Budesonide/formoterol effects on metalloproteolytic balance in TGFβ-activated human lung fibroblasts☆

Summary 

In the airways of asthmatic patients, activated fibroblasts account for an excessive matrix production including proteoglycans (PGs). Transforming growth factor-β (TGFβ), metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) play key roles in matrix turnover. It is unclear whether asthma therapy with combination of inhaled glucocorticoids and long-acting β₂-agonists affects metalloproteolytic equilibrium and by that counteracts airway fibrosis.

The effects of the glucocorticoid, budesonide, and the long-acting β₂-agonist, formoterol, on the PG production and the activity of PGs' main regulators: MMP-3, MMP-9, MMP-2 and TIMP-1 were investigated in human lung fibroblasts (HFL-1) treated for 24h with TGFβ1 (10ng/ml) without/with budesonide (10⁻⁹ to 10⁻⁶M) and/or formoterol (10⁻¹¹ to 10⁻⁶M).

TGFβ1 significantly increased production of PGs and TIMP-1, and the activity of MMP-3, MMP-9 and MMP-2. Concurrent budesonide/formoterol combination counteracted the enhanced: PG and TIMP-1 production, MMP-9 activity and MMP-9/TIMP-1 ratio, whereas MMP-2 and MMP-3 were not affected and so their ratios to TIMP-1 were significantly increased. Budesonide or formoterol alone achieved equal effects as budesonide/formoterol on MMP-9 and MMP-9/TIMP-1 ratio but had no effects on TIMP-1, MMP-2 or MMP-3. In the formoterol absence, higher budesonide concentrations were required to reduce the PG production, whereas formoterol alone had no effects.

These results suggest that the budesonide/formoterol combination enhanced metalloproteolytic activity of human lung fibroblasts via a synergistic decrease of TIMP-1, and that this mechanism may be involved in the synergistic inhibition of the TGFβ1-induced PG production. This implies that budesonide/formoterol combination therapy can counteract excessive matrix production and thus pathological airway fibrotic remodeling in asthma.

Keywords: Metalloproteinases, TIMP-1, TGFβ1, Budesonide, Formoterol, Proteoglycans