Activation of MTOR in pulmonary epithelium promotes LPS-induced acute lung injury

Area of Science:

• Cellular biology
• Pulmonary medicine
• Immunology

Background:

• Mechanistic target of rapamycin (MTOR) and autophagy are critical cellular processes implicated in various diseases.
• Their specific roles in pulmonary epithelial cells during acute lung injury (ALI) remain largely unknown.
• Understanding these roles is crucial for developing effective treatments for lung disorders.

Purpose of the Study:

• To investigate the role of MTOR and autophagy in lipopolysaccharide (LPS)-induced ALI in pulmonary epithelial cells.
• To elucidate the signaling pathways involved in MTOR activation and its downstream effects on inflammation and autophagy.
• To evaluate the therapeutic potential of targeting MTOR in ALI.

Main Methods:

• Utilized mouse models and human bronchial epithelial (HBE) cells to study LPS-induced ALI.
• Assessed MTOR phosphorylation, autophagy markers (LC3B-II), and inflammatory cytokine expression (IL6, IL8).
• Employed genetic knockdown of MTOR and modulation of autophagy-related proteins, alongside toll-like receptor 4 (TLR4) and nuclear factor-kappa B (NFKB) signaling pathway analysis.

Main Results:

• LPS stimulation activated MTOR and suppressed autophagy in lung epithelial cells via TLR4 signaling.
• MTOR activation and autophagy inhibition promoted LPS-induced IL6 and IL8 expression through NFKB signaling.
• Genetic MTOR knockdown in epithelial cells attenuated ALI, reduced inflammation and edema, and improved survival in mice.
• Inhibition of autophagy exacerbated LPS-induced inflammation.

Conclusions:

• MTOR activation in pulmonary epithelial cells exacerbates LPS-induced ALI by downregulating autophagy and activating NFKB signaling.
• Targeting MTOR in lung epithelial cells presents a promising therapeutic strategy for bacterial-induced ALI.
• Further research into MTOR and autophagy pathways could lead to novel treatments for acute lung injury.