Alcohol-induced fatty liver (steatosis) was believed to result from excessive generation of reducing equivalents from ethanol metabolism, thereby enhancing fat accumulation. Recent findings have revealed a more comple...Alcohol-induced fatty liver (steatosis) was believed to result from excessive generation of reducing equivalents from ethanol metabolism, thereby enhancing fat accumulation. Recent findings have revealed a more complex picture in which ethanol oxidation is still required, but specific transcription as well as humoral factors also have important roles. Transcription factors involved include the sterol regulatory element binding protein 1 (SREBP-1) which is activated to induce genes that regulate lipid biosynthesis. Conversely, ethanol consumption causes a general down-regulation of lipid (fatty acid) oxidation, a reflection of inactivation of the peroxisome proliferator- activated receptor-alpha (PPAR-α) that regulates genes involved in fatty acid oxidation. A third transcription factor is the early growth response-1 (Egr-1), which is strongly induced prior to the onset of steatosis. The activities of all these factors are governed by that of the principal regulatory enzyme, AMP kinase. Important humoral factors, including adiponectin, and tumor necrosis factor-α (TNF-α), also regulate alcohol-induced steatosis. Their levels are affected by alcohol consumption and by each other. This review will summarize the actions of these proteins in ethanol-elicited fatty liver. Because steatosis is now regarded as a significant risk factor for advanced liver pathology, an understanding of the molecular mechanisms in its etiology is essential for development of effective therapies.展开更多
The majority of ethanol metabolism occurs in the liver. Consequently, this organ sustains the greatest damage from ethanol abuse. Ethanol consumption disturbs the delicate balance of protein homeostasis in the liver, ...The majority of ethanol metabolism occurs in the liver. Consequently, this organ sustains the greatest damage from ethanol abuse. Ethanol consumption disturbs the delicate balance of protein homeostasis in the liver, causing intracellular protein accumulation due to a disruption of hepatic protein catabolism. Evidence indicates that ethanol or its metabolism impairs trafficking events in the liver, including the process of macroautophagy, which is the engulfment and degradation of cytoplasmic constituents by the lysosomal system. Autophagy is an essential, ongoing cellular process that is highly regulated by nutrients, endocrine factors and signaling pathways. A great number of the genes and gene products that govern the autophagic response have been characterized and the major metabolic and signaling pathways that activate or suppress autophagy have been identified. This review describes the process of autophagy, its regulation and the possible mechanisms by which ethanol disrupts the process of autophagic degradation. The implications of autophagic suppression are discussed in relation to the pathogenesis of alcohol-induced liver injury.展开更多
Alcoholic patients have a high incidence of hepatitis C virus （HCV） infection. Alcohol consumption enhances the severity of the HCV disease course and worsens the outcome of chronic hepatitis C. The accumulation of ...Alcoholic patients have a high incidence of hepatitis C virus （HCV） infection. Alcohol consumption enhances the severity of the HCV disease course and worsens the outcome of chronic hepatitis C. The accumulation of virally infected cells in the liver is related to the HCV- induced inability of the immune system to recognize infected cells and to develop the immune responses. This review covers the effects of HCV proteins and ethanol on major histocompatibility complex （MHC） class Ⅰ- and class Ⅱ-restricted antigen presentation. Here, we discuss the liver which functions as an immune privilege organ; factors, which affect cleavage and loading of antigenic peptides onto MHC class I and class ~I in hepatocytes and dendritic cells, and the modulating effects of ethanol and HCV on antigen presentation by liver cells. Altered antigen presentation in the liver limits the ability ＇of the immune system to clear HCV and infected cells and contributes to disease progression. HCV by itself affects dendritic cell function, switching their cytokine profile to the suppressive phenotype of interleukin-10 （IL-10） and transforming growth factor beta （TGFβ） predominance, preventing cell maturation and allostimulation capacity. The synergistic action of ethanol with HCV results in the suppression of MHC class Ⅱ-restricted antigen presentation. In addition, ethanol metabolism and HCV proteins reduce proteasome function and interferon signaling, thereby suppressing the generation of peptides for MHC class I -restricted antigen presentation. Collectively, ethanol exposure further impairs antigen presentation in HCV-infected liver cells, which may provide a partial explanation for exacerbations and the poor outcome of HCV infection in alcoholics.展开更多
The proteasome is a major protein-degrading enzyme, which catalyzes degradation of oxidized and aged proteins, signal transduction factors and cleaves peptides for antigen presentation. Proteasome exists in the equili...The proteasome is a major protein-degrading enzyme, which catalyzes degradation of oxidized and aged proteins, signal transduction factors and cleaves peptides for antigen presentation. Proteasome exists in the equilibrium of 26S and 20S particles. Proteasome function is altered by ethanol metabolism, depending on oxidative stress levels： low oxidative stress induces proteasome activity, while high oxidative stress reduces it. The proposed mechanisms for modulation of proteasome activity are related to oxidative modification of proteasomal proteins with primary and secondary products derived from ethanol oxidation. Decreased proteolysis by the proteasome results in the accumulation of insoluble protein aggregates, which cannot be degraded by proteasome and which further inhibit proteasome function. Mallory bodies, a common signature of alcoholic liver diseases, are formed by liver cells, when proteasome is unable to remove cytokeratins. Proteasome inhibition by ethanol also promotes the accumulation of pro-apoptotic factors in mitochondria of ethanol-metabolizing liver cells that are normally degraded by proteasome. In addition, decreased proteasome function also induces accumulation of the negative regulators of cytokine signaling （I-~B and SOCS）, thereby blocking cytokine signal transduction. Finally, ethanol-elicited blockade of interferon type 2 and 2 signaling and decreased proteasome function impairs generation of peptides for MHC class Ⅰ-restricted antigen presentation.展开更多
Fibronectins are adhesive glycoproteins that can be found in tissue matrices and circulating in various fluids of the body. The variable composition of fibronectin molecules facilitates a diversity of interactions wit...Fibronectins are adhesive glycoproteins that can be found in tissue matrices and circulating in various fluids of the body. The variable composition of fibronectin molecules facilitates a diversity of interactions with cell surface receptors that suggest a role for these proteins beyond the structural considerations of the extracellular matrix. These interactions implicate fibronectin in the regulation of mechanisms that also determine cell behavior and activity. The two major forms, plasma fibronectin (pFn) and cellular fibronectin (cFn), exist as balanced amounts under normal physiological conditions. However, during injury and/or disease, tissue and circulating levels of cFn become disproportionately elevated. The accumulating cFn, in addition to being a consequence of prolonged tissue damage, may in factstimulate cellular events that promote further damage. In this review, we summarize what is known regarding such interactions between fibronectin and cells that may influence the biological response to injury. We elaborate on the effects of cFn in the liver, specifically under a condition of chronic alcohol-induced injury. Studies have revealed that chronic alcohol consumption stimulates excess production of cFn by sinusoidal endothelial cells and hepatic stellate cells while impairing its clearance by other cell types resulting in the build up of this glycoprotein throughout the liver and its consequent increased availability to influence cellular activity that could promote the development of alcoholic liver disease. We describe recent findings by our laboratory that support a plausible role for cFn in the promotion of liver injury under a condition of chronic alcohol abuse and the implications of cFn stimulation on the pathogenesis of alcoholic liver disease. These findings suggest an effect of cFn in regulating cell behavior in the alcohol-injured liver that is worth further characterizing not only to gain a more comprehensive understanding of the role this reactive glycoprotein plays in the progression of injury but also for the insight further studies could provide towards the development of novel therapies for alcoholic liver disease.展开更多
The asialoglycoprotein （ASGP） receptor is a wellcharacterized hepatic receptor that is recycled via the common cellular process of receptor-mediated endocytosis （RME）. The RME process plays an integral part in the...The asialoglycoprotein （ASGP） receptor is a wellcharacterized hepatic receptor that is recycled via the common cellular process of receptor-mediated endocytosis （RME）. The RME process plays an integral part in the proper trafficking and routing of receptors and ligands in the healthy cell. Thus, the missorting or altered transport of proteins during RME is thought to play a role in several diseases associated with hepatocyte and liver dysfunction. Previously, we examined in detail alterations that occur in hepatocellular RME and associated receptor functions as a result of one particular liver injury, alcoholic liver disease （ALD）. The studies revealed profound ethanol- mediated impairments to the ASGP receptor and the RME process, indicating the importance of this receptor and the maintenance of proper endocytic events in normal tissue. To further clarify these observations, studies were performed utilizing knockout mice （lacking a functional ASGP receptor） to which were administered several liver toxicants. In addition to alcohol, we examined the effects following administration of anti- Fas （CD95） antibody, carbon tetrachloride （CCh） and lipopolysaccharide （LPS）/galactosamine. The results of these studies demonstrated that the knockout mice sustained enhanced liver injury in response to all of the treatments, as shown by increased indices of liver damage, such as enhancement of serum enzyme levels, histopathological scores, as well as hepatocellular death. Overall, the work completed to date suggests a possible link between hepatic receptors and liver injury. In particular, adequate function and content of the ASGP receptor may provide protection against various toxinmediated liver diseases.展开更多
AIM:To examine the consequences of cellular f ibronectin(cFn)accumulation during alcohol-induced injury,and inv estigate whether increased cFn could have an effect on hepatocytes(HCs)by producing factors that could co...AIM:To examine the consequences of cellular f ibronectin(cFn)accumulation during alcohol-induced injury,and inv estigate whether increased cFn could have an effect on hepatocytes(HCs)by producing factors that could cont ribute to alcohol-induced liver injury.METHODS:HCs were isolated from rats fed a control or ethanol liquid diet for four to six weeks.Exogenous c Fn(up to 7.5 μg/mL)was added to cells cultured for 20 h,and viability(lactate dehydrogenase),apoptosis(caspase activity)and se cretion of proinflammat-ory cytokines(tumor ne c rosis fac tor alpha,TNF-α and interleukin 6,IL-6),mat rix metalloproteinases(MMPs)and their inhibitors(tissue inhibitors of metall-oproteinases,TIMPs)was det ermined.Degrad ation of iodinated cFn was det ermined over a 3 h time period in the preparations.RESULTS:cFn degradation is impaired in HCs isolated from ethanol-fed animals,leading to its accumulation in the matrix.Addition of exogenous cFn did not affect viability of HCs from control or ethanolfed animals,and apoptosis was affected only at the higher concentration.Sec retion of MMPs,TIMPs,TNF-α and IL-6,however,was increased by exogenously added cFn,with HCs from ethanolfed animals showing increased susceptibility compared to the controls.CONCLUSION:These results suggest that the elevated amounts of cFn observed in alcoholic liver injury can stimulate hepatocytes to produce factors which promote further tissue damage.展开更多
An annual topic highlight: Alcohol and Liver, 2011, covers the important and new aspects of pathogenesis of alcoholic liver diseases (ALD). It includes broad topics ranging from the exacerbation of ALD by infectious (...An annual topic highlight: Alcohol and Liver, 2011, covers the important and new aspects of pathogenesis of alcoholic liver diseases (ALD). It includes broad topics ranging from the exacerbation of ALD by infectious (viral) agents (hepatitis C virus and human immunodeficiency virus) to the influence of alcohol on liver fibrogenesis, lipid rafts, autophagy and other aspects. This issue is recommended for both basic scientists and clinicians who are involved in alcoholic liver research.展开更多
Liver is known as an organ that is primarily affected by alcohol. Alcoholic liver disease (ALD) is the cause of an increased morbidity and mortality worldwide. Progression of ALD is driven by "second hits". ...Liver is known as an organ that is primarily affected by alcohol. Alcoholic liver disease (ALD) is the cause of an increased morbidity and mortality worldwide. Progression of ALD is driven by "second hits". These second hits include the complex of nutritional, pharmacological, genetic and viral factors, which aggravate liver pathology. However, in addition to liver failure, ethanol causes damage to other organs and systems. These extrahepatic manifestations are regulated via the similar hepatitis mechanisms. In the Topic Highlight series, we provide an update of current knowledge in the f ield of ALD.展开更多
AIM： To investigate the role of reactive oxygen species （ROS） in ethanol-mediated cell death of polarized hepatic （WlF-B） cells.METHODS： In this work, WIF-B cultures were treated with pyrazole （inducer of cytoc...AIM： To investigate the role of reactive oxygen species （ROS） in ethanol-mediated cell death of polarized hepatic （WlF-B） cells.METHODS： In this work, WIF-B cultures were treated with pyrazole （inducer of cytochrome P4502E1, CYP2E1） and/or L-buthionine sulfoximine （BSO）, a known inhibitor of hepatic glutathione （GSH）, followed by evaluation of ROS production, antioxidant levels, and measures of cell injury （apoptosis and necrosis）.RESULTS： The results revealed that ethanol treatment alone caused a significant two-fold increase in the activation of caspase-3 as well as a similar doubling in ROS. When the activity of the CYP2E1 was increased by pyrazole pretreatment, an additional two-fold elevation in ROS was detected. However, the CYP2EIrelated ROS elevation was not accompanied with a correlative increase in apoptotic cell injury, but rather was found to be associated with an increase in necrotic cell death. Interestingly, when the thiol status of the cells was manipulated using BSO, the ethanol-induced activation of caspase-3 was abrogated. Additionally, ethanol-treated cells displayed enhanced susceptibility to Fas-mediated apoptosis that was blocked by GSH depletion as a result of diminished caspase-8 activity.CONCLUSION： Apoptotic cell death induced as a consequence of ethanol metabolism is not completely dependent upon ROS status but is dependent on sustained GSH levels,展开更多
Chronic ethanol consumption is associated with serious and potentially fatal alcohol-related liver injuries such as hepatomegaly, alcoholic hepatitis and cirrhosis. Moreover, it has been documented that the clinical p...Chronic ethanol consumption is associated with serious and potentially fatal alcohol-related liver injuries such as hepatomegaly, alcoholic hepatitis and cirrhosis. Moreover, it has been documented that the clinical progression of alcohol-induced liver damage may be associated with an increase in hepatocellular death that involves apoptotic mechanisms. Although much information has been learned about the clinical manifestations associated with alcohol-related diseases, the search continues for a better understanding of the molecular and/or cellular mechanisms by which ethanol exerts its deleterious effects such as the induction of pro-apoptotic mechanisms and related cell damaging events. As part of the effort to enhance our understanding of those particular cellular pathways and mechanisms associated with ethanol toxicity, researchers over the years have utilized a variety of model systems. Recently, work has come forth demonstrating the utility of a hybrid cell line (WIF-B) as a cell culture model system for the study of alcohol-associated alterations in hepatocellular mechanisms. Success with such emerging model systems could aid in the development of potential therapeutic treatments for the prevention of alcohol- induced apoptotic cell death that may ultimately serve as a significant target in delaying the onset and/or progression of clinical symptoms of alcohol-mediated liver disease. This review article summarizes the current understanding of ethanol-mediated modifications in cell survival and thus the promotion of pro-apoptotic events with emphasis on analyses made in various experimental model systems, particularly the more recently characterized WIF-B cell system.展开更多
基金Supported by New Research Grant from the University of Nebraska Medical Center, the NIAAA, and Medical Research Funds from the Department of Veterans Affairs, United States
文摘Alcohol-induced fatty liver (steatosis) was believed to result from excessive generation of reducing equivalents from ethanol metabolism, thereby enhancing fat accumulation. Recent findings have revealed a more complex picture in which ethanol oxidation is still required, but specific transcription as well as humoral factors also have important roles. Transcription factors involved include the sterol regulatory element binding protein 1 (SREBP-1) which is activated to induce genes that regulate lipid biosynthesis. Conversely, ethanol consumption causes a general down-regulation of lipid (fatty acid) oxidation, a reflection of inactivation of the peroxisome proliferator- activated receptor-alpha (PPAR-α) that regulates genes involved in fatty acid oxidation. A third transcription factor is the early growth response-1 (Egr-1), which is strongly induced prior to the onset of steatosis. The activities of all these factors are governed by that of the principal regulatory enzyme, AMP kinase. Important humoral factors, including adiponectin, and tumor necrosis factor-α (TNF-α), also regulate alcohol-induced steatosis. Their levels are affected by alcohol consumption and by each other. This review will summarize the actions of these proteins in ethanol-elicited fatty liver. Because steatosis is now regarded as a significant risk factor for advanced liver pathology, an understanding of the molecular mechanisms in its etiology is essential for development of effective therapies.
基金Supported by Development funds from the Section of Gastroenterology/Hepatology, University of Nebraska Medical CenterBridge Research Grant from the University of Nebraska Medical CenterMedical Research Funds from the Department of Veterans Affairs, United States of America
文摘The majority of ethanol metabolism occurs in the liver. Consequently, this organ sustains the greatest damage from ethanol abuse. Ethanol consumption disturbs the delicate balance of protein homeostasis in the liver, causing intracellular protein accumulation due to a disruption of hepatic protein catabolism. Evidence indicates that ethanol or its metabolism impairs trafficking events in the liver, including the process of macroautophagy, which is the engulfment and degradation of cytoplasmic constituents by the lysosomal system. Autophagy is an essential, ongoing cellular process that is highly regulated by nutrients, endocrine factors and signaling pathways. A great number of the genes and gene products that govern the autophagic response have been characterized and the major metabolic and signaling pathways that activate or suppress autophagy have been identified. This review describes the process of autophagy, its regulation and the possible mechanisms by which ethanol disrupts the process of autophagic degradation. The implications of autophagic suppression are discussed in relation to the pathogenesis of alcohol-induced liver injury.
基金Supported by Development funds from Section of Gastroenterology/Hepatology, Internal Medicine, University of Nebraska Medical Center
文摘Alcoholic patients have a high incidence of hepatitis C virus （HCV） infection. Alcohol consumption enhances the severity of the HCV disease course and worsens the outcome of chronic hepatitis C. The accumulation of virally infected cells in the liver is related to the HCV- induced inability of the immune system to recognize infected cells and to develop the immune responses. This review covers the effects of HCV proteins and ethanol on major histocompatibility complex （MHC） class Ⅰ- and class Ⅱ-restricted antigen presentation. Here, we discuss the liver which functions as an immune privilege organ; factors, which affect cleavage and loading of antigenic peptides onto MHC class I and class ~I in hepatocytes and dendritic cells, and the modulating effects of ethanol and HCV on antigen presentation by liver cells. Altered antigen presentation in the liver limits the ability ＇of the immune system to clear HCV and infected cells and contributes to disease progression. HCV by itself affects dendritic cell function, switching their cytokine profile to the suppressive phenotype of interleukin-10 （IL-10） and transforming growth factor beta （TGFβ） predominance, preventing cell maturation and allostimulation capacity. The synergistic action of ethanol with HCV results in the suppression of MHC class Ⅱ-restricted antigen presentation. In addition, ethanol metabolism and HCV proteins reduce proteasome function and interferon signaling, thereby suppressing the generation of peptides for MHC class I -restricted antigen presentation. Collectively, ethanol exposure further impairs antigen presentation in HCV-infected liver cells, which may provide a partial explanation for exacerbations and the poor outcome of HCV infection in alcoholics.
基金Supported by the National Institute on Alcohol Abuse and Alcoholism, grant number 5R21 AA015379-02
文摘The proteasome is a major protein-degrading enzyme, which catalyzes degradation of oxidized and aged proteins, signal transduction factors and cleaves peptides for antigen presentation. Proteasome exists in the equilibrium of 26S and 20S particles. Proteasome function is altered by ethanol metabolism, depending on oxidative stress levels： low oxidative stress induces proteasome activity, while high oxidative stress reduces it. The proposed mechanisms for modulation of proteasome activity are related to oxidative modification of proteasomal proteins with primary and secondary products derived from ethanol oxidation. Decreased proteolysis by the proteasome results in the accumulation of insoluble protein aggregates, which cannot be degraded by proteasome and which further inhibit proteasome function. Mallory bodies, a common signature of alcoholic liver diseases, are formed by liver cells, when proteasome is unable to remove cytokeratins. Proteasome inhibition by ethanol also promotes the accumulation of pro-apoptotic factors in mitochondria of ethanol-metabolizing liver cells that are normally degraded by proteasome. In addition, decreased proteasome function also induces accumulation of the negative regulators of cytokine signaling （I-~B and SOCS）, thereby blocking cytokine signal transduction. Finally, ethanol-elicited blockade of interferon type 2 and 2 signaling and decreased proteasome function impairs generation of peptides for MHC class Ⅰ-restricted antigen presentation.
基金Supported by The National Institute on Alcohol Abuse and Al-coholism and the US Department of Veterans Affairs
文摘Fibronectins are adhesive glycoproteins that can be found in tissue matrices and circulating in various fluids of the body. The variable composition of fibronectin molecules facilitates a diversity of interactions with cell surface receptors that suggest a role for these proteins beyond the structural considerations of the extracellular matrix. These interactions implicate fibronectin in the regulation of mechanisms that also determine cell behavior and activity. The two major forms, plasma fibronectin (pFn) and cellular fibronectin (cFn), exist as balanced amounts under normal physiological conditions. However, during injury and/or disease, tissue and circulating levels of cFn become disproportionately elevated. The accumulating cFn, in addition to being a consequence of prolonged tissue damage, may in factstimulate cellular events that promote further damage. In this review, we summarize what is known regarding such interactions between fibronectin and cells that may influence the biological response to injury. We elaborate on the effects of cFn in the liver, specifically under a condition of chronic alcohol-induced injury. Studies have revealed that chronic alcohol consumption stimulates excess production of cFn by sinusoidal endothelial cells and hepatic stellate cells while impairing its clearance by other cell types resulting in the build up of this glycoprotein throughout the liver and its consequent increased availability to influence cellular activity that could promote the development of alcoholic liver disease. We describe recent findings by our laboratory that support a plausible role for cFn in the promotion of liver injury under a condition of chronic alcohol abuse and the implications of cFn stimulation on the pathogenesis of alcoholic liver disease. These findings suggest an effect of cFn in regulating cell behavior in the alcohol-injured liver that is worth further characterizing not only to gain a more comprehensive understanding of the role this reactive glycoprotein plays in the progression of injury but also for the insight further studies could provide towards the development of novel therapies for alcoholic liver disease.
基金Supported by The National Institute on Alcohol Abuse and Alcoholismthe Department of Veterans Affairs
文摘The asialoglycoprotein （ASGP） receptor is a wellcharacterized hepatic receptor that is recycled via the common cellular process of receptor-mediated endocytosis （RME）. The RME process plays an integral part in the proper trafficking and routing of receptors and ligands in the healthy cell. Thus, the missorting or altered transport of proteins during RME is thought to play a role in several diseases associated with hepatocyte and liver dysfunction. Previously, we examined in detail alterations that occur in hepatocellular RME and associated receptor functions as a result of one particular liver injury, alcoholic liver disease （ALD）. The studies revealed profound ethanol- mediated impairments to the ASGP receptor and the RME process, indicating the importance of this receptor and the maintenance of proper endocytic events in normal tissue. To further clarify these observations, studies were performed utilizing knockout mice （lacking a functional ASGP receptor） to which were administered several liver toxicants. In addition to alcohol, we examined the effects following administration of anti- Fas （CD95） antibody, carbon tetrachloride （CCh） and lipopolysaccharide （LPS）/galactosamine. The results of these studies demonstrated that the knockout mice sustained enhanced liver injury in response to all of the treatments, as shown by increased indices of liver damage, such as enhancement of serum enzyme levels, histopathological scores, as well as hepatocellular death. Overall, the work completed to date suggests a possible link between hepatic receptors and liver injury. In particular, adequate function and content of the ASGP receptor may provide protection against various toxinmediated liver diseases.
基金Supported by the National Institute on Alcohol Abuse and Alcoholism and the US Department of Veterans Affairs
文摘AIM:To examine the consequences of cellular f ibronectin(cFn)accumulation during alcohol-induced injury,and inv estigate whether increased cFn could have an effect on hepatocytes(HCs)by producing factors that could cont ribute to alcohol-induced liver injury.METHODS:HCs were isolated from rats fed a control or ethanol liquid diet for four to six weeks.Exogenous c Fn(up to 7.5 μg/mL)was added to cells cultured for 20 h,and viability(lactate dehydrogenase),apoptosis(caspase activity)and se cretion of proinflammat-ory cytokines(tumor ne c rosis fac tor alpha,TNF-α and interleukin 6,IL-6),mat rix metalloproteinases(MMPs)and their inhibitors(tissue inhibitors of metall-oproteinases,TIMPs)was det ermined.Degrad ation of iodinated cFn was det ermined over a 3 h time period in the preparations.RESULTS:cFn degradation is impaired in HCs isolated from ethanol-fed animals,leading to its accumulation in the matrix.Addition of exogenous cFn did not affect viability of HCs from control or ethanolfed animals,and apoptosis was affected only at the higher concentration.Sec retion of MMPs,TIMPs,TNF-α and IL-6,however,was increased by exogenously added cFn,with HCs from ethanolfed animals showing increased susceptibility compared to the controls.CONCLUSION:These results suggest that the elevated amounts of cFn observed in alcoholic liver injury can stimulate hepatocytes to produce factors which promote further tissue damage.
文摘An annual topic highlight: Alcohol and Liver, 2011, covers the important and new aspects of pathogenesis of alcoholic liver diseases (ALD). It includes broad topics ranging from the exacerbation of ALD by infectious (viral) agents (hepatitis C virus and human immunodeficiency virus) to the influence of alcohol on liver fibrogenesis, lipid rafts, autophagy and other aspects. This issue is recommended for both basic scientists and clinicians who are involved in alcoholic liver research.
文摘Liver is known as an organ that is primarily affected by alcohol. Alcoholic liver disease (ALD) is the cause of an increased morbidity and mortality worldwide. Progression of ALD is driven by "second hits". These second hits include the complex of nutritional, pharmacological, genetic and viral factors, which aggravate liver pathology. However, in addition to liver failure, ethanol causes damage to other organs and systems. These extrahepatic manifestations are regulated via the similar hepatitis mechanisms. In the Topic Highlight series, we provide an update of current knowledge in the f ield of ALD.
基金Supported by The National Institute on Alcohol Abuse and Alcoholism and by the Department of Veterans Affairs
文摘AIM： To investigate the role of reactive oxygen species （ROS） in ethanol-mediated cell death of polarized hepatic （WlF-B） cells.METHODS： In this work, WIF-B cultures were treated with pyrazole （inducer of cytochrome P4502E1, CYP2E1） and/or L-buthionine sulfoximine （BSO）, a known inhibitor of hepatic glutathione （GSH）, followed by evaluation of ROS production, antioxidant levels, and measures of cell injury （apoptosis and necrosis）.RESULTS： The results revealed that ethanol treatment alone caused a significant two-fold increase in the activation of caspase-3 as well as a similar doubling in ROS. When the activity of the CYP2E1 was increased by pyrazole pretreatment, an additional two-fold elevation in ROS was detected. However, the CYP2EIrelated ROS elevation was not accompanied with a correlative increase in apoptotic cell injury, but rather was found to be associated with an increase in necrotic cell death. Interestingly, when the thiol status of the cells was manipulated using BSO, the ethanol-induced activation of caspase-3 was abrogated. Additionally, ethanol-treated cells displayed enhanced susceptibility to Fas-mediated apoptosis that was blocked by GSH depletion as a result of diminished caspase-8 activity.CONCLUSION： Apoptotic cell death induced as a consequence of ethanol metabolism is not completely dependent upon ROS status but is dependent on sustained GSH levels,
基金Supported by the National Institute on Alcohol Abuse and Alcoholism and the Department of Veterans Affairs
文摘Chronic ethanol consumption is associated with serious and potentially fatal alcohol-related liver injuries such as hepatomegaly, alcoholic hepatitis and cirrhosis. Moreover, it has been documented that the clinical progression of alcohol-induced liver damage may be associated with an increase in hepatocellular death that involves apoptotic mechanisms. Although much information has been learned about the clinical manifestations associated with alcohol-related diseases, the search continues for a better understanding of the molecular and/or cellular mechanisms by which ethanol exerts its deleterious effects such as the induction of pro-apoptotic mechanisms and related cell damaging events. As part of the effort to enhance our understanding of those particular cellular pathways and mechanisms associated with ethanol toxicity, researchers over the years have utilized a variety of model systems. Recently, work has come forth demonstrating the utility of a hybrid cell line (WIF-B) as a cell culture model system for the study of alcohol-associated alterations in hepatocellular mechanisms. Success with such emerging model systems could aid in the development of potential therapeutic treatments for the prevention of alcohol- induced apoptotic cell death that may ultimately serve as a significant target in delaying the onset and/or progression of clinical symptoms of alcohol-mediated liver disease. This review article summarizes the current understanding of ethanol-mediated modifications in cell survival and thus the promotion of pro-apoptotic events with emphasis on analyses made in various experimental model systems, particularly the more recently characterized WIF-B cell system.
