Ticagrelor Reduces Thromboinflammatory Markers in Patients With Pneumonia

Abstract

Despite treatment advances for sepsis and pneumonia, significant improvements in outcome have not been realized. Antiplatelet therapy may improve outcome in pneumonia and sepsis. In this study, the authors show that ticagrelor reduced leukocytes with attached platelets as well as the inflammatory biomarker interleukin (IL)-6. Pneumonia patients receiving ticagrelor required less supplemental oxygen and lung function tests trended toward improvement. Disruption of the P2Y₁₂ receptor in a murine model protected against inflammatory response, lung permeability, and mortality. Results indicate a mechanistic link between platelets, leukocytes, and lung injury in settings of pneumonia and sepsis, and suggest possible therapeutic approaches to reduce complications.(Targeting Platelet-Leukocyte Aggregates in Pneumonia With Ticagrelor [XANTHIPPE]; NCT01883869).

Keywords: ADP, adenosine diphosphate; CAP, community-acquired pneumonia; CI, confidence interval; COPD, chronic obstructive pulmonary disease; ELISA, enzyme-linked immunosorbent assay; FEV-1, forced expiratory volume in 1 s; HAP, hospital-acquired pneumonia; IL, interleukin; IQR, interquartile range; Kfc, capillary filtration coefficient; LPS, lipopolysaccharide; LTA, light transmission aggregometry; MPO, myeloperoxidase; MVV, maximum ventilation velocity; NE, neutrophil elastase; NET, neutrophil extracellular trap; OR, odds ratio; PRP, platelet-rich plasma; TNF, tumor necrosis factor; TRAP, thrombin receptor activating peptide; WT, wild-type; dsDNA, doubled-stranded DNA; inflammation; leukocytes; platelets; pneumonia; sepsis.

Graphical abstract

Figure 1

Ticagrelor Reduces Ex Vivo ADP-Induced Platelet Aggregation in Pneumonia Patients Maximum platelet aggregation was measured by light transmission aggregometry in PRP in response to 5 μmol/l ADP (A) and 15 μmol/l TRAP (C). Area under the curve values in the Multiplate assay are shown with ADP (B) or TRAP (D) as an agonist. Patients randomized to placebo are represented by open circles and patients randomized to ticagrelor are represented by filled circles. A significant difference between groups on the change from baseline to 24 h is indicated by an asterisk. ADP = adenosine diphosphate; AU = arbitrary units; BL = baseline; LTA = light transmission aggregometry; TRAP = thrombin receptor activating peptide

Figure 2

Ticagrelor Reduces Platelet–Leukocyte Aggregates The percentage of leukocytes with attached platelets for each subject is plotted at baseline (BL) and at 24 h in patients given placebo (A, open circles) and ticagrelor (A, filled circles). A significant difference between groups on the change from baseline to 24 h is indicated by an asterisk. Delta change of platelet–leukocyte aggregates at 24 h (compared with baseline) is represented for patients randomized to placebo (B, open circles and top dashed line) and ticagrelor (B, filled circles and bottom dashed line).

Figure 3

Ticagrelor and NETosis Biomarkers in Pneumonia Patients The delta change at 24 and 48 h after dosing for the MPO-NE NETosis assay (A) and circulating dsDNA (B) were measured in placebo patients (open circles) and ticagrelor patients (filled circles) that had samples through 48 h after dosing. Significant changes are indicated by an asterisk. dsDNA = doubled-stranded DNA; MPO = myeloperoxidase; NE = neutrophil elastase.

Figure 4

Ticagrelor and Lung Function Within 24 h in Pneumonia Patients Lung function was tested in subjects willing and able to undergo spirometry testing. Data were collected at baseline and at 24 h. Changes at 24 h from baseline (midline in all 3 graphs) are shown for tidal volume (A), FEV-1 (B), and MVV (C). Units reported are liters for tidal volume and FEV-1 (A, B) and liters per minute for MVV (C). Data from patients randomized to placebo are shown in the open boxes, whereas patients randomized to ticagrelor are represented in the shaded boxes. Each box represents the interquartile range (25% to 75%), whereas the whiskers represent the full range of the data. The vertical line in each interquartile range box represents the median value (note that the median for the placebo group in C overlaps with the midline). FEV-1 = forced expiratory volume in 1 s; MVV = maximum ventilation velocity.

Figure 5

Pneumonia Patients Taking Ticagrelor Became Less Reliant on Supplemental Oxygen Supplemental oxygen requirements were recorded from patient records. Data were collected at the time closest to when the patient received the study medication and 24 and 48 h following study dosage. Supplemental oxygen was recorded as none (room air), nasal cannula, and high-flow (HF) devices and mechanical ventilation. Patients randomized to ticagrelor demonstrated a progression to room air and away from supplemental oxygen (odds ratio [OR]: 1.08; 95% confidence interval [CI]: 1.01 to 1.15). Patients randomized to placebo did not change over 48 h after receiving the study dose (OR: 0.99; 95% CI: 0.95 to 1.04).

Figure 6

Ticagrelor Reduces Inflammation, Increases Lung Function, and Protects Against Mortality in a Murine Sepsis Model The concentrations of TNF-α (A) and IL-10 (B) at 0 h up to 8 h post-LPS injection are graphed for control mice and mice treated with ticagrelor or clopidogrel (A and B, reported as mean with bar indicating SE). Significant difference over the time course compared with the control is indicated by an asterisk in A and B. Survival curves of wild-type (WT) mice and P2y12^−/− mice injected with LPS are plotted in C, whereas D shows survival curves of WT and P2y12^−/− mice treated with clopidogrel or ticagrelor (T10) before LPS injection. Significance between mutant and WT (A) and P2Y₁₂ antagonist treated and untreated (D) is indicated by an asterisk. Capillary filtration coefficients (K_FC) are graphed for control mice and mice treated with ticagrelor or clopidogrel (E, reported as mean with bar indicating SE). Significant differences between treatment group and control are indicated by an asterisk. IL = interleukin; LPS = lipopolysaccharide; TNF = tumor necrosis factor.