Enhanced acute lung damage following corticosteroid treatment

Area of Science:

• Pulmonary Pathology
• Toxicology
• Pharmacology

Background:

• Butylated hydroxytoluene (BHT) induces lung injury characterized by alveolar epithelial cell damage.
• Corticosteroids are often used to manage inflammatory lung conditions.

Purpose of the Study:

• To investigate the effects of corticosteroid administration on BHT-induced lung injury in mice.
• To determine the role of prednisolone dosage and timing in exacerbating or mitigating lung damage and fibrosis.

Main Methods:

• Mice were treated with butylated hydroxytoluene (BHT) to induce lung injury.
• Prednisolone or methylprednisolone acetate was administered at varying doses and time points after BHT exposure.
• Lung histology, hydroxyproline levels (a marker of fibrosis), and DNA synthesis were assessed at different time points.

Main Results:

• Prednisolone (30 mg/kg twice daily on Days 1-5 post-BHT) significantly exacerbated lung damage, leading to severe interstitial pneumonitis and consolidation.
• Fibrotic changes, indicated by increased lung hydroxyproline, were dose- and time-dependent, occurring with specific prednisolone regimens.
• While histology showed resolution of pneumonitis by 60 days, biochemical fibrotic changes persisted.
• Single doses of corticosteroids inhibited BHT-induced lung DNA synthesis, with prolonged dual daily dosing showing a rebound effect.

Conclusions:

• Corticosteroid administration, particularly with specific dosing regimens, can significantly worsen BHT-induced lung injury and promote persistent fibrosis.
• The timing and dosage of corticosteroid treatment are crucial factors influencing the development and resolution of lung damage and fibrosis.
• These findings highlight potential risks of corticosteroid use in certain lung injury contexts.