Platelet disturbances correlate with endothelial cell activation in uncomplicated Plasmodium vivax malaria

Abstract

23Introduction. Platelets drive endothelial cell activation in many diseases. 24 However, if this occurs in Plasmodium vivax malaria is unclear. As platelets have 25 been reported to be activated and to play a role in inflammatory response during 26 malaria, we hypothesized that this would correlate with endothelial alterations 27 during acute illness. 28Methods. We performed platelet flow cytometry of PAC-1 and P-selectin. We 29 measured Platelet markers (CXCL4, CD40L, P-selectin, Thrombopoietin, IL-11) and 30 endothelial markers (ICAM-1, von Willebrand Factor and E-selectin) in plasma with a 31 multiplex-based assay. The values of each mediator were used to generate heatmaps, K-32 means clustering and Principal Component analysis. In addition, we determined pair-wise 33 Pearson's correlation coefficients to generate correlation networks. 34 Results. Platelet counts were reduced, and mean platelet volume increased in 35 malaria patients. The activation of circulating platelets in flow cytometry did not differ 36 between patients and controls. CD40L levels (Median [IQ]: 517 [406-651] vs. 1029 [732-37 1267] pg/mL, P=0.0001) were significantly higher in patients, while P-selectin (Median 38 [IQ]: 17.0 [15.4-20.6] vs. 22.2 [17.6-25.7] ng/mL, P=0.0621) and CXCL4 showed a 39 nonsignificant trend towards higher levels in patients. The network correlation 40 approach demonstrated the correlation between markers of platelet and endothelial 41 activation, and the heatmaps revealed a distinct pattern of activation in two subsets 42 of P. vivax patients when compared to controls.43 Conclusion. platelet activation occurs in uncomplicated vivax malaria and 44 this correlates with higher endothelial cell activation, especially in a subset of 45 patients. 46 47 131 (R&D Systems): CD40L, P-selectin, PF4 and thrombopoietin (TPO), IL-11, as 132 well as circulating markers of EC activation (ICAM-1, E-selectin, von Willebrand 133Factor (vWF)). We selected 31 patients for the multiplex assay from a wide range 134 of parasitemias (260 to 25,150 Pv-IE/μL), so that a wide spectrum of disease 135 burden could be evaluated. This subgroup did not differ from the overall 136 population of patients regarding severity of disease, sex proportion, platelet counts 137 and mean parasitemia. We selected nine controls matched for age and sex. For the 138 network analysis, we used some interpolated results from below standard range. 139 140

Total parasite biomass but not peripheral parasitaemia is associated with endothelial and haematological perturbations in Plasmodium vivax patients

“…Patients with severe thrombocytopenia also show more severe leukopenia, lymphopenia and mega platelets (higher MPV). In addition, Our data support previous studies suggesting a role for endothelial cell (EC) activation and damage in increased leukocyte adhesion, intravascular platelet agglutination with increased platelet clearance from the circulation and skewing of haematopoiesis toward the myeloid lineage (likely at the expense of lymphopoiesis) in the BM [28][29][30][33][34][35]41,42,45 . P. vivax elicits a stronger inflammatory response and more pronounced endothelial activation when compared with other Plasmodium infections with similar or higher peripheral parasitaemia 23 , however the role of EC activation in P. vivax pathogenesis is not yet understood.…”

“…Patient clustering indicated that Vivax high patients have increased levels of EC markers in the plasma compared to Vivax low patients (Figure 2C). Previous studies indicate that EC activation and damage might contribute to thrombocytopenia and inducing hematopoiesis, resulting in HSC differentiation directed towards myelopoiesis 24,28,29,[33][34][35][41][42][43] . In our cohort, circulating levels of EC adhesion molecules (ICAM-1, VCAM-1, E-selectin and P-selectin) and other EC activation markers and procoagulant molecules (Ang-2, VWF-A2, CD40L and PAI-1) were significantly increased in the plasma of Vivax high patients compared to Vivax low patients and healthy controls (Figures 5A, Figure 5-figure supplement 1A, B).…”

Effects of Gymnema inodorum Leaf Extract on the Alteration of Blood Coagulation Parameters and Platelet Count in Plasmodium berghei-Infected Mice

“…Platelet and erythrocyte sequestration are frequent in the severe forms of malaria, and thrombocytopenia is present [30]. Thrombocytopenia in this study might also be associated with endothelial damage and isolated platelet consumption [31]. Our results showed significant increases in platelet count in mice treated with 250 and 500 mg/kg of GIE and CQ when compared to healthy control, suggesting their role as an acute phase reactant to infection.…”

Cerebral Malaria and Neuronal Implications of Plasmodium Falciparum Infection: From Mechanisms to Advanced Models

“…PAF recruits and activates leukocytes, increases cytokine and chemokine secretion, and modulates vascular permeability. [117,118]…”