Antimitochondrial Rather than Antinuclear Antibodies Correlate with Severe Drug-Induced Liver Injury

[Drug-induced autoimmune-like liver injury]

Drug-induced liver injury (DILI) is a rare yet potentially life-threatening disease. Besides intrinsic DILI, which is mainly caused by paracetamol overdosing and which is dose-dependent and predictable, there is idiosyncratic DILI-an unpredictable and dose-independent injury of the liver caused by certain medications that only occurs in a minority of patients taking this drug. The reason why some patients react with DILI towards a specific drug is still unknown. However, the immune system plays a central role, which is underlined by the association of certain human leukocyte antigen (HLA) polymorphisms and DILI caused by specific drug classes. Due to the immunological processes that lead to the liver injury in DILI, there are great overlaps regarding laboratory and histological parameters between DILI and autoimmune hepatitis (AIH). Differentiating DILI and AIH can therefore be challenging, especially at the time of presentation. In addition, there are other immunologically mediated DILI phenotypes, in particular the newly defined drug-induced autoimmune-like hepatitis (DI-ALH) and liver injuries caused by checkpoint inhibitors (CPI). DI-ALH is characterized by autoimmune features and good responses towards corticosteroids, with the difference that DI-ALH mostly does not relapse after discontinuation of corticosteroids. CPI-induced liver injury has become more frequent with the rising use of those drugs and is characterized by a distinct histopathological pattern with granulomatous hepatitis and infiltration dominated by cytotoxic T cells. Similarly, the recently recognized liver injury following vaccinations also shows an autoimmune phenotype; however, in contrast to AIH, cytotoxic T cells seem to dominate the inflammatory infiltrates in the liver.

Evaluation of patients with positive anti-mitochondiral antibody and normal alkaline phosphatase levels for primary biliary cholangitis

Primary Biliary Cholangitis (PBC) is a chronic cholestatic liver disease typically diagnosed by elevated cholestatic liver enzymes and a positive anti-mitochondrial antibody (AMA) test. The clinical importance of AMA positivity in patients with normal cholestatic liver enzymes is unclear. The aim of this study was to determine the relationship between PBC and AMA positivity detected in individuals with normal cholestatic enzyme levels. The files of patients with AMA and/or AMA-M2 positivity between 2009 and 2018 and whose alkaline phosphatase (ALP) levels were below upper limit of normal (ULN) at initial admission were retrospectively analyzed. The ALP levels were normal in all patients. All patients had AMA positivity demonstrated by indirect immunofluorescence (IIF) or AMA-M2 positivity demonstrated by ELISA. A total of 16 patients underwent liver biopsy and seven (43.75%) showed changes consistent with those with PBC. A total of 12 patients were diagnosed with PBC and were treated and followed up with this diagnosis. People with AMA positivity and normal cholestasis enzyme levels are closely associated with PBC. Some of these patients were diagnosed with PBC as a result of biopsy and some were diagnosed by clinical and laboratory findings during follow-up.. The patients with an AMA titration of 1/20 were not associated with PBC. In our study, results similar to the studies confirmed by biopsies were obtained. In this regard, there is a need for prospective and retrospective studies with longer follow-up periods.

Corydalis and Drug-Induced Liver Injury: A Series of 2 Cases

Corydalis is an herbal plant found in Asian countries. Research has demonstrated multiple health benefits. It has also been implicated in drug-induced liver injury. Cannabis dispensaries market a sleep aid which has corydalis as an active ingredient. We present 2 cases of corydalis-induced hepatotoxicity. An asymptomatic female patient exhibited a rise and fall of her transaminases coinciding with the consumption and rechallenge of this sleep aid. A man with symptoms consistent with liver dysfunction began taking the same sleep aid. With discontinuance, his liver function returned to normal. These 2 clinical cases provide evidence for corydalis-induced liver injury.

Nomenclature, diagnosis and management of drug-induced autoimmune-like hepatitis (DI-ALH): An expert opinion meeting report

Drug-induced liver injury (DILI) can mimic almost all other liver disorders. A phenotype increasingly ascribed to drugs is autoimmune-like hepatitis (ALH). This article summarises the major topics discussed at a joint International Conference held between the Drug-Induced Liver Injury consortium and the International Autoimmune Hepatitis Group. DI-ALH is a liver injury with laboratory and/or histological features that may be indistinguishable from those of autoimmune hepatitis (AIH). Previous studies have revealed that patients with DI-ALH and those with idiopathic AIH have very similar clinical, biochemical, immunological and histological features. Differentiating DI-ALH from AIH is important as patients with DI-ALH rarely require long-term immunosuppression and the condition often resolves spontaneously after withdrawal of the implicated drug, whereas patients with AIH mostly require long-term immunosuppression. Therefore, revision of the diagnosis on long-term follow-up may be necessary in some cases. More than 40 different drugs including nitrofurantoin, methyldopa, hydralazine, minocycline, infliximab, herbal and dietary supplements (such as Khat and Tinospora cordifolia) have been implicated in DI-ALH. Understanding of DI-ALH is limited by the lack of specific markers of the disease that could allow for a precise diagnosis, while there is similarly no single feature which is diagnostic of AIH. We propose a management algorithm for patients with liver injury and an autoimmune phenotype. There is an urgent need to prospectively evaluate patients with DI-ALH systematically to enable definitive characterisation of this condition.

COVID-19-associated secondary sclerosing cholangitis - A case series of 4 patients

We report a case series of four patients diagnosed with COVID-19-associated secondary sclerosing cholangitis (SSC), a recently described rare late complication of severe COVID-19. Following prolonged stays in the intensive care unit, these patients developed marked sustained cholestasis and jaundice despite clinical improvement. Cholangiography showed beaded appearance of intra-hepatic bile ducts and bile casts were removed in one patient. None of the patients reached normalization of liver enzymes and at least one progressed to liver cirrhosis (follow-up time of 11 to 16 months). COVID-19-associated SSC has a dismal prognosis with rapid progression to advanced chronic liver disease.

The future risk of primary biliary cholangitis (PBC) is low among patients with incidental anti-mitochondrial antibodies but without baseline PBC

Anti-mitochondrial autoantibodies (AMAs) are highly specific for the diagnosis of primary biliary cholangitis (PBC) but are also occasionally found in other diseases. In the present study, we evaluated the incidence of and predictors for PBC development in AMA-positive patients with other liver or non-liver diseases at baseline. In this retrospective study, we screened patients who tested positive for AMA and/or anti-mitochondrial M2 antibody (AMA-M2) at Beijing Friendship Hospital, Capital Medical University, from October 2005 to January 2017. They were categorized by their diagnosis at the baseline as patients with PBC or non-PBC cases. We followed up on the non-PBC cases through telephone interviews and reviewing of medical records to obtain laboratory results and clinical outcomes. In total, 139 patients were AMA-positive but did not fulfill the diagnostic criteria of PBC at baseline, including 51 patients with non-PBC liver diseases and 88 cases with non-liver diseases. The titers of AMA-M2, alkaline phosphatase, gamma-glutamyl transpeptidase, and immunoglobulin M were significantly higher in patients with PBC compared to those with non-PBC liver diseases and non-liver diseases. After a median follow-up of 4.6 (interquartile range: 2.4-7.6) years, 4.3% (6 of 139) developed PBC, with an accumulative 5-year incidence rate of 4.2%. None of the patients with non-PBC liver diseases developed PBC, whereas the 5-year incidence rate of PBC was 7.8% among 88 patients with non-liver diseases. Lower alanine aminotransferase and higher immunoglobulin M were independent predictors for developing PBC. Conclusion: Our results suggest a low risk of developing PBC over time in AMA-positive patients with other liver and non-liver diseases.

Marked Increase of Gamma-Glutamyltransferase as an Indicator of Drug-Induced Liver Injury in Patients without Conventional Diagnostic Criteria of Acute Liver Injury

INTRODUCTION

Clinically significant drug-induced liver injury (DILI) is defined by elevations of alanine aminotransferase (ALT) ≥5 times the upper limit of normal (ULN), alkaline phosphatase (ALP) ≥2 × ULN, or ALT ≥3 × ULN and total bilirubin TBIL >2 × ULN. However, DILI might also occur in patients who do not reach those thresholds and still may benefit from discontinuation of medication.

METHODS

Fifteen patients recruited for our prospective study on potentially hepatotoxic drugs were included. DILI diagnosis was based on RUCAM (Roussel Uclaf Causality Assessment Method) score and expert opinion and was supported by an in vitro test using monocyte-derived hepatocyte-like (MH) cells.

RESULTS

Median RUCAM score was 6 (range 4-8), indicating that DILI was possible or probable in all cases. The predominant types of liver injury were mixed (60%) and cholestatic (40%). While no elevation above 2 × ULN of ALP and TBIL was observed, gamma-glutamyltransferase (GGT) above 2 × ULN was identified in 8 of the patients. Six of the 15 patients did not achieve full remission and showed persistent elevation of GGT, which was significantly associated with peak GGT elevation above 2 × ULN (p = 0.005).

CONCLUSION

Here we present a case series of patients with liver enzyme elevation below the conventional thresholds who developed DILI with a predominant GGT elevation leading to drug withdrawal and/or chronic elevation of liver parameters, in particular of GGT. Thus, we propose that DILI should be considered in particular in cases with marked increase of GGT even if conventional DILI threshold levels are not reached, resulting in discontinuation of the causative drug and/or close monitoring of the patients.

Challenges and Future of Drug-Induced Liver Injury Research-Laboratory Tests

Drug-induced liver injury (DILI) is a rare but potentially severe adverse drug event, which is also a major cause of study cessation and market withdrawal during drug development. Since no acknowledged diagnostic tests are available, DILI diagnosis poses a major challenge both in clinical practice as well as in pharmacovigilance. Differentiation from other liver diseases and the identification of the causative agent in the case of polymedication are the main issues that clinicians and drug developers face in this regard. Thus, efforts have been made to establish diagnostic testing methods and biomarkers in order to safely diagnose DILI and ensure a distinguishment from alternative liver pathologies. This review provides an overview of the diagnostic methods used in differential diagnosis, especially with regards to autoimmune hepatitis (AIH) and drug-induced autoimmune hepatitis (DI-AIH), in vitro causality methods using individual blood samples, biomarkers for diagnosis and severity prediction, as well as experimental predictive models utilized in pre-clinical settings during drug development regimes.

Antimitochondrial Antibodies: from Bench to Bedside

Anti-mitochondrial antibodies (AMA) are directed against the E2 subunits of the 2-oxo acid dehydrogenase complexes (PDC-E2) and are the typical biomarkers of primary biliary cholangitis (PBC), being present in 90-95% of patients, with increasing sensitivity at increasing titers. Albeit being highly specific for PBC diagnosis, AMA can be detected in less than 1% of healthy subjects, and thus the management subjects with no sign or symptom of liver disease is still a challenge and data concerning clinical risk of developing PBC in this subgroup of patients are controversial. Moreover, AMA can also be detected in patients affected by overlap syndrome, as well as hepatic diseases (i.e., NASH and viral hepatitis), while the association with autoimmune diseases, in particular Sjögren's syndrome, systemic sclerosis, and systemic lupus erythematosus, is well established. Furthermore, new associations are being identified with inflammatory myositis and heart disease. AMA are directed towards the pyruvate dehydrogenase multi enzyme complex (PDC-E2) subunit, which represents an epithelial specific autoantigen for PBC. This review focuses on the main characteristics of AMA, their association with autoimmune diseases and liver diseases.

The Emerging Role of the Innate Immune Response in Idiosyncratic Drug Reactions

Idiosyncratic drug reactions (IDRs) range from relatively common, mild reactions to rarer, potentially life-threatening adverse effects that pose significant risks to both human health and successful drug discovery. Most frequently, IDRs target the liver, skin, and blood or bone marrow. Clinical data indicate that most IDRs are mediated by an adaptive immune response against drug-modified proteins, formed when chemically reactive species of a drug bind to self-proteins, making them appear foreign to the immune system. Although much emphasis has been placed on characterizing the clinical presentation of IDRs and noting implicated drugs, limited research has focused on the mechanisms preceding the manifestations of these severe responses. Therefore, we propose that to address the knowledge gap between drug administration and onset of a severe IDR, more research is required to understand IDR-initiating mechanisms; namely, the role of the innate immune response. In this review, we outline the immune processes involved from neoantigen formation to the result of the formation of the immunologic synapse and suggest that this framework be applied to IDR research. Using four drugs associated with severe IDRs as examples (amoxicillin, amodiaquine, clozapine, and nevirapine), we also summarize clinical and animal model data that are supportive of an early innate immune response. Finally, we discuss how understanding the early steps in innate immune activation in the development of an adaptive IDR will be fundamental in risk assessment during drug development. SIGNIFICANCE STATEMENT: Although there is some understanding that certain adaptive immune mechanisms are involved in the development of idiosyncratic drug reactions, the early phase of these immune responses remains largely uncharacterized. The presented framework refocuses the investigation of IDR pathogenesis from severe clinical manifestations to the initiating innate immune mechanisms that, in contrast, may be quite mild or clinically silent. A comprehensive understanding of these early influences on IDR onset is crucial for accurate risk prediction, IDR prevention, and therapeutic intervention.

Liver Injury Associated with Metamizole Exposure: Features of an Underestimated Adverse Event

INTRODUCTION AND OBJECTIVE

The potential of metamizole to cause drug-induced liver injury (DILI) has received increasing attention. We investigated the distinguishing features of a case series comprising 32 patients with suspected metamizole-induced DILI.

METHODS

For the current analysis, 32 of 238 patients with DILI included in our prospective study on drugs potentially causing DILI were included. Diagnosis of DILI was based on expert opinion and RUCAM (Roussel Uclaf Causality Assessment Method) score and supported by an in vitro test using monocyte-derived hepatocyte-like cells.

RESULTS

Suspected metamizole-DILI was characterised by a female predominance, hepatocellular pattern of injury, high proportion of antinuclear antibody positivity, and predominance of eosinophilic cell infiltration and necrosis in the histopathological analysis. With 22%, a high proportion of these metamizole-associated liver injury cases developed acute liver failure, which was characterised by a longer latency of metamizole use and more pronounced liver biochemistry abnormalities at onset and peak levels. Furthermore, jaundice was a common finding in the metamizole-associated liver injury cases with 66% presenting with peak bilirubin levels of 3 mg/dL or higher, which was associated with a worse outcome and a higher frequency of acute liver failure.

CONCLUSIONS

Our analysis of a well-characterised DILI cohort further supports the potential of metamizole causing DILI and provides important features for the establishment of a signature pattern of liver injury observed in patients treated with metamizole.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: NCT02353455.