Activation of mouse protease-activated receptor-2 induces lymphocyte adhesion and generation of reactive oxygen species.
OBJECTIVE
Protease-activated receptor-2 (PAR-2) is expressed on lymphocytes and endothelial cells, and plays a significant role in inflammatory reactions. Since leukocyte-endothelial cell interaction and reactive oxygen species (ROS) generation are hallmarks of the development of inflammation, the effects of PAR-2 activation by trypsin on lymphocyte adhesion and ROS generation was examined utilising PAR-2 wild type and knockout (PAR-2-/-) mice.


METHODS
Lymphocyte adhesion to the luminal surface of mouse isolated aortae was measured using 51Cr-labelled leukocytes and ROS generation from isolated lymphocytes was quantified using chemiluminescence.


RESULTS
Trypsin induced adhesion of lymphocytes when added exogenously to the endothelial surface of the aorta for 30 min. Similarly, increased lymphocyte adhesion was also observed when mice were injected with trypsin intravenously 24 h prior to the adhesion assay, an effect which was partly ICAM-1 mediated. Trypsin also increased ROS generation from isolated mouse lymphocytes in a dose-dependent manner. The increase in lymphocyte adhesion and ROS production in response to trypsin were abolished in PAR-2-/- mice indicating a PAR-2 dependent mechanism. Superoxide dismutase had a greater inhibitory effect in PAR-2-/- mice compared to wild type mice when lymphocytes were stimulated with PMA but not trypsin.


CONCLUSIONS
The present study indicates that activation of PAR-2 may be an important factor in modulating lymphocyte adhesion and ROS generation. The results have implications for developing anti-inflammatory strategies.
Lim
S Y
SY
Department of Physiology & Pharmacology, University of Strathclyde, Glasgow, UK.
Tennant
G M
GM
Kennedy
S
S
Wainwright
C L
CL
Kane
K A
KA
D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D039481:CD11b Antigen / Q000032:analysis; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005434:Flow Cytometry; D066298:In Vitro Techniques; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008163:Luminescent Measurements / Q000379:methods; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D022423:Myeloid Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D019007:P-Selectin / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D044464:Receptor, PAR-2 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013154:Spleen / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013482:Superoxide Dismutase / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology
D039481:CD11b Antigen; D019007:P-Selectin; D017382:Reactive Oxygen Species; D044464:Receptor, PAR-2; D018799:Intercellular Adhesion Molecule-1; D013482:Superoxide Dismutase; D014357:Trypsin; D013755:Tetradecanoylphorbol Acetate