Heparin attenuates TNF-alpha induced inflammatory response through a CD11b dependent mechanism.
BACKGROUND
In addition to its anticoagulant properties, heparin has anti-inflammatory effects, the molecular and mechanistic bases of which are incompletely defined.


OBJECTIVE
The current studies were designed to test the hypothesis that heparin abrogates the expression or function of leucocyte-endothelial adherence molecules which are fundamental to the acute inflammatory response.


METHODS
The effects of heparin on tumour necrosis factor alpha (TNF-alpha) induced leucocyte rolling, adhesion, and migration as well as vascular permeability were assessed in rat mesenteric venules using intravital microscopy. Expression of adhesion molecules was quantitated using a double radiolabelled monoclonal antibody (mAb) binding technique in vivo (P-selectin, intercellular cell adhesion molecule type 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1)) or flow cytometry (CD11a, CD11b, and L-selectin). Ex vivo binding of heparin to neutrophils was assessed by flow cytometry.


RESULTS
TNF-alpha induced a significant increase in leucocyte rolling, adhesion, and migration, and vascular permeability, coincident with a significant increase in expression of P-selectin, ICAM-1, and VCAM-1. Ex vivo assessment of blood neutrophils showed significant upregulation of CD11a and CD11b and significant downregulation of L-selectin within five hours of TNF-alpha administration. Heparin pretreatment significantly attenuated leucocyte rolling, adhesion, and migration but did not affect expression of cell adhesion molecules or vascular permeability elicited by TNF-alpha administration. Binding of heparin was significantly increased on blood neutrophils obtained five hours after TNF-alpha administration. Preincubation with an anti-CD11b mAb but not with an anti-CD11a or anti-L-selectin antibody significantly diminished heparin binding ex vivo.


CONCLUSIONS
Our results support the concept that the anti-inflammatory effects of heparin involve attenuation of a CD11b dependent adherent mechanism.
Salas
A
A
Gastroenterology Department, Hospital Clínic, IDIBAPS, Barcelona, Spain.
Sans
M
M
Soriano
A
A
Reverter
J C
JC
Anderson
D C
DC
Piqué
J M
JM
Panés
J
J
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism / Q000494:pharmacology*; D002199:Capillary Permeability / Q000187:drug effects; D002448:Cell Adhesion / Q000187:drug effects; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000378:metabolism; D006493:Heparin / Q000378:metabolism / Q000494:pharmacology*; D015212:Inflammatory Bowel Diseases / Q000209:etiology / Q000517:prevention & control*; D007962:Leukocytes / Q000187:drug effects / Q000502:physiology; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism*; D008297:Male; D008642:Mesenteric Veins / Q000187:drug effects; D009504:Neutrophils / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D015815:Cell Adhesion Molecules; D016169:Lymphocyte Function-Associated Antigen-1; D014409:Tumor Necrosis Factor-alpha; D006493:Heparin