L-selectin shedding in sepsis limits leukocyte mediated microvascular injury at remote sites.
BACKGROUND
Increased soluble L-selectin levels have been shown to attenuate local inflammation-mediated microvascular leakage, and failure to generate high levels has been associated with increased risk of acute respiratory distress syndrome in septic patients. We hypothesized that failure to shed L-selectin in systemic inflammation would result in increased local inflammation-induced leukocyte adherence and microvascular leakage.


METHODS
Using intraperitoneal lipopolysaccharide (LPS) or control bicarbonate buffered saline (BBS) and intrascrotal TNFalpha or BBS, mice were randomized to systemic inflammation (LPSip + BBSis), local inflammation (BBSip + TNFis), both (LPSip + TNFis), or control (BBSip+BBSis). Furthermore, mice received intraperitoneal L-selectin Sheddase inhibitor (Ro31-9790) or control vector. With intravital microscopy on cremaster muscle, we measured leukocyte-endothelial cell interactions and microvascular leakage (permeability index). Surface L-selectin was measured by flow cytometry (MCF).


RESULTS
Without Ro31-9790, systemic inflammation attenuated increases induced by local inflammation in leukocyte adherence and vascular leakage. Ro31-9790 significantly increased adherence and leakage in systemic and systemic + local inflammation. L-selectin was shed progressively by increasing degrees of inflammation. Ro31-9790 limited this shedding of L-selectin.


CONCLUSIONS
In systemic inflammation, L-selectin shedding is required to limit local inflammation-mediated leukocyte adherence and microvascular leakage. Failure to shed L-selectin may increase leukocyte-mediated end-organ injury in septic patients.
Ferri
Lorenzo E
LE
Department of Surgery, McGill University, Montreal, Canada. lorenzo.ferri@muhc.mcgill.ca
Chia
Shea
S
Benay
Cassandre
C
Giannias
Betty
B
Christou
Nicolas V
NV
D000818:Animals; D002199:Capillary Permeability / Q000276:immunology*; D002448:Cell Adhesion; D042783:Endothelial Cells / Q000502:physiology; D016650:Fluorescein-5-isothiocyanate; D006877:Hydroxamic Acids / Q000494:pharmacology; D007249:Inflammation / Q000188:drug therapy; D019041:L-Selectin / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008070:Lipopolysaccharides; D008297:Male; D051379:Mice; D009504:Neutrophils / Q000502:physiology*; D011897:Random Allocation; D012611:Scrotum / Q000098:blood supply; D018805:Sepsis / Q000276:immunology / Q000503:physiopathology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D006877:Hydroxamic Acids; D008070:Lipopolysaccharides; C097661:Ro 31-9790; D014409:Tumor Necrosis Factor-alpha; D019041:L-Selectin; D016650:Fluorescein-5-isothiocyanate