Seabuckthorn berry polysaccharide extracts protect against acetaminophen induced hepatotoxicity in mice via activating the Nrf-2/HO-1-SOD-2 signaling pathway

The Protective Effect of Sonneratia apetala Fruit Extract on Acetaminophen-Induced Liver Injury in Mice

Acute liver injury is a common consequence of taking overdose of acetaminophen (APAP). The aim of this study was to evaluate the antioxidant activity and hepatoprotective effect of a mangrove plant Sonneratia apetala fruit extract (SAFE) on APAP-induced liver injury in mice. Mice were orally pretreated with SAFE (100, 200, and 400 mg/kg) daily for one week. The control and APAP groups were intragastrically administered with distilled water, and NAC group was treated with N-Acetyl-L-cysteine (NAC) before APAP exposure. The results manifested that SAFE significantly improved survival rates, attenuated hepatic histological damage, and decreased the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in serum in APAP-exposed mice. SAFE treatment also increased glutathione (GSH) level and glutathione peroxidase (GSH-Px) activity, enhanced catalase (CAT), and total antioxidant capacity (T-AOC), as well as reducing malondialdehyde (MDA) level in liver. In addition, the formation of tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), and elevation of myeloperoxidase (MPO) in APAP-exposed mice were inhibited after SAFE treatment. And SAFE also displayed high DPPH radical scavenging activity and reducing power in vitro. The main bioactive components of SAFE such as total phenol, flavonoid, condensed tannin, and carbohydrate were determined. The current study proved that SAFE exerted potential protective effect against APAP-induced acute liver injury, which might be associated with the antioxidant and anti-inflammatory activities of SAFE.

The PD-1/PD-Ls pathway is up-regulated during the suppression of experimental autoimmune encephalomyelitis treated by Astragalus polysaccharides

Multiple sclerosis (MS) is an inflammatory demyelinating disease of CNS. Astragalus polysaccharides (APS), the main active extract from astragalus membranaceus which is a kind of traditional Chinese medicinal herb, is associated with a variety of immunomodulatory activities. We have evaluated the therapeutic effects of APS in the animal model of MS, experimental autoimmune encephalomyelitis (EAE). It was found that APS could effectively alleviate EAE through inhibiting MOG_35-55-specific T cell proliferation and reducing the expression of proinflammatory cytokines, which is mediated by up-regulating the expression of PD-1/PD-Ls signaling pathway. Our results demonstrated that EAE could be suppressed significantly by APS administration. It indicated that APS might be a potential of developing innovative drug for the therapy of MS.

Impairment of Mitochondrial-Nuclear Cross Talk in Lymphocytes Exposed to Landfill Leachate

Landfill leachate, a complex mixture of different solid waste compounds, is widely known to possess toxic properties. However, the fundamental molecular mechanisms engaged with landfill leachate exposure inducing cellular and sub-cellular ramifications are not well explicated. Therefore, we aim to examine the potential of leachate to impair mitochondrial machinery and its associated mechanisms in human peripheral blood lymphocytes. On assessment, the significant increase in the dichlorofluorescein (DCF) fluorescence, accumulation of 8-Oxo-2'-deoxyguanosine (8-oxo-dG), and levels of nuclear factor erythroid 2-related factor 2 (Nrf-2) strongly indicated the ability of the leachate to induce a pro-oxidant state inside the cell. The decrease in the mitochondrial membrane potential and alterations in the mitochondrial genome observed in leachate-exposed cells further suggested the disturbances in mitochondrial machinery. Moreover, these mitochondrial-associated redox imbalances were accompanied by the increased level of NF-κβ, pro-inflammatory cytokines, and DNA damage. In addition, the higher DNA fragmentation, release of nucleosomes, levels of polyadenosine diphosphate ADP-ribose polymerase (PARP), and activity of caspase-3 suggested the involvement of mitochondrial mediated apoptosis in leachate exposed cells. These observations were accompanied by the low proliferative index of the exposed cells. Conclusively, our results clearly indicate the ability of landfill leachate to disturb mitochondrial redox homeostasis, which might be a probable source for the immunotoxic consequences leading to plausible patho-physiological conditions in humans susceptible to such environmental exposures.

Evaluation of in vitro anti-oxidant and anti-inflammatory activities of Korean and Chinese Lonicera caerulea

BACKGROUND/OBJECTIVES

The honeysuckle berry (HB) contains ascorbic acid and phenolic components, especially anthocyanins, flavonoids, and low-molecular-weight phenolic acids. In order to examine the potential of HB as a hepatoprotective medicinal food, we evaluated the in vitro anti-oxidant and anti-inflammatory activities of Korean HB (HBK) and Chinese HB (HBC).

MATERIALS/METHODS

Antioxidant and anti-inflammatory effects of the extracts were examined in HepG2 and RAW 264.7 cells, respectively. The anti-oxidant capacity was determined by DPPH, SOD, CAT, and ARE luciferase activities. The production of nitric oxide (NO) as an inflammatory marker was also evaluated. The Nrf2-mediated mRNA levels of heme oxygenase-1 (HO-1), NAD(P)H dehydrogenase [quinone] 1 (Nqo1), and glutamate-cysteine ligase catalytic subunit (Gclc) were measured. The concentrations of HB extracts used were 3, 10, 30, 100, and 300 µg/mL.

RESULTS

The radical scavenging activity of all HB extracts increased in a concentration-dependent manner (P < 0.01 or P < 0.05). SOD (P < 0.05) and CAT (P < 0.01) activities were increased by treatment with 300 µg/mL of each HB extract, when compared to those in the control. NO production was observed in cells pretreated with 100 or 300 µg/mL of HBC and HBK (P < 0.01). Treatment with 300 µg/mL of HBC significantly increased Nqo1 (P < 0.01) and Gclc (P < 0.05) mRNA levels compared to those in the control. Treatment with 300 µg/mL of HBK (P < 0.05) and HBC (P < 0.01) also significantly increased the HO-1 mRNA level compared to that in the control.

CONCLUSIONS

Thus, the Korean and Chinese HBs were found to possess favorable in vitro anti-oxidant and anti-inflammatory activities. Nrf2 and its related anti-oxidant genes were associated with both anti-oxidant and anti-inflammatory activities in HB-treated cells. Further studies are needed to confirm these in vivo effects.

Mito-tempo protects against acute liver injury but induces limited secondary apoptosis during the late phase of acetaminophen hepatotoxicity

We previously reported that delayed treatment with Mito-tempo (MT), a mitochondria-targeted superoxide dismutase mimetic, protects against the early phase of acetaminophen (APAP) hepatotoxicity by inhibiting peroxynitrite formation. However, whether this protection is sustained to the late phase of toxicity is unknown. To investigate the late protection, C57Bl/6J mice were treated with 300 mg/kg APAP followed by 20 mg/kg MT 1.5 h or 3 h later. We found that both MT treatments protected against the late phase of APAP hepatotoxicity at 12 and 24 h. Surprisingly, MT-treated mice demonstrated a significant increase in apoptotic hepatocytes, while the necrotic phenotype was observed almost exclusively in mice treated with APAP alone. In addition, there was a significant increase in caspase-3 activity and cleavage in the livers of MT-treated mice. Immunostaining for active caspase-3 revealed that the positively stained hepatocytes were exclusively in centrilobular areas. Treatment with the pan-caspase inhibitor ZVD-fmk (10 mg/kg) 2 h post-APAP neutralized this caspase activation and provided additional protection against APAP hepatotoxicity. Treatment with N-acetylcysteine, the current standard of care for APAP poisoning, protected but did not induce this apoptotic phenotype. Mechanistically, MT treatment inhibited APAP-induced RIP3 kinase expression, and RIP3-deficient mice showed caspase activation and apoptotic morphology in hepatocytes analogous to MT treatment. These data suggest that while necrosis is the primary cause of cell death after APAP hepatotoxicity, treatment with the antioxidant MT may switch the mode of cell death to secondary apoptosis in some cells. Modulation of mitochondrial oxidative stress and RIP3 kinase expression play critical roles in this switch.

The role of apoptosis in acetaminophen hepatotoxicity

Although necrosis is recognized as the main mode of cell death induced by acetaminophen (APAP) overdose in animals and humans, more recently an increasing number of publications, especially in the herbal medicine and dietary supplement field, claim an important contribution of apoptotic cell death in the pathophysiology. However, most of these conclusions are based on parameters that are not specific for apoptosis. Therefore, the objective of this review was to re-visit the key signaling events of receptor-mediated apoptosis and APAP-induced programmed necrosis and critically analyze the parameters that are being used as evidence for apoptotic cell death. Both qualitative and quantitative comparisons of parameters such as Bax, Bcl-2, caspase processing and DNA fragmentation in both modes of cell death clearly show fundamental differences between apoptosis and cell death induced by APAP. These observations together with the lack of efficacy of pan-caspase inhibitors in the APAP model strongly supports the conclusion that APAP hepatotoxicity is dominated by necrosis or programmed necrosis and does not involve relevant apoptosis. In order not to create a new controversy, it is important to understand how to use these "apoptosis" parameters and properly interpret the data. These issues are discussed in this review.