A mechanistic insight into MDMA-mediated hepatotoxicity

methylenedioxymethamphetamine (MDMA, Ecstasy) is a popular drug of abuse among young people that can induce adverse effects. However, these effects lack a specific pattern, as consumption quantities are not correlated with the initiation and severity of the injury. MDMA can cause drug-induced liver injury (DILI). Two suggested pathways that play a role in the onset of DILI are direct hepatotoxicity due to toxic metabolites and adverse immune responses. Therefore, we studied MDMA interactions with phase I and II enzymes and the possible alteration of immune events in several in vitro systems (human liver (THLE) cells transfected with individual CYP450, rat liver microsomes, human PXR-mediated CYP3A4-reporter gene assay, rat primary hepatocytes, HepG2, THP-1 and PBMC). Our data suggests that not only CYP2D6 but also CYP3A4 plays an important role in MDMA bioactivation. Furthermore,MDMA alone or in combination with other therapeutic drugs inhibited CYP3A catalytic activity. This appeared to be due to decreased activation of its main regulator pregnane X receptor (PXR) which subsequently decreases CYP3A gene expression. Therefore, MDMA use in combination with other (therapeutic) drugs could induce adverse drug-drug interactions through interactions with PXR and/or CYP3A. Following metabolism by phase II enzymes, interactions between MDMA/HHMA (a toxic MDMA metabolite) and the glutathione system were observed. HHMA significantly decreased cell viability and depleted GSH levels, resulting in an increased expression of glutamate cysteine ligase catalytic subunit (GCLC) and glutathione-S-transferase (GST). Upon MDMA exposure GSH levels and GCLC expression were not significantly affected, although GST expression was increased. Moreover, we evaluated the potential protective effects of two antioxidants, N-acetyl-cysteine (NAC) and sulforaphane (SFN). NAC counteracted MDMA-induced cytotoxicity and restored GSH levels. Phase II enzyme expression was also reverted. Conversely, SFN increased MDMA-induced cytotoxicity, GSH depletion, GCLC and GST expression. The differential behavior of both antioxidants indicates that care should be taken when using them during treatment of MDMA intoxications, since NAC could very rapidly restore GSH levels, while SFN lacks this effect.Finally, we investigated the role of the immune system on MDMA-mediated liver injury using liver and immune cells in a co-culture model. A protection (HepG2/THP-1) versus impairment (HepG2/PBMC) of MDMA-induced HepG2 cell viability was observed. In THP-1 cells, TNF‑α expression was moderately decreased and IL-8 expression was increased. In the HepG2/PBMC model, MDMA exposure reduced TNF-α and IL-8 but increased IL-10 gene expression, comparable with effects observed in MDMA users. These data suggests that the HepG2/PBMC model is useful to study drug-induced liver toxicity. Using this model, we have shown that immunosuppression appeared to be partially mediated by antagonistic effects of MDMA on peroxisome proliferator activated receptor alpha (PPARα) in HepG2 cells. Taken together, MDMA interactions with metabolizing enzymes and the nuclear receptors that regulate them may alter the metabolic pattern of individuals. This should be taken into account when searching for a clinical treatment to counteract MDMA-mediated side effects. Furthermore, MDMA may cause a greater susceptibility to infectious diseases through a reduction of pro-inflammatory events

A mechanistic insight into 3,4-methylenedioxymethamphetamine ("ecstasy")-mediated hepatotoxicity

3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") is a popular drug of abuse among young people with stimulant and hallucinogenic properties. The drug is generally thought to be safe among consumers due to its low-mortality rates. However, MDMA-adverse effects can occur and the risks are not clearly associated to a specific pattern since the consumption quantity seems not to be correlated with the initiation and severity of the injury. MDMA-mediated adverse health effects have been widely studied and can be evoked by multiple factors such as hyperthermia, polydrug abuse (drug-drug interactions), the altered release of neurotransmitters, impairment of mitochondrial function and apoptosis, metabolism and immune responses. Another adverse effect often associated with MDMA is liver toxicity, yet the mechanism of MDMA-induced liver toxicity is not completely understood. A critical starting point appears to be the hepatic metabolism of MDMA by phase I and II enzymes, leading to reactive metabolites. Elucidating the mechanism of hepatic injury mediated by MDMA is of high toxicological and clinical relevance. In this review, an overview of the literature and the latest findings with respect to the mechanism of MDMA-mediated liver toxicity is described

Differential roles of phase I and phase II enzymes in 3,4-methylendioxymethamphetamine-induced cytotoxicity.

Metabolism plays an important role in the toxic effects caused by 3,4-methylenedioxymethamphetamine (MDMA). Most research has focused on the involvement of CYP2D6 enzyme in MDMA bioactivation, and less is known about the contribution of other cytochrome P450 (P450) and phase II metabolism. In this study, we researched the differential roles of phase I P450 enzymes CYP1A2, CYP3A4, and CYP2D6 and phase II enzymes glutathione S-transferase (GST) and catechol-O-methyltransferase (COMT) on the toxic potential of MDMA. MDMA acts as inhibitor of its own metabolism with a relative potency of inhibition of CYP2D>CYP3A>> CYP1A in rat liver microsomes and in human liver [immortalized human liver epithelial cells (THLE)] cells transfected with individual CYP1A2, CYP3A4, or CYP2D6. Cytotoxicity measurements [by 3,(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] in THLE cells showed that the inhibition of phase I enzymes CYP1A2 by alpha-naphthoflavone and CYP3A4 by troleandomycin does not affect MDMA-induced cytotoxicity. MDMA metabolism by CYP2D6 significantly increased cytotoxicity, which was counteracted by CYP2D6 inhibition by quinidine. Inhibition of COMT by 2'-fluoro-3,4-dihydroxy-5-nitrobenzophenone (Ro-41-0960) and GST by buthionine sulfoximine showed that COMT is mainly involved in detoxification of CYP2D6-formed MDMA metabolites, whereas glutathione (GSH) is mainly involved in detoxification of CYP3A4-formed MDMA metabolites. Liquid chromatography/tandem mass spectrometry analyses of MDMA-metabolites in the THLE cell culture media confirmed formation of the specific MDMA metabolites and corroborated the observed cytotoxicity. Our data suggest that CYP2D6 as well as CYP3A4 play an important role in MDMA bioactivation. In addition, further studies are needed to address the differential roles of CYP3A4 and GSH/GST in MDMA bioactivation and detoxification