Glycocalyx Breakdown is Associated with Severe Disease and Fatal Outcome in Plasmodium falciparum Malaria.
Yeo TW., Weinberg JB., Lampah DA., Kenangalem E., Bush P., Chen Y., Price RN., Young S., Zhang HY., Millington D., Granger DL., Anstey NM.
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.