Human plasma platelet‐derived exosomes: effects of aspirin

Abstract

Platelet-derived exosomes mediate platelet atherogenic interactions with endothelial cells and monocytes. A new method for isolation of plasma plateletderived exosomes is described and used to examine effects of aging and aspirin on exosome cargo proteins. Exosome secretion by purified platelets in vitro did not increase after exposure to thrombin or collagen, as assessed by exosome counts and quantification of the CD81 exosome marker. Thrombin and collagen increased exosome content of a-granule chemokines CXCL4 and CXCL7 and cytoplasmic high-mobility group box 1 (HMGB1) protein, but not membrane platelet glycoprotein VI (GPVI), with dependence on extracellular calcium. Aspirin consumption significantly blocked thrombin-and collageninduced increases in exosome cargo levels of chemokines and HMGB1, without altering total exosome secretion or GPVI cargo. Plasma platelet-derived exosomes, enriched by absorption with mouse antihuman CD42b [platelet glycoprotein Ib (GPIb)] mAb, had sizes and cargo protein contents similar to those of exosomes from purified platelets. The plasma platelet-derived exosome number is lower and its chemokine and HMGB1 levels higher after age 65 yr. Aspirin consumption significantly suppressed cargo protein levels of plasma platelet-derived exosomes without altering total levels of exosomes. Cargo proteins of human plasma platelet-derived exosomes may biomark platelet abnormalities and in vivo effects of drugs.-Goetzl, E.

Emerging Role of High Mobility Group Box-1 in Thrombosis-Related Diseases

“…Consistent with earlier reports, HMGB-1 was rarely detected in the plasma and was mainly an intracellular protein [103]. However, thrombin, collagen, C-reactive protein, or adenosine diphosphate induced translocation of HMGB-1 from the cytoplasm to the supernatant in platelets [104][105][106]. Interestingly, thrombin or collagen did not change the exosome secretion of purified platelets.…”

“…Interestingly, thrombin or collagen did not change the exosome secretion of purified platelets. However, cytoplasmic HMGB-1 could be released from thrombin-or collagen-induced platelets under conditions of high extracellular calcium, suggesting that extracellular calcium mediated thrombin/collagen-induced expression of HMGB-1 in platelets [104]. Thus, these findings indicated extracellular calcium-dependent HMGB-1 secretion in active platelets.…”

“…Nuclear magnetic resonance spectroscopic studies have shown the binding of salicylic acid, an active metabolite of aspirin, to HMGB-1 [165,166]. Recently, Goetzel found that aspirin, a classical antiplatelet drug, significantly blocked thrombin-and collagen-induced HMGB-1 release in active platelets [104]. Besides, two other antiplatelet drugs (clopidogrel and cilostazol) attenuated the expression of HMGB-1 in septic shock [167,168].…”

Extracellular vesicles in cardiovascular homeostasis and disease

“…Further, the charged phospholipid profile (e.g., enrichment of phosphatidylserine) characteristic of many EV populations may also aid in the generation of thrombin [28]. In response to the generation of thrombin, local platelets release exosomal EVs that mediate paracrine signaling to endothelial cells [29]. In turn, the endothelial cells release EVs enriched with matrix metallopreinase-10, which exacerbate the pro-inflammatory vascular wall remodeling [30].…”

Sterile Inflammatory Role of High Mobility Group Box 1 Protein: Biological Functions and Involvement in Disease

“…EP reduced circulating levels of HMGB1 and significantly prevented lethality [121]. Aspirin, a classical antiplatelet drug, significantly blocked thrombin-and collageninduced HMGB1 release in active platelets [122]. Two other antiplatelet drugs (clopidogrel and cilostazol) also attenuated the expression of HMGB1 in septic shock [123].…”