ERS 2024: Anti-inflammatory Effect of PDE3 or 4 Inhibitors Ensifetrine in Peripheral Blood Mononuclear Cells from COPD Patients
Speaker: Simon Lea
Inhibition of Phosphodiesterase 3 (PDE3) and Phosphodiesterase 4 (PDE4) is associated with the upregulation of cyclic Adenosine Monophosphate (cAMP) and cyclic Guanosine Monophosphate (cGMP), which respectively signal a reduction in inflammatory mediators such as Tumor Necrosis Factor Alpha (TNF-α) and Interferon Gamma, as well as induce bronchodilation in airway smooth muscle and reduce apoptosis and cell death induced by oxidative stress. Ensifentrine, which targets both pathways, has been shown clinically to induce bronchodilation and exhibit anti-inflammatory effects.
The study aimed to further explore these anti-inflammatory effects using a Peripheral Blood Mononuclear Cell (PBMC) model from Chronic Obstructive Pulmonary Disease (COPD) patients and to assess the anti-oxidative stress effects of Ensifentrine in these cells. The drugs utilized in these experiments included Ensifentrine, the PDE3/4 inhibitor; PDE4 inhibitors such as Roflumilast and the compound GSK256066; and Dexamethasone as a corticosteroid comparator. Results showed that TNF-alpha production induced by Lipopolysaccharides (LPS) was inhibited dose-dependently by Dexamethasone, with significant inhibition observed at higher concentrations. PDE4 inhibitors (Roflumilast and GSK256066) and Ensifentrine also demonstrated dose-dependent inhibition of TNF-alpha, with significant effects at top concentrations. The maximal effects of all compounds were similar, but Ensifentrine exhibited lower potency than the other compounds, as evidenced by higher IC50 values. Despite this, the maximal effect at the top concentration was comparable.
In terms of T cell activation and interferon-gamma induction, all compounds showed significant inhibition at higher concentrations. The oxidative stress effects were assessed using hydrogen peroxide, which led to a reduction in the anti-apoptotic gene Myeloid leukemia 1 (MCL-1), an increase in the pro-apoptotic gene Bcl-2-associated X-protein (Bax), and induction of caspase activity associated with apoptosis. Ensifentrine significantly reversed these effects, resulting in reduced apoptosis and increased cell viability. In conclusion, Ensifentrine demonstrates anti-inflammatory effects with a similar maximal effect but lower potency than PDE4 inhibitors. Ensifentrine also protects against oxidative stress by increasing anti-apoptosis gene expression, reducing caspase activity, and ultimately decreasing apoptosis and cell death.
A question was asked about the methods used for cell viability and apoptosis markers. The apoptosis markers were assessed through PCR, while cell viability was measured using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and Lactate Dehydrogenase assays. The staining of apoptosis was also evaluated using TUNEL (Terminal deoxynucleotidyl transferase dUTP nick end labeling). The apoptosis experiments and oxidative stress assessments were conducted using PBMCs from COPD patients. However, TNF induction experiments involved healthy and COPD patients, with no significant differences observed between the two groups. Despite the small sample size, the method remained effective for COPD patients.
European Respiratory Society Congress (ERS) 2024, 7–11 September, Vienna, Austria.
