Aspirin attenuates platelet activation and immune activation in HIV-1-infected subjects on antiretroviral therapy: a pilot study

Abstract

Background: Mechanisms for increased cardiovascular risk in HIV-1-infected adults are incompletely understood, but platelet activation and immune activation leading to a prothrombotic state have been proposed as significant contributors. Aspirin has antiplatelet and immunomodulatory properties. We explored whether 1 week of low-dose aspirin attenuates platelet activation and immune activation in HIV-1-infected and virologically suppressed adults on antiretroviral therapy.

Methods: Platelet activation and immune activation were measured in HIV-1-infected subjects virologically suppressed on antiretroviral therapy and controls before and after 1 week of low-dose aspirin.

Results: Compared with control subjects, HIV-1-infected subjects had increased platelet activation, as measured by spontaneous platelet aggregation and aggregation in response to adenosine diphosphate, collagen, and arachidonic acid. After aspirin therapy, percent aggregation decreased similarly in both HIV-1-infected and control subjects to all platelet agonists tested except aggregation in response to arachidonic acid, which remained elevated in the HIV-1-infected group. HIV-1-infected subjects exhibited increased markers of T-cell activation (CD38 and HLA-DR) and monocyte activation (sCD14), which decreased after 1 week of aspirin therapy. Moreover, leukocyte responses to Toll-like receptor stimulation were enhanced after 1 week of aspirin therapy. In vitro studies showed that HIV-1 plasma could activate healthy platelets, which in turn activated monocytes, implicating a direct role for activated platelets in immune activation.

Conclusions: Our data demonstrate that heightened platelet activation and immune activation in treated HIV-1 disease are attenuated by 1 week of aspirin therapy. Aspirin should be further studied for its antithrombotic and immunomodulatory benefits in treated HIV-1 disease.

Conflict of interest statement

The authors have no conflicts of interest to disclose.

Figures

FIGURE 1

Urinary thromboxane is higher in HIV-infected subjects and is less responsive to aspirin therapy. A, Urinary 11-dehydro-TXB2 levels were higher in HIV(+) subjects as compared to HIV(−) control subjects at baseline, (*P = 0.02) and after 1 week of aspirin (*P = 0.04), Mann– Whitney test. B, Plasma P-selectin levels decreased in ART-treated HIV-infected subjects after 1 week of aspirin, paired t test, *P < 0.05. P-selectin levels do not decrease in uninfected control subjects after 1 week of aspirin.

FIGURE 2

T-cell activation is increased in ART-treated HIV-infected subjects and decreases after a week of aspirin therapy. Fresh PBMCs were isolated from blood from HIV(+) subjects and HIV(−) control subjects and were stained for markers of immune activation, fixed, and analyzed by flow cytometry. A, HLADR+CD38+CD4+ and B, HLADR+CD38+CD8+ lymphocytes decrease significantly after 1 week of aspirin therapy, paired t test, *P < 0.05. ART-treated HIV-infected subjects have elevated sCD14, which is decreased after 1 week of aspirin. C, Both HIV(+) and HIV(−) subjects experienced a decrease in sCD14 after 1 week of aspirin therapy, paired t test, *P < 0.05. D, sCD14 correlated with CD8+ lymphocyte immune activation, r = 0.43; P = 0.06.

FIGURE 3

One week of aspirin therapy improves responsiveness of leukocytes to certain TLR agonists. Fresh PBMCs were incubated overnight with TLR agonists CpG and HIV, and culture supernatants were stored at −20°C. Cytokine Bead Array analyses were performed on culture supernatants by flow cytometry. After 1 week of aspirin, more IL-6 was produced in response to CpGB, P = 0.01, more IL-6 was produced in response to HIV-1, P = 0.01, and more TNFα was produced in response to CpGB, P = 0.06 (all using paired t tests).

FIGURE 4

Plasma from HIV-infected subjects activates platelets and HIV-1 plasma–activated platelets activate monocytes. Normal platelets from 5 donors were incubated with control plasma at 37°C for 30 minutes 6 epinephrine or plasma from 5 donor HIV study subjects before and after 1-week aspirin therapy. Normal platelets mixed with plasma from HIV subjects expressed higher platelet activation markers. A, PAC-1; and B, P-selectin at baseline, (*P < 0.05, Mann–Whitney test) but this was abrogated when HIV-1 plasma was used from subjects receiving 1 week of aspirin therapy (paired student t test, *P < 0.05). C, These activated platelets caused THP-1 cell line mon-ocytes to activate more, as measured by CD14+CD61+ double-staining aggregates, Mann–Whitney test, *P ≤ 0.05, but this effect was also abrogated after 1-week aspirin therapy (paired student t test, *P < 0.05). epi, epinephrine.