5-(3',4'-dihydroxyphenyl)-γ-valerolactone, a microbiota metabolite of flavan-3-ols, activates SIRT1-mediated autophagy to attenuate H₂O₂-induced inhibition of osteoblast differentiation in MC3T3-E1 cells

Phenolic compounds are promising agents for the prevention of osteoporosis. 5-(3',4'-dihydroxyphenyl)-γ-valerolactone (DHPV) is the major microbiota metabolite of the flavan-3-ols phenolic compound. Herein, we aimed to investigate the potential mechanisms underlying the effects of DHPV on an osteoblast cell model with H2O2-induced oxidative injury. The MC3T3-E1 cell cultured with H2O2 was used as an oxidative injury model after pretreating with DHPV. Pretreatment with DHPV significantly attenuated cell viability decline, enhanced the activity of alkaline phosphatase and mineralization capacity in MC3T3-E1 cells. Reduced reactive oxygen species (ROS) and malondialdehyde (MDA) levels as well as increased in mitochondrial membrane potential and superoxide dismutase (SOD) activities indicated that DHPV affected both the oxidative and antioxidative processes in the cells. DHPV administration increased the LC3-II/I ratio and Beclin-1 protein levels, thereby promoting autophagy, which perhaps contributes to ROS elimination. However, the inhibition of Sirtuin 1 (SIRT1) by SIRT1 small interfering RNA reduced the protective effect of DHPV or SRT1720, as revealed by the increased ROS and MDA levels and decreased SOD, LC3-II/I ratio and Beclin-1 levels. DHPV may promote autophagy and reduce oxidative stress through the SIRT1-mediated pathway, thereby protecting MC3T3-E1 cells from H2O2-induced oxidative damage.

[Effects of flavonoids from Gynostemma pentaphyllum on A549 cells damaged by hydrogen peroxide]

This study focuses on the therapeutical effect of flavonoids from Gynostemma pentaphyllum on human lung carcinoma A549 cells induced by H₂O₂ oxidative stress and its possible mechanisms. The oxidative damage model was established using different concentrations H₂O₂ to induce A549 cell for different hours, and then treated with the flavonoids for 10 hours. The effects of flavonoids from G. pentaphyllum on cell viability of A549 cell damaged by H₂O₂ were detected by MTT assay. The contents of ROS were detected by DCFH-DA fluorescent probe method via flow cytometer. The contents of MDA, SOD and GSH were detected by TBA，NBT and DTNB-linked colorimetry assay, respectively. Expressions levels of Nrf2, NQO1 and HO-1 in A549 cells were evaluated by Western blot. The results showed that the cell activity was decreasing with the rise of H₂O₂ concentration within the range of 200-700 μmol·L⁻¹. The cell viability was 60.4% after treated with 500 μmol·L⁻¹H₂O₂ for 10 h, so it was chosen to be as an oxidant stress model. Compared with normal group，the contents of SOD, GSH and HO-1 expressions were lower after damaged with H₂O₂. On the contrary, the contents of ROS and MDA expressions were increased. Compared with model group, the contents of SOD, GSH and the expressions of Nrf2, NQO1 and HO-1 were increased after treated with flavonoids from G. pentaphyllum. The above results demonstrate that flavonoids from G. pentaphyllum may attenuate the effect of H₂O₂-induced oxidative stress on A549 cell by resisting oxidation. The finding may provide a biological evidence for the application of the G. pentaphyllum to fight the oxidative stress related diseases.

[Effect of hydrogen peroxide on the lateral line hair cell regeneration of zebrafish]

Objective:To investigate effect of hydrogen peroxide (H₂O₂) in the lateral line hair cell growth and regeneration after damage on zebrafish. Method:Select 5 dpf zebrafish, each group of 10, randomly divided into A control group: the system of water culture. B H₂O₂ group: 10 μmol/L, 20 μmol/L H₂O₂ solution to replace three times a day. C neomycin group: treatment with system water after 1 h culture by 200 μmol/L neomycin. D neomycin + H₂O₂ group: 20 μmol/L H₂O₂ solution to replace three times a day after 200 μmol/L neomycin treatment for 1 h. E cisplatin group: treatment with system water after 3 h culture by 1 000 μmol/L cisplatin. F cisplatin + H₂O₂ group: 20 μmol/L H₂O₂ solution to replace three times a day after 1 000 μmol/L cisplatin treatment for 3 h. Each group in H₂O₂ treatment for 0 h, 24 h, 48 h was marked their hair cells by immunofluorescence method and count the P1, P7, P8 neuromasts under the fluorescence microscope. Repeat 3 times. Result:The number of hair cells on P1, P7, P8 three neuramasts among 5 to 7 dpf zebrafish were 9.364±0.901(n=11),9.645±0.598(n=15),9.922±0.862(n=13), no obvious difference (P>0.05); 10μmol/L, 20μmol/L H₂O₂ treated zebrafish for 48 h, the numbers were 11.540±0.741,11.905±0.607,compaired with the control group(10.841±0.389), P<0.05; neomycin+ H₂O₂ 48 h and neomycin 48 h respectively were 10.600±0.689,8.767±0.603, P<0.01; cisplatin+ H₂O₂ 48 h and cisplatin 48 h were 5.967±1.086,5.633±1.548, P>0.05. Conclusion:20 μmol/L H₂O₂ promotes the development of lateral line hair cells of zebrafish; H₂O₂ promotes the regeneration of the lateral line hair cells after injury of neomycin, but not cisplatin.

[Sodium Ferulate Attenuates Oxidative Stressvia Suppressing NALP3 Inflammasome and ERK Signal Pathway]

OBJECTIVES

Study the gene and protein expression of NACHT-PYD-containing protein 3 (NALP3) inflammasome and extracellular regulated protein kinase (ERK), the intervention effects of sodium ferulate (SF) in human lung epithelial cells A549 under oxidative stress, and to investigate the possible mechanism.

METHODS

Human lung epithelial cells A549 cultured in vitro were divided into 6 groups, including control group,H₂O₂(200 umol/L) group, SF group (400 ug/mL), caspase-1 blockers (Z-VAD) group (Z-VAD 20 umol/L+H₂O₂200 umol/L), ERK blockers (PD98059) group (PD98059 50 umol/L+H₂O₂ 200 umol/L), and SF+H₂O₂ group (SF 400 ug/mL+H₂O₂ 200 umol/L). Fluorescent quantitative real-time PCR (qRT-PCR) was performed to detect the mRNA levels of caspase-1 and NALP3, the expression of caspase-1, NALP3, phosphorylated ERK p-ERK, ERK protein were evaluated by Western blot. The level of interleukin-1 β (IL-1β) were detected by ELISA.

RESULTS

Compared with the control group,H₂O₂ not only increased the mRNA and protein expression levels of caspase-1 and NALP3 and the protein expression levels of p-ERK/ERK, but also enhanced the secretion of IL-1β in human lung epithelial cells A549 (P<0.05),while SF group showed no statistic significance of those indicators above (P>0.05). The Z-VAD group, the PD98059 group and the SF+H₂O₂ group resisted the effects of H₂O₂ on A549 cells by decreasing the mRNA and protein expressions of caspase-1 and NALP3,and the protein expression of p-ERK/ERK, as well as reducing the secretion of IL-1β(P<0.05),when compared with the H₂O₂ group.

CONCLUSIONS

SF may reduce the expression of caspase-1, NALP3 and IL-1β by inhibiting ERK, so as to reduce the inflammation caused by oxidative stress.