Macrophage inflammatory protein-1 alpha expression in interstitial lung disease

Area of Science:

• Pulmonary Medicine
• Immunology
• Cell Biology

Background:

• Chronic inflammatory lung diseases, including sarcoidosis and idiopathic pulmonary fibrosis (IPF), involve mononuclear phagocyte (M phi) recruitment and activation.
• Macrophage inflammatory protein-1 alpha (MIP-1 alpha) is a peptide with leukocyte-activating and chemotactic properties, suggesting a potential role in these diseases.

Purpose of the Study:

• To investigate the role of MIP-1 alpha in sarcoidosis and IPF.
• To determine if MIP-1 alpha levels and activity are increased in patients with these lung diseases.
• To identify the cellular sources of MIP-1 alpha within the lung.

Main Methods:

• Quantification of MIP-1 alpha in bronchoalveolar lavage fluid (BALF) from patients and healthy subjects.
• Assay of monocyte and neutrophil chemotactic activity in BALF, with and without MIP-1 alpha antibody inhibition.
• Immunohistochemical analysis of lung biopsies to detect MIP-1 alpha expression in various cell types.
• In vitro production of MIP-1 alpha by pulmonary fibroblasts.

Main Results:

• MIP-1 alpha was significantly elevated in BALF of sarcoidosis and IPF patients compared to healthy controls.
• BALF from sarcoidosis and IPF patients exhibited increased monocyte chemotactic activity, partially inhibited by anti-MIP-1 alpha antibodies.
• Immunohistochemistry revealed substantial MIP-1 alpha expression in alveolar and interstitial M phi, as well as interstitial fibroblasts in sarcoidosis and IPF lungs.
• Pulmonary fibroblasts from IPF patients produced more MIP-1 alpha upon IL-1 beta challenge than those from healthy individuals.

Conclusions:

• MIP-1 alpha is upregulated in the lung airspace and interstitium of patients with sarcoidosis and IPF.
• MIP-1 alpha likely contributes to the characteristic M phi activation and recruitment observed in these chronic inflammatory lung diseases.