Mitochondrial reactive oxygen species as a mystery voice in hepatitis C

There are several lines of evidence suggesting that oxidative stress is present in hepatitis C to a greater degree than in other inflammatory liver diseases and is closely related to disease progression. The main production site of reactive oxygen species (ROS) is assumed to be mitochondria, which concept is supported by evidence that hepatitis C virus (HCV) core protein is directly associated with them. The detoxification of ROS also is an important function of the cellular redox homeostasis system. These results draw our attention to how HCV‐induced mitochondrial ROS production is beyond redox regulation and affects the disease progression and development of hepatocellular carcinoma (HCC) in chronic hepatitis C. On the other hand, HCV‐related chronic liver diseases are characterized by metabolic alterations such as insulin resistance, hepatic steatosis and/or iron accumulation in the liver. These metabolic disorders also are relevant to the development of HCC in HCV‐related chronic liver diseases. Here, we review the mechanisms by which HCV increases mitochondrial ROS production and offer new insights as to how mitochondrial ROS are linked to metabolic disorders such as insulin resistance, hepatic steatosis and hepatic iron accumulation that are observed in HCV‐related chronic liver diseases.     

胰岛素抵抗与代谢综合征

胰岛素对糖脂代谢、血压调控、血管收缩反应都有影响,胰岛素抵抗和/或代偿性高胰岛素血症可导致糖耐量异常、血脂异常、高血压、血管功能失调。随着胰岛素抵抗的出现,一些心血管危险因子往往聚集在一起形成代谢综合征,由于此综合征具有预测心血管疾病的内在价值,因此最近提出将代谢综合征提升为“疾病”。这些心血管危险因子的病理生理改变与胰岛素抵抗和代偿性高胰岛素血症密切相关,现对此进行综述。     

Nonalcoholic fatty liver disease,metabolic risk factors,and hepatocellular carcinoma: An open question

Non-alcoholic liver disease(NAFLD) defines liver abnormalities ranging from simple steatosis to nonalcoholic steatohepatitis with or without cirrhosis development, occurring in the absence of significant alcohol consumption, use of teratogenic medication, or hereditary disorders. The association between NAFLD and metabolic syndrome is well documented and widely recognized. Obesity, type 2 diabetes mellitus(T2DM), and dyslipidemia are the most common metabolic risk factors associated with NAFLD. Among the components of metabolic syndrome, current evidence strongly indicates obesity and diabetes as hepatocellular carcinoma(HCC) risk factors. There is also growing evidence that suggests an increased risk of HCC in NAFLD patients, even surpassing other etiologies in some high-income countries. Epidemiologic data demonstrate a parallel rise in prevalence of obesity, diabetes, NAFLD, and HCC. As obesity and its related diseases have steadily afflicted larger populations, HCC incidence is expected to increase in the future. Pathophysiologic mechanisms that underlie NAFLD development and subsequent progression to nonalcoholic steatohepatitis and cirrhosis(insulin resistance and hyperinsulinemia, oxidative stress, hepatic stellate cell activation, cytokine/adipocytokine signaling pathways, and genetic and environmental factors) appear to play a significant role in the development of NAFLD-related HCC. However, a comprehensive view of molecular mechanisms linking obesity, T2 DM, and NAFLD-related HCC, as well as the exact sequence of molecular events, is still not understood in its entirety. Good-quality data are still necessary, and efforts should continue towards better understanding the underlying carcinogenic mechanisms of NAFLD-related HCC. In this paper, we aimed to centralize the most important links supporting these relationships, focusing on obesity, T2 DM, and NAFLD-related HCC, as well as point out the major gaps in knowledge regarding the underlying molecular mechanisms behind them.     

Obesity-associated mechanisms of hepatocarcinogenesis

Obesity has been recognized as a key component of the metabolic syndrome, a cluster of risk factors associated with diabetes and cardiovascular morbidity. In addition, obesity has been linked to higher frequency of cancers in a variety of tissues including the liver. Liver cancer most often occurs as hepatocellular carcinoma (HCC) complicating cirrhosis due to chronic viral infection or toxic injury and remains the third leading cause of cancer death in the world. However, HCC is increasingly diagnosed among individuals with obesity and related disorders. As these metabolic conditions have become globally prevalent, they coexist with well-established risk factors of HCC and create a unique challenge for the liver as a chronically diseased organ. Obesity-associated HCC has recently been attributed to molecular mechanisms such as chronic inflammation due to adipose tissue remodeling and pro-inflammatory adipokine secretion, ectopic lipid accumulation and lipotoxicity, altered gut microbiota, and disrupted senescence in stellate cells, as well as insulin resistance leading to increased levels of insulin and insulin-like growth factors. These mechanisms synergize with those occurring in chronic liver disease resulting from other etiologies and accelerate the development of HCC before or after the onset of cirrhosis. Increasingly common interactions between oncogenic pathways linked to obesity and chronic liver disease may explain why HCC is one of the few malignancies with rising incidence in developed countries. Better understanding of this complex process will improve our strategies of cancer prevention, prediction, and surveillance.     

HCC and NASH: How strong is the clinical demonstration?

Obesity and the metabolic syndrome (MS) are growing epidemics associated with an increased risk for many types of cancer. In the liver, in?ammatory and angiogenic changes due to insulin resistance and fatty liver disease are associated with an increased incidence of liver cancer. Regardless of underlying liver disease, cirrhosis remains the most important risk factor for hepatocellular carcinoma (HCC) although rare cases of HCC arising without cirrhosis raise the possibility of a direct carcinogenesis secondary to nonalcoholic fatty liver disease (NAFLD). Moreover, MS and its different features may also increase the risk of HCC in the setting of chronic liver diseases of other causes such as viral hepatitis or alcohol abuse. Taking into account all these data, it is necessary to better determine the risk of developing HCC in patients with MS to improve the screening guidelines and develop prophylactic treatments in this setting.     

Impact of cancers and cardiovascular diseases in chronic obstructive pulmonary disease

PURPOSE OF REVIEW: Cardiovascular disease and cancer are the two leading causes of morbidity and mortality in patients with chronic obstructive pulmonary disease. The epidemiological and mechanistic evidence linking these disorders, however, is uncertain. RECENT FINDINGS: In patients with mild chronic obstructive pulmonary disease, cardiovascular disease accounts for nearly 50% of all hospitalizations and over 20% of all deaths, whereas lung cancer accounts for about a third of all mortality. Collectively, cancer is responsible for over 50% of all deaths in mild chronic obstructive pulmonary disease. In general, chronic obstructive pulmonary disease increases the risk of cardiovascular disease and lung cancer by two-fold, with increasing risk as the disease progresses. The mechanisms linking these disorders have not been well worked out. Shared genetic risk factors, and perturbations in the inflammatory, oxidative and neurohumoral responses, are implicated. Epidemiological studies suggest that anti-inflammatory drugs may reduce the risk of cardiovascular disease and lung cancer but have not been confirmed. SUMMARY: Cardiovascular diseases and lung cancer are major sources of morbidity and mortality in chronic obstructive pulmonary disease. Patients should be assessed carefully for additional risk factors and be treated aggressively with interventions to mitigate the risk of cardiovascular disease and lung cancer.     

Prevention of hepatocellular carcinoma in the Asia–Pacific region: Consensus statements

Among approximately 650 000 people who die from hepatocellular carcinoma (HCC) each year, at least two‐thirds live in Asia. Efforts to improve early diagnosis and treatment have not yet impacted mortality. An Asia–Pacific Working Party convened in Hong Kong in June 2008 to consider ways to prevent HCC in this region. Separate reviews have summarized epidemiology of HCC, preventive approaches related to hepatitis B virus (HBV), hepatitis C virus (HCV) and non‐viral liver diseases, and the role of surveillance to detect HCC at a curative stage. We now present Consensus Statements from these deliberations and reviews. As chronic hepatitis B is the most common cause of HCC in Asia, effective hepatitis B vaccination programs are the most important strategy to reduce HCC incidence. Prevention of HCV by screening blood donors, universal precautions against blood contamination in health‐care settings and reducing HCV transmission from injection drug use are also vital. There is strong evidence that effective antiviral therapy to control HBV infection or eradicate HCV substantially reduces (but does not abolish) HCC risk. With hemochromatosis, family screening, early diagnosis and correcting iron overload to prevent liver fibrosis prevents HCC. There is currently insufficient evidence to give firm recommendations on alcohol, obesity/metabolic risk factors and other liver diseases. HCC surveillance for high‐risk groups is recommended in individual cases but cost‐effectiveness is not as high as infant hepatitis B vaccination and screening blood for HCV. Widespread application of HCC surveillance in Asia–Pacific countries depends on economic factors and health‐care priorities.     

Evaluation of metabolic factors on the prognosis of patients undergoing resection of hepatocellular carcinoma

Background and Aim: The metabolic factors including obesity, diabetes, and hypertension have been implicated as risk factors of hepatocellular carcinoma (HCC) in patients with chronic hepatitis. The effects of metabolic factors were investigated on the prognosis of patients undergoing resection of HCC. Methods: A total of 469 HCC patients were classified into three groups; hepatitis B virus (HBV)‐, hepatitis C virus (HCV)‐, and non‐HBV/HCV (NBC)‐related HCC. Further, the patients with HCV‐related HCC were sub‐classified into three groups; the patients who did not have documented hypertension, hypertensive patients who received angiotensin II‐blocking agents (ABA), and hypertensive patients who received no ABA. Results: There were no significant difference of survival in the HBV‐HCC and NBC‐HCC patients with or without obesity, diabetes, and hypertension. In the patients with HCV‐related HCC, however, hypertensive patients were significantly worse on both disease‐free and overall survivals than non‐hypertensive patients. Among the HCV‐HCC patients with chronic hepatitis, hypertensive patients with ABA had significantly better preoperative liver function, and hypertensive patients without ABA were significantly worse on both disease‐free and overall survivals than those of hypertensive patients with ABA and non‐hypertensive patients. Conclusions: Results suggest that hypertension is a risk factor for a poor prognosis after resection of HCV‐related HCC. Angiotensin II blockade may improve the prognosis of hypertensive patients with early hepatic fibrosis after resection in HCV‐related HCC.     

The role of the gut microbiome in the development and progression of liver cirrhosis and hepatocellular carcinoma

Liver cirrhosis and hepatocellular carcinoma (HCC) represent the endstage of most chronic liver diseases and are a major global health burden. It has been consistently shown that both liver cirrhosis and HCC are triggered by inflammatory processes, but the molecular mechanisms linking chronic hepatitis with cirrhosis and HCC are only poorly understood. Recent studies suggested that the intestinal microflora as a main source of portal-vein LPS might play a critical role in this process. Here we summarize the available literature on the role of the gut microbiome in hepatofibrogenesis and -carcinogenesis. Such knowledge might help to develop novel, innovative strategies for the prevention and therapy of liver disease.     

Chemoprevention of obesity-related liver carcinogenesis by using pharmaceutical and nutraceutical agents

Obesity and its related metabolic disorders are serious health problems worldwide, and lead to various health-related complications, including cancer. Among human cancers, hepatocellular carcinoma (HCC) is one of the most common malignancies affected by obesity. Therefore, obesity and its related disorders might be a key target for the prevention of HCC. Recently, new research indicates that the molecular abnormalities associated with obesity, including insulin resistance/hyperinsulinemia, chronic inflammation, adipokine imbalance, and oxidative stress, are possible molecular mechanisms underlying the pathogenesis of obesity-related hepatocarcinogenesis. Green tea catechins and branched-chain amino acids, both of which are classified as nutraceutical agents, have been reported to prevent obesity-related HCC development by improving metabolic abnormalities. The administration of acyclic retinoid, a pharmaceutical agent, reduced the incidence of HCC in obese and diabetic mice, and was also associated with improvements in insulin resistance and chronic inflammation. In this article, we review the detailed molecular mechanisms that link obesity to the development of HCC in obese individuals. We also summarize recent evidence from experimental and clinical studies using either nutraceutical or pharmaceutical agents, and suggest that nutraceutical and pharmaceutical approaches targeting metabolic abnormalities might be a promising strategy to prevent the development of obesity-related HCC.     

Do hepatitis B virus and hepatitis C virus co‐infections increase hepatocellular carcinoma occurrence through synergistically modulating lipogenic gene expression?

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections cause a wide range of liver diseases including hepatocellular carcinoma (HCC). Because of the similar modes of transmission, HBV HCV co-infections are found in approximately 7-20 million people globally. Compared with HBV or HCV mono-infections, co-infections are associated with more severe liver diseases and higher risk of HCC. Abnormal lipid biosynthesis and metabolism has been increasingly recognized as a cause for cancer. While HBV infection does not seem to significantly increase the risk of developing hepatic steatosis, steatosis is a prominent feature of chronic hepatitis C (CHC). In addition, steatosis in HBV or HCV mono-infections is a significant and independent risk factor for HCC. However, whether and how HBV HCV co-infections synergistically increase the risk of HCC development through modulating lipid metabolism is not well understood. Possible mechanisms by which steatosis causes HCC include: activation of sterol regulatory element-binding protein-mediated lipogenesis through the PI3K-Akt pathway, abnormal activation of peroxisome proliferator-activated receptors and endoplasmic reticulum stress. Here, we review the potential mechanisms by which HBV HCV co-infections may increase HCC risk through modulation of lipogenic gene expression. We begin with reviewing the impact of HBV and HCV on host lipogenic gene expression and carcinogenesis. We then discuss the potential mechanisms by which HBV and HCV can increase carcinogenesis through synergistically activating lipid biosynthesis and metabolism. We end by sharing our thoughts on future research directions in this emerging paradigm with an ultimate goal of developing effective therapeutics.     

Uric acid in metabolic syndrome: From an innocent bystander to a central player

Uric acid, once viewed as an inert metabolic end-product of purine metabolism, has been recently incriminated in a number of chronic disease states, including hypertension, metabolic syndrome, diabetes, non-alcoholic fatty liver disease, and chronic kidney disease. Several experimental and clinical studies support a role for uric acid as a contributory causal factor in these conditions. Here we discuss some of the major mechanisms linking uric acid to metabolic and cardiovascular diseases. At this time the key to understanding the importance of uric acid in these diseases will be the conduct of large clinical trials in which the effect of lowering uric acid on hard clinical outcomes is assessed. Elevated uric acid may turn out to be one of the more important remediable risk factors for metabolic and cardiovascular diseases.     

Insulin resistance: a risk marker for disease and disability in the older person

Clinical metabolic studies have demonstrated that insulin action declines progressively with age in humans. In addition to its close association with Type 2 diabetes, which reduces life expectancy in older people, age‐related insulin resistance is implicated in pathogenesis of several highly prevalent disorders for which ageing is a major risk factor. These include atherosclerotic cardiovascular disease, dementia, frailty and cancer. Accordingly, insulin resistance may be viewed as biomarker of age‐related ill health and reduced lifespan. The rapidly rising number of older people, coupled with a high prevalence of insulin resistance resulting from obesity and sedentary lifestyles, presents unprecedented public health and societal challenges. Studies of centenarians have shown that preserved whole‐body sensitivity to insulin is associated with longevity. The mechanisms through which insulin action is associated with age‐related diseases remain unclear. Changes in body composition, i.e. sarcopenia and excess adiposity, may be more potent than age per se. Moreover, the impact of insulin resistance has been difficult to disentangle from the clustering of vascular risk factors that co‐segregate with the insulin resistance–hyperinsulinaemia complex. Potentially modifiable mediators of age‐related changes in insulin sensitivity include alterations in adipocytokines, impaired skeletal myocyte mitochondrial function and brown fat activity. The hypothesis that improving or maintaining insulin sensitivity preserves health and extends lifespan merits further evaluation. Practical non‐pharmacological interventions directed against age‐related insulin resistance remain underdeveloped. Novel metabolically active pharmacological agents with theoretical implications for some age‐related disorders are entering clinical trials. However, recent adverse experiences with the thiazolidinediones suggest the need for a cautious approach to the use of insulin sensitizing drugs in older people. This could be particularly important in the absence of diabetes where the risk to benefit analysis may be less favourable.     

The role of the microbiota in sedentary lifestyle disorders and ageing: lessons from the animal kingdom

A paradox of so‐called developed countries is that, as the major historical causes of human mortality are eliminated or mitigated by medical progress, lifestyle‐related diseases have become major killers. Furthermore, as lifespan is extended by the combined effects of modern medicine, health span is struggling to keep apace because of the burden of noncommunicable diseases linked to diet and sedentary lifestyle. The gut microbiome is now recognized as a plastic environmental risk factor for many of these diseases, the microbiome being defined as the complex community of co‐evolved commensal microbes that breaks down components of a complex diet, modulates innate immunity, and produces signalling molecules and metabolites that can impact on diverse regulatory systems in mammals. Aspects of the so‐called ‘Western’ lifestyle linked to disease risk such as energy dense diet and antibiotic treatment are known to affect the composition and function of the microbiome. Here, we review the detailed mechanisms whereby the gut microbiome may modulate risk of diseases linked to sedentary lifestyle and ageing‐related health loss. We focus on the comparative value of natural animal models such as hibernation for studying metabolic regulation and the challenge of extrapolating from animal models to processes that occur in human ageing.     

Diabetes and cancer: two diseases with obesity as a common risk factor

There is a growing body of evidence to support a connection between diabetes (predominantly type 2), obesity and cancer. Multiple meta‐analyses of epidemiological data show that people with diabetes are at increased risk of developing many different types of cancers, along with an increased risk of cancer mortality. Several pathophysiological mechanisms for this relationship have been postulated, including insulin resistance and hyperinsulinaemia, enhanced inflammatory processes, dysregulation of sex hormone production and hyperglycaemia. In addition to these potential mechanisms, a number of common risk factors, including obesity, may be behind the association between diabetes and cancer. Indeed, obesity is associated with an increased risk of cancer and diabetes. Abdominal adiposity has been shown to play a role in creating a systemic pro‐inflammatory environment, which could result in the development of both diabetes and cancer. Here, we examine the relationship between diabetes, obesity and cancer, and investigate the potential underlying causes of increased cancer risk in individuals with diabetes. Current treatment recommendations for reducing the overall disease burden are also explored and possible areas for future research are considered.     

Hepatocellular carcinoma in the Asia pacific region

Primary liver cancer, particularly hepatocellular carcinoma (HCC) remains a significant disease worldwide. It is among the top three causes of cancer death in the Asia Pacific region because of the high prevalence of its main etiological agents, chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections. In this region, the incidence of HCC has been static over recent decades. Older age is a major risk factor; the incidence increasing sharply after age 40 years. There is a male predilection, with male to female ratio of 3:1, except in elderly Japanese with equal sex incidence or female predominance. In most Asia‐Pacific countries, chronic HBV infection accounts for 75–80% of cases; Japan, Singapore and Australia/New Zealand are exceptions because of higher prevalence of HCV infection. In spite of advances in surgery, liver transplantation and newer pharmaco/biological therapies, the survival rate has improved only slightly over recent decades, and this could be attributable to earlier diagnosis (‘lead‐time bias’). The majority of patients present with advanced diseases, hence reducing the chance of curative treatment. The importance of HCC may decrease in two to three decades when the prevalence of chronic HBV infection decreases as a result of the universal HBV vaccination programs implemented in late 1980s in most Asia‐Pacific countries, and because of reduced incidence of medical transmission of HCV. However, transmission of HCV by injection drug use, and rising prevalence of obesity and diabetes, both independent risk factors for HCC, may partly offset this decline.     

The metabolic syndrome: evolving evidence that thiazolidinediones provide rational therapy

The metabolic syndrome, also known as the dysmetabolic syndrome, syndrome X or the insulin resistance syndrome, refers to the clustering of cardiovascular disease risk factors that are present in many individuals who are at increased risk for both cardiovascular events and type 2 diabetes. Prediabetic subjects typically exhibit an atherogenic pattern of cardiovascular risks that is associated with hyperinsulinaemia. Thus, identification of components of the metabolic syndrome is important if patients are to be treated early enough to prevent cardiovascular events and other complications related to diabetes. Therapies targeted to specific components of the metabolic syndrome such as improving glycaemic control, managing dyslipidaemia and reducing the prothrombotic state should help to minimize cardiovascular risk, particularly if initiated early. Traditional pharmacologic agents used to manage the individual components of the metabolic syndrome do not typically impact the other components. The thiazolidinediones, a new class of agents that improve insulin resistance, have the ability, in addition to their glucose-lowering effects, to exert several powerful anti-atherogenic properties, including anti-inflammatory effects in the vascular endothelium, redistribution of visceral fat and reduction of insulin resistance, hyperinsulinaemia and hyperproinsulinaemia. This makes the thiazolidinediones ideal candidates for the early treatment of many components associated with the metabolic syndrome.     

Economic growth leads to increase of obesity and associated hepatocellular carcinoma in developing countries

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and the third leading cause of cancer related death worldwide. In recent years, the prevalence of HCC has increased in both developing and developed countries. Most HCC cases develop in the presence of advanced chronic liver disease related to viral hepatitis. In particular hepatitis B virus and hepatitis C virus infections are considered as major HCC risk factors worldwide. However, current studies provide strong evidence for increasing numbers of HCC in nonalcoholic fatty liver disease (NAFLD). NAFLD represents the hepatic manifestation of metabolic syndrome which is based on obesity and insulin resistance. Epidemiologic data clearly demonstrates that NAFLD and obesity-related disorders are significant risk factors for tumor development in general and HCC in particular. As a consequence of life style changes towards higher calorie intake and less exercise, obesity and metabolic syndrome are spreading all over the world. Due to this increase in obesity and metabolic syndrome NAFLD-related HCC will become a major health care problem in the future. In conclusion, better understanding of the impact of NAFLD and obesity in the development of HCC will improve our treatment strategies of HCC and allow preventive measures.     

Hepatocellular carcinoma in non-alcoholic fatty liver disease: an emerging menace

Hepatocellular carcinoma (HCC) is a common cancer worldwide that primarily develops in cirrhosis resulting from chronic infection by hepatitis B virus and hepatitis C virus, alcoholic injury, and to a lesser extent from genetically determined disorders such as hemochromatosis. HCC has recently been linked to non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of obesity and related metabolic disorders such as diabetes. This association is alarming due to the globally high prevalence of these conditions and may contribute to the rising incidence of HCC witnessed in many industrialized countries. There is also evidence that NAFLD acts synergistically with other risk factors of HCC such as chronic hepatitis C and alcoholic liver injury. Moreover, HCC may complicate non-cirrhotic NAFLD with mild or absent fibrosis, greatly expanding the population potentially at higher risk. Major systemic and liver-specific molecular mechanisms involved include insulin resistance and hyperinsulinemia, increased TNF signaling pathways, and alterations in cellular lipid metabolism. These provide new targets for prevention, early recognition, and effective treatment of HCC associated with NAFLD. Indeed, both metformin and PPAR gamma agonists have been associated with lower risk and improved prognosis of HCC. This review summarizes current evidence as it pertains to the epidemiology, pathogenesis, and prevention of NAFLD-associated HCC.     

Leptin as a link between the immune system and kidney‐related diseases: leading actor or just a coadjuvant?

Food intake and nutritional status modify the physiological responses of the immune system to illness and infection and regulate the development of chronic inflammatory processes, such as kidney disease. Adipose tissue secretes immune‐related proteins called adipokines that have pleiotropic effects on both the immune and neuroendocrine systems, linking metabolism and immune physiology. Leptin, an adipose tissue‐derived adipokine, displays a variety of immune and physiological functions, and participates in several immune responses. Here, we review the current literature on the role of leptin in kidney diseases, linking adipose tissue and the immune system with kidney‐related disorders. The modulation of this adipose hormone may have a major impact on the treatment of several immune‐ and metabolic‐related kidney diseases.