Overexpression of UBE2E2 in Mouse Pancreatic β-Cells Leads to Glucose Intolerance via Reduction of β-Cell Mass

Genome-wide association studies have identified several gene polymorphisms, including UBE2E2, associated with type 2 diabetes. Although UBE2E2 is one of the ubiquitin-conjugating enzymes involved in the process of ubiquitin modifications, the pathophysiological roles of UBE2E2 in metabolic dysfunction are not yet understood. Here, we showed upregulated UBE2E2 expression in the islets of a mouse model of diet-induced obesity. The diabetes risk allele of UBE2E2 (rs13094957) in noncoding regions was associated with upregulation of UBE2E2 mRNA in the human pancreas. Although glucose-stimulated insulin secretion was intact in the isolated islets, pancreatic β-cell-specific UBE2E2-transgenic (TG) mice exhibited reduced insulin secretion and decreased β-cell mass. In TG mice, suppressed proliferation of β-cells before the weaning period and while receiving a high-fat diet was accompanied by elevated gene expression levels of p21, resulting in decreased postnatal β-cell mass expansion and compensatory β-cell hyperplasia, respectively. In TG islets, proteomic analysis identified enhanced formation of various types of polyubiquitin chains, accompanied by increased expression of Nedd4 E3 ubiquitin protein ligase. Ubiquitination assays showed that UBE2E2 mediated the elongation of ubiquitin chains by Nedd4. The data suggest that UBE2E2-mediated ubiquitin modifications in β-cells play an important role in regulating glucose homeostasis and β-cell mass.

Corticosteroid-triggered acute skeletal muscle loss in lipodystrophy: A case report

The potential liability to hypercatabolism in lipodystrophy remains to be fully elucidated. Here we report a 28-year-old Japanese woman with acquired generalized lipodystrophy, who presented with recurrence of panniculitis and anemia. After corticosteroid treatment was started, she showed rapid reductions in body weight and lean mass by 15% at maximum, accompanied by an elevated urea nitrogen/creatinine ratio, which recovered almost fully as the corticosteroid treatment was tapered and discontinued. She had multiple risk factors for hypercatabolism: lack of metabolic reserves, insulin resistance, and hyperglycemia due to lipodystrophy, lowered daily activity due to anemia, persistent inflammation, and wasting associated with panniculitis, and relatively insufficient energy and protein intake during hospitalization. More attention should be paid to the potential liability to hypercatabolism in patients with lipodystrophy, and to skeletal muscle loss as an adverse effect of corticosteroid treatment in patients at high risk, such as those with diabetes or decreased metabolic reserves.

Exploring mechanisms underlying diabetes comorbidities and strategies to prevent vascular complications

It is important to prevent not only diabetic complications but also diabetic comorbidities in diabetes care. We have elucidated multifaceted insulin action in various tissues mainly by means of model mice, and it was revealed that insulin regulates endoplasmic reticulum (ER) stress response during feeding, whereas ER stress 'response failure' contributes to the development of steatohepatitis, one of the major diabetic comorbidities. Insulin regulates gluconeogenesis not only in the liver but also in the proximal tubules of the kidney, which is also suppressed by reabsorbed glucose in the latter. In skeletal muscle, another important insulin-targeted tissue, impaired insulin/IGF-1 signaling leads not only to sarcopenia, an aging-related disease, but also to bone loss and shorter longevity. Aging is regulated by adipokines as well, and it is deemed to be accelerated by 'imbalanced adipokines' in combination with genetic background of progeria. Moreover, we reported effects of intensive multifactorial intervention on diabetic complications and mortality in patients with type 2 diabetes in a large-scale clinical trial, the J-DOIT3, followed by reports of subsequent sub-analyses of renal events and fracture events. Various approaches to elucidate the mechanisms underlying the development of diabetes and how it should be treated are expected to help us improve diabetes management.

Gut insulin action protects from hepatocarcinogenesis in diabetic mice comorbid with nonalcoholic steatohepatitis

Diabetes is known to increase the risk of nonalcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC). Here we treat male STAM (STelic Animal Model) mice, which develop diabetes, NASH and HCC associated with dysbiosis upon low-dose streptozotocin and high-fat diet (HFD), with insulin or phlorizin. Although both treatments ameliorate hyperglycemia and NASH, insulin treatment alone lead to suppression of HCC accompanied by improvement of dysbiosis and restoration of antimicrobial peptide production. There are some similarities in changes of microflora from insulin-treated patients comorbid with diabetes and NASH. Insulin treatment, however, fails to suppress HCC in the male STAM mice lacking insulin receptor specifically in intestinal epithelial cells (ieIRKO), which show dysbiosis and impaired gut barrier function. Furthermore, male ieIRKO mice are prone to develop HCC merely on HFD. These data suggest that impaired gut insulin signaling increases the risk of HCC, which can be countered by restoration of insulin action in diabetes.

Sarcopenia: Loss of mighty armor against frailty and aging

The goal of diabetes management is to achieve longevity and quality of life equivalent to those of people without diabetes, and for that, it is now deemed important to pay close attention not only to diabetic vascular complications but also to diabetic comorbidities, as is recommended by the Japan Diabetes Society. In this editorial, we focus on sarcopenia as an important diabetic comorbidity which is an aging-related phenomenon in skeletal muscle. Taking our recent report on a sarcopenia mouse model and other accumulated evidence into account, we propose the existence of a skeletal muscle-centered inter-tissue network that regulates frailty and systemic aging. Sarcopenia is deemed to be a state in which skeletal muscle serving as a protective mighty armor against frailty and systemic aging is lost, and it is vitally important to establish how to recover it and keep it in good shape, so that the goal of diabetes management can be achieved.

Intensified Multifactorial Intervention in Patients with Type 2 Diabetes Mellitus

In the management of diabetes mellitus, one of the most important goals is to prevent its micro- and macrovascular complications, and to that end, multifactorial intervention is widely recommended. Intensified multifactorial intervention with pharmacotherapy for associated risk factors, alongside lifestyle modification, was first shown to be efficacious in patients with microalbuminuria (Steno-2 study), then in those with less advanced microvascular complications (the Anglo-Danish-Dutch Study of Intensive Treatment In People with Screen Detected Diabetes in Primary Care [ADDITION]-Europe and the Japan Diabetes Optimal Treatment study for 3 major risk factors of cardiovascular diseases [J-DOIT3]), and in those with advanced microvascular complications (the Nephropathy In Diabetes-Type 2 [NID-2] study and Diabetic Nephropathy Remission and Regression Team Trial in Japan [DNETT-Japan]). Thus far, multifactorial intervention led to a reduction in cardiovascular and renal events, albeit not necessarily significant. It should be noted that not only baseline characteristics but also the control status of the risk factors and event rates during intervention among the patients widely varied from one trial to the next. Further evidence is needed for the efficacy of multifactorial intervention in a longer duration and in younger or elderly patients. Moreover, now that new classes of antidiabetic drugs are available, it should be addressed whether strict and safe glycemic control, alongside control of other risk factors, could lead to further risk reductions in micro- and macrovascular complications, thereby decreasing all-cause mortality in patients with type 2 diabetes mellitus.

Deletion of skeletal muscle Akt1/2 causes osteosarcopenia and reduces lifespan in mice

Aging is considered to be accelerated by insulin signaling in lower organisms, but it remained unclear whether this could hold true for mammals. Here we show that mice with skeletal muscle-specific double knockout of Akt1/2, key downstream molecules of insulin signaling, serve as a model of premature sarcopenia with insulin resistance. The knockout mice exhibit a progressive reduction in skeletal muscle mass, impairment of motor function and systemic insulin sensitivity. They also show osteopenia, and reduced lifespan largely due to death from debilitation on normal chow and death from tumor on high-fat diet. These phenotypes are almost reversed by additional knocking out of Foxo1/4, but only partially by additional knocking out of Tsc2 to activate the mTOR pathway. Overall, our data suggest that, unlike in lower organisms, suppression of Akt activity in skeletal muscle of mammals associated with insulin resistance and aging could accelerate osteosarcopenia and consequently reduce lifespan.

Skeletal muscle mitoribosomal defects are linked to low bone mass caused by bone marrow inflammation in male mice

BACKGROUND

Mitochondrial oxidative phosphorylation (OxPhos) is a critical regulator of skeletal muscle mass and function. Although muscle atrophy due to mitochondrial dysfunction is closely associated with bone loss, the biological characteristics of the relationship between muscle and bone remain obscure. We showed that muscle atrophy caused by skeletal muscle-specific CR6-interacting factor 1 knockout (MKO) modulates the bone marrow (BM) inflammatory response, leading to low bone mass.

METHODS

MKO mice with lower muscle OxPhos were fed a normal chow or high-fat diet and then evaluated for muscle mass and function, and bone mineral density. Immunophenotyping of BM immune cells was also performed. BM transcriptomic analysis was used to identify key factors regulating bone mass in MKO mice. To determine the effects of BM-derived CXCL12 (C-X-C motif chemokine ligand 12) on regulation of bone homeostasis, a variety of BM niche-resident cells were treated with recombinant CXCL12. Vastus lateralis muscle and BM immune cell samples from 14 patients with hip fracture were investigated to examine the association between muscle function and BM inflammation.

RESULTS

MKO mice exhibited significant reductions in both muscle mass and expression of OxPhos subunits but increased transcription of mitochondrial stress response-related genes in the extensor digitorum longus (P < 0.01). MKO mice showed a decline in grip strength and a higher drop rate in the wire hanging test (P < 0.01). Micro-computed tomography and von Kossa staining revealed that MKO mice developed a low mass phenotype in cortical and trabecular bone (P < 0.01). Transcriptomic analysis of the BM revealed that mitochondrial stress responses in skeletal muscles induce an inflammatory response and adipogenesis in the BM and that the CXCL12-CXCR4 (C-X-C chemokine receptor 4) axis is important for T-cell homing to the BM. Antagonism of CXCR4 attenuated BM inflammation and increased bone mass in MKO mice. In humans, patients with low body mass index (BMI = 17.2 ± 0.42 kg/m² ) harboured a larger population of proinflammatory and cytotoxic senescent T-cells in the BMI (P < 0.05) and showed reduced expression of OxPhos subunits in the vastus lateralis, compared with controls with a normal BMI (23.7 ± 0.88 kg/m² ) (P < 0.01).

CONCLUSIONS

Defects in muscle mitochondrial OxPhos promote BM inflammation in mice, leading to decreased bone mass. Muscle mitochondrial dysfunction is linked to BM inflammatory cytokine secretion via the CXCL12-CXCR4 signalling axis, which is critical for inducing low bone mass.

Severe aortic stenosis during leptin replacement therapy in a patient with generalized lipodystrophy-associated progeroid syndrome due to a LMNA variant: a case report

Leptin replacement therapy (LRT) has drastically improved the prognosis of patients with lipodystrophy, but pro‐inflammatory properties of leptin could become evident in the long term. Here, we report a 30‐year‐old Japanese woman with generalized lipodystrophy‐associated progeroid syndrome due to a heterozygous LMNA variant (c.29C > T; p.T10I), who was diagnosed with severe aortic stenosis (AS) after more than a decade of LRT, which required transcatheter aortic valve implantation. Given her marked hypoadiponectinemia and the LMNA variant, our patient might have been susceptible to progeria‐associated disorders, including aortic stenosis, which could have been exaggerated by the prolonged ‘imbalanced adipokines’ caused by LRT between pro‐inflammatory leptin and anti‐inflammatory adiponectin. Thus, long‐term LRT could be associated with AS in patients with the LMNA variant to cause generalized lipodystrophy‐associated progeroid syndrome and hypoadiponectinemia.

Effect of a Multifactorial Intervention on Fracture in Patients With Type 2 Diabetes: Subanalysis of the J-DOIT3 Study

AIMS

To evaluate the effects of an intensified multifactorial intervention and patient characteristics on the incidence of fractures comorbid with type 2 diabetes.

METHODS

Fracture events were identified and analyzed among adverse events reported in the J-DOIT3 study, a multicenter, open-label, randomized, parallel-group trial that was conducted in Japan, in which patients with type 2 diabetes were randomly assigned to receive conventional therapy for glucose, blood pressure, and lipids (targets: HbA1c < 6.9%, blood pressure <130/80 mm Hg, LDL-cholesterol <120mg/dL) or intensive therapy (HbA1c < 6.2%, blood pressure <120/75 mm Hg, LDL-cholesterol <80mg/dL) (ClinicalTrials.gov registration no. NCT00300976).

RESULTS

The cumulative incidence of fractures did not differ between those receiving conventional therapy and those receiving intensive therapy (hazard ratio (HR) 1.15; 95% CI, 0.91-1.47; P = 0.241). Among the potential risk factors, only history of smoking at baseline was significantly associated with the incidence of fractures in men (HR 1.96; 95% CI, 1.04-3.07; P = 0.038). In contrast, the incidence of fractures in women was associated with the FRAX score [%/10 years] at baseline (HR 1.04; 95% CI, 1.02-1.07; P < 0.001) and administration of pioglitazone at 1 year after randomization (HR 1.59; 95% CI, 1.06-2.38; P = 0.025).

CONCLUSIONS

Intensified multifactorial intervention may be implemented without increasing the fracture risk in patients with type 2 diabetes. The fracture risk is elevated in those with a history of smoking in men, whereas it is predicted by the FRAX score and is independently elevated with administration of pioglitazone in women.

Hepatocellular carcinoma development in diabetic patients: a nationwide survey in Japan

BACKGROUND

Although type 2 diabetes mellitus (T2DM) is a known risk factor for hepatocellular carcinoma (HCC) development, the annual incidence in diabetes patients is far below the threshold of efficient surveillance. This study aimed to elucidate the risk factors for HCC in diabetic patients and to determine the best criteria to identify surveillance candidates.

METHODS

The study included 239 patients with T2DM who were diagnosed with non-viral HCC between 2010 and 2015, with ≥ 5 years of follow-up at diabetes clinics of 81 teaching hospitals in Japan before HCC diagnosis, and 3277 non-HCC T2DM patients from a prospective cohort study, as controls. Clinical data at the time of and 5 years before HCC diagnosis were collected.

RESULTS

The mean patient age at HCC diagnosis was approximately 73 years, and 80% of the patients were male. The proportion of patients with insulin use increased, whereas the body mass index (BMI), proportion of patients with fatty liver, fasting glucose levels, and hemoglobin A1c (HbA1c) levels decreased significantly in 5 years. In the cohort study, 18 patients developed HCC during the mean follow-up period of 4.7 years with an annual incidence of 0.11%. Multivariate logistic regression analyses showed that the FIB-4 index was an outstanding predictor of HCC development along with male sex, presence of hypertension, lower HbA1c and albumin levels, and higher BMI and gamma-glutamyl transpeptidase levels. Receiver-operating characteristic analyses showed that a FIB-4 cut-off value of 3.61 could help identify high-risk patients, with a corresponding annual HCC incidence rate of 1.1%.

CONCLUSION

A simple calculation of the FIB-4 index in diabetes clinics can be the first step toward surveillance of HCC with a non-viral etiology.

Clinical usefulness of multigene screening with phenotype-driven bioinformatics analysis for the diagnosis of patients with monogenic diabetes or severe insulin resistance

AIMS

Monogenic diabetes is clinically heterogeneous and differs from common forms of diabetes (type 1 and 2). We aimed to investigate the clinical usefulness of a comprehensive genetic testing system, comprised of targeted next-generation sequencing (NGS) with phenotype-driven bioinformatics analysis in patients with monogenic diabetes, which uses patient genotypic and phenotypic data to prioritize potentially causal variants.

METHODS

We performed targeted NGS of 383 genes associated with monogenic diabetes or common forms of diabetes in 13 Japanese patients with suspected (n = 10) or previously diagnosed (n = 3) monogenic diabetes or severe insulin resistance. We performed in silico structural analysis and phenotype-driven bioinformatics analysis of candidate variants from NGS data.

RESULTS

Among the patients suspected having monogenic diabetes or insulin resistance, we diagnosed 3 patients as subtypes of monogenic diabetes due to disease-associated variants of INSR, LMNA, and HNF1B. Additionally, in 3 other patients, we detected rare variants with potential phenotypic effects. Notably, we identified a novel missense variant in TBC1D4 and an MC4R variant, which together may cause a mixed phenotype of severe insulin resistance.

CONCLUSIONS

This comprehensive approach could assist in the early diagnosis of patients with monogenic diabetes and facilitate the provision of tailored therapy.

Multifactorial intervention has a significant effect on diabetic kidney disease in patients with type 2 diabetes

To evaluate the effect of multifactorial intervention on the onset and progression of diabetic kidney disease in the patients with type 2 diabetes, we analyzed the effects of intensified multifactorial intervention by step-wise intensification of medications and life-style modifications (intensive therapy treatment targets; HbA1c under 6.2%, blood pressure under 120/75 mmHg, low-density lipoprotein cholesterol under 80 mg/dL) comparing with the guideline-based standard care (conventional therapy treatment targets: HbA1c under 6.9%, blood pressure under 130/80 mmHg, low-density lipoprotein cholesterol under 120 mg/dL) on diabetic kidney disease. A total of 2540 eligible patients in the Japan Diabetes Optimal Integrated Treatment for three major risk factors of cardiovascular diseases (J-DOIT3) cohort were randomly assigned to intensive therapy (1269) and conventional therapy (1271) and treated for a median of 8.5 years. The prespecified kidney outcome measure was a composite of progression from normoalbuminuria to microalbuminuria or progression from normoalbuminuria to macroalbuminuria or progression from microalbuminuria to macroalbuminuria, serum creatinine levels elevated by two-fold or more compared to baseline, or kidney failure. Primary analysis was carried out on the intention-to-treat population. Changes in the estimated glomerular filtration rate and albuminuria were also analyzed. A total of 438 kidney events occurred (181 in the intensive therapy group and 257 in the conventional therapy group). Intensive therapy was associated with a significant 32% reduction in kidney events compared to conventional therapy and was associated with a change in HbA1c at one year from study initiation. Thus, prespecified analysis shows that intensified multifactorial intervention significantly reduced the onset and progression of diabetic kidney disease compared to currently recommended care.

Insulin- and Lipopolysaccharide-Mediated Signaling in Adipose Tissue Macrophages Regulates Postprandial Glycemia through Akt-mTOR Activation

The physiological role of immune cells in the regulation of postprandial glucose metabolism has not been fully elucidated. We have found that adipose tissue macrophages produce interleukin-10 (IL-10) upon feeding, which suppresses hepatic glucose production in cooperation with insulin. Both elevated insulin and gut-microbiome-derived lipopolysaccharide in response to feeding are required for IL-10 production via the Akt/mammalian target of rapamycin (mTOR) pathway. Indeed, myeloid-specific knockout of the insulin receptor or bone marrow transplantation of mutant TLR4 marrow cells results in increased expression of gluconeogenic genes and impaired glucose tolerance. Furthermore, myeloid-specific Akt1 and Akt2 knockout results in similar phenotypes that are rescued by additional knockout of TSC2, an inhibitor of mTOR. In obesity, IL-10 production is impaired due to insulin resistance in macrophages, whereas adenovirus-mediated expression of IL-10 ameliorates postprandial hyperglycemia. Thus, the orchestrated response of the endogenous hormone and gut environment to feeding is a key regulator of postprandial glycemia.

Variation in process quality measures of diabetes care by region and institution in Japan during 2015-2016: An observational study of nationwide claims data

AIMS

To calculate process quality measures of diabetes care in Japan using nationwide exclusive claims database.

METHODS

Using the National Database of health insurance claims during 2015-2016, the proportions of outpatients who received recommended examinations at least annually among those with regular antidiabetic medication were calculated as quality indicators, reported altogether and by prefecture and institutional certification (from the Japan Diabetes Society). Distributions of institutional-level quality indicators were also reported.

RESULTS

Among 4,154,452 outpatients, 96.7% underwent HbA1c or glycated albumin examination. Retinopathy examination was conducted among 46.5% of patients [prefecture (range): 37.5%-51.0%, institutional certification: 44.8% (without) vs. 59.8% (with)]. Urinary qualitative examination was conducted among 67.3% of patients at institutions with <200 beds (prefecture: 54.1%-81.9%, institutional certification: 66.8% vs. 92.8%), whereas urinary quantitative albumin or protein examination was conducted among 19.4% of patients (prefecture: 10.8%-31.6%, institutional certification: 18.7% vs. 54.8%). Distributions of institutional-level quality indicators showed that most institutions without institutional certification seldomly order urinary quantitative examination.

CONCLUSIONS

Although the quality indicator for glycaemic control examination was favourable, some aspects of diabetes care were suboptimal and varied greatly by prefecture and institution; individual and organisational efforts to improve quality of diabetes care would be needed in Japan.

Robust and highly efficient hiPSC generation from patient non-mobilized peripheral blood-derived CD34+ cells using the auto-erasable Sendai virus vector

BACKGROUND

Disease modeling with patient-derived induced pluripotent stem cells (iPSCs) is a powerful tool for elucidating the mechanisms underlying disease pathogenesis and developing safe and effective treatments. Patient peripheral blood (PB) cells are used for iPSC generation in many cases since they can be collected with minimum invasiveness. To derive iPSCs that lack immunoreceptor gene rearrangements, hematopoietic stem and progenitor cells (HSPCs) are often targeted as the reprogramming source. However, the current protocols generally require HSPC mobilization and/or ex vivo expansion owing to their sparsity at the steady state and low reprogramming efficiencies, making the overall procedure costly, laborious, and time-consuming.

METHODS

We have established a highly efficient method for generating iPSCs from non-mobilized PB-derived CD34+ HSPCs. The source PB mononuclear cells were obtained from 1 healthy donor and 15 patients and were kept frozen until the scheduled iPSC generation. CD34+ HSPC enrichment was done using immunomagnetic beads, with no ex vivo expansion culture. To reprogram the CD34+-rich cells to pluripotency, the Sendai virus vector SeVdp-302L was used to transfer four transcription factors: KLF4, OCT4, SOX2, and c-MYC. In this iPSC generation series, the reprogramming efficiencies, success rates of iPSC line establishment, and progression time were recorded. After generating the iPSC frozen stocks, the cell recovery and their residual transgenes, karyotypes, T cell receptor gene rearrangement, pluripotency markers, and differentiation capability were examined.

RESULTS

We succeeded in establishing 223 iPSC lines with high reprogramming efficiencies from 15 patients with 8 different disease types. Our method allowed the rapid appearance of primary colonies (~ 8 days), all of which were expandable under feeder-free conditions, enabling robust establishment steps with less workload. After thawing, the established iPSC lines were verified to be pluripotency marker-positive and of non-T cell origin. A majority of the iPSC lines were confirmed to be transgene-free, with normal karyotypes. Their trilineage differentiation capability was also verified in a defined in vitro assay.

CONCLUSION

This robust and highly efficient method enables the rapid and cost-effective establishment of transgene-free iPSC lines from a small volume of PB, thus facilitating the biobanking of patient-derived iPSCs and their use for the modeling of various diseases.

Hepatic Sdf2l1 controls feeding-induced ER stress and regulates metabolism

Dynamic metabolic changes occur in the liver during the transition between fasting and feeding. Here we show that transient ER stress responses in the liver following feeding terminated by Sdf2l1 are essential for normal glucose and lipid homeostasis. Sdf2l1 regulates ERAD through interaction with a trafficking protein, TMED10. Suppression of Sdf2l1 expression in the liver results in insulin resistance and increases triglyceride content with sustained ER stress. In obese and diabetic mice, Sdf2l1 is downregulated due to decreased levels of nuclear XBP-1s, whereas restoration of Sdf2l1 expression ameliorates glucose intolerance and fatty liver with decreased ER stress. In diabetic patients, insufficient induction of Sdf2l1 correlates with progression of insulin resistance and steatohepatitis. Therefore, failure to build an ER stress response in the liver may be a causal factor in obesity-related diabetes and nonalcoholic steatohepatitis, for which Sdf2l1 could serve as a therapeutic target and sensitive biomarker.

[Aging-related frailty and sarcopenia. Frailty/sarcopenia and insulin/IGF-1 signaling.]

Insulin and IGF-1 share many of the downstream molecules involved in the signal transduction, and cooperatively maintain volume of skeletal muscle. Along with aging, however, insulin/IGF-1 signaling is impaired, mainly due to insulin resistance and lowered IGF-1 levels, which is thought to promote the development of sarcopenia, and thus they are among the promising therapeutic targets. It is also known that sarcopenia is associated with the development of frailty, one of the phenomena of systemic aging. Actually insulin/IGF-1 signaling is known to affect longevity in lower organisms, but in humans, little is known about roles of the signaling in the development of frailty, and further investigation is needed.

[Homeostasis and Disorder of Musculoskeletal System.Roles of the motor system in systemic metabolism and the aging-related disorders.]

Among the tissues involved in the motor system, skeletal muscle plays an important role in systemic metabolism and is the largest organ in terms of glucose uptake. Insulin promotes anabolism of nutrients in skeletal muscle, as in other insulin-targeted organs, and maintains muscle volume, in cooperation with insulin-like growth factor-1. In humans, along with aging, insulin resistance is induced in skeletal muscle, which could lead to systemic insulin resistance, and circulating IGF-1 levels are lowered. These changes contribute to the development of sarcopenia, in which function and volume of skeletal muscle are impaired, and modulation of the insulin/IGF-1 signaling could be promising in treatment of sarcopenia.

Hepatic IRS1 and ß-catenin expression is associated with histological progression and overt diabetes emergence in NAFLD patients

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a risk factor for type 2 diabetes. Our aim was to investigate the relationship between NAFLD and impaired glucose metabolism in terms of insulin receptor substrate 1 and 2 (IRS1 and IRS2) expression in the liver.

METHODS

Liver biopsy was performed at the University of Tokyo Hospital between November 2011 and March 2016 on 146 patients with NAFLD who were not being treated with any diabetes or dyslipidemia drugs. Among them, 63 underwent liver biopsy after an overnight fast, and 83 at 5 h after an oral glucose tolerance test (OGTT). Differences in messenger RNA (mRNA) levels of several glucose metabolism-related factors were determined and correlated with hepatic histological changes assessed by NAFLD activity score. We prospectively followed up with the patients until May 2017.

RESULTS

Hepatic necroinflammation was significantly correlated with serum insulin levels and inversely correlated with IRS1 mRNA levels. In specimens obtained after an OGTT, hepatic necroinflammation and IRS1 expression correlated significantly with both peripheral and hepatic insulin resistance. We also found that hepatic β-catenin and glucokinase mRNA levels were elevated in patients undergoing liver biopsy after an OGTT, especially in those with less hepatic necroinflammation and a lower degree of fibrosis. A prospective cohort study showed that ballooning is the most significant risk factor for developing diabetes.

CONCLUSIONS

The decreased hepatic expression of IRS1 and β-catenin in NAFLD is linked to histological progression such as ballooning, and might lead to diabetes as a result of impaired glucose metabolism.

Effect of an intensified multifactorial intervention on cardiovascular outcomes and mortality in type 2 diabetes (J-DOIT3): an open-label, randomised controlled trial

BACKGROUND

Limited evidence suggests that multifactorial interventions for control of glucose, blood pressure, and lipids reduce macrovascular complications and mortality in patients with type 2 diabetes. However, safe and effective treatment targets for these risk factors have not been determined for such interventions.

METHODS

In this multicentre, open-label, randomised, parallel-group trial, undertaken at 81 clinical sites in Japan, we randomly assigned (1:1) patients with type 2 diabetes aged 45-69 years with hypertension, dyslipidaemia, or both, and an HbA_1c of 6·9% (52·0 mmol/mol) or higher, to receive conventional therapy for glucose, blood pressure, and lipid control (targets: HbA_1c <6·9% [52·0 mmol/mol], blood pressure <130/80 mm Hg, LDL cholesterol <120 mg/dL [or 100 mg/dL in patients with a history of coronary artery disease]) or intensive therapy (HbA_1c <6·2% [44·3 mmol/mol], blood pressure <120/75 mm Hg, LDL cholesterol <80 mg/dL [or 70 mg/dL in patients with a history of coronary artery disease]). Randomisation was done using a computer-generated, dynamic balancing method, stratified by sex, age, HbA_1c, and history of cardiovascular disease. Neither patients nor investigators were masked to group assignment. The primary outcome was occurrence of any of a composite of myocardial infarction, stroke, revascularisation (coronary artery bypass surgery, percutaneous transluminal coronary angioplasty, carotid endarterectomy, percutaneous transluminal cerebral angioplasty, and carotid artery stenting), and all-cause mortality. The primary analysis was done in the intention-to-treat population. This study is registered with ClinicalTrials.gov, number NCT00300976.

FINDINGS

Between June 16, 2006, and March 31, 2009, 2542 eligible patients were randomly assigned to intensive therapy or conventional therapy (1271 in each group) and followed up for a median of 8·5 years (IQR 7·3-9·0). Two patients in the intensive therapy group were found to be ineligible after randomisation and were excluded from the analyses. During the intervention period, mean HbA_1c, systolic blood pressure, diastolic blood pressure, and LDL cholesterol concentrations were significantly lower in the intensive therapy group than in the conventional therapy group (6·8% [51·0 mmol/mol] vs 7·2% [55·2 mmol/mol]; 123 mm Hg vs 129 mm Hg; 71 mm Hg vs 74 mm Hg; and 85 mg/dL vs 104 mg/dL, respectively; all p<0·0001). The primary outcome occurred in 109 patients in the intensive therapy group and in 133 patients in the conventional therapy group (hazard ratio [HR] 0·81, 95% CI 0·63-1·04; p=0·094). In a post-hoc breakdown of the composite outcome, frequencies of all-cause mortality (HR 1·01, 95% CI 0·68-1·51; p=0·95) and coronary events (myocardial infarction, coronary artery bypass surgery, and percutaneous transluminal coronary angioplasty; HR 0·86, 0·58-1·27; p=0·44) did not differ between groups, but cerebrovascular events (stroke, carotid endarterectomy, percutaneous transluminal cerebral angioplasty, and carotid artery stenting) were significantly less frequent in the intensive therapy group (HR 0·42, 0·24-0·74; p=0·002). Apart from non-severe hypoglycaemia (521 [41%] patients in the intensive therapy group vs 283 [22%] in the conventional therapy group, p<0·0001) and oedema (193 [15%] vs 129 [10%], p=0·0001), the frequencies of major adverse events did not differ between groups.

INTERPRETATION

Our results do not fully support the efficacy of further intensified multifactorial intervention compared with current standard care for the prevention of a composite of coronary events, cerebrovascular events, and all-cause mortality. Nevertheless, our findings suggest a potential benefit of an intensified intervention for the prevention of cerebrovascular events in patients with type 2 diabetes.

FUNDING

Ministry of Health, Labour and Welfare of Japan, Asahi Kasei Pharma, Astellas Pharma, AstraZeneca, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Daiichi Sankyo, Eli Lilly, GlaxoSmithKline, Kissei Pharmaceutical, Kowa Pharmaceutical, Mitsubishi Tanabe Pharma, Mochida Pharmaceutical, MSD, Novartis Pharma, Novo Nordisk, Ono Pharmaceutical, Pfizer, Sanwa Kagaku Kenkyusho, Shionogi, Sumitomo Dainippon Pharma, Taisho Toyama Pharmaceutical, and Takeda.

Dual Regulation of Gluconeogenesis by Insulin and Glucose in the Proximal Tubules of the Kidney

Growing attention has been focused on the roles of the proximal tubules (PTs) of the kidney in glucose metabolism, including the mechanism of regulation of gluconeogenesis. In this study, we found that PT-specific insulin receptor substrate 1/2 double-knockout mice, established by using the newly generated sodium-glucose cotransporter 2 (SGLT2)-Cre transgenic mice, exhibited impaired insulin signaling and upregulated gluconeogenic gene expression and renal gluconeogenesis, resulting in systemic insulin resistance. In contrast, in streptozotocin-treated mice, although insulin action was impaired in the PTs, the gluconeogenic gene expression was unexpectedly downregulated in the renal cortex, which was restored by administration of an SGLT1/2 inhibitor. In the HK-2 cells, the gluconeogenic gene expression was suppressed by insulin, accompanied by phosphorylation and inactivation of forkhead box transcription factor 1 (FoxO1). In contrast, glucose deacetylated peroxisome proliferator-activated receptor γ coactivator 1-α (PGC1α), a coactivator of FoxO1, via sirtuin 1, suppressing the gluconeogenic gene expression, which was reversed by inhibition of glucose reabsorption. These data suggest that both insulin signaling and glucose reabsorption suppress the gluconeogenic gene expression by inactivation of FoxO1 and PGC1α, respectively, providing insight into novel mechanisms underlying the regulation of gluconeogenesis in the PTs.

Willingness of patients with diabetes to use an ICT-based self-management tool: a cross-sectional study

OBJECTIVES

To examine the prevalence of the willingness of patients with diabetes to use a self-management tool based on information and communication technology (ICT) such as personal computers, smartphones, and mobile phones; and to examine the patient characteristics associated with that willingness.

RESEARCH DESIGN AND METHODS

We conducted a cross-sectional interview survey of 312 adults with diabetes at a university hospital in an urban area in Japan. Participants were classified into 2 groups: those who were willing to use an ICT-based self-management tool and those who were unwilling. Multiple logistic regression analysis was used to identify factors associated with the willingness, including clinical and social factors, current use of ICT, self-management practices, self-efficacy, and diabetes-related emotional distress.

RESULTS

The mean age of the 312 participants was 66.3 years (SD=11.5) and 198 (63%) were male. Most of the participants (93%) had type 2 diabetes. Although only 51 (16%) currently used ICT-based self-management tools, a total of 157 (50%) expressed the willingness to use such a tool. Factors associated with the willingness included: not having nephropathy (OR=2.02, 95% CI 1.14 to 3.58); outpatient visits once a month or more (vs less than once a month, OR=2.13, 95% CI 1.13 to 3.99); current use of personal computers and/or smartphones (OR=4.91, 95% CI 2.69 to 8.98); and having greater diabetes-related emotional distress (OR=1.10, 95% CI 1.01 to 1.20).

CONCLUSIONS

Approximately half of the patients showed interest in using an ICT-based self-management tool. Willing patients may expect ICT-based self-management tools to complement outpatient visits and to make self-management easier. Starting with patients who display the willingness factors might optimize programs based on such tools.

Differential hepatic distribution of insulin receptor substrates causes selective insulin resistance in diabetes and obesity

Hepatic insulin signalling involves insulin receptor substrates (Irs) 1/2, and is normally associated with the inhibition of gluconeogenesis and activation of lipogenesis. In diabetes and obesity, insulin no longer suppresses hepatic gluconeogenesis, while continuing to activate lipogenesis, a state referred to as 'selective insulin resistance'. Here, we show that 'selective insulin resistance' is caused by the differential expression of Irs1 and Irs2 in different zones of the liver. We demonstrate that hepatic Irs2-knockout mice develop 'selective insulin resistance', whereas mice lacking in Irs1, or both Irs1 and Irs2, develop 'total insulin resistance'. In obese diabetic mice, Irs1/2-mediated insulin signalling is impaired in the periportal zone, which is the primary site of gluconeogenesis, but enhanced in the perivenous zone, which is the primary site of lipogenesis. While hyperinsulinaemia reduces Irs2 expression in both the periportal and perivenous zones, Irs1 expression, which is predominantly in the perivenous zone, remains mostly unaffected. These data suggest that 'selective insulin resistance' is induced by the differential distribution, and alterations of hepatic Irs1 and Irs2 expression.

[Insulin/IGF-1 signaling and aging]

Insulin and IGF-1 have a high similarity in structure and play pivotal roles in regulation of aging and longevity. Insulin is bound to insulin receptor on cell surface, whereas IGF-1 is bound to IGF1R, but the molecules to transduce intracellular signals are almost identical, including Akt and FoxO. Akt is a kinase to regulate growth and metabolism in various tissues, and among the substrates, FoxO is one of the key transcription factors to regulate expression of a number or genes, including anti-oxidative enzymes. Akt phosphorylates FoxO and sup- presses its activity by promoting translocation to cytoplasm. In yeast, worms and flies, it is known that various mutations to impair insulin/IGF-1 signaling prolong longevity, potentially via activation of FoxO. In mice, however, longevity was prolonged in some models with disrup- tion of insulin/IGF-1 signaling-related genes, whereas it was shortened in others. Moreover, in many cases, prolonged longevity was accompanied by growth retardation or metabolic disorders, which means that they did not live a 'long and healthy' life. It is still controversial whether suppression of insulin/IGF-1 signaling is beneficial in terms of aging also in mammalians.

Design of and rationale for the Japan Diabetes Optimal Integrated Treatment study for 3 major risk factors of cardiovascular diseases (J-DOIT3): a multicenter, open-label, randomized, parallel-group trial

OBJECTIVE

Multifactorial intervention including the management of levels of blood glucose (BG), blood pressure (BP), and lipids has been suggested to decrease cardiovascular disease (CVD) risk. However, the target ideal and feasible levels for these individual parameters have not been fully evaluated. In this study, we examine the hypothesis that stricter control compared with the current targets in the Japanese guideline for BG, BP, and lipids could efficiently and safely reduce CVD risk.

RESEARCH DESIGN AND METHODS

We screened patients with type 2 diabetes and hypertension and/or dyslipidemia among 81 hospitals in Japan and allocated them into 2 groups: the intensive therapy group (ITG) and the conventional therapy group (CTG). For the 2 respective groups, the target for glycated hemoglobin (HbA1c) is <6.2% (44 mmol/mol) and <6.9% (52 mmol/mol), for BP it is <120/75 mm Hg and <130/80 mm Hg, and for low-density lipoprotein cholesterol it is <80 mg/dL (<70 mg/dL in the presence of CVD history) and <120 mg/dL (<100 mg/dL in the presence of CVD history). The primary end point is the occurrence of CVD events or death by any cause. These patients are scheduled for stepwise intensifications of medication for BG, BP, and lipid control in the ITG, until the number of primary end point events reaches 250.

RESULTS

We recruited 2542 patients and randomly allocated 1271 into the ITG and 1271 into the CTG between June 2006 and March 2009. The mean HbA1c was 8.0% (64 mmol/mol) and the mean duration of diabetes was 8.3 years.

CONCLUSIONS

This randomized controlled study will test the hypothesis that strict multifactorial intervention therapy is effective for the prevention of CVDs in patients with type 2 diabetes who are at high CVD risk.

TRIAL REGISTRATION NUMBER

NCT00300976.

Impaired insulin signaling in endothelial cells reduces insulin-induced glucose uptake by skeletal muscle

In obese patients with type 2 diabetes, insulin delivery to and insulin-dependent glucose uptake by skeletal muscle are delayed and impaired. The mechanisms underlying the delay and impairment are unclear. We demonstrate that impaired insulin signaling in endothelial cells, due to reduced Irs2 expression and insulin-induced eNOS phosphorylation, causes attenuation of insulin-induced capillary recruitment and insulin delivery, which in turn reduces glucose uptake by skeletal muscle. Moreover, restoration of insulin-induced eNOS phosphorylation in endothelial cells completely reverses the reduction in capillary recruitment and insulin delivery in tissue-specific knockout mice lacking Irs2 in endothelial cells and fed a high-fat diet. As a result, glucose uptake by skeletal muscle is restored in these mice. Taken together, our results show that insulin signaling in endothelial cells plays a pivotal role in the regulation of glucose uptake by skeletal muscle. Furthermore, improving endothelial insulin signaling may serve as a therapeutic strategy for ameliorating skeletal muscle insulin resistance.

Generation of transgenic mice on an NOD/SCID background using the conventional microinjection technique

Humanized mice, which refers to immunodeficient mice repopulated with the human immune system, are powerful tools for study in the field of immunology. It has been difficult, however, to generate these transgenic (Tg) mice directly from such strains as the NOD/SCID mouse. In this study, we describe a method developed by us for the generation of Tg mice on an NOD/SCID background. First, we obtained fertilized eggs efficiently by means of in vitro fertilization (IVF); then, we attempted to generate CAG-EGFP Tg mice on an NOD/SCID background, finding that delayed timing of the microinjection after the IVF improved the time to development of the two-cell-stage embryos and the obtainment of newborns. We successfully generated Tg mice and confirmed the germ-line transmission in the offspring. In conclusion, we established a novel system for directly generating transgenic mice on an NOD/SCID background. This novel system is expected to allow improved efficiency of the generation of humanized mice.

Dynamic functional relay between insulin receptor substrate 1 and 2 in hepatic insulin signaling during fasting and feeding

Insulin receptor substrate (Irs) mediates metabolic actions of insulin. Here, we show that hepatic Irs1 and Irs2 function in a distinct manner in the regulation of glucose homeostasis. The PI3K activity associated with Irs2 began to increase during fasting, reached its peak immediately after refeeding, and decreased rapidly thereafter. By contrast, the PI3K activity associated with Irs1 began to increase a few hours after refeeding and reached its peak thereafter. The data indicate that Irs2 mainly functions during fasting and immediately after refeeding, and Irs1 functions primarily after refeeding. In fact, liver-specific Irs1-knockout mice failed to exhibit insulin resistance during fasting, but showed insulin resistance after refeeding; conversely, liver-specific Irs2-knockout mice displayed insulin resistance during fasting but not after refeeding. We propose the concept of the existence of a dynamic relay between Irs1 and Irs2 in hepatic insulin signaling during fasting and feeding.