Factors Affecting Human Damage in Heavy Rains and Typhoon Disasters.

Floods due to heavy rains or typhoons are frequent annual hazards in Japan. This study aims to reduce disaster fatalities and contribute to disaster risk reduction. This retrospective observational study analyzed fatalities caused by heavy rains or typhoons. In Japan, 578 fatalities, related to seven occurrences of heavy rains and 16 typhoons, occurred between 2016 and 2020. Moreover, 13,195 houses collapsed due to hazards. Furthermore, 334 (73.2%) of the 456 fatalities were > 60 years old. Heavy rains caused more local area destruction due to floods and landslides than typhoons although wind- and disaster-related mortalities were found to be caused by typhoons. Human damage was eminent in older people because of their vulnerabilities and possibly dangerous behavior. Many fatalities were due to floods (46.9%) and landslides (44.1%). Indoor and outdoor mortalities due to heavy rains or typhoons were 157 (55.9%) and 124 (44.1%), respectively, and 24 (21.8%) of 124 outdoor mortalities occurred in vehicles. The number of recent flood mortalities in Japan correlates with the number of destroyed houses. Analyzing the victim's locations in the 2020 Kumamoto Heavy Rain using hazard and inundation maps suggested the difficulty of ensuring the safety of people living in dangerous areas. This study showed the characteristics of flood damage by heavy rains and typhoons in Japan and reports that flood damage is increasing because of the hazard size and community aging. Disaster risk reduction, disaster education, and evacuation safety plans for the elderly using hazard maps were important for strengthening disaster resilience.

Sirt7 Deficiency Attenuates Neointimal Formation Following Vascular Injury by Modulating Vascular Smooth Muscle Cell Proliferation.

BACKGROUND: Sirt7 is a recently identified sirtuin and has important roles in various pathological conditions, including cancer progression and metabolic disorders. It has previously been reported that Sirt7 is a key molecule in acute myocardial wound healing and pressure overload-induced cardiac hypertrophy. In this study, the role of Sirt7 in neointimal formation after vascular injury is investigated.Methods and Results:Systemic (Sirt7-/-) and smooth muscle cell-specific Sirt7-deficient mice were subjected to femoral artery wire injury. Primary vascular smooth muscle cells (VSMCs) were isolated from the aorta of wild type (WT) and Sirt7-/-mice and their capacity for cell proliferation and migration was compared. Sirt7 expression was increased in vascular tissue at the sites of injury. Sirt7-/-mice demonstrated significant reduction in neointimal formation compared to WT mice. In vitro, Sirt7 deficiency attenuated the proliferation of serum-induced VSMCs. Serum stimulation-induced upregulation of cyclins and cyclin-dependent-kinase 2 (CDK2) was significantly attenuated in VSMCs of Sirt7-/-compared with WT mice. These changes were accompanied by enhanced expression of the microRNA 290-295 cluster, the translational negative regulator of CDK2, in VSMCs of Sirt7-/-mice. It was confirmed that smooth muscle cell-specific Sirt7-deficient mice showed significant reduction in neointima compared with control mice. CONCLUSIONS: Sirt7 deficiency attenuates neointimal formation after vascular injury. Given the predominant role in vascular neointimal formation, Sirt7 is a potentially suitable target for treatment of vascular diseases.

Inhibition of inflammation-mediated DPP-4 expression by linagliptin increases M2 macrophages in atherosclerotic lesions.

BACKGROUND AND AIMS: Dipeptidyl peptidase-4 (DPP-4) inhibitors have been reported to suppress atherosclerosis progression in atherosclerotic mouse models through unclear mechanisms. In this study, we investigated the effect of the DPP-4 inhibitor, linagliptin, on macrophage polarization in vitro and in vivo. METHODS: Mouse bone marrow macrophages (BMMs) were used in in vitro assays. High fat diet (HFD)-fed Apoe-/- mice were treated orally with linagliptin (10 mg/kg-1•day-1) or a vehicle (water) control. RESULTS: In in vitro assays using BMMs, treatment with LPS and IFNγ decreased the mRNA-expression levels of alternatively activated macrophage (M2) markers, and linagliptin treatment prevented these reductions. The mRNA levels of M2 markers and the number of M2 macrophages in the aorta were higher in linagliptin groups than in control groups. Linagliptin decreased the size of atherosclerotic lesions in HFD-fed Apoe-/- mice. Interestingly, inflammatory stimulation increased DPP-4 expression, and linagliptin suppressed these effects in BMMs. Treatment with DPP-4 small-interfering RNA (siRNA) reproduced linagliptin-mediated alteration of M2 polarization. CONCLUSIONS: Linagliptin increased M2 macrophage polarization by inhibiting DPP-4 expression and activity. These findings may indicate the beneficial effects of DPP-4 inhibitors on the progression of diabetic macrovascular complications.

Inhibition of Local Macrophage Growth Ameliorates Focal Inflammation and Suppresses Atherosclerosis.

OBJECTIVE: Macrophages play a central role in various stages of atherosclerotic plaque formation and progression. The local macrophages reportedly proliferate during atherosclerosis, but the pathophysiological significance of macrophage proliferation in this context remains unclear. Here, we investigated the involvement of local macrophage proliferation during atherosclerosis formation and progression using transgenic mice, in which macrophage proliferation was specifically suppressed. APPROACH AND RESULTS: Inhibition of macrophage proliferation was achieved by inducing the expression of cyclin-dependent kinase inhibitor 1B, also known as p27kip, under the regulation of a scavenger receptor promoter/enhancer. The macrophage-specific human p27kip Tg mice were subsequently crossed with apolipoprotein E-deficient mice for the atherosclerotic plaque study. Results showed that a reduced number of local macrophages resulted in marked suppression of atherosclerotic plaque formation and inflammatory response in the plaque. Moreover, fewer local macrophages in macrophage-specific human p27kip Tg mice helped stabilize the plaque, as evidenced by a reduced necrotic core area, increased collagenous extracellular matrix, and thickened fibrous cap. CONCLUSIONS: These results provide direct evidence of the involvement of local macrophage proliferation in formation and progression of atherosclerotic plaques and plaque stability. Thus, control of macrophage proliferation might represent a therapeutic target for treating atherosclerotic diseases.

Study Design of a Phase II Clinical Trial to Assess the Efficacy and Safety of Eperisone in Japanese Type 2 Diabetes Patients with Risk and Non-risk Alleles of CDKAL1.

Genetic variation in Cdk5 Regulatory Associated Protein 1-Like 1 (CDKAL1) is associated with the development of type 2 diabetes (T2D). Dysfunction of CDKAL1 impairs the translation of proinsulin, which leads to glucose intolerance. Eperisone, an antispasmodic agent, has been shown to ameliorate glucose intolerance in Cdkal1-deficient mice. We have launched a phase II clinical study to investigate the potential anti-diabetic effect of eperisone in T2D patients carrying risk or non-risk alleles of CDKAL1. The primary endpoint is the change of hemoglobin A1c (HbA1c) levels. We also examined whether the efficacy of eperisone in T2D patients is associated with CDKAL1 activity.

Sirt7 Contributes to Myocardial Tissue Repair by Maintaining Transforming Growth Factor-ß Signaling Pathway.

BACKGROUND: Sirt7, 1 of the 7 members of the mammalian sirtuin family, promotes oncogenic transformation. Tumor growth and metastasis require fibrotic and angiogenic responses. Here, we investigated the role of Sirt7 in cardiovascular tissue repair process. METHODS AND RESULTS: In wild-type mice, Sirt7 expression increased in response to acute cardiovascular injury, including myocardial infarction and hind-limb ischemia, particularly at the active wound healing site. Compared with wild-type mice, homozygous Sirt7-deficient (Sirt7(-/-)) mice showed susceptibility to cardiac rupture after myocardial infarction, delayed blood flow recovery after hind-limb ischemia, and impaired wound healing after skin injury. Histological analysis showed reduced fibrosis, fibroblast differentiation, and inflammatory cell infiltration in the border zone of infarction in Sirt7(-/-) mice. In vitro, Sirt7(-/-) mouse-derived or Sirt7 siRNA-treated cardiac fibroblasts showed reduced transforming growth factor-ß signal activation and low expression levels of fibrosis-related genes compared with wild-type mice-derived or control siRNA-treated cells. These changes were accompanied by reduction in transforming growth factor receptor I protein. Loss of Sirt7 activated autophagy in cardiac fibroblasts. Transforming growth factor-ß receptor I downregulation induced by loss of Sirt7 was blocked by autophagy inhibitor, and interaction of Sirt7 with protein interacting with protein kinase-Cα was involved in this process. CONCLUSION: Sirt7 maintains transforming growth factor receptor I by modulating autophagy and is involved in the tissue repair process.

Acetate alters expression of genes involved in beige adipogenesis in 3T3-L1 cells and obese KK-Ay mice.

The induction of beige adipogenesis within white adipose tissue, known as "browning", has received attention as a novel potential anti-obesity strategy. The expression of some characteristic genes including PR domain containing 16 is induced during the browning process. Although acetate has been reported to suppress weight gain in both rodents and humans, its potential effects on beige adipogenesis in white adipose tissue have not been fully characterized. We examined the effects of acetate treatment on 3T3-L1 cells and in obese diabetic KK-Ay mice. The mRNA expression levels of genes involved in beige adipocyte differentiation and genes selectively expressed in beige adipocytes were significantly elevated in both 3T3-L1 cells incubated with 1.0 mM acetate and the visceral white adipose tissue from mice treated with 0.6% acetate for 16 weeks. In KK-Ay mice, acetate reduced the food efficiency ratio and increased the whole-body oxygen consumption rate. Additionally, reduction of adipocyte size and uncoupling protein 1-positive adipocytes and interstitial areas with multilocular adipocytes appeared in the visceral white adipose tissue of acetate-treated mice, suggesting that acetate induced initial changes of "browning". In conclusion, acetate alters the expression of genes involved in beige adipogenesis and might represent a potential therapeutic agent to combat obesity.

Statins meditate anti-atherosclerotic action in smooth muscle cells by peroxisome proliferator-activated receptor-γ activation.

The peroxisome proliferator-activated receptor-γ (PPARγ) is an important regulator of lipid and glucose metabolism, and its activation is reported to suppress the progression of atherosclerosis. We have reported that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) activate PPARγ in macrophages. However, it is not yet known whether statins activate PPARγ in other vascular cells. In the present study, we investigated whether statins activate PPARγ in smooth muscle cells (SMCs) and endothelial cells (ECs) and thus mediate anti-atherosclerotic effects. Human aortic SMCs (HASMCs) and human umbilical vein ECs (HUVECs) were used in this study. Fluvastatin and pitavastatin activated PPARγ in HASMCs, but not in HUVECs. Statins induced cyclooxygenase-2 (COX-2) expression in HASMCs, but not in HUVECs. Moreover, treatment with COX-2-siRNA abrogated statin-mediated PPARγ activation in HASMCs. Statins suppressed migration and proliferation of HASMCs, and inhibited lipopolysaccharide-induced expression of monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α) in HASMCs. These effects of statins were abrogated by treatment with PPARγ-siRNA. Treatment with statins suppressed atherosclerotic lesion formation in Apoe(-/-) mice. In addition, transcriptional activity of PPARγ and CD36 expression were increased, and the expression of MCP-1 and TNF-α was decreased, in the aorta of statin-treated Apoe(-/-) mice. In conclusion, statins mediate anti-atherogenic effects through PPARγ activation in SMCs. These effects of statins on SMCs may be beneficial for the prevention of atherosclerosis.

Regulation of TNFα converting enzyme activity in visceral adipose tissue of obese mice.

Tumor necrosis factor α (TNFα) is a pro-inflammatory cytokine and one of the major mediators of obesity-induced insulin resistance. TNFα is generated through TNFα converting enzyme (TACE)-mediated cleavage of the transmembrane precursor pro-TNFα. Inhibition of TACE resulted in the improvement in glucose and insulin levels in diabetic animals, suggesting a crucial role of TACE activity in glucose metabolism. However, the regulation of TACE activity in insulin-sensitive tissues has not been fully determined. This study aimed to investigate the impact of TACE in insulin-sensitive tissues in the early stage of the development of obesity. C57BL6 mice were fed standard chow (B6-SC) or high-fat/high-sucrose diet (B6-HF/HS). KK-Ay mice were fed SC ad libitum (Ay-AL) or fed reduced amounts of SC (caloric restriction (CR); Ay-CR). As control for Ay-AL, KK mice fed SC ad libitum (KK-AL) were used. TACE activity in visceral adipose tissue (VAT), but not in liver or skeletal muscle, was significantly elevated in B6-HF/HS and Ay-AL compared with B6-SC and KK-AL, respectively. Phosphorylation of JNK and p38MAPK, but not ERK, in VATs from B6-HF/HS and Ay-AL was also significantly elevated. Ay-CR showed significantly lower TACE, JNK and p38MAPK activities in VAT and serum TNFα level compared with those of Ay-AL. In contrast, intraperitoneal injection of TNFα activated TACE, JNK and p38MAPK activities in VAT in KK mice. In conclusion, during the development of obesity, TACE activity is elevated only in VAT, and CR effectively reduced TACE activity and TACE-mediated pro-TNFα shedding in VAT.

Apocynin suppresses the progression of atherosclerosis in apoE-deficient mice by inactivation of macrophages.

Production of reactive oxygen species (ROS) and other proinflammatory substances by macrophages plays an important role in atherogenesis. Apocynin (4-hydroxy-3-methoxy-acetophenone), which is well known as a NADPH oxidase inhibitor, has anti-inflammatory effects including suppression of the generation of ROS. However, the suppressive effects of apocynin on the progression of atherosclerosis are not clearly understood. Thus, we investigated anti-atherosclerotic effects of apocynin using apolipoprotein E-deficient (apoE(-/-)) mice in vivo and in mouse peritoneal macrophages in vitro. In atherosclerosis-prone apoE(-/-) mice, apocynin suppressed the progression of atherosclerosis, decreased 4-hydroxynonenal-positive area in atherosclerotic lesions, and mRNA expression of monocyte chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6) in aorta. In mouse peritoneal macrophages, apocynin suppressed the Ox-LDL-induced ROS generation, mRNA expression of MCP-1, IL-6 and granulocyte/macrophage colony-stimulating factor, and cell proliferation. Moreover, immunohistochemical studies revealed that apocynin decreased the number of proliferating cell nuclear antigen-positive macrophages in atherosclerotic lesions of apoE(-/-) mice. These results suggested that apocynin suppressed the formation of atherosclerotic lesions, at least in part, by inactivation of macrophages. Therefore, apocynin may be a potential therapeutic material to prevent the progression of atherosclerosis.

Association between circulating leukocyte subtype counts and carotid intima-media thickness in Japanese subjects with type 2 diabetes.

BACKGROUND: An increased leukocyte count is an independent risk factor for cardiovascular events, but the association between leukocyte subtype counts and carotid atherosclerosis in patients with diabetes has not been determined. We therefore investigated the correlation between leukocyte subtype counts and intima-media thickness of the common carotid artery (CCA-IMT) in subjects with type 2 diabetes. METHODS: This cross-sectional study involved 484 in-patients with type 2 diabetes (282 males and 202 females), who were hospitalized for glycemic control and underwent carotid ultrasonography at Kumamoto University Hospital between 2005 and 2011. Mean and maximum CCA-IMT was measured by high-resolution B-mode ultrasonography. RESULTS: Univariate analyses revealed that mean CCA-IMT was positively correlated with age, systolic blood pressure, brachial-ankle pulse wave velocity (PWV), urinary albumin excretion and duration of diabetes, but was negatively correlated with diastolic blood pressure and fasting plasma glucose. Maximum CCA-IMT was positively and negatively correlated with the same factors as mean CCA-IMT except for fasting plasma glucose. Mean CCA-IMT was positively correlated with total leukocyte (r = 0.124, p = 0.007), monocyte (r = 0.373, p < 0.001), neutrophil (r = 0.139, p = 0.002) and eosinophil (r = 0.107, p = 0.019) counts. Maximum CCA-IMT was positively correlated with total leukocyte (r = 0.154, p < 0.001), monocyte (r = 0.398, p < 0.001), neutrophil (r = 0.152, p < 0.001) and basophil counts (r = 0.102, p = 0.027). Multiple regression analyses showed that monocyte count, age and PWV were significant and independent factors associated with mean CCA-IMT (adjusted R2 = 0.239, p < 0.001), and that monocyte count, age and urinary albumin excretion were significant and independent factors associated with maximum CCA-IMT (adjusted R2 = 0.277, p < 0.001). CONCLUSIONS: Monocyte counts were positively correlated with both mean CCA-IMT and maximum CCA-IMT in patients with type 2 diabetes. Monocyte count may be a useful predictor of macrovascular complications in patients with type 2 diabetes. TRIAL REGISTRATION: Trial registry no: UMIN000003526.

Mitochondrial dysfunction and increased reactive oxygen species impair insulin secretion in sphingomyelin synthase 1-null mice.

Sphingomyelin synthase 1 (SMS1) catalyzes the conversion of ceramide to sphingomyelin. Here, we generated and analyzed SMS1-null mice. SMS1-null mice exhibited moderate neonatal lethality, reduced body weight, and loss of fat tissues mass, suggesting that they might have metabolic abnormality. Indeed, analysis on glucose metabolism revealed that they showed severe deficiencies in insulin secretion. Isolated mutant islets exhibited severely impaired ability to release insulin, dependent on glucose stimuli. Further analysis indicated that mitochondria in mutant islet cells cannot up-regulate ATP production in response to glucose. We also observed additional mitochondrial abnormalities, such as hyperpolarized membrane potential and increased levels of reactive oxygen species (ROS) in mutant islets. Finally, when SMS1-null mice were treated with the anti-oxidant N-acetyl cysteine, we observed partial recovery of insulin secretion, indicating that ROS overproduction underlies pancreatic ß-cell dysfunction in SMS1-null mice. Altogether, our data suggest that SMS1 is important for controlling ROS generation, and that SMS1 is required for normal mitochondrial function and insulin secretion in pancreatic ß-cells.

Synthesized basement membranes direct the differentiation of mouse embryonic stem cells into pancreatic lineages.

We previously reported that embryonic stem (ES) cells cultured on M15 cells, a mesoderm-derived supportive cell line, were efficiently differentiated towards an endodermal fate, finally adopting the specific lineages of various digestive organs such as the pancreas and liver. We show here that the endoderm-inducing activity of M15 cells is in part mediated through the extracellular matrices, and that laminin alpha5 is one of the crucial components. In an attempt to establish a feeder-free ES-cell procedure for pancreatic differentiation, we used a synthesized basement membrane (sBM) substratum using an HEK293 cell line stably expressing laminin-511. On the sBM, mouse ES or induced pluripotent stem (iPS) cells sequentially differentiated into the definitive endoderm, pancreatic progenitor cells, and then insulin-expressing pancreatic beta-cells in vitro. Knockdown of ES cells with integrin beta1 (Itgb1) reduces differentiation towards pancreatic cells. Heparan sulfate proteoglycan 2 (HSPG2) knockdown and heparitinase treatment synergistically decreased the number of Pdx1-expressing cells. These findings indicate that components of the basement membrane have an important role in the differentiation of definitive endoderm lineages. This novel procedure will be useful for the study of pancreatic differentiation of ES or iPS cells and the generation of potential sources of surrogate cells for regenerative medicine.

Telmisartan exerts antiatherosclerotic effects by activating peroxisome proliferator-activated receptor-γ in macrophages.

OBJECTIVE: Telmisartan, an angiotensin type I receptor blocker (ARB), protects against the progression of atherosclerosis. Here, we investigated the molecular basis of the antiatherosclerotic effects of telmisartan in macrophages and apolipoprotein E-deficient mice. METHODS AND RESULTS: In macrophages, telmisartan increased peroxisome proliferator-activated receptor-γ (PPARγ) activity and PPAR ligand-binding activity. In contrast, 3 other ARBs, losartan, valsartan, and olmesartan, did not affect PPARγ activity. Interestingly, high doses of telmisartan activated PPARα in macrophages. Telmisartan induced the mRNA expression of CD36 and ATP-binding cassette transporters A1 and G1 (ABCA1/G1), and these effects were abrogated by PPARγ small interfering RNA. Telmisartan, but not other ARBs, inhibited lipopolysaccharide-induced mRNA expression of monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α, and these effects were abrogated by PPARγ small interfering RNA. Moreover, telmisartan suppressed oxidized low-density lipoprotein-induced macrophage proliferation through PPARγ activation. In apolipoprotein E(-/-) mice, telmisartan increased the mRNA expression of ABCA1 and ABCG1, decreased atherosclerotic lesion size, decreased the number of proliferative macrophages in the lesion, and suppressed MCP-1 and tumor necrosis factor-α mRNA expression in the aorta. CONCLUSION: Telmisartan induced ABCA1/ABCG1 expression and suppressed MCP-1 expression and macrophage proliferation by activating PPARγ. These effects may induce antiatherogenic effects in hypertensive patients.

Voltage-gated K+ channel KCNQ1 regulates insulin secretion in MIN6 ß-cell line.

KCNQ1, located on 11p15.5, encodes a voltage-gated K(+) channel with six transmembrane regions, and loss-of-function mutations in the KCNQ1 gene cause hereditary long QT syndrome. Recent genetic studies have identified that single nucleotide polymorphisms located in intron 15 of the KCNQ1 gene are strongly associated with type 2 diabetes and impaired insulin secretion. In order to understand the role of KCNQ1 in insulin secretion, we introduced KCNQ1 into the MIN6 mouse ß-cell line using a retrovirus-mediated gene transfer system. In KCNQ1 transferred MIN6 cells, both the density of the KCNQ1 current and the density of the total K(+) current were significantly increased. In addition, insulin secretion by glucose, pyruvate, or tolbutamide was significantly impaired by KCNQ1-overexpressing MIN6 cells. These results suggest that increased KCNQ1 protein expression limits insulin secretion from pancreatic ß-cells by regulating the potassium channel current.

Nifedipine induces peroxisome proliferator-activated receptor-gamma activation in macrophages and suppresses the progression of atherosclerosis in apolipoprotein E-deficient mice.

OBJECTIVE: Nifedipine, an L-type calcium channel blocker, protects against the progression of atherosclerosis. We investigated the molecular basis of the antiatherosclerotic effect of nifedipine in macrophages and apolipoprotein E-deficient mice. METHODS AND RESULTS: In macrophages, nifedipine increased peroxisome proliferator-activated receptor-gamma (PPARgamma) activity without increasing PPARgamma-binding activity. Amlodipine, another L-type calcium channel blocker, and 1,2-bis-(o-aminophenoxy)-ethane-N,N,-N',N'-tetraacetic acid tetraacetoxy-methyl ester (BAPTA-AM), a calcium chelator, decreased PPARgamma activity, suggesting that nifedipine does not activate PPARgamma via calcium channel blocker activity. Inactivation of extracellular signal-regulated kinase 1/2 suppressed PPARgamma2-Ser112 phosphorylation and induced PPARgamma activation. Nifedipine suppressed extracellular signal-regulated kinase 1/2 activation and PPARgamma2-Ser112 phosphorylation, and mutating PPARgamma2-Ser112 to Ala abrogated nifedipine-mediated PPARgamma activation. These results suggested that nifedipine inhibited extracellular signal-regulated kinase 1/2 activity and PPARgamma2-Ser112 phosphorylation, leading to PPARgamma activation. Nifedipine inhibited lipopolysaccharide-induced monocyte chemoattractant protein-1 expression and induced ATP-binding cassette transporter A1 mRNA expression, and these effects were abrogated by small interfering RNA for PPARgamma. Furthermore, in apolipoprotein E-deficient mice, nifedipine treatment decreased atherosclerotic lesion size, phosphorylation of PPARgamma2-Ser112 and extracellular signal-regulated kinase 1/2, and monocyte chemoattractant protein-1 mRNA expression and increased ATP-binding cassette transporter A1 expression in the aorta. CONCLUSIONS: Nifedipine unlike amlodipine inhibits PPARgamma-Ser phosphorylation and activates PPARgamma to suppress monocyte chemoattractant protein-1 expression and induce ATP-binding cassette transporter A1 expression in macrophages. These effects may induce antiatherogenic effects in hypertensive patients.

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.

Activation of AMP-activated protein kinase suppresses oxidized low-density lipoprotein-induced macrophage proliferation.

Macrophage-derived foam cells play important roles in the progression of atherosclerosis. We reported previously that ERK1/2-dependent granulocyte/macrophage colony-stimulating factor (GM-CSF) expression, leading to p38 MAPK/ Akt signaling, is important for oxidized low density lipoprotein (Ox-LDL)-induced macrophage proliferation. Here, we investigated whether activation of AMP-activated protein kinase (AMPK) could suppress macrophage proliferation. Ox-LDL-induced proliferation of mouse peritoneal macrophages was assessed by [(3)H]thymidine incorporation and cell counting assays. The proliferation was significantly inhibited by the AMPK activator 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) and restored by dominant-negative AMPKalpha1, suggesting that AMPK activation suppressed macrophage proliferation. AICAR partially suppressed Ox-LDL-induced ERK1/2 phosphorylation and GM-CSF expression, suggesting that another mechanism is also involved in the AICAR-mediated suppression of macrophage proliferation. AICAR suppressed GM-CSF-induced macrophage proliferation without suppressing p38 MAPK/Akt signaling. GM-CSF suppressed p53 phosphorylation and expression and induced Rb phosphorylation. Overexpression of p53 or p27(kip) suppressed GM-CSF-induced macrophage proliferation. AICAR induced cell cycle arrest, increased p53 phosphorylation and expression, and suppressed GM-CSF-induced Rb phosphorylation via AMPK activation. Moreover, AICAR induced p21(cip) and p27(kip) expression via AMPK activation, and small interfering RNA (siRNA) of p21(cip) and p27(kip) restored AICAR-mediated suppression of macrophage proliferation. In conclusion, AMPK activation suppressed Ox-LDL-induced macrophage proliferation by suppressing GM-CSF expression and inducing cell cycle arrest. These effects of AMPK activation may represent therapeutic targets for atherosclerosis.

Impact of tissue macrophage proliferation on peripheral and systemic insulin resistance in obese mice with diabetes.

INTRODUCTION: Obesity-related insulin resistance is a widely accepted pathophysiological feature in type 2 diabetes. Systemic metabolism and immunity are closely related, and obesity represents impaired immune function that predisposes individuals to systemic chronic inflammation. Increased macrophage infiltration and activation in peripheral insulin target tissues in obese subjects are strongly related to insulin resistance. Using a macrophage-specific proliferation inhibition mouse model (mac-p27Tg), we previously reported that suppressed plaque inflammation reduced atherosclerosis and improved plaque stabilization. However, the direct evidence that proliferating macrophages are responsible for inducing insulin resistance was not provided. RESEARCH DESIGN AND METHODS: The mac-p27Tg mice were fed a high-fat diet, and glucose metabolism, histological changes, macrophage polarization, and tissue functions were investigated to reveal the significance of tissue macrophage proliferation in insulin resistance and obesity. RESULTS: The mac-p27Tg mice showed improved glucose tolerance and insulin sensitivity, along with a decrease in the number and ratio of inflammatory macrophages. Obesity-induced inflammation and oxidative stress was attenuated in white adipose tissue, liver, and gastrocnemius. Histological changes related to insulin resistance, such as liver steatosis/fibrosis, adipocyte enlargement, and skeletal muscle fiber transformation to fast type, were ameliorated in mac-p27Tg mice. Serum tumor necrosis factor alpha and free fatty acid were decreased, which might partially impact improved insulin sensitivity and histological changes. CONCLUSIONS: Macrophage proliferation in adipose tissue, liver, and skeletal muscle was involved in promoting the development of systemic insulin resistance. Controlling the number of tissue macrophages by inhibiting macrophage proliferation could be a therapeutic target for insulin resistance and type 2 diabetes.

The macrophage at the crossroads of insulin resistance and atherosclerosis.

The macrophage has emerged as an important player in the pathogenesis of both atherosclerosis and insulin resistance. Cross-talk between inflammatory macrophages and adipocytes may be involved in insulin resistance in peripheral tissues. Defective insulin signaling in cells of the arterial wall including macrophages may promote the development of atherosclerosis. Insulin resistant macrophages are more susceptible to endoplasmic reticulum stress and apoptosis in response to various stimuli such as nutrient deprivation, free cholesterol loading, and oxidized LDL. Increased apoptosis of insulin resistant macrophages and impaired phagocytic clearance of apoptotic cells by insulin resistant macrophages in atherosclerotic lesions may lead to enhanced postapoptotic necrosis, larger lipid-rich cores, increased inflammation, and more complex vulnerable plaques.