Role of platelet biomarkers in inflammatory response

Abstract

Beyond hemostasis, thrombosis and wound healing, it is becoming increasingly clear that platelets play an integral role in inflammatory response and immune regulation. Platelets recognize pathogenic microorganisms and secrete various immunoregulatory cytokines and chemokines, thus facilitating a variety of immune effects and regulatory functions. In this review, we discuss recent advances in signaling of platelet activation-related biomarkers in inflammatory settings and application prospects to apply for disease diagnosis and treatment.

Keywords: Activation-related biomarkers; Immune regulation; Inflammatory response; Platelet.

Fig. 1

The key roles of platelets in modulating inflammatory processes. (1) Platelets are activated by invading pathogens (or their products) that have already been targeted by IgG receptor FcγRIIA (via IgG production). (2) Platelets can carry and eliminate pathogens, and via the expression of TLRs they can bind bacterial LPS and activate neutrophils, inducing NETs formation. (3) Platelet CD40L expression allows them to interact with different immune cells and either activate (arrow) and/or suppress (T bar) them. Furthermore, CD40L may be cleaved into a soluble form (sCD40L) that enhances platelet activation, aggregation, and platelet-leukocyte conjugation. (4) Intact platelet MHC class I molecules are located intracellularly but upon activation are expressed and can activate antigen-specific CD8+ T cells. In contrast, the MHC class I molecules on the surface of resting platelets are denatured and lead to CD8+ T cell inhibition. (5) Platelets contain many proinflammatory and anti-inflammatory cytokines and chemokines and, upon activation, can release them to the extracellular space. The culmination of these events makes platelets a formidable immunomodulatory host