Identification of a Novel HIF-1α-α_Mβ₂ Integrin-NET Axis in Fibrotic Interstitial Lung Disease

Area of Science:

• Pulmonary Medicine
• Immunology
• Cell Biology

Background:

• Neutrophilic inflammation is linked to mortality in fibrotic interstitial lung disease (ILD), especially idiopathic pulmonary fibrosis (IPF).
• Mechanisms driving neutrophil activation in ILD, including the role of hypoxia, are not fully understood.

Purpose of the Study:

• To investigate neutrophil activation in ILD and the specific impact of hypoxia.
• To identify key molecular pathways involved in neutrophil dysfunction in fibrotic lung disease.

Main Methods:

• Analysis of lung biopsies and bronchoalveolar lavage (BAL) fluid from ILD patients.
• Ex vivo studies using neutrophils from healthy volunteers and ILD patients.
• Intracellular staining for HIF-1α, assessment of neutrophil extracellular trap (NET) release, adhesion, and trans-endothelial migration under hypoxic conditions.

Main Results:

• HIF-1α stabilization was observed in neutrophils and endothelial cells in ILD lung biopsies.
• Hypoxia significantly enhanced NET release, neutrophil adhesion, and trans-endothelial migration, alongside increased αM and αX integrin expression.
• NET formation was mediated by αMβ2 integrin activation, and NET-like structures were found in IPF lungs and ILD patient BAL fluid.

Conclusions:

• Upregulation of HIF-1α likely promotes neutrophil recruitment and activation in the lung interstitium via β2 integrin activation.
• A novel HIF-1α-αMβ2 integrin axis in NET formation is identified, representing a potential therapeutic target for fibrotic ILD.