(-)-Epigallocatechin-3-gallate (EGCG) prevents aminoglycosides-induced ototoxicity via anti-oxidative and anti-apoptotic pathways

AMP-activated protein kinase mediates (-)-epigallocatechin-3-gallate (EGCG) to promote lipid synthesis in mastitis cows

Mastitis, a serious threat to the health and milk production function of dairy cows decreases milk quality. Blood from three healthy cows and three mastitis cows were collected in this study and their transcriptome was sequenced using the Illumina HiSeq platform. Differentially expressed genes (DEGs) were screened according to the |log2FoldChange| > 1 and P-value < 0.05 criteria. Pathway enrichment and functional annotation were performed through KEGG and GO analyses. Finally, the mechanism of the AMP-activated protein kinase (AMPK) mediation of (-)-epigallocatechin-3-gallate (EGCG) to promote lipid metabolism in mastitis cows was analyzed in bovine mammary epithelial cells (BMECs). Transcriptome analysis revealed a total of 825 DEGs, with 474 genes showing increased expression and 351 genes showing decreased expression. The KEGG analysis of DEGs revealed that they were mainly linked to tumour necrosis factor, nuclear factor-κB signalling pathway, and lipid metabolism-related signalling pathway, whereas GO functional annotation found that DEGs were enriched in threonine and methionine kinase activity, cellular metabolic processes, and cytoplasm. AMPK expression, which is involved in several lipid metabolism pathways, was downregulated in mastitis cows. The results of in vitro experiments showed that the inhibition of AMPK promoted the expression of lipid synthesis genes in lipopolysaccharide-induced BMECs and that EGCG could promote lipid synthesis by decreasing the expression of AMPK and downregulating the expression of inflammatory factors in inflammatory BMECs. In conclusion, our study demonstrated that AMPK mediated EGCG to inhabit of inflammatory responses and promote of lipid synthesis in inflammatory BMECs.

Rutin Attenuates Gentamycin-induced Hair Cell Injury in the Zebrafish Lateral Line via Suppressing STAT1

Aminoglycoside antibiotics, including gentamicin (GM), induce delayed ototoxic effects such as hearing loss after prolonged use, which results from the death of hair cells. However, the mechanisms underlying the ototoxicity of aminoglycosides warrant further investigation, and there are currently no effective drugs in the clinical setting. Herein, the therapeutic effect of the flavonoid compound rutin against the ototoxic effects of GM in zebrafish hair cells was investigated. Animals incubated with rutin (100-400 µmol/L) were protected against the pernicious effects of GM (200 µmol/L). We found that rutin improves hearing behavior in zebrafish, and rutin was effective in reducing the number of Tunel-positive cells in the neuromasts of the zebrafish lateral line and promoting cell proliferation after exposure to GM. Subsequently, rutin exerted a protective effect against GM-induced cell death in HEI-OC1 cells and could limit the production of cytosolic reactive oxygen species (ROS) and diminish the percentage of apoptotic cells. Additionally, the results of the proteomic analysis revealed that rutin could effectively inhibit the expression of necroptosis and apoptosis related genes. Meanwhile, molecular docking analysis revealed a high linking activity between the molecular docking of rutin and STAT1 proteins. The protection of zebrafish hair cells or HEI-OC1 cells from GM-induced ototoxicity by rutin was attenuated by the introduction of STAT1 activator. Finally, we demonstrated that rutin significantly improves the bacteriostatic effect of GM by in vitro experiments, emphasising its clinical application value. In summary, these results collectively unravel a novel therapeutic role for rutin as an otoprotective drug against the adverse effects of GM.

Epigallocatechin gallate-rich fraction alleviates histamine-induced neurotoxicity in rats via inactivating caspase-3/JNK signaling pathways

Ingestion of prominent levels of histamine (HIS) leads to dangerous effects on biological systems. The most frequent and active catechin in green tea is epigallocatechin gallate which has strong antioxidant properties. Our research intended to investigate the possible neuroprotective effect of epigallocatechin gallate-rich fraction (EGCGR) against HIS-inducing neurotoxicity. Six groups of male rats (n = 5) were used as follows: (1) Distilled water, (2&3) EGCGR (100-200 mg/kg BWT/day, respectively), (4) HIS (1750 mg/kg BWT/week, (5&6) HIS + EGCGR. Administration of HIS for 14 days induced severe neurobehavioral changes including depression, incoordination, and loss of spatial memory. Extensive neuronal degeneration with diffuse gliosis was the prominent histopathological lesion observed and confirmed by strong immunostaining of casp-3, Cox-2, and GFAP. Additionally, the HIS group showed a significantly higher MDA level with lower CAT and GSH activity than the control group. Moreover, HIS promoted apoptosis, which is indicated by increasing JNK, and Bax and decreasing Bcl-2 gene expressions. Otherwise, the oral intake of EGCGR with HIS improved all neurotoxicological parameters induced by HIS. We concluded that HIS could cause neurotoxicity via an upset of the equilibrium between oxidants and antioxidants which trigger apoptosis through modulation of JNK signaling pathway. Furthermore, EGCGR has either direct or indirect antihistaminic effects.

Ferroptosis as a molecular target of epigallocatechin gallate in diseases

CONTEXT

Ferroptosis is a novel form of cell death characterised by iron overload and lipid peroxidation. It is closely associated with many diseases, including cardiovascular diseases, tumours, and neurological diseases. The use of natural chemicals to modulate ferroptosis is of great concern because of the critical role ferroptosis plays in disease. The main active ingredient in green tea is epigallocatechin gallate (EGCG), which is the most abundant catechin in green tea. EGCG shows a wide range of biological and therapeutic effects in various diseases, including anti-inflammatory, antioxidant, anticancer, and cardioprotective.

OBJECTIVE

The purpose of this article is to summarise the existing information on the relationship between EGCG and ferroptosis.

METHODS

Articles related to EGCG and ferroptosis were searched in PubMed and Web of Science databases, and the literature was analysed.

RESULTS AND CONCLUSION

EGCG could improve ferroptosis-related diseases and affect the development of ferroptosis by regulating the nuclear factor erythroid 2-related factor 2, autophagy, microRNA, signal transducer and activator of transcription 1, and protein kinase D1 signalling pathways.

Unveiling the Role of Oxidative Stress in Cochlear Hair Cell Death: Prospective Phytochemical Therapeutics against Sensorineural Hearing Loss

Hearing loss represents a multifaceted and pervasive challenge that deeply impacts various aspects of an individual's life, spanning psychological, emotional, social, and economic realms. Understanding the molecular underpinnings that orchestrate hearing loss remains paramount in the quest for effective therapeutic strategies. This review aims to expound upon the physiological, biochemical, and molecular aspects of hearing loss, with a specific focus on its correlation with diabetes. Within this context, phytochemicals have surfaced as prospective contenders in the pursuit of potential adjuvant therapies. These compounds exhibit noteworthy antioxidant and anti-inflammatory properties, which hold the potential to counteract the detrimental effects induced by oxidative stress and inflammation-prominent contributors to hearing impairment. Furthermore, this review offers an up-to-date exploration of the diverse molecular pathways modulated by these compounds. However, the dynamic landscape of their efficacy warrants recognition as an ongoing investigative topic, inherently contingent upon specific experimental models. Ultimately, to ascertain the genuine potential of phytochemicals as agents in hearing loss treatment, a comprehensive grasp of the molecular mechanisms at play, coupled with rigorous clinical investigations, stands as an imperative quest.

Development of Chinese herbal medicine for sensorineural hearing loss

According to the World Health Organization's world report on hearing, nearly 2.5 billion people worldwide will suffer from hearing loss by 2050, which may contribute to a severe impact on individual life quality and national economies. Sensorineural hearing loss (SNHL) occurs commonly as a result of noise exposure, aging, and ototoxic drugs, and is pathologically characterized by the impairment of mechanosensory hair cells of the inner ear, which is mainly triggered by reactive oxygen species accumulation, inflammation, and mitochondrial dysfunction. Though recent advances have been made in understanding the ability of cochlear repair and regeneration, there are still no effective therapeutic drugs for SNHL. Chinese herbal medicine which is widely distributed and easily accessible in China has demonstrated a unique curative effect against SNHL with higher safety and lower cost compared with Western medicine. Herein we present trends in research for Chinese herbal medicine for the treatment of SNHL, and elucidate their molecular mechanisms of action, to pave the way for further research and development of novel effective drugs in this field.

Testing the Anticancer Effect of Matcha Using Zebrafish as an Animal Model

Cancer is the second leading cause of death worldwide, and triple-negative breast cancer (TNBC) patients show the poorest prognosis and survival and the highest metastasis prevalence among all breast cancer subtypes. Matcha has recently been associated with multiple health benefits, and in vitro studies showed the potential effect of matcha in inhibiting cancer development and metastasis. We aimed to determine the safe, non-toxic dose of matcha suitable for zebrafish and to investigate the anticancer effect of matcha on the metastasis and growth of human TBNC cells using a zebrafish xenograft model. Wild-type AB zebrafish were used to conduct multiple general toxicity assessments, including developmental, neuromuscular, and cardiovascular toxicities. The safe, non-toxic concentration of matcha was determined to be 50 µg/mL and 100 µg/mL. Afterward, the zebrafish xenograft model was successfully established for MDA-MB-468 and MDA-MB-231 TNBC cells. The tumor size and metastasis of the injected cancer cells were traced through CM-Dil red fluorescent dye. Upon exposure to matcha at the safe doses, MDA-MB-231 and MDA-MB-468 showed a trend toward reduction in tumor size in a dose-dependent manner, indicated by quantified fluorescence. Matcha also visibly suppressed metastasis of cancer cells in the zebrafish body. Our results point to a potential dose-dependent anticancer effect of matcha on TNBC cells; however, more extended observation periods after xenotransplantation are required to confirm the long-term anticancer effect of matcha on tumor growth and metastasis.

N-Acetyl-L-cysteine Affects Ototoxicity Evoked by Amikacin and Furosemide Either Alone or in Combination in a Mouse Model of Hearing Threshold Decrease

Drug-induced ototoxicity resulting from therapy with aminoglycoside antibiotics and loop diuretics is one of the main well-known causes of hearing loss in patients. Unfortunately, no specific protection and prevention from hearing loss are recommended for these patients. This study aimed at evaluating the ototoxic effects produced by mixtures of amikacin (AMI, an aminoglycoside antibiotic) and furosemide (FUR, a loop diuretic) in the mouse model as the hearing threshold decreased by 20% and 50% using auditory brainstem responses (ABRs). Ototoxicity was produced by the combinations of a constant dose of AMI (500 mg/kg; i.p.) on FUR-induced hearing threshold decreases, and a fixed dose of FUR (30 mg/kg; i.p.) on AMI-induced hearing threshold decreases, which were determined in two sets of experiments. Additionally, the effects of N-acetyl-L-cysteine (NAC; 500 mg/kg; i.p.) on the hearing threshold decrease of 20% and 50% were determined by means of an isobolographic transformation of interactions to detect the otoprotective action of NAC in mice. The results indicate that the influence of a constant dose of AMI on FUR-induced hearing threshold decreases was more ototoxic in experimental mice than a fixed dose of FUR on AMI-induced ototoxicity. Moreover, NAC reversed the AMI-induced, but not FUR-induced, hearing threshold decreases in this mouse model of hearing loss. NAC could be considered an otoprotectant in the prevention of hearing loss in patients receiving AMI alone and in combination with FUR.

Evaluation of tea (Camellia sinensis L.) phytochemicals as multi-disease modulators, a multidimensional in silico strategy with the combinations of network pharmacology, pharmacophore analysis, statistics and molecular docking

Tea (Camellia sinensis L.) is considered as to be one of the most consumed beverages globally and a reservoir of phytochemicals with immense health benefits. Despite numerous advantages, tea compounds lack a robust multi-disease target study. In this work, we presented a unique in silico approach consisting of molecular docking, multivariate statistics, pharmacophore analysis, and network pharmacology approaches. Eight tea phytochemicals were identified through literature mining, namely gallic acid, catechin, epigallocatechin gallate, epicatechin, epicatechin gallate (ECG), quercetin, kaempferol, and ellagic acid, based on their richness in tea leaves. Further, exploration of databases revealed 30 target proteins related to the pharmacological properties of tea compounds and multiple associated diseases. Molecular docking experiment with eight tea compounds and all 30 proteins revealed that except gallic acid all other seven phytochemicals had potential inhibitory activities against these targets. The docking experiment was validated by comparing the binding affinities (Kcal mol^-1) of the compounds with known drug molecules for the respective proteins. Further, with the aid of the application of statistical tools (principal component analysis and clustering), we identified two major clusters of phytochemicals based on their chemical properties and docking scores (Kcal mol^-1). Pharmacophore analysis of these clusters revealed the functional descriptors of phytochemicals, related to the ligand-protein docking interactions. Tripartite network was constructed based on the docking scores, and it consisted of seven tea phytochemicals (gallic acid was excluded) targeting five proteins and ten associated diseases. Epicatechin gallate (ECG)-hepatocyte growth factor receptor (PDB id 1FYR) complex was found to be highest in docking performance (10 kcal mol^-1). Finally, molecular dynamic simulation showed that ECG-1FYR could make a stable complex in the near-native physiological condition.

Epigallocatechin Gallate Attenuates Gentamicin-Induced Nephrotoxicity by Suppressing Apoptosis and Ferroptosis

Gentamicin (GEN) is a kind of aminoglycoside antibiotic with the adverse effect of nephrotoxicity. Currently, no effective measures against the nephrotoxicity have been approved. In the present study, epigallocatechin gallate (EG), a useful ingredient in green tea, was used to attenuate its nephrotoxicity. EG was shown to largely attenuate the renal damage and the increase of malondialdehyde (MDA) and the decrease of glutathione (GSH) in GEN-injected rats. In NRK-52E cells, GEN increased the cellular ROS in the early treatment phase and ROS remained continuously high from 1.5 H to 24 H. Moreover, EG alleviated the increase of ROS and MDA and the decrease of GSH caused by GEN. Furthermore, EG activated the protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). After the treatment of GEN, the protein level of cleaved-caspase-3, the flow cytometry analysis and the JC-1 staining, the protein levels of glutathione peroxidase 4 (GPX4) and SLC7A11, were greatly changed, indicating the occurrence of both apoptosis and ferroptosis, whereas EG can reduce these changes. However, when Nrf2 was knocked down by siRNA, the above protective effects of EG were weakened. In summary, EG attenuated GEN-induced nephrotoxicity by suppressing apoptosis and ferroptosis.

Oridonin alleviates kanamycin-related hearing loss by inhibiting NLRP3/caspase-1/gasdermin D-induced inflammasome activation and hair cell pyroptosis

Aminoglycoside antibiotic drugs induce hearing loss in children and adults every year; however, the pathological mechanisms remain unknown. Previous studies have shown that the accumulation of reactive oxygen species (ROS) and inflammation in the inner ear may be responsible for kanamycin (KM)-induced hair cell death and hearing loss. Nucleotide-binding oligomerization domain-, leucine-rich repeat-, and pyrin domain-containing protein 3 (NLRP3) is a specific ROS sensor that initiates inflammasome assembly as well as activates caspase-1 and downstream inflammatory factors. Therefore, this study aimed to determine whether NLRP3 inflammasomes are involved in KM-related hearing loss in mice. Compared with the control (saline) group, increased levels of activated caspase-1, interleukin (IL)-1β, IL-18, N-terminal fragment of gasdermin D (GSDMD-N), and NLRP3 were detected by immunofluorescence, western blot, and enzyme-linked immunosorbent assay (ELISA) in the KM-plus-furosemide (LASIX)-treated group. Moreover, we also found that the NLRP3 inhibitor oridonin (Ori) could significantly rescue KM-related hearing loss by inhibiting NLRP3-inflammasome activation and caspase-1/GSDMD-related hair cell pyroptosis. These findings demonstrate that apoptosis, as well as pyroptosis, may be involved in KM-related hearing loss and that the NLRP3/caspase-1/GSDMD pathway may be a new target for treating aminoglycoside-induced hearing loss.

Cichoric Acid May Play a Role in Protecting Hair Cells from Ototoxic Drugs

Ototoxic hearing loss due to antibiotic medication including aminoglycosides and excess free radical production causes irreversible hair cell injury. Cichoric acid, a naturally occurring phenolic acid, has recently been found to exert anti-oxidative and anti-inflammatory properties through its free radical scavenging capacity. The present study aimed to investigate the protective effects of cichoric acid against neomycin-induced ototoxicity using transgenic zebrafish (pvalb3b: TagGFP). Our results indicated that cichoric acid in concentrations up to 5 μM did not affect zebrafish viability during the 2 h treatment period. Therefore, the otoprotective concentration of cichoric acid was identified as 5 μM under 2 h treatment by counting viable hair cells within the neuromasts of the anterior- and posterior-lateral lines in the study. Pretreatment of transgenic zebrafish with 5 μM of cichoric acid for 2 h significantly protected against neomycin-induced hair cell death. Protection mediated by cichoric acid was, however, lost over time. A terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay and FM4-64 staining, respectively, provided in situ evidence that cichoric acid ameliorated apoptotic signals and mechanotransduction machinery impairment caused by neomycin. A fish locomotor test (distance move, velocity, and rotation frequency) assessing behavioral alteration after ototoxic damage revealed rescue due to cichoric acid pretreatment before neomycin exposure. These findings suggest that cichoric acid in 5 μM under 2 h treatment has antioxidant effects and can attenuate neomycin-induced hair cell death in neuromasts. Although cichoric acid offered otoprotection, there is only a small difference between pharmacological and toxic concentrations, and hence cichoric acid can be considered a rather prototypical compound for the development of safer otoprotective compounds.