58-F, a flavanone from Ophiopogon japonicus, prevents hepatocyte death by decreasing lysosomal membrane permeability

Ameliorative effect and mechanism of ursodeoxycholic acid on hydrogen peroxide-induced hepatocyte injury

To assess the ameliorative effect of ursodeoxycholic acid (UDCA) on hydrogen peroxide (H2O2)-induced hepatocyte injury. In our in vivo experiments, we modelled hyperlipidemia in ApoE-/- mice subjected to a 3-month high-fat diet and found that HE staining of the liver showed severe liver injury and excessive H2O2 was detected in the serum. We modelled oxidative stress injury in L02 cells by H2O2 in vitro and analyzed the levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) and related genes. UDCA significantly improved the level of oxidative stress in H2O2-injured L02 cells (P < 0.05). In addition, UDCA improved the transcription levels of inflammation and oxidative stress-related genes (P < 0.05), showing anti-inflammatory and anti-oxidative stress effects. UDCA has a protective effect on H2O2-damaged L02 cells, which lays a theoretical foundation for its application development.

Liriopogons (Genera Ophiopogon and Liriope, Asparagaceae): A Critical Review of the Phytochemical and Pharmacological Research

The closely related genera Liriope and Ophiopogon (Asparagaceae), collectively known in English as liriopogons, have similar therapeutic uses in treating cough, rheumatoid arthritis, and cleaning heat. The main aim of this review is to understand the current phytochemical and pharmacological knowledge including an assessment of the quality of the scientific evidence. A literature search was conducted in line with PRISMA guidelines, by retrieving available information up to 2020 from five online resources. The bioactive metabolites of liriopogons include steroidal saponins, flavonoids, polysaccharides, organic acids, phenols. Cardiovascular protective, anti-inflammatory, anti-diabetic, anti-oxidant, anti-cancer, neuroprotective, anti-viral, anti-acute myeloid leukemia and hepatoprotective effects have been at the center of attention. From a toxicological perspective Ophiopogon japonicus seems to be safe. Some problems with the quality of the pharmacological evidence stand out including the application of excessive dose level and methodological problems in the design. Additionally, a reasonable link between local/traditional uses and pharmacological assessment is often vague or not reflected in the text. Future researches on liriopogons are required to use rigorous scientific approaches in research on evidence-based natural products for the future benefits of patients.

A small bioactive glycoside inhibits epsilon toxin and prevents cell death

Clostridium perfringens epsilon toxin (Etx) is categorized as the third most lethal bioterrorism agent by the Centers for Disease Control and Prevention (CDC), with no therapeutic counter measures available for humans. Here, we have developed a high-affinity inhibitory compound by synthesizing and evaluating the structure activity relationship (SAR) of a library of diverse glycosides (numbered 1-12). SAR of glycoside-Etx heptamers revealed exceptionally strong H-bond interactions of glycoside-4 with a druggable pocket in the oligomerization and β-hairpin region of Etx. Analysis of its structure suggested that glycoside-4 might self-aggregate to form a robust micelle-like supra-molecular complex due to its linear side-chain architecture, which was authenticated by fluorescence spectroscopy. Further, this micelle hinders the Etx monomer-monomer interaction required for oligomerization, validated by both surface plasmon resonance (SPR) and immunoblotting. This phenomenon in turn leads to blockage of pore formation. Downstream evaluation revealed that glycoside-4 effectively blocked cell death of Etx-treated cultured primary cells and maintained cellular homeostasis via disrupting oligomerization, blocking pore formation, restoring calcium homeostasis, stabilizing the mitochondrial membrane and impairing high mobility group box 1 (HMGB1) translocation from nucleus to cytoplasm. Furthermore, a single dosage of glycoside-4 protected the Etx-challenged mice and restored normal function to multiple organs. This work reports for the first time a potent, nontoxic glycoside with strong ability to occlude toxin lethality, representing it as a bio-arm therapeutic against Etx-based biological threat.

Proteomic analysis of oxidized proteins in the brain and liver of the Nile tilapia (Oreochromis niloticus) exposed to a water-accommodated fraction of Maya crude oil

Crude oil (CO) is a super mixture of chemical compounds whose toxic effects are reported in fish species according to international guidelines. In the current study a proteomic analysis of oxidized proteins (ox) was performed on the brain and liver of Nile tilapia exposed to WAF obtained from relevant environmental loads (0.01, 0.1 and 1.0 g/L) of Maya CO. Results have shown that oxidation of specific proteins was a newly discovered organ-dependent process able to disrupt key functions in Nile tilapia. In control fish, enzymes involved on aerobic metabolism (liver aldehyde dehydrogenase and brain dihydrofolate reductase) and liver tryptophan--tRNA ligase were oxidized. In WAF-treated liver specimens, fructose-bisphosphate aldolase (FBA), β-galactosidase (β-GAL) and dipeptidyl peptidase 9 (DPP-9) were detected in oxidized form. oxDPP-9 could be favorable by reducing the risk associated with altered glucose metabolism, the opposite effects elicited by oxFBA and oxβ-GAL. oxTrypsin showed a clear adverse effect by reducing probably the hepatocyte capacity to achieve proteolysis of oxidized proteins as well as for performing the proper digestive function. Additionally, enzyme implicated in purine metabolism adenosine (deaminase) was oxidized. Cerebral enzymes of mitochondrial respiratory chain complex (COX IV, COX5B), of glycosphingolipid biosynthesis (β-N-acetylhexosaminidase), involved in catecholamines degradation (catechol O-methyltransferase), and microtubule cytoskeleton (stathmin) were oxidized in WAF-treated specimens. This response suggests, in the brain, an adverse scenario for the mitochondrial respiration process and for ATP provision as for ischemia/reoxygenation challenges. Proteomic analysis of oxidized proteins is a promising tool for monitoring environmental quality influenced by hydrocarbons dissolved in water.

A Rab20-Dependent Membrane Trafficking Pathway Controls M. tuberculosis Replication by Regulating Phagosome Spaciousness and Integrity

The intracellular pathogen Mycobacterium tuberculosis (Mtb) lives within phagosomes and also disrupts these organelles to access the cytosol. The host pathways and mechanisms that contribute to maintaining Mtb phagosome integrity have not been investigated. Here, we examined the spatiotemporal dynamics of Mtb-containing phagosomes and identified an interferon-gamma-stimulated and Rab20-dependent membrane trafficking pathway in macrophages that maintains Mtb in spacious proteolytic phagolysosomes. This pathway functions to promote endosomal membrane influx in infected macrophages, and is required to preserve Mtb phagosome integrity and control Mtb replication. Rab20 is specifically and significantly upregulated in the sputum of human patients with active tuberculosis. Altogether, we uncover an immune-regulated cellular pathway of defense that promotes maintenance of Mtb within intact membrane-bound compartments for efficient elimination.

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The spatiotemporal dynamics of the M. tuberculosis (Mtb) phagosome were investigated

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A Rab20-dependent pathway regulates endocytic influx into Mtb phagosomes

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Mtb avoids targeting to Rab20-positive phagosomes through its ESX-1 system

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Rab20 is required to maintain Mtb phagosome integrity and for control of Mtb replication

Differential induction of apoptosis and autophagy by pyrrolizidine alkaloid clivorine in human hepatoma Huh-7.5 cells and its toxic implication

Growing evidence suggests that the pyrrolizidine alkaloids (PAs)-induced hepatotoxicity is mediated by multiple cell death/defence modalities. However, the detailed mechanisms are still lacking. In this study, the hepatotoxic effects of four PAs including three retronecine-type ones (senecionine, seneciphylline and monocrotaline) and one otonecine-type (clivorine) on the proliferation of Huh-7.5 cells and the possible mechanisms were investigated. The results showed that all the PAs could inhibit cell proliferation and induce apoptosis in a concentration-dependent manner. Among them clivorine was the most significant one. In addition to its effect on apoptosis, clivorine treatment could promote autophagy in Huh-7.5 cells, as evidenced by the accumulation of autophagosomes, the enhancement of LC3B expression at the concentrations close to its IC0 value, and the increased conversion of LC3B-I to LC3B-II in the presence of lysosomal inhibitor (chloroquine) and decreased formation of green fluorescent protein (GFP)-LC3 positive puncta in the presence of autophagic sequestration inhibitor (3-methyladenine). Among the other tested PAs, senecionine and seneciphylline also activated autophagy at the same concentrations used for clivorine but monocrotaline did not. Furthermore, our study demonstrated that suppression or enhancement of autophagy resulted in the remarkable enhancement or suppression of senecionine, seneciphylline and clivorine-induced apoptosis at the concentration close to the IC10 for clivorine, respectively, indicating a protective role of autophagy against the PA-induced apoptosis at the low level of exposure. Collectively, our data suggest that PAs in different structures may exert different toxic disturbances on the liver cells. Apoptosis may be one of the most common models of the PA-induced cytotoxicity, while autophagy may be a structure-dependent defence model in the early stage of PA intoxication. Differential induction of apoptosis and autophagy probably depending on the concentration is essential for the cytotoxic potency of clivorine.

HMGB1 release by H2O2-induced hepatocytes is regulated through calcium overload and 58-F interference

HMGB1 is passively released by injured or dying cells and aggravates inflammatory processes. The release of HMGB1 and calcium overload have each been reported to be important mediators of H₂O₂-induced injury. However, a potential connection between these two processes remains to be elucidated. In the present study, we employed H₂O₂-induced hepatocytes to investigate how calcium overload takes place during cellular injury and how the extracellular release of HMGB1 is regulated by this overload. In addition, we investigated the use of 58-F, a flavanone extracted from Ophiopogon japonicus, as a potential therapeutic drug. We show that the PLCγ1-IP₃R-SOC signalling pathway participates in the H₂O₂-induced disturbance of calcium homoeostasis and leads to calcium overload in hepatocytes. After a rise in intracellular calcium, two calcium-dependent enzymes, PKCα and CaMKIV, are activated and translocated from the cytoplasm to the nucleus to modify HMGB1 phosphorylation. In turn, this promotes HMGB1 translocation from the nucleus to the cytoplasm and subsequent extracellular release. 58-F effectively rescued the hepatocytes by suppressing the PLCγ1-IP₃R-SOC signalling pathway and decreasing the calcium concentration in cells, thus reducing HMGB1 release.