Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Suppression of Ventilation-Induced Diaphragm Fibrosis through the Phosphoinositide 3-Kinase-γ in a Murine Bleomycin-Induced Acute Lung Injury Medel

Version 1 : Received: 17 April 2024 / Approved: 18 April 2024 / Online: 18 April 2024 (10:06:43 CEST)

How to cite: Li, L.; Yu, C.; Huang, C.; Wu, H.; Chu, C.; Liu, P.; Liu, Y. Suppression of Ventilation-Induced Diaphragm Fibrosis through the Phosphoinositide 3-Kinase-γ in a Murine Bleomycin-Induced Acute Lung Injury Medel. Preprints 2024, 2024041231. https://doi.org/10.20944/preprints202404.1231.v1 Li, L.; Yu, C.; Huang, C.; Wu, H.; Chu, C.; Liu, P.; Liu, Y. Suppression of Ventilation-Induced Diaphragm Fibrosis through the Phosphoinositide 3-Kinase-γ in a Murine Bleomycin-Induced Acute Lung Injury Medel. Preprints 2024, 2024041231. https://doi.org/10.20944/preprints202404.1231.v1

Abstract

Mechanical ventilation (MV), used in patients with acute lung injury (ALI), induces diaphragmatic myofiber atrophy and contractile inactivity, termed ventilator-induced diaphragm dysfunction. Phosphoinositide 3-kinase- (PI3K-) is crucial in modulating fibrogenesis during the reparative phase of ALI; however, the mechanisms regulating the interactions among MV, myofiber fibrosis, and PI3K- remain unclear. We hypothesized MV with or without bleomycin treatment would increase diaphragm muscle fibrosis through the PI3K- pathway. Five days after receiving a single bolus of 0.075 units bleomycin intratracheally, C57BL/6 mice were exposed to 6 or 10 mL/kg MV for 8 h after receiving 5 mg/kg of AS605240 intraperitoneally. In wild-type mice, bleomycin exposure followed by MV 10 mL/kg prompted significant increases in disruptions of diaphragmatic myofibrillar organization, transforming growth factor-1, oxidative loads, Masson’s trichrome staining, extracellular collagen levels, positive staining of -smooth muscle actin, PI3K- expression, and myonuclear apoptosis (P < 0.05). Decreased diaphragm contractility and peroxisome proliferator activated receptor- coactivator-1 levels were also observed (P < 0.05). MV-augmented bleomycin-induced diaphragm fibrosis and myonuclear apoptosis were attenuated in PI3K-γ-deficient mice and through AS605240-induced inhibition of PI3K- activity (P < 0.05). MV-augmented diaphragm fibrosis after bleomycin-induced ALI is partially mediated through PI3K-γ. Therapy targeting PI3K-γ may ameliorate MV-associated diaphragm fibrosis.

Keywords

apoptosis; diaphragm fibrosis; phosphoinositide 3-kinase-g; ventilator-induced diaphragm dysfunction

Subject

Medicine and Pharmacology, Pulmonary and Respiratory Medicine

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