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Insulin like growth factor-1 (IGF-1) plays important roles in metabolic functions, especially in adulthood. Additionally, obese subjects are reportedly predisposed to having low absolute IGF-1 levels. However, the prevalence and clinical characteristics of obese subjects with low IGF-1 levels are unknown. We examined 64 severely obese subjects (body mass index (BMI) ≥ 35 kg/m2), with no history of endocrinological disorders, receiving inpatient care. IGF-1 levels were interpreted based on the IGF-1 standard deviation score (SDS) clinically used and standardized by age and sex (low IGF-1 group; ≤ -2.0 SDS and standard IGF-1 group; -2.0 < and < +2.0 SDS). Notably, 26.6% of severely obese subjects had low IGF-1. Body fat mass and percentage, but not BMI, were significantly higher in the low than in the standard IGF-1 group. Furthermore, natural log-transformed high-sensitivity C-reactive protein, and the frequencies of dyslipidemia and hyperuricemia were higher in the low IGF-1 group. Moreover, among the subjects without diabetes, fasting glucose levels were significantly higher in the low IGF-1 group. Stepwise variable selection procedure revealed body fat percentage to be a parameter most strongly associated with low IGF-1. Thus, low IGF-1 levels may be an important marker of adiposity-associated metabolic disorders in severely obese patients.

In insulin-resistant states such as obesity, pancreatic β-cells proliferate to prevent blood glucose elevations. Failure of this β-cells proliferative response leads to the development of diabetes. On the other hand, when organs are damaged, cells proliferate to repair the organs. Therefore, these proliferations are compensatory mechanisms aimed at maintaining whole-body homeostasis. We previously discovered vagal signal-mediated systems regulating adaptive proliferation of β-cells and hepatocytes. Neuron-mediated liver-β-cell inter-organ crosstalk is involved in promotion of β-cell proliferation during obesity, and in this system, vagal signals directly stimulate β-cell proliferation. Meanwhile, in the liver, the multi-step mechanisms whereby vagal nerve signals activate hepatic resident macrophages are involved in hepatocyte proliferation after severe injury. Diabetes mellitus develops on the pathological basis of insufficient insulin action. Insulin action insufficiency is attributable to insulin resistance, i.e., the failure of insulin to exert sufficient effects, and/or to impairment of insulin secretion. Impairment of insulin secretion is attributable not only to the β-cell dysfunction but also to functional β-cell mass reduction. In this regard, there are already therapeutic options to increase insulin secretion from residual β-cells, such as sulfonyl urea and incretin-related drugs. In contrast, there are as yet no applicable therapeutic strategies to increase functional β-cell mass in vivo. Therefore, we have conducted the basic investigations to tackle this issue based on the discovery of neuron-mediated liver-β-cell inter-organ crosstalk. This review introduces vagal signal-mediated regulatory systems of adaptive cell proliferation in vivo and efforts to develop cell-increasing therapies based on vagal nerve-mediated cell proliferation.

Autonomic nerves, including sympathetic nerves and parasympathetic nerves, innervate organs and modulate those function, thereby regulating systemic metabolism. Autonomic nerve bundles contain both afferent and efferent nerve fibers, and both fibers play important roles in regulating systemic metabolism for maintenance of homeostasis at the whole-body level. Furthermore, recently-obtained evidence unraveled the metabolic regulatory systems through autonomic nerve-mediated inter-organ networks. In these systems, afferent innervations of autonomic nerves transmit metabolic information from peripheral organs to the central nervous system (CNS), and the CNS regulates organ functions based on the transmitted metabolic information through efferent innervations of autonomic nerves. In this review, autonomic nerve-mediated inter-organ networks that are involved in systemic metabolism are introduced, especially focusing on the liver-brain-pancreatic β-cell inter-organ network.

Autonomic nerves, sympathetic and parasympathetic, innervate organs and modulate their functions. It has become evident that afferent and efferent signals of the autonomic nervous system play important roles in regulating systemic metabolism, thereby maintaining homeostasis at the whole-body level. Vagal afferent nerves receive signals, such as nutrients and hormones, from the peripheral organs/tissues including the gastrointestinal tract and adipose tissue then transmit these signals to the hypothalamus, thereby regulating feeding behavior. In addition to roles in controlling appetite, areas in the hypothalamus serve as regulatory centers of both sympathetic and parasympathetic efferent fibers. These efferent innervations regulate the functions of peripheral organs/tissues, such as pancreatic islets, adipose tissues and the liver, which play roles in metabolic regulation. Furthermore, recent evidence has unraveled the metabolic regulatory systems governed by autonomic nerve circuits. In these systems, afferent nerves transmit metabolic information from peripheral organs to the central nervous system (CNS) and the CNS thereby regulates the organ functions through the efferent fibers of autonomic nerves. Thus, the autonomic nervous system regulates the homeostasis of systemic metabolism, and both afferent and efferent fibers play critical roles in its regulation. In addition, several lines of evidence demonstrate the roles of the autonomic nervous system in regulating and dysregulating the immune system. This review introduces variety of neuron-mediated inter-organ cross-talk systems and organizes the current knowledge of autonomic control/coordination of systemic metabolism, focusing especially on a liver–brain–pancreatic β-cell autonomic nerve circuit, as well as highlighting the potential importance of connections with the neuronal and immune systems.

Background A high-molecular-weight form of insulin-like growth factor-2 (IGF-2), known as “big” IGF-2, is occasionally produced by various tumor types, leading to hypoglycemia. Although solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm, it has been estimated that 4–6% of SFT patients develop hypoglycemia due to circulating big IGF-2. The mean time elapsed from tumor detection until the onset of hypoglycemia is reportedly less than one year (8.5 ± 1.9 months). Case presentation A 68-year-old man was hospitalized for exacerbation of recurring hypoglycemic episodes. He had been diagnosed with an SFT 17 years before the onset of hypoglycemia, and the SFT had already been very large at that time. The tumor, which was non-resectable and refractory to chemotherapies, had slowly increased in size since the initial diagnosis. Half a year before the hypoglycemic episodes manifested, another tumor, adjacent to the left kidney, was newly identified. Fluorodeoxyglucose positron emission tomography-computed tomography scanning, revealed the left peri-renal tumor to show much higher fluorodeoxyglucose uptake than the preexisting SFT, suggesting that it was unlikely to be a metastasis from the SFT. Abundant serum big IGF-2 was detected by western immunoblot analysis, indicating it to be the cause of the hypoglycemia. Since the 17 years between SFT detection and the onset of IGF-2-induced hypoglycemia was an extremely long period as compared with those in previous reports, we initially suspected that the new, peri-renal tumor had produced big IGF-2, but transcatheter arterial embolization of its feeding arteries did not suppress hypoglycemia. Notably, by measuring the tumor volume doubling time, the peri-renal tumor growth was shown to be markedly accelerated in parallel with exacerbation of the hypoglycemia. The patient died of heart failure 21 months after the onset of hypoglycemia. Unexpectedly, autopsy revealed that big IGF-2 had been produced only by the preexisting SFT, not the peri-renal tumor, and that the peri-renal tumor was a dedifferentiated liposarcoma. Conclusions We should keep in mind that even a long-inactive SFT can undergo transformation to produce big IGF-2, which then acts on both insulin and IGF-1 receptors, possibly leading to both hypoglycemia and the development/growth of another tumor, respectively.

Bariatric surgery is associated with a high remission rate of type 2 diabetes mellitus. However, it is unclear whether patients showing remission of diabetes actually have normal blood glucose levels throughout the day. We therefore performed continuous glucose monitoring (CGM) in 15 ambulatory patients showing remission of diabetes after laparoscopic sleeve gastrectomy (LSG) without or with duodenojejunal bypass (DJB) at the time of diabetic remission (12.9 ± 1.8 months after bariatric surgery). The definition of remission of diabetes was based on the American Diabetes Association criteria. The mean, SD, and coefficient of variation (CV) of glucose calculated from CGM were 6.2 ± 0.6 mmol/L, 1.5 ± 0.4 mmol/L, and 23.7 ± 6.2%, respectively. These values were higher than those of healthy participants without diabetes previously reported. The percentages of time spent above 10.0 mmol/L and below 3.9 mmol/L were 2.6 (IQR 0-5.0)% and 0 (IQR 0-8.0)%, respectively. Thus, patients with remission of diabetes after LSG or LSG/DJB still had substantial periods of hyperglycemia and hypoglycemia throughout the day. Therefore, we must manage patients with diabetes carefully, even after apparent remission of type 2 diabetes in response to bariatric surgery.

Soft-drink diabetic ketosis, characterized by acute onset ketosis induced by excessive ingestion of sugar-containing drinks, is often seen in obese, young patients, even with undiagnosed type 2 diabetes. We herein report a 15-year-old obese patient with the apolipoprotein E4/2 phenotype, in whom eruptive xanthomas lead to a diagnosis of soft-drink diabetic ketosis. He developed multiple asymptomatic yellowish papules on the auricles, back, buttocks and the extensor surfaces of the elbows and knees. He initially visited a dermatology clinic and his blood triglyceride and HbA1c levels were found to be 6,490 mg/dL and 16.5%, respectively. He was referred to our hospital for treatment of hyperglycemia and hypertyriglyceridemia. On admission, he had ketonuria and increased blood levels of 3-hydroxybutylate and acetoacetate. He habitually drank 1-3 litters of sweet beverages daily to quench his thirst. Therefore, "soft-drink diabetic ketosis" was diagnosed. Severe hypertriglyceridemia was considered to have been a consequence of impaired insulin action and his apolipoprotein E4/2 phenotype. We treated the diabetic ketosis and hypertriglyceridemia with intensive insulin therapy and a fat-restricted diet. At discharge, he no longer required insulin therapy and his blood glucose levels were controlled with metformin and voglibose. Along with amelioration of the hyperglycemia, triglyceride levels decreased to 247 mg/dL without administration of anti-hyperlipidemia agents. The eruptive xanthoma lesions gradually diminished in size and number and eventually disappeared by 12 months. This case provides an instructive example of eruptive xanthomas serving as a sign of severe dysregulation, not only of lipid, but also glucose, metabolism.

The liver possesses a high regenerative capacity. Liver regeneration is a compensatory response overcoming disturbances of whole-body homeostasis provoked by organ defects. Here we show that a vagus-macrophage-hepatocyte link regulates acute liver regeneration after liver injury and that this system is critical for promoting survival. Hepatic Foxm1 is rapidly upregulated after partial hepatectomy (PHx). Hepatic branch vagotomy (HV) suppresses this upregulation and hepatocyte proliferation, thereby increasing mortality. In addition, hepatic FoxM1 supplementation in vagotomized mice reverses the suppression of liver regeneration and blocks the increase in post-PHx mortality. Hepatic macrophage depletion suppresses both post-PHx Foxm1 upregulation and remnant liver regeneration, and increases mortality. Hepatic Il-6 rises rapidly after PHx and this is suppressed by HV, muscarinic blockade or resident macrophage depletion. Furthermore, IL-6 neutralization suppresses post-PHx Foxm1 upregulation and remnant liver regeneration. Collectively, vagal signal-mediated IL-6 production in hepatic macrophages upregulates hepatocyte FoxM1, leading to liver regeneration and assures survival., The mechanisms underlying the regenerative capacity of the liver are not fully understood. Here, the authors show that the acute regenerative response to liver injury in mice is regulated by the communication involving the vagus nerve, macrophages, and hepatocytes, leading to hepatic FoxM1 activation and promotion of overall survival.

The prevalence of type 2 diabetes increases with aging, and the type 2 diabetes developing in the elderly is often accompanied by a gradual impairment of β-cell function and reduced β-cell mass along with aging. However, the contribution of β-cell senescence to the pathogenesis of type 2 diabetes remains uncertain. In a recent Cell Metabolism article, Aguayo-Mazzucato et al. described their efforts to identify the signatures of senescent β-cells, and explored the role(s) of senescent β-cells in type 2 diabetes.

Aims Detection of early-stage atherosclerosis in type 2 diabetes mellitus (T2DM) patients is important for preventing cardiovascular disease. A phased tracking method for evaluating arterial wall elasticity sensitively detects early-stage atherosclerosis. However, biochemical markers for early-stage atherosclerosis have yet to be established. Methods This cross-sectional study enrolled 180 T2DM patients, who were classified as not having atherosclerosis according to the carotid intima-media thickness (IMT) criteria. We measured serum cystatin C, the estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (ACR), and analyzed the associations between these markers and arterial wall elasticity (Eθ), IMT and the cardio-ankle velocity index. Results Multiple linear regression analyses revealed that cystatin C was significantly associated with Eθ, while neither eGFR nor ACR showed an association. Furthermore, among the examined atherosclerotic markers, Eθ was most reliably associated with cystatin C. Additionally, the association between cystatin C and Eθ disappeared in the low elasticity subgroup, which included subjects in whom no atherosclerotic changes had yet been initiated. Conclusions In T2DM patients without apparent arterial wall thickening, cystatin C is strongly and independently associated with arterial wall elasticity, which reflects the degree of subclinical atherosclerosis. Thus, cystatin C is a potentially useful marker of early-stage atherosclerosis.

In insulin-resistant states such as obesity, pancreatic β-cells proliferate to prevent blood glucose elevations. However, the mechanism(s) by which obesity induces compensatory β-cell responses is not fully understood. Recently, several studies have shown that signals from the liver, such as neuronal signals or humoral factors, regulate β-cell proliferation during obesity development. We previously reported a liver-brain-pancreas neuronal relay, consisting of afferent splanchnic nerves, the central nervous system and efferent vagal nerves, to promote this compensatory β-cell proliferation. Furthermore, we recently clarified the molecular mechanisms by which efferent vagal signals induce β-cell proliferation in this inter-organ neuronal network system. Herein, these liver-β-cell inter-organ networks are reviewed, focusing mainly on the neuronal network. The significance of the neuronal network system in the maintenance of glucose homeostasis is also discussed with reference to the relevant literature.

Aims Evaluation of the retinal microcirculation is key to understanding retinal vasculopathies, such as diabetic retinopathy. Laser speckle flowgraphy (LSFG) has recently enabled us to directly evaluate the vascular resistance in both retinal vessels and capillaries, non-invasively. We therefore assessed whether retinal vessel blood flow and/or the capillary microcirculation are associated with blood flow in the cervical arteries in diabetic patients without severe retinopathy. Methods We enrolled 110 type 2 diabetes patients, with no or mild non-proliferative diabetic retinopathy, in this prospective cross-sectional study. We measured the resistivity indices (RIs) of the retinal vessel and capillaries by LSFG and those of cervical arteries by Doppler ultrasonography, followed by analyzing associations. Results The RIs of not only the carotid but also vertebral arteries were associated with those of retinal vessel blood flow and the retinal capillary microcirculation. Multiple regression analyses revealed these associations to be independent of other explanatory variables including age and diabetes duration. Conclusions We obtained novel and direct evidence demonstrating a close association between the retinal microcirculation and cervical artery hemodynamics in diabetic patients. These findings suggest shared mechanisms to underlie micro- and macro-angiopathies. Thus, high vascular resistance of cervical arteries may be a risk of developing retinopathy.

Additional file 1. Uncropped western immunoblot image related to Fig. 1c.

Additional file 2. Procedure of protein extraction and immunoblot analysis and information of antibodies for immunoblotting and immunohistochemistry.

Leptin resistance is an important mechanism underlying the development and maintenance of obesity and is thus regarded as a promising target of obesity treatment. Plasminogen activator inhibitor 1 (PAI-1), a physiological inhibitor of tissue-type and urokinase-type plasminogen activators, is produced at high levels in adipose tissue, especially in states of obesity, and is considered to primarily be involved in thrombosis. PAI-1 may also have roles in inter-organ tissue communications regulating body weight, because PAI-1 knockout mice reportedly exhibit resistance to high fat diet (HFD)-induced obesity. However, the role of PAI-1 in body weight regulation and the underlying mechanisms have not been fully elucidated. We herein studied how PAI-1 affects systemic energy metabolism. We examined body weight and food intake of PAI-1 knockout mice fed normal chow or HFD. We also examined the effects of pharmacological inhibition of PAI-1 activity by a small molecular weight compound, TM5441, on body weight, leptin sensitivities, and expressions of thermogenesis-related genes in brown adipose tissue (BAT) of HFD-fed wild type (WT) mice. Neither body weight gain nor food intake was reduced in PAI-1 KO mice under chow fed conditions. On the other hand, under HFD feeding conditions, food intake was decreased in PAI-1 KO as compared with WT mice (HFD-WT mice 3.98 ± 0.08 g/day vs HFD-KO mice 3.73 ± 0.07 g/day, P = 0.021), leading to an eventual significant suppression of weight gain (HFD-WT mice 40.3 ± 1.68 g vs HFD-KO mice 34.6 ± 1.84 g, P = 0.039). Additionally, TM5441 treatment of WT mice pre-fed the HFD resulted in a marked suppression of body weight gain in a PAI-1-dependent manner (HFD-WT-Control mice 37.6 ± 1.07 g vs HFD-WT-TM5441 mice 33.8 ± 0.97 g, P = 0.017). TM5441 treatment alleviated HFD-induced systemic and hypothalamic leptin resistance, before suppression of weight gain was evident. Moreover, improved leptin sensitivity in response to TM5441 treatment was accompanied by increased expressions of thermogenesis-related genes such as uncoupling protein 1 in BAT (HFD-WT-Control mice 1.00 ± 0.07 vs HFD-WT-TM5441 mice 1.32 ± 0.05, P = 0.002). These results suggest that PAI-1 plays a causative role in body weight gain under HFD-fed conditions by inducing hypothalamic leptin resistance. Furthermore, they indicate that pharmacological inhibition of PAI-1 activity is a potential strategy for alleviating diet-induced leptin resistance in obese subjects.

Lipoprotein lipase (LPL) deficiency is a rare monogenic disorder that manifests as severe hypertriglyceridemia. Whether or not LPL deficiency accelerates the development of atherosclerosis remains controversial. We herein report a 66-year-old woman who was homozygous for the R243H LPL mutation. She had developed multiple arterial aneurysms and systemic atherosclerosis despite good control of other atherogenic risk factors, including diabetes. Furthermore, although intensive pharmaceutical therapies had been minimally effective, medium chain triglyceride (MCT) therapy reduced the serum triglyceride levels. Thus, this case suggests important role that mutated LPL protein plays in the progression of atherosclerosis and that MCT therapy is potentially effective, even for severe hypertriglyceridemia due to LPL deficiency.

Aims/Introduction We investigated impacts of the Great East Japan Earthquake on diabetic patients and characterized those with disaster-susceptible diabetes. Materials and Methods We enrolled 497 diabetic patients who had been followed at hospitals in devastated areas. We collected metabolic parameters prospectively, 1 and 3 months after the earthquake, and retrospectively for pre-earthquake time-points. Questionnaire surveys were carried out regarding earthquake-related damage and post-earthquake lifestyle alterations. Available data were analyzed to examine associations with post-earthquake glycosylated hemoglobin alterations. Results The mean glycosylated hemoglobin level of the participants was not elevated at 1 month, and was significantly decreased at 3 months as compared with the pre-earthquake glycosylated hemoglobin. There were no significant differences in earthquake-related damage or lifestyle alterations between the improved and worsened glycemic control groups according to the data obtained from the questionnaire survey. As reported, fasting serum C-peptide levels were significantly lower in the worsened glycemic control group (P

Olfactory receptors (ORs) mediate olfactory chemo-sensation in OR neurons. Herein, we have demonstrated that the OR chemo-sensing machinery functions in pancreatic β-cells and modulates insulin secretion. First, we found several OR isoforms, including OLFR15 and OLFR821, to be expressed in pancreatic islets and a β-cell line, MIN6. Immunostaining revealed OLFR15 and OLFR821 to be uniformly expressed in pancreatic β-cells. In addition, mRNAs of Olfr15 and Olfr821 were detected in single MIN6 cells. These results indicate that multiple ORs are simultaneously expressed in individual β-cells. Octanoic acid, which is a medium-chain fatty acid contained in food and reportedly interacts with OLFR15, potentiated glucose-stimulated insulin secretion (GSIS), thereby improving glucose tolerance in vivo. GSIS potentiation by octanoic acid was confirmed in isolated pancreatic islets and MIN6 cells and was blocked by OLFR15 knockdown. While Gα olf expression was not detectable in β-cells, experiments using inhibitors and siRNA revealed that the pathway dependent on phospholipase C-inositol triphosphate, rather than cAMP-protein kinase A, mediates GSIS potentiation via OLFR15. These findings suggest that the OR system in pancreatic β-cells has a chemo-sensor function allowing recognition of environmental substances obtained from food, and potentiates insulin secretion in a cell-autonomous manner, thereby modulating systemic glucose metabolism.

Background/objective: Insulin signals, via the regulation of key enzyme expression, both suppress gluconeogenesis and enhance lipid synthesis in the liver. Animal studies have revealed insulin signaling favoring gluconeogenesis suppression to be selectively impaired in steatotic livers. However, whether, and if so how, such selective insulin resistance occurs in human steatotic livers remains unknown. Our aim was to investigate selective insulin resistance in human livers with non-alcoholic fatty liver disease (NAFLD). Subjects/methods: We examined mRNA expressions of key molecules for insulin signaling, gluconeogenesis and lipogenesis in human liver biopsy samples obtained from 51 non-diabetic subjects: 9 healthy controls and 42 NAFLD patients, and analyzed associations of these molecules with each other and with detailed pathological and clinical biochemistry data. Results: In NAFLD patients, insulin receptor substrate (IRS)-2 expression was decreased, while those of key enzymes for gluconeogenesis were increased. These alterations of IRS-2 and gluconeogenesis enzymes were induced both in simple steatosis (SS) and non-alcoholic steatohepatitis (NASH), while these expression levels did not differ between SS and NASH. Furthermore, alterations in the expressions of IRS-2 and gluconeogenesis enzymes showed strong negative correlations and were concurrently induced in the early histological stage of NAFLD. In contrast, fatty acid synthase (FAS) expression was not decreased in NAFLD, despite IRS-2 downregulation, but correlated strongly with IRS-1 expression. Furthermore, no histological scores were associated with these molecules. Thus, IRS-1 signaling, which is not impaired in NAFLD, appears to modulate FAS expression. Conclusion: These analyses revealed that selective insulin resistance is present in human NAFLD livers and occurs in its early phases. The effect of insulin, during the IRS step, on gene expressions for lipogenesis and gluconeogenesis are apparently distinct and preferential downregulation of IRS-2 may contribute to selective resistance to the suppressive effects of insulin on gluconeogenesis.

Fulminant type 1 diabetes is characterized by remarkably rapid and complete β-cell destruction. The established diagnostic criteria include the occurrence of diabetic ketosis soon after the onset of hyperglycemic symptoms, elevated plasma glucose with relatively low HbA1c at the first visit, and extremely low C-peptide. Serum C-peptide levels remain extremely low over a prolonged period. A 26-year-old-man with diabetic ketosis was admitted to our hospital. His relatively low HbA1c (7.6%), despite marked hyperglycemia (593 mg/dL) with marked ketosis, indicated abrupt onset. Islet-related autoantibodies were all negative. His data at onset, including extremely low serum C-peptide (0.11 ng/mL), fulfilled the diagnostic criteria for fulminant type 1 diabetes. However, his fasting serum C-peptide levels subsequently showed substantial recovery. While fasting C-peptide stayed below 0.30 ng/mL during the first two months post onset, the levels gradually increased and thereafter fluctuated between 0.60 ng/mL and 0.90 ng/mL until 24 months post onset. By means of multiple daily insulin injection therapy, his glycemic control has been well maintained (HbA1c approximately 6.0%), with relatively small glycemic fluctuations evaluated by continuous glucose monitoring. This clinical course suggests that, despite the abrupt diabetes onset with extremely low C-peptide levels, substantial numbers of β-cells had been spared destruction and their function later showed gradual recovery. Diabetes has come to be considered a much more heterogeneous disease than the present subdivisions suggest. This case does not fit into the existing concepts of either fulminant type 1 or ketosis-prone diabetes, thereby further highlighting the heterogeneity of idiopathic type 1 diabetes.

Background & Aims Hypoxia-inducible factor 1α subunit (HIF1A) is a transcription factor that controls the cellular response to hypoxia and is activated in hepatocytes of patients with nonalcoholic fatty liver disease (NAFLD). NAFLD increases the risk for cholesterol gallstone disease by unclear mechanisms. We studied the relationship between HIF1A and gallstone formation associated with liver steatosis. Methods We performed studies with mice with inducible disruption of Hif1a in hepatocytes via a Cre adenoviral vector (inducible hepatocyte-selective HIF1A knockout [iH-HIFKO] mice), and mice without disruption of Hif1a (control mice). Mice were fed a diet rich in cholesterol and cholate for 1 or 2 weeks; gallbladders were collected and the number of gallstones was determined. Livers and biliary tissues were analyzed by histology, quantitative reverse-transcription polymerase chain reaction, immunohistochemistry, and immunoblots. We measured concentrations of bile acid, cholesterol, and phospholipid in bile and rates of bile flow. Primary hepatocytes and cholangiocytes were isolated and analyzed. HIF1A was knocked down in Hepa1-6 cells with small interfering RNAs. Liver biopsy samples from patients with NAFLD, with or without gallstones, were analyzed by quantitative reverse-transcription polymerase chain reaction. Results Control mice fed a diet rich in cholesterol and cholate developed liver steatosis with hypoxia; levels of HIF1A protein were increased in hepatocytes around central veins and 90% of mice developed cholesterol gallstones. Only 20% of the iH-HIFKO mice developed cholesterol gallstones. In iH-HIFKO mice, the biliary lipid concentration was reduced by 36%, compared with control mice, and bile flow was increased by 35%. We observed increased water secretion from hepatocytes into bile canaliculi to mediate these effects, resulting in suppression of cholelithogenesis. Hepatic expression of aquaporin 8 (AQP8) protein was 1.5-fold higher in iH-HIFKO mice than in control mice. Under hypoxic conditions, cultured hepatocytes increased expression of Hif1a , Hmox1 , and Vegfa messenger RNAs (mRNAs), and down-regulated expression of AQP8 mRNA and protein; AQP8 down-regulation was not observed in cells with knockdown of HIF1A. iH-HIFKO mice had reduced inflammation and mucin deposition in the gallbladder compared with control mice. Liver tissues from patients with NAFLD with gallstones had increased levels of HIF1A , HMOX1 , and VEGFA mRNAs, compared with livers from patients with NAFLD without gallstones. Conclusions In steatotic livers of mice, hypoxia up-regulates expression of HIF1A, which reduces expression of AQP8 and concentrates biliary lipids via suppression of water secretion from hepatocytes. This promotes cholesterol gallstone formation. Livers from patients with NAFLD and gallstones express higher levels of HIF1A than livers from patients with NAFLD without gallstones.

SummaryConsidering the explosive increase in obesity worldwide, there must be an unknown mechanism(s) promoting energy accumulation under conditions of overnutrition. We identified a feed-forward mechanism favoring energy storage, originating in hepatic glucokinase (GK) upregulation. High-fat feeding induced hepatic GK upregulation, and hepatic GK overexpression dose-dependently decreased adaptive thermogenesis by downregulating thermogenesis-related genes in brown adipose tissue (BAT). This intertissue (liver-to-BAT) system consists of the afferent vagus from the liver and sympathetic efferents from the medulla and antagonizes anti-obesity effects of leptin on thermogenesis. Furthermore, upregulation of endogenous GK in the liver by high-fat feeding was more marked in obesity-prone than in obesity-resistant strains and was inversely associated with BAT thermogenesis. Hepatic GK overexpression in obesity-resistant mice promoted weight gain, while hepatic GK knockdown in obesity-prone mice attenuated weight gain with increased adaptive thermogenesis. Thus, this intertissue energy-saving system may contribute to determining obesity predisposition.

Slowly Progressive Type 1 Diabetes (SPT1D) is characterized by the absence of insulin dependence at the onset of diabetes and persistent detection of islet cell autoantibodies. These patients with high titers of glutamic acid decarboxylase autoantibodies (GADA) are known to progress to insulin dependence within several years. Low-dose insulin injections have been reported to prevent or delay the decline of insulin secretion in SPT1D patients. We experienced the case of an SPT1D patient with preserved endogenous insulin secretion and good glycemic control achieved with α-glucosidase inhibitor (α-GI) treatment alone for 10 years despite having continuously elevated GADA titers. The details of this case suggest that α-GI treatment might have preventive effects on SPT1D progression.

Aims Obesity is commonly associated with hypertension. Increased sympathetic tonus in obese subjects contributes to the underlying mechanism. However, the precise mechanisms whereby obesity induces this sympathetic activation remain unclear. Hepatic peroxisome proliferator-activated receptor (PPAR)-γ2 expression, which is reportedly upregulated during obesity development, affects sympathetic activation via hepatic vagal afferents. Herein, we report involvement of this neuronal relay in obesity-related hypertension. Methods and results Peroxisome proliferator-activated receptor-γ and a direct PPARγ target, fat-specific protein 27 (Fsp27), were adenovirally overexpressed or knocked down in the liver, in combination with surgical dissection or pharmacological deafferentation of the hepatic vagus. Adenoviral PPARγ2 expression in the liver raised blood pressure (BP) in wild-type but not in β1/β2/β3 adrenergic receptor-deficient mice. In addition, knockdown of endogenous PPARγ in the liver lowered BP in murine obesity models. Either surgical dissection or pharmacological deafferentation of the hepatic vagus markedly blunted BP elevation in mice with diet-induced and genetically-induced obesity. In contrast, BP was not elevated in other models of hepatic steatosis, DGAT1 and DGAT2 overexpressions, in which PPARγ is not upregulated in the liver. Thus, hepatic PPARγ upregulation associated with obesity is involved in BP elevation during obesity development. Furthermore, hepatic expression of Fsp27 raised BP and the effect was blocked by hepatic vagotomy. Hepatic Fsp27 is actually upregulated in murine obesity models and its knockdown reversed BP elevation. Conclusion The hepatic PPARγ–Fsp27 pathway plays important roles in the development of obesity-related hypertension via afferent vagal signals from the liver.