Publications

Emerging data demonstrate that microglia activation plays a pivotal role in the development of hypothalamic inflammation in obesity. Early after the introduction of a high-fat diet, hypothalamic microglia undergo morphological, and functional changes in response to excessive dietary saturated fats. Initially the resident microglia are affected; however, as diet-induced obesity persists, bone marrow-derived myeloid cells gradually replace resident microglia. Genetic and pharmacological approaches aimed at dampening the inflammatory activity in the hypothalamus of experimental models of obesity have proven beneficial to correct the obese phenotype and improve metabolic abnormalities commonly associated with obesity. These approaches provide an experimental proof-of-concept that hypothalamic inflammation is central to the pathophysiology of obesity; understanding the details of the roles played by microglia in this process may help the development of preventive and therapeutic advances in the field. In this review, we discuss the potential mechanisms underlying hypothalamic microglial activation in high-fat induced obesity.

AIMS: Enhancement of glucagon-like peptide-1 (GLP-1) reduces glucose levels and preserves pancreatic β-cell function, but its effect against restenosis is unknown.

METHODS AND RESULTS: We investigated the effect of subcutaneous injection of exenatide or local delivery of a recombinant adenovirus expressing GLP-1 (rAd-GLP-1) into carotid artery, in reducing the occurrence of restenosis following balloon injury. As a control, we inserted β-galactosidase cDNA in the same vector (rAd-βGAL). Otsuka Long-Evans Tokushima rats were assigned to three groups (n = 12 each): (1) normal saline plus rAd-βGAL delivery (NS + rAd-βGAL), (2) exenatide plus rAd-βGAL delivery (Exenatide + rAd-βGAL), and (3) normal saline plus rAd-GLP-1 delivery (NS + rAd-GLP-1). Normal saline or exenatide were administered subcutaneously from 1 week before to 2 weeks after carotid injury. After 3 weeks, the NS + rAd-βGAL group showed the highest intima-media ratio (IMR; 3.73 ± 0.90), the exenatide + rAd-βGAL treatment was the next highest (2.80 ± 0.51), and NS + rAd-GLP-1 treatment showed the lowest IMR (1.58 ± 0.48, P < 0.05 vs. others). The proliferation and migration of vascular smooth muscle cells and monocyte adhesion were decreased significantly after rAd-GLP-1 treatment, showing the same overall patterns as the IMR. In injured vessels, the apoptosis was greater and MMP2 expression was less in the NS + rAd-GLP-1 than in the exenatide or rAd-βGAL groups. In vitro expressions of matrix metalloproteinases-2 and monocyte chemoattractant protein-1 and nuclear factor-kappa-B-p65 translocation were decreased more in the NS + rAd-GLP-1 group than in the other two groups (all P < 0.05).

CONCLUSION: Direct GLP-1 overexpression showed better protection against restenosis after balloon injury via suppression of vascular smooth muscle cell migration, increased apoptosis, and decreased inflammatory processes than systemic exenatide treatment. This has potential therapeutic implications for treating macrovascular complications in diabetes.

OBJECTIVE: The objective of this study was to evaluate the association of urine clusterin/apolipoprotein J (Apo J) with the development and/or progression of diabetic kidney disease (DKD) in type 2 diabetes.

MATERIALS AND METHODS: A total of 159 type 2 diabetic patients and 20 nondiabetic subjects with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 were enrolled. The baseline values of urine clusterin and tubular damage markers were measured. The primary outcome was the annual decline rate in eGFR, and secondary outcomes were the development of chronic kidney disease (CKD) stage 3 or greater and the persistence/progression of albuminuria. The median follow-up duration of enrolled patients was 3.0 (1.0-5.9) years.

RESULTS: Baseline clusterin levels in urine were significantly increased in type 2 diabetic subjects compared with those of nondiabetic subjects. The levels of urine clusterin had a significant correlation with urine tubular damage markers. A positive correlation between the annual rate of decline in eGFR and urine clusterin after adjusting for clinical confounding factors was detected. Multivariate analysis further indicated that urine clusterin correlated with the development of CKD stage 3 or greater and persistence/progression of albuminuria. In type 2 diabetic subjects with albuminuria, urine clusterin remained associated with the annual decline rate in eGFR and the progression of CKD stage.

CONCLUSIONS: Urine clusterin reflects tubular damage in the early stage of DKD. The increase in urine clusterin along with albuminuria could be an independent predictive marker for the progression of DKD in type 2 diabetes.

AIMS/HYPOTHESIS: A recent large clinical study has shown that empagliflozin has a lower rate of cardiovascular and all-cause mortality when compared with placebo in patients with type 2 diabetes. We investigated the effect of empagliflozin (compared with glimepiride) on the progression of atherosclerosis, and its possible mechanisms of action.

METHODS: Forty-eight 5-week-old male ApoE -/- mice were fed a western diet for 20 weeks and divided into four groups: control (saline, 154 mmol/l NaCl), glimepiride 0.1 mg/kg, empagliflozin 1 mg/kg and empagliflozin 3 mg/kg (n = 12/group). Plaque size and composition in the aortic arch/valve areas and cardiovascular risk variables in the blood and tissues were evaluated. Insulin resistance was estimated by HOMA and adiponectin levels. Body composition was determined using dual-energy x-ray absorptiometry.

RESULTS: After 8 weeks of treatment, the empagliflozin and glimepiride groups exhibited decreased blood glucose levels. Atherosclerotic plaque areas in the aortic arch/valve were significantly smaller in the empagliflozin groups than in the control or glimepiride groups. Insulin resistance and circulating concentrations of TNF-α, IL-6, monocyte chemoattractant protein-1 (MCP-1), serum amyloid A and urinary microalbumin decreased after empagliflozin treatment, and this significantly correlated with plaque size. Empagliflozin treatment reduced weight and fat mass, lipid droplets in the liver, fat cell size, mRNA expression of Tnf, Il6 and Mcp-1 (also known as Ccl2) and the infiltration of inflammatory cells in plaque and adipose tissue compared with the control or glimepiride group. Empagliflozin treatment increased adiponectin levels.

CONCLUSIONS/INTERPRETATION: Improvements in inflammation and insulin resistance seem to be mechanisms involved in the mitigation of atherosclerosis by empagliflozin.

Cancer cell-derived extracellular vesicles have been linked to the pathogenesis of various cancers; however, the role of extracellular vesicles in tumorigenesis remains unclear. To identify extracellular vesicle proteins involved in cancer metastasis, quantitative proteomic analyses were performed on extracellular vesicles derived from two representative breast cancer cell lines: the less invasive MCF-7 and the invasive MDA-MB-231. Proteomic analysis allowed for the identification of 270 proteins in the extracellular vesicles. Here we report a new function of EDIL3 on extracellular vesicles, which are sufficient for enhancement of cell invasion and for acceleration of lung metastasis in vivo. This invasion is most likely mediated via the integrin-FAK signaling cascade in breast cancer cells. However, these effects are suppressed when EDIL3 is inactivated, providing evidence for a critical role of EDIL3 in development of cancer. Consistently, in human patients with metastatic breast cancer, the levels of EDIL3 on circulating extracellular vesicles are significantly elevated. This information is a remarkable breakthrough in understanding of the molecular mechanism underlying metastasis of breast cancer as well as in the research for cancer biomarkers using circulating extracellular vesicles. Furthermore, targeting EDIL3 on extracellular vesicles may lead to a new therapeutic option for treatment of breast cancer.

The seaweeds were collected from the coast of Jeju Island, South Korea. We investigated ethanol extracts from seaweed as potential antiobesity agents by testing their effect on adipogenic differentiation in 3T3-L1 cells. Among the red algae extracts tested, the Plocamium telfairiae extract (PTE) showed the highest inhibitory effect on lipogenesis in adipocytes and, thus, was selected as a potential antiobesity agent. PTE treatment significantly decreased the expression of the adipogenic-specific proteins peroxisome proliferator-activated receptor-γ, CCAAT/enhancer-binding protein-α, sterol regulatory element-binding protein 1, and fatty acid-binding protein 4 compared with that in the untreated 3T3-L1 cells. PTE also inhibited high-fat diet (HFD)-induced obesity in male C57BL/6 mice. Oral administration of PTE significantly reduced the body weight, fatty liver, amount of white adipose tissue, and levels of triglyceride and glucose in the tested animals. Taken together, these data demonstrate that PTE can be developed as a therapeutic agent for obesity.

PURPOSE: Currently, there are no molecular biomarkers for the early detection of breast cancer. This study focused on identifying surface proteins found on circulating extracellular vesicles (EVs) for detecting early-stage breast cancer.

EXPERIMENTAL DESIGN: Circulating EVs, isolated from the plasma of 10 patients with breast cancer (stages I and II) and 5 healthy controls, were analyzed using LC-MS/MS. Developmental endothelial locus-1 protein (Del-1) was selected as a candidate biomarker. Two different ELISAs were used to measure Del-1 in plasma samples from healthy controls (n= 81), patients with breast cancer (n= 269), breast cancer patients after surgical resection (n= 50), patients with benign breast tumors (n= 64), and patients with noncancerous diseases (n= 98) in two cohorts.

RESULTS: Plasma Del-1 levels were significantly higher (P< 0.0001) in patients with breast cancer than in all controls and returned to almost normal after tumor removal. The diagnostic accuracy of Del-1 was AUC, 0.961 [95% confidence interval (CI), 0.924-0.983], sensitivity of 94.70%, and specificity of 86.36% in test cohort and 0.968 (0.933-0.988), 92.31%, and 86.62% in validation cohort for early-stage breast cancer by one type of ELISA. Furthermore, Del-1 maintained diagnostic accuracy for patients with early-stage breast cancer using the other type of ELISA [0.946 (0.905-0.972), 90.90%, and 77.14% in the test cohort; 0.943 (0.900-0.971), 89.23%, and 80.99% in the validation cohort].

CONCLUSIONS: Del-1 on circulating EVs is a promising marker to improve identification of patients with early-stage breast cancer and distinguish breast cancer from benign breast tumors and noncancerous diseases.

The preadipocyte factor 1 (Pref-1) is involved in the proliferation and differentiation of various precursor cells. However, the intracellular signaling pathways that control these processes and the role of Pref-1 in the pancreas remain poorly understood. Here, we showed that Pref-1 induces insulin synthesis and secretion via two independent pathways. The overexpression of Pref-1 activated MAPK signaling, which induced nucleocytoplasmic translocation of FOXO1 and PDX1 and led to the differentiation of human pancreatic ductal cells into β-like cells and an increase in insulin synthesis. Concurrently, Pref-1 activated Akt signaling and facilitated insulin secretion. A proteomics analysis identified the Rab43 GTPase-activating protein as a downstream target of Akt. A serial activation of both proteins induced various granular protein syntheses which led to enhanced glucose-stimulated insulin secretion. In a pancreatectomised diabetic animal model, exogenous Pref-1 improved glucose homeostasis by accelerating pancreatic ductal and β-cell regeneration after injury. These data establish a novel role for Pref-1, opening the possibility of applying this molecule to the treatment of diabetes.

The popular edible seaweed, Gelidium amansii is broadly used as food worldwide. To determine whether G. amansii extract (GAE) has protective effects on obesity, mice fed a high-fat diet (HFD) treated with GAE (1 and 3 %) were studied. After 12 weeks of GAE treatment, body weight was greatly decreased in mice fed a high-fat diet. This effect could be due to decreased adipogenesis, as evidenced by the fact that GAE suppressed adipogenic gene expression in adipocytes. In addition, blood glucose and serum insulin levels were reduced by GAE treatment in mice fed a high-fat diet, suggesting improvement in glucose metabolism. GAE supplementation also led to a significant decrease in total cholesterol and triglyceride levels. These data are further confirmed by H&E staining. Our findings indicate that Gelidium amansii prevents against the development of diet-induced obesity, and further implicate that GAE supplementation could be the therapeutical option for treatment of metabolic disorder such as obesity.