced heme oxygenase-1 (HO-1) expression in white adipose tissue and liver, and the induced expression levels of HO-1 correlated with the glucose-lowering effects of ALA/SFC. Taken together, these results suggest that ALA combined with ferrous ion is effective in reducing hyperglycemia of T2DM without affecting plasma insulin levels. HO-1 induction may be involved in the mechanisms underlying the glucose-lowering effect of ALA/SFC.

BACKGROUND: microRNAs (miRNAs) are non-coding small RNAs that regulate embryonic development, cell differentiation and pathological processes via interaction with mRNA. Epithelial-mesenchymal transition (EMT) is pathological process that involves in a variety of diseases such as cancer or fibrosis. METHODS: In this study, we identified miR-363 as a potent inducer of EMT by microarray analysis in human kidney tubular cells, and analyzed the function and mechanisms of miR-363. RESULTS: Overexpression of miR-363 induced mesenchymal phenotypes with loss of epithelial phenotypes in human kidney tubular cells. In addition, in vitro scratch assay demonstrated that miR-363 promotes cell migration of primary culture of human kidney tubular cells. We identified TWIST/canonical WNT pathway as the downstream effecter of miR-363, and inhibition of canonical WNT by small molecule, IWR-1, attenuated EMT induced by miR-363. CONCLUSION: miR-363 induces transdifferentiation of human kidney tubular cells via upregulation of TWIST/canonical WNT pathway.

We used an optical imaging technique to investigate whether axons of neurons in the caudal end of the ventrolateral medulla (CeVLM), as well as axons of neurons in the rostral ventrolateral medulla (RVLM), project to neurons in the intermediolateral cell column (IML) of the spinal cord. Brain stem-spinal cord preparations from neonatal normotensive Wistar-Kyoto and spontaneously hypertensive rats were stained with a voltage-sensitive dye, and responses to electrical stimulation of the IML at the Th2 level were detected as changes in fluorescence intensity with an optical imaging apparatus (MiCAM-01). The results were as follows: 1) depolarizing responses to IML stimulation during low-Ca high-Mg superfusion were detected on the ventral surface of the medulla at the level of the CeVLM, as well as at the level of the RVLM, 2) depolarizing responses were also detected on cross sections at the level of the CeVLM, and they had a latency of 24.0 +/- 5.5 (SD) ms, 3) antidromic action potentials in response to IML stimulation were demonstrated in the CeVLM neurons where optical images were detected, and 4) glutamate application to the CeVLM increased the frequency of excitatory postsynaptic potentials (EPSPs) and induced depolarization of the IML neurons. The optical imaging findings suggested a novel axonal and functional projection from neurons in the CeVLM to the IML. The increase in EPSPs of the IML neurons in response to glutamate application suggests that the CeVLM participates in the regulation of sympathetic nerve activity and blood pressure and may correspond to the caudal pressor area.

The incidence of hypertension and hypertensive renal disease is increasing worldwide, and new strategies to prevent these diseases need to be investigated. The aims of this study were 1) to examine if transient exposure to an angiotensin receptor blocker (ARB) during an early period in hypertension development confers protection against subsequent worsening of hypertension and renal injury induced by the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME), and 2) conversely, to examine the effects of transient exposure to angiotensin II (Ang II) during the same period. First, spontaneously hypertensive rats (SHR) were treated transiently from age 3 to 10 weeks with an ARB (candesartan cilexetil), a calcium channel antagonist or a vasodilator, then taken off treatment for 2 months. Administration of L-NAME at age 18 weeks caused severe hypertension and renal injury. However, the rats that had been exposed to the ARB not only had a lower blood pressure, but also failed to show signs of renal injury or increase of oxidative stress. Furthermore, the elevation of components of the renin-angiotensin-aldosterone system was also suppressed in these rats. In the second study, Wistar-Kyoto rats (WKY) and SHR were exposed to Ang II from age 4 to 8 weeks. The follow-up showed that the blood pressures in the WKY remained elevated compared to controls, while the SHR had heightened increases in blood pressure, renal renin mRNA, and urinary 8-hyroxydeoxyguanosine after L-NAME administration. Together, these experiments demonstrate that transient treatment of rats during an early phase in the development of hypertension with an ARB suppresses the renin-angiotensin-aldosterone system and confers long-term protection against subsequent L-NAME-induced renal injury and increases in renal oxidative stress. Conversely, developmental exposure to Ang II during this "critical" period had the opposite effect, predisposing rats to higher blood pressure, renal injury, and oxidative stress after L-NAME administration.

OBJECTIVE: The acquisition of arterial or venous identity is highlighted in vascular development. Previously, we have reported an embryonic stem (ES) cell differentiation system that exhibits early vascular development using vascular endothelial growth factor (VEGF) receptor-2 (VEGFR2)-positive cells as common vascular progenitors. In this study, we constructively induced differentiation of arterial and venous endothelial cells (ECs) in vitro to elucidate molecular mechanisms of arterial-venous specification. METHODS AND RESULTS: ECs were induced from VEGFR2+ progenitor cells with various conditions. VEGF was essential to induce ECs. Addition of 8bromo-cAMP or adrenomedullin (AM), an endogenous ligand-elevating cAMP, enhanced VEGF-induced EC differentiation. Whereas VEGF alone mainly induced venous ECs, 8bromo-cAMP (or AM) with VEGF supported substantial induction of arterial ECs. Stimulation of cAMP pathway induced Notch signal activation in ECs. The arterializing effect of VEGF and cAMP was abolished in recombination recognition sequence binding protein at the Jkappa site deficient ES cells lacking Notch signal activation or in ES cells treated with gamma-secretase inhibitor. Nevertheless, forced Notch activation by the constitutively active Notch1 alone did not induce arterial ECs. CONCLUSIONS: Adrenomedullin/cAMP is a novel signaling pathway to activate Notch signaling in differentiating ECs. Coordinated signaling of VEGF, Notch, and cAMP is required to induce arterial ECs from vascular progenitors.