Coagulation disorders and the IPF puzzle

Antithrombin III as predictive indicator of survival in idiopathic pulmonary fibrosis (IPF) patients treated with nintedanib: a preliminary study

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease often managed with nintedanib, a tyrosine kinase inhibitor targeting several profibrotic pathways. Although clotting processes are involved in wound healing and repair in the lung, there are no data on the role of antithrombin III (ATIII) in IPF patients treated with nintedanib. A previous proteomic analysis of serum of IPF patients before and after 1 year of nintedanib treatment showed differential protein expression of ATIII.

AIMS

Here we used quantitative methods to evaluate differential ATIII concentrations in IPF patients before and after 1 year of nintedanib treatment and to assess the potential of ATIII as a prognostic biomarker in IPF patients.

METHODS

Serum levels of ATIII were measured by enzyme-linked immunosorbent assay in 14 IPF patients before and after 1 year of nintedanib treatment.

RESULTS

A statistically significant inverse correlation was found between serum ATIII concentrations and pulmonary function test parameters in all patients at baseline and follow up. Baseline serum ATIII and bronchoalveolar lavage (BAL) neutrophils proved to be reliable predictors of poor prognosis. A baseline ATIII threshold of 126.5 μg/mL discriminated survivors from non-survivors.

CONCLUSIONS

After 12 months of antifibrotic treatment, IPF patients with high serum ATIII concentrations and high BAL neutrophil percentages had a poor prognosis and increased survival risk. The results of this preliminary study suggest that ATIII has potential as a biomarker of IPF severity and in predicting response to nintedanib therapy. As a marker, ATIII showed several advantages over BAL neutrophil percentage.

Pharmacological Targeting of Protease-Activated Receptor 2 Affords Protection from Bleomycin-Induced Pulmonary Fibrosis

Idiopathic pulmonary fibrosis is the most devastating diffuse fibrosing lung disease that remains refractory to therapy. Despite increasing evidence that protease-activated receptor 2 (PAR-2) contributes to fibrosis, its importance in pulmonary fibrosis is under debate. We addressed whether PAR-2 deficiency persistently reduces bleomycin-induced pulmonary fibrosis or merely delays disease progression and whether pharmacological PAR-2 inhibition limits experimental pulmonary fibrosis. Bleomycin was instilled intranasally into wild-type or PAR-2-deficient mice in the presence/absence of a specific PAR-2 antagonist (P2pal-18S). Pulmonary fibrosis was consistently reduced in PAR-2-deficient mice throughout the fibrotic phase, as evident from reduced Ashcroft scores (29%) and hydroxyproline levels (26%) at d 28. Moreover, P2pal-18S inhibited PAR-2-induced profibrotic responses in both murine and primary human pulmonary fibroblasts (p < 0.05). Once daily treatment with P2pal-18S reduced the severity and extent of fibrotic lesions in lungs of bleomycin-treated wild-type mice but did not further reduce fibrosis in PAR-2-deficient mice. Importantly, P2pal-18S treatment starting even 7 d after the onset of fibrosis limits pulmonary fibrosis as effectively as when treatment was started together with bleomycin instillation. Overall, PAR-2 contributes to the progression of pulmonary fibrosis, and targeting PAR-2 may be a promising therapeutic strategy for treating pulmonary fibrosis.