Regulation of Innate Immune Responses by Platelets

Abstract

The role of platelets has been extensively studied in the context of coagulation and vascular integrity. Their hemostatic imbalance can lead to known conditions as atherosclerotic plaques, thrombosis, and ischemia. Nevertheless, the knowledge regarding the regulation of different cell types by platelets has been growing exponentially in the past years. Among these biological systems, the innate immune response is remarkably affected by the crosstalk with platelets. This interaction can come from the formation of platelet-leukocyte aggregates, signaling by direct contact between membrane surface molecules or by the stimulation of immune cells by soluble factors and active microparticles secreted by platelets. These ubiquitous blood components are able to sense and react to danger signals, guiding leukocytes to an injury site and providing a scaffold for the formation of extracellular traps for efficient microbial killing and clearance. Using several different mechanisms, platelets have an important task as they regulate the release of different cytokines and chemokines upon sterile or infectious damage, the expression of cell markers and regulation of cell death and survival. Therefore, platelets are more than clotting agents, but critical players within the fine inflammatory equilibrium for the host. In this review, we present pointers to a better understanding about how platelets control and modulate innate immune cells, as well as a summary of the outcome of this interaction, providing an important step for therapeutic opportunities and guidance for future research on infectious and autoimmune diseases.

Ability of Bicarbonate Supplementation To Sensitize Selected Methicillin-Resistant Staphylococcus aureus Strains to β-Lactam Antibiotics in an Ex Vivo Simulated Endocardial Vegetation Model

“…The present study extends our previous work on the ability of NaHCO 3 supplemen- tation of standard MRSA in vitro media to identify a subset of MRSA strains that may, in fact, exhibit ␤-lactam susceptibility (10,18,19). The notion of using alternative media for antibiotic susceptibility screening is not new; however, the biological basis and clinical utility of this approach has substantially increased in the last few years in a variety of bacteria, including Salmonella, Acinetobacter, and Staphylococcus spp.…”

Ability of Bicarbonate Supplementation to Sensitize Selected Methicillin-ResistantStaphylococcus aureus(MRSA) Strains to β-Lactam Antibiotics in anEx VivoSimulated Endocardial Vegetation Model

“…The current study extends our previous work on the ability of NaHCO 3 supplementation of standard MRSA in vitro media to identify a sub-set of MRSA strains that may, in fact, exhibit β-lactam susceptibility (14, 22, 23). The notion of employing alternative media for antibiotic susceptibility screening is not new; however, the biological basis and clinical utility of this approach has substantially increased in the last few years.…”

Dynamics of Gene Expression in Mice Infected with Different Genotypes of Toxoplasma gondii

“…3F to 3I). Since Pf4 was reported to be released from alpha-granules of activated platelets that could fight some parasite infections [47,48,49], the data imply that platelet may play an important role in host defense to the infections with different T. gondii genotype; however, the detailed mechanism needs to be further studied. The roles of three other down-regulated genes (Prg4, CXCL13 and Selp) in T. gondii infection also need to be identified in the future study.…”