Role of Insulin Resistance in MAFLD.

Many studies have reported that metabolic dysfunction is closely involved in the complex mechanism underlying the development of non-alcoholic fatty liver disease (NAFLD), which has prompted a movement to consider renaming NAFLD as metabolic dysfunction-associated fatty liver disease (MAFLD). Metabolic dysfunction in this context encompasses obesity, type 2 diabetes mellitus, hypertension, dyslipidemia, and metabolic syndrome, with insulin resistance as the common underlying pathophysiology. Imbalance between energy intake and expenditure results in insulin resistance in various tissues and alteration of the gut microbiota, resulting in fat accumulation in the liver. The role of genetics has also been revealed in hepatic fat accumulation and fibrosis. In the process of fat accumulation in the liver, intracellular damage as well as hepatic insulin resistance further potentiates inflammation, fibrosis, and carcinogenesis. Increased lipogenic substrate supply from other tissues, hepatic zonation of Irs1, and other factors, including ER stress, play crucial roles in increased hepatic de novo lipogenesis in MAFLD with hepatic insulin resistance. Herein, we provide an overview of the factors contributing to and the role of systemic and local insulin resistance in the development and progression of MAFLD.

TCF7L2 in mouse pancreatic beta cells plays a crucial role in glucose homeostasis by regulating beta cell mass.

AIMS/HYPOTHESIS: Common genetic variations of the transcription factor 7-like 2 gene (encoded by TCF7L2), one of the T cell factor/lymphoid enhancer-binding factor transcription factors for the converging wingless-type MMTV integration site family (Wnt)/ß-catenin signalling pathway, are known to be associated with type 2 diabetes. Individuals with at-risk alleles of TCF7L2 exhibit impaired insulin secretion. Although previous studies using animal models have revealed the existence of a relationship between the Wnt/ß-catenin signalling pathway and glucose homeostasis, it remains unclear whether TCF7L2 in the pancreatic beta cells might be causally involved in insulin secretion in vivo. In this study, we investigated the role of TCF7L2 expressed in the pancreatic beta cells in glucose homeostasis. METHODS: Three independent groups of genetically engineered mice (DN mice) were generated, in which expression of the dominant-negative form of Tcf7l2 was driven under a rat insulin promoter. Phenotypes of both adult and newborn mice were evaluated. The levels of genes and proteins expressed in isolated islets were determined by reverse transcription-quantitative PCR and western blot analysis, respectively. RESULTS: Adult DN mice showed impaired glucose tolerance and decreased insulin secretion in both oral and intraperitoneal glucose tolerance tests. Marked reduction of the beta cell area and whole-pancreas insulin content was observed in both the adult and newborn DN mice. Islets from the DN mice showed decreased gene expressions of Ccnd1, Ccnd2, Irs1, Irs2, Ins1, Ins2 and Mafa, consistent with the deleterious effects of the dominant-negative form of Tcf7l2 on beta cell proliferation and insulin production. CONCLUSIONS/INTERPRETATION: TCF7L2 expressed in the pancreatic beta cells plays a crucial role in glucose metabolism through regulation of the beta cell mass.

Overexpression of UBE2E2 in Mouse Pancreatic ß-Cells Leads to Glucose Intolerance via Reduction of ß-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 ß-cell-specific UBE2E2-transgenic (TG) mice exhibited reduced insulin secretion and decreased ß-cell mass. In TG mice, suppressed proliferation of ß-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 ß-cell mass expansion and compensatory ß-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 ß-cells play an important role in regulating glucose homeostasis and ß-cell mass.

Bi-weekly Glycated Albumin Measurement was Useful to Encourage Behavioral Changes in People with Type 2 Diabetes Mellitus.

INTRODUCTION: Hemoglobin A1c (HbA1c), representing the average blood glucose over 1-2 months, is the most commonly used glycemic marker in people with diabetes. Glycated albumin (GA) reflects the average blood glucose over the most recent 1-2 weeks. We considered whether the faster response of GA compared with HbA1c could make people with diabetes realize their glycemic control intuitively and effectively. METHODS: We randomized 61 people with diabetes into the control and intervention groups. Blood samples were collected from both every fortnight over an 8-week period (five times; visit 1-5). Only the intervention group was notified of the GA levels on the same day. At the beginning and end of the study, International Physical Activity Questionnaire and Eating Behavior Questionnaire assessments, and body composition measurements were conducted. RESULTS: The body weight change was significantly lower in the intervention group at visit 2 and visit 5. The percent body fat change was lower, while the percent skeletal muscle mass change at visit 5 was higher in the intervention group. Increasing GA trend was observed in the control group, but not in the intervention group. The fasting plasma glucose and HbA1c changes at visit 5 were similar in the two groups. Physical activity level change tended to be higher in the intervention group. The YN Eating Behavior Questionnaire score changes were similar in the two groups. CONCLUSION: Bi-weekly GA measurement over an 8-week period in people with type 2 diabetes induced behavioral changes. Development of this method is expected to improve diabetes management. TRIAL REGISTRATION: UMIN000037795.

Associations of sleep quality with the skeletal muscle strength in patients with type 2 diabetes with poor glycemic control.

AIMS/INTRODUCTION: Patients with type 2 diabetes mellitus are reported to be at a high risk for sarcopenia, and are known to have a poorer sleep quality. However, the association between sleep quality and skeletal muscle in patients with type 2 diabetes mellitus is not yet precisely understood. MATERIALS AND METHODS: A total of 110 inpatients with type 2 diabetes mellitus aged 40-90 years were enrolled. The sleep quality was assessed using the Pittsburgh sleep quality index (PSQI). Skeletal muscle mass was measured using bioelectrical impedance analysis. Muscle strength was evaluated by measuring the grip strength. We also performed dietary surveys and measurements of the plasma amino acid levels. RESULTS: A high total score on the PSQI was significantly associated with reduced muscle strength, and the association persisted even after adjustments for confounders. On the other hand, adjusted analysis did not reveal any significant associations between the PSQI total score and the skeletal muscle mass. In regard to the associations with subscores of the PSQI, the scores for sleep latency, sleep efficiency, and daytime dysfunction were significantly negatively associated with the muscle strength. Although poor sleep quality was associated with a high confectionery intake and low plasma arginine, citrulline, and ornithine levels, neither confectionery intake levels nor the plasma levels of these amino acids was associated with the muscle strength. CONCLUSIONS: Our study revealed a significant association between the sleep quality and muscle strength in patients with type 2 diabetes mellitus. These results suggest that poor sleep quality is an important risk factor for sarcopenia in patients with type 2 diabetes mellitus.

Evaluation of glycated albumin levels in tears and saliva as a marker in patients with diabetes mellitus.

AIMS: Glycated albumin (GA) is a biomarker, whose level reflects glycemic control status over the previous 2 weeks. To develop a non-invasive method for evaluating glycemic control in people with diabetes mellitus, we investigated the measurement of GA levels in tears and saliva, which could be collected noninvasively. METHODS: Tear and saliva samples were collected from 48 participants with diabetes mellitus. The GA levels in the tear and saliva specimens were measured by Liquid Chromatography-Mass Spectrometry (LC-MS/MS). RESULTS: GA levels in both tear and saliva samples were significantly correlated with the GA levels in the blood (P < 0.001). Multiple regression analysis revealed that these correlations were maintained even after adjustments for the BMI, age, and nephropathy stage (P < 0.001). CONCLUSION: GA levels in tear and saliva specimens, as diabetes-related biomarkers, can be measured non-invasively. Since this measurement can be performed noninvasively and not as frequently as compared with the more invasive finger prick method, it is expected to reduce the burden on people with diabetes in terms of both the invasiveness and cost-effectiveness. In the future, we would like to verify the effect of regular GA measurement on the glycemic control while considering the clinical cost-effectiveness.

Toward sensor-based context aware systems.

This paper proposes a methodology for sensor data interpretation that can combine sensor outputs with contexts represented as sets of annotated business rules. Sensor readings are interpreted to generate events labeled with the appropriate type and level of uncertainty. Then, the appropriate context is selected. Reconciliation of different uncertainty types is achieved by a simple technique that moves uncertainty from events to business rules by generating combs of standard Boolean predicates. Finally, context rules are evaluated together with the events to take a decision. The feasibility of our idea is demonstrated via a case study where a context-reasoning engine has been connected to simulated heartbeat sensors using prerecorded experimental data. We use sensor outputs to identify the proper context of operation of a system and trigger decision-making based on context information.

The sodium-glucose co-transporter 2 inhibitor tofogliflozin suppresses atherosclerosis through glucose lowering in ApoE-deficient mice with streptozotocin-induced diabetes.

Epidemiological and animal studies have revealed that sodium-glucose cotransporter 2 (SGLT2) inhibitors suppress cardiovascular events in subjects with type 2 diabetes and atherosclerosis in animal models of diabetes. However, it still remains unclear if the anti-atherosclerotic effect of SGLT2 inhibitors is entirely dependent on their glucose-lowering effect. Tofogliflozin, a highly specific SGLT2 inhibitor, was administrated to apolipoprotein-E-deficient (ApoEKO) with streptozotocin (STZ)-induced diabetes and nondiabetic ApoEKO mice. After 6 weeks, samples were collected to investigate the histological changes and peritoneal macrophage inflammatory cytokine levels. Tofogliflozin suppressed atherosclerosis in the diabetic ApoEKO mice. The atherosclerosis lesion areas and accumulation of macrophages in these areas were reduced by tofogliflozin treatment. The expression levels of interleukin (IL)-1ß and IL-6 in the peritoneal macrophages were significantly suppressed in the tofogliflozin-treated diabetic ApoEKO mice. Tofogliflozin treatment failed to inhibit atherosclerosis in the nondiabetic ApoEKO mice. No significant difference in the anti-atherosclerotic effects of insulin and tofogliflozin was observed between diabetic ApoEKO mice with equivalent degrees of glycemic control achieved with the two treatments. Insulin treatment significantly reduced the IL-1ß and IL-6 expression levels in the peritoneal macrophages of the diabetic ApoEKO mice. Significant decrease of the LPS-stimulated IL-1ß concentrations was also observed in the conditioned medium of the peritoneal macrophages collected from insulin- and tofogliflozin-treated diabetic ApoEKO mice. These results suggest that tofogliflozin suppresses atherosclerosis by improving glucose intolerance associated with inhibition of inflammation. Tofogliflozin suppresses atherosclerosis in ApoEKO mice with STZ-induced diabetes via its glucose-lowering effect.

Chronic Intestinal Pseudo-obstruction with Mitochondrial Diseases.

Chronic intestinal pseudo-obstruction (CIPO) is a rare disorder of intestinal dysmotility characterized by chronic symptoms, including vomiting and abdominal pain, associated with bowel obstruction without any mechanical obstructive causes. We herein report a case of mitochondrial diseases with recurrent duodenal obstruction that was initially diagnosed as superior mesenteric artery syndrome (SMAS) for a few years but was later diagnosed as CIPO. Since CIPO is known to be associated with mitochondrial diseases, it should be considered in the differential diagnosis of patients with mitochondrial diseases presenting with recurrent intestinal obstruction.

Counseling (ro)bot as a use case for 5G/6G.

This paper presents a counseling (ro)bot called Visual Counseling Agent (VICA) which focuses on remote mental healthcare. It is an agent system leveraging artificial intelligence (AI) to aid mentally distressed persons through speech conversation. The system terminals are connected to servers by the Internet exploiting Cloud-nativeness, so that anyone who has any type of terminal can use it from anywhere. Despite a promising voice communication interface, VICA shows limitations in conversation continuity on conventional 4G networks. Concretely, the use of the current 4G networks produces word dropping, delayed response, and the occasional connection failure. The objective of this paper is to mitigate these issues by leveraging a 5G/6G slice inclusive of mobile/multiple edge computing (MEC). First, we propose and partly implement the enhanced and advanced version of VICA. Servers of enhanced versions collaborate to increase speech recognition reliability. Although it significantly increases generated data volume, the advanced version enables a recognition of the facial expressions to greatly enhance counseling quality. Then, we propose a quality assurance mechanism using multiple levels of catalog, as well as 5G/6G slice inclusive of MEC, and conduct experiments to uncover issues related to the 4G. Results indicate that the number of speech recognition errors in Internet Cloud is more than twofold compared to edge computing, implying that quality assurance using 5G/6G in conjunction with VICA Counseling (ro)bot has higher efficiency.

Lack of Brain Insulin Receptor Substrate-1 Causes Growth Retardation, With Decreased Expression of Growth Hormone-Releasing Hormone in the Hypothalamus.

Insulin receptor substrate-1 (Irs1) is one of the major substrates for insulin receptor and insulin-like growth factor-1 (IGF-1) receptor tyrosine kinases. Systemic Irs1-deficient mice show growth retardation, with resistance to insulin and IGF-1, although the underlying mechanisms remain poorly understood. For this study, we generated mice with brain-specific deletion of Irs1 (NIrs1KO mice). The NIrs1KO mice exhibited lower body weights, shorter bodies and bone lengths, and decreased bone density. Moreover, the NIrs1KO mice exhibited increased insulin sensitivity and glucose utilization in the skeletal muscle. Although the ability of the pituitary to secrete growth hormone (GH) remained intact, the amount of hypothalamic growth hormone-releasing hormone (GHRH) was significantly decreased and, accordingly, the pituitary GH mRNA expression levels were impaired in these mice. Plasma GH and IGF-1 levels were also lower in the NIrs1KO mice. The expression levels of GHRH protein in the median eminence, where Irs1 antibody staining is observed, were markedly decreased in the NIrs1KO mice. In vitro, neurite elongation after IGF-1 stimulation was significantly impaired by Irs1 downregulation in the cultured N-38 hypothalamic neurons. In conclusion, brain Irs1 plays important roles in the regulation of neurite outgrowth of GHRH neurons, somatic growth, and glucose homeostasis.

Association between tear and blood glucose concentrations: Random intercept model adjusted with confounders in tear samples negative for occult blood.

AIMS/INTRODUCTION: To prevent diabetic complications, strict glucose control and frequent monitoring of blood glucose levels with invasive methods are necessary. We considered the monitoring of tear glucose levels might be a possible method for non-invasive glucose monitoring. To develop tear glucose monitoring for clinical application, we investigated the precise correlation between the blood and tear glucose concentrations. MATERIALS AND METHODS: A total of 10 participants and 20 participants with diabetes were admitted, and blood and tear samples were collected. Before statistical analysis, we eliminated tear samples contaminated with blood. We observed the daily blood and tear glucose dynamics, and carried out a random intercept model analysis to examine the association between the blood and tear glucose concentrations. RESULTS: Tear occult blood tests showed that the tear glucose concentrations and their variation increased in both participants with and without diabetes as contamination of blood increased. In both participants with and without diabetes, fluctuations of the plasma glucose concentrations were observed depending on the timing of collection of the samples, and the dynamics of the tear glucose concentrations paralleled those of the plasma glucose concentrations. The random intercept model analysis showed a significant association between the plasma and tear glucose concentrations in participants with diabetes (P < 0.001). This association still existed even after adjusting for the glycated hemoglobin levels and the prandial state (P < 0.001). CONCLUSIONS: It is important to eliminate the tear samples contaminated with blood. Tear glucose monitoring might be a reliable and non-invasive substitute method for monitoring the blood glucose concentrations for diabetes patients, irrespective of glycated hemoglobin levels and timing of sample collection.

Role of insulin receptor substrates in the progression of hepatocellular carcinoma.

Several cellular signaling pathways, including insulin/IGF signaling, are known to be activated in hepatocellular carcinoma (HCC). Here, we investigated the roles of insulin receptor substrate (Irs) 1 and Irs2, both of which are the major molecules to be responsible for transducing insulin/IGF signaling in the liver, in the development of HCC by inducing chemical carcinogenesis using diethylnitrosamine (DEN) in mice. The Irs1 mRNA and protein expressions were upregulated in the tumors, along with enhanced insulin signaling. Liver-specific Irs1-knockout (LIrs1KO) mice exhibited suppression of DEN-induced HCC development, accompanied by reduced cancer cell proliferative activity and reduced activation of Akt. Gene expression analyses revealed that the tumors in the DEN-treated LIrs1KO mice showed modest metabolic alterations during hepatocarcinogenesis as well as decreased inflammation and invasion potentials. On the other hand, liver-specific Irs2-knockout (LIrs2KO) mice showed a similar pattern of HCC development to the DEN-treated control wild-type mice. Based on the knowledge that Wnt/ß-catenin signaling is activated in HCC, we focused on Wnt/ß-catenin signaling and demonstrated that Irs1 expression was induced by Wnt3a stimulation in the primary hepatocytes, associated with insulin-stimulated Akt activation. These data suggest that upregulated Irs1 by Wnt/ß-catenin signaling plays a crucial role in the progression of HCC.

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.

Tofogliflozin Improves Insulin Resistance in Skeletal Muscle and Accelerates Lipolysis in Adipose Tissue in Male Mice.

Sodium glucose cotransporter 2 inhibitors have attracted attention as they exert antidiabetic and antiobesity effects. In this study, we investigated the effects of tofogliflozin on glucose homeostasis and its metabolic consequences and clarified the underlying molecular mechanisms. C57BL/6 mice were fed normal chow containing tofogliflozin (0.005%) for 20 weeks or a high-fat diet containing tofogliflozin (0.005%) for 8 weeks ad libitum. In addition, the animals were pair-fed in relation to controls to exclude the influence of increased food intake. Tofogliflozin reduced the body weight gain, mainly because of fat mass reduction associated with a diminished adipocyte size. Glucose tolerance and insulin sensitivity were ameliorated. The serum levels of nonesterified fatty acid and ketone bodies were increased and the respiratory quotient was decreased in the tofogliflozin-treated mice, suggesting the acceleration of lipolysis in the white adipose tissue and hepatic ß-oxidation. In fact, the phosphorylation of hormone-sensitive lipase and the adipose triglyceride lipase protein levels in the white adipose tissue as well as the gene expressions related to ß-oxidation, such as Cpt1α in the liver, were significantly increased. The hepatic triglyceride contents and the expression levels of lipogenic genes were decreased. Pair-fed mice exhibited almost the same results as mice fed an high-fat diet ad libitum. Moreover, a hyperinsulinemic-euglycemic clamp revealed that tofogliflozin improved insulin resistance by increasing glucose uptake, especially in the skeletal muscle, in pair-fed mice. Taken together, these results suggest tofogliflozin ameliorates insulin resistance and obesity by increasing glucose uptake in skeletal muscle and lipolysis in adipose tissue.