Andrew S. deLemos

Pharmacological Inhibition of a MicroRNA Family in Nonhuman Primates by a Seed-Targeting 8-Mer AntimiR

Long-term treatment of obese, insulin-resistant nonhuman primates with a seed-targeting antimiR oligonucleotide against the microRNA-33 family derepresses hepatic expression of miR-33 targets, increases circulating HDL cholesterol, and has a clean safety profile. Little AntimiR Packs a Double Punch MicroRNAs (miRNAs) are a type of noncoding RNA that are about 22 nucleotides in length and affect a variety of cellular functions, including normal development and metabolism. These RNAs have also been implicated in many different diseases. Targeted inhibition of miRNAs can be achieved with antimiRs—RNA segments with complementary sequences to miRNAs of interest, which can bind and specifically inhibit their target miRNAs. In humans, miRNAs called miR-33a and miR-33b help control the homeostasis of cholesterol and other lipids, which are associated with cardiovascular disease. To inhibit both of these miRNAs at the same time, Rottiers and colleagues created an unusually short antimiR, only 8 nucleic acids in length, which targets the common portion of both miR-33a and miR-33b. They had tested it in mammalian cells and in mice, and now also confirmed that this short antimiR can be used in nonhuman primates. The authors demonstrated that their antimiR is safe in obese, insulin-resistant nonhuman primates, and that it increases high-density lipoprotein cholesterol. Additional studies will be necessary to learn more about the effects of this 8-mer antimiR on different parameters of metabolism, and to determine how it affects clinical outcomes, such as the risk of death from cardiovascular disease. Nevertheless, this work suggests that miRNA-based approaches could be specifically tailored and potentially safe for patient use, providing an alternative to standard pharmaceutical interventions. MicroRNAs (miRNAs) regulate many aspects of human biology. They target mRNAs for translational repression or degradation through base pairing with 3′ untranslated regions, primarily via seed sequences (nucleotides 2 to 8 in the mature miRNA sequence). A number of individual miRNAs and miRNA families share seed sequences and targets, but differ in the sequences outside of the seed. miRNAs have been implicated in the etiology of a wide variety of human diseases and therefore represent promising therapeutic targets. However, potential redundancy of different miRNAs sharing the same seed sequence and the challenge of simultaneously targeting miRNAs that differ significantly in nonseed sequences complicate therapeutic targeting approaches. We recently demonstrated effective inhibition of entire miRNA families using seed-targeting 8-mer locked nucleic acid (LNA)–modified antimiRs in short-term experiments in mammalian cells and in mice. However, the long-term efficacy and safety of this approach in higher organisms, such as humans and nonhuman primates, have not been determined. We show that pharmacological inhibition of the miR-33 family, key regulators of cholesterol/lipid homeostasis, by a subcutaneously delivered 8-mer LNA-modified antimiR in obese and insulin-resistant nonhuman primates results in derepression of miR-33 targets, such as ABCA1, increases circulating high-density lipoprotein cholesterol, and is well tolerated over 108 days of treatment. These findings demonstrate the efficacy and safety of an 8-mer LNA-antimiR against an miRNA family in a nonhuman primate metabolic disease model, suggesting that this could be a feasible approach for therapeutic targeting of miRNA families sharing the same seed sequence in human diseases.

Genome-wide identification of microRNAs regulating cholesterol and triglyceride homeostasis

Genome-wide association studies (GWASs) have linked genes to various pathological traits. However, the potential contribution of regulatory noncoding RNAs, such as microRNAs (miRNAs), to a genetic predisposition to pathological conditions has remained unclear. We leveraged GWAS meta-analysis data from >188,000 individuals to identify 69 miRNAs in physical proximity to single-nucleotide polymorphisms (SNPs) associated with abnormal levels of circulating lipids. Several of these miRNAs (miR-128-1, miR-148a, miR-130b, and miR-301b) control the expression of key proteins involved in cholesterol-lipoprotein trafficking, such as the low-density lipoprotein (LDL) receptor (LDLR) and the ATP-binding cassette A1 (ABCA1) cholesterol transporter. Consistent with human liver expression data and genetic links to abnormal blood lipid levels, overexpression and antisense targeting of miR-128-1 or miR-148a in high-fat diet–fed C57BL/6J and Apoe-null mice resulted in altered hepatic expression of proteins involved in lipid trafficking and metabolism, and in modulated levels of circulating lipoprotein-cholesterol and triglycerides. Taken together, these findings support the notion that altered expression of miRNAs may contribute to abnormal blood lipid levels, predisposing individuals to human cardiometabolic disorders.

Drug-induced liver injury with autoimmune features.

Drug-induced liver injury (DILI) with features of autoimmunity (AI) represents an important category of hepatotoxicity due to medication exposure. Drugs repeatedly associated with AI-DILI include diclofenac, α-methyl DOPA, hydralazine, nitrofurantoin, minocycline, and more recently statins and anti-TNF-α agents. Usually, symptoms of acute liver injury occur within a few months after initiation of a culprit medication, but a longer latency period is possible. Like idiopathic autoimmune hepatitis, circulating autoantibodies and a hypergammaglobulinemia are frequently present in sera from patients with AI-DILI. If performed, a liver biopsy should demonstrate interface hepatitis with a prominent plasma cell infiltrate. The severity of AI-DILI is variable, but a complete resolution after withdrawal of the offending medication is the expectation. A response to corticosteroid therapy supports the diagnosis, whereas a lack of recurrence of symptoms or signs following corticosteroid cessation distinguishes AI-DILI from idiopathic autoimmune hepatitis.

Hepatitis C treatment: an incipient therapeutic revolution

An exciting paradigm shift is occurring in the treatment of hepatitis C virus (HCV). We now have the capacity to specifically target therapy to HCV proteins, and thereby directly interrupt the viral life cycle. The first direct-acting antivirals (DAAs), the NS3-4A serine protease inhibitors boceprevir and telaprevir, improved the rate of sustained virologic response (SVR), but their toxicities combined with PEG-IFN and RBV limited their overall efficacy. Sofosbuvir, a nucleotide HCV polymerase inhibitor, is now available and offers better tolerability and efficacy across all HCV genotypes. The next phase of therapy will be combining several classes of DAAs without IFN in order to make sustained clearance of hepatitis C deliverable to a much larger number of infected individuals.

Viral hepatitis and hepatocellular carcinoma: etiology and management

Chronic hepatitis B virus (HBV) and chronic hepatitis C virus (HCV) are associated with hepatic fibrosis and development of hepatocellular carcinoma (HCC). There are differences and variation with the incidence of HCC worldwide. Additionally, HCC develops via different pathways with these viral hepatitides. This review outlines the various mechanisms and pathophysiology that contributes to this process. There will also be a review on the recommended screening for HCC. Treatment considerations, which are different for these viruses, will be outlined in this review.

Systemic Causes of Cholestasis

Systemic causes of cholestasis constitute a diverse group of diseases across organ systems. The pathophysiology of cholestasis in systemic disease can be a consequence of direct involvement of a disease process within the liver or extrahepatic biliary system or secondary to immune-mediated changes in bile flow. Evaluating a patient with cholestasis for a systemic cause requires an understanding of the patient’s risk factors, clinical setting (eg, hospitalized or immunosuppressed patient), clinical features, and pattern of laboratory abnormalities.

Recurrent hepatitis C after liver transplant.

End stage liver disease from hepatitis C is the most common indication for liver transplantation in many parts of the world accounting for up to 40% of liver transplants. Antiviral therapy either before or after liver transplantation is challenging due to side effects and lower efficacy in patients with cirrhosis and liver transplant recipients, as well as from drug interactions with immunosuppressants. Factors that may affect recurrent hepatitis C include donor age, immunosuppression, IL28B genotype, cytomegalovirus infection, and metabolic syndrome. Older donor age has persistently been shown to have the greatest impact on recurrent hepatitis C. After liver transplantation, distinguishing recurrent hepatitis C from acute cellular rejection may be difficult, although the development of molecular markers may help in making the correct diagnosis. The advent of interferon free regimens with direct acting antiviral agents that include NS3/4A protease inhibitors, NS5B polymerase inhibitors and NS5A inhibitors holds great promise in improving outcomes for liver transplant candidates and recipients.

Risk factors for hepatocellular carcinoma in cirrhosis due to nonalcoholic fatty liver disease: A multicenter, case-control study

AIM To identify risk factors associated with hepatocellular carcinoma (HCC), describe tumor characteristics and treatments pursed for a cohort of individuals with nonalcoholic steatohepatitis (NASH) cirrhosis. METHODS We conducted a retrospective case-control study of a well-characterized cohort of patients among five liver transplant centers with NASH cirrhosis with (cases) and without HCC (controls). RESULTS Ninety-four cases and 150 controls were included. Cases were significantly more likely to be male than controls (67% vs 45%, P < 0.001) and of older age (61.9 years vs 58 years, P = 0.002). In addition, cases were more likely to have had complications of end stage liver disease (83% vs 71%, P = 0.032). On multivariate analysis, the strongest association with the presence of HCC were male gender (OR 4.3, 95%CI: 1.83-10.3, P = 0.001) and age (OR = 1.082, 95%CI: 1.03-1.13, P = 0.001). Hispanic ethnicity was associated with a decreased prevalence of HCC (OR = 0.3, 95%CI: 0.09-0.994, P = 0.048). HCC was predominantly in the form of a single lesion with regional lymph node(s) and distant metastasis in only 2.6% and 6.3%, respectively. Fifty-nine point three percent of individuals with HCC underwent locoregional therapy and 61.5% underwent liver transplantation for HCC. CONCLUSION Male gender, increased age and non-Hispanic ethnicity are associated with HCC in NASH cirrhosis. NASH cirrhosis associated HCC in this cohort was characterized by early stage disease at diagnosis and treatment with locoregional therapy and transplant.

Surgery in the Patient With Liver Disease and Postoperative Jaundice

In a patient with liver disease, the degree of liver impairment should be evaluated carefully before surgery. The Model for End-stage Liver Disease (MELD) score, used to prioritize candidates awaiting liver transplantation, can also be used to help predict the risk of postoperative mortality in patients with cirrhosis. Strategies to mitigate the risk of liver-related morbidity in patients with cirrhosis undergoing surgery include avoiding hypotension, minimizing the duration of anesthesia, and limiting exposure to narcotics and sedatives to avoid precipitating hepatic encephalopathy. For treatment of hepatocellular carcinoma, minimally invasive surgery with radiofrequency or microwave ablation is increasingly used in patients with cirrhosis, with excellent outcomes. Postoperative patients with ascites who require volume expansion, should receive 25% albumin or blood products rather than crystalloid. In addition, it is crucial to avoid nephrotoxic agents such as nonsteroidal antiinflammatory drugs to prevent the development of hepatorenal syndrome. Postoperative jaundice can occur in patients with or without liver disease due to an increase in serum bilirubin levels from blood transfusions or resorption of hematomas or from intrahepatic cholestasis resulting from drug-induced liver injury, sepsis, ischemia, or total parenteral nutrition.