Autoimmune hepatitis and thyroiditis associated with rifampin and pyrazinamide prophylaxis: an unusual reaction

Tracing environmental markers of autoimmunity: introducing the infectome

We recently introduced the concept of the infectome as a means of studying all infectious factors which contribute to the development of autoimmune disease. It forms the infectious part of the exposome, which collates all environmental factors contributing to the development of disease and studies the sum total of burden which leads to the loss of adaptive mechanisms in the body. These studies complement genome-wide association studies, which establish the genetic predisposition to disease. The infectome is a component which spans the whole life and may begin at the earliest stages right up to the time when the first symptoms manifest, and may thus contribute to the understanding of the pathogenesis of autoimmunity at the prodromal/asymptomatic stages. We provide practical examples and research tools as to how we can investigate disease-specific infectomes, using laboratory approaches employed from projects studying the “immunome” and “microbiome”. It is envisioned that an understanding of the infectome and the environmental factors that affect it will allow for earlier patient-specific intervention by clinicians, through the possible treatment of infectious agents as well as other compounding factors, and hence slowing or preventing disease development.

Hepatotoxicity of antibiotics: a review and update for the clinician

Collectively, the various classes of antibiotics are a leading cause of drug-induced liver injury (DILI). However, acute antibiotic-associated DILI can be difficult to diagnose, as the course of therapy is usually brief, and other confounding factors are often present. In addition to the broad clinicopathologic spectrum of hepatotoxicity associated with the antimicrobials, the underlying infectious disease being treated may itself be associated with hepatic dysfunction and jaundice. This review provides summarized information on several classes of antimicrobial agents, highlighting new agents causing DILI and updating information on older agents.

Infectome: a platform to trace infectious triggers of autoimmunity

The "exposome" is a term recently used to describe all environmental factors, both exogenous and endogenous, which we are exposed to in a lifetime. It represents an important tool in the study of autoimmunity, complementing classical immunological research tools and cutting-edge genome wide association studies (GWAS). Recently, environmental wide association studies (EWAS) investigated the effect of environment in the development of diseases. Environmental triggers are largely subdivided into infectious and non-infectious agents. In this review, we introduce the concept of the "infectome", which is the part of the exposome referring to the collection of an individual's exposures to infectious agents. The infectome directly relates to geoepidemiological, serological and molecular evidence of the co-occurrence of several infectious agents associated with autoimmune diseases that may provide hints for the triggering factors responsible for the pathogenesis of autoimmunity. We discuss the implications that the investigation of the infectome may have for the understanding of microbial/host interactions in autoimmune diseases with long, pre-clinical phases. It may also contribute to the concept of the human body as a superorganism where the microbiome is part of the whole organism, as can be seen with mitochondria which existed as microbes prior to becoming organelles in eukaryotic cells of multicellular organisms over time. A similar argument can now be made in regard to normal intestinal flora, living in symbiosis within the host. We also provide practical examples as to how we can characterise and measure the totality of a disease-specific infectome, based on the experimental approaches employed from the "immunome" and "microbiome" projects.

Terbinafine-induced acute autoimmune hepatitis in the setting of hepatitis B virus infection

OBJECTIVE

To report a case of terbinafine-induced autoimmune hepatitis in a patient with chronic hepatitis B infection.

CASE SUMMARY

A 57-year-old Taiwanese male with chronic hepatitis B virus (HBV) began an oral regimen of terbinafine 250 mg once daily for dermatophyte toenail onychomycosis, despite the manufacturer's recommendation not to use the drug in patients with liver dysfunction. The patient's liver enzyme levels were within normal limits at initiation of therapy. Immediately prior to concluding the 12 week treatment course, he became anorexic with malaise and subsequently developed ascites and jaundice. After a visit to an outside emergency department and positively trending liver function test levels, he was referred to our liver clinic. The patient was taking no other medications or herbal supplements, did not drink alcohol, and did not appear to suffer a flare of HBV infection. The diagnosis was supported by the presence of transient autoantibodies and a liver biopsy consistent with acute autoimmune drug injury. Three weeks after terbinafine was discontinued, peak levels of aspartate aminotransferase (1282 IU/L), alanine aminotransferase (1044 IU/L), and bilirubin (5.9 mg/dL) were noted; his platelet level had decreased to 77 x 10(3)/mm3. He was treated with supportive care that included vitamin K for coagulopathy, diuretics for ascites, and adefovir to prevent hepatitis B exacerbation. The patient's liver function studies began to normalize 6 weeks after terbinafine was discontinued.

DISCUSSION

Terbinafine-induced hepatobiliary dysfunction, due to hepatocellular injury, cholestasis, or mixed form, has been reported, but this is the first case of autoimmune hepatitis supported by serologic, biochemical, and biopsy results. Use of the Naranjo probability scale revealed a probable relationship between the patient's hepatitis and terbinafine. Furthermore, the Roussel Uclaf Causality Assessment Method, a scoring system that specifically assesses the likelihood of drug-induced elevated levels of liver-associated enzymes, also supported a probable relationship. The pathogenesis of most drug-induced autoimmune hepatitis remains speculative, likely involving hapten-carrier complex and the cytochrome P450 isoenzymes. In this patient, his chronic HBV carrier state may have predisposed him to this autoimmune reaction.

CONCLUSIONS

Healthcare practitioners should heed the manufacturer's warning that terbinafine not be used in patients with underlying hepatic disease.

Allergic hepatitis induced by drugs

PURPOSE OF REVIEW

To examine recent advances in our understanding of how drugs can trigger a hypersensitivity reaction in the liver, how tolerance is lost, the mechanisms of damage to hepatocytes and the strategies towards a better assessment of an idiosyncratic drug liver reaction.

RECENT FINDINGS

Formation and presentation of drug-protein adducts, or a direct interaction with the major histocompatibility complex/T-cell receptor complex is a necessary but not sufficient stimulus to trigger a hypersensitivity reaction. Liver shows considerable tolerogenic potential towards drug adducts. Recent studies highlight allergic hepatitis as a loss of liver tolerance towards drug antigens, the mechanisms of which are beginning to be unravelled. Cell injury caused by the drug itself, a concomitant inflammatory process, or a coincidental stimulus probably represents the additional signal needed to initiate the allergic process.

SUMMARY

Drug-induced liver injury is of concern due to its unpredictable nature and serious clinical implications. Clinically, both hepatocellular injury and cholestasis can occur and most episodes have good clinical prognoses upon drug discontinuation. In a few cases, damage to the liver cells may continue in the form of an autoimmune hepatitis. The available diagnostic tools to confirm an immune-mediated hepatic injury are still very limited, and rely on the lymphocyte transformation test.