No abstract

Objective-Cyclooxygenase (COX)-2 is a key regulatory enzyme in the synthesis of prostanoids associated with trauma and inflammation. We investigated the COX-2 gene for functional variants that may influence susceptibility to disease. Methods and Results-The promoter of COX-2 was screened for variants in healthy subjects by use of polymerase chain reaction-based methods. Promoter activity was investigated by using reporter expression experiments in human lung fibroblasts. Patients undergoing coronary artery bypass graft surgery, with measurements of plasma markers linked to COX-2 activity, were genotyped for association studies. A common COX-2 promoter variant, Ϫ765GϾC, was found and shown to be carried by Ͼ25% of a group of healthy UK subjects. The Ϫ765C allele had significantly lower promoter activity compared with Ϫ765G, basally (28Ϯ3% lower, PϽ0.005) and in serum-stimulated cells (31Ϯ2% lower, PϽ0.005). In patients subjected to coronary artery bypass graft surgery, the magnitude of rise in levels of C-reactive protein (CRP) was strongly genotype dependent. Compared with Ϫ765G homozygotes, patients carrying the Ϫ765C allele had significantly lower plasma CRP levels at 1 to 4 days after surgery (14% lower at the peak of CRP levels on day 3, PϽ0.05 for all time points). Key Words: cyclooxygenase-2 Ⅲ promoter variant Ⅲ coronary artery bypass graft surgery Ⅲ C-reactive protein Ⅲ inflammation C yclooxygenase (COX) is a key regulatory enzyme in eicosanoid metabolism, converting free arachidonic acid to prostaglandin (PG)H 2 , from which a number of prostanoids, including PGE 2 , PGI 2 , PGD 2 , and thromboxane, are produced. 1 The prostanoids are important mediators in the control of normal tissue homeostasis and regulate inflammation in response to trauma or infection. 2 Two isoforms of COX have been identified, COX-1 and COX-2, which have common and specific roles. 3 COX-1 is expressed constitutively in most cell types; however, COX-2 is inducible on cell activation and is mainly expressed at sites of inflammation. COX-2 expression is raised in several pathophysiological states, and the use of COX inhibitors to reduce COX-2 activity has proven beneficial in attenuating chronic inflammatory conditions, such as arthritis and inflammatory bowel disease. 4,5 Several million people worldwide regularly use COX inhibitors. Regular use has been shown to decrease the relative risk of developing cardiovascular disease, stroke, and colorectal cancer. 5,6 See page 1516 Conclusions-ForAlthough COX-2 is widely accepted as a proinflammatory agonist and is therefore a suitable target for treating chronic inflammatory disease, there is increasing evidence to suggest that COX-2 has other roles, including anti-inflammatory, antifibrotic, and antithrombotic properties. 7-9 These alternative roles challenge the dogma that COX-2 is ubiquitously a foe, and indeed, there is evidence indicating that with certain tissue injuries, a limited expression of COX-2 can result in pathology, as in pulmonary fibrosis. 8,10 It also appears that COX-...

Acute respiratory distress syndrome (ARDS) is an often fatal condition for which a genetic predisposition is postulated, although no specific genes have been identified to date. Angiotensin converting enzyme (ACE) has a potential role in the pathogenesis of ARDS via effects on pulmonary vascular tone/permeability, epithelial cell survival, and fibroblast activation. Forty-seven percent of the variance in plasma ACE activity is accounted for by the ACE insertion/deletion (I/D) polymorphism, the D allele being associated with higher activity. We therefore hypothesized that the presence of the D allele would be associated with the development of ARDS. Ninety-six white patients fulfilling American/European Consensus Committee criteria for ARDS were genotyped for the ACE polymorphism together with individuals from three comparison groups: 88 white patients with non-ARDS respiratory failure ventilated in the intensive care unit (ICU), 174 ICU patients undergoing coronary artery bypass grafting, and 1,906 individuals from a general population group. DD genotype frequency was increased in the patients with ARDS compared with the ICU (p = 0.00008), coronary artery bypass grafting (p = 0.0009), and general population group (p = 0.00004) control groups and was significantly associated with mortality in the ARDS group (p < 0.02). These data suggest a potential role for renin-angiotensin systems in the pathogenesis of ARDS and for the first time implicate genetic factors in the development and progression of this syndrome.

Mast cells play a potentially important role in fibroproliferative diseases, releasing mediators including tryptase that are capable of stimulating fibroblast proliferation and procollagen synthesis. The mechanism by which tryptase stimulates fibroblast proliferation is unclear, although recent studies suggest it can activate protease-activated receptor (PAR)-2. We therefore investigated the role of PAR-2 in tryptase-induced proliferation of human fetal lung and adult lung parenchymal and airway fibroblasts and, for comparative purposes, adult dermal fibroblasts. Tryptase (0.7-70 mU/ml) induced concentration-dependent increases in proliferation of all fibroblasts studied. Antipain, bis(5-amidino-2-benzimidazolyl)methane, and benzamidine inhibited tryptase-induced fibroblast proliferation, demonstrating that proteolytic activity is required for the proliferative effects of tryptase. RT-PCR demonstrated the presence of PAR-2 mRNA, and immunohistochemical staining localized PAR-2 to the cell surface of lung fibroblasts. In addition, specific PAR-2 activating peptides, SLIGKV and SLIGRL, mimicked the proliferative effects of tryptase. In contrast, human dermal fibroblasts only weakly stained with the PAR-2 antibody, PAR-2 mRNA was almost undetectable, and fibroblasts did not respond to PAR-2 activating peptides. These results suggest that tryptase induces lung, but not dermal, fibroblast proliferation via activation of PAR-2 and are consistent with the hypothesis that the release of tryptase from activated mast cells may play an important role in the fibroproliferative response observed in asthma, chronic obstructive pulmonary disease, and patients with pulmonary fibrosis.

The fibroproliferative phase of acute respiratory distress syndrome (ARDS) has traditionally been regarded as a late event but recent studies that suggest increased lung collagen turnover within 24 h of diagnosis challenge this view. We hypothesized that fibroproliferation is initiated early in ARDS, characterized by the presence of fibroblast growth factor activity in the lung and would relate to clinical outcome. Patients fulfilling American/European Consensus Committee criteria for ARDS and control patients ventilated for non-ARDS respiratory failure underwent bronchoalveolar lavage (BAL) and serum sampling within 24 h of diagnosis and again at 7 d. The ability of BAL fluid (BALF) to stimulate human lung fibroblast proliferation in vitro was examined in relation to concentrations of N-terminal peptide for type III procollagen (N-PCP-III) in BALF/serum and clinical indices. At 24 h, ARDS lavage fluid demonstrated potent mitogenic activity with a median value equivalent to 70% (range 31-164) of the response to serum, and was significantly higher than control lavage (32% of serum response, range 11-42; p < 0.05). At 24 h, serum N-PCP-III concentrations were elevated in the ARDS group compared with control patients (2.8 U/ml; range 0.6-14.8 versus 1.1 U/ml; range 0.4-3.7, p < 0.0001) as were BALF N-PCP-III concentrations (2.9 U/ml; range 0. 6-11.4 versus 0.46 U/ ml; range 0.00-1.63, p < 0.01). In addition, BALF N-PCP-III concentrations at 24 h were significantly elevated in nonsurvivors of ARDS compared with survivors (p < 0.05). At 7 d, the mitogenic activity remained elevated in the ARDS group compared with control (p < 0.05) and was also significantly higher in ARDS nonsurvivors compared with survivors (67%; range 45-120 versus 31%; range 16-64, p < 0.05). These data are consistent with the hypothesis that fibroproliferation is an early response to lung injury and an important therapeutic target.