Role of Hepatitis E Virus Infection in North American Patients With Severe Acute Liver Injury

Distinct disease features of acute and persistent genotype 3 hepatitis E virus infection in immunocompetent and immunosuppressed Mongolian gerbils

Hepatitis E virus (HEV) causes self-limited acute hepatitis in immunocompetent individuals and can establish chronic infection in solid organ transplant recipients taking immunosuppressive drugs. A well characterized small animal model is needed to understand HEV pathogenesis. In this study, we established a robust model to study acute and persistent HEV infection using Mongolian gerbils (Meriones unguiculatus) with or without immunosuppression. Gerbils were implanted subcutaneously with continuous release tacrolimus pellet to induce immunosuppression. Gerbils with or without tacrolimus treatment were inoculated with HEV intraperitoneally. Viremia, fecal virus shedding, serum antibody and ALT levels, liver histopathological lesions, hepatocyte apoptosis, and liver macrophage distribution were assessed. Mild to moderate self-limited hepatitis and IgM and IgG antibody responses against HEV ORF2 were observed in immunocompetent gerbils. Levels of HEV-specific IgM responses were higher and lasted longer in immunocompetent gerbils with higher peak viremia. Persistent viremia and fecal virus shedding with either weak, or absent HEV antibody levels were seen in immunosuppressed gerbils. Following HEV infection, serum ALT levels were increased, with lower and delayed peaks observed in immunosuppressed compared to immunocompetent gerbils. In immunocompetent gerbils, foci of apoptotic hepatocytes were detected that were distributed with inflammatory infiltrates containing CD68+ macrophages. However, these foci were absent in immunosuppressed gerbils. The immunosuppressed gerbils showed no inflammation with no increase in CD68+ macrophages despite high virus replication in liver. Our findings suggest adaptive immune responses are necessary for inducing hepatocyte apoptosis, CD68+ macrophage recruitment, and inflammatory cell infiltration in response to HEV infection. Our studies show that Mongolian gerbils provide a promising model to study pathogenesis during acute and persistent HEV infection.

Liver Transplantation for Acute Liver Failure- Indication, Prioritization, Timing, and Referral

Acute liver failure (ALF) is a major success story in gastroenterology, with improvements in critical care and liver transplant resulting in significant improvements in patient outcomes in the current era compared to the dismal survival rates in the pretransplant era. However, the ever-increasing list of transplant candidates and limited organ pool makes judicious patient selection and organ use mandatory to achieve good patient outcomes and prevent organ wastage. Several scoring systems exist to facilitate the identification of patients who need a liver transplant and would therefore need an early referral to a specialized liver unit. The timing of the liver transplant is also crucial as transplanting a patient too early would lead to those who would recover spontaneously receiving an organ (wastage), and a late decision might result in the patient becoming unfit for transplant (delisted) or have an advanced disease which would result in poor post-transplant outcomes. The current article reviews the indications and contraindications of liver transplant in ALF patients, the various prognostic scoring systems, etiology-specific outcomes, prioritization and timing of referral.

Paracetamol (acetaminophen) overdose and hepatotoxicity: mechanism, treatment, prevention measures, and estimates of burden of disease

INTRODUCTION

Paracetamol is one of the most used medicines worldwide and is the most common important poisoning in high-income countries. In overdose, paracetamol causes dose-dependent hepatotoxicity. Acetylcysteine is an effective antidote, however despite its use hepatotoxicity and many deaths still occur.

AREAS COVERED

This review summarizes paracetamol overdose and toxicity (including mechanisms, risk factors, risk assessment, and treatment). In addition, we summarize the epidemiology of paracetamol overdose worldwide. A literature search on PubMed for poisoning epidemiology and mortality from 1 January 2017 to 26 October 2022 was performed to estimate rates of paracetamol overdose, liver injury, and deaths worldwide.

EXPERT OPINION

Paracetamol is widely available and yet is substantially more toxic than other analgesics available without prescription. Where data were available, we estimate that paracetamol is involved in 6% of poisonings, 56% of severe acute liver injury and acute liver failure, and 7% of drug-induced liver injury. These estimates are limited by lack of available data from many countries, particularly in Asia, South America, and Africa. Harm reduction from paracetamol is possible through better identification of high-risk overdoses, and better treatment regimens. Large overdoses and those involving modified-release paracetamol are high-risk and can be targeted through legislative change.

Hepatitis E prevalence and infection in solid-organ transplant recipients in the United States

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis worldwide. An increased risk for HEV infection has been reported in organ-transplant recipients, mainly from Europe. Prospective data on HEV prevalence in the United States (U.S.) organ transplant population are limited. To determine the prevalence and factors associated with HEV infection among solid organ transplant-recipients, we conducted a prospective, cross-sectional, multicentre study among transplant-recipients and age- and organ-matched waitlist patients. Participants answered a risk-exposure questionnaire and were tested for HEV-RNA (in-house PCR), HEV-IgG, and IgM (ELISA, Wantai). Among 456 participants, 224 were transplant-recipients, and 232 were waitlist patients. The mean age was 58 years, 35% female, and 74% White. HEV seroprevalence of the entire cohort was 20.2% and associated with older age (p < 0.0001) and organ transplantation (p = 0.02). The HEV seropositivity was significantly higher among transplant-recipients compared with waitlist patients (24% vs. 16.4%, p = 0.042). Among transplant recipients, relative-risk of being HEV seropositive increased with older age (RR = 3.4 [1.07-10.74] in patients >70 years compared with ≤50 years, p = 0.037); history of graft hepatitis (2.2 [1.27-3.72], p = 0.005); calcineurin inhibitor use (RR = 1.9 [1.03-3.34], p = 0.02); and kidney transplantation (2.4 [1.15-5.16], p = 0.02). HEV-RNA, genotype 3 was detected in only two patients (0.4%), both transplant-recipients. HEV seroprevalence was higher among transplant-recipients than waitlist patients. HEV should be considered in transplant-recipients presenting with graft hepatitis. Detection of HEV-RNA was rare, suggesting that progression to chronic HEV infection is uncommon in transplant-recipients in the U.S.

Incidence of Hepatitis E Infection in American Patients With Suspected Drug-Induced Liver Injury Is Low and Declining: The DILIN Prospective Study

INTRODUCTION

Hepatitis E virus (HEV) infection rarely causes icteric hepatitis, yet 10%-40% of adult Americans have serological evidence of previous infection. The aim of this study was to investigate the incidence, presentation, and outcome of acute and previous HEV infection in a large cohort of patients with suspected drug-induced liver injury (DILI).

METHODS

Serum samples from 2012 patients enrolled in the DILI Network were tested for anti-HEV immunoglobulin G (IgG). Those with detectable anti-HEV IgG underwent testing for anti-HEV IgM; those with detectable anti-HEV immunoglobulin m (IgM) were tested for HEV RNA.

RESULTS

Anti-HEV IgG was detected in 407 (20%) patients and associated with increasing subject age and earlier year of enrollment. The median age of seropositive subjects was more than a decade higher than seronegative subjects (59.8 vs 48.7 years). The overall prevalence of anti-HEV declined from 22% (2004-2011) to 18% (2012-2019), suggestive of a cohort effect. The frequency of acute hepatitis E (median ALT = 1231 IU/L) also decreased from 3% (2004-2008) to 1.2% (2009-2013) to 0.6% (2014-2019). These results suggest that acute HEV infection is usually subclinical and was much more frequent in this cohort before 2004.

DISCUSSION

Acute HEV infection accounts for less than 1% of suspected American DILI cases and is more frequent in older men. Previous HEV infection is also most commonly seen in older individuals. Clinicians should consider testing for unsuspected acute HEV infection in older adult patients with acute hepatocellular DILI and jaundice.

Hepatitis E virus infection in the United States: Seroprevalence, risk factors and the influence of immunological assays

In the United States (U.S.), a hepatitis E virus (HEV) seroprevalence between 6 and 21% has been described, with a decreasing trend. We aimed to investigate HEV infection in the U.S. population from 2009 to 2016, and examine the differences in seroprevalence using different assays. We used data from the National Health and Nutrition Examination Survey (NHANES-CDC) to estimate HEV seroprevalence and analyze demographic variables related to the infection. Additionally, we compared 4 serological tests used. The estimated HEV seroprevalence between 2009–2016 was 6.1% (95% CI: 5.6%-7.0%) for IgG and 1.02% (0.8%-1.2%) for IgM. Higher HEV IgG prevalences were found in older people, females, non-Hispanic Asians and those born outside of the U.S. The in-house immunoassay and the Wantai HEV-IgG ELISA presented the highest sensitivity values in the tested population. The highest specificity values corresponded to the DSI-EIA-ANTI-HEV-IgG assay. The kappa statistical values showed concordances no greater than 0.64 between the assays. HEV prevalence in our study was similar to previously reported, and a decline in the prevalence was observed through the NHANES assessments (from 1988 to 2016). The sensitivity and specificity of the assays varied widely, making comparisons difficult and highlighting the need to develop a gold standard assay.