Hepatic transcriptional analysis in rats treated with Cassia occidentalis seed: Involvement of oxidative stress and impairment in xenobiotic metabolism as a putative mechanism of toxicity

An adverse outcome pathway-based approach to assess aurantio-obtusin-induced hepatotoxicity

Cassiae semen (CS), a traditional Chinese medicine, has various bioactivities in preclinical and clinical practice. Aurantio-obtusin (AO) is a major anthraquinone (AQ) ingredient derived from CS, and has drawn public concerns over its potential hepatotoxicity. We previously found that AO induces hepatic necroinflammation by activating NOD-like receptor protein 3 inflammasome signaling. However, the mechanisms contributing to AO-motivated hepatotoxicity remain unclear. Herein, we evaluated hepatotoxic effects of AO on three liver cell lines by molecular and biochemical analyses. We found that AO caused cell viability inhibition and biochemistry dysfunction in the liver cells. Furthermore, AO elevated reactive oxygen species (ROS), followed by mitochondrial dysfunction (decreases in mitochondrial membrane potential and adenosine triphosphate) and apoptosis (increased Caspase-3, Cleaved caspase-3, Cytochrome c and Bax expression, and decreased Bcl-2 expression). We also found that AO increased the lipid peroxidation (LPO) and enhanced ferroptosis by activating cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA)-cAMP response element-binding (CREB) pathway (increases in PKA, p-CREB, acyl-CoA synthetase long chain family member 4). Based on these results, we used an AOP framework to explore the mechanisms underlying AO's hepatotoxicity. It starts from molecular initiating event (ROS), and follows two critical toxicity pathways (i.e., mitochondrial dysfunction-mediated apoptosis and LPO-enhanced ferroptosis) over a series of key events (KEs) to the adverse outcome of hepatotoxicity. The results of an assessment confidence in the adverse outcome pathway (AOP) framework supported the evidence concordance in dose-response, temporal and incidence relationships between KEs in AO-induced hepatotoxicity. This study's findings offer a novel toxicity pathway network for AO-caused hepatotoxicity.

Aurantio-obtusin induces hepatotoxicity through activation of NLRP3 inflammasome signaling

Aurantio-obtusin (AO) is a major anthraquinone (AQ) compound derived from Cassiae semen (CS). Although pharmacological studies have shown that the CS extracts can serve as effective agents in preclinical and clinical practice, AQ-induced hepatotoxicity in humans has attracted widespread attention. To explore whether AO induces hepatotoxicity and its underlying mechanisms, we exposed larval zebrafish and mice to AO. We found that AO delayed yolk sac absorption, and increased liver area and inflammation in the larval zebrafish. This inflammation was manifested as an increase in liver neutrophils and the up-regulated mRNA expression of interleukin-6 (Il-6) and tumor necrosis factor-α (Tnf-α) in the larval zebrafish. Furthermore, a pharmacokinetics study showed that AO was quickly absorbed into the blood and rapidly metabolized in the mice. Of note, AO induced hepatotoxicity in a gender-dependent manner, characterized by liver dysfunction, increased hepatocyte necrosis with inflammatory infiltration, and up-regulated mRNAs of Il-6, Tnf-α and monocyte chemotactic protein 1(Mcp1) in the female mice after 28-day oral administration. It also highlighted that AO triggered NOD-like receptor protein (NLRP) signaling in the female mice, as evidenced by the increased NLRP3, Caspase-1, pro-IL-1β, IL-1β and IL-18. Finally, we found that AO led to a significant increase in potassium calcium-activated channel, subfamily N, member 4 (KCNN4) and reactive oxygen species (ROS) levels, along with decreased nuclear factor kappa B p65 (NF-κB p65), in the female mouse livers. In conclusion, AO induced hepatotoxicity by activating NLRP3 inflammasome signaling, at least in part, through increased KCNN4 and ROS production, and NF-κB inhibition.

The clinical significance and correlative signaling pathways of paired box gene 9 in development and carcinogenesis

Paired box 9 (PAX9) gene belongs to the PAX family, which encodes a family of metazoan transcription factors documented by a conserved DNA binding paired domain 128-amino-acids, critically essential for physiology and development. It is primarily expressed in embryonic tissues, such as the pharyngeal pouch endoderm, somites, neural crest-derived mesenchyme, and distal limb buds. PAX9 plays a vital role in craniofacial development by maintaining the odontogenic potential, mutations, and polymorphisms associated with the risk of tooth agenesis, hypodontia, and crown size in dentition. The loss-of-function of PAX9 in the murine model resulted in a short life span due to the arrest of cleft palate formation and skeletal abnormalities. According to recent studies, the PAX9 gene has a significant role in maintaining squamous cell differentiation, odontoblast differentiation of pluripotent stem cells, deregulation of which is associated with tumor initiation, and malignant transformation. Moreover, PAX9 contributes to promoter hypermethylation and alcohol- induced oro-esophageal squamous cell carcinoma mediated by downregulation of differentiation and apoptosis. Likewise, PAX9 activation is also reported to be associated with drug sensitivity. In summary, this current review aims to understand PAX9 function in the regulation of development, differentiation, and carcinogenesis, along with the underlying signaling pathways for possible cancer therapeutics.

Role of anthraquinones in Cassia occidentalis induced hepato-myo-encephalopathy

ETHNOPHARMACOLOGICAL RELEVANCE

The different plant parts of Cassia occidentalis Linn, (CO) such as root, leaves, seeds and pods have traditionally been used in multifarious medicines for the treatment of dysentery, diarrhea, constipation, fever, eczema, cancer and venereal diseases.

MATERIALS AND METHODS

A systematic search of literature has been done in books and scientific databases like Science Direct, Pubmed, Google Scholar and Scopus etc. These sources were used to compile, analyze and review the information regarding the phytochemistry, toxicology and mechanism of toxicity of CO. The various references on this subject are cited in our review ranging from 1956 to 2019.

RESULTS

Unintentional exposure of CO causes serious pathological condition in children, known as hepato-myo-encephalopathy (HME). The toxicity after CO consumption is associated with the presence of anthraquinones (AQs), a class of secondary plant metabolites. These AQs at high concentrations are known to cause detrimental effects on essential vital organs such as liver, kidney, spleen, brain, muscle and reproductive organs. The animal studies in rodent models as well as clinical investigations have clearly revealed that CO toxicity is associated with enhanced hepatotoxicity serum markers (ALT, AST, and LDH) and presence of necrotic lesions in liver. Furthermore, CO also causes vacuolization in muscle tissue and increases the level of CPK which is a prominent muscle damage marker. Apart from these target organs, CO consumption also causes neuronal damage via disturbing the levels of different proteins such as (GFAP and b-tubulin III). The mechanistic studies show that AQs present in CO have the potential to disturb the cellular homeostasis via binding to DNA, increasing the production ROS and showing inhibitory effects on essential enzymes etc. Therefore, AQs have been observed to be the primary culprit agents contributing to the toxicity of CO in children and animals.

CONCLUSION

Despite its therapeutic potential, CO consumption can be detrimental if consumed in high amounts. A thorough analysis of literature reveals that AQs are the primary factors contributing to toxicity of CO seeds. Exposure to CO seeds causes HME, which is a serious life threatening condition for the malnourished children from lower strata. Multiple mechanisms are involved in the CO induced HME in patients. Lack of appropriate diagnostic measures and a poor understanding of the CO toxicity mechanism in humans and animals complicate the clinical management of CO poisoning subjects. Therefore, development of point of care diagnostic kits shall help in early diagnosis & suitable management of CO poisoning.

A Surviving Child from Acute Liver Failure after an Ingestion of Cassia occidentalis Seeds

Cassia occidentalis toxicity is thought to be uncommon; however, several cases have been described with acute hepatomyoencephalopathy with a high-mortality rate. We report a previously healthy, 2-year-old girl who developed acute liver failure after fresh seed ingestion. Without a specific antidote, we decided to implement supportive measures and medications including lactulose, sodium benzoate and N-acetylcysteine. The patient also experienced with cardiogenic shock and transient distal renal tubular acidosis, which were all spontaneously resolved. The liver chemistries returned to normal 3 months after the ingestion, without receiving liver assisted device or liver transplantation.

Investigation of the phytochemical composition and antioxidant properties of chinar (Platanus orientalis L.) leaf infusion against ethanol-induced oxidative stress in rats

Chinar (Platanus orientalis L.) is used in folk medicine against tooth and knee pain, wounds, inflammation, and stomach discomfort; however, the effects of P. orientalis leaf (PO-leaf) infusion on the liver and kidney are unknown. The aim of this study was to investigate the phytochemical composition and antioxidant properties of an infusion obtained from dried P. orientalis leaves against ethanol-induced oxidative stress (OS) in rats. After a toxicity test, thirty male Wistar rats were divided into five groups: Control, Ethanol 20%, Ethanol 20% + Silymarin (10 mg/kg), Ethanol 20% + PO-20 mg/mL infusion, and Ethanol 20% + PO-60 mg/mL infusion. The PO-leaf infusion doses were given ad libitum during 28 days to test the biochemical and antioxidant enzyme levels. According to the results, the PO-leaf contained rich compounds such as benzaldehyde, palmitic acid, 2,4-ditert-butylphenol, stearic acid, octadecanoic acid, linoleic acid, linolenic acid, kaempferol, and kaempferol derivatives. In the Ethanol group, AST, ALT, LDH, GGT, UA, and urea in the serum and GST and malondialdehyde (MDA) in the liver and erythrocyte tissues showed a significant increase compared to the Control group. AST, LDH, GGT, UA, and LDL-C levels in the serum and MDA (all tissues) significantly decreased in the Ethanol + PO-60 mg/mL group compared to the Ethanol group. SOD, GPx, and CAT activities in the kidney tissue of the Ethanol group showed a significant decrease compared to the Control group, whereas the GPx activity in kidney tissue in all of the treatment groups increased significantly compared to the Ethanol group. These findings suggest that the administration of the determined PO-leaf infusion doses might have a protective role against ethanol-induced liver and kidney damage in rats.

Molecular Mechanisms Involved in Oxidative Stress-Associated Liver Injury Induced by Chinese Herbal Medicine: An Experimental Evidence-Based Literature Review and Network Pharmacology Study

Oxidative stress, defined as a disequilibrium between pro-oxidants and antioxidants, can result in histopathological lesions with a broad spectrum, ranging from asymptomatic hepatitis to hepatocellular carcinoma in an orchestrated manner. Although cells are equipped with sophisticated strategies to maintain the redox biology under normal conditions, the abundance of redox-sensitive xenobiotics, such as medicinal ingredients originated from herbs or animals, can dramatically invoke oxidative stress. Growing evidence has documented that the hepatotoxicity can be triggered by traditional Chinese medicine (TCM) during treating various diseases. Meanwhile, TCM-dependent hepatic disorder represents a strong correlation with oxidative stress, especially the persistent accumulation of intracellular reactive oxygen species. Of note, since TCM-derived compounds with their modulated targets are greatly diversified among themselves, it is complicated to elaborate the potential pathological mechanism. In this regard, data mining approaches, including network pharmacology and bioinformatics enrichment analysis have been utilized to scientifically disclose the underlying pathogenesis. Herein, top 10 principal TCM-modulated targets for oxidative hepatotoxicity including superoxide dismutases (SOD), malondialdehyde (MDA), glutathione (GSH), reactive oxygen species (ROS), glutathione peroxidase (GPx), Bax, caspase-3, Bcl-2, nuclear factor (erythroid-derived 2)-like 2 (Nrf2), and nitric oxide (NO) have been identified. Furthermore, hepatic metabolic dysregulation may be the predominant pathological mechanism involved in TCM-induced hepatotoxic impairment.

Interaction of anthraquinones of Cassia occidentalis seeds with DNA and Glutathione

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Emodin has the maximum binding affinity to calf thymus DNA.

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Anthraquinones form GSH conjugates.

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Anthraquinones oxidizes GSH to GSSG.

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Cytotoxicity of anthraquinones are linked to their DNA binding affinity.

Consumption of Cassia occidentalis (CO) seeds has been associated with the hepatomyoencephalopathy (HME) in children. Recently, we have characterized the toxic anthraquinones (AQs) such as Emodin, Rhein, Aloe-emodin, Chrysophanol and Physcion in CO seeds and detected these moieties in the bio fluids of CO poisoning cases. As AQs were detected in the serum of HME patients, their interaction with key biomolecules including protein, DNA and glutathione (GSH) is imperative. In this regard, we have previously reported the interaction of these AQs with serum albumin protein and their subsequent biological effects. However, the interaction of these AQs with DNA and GSH remained unexplored. In the present work, we have studied the binding of these AQs of CO seeds with DNA and GSH by fluorescence spectroscopy, UV–vis spectral analysis, molecular docking, and biochemical studies. Results indicated a higher binding affinity for Emodin (K_a = 3.854 × 10⁴ L mol⁻¹ S⁻¹), Aloe-emodin (K_a = 0.961 × 10⁴ L mol⁻¹ S⁻¹) and Rhein (K_a = 0.034 × 10⁴ L mol⁻¹ S⁻¹) towards calf thymus DNA may be associated with their higher cytotoxicity. Alternatively, Physcion and Chrysophanol which showed less cytotoxicity in our earlier studies exhibited very low DNA binding. The binding pattern of all these AQs is consistent with the in-silico data. Absorption spectroscopy studies indicated the possible formation of GSH conjugate with Aloe-emodin and Physcion. Further biochemical measurement of GSH and GSSG (Glutathione disulfide) following incubation with AQs indicated that Aloe-emodin (28%) and Rhein (30%) oxidizes GSH to GSSG more as compared to other AQs. Taken together, these results suggest that the higher cytotoxicity of Rhein, Emodin and Aloe-emodin may be attributed to their potent DNA and GSH binding affinity.

Immunomodulatory potential of Rhein, an anthraquinone moiety of Cassia occidentalis seeds

Rhein, the most toxic anthraquinone moiety in Cassia occidentalis seeds, has been associated with hepatomyoencephalopathy (HME) in children. Structural and functional alterations in the lymphoid organs have been reported both in HME patients and experimental animals indicating a possibility of the dysfunction of immune system following exposure to CO seeds or its toxic anthraquinones (Panigrahi et al., 2014a). In the present study the mechanism of immune response of Rhein in splenocytes has been investigated by measuring functional assays of lymphocyte, cell surface receptor expression and analysis of cytokine levels. Results indicate that Rhein at a maximum dose of 10 μM is non cytotoxic up to 72 h in splenocytes. In addition to its potential to decrease the allogenic response of T-cells, Rhein significantly suppresses the proliferation of the concavalin A (Con A) and lipopolysaccharide (LPS) stimulated splenocytes. Lymphocyte receptor expression analysis revealed that Rhein exposure significantly down regulate the expression of CD3e, CD4, CD8, CD28, CD69 molecules in T-cells. The expression of CD19, CD28, CD40 in B-cells were also found to be significantly decreased following Rhein exposure. In accordance with the functional responses, Rhein treatment significantly lowered the expression of IL2 and IL6 cytokines in Con A stimulated splenocytes, and IL6, IL10, IFNγ and TNFα in LPS stimulated splenocytes. Over all, the study suggests the immunomodulatory activity of Rhein and that it would be useful in understanding the immune response of CO seeds in human subjects.

Antioxidant treatment enhances human mesenchymal stem cell anti-stress ability and therapeutic efficacy in an acute liver failure model

One of the major problems influencing the therapeutic efficacy of stem cell therapy is the poor cell survival following transplantation. This is partly attributed to insufficient resistance of transplanted stem cells to oxidative and inflammatory stresses at the injured sites. In the current study, we demonstrated the pivotal role of antioxidant levels in human umbilical cord mesenchymal stem cells (hUCMSCs) dynamic in vitro anti-stress abilities against lipopolysaccharide (LPS)/H₂O₂ intoxication and in vivo therapeutic efficacy in a murine acute liver failure model induced by D-galactosamine/LPS (Gal/LPS) by either reducing the antioxidant levels with diethyl maleate (DEM) or increasing antioxidant levels with edaravone. Both the anti- and pro-oxidant treatments dramatically influenced the survival, apoptosis, and reactive oxygen species (ROS) production of hUCMSCs through the MAPK-PKC-Nrf2 pathway in vitro. When compared with untreated and DEM-treated cells, edaravone-treated hUCMSCs rescued NOD/SCID mice from Gal/LPS-induced death, significantly improved hepatic functions and promoted host liver regeneration. These effects were probably from increased stem cell homing, promoted proliferation, decreased apoptosis and enhanced secretion of hepatocyte growth factor (HGF) under hepatic stress environment. In conclusion, elevating levels of antioxidants in hUCMSCs with edaravone can significantly influence their hepatic tissue repair capacity.