Seawater Drowning-induced Acute Lung Injury Research Articles

Vaporization of perfluorocarbon attenuates sea-water-drowning-induced acute lung injury by deactivating the NLRP3 inflammasomes in canines.

Seawater-drowning-induced acute lung injury (SD-ALI) is a life-threatening disorder characterized by increased alveolar-capillary permeability, an excessive inflammatory response, and refractory hypoxemia. Perfluorocarbons (PFCs) are biocompatible compounds that are chemically and biologically inert and lack toxicity as oxygen carriers, which could reduce lung injury in vitro and in vivo. The aim of our study was to explore whether the vaporization of PFCs could reduce the severity of SD-ALI in canines and investigate the underlying mechanisms. Eighteen beagle dogs were randomly divided into three groups: the seawater drowning (SW), perfluorocarbon (PFC), and control groups. The dogs in the SW group were intratracheally administered seawater to establish the animal model. The dogs in the PFC group were treated with vaporized PFCs. Probe-based confocal laser endomicroscopy (pCLE) was performed at 3h. The blood gas, volume air index (VAI), pathological changes, and wet-to-dry (W/D) lung tissue ratios were assessed. The expression of heme oxygenase-1 (HO-1), nuclear respiratory factor-1 (NRF1), and NOD-like receptor family pyrin domain containing-3 (NLRP3) inflammasomes was determined by means of quantitative real-time polymerase chain reaction (qRT-PCR) and immunological histological chemistry. The SW group showed higher lung injury scores and W/D ratios, and lower VAI compared to the control group, and treatment with PFCs could reverse the change of lung injury score, W/D ratio and VAI. PFCs deactivated NLRP3 inflammasomes and reduced the release of caspase-1, interleukin-1β (IL-1β), and interleukin-18 (IL-18) by enhancing the expression of HO-1 and NRF1. Our results suggest that the vaporization of PFCs could attenuate SD-ALI by deactivating NLRP3 inflammasomes via the HO-1/NRF1 pathway.

The Therapeutic Effect and the Possible Mechanism of C-Phycocyanin in Lipopolysaccharide and Seawater-Induced Acute Lung Injury

BackgroundSeawater drowning-induced acute lung injury (ALI) is a severe clinical condition characterized by increased alveolar-capillary permeability, excessive inflammatory response, and refractory hypoxemia. C-phycocyanin (C-PC), a biliprotein found in blue-green algae such as spirulina platensis, is widely used in the food and dietary nutritional supplement fields due to its beneficial pharmacological effects. Previous studies have revealed that C-PC has anti-inflammatory, antioxidant, and anti-apoptotic activities.PurposeTherefore, this study investigated the protective effect and underlying mechanisms of C-PC on lipopolysaccharide (LPS) and seawater (SW) induced ALI (SW and LPS-induced ALI).MethodsAn SW and LPS mouse model of ALI mice was established through intratracheal administration of 5mg/kg LPS and 25% SW. Different doses of C-PC (100, 200 and 400 mg/kg) were administered by intraperitoneal injection for seven days. In addition, gap junction communication in RAW264.7 and MLE-12 cells was determined following stimulation with 25% SW and 10 μg/ml LPS after treatment with C-PC (120 μg/ml). Moreover, the arterial partial pressure of oxygen, lung wet/dry weight ratios, total protein content and MPO levels in the bronchoalveolar lavage fluid (BALF), and the histopathologic and ultrastructure staining of the lung tissues were determined. The oxidative stress index, levels of the pro-inflammatory mediators, epithelial cell viability and apoptosis, and the regulatory effect of C-PC on the NF-κB/NLRP3 axis were investigated.ResultsThe results showed that C-PC significantly alleviated pathological damages, suppressed oxidative stress, inflammation and apoptosis, and enhanced the viability of epithelial cells in the lung tissues. Furthermore, C-PC was shown to inhibit activation of the NF-κB/NLRP3 pathway and the formation of the NLRP3 inflammasome complex.ConclusionsIn conclusion, C-PC shows promising therapeutic value in SW and LPS-induced ALI/ARDS, providing new insight into ALI/ARDS treatment.

Nrf2 protects against seawater drowning-induced acute lung injury via inhibiting ferroptosis

BackgroundFerroptosis is a new type of nonapoptotic cell death model that was closely related to reactive oxygen species (ROS) accumulation. Seawater drowning-induced acute lung injury (ALI) which is caused by severe oxidative stress injury, has been a major cause of accidental death worldwide. The latest evidences indicate nuclear factor (erythroid-derived 2)-like 2 (Nrf2) suppress ferroptosis and maintain cellular redox balance. Here, we test the hypothesis that activation of Nrf2 pathway attenuates seawater drowning-induced ALI via inhibiting ferroptosis.Methodswe performed studies using Nrf2-specific agonist (dimethyl fumarate), Nrf2 inhibitor (ML385), Nrf2-knockout mice and ferroptosis inhibitor (Ferrostatin-1) to investigate the potential roles of Nrf2 on seawater drowning-induced ALI and the underlying mechanisms.ResultsOur data shows that Nrf2 activator dimethyl fumarate could increase cell viability, reduced the levels of intracellular ROS and lipid ROS, prevented glutathione depletion and lipid peroxide accumulation, increased FTH1 and GPX4 mRNA expression, and maintained mitochondrial membrane potential in MLE-12 cells. However, ML385 promoted cell death and lipid ROS production in MLE-12 cells. Furthermore, the lung injury became more aggravated in the Nrf2-knockout mice than that in WT mice after seawater drowning.ConclusionsThese results suggested that Nrf2 can inhibit ferroptosis and therefore alleviate ALI induced by seawater drowning. The effectiveness of ferroptosis inhibition by Nrf2 provides a novel therapeutic target for seawater drowning-induced ALI.

Heme oxygenase-1 attenuates seawater drowning-induced acute lung injury through a reduction in inflammation and oxidative stress

ObjectiveHeme oxygenase-1 (HO-1) plays a critical protective role in various insults-induced acute lung injury (ALI) through its strong anti-inflammatory, anti-oxidant, and anti-apoptotic properties, but its protective role and mechanism on seawater aspiration-induced acute lung injury remains unclear. This study aimed to explore the therapeutic potential and mechanism of HO-1 to attenuate seawater aspiration-induced ALI in vivo and in vitro. MethodsThe viability and invasion of A549 cell were analyzed through cell counting kit-8 and lactate dehydrogenase release assay; the transcriptional level of inflammatory cytokines (TNF-α, IL-6, IL-8 and MCP-1) and cell proliferation-related cytokines (FoxM1, Ccnb1 and Cdc25C) in seawater-treated A549 cell were tested by qPCR; apoptotic cells were analyzed by flow cytometryd; HO-1mRNA and protein were determined by qPCR and western blotting; the fluorescent indicators (DCFH-DA, dihydroethidium, MitoSox Red and Fluo-4) were used to monitor generation of ROS and mitochondrial function. The lung wet/dry weight radio and lactate dehydrogenase activity, Sirius red staining, TUNEL assay and immunohistochemical staining with anti-pan Cytokeratin antibody were analyzed in seawater-drowning mice. The role of HO-1 on seawater-drowning pulmonary injury was explored via HO-1 activity inhibitors (Zinc protoporphyrin) in vitro and in vivo. ResultsSeawater exposure decreased the cellular viability, increased the production of pro-inflammatory cytokines (IL-6, IL-8 and TNF-α), induced cellular apoptosis and inhibited the expression of cell proliferation-related cytokines (FoxM1, Ccnb1 and Cdc25C). Moreover, seawater exposure led to mitochondrial dysfunction in A549 cells. Supplement of HO-1 sepcific inducer (heme) or its catalytic product (biliverdin) significantly attenuated seawater-induced A549 damage and promoted cell proliferation. However, Zinc protoporphyrin abolished the beneficial effects of HO-1 on seawater drowning-induced pulmonary tissue injury. ConclusionHO-1 attenuates seawater drowning-induced lung injury by its anti-inflammatory, anti-oxidative, and anti-apoptosis function.

Activation of TRPV1-dependent calcium oscillation exacerbates seawater inhalation-induced acute lung injury.

Calcium is an important second messenger and it is widely recognized that acute lung injury (ALI) is often caused by oscillations of cytosolic free Ca2+. Previous studies have indicated that the activation of transient receptor potential-vanilloid (TRPV) channels and subsequent Ca2+ entry initiates an acute calcium-dependent permeability increase during ALI. However, whether seawater exposure induces such an effect through the activation of TRPV channels remains unknown. In the current study, the effect of calcium, a component of seawater, on the inflammatory reactions that occur during seawater drowning-induced ALI, was examined. The results demonstrated that a high concentration of calcium ions in seawater increased lung tissue myeloperoxidase activity and the secretion of inflammatory mediators, such as tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β and IL-6. Further study demonstrated that the seawater challenge elevated cytosolic Ca2+ concentration, indicated by [Ca2+]c, by inducing calcium influx from the extracellular medium via TRPV1 channels. The elevated [Ca2+c] may have resulted in the increased release of TNF-α and IL-1β via increased phosphorylation of nuclear factor-κB (NF-κB). It was concluded that a high concentration of calcium in seawater exacerbated lung injury, and TRPV1 channels were notable mediators of the calcium increase initiated by the seawater challenge. Calcium influx through TRPV1 may have led to greater phosphorylation of NF-κB and increased release of TNF-α and IL-1β.

Erythropoietin Pretreatment Attenuates Seawater Aspiration-Induced Acute Lung Injury in Rats.

Seawater drowning-induced acute lung injury (ALI) is a serious clinical condition characterized by increased alveolar-capillary permeability, excessive inflammatory responses, and refractory hypoxemia. However, current therapeutic options are largely supportive; thus, it is of great interest to search for alternative agents to treat seawater aspiration-induced ALI. Erythropoietin (EPO) is a multifunctional agent with antiinflammatory, antioxidative, and antiapoptotic properties. However, the effects of EPO on seawater aspiration-induced ALI remain unclear. In the present study, male rats were randomly assigned to the naive group, normal saline group, seawater group, or seawater + EPO group. EPO was administered intraperitoneally at 48 and 24h before seawater aspiration. Arterial blood gas analysis was performed with a gas analyzer at baseline, 30min, 1h, 4h, and 24h after seawater aspiration, respectively. Histological scores, computed tomography scan, nuclear factor kappa B p65, inducible nitric oxide synthase, caspase-3, tumor necrosis factor-alpha, interleukin (IL)-1β, IL-6, IL-10, wet-to-dry weight ratio, myeloperoxidase activity, malondialdehyde, and superoxide dismutase in the lung were determined 30min after seawater aspiration. Our results showed that EPO pretreatment alleviated seawater aspiration-induced ALI, as indicated by increased arterial partial oxygen tension and decreased lung histological scores. Furthermore, EPO pretreatment attenuated seawater aspiration-induced increase in the expressions of pulmonary nuclear factor kappa B p65, inducible nitric oxide synthase, caspase-3, tumor necrosis factor-alpha, IL-1β, myeloperoxidase activity, and malondialdehyde when compared with the seawater group. Collectively, our study suggested that EPO pretreatment attenuates seawater aspiration-induced ALI by down-regulation of pulmonary pro-inflammatory cytokines, oxidative stress, and apoptosis.

3,5,4′-Tri-O-acetylresveratrol attenuates seawater aspiration-induced lung injury by inhibiting activation of nuclear factor-kappa B and hypoxia-inducible factor-1α

Resveratrol is a phytoalexin synthesized by a wide variety of plants, which has been proven to be effective in suppressing oxidative stress and inflammation. The aim of the present study was to investigate the effect of Resveratrol's prodrug: 3,5,4′-tri-O-acetylresveratrol, on seawater drowning-induced acute lung injury (SWD-ALI). Histological changes were assessed to study lung injuries; cytokines in lung samples were monitored by ELISA to reflect inflammation; T-SOD and MDA activity were detected to examine oxidative stress in lung tissues. Besides, we also tested the expression of NF-κB and HIF-1α to probe the possible protecting mechanism of 3,5,4′-tri-O-acetylresveratrol on AWD-ALI. The results showed that pretreatment with different doses of 3,5,4′-tri-O-acetylresveratrol improved seawater-induced lung histopathologic changes, alleviated lung edema, reduced the production of inflammatory mediators including TNF-α and IL-1β, inhibited MDA activity, and enhanced T-SOD activity, which was possibly associated with inhibition of NF-κB and HIF-1α. In conclusion, the current study demonstrated that 3,5,4′-tri-O-acetylresveratrol exhibited a protective effect on SWD-ALI by inhibiting of the inflammatory response, which may also involve the suppression of oxidative stress in lung tissues.

Urinary Trypsin Inhibitor Attenuates Seawater-Induced Acute Lung Injury by Influencing the Activities of Nuclear Factor-ĸB and Its Related Inflammatory Mediators

Background: Few data are available on the role of neutrophil elastase (NE) and nuclear factor-ĸB (NF-ĸB) in the course of seawater drowning-induced acute lung injury (SWD-ALI), and there is no evidence on the value of giving urinary trypsin inhibitor (UTI) in the case of SWD-ALI. Objective: To investigate the role of NF-ĸB and NE in the pathogenesis of SWD-ALI and whether UTI treatment can attenuate SWD-ALI in rabbits. Methods: Rabbits were randomly assigned to control, seawater drowning, and UTI treatment groups. The rabbits in the control group only suffered from intubation, whereas the rabbits in the seawater drowning group and the UTI treatment group received arterial injection of normal saline without/with 50,000 U/kg body weight of UTI after instillation of seawater into an endotracheal catheter. The activities or contents of NF-ĸB, MPO, NE, TNF-α, and IL-10 in lung tissue were measured by nonradioactive EMSA, biochemical methods, and ELISA, respectively. Results: After the seawater challenge, all of the rabbits demonstrated immediate drops in arterial PaO₂/FiO₂ and pronounced pulmonary edema and inflammatory cell infiltration with evidence of an increase in the ratio of wet weight to dry weight, lung permeability index, lung injury scores, and the activities or contents of NF-ĸB, NE, MPO, TNF-α, and IL-10. UTI treatment markedly attenuated lung histopathological changes with evidence of a decrease in all of the parameters, except for upregulation of IL-10. Arterial PaO₂/FiO₂ was significantly improved after 6 h of UTI treatment. Conclusion: These results suggest that NF-ĸB and NE play an important role in SWD-ALI. UTI protects against SWD-ALI, at least partly, through inhibition of the enhanced local activity of NF-ĸB, contents of TNF-α and NE, and infiltration of neutrophils and promotion of the level of IL-10.

Tanshinone IIA ameliorates seawater exposure-induced lung injury by inhibiting aquaporins (AQP) 1 and AQP5 expression in lung

Aquaporins (AQPs), a family of transmembrane water channels, mediate physiological response to changes of fluid volume and osmolarity. It is still unknown what role of AQPs plays in seawater drowning-induced acute lung injury (ALI) and whether pharmacologic modulation of AQPs could alleviate the severity of ALI caused by seawater aspiration. In our study, the results from RT-PCR and Western blotting showed that intratracheal installation of seawater up-regulated the mRNA and protein levels of AQP1 and AQP5 in lung tissues. Furthermore, we found that treatment of tanshinone IIA (TIIA, one of the main active components from Chinese herb Danshen) significantly reduced the elevation of AQP1 and AQP5 expression induced by seawater in rats, A549 cells and primary alveolar type II cells. Treatment of TIIA also improved lung histopathologic changes and blood-gas indices, and reduced lung edema and vascular leakage. These findings demonstrated that AQP1 and AQP5 might play an important role in the development of lung edema and lung injury, and that treatment with TIIA could significantly alleviate seawater exposure-induced ALI, which was probably through the inhibition of AQP1 and AQP5 over-expression in lungs.

Effects of dexamethasone on NF-κB activity in lung tissue of rabbits with seawater drowning-induced acute lung injury

Objective To explore the changes of nuclear factor-κB(NF-κB) activity,TNF-α,IL-1β and IL-10 contents in the lung tissue of rabbit with seawater drowning-induced acute lung injury(SWD-ALI) and the effects of dexamethasone on the changes.Methods Forty-two New Zealand white rabbits were randomly allocated to control group(C group,n = 18),seawater drowning group(S group,n = 12) and dexamethasone treatment group(D group,n = 12).The drowning model was established by instilling seawater(2 ml/kg body weight) into the endotracheal catheter of animals,then the rabbits received arterial injection of dexamethasone(D group,1 mg/kg body weight) or 2 ml normal saline(S group).Blood gas analysis was done at predefined time points.The lung wet to dry weight ratio(W/D) and lung permeability index(LPI) were calculated.The activity of NF-κB was analyzed by non-radioactive electrophoretic mobility shift assay(EMSA).The contents of TNF-α,IL-1β and IL-10 were detected by ELISA.Meanwhile,the pathology changes of lung tissues were detected by H-E staining,and the semi-quantitative lung pathologic scores(LPS) was also calculated.Results The lung of rabbits in S group was obviously enlarged and had more severe edema and congestion compared with C group;furthermore,histopathologic findings indicated inflammatory cell infiltration and other pathologic signs of ALI;the oxygenation index(PaO2 /FiO2) reached the bottom at 0.5 h and did not elevate to more than 300 mmHg(1 mmHg = 0.133 kPa) until 6 h.The largest W/D ratio appeared at 3 h after seawater drowning,and the highest LPI and LPS appeared at 6 h;and NF-κB activity and the contents of TNF-α,IL-1β and IL-10 in lung tissues were significantly higher in S group than in C group(P 0.05,P 0.01).The pathological changes of lung in the rabbits of D group were improved compared with S group but worse than those of group C.The W/D ratio,lung permeability index,and lung pathological score in D group were lower than those of the S group;and the oxygenation index was greatly improved 6 h after seawater drowning.NF-κB activity and the contents of TNF-α,IL-1β and IL-10 in lung tissues were significantly lower than those of the S group(P 0.05,P 0.01).Conclusion Dexamethasone can inhibit the activity of NF-κB and the expression of TNF-α,IL-1β and IL-10 in the lung tissue of rabbits with SWD-ALI and relieve the inflammatory responses and pathological changes.