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Liposomal dexamethasone effectiveness in the treatment of hypersensitivity pneumonitis in mice
G M Tremblay1, H M Thérien, H Rocheleau
1Unité de recherche, Hôpital Laval, Université Laval, Sainte-Foy, Québec, Canada.
Abstract:
The effects of daily intranasal instillation of liposomal dexamethasone and free dexamethasone phosphate were compared in a murine model of hypersensitivity pneumonitis induced by Saccharopolyspora rectivirgula (formally known as Micropolyspora faeni). After 3 weeks of antigen and liposome instillations, lung response was evaluated by bronchoalveolar lavage cell counts, lung index and histopathology. Systemic absorption was evaluated by measuring plasma adrenocorticotropic hormone (ACTH) level. Free dexamethasone phosphate induced a dose-dependent response with the maximal effect reached at 1 mg kg-1. At 0.1 mg kg-1, liposomal dexamethasone had a greater effect than free dexamethasone phosphate on bronchoalveolar cells ml-1: 3.01 x 10(5) +/- 0.35 x 10(5) compared to 4.70 x 10(5) +/- 0.34 x 10(5), and lung index: 1.22 +/- 0.10 compared to 1.86 +/- 0.07. Effect on histopathology was similar. Plasma ACTH levels (pg ml-1) were: 75.1 +/- 14.0 for animals receiving antigen and free dexamethasone phosphate (0.2 mg kg-1), and 149.7 +/- 12.0 for animals receiving antigen and liposomal dexamethasone (0.2 mg kg-1). In conclusion, liposome-incorporated dexamethasone is efficient in the treatment of experimental hypersensitivity pneumonitis and, contrarily to free dexamethasone phosphate, does not inhibit ACTH secretion.
Insights
Liposomal dexamethasone effectively treats experimental hypersensitivity pneumonitis in mice. Unlike free dexamethasone phosphate, it does not suppress adrenocorticotropic hormone (ACTH) levels, indicating a safer systemic profile.
Area of Science:
- Pulmonary Medicine
- Pharmacology
- Immunology
Background:
- Hypersensitivity pneumonitis (HP) is an immune-mediated lung disease.
- Dexamethasone is a common treatment, but systemic side effects are a concern.
- Liposomal drug delivery may offer targeted therapeutic benefits with reduced systemic absorption.
Purpose of the Study:
- To compare the efficacy of intranasal liposomal dexamethasone versus free dexamethasone phosphate in a murine model of HP.
- To evaluate the impact of both treatments on lung inflammation and systemic hormonal levels.
Main Methods:
- A murine model of HP was established using Saccharopolyspora rectivirgula.
- Animals received daily intranasal instillations of liposomal or free dexamethasone phosphate.
- Lung inflammation was assessed via bronchoalveolar lavage cell counts, lung index, and histopathology.
- Systemic absorption was evaluated by measuring plasma adrenocorticotropic hormone (ACTH) levels.
Main Results:
- Liposomal dexamethasone showed greater efficacy in reducing bronchoalveolar lavage cells and lung index compared to free dexamethasone phosphate at equivalent doses.
- Both formulations demonstrated similar effects on lung histopathology.
- Free dexamethasone phosphate significantly suppressed plasma ACTH levels, while liposomal dexamethasone did not.
Conclusions:
- Intranasal liposomal dexamethasone is an effective treatment for experimental hypersensitivity pneumonitis.
- Liposomal formulation offers a potential advantage by avoiding the suppression of ACTH secretion, suggesting a more favorable systemic safety profile compared to free dexamethasone phosphate.