Nonalcoholic fatty liver disease （NAFLD） is an increasingly recognized cause of liver-related morbidity and mortality. It can develop secondary to numerous causes but a great majority of NAFLD cases occur in patient...Nonalcoholic fatty liver disease （NAFLD） is an increasingly recognized cause of liver-related morbidity and mortality. It can develop secondary to numerous causes but a great majority of NAFLD cases occur in patients who are obese or present with other components of metabolic syndrome （hypertension, dyslipidemia, diabetes）. This is called primary NAFLD and insulin resistance plays a key role in its pathogenesis. Obesity is characterized by expanded adipose tissue, which is under a state of chronic inflammation. This disturbs the normal storage and endocrine functions of adipose tissue. In obesity, the secretome （adipokines, oytokines, free fatty acids and other lipid moieties） of fatty tissue is amplified, which through its autocrine, paracrine actions in fat tissue and systemic effects especially in the liver leads to an altered metabolic state with insulin resistance （IR）. IR leads to hyperglycemia and reactive hyperinsulinemia, which stimulates lipid-accumulating processes and impairs hepatic lipid metabolism. IR enhances free fatty acid delivery to liver from the adipose tissue storage due to uninhibited lipolysis. These changes result in hepatic abnormal fat accumulation, which may initiate the hepatic IR and further aggravate the altered metabolic state of whole body. Hepatic steatosis can also be explained by the fact that there is enhanced dietary fat delivery and physical inactivity. IR and NAFLD are also seen in various lipodystrophic states in contrary to popular belief that these problems only occur due to excessive adiposity in obesity. Hence, altered physiology of adipose tissue is central to development of IR, metabolic syndrome and NAFLD.展开更多
Nonalcoholic fatty liver disease (NAFLD) is a condition in which excess fat accumulates in the liver of a patient with no history of alcohol abuse or other causes for secondary hepatic steatosis. The pathogenesis of N...Nonalcoholic fatty liver disease (NAFLD) is a condition in which excess fat accumulates in the liver of a patient with no history of alcohol abuse or other causes for secondary hepatic steatosis. The pathogenesis of NAFLD and nonalcoholic steatohepatitis (NASH) has not been fully elucidated. The “two-hit“ hypothesis is probably a too simplified model to elaborate complex pathogenetic events occurring in patients with NASH. It should be better regarded as a multiple step process, with accumulation of liver fat being the first step, followed by the development of necroinflammation and fibrosis. Adipose tissue, which has emerged as an endocrine organ with a key role in energy homeostasis, is responsive to both central and peripheral metabolic signals and is itself capable of secreting a number of proteins. These adipocyte-specific or enriched proteins, termed adipokines, have been shown to have a variety of local, peripheral, and central effects. In the current review, we explore the role of adipocytokines and proinflammatory cytokines in the pathogenesis of NAFLD. We particularly focus on adiponectin, leptin and ghrelin, with a brief mention of resistin, visfatin and retinol-binding protein 4 among adipokines, and tumor necrosis factor-α, interleukin (IL)-6, IL-1, and briefly IL-18 among proinflammatory cytokines. We update their role in NAFLD, as elucidated in experimental models and clinical practice.展开更多
Non-alcoholic fatty liver disease (NAFLD) is recognized as the most common type of chronic liver disease in Western countries.Insulin resistance is a key factor in the pathogenesis of NAFLD,the latter being considered...Non-alcoholic fatty liver disease (NAFLD) is recognized as the most common type of chronic liver disease in Western countries.Insulin resistance is a key factor in the pathogenesis of NAFLD,the latter being considered as the hepatic component of insulin resistance or obesity.Adiponectin is the most abundant adipose-specific adipokine.There is evidence that adiponectin decreases hepatic and systematic insulin resistance,and attenuates liver inflammation and fibrosis.Adiponectin generally predicts steatosis grade and the severity of NAFLD;however,to what extent this is a direct effect or related to the presence of more severe insulin resistance or obesity remains to be addressed.Although there is no proven pharmacotherapy for the treatment of NAFLD,recent therapeutic strategies have focused on the indirect upregulation of adiponectin through the administration of various therapeutic agents and/or lifestyle modifications.In this adiponectin-focused review,the pathogenetic role and the potential therapeutic benefits of adiponectin in NAFLD are analyzed systematically.展开更多
Intrahepatic fat deposition has been demonstrated in patients with nonalcoholic fatty liver disease(NAFLD). Genetic and environmental factors are important for the development of NAFLD. Diseases such as obesity, diabe...Intrahepatic fat deposition has been demonstrated in patients with nonalcoholic fatty liver disease(NAFLD). Genetic and environmental factors are important for the development of NAFLD. Diseases such as obesity, diabetes, and hypertension have been found to be closely associated with the incidence of NAFLD. Evi-dence suggests that obesity and insulin resistance are the major factors that contribute to the development of NAFLD. In comparing the factors that contribute to the buildup of excess calories in obesity, an imbalance of energy homeostasis can be considered as the basis. Among the peripheral signals that are generated to regulate the uptake of food, signals from adipose tissue are of major relevance and involve the maintenance of energy homeostasis through processes such as lipo-genesis, lipolysis, and oxidation of fatty acids. Advances in research on adipose tissue suggest an integral role played by adipokines in NAFLD. Cytokines secreted by adipocytes, such as tumor necrosis factor-α, transform-ing growth factor-β, and interleukin-6, are implicated in NAFLD. Other adipokines, such as leptin and adiponectin and, to a lesser extent, resistin and retinol binding protein-4 are also involved. Leptin and adiponectin can augment the oxidation of fatty acid in liver by activating the nuclear receptor super-family of transcription fac-tors, namely peroxisome proliferator-activated receptor(PPAR)-α. Recent studies have proposed downregula-tion of PPAR-α in cases of hepatic steatosis. This re-view discusses the role of adipokines and PPARs with regard to hepatic energy metabolism and progression of NAFLD.展开更多
Free fatty acids are known to play a key role in promoting loss of insulin sensitivity in type 2 diabetes mellitus but the underlying mechanism is still unclear.It has been postulated that an increase in the intracell...Free fatty acids are known to play a key role in promoting loss of insulin sensitivity in type 2 diabetes mellitus but the underlying mechanism is still unclear.It has been postulated that an increase in the intracellular concentration of fatty acid metabolites activates a serine kinase cascade,which leads to defects in insu-lin signaling downstream to the insulin receptor.In addition,the complex network of adipokines released from adipose tissue modulates the response of tissues to insulin.Among the many molecules involved in the intracellular processing of the signal provided by insulin,the insulin receptor substrate-2,the protein kinase B and the forkhead transcription factor Foxo 1a are of particular interest,as recent data has provided strong evidence that dysfunction of these proteins results in insulin resistance in vivo.Recently,studies have revealed that phosphoinositidedependent kinase 1-independent phosphorylation of protein kinase Cε causes a reduction in insulin receptor gene expression.Additionally,it has been suggested that mitochondrial dysfunction triggers activation of several serine kinases,and weakens insulin signal transduction.Thus,in this review,the current developments in understanding the pathophysiological processes of insulin resistance in type 2 diabetes have been summarized.In addition,this study provides potential new targets for the treatment and prevention of type 2 diabetes.展开更多
Non-alcoholic fatty liver disease (NAFLD), a further expression of metabolic syndrome, strictly linked to obesity and diabetes mellitus, is characterized by insulin resistance (IR), elevated serum levels of free fatty...Non-alcoholic fatty liver disease (NAFLD), a further expression of metabolic syndrome, strictly linked to obesity and diabetes mellitus, is characterized by insulin resistance (IR), elevated serum levels of free fatty acids and fatty infi ltration of the liver, which is known as hepatic steatosis. Hepatocyte apoptosis is a key feature of this disease and correlates with its severity. Free-fatty-acidinduced toxicity represents one of mechanisms for the pathogenesis of NAFLD and hormones, growth factors and adipokines influence also play a key role. This review highlights the various pathways that contribute to the development of hepatic steatosis. Circulating concentrations of inflammatory cytokines are reckoned to be the most important factor in causing and maintaining IR. Low-grade chronic inflammation is fundamental in the progression of NAFLD toward higher risk cirrhotic states.展开更多
AIM:To analyze the prognostic value of adipokines in predicting the course,complications and fatal outcome of acute pancreatitis(AP).METHODS:We performed the search of PubMed database and the systemic analysis of the ...AIM:To analyze the prognostic value of adipokines in predicting the course,complications and fatal outcome of acute pancreatitis(AP).METHODS:We performed the search of PubMed database and the systemic analysis of the literature for both experimental and human studies on prognostic value of adipokines in AP for period 2002-2012.Only the papers that described the use of adipokines for prediction of severity and/or complications of AP were selected for further analysis.Each article had to contain information about the levels of measured adipokines,diagnosis and verification of AP,to specify presence of pancreatic necrosis,organ dysfunction and/or mortality rates.From the very beginning,study was carried out adhering to the PRISMA checklist and flowchart for systemic reviews.To assess quality of all included human studies,the Quality Assessment of Diagnostic Accuracy Studies tool was used.Because of the high heterogeneity between the studies,it was decided to refrain from the statistical processing or meta-analysis of the available data.RESULTS:Nine human and three experimental studies were included into review.In experimental studies significant differences between leptin concentrations at 24 and 48 h in control,acute edematous and acute necrotizing pancreatitis groups were found(P = 0.027 and P < 0.001).In human studies significant differences between leptin and resitin concentrations in control and acute pancreatitis groups were found.1-3 d serum adiponectin threshold of 4.5 μg/mL correctly classified the severity of 81% of patients with AP.This threshold yielded a sensitivity of 70%,specificity 85%,positive predictive value 64%,negative predictive value88%(area under curve 0.75).Resistin and visfatin concentrations differ significantly between mild and severe acute pancreatitis groups,they correlate with severity of disease,need for interventions and outcome.Both adipokines are good markers for parapancreatic necrosis and the cut-off values of 11.9 ng/mL and 1.8 ng/mL respectively predict the high ranges of radi展开更多
Osteoarthritis(OA)is one of the most common degenerative joint diseases in aging population.Obesity is an important risk factor for initiation and progression of OA.It is accepted that excess body weight may lead to c...Osteoarthritis(OA)is one of the most common degenerative joint diseases in aging population.Obesity is an important risk factor for initiation and progression of OA.It is accepted that excess body weight may lead to cartilage degeneration by increasing the mechanical forces across weight-bearing joints.However,emerging data suggest that additional metabolic factors released mainly by white adipose tissue may also be responsible for the high prevalence of OA among obese people.Adipocyte-derived molecules‘‘adipokines’’have prompt much interest in OA pathophysiological research over the past decade since they play an important role in cartilage and bone homeostasis.Therefore,the aim of this review is to summarize the current knowledge on the role of adipokines including leptin,adiponectin,visfatin and resistin in OA and their potential to be used as biomarkers for earlier diagnosis,classifying disease severity,monitoring disease progression,and testing pharmacological interventions for OA.In OA patients,leptin,visfatin and resistin showed increased production whereas adiponectin showed decreased production.Leptin and adiponectin are far more studied than visfatin and resistin.Importantly,altered adipokine levels also contribute to a wide range of diseases.Further experiments are still crucial for understanding the relationship between adipokines and OA.展开更多
文摘Nonalcoholic fatty liver disease （NAFLD） is an increasingly recognized cause of liver-related morbidity and mortality. It can develop secondary to numerous causes but a great majority of NAFLD cases occur in patients who are obese or present with other components of metabolic syndrome （hypertension, dyslipidemia, diabetes）. This is called primary NAFLD and insulin resistance plays a key role in its pathogenesis. Obesity is characterized by expanded adipose tissue, which is under a state of chronic inflammation. This disturbs the normal storage and endocrine functions of adipose tissue. In obesity, the secretome （adipokines, oytokines, free fatty acids and other lipid moieties） of fatty tissue is amplified, which through its autocrine, paracrine actions in fat tissue and systemic effects especially in the liver leads to an altered metabolic state with insulin resistance （IR）. IR leads to hyperglycemia and reactive hyperinsulinemia, which stimulates lipid-accumulating processes and impairs hepatic lipid metabolism. IR enhances free fatty acid delivery to liver from the adipose tissue storage due to uninhibited lipolysis. These changes result in hepatic abnormal fat accumulation, which may initiate the hepatic IR and further aggravate the altered metabolic state of whole body. Hepatic steatosis can also be explained by the fact that there is enhanced dietary fat delivery and physical inactivity. IR and NAFLD are also seen in various lipodystrophic states in contrary to popular belief that these problems only occur due to excessive adiposity in obesity. Hence, altered physiology of adipose tissue is central to development of IR, metabolic syndrome and NAFLD.
文摘Nonalcoholic fatty liver disease (NAFLD) is a condition in which excess fat accumulates in the liver of a patient with no history of alcohol abuse or other causes for secondary hepatic steatosis. The pathogenesis of NAFLD and nonalcoholic steatohepatitis (NASH) has not been fully elucidated. The “two-hit“ hypothesis is probably a too simplified model to elaborate complex pathogenetic events occurring in patients with NASH. It should be better regarded as a multiple step process, with accumulation of liver fat being the first step, followed by the development of necroinflammation and fibrosis. Adipose tissue, which has emerged as an endocrine organ with a key role in energy homeostasis, is responsive to both central and peripheral metabolic signals and is itself capable of secreting a number of proteins. These adipocyte-specific or enriched proteins, termed adipokines, have been shown to have a variety of local, peripheral, and central effects. In the current review, we explore the role of adipocytokines and proinflammatory cytokines in the pathogenesis of NAFLD. We particularly focus on adiponectin, leptin and ghrelin, with a brief mention of resistin, visfatin and retinol-binding protein 4 among adipokines, and tumor necrosis factor-α, interleukin (IL)-6, IL-1, and briefly IL-18 among proinflammatory cytokines. We update their role in NAFLD, as elucidated in experimental models and clinical practice.
文摘Non-alcoholic fatty liver disease (NAFLD) is recognized as the most common type of chronic liver disease in Western countries.Insulin resistance is a key factor in the pathogenesis of NAFLD,the latter being considered as the hepatic component of insulin resistance or obesity.Adiponectin is the most abundant adipose-specific adipokine.There is evidence that adiponectin decreases hepatic and systematic insulin resistance,and attenuates liver inflammation and fibrosis.Adiponectin generally predicts steatosis grade and the severity of NAFLD;however,to what extent this is a direct effect or related to the presence of more severe insulin resistance or obesity remains to be addressed.Although there is no proven pharmacotherapy for the treatment of NAFLD,recent therapeutic strategies have focused on the indirect upregulation of adiponectin through the administration of various therapeutic agents and/or lifestyle modifications.In this adiponectin-focused review,the pathogenetic role and the potential therapeutic benefits of adiponectin in NAFLD are analyzed systematically.
文摘Intrahepatic fat deposition has been demonstrated in patients with nonalcoholic fatty liver disease(NAFLD). Genetic and environmental factors are important for the development of NAFLD. Diseases such as obesity, diabetes, and hypertension have been found to be closely associated with the incidence of NAFLD. Evi-dence suggests that obesity and insulin resistance are the major factors that contribute to the development of NAFLD. In comparing the factors that contribute to the buildup of excess calories in obesity, an imbalance of energy homeostasis can be considered as the basis. Among the peripheral signals that are generated to regulate the uptake of food, signals from adipose tissue are of major relevance and involve the maintenance of energy homeostasis through processes such as lipo-genesis, lipolysis, and oxidation of fatty acids. Advances in research on adipose tissue suggest an integral role played by adipokines in NAFLD. Cytokines secreted by adipocytes, such as tumor necrosis factor-α, transform-ing growth factor-β, and interleukin-6, are implicated in NAFLD. Other adipokines, such as leptin and adiponectin and, to a lesser extent, resistin and retinol binding protein-4 are also involved. Leptin and adiponectin can augment the oxidation of fatty acid in liver by activating the nuclear receptor super-family of transcription fac-tors, namely peroxisome proliferator-activated receptor(PPAR)-α. Recent studies have proposed downregula-tion of PPAR-α in cases of hepatic steatosis. This re-view discusses the role of adipokines and PPARs with regard to hepatic energy metabolism and progression of NAFLD.
文摘Free fatty acids are known to play a key role in promoting loss of insulin sensitivity in type 2 diabetes mellitus but the underlying mechanism is still unclear.It has been postulated that an increase in the intracellular concentration of fatty acid metabolites activates a serine kinase cascade,which leads to defects in insu-lin signaling downstream to the insulin receptor.In addition,the complex network of adipokines released from adipose tissue modulates the response of tissues to insulin.Among the many molecules involved in the intracellular processing of the signal provided by insulin,the insulin receptor substrate-2,the protein kinase B and the forkhead transcription factor Foxo 1a are of particular interest,as recent data has provided strong evidence that dysfunction of these proteins results in insulin resistance in vivo.Recently,studies have revealed that phosphoinositidedependent kinase 1-independent phosphorylation of protein kinase Cε causes a reduction in insulin receptor gene expression.Additionally,it has been suggested that mitochondrial dysfunction triggers activation of several serine kinases,and weakens insulin signal transduction.Thus,in this review,the current developments in understanding the pathophysiological processes of insulin resistance in type 2 diabetes have been summarized.In addition,this study provides potential new targets for the treatment and prevention of type 2 diabetes.
文摘Non-alcoholic fatty liver disease (NAFLD), a further expression of metabolic syndrome, strictly linked to obesity and diabetes mellitus, is characterized by insulin resistance (IR), elevated serum levels of free fatty acids and fatty infi ltration of the liver, which is known as hepatic steatosis. Hepatocyte apoptosis is a key feature of this disease and correlates with its severity. Free-fatty-acidinduced toxicity represents one of mechanisms for the pathogenesis of NAFLD and hormones, growth factors and adipokines influence also play a key role. This review highlights the various pathways that contribute to the development of hepatic steatosis. Circulating concentrations of inflammatory cytokines are reckoned to be the most important factor in causing and maintaining IR. Low-grade chronic inflammation is fundamental in the progression of NAFLD toward higher risk cirrhotic states.
文摘AIM:To analyze the prognostic value of adipokines in predicting the course,complications and fatal outcome of acute pancreatitis(AP).METHODS:We performed the search of PubMed database and the systemic analysis of the literature for both experimental and human studies on prognostic value of adipokines in AP for period 2002-2012.Only the papers that described the use of adipokines for prediction of severity and/or complications of AP were selected for further analysis.Each article had to contain information about the levels of measured adipokines,diagnosis and verification of AP,to specify presence of pancreatic necrosis,organ dysfunction and/or mortality rates.From the very beginning,study was carried out adhering to the PRISMA checklist and flowchart for systemic reviews.To assess quality of all included human studies,the Quality Assessment of Diagnostic Accuracy Studies tool was used.Because of the high heterogeneity between the studies,it was decided to refrain from the statistical processing or meta-analysis of the available data.RESULTS:Nine human and three experimental studies were included into review.In experimental studies significant differences between leptin concentrations at 24 and 48 h in control,acute edematous and acute necrotizing pancreatitis groups were found(P = 0.027 and P < 0.001).In human studies significant differences between leptin and resitin concentrations in control and acute pancreatitis groups were found.1-3 d serum adiponectin threshold of 4.5 μg/mL correctly classified the severity of 81% of patients with AP.This threshold yielded a sensitivity of 70%,specificity 85%,positive predictive value 64%,negative predictive value88%(area under curve 0.75).Resistin and visfatin concentrations differ significantly between mild and severe acute pancreatitis groups,they correlate with severity of disease,need for interventions and outcome.Both adipokines are good markers for parapancreatic necrosis and the cut-off values of 11.9 ng/mL and 1.8 ng/mL respectively predict the high ranges of radi
基金Supported by Post-Doctoral Fellowship Research Grant from Ratchadaphiseksomphot Endowment FundChulalongkorn University,Ratchadapiseksompotch Fund+1 种基金Faculty of Medicine,Chulalongkorn University,Thailand Research Fundthe Commission of Higher Education
文摘Osteoarthritis(OA)is one of the most common degenerative joint diseases in aging population.Obesity is an important risk factor for initiation and progression of OA.It is accepted that excess body weight may lead to cartilage degeneration by increasing the mechanical forces across weight-bearing joints.However,emerging data suggest that additional metabolic factors released mainly by white adipose tissue may also be responsible for the high prevalence of OA among obese people.Adipocyte-derived molecules‘‘adipokines’’have prompt much interest in OA pathophysiological research over the past decade since they play an important role in cartilage and bone homeostasis.Therefore,the aim of this review is to summarize the current knowledge on the role of adipokines including leptin,adiponectin,visfatin and resistin in OA and their potential to be used as biomarkers for earlier diagnosis,classifying disease severity,monitoring disease progression,and testing pharmacological interventions for OA.In OA patients,leptin,visfatin and resistin showed increased production whereas adiponectin showed decreased production.Leptin and adiponectin are far more studied than visfatin and resistin.Importantly,altered adipokine levels also contribute to a wide range of diseases.Further experiments are still crucial for understanding the relationship between adipokines and OA.
