期刊
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
卷 184, 期 4, 页码 438-448出版社
AMER THORACIC SOC
DOI: 10.1164/rccm.201009-1422OC
关键词
acute respiratory distress syndrome, human; cell surface receptors; endocytosis; low-density lipoprotein receptor-related protein-1; matrix metalloproteinases
资金
- University Medical Center Giessen and Marburg
- German Research Foundation (DFG) [WY119/1-1, KFO 118, SFB/TR84]
- Excellence Cluster Cardiopulmonary System (ECCPS)
- Bayer Schering Pharma AG
- Lung RX
- Nycomed
- Activaero
- Actelion
- Pfizer
- Novartis
- Intermune
- Excellence Cluster Cardiopulmonary System
- Universities of Giessen and Marburg Lung Center
Rationale: Low-density lipoprotein receptor-related protein-1 (LRP-1) mediates the endocytic clearance of various proteinases, including matrix metalloproteinases (MMPs). The ectodomain of LRP-1 can be shed from the cell surface, releasing a soluble form of this receptor (sLRP-1), which antagonizes ligand endocytosis by cellular LRP-1. Objectives: To assess if increased LRP-1 shedding occurs in the lungs of patients with acute respiratory distress syndrome (ARDS) and may lead to the accumulation of MMPs and subsequent tissue injury. Methods: We determined sLRP-1 levels in bronchoalveolar lavage fluids (BALF) from 46 patients with ARDS and their correlation with MMP concentration and disease severity. In complementary in vitro studies, we investigated the mechanisms underlying the LRP-1 release from the cell surface and its impact on MMP cellular uptake. Measurements and Main Results: sLRP-1 levels were significantly elevated in BALF but not in plasma from patients with ARDS compared with control subjects and further increased in the later course of the disease. Baseline BALF sLRP-1 concentration was positively correlated with disease severity and significantly higher in nonsurvivors compared with survivors. The presence of ARDS BALF enhanced LRP-1 shedding from cultured lung fibroblasts but not from alveolar type II cells or macrophages. This process was blocked when ARDS BALF was supplemented with metalloproteinase inhibitor resulting in enhanced cellular uptake and degradation of MMP-2 and -9. Accordingly, sLRP-1 BALF concentration in patients with ARDS was positively correlated with MMP levels and laminin, a marker of basement membrane disruption. Conclusions: Increased LRP-1 shedding prevents the cellular clearance of MMPs and might thereby contribute to tissue destruction in ARDS lungs.
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