Abstract
Introduction: Dual anti-platelet therapy (DAPT) is routinely administered to inhibit platelet aggregation in acute myocardial infarction (AMI) and, in doing so, reduces the risk of recurrent adverse cardiovascular events. Alongside platelets, neutrophils are also key mediators of inflammation during AMI, both secreting cytokines and chemokines and producing Neutrophil Extracellular Traps (NETs). While DAPT is known to mediate off-target anti-inflammatory effects, the extent to which DAPT affects neutrophil function is not well understood. Objective: To investigate the effects of DAPT on neutrophil-mediated inflammation.
Methods: Neutrophils were isolated from whole blood of ten healthy subjects pre- and post-DAPT (ticagrelor and aspirin) treatment and NET formation in response to classical NET-inducing agonists (PMA and ionomycin) was measured by SYTOX Green fluorescence and MPO activity. Cytokine and chemokine production following stimulation with an activating agonist (FSL-1) was measured by cytometric bead array and reported as median fluorescence intensity (MFI). DAPT was effective in inhibiting platelet aggregation in response to AA and ADP.
Results: NET formation in response to ionomycin, but not PMA, was greater in DAPT-treated neutrophils compared to treatment-naïve neutrophils (69.9 % ± 30.66 SEM). Levels of inflammatory mediators were also markedly different pre- and post- DAPT treatment. For example, MFI of IL-8 was decreased by 18% ± 9.97 SEM post-DAPT compared with pre-DAPT MFI, while MFI of IL-12p and IFN-α were significantly increased (32.54% ± 12.12 SEM, 58.68% ± 18.72 SEM respectively) compared to pre-DAPT.
Conclusion: DAPT primes neutrophils for inducing some, but not all, NETotic pathways and releasing some, but not all, inflammatory mediators. This suggests that our primary strategy for inhibiting platelet aggregation in AMI does not provide broad off-target anti-inflammatory effects on neutrophils. In fact, DAPT may encourage a pro-inflammatory neutrophil phenotype.