Elevated plasma TGF-β₁ levels in patients with chronic obstructive pulmonary disease

Summary 

Background

Transforming growth factor-β₁ (TGF-β₁), a multifunctional cytokine, has been implicated to be responsible for the increased deposition of extracellular matrix in the airways, and increased submucosal collagen expression in chronic obstructive pulmonary disease (COPD). We determined plasma TGF-β₁ levels in patients with COPD and explored its association with common functional polymorphisms of TGF-β₁ gene at C-509T and T869C in the development of COPD in a case–control study.

Methods

Stable COPD patients who were ever smokers, and age and pack-years smoked matched healthy controls (n = 205 in each group) were recruited for measurement of plasma TGF-β₁ levels using commercially available ELISA kit, and genotyped at C-509T and T869C functional polymorphisms of TGF-β₁ gene using polymerase chain reaction and restriction fragment length polymorphism (PCR–RFLP).

Results

COPD patients had significantly elevated plasma TGF-β₁ levels in comparison to healthy controls irrespective of the genotypes. Allele frequencies and genotype distributions at both polymorphic sites were not different among COPD patients or controls. TGF-β₁ levels were inversely correlated (Pearson's correlation analysis) with FEV₁ (% predicted) (p < 0.001) and FVC (% predicted) (p < 0.001).

Conclusion

The findings of elevated plasma TGF-β₁ levels in patients with COPD suggest that TGF-β₁ may play a role in COPD pathogenesis. The C-509T and T869C functional polymorphisms of TGF-β₁ gene do not represent a genetic predisposition to COPD susceptibility in Hong Kong Chinese patients.

Keywords: Chronic obstructive pulmonary disease, Genetic polymorphism, Plasma, Transforming growth factor-β₁