Alpha1-antitrypsin suppresses TNF-alpha and MMP-12 production by cigarette smoke-stimulated macrophages.
We have previously observed that mice exposed to cigarette smoke and treated with exogenous alpha(1)-antitrypsin (A1AT) were protected against the development of emphysema and against smoke-induced increases in serum TNF-alpha. To investigate possible mechanisms behind this latter observation, we cultured alveolar macrophages lavaged from C57 mice. Smoke-conditioned medium caused alveolar macrophages to increase secretion of macrophage metalloelastase (MMP-12) and TNF-alpha, and this effect was suppressed in a dose-response fashion by addition of A1AT. Macrophages from animals exposed to smoke in vivo and then lavaged also failed to increase MMP-12 and TNF-alpha secretion when the animals were pretreated with A1AT. Because proteinase activated receptor-1 (PAR-1) is known to control MMP-12 release, macrophages were treated with the G protein-coupled receptor inhibitor, pertussis toxin; this suppressed both TNF-alpha and MMP-12 release, while a PAR-1 agonist (TRAP) increased TNF-alpha and MMP-12 release. Smoke-conditioned medium caused increased release of the prothrombin activator, tissue factor, from macrophages. Hirudin, a thrombin inhibitor, and aprotinin, an inhibitor of plasmin, reduced smoke-mediated TNF-alpha and MMP-12 release, and A1AT inhibited both plasmin and thrombin activity in a cell-free functional assay. These findings extend our previous suggestion that TNF-alpha production by alveolar macrophages is related to MMP-12 secretion. They also suggest that A1AT can inhibit thrombin and plasmin in blood constituents that leak into the lung after smoke exposure, thereby preventing PAR-1 activation and MMP-12/TNF-alpha release, and decreasing smoke-mediated inflammatory cell influx.
Churg
Andrew
A
Department of Pathology, University of British Columbia, 2211 Wesbrook Mall, Vancouver, BC, V6T 2B5 Canada. achurg@interchange.ubc.ca
Wang
Xiaoshan
X
Wang
Rong D
RD
Meixner
Scott C
SC
Pryzdial
Edward L G
EL
Wright
Joanne L
JL
D000818:Animals; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D004305:Dose-Response Relationship, Drug; D005341:Fibrinolysin / Q000378:metabolism; D005343:Fibrinolytic Agents / Q000378:metabolism; D006629:Hirudins / Q000378:metabolism; D006801:Humans; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000378:metabolism*; D053508:Matrix Metalloproteinase 12 / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D037342:Pertussis Toxin / Q000378:metabolism; D012906:Smoke; D012907:Smoking / Q000009:adverse effects; D013917:Thrombin / Q000378:metabolism; D014026:Nicotiana / Q000009:adverse effects; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D000515:alpha 1-Antitrypsin / Q000378:metabolism* / Q000494:pharmacology
D017077:Culture Media, Conditioned; D005343:Fibrinolytic Agents; D006629:Hirudins; D012906:Smoke; D014409:Tumor Necrosis Factor-alpha; D000515:alpha 1-Antitrypsin; D037342:Pertussis Toxin; D013917:Thrombin; D005341:Fibrinolysin; D053508:Matrix Metalloproteinase 12