Faculty Bibliography

BACKGROUND: Monocyte-platelet aggregates (MPAs) represent the crossroads between thrombosis and inflammation, and targeting this axis may suppress thromboinflammation. While antiplatelet therapy (APT) reduces platelet-platelet aggregation and thrombosis, its effects on MPA and platelet effector properties on monocytes are uncertain. OBJECTIVES/OBJECTIVE: To analyze the effect of platelets on monocyte activation and APT on MPA and platelet-induced monocyte activation. METHODS:, GP IIb/IIIa, and COX-1 inhibitors and assessed for platelet and monocyte activity via flow cytometry. RNA-Seq of monocytes incubated with platelets was used to identify platelet-induced monocyte transcripts and was validated by RT-qPCR in monocyte-PR co-incubation ± APT. RESULTS:inhibition attenuates platelet-induced monocyte activation.

INTRODUCTION:Thromboinflammatory complications are well described sequalae of Coronavirus Disease 2019 (COVID-19), and there is evidence of both hyperreactive platelet and inflammatory neutrophil biology that contributes to the thromoinflammatory milieu. It has been demonstrated in other thromboinflammatory diseases that the circulating environment may affect cellular behavior, but what role this environment exerts on platelets and neutrophils in COVID-19 remains unknown. We tested the hypotheses that 1) plasma from COVID-19 patients can induce a prothrombotic platelet functional phenotype, and 2) contents released from platelets (platelet releasate) from COVID-19 patients can induce a proinflammatory neutrophil phenotype. METHODS:We treated platelets with COVID-19 patient and disease control plasma, and measured their aggregation response to collagen and adhesion in a microfluidic parallel plate flow chamber coated with collagen and thromboplastin. We exposed healthy neutrophils to platelet releasate from COVID-19 patients and disease controls and measured neutrophil extracellular trap formation and performed RNA sequencing. RESULTS:. Neither disease condition increased the number of platelets adhered to a collagen and thromboplastin coated parallel plate flow chamber, but both markedly reduced platelet size. COVID-19 patient platelet releasate increased myeloperoxidasedeoxyribonucleic acid complexes and induced changes to neutrophil gene expression. DISCUSSION:Together these results suggest aspects of the soluble environment circulating platelets, and that the contents released from those neutrophil behavior independent of direct cellular contact.

BACKGROUND:Early life stress (ELS) is associated with increased morbidity and mortality across the lifecourse. Studies observing a relationship between ELS and stress physiology (cortisol), may help explain the connection to poor health outcomes, but have been limited by cortisol measures used. PURPOSE/OBJECTIVE:We examined the association between ELS measured by a Risky Family (RF) environment questionnaire, and adult diurnal cortisol profile inclusive of multiple cortisol measures. METHODS:RF and cortisol were collected from Coronary Artery Risk Development in Young Adults Study participants at follow-up (Year 15). Complete case (n = 672) data were included in multi-variable regression analyses with log transformed cortisol measures (outcomes) including wake-up cortisol, cortisol awakening response [CAR], AUC and five other cortisol diurnal curve measures. RESULTS:Participants were age 39.9 + /- 3.7 years and 51.6% Black. For every 1 unit increase in RF, there was a 1.4% greater wake-up cortisol and flatter CAR after adjustment for age, sex, income, and smoking (B=0.014, p = 0.023; B=-0.014, p = 0.028, respectively). Each unit increase in caregiver warmth/affection was associated with a 6.9% higher (steeper) CAR (B=0.069, p = 0.03). Results remained significant after adjusting for other covariates except social support in adulthood. An interaction between child abuse and caregiver warmth was nearly significant (p = 0.068), such that for those with exposure to the greatest caregiver warmth and lowest child abuse, CAR was steepest CONCLUSIONS: We demonstrate that ELS is associated with altered cortisol regulation in adulthood. However, further research is needed to assess how healthy relationships throughout the life course may modulate cortisol regulation in adulthood.

OBJECTIVE:To compare rates of clopidogrel response among patients receiving medication produced by 2 different manufacturers after acute coronary syndrome (ACS) and/or percutaneous coronary intervention. METHODS:This quality-improvement project included 515 adult patients receiving clopidogrel for ACS or ischemic heart disease and referred for coronary angiography/ percutaneous coronary intervention. The project was divided into 2 phases: (1) retrospective collection of baseline data (April 2019-October 2020); and (2) two 12-week, prospective phases in which all clopidogrel in the hospital was restricted to a single manufacturer at a time (November 2020-May 2021). The primary outcome was clopidogrel response measured by platelet function testing, defined as adenosine diphosphate (ADP) response <40% on light transmission aggregometry. RESULTS:Of 515 total patients included in both phases (mean age, 64.5 ± 11.4 years; 351 men [68.2%]; 450 with ACS [87.4%]), 52% were found to be clopidogrel responders based on results of platelet function testing. Among 135 patients in the prospective phase, there was a significantly lower proportion of patients who were clopidogrel responders in the Manufacturer 1 group compared with the Manufacturer 2 group (34.8% vs 55.1%, respectively; P=.03). After adjustment for age, sex, body mass index, aspirin response, therapeutic hypothermia, left heart catheterization indication, clopidogrel loading dose, time between loading dose and lab measurement, and manufacturer, aspirin response (odds ratio 0.96; 95% confidence interval, 0.95-0.97; P<.001) and manufacturer (odds ratio, 2.45; 95% confidence interval, 1.18-5.22; P=.02) were associated with clopidogrel response. CONCLUSIONS:In a large public hospital, we observed that pharmacodynamic response to clopidogrel varied by drug manufacturer. Further investigation and/or regulation is needed to minimize inter-manufacturer variability.

BACKGROUND:Posttraumatic venous thromboembolism (VTE) remains prevalent in severely injured patients despite chemoprophylaxis. Importantly, although platelets are central to thrombosis, they are not routinely targeted in prevention of posttraumatic VTE. Furthermore, platelets from injured patients show ex vivo evidence of increased activation yet impaired aggregation, consistent with functional exhaustion. However, the relationship of this platelet functional phenotype with development of posttraumatic VTE is unknown. We hypothesized that, following injury, impaired ex vivo platelet aggregation (PA) is associated with the development of posttraumatic VTE. METHODS:We performed a secondary analysis of 133 severely injured patients from a prospective observational study investigating coagulation and inflammation (2011-2019). Platelet aggregation in response to stimulation with adenosine diphosphate (ADP), collagen, and thrombin was measured at presentation (preresuscitation) and 24 hours (postresuscitation). Viscoelastic clot strength and lysis were measured in parallel by thromboelastography. Multivariable regression examined relationships between PA at presentation, 24 hours, and the change (δ) in PA between presentation and 24 hours with development of VTE. RESULTS:The 133 patients were severely injured (median Injury Severity Score, 25), and 14% developed VTE (all >48 hours after admission). At presentation, platelet count and PA were not significantly different between those with and without incident VTE. However, at 24 hours, those who subsequently developed VTE had significantly lower platelet counts (126 × 10 9 /L vs. 164 × 10 9 /L, p = 0.01) and lower PA in response to ADP ( p < 0.05), collagen ( p < 0.05), and thrombin ( p = 0.06). Importantly, the magnitude of decrease in PA (δ) from presentation to 24 hours was independently associated with development of VTE (adjusted odds ratios per 10 aggregation unit decrease: δ-ADP, 1.31 [ p = 0.03]; δ-collagen, 1.36 [ p = 0.01]; δ-thrombin, 1.41 [ p < 0.01]). CONCLUSION:Severely injured patients with decreasing ex vivo measures of PA despite resuscitation have an increased risk of developing VTE. This may have implications for predicting development of VTE and for studying platelet targeted chemoprophylaxis regimens. LEVEL OF EVIDENCE:Prognostic/Epidemiological; Level III.

Patients with HIV exhibit platelet activation and increased risk of cardiovascular disease, the prevention of which is not fully known. Fifty-five HIV-positive patients were randomized to clopidogrel, aspirin, or no-treatment for 14 days, and the platelet phenotype and ability to induce endothelial inflammation assessed. Clopidogrel as opposed to aspirin and no-treatment reduced platelet activation (P-selectin and PAC-1 expression). Compared with baseline, platelet-induced proinflammatory transcript expression of cultured endothelial cells were reduced in those assigned to clopidogrel, with no change in the aspirin and no-treatment arms. In HIV, clinical trials of clopidogrel to prevent cardiovascular disease are warranted. (Antiplatelet Therapy in HIV; NCT02559414)

BACKGROUND:Male sex, elevated troponin levels, and elevated D-dimer levels are associated with more complicated COVID-19 illness and greater mortality; however, while there are known sex differences in the prognostic value of troponin and D-dimer in other disease states, it is unknown whether they exist in the setting of COVID-19. OBJECTIVE:We assessed whether sex modified the relationship between troponin, D-dimer, and severe COVID-19 illness (defined as mechanical ventilation, ICU admission or transfer, discharge to hospice, or death). METHODS:We conducted a retrospective cohort study of patients hospitalized with COVID-19 at a large, academic health system. We used multivariable regression to assess associations between sex, troponin, D-dimer, and severe COVID-19 illness, adjusting for demographic, clinical, and laboratory covariates. To test whether sex modified the relationship between severe COVID-19 illness and troponin or D-dimer, models with interaction terms were utilized. RESULTS:Among 4,574 patients hospitalized with COVID-19, male sex was associated with higher levels of troponin and greater odds of severe COVID-19 illness, but lower levels of initial D-dimer when compared with female sex. While sex did not modify the relationship between troponin level and severe COVID-19 illness, peak D-dimer level was more strongly associated with severe COVID-19 illness in male patients compared to female patients (males: OR=2.91, 95%CI=2.63-2.34, p<0.001; females: OR=2.31, 95%CI=2.04-2.63, p<0.001; p-interaction=0.005). CONCLUSION/CONCLUSIONS:Sex did not modify the association between troponin level and severe COVID-19 illness, but did modify the association between peak D-dimer and severe COVID-19 illness, suggesting greater prognostic value for D-dimer in males with COVID-19.

Prior observational studies suggest rivaroxaban is safe and effective among patients with morbid obesity who suffered a venous thromboembolism (VTE) event, but existing data are more limited in the broader population of VTE patients with obesity. This study assessed VTE recurrence, major bleeding, healthcare resource utilization, and healthcare costs among VTE patients with obesity who received rivaroxaban versus warfarin. VTE patients with obesity who initiated rivaroxaban or warfarin after a first VTE (index date) were identified from the IQVIA PharMetrics® Plus database (01/02/2011-09/30/2019). The follow-up period spanned from the index date until health plan disenrollment, end of data availability, cancer diagnosis/treatment, end of the 12 month post-index period, or (for the analysis of major bleeding) anticoagulant discontinuation or switch. Patient characteristics were balanced using inverse probability of treatment weighting. The weighted rivaroxaban (N = 8666) and warfarin cohorts (N = 5946) were well balanced (mean age = 51 years, females = 52%). Over a 9.6 months mean observation period, rivaroxaban users had a significantly lower risk of VTE recurrence [7.0% vs. 8.2%, HR(95% CI) = 0.85(0.75;0.97)] and a similar risk of major bleeding [4.1% vs. 3.6%, HR(95% CI) = 1.11(0.89;1.37)] relative to warfarin users at 12 months. Relative to warfarin users, rivaroxaban users had significantly fewer all-cause outpatient visits [RR(95% CI) = 0.71(0.70;0.74)]. The higher pharmacy costs incurred by rivaroxaban recipients (cost difference = $1252) were offset by lower medical costs (cost difference = - $2515, all p < 0.05) compared with warfarin recipients. Our findings suggest that rivaroxaban is safe and effective versus warfarin, and associated with lower medical costs among VTE patients with obesity.

Aspirin protects against atherothrombosis while increasing the risk of major bleeding. Although it is widely used to prevent cardiovascular disease (CVD), its benefit does not outweigh its risk for primary CVD prevention in large population settings. The recent United States Preventive Services Task Force guidelines on aspirin use to prevent CVD reflect this clinical tradeoff as well as the persistent struggle to define a population that would benefit from prophylactic aspirin therapy. Past clinical trials of primary CVD prevention with aspirin have not included consideration of a biomarker relevant to aspirin's mechanism of action, platelet inhibition. This approach is at odds with the paradigm used in other key areas of pharmacological CVD prevention, including antihypertensive and statin therapy, which combine cardiovascular risk assessment with the measurement of mechanistic biomarkers (eg, blood pressure and LDL [low-density lipoprotein]-cholesterol). Reliable methods for quantifying platelet activity, including light transmission aggregometry and platelet transcriptomics, exist and should be considered to identify individuals at elevated cardiovascular risk due to a hyperreactive platelet phenotype. Therefore, we propose a new, platelet-guided approach to the study of prophylactic aspirin therapy. We think that this new approach will reveal a population with hyperreactive platelets who will benefit most from primary CVD prevention with aspirin and usher in a new era of precision-guided antiplatelet therapy.