Investigation On Polymorphism Of Variable Numbers Of Tandem Repeat (VNTR) In The Intron 2 Of IL-1RA In Patients With Idiopathic Pulmonary Fibrosis

Objective: To explore the differences about the hereditary susceptibility, polymorphism of variable numbers of tandem repeat (VNTR) in the intron 2 of IL-1RA between the Han nationality patients of He Bei and other nationality's with idiopathic pulmonary fibrosis by studying the correlation of polymorphism of VNTR in the intron 2 of IL-1RA and idiopathic pulmonary fibrosis of the Han nationality, and observe the serum protein concentration of Interleukin-1 receptor antagonist(IL-1RA) and Interleukin-1β(IL-1β) in idiopathic pulmonary fibrosis patients, so as to investigate the pathogenesy of idiopathic pulmonary fibrosis.Methods: The investigation was designed as a case-control association study with IPF. The subjects were composed of two groups. According to the 2002 diagnostic standard of《Diagnostic and Treatment Guidelines(Draft)of idiopathic pulmonary fibrosis》, the patient group consisted of 63 Han people's subjects(40 males and 23 females) with IPF (mean age 67.3±10.5 years),which diagnostic confirmation was based on a detailed clinical assessment. Subjects were excluded from the study if they had a secondary cause of pulmonary fibrosis 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 immunodepressant even though there was a detailed clinical assessment of IPF. The control group comprised ethnically matched healthy control subjects, a total of 57 healthy subjects (32 males and 25 females) were recruited, In addition none of them were suffering from any infection, autoimmune, inflammatory disorders and any using immunodepressant, and the mean age in this group was 50.6±7.9 years. 5ml venous blood of the IPF patients and control individuals was collected. Genomic DNA was isolated from peripheral blood with the use of standard methods. The method of polymerase chain reaction-restriction (PCR) was used to detect the polymorphism of VNTR in the intron 2 of IL-1RA in both the IPF patients and the healthy controls. Expression of the serum protein of IL-1RA and IL-1βin both the IPF patients and the healthy controls was measured by Enzyme-linked immunosorbent assay( ELISA). And then, the analysis of their ratio was needed.Results:1 The polymorphism of VNTR in the intron 2 of IL-1RA was as follows: frequencies ofⅠ/Ⅰ,Ⅰ/Ⅱ,Ⅱ/ⅡandⅢ/Ⅲgenotypes were 51(80.95%), 11(17.46%), 0 and 1(1.59%) in the IPF group ,however 47 ( 82.46 %), 6 ( 10.53 % ) , 1(1.75%) and 3 (5.26 % ) in the control group , respectively; Frequencies of alleleⅠ,ⅡandⅢwere 113(89.68%), 11(8.73%) and 2(1.59%) in the IPF group, however 100(87.72%), 8(7.02%), 6(5.26%) in the control group. There was no difference from distribution of polymorphism of VNTR in the intron 2 of IL-1RA and frequencies of various allele in two groups(χ2=3.342, P>0.05;χ2=2.674, P>0.05)2 Changes of the serum IL-1RA and IL-1βprotein concentration2.1 Changes of the serum IL-1RA protein concentration were 312.07±221.50 and 700.35±646.00 in the IPF group and the control group, respectively. It revealed that the concentration of the patients was lower than that of the normal (P<0.05).2.2 Changes of the serum IL-1βprotein concentration were 395.41±40.83 and 19.49±10.44 in the IPF group and the control group, respectively. Compared with the concentration of the normal group, the concentration significantly increased in the IPF group (P<0.05).2.3 Through the comparison of the IL-1RA protein concentration/ the IL-1βprotein concentration, the ratios were 4.10±4.83 and 41.95±41.30 in the IPF group and the control group, respectively. The ratio in the patients was lower than that in the normal (P<0.05). Conclusion:1 There is no obvious correlation between the polymorphism of VNTR in the intron 2 of IL-1RA and the susceptibility of IPF; meanwhile, in the different nationalities, there are differences on the polymorphism of VNTR in the intron 2 of IL-1RA and the susceptibility of IPF.2 Because increased IL-1βand decreased IL-1RA lead to the proportional imbalance, so IL-1RA doesn't antagonize IL-1βeffectively. Enhanced Inflammation-inducing and fibrogenic effects of IL-1βcould result in the generation and development of IPF.