Genotypic variation in the transforming growth factor-beta1 gene: association with transforming growth factor-beta1 production, fibrotic lung disease, and graft fibrosis after lung transplantation.
BACKGROUND
Transforming growth factor (TGF)-beta1 is a profibrogenetic cytokine that has been implicated in the development of fibrosis in transplanted tissues. In this study, we have analyzed the genetic regulation of TGF-beta1 production in lung transplant recipients.


METHODS
A polymerase chain reaction-single-stranded conformational polymorphism technique was used to detect polymorphisms in the TGF-beta1 gene from genomic DNA. Polymorphisms were shown to correlate with in vitro TGF-beta1 production by stimulated lymphocytes. A single-specific oligonucleotide probe hybridization method was devised to screen for these polymorphisms in lung transplant groups and controls.


RESULTS
We have identified five polymorphisms in the TGF-beta1 gene: two in the promoter region at positions -800 and -509, one at position +72 in a nontranslated region, and two in the signal sequence at positions +869 and +915. The polymorphism at position +915 in the signal sequence, which changes codon 25 (arginine-->proline), is associated with interindividual variation in levels of TGF-beta1 production. Stimulated lymphocytes of homozygous genotype (arginine/arginine) from control individuals produced significantly more TGF-beta1 in vitro (10037+/-745 pg/ml) compared with heterozygous (arginine/proline) individuals (6729+/-883 pg/ml; P<0.02). In patients requiring lung transplantation for a fibrotic lung condition, there was an increase in the frequency of the high-producer TGF-beta1 allele (arginine). This allele was significantly associated with pretransplant fibrotic pathology (P<0.02) (n=45) when compared with controls (n=107) and with pretransplant nonfibrotic pathology (P<0.004) (n=50). This allele was also associated with allograft fibrosis in transbronchial biopsies when compared with controls (P<0.03) and with nonallograft fibrosis (P<0.01).


CONCLUSIONS
The production of TGF-beta1 is under genetic control, and this in turn influences the development of lung fibrosis. Hence, the TGF-beta1 genotype has prognostic significance in transplant recipients.
Awad
M R
MR
School of Biological Sciences, University of Manchester, United Kingdom.
El-Gamel
A
A
Hasleton
P
P
Turner
D M
DM
Sinnott
P J
PJ
Hutchinson
I V
IV
D000483:Alleles; D014644:Genetic Variation / Q000235:genetics*; D005838:Genotype; D006801:Humans; D016040:Lung Transplantation; D011110:Polymorphism, Genetic / Q000235:genetics*; D011183:Postoperative Complications; D011658:Pulmonary Fibrosis / Q000209:etiology / Q000235:genetics*; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics*
D016212:Transforming Growth Factor beta