| Summary: | Background:Interactions between the endothelium and infected erythrocytes, microvascular dysfunction and parasite sequestration play major roles in the pathogenesis of severe falciparum malaria. The glycocalyx is a carbohydrate-rich layer lining the endothelium mediating NO production and vascular homeostasis. The role of the glycocalyx in falciparum malaria and the association with disease severity is not known. Methods:We prospectively enrolled Indonesian inpatients (≥18 years old) with severe (SM) or moderately-severe (MSM) falciparum malaria and healthy controls (HCs). Glycocalyx breakdown products were measured in enrolment samples of urine (glycosaminoglycans; dimethylmethylene blue [GAG-DMMB] and liquid chromatography-tandem mass spectrometry [GAG-MS] assays) and plasma (syndecan-1; ELISA), and related to vascular NO bioavailability (reactive hyperemia-peripheral arterial tonometry). Results:A total of 129 subjects (SM=43, MSM=57, HC=29) were recruited. Syndecan-1 (µg/ml), GAG-DMMB and GAG-MS (g/mol creatinine) were increased in SM [median (range) 332.4 (85-3-1913), 3.16 (0.04-27.9) and 4.73 (2.02-27.13)] compared to MSM [99.1 (19.9-767.6), 1.28 (0.03-9.3) and 4.44 (1.19-13.87)], and HCs [48.9 (32.3-88.3), 0.11 (0.02-1.9) and 2.55 (0.73-10.19)]; P<0.001. In SM, GAG-DMMB and GAG-MS were increased in non-survivors (n=3) [median (IQR): 6.72 (3.80-27.87) and 12.15 (7.88-17.20)] compared to survivors n=39 [(3.10 (0.46-4.5) and 4.64 (2.02-15.20)]; P=0.03. Glycocalyx degradation was associated with parasite biomass in MSM (r=0.31, P=0.03 [syndecan-1]; r=0.48 [GAG-DMMB] and r=0.43 [GAG-MS], P<0.001), and SM patients (r=0.29, P=0.04, r=0.47; P=0.002 and r=0.33, P=0.04), and inversely associated with endothelial NO bioavailability. Conclusions:Increased endothelial glycocalyx breakdown is associated with impaired vascular NO, severe disease and fatal outcome in adults with falciparum malaria, likely contributing to pathogenesis.
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