Abstract
The mechanism of action of pirfenidone in idiopathic pulmonary fibrosis (IPF) has not been fully elucidated. To offer additional insight, we evaluated the change in the cytokine profile in exhaled breath condensate (EBC) following a six-month treatment with pirfenidone in patients with IPF. EBC concentrations of interleukin (IL)-6, IL-8, IL-15, TNF-α and VEGF-A were assessed with ELISA and compared at baseline and after six months of pirfenidone treatment. Twenty-nine patients with IPF and 13 controls were evaluated at baseline. With the exception of IL-8 concentration, which was lower in patients with IPF when compared to controls (p = 0.005), the cytokine levels did not differ between the groups. Despite the use of a high sensitivity assay, IL-8 reached detectable values only in 24% of IPF patients. EBC analysis after six months of treatment with pirfenidone did not reveal any differences in the cytokine levels. The change in EBC vascular endothelial growth factor A (VEGF-A) correlated with the change in the 6 min walk distance (r = 0.54, p = 0.045). We conclude that a six-month treatment with pirfenidone did not significantly change the EBC cytokine profile. Our findings support the potential usefulness of VEGF-A as a marker in IPF. The low EBC IL-8 level in patients with IPF is a novel finding which needs confirmation in larger studies.
Highlights
Idiopathic pulmonary fibrosis (IPF) is a chronic progressive fibrosing interstitial lung disease of unknown etiology, which occurs primarily in older adults
We found a limited utility of ELISA measurements for IL-15 and TNFα in exhaled breath condensate (EBC) from these patients
We showed that EBC concentrations of IL-8 are significantly lower in nontreated patients with IPF when comp1ared to controls
Summary
Idiopathic pulmonary fibrosis (IPF) is a chronic progressive fibrosing interstitial lung disease of unknown etiology, which occurs primarily in older adults. It is currently hypothesized that IPF is a consequence of repeated microinjuries to the alveolar epithelium, which lead to dysregulation of wound healing and causes fibrosis by activating myofibroblasts [3]. Both the innate and adaptive systems appear to be involved in IPF. Macrophages are one of the most studied innate immune cells in IPF pathogenesis. They can contribute to fibrosis by secreting immune molecules, such as profibrotic tumor necrosis factor-alpha (TNFα), interleukin (IL)-1, IL-6, IL-8 and vascular endothelial growth factor (VEGF), which can both promote or inhibit the cascade of fibrosis [2]. High blood IL-8 concentrations were shown to be associated with disease activity [7] and increased mortality in IPF [8]
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