2-Arachidonoylglycerol enhances platelet formation from human megakaryoblasts

Abstract

Platelets modulate vascular system integrity, and their loss is critical in haematological pathologies and after chemotherapy. Therefore, identification of molecules enhancing platelet production would be useful to counteract thrombocytopenia. We have previously shown that 2-arachidonoylglycerol (2-AG) acts as a true agonist of platelets, as well as it commits erythroid precursors toward the megakaryocytic lineage. Against this background, we sought to further interrogate the role of 2-AG in megakaryocyte/platelet physiology by investigating terminal differentiation, and subsequent thrombopoiesis. To this end, we used MEG-01 cells, a human megakaryoblastic cell line able to produce in vitro platelet-like particles.2-AG increased the number of cells showing ruffled surface and enhanced surface expression of specific megakaryocyte/platelet surface antigens, typical hallmarks of terminal megakaryocytic differentiation and platelet production. Changes in cytoskeleton modeling also occurred in differentiated megakaryocytes and blebbing platelets. 2-AG acted by binding to CB 1 and CB 2 receptors, because specific antagonists reverted its effect. Platelets were split off from megakaryocytes and were functional: they contained the platelet-specific surface markers CD61 and CD49, whose levels increased following stimulation with a natural agonist like collagen. Given the importance of 2-AG for driving megakaryopoiesis and thrombopoiesis, not surprisingly we found that its hydrolytic enzymes were tightly controlled by classical inducers of megakaryocyte differentiation.In conclusion 2-AG, by triggering megakaryocyte maturation and platelet release, may have clinical efficacy to counteract thrombocytopenia-related diseases.

Disease-Specific Derangement of Circulating Endocannabinoids and N-Acylethanolamines in Myeloproliferative Neoplasms

“…In addition, PPAR-alpha and -gamma targets mediate NAE anti-inflammatory properties [14]. In particular, in contrast to 2AG, which is involved in immune cell recruitment, AEA suppresses pro-inflammatory cytokines production and enhances the release of anti-inflammatory cytokines regulating the immune responses [15][16][17]. Furthermore, PEA was shown to counteract systemic inflammation in mice and humans [14] and to support the increased intestinal permeability associated with inflammation along with OEA [18].…”

From Phytocannabinoids to Cannabinoid Receptors and Endocannabinoids: Pleiotropic Physiological and Pathological Roles Through Complex Pharmacology

“…The effects occur through CB2 activation (666,866). Furthermore, 2-AG is able to drive a cell line expressing surface antigens of both erythroid and megakaryocytic phenotypes towards megakaryocytic differentiation (128), thereby stimulating platelet production and release (285). Accordingly, 2-AG hydrolytic enzymes are under control of inducers of megakaryocyte differentiation (285).…”

Endocannabinoids

“…Looking first at the effects of endocannabinoids and endocannabinoid-like compounds on the formation of blood cellular components, AEA, 2-AG and PEA have been shown to stimulate mouse haematopoietic cell growth and differentiation into granulocyte, erythrocyte, macrophage and megakaryocyte colonies (Valk et al 1997;Patinkin et al 2008) through activation of the CB 2 receptor (Valk et al 1997). 2-AG can also increase the formation and maturation of platelets from human megakaryoblasts (Gasperi et al 2014).…”

“…The collective results suggested that the potency of AEA in the suppression of IL-2 secretion correlated with levels of COX-2 protein in T cells and that the 2-AG-mediated inhibition of IL-2 secretion was dependent upon COX-2-catalyzed metabolism. Gasperi et al (2014) found that 2-AG was able to initiate and complete the leukocyte adhesion cascade, by modulating the expression of selectins, cell adhesion molecules that are involved in lymphocyte homing and in chronic and acute inflammatory processes. A short exposure of primary human umbilical vein endothelial cells (HUVECs) to 2-AG was sufficient to prime them toward an activated state.…”

“…This could be blocked by inhibitors of their metabolism by MAGL or COX, and was not mimicked by CB 1 or CB 2 agonists, suggesting it is metabolites of virodhamine and 2-AG that mediate their effects. 2-AG can also increase platelet formation and maturation (Gasperi et al 2014). Similarly, AEA can extend platelet survival through CB 1 -dependent Akt signalling (Catani et al 2010b), indicating that there are many aspects of platelet function that can be modulated by endocannabinoids.…”