Impact of high platelet turnover on the platelet transcriptome: Results from platelet RNA-sequencing in patients with sepsis

Abstract

Background Sepsis is associated with high platelet turnover and elevated levels of immature platelets. Changes in the platelet transcriptome and the specific impact of immature platelets on the platelet transcriptome remain unclear. Thus, this study sought to address whether and how elevated levels of immature platelets affect the platelet transcriptome in patients with sepsis. Methods Blood samples were obtained from patients with sepsis requiring vasopressor therapy (n = 8) and from a control group of patients with stable coronary artery disease and otherwise similar demographic characteristics (n = 8). Immature platelet fraction (IPF) was determined on a Sysmex XE 2100 analyser and platelet function was tested by impedance aggregometry. RNA from leukocyte-depleted platelets was used for transcriptome analysis by Next Generation Sequencing integrating the use of unique molecular identifiers. Results IPF (median [interquartile range]) was significantly elevated in sepsis patients (6.4 [5.3–8.7] % vs. 3.6 [2.6–4.6] %, p = 0.005). Platelet function testing revealed no differences in adenosine diphosphate- or thrombin receptor activating peptide-induced platelet aggregation between control and sepsis patients. Putative circular RNA transcripts were decreased in platelets from septic patients. Leukocyte contamination defined by CD45 abundance levels in RNA-sequencing was absent in both groups. Principal component analysis of transcripts showed only partial overlap of clustering with IPF levels. RNA sequencing showed up-regulation of 524 and down-regulation of 118 genes in platelets from sepsis patients compared to controls. Upregulated genes were mostly related to catabolic processes and protein translation. Comparison to published platelet transcriptomes showed a large overlap of changes observed in sepsis and COVID-19 but not with reticulated platelets from healthy donors. Conclusions Patients with sepsis appear to have a less degraded platelet transcriptome as indicated by increased levels of immature platelets and decreased levels of putative circular RNA transcripts. The present data suggests that increased protein translation is a characteristic mechanism of systemic inflammation.

The amazing genetic complexity of anucleated platelets

“…21 Moreover, RNAseq of human and murine platelets showed that the platelet transcriptional and translational landscapes are significantly altered in sepsis, and that upregulation of ITGA2B is associated with higher mortality 22 providing novel evidence that upregulation of protein synthetic events in platelets may play a pathogenic role in sepsis. A recent study 23 confirmed the differential expression of several genes in platelets from sepsis patients compared to controls and showed that upregulated genes were mostly related to catabolic processes and protein translation. The Authors also showed that patients with sepsis have increased levels of immature platelets and a less degraded platelet transcriptome, as indicated by decreased levels of circRNAs.…”

“…The biological implications of the increased platelet turnover remain unclear, however this study first suggested that increased protein translation is a characteristic mechanism of systemic inflammation. 23 Intriguingly, there is a large overlap of the platelet transcriptome changes observed either in sepsis or in COVID-19. [22][23][24] Distinctive changes in the gene-expression profile of circulating platelets of COVID-19 patients have been shown involving the pathways associated with protein ubiquitination, antigen presentation, and mitochondrial dysfunction, 24 suggesting a drastic change in the redox balance and in platelet metabolism leading to platelet activation and to the high thrombotic risk of COVID-19 patients.…”

“…23 Intriguingly, there is a large overlap of the platelet transcriptome changes observed either in sepsis or in COVID-19. [22][23][24] Distinctive changes in the gene-expression profile of circulating platelets of COVID-19 patients have been shown involving the pathways associated with protein ubiquitination, antigen presentation, and mitochondrial dysfunction, 24 suggesting a drastic change in the redox balance and in platelet metabolism leading to platelet activation and to the high thrombotic risk of COVID-19 patients. Another study similarly found in platelets from COVID-19 patients differentially expressed lncRNAs involved in the regulation of hemostasis, platelet activation and the immune response, 25 further confirming that platelet hyperactivation and immune-thrombosis are major players in COVID-19 complications.…”

An Analysis of Predictive Factors for Severe Neonatal Infection and the Construction of a Prediction Model

“…However, since MPV in the early stages of infection did not differ, multivariate logistic regression analysis showed that the MVP/PLT ratio is not an early predictor of severe neonatal infection; this result is inconsistent with the findings of related studies. 22 , 23 This change may be due to the following reasons: (1) PLT levels increase in the early stage of infection, while the number of immature platelets in the blood increases in the recovery stage; an increase in MPV levels compensates for the adverse consequences of decreased PLT; 24 (2) relevant studies do not indicate clearly whether data were drawn from the early or the recovery stage of infection. Therefore, the increase in MPV levels may derive from the recovery stage of infection rather than the early stage, which necessitates further research and discussion.…”

El hemograma como predictor en la infección por SARS-CoV-2

“…Respecto a los otros parámetros plaquetarios derivados de los autoanalizadores de hematología y la infección por SARS-CoV-2, con relación al volumen medio plaquetario (VMP por la sigla en inglés Mean Platelet Volume) y el ancho de distribución de las plaquetas (PDW por la sigla en inglés Platelet Distribution Width) no hay información suficiente para postularlos como predictores en la infección por SARS-CoV-2. Las plaquetas reticuladas, también conocidas como fracción de plaquetas inmaduras o reticuloplaquetas, son plaquetas jóvenes, de 1 a 2 días, que se caracterizan por una alto contenido de ARN (76), lo que en la práctica refleja un aumento de la trombopoyesis y en la clínica se correlaciona con condiciones inflamatorias activas y severas (77) y puede servir como un predictor de progresión a un estado severo de la enfermedad y desenlaces fatales en pacientes críticos con COVID-19 (78)(79)(80)(81), íntimamente relacionadas con aumento del riesgo cardiovascular (79) y desenlace fatal cuando el paciente tiene una sepsis sobreagregada (81).…”