Heme oxygenase-1 participates in the resolution of seawater drowning-induced acute respiratory distress syndrome

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

Background

Seawater 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.

Purpose

Therefore, 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).

Methods

An 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.

Results

The 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.

Conclusions

In conclusion, C-PC shows promising therapeutic value in SW and LPS-induced ALI/ARDS, providing new insight into ALI/ARDS treatment.

Determining the effect of water temperature on the T1 and T2 relaxation times of the lung tissue at 9.4 T MRI: A drowning mouse model

Japanese individuals have a unique culture of soaking in a bathtub, and forensic pathologists have experienced fatal cases due to drowning. However, T1 and T2 relaxation times of a drowning lung are poorly documented. In the present study, we investigated the relationship between drowning water temperature and T1 and T2 relaxation times of drowning lung tissues at 9.4 T MRI (Bruker, BioSpec94/20USR). The mice used as animal drowning models were directly submerged in freshwater. Water temperature was set to 8 °C-10 °C (cold), 20 °C-22 °C (normal), 30 °C, and 45 °C. The regions of interest (ROIs) on the axial section of the third slice were set at the central and peripheral areas of each-the left and the right-lung. T1 relaxation times measured immediately after death differed by the presence or absence of soaking water, except in case of cold water temperature. In the drowning groups, T1 relaxation time showed a linear dependency on water temperature. By contrast, T2 relaxation time was almost constant regardless of the presence of drowning under the same temperature condition; when compared in the lung areas of the same individuals, the times were uniformly reduced in drowning models. To minimize the effects of hypostasis and decomposition, we performed measurements immediately after death and were able to determine the noticeable difference in drowning water temperature. These results may be useful for qualitative assessments of a drowning lung and may serve as a basis when imaging the human body during forensic autopsy cases.

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

Background

Ferroptosis 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.

Methods

we 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.

Results

Our 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.

Conclusions

These 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.

Human Adipose-Derived Stem Cells Promote Seawater-Immersed Wound Healing by Activating Skin Stem Cells via the EGFR/MEK/ERK Pathway

Seawater (SW) immersion can increase the damage of skin wounds and produce refractory wounds. However, few studies have been conducted to investigate the mechanisms of SW immersion on skin wounds. In our current study, we investigated the effect of human adipose-derived stem cells (hADSCs) on the repair of SW-treated full-thickness skin wounds and the underlying mechanisms. The results showed that SW immersion could reduce the expression of EGF and suppress the activation of the MEK/ERK signaling pathway. At the same time, the proliferation and migration of skin stem cells were inhibited by SW immersion, resulting in delayed wound healing. However, hADSCs significantly accelerated the healing of SW-immersed skin wounds by promoting cell proliferation and migration through the aforementioned mechanisms. Our results indicate a role for hADSCs in the repair of seawater-immersed skin wounds and suggest a potential novel treatment strategy for seawater-immersed wound healing.

BML-111 attenuates high glucose-induced inflammation, oxidative stress and reduces extracellular matrix accumulation via targeting Nrf2 in rat glomerular mesangial cells

Diabetic nephropathy (DN) is the most paradigmatic complication of diabetes mellitus (DM) and brings about severe social and economic burdens. BML-111 is a potent agonist of Lipoxin A4 and has shown anti-inflammatory function in many diseases. The aim of the study is to investigate the effects of BML-111 on high glucose (HG) -induced mesangial cells. HBZY-1 cells were stimulated by HG with or without BML-111. ML385 was used as an Nrf2 inhibitor. Cell proliferation was measured by CC-K 8 assay. Besides, levels of TNF-α, IL-1, IL-6 and MCP-1 were detected by corresponding ELISA kits. DCFH-DA staining and an available ROS kit were employed to determine the ROS generation. In addition, extracellular matrix (ECM) accumulation was evaluated by immunofluorescence assay and western blot analysis. The protein expressions involved in Nrf2/HO-1 and MAPK pathway were assessed by western blot assay. Results indicated that BML-111 extremely inhibited HBZY-1 cell proliferation induced by HG. Moreover, BML-111 reduced the levels of TNF-α, IL-1, IL-6 and MCP-1, declined intracellular ROS level, and attenuated expression of ECM proteins laminin, fibronectin, collagen IV and TGF-β1. In addition, BML-111 promoted the activation of Nrf2, HO-1, and NQO1, while suppressed the phosphorylation of p38 and JNK. Further, NRF2 silence reversed the inhibitory effects of BML-111 on HG-induce inflammation, oxidative stress and ECM accumulation, accelerate the MAPK signaling, and diminished the expression of Nrf2 pathway. In summary, BML-111 alleviated HG-induced injury in HBZY-1 cells by repressing inflammatory response, oxidative stress and ECM accumulation via activating Nrf2 and inhibiting MAPK pathway.

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

OBJECTIVE

Heme 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.

METHODS

The 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.

RESULTS

Seawater 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.

CONCLUSION

HO-1 attenuates seawater drowning-induced lung injury by its anti-inflammatory, anti-oxidative, and anti-apoptosis function.

RETRACTED: MicroRNA-494 inhibition alleviates acute lung injury through Nrf2 signaling pathway via NQO1 in sepsis-associated acute respiratory distress syndrome

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Figures 5G,H+I, which appear to have a similar phenotype as many other publications, as detailed here: https://pubpeer.com/publications/7C9483B2551952AD53CCFCE206C4EB; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. The journal requested that the corresponding author comment on these concerns and provide the raw data. The authors did not respond to this request and therefore the Editor-in-Chief decided to retract the article.