Insulin resistance and hepatitis C

Insulin resistance is the major feature of the metabolic syndrome and depends on insulin secretion and insulin sensitivity. In chronic hepatitis C, insulin resistance and type 2 diabetes mellitus are more often seen than in healthy controls or chronic hepatitis B patients. Hepatitis C virus （HCV） infection promotes insulin resistance, mainly by increased TNF production together with enhancement of suppressor of cytokine （SOC-3）; both events block PI3K and Akt phosphorylation. Two types of insulin resistance could be found in chronic hepatitis C patients＇. ＂viral＂ and ＂metabolic＂ insulin resistance. Insulin resistance in chronic hepatitis C is relevant because it promotes steatosis and fibrosis. The mechanisms by which insulin resistance promotes fibrosis progression include： （1） steatosis, （2） hyperleptinemia, （3） increased TNF production, （4） impaired expression of PPARy receptors. Lastly, insulin resistance has been found as a common denominator in patients difficult-to-treat like cirrhotics, overweight, HIV coinfected and Afro-American. Insulin resistance together with fibrosis and genotype has been found to be independently associated with impaired response rate to peginterferon plus ribavirin. Indeed, in genotype 1, the sustained response rate was twice （60%） in patients with HOMA ≤ 2 than patients with HOMA 〉 2. In experiments carried out on Huh-7 cells transfected by full length HCVRNA, interferon alpha blocks HCV replication. However, when insulin （at doses of 128 μU/mL, similar that seen in the hyperinsulinemic state） was added to interferon, the ability to block HCV replication disappeared, and the PKR synthesis was abolished. In summary, hepatitis C promotes insulin resistance and insulin resistance induces interferon resistance, steatosis and fibrosis progression.

Hepatobiliary manifestations in inflammatory bowel disease: The gut,the drugs and the liver

Abnormal liver biochemical tests are present in up to30%of patients with inflammatory bowel disease(IBD),and therefore become a diagnostic challenge.Liver and biliary tract diseases are common extraintestinal manifestations for both Crohn’s disease and ulcerative colitis(UC),and typically do not correlate with intestinal activity.Primary sclerosing cholangitis(PSC)is the most common hepatobiliary manifestation of IBD,and is more prevalent in UC.Approximately 5%of patients with UC develop PSC,with the prevalence reaching up to 90%.Cholangiocarcinoma and colon cancer risks are increased in these patients.Less common disorders include autoimmune hepatitis/PSC overlap syndrome,IgG4-associated cholangiopathy,primary biliary cirrhosis,hepatic amyloidosis,granulomatous hepatitis,cholelithiasis,portal vein thrombosis,liver abscess,and non-alcoholic fatty liver disease.Hepatitis B reactivation during immunosuppressive therapy is a major concern,with screening and vaccination being recommended in serologically negative cases for patients with IBD.Reactivation prophylaxis with entecavir or tenofovir for 6to 12 mo after the end of immunosuppressive therapy is mandatory in patients showing as hepatitis B surface antigen(HBsAg)positive,independently from viral load.HBsAg negative and anti-HBc positive patients,with or without anti-HBs,should be closely monitored,measuring alanine aminotransferase and hepatitis B virus DNA within 12 mo after the end of therapy,and should be treated if the viral load increases.On the other hand,immunosuppressive therapy does not seem to promote reactivation of hepatitis C,and hepatitis C antiviral treatment does not influence IBD natural history either.Most of the drugs used for IBD treatment may induce hepatotoxicity,although the incidence of serious adverse events is low.Abnormalities in liver biochemical tests associated with aminosalicylates are uncommon and are usually not clinically relevant.Methotrexaterelated hepatotoxicity has been described in 14%of patients with IBD,in a dose-dependent manner.Liver biopsy is not routinely recommended.Biologics-related hepatotoxicity is rare,but has been shown most frequently in patients treated with infliximab.Thiopurines have been associated with veno-occlusive disease,regenerative nodular hyperplasia,and liver peliosis.Routine liver biochemical tests are recommended,especially during the first month of treatment.All these conditions should be considered in IBD patients with clinical or biochemical features suggestive of hepatobiliary involvement.Diagnosis and management of these disorders usually involve hepatologists and gastroenterologists due to its complexity.

Low phase angle is associated with the development of hepatic encephalopathy in patients with cirrhosis

AIM Evaluate the association between phase angle and the development of hepatic encephalopathy in the longterm follow-up of cirrhotic patients.METHODS This was a prospective cohort study. Clinical, nutritional and biochemical evaluations were performed. MannWhitney's U and χ2 tests were used as appropriate. Kaplan-Meier curves and Cox proportional Hazards analysis were used to evaluate the prediction and incidence of hepatic encephalopathy.RESULTS Two hundred and twenty were included; the most frequent etiology of cirrhosis was hepatitis C infection, 52% of the patients developed hepatic encephalopathy(18.6% covert and 33.3% overt); the main precipitating factors were infections and variceal bleeding. KaplanMeier curves showed a higher proportion of HE in the group with low phase angle(39%) compared to the normal phase angle group(13%)(P = 0.012). Furthermore, creatinine and phase angle remained independently associated to hepatic encephalopathy in the Cox regression multivariate analysis [hazard ratio = 1.80(1.07-3.03)]. CONCLUSION In our cohort of patients low phase angle was associated with an increased incidence of hepatic encephalopathy. Phase angle is a useful nutritional marker that evaluates cachexia and could be used as a part of the integral assessment in patients with cirrhosis.

Cardiovascular assessment in liver transplant for nonalcoholic steatohepatitis patients:What we do,what we should do

Non-alcoholic fatty liver disease(NAFLD) is increasing considerably due to the current lifestyle,which means that it is becoming one of the main indications for liver transplantation.On the other hand,there is a strong association between NAFLD and cardiovascular disease.This has been evidenced in many studies revealing a higher presence of carotid plaques or carotid intima-media thickness,leading to cardiovascular events and,ultimately,mortality.According to the liver transplant guidelines,screening for heart disease in transplant candidates should be performed by electrocardiogram and transthoracic echocardiography while a stress echocardiogram should be reserved for those with more than two cardiovascular risk factors or greater than 50 years old.However,there are no specific recommendations in NAFLD patients requiring a liver transplantation,despite its well-known cardiovascular risk association.Many studies have shown that these patients probably require a more exhaustive assessment and a global approach including other specialists such as cardiologists or nutritionists.Also,the incidence of cardiovascular disease is also increased in NAFLD patients in the post-transplantation period in comparison with other etiologies,because of the pre-existent risk factors together with the immunosuppressive therapy.Therefore,an early intervention on the lifestyle and the individualized selection of the immunosuppressive regimen could lead to a modification of the cardiovascular risk factors in NAFLD patients requiring a liver transplantation.

Epigenetic mechanisms in non-alcoholic fatty liver disease:An emerging field

Non-alcoholic fatty liver disease(NAFLD) is an emerging health concern in both developed and non-developed world, encompassing from simple steatosis to nonalcoholic steatohepatitis(NASH), cirrhosis and liver cancer. Incidence and prevalence of this disease are increasing due to the socioeconomic transition and change to harmful diet. Currently, gold standard method in NAFLD diagnosis is liver biopsy, despite complications and lack of accuracy due to sampling error. Further, pathogenesis of NAFLD is not fully understood, but is well-known that obesity, diabetes and metabolic derangements played a major role in disease development and progression. Besides, gut microbioma and host genetic and epigenetic background could explain considerable interindividual variability. Knowledge that epigenetics, heritable events not caused by changes in DNA sequence, contribute to development of diseases has been a revolution in the last few years. Recently, evidences are accumulating revealing the important role of epigenetics in NAFLD pathogenesis and in NASH genesis. Histone modifications, changes in DNA methylation and aberrant profiles or micro RNAs could boost development of NAFLD and transition into clinical relevant status. PNPLA3 genotype GG has been associated with a more progressive disease and epigenetics could modulate this effect. The impact of epigenetic on NAFLD progression could deserve further applications on therapeutic targets together with future non-invasive methods useful for the diagnosis and staging of NAFLD.

Steatosis and insulin resistance in hepatitis C: A way out for the virus?

The hepatitis C virus (HCV) induces lipid accumulation in vitro and in vivo. The pathogenesis of steatosis is due to both viral and host factors. Viral steatosis is mostly reported in patients with genotype 3a, whereas meta-bolic steatosis is often associated with genotype 1 and metabolic syndrome. Several molecular mechanisms responsible for steatosis have been associated with the HCV core protein, which is able to induce gene expres-sion and activity of sterol regulatory element binding protein 1 (SREBP1) and peroxisome proliferator-activat-ed receptor γ (PPARγ), increasing the transcription of genes involved in hepatic fatty acid synthesis. Steatosis has been also implicated in viral replication. In infected cells, HCV core protein is targeted to lipid droplets which serve as intracellular storage organelles. These studies have shown that lipid droplets are essential for virus assembly. Thus, HCV promotes steatosis as an eff icient mechanism for stable viral replication. Chronic HCV in-fection can also induce insulin resistance. In patients with HCV, insulin resistance is more strongly associated with viral load than visceral obesity. HCV seems to lead to insulin resistance through interference of intracellular insulin signalling by HCV proteins, mainly, the serine phosphorylation of insulin receptor-1 (IRS-1) and im-pairment of the downstream Akt signalling pathway. The HCV core protein interferes with in vitro insulin signal-ling by genotype-specif ic mechanisms, where the role of suppressor of cytokine signal 7 (SOCS-7) in genotype 3aand mammalian target of rapamycin (mTOR) in geno-type 1 in IRS-1 downregulation play key roles. Steatosis and insulin resistance have been associated with f ibrosis progression and a reduced rate of sustained response to peginterferon plus ribavirin.

Wilson's disease:Revisiting an old friend

Wilson's disease(WD)is a rare condition caused by copper accumulation primarily in the liver and secondly in other organs,such as the central nervous system.It is a hereditary autosomal recessive disease caused by a deficiency in the ATP7B transporter.This protein facilitates the incorporation of copper into ceruloplasmin.More than 800 mutations associated with WD have been described.The onset of the disease frequently includes manifestations related to the liver(as chronic liver disease or acute liver failure)and neurological symptoms,although it can sometimes be asymptomatic.Despite it being more frequent in young people,WD has been described in all life stages.Due to its fatal prognosis,WD should be suspected in all patients with unexplained biochemical liver abnormalities or neurological or psychiatric symptoms.The diagnosis is established with a combination of clinical signs and tests,including the measurement of ceruloplasmin,urinary copper excretion,copper quantification in liver biopsy,or genetic assessment.The pharmacological therapies include chelating drugs,such as D-penicillamine or trientine,and zinc salts,which are able to change the natural history of the disease,increasing the survival of these patients.In some cases of end-stage liver disease or acute liver failure,liver transplantation must be an option to increase survival.In this narrative review,we offer an overview of WD,focusing on the importance of clinical suspicion,the correct diagnosis,and treatment.

Modulation of host lipid metabolism by hepatitis C virus: role of new therapies

It is well established that hepatitis C virus(HCV) infection and replication relies on host lipid metabolism. HCV proteins interact and associate with lipid droplets to facilitate virion assembly and production. Besides,circulating infective particles are associated with verylow-density lipoprotein. On the other hand,higher serum lipid levels have been associated with sustained viral response to pegylated interferon and ribavirin therapy in chronic HCV infection,suggesting a relevant role in viral clearance for host proteins. Host and viral genetic factors play an essential role in chronic infection. Lipid metabolism is hijacked by viral infection and could determine the success of viral replication. Recently development of direct acting antiviral agents has shown a very high efficacy(> 90%) in sustained viral response rates even for cirrhotic patients and most of the viral genotypes. HCV RNA clearance induced by Sofosbuvir has been associated with an increased concentration and size of the low-density lipoprotein particles. In this review,host genetic factors,viral factors and the interaction between them will be depicted to clarify the major issues involved in viral infection and lipid metabolism.

Assessing cardiovascular risk in hepatitis C: An unmet need

Chronic hepatitis C virus(HCV) is associated with significant morbidity and mortality, as a result of the progression towards cirrhosis and hepatocellular carcinoma. Additionally, HCV seems to be an independent risk factor for cardiovascular diseases(CVD) due to its association with insulin resistance, diabetes and steatosis. HCV infection represents an initial step in the chronic inflammatory cascade, showing a direct rolein altering glucose metabolism. After achieving sustained virological response, the incidence of insulin resistance and diabetes dramatically decrease. HCV core protein plays an essential role in promoting insulin resistance and oxidative stress. On the other hand, atherosclerosis is a common disease in which the artery wall thickens due to accumulation of fatty deposits. The main step in the formation of atherosclerotic plaques is the oxidation of low density lipoprotein particles, together with the increased production of proinflammatory markers [tumor necrosis factor-α, interleukin(IL)-6, IL-18 or C-reactive protein]. The advent of new direct acting antiviral therapy has dramatically increased the sustained virological response rates of hepatitis C infection. In this scenario, the cardiovascular risk has emerged and represents a major concern after the eradication of the virus. Consequently, the number of studies evaluating this association is growing. Data derived from these studies have demonstrated the strong link between HCV infection and the atherogenic process, showing a higher risk of coronary heart disease, carotid atherosclerosis, peripheral artery disease and, ultimately, CVD-related mortality.

Combination of squamous cell carcinoma antigen immunocomplex and alpha-fetoprotein in mid-and long-term prediction of hepatocellular carcinoma among cirrhotic patients

BACKGROUND The combination of alpha-fetoprotein(AFP)and squamous cell carcinoma antigen immunocomplex(SCCA-IgM)have been proposed for its use in the screening of hepatocellular carcinoma(HCC).Current screening programs for all cirrhotic patients are controversial and a personalized screening is an unmet need in the precision medicine era.AIM To determine the role of the combination of SCCA-IgM and AFP in predicting mid-and long-term appearance of HCC.METHODS Two-hundred and three cirrhotic patients(Child A 74.9%,B 21.2%,C 3.9%)were followed-up prospectively every six months to screen HCC by ultrasound and AFP according to European Association for the Study of the Liver guidelines.The estimation cohort was recruited in Italy(30.5%;62/203)and validation cohort from Spain(69.5%;141/203).Patients underwent to evaluate SCCA-IgM by enzyme-linked immunosorbent assay(Hepa-IC,Xeptagen,Italy)and AFP levels at baseline.Patients were followed-up for 60 mo,being censored at the time of the appearance of HCC.RESULTS There were 10.8%and 23.1%of HCC development at two-and five-years followup.Patients with HCC showed higher levels of SCCA-IgM than those without it(425.72±568.33 AU/mL vs 195.93±188.40 AU/mL,P=0.009)during the fiveyear follow-up.In multivariate analysis,after adjusting by age,sex,aspartate transaminase and Child-Pugh,the following factors were independently associated with HCC:SCCA-IgM[Hazard ratio(HR)=1.001,95%CI:1.000-1.002;P=0.003],AFP(HR=1.028,95%CI:1.009-1.046;P=0.003)and creatinine(HR=1.56495%CI:1.151-2.124;P=0.004).The log-rank test of the combination resulted in 7.488(P=0.024)in estimation cohort and 11.061(P=0.004)in the validation cohort,and a 100%of correctly classified rate identifying a low-risk group in both cohorts in the two-year follow-up.CONCLUSION We have constructed a predictive model based on the combination of SCCA-IgM and AFP that provides a new HCC screening method,which could be followed by tailored HCC surveillance for individual patients,especially for those cirrhotic patients belonging to the subgroup identified as low-risk of HCC development.

Hyperammonemia induced oxidative stress in cirrhotic rats without promoting differential protein expression in the brain cortex: A 2D-DIGE analysis

Oxidative stress induced by a high ammonia concentration could modify protein expression in the brain. This study was undertaken in order to investigate the impact of hyperammonemia, caused by thioacetmide (TAA) in rats, on brain cortex protein expression using 2D-DIGE, and analyzing its role in the pathogenesis of HE. Hyperammonemia was induced with TAA. Ammonia and active oxidants were measured by L-glutamate dehydrogenase and dichlorodihydrofluorescein diacetate methods, respectively. Lipid peroxidation and protein oxidation biomarkers were also studied. Differential protein expression in the cortex of TAA- and control-rats was studied by 2D-DIGE. Image analysis was performed using the DeCyder? Software. Ammonia concentration in plasma and brain tissue was higher in TAA-rats compared to control-rats, 3.12 and 2.43 fold higher, respectively. Active oxidants production in TAA-rats was increased by 2.7 fold compared to control-rats. Measurements of MDA, HNE and carbonyl groups, biomarkers of lipid peroxidation and protein oxidation respectively, were found to be statistically significantly increased in TAA-rats compared to control-rats (3.16-, 2.44- and 1.95-fold, respectively), reflecting the presence of oxidative stress in the brain of TAA-rats. 2D-DIGE analysis of brain cortex protein allowed the detection of 2896 spots, however, image analysis showed no statistically significant differential protein expression between the proteins expressed in TAA- and control-rats. No statistical significant differential protein expression in the cortex of TAA-rats was observed, although oxidative stress biomarkers for lipid and proteins were higher in the brain of TAA-rats than in control-rats. These results support the idea that oxidative post-translational modifications are implicated in HE physiopathology.

Entry of hepatitis C virus into the cell: A therapeutic target

Several receptors have been identified as implicated on viral entry into the hepatocyte; and, this interaction between the virus and potential receptors could modulate infection, spontaneous viral clearance, persistence of the infection and the widespread of the virus as outbreak. Nevertheless, the playing role of each of them remains controversial. The NiemannPick type C1 like 1 gene (NPC1L1) receptor has been recently implicated on hepatitis C virus (HCV) entry into the cell and ezetimibe, an anti-cholesterol drug seems to block that, emerging the idea to control hepatitis C outbreak modulating lipid-related receptors. Hepatitis C infection seems to modulate lipid metabolism according to host genetic background. Indeed, it circulates like a lipoviroparticle. The main aim of this field of vision would be to discuss the role of hepatocyte receptors implicated on virus entry, especially NPC1L1 and the therapeutic options derived from the better knowledge about HCV-lipidsreceptors interaction.

Phosphate-activated glutaminase activity is enhanced in brain, intestine and kidneys of rats following portacaval anastomosis

AIM： To assess whether portacaval anastomosis （PCA） in rats affects the protein expression and/or activity of glutaminase in kidneys, intestines and in three brain areas of cortex, basal ganglia and cerebellum and to explain the neurological alterations found in hepatic encephalopathy （HE）. METHODS： Sixteen male Wistar rats weighing 250-350 g were grouped into sham-operation control （n=8） or portacaval shunt （n = 8）. Twenty-eight days after the procedure, the animals were sacrificed. The duodenum, kidney and brain were removed, homogenised and mitochondria were isolated. Ammonia was measured in brain and blood. Phosphate-activated glutaminase （PAG） activity was determined by measuring ammonia production following incubation for one hour at 37 ℃ with O-phthalaldehyde （OPA） and specific activity expressed in units per gram of protein （pkat/g of protein）. Protein expression was measured by immunoblotting. RESULTS： Duodenal and kidney PAG activities together with protein content were significantly higher in PCA group than in control or sham-operated rats （duodenum PAG activity was 976.95±268.87μkat/g of protein in PCA rats vs 429.19±126.92.μkat/g of protein in shamoperated rats; kidneys PAG activity was 1259.18±228.79 μkat/g protein in PCA rats vs 669.67±400.8 μkat/g of protein in controls, P〈0.05; duodenal protein content： 173% in PCA vs sham-operated rats; in kidneys the content of protein was 152% in PCA vs sham-operated rats）. PAG activity and protein expression in PCA rats were higher in cortex and basal ganglia than those in shamoperated rats （cortex： 6646.6 ±1870.4 μkat/g of protein vs 3573.8± 2037.4 μkat/g of protein in control rats, P〈 0.01; basal ganglia, PAG activity was 3657.3± 1469.6 μkat/g of protein in PCA rats vs 2271.2±384 μkat/g of protein in sham operated rats, P〈0.05; In the cerebellum, the PAG activity was 2471.6±701.4 μkat/g of protein vs 1452.9 ±567.8 μkat/g of protein in the PCA and sham rats, respectively, P〈0.05; content of protein： cerebral cortex： 162% ±40% vs 100% ± 26%, P〈 0.009; and basal ganglia： 140% ±39% vs 100% ±14%, P〈0.05; but not in cerebellum： 100% ±25% vs 100% ± 16%, P= ns）. CONCLUSION： Increased PAG activity in kidney and duodenum could contribute significantly to the hyperammonaemia in PCA rats, animal model of encephalopathy. PAG is increased in non-synaptic mitochondria from the cortex and basal ganglia and could be implicated in the pathogenesis of hepatic encephalopathy. Therefore, PAG could be a possible target for the treatment of HE or liver dysfunction.

Impact of COVID-19 on liver disease: From the experimental to the clinic perspective

Coronavirus disease 2019(COVID-19)has caused a global pandemic unprecedented in over a century.Although severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is a predominantly respiratory infection,various degrees of liver function abnormalities have been reported.Pre-existing liver disease in patients with SARS-CoV-2 infection has not been comprehensively evaluated in most studies,but it can critically compromise survival and trigger hepatic decompensation.The collapse of the healthcare services has negatively impacted the diagnosis,monitoring,and treatment of liver diseases in non-COVID-19 patients.In this review,we aim to discuss the impact of COVID-19 on liver disease from the experimental to the clinic perspective.

Glutaminolysis-ammonia-urea Cycle Axis,Non-alcoholic Fatty Liver Disease Progression and Development of Novel Therapies

The prevalence of non-alcoholic fatty liver disease(NAFLD)is increasing worldwide,reflecting the current epidemics of obesity,insulin resistance,type 2 diabetes mellitus,and metabolic syndrome.NAFLD is characterized by the accumulation of fat in the liver,and is known to be a cause of cirrhosis.Although many pathways have been proposed,the cause of NAFLD-linked fibrosis progression is still unclear,which posed challenges for the development of new therapies to prevent NASH-related cirrhosis and hepatocellular carcinoma.Cirrhosis is associated with activation of hepatic stellate cells(HSC)and accumulation of excess extracellular matrix proteins,and inhibiting the activation of HSCs would be expected to slow the progression of NAFLD-cirrhosis.Multiple molecular signals and pathways such as oxidative stress and glutaminolysis have been reported to promote HSC activation.Both mechanisms are plausible antifibrotic targets in NASH,as the activation of HSCs the proliferation of myofibroblasts depend on those processes.This review summarizes the role of the glutaminolysis-ammonia-urea cycle axis in the context of NAFLD progression,and shows how the axis could be a novel therapeutic target.

What Has the COVID-19 Pandemic Taught Us so Far?Addressing the Problem from a Hepatologist's Perspective

As of today, March 30, 2020, when this Editorial is being written, the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), causal agent of the coronavirus disease (COVID-19) has been confirmed in more than 745,000 cases worldwide and has claimed the lives of more than 35,000 people.1 In addition to the morbidity and mortality associated with COVID-19, this betacoronavirus has placed several of the world's major economies in strife, mainly in Western Europe and North America, paralyzing travel and regular social interactions, making COVID-19 undoubtedly one of the most important pandemics in human history.