Recombinant adenovirus Ad-RUNrf2 reduces paraquat-induced A549 injury

Paraquat-induced ferroptosis suppression via NRF2 expression regulation

Paraquat (PQ) is an environmentally friendly and efficient herbicide, but PQ misuse or intentional self-use can cause death through multiple organ damage and can cause acute lung injury. Existing clinical treatments alleviate symptoms but do not significantly improve the mortality rate. Ferroptosis is a type of necrosis that presents in a manner very similar to the cell damage induced by high doses of PQ, but the role of ferroptosis in paraquat-induced lung injury remains unclear. In this study, we aimed to explore the role of ferroptosis in PQ-induced A549 cell injury and identify the potential mechanisms and critical sites of protection against PQ-induced A549 injury by ferroptosis inhibitors. We found that the ferroptosis inhibitors Ferr-1 and Lip-1 inhibit ferroptosis by attenuating oxidative stress through the upregulation of NRF2 gene expression. The protective role of the ferroptosis inhibitor Dfo was most evident in paraquat-induced cell injury. Dfo inhibited ferroptosis by iron chelation and promoted NRF2 protein level reduction. NRF2 attenuated PQ-induced ferroptosis in A549 cells, mainly through the upregulation of SLC40A1 to encourage the movement of iron to the extracellular side to alleviate iron overload, and the upregulation of SLC7A11 to promote the expression of GPX4 to inhibit lipid peroxidation.

Metformin Activates the Protective Effects of the AMPK Pathway in Acute Lung Injury Caused by Paraquat Poisoning

Objective

To observe whether metformin (MET) plays a protective role in acute lung injury (ALI) induced by paraquat (PQ) poisoning in rats by activating the AMPK/NF-κB signaling pathway.

Methods

PQ exposure was used to construct a rat model of ALI and a model of acute type II alveolar epithelial cell (RLE-6TN) injury, and MET intervention was performed. Rat lung tissue samples were collected to evaluate pathological changes in rat lung tissue, the oxidation index, and inflammatory factors; cell viability was detected by CCK-8 assays, and the protein expression levels of phospho-AMPK and phospho-NF-κBp65 in rat lung tissue and RLE-6TN cells were observed by Western blotting.

Results

Compared with the PQ group, the MET treatment group showed significantly (1) reduced lung wet/dry ratio (W/D: 4.67 ± 0.31 vs. 5.45 ± 0.40, P < 0.001), (2) reduced pathological changes in lung tissue, (3) decreased MDA levels (nmol/mg prot: 2.70 ± 0.19 vs. 3.08 ± 0.15, P < 0.001) and increased SOD and GSH-Px activities (U/mg prot: 76.17 ± 5.22 vs. 45.23 ± 6.58, 30.40 ± 2.84 vs. 21.00 ± 3.20; all P < 0.001) in lung tissue homogenate, (4) reduced levels of IL-1β, IL-6, and TNF-α in lung tissue homogenates (pg/mL: 47.87 ± 5.06 vs. 66.77 ± 6.55; 93.03 ± 7.41 vs. 107.39 ± 9.81; 75.73 ± 6.08 vs. 89.12 ± 8.94; all P < 0.001), (5) increased activity of RLE-6TN cells (%: 0.69 ± 0.09, 0.76 ± 0.06, and 0.58 ± 0.03 vs. 0.50 ± 0.05; all P < 0.05), (6) decreased protein levels of phospho-NF-κBp65 in lung homogenates and RLE-6TN cells (p-NF-κB/NF-κB: 0.47 ± 0.09 vs. 0.81 ± 0.13; 0.26 ± 0.07 vs. 0.79 ± 0.13; all P < 0.01), and (7) upregulated protein expression of phospho-AMPK in lung homogenates and RLE-6TN cells (p-AMPK/AMPK: 0.88 ± 0.05 vs. 0.36 ± 0.12; 0.93 ± 0.03 vs. 0.56 ± 0.15; all P < 0.01). After the addition of the AMPK inhibitor Compound C (Com C), the protein expression levels of phospho-AMPK and phospho-NF-κBp65 returned to baseline.

Conclusion

MET can effectively alleviate ALI induced by paraquat poisoning and increase the viability of cells exposed to paraquat. The mechanism may be related to the activation of the AMPK/NF-κB pathway, downregulation of inflammatory mediators such as IL-6 and TNF-α, and upregulation of the SOD and GSH-Px oxidation index, and these effects can be inhibited by the AMPK inhibitor Com C.

Effects of high temperature on pandemic and seasonal human influenza viral replication and infection-induced damage in primary human tracheal epithelial cell cultures

High temperature reduces influenza viral replication; however, the treatment of fevers is thought to be necessary to improve patients' conditions. We examined the effects of high temperature on viral replication and infection-induced damage to human tracheal epithelial cells. Cell viability and dome formation were reduced, the number of detached cells was increased and lactate dehydrogenase (LDH) levels tended to be increased from 72 h to 120 h in uninfected cells cultured at 40 °C. Long-term (72 h and/or 120 h) exposure to high temperatures (39 °C and/or 40 °C) decreased RNA levels and/or viral titers of eight influenza virus strains. Cell viability and dome formation were reduced, and the number of detached cells and LDH levels were increased to a similar extent after infection with the A/H1N1 pdm 2009 virus at 37 °C and 40 °C. High temperature increased the endosomal pH, where the viral RNA enters the cytoplasm, in uninfected cells. High temperature reduced the production of IL-6, which mediate viral replication processes, and IL-1β and IL-8 in uninfected and infected cells. Based on these findings, high temperature may cause similar levels of airway cell damage after infection to cells exposed normal temperatures, although high temperature reduces viral replication by affecting the function of acidic endosomes and inhibiting IL-6-mediated processes.

Adiponectin ameliorates the apoptotic effects of paraquat on alveolar type Ⅱ cells via improvements in mitochondrial function

Previous studies have demonstrated that excessive reactive oxygen/nitrogen species (ROS/RNS)-induced apoptosis is an important feature of the injury to the lung epithelium in paraquat (PQ) poisoning. However the precise mechanisms of PQ-induced dysfunction of the mitochondria, where ROS/RNS are predominantly produced, remain to be fully elucidated. Whether globular adiponectin (gAd), a potent molecule protective to mitochondria, regulates the mitochondrial function of alveolar type II cells to reduce PQ-induced ROS/RNS production remains to be investigated. The current study aimed to investigate the precise mechanisms of PQ poisoning in the mitochondria of alveolar type II cells, and to elucidate the role of gAd in protecting against PQ-induced lung epithelium injury. Therefore, lung epithelial injury was induced by PQ co-culture of alveolar type II A549 cells for 24 h. gAd was administrated to and removed from the injured cells in after 24 h. PQ was observed to reduce cell viability and increase apoptosis by ~1.5 fold in A549 cells. The oxidative/nitrative stress, resulting from ROS/RNS and disordered mitochondrial function were evidenced by increased O2−., NO production and reduced mitochondrial membrane potential (ΔΨ), adenosine 5′-triphosphate (ATP) content in PQ-poisoned A549 cells. gAd treatment significantly reversed the PQ-induced cell injury and mitochondrial dysfunction in A549 cells. The protective effects of gAd were partly abrogated by an adenosine 5′-monophosphate-activated protein kinase (AMPK) inhibitor, compound C. The results suggest that reduced ΔΨ and ATP content may result in PQ-induced mitochondrial dysfunction of the lung epithelium, which constitutes a novel mechanism for gAd exerting pulmonary protection against PQ poisoning via AMPK activation.

Magnitude of influenza virus replication and cell damage is associated with interleukin-6 production in primary cultures of human tracheal epithelium

Primary cultures of human tracheal epithelium were infected with influenza viruses to examine the relationships between the magnitude of viral replication and infection-induced cell damage and cytokine production in airway epithelial cells. Infection with four strains of the type A influenza virus increased the detached cell number and lactate dehydrogenase (LDH) levels in the supernatants. The detached cell number and LDH levels were related to the viral titers and interleukin (IL)-6 levels and the nuclear factor kappa B (NF-κB) p65 activation. Treatment of the cells with an anti-IL-6 receptor antibody and an NF-κB inhibitor, caffeic acid phenethyl ester, reduced the detached cell number, viral titers and the LDH levels and improved cell viability after infection with the pandemic influenza virus [A/Sendai-H/N0633/2009 (H1N1) pdm09]. A caspase-3 inhibitor, benzyloxycarbonyl-DEVD-fluoromethyl ketone, reduced the detached cell number and viral titers. Influenza viral infection-induced cell damage may be partly related to the magnitude of viral replication, NF-κB-p65-mediated IL-6 production and caspase-3 activation.

Mifepristone-inducible recombinant adenovirus attenuates paraquat-induced lung injury in rats

Objective:

To investigate the effects of overexpression of nuclear factor E2-related factor-2 (NRF2) on lung injury in rats exposed to paraquat (PQ) poisoning.

Methods:

A mifepristone (RU486)-inducible recombinant adenoviral vector carrying the human NRF2 gene (Ad-RUNRF2) was constructed and transfected via airway into the rats 7 days before the administration of RU486. Rats were orally challenged with PQ at 20 mg/kg 24 h after the injection of RU486. On days 0.5, 3 and 21 after PQ poisoning, the expressions of NRF2 and cytokines related to inflammation and oxidation in lung tissue were examined.

Results:

RU486 remarkably enhanced NRF2 mRNA and NRF2 protein levels in Ad-RUNRF2-transfected rats in a dose-dependent manner ( p < 0.01). PQ stimulated compensatory overexpression of NRF2, heme oxygenase 1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO-1) in lungs on days 0.5 and 3 after exposure ( p < 0.05), but depleted the expression of catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione (GSH), with an increased malondialdehyde (MDA) ( p < 0.05). However, pretreatment with Ad-RUNRF2 and RU486 strongly enhanced the expression levels of NRF2, HO-1, NQO-1, CAT and GSH-Px in the lungs of PQ intoxicated rats, with increased GSH and decreased MDA ( p < 0.05). Pretreatment with Ad-RUNRF2 and RU486 also strongly suppressed the PQ-induced activation of nuclear factor κB (NF-κB) and decreased the levels of tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). In addition, Ad-RUNRF2 and RU486 induction significantly reduced PQ-induced pathological changes in lungs and attenuated lung oedema and protein leakage caused by PQ ( p < 0.05).

Conclusion:

RU486-induced overexpression of NRF2 in lungs transfected with Ad-RUNRF2 can ameliorate PQ-induced lung injury by the activation of the NRF2-antioxidant response element (ARE) pathway.