Serine protease activity of Cur l 1 from Curvularia lunata augments Th2 response in mice

Abstract

Rationale: Studies with mite allergens demonstrated that proteolytic activity augments allergic airway inflammation. This knowledge is limited to few enzyme allergens.

Objective: The objective of this study is to investigate the effect of serine protease Cur l 1 from Curvularia lunata in airway inflammation/hyper-responsiveness.

Methods: Cur l 1 was purified and inactivated using a serine protease inhibitor. Balb/c mice were sensitized with enzymatically active Cur l 1 or C. lunata extract. Sensitized mice were given booster dose on day 14 with active or inactivated Cur l 1. Intranasal challenge was given on day 28, 29, and 30. Airway hyper-responsiveness was measured by plethysmography. Blood, bronchoalveolar lavage fluid (BALF), spleen, and lungs from mice were analyzed for cellular infiltration, immunoglobulins, and cytokine levels.

Results: Mice challenged with enzymatically active Cur l 1 demonstrated significantly higher airway inflammation than inactive Cur l 1 group mice (p < 0.01). There was a significant difference in serum IgE and IgG1 levels among mice immunized with active Cur l 1 and inactive Cur l 1 (p < 0.01). IL-4 and IL-5 were higher in BALF and splenocyte culture supernatant of active Cur l 1 than inactive Cur l 1 mice. Lung histology revealed increased eosinophil infiltration, goblet cell hyperplasia and mucus secretion in active group.

Conclusion: Proteolytic activity of Cur l 1 plays an important role in airway inflammation and the inactivated Cur l 1 has potential to be explored for immunotherapy.