Relationship Between Matrix Metalloproteinase-1Gene Polymorphism And Idiopathic Pulmonary Fibrosis

Objective: Idiopathic pulmonary fibrosis is chronic and fatal interstialpulmonary disease with characteristic abnormal lung tissue remodeling.Although the etiology of IPF is unknown, it is likely to involve in aninteraction between environmental and multiple genetic components. MMP-1whose main function is cleave extracellular matrix components, plays animportant role in the formation of pulmonary fibrosis. Recent findings haveshown that there is a functional polymorphism in MMP-1gene promoter and agreat deal of literatures have been reported about correlation between genepolymorphism of MMP-1and various pulmonary diseases such as asthma,COPD,pulmonary tuberculosis and so on. However, there is no report aboutthe correlation between MMP-1polymorphism and IPF at home. The puoposeof the experiment is to explore the differences about the herediatarysusceptibility, investigate the association of a single nucleotide polymorphism(SNP) in the promoter region of-1607bp of the human matrixmetalloproteinase-1(MMP-1) with genetic susceptibility of Han nationalitypatients of HeBei with idiopathic pulmonary fibrosis (IPF), and observe theserum protein concentraction of matrix metalloproteinase-1(MMP-1) andtissue inhibitor of matrix metalloproteinase-1(TIMP-1) in idiopathicpulmonary fibrosis patients, so as to investigate the pathogenesy of idiopathicpulmonary fibrosis.Method: The investigation was designed as a case-control associationstudy with IPF. The subjects were composed of two groups. According to the2002diagnostic standard of 《Diagnostic and Treatment Guidelines(Draft)ofidiopathic pulmonary fibrosis》, the patient group consisted of84Han people'ssubjects(51males and33females) with IPF (mean age66.7±9.5years),whosediagnostic confirmation was based on a detailed clinical assessment. Subjects were excluded from the study if they had a secondary cause of pulmonaryfibrosis or if they had manifestations of acute infection, cancer, embolism,congestive heart failure, diabetes, peptic ulcer, severe osteoporosis,tuberculosis or if they had a treatment of hormone and immunodepressanteven though there was a detailed clinical assessment of IPF. The control groupcomprised ethnically matched healthy control subjects, a total of100healthysubjects (53males and47females) were recruited, In addition none of themwere suffering from any infection, autoimmune, inflammatory disorders andany using immunodepressant, and the mean age in this group was50.2±7.5years.5ml venous blood of the IPF patients and control individuals wascollected in EDTA. Genomic DNA was isolated from peripheral blood withthe use of collected. Genomic DNA was isolated from peripheral blood withthe use of standard methods.ALU Ⅰr estriction enzyme and polymerase chainreaction-restriction fragment length polymorphism(PCR-RFLP) were used todetect the polymorphism in the promoter region of-1607bp of matrixmetalloproteinase-1(MMP-1) in both the IPF patients and the healthy controls.Expression of the serum protein of MMP-1and TIMP-1in both the IPFpatients and the healthy controls was measured by Enzyme-linkedimmunosorbentassay(ELISA). And then, the analysis of their ratio wasneeded.Results:1MMP-1-1607genetic polymorphism1.1The genetype of MMP-1-1607The results showed that there were three genotypes of MMP-1-1607,1G/1G,1G/2G and2G/2G..1G/1G was wild type,1G/2G and2G/2G weremutant type. Healthy control group and the IPF group are in line withHardy-Weinberg genetic equilibrium test (P>0.05), with good comparability.1.2MMP-1genetype frequency distribution between the two groups caseswas as follows:11cases were1G/1G,42cases were1G/2G genetype and47caseswere2G/2G genotype in100cases of the healthy control group.12cases were1G/1G genotype,1G/2G genotype of30cases and2G/2G genotype of42cases in84cases of the IPF group. There was not significant differencebetween two groups on MMP-1genetype frequency distribution (χ2=0.940,P>0.05).1.3MMP-1allele frequency distribution between the two groups was asfollows:the1G allele frequencies was32%and2G allele frequencies was68%in100cases of the healthy control group. And the1G allele frequencies was32.1%and2G allele frequencies was67.9%in84cases of the IPF group.There was no significant difference between two groups on allele frequency ofMMP-1-16071G/2G (χ2=0.001, P>0.05).2.Changes of the serum MMP-1and TIMP-1proiein concentration.2.1Changes of the serum MMP-1protein concentration were374.66±54.18ng/ml,97.45±20.39ng/ml in the IPF group and the control group,respectively. It revealed that the concentration of patients was higher than thatof the normal(P<0.05)2.2Changes of the serum TIMP-1protein concentration were111.10±26.70ng/ml,40.75±11.46ng/ml in the IPF group and the control group,respectively. Compared with the concentration of the normal group, theconcentration significantly increased in the IPF group(P<0.05)2.3Through the comparison of MMP-1protein concentration/TIMP-1protein concentration, the ratios were3.39±1.06and2.72±1.00in the IPFgroup and the control group, respectively. The ratio in the IPF group washigher than in the normal(P<0.05).Conclusion:1. There is no obvious correlation between MMP-1-16071G/2Gpolymorphism and the susceptibility of IPF; meanwhile, in the differentnationalities, there are differences on the polymorphism of MMP-1in thepromoter of1607bp and the susceptibility of IPF.2. Because of proportional imbalance of expression of MMP-1and TIMP-1,so enhanced Inflammation-inducing and fibrogenic effects, resulted in generation and development of IPF.