Abdominal fat accumulation has been shown to play crucial roles in the development of metabolic syndrome. Visceral fat accumulation particularly is closely correlated to the development of cardiovascular disease and obesity-related disorders such as diabetes mellitus, hyperlipidemia and hypertension. Given these clinical findings, the functions of adipocytes have been intensively investigated in the past 10 years, and have been revealed to act as endocrine cells that secrete various bioactive substances termed adipocytokines. Among adipocytokines, tumor-necrosis factor-alpha, plasminogen activator inhibitor type 1 and heparin-binding epidermal growth factor-like growth factor are produced in adipocytes as well as other organs, and contribute to the development of vascular diseases. Visfatin has been identified as a visceral-fat-specific protein that might be involved in the development of obesity-related diseases, such as diabetes mellitus and cardiovascular disease. In contrast to these adipocytokines, adiponectin, which is an adipose-tissue-specific, collagen-like protein, has been noted as an important antiatherogenic and antidiabetic protein, or as an anti-inflammatory protein. The functions of adipocytokine secretion might be regulated dynamically by nutritional state. Visceral fat accumulation causes dysregulation of adipocyte functions, including oversecretion of tumor-necrosis factor-alpha, plasminogen activator inhibitor type 1 and heparin-binding epidermal growth factor-like growth factor, and hyposecretion of adiponectin, which results in the development of a variety of metabolic and circulatory diseases. In this review, the importance of adipocytokines, particularly adiponectin, is discussed with respect to cardiovascular diseases.
"Accumulating evidence indicates that visceral fat obesity is located upstream of the metabolic syndrome and atherosclerosis910. In the Human Body Map project11, our group demonstrated systematically for the first time that adipose tissue serves as not only an energy storage organ but also an endocrine organ12. "
[Show abstract][Hide abstract] ABSTRACT: Adiponectin, adipose-specific secretory protein, abundantly circulates in bloodstream and its concentration is around 1000-fold higher than that of other cytokines and hormones. Hypoadiponectinemia is a risk factor for atherosclerosis. There is little or no information on ultrastructural localization of adiponectin in the vasculature. Herein we investigated the localization of vascular adiponectin in the aorta using the immunoelectron microscopic technique. In wild-type (WT) mice, adiponectin was mainly detected on the luminal surface membrane of endothelial cells (ECs) and also found intracellularly in the endocytic vesicles of ECs. In the atherosclerotic lesions of apolipoprotein E-knockout (ApoE-KO) mice, adiponectin was detected in ECs, on the cell surface membrane of synthetic smooth muscle cells, and on the surface of monocytes adherent to ECs. Changes in adiponectin localization within the wall of the aorta may provide novel insight into the pathogenesis of atherosclerosis.
"The imbalance between caloric intake and energy consumption, high-calorie diets and physical inactivity, are major causes of metabolic syndrome (MetS), which manifests as accumulation of visceral fat and insulin resistance . The prevention of MetS is an important issue, as it is a major cause of cardiovascular disease (CVD) [2,3]. "
[Show abstract][Hide abstract] ABSTRACT: A high-calorie diet and physical inactivity, an imbalance between caloric intake and energy consumption, are major causes of metabolic syndrome (MetS), which manifests as accumulation of visceral fat and insulin resistance. However, the lifestyle-related factors associated with visceral fat mass in healthy men are not fully understood.
We evaluated visceral fat area (VFA), skeletal muscle mass, caloric intake, and energy expenditure in 67 healthy male participants (mean age, 36.9 +/- 8.8 years; body mass index 23.4 +/- 2.5 kg/m2).
Multiple regression analysis showed that the total skeletal muscle mass (P < 0.001) were negatively and age (P < 0.001) were positively associated with VFA. Lower limb muscle mass (P < 0.001) was strongly associated with VFA. However, total caloric intake, total energy expenditure, and energy expenditure during exercise were not associated with VFA.
Skeletal muscle mass especially lower limb muscle mass negatively contributes to visceral fat mass in healthy men. Therefore, maintaining lower limb muscular fitness through daily activity may be a useful strategy for controlling visceral obesity and metabolic syndrome.
"For example, dysregulation of adipocytokines (e.g. TNF-α, plasminogen activator inhibitor type 1 (SERPINE1), heparin-binding epidermal growth factor-like growth factor) and adiponectin contributes to the development of a variety of cardiovascular disease . Similarly, secretory proteins also play a role in infectious disease. "
[Show abstract][Hide abstract] ABSTRACT: Mycoplasma pneumoniae (M. pneumoniae) is one of the major etiological agents for community-acquired pneumonia (CAP) in all age groups. The early host response to M. pneumoniae infection relies on the concerted release of proteins with various biological activities. However, no comprehensive analysis of the secretory proteins has been conducted to date regarding the host response upon M. pneumoniae infection.
We employed the liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based label-free quantitative proteomic technology to identify and characterize the members of the human alveolar epithelial carcinoma A549 cell secretome during M. pneumoniae infection. A total of 256 proteins were identified, with 113 being differentially expressed (>1.5-fold change), among which 9 were only expressed in control cells, 10 only in M. pneumoniae-treated cells, while 55 were up-regulated and 39 down-regulated by M. pneumoniae. The changed expression of some of the identified proteins was validated by RT-PCR and immunoblot analysis. Cellular localization analysis of the secretome data revealed 59.38% of the proteins were considered as "putative secretory proteins". Functional analysis revealed that the proteins affected upon M. pneumoniae infection were mainly related to metabolic process, stress response, and immune response. We further examined the level of one up-regulated protein, IL-33, in clinical samples. The result showed that IL-33 levels were significantly higher in the plasma and bronchoalveolar lavage fluid (BALF) of M. pneumoniae pneumonia (MPP) patients.
The present study provided systematic information about the changes in the expression of secretory proteins during M. pneumoniae infection, which is useful for the discovery of specific biomarkers and targets for pharmacological intervention.
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