Hypoxia synergizes cGAS-STING activation and AKT1 phosphorylation to drive pulmonary inflammation in one-lung ventilation: therapeutic attenuation by RU.521 and MK2206
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Published on: March 21, 2021
Jiangsheng Zhang1, Yuntao Zou1, Dongni Chen1
1Department of Thoracic Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China.
Background:
To explore the mechanisms involved in hypoxia-induced acute lung injury (ALI) and oxidative stress during one-lung ventilation (OLV) in order to find pharmacological interventions that can attenuate OLV injury.
Methods:
An OLV model was established in Sprague-Dawley (SD) rats. Lung tissue damage was assessed via histological staining and by quantifying inflammatory factors (TNF-α, IL-6, IL-1β) using qPCR. High-throughput transcriptome sequencing of left lung tissues from the OLV group and the two-lung ventilation (TLV) group screened for differentially expressed genes (DEGs) in pathways and biological functions associated with lung injury. Furthermore, a hypoxia reoxygenation (H/R) model was established using the mouse lung epithelial cell line (MLE-12) for further mechanism mapping and validation in vitro.
Results:
Transcriptomic analysis revealed upregulated gene signatures linked to DNA damage, mitochondrial membrane permeabilization, oxidative stress, and innate immune activation. KEGG enrichment identified innate immune pathways, specifically cytosolic DNA sensing. Subsequent in vivo and in vitro studies confirmed cGAS-STING pathway activation, characterized by increased expression and enhanced phosphorylation of downstream components. Genetic knockdown of cGAS or AKT1 (a kinase required for downstream phosphorylation of key cGAS-STING downstream effectors) suppressed cGAS-STING pathway signaling.
Conclusion:
This study highlights that innate immunity contributes to lung tissue damage during OLV. Hypoxia-induced DNA damage activates the cytoplasmic DNA-sensing cGAS-STING pathway. Subsequently, AKT1 modulates the downstream phosphorylation of TBK1, IRF3, and NF-κB, thereby promoting DNA damage-associated inflammation in alveolar epithelial cells. Pharmacologically, both the cGAS inhibitor RU.521 and AKT1 inhibitor MK2206 attenuated cGAS-STING-mediated inflammation and mitigated hypoxia-induced oxidative stress in alveolar epithelia.
Clinical Trial Number:
Not applicable.
Insights
Hypoxia during one-lung ventilation triggers DNA damage and activates the cGAS-STING innate immune pathway, leading to lung injury. Inhibiting cGAS or AKT1 can reduce this inflammation and oxidative stress.
Area of Science:
- Pulmonary Medicine
- Immunology
- Molecular Biology
Background:
- One-lung ventilation (OLV) can induce acute lung injury (ALI) and oxidative stress.
- Understanding the underlying mechanisms is crucial for developing effective pharmacological interventions.
Purpose of the Study:
- To investigate the molecular mechanisms of hypoxia-induced ALI and oxidative stress during OLV.
- To identify potential pharmacological targets for attenuating OLV-related lung injury.
Main Methods:
- Established an OLV rat model and a hypoxia-reoxygenation (H/R) cell model.
- Assessed lung tissue damage and quantified inflammatory factors (TNF-α, IL-6, IL-1β).
- Utilized high-throughput transcriptome sequencing and in vitro validation to identify key pathways and genes.
Main Results:
- Transcriptomic analysis revealed upregulated signatures related to DNA damage, oxidative stress, and innate immune activation.
- Confirmed activation of the cGAS-STING pathway, involving DNA damage and innate immune responses.
- Demonstrated that genetic knockdown of cGAS or AKT1 suppressed cGAS-STING signaling.
Conclusions:
- Innate immunity contributes significantly to OLV-induced lung tissue damage.
- Hypoxia-induced DNA damage activates the cGAS-STING pathway, with AKT1 modulating downstream signaling.
- Pharmacological inhibition of cGAS (RU.521) or AKT1 (MK2206) effectively reduced inflammation and oxidative stress.
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