Related Experiment Video
Updated: Jun 3, 2026
In Vivo Assessment of Alveolar Macrophage Efferocytosis Following Ozone Exposure
Published on: October 22, 2019
Oxidative stress-induced glucocorticoid resistance is prevented by dual PDE3/PDE4 inhibition in human alveolar
J Milara1, A Navarro, P Almudéver
1Research Unit, University General Hospital Consortium, Valencia, Spain. xmilara@hotmail.com
Background:
Oxidative stress is present in airway diseases such as severe asthma or Chronic Obstructive Pulmonary Disease and contributes to the low response to glucocorticoids through the down-regulation of histone deacetylase (HDAC) activity.
Objective:
To study the effects of the phosphodiesterase (PDE)-3 and 4 inhibitors and their combination vs. glucocorticoids in a model of lipopolysaccharide (LPS)-induced cytokine release in alveolar macrophages under oxidative stress conditions.
Methods:
Differentiated U937 or human alveolar macrophages were stimulated with H(2) O(2) (10-1000 μM) or cigarette smoke extract (CSE, 0-15%) for 4 h before LPS (0.5 μg/mL, 24 h) addition. In other experiments, cells were pre-treated with dexamethasone or budesonide (10(-9) -10(-6) M), with the PDE4 inhibitor rolipram (10(-9) -10(-5) M), PDE3 inhibitor motapizone (10 μM), 3',5'-cyclic monophosphate enhancer PGE(2) (10 nM), or with the combination of rolipram (10(-6) M)+PGE(2) (10 nM)+motapizone (10 μM) 15 min before oxidants. IL-8 and TNF-α were measured by ELISA and HDAC activity by a colorimetric assay.
Results:
Budesonide and dexamethasone produced a concentration-dependent inhibition of the LPS-induced IL-8 and TNF-α secretion with an E(max) about 90% of inhibition, which was reduced by approximately 30% in the presence of H(2)O(2) or CSE. Pre-treatment with rolipram, motapizone or PGE2 only reached about 20% of inhibition but was not affected by oxidative stress. In contrast, PDE4/PDE3 combination in presence of PGE2 effectively inhibited the LPS-induced cytokine secretion by about 90% and was not affected by oxidative stress. Combined PDE4 and PDE3 inhibition reversed glucocorticoid resistance under oxidative stress conditions. HDAC activity was reduced in the presence of oxidative stress, and in contrast to glucocorticoids, pre-treatment with PDE4/PDE3 combination was able to prevent HDAC inactivity.
Conclusions & Clinical Relevance:
This study shows that the combination of the PDE3/PDE4 inhibitors prevents alveolar macrophage activation in those situations of glucocorticoid resistance, which may be of potential interest to develop new effective anti-inflammatory drugs in airway diseases.
Insights
Combining phosphodiesterase (PDE) 3 and 4 inhibitors overcomes glucocorticoid resistance in airway diseases. This approach prevents alveolar macrophage activation under oxidative stress, offering potential for new anti-inflammatory therapies.
Area of Science:
- Pulmonology and Immunology
- Molecular Pharmacology
Background:
- Oxidative stress in severe asthma and COPD impairs glucocorticoid response by reducing histone deacetylase (HDAC) activity.
- Glucocorticoid resistance is a significant challenge in managing severe airway diseases.
Purpose of the Study:
- To investigate the efficacy of phosphodiesterase (PDE)-3 and 4 inhibitors, alone and in combination, against glucocorticoids.
- To assess their effects on lipopolysaccharide (LPS)-induced cytokine release in alveolar macrophages under oxidative stress.
Main Methods:
- Human alveolar macrophages were exposed to oxidative stress (H2O2 or cigarette smoke extract) and LPS.
- Cells were pre-treated with glucocorticoids (dexamethasone, budesonide), PDE4 inhibitor (rolipram), PDE3 inhibitor (motapizone), PGE2, or a combination of rolipram, PGE2, and motapizone.
- Interleukin-8 (IL-8), Tumor Necrosis Factor-alpha (TNF-α), and HDAC activity were measured.
Main Results:
- Glucocorticoids showed reduced efficacy in inhibiting LPS-induced cytokine release under oxidative stress.
- The combination of PDE3 and PDE4 inhibitors with PGE2 effectively inhibited cytokine secretion and preserved HDAC activity, independent of oxidative stress.
- Combined PDE inhibition reversed glucocorticoid resistance and prevented HDAC inactivity caused by oxidative stress.
Conclusions:
- The combination of PDE3 and PDE4 inhibitors effectively counteracts glucocorticoid resistance in alveolar macrophages during oxidative stress.
- This dual inhibition strategy prevents macrophage activation and may lead to novel anti-inflammatory treatments for airway diseases.
Related Concept Videos
01:20Chronic Obstructive Pulmonary Disease-II: Pathophysiology
Chronic Inflammation
01:25Antiasthma Drugs: Inhaled Corticosteroids and Glucocorticoids
ICS work through a multifaceted mechanism of action. They suppress the inflammatory response caused by the proliferation of TH cells. They also reduce the transcription of the IL-2 gene, which is involved in the...
01:26COPD: Management Using Bronchodilators and Corticosteroids
01:23Chronic Obstructive Pulmonary Disease II: Emphysema