Deciphering the role of platelets in severe allergy by an integrative omics approach

Abstract

Background: Mechanisms causing the onset and perpetuation of inflammation in severe allergic patients remain unknown. Our previous studies suggested that severe allergic inflammation is linked to platelet dysfunction. Methods:Platelet-rich plasma (PRP) and platelet-poor plasma (PPP) samples were obtained by platelet-apheresis from severe (n = 7) and mild (n = 10) allergic patients and nonallergic subjects (n = 9) to perform platelet lipidomics by liquid chromatography coupled to mass spectrometry (LC-MS) and RNA-seq analysis. Significant metabolites and transcripts were used to identify compromised biological pathways in the severe phenotype. Platelet and inflammation-related proteins were quantified by Luminex.Results: Platelets from severe allergic patients were characterized by high levels of ceramides, phosphoinositols, phosphocholines, and sphingomyelins. In contrast, they showed a decrease in eicosanoid precursor levels. Biological pathway analysis performed with the significant lipids revealed the alteration of phospholipases, calcium-dependent events, and linolenic metabolism. RNAseq confirmed mRNA overexpression of genes related to platelet activation and arachidonic acid metabolism in the severe phenotypes. Pathway analysis indicated the alteration of NOD, MAPK, TLR, TNF, and IL-17 pathways in the severe phenotype. P-Selectin and IL-17AF proteins were increased in the severe phenotype.

Platelet-Derived Extracellular Vesicles as Lipid Carriers in Severe Allergic Inflammation

“…Whole blood hemograms showed no differences in platelet and white blood cell counts between the experimental groups. As we have previously shown [ 10 ], platelet-rich plasma (PRP) hemograms confirmed the absence of other blood cell types, which ensured the purity of the PL-EV samples. Likewise, platelet counts and mean platelet volume did not differ between experimental groups ( p > 0.05, Table S2 ).…”

“…Recent studies have highlighted platelet alterations in inflammatory conditions such as rheumatoid arthritis [ 5 ], multiple sclerosis [ 6 ], Crohn’s disease [ 7 ], sepsis [ 8 ], and, more recently, allergy [ 9 , 10 ]. In fact, we have previously found that platelets from severely allergic patients present a specific lipid content that could contribute to the development of chronic inflammation [ 10 ]. In these inflammatory disorders, platelets become activated and release their content together with extracellular vesicles (EVs) [ 11 , 12 ], which could alter platelet–immune cell communication.…”

“…In this study, using a model of respiratory allergic inflammation stratified according to severity [ 10 ], the metabolic load of PL-EVs was investigated, aiming to provide insights into novel mediators and mechanisms involved in the progression of inflammation into a severely allergic condition.…”

Transcriptomics reveals a distinct metabolic profile in T cells from severe allergic asthmatic patients

“…This finding, together with the alterations observed in FAO, point to an altered regulatory function in severe allergic asthmatic patients. In fact, the lack of regulation capacity might be a key mechanism in the maintenance of the inflammatory state in these patients ( 1 , 7 , 24 ). We have already demonstrated that severe respiratory allergic patients presented an enhanced inflammatory immune response in the oral mucosa, with an increased number of CD4 + infiltrates ( 24 ) and enhanced recruitment of Treg cells ( 2 ).…”

“…We have previously shown that severe respiratory allergic patients have specific platelet content, reduced protein synthesis, and switch of immune cells' metabolism to aerobic glycolysis ( 6 , 7 ). It has been widely described how systemic metabolism reprograms the fate of immune cells, by influencing their activation, proliferative capacity and their quiescent state in tissues and in the systemic circulation ( 8 ).…”