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Is green tea a potential trigger for autoimmune hepatitis?


Article history:

Received 14 March 2013

Received in revised form 24 May 2013

Accepted 2 July 2013


Autoimmune hepatitis


Green tea

Single nucleotide polymorphism


A case of autoimmune liver hepatitis is reported: the onset was triggered by consumption of green tea infusion in a patient taking oral contraceptives and irbesartan.

We hypothesize that our patient, carrying genetic variant of hepatic metabolism making her particularly susceptible to oxidative stress, developed an abnormal response to a mild toxic insult, afforded by a combination of agents (oral contraceptives + irbesartan + green tea) that normally would not be able to cause damage. Her particular hepatic metabolism further increased the drugs' concentration, favoring the haptenization of liver proteins, eventually leading to the development of an autoimmune hepatitis.

[c] 2013 Elsevier GmbH. All rights reserved.


Green tea (Camellia sinensis) is a worldwide consumed beverage, used for almost 50 centuries. Green tea's popularity recently increased with scientific evidences that demonstrate its beneficial health effects, such as reduced risk of cardiovascular and degenerative diseases, likely due to the antioxidant properties of polyphenols. Among them, catechins, and in particular epigallocatechin-3-gallate (EGCG), seem to be the most effective compound in exerting the beneficial effects of green tea (Boehm et al. 2009). Although EGCG has widely demonstrated an antioxidant effect and radical scavenging activity, recent data suggest also a pro-oxidant activity (Forester and Lambert 2011). This oxidative effect may also exert some benefit, inducing apoptosis in tumor cells and, at the same time, stimulating endogenous antioxidant systems in normal tissues, potentially exerting protection against carcinogenic insults (Forester and Lambert 2011). Despite its positive effects and its wide consumption, recently, some reports of suspected green tea-related hepatic reactions have also been published; those were generally observed in subjects taking high doses of dietary supplements containing concentrated or purified tea preparations, even if one case study reported hepatotoxicity after consumption of 6 cups/day of green tea infusion (Mazzanti et al. 2009). The potential hepatotoxicity of green tea could be related to EGCG-induced oxidative stress with the main evidences supporting an idiosyncratic or immune-mediated mechanism (Lambert et al. 2010). The major risk factors implicated in idiosyncratic drug induced liver injury are old age, female gender, high dose, drug interactions, cross-sensitizations, genetic factors, and hepatic metabolism of the compounds (Czaja 2011). In addition, as it happens with other herbal remedies, green tea molecules may act as triggers for an immune process and may lead to an autoimmune like hepatitis (AIH) according to the 'hapten hypothesis' (Czaja 2011).

Here we report a case of autoimmune liver hepatitis whose onset was triggered by consumption of green tea infusion in a patient taking oral contraceptives and irbesartan.

Case presentation

A 42-year-old woman was admitted to the Gastroenterology Unit of Careggi University Hospital of Florence for sudden onset of jaundice, without fever or abdominal pain. Laboratory analyses revealed total bilirubin level 31 mg/dl, direct bilirubin 21 mg/d1, aspartate aminotransferase 1447 U/1; alanine aminotransferase (ALT), 1618 U/1, [gramma] glutamiltransferase (GGT) 158 U1/1, alkaline phosphatase (AP) 115 U/1, [gramma]-globulin 20%. An extensive diagnostic workup discarded any other known etiology for liver disease, included viral serology for hepatitis (HAV, HBV, HCV, CMV, EBV, HSV, HIV), auto-antibodies (ANA, AMA, ASMA, anti-LKM, anti-Sp100, anti-gp210, anti-LC1, anti-SLA) and extensive toxicology screening. The remaining blood chemistry findings were negative. A liver biopsy (16 portal spaces) revealed multifocal hepatocytes necrosis especially at zone 3, apoptosis of several hepatocytes, and portal, peri-portal and lobular moderate mononuclear infiltration. With regard to drug therapy, the patient was taking since several years irbesartan 150 mg/day for hypertension and a combination of gestalene and 17a-ethinylestradiol as oral contraceptive. A detailed review of her clinical history revealed that she had been drinking Japanese "matcha" green tea (micronized water-soluble powder of Camellia sinensis) every other day (correspondent to 1.0 g/die of catechins) for 10 days. Due to the persistence of hepatic insufficiency and jaundice after three weeks, steroid therapy with prednisone 50 mg/die was started, with a progressive tapering in one month. Following one month of steroid therapy the blood chemistry was as follows: AST 87, ALT 124, GGT 92, AP 84, total bilirubin 2.5 mg/dl (direct 1.3). However, 10 days following steroid withdrawal, liver function tests worsened again (AST 792, ALT 1088, GGT 389, AF 115, total bilirubin 4.23). Prednisone 50 mg/die was re-started with a slower tapering up to complete normalization of liver function tests. A slight positivity of ANA antibodies 1:160 was found twice.

In order to investigate the possible role of the genetic variability in the toxicity observed in the patient, we genotyped various polymorphisms that potentially affect the function/expression of a set of enzymes involved in the regulation of liver function (Table 1). We found that the patient carries various genetic variants that could affect phase I (via CYP3A4) and phase II (via UGT and GST-M1/P1) drug metabolism, transport (via MDR1) and folate metabolism (via MTHFR).

Table 1

Results of the molecular genetic analyses of the patient.

Gene                          rs (c)    MAF  Genotype  Enzyme
                                        (a)            activity

Phase I

CYP3A4       IVS10+12C>A *   2242480   0.12  C/A (b)   Increased

Phase II

UGT1A1            (TA) 6>7   8175347   0.35  6/7 (b)   Decreased

UGT1A9            -118(T)9                   9/9 (b)   Decreased

SULT1A1              G638A   92828G1       0.24  C/C   Normal

GSTM1                  Del             0.50  NULL (b)  Absent

GSTT1                  Del                   0.17  +   Normal

GSTP1            Ile105Val      1695   0.38  A/G (b)   Decreased


MDR1               3435T>C   1045642   0.45  T/C (b)   Decreased


MTHFR        C677T; A1298C  1801133;  0.31;  C/C; C/C  Decreased
                             1801131        0.36  (b)

Gene         Reference

Phase I

CYP3A4       He et al.

Phase II

UGT1A1       Kiang et
             al. (2005)



GSTM1        Bolufer et
             al. (2006)


GSTP1        Bolufer et
             al. (2006)


MDR1         Wang and


MTHFR        Bolufer et
             al. (2006)

(a) MAF minor allele frequency in Caucasian population.

(b) Polymorphisms potentially concurrent to patients genetic

(c) DB SNP

To definitely exclude the presence of contaminants (heavy metals, aflatoxines), laboratory analyses on the green tea powder were performed by means of high-performance liquid chromatography-mass spectrometry.

In our patient, although in a first phase most serum autoantibodies were negative with the exception of low titer ANA, several pieces of information strongly suggested an autoimmune pathogenesis of the liver injury: rapid response to steroids, relapse after steroid withdrawal, histology consistent with autoimmune hepatitis, and the complete resolution after a prolonged course of immunosuppressive therapy. Consistently, the 'Revised scoring system for the diagnosis of autoimmune hepatitis' proposed by the International Autoimmune Hepatitis Group Report obtained a score consistent with 'probable autoimmune hepatitis' (Alvarez et al. 1999).


Since the patient presented with an acute liver damage, our first diagnostic hypothesis was an acute toxic hepatitis. This was also compatible with the histological findings at liver biopsy. Nevertheless, since the clinical features of the patient markedly improved after steroid treatment and worsened again after steroid withdrawal, a diagnosis of autoimmune hepatitis, triggered by an acute toxic damage, was finally performed.

The patient was taking since a long time irbesartan and a combination of gestodene and 17[alpha]-ethinylestradiol. 17[alpha]-Ethinylestradiol is mainly metabolized via intestinal and hepatic oxidation (CYP3A4), glucuronidation (UGT1A1) and sulfation (SULTs) (Zhang et al. 2007) while irbesartan is metabolized by CYP2C9 and CYP3A4 (Marino and Vachharajani 2001). The patient resulted heterozygote for the CYP3A4 gene 1VS10+12G>A polymorphisms (rs2242480) and for the UGT1A1 gene * 28 polymorphism associated to a decreased enzymatic activity (Kiang et al. 2005); moreover the patient is homozygote for the UGT1A9 * 22 polymorphism associated with a reduced transcriptional activity (Table 1).

The effect of the A allele of CYP3A4 intron 10 (rs2242480) polymorphisms is still controversial, it has been associated with reduced CYP3A4 expression (Zhang et al. 2010) but recently it has been shown, by a luciferase assay, that the A allele had significantly higher transcriptional activity than the G allele (He et al. 2011).

According to these recent evidences, oral contraceptives (OC) metabolism of the patient could be increased with consequent major bioavailability of intermediates. Moreover the intermediates concentration was likely further increased due to a defective efflux transport due to MDR1 3435T/C genotype (Wang and Sadee 2006).

The patient was also assuming a high-concentrated green tea infusion since ten days from the occurrence of jaundice. Green tea glucuronidation is reduced by the presence of UGT1A1 and UGT1A9 SNPs carried by the patient with consequent increased of EGCG bioavailability (Feng 2006). Also EGCG has been proven to have in vitro inhibitory effects on UGT and CYP3A4 enzymes, and on P-gp function (Jodoin et al. 2002) with potential further increase of intermediates and consequent oxidative stress (Feng 2006). Thus in this context the role of EGCG seems to be unbalanced toward a pro-oxidant effect. In fact EGCG has been classically regarded as an antioxidant, but several data suggest that EGCG-inducal oxidative stress may also play a role in the toxic potential of green tea (Lambert et al. 2010). The risk may exist for high doses, although at least one case study has reported hepatotoxicity after consumption of 6 cups/clay of green tea infusion (Mazzanti et al. 2009).

Tea extract and EGCG have shown in vitro an inhibitory effect on folic acid uptake (Alemdaroglu et al. 2007) and the patient was found carrying the MTHFR 1298CC genotype linked to decreased MTHFR activity (Bolufer et al. 2006) suggesting possible further oxidative damage.

Therefore patient reduced glutathione-related detoxification system (GSTM1 null and GSTP1 Ile/Val) (Bolufer et al. 2006) seems to indicate a general genetic predisposition toward oxidative damage.

So, with respect to the diagnosis of autoimmune hepatitis, we suggest that in the potentially hepatotoxic context of the patient, the EGCG could have triggered an immune-mediated process.

In fact high EGCG bioavailability, resulting in further inhibition of UGT1A1, contributed to the increased concentration of final drug intermediates that could have acted as haptens: protein adducts that may be recognized by the immune system as neoantigens and immunocyte activation generating a utoantibodies and cell-mediated immune responses (Fig. 1). In fact, the "hapten hypothesis" proposes that a drug metabolite can act as a hapten and modify the self of the individual by covalently binding to proteins (Czaja 2011).

This AIH predisposition picture is enriched by other risk factors as gender (AIH has been related to a female predominance) (Czaja 2011), dose and drug interactions. It is known that certain drugs or herbs can modify the hepatotoxic potential of other drugs by enzyme induction/inhibition and lead to formation of reactive metabolites (Czaja 2011).


With respect to the drugs assumed by the patient, estrogen and irbesartan were associated to the onset of hepatic injury also autoimmune-like type (Navarro and Senior 2006). On the other hand irbesartan and oral contraceptives were well tolerated by the patient for several years, suggesting that they were not sufficient to cause AIH.

Most drug-induced liver injuries have an acute onset and manifest histological patterns that can be categorized as hepatocellular, cholestatic, or mixed. Drug-induced liver injuries, mimicking an autoimmune hepatitis, are unpredictable idiosyncratic or hypersensitivity reactions as in the present report. Genetic differences in activation of drugs in toxic intermediate molecules and their detoxification can explain the inter-individual differences in susceptibility to liver damage, accounting also for their intrinsic idiosyncratic nature. Reactive drug metabolites can act as haptens through a covalent link with proteins and form an immune-complex protein-drug which, after being processed by antigen-presenting cells, stimulates both cyto-toxic T cells and antibody responses. Moreover, the metabolism of a drug can determine lipid peroxidation, due to the formation of free radicals. These events can produce signals that activate the immune system.

In conclusion, we hypothesize that our patient, carrying genetic variant of hepatic metabolism making her particularly susceptible to oxidative stress, developed an abnormal response to a mild toxic insult, afforded by a combination of agents (oral contraceptives + irbesartan +green tea) that normally would not be able to cause damage. Her particular hepatic metabolism might have further increased the drugs' concentration, favoring the haptenization of liver proteins, eventually leading to the development of an autoimmune hepatitis. It should be also kept in mind that the health benefits afforded by the intake of high-dose antioxidant food supplements, widespread in many patients out of medical control, might be overestimated. Natural products are not devoid of side effects and their use should always be reported to pharmacists and doctors, who should advise their patients on the opportunity of the assumption.


This work is supported by a grant from the Italian Ministry of Health ("Progetto Giovani Ricercatori" 2007).

Conflict of interest


Short communication

Abbreviations: EGCG, epigallocatechin-3-gallate; AIH, autoimmune like hepatitis; ALT, alanine aminotransferase; GGT, glutamiltransferase; AP, alkaline phosphatase; CYP, cytochrome P450; UGT, UDP glucuronosyltransferase; GST, glutathione S-transferase; MDR, multidrug resistance; MTHFR, methylenetetra-hydrofolate reductase; SULT, sulfotransferase.

* Corresponding author at: University of Florence. Department of NeuroFarBa. CIMMBA, Viale Pieraccini 6,50139, Italy. Tel.: +39 4271522; fax: +39 0554271280.

E-mail address: (V. Maggini).

(1) These authors contributed equally to this study.

0944-7113/$--see front matter [c] 2013 Elsevier GmbH. All rights reserved.


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Eugenia Gallo (a), (l), Valentina Maggini (a), * (1), Margherita Berardi (b), Alessandra Pugi (a), Rosario Notaro (b), Giulia Talini (b), Giancarlo Vannozzi (c), Siro Bagnoli (c), Paolo Forte (c), Alessandro Mugelli (a), (d), Vito Annese (c), Fabio Firenzuoli (a), (d), Alfredo Vannacci (a), (d)

(a) University of Florence, Department of Neuroscience. Psychology. Drug Research and Child Health (NeuroFarBa), Center of Molecular Medicine (CIMMBA), Florence; Italy

(b) Cancer Genetics and Gene Transfer Unit, Core Research Laboratory--Istituto Toscano Turnori, AOUC, Florence, Italy

(c) Gastroenterology Unit at the Careggi University Hospital of Florence, Italy

(d) Center for Integrative Medicine, Careggi General Hospital, University of Florence, Italy
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Author:Gallo, Eugenia; Maggini, Valentina; Berardi, Margherita; Pugi, Alessandra; Notaro, Rosario; Talini,
Publication:Phytomedicine: International Journal of Phytotherapy & Phytopharmacology
Article Type:Report
Geographic Code:4EUIT
Date:Oct 15, 2013
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