Platelet, a key regulator of innate and adaptive immunity.

Platelets, anucleate blood components, represent the major cell type involved in the regulation of hemostasis and thrombosis. In addition to performing haemostatic roles, platelets can influence both innate and adaptive immune responses. In this review, we summarize the development of platelets and their functions in hemostasis. We also discuss the interactions between platelet products and innate or adaptive immune cells, including neutrophils, monocytes, macrophages, T cells, B cells and dendritic cells. Activated platelets and released molecules regulate the differentiation and function of these cells via platelet-derived receptors or secreting molecules. Platelets have dual effects on nearly all immune cells. Understanding the exact mechanisms underlying these effects will enable further application of platelet transfusion.

Altered Lipid Profile Is a Risk Factor for the Poor Progression of COVID-19: From Two Retrospective Cohorts.

Background: The coronavirus disease 2019 (COVID-19) pandemic has spread worldwide. However, the impact of baseline lipid profile on clinical endpoints in COVID-19 and the potential effect of COVID-19 on lipid profile remain unclear. Methods: In this retrospective cohort study, we consecutively enrolled 430 adult COVID-19 patients from two Chinese hospitals (one each in Chengdu and Wuhan). The lipid profile before admission and during the disease course and the clinical endpoint including in-hospital death or oropharyngeal swab test positive again (OSTPA) after discharge were collected. We used Kaplan-Meier and Cox regression to explore the lipid risk factors before admission associated with endpoints. Then, we assessed the lipid level change along with the disease course to determine the relationship between pathology alteration and the lipid change. Results: In the Chengdu cohort, multivariable Cox regression showed that low-density lipoprotein cholesterol (LDL-C) dyslipidemia before admission was associated with OSTPA after discharge for COVID-19 patients (RR: 2.51, 95% CI: 1.19, 5.29, p = 0.006). In the Wuhan cohort, the patients with triglyceride (TG) dyslipidemia had an increased risk of in-hospital death (RR: 1.92, 95% CI: 1.08, 3.60, p = 0.016). In addition, in both cohorts, the lipid levels gradually decreased in the in-hospital death or OSTPA subgroups since admission. On admission, we also noticed the relationship between the biomarkers of inflammation and the organ function measures and this lipid level in both cohorts. For example, after adjusting for age, sex, comorbidities, smoking, and drinking status, the C-reactive protein level was negatively associated with the TC lipid level [ß (SE) = -0.646 (0.219), p = 0.005]. However, an increased level of alanine aminotransferase, which indicates impaired hepatic function, was positively associated with total cholesterol (TC) lipid levels in the Chengdu cohort [ß (SE) = 0.633 (0.229), p = 0.007]. Conclusions: The baseline dyslipidemia should be considered as a risk factor for poor prognosis of COVID-19. However, lipid levels may be altered during the COVID-19 course, since lipidology may be distinctly affected by both inflammation and organic damage for SARS-CoV-2.

[Analysis of Transfusion Therapy Effectiveness in Patients with Myelodysplastic Syndrome].

OBJECTIVE: To investigate the transfusion effectiveness of suspended leucocyte depleted red blood cells (sld RBC) and fresh and irradiated apheresis platelets (fia Plt) in patients with myelodysplastic syndromes (MDS), and to explore the causes and mechanisms of ineffective platelet transfusion in patients with MDS. METHODS: Clinical data of 37 patients with confirmed MDS (WHO standard) such as the sex, age, Hb levels, Plt count, hemorrhage and coagulation functions, TEG and so on, were retrospectively analyzed. RESULTS: Among the 37 patients, 15 patients (40.5%) received only sld RBC transfusion, 9 patients (24.3%) received only fia Plt transfusion, and 13 patients (35.1%) received both transfusion. Among the 15 patients with only red blood cell transfusion, 3 patients were ineffective and the ineffectual transfusion rate was 20.0%. Among the 9 patients with only received platelet transfusion, 5 patients were ineffective and the ineffectual transfusion rate was 55.6%, there were significant statistical differences between the two groups (P﹤0.01). The red blood cell transfusion ineffective were 3 patients (23.1%) , the platelet transfusion ineffective were 8 patients (61.5%) and the both transfusion ineffective were 2 patients (15.4%) among the patients both transfusion . The positive rate of platelet antibody in MDS patients with ineffective platelet transfusion was 23.1%. Compared with the normal control group, Human P selectin (P-SelectinCD62P) (P＜0.001) and human anti-thrombin 3 antibody (AT-III Ab) (P＜0.001) significantly increased and human tissue factor pathway inhibitor (TFPI) significantly decreased (P＜0.05) in MDS patients with ineffective platelet transfusion. CONCLUSION: In the process of component transfusion for MDS patients, compared with the transfusion of red blood cells, the inefficiencies of platelet transfusion significantly increased, mainly due to the disorder of blood coagulation and the generation of platelet antibodies in MDS patients with ineffective platelet transfusion. Compared with the normal control group, human P selectin and human anti-thrombin 3 antibody significantly increase and human tissue factor pathway inhibitor significantly decreases in MDS patients with ineffective platelet transfusion. Human P selectin, human anti-thrombin 3 antibody and human tissue factor pathway inhibitor in molecular markers and fibrinolytic markers can be used as indicators of platelet transfusion time and efficiency in patients with MDS.