Activated α_IIbβ₃on platelets mediates flow-dependent NETosis via SLC44A2

Abstract

Platelet-leukocyte interactions are important for innate immune responses, but also contribute to the pathogenesis of thrombotic disorders, such as deep vein thrombosis. How these interactions are manifest and how they influence leukocyte function remains poorly understood. Here, we demonstrate that binding to von Willebrand factor under flow through glycoprotein Ib 'primes' platelets resulting in intracellular Ca 2+ release and  IIb  3 activation. This priming enables platelets to bind leukocytes via a mechanism that is largely independent of P-selectin, but that is inhibited by blocking  IIb  3 . We show that neutrophils and T-cells bind directly to activated  IIb  3 under flow, identifying this platelet integrin as a novel leukocyte receptor. Binding of neutrophils to  IIb  3 under flow causes rapid intracellular Ca 2+ release, and initiates Ca 2+ -and NADPH oxidase-dependent signaling leading to production of neutrophil extracellular traps (NETs). NET production is itself dependent upon a mechanosensitive mechanism, as NETosis is markedly diminished if neutrophils are captured by  IIb  3 under static conditions. Takentogether, these data demonstrate a novel mechanism for platelet-neutrophil cross-talk and mechanosensitive NET production.

Plasma Protein Signatures of a Murine Venous Thrombosis Model and Slc44a2 Knockout Mice Using Quantitative-Targeted Proteomics

“…31,32 Slc44a2 deficient mice do however display reduced thrombus formation following flow restriction 57 where inflammatory cells from the blood, including neutrophils and platelets, are important contributors. 58,59 Moreover, it was recently demonstrated that platelets primed by VWF display-activated integrin α IIb β 3 (but not CD62P), which can then bind neutrophil SLC44A2 and mediate NETosis under venous flow, 60 suggesting that SLC44A2 is a mediator of cell-cell interactions. Therefore, we suggest incorporating the cellular compartment of the blood in further investigation of the effect of SLC44A2 on VT. To elucidate the contribution of SLC44A2 on the different cell types, cell specific knockouts of Slc44a2 might be interesting to include.…”

Platelets can contain SARS-CoV-2 RNA and are hyperactivated in COVID-19

“…36,37 NETosis requires platelets and may thus contribute to thrombosis. 38,39 Platelets express immune and inflammatory molecules such as interleukin-1 (IL1), 40 and a set of immune receptors including CD40L, Toll-like receptors (TLR), 31 and the Fc receptor for IgG FcRIIA 41 .…”

Choline transporter-like proteins 1 and 2 are newly identified plasma membrane and mitochondrial ethanolamine transporters

“…CTL2 gene SLC44A2 is well-established the human neutrophil antigen ( 37 ), and genetic risk factor for hearing loss, Meniere’s disease, and venous thrombosis ( 38 ). Neutrophil CTL2 could interact directly with platelets’ integrin α IIb β 3 and induce neutrophil extracellular trap (NETosis) that promotes thrombosis ( 39 ). SLC44A2 knockout mouse is protected against venous thrombosis showing that CTL2 could be an important therapeutic target for the disease ( 40 , 41 , 42 ).…”