Analysis of an IL-10 polymorphism in idiopathic pulmonary fibrosis.
Idiopathic pulmonary fibrosis (IPF) is a chronic progressive fibrotic disorder of the lung parenchyma. We have demonstrated changes in IL-10 protein production by alveolar macrophages (AMs) from patients with IPF, which we hypothesise could be because of an IL-10 gene polymorphism. We have screened the coding sequence and 3' untranslated region of IL-10 for polymorphisms using single-standard conformational polymorphism analysis. A novel polymorphism was identified resulting in a G to A substitution of +43 nucleotides from the start codon changing glycine to arginine at amino acid 15 of the signal peptide sequence. We have introduced the signal peptide mutation into the IL-10 gene and compared secretion of the mutant and wild-type forms after transient transfection of COS-7 cells. Our studies showed that the signal peptide mutation did not have a significant effect on secretion at 24 h post-transfection (P=0.4529 by Mann-Whitney test). However, by 48 h there are significantly lower levels of mutant IL-10 (P=0.0515). There were no differences in the level of cell-associated IL-10 at either 24 or 48 h (P=0.9296 and 0.4268). We suggest that the mutation could affect the efficiency of protein translocation and signal peptide cleavage resulting in lower levels of IL-10 protein secretion.
Whittington
H A
HA
Lung Research Group, University of Bristol Medical School Unit, Southmead Hospital, Westbury on Trym, Bristol, UK.
Freeburn
R W
RW
Godinho
S I H
SI
Egan
J
J
Haider
Y
Y
Millar
A B
AB
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D005260:Female; D006801:Humans; D016753:Interleukin-10 / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009154:Mutation; D018807:Polymorphism, Single-Stranded Conformational; D011658:Pulmonary Fibrosis / Q000235:genetics* / Q000276:immunology*
D016753:Interleukin-10