Effects of a new 1,2,3-thiadiazole containing hydrazone antimycobacterial agent on serum and liver biochemical parameters in female mice

Isoniazid (INH), a first-line drug in anti-tuberculosis therapy, is known to be potentially harmful and is associated with numerous side effects especially in the blood and liver. In the course of our previous investigations, 1,2,3-thiadiazole containing hydrazone (compound 3) showed excellent antimycobacterial activity against a referent strain M. tuberculosis H37Rv (MIC value 0.39 μM), low cytotoxicity, and did not have toxic effects when administered by oral or intraperitoneal routes to experimental animals (selectivity index SI > 1979, LD₅₀>2000 mg/kg b.w.) what revealed its suitability for further exploration. In the present study compound 3 was chosen to determine its effects on the liver and kidney functions in female mice. The compound was administered orally for 14 days at three doses (100, 200, and 400 mg/kg b.w.). The quantity of malondialdehyde (MDA), the level of reduced glutathione (GSH), blood hematological and biochemical parameters were assessed, and urine analysis was carried out. As a positive control INH was used orally at a dose of 50 mg/kg b.w. The investigated compound 3 did not affect the urine and serum hematological and biochemical parameters as INH did, compared to those of the control mice. The new compound did not affect significantly the MDA quantity and maintained its level near to the control values, though lower by 36% (p < 0.05) than in the INH treated animals. At the higher doses, 200 and 400 mg/kg, it depleted the GSH content by 25% (p < 0.05), compared to the control. However, its level remained 47% (p < 0.05) higher than in the INH treated animals.

The antineoplastic agent anacardic 6-pentadecyl salicylic acid produces immunomodulation in vivo via the activation of MAPKs

Anacardic 6-pentadecyl salicylic acid (6SA) is the active component of Amphipterygium adstringens, a plant used in traditional medicine for the treatment of malaria and vascular diseases and as an anti-bacterial and immune-modulatory agent. However, the effect of 6SA on the immune system remains unclear. In this study, we examined the immune-stimulatory activity of 6SA in 6-8-week-old female BALB/c mice. We found that treatment with 2 mg/kg of 6SA increased the proportions of macrophages after 7 and 14 days of treatment and of natural killer (NK) cells after 14 days of treatment in circulating blood. In lymph nodes, treatment with 6SA for 14 days increased the number of macrophages. In addition, 6SA increases in the systemic levels of pro-inflammatory cytokines such as tumour necrosis factor (TNF)-α, interleukin (IL)-2, IL-12, IL-6 and IL-1β and of nitric oxide (NO). We observed an increase in the secretion of Granulocyte/Macrophage Colony Stimulation Factor (GM-CSF) that could explain the increase in the proportion of macrophages. Moreover, 6SA induced the classical activation of macrophages by increasing their expression of MHC-II and their production of TNF-α. These M1-polarised macrophages presented enhanced phagocytosis and NO secretion. This activation was due to induction of the phosphorylation of MAPKs such as ERK, JNK and p38 because specific inhibitors of the phosphorylation of these MAPKs reduced the 6SA-induced phagocytosis and NO and particularly, the secretion of GM-CSF in macrophages by inhibition of ERK. Despite these effects on macrophages, 6SA does not have any direct effect on the proportion of lymphocytes.

Genetic Variations Associated with Anti-Tuberculosis Drug-Induced Liver Injury

Purpose of this Review

In order to combat the development of drug resistance, the clinical treatment of tuberculosis requires the combined use of several anti-tuberculosis (anti-TB) drugs, including isoniazid and rifampicin. Combinational treatment approaches are suggested by the World Health Organization (WHO) and are widely accepted throughout the world. Unfortunately, a major side effect of the treatment is the development of anti-tuberculosis drug-induced liver injury (AT-DILI). Many factors contribute to isoniazid- and rifampicin-mediated AT-DILI and genetic variations are among the most common factors. The purpose of this review is to provide information on genetic variations associated with isoniazid- and rifampicin-mediated AT-DILI.

Recent Findings

The genetic variations associated with AT-DILI have been identified in the genomic regions within or near genes encoding proteins in the following pathways: drug metabolizing enzymes (NAT2, CYP2E1, and GSTs), accumulation of bile acids, lipids, and heme metabolites (CYP7A1, BSEP, UGTs, and PXR), immune adaptation (HLAs and TNF-α), and oxidant challenge (TXNRD1, SOD1, BACH1, and MAFK).

Summary

The information summarized in this review considers the genetic bases of risk factors contributing to AT-DILI and provides information that may help for future studies. Some of the implicated genetic variations can be used in the design of genetic tests and serve as biomarkers for the prediction of isoniazid- and rifampicin-mediated AT-DILI risk in personalized medicine.

Mechanism of isoniazid-induced hepatotoxicity: then and now

Isoniazid (INH) remains a mainstay for the treatment of tuberculosis despite the fact that it can cause liver failure. Previous mechanistic hypotheses have classified this type of drug-induced liver injury (DILI) as 'metabolic idiosyncrasy' which was thought not to involve an immune response and was mainly due to the bioactivation of the acetylhydrazine metabolite. However, more recent studies support an alternative hypothesis, specifically, that INH itself is directly bioactivated to a reactive metabolite, which in some patients leads to an immune response and liver injury. Furthermore, there appear to be two phenotypes of INH-induced liver injury. Most cases involve mild liver injury, which resolves with immune tolerance, while other cases appear to have a more severe phenotype that is associated with the production of anti-drug/anti-CYP P450 antibodies and can progress to liver failure.

The Combination of Anti-CTLA-4 and PD1-/- Mice Unmasks the Potential of Isoniazid and Nevirapine To Cause Liver Injury

Our laboratory recently reported what we believe is the first valid animal model of idiosyncratic drug-induced liver injury (IDILI) by treating PD1-/- mice with an anti-CTLA-4 antibody and amodiaquine (AQ). PD1 and CTLA-4 are important immune checkpoint receptors that are involved in inducing immune tolerance. This model was able to produce significant liver injury that looks very similar to the liver injury seen in humans. Although this model was shown to work with AQ, the question becomes whether blocking immune tolerance would unmask the potential of other drugs to cause IDILI. In this study, we tested isoniazid and nevirapine, both drugs with significant histories of causing IDILI in humans even though they do not cause significant injury in animals with doses that result in therapeutic blood levels. Both drugs in combination with these immune checkpoint inhibitors caused mild but significant delayed onset liver injury, which is similar to the mild injury that they can cause in humans. INH-induced liver injury in this model was associated with an increase in NK cells, while NVP-induced liver injury was associated with a greater increase in CD8 T cells. Although the liver injury caused by these drugs in this model was mild, these results suggest that impairing immune tolerance may be a general method for unmasking the potential of drugs to cause IDILI and therefore provide a screening tool for drug development.

Xenobiotic and Endobiotic Mediated Interactions Between the Cytochrome P450 System and the Inflammatory Response in the Liver

The liver is a unique organ in the body as it has significant roles in both metabolism and innate immune clearance. Hepatocytes in the liver carry a nearly complete complement of drug metabolizing enzymes, including numerous cytochrome P450s. While a majority of these enzymes effectively detoxify xenobiotics, or metabolize endobiotics, a subportion of these reactions result in accumulation of metabolites that can cause either direct liver injury or indirect liver injury through activation of inflammation. The liver also contains multiple populations of innate immune cells including the resident macrophages (Kupffer cells), a relatively large number of natural killer cells, and blood-derived neutrophils. While these cells are primarily responsible for clearance of pathogens, activation of these immune cells can result in significant tissue injury during periods of inflammation. When activated chronically, these inflammatory bouts can lead to fibrosis, cirrhosis, cancer, or death. This chapter will focus on interactions between how the liver processes xenobiotic and endobiotic compounds through the cytochrome P450 system, and how these processes can result in a response from the innate immune cells of the liver. A number of different clinically relevant diseases, as well as experimental models, are currently available to study mechanisms related to the interplay of innate immunity and cytochrome P450-mediated metabolism. A major focus of the chapter will be to evaluate currently understood mechanisms in the context of these diseases, as a way of outlining mechanisms that dictate the interactions between the P450 system and innate immunity.