title: Matrix metalloproteinase-12 (MMP-12) SNP affects MMP activity, lung macrophage infiltration and protects against emphysema in COPD.
abstract: BACKGROUND
  Recent genetic and animal studies have implicated matrix metalloproteinase-12 (MMP-12) in the pathogenesis of chronic obstructive pulmonary disease (COPD). It has previously been shown that individuals homozygous for the A/A allele of rs652438 in MMP-12 are over-represented among patients with severe COPD (n=1517). A study was undertaken to examine the functional basis of these findings.
  
  
  METHODS
  rs652438 A and G variants were generated by site-directed mutagenesis and transfected into COS7 cells where they were expressed. Casein zymography and a specific FRET activity assay were used to compare MMP-12 activity between alleles. Cell migration was examined using a transwell assay. Patients from two COPD cohorts were genotyped for rs652438 and associated with inflammatory cell number in bronchoalveolar lavage fluid (n=10) and induced sputum (n=262); the emphysema score (n=1428) was assessed by CT scanning.
  
  
  RESULTS
  Mean MMP activity was 2.95-fold higher by zymography (p=0.0049) and 3.45-fold higher by FRET assay (p=0.0001) for the A allele than the G allele. Mean migration of COS7 cells expressing the A allele was 2.31-fold greater than for those expressing the G allele (p=0.0001). Macrophage numbers were greater in bronchoalveolar lavage fluid (1.28-fold increase, p=0.033) and induced sputum (1.58-fold increase, p=0.083) of A/A individuals compared with A/G heterozygotes. The presence of the A allele was dose-dependently associated with increased emphysema (p=0.016).
  
  
  CONCLUSIONS
  The rs652438 SNP alters MMP-12 activity with the A allele being more active, which is associated with increased macrophage infiltration and emphysema in the lungs of patients with COPD. These findings further implicate MMP-12 and this SNP in COPD.
authors: Division of Therapeutics and Molecular Medicine and NIHR Respiratory Biomedical Research Unit, Queens Medical Centre, University of Nottingham, D Floor, South Block, Queen's Medical Centre, Nottingham NG7 2UH, UK.
authors: Imran
authors: I
authors: Haq
authors: Gillian E
authors: GE
authors: Lowrey
authors: Noor
authors: N
authors: Kalsheker
authors: Simon R
authors: SR
authors: Johnson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D019556:COS Cells; D002470:Cell Survival / Q000235:genetics; D002633:Chemotaxis / Q000235:genetics; D002522:Chlorocebus aethiops; D015331:Cohort Studies; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D053508:Matrix Metalloproteinase 12 / Q000096:biosynthesis / Q000235:genetics*; D008875:Middle Aged; D016297:Mutagenesis, Site-Directed; D020641:Polymorphism, Single Nucleotide; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000201:enzymology / Q000235:genetics*; D011656:Pulmonary Emphysema / Q000201:enzymology / Q000209:etiology / Q000235:genetics*; D013183:Sputum / Q000166:cytology; D014162:Transfection
chemical_list: D053508:Matrix Metalloproteinase 12