Hydrogen sulfide attenuates ferroptosis and stimulates autophagy by blocking mTOR signaling in sepsis-induced acute lung injury.

Sepsis often leads to multiple organ failure or even death and is a significant health problem that contributes to a heavy economic burden. The lung is the first organ to be affected by sepsis. Presently, there is no specific drug or method to treat sepsis and sepsis-induced acute lung injury (ALI). H2S, along with CO and NO, is a physiological gas that acts as a signaling molecule and plays an active role in fighting various lung infections. GYY4137 is a novel H2S donor that is stable in vivo and in vitro. However, particularly in the context of ferroptosis, GYY4137 affects cecal ligation and puncture (CLP)-induced ALI by a mechanism that is not understood. Ferroptosis is a new form of cell necrosis. The primary mechanism is the accumulation of cellular lipid ROS in an iron-dependent manner. The principal objective of this project was to investigate the effects of GYY4137 on ferroptosis and autophagy in a mouse model of sepsis-induced ALI. We divided the experimental mice randomly into 5 groups: (1) sham group; (2) CLP group; (3) CLP + DMSO group: (4) CLP + GYY4137 (25 mg/kg) group; and (5) CLP + GYY4137 (50 mg/kg) group. (6) CLP + Rapamycin (2.0 mg/Kg) group. (7) CLP + Chloroquine (80 mg/Kg) group. (8) the Chloroquine (80 mg/Kg) + GYY (50 mg/Kg) group. The findings showed that GYY4137 significantly protected against CLP-induced ALI by improving sepsis-induced lung histopathological changes, diminishing lung tissue damage, ameliorating oxidative stress, and attenuating the severity of lung injury in mice. In this study, we found that GYY4137 could alleviate septicemia-induced ferroptosis in ALI by increasing the expression of GPx4 and SLC7A11 in lung tissue after CLP. One unexpected finding was the extent to which the levels of ferritin and ferritin light chain increased after CLP, which may be a compensatory mechanism for storing abnormally increased iron. We also found that the expression of p-mTOR, P62, and Beclin1 was significantly increased and that LC3II/LC3I declined after LPS stimulation, but the effect was inhibited by treatment with GYY4137, indicating that GYY4137 could inhibit the activation of autophagy in sepsis-induced ALI by blocking mTOR signaling.

Li J ，Li M ，Li L ，Ma J ，Yao C ，Yao S ... -  《-》

GYY4137 alleviates sepsis-induced acute lung injury in mice by inhibiting the PDGFRβ/Akt/NF-κB/NLRP3 pathway.

GYY4137 [GYY, morpholin-4-ium-4-methoxyphenyl (morpholino) phosphinodithioate] is a novel and perfect hydrogen sulfide (H2S) donor that is stable in vivo and in vitro. H2S, along with CO and NO, has been recognized as the third physiological gas signaling molecule that plays an active role in fighting various lung infections. However, the mechanism by which GYY4137 affects cecal ligation and puncture (CLP)-induced acute lung injury (ALI) is not understood. This study aimed to investigate whether GYY4137 inhibits the activation of the pyrin domain-containing protein 3 (NLRP3) inflammasome by inhibiting the PDGFRβ/Akt/NF-κB pathway. The model of CLP-induced ALI was established in vivo. The mice were subsequently treated with GYY4137 (25 μg/g and 50 μg/g) to simulate the realistic conditions of pathogenesis. Western blotting and immunohistochemical staining were used to examine protein expression, hematoxylin and eosin staining was used for the histopathological analysis, and the levels of inflammatory factors were determined using enzyme-linked immunosorbent assays (ELISAs). GYY4137 significantly increased the 7-day survival of mice with septic peritonitis and protected against CLP-induced ALI, including decreasing neutrophil infiltration, improving sepsis-induced lung histopathological changes, diminishing lung tissue damage, and attenuating the severity of lung injury in mice. The protective effect of GYY4137 was undoubtedly dose-dependent. We discovered that GYY4137 reduced the levels of the p-PDGFRβ, p-NF-κB, ASC, NLRP3, caspase-1, and p-Akt proteins in septic mouse lung tissue. Akt regulates the generation of proinflammatory cytokines in endotoxemia-associated ALI by enhancing the nuclear translocation of NF-κB. These results indicate a new molecular mechanism explaining the effect of GYY4137 on the treatment of CLP-induced ALI in mice.

Li J ，Ma J ，Li M ，Tao J ，Chen J ，Yao C ，Yao S ... -  《-》

Hydrogen sulfide ameliorated lipopolysaccharide-induced acute lung injury by inhibiting autophagy through PI3K/Akt/mTOR pathway in mice.

Recent studies reported that hydrogen sulfide (H2S) is an effective agent for the prevention and treatment of acute lung injury (ALI). But the underlying mechanisms have not been understood clearly. In this study, we explored the possible mechanism from the perspective of autophagy regulation. A mouse model of ALI and alveolar type II epithelial cells (MLE-12 cells) injury was induced using lipopolysaccharide (LPS). Expression of Beclin 1 and the conversion of LC3I to LC3II were detected to evaluate the activity of autophagy. Lung histopathological changes, wet/dry (W/D) ratio, pro-inflammatory cytokines TNF-α, IL-1β and protein content in bronchoalveolar lavage fluid (BALF), cell viability and lactic dehydrogenase (LDH) in the culture medium were determined to evaluate the severity of ALI. The activity of PI3K/Akt/mTOR pathway was detected to explore the possible mechanisms involved in the regulation of autophagy by H2S. The expression of Beclin 1 and the conversion of LC3I to LC3II were significantly increased after LPS treatment and reversed by H2S both in vivo and in vitro. Lung histopathological changes, W/D ratio, TNF-α, IL-1β and protein content in BALF induced by LPS were effectively ameliorated by H2S and autophagy inhibitor 3-methyladenine. The in vitro results showed that H2S and 3-methyladenine also attenuated LPS-induced cell viability decrease and LDH release. Furthermore, H2S effectively reversed LPS-induced PI3K/Akt/mTOR signaling pathway inhibition. Autophagy inhibition through PI3K/Akt/mTOR pathway was involved in H2S prevention of LPS-induced ALI in mice.

Xu X ，Li H ，Gong Y ，Zheng H ，Zhao D ... -  《-》

Attenuation of Sepsis-Induced Acute Kidney Injury by Exogenous H(2)S via Inhibition of Ferroptosis.

Zhang L ，Rao J ，Liu X ，Wang X ，Wang C ，Fu S ，Xiao J ... -  《MOLECULES》

Hydrogen sulfide inhibits endoplasmic reticulum stress through the GRP78/mTOR pathway in rat chondrocytes subjected to oxidative stress.

Wu J ，Yang F ，Zhang X ，Chen G ，Zou J ，Yin L ，Yang D ... -  《-》