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

Megakaryocytes possess a STING pathway that is transferred to platelets to potentiate activation

Platelets display unexpected roles in immune and coagulation responses. Emerging evidence suggests that STING is implicated in hypercoagulation. STING is an adaptor protein downstream of the DNA sensor cyclic GMP-AMP synthase (cGAS) that is activated by cytosolic microbial and self-DNA during infections, and in the context of loss of cellular integrity, to instigate the production of type-I IFN and pro-inflammatory cytokines. To date, whether the cGAS-STING pathway is present in platelets and contributes to platelet functions is not defined. Using a combination of pharmacological and genetic approaches, we demonstrate here that megakaryocytes and platelets possess a functional cGAS-STING pathway. Our results suggest that in megakaryocytes, STING stimulation activates a type-I IFN response, and during thrombopoiesis, cGAS and STING are transferred to proplatelets. Finally, we show that both murine and human platelets contain cGAS and STING proteins, and the cGAS-STING pathway contributes to potentiation of platelet activation and aggregation. Taken together, these observations establish for the first time a novel role of the cGAS-STING DNA sensing axis in the megakaryocyte and platelet lineage.

Alterations in the megakaryocyte transcriptome impacts platelet function in sepsis and COVID-19 infection

Platelets and their parent cell, the megakaryocyte (MK), are increasingly recognized for their roles during infection and inflammation. The MK residing in the bone marrow or arising from precursors trafficked to other organs for development go on to form platelets through thrombopoiesis. Infection, by direct and indirect mechanisms, can alter the transcriptional profile of MKs. The altered environment, whether mediated by inflammatory cytokines or other signaling mechanisms results in an altered platelet transcriptome. Platelets released into the circulation, in turn, interact with each other, circulating leukocytes and endothelial cells and contribute to the clearance of pathogens or the potentiation of pathophysiology through such mechanisms as immunothrombosis. In this article we hope to identify key contributions that explore the impact of an altered transcriptomic landscape during severe, systemic response to infection broadly defined as sepsis, and viral infections, including SARS-CoV2. We include current publications that outline the role of MKs from bone-marrow and extra-medullary sites as well as the circulating platelet. The underlying diseases result in thrombotic complications that exacerbate organ dysfunction and mortality. Understanding the impact of platelets on the pathophysiology of disease may drive therapeutic advances to improve the morbidity and mortality of these deadly afflictions.

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

Objective

To investigate the primary predictive factors for the occurrence of severe neonatal infection, construct a prediction model and assess its effectiveness.

Methods

A total of 160 neonates hospitalised in the Department of Neonatology at Suixi County Hospital from January 2019 to June 2022 were retrospectively analysed. Clinical data was analyzed to determine the primary predictive factors for the occurrence of severe neonatal infection. Predictive efficacy was evaluated using a receiver operating characteristic curve, and a nomogram model was constructed according to the predictors. A bootstrap technique was used to verify the accuracy of the model.

Results

The neonates were divided, based on the degree of infection, into a mild infection group (n = 80) and a severe infection group (n = 80) according to a 1:1 ratio. Multivariate logistic regression analysis showed that compared with the recovery stage, white blood cell count (WBC) and platelet count (PLT) in the two groups were significantly decreased in the early stage of infection, and the ratio of mean platelet volume to PLT, as well as C-reactive protein (CRP) and procalcitonin levels, was elevated (P < 0.05). The area under the curves (AUCs) of decreased WBC, decreased PLT and elevated CRP levels, and the combination of these three indicators, were 0.881, 0.798, 0.523 and 0.914, respectively. According to the filtered indicators, two models (a dichotomous variable equation model and a nomogram model) of continuous numerical variables were constructed, and their AUCs were 0.958 and 0.914, respectively. The calibration curve of the nomogram model was validated with a consistency index of 0.908 (95% confidence interval [0.862, 0.954]).

Conclusion

Decreased WBC and PLT levels and an elevated CRP level were the primary independent predictors of severe neonatal infection.