Recombinant Human Proteoglycan-4 Mediates Interleukin-6 Response in Both Human and Mouse Endothelial Cells Induced Into a Sepsis Phenotype.

OBJECTIVES:Sepsis is a leading cause of death in the United States. Putative targets to prevent systemic inflammatory response syndrome include antagonism of toll-like receptors 2 and 4 and CD44 receptors in vascular endothelial cells. Proteoglycan-4 is a mucinous glycoprotein that interacts with CD44 and toll-like receptor 4 resulting in a blockade of the NOD-like receptor pyrin domain-containing-3 pathway. We hypothesized that endothelial cells induced into a sepsis phenotype would have less interleukin-6 expression after recombinant human proteoglycan 4 treatment in vitro. DESIGN:Enzyme-linked immunosorbent assay and reverse transcriptase-quantitative polymerase chain reaction to measure interleukin-6 protein and gene expression. SETTING:Research laboratory. SUBJECTS:Human umbilical vascular endothelial cells, human lung microvascular endothelial cells, and transgenic mouse (wild type) ( Cd44+/+Prg4+/+Cd44-/-Cd44tm1HbgPrg4+/+Prg4GT/GTCd44+/+Prg4tm2Mawa/JCd44tm1HbgPrg4tm2Mawa/JINTERVENTIONS:Cells were treated with 100 or 250 ng/mL lipopolysaccharide- Escherichia coliMEASUREMENTS AND MAIN RESULTS:Human umbilical vascular endothelial cell, human lung microvascular endothelial cell, and mouse lung microvascular endothelial cell treated with lipopolysaccharide had significantly increased interleukin-6 protein compared with controls. Recombinant human proteoglycan-4 significantly reduced interleukin-6 in human and mouse endothelial cells. Interleukin-6 gene expression was significantly increased after lipopolysaccharide treatment compared with controls. This response was reversed by 50 or 100 µg/mL recombinant human proteoglycan-4 in 80% of sepsis samples in human umbilical vascular endothelial cells and in 60-73% in human lung microvascular endothelial cells. In Cd44-/-Cd44INTERPRETATION AND CONCLUSIONS:Recombinant human proteoglycan-4 is a potential adjunct therapy for sepsis patients and warrants future in vivo model studies.