A method based on plateletpheresis to obtain functional platelet, CD3+ and CD14+ matched populations for research immunological studies

Effect of preoperative autologous platelet-rich plasmapheresis on postoperative bleeding in patients undergoing heart valve surgery

Background

Cardiovascular surgeries often require deep hypothermic circulatory arrest and cardiopulmonary bypass (CPB), which can disrupt blood clotting and lead to excessive bleeding. Traditional treatments involve transfusing blood and blood products, which can have adverse effects and place significant strain on the global blood supply. Research suggests that autologous platelet-rich plasmapheresis (aPRP) may reduce the need for transfusions by preserving blood components. However, the impact of aPRP on postoperative blood loss and clinical outcomes in cardiovascular surgery remains controversial. This study aimed to examine the effects of aPRP on postoperative blood loss and recovery in patients undergoing heart valve surgery.

Methods

A total of 183 patients were divided into either aPRP or control groups. The aPRP group received aPRP before CPB, whereas the control group did not. The primary endpoint was postoperative bleeding between the groups. The secondary endpoints were postoperative bleeding risk factors and clinical outcome assessment. Logistic regression analysis with covariate adjustment was used to calculate these risk factors.

Results

A total of 76 patients (41.5%) in the aPRP group and 107 patients (58.5%) in the control group were included in the analysis. No significant difference was found in the occurrence of postoperative bleeding [odds ratio (OR) =0.53, 95% confidence interval (CI): 0.28-1.00, P=0.05], and the aPRP group had fewer complications than the controls (OR =0.28, 95% CI: 0.10-0.68, P=0.009). However, after adjusting for the New York Heart Association (NYHA) classification, diabetes, arrhythmology, mean activated clotting time (ACTmean), CPB, bleeding, thoracotomy, and body mass index (BMI), there was a significant difference in postoperative bleeding (adjusted OR =0.47, 95% CI: 0.22-0.98, P=0.04) and complications (adjusted OR =0.23, 95% CI: 0.07-0.64, P=0.008) between the two groups.

Conclusions

Preoperative aPRP can improve postoperative outcomes and reduce complications in patients undergoing heart valve surgery.

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

The resolution of inflammation is a complex process that is critical for removing inflammatory cells and restoring tissue function. The dysregulation of these mechanisms leads to chronic inflammatory disorders. Platelets, essential cells for preserving homeostasis, are thought to play a role in inflammation as they are a source of immunomodulatory factors. Our aim was to identify key metabolites carried by platelet-derived extracellular vesicles (PL-EVs) in a model of allergic inflammation. PL-EVs were isolated by serial ultracentrifugation using platelet-rich plasma samples obtained from platelet apheresis from severely (n = 6) and mildly (n = 6) allergic patients and non-allergic individuals used as controls (n = 8). PL-EVs were analysed by a multiplatform approach using liquid and gas chromatography coupled to mass spectrometry (LC-MS and GC-MS, respectively). PL-EVs obtained from severely and mildly allergic patients and control individuals presented comparable particle concentrations and sizes with similar protein concentrations. Strikingly, PL-EVs differed in their lipid and metabolic content according to the severity of inflammation. L-carnitine, ceramide (Cer (d18:0/24:0)), and several triglycerides, all of which seem to be involved in apoptosis and regulatory T functions, were higher in PL-EVs from patients with mild allergic inflammation than in those with severe inflammation. In contrast, PL-EVs obtained from patients with severe allergic inflammation showed an alteration in the arachidonic acid pathway. This study demonstrates that PL-EVs carry specific lipids and metabolites according to the degree of inflammation in allergic patients and propose novel perspectives for characterising the progression of allergic inflammation.

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

The reasons behind the onset and continuation of chronic inflammation in individuals with severe allergies are still not understood. Earlier findings indicated that there is a connection between severe allergic inflammation, systemic metabolic alterations and impairment of regulatory functions. Here, we aimed to identify transcriptomic alterations in T cells associated with the degree of severity in allergic asthmatic patients. T cells were isolated from severe (n = 7) and mild (n = 9) allergic asthmatic patients, and control (non-allergic, non-asthmatic healthy) subjects (n = 8) to perform RNA analysis by Affymetrix gene expression. Compromised biological pathways in the severe phenotype were identified using significant transcripts. T cells' transcriptome of severe allergic asthmatic patients was distinct from that of mild and control subjects. A higher count of differentially expressed genes (DEGs) was observed in the group of individuals with severe allergic asthma vs. control (4,924 genes) and vs. mild (4,232 genes) groups. Mild group also had 1,102 DEGs vs. controls. Pathway analysis revealed alterations in metabolism and immune response in the severe phenotype. Severe allergic asthmatic patients presented downregulation in genes related to oxidative phosphorylation, fatty acid oxidation and glycolysis together with increased expression of genes coding inflammatory cytokines (e.g. IL-19, IL-23A and IL-31). Moreover, the downregulation of genes involved in TGFβ pathway together with a decreased tendency on the percentage of T regulatory cell (CD4 + CD25+), suggest a compromised regulatory function in severe allergic asthmatic patients. This study demonstrates a transcriptional downregulation of metabolic and cell signalling pathways in T cells of severe allergic asthmatic patients associated with diminished regulatory T cell function. These findings support a link between energy metabolism of T cells and allergic asthmatic inflammation.

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

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.

CONCLUSIONS

This study demonstrates that platelet lipid, mRNA, and protein content is different according to allergy severity. These findings suggest that platelet load is a potential source of biomarkers and a new chance for therapeutic targets in severe inflammatory pathologies.