Characterization of Circulating Heparan Sulfate During Pediatric Sepsis: A Pilot Study

Introduction: In pediatric sepsis, the glycocalyx attached to the luminal surface of vascular endothelial cells (EC) is systemically damaged, contributing to endotheliopathy and end-organ injury. The glycocalyx is comprised of proteoglycans to which glycosaminoglycans, predominantly heparan sulfate (HS), are attached. We previously observed increased circulating HS levels in children with sepsis and discovered a mechanistic link between HS shedding and pathological EC activation. As structural modifications to HS may influence aberrant signaling in ECs, we performed a pilot study to characterize circulating HS fragments in children with sepsis and explore associations between HS disaccharide sulfation and plasma levels of angiopoietin-2 (Ang2), a marker of EC activation.


Methods: Plasma was collected from 19 children with sepsis at PICU admission and from 9 healthy children (controls). LC-MS/MS was used to measure sulfated and nonsulfated HS disaccharides (i.e., hexuronic acid, or ∆UA, linked to glucosamine, or GlcNAc) and 3-O-sulfated tetrasaccharides in plasma after enzymatic digestion of unfractionated HS. Ang2 was measured via ELISA. Differences in levels of HS fragments between sepsis and control cohorts were evaluated, and HS correlations with Ang2 levels and clinical outcomes were determined.


Results: Children with sepsis demonstrated higher total HS levels relative to controls with a higher percentage of unsulfated disaccharides. HS in children with sepsis contained less of the disaccharide ∆UA-GlcNAc6S and the tetrasaccharide ∆UA-GlcNS-IdoA2S-GlcNS3S. Total levels of HS correlated with Ang2 (Spearman’s ρ=0.477, p=0.0118) as did levels of ∆UA-GlcNAc (ρ=0.578, p=0.0016) and ∆UA-GlcNS6S (ρ=0.469, p=0.0136). No correlations with clinical outcomes were observed.


Conclusions: In this pilot study, we identified that HS fragments in children with sepsis appear to be less sulfated than those observed in healthy children, which may indicate increased sulfatase activity during the acute phase of sepsis. Additionally, we found correlations between specific HS sulfation patterns and Ang2 levels that warrant further mechanistic study. Together, these data offer novel insights into potential linkages between HS and vascular pathobiology occurring in pediatric sepsis.