Risk Prediction Model for Isoniazid Dosing in Tuberculosis Meningitis Patients in Southwest China

Purpose

Tuberculosis meningitis (TBM) has emerged as the most lethal type of disease. The prognosis of meningitis is often related to disease severity and early therapeutic intervention.

Methods

Patients were screened for primary TBM and received a quadruple regimen comprising isoniazid (standard dose of 300 mg/day and high dose of 600 mg/day), rifampin, ethambutol, and pyrazinamide. Further, the indices and prognosis factors of diseased patients were analyzed, using 12-month treatment mortality as the primary observation endpoint. Several predictors included demographic data, clinical presentation, ancillary tests, treatment changes, and isoniazid dose. The data were analyzed using a least absolute shrinkage, the selection operator regression, and multi-factor logistic regression.

Results

Among the selected TBM patients (n=119), 18 patients were dead at the end of December. A total of 68 influencing factors were screened, in which 5 clinical factors were included as potential prognostic factors, including older age, presence of nausea, high MRC grade, imaging suggestive of cerebral infarction, and dose of isoniazid (300 mg/day). The AUC value was recorded as 0.8316832. The validation set confirmed the model's robustness, with an AUC of 0.887 and good calibration performance. These findings highlight the model's potential for clinical application in optimizing isoniazid dosing. The model demonstrated the advantage of predicting the therapeutic outcome of patients.

Conclusion

In summary, the model could be suitable for evaluating the risk of death within 12 months in TBM patients towards assessing the severity and treatment needs of patients. The isoniazid dose is an important factor affecting the prognosis of these patients.

Herbo-vitamin medicine Livogrit Vital ameliorates isoniazid induced liver injury (IILI) in human liver (HepG2) cells by decreasing isoniazid accumulation and oxidative stress driven hepatotoxicity

BACKGROUND

Tuberculosis (TB) is a leading cause of infection related mortality. Isoniazid is one of the frontline drugs for anti-TB therapy. Hepatotoxicity induced by isoniazid is a major cause of drug-discontinuation which may lead to development of resistant TB or increased mortality.

PURPOSE

To characterize pharmacological properties of plant-based prescription medicine, Livogrit Vital (LVV) against isoniazid-induced liver injury (IILI) using HepG2 cells.

METHOD

Phytometabolite characterization of LVV was performed by High-performance liquid chromatography (HPLC). The effects of LVV on cytosafety, IC50 shift, oxidative stress, ER stress, apoptosis, liver injury markers, and accumulation of isoniazid and hydrazine was performed on HepG2 cells induced with isoniazid. Silymarin was used as the positive control.

RESULTS

HPLC based phytometabolite characterization of LVV revealed the presence of several anti-oxidant, anti-apoptotic, and hepatoprotective compounds. In isoniazid-induced HepG2 cells, LVV reduced cytotoxicity of isoniazid and shifted its IC50 value. Treatment with LVV reduced ROS generation and lipid peroxidation; enhanced GSH enzyme levels in isoniazid-induced HepG2 cells. As per the mechanistic evaluation, LVV modulated gene expression level of Caspase-3, FGF21, and IRE-1α. LVV treatment also normalized isoniazid-induced elevated Caspase-3 activity and cPARP1 protein levels, indicating its potentials to regulate liver cell apoptosis. Concomitantly, biomarkers of hepatotoxicity, ALT and GGT, also decreased by LVV treatment. Interestingly, LVV treatment reduced intracellular accumulation of isoniazid and its toxic metabolite hydrazine, in isoniazid-stimulated HepG2 cells.

CONCLUSION

Treatment of hepatic cells with the herbo-vitamin medicine, Livogrit Vital, regulates IILI by modulation of oxidative and ER stress, apoptosis, and bioaccumulation of isoniazid and hydrazine. Collectively, Livogrit Vital could well be explored as an adjuvant hepatoprotective agent alongwith anti-TB medicines.

Research progress on rodent models and its mechanisms of liver injury

The liver is the most important organ for biological transformation in the body and is crucial for maintaining the body's vital activities. Liver injury is a serious pathological condition that is commonly found in many liver diseases. It has a high incidence rate, is difficult to cure, and is prone to recurrence. Liver injury can cause serious harm to the body, ranging from mild to severe fatty liver disease. If the condition continues to worsen, it can lead to liver fibrosis and cirrhosis, ultimately resulting in liver failure or liver cancer, which can seriously endanger human life and health. Therefore, establishing an rodent model that mimics the pathogenesis and severity of clinical liver injury is of great significance for better understanding the pathogenesis of liver injury patients and developing more effective clinical treatment methods. The author of this article summarizes common chemical liver injury models, immune liver injury models, alcoholic liver injury models, drug-induced liver injury models, and systematically elaborates on the modeling methods, mechanisms of action, pathways of action, and advantages or disadvantages of each type of model. The aim of this study is to establish reliable rodent models for researchers to use in exploring anti-liver injury and hepatoprotective drugs. By creating more accurate theoretical frameworks, we hope to provide new insights into the treatment of clinical liver injury diseases.

A near-infrared fluorescent probe for detecting hydrazine metabolized from isoniazid in living cells

Isoniazid is a drug for treating tuberculosis, but hydrazine (N2 H4 ), the major metabolite of isoniazid, can cause hepatotoxicity. Therefore, monitoring the content of N2 H4 in time is of great significance for studying the hepatotoxicity induced by isoniazid. In this study, a near-infrared fluorescent probe (BC-N) was designed and synthesized based on the specific reaction of acetyl ester with N2 H4 . BC-N exhibits excellent selectivity, sensitivity, and biocompatibility. In addition, BC-N is applied in the visualization of N2 H4 produced from isoniazid in living cells and is a potential tool for monitoring hepatotoxicity induced by isoniazid.

Evaluation of Acute and Sub-Acute Toxicity, Oxidative Stress and Molecular Docking of Two Nitrofuranyl Amides as Promising Anti-Tuberculosis Agents

Tuberculosis (TB) remains a widespread infectious disease and one of the top 10 causes of death worldwide. Nevertheless, despite significant advances in the development of new drugs against tuberculosis, many therapies and preventive measures do not lead to the expected favorable health results for various reasons. The aim of this study was to evaluate the acute and sub-acute toxicity and oxidative stress of two selected nitrofuranyl amides with high in vitro antimycobacterial activity. In addition, molecular docking studies were performed on both compounds to elucidate the possibilities for further development of new anti-tuberculosis candidates with improved efficacy, selectivity, and pharmacological parameters. Acute toxicity tests showed that no changes were observed in the skin, coat, eyes, mucous membranes, secretions, and vegetative activity in mice. The histological findings include features consistent with normal histological architecture without being associated with concomitant pathological conditions. The observed oxidative stress markers indicated that the studied compounds disturbed the oxidative balance in the mouse liver. Based on the molecular docking, compound DO-190 showed preferable binding energies compared to DO-209 in three out of four targets, while both compounds showed promising protein-ligand interactions. Thus, both studied compounds displayed promising activity with low toxicity and can be considered for further evaluation and/or lead optimization.

Molecular mechanism for the activation of the potent hepatotoxin acetylhydrazine: Identification of the initial N-centered radical and the secondary C-centered radical intermediates

Acetylhydrazine (AcHZ), a major human metabolite of the widely-used anti-tuberculosis drug isoniazid (INH), was considered to be responsible for its serious hepatotoxicity and potentially fatal liver injury. It has been proposed that reactive radical species produced from further metabolic activation of AcHZ might be responsible for its hepatotoxicity. However, the exact nature of such radical species remains not clear. Through complementary applications of ESR spin-trapping and HPLC/MS methods, here we show that the initial N-centered radical intermediate can be detected and identified from AcHZ activated by transition metal ions (Mn(III)Acetate and Mn(III) pyrophosphate) and myeloperoxidase. The exact location of the radical was found to be at the distal-nitrogen of the hydrazine group by ¹⁵N-isotope-labeling techniques via using ¹⁵N-labeled AcHZ we synthesized. Additionally, the secondary C-centered radical was identified unequivocally as the reactive acetyl radical by complementary applications of ESR spin-trapping and persistent radical TEMPO trapping coupled with HPLC/MS analysis. This study represents the first detection and unequivocal identification of the initial N-centered radical and its exact location, as well as the reactive secondary acetyl radical. These findings should provide new perspectives on the molecular mechanism of AcHZ activation, which may have potential biomedical and toxicological significance for future research on the mechanism of INH-induced hepatotoxicity.

Molecular mechanism for the involvement of CYP2E1/NF-κB axis in bedaquiline-induced hepatotoxicity

Bedaquiline (BDQ) is a new class of anti-tubercular (anti-TB) drugs and is currently reserved for multiple drug resistance (MDR-TB). However, after receiving fast-track approval, its clinical studies demonstrate that its treatment is associated with hepatotoxicity and labeled as 'boxed warning' by the USFDA. No data is available on BDQ to understand the mechanism for drug-induced liver injury (DILI), a severe concern for therapeutic failure/unbearable tolerated toxicities leading to drug resistance. Therefore, we performed mechanistic studies to decipher the potential of BDQ at three dose levels (80 to 320 mg/kg) upon the repeated dose administration orally using a widely used mice model for TB. Results of BDQ treatment at the highest dose level showed that substantial increase of hepatic marker enzymes (SGPT and SGOT) in serum, oxidative stress marker levels (MDA and GSH) in hepatic tissue, and pro-inflammatory cytokine levels (TNF-α, IL-6, and IL-1β) in serum compared to control animals. Induction of liver injury situation was further evaluated by Western blotting for various protein expressions linked to oxidative stress (SOD, Nrf2, and Keap1), inflammation (NF-ĸB and IKKβ), apoptosis (BAX, Bcl-2, and Caspase-3) and drug metabolism enzymes (CYP3A4 and CYP2E1). The elevated plasma level of BDQ and its metabolite (N-desmethyl BDQ) were observed, corresponding to BDQ doses. Histopathological examination and SEM analysis of the liver tissue corroborate the above-mentioned findings. Overall results suggest that BDQ treatment-associated generation of its cytotoxic metabolite could act on CYP2E1/NF-kB pathway to aggravate the condition of oxidative stress, inflammation, and apoptosis in the liver and precipitating hepatotoxicity.

Amelioration of Nephrotoxicity in Mice Induced by Antituberculosis Drugs Using Ensete ventricosum (Welw.) Cheesman Corm Extract

Background

Antituberculosis drugs are antimicrobial agents important for treating a communicable disease called tuberculosis. Despite their importance, antituberculosis drugs such as isoniazid and rifampicin have severe adverse effects like nephrotoxicity with acute renal failures. Ensete ventricosum (Welw.) Cheesman is a nutritional herbaceous perennial plant, and it has indigenous ethnomedicinal values for the society. This study aimed to evaluate the protective role of the Ensete ventricosum (Welw.) Cheesman corm extract (EVCE) against nephrotoxicity induced by isoniazid and rifampicin in mice.

Methods

The present study was conducted on thirty Swiss albino mice randomly allocated into five groups. Group-I (only distilled water), Group-II (only isoniazid 75 mg/kg and rifampicin150 mg/kg), Group-III (isoniazid and rifampicin along with 200 mg/kg EVCE), Group-IV (isoniazid and rifampicin along with 400 mg/kg EVCE), and Group-V (isoniazid and rifampicin along with silymarin) were treated for thirty days. At the end of the study, the experimental animals were sacrificed after being injected with anesthetic drug, blood was drawn for a kidney function test, and the kidney was also taken from each experimental animal for histopathological evaluation. Data were entered and analyzed by using one-way ANOVA of SPSS version 25. Results and Conclusion. Serum levels of creatinine, blood urea nitrogen (BUN), and uric acid of the Group-II mice were significantly (P < 0.01) elevated, and serum levels of total proteins and albumin of Group-II mice were significantly (P < 0.01) decreased as compared to Group-I. The group of mice treated with an EVCE reinstated those derangements. The kidney section of Group-II mice showed an abnormality in kidney structure; however, these deformities were not detectable in group-IV mice. The EVCE has sufficient nephroprotective potential against antituberculosis drug-induced kidney injury.

A HepG2 Cell-Based Biosensor That Uses Stainless Steel Electrodes for Hepatotoxin Detection

Humans are frequently exposed to environmental hepatotoxins, which can lead to liver failure. Biosensors may be the best candidate for the detection of hepatotoxins because of their high sensitivity and specificity, convenience, time-saving, low cost, and extremely low detection limit. To investigate suitability of HepG2 cells for biosensor use, different methods of adhesion on stainless steel surfaces were investigated, with three groups of experiments performed in vitro. Cytotoxicity assays, which include the resazurin assay, the neutral red assay (NR), and the Coomassie Brilliant Blue (CBB) assay, were used to determine the viability of HepG2 cells exposed to various concentrations of aflatoxin B1 (AFB1) and isoniazid (INH) in parallel. The viability of the HepG2 cells on the stainless steel surface was quantitatively and qualitatively examined with different microscopy techniques. A simple cell-based electrochemical biosensor was developed by evaluating the viability of the HepG2 cells on the stainless steel surface when exposed to various concentrations of AFB1 and INH by using electrochemical impedance spectroscopy (EIS). The results showed that HepG2 cells can adhere to the metal surface and could be used as part of the biosensor to determine simple hepatotoxic samples.

Generation of a Transgenic Zebrafish Line for In Vivo Assessment of Hepatic Apoptosis

Hepatic apoptosis is involved in a variety of pathophysiologic conditions in the liver, including hepatitis, steatosis, and drug-induced liver injury. The development of easy-to-perform and reliable in vivo assays would thus greatly enhance the efforts to understand liver diseases and identify associated genes and potential drugs. In this study, we developed a transgenic zebrafish line that was suitable for the assessment of caspase 3 activity in the liver by using in vivo fluorescence imaging. The larvae of transgenic zebrafish dominantly expressed Casper3GR in the liver under control of the promoter of the phosphoenolpyruvate carboxykinase 1 gene. Casper3GR is composed of two fluorescent proteins, tagGFP and tagRFP, which are connected via a peptide linker that can be cleaved by activated caspase 3. Under tagGFP excitation conditions in zebrafish that were exposed to the well-characterized hepatotoxicant isoniazid, we detected increased and decreased fluorescence associated with tagGFP and tagRFP, respectively. This result suggests that isoniazid activates caspase 3 in the zebrafish liver, which digests the linker between tagGFP and tagRFP, resulting in a reduction in the Förster resonance energy transfer to tagRFP upon tagGFP excitation. We also detected isoniazid-induced inhibition of caspase 3 activity in zebrafish that were treated with the hepatoprotectants ursodeoxycholic acid and obeticholic acid. The transgenic zebrafish that were developed in this study could be a powerful tool for identifying both hepatotoxic and hepatoprotective drugs, as well as for analyzing the effects of the genes of interest to hepatic apoptosis.

Difficulties in Diagnosing and Treating Disseminated Bacillus Calmette-Guérin (BCG) Infection After Intravesical BCG Therapy in a Patient with Liver Cirrhosis: A Case Report

Patient: Male, 62-year-old

Final Diagnosis: BCGitis

Symptoms: Fever • general fatigue

Medication: —

Clinical Procedure: Bone marrow biopsy • liver biopsy

Specialty: Infectious Diseases • General and Internal Medicine

Serum biomarkers of isoniazid-induced liver injury: Aminotransferases are insufficient, and OPN, L-FABP and HMGB1 can be promising novel biomarkers

Isoniazid (INH)-induced liver injury is a great challenge for tuberculosis treatment. Existing biomarkers cannot accurately determine the occurrence of this injury in the early stage. Therefore, developing early specific sensitive biomarkers of INH-induced liver injury is urgent. A rat model of liver injury was established with gastric infusion of INH or INH plus rifampicin (RFP). We examined seven potential novel serum biomarkers, namely, glutamate dehydrogenase (GLDH), liver-fatty acid-binding protein (L-FABP), high-mobility group box-1 (HMGB1), macrophage colony-stimulating factor receptor (MCSF1R), osteopontin (OPN), total cytokeratin 18 (K18), and caspase-cleaved cytokeratin-18 (ccK18), to evaluate their sensitivity and specificity on INH-induced liver injury. With the increase of drug dosage, combining with RFP and prolonging duration of administration, the liver injury was aggravated, showing as decreased weight of the rats, upgraded liver index and oxidative stress level, and histopathological changes of liver becoming marked. But the activity of serum aminotransferases decreased significantly. The area under the curve (AUC) of receiver-operating characteristic (ROC) curve of OPN, L-FABP, HMGB1, MCSF1R, and GLDH was 0.88, 0.87, 0.85, 0.71, and 0.70 (≥0.7), respectively, and 95% confidence interval of them did not include 0.5, with statistical significance, indicating their potential abilities to become biomarkers of INH-induced liver injury. In conclusion, we found traditional biomarkers ALT and AST were insufficient to discover the INH-induced liver injury accurately and OPN, L-FABP, and HMGB1 can be promising novel biomarkers.

Activatable photoacoustic/fluorescent dual-modal probe for monitoring of drug-induced liver hypoxia in vivo

Effective monitoring of liver hypoxia status is crucial for the detection and treatment of drug-induced liver injury. Here, a novel photoacoustic and fluorescent dual-modal probe (NO2-CS) was rationally developed and applied to image isoniazid-induced liver hypoxia through detecting the over-expressed nitroreductase.

Histological and histochemical changes in the peripheral organs of the immune system of dogs in cases of isoniazid poisoning

Most publications on isoniazid poisoning in dogs are devoted to clinical diagnostics, treatment, and prevention of the disease. Histological and histochemical changes are not fully described, though they are important in assessing the toxic effects of isoniazid. Isoniazid is used to treat tuberculosis in humans. Dogs are hypersensitive to this drug. The article highlights the results of macroscopic, histological, and histochemical studies of the dogs’ lymph nodes and spleen in cases of isoniazid poisoning. A pathological examination of 19 corpses of dogs of different ages was performed, during which isoniazid poisoning was posthumously diagnosed, based on anamnesis, clinical signs, pathological autopsy, histological, and histochemical examination. Samples of lymph nodes and spleen were fixed in a 10% aqueous neutral formalin solution, Carnoy’s solution, and Bouin’s fixative. Histoсuts were prepared using a sled microtome and stained with hematoxylin and eosin. Staining was also performed according to the techniques suggested by McManus, Brachet, and Perls. The pathomorphological changes in lymph nodes and spleen were characterized by disorganization of vascular walls and connective tissue fibers of the stroma, dilatation of veins, their overflow with hemolyzed blood, and, in cases of the long clinical course, thrombosis of small vessels. Intravascular hemolysis of erythrocytes resulted in an excessive formation of hemosiderin. Histochemically, the spleen and lymph nodes showed a significant increase in the number of hemosiderophages in the spleen’s red and white pulp and the lymph nodes’ central sinuses and pulp cords. In the spleen, mucoid swelling and necrobiotic changes in the wall structures of the arterioles and arteries progressed with a narrowing of their lumen in dogs suffering from the long clinical course. Increased permeability of the microcirculatory tract vessels of the spleen and lymph nodes, transudate formation, and the destructive changes in the reticular skeleton accompanied hemodynamic violations. A sharp change in blood rheology caused the violation of trophism and metabolism in the immune system. Lymphoid elements of the lymph nodes and white pulp of the spleen were in a state of karyorrhexis and karyolysis. The morphological study of the immune system’s peripheral organs suggests that dogs poisoned by isoniazid demonstrate hemodynamic disorders, changes in the physicochemical properties of blood (hemolysis of erythrocytes and thrombosis). This is the basis of trophic disorders, metabolic malfunctions, and the development of dystrophic processes in all structural elements of the spleen and lymph nodes.

Lagerstroemia speciosa (L.) Pers., ethanolic extract attenuates simultaneously administered isoniazid- and dapsone-induced hepatotoxicity in rats

Herbal tea of Lagerstroemia speciosa Pers., commonly known as banaba, has been traditionally used to treat various ailments including diabetes and obesity due to its antioxidant and anti-inflammatory efficacies. Drug-induced liver injury is a common cause of acute liver failure. Isoniazid (INH) is used as the first-line treatment for tuberculosis; clinical and experimental studies have reported an abnormal liver function after INH therapy. Dapsone (DDS) is used for leprosy and other infections. This study investigates the hepatoprotective effect of ethanolic banaba leaves extract (EBLE) against simultaneously administered INH- and DDS-induced hepatotoxicity in rats. DDS (30 mg/kg, i.p.) and INH (50 mg/kg. p.o.) were administered simultaneously for 30 days. In separate groups, rats were posttreated orally with EBLE (500 mg/kg) and silymarin (100 mg/kg) for 30 days after INH + DDS administration. The marker enzymes of hepatotoxicity, oxidative stress markers, inflammatory markers, and histopathology were done. Simultaneous administration of INH- and DDS-induced significant elevation of marker enzymes of hepatotoxicity in the serum. This treatment also increased lipid peroxidation and pro-inflammatory markers (tumor necrosis factor alpha, transforming growth factor beta, and nuclear factor kappa B) expressions and decreased intracellular antioxidants such as superoxide dismutase, catalase, and glutathione in the liver tissue. All these abnormalities were significantly mitigated after EBLE and SIL posttreatments. The results of this study suggest that EBLE and silymarin can be protective against INH + DDS-induced hepatotoxicity. PRACTICAL APPLICATIONS: Herbal tea contain Lagerstroemia speciosa leaves are used in several Southeast Asian countries due to its rich antioxidant and inflammatory properties. This study showed the hepatoprotective efficacy of L. speciosa ethanolic extract against simultaneously administered dapsone- and isoniazid-induced hepatotoxicity in rats. L. speciosa administration was found to decrease dapsone- and isoniazid-induced oxidative stress and hepatic inflammation. L. speciosa herbal tea can reduce drug-induced hepatic complications as it contains phytochemicals such as corosolic acid, gallic acid, ellagic acid and berberine and are implicated for its hepatoprotective effect. Therefore, L. speciosa extract can be used for drug-induced liver injury.

Ameliorative potential of Adhatoda vasica against anti-tubercular drugs induced hepatic impairments in female Wistar rats in relation to oxidative stress and xeno-metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Adhatoda vasica Nees is widely used herb of indigenous system to treat various ailments especially upper respiratory tract infections. Not only, anti-tubercular efficacy of crude extract and phytoconstituents of A. vasica has been documented but its hepatoprotective role against various drugs mediated hepatic alterations in different animal models has also been observed.

BACKGROUND AND PURPOSE

Isoniazid, rifampicin and pyrazinamide (H-R-Z) are anti-tubercular drugs normally prescribed by health professionals for the treatment of tuberculosis, however along with their medical effectiveness these drugs also exhibit hepatotoxicity among TB patients. Unexpectedly, substantial toxicological data on the metabolism of anti-TB drugs are available but the mystery behind these xenobiotics is too complex and partly implicit. In this study, we further explored the hepatotoxic effects of these xeno-metabolic products and their amelioration by Adhatoda vasica Nees by elucidating its mechanistic action.

METHODS

We generated a hepatotoxic rodent model by oral administration of H, R and Z (30.85, 61.7 and 132.65 mg/kg body weight) drugs for 25 days in Wistar rats. Additionally, to achieve hepatoprotection two different doses of Adhatoda vasica Nees ethanolic leaf extract (200 and 300 mg/kg body weight) were used along with H-R-Z dosage, orally and once daily for 25 days and tried to ascertain their mechanistic action. For this, initially phytoconstituents of the extract were evaluated followed by extract standardization using RP-HPLC and FTIR methods. Furthermore, antioxidant activity of the extract was analyzed by DPPH assay. Finally, different treated groups were analyzed for hepatic oxidative stress markers, antioxidant markers, histopathological changes and gene expression study including CYP2E1, CYP7A1, NAT, NR1I2 and UGT1A1 genes involved in phase I and phase II xeno-metabolism.

RESULTS

Estimated content of vasicine in RP-HPLC method and free-radical scavenging activity in DPPH assay was found to be 134.519 ± 0.00269μg/10mg of leaf extract and 47.81 μg/mL respectively. In H-R-Z treated group, a significant increase in the levels of thiobarbituric acid, significant reduction in the levels of GSH, and enzymatic markers and marked changes in hepatic histological architecture were observed. In addition, there was significance up-regulation of CYP7A and NAT genes, down-regulation of CYP2E1 gene and insignificant expression levels of NR1I2 and UGT1A1 genes were observed in H-R-Z group. Conversely, high dose of A. vasica extract effectively diminished these alterations by declining oxidative stress and boosting of antioxidant levels. In addition, it acted as bi-functional inducer of both phase I (CYP2E1) and phase II (NAT and UGT1A1) enzyme systems.

CONCLUSION

Hence, we concluded that anti-TB drugs exposure has potential to generate reactive metabolites that eventually cause hepatotoxicity by altering oxidant-antioxidant levels and their own metabolism. This study not only emphasized on xeno-metabolism mediated hepatic alterations but also explore the benefit of A. vasica on these toxic insults.

Formulation and Pharmacological Studies of Leaves of Moringa (Moringa oleifera), a Novel Hepatoprotection in Oral Drug Formulations

BACKGROUND: Moringa oleifera, Moringaceae, is a tree that is native to South East Asia. Various parts of this tree are commonly used in traditional medicine to treat inflammation, hepatitis, gastric ulcer, and other ailments. AIM: M. oleifera leaves extract was formulated into stable suspensions, characterized, and then evaluated for hepatoprotection activity against isoniazid. MATERIALS AND METHODS: The leaves were extracted using cold maceration, and suspensions of extract were prepared using sodium carboxymethyl cellulose (Na-CMC) as suspension agent at various concentrations (0.1, 0.5, and 1.0%). The formulations were analyzed by their appearance, color, odor, and taste. Density, pH, viscosity, re-dispersibility test, and sedimentation volume were observed. The stability of oral suspensions was analyzed in accelerated studies (5°C ± 2°C and 35°C ± 2°C for 12 h for 7 cycles) to find stable formulation, while the hepatoprotection activity was analyzed using an in vivo isoniazid-induced model. RESULTS: The appearance, color, odor, and taste of the suspensions were shown to be characteristic of the extract. Na-CMC at concentration 0.5% showed good physical properties. Stable suspension at dose 400 mg/kg BW per oral for 28 days exhibited a significant (p < 0.05) decrease in the serum glutamate oxaloacetate transaminase and serum glutamate pyruvate transaminase. CONCLUSION: Suspension containing M. oleifera leaves extract at 50 mg/5 mL was successfully obtained and showed physical properties that were appropriate and characteristic of this dosage form, suitable for hepatoprotection (400 mg/kg BW), making this an alternative to tablets.

MicroRNA-122 and cytokeratin-18 have potential as a biomarkers of drug-induced liver injury in European and African patients on treatment for mycobacterial infection

Aims

Patients on antituberculosis (anti‐TB) therapy are at risk of drug‐induced liver injury (DILI). MicroRNA‐122 (miR‐122) and cytokeratin‐18 (K18) are DILI biomarkers. To explore their utility in this global context, circulating miR‐122 and K18 were measured in UK and Ugandan populations on anti‐TB therapy for mycobacterial infection.

Methods

Healthy subjects and patients receiving anti‐TB therapy were recruited at the Royal Infirmary of Edinburgh, UK (ALISTER—ClinicalTrials.gov Identifier: NCT03211208). African patients with human immunodeficiency virus–TB coinfection were recruited at the Infectious Diseases Institute, Kampala, Uganda (SAEFRIF—NCT03982277). Serial blood samples, demographic and clinical data were collected. In ALISTER samples, MiR‐122 was quantified using polymerase chain reaction. In ALISTER and SAEFRIF samples, K18 was quantified by enzyme‐linked immunosorbent assay.

Results

The study had 235 participants (healthy volunteers [n = 28]; ALISTER: active TB [n = 30], latent TB [n = 88], nontuberculous mycobacterial infection [n = 25]; SAEFRIF: human immunodeficiency virus‐TB coinfection [n = 64]). In the absence of DILI, there was no difference in miR‐122 and K18 across the groups. Both miR‐122 and K18 correlated with alanine transaminase (ALT) activity (miR‐122: R = .52, 95%CI = 0.42–0.61, P < .0001. K18: R =0.42, 95%CI = 0.34–0.49, P < .0001). miR‐122 distinguished those patients with ALT>50 U/L with higher sensitivity/specificity than K18. There were 2 DILI cases: baseline ALT, 18 and 28 IU/L, peak ALT 431 and 194 IU/L; baseline K18, 58 and 219 U/L, peak K18 1247 and 3490 U/L; baseline miR‐122 4 and 17 fM, peak miR‐122 60 and 336 fM, respectively.

Conclusion

In patients treated with anti‐TB therapy, miR‐122 and K18 correlated with ALT and increased with DILI. Further work should determine their diagnostic and prognostic utility in this global context‐of‐use.

Tylophora indica (Burm. f.) merr: An insight into phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Tylophora indica (Burm. f.) Merr. commonly known as ananthamool is a climbing perennial plant which is widely used in Indian traditional medicine. T. indica exhibits diverse range of pharmacological activities viz. antiasthmatic, antidiarrheal, anticancer, antiarthritic, antiepileptic, anti-inflammatory etc. AIM OF THE STUDY: Present review aims to grant an up-to-date insight into the botany, ethnopharmacology, phytochemistry, pharmacology and toxicology of T. indica, exploring its future research and opportunities.

MATERIAL AND METHODS

Comprehensive information regarding T. indica was collected using the keywords Tylophora indica or Indian ipecac or ananthamool in various electronic databases ACS, Google Scholar, Pubmed, Science Direct, SciFinder, Web of Science, Springer Link and Wiley. In addition, some books and book chapters were also consulted.

RESULTS

T. indica has been traditionally used in India, Bangladesh and Sri Lanka in the form of various preparations like powder, decoction, pulp, paste and extract alone or in combination with other herbs against various ailments like skin disorders, inflammation, cough, asthma, diarrhea, cancer, microbial infections etc. In vitro and in vivo pharmacological studies on T. indica revealed its potential as antiasthmatic, antiallergic, anti-inflammatory, anticancer, antimicrobial, antioxidant, antidiarrheal agent etc. A diverse range of phytochemical constituents have been isolated and identified from T. indica namely alkaloids (Tylophorine, Tylophorinine, Tylophorinidine), flavonoids (Kaempferol & Quercetin) terpenoids (α-Amyrin & β-Amyrin) and sterols (β-sitosetrol). Amongst which phenanthroindolizidine alkaloids isolated from roots and leaves are largely explored and considered to be the most active constituent of plant.

CONCLUSION

Present review provides an insight into botany, ethnopharmacology, phytochemistry, pharmacology and toxicology of T. indica. As an important traditional Indian medicine, few ethnobotanicals use of T. indica have been supported by modern pharmacological studies, especially in asthma, cancer and inflammation. Among compounds from various phytochemical classes, phenanthoindolizidine alkaloids namely tylophorine and tylophorinidine alkaloids have been considered as bioactive components of the plant and widely investigated. However, further identification, isolation and quantification employing some advanced hyphenated techniques viz. LC-MS/MS, LC-NMR to discover new pharmacologically active phytoconstituents in the management of different diseases. Several investigators have highlighted possible therapeutic roles of T. indica extracts and isolated compounds. Moreover, information about various aspects of T. indica pertaining to phytochemistry, toxicology and quality control are still unresolved. Further in-depth studies are required to discover key features viz. structure activity relationships, mode of action, safety and toxicity and therapeutic potentials T. indica in clinical settings.

Redox Imbalance and Oxidative DNA Damage During Isoniazid Treatment of HIV-Associated Tuberculosis: A Clinical and Translational Pharmacokinetic Study

BACKGROUND

The potential for hepatotoxicity during isoniazid-based tuberculosis (TB) treatment presents a major challenge for TB control programs worldwide. We sought to determine whether pharmacokinetic exposures of isoniazid and its metabolites were related to cellular oxidation/reduction status and downstream markers of oxidative DNA damage.

METHODS

We performed intensive pharmacokinetic sampling among isoniazid-treated patients to determine the relative plasma exposures of isoniazid, acetylisoniazid, hydrazine, and acetylhydrazine. Physiologically-based pharmacokinetic modeling was used to estimate liver tissue exposures during a 24-h dosing interval for each compound. We experimentally treated HepG2 cells with isoniazid and metabolites at equimolar concentrations corresponding to these exposures for 7, 14, and 28-day periods, and performed assays related to redox imbalance and oxidative DNA damage at each timepoint. We related a urine marker of oxidative DNA damage to serum isoniazid pharmacokinetic exposures and pharmacogenetics in a clinical study.

RESULTS

Among isoniazid-treated patients, serum concentrations of hydrazine and isoniazid concentrations were highly correlated. At equimolar concentrations that approximated hepatic tissue exposures during a 24-h dosing interval, hydrazine demonstrated the highest levels of redox imbalance, mitochondrial injury, and oxidative DNA damage over a 28-day treatment period. In a clinical validation study of isoniazid-treated TB patients, peak isoniazid serum concentrations were positively associated with a urine biomarker of oxidative DNA damage.

CONCLUSIONS

Isoniazid and its metabolites share the potential for oxidative cellular damage, with the greatest effects observed for hydrazine. Future studies should investigate the clinical consequences of oxidative stress with regards to clinical episodes of drug induced liver injury during isoniazid treatment.

Cocrystallization with syringic acid presents a new opportunity for effectively reducing the hepatotoxicity of isoniazid

Objective: With the aim of surmounting the severe hepatotoxicity induced by antituberculosis drug isoniazid (INH), a novel cocrystal of INH with hepatoprotective nutraceutical syringic acid (SYA), namely INH-SYA, was designed and prepared through cocrystallization strategy, which is an intriguing attempt to reduce the toxic side effects of INH.Significance: The study not only provides new thinking for inhibiting toxic side effects of drugs through cocrystallization strategy, but also opens a new pathway for the application of nutraceuticals in the pharmacy.Methods: INH and SYA were successfully crystallized into the same crystal lattice through combining volatilization with solvent assisted methods. The resulting cocrystal was structurally characterized by single crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), and differential scanning calorimetry (DSC).Results: The SCXRD analysis for the present cocrystal revealed that it has a 1:1 ratio of INH to SYA with two molecules INH homodimers and two SYA molecules, in which they are arranged alternately linked by hydrogen bonds to form a six molecules ring structure (R⁶₆(40)) in crystal. The systematic evaluation of the in vitro/in vivo suggested that, owing to the formation of cocrystal, the dissolution efficiency of SYA was increased 5.85-fold compared with that of coarse SYA, and the oral bioavailability of the cocrystal in rats was enhanced by 3.66 times. As a result, the present INH-SYA cocrystal almost removed INH induced serious hepatotoxicity, which was further demonstrated by the hepatotoxicity studies in rats.Conclusion: INH-SYA cocrystal could effectively reduce the hepatotoxicity of INH.

Possible Pathways of Hepatotoxicity Caused by Chemical Agents

BACKGROUND

Liver injury induced by drugs has become a primary reason for acute liver disease and therefore posed a potential regulatory and clinical challenge over the past few decades and has gained much attention. It also remains the most common cause of failure of drugs during clinical trials. In 50% of all acute liver failure cases, drug-induced hepatoxicity is the primary factor and 5% of all hospital admissions.

METHODS

The various hepatotoxins used to induce hepatotoxicity in experimental animals include paracetamol, CCl4, isoniazid, thioacetamide, erythromycin, diclofenac, alcohol, etc. Among the various models used to induce hepatotoxicity in rats, every hepatotoxin causes toxicity by different mechanisms.

RESULTS

The drug-induced hepatotoxicity caused by paracetamol accounts for 39% of the cases and 13% hepatotoxicity is triggered by other hepatotoxic inducing agents.

CONCLUSION

Research carried out and the published papers revealed that hepatotoxins such as paracetamol and carbon- tetrachloride are widely used for experimental induction of hepatotoxicity in rats.

A new cocrystal of isoniazid-quercetin with hepatoprotective effect: The design, structure, and in vitro/in vivo performance evaluation

With the purpose of overcoming the serious hepatotoxicity of antituberculosis drug isoniazid (INH), a cocrystallization strategy based on complementary advantages was implemented by choosing the hepatoprotective nutraceutical quercetin (QCT) as the cocrystal former. The strategy plays the solubility advantage of INH to improve the bioavailability of the insoluble QCT, thereby significantly enhancing the QCT's hepatoprotective effects. The optimized protective effects of QCT, in turn, feed back to INH to reduce its hepatotoxicity. Along this line, a novel INH-QCT cocrystal was successfully prepared and structurally characterized. The systematic evaluation results of the in vitro/in vivo revealed that, due to the advantage of INH's solubility, the dissolution efficiency of QCT from the cocrystal was increased 51.67-fold compared with that of coarse quercetin, and the oral bioavailability of the cocrystal in rats was enhanced by 28.91 times. As a result, the INH-QCT cocrystal almost removed INH induced serious hepatotoxicity, which has been demonstrated by the hepatotoxicity studies in rats. These findings present new opportunities for the advantageous solid forms of low-toxic antituberculosis drugs, and open new avenues against toxic side effects of drugs through the cocrystallization mean.

Hepatotoxicity Induced by Isoniazid-Lipopolysaccharide through Endoplasmic Reticulum Stress, Autophagy, and Apoptosis Pathways in Zebrafish

Isoniazid (INH) is a first-line antituberculosis drug. The incidence of adverse reactions accompanied by inflammation in the liver during drug administration to tuberculosis patients is high and severely affects clinical treatment. To better understand the mechanism of hepatotoxicity induced by INH under the inflammatory state, we compared the differences in levels of hepatotoxicity from INH between normal zebrafish and zebrafish in an inflammatory state to elucidate the hepatotoxic mechanism using different endpoints such as mortality, malformation, inflammatory effects, liver morphology, histological changes, transaminase analysis, and expression levels of certain genes. The results showed that the toxic effect of INH in zebrafish in an inflammatory state was more obvious than that in normal zebrafish, that liver size was significantly decreased as measured by liver fatty acid binding protein (LFABP) reporter fluorescence and intensity, and that alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were significantly increased. Hematoxylin and eosin (HE) staining and electron microscopy showed that hepatocyte injury was more obvious in the inflammatory state. In the inflammatory state, INH significantly increased the expression levels of endoplasmic reticulum stress (ERS)-related factors (GRP78, ATF6, PERK, IRE1, XBP1s, GRP94, and CHOP), autophagy-related factors (beclin 1, LC3, Atg3, and Atg12), and apoptosis-related factors (caspase-3, caspase-8, caspase-9, Bax, p53, and Cyt) in larvae. Correlational analyses indicated that the transcription levels of the inflammatory factors interleukin-1b (IL-1b), tumor necrosis factor beta (TNF-β), cyclooxygenase 2 (COX-2), and TNF-ɑ were strongly positively correlated with ALT and AST. Furthermore, the ERS inhibitor sodium 4-phenylbutyrate (4-PBA) could ameliorate the hepatotoxicity of INH-lipopolysaccharide (LPS) in zebrafish larvae. These results indicated that INH hepatotoxicity was enhanced in the inflammatory state. ERS and its mediated autophagy and apoptosis pathways might be involved in INH-induced liver injury promoted by inflammation.

Exposure of Infants to Isoniazid via Breast Milk After Maternal Drug Intake of Recommended Doses Is Clinically Insignificant Irrespective of Metaboliser Status. A Physiologically-Based Pharmacokinetic (PBPK) Modelling Approach to Estimate Drug Exposure of Infants via Breast-Feeding

Isoniazid is a first-line anti-tuberculosis drug recommended for treatment of drug-susceptible Mycobacterium tuberculosis infections. Breast-feeding is not contra-indicated while undergoing isoniazid therapy, even though isoniazid was found to migrate into breast milk, leading to infant drug exposure. Exposure assessment of isoniazid in infants exposed to the drug via breast milk has so far not accounted for the polymorphic expression of the isoniazid metabolising enzyme N-acetyltransferase 2. The aim of this study was to re-visit the safety assessment of maternal isoniazid therapy for infants exposed to the drug via breast milk, while accounting for fast and slow metabolisers in the adult and infant population, as well as for slower metabolism in small infants than in adults. We applied a physiologically-based pharmacokinetic (PBPK) modelling approach to estimate mother and infant external and internal drug exposure non-invasively. Validity of our PBPK models was confirmed through comparison of simulated results with experimental data. Highest recommended oral doses for mothers are daily 300 mg or 900 mg every 3 days. Simulation of maternal intake of 300 mg resulted in oral exposures of 0.58 (95%CI: 0.42-0.69) mg/day and 1.49 (1.22-1.50) mg/day for infants of fast and slow metabolising mothers, respectively. Oral exposures of infants within the first 24 h after maternal intake of 900 mg were 1.75 (1.25-2.06) mg/day and 4.46 (4.00-4.50) mg/day. Maximal drug concentrations in infant plasma ranged between 0.04 and 0.78 mg/L for the two dosing regimens. We therefore conclude that infant exposure to isoniazid via breast milk after maternal drug intake of highest recommended doses is very low. We expect that such low exposure levels most likely do not cause any clinically significant adverse effects in nursed infants.

Prominence of Oxidative Stress in the Management of Anti-tuberculosis Drugs Related Hepatotoxicity

Advanced medical services and treatments are available for treating Tuberculosis. Related prevalence has increased in recent times. Unfortunately, the continuous consumption of related drugs is also known for inducing hepatotoxicity which is a critical condition and cannot be overlooked. The present review article has focused on the pathways causing these toxicities and also the role of enzyme CYP2E1, hepatic glutathione, Nrf2-ARE signaling pathway, and Membrane Permeability Transition as possible targets which may help in preventing the hepatotoxicity induced by the drugs used in the treatment of tuberculosis.

Cytoprotective Properties of Carnosine against Isoniazid-Induced Toxicity in Primary Cultured Rat Hepatocytes

Background: Drug-induced liver injury is a critical clinical complication. Hence, finding new and safe protective agents with potential clinical application is of value. Isoniazid (INH) is an antituberculosis agent widely used against Mycobacterium tuberculosis infection in human. On the other hand, hepatotoxicity is a clinical complication associated with isoniazid therapy. Oxidative stress and its associated events are major mechanisms identified for INH-induced liver injury. Carnosine is an endogenously found peptide widely investigated for its hepatoprotective effects. On the other hand, robust antioxidant and cytoprotective effects have been attributed to this peptide. Methods: The current study designed to evaluate the potential cytoprotective properties of carnosine against INH-induced cytotoxicity in drug-exposed primary cultured rat hepatocytes. Primary cultured rat hepatocytes were incubated with INH (1.2 mM). Results: INH treatment caused significant increase in cell death and lactate dehydrogenase (LDH) release. On the other hand, it was found that markers of oxidative stress including reactive oxygen species were significantly increased in INH-treated cells. Cellular glutathione reservoirs were also depleted in INH-treated group. Carnosine treatment (50 and 100 µM) significantly diminished INH-induced oxidative stress and cytotoxicity. Conclusion: These data mention carnosine as a potential protective agent with therapeutic capability against INH hepatotoxicity.

Elevated CPK levels after hydrazine inhalation exposure in an F16 aircraft technician

Hydrazine is a hazardous material that is commonly used in the pharmaceutical industry, as well as in rocket and jet fuels, including the emergency power unit of F-16 model jets. We present four ground crew technicians who were exposed to hydrazine for less than one minute, due to a voltage fall in an F-16 jet. Physical examinations were normal and none of the technicians were symptomatic for toxicity. One of the technicians had abnormal blood chemistry levels for liver and muscle enzymes: serum glutamic-oxaloacetic transaminase(SGOT)-321U/L, serum glutamate-pyruvate transaminase (SGPT)-123U/L, and creatine phosphokinase (CPK) 3300U/L. The CPK level peaked during hospitalization to 20960U/L at 36 h after the exposure, and subsequently declined. Upon release from the hospital, 48 h after the exposure, the CPK level -was 9429U/L. In repeated tests one week and one year after exposure, liver function and CPK levels were normal. We conclude that evaluation of blood tests is important, in addition to a physical examination, in asymptomatic persons following exposure to even short term highly elevated levels of hydrazine.

Comparison of base-line and chemical-induced transcriptomic responses in HepaRG and RPTEC/TERT1 cells using TempO-Seq

The utilisation of genome-wide transcriptomics has played a pivotal role in advancing the field of toxicology, allowing the mapping of transcriptional signatures to chemical exposures. These activities have uncovered several transcriptionally regulated pathways that can be utilised for assessing the perturbation impact of a chemical and also the identification of toxic mode of action. However, current transcriptomic platforms are not very amenable to high-throughput workflows due to, high cost, complexities in sample preparation and relatively complex bioinformatic analysis. Thus, transcriptomic investigations are usually limited in dose and time dimensions and are, therefore, not optimal for implementation in risk assessment workflows. In this study, we investigated a new cost-effective, transcriptomic assay, TempO-Seq, which alleviates the aforementioned limitations. This technique was evaluated in a 6-compound screen, utilising differentiated kidney (RPTEC/TERT1) and liver (HepaRG) cells and compared to non-transcriptomic label-free sensitive endpoints of chemical-induced disturbances, namely phase contrast morphology, xCELLigence and glycolysis. Non-proliferating cell monolayers were exposed to six sub-lethal concentrations of each compound for 24 h. The results show that utilising a 2839 gene panel, it is possible to discriminate basal tissue-specific signatures, generate dose-response relationships and to discriminate compound-specific and cell type-specific responses. This study also reiterates previous findings that chemical-induced transcriptomic alterations occur prior to cytotoxicity and that transcriptomics provides in depth mechanistic information of the effects of chemicals on cellular transcriptional responses. TempO-Seq is a robust transcriptomic platform that is well suited for in vitro toxicity experiments.

Mitochondrial dysfunction as a mechanism of drug-induced hepatotoxicity: current understanding and future perspectives

Mitochondria are critical cellular organelles for energy generation and are now also recognized as playing important roles in cellular signaling. Their central role in energy metabolism, as well as their high abundance in hepatocytes, make them important targets for drug-induced hepatotoxicity. This review summarizes the current mechanistic understanding of the role of mitochondria in drug-induced hepatotoxicity caused by acetaminophen, diclofenac, anti-tuberculosis drugs such as rifampin and isoniazid, anti-epileptic drugs such as valproic acid and constituents of herbal supplements such as pyrrolizidine alkaloids. The utilization of circulating mitochondrial-specific biomarkers in understanding mechanisms of toxicity in humans will also be examined. In summary, it is well-established that mitochondria are central to acetaminophen-induced cell death. However, the most promising areas for clinically useful therapeutic interventions after acetaminophen toxicity may involve the promotion of adaptive responses and repair processes including mitophagy and mitochondrial biogenesis, In contrast, the limited understanding of the role of mitochondria in various aspects of hepatotoxicity by most other drugs and herbs requires more detailed mechanistic investigations in both animals and humans. Development of clinically relevant animal models and more translational studies using mechanistic biomarkers are critical for progress in this area.

Relevance for patients:This review focuses on the role of mitochondrial dysfunction in liver injury mechanisms of clinically important drugs like acetaminophen, diclofenac, rifampicin, isoniazid, amiodarone and others. A better understanding ofthe mechanisms in animal models and their translation to patients will be critical for the identification of new therapeutic targets.

High-throughput toxicity testing of chemicals and mixtures in organotypic multi-cellular cultures of primary human hepatic cells

High-throughput screening (HTS) of liver toxicants can bridge the gap in understanding adverse effects of chemicals on humans. Toxicity testing of mixtures is time consuming and expensive, since the number of possible combinations increases exponentially with the number of chemicals. The combination of organotypic culture models (OCMs) and HTS assays can lead to the rapidly evaluation of chemical toxicity in a cost and time-effective manner while prioritizing chemicals that warrant additional investigation. We describe the design, assembly and toxicant response of multi-cellular hepatic organotypic culture models comprised of primary human or rat cells assembled in 96-well plates (denoted as μOCMs). These models were assembled using automated procedures that did not affect hepatocyte function or viability, rendering them ideal for large-scale toxicity evaluations. Rat μOCMs were assembled to obtain insights into deviations from human toxicity. Four test chemicals (acetaminophen, ethanol, isoniazid, and perfluorooctanoic acid) were added to the μOCMs individually or in mixtures. HTS assays were utilized to measure cell death, apoptosis, glutathione depletion, mitochondrial membrane damage, and cytochrome P450 2E1 activity. The μOCMs exhibited increased toxicant sensitivity compared to hepatocyte sandwich cultures. Synergistic and non-synergistic interactions were observed when the toxicants were added as mixtures. Specifically, chemical interactions in the μOCMs were manifested by changes in apoptosis and decreased glutathione. The μOCMs accurately predicted hepatotoxicity for individual and mixtures of toxicants, demonstrating their potential for large-scale toxicity evaluations in the future.

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.

Investigating the CYP2E1 Potential Role in the Mechanisms Behind INH/LPS-Induced Hepatotoxicity

Tuberculosis (TB) is one of the oldest infectious diseases that affected humankind and remains one of the world's deadliest communicable diseases that could be considered as global emergency, but the discovery and development of isoniazid (INH) in the 1950s paved the way to an effective single and/or combined first-line anti-TB therapy. However, administration of INH induces severe hepatic toxicity in some patients. Previously, we establish a rat model of INH hepatotoxicity utilizing the inflammatory stress theory, in which bacterial lipopolysaccharide (LPS) potentially enhanced INH toxicity. These enhancing activities ranged between augmenting the inflammatory stress, oxidative stress, alteration of bile acid homeostasis, and CYP2E1 over-expression. Although pre-treatment with dexamethasone (DEX) helped overcome both inflammatory and oxidative stress which ended-up in alleviation of LPS augmenting effects, but still minor toxicities were being detected, alongside with CYP2E1 over expression. This finding positively indicated the corner-stone role played by CYP2E1 in the pathogenesis of INH/LPS-induced liver damage. Therefore, we examined whether INH/LPS co-treatment with CYP2E1 inhibitor diallyl sulfide (DAS) and DEX can protect against the INH/LPS-induced hepatotoxicity. Our results showed that pre-administration of both DAS and DEX caused significant reduction in serum TBA, TBil, and gamma-glutamyl transferase levels. Furthermore, the histopathological analysis showed that DAS and DEX could effectively reverse the liver lesions seen following INH/LPS treatment and protect against hepatic steatosis as indicated by absence of lipid accumulation. Pre-treatment with DAS alone could not completely block the CYP2E1 protein expression following INH/LPS treatment, as appeared in the immunoblotting and immunohistochemistry results. This is probably due to the fact that the combined enhancement activities of both INH and LPS on CYP2E1 protein expression levels might resist the blocking probabilities of DAS. In the meantime, addition of DEX to the DAS/INH/LPS combination caused a significant reduction in CYP2E1 protein expression as revealed by the immunoblotting and fading coloration in immunohistochemistry results. Thus, addition of DEX and DAS together caused strong protection against INH/LPS-induced hepatic damage. These findings reveal the potential therapeutic value of combining DAS and DEX with INH in TB management for reducing the potential risk and incidences of hepatotoxicity.

Revisiting Activation of and Mechanism of Resistance to Compound IQG-607 in Mycobacterium tuberculosis

IQG-607 is a metal complex previously reported as a promising anti-tuberculosis (TB) drug against isoniazid (INH)-resistant strains of Mycobacterium tuberculosis Unexpectedly, we found that INH-resistant clinical isolates were resistant to IQG-607. Spontaneous mutants resistant to IQG-607 were subjected to whole-genome sequencing, and all sequenced colonies carried alterations in the katG gene. The katG(S315T) mutation was sufficient to confer resistance to IQG-607 in both MIC assays and inside macrophages. Moreover, overexpression of the InhA(S94A) protein caused IQG-607's resistance.

Isoniazid toxicosis in dogs: 137 cases (2004-2014)

OBJECTIVE To establish the minimum toxic dose of isoniazid in dogs, characterize the clinical signs and outcomes for dogs following isoniazid ingestion, and determine whether IV administration of pyridoxine to dogs with isoniazid toxicosis is protective against death. DESIGN Retrospective case series. ANIMALS 137 dogs with isoniazid toxicosis. PROCEDURES The electronic database of the American Society for the Prevention of Cruelty to Animals Animal Poison Control Center was reviewed from January 2004 through December 2014 to identify dogs with isoniazid toxicosis. For each dog identified, information extracted from the medical record included signalment, estimated dose of isoniazid ingested, clinical signs, treatment, and outcome. Follow-up communication with pet owners or primary care veterinarians was performed when necessary to obtain missing information. RESULTS Clinical signs of isoniazid toxicosis were observed in 134 of 137 (98%) dogs and included seizures (n = 104), CNS signs without seizures (94), and gastrointestinal (41), cardiovascular (19), urogenital (4), and respiratory (1) abnormalities. Of the 87 dogs for which the outcome was available, 61 survived, 18 died, and 8 were euthanized. Probability of survival was positively associated with body weight and IV administration of pyridoxine and negatively associated with dose of isoniazid ingested and presence of seizures. Dogs that received pyridoxine IV were 29 times as likely to survive as dogs that did not receive pyridoxine IV. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated rapid diagnosis of isoniazid toxicosis and prompt treatment of affected dogs with pyridoxine and other supportive care were imperative for achieving a successful outcome.

Drug-Induced Liver Injury in Children: Clinical Observations, Animal Models, and Regulatory Status

Drug-induced liver injury in children (cDILI) accounts for about 1% of all reported adverse drug reactions throughout all age groups, less than 10% of all clinical DILI cases, and around 20% of all acute liver failure cases in children. The overall DILI susceptibility in children has been assumed to be lower than in adults. Nevertheless, controversial evidence is emerging about children's sensitivity to DILI, with children's relative susceptibility to DILI appearing to be highly drug-specific. The culprit drugs in cDILI are similar but not identical to DILI in adults (aDILI). This is demonstrated by recent findings that a drug frequently associated with aDILI (amoxicillin/clavulanate) was rarely associated with cDILI and that the drug basiliximab caused only cDILI but not aDILI. The fatality in reported cDILI studies ranged from 4% to 31%. According to the US Food and Drug Administration-approved drugs labels, valproic acid, dactinomycin, and ampicillin appear more likely to cause cDILI. In contrast, deferasirox, isoniazid, dantrolene, and levofloxacin appear more likely to cause aDILI. Animal models have been explored to mimic children's increased susceptibility to valproic acid hepatotoxicity or decreased susceptibility to acetaminophen or halothane hepatotoxicity. However, for most drugs, animal models are not readily available, and the underlying mechanisms for the differential reactions to DILI between children and adults remain highly hypothetical. Diagnosis tools for cDILI are not yet available. A critical need exists to fill the knowledge gaps in cDILI. This review article provides an overview of cDILI and specific drugs associated with cDILI.

Proteomic profile of Mycobacterium tuberculosis after eupomatenoid-5 induction reveals potential drug targets

Aim: We investigated a proteome profile, protein–protein interaction and morphological changes of Mycobacterium tuberculosis after different times of eupomatenoid-5 (EUP-5) induction to evaluate the cellular response to the drug-induced damages. Methods: The bacillus was induced to sub-minimal inhibitory concentration of EUP-5 at 12 h, 24 h and 48 h. The proteins were separated by 2D gel electrophoresis, identified by LC/MS-MS. Scanning electron microscopy and Search Tool for the Retrieval of Interacting Genes/Proteins analyses were performed. Results: EUP-5 impacts mainly in M. tuberculosis proteins of intermediary metabolism and interactome suggests a multisite disturbance that contributes to bacilli death. Scanning electron microscopy revealed the loss of bacillary form. Conclusion: Some of the differentially expressed proteins have the potential to be drug targets such as citrate synthase (Rv0896), phosphoglycerate kinase (Rv1437), ketol-acid reductoisomerase (Rv3001c) and ATP synthase alpha chain (Rv1308).

Establishment of a mouse model of enalapril-induced liver injury and investigation of the pathogenesis

Drug-induced liver injury (DILI) is a major concern in drug development and clinical drug therapy. Since the underlying mechanisms of DILI have not been fully understood in most cases, elucidation of the hepatotoxic mechanisms of drugs is expected. Although enalapril (ELP), an angiotensin-converting enzyme inhibitor, has been reported to cause liver injuries with a low incidence in humans, the precise mechanisms by which ELP causes liver injury remains unknown. In this study, we established a mouse model of ELP-induced liver injury and analyzed the mechanisms of its hepatotoxicity. Mice that were administered ELP alone did not develop liver injury, and mice that were pretreated with a synthetic glucocorticoid dexamethasone (DEX) and a glutathione synthesis inhibitor l-buthionine-(S,R)-sulfoximine (BSO) exhibited liver steatosis without significant increase in plasma alanine aminotransferase (ALT). In mice pretreated with DEX and BSO, ALT levels were significantly increased after ELP administration, suggesting that hepatic steatosis sensitized the liver to ELP hepatotoxicity. An immunohistochemical analysis showed that the numbers of myeloperoxidase-positive cells that infiltrated the liver were significantly increased in the mice administered DEX/BSO/ELP. The levels of oxidative stress-related factors, including hepatic heme oxygenase-1, serum hydrogen peroxide and hepatic malondialdehyde, were elevated in the mice administered DEX/BSO/ELP. The involvement of oxidative stress in ELP-induced liver injury was further supported by the observation that tempol, an antioxidant agent, ameliorated ELP-induced liver injury. In conclusion, we successfully established a model of ELP-induced liver injury in DEX-treated steatotic mice and demonstrated that oxidative stress and neutrophil infiltration are involved in the pathogenesis of ELP-induced liver injury.

Evaluation of HepaRG cells for the assessment of indirect drug-induced hepatotoxicity using INH as a model substance

HepaRG cells are widely used as an in vitro model to assess drug-induced hepatotoxicity. However, only few studies exist so far regarding their suitability to detect the effects of drugs requiring a preceding activation via the cytochrome P450 (CYP) system. A prototypic substance is the anti-tuberculosis agent INH, which is metabolized into N-acetylhydrazine, which then triggers hepatotoxicity. Therefore, the aim of the present study was to test if this effect can also be detected in HepaRG cells and if it can be counteracted by the known hepatoprotectant silibinin. For this purpose, differentiated HepaRG cells were treated with increasing concentrations of INH (0.1-100 mM) or 10 mM INH plus escalating concentrations of silibinin (1-100 µM). After 48 h of treatment, cell morphology and parameters indicating cell vitality, oxidative stress, and liver cell function were assessed. High concentrations of INH led to severe histopathological changes, reduced cell vitality and glutathione content, increased LDH and ASAT release into the medium, enhanced lipid peroxidation, and elevated cleaved caspase-3 expression. Additionally, glycogen depletion and reduced biotransformation capacity were seen at high INH concentrations, whereas at low concentrations an induction of biotransformation enzymes was noticed. Silibinin caused clear-cut protective effects, but with few parameters INH toxicity was even aggravated, most probably due to increased metabolization of INH into its toxic metabolite. In conclusion, HepaRG cells are excellently suited to evaluate the effects of substances requiring prior toxification via the CYP system, such as INH. They additionally enable the identification of complex substance interactions.

Drug-Induced Liver Injury

Drug-induced liver injury (DILI) can result from both idiosyncratic and intrinsic mechanisms. This article discusses the clinical impact of DILI from a broad range of medications as well as herbal and dietary supplements. Risk factors for idiosyncratic DILI (IDILI) are the result of multiple host, environmental, and compound factors. Some triggers of IDILI often seen in critical care include antibiotics, antiepileptic medications, statins, novel anticoagulants, proton pump inhibitors, inhaled anesthetics, nonsteroidal anti-inflammatory agents, methotrexate, sulfasalazine, and azathioprine. The mechanism of IDILI due to these medications varies, and the resulting damage can be cholestatic, hepatocellular, or mixed. The primary treatment of IDILI is to discontinue the causative agent. DILI due to acetaminophen is intrinsic because the liver damage is predictably aligned with the dose ingested. Acute acetaminophen ingestion can be treated with activated charcoal or N-acetylcysteine. Future areas of research include identification of mitochondrial stress biomarkers and of the patients at highest risk for DILI.

Role of Inflammatory and Oxidative Stress, Cytochrome P450 2E1, and Bile Acid Disturbance in Rat Liver Injury Induced by Isoniazid and Lipopolysaccharide Cotreatment

Isoniazid (INH) remains the core drug in tuberculosis management, but serious hepatotoxicity and potentially fatal liver injury continue to accompany INH consumption. Among numerous theories that have been established to explain INH-induced liver injury, an inflammatory stress theory has recently been widely used to explain the idiosyncrasy. Inflammatory stress usually sensitizes tissues to a drug's toxic consequences. Therefore, the present study was conducted to verify whether bacterial lipopolysaccharide (LPS)-induced inflammation may have a role in enhancing INH hepatotoxicity. While single INH or LPS administration showed no major toxicity signs, INH-LPS cotreatment intensified liver toxicity. Both blood biomarkers and histological evaluations clearly showed positive signs of severe liver damage accompanied by massive necrosis, inflammatory infiltration, and hepatic steatosis. Furthermore, elevated serum levels of bile acid associated with the repression of bile acid synthesis and transport regulatory parameters were observed. Moreover, the principal impact of cytochrome P450 2E1 (CYP2E1) on INH toxicity could be anticipated, as its protein expression showed enormous increases in INH-LPS-cotreated animals. Furthermore, the crucial role of CYP2E1 in the production of reactive oxygen species (ROS) was clearly obvious in the repression of hepatic antioxidant parameters. In summary, these results confirmed that this LPS-induced inflammation model might prove valuable in revealing the hepatotoxic mechanisms of INH and the crucial role played by CYP2E1 in the initiation and propagation of INH-induced liver damage, information which could be very useful to clinicians in understanding the pathogenesis of drug-induced liver injury.

Genotype and allele frequencies of isoniazid-metabolizing enzymes NAT2 and GSTM1 in Latvian tuberculosis patients

Pharmacogenomic testing of tuberculosis drug-metabolizing enzyme genes was proposed as a strategy to identify patients at risk for suboptimal responses to medications. However, variations of the genotype frequencies among ethnic groups exist and new alleles are been identified. The aim of this study was to identify polymorphisms of genes encoding metabolic enzymes NAT2 and GSTM1 in tuberculosis patients in Latvia and to estimate the frequency of NAT2 slow acetylator and GSTM1 null genotypes. In total, 85 DNA samples were genotyped, all individuals were Caucasian. An ethnic heterogeneity reflecting the multiethnic population of the country was observed. 49 patients were Latvians, 30 were Russians and 6 of other ethnicity. In total, 7 NAT2 alleles were identified: *4, *5, *6, *7, *11, *12, * and *13. The most frequent was the slow acetylation allele NAT2*6 (frequency 0.388) followed by the slow acetylation allele NAT2*5 and the rapid acetylation allele NAT2*4 (frequencies 0.306 and 0.194, respectively). The predominance of slow (51.8%) and intermediate (43.5%) acetylators compared with rapid acetylators (4.7%) was observed. The GSTM1 null genotype was detected in 48.2% of tuberculosis patients. When subgroup analysis was performed according to ethnicity, the results showed that neither NAT2 allele frequencies nor GSTM1 null genotype frequency did not differ significantly in TB patients of Latvian or Russian ethnicity. Overall, genotyping results were similar with previous reports of a NAT2 gene variation and GSTM1 null genotype frequency in Caucasians. Our findings have a contribution for the pharmacogenetics-based tuberculosis therapy in Latvia in future.

Update meta-analysis of the CYP2E1 RsaI/PstI and DraI polymorphisms and risk of antituberculosis drug-induced hepatotoxicity: evidence from 26 studies

WHAT IS KNOWN AND OBJECTIVE

Several studies have investigated the association of the CYP2E1 RsaI/PstI and/or DraI polymorphisms with susceptibility to antituberculosis drug-induced hepatotoxicity (ATDH), but the results have been inconsistent. Therefore, we performed a large meta-analysis to determine a more precise estimation of this relationship.

METHODS

The PubMed, EMBASE, China National Knowledge Infrastructure and Chinese Biomedical Literature databases were systematically searched to identify relevant studies. Meta-analyses based on the entire population and subgroups were performed to examine the association between CYP2E1 polymorphisms and susceptibility to ATDH. The odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of the associations.

RESULTS AND DISCUSSION

Twenty-six studies with a total of 7423 participants were analysed. The overall ORs of relevant studies demonstrated that the CYP2E1 RsaI/PstI C1/C1 genotype was associated with an elevated risk of ATDH (OR = 1·32, 95% CI 1·03-1·69, P = 0·027), but for the DraI polymorphism there was no increase in risk (OR = 1·05, 95% CI 0·80-1·37, P = 0·748). In subgroup analyses of the RsaI/PstI polymorphism, significant results were found in East Asians, patients who used isoniazid + rifampicin + pyrazinamide + ethambutol and patients with twice the upper limit of normal as the minimum standard for defining ATDH.

WHAT IS NEW AND CONCLUSION

This meta-analysis suggests that there is an increased risk of ATDH in individuals carrying the C1/C1 genotype of the CYP2E1 RsaI/PstI polymorphism. However, no association was found for the DraI polymorphism.

Transcriptome profiling and pathway analysis of hepatotoxicity induced by tris (2-ethylhexyl) trimellitate (TOTM) in mice

Tris (2-ethylhexyl) trimellitate (TOTM) is commonly used as an alternative plasticizer for medical devices. But very little information was available on its biological effects. In this study, we investigated toxicity effects of TOTM on hepatic differential gene expression analyzed by using high-throughput sequencing analysis for over-represented functions and phenotypically anchored to complementary histopathologic, and biochemical data in the liver of mice. Among 1668 candidate genes, 694 genes were up-regulated and 974 genes were down-regulated after TOTM exposure. Using Gene Ontology analysis, TOTM affected three processes: the cell cycle, metabolic process and oxidative activity. Furthermore, 11 key genes involved in the above processes were validated by real time PCR. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that these genes were involved in the cell cycle pathway, lipid metabolism and oxidative process. It revealed the transcriptome gene expression response to TOTM exposure in mouse, and these data could contribute to provide a clearer understanding of the molecular mechanisms of TOTM-induced hepatotoxicity in human.