Neutrophil serine proteases mediate inflammatory cell recruitment by glomerular endothelium and progression towards dysfunction.
BACKGROUND
Neutrophil recruitment into glomerular tissues and reduced capillary wall integrity has been implicated in the development of vasculitic glomerulonephritis (VGN). This study investigated the stages and mechanisms through which neutrophil serine proteases (SPs), proteinase 3 (PR3) or elastase contribute to endothelial dysfunction.


METHODS
Protease-induced damage to endothelium and adhesion molecule upregulation was measured by viability assays and ELISA. Neutrophil/platelet adhesion to human glomerular and umbilical vein endothelium was assessed using in vitro adhesion assays.


RESULTS
PR3 and elastase (1 µg/mL, 2 h) significantly induced neutrophil adhesion to endothelial cells (EnC) whilst PR3 also enhanced platelet-EnC interactions. This neutrophil adhesion was associated with enhanced P-selectin expression and required CXCL8 receptor involvement, and could be inhibited by blocking the P-selectin ligand PSGL-1. SPs induced damage in a time- and dose-dependent fashion, decreasing cell monolayer integrity followed by cell membrane integrity, inducing caspase-3 activation and p21 cleavage. However, SPs caused significant EnC damage with increasing concentrations and prolonged exposures.


CONCLUSIONS
Neutrophil SPs induce a pro-adhesive phenotype in glomerular endothelium primarily by inducing neutrophil and platelet adhesion that transits to dysfunction after high/prolonged exposures. Dysregulated release of these enzymes within glomeruli may contribute to injury during diseases such as VGN.
Schools of Immunity and Infection, University of Birmingham, Birmingham, UK.
Sahithi J
SJ
Kuravi
Anne
A
Bevins
Simon C
SC
Satchell
Lorraine
L
Harper
Julie M
JM
Williams
G Ed
GE
Rainger
Caroline O S
CO
Savage
Samantha P
SP
Tull
D006801:Humans; D007249:Inflammation / Q000201:enzymology*; D007678:Kidney Glomerulus / Q000201:enzymology* / Q000276:immunology*; D053146:Myeloblastin / Q000502:physiology*; D020556:Neutrophil Infiltration / Q000502:physiology*; D010196:Pancreatic Elastase / Q000502:physiology*; D019459:Urothelium / Q000201:enzymology* / Q000276:immunology*
D010196:Pancreatic Elastase; D053146:Myeloblastin