Toxins mechanism in instigating hepatotoxicity

Zinc and L-carnitine combination with or without methotrexate prevents intestinal toxicity during arthritis treatment via Nrf2/Sirt1/Foxo3 pathways: an In vivo and molecular docking approach

Methotrexate (MTX) is an antifolate that is inescapable and widely used to treat autoimmune diseases and is the gold standard medicine for the arthritic condition. Despite its importance, it is more prone to gastrointestinal toxicity, which is most common in arthritis patients during MTX treatment. Combination therapies are required to ensure MTX's antiarthritic activity while providing gastrointestinal protection. Zinc (Zn) and L-carnitine (Lc) are well-known potent antioxidants and anti-inflammatory supplements with promising results in pre-clinical studies. Arthritis was induced in Wistar rat's ankles with Freund's adjuvant and treated with either MTX (2.5 mg/kg b.w per week for two weeks) or Zn (18 mg/kg b.w. per day) Lc (200 mg/kg b.w. per day) individually or in combination (MTX + Zn Lc). The antiarthritic effects were evaluated by body weight, paw volume, ankle tissue, and joint histopathology. At the same time, anti-toxicity/gastrointestinal protective activity was examined by tissue oxidative stress markers, antioxidants, mitochondrial function, inflammatory mediators, and antioxidant signaling proteins and their binding mechanism. Repercussions of MTX intoxication induced upregulation of oxidative stress markers, antioxidant depletion, ATP depletion, decreased expression of Nrf2/Sirt1/Foxo3, and the overexpression of inflammatory mediators attenuated by co-treatment with Zn Lc. Zn Lc markedly mitigated MTX-instigated intestinal injury by activating antioxidant signaling mechanisms Nrf2/Sirt1/Foxo3 signaling and tissue architectural anomalies and exhibited an enhanced antiarthritic effect. In conclusion, we report that Zn Lc and MTX combination could presumably protect the intestine from low-dose MTX which managed arthritis but induced severe intestinal damage with increased inflammation and downregulated Nrf2/Sirt1/Foxo3 pathway.

Spatiotemporal pharmacometabolomics based on ambient mass spectrometry imaging to evaluate the metabolism and hepatotoxicity of amiodarone in HepG2 spheroids

Three-dimensional (3D) cell spheroid models combined with mass spectrometry imaging (MSI) enables innovative investigation of in vivo-like biological processes under different physiological and pathological conditions. Herein, airflow-assisted desorption electrospray ionization-MSI (AFADESI-MSI) was coupled with 3D HepG2 spheroids to assess the metabolism and hepatotoxicity of amiodarone (AMI). High-coverage imaging of >1100 endogenous metabolites in hepatocyte spheroids was achieved using AFADESI-MSI. Following AMI treatment at different times, 15 metabolites of AMI involved in N-desethylation, hydroxylation, deiodination, and desaturation metabolic reactions were identified, and according to their spatiotemporal dynamics features, the metabolic pathways of AMI were proposed. Subsequently, the temporal and spatial changes in metabolic disturbance within spheroids caused by drug exposure were obtained via metabolomic analysis. The main dysregulated metabolic pathways included arachidonic acid and glycerophospholipid metabolism, providing considerable evidence for the mechanism of AMI hepatotoxicity. In addition, a biomarker group of eight fatty acids was selected that provided improved indication of cell viability and could characterize the hepatotoxicity of AMI. The combination of AFADESI-MSI and HepG2 spheroids can simultaneously obtain spatiotemporal information for drugs, drug metabolites, and endogenous metabolites after AMI treatment, providing an effective tool for in vitro drug hepatotoxicity evaluation.

Mitochondrial Glrx2 Knockout Augments Acetaminophen-Induced Hepatotoxicity in Mice

Acetaminophen (APAP) is one of the most widely used drugs with antipyretic and analgesic effects, and thus hepatotoxicity from the overdose of APAP becomes one of the most common forms of drug-induced liver injury. The reaction towards thiol molecules, such as GSH by APAP metabolite, N-acetyl-p-benzo-quinonimine (NAPQI), is the main cause of APAP-induced hepatotoxicity. However, the role of many other thiol-related regulators in toxicity caused by APAP is still unclear. Here we have found that knockout of the Glrx2 gene, which encodes mitochondrial glutaredoxin2 (Grx2), sensitized mice to APAP-caused hepatotoxicity. Glrx2 deletion hindered Nrf2-mediated compensatory recovery of thiol-dependent redox systems after acetaminophen challenge, resulting in a more oxidized cellular state with a further decrease in GSH level, thioredoxin reductase activity, and GSH/GSSG ratio. The weakened feedback regulation capacity of the liver led to higher levels of protein glutathionylation and thioredoxin (both Trx1 and Trx2) oxidation in Glrx2^−/− mice. Following the cellular environment oxidation, nuclear translocation of apoptosis-inducing factor (AIF) was elevated in the liver of Glrx2^−/− mice. Taken together, these results demonstrated that mitochondrial Grx2 deficiency deteriorated APAP-induced hepatotoxicity by interrupting thiol-redox compensatory response, enhancing the AIF pathway-mediated oxidative damage.

Protective effects of melatonin and L-carnitine against methotrexate-induced toxicity in isolated rat hepatocytes

The present study was designed to evaluate the possible protective effects of melatonin (MEL) and/or L-carnitine (L-CAR) against methotrexate (MTX)-induced toxicity in isolated rat hepatocytes. Hepatocytes were prepared using collagenase techniques of perfusion and digestion of rat liver. Trypan blue uptake, as well as, glutathione (GSH), lipid peroxidation (LPO), nitric oxide (NO), and tumor necrosis factor-alpha (TNF-α) levels were measured. Caspase-3 activity was also assessed. Pre-incubation of hepatocytes with MEL (1 mM) and/or L-CAR (10 mM) 30 min prior to intoxication with MTX, significantly protected hepatocytes against toxicity. In addition, LPO, NO, TNF-α levels, and caspase-3 activity were decreased in comparison to the MTX-intoxicated group. Furthermore, the two drugs increased the MTX-depleted GSH level. MEL and L-CAR prevented MTX-induced hepatocytotoxicity, at least partly, by their antioxidative, antiinflammatory, and antiapoptotic effects. Further studies are recommended on the clinical pharmacologic and toxicologic effects of MEL and L-CAR in patients receiving MTX.

Molecular toxicity of methotrexate in rheumatoid arthritis treatment: A novel perspective and therapeutic implications

Rheumatoid arthritis (RA) is an autoimmune inflammatory systematic complication which is a chronic disorder that severely affects bones and joints and results in the quality of life impairment. Methotrexate (MTX), an FDA-approved drug has maintained the standard of care for treating patients affected with RA. The mechanism of MTX includes the inhibition of purine and pyrimidine synthesis, suppression of polyamine accumulation, promotion of adenosine release, adhesion of the inflammatory molecules, and controlling of cytokine cascade in RA. The recommended dose for RA patients is 5-25 mg of MTX per week, depending on the severity of the disease but MTX has proven to be cytotoxic with side effects affecting various tissues when treating RA patients even with low doses over a prolonged period of time. The mechanism of such toxicity is not entirely understood. This review strives to understand it by correlating the different pathways, including MTX in folate metabolism, Sirt1/Nrf2/γ-gcs, and γ-gcs/CaSR-TNF-α/NF-kB signaling. In addition to this, the importance of targeted therapy combination with MTX on RA treatment and combinations approved from the clinical trials are also briefly discussed. Overall, this review elucidates the various MTX molecular mechanisms and toxicity at the molecular level, the limitations, and the scope for future directions.

The potential effect of phytochemicals and herbal plant remedies for treating drug-induced hepatotoxicity: a review

Drug-induced liver injury significantly caused by synthetic drugs, and other xenobiotics contribute to clinical hepatic dysfunction, which has been a substantial challenge for both patients and physicians. Traditional medicines used as an alternative therapy because of their pharmacological benefits, less or no side effects, and enormous availability in nature. Phytochemicals are essential ingredients of plants that reduce necrotic cell death, restore the antioxidant defence mechanism, limit oxidative stress, and prevent the inflammation of tissue and dysfunction of the mitochondria. In this review, we principally focused on the potential effect of the herbal plants and their phytochemicals in treating drug-induced hepatotoxicity.