Lysosomal proteases and protease inhibitors in nasal allergy and non-atopic sinusitis

Patterns of protease activity and levels of protease inhibitors were analyzed in both nasal secretions and tissue extracts from patients with nasal allergy and non-atopic sinusitis to investigate the role of proteases in the inflammatory reaction. Protease activity was measured using specific methyl-coumaryl-7-amide substrates. The pattern of protease activity in the nasal secretions of chronic sinusitis patients was similar to that in neutrophil lysate and quite different from that in plasma. Both gluthatione activation testing and inhibition testing using synthetic inhibitors revealed that the majority of proteases in both secretions and tissues are lysosomal thiol proteases such as cathepsins B and L. Neutrophilic elastase is also a major protease in nasal secretions. In acute sinusitis, both protease activity and inhibitor levels were very high, suggesting an interaction between proteases and inhibitors. Cathepsin B and B-like thiol proteases appear to play a key role in prolonging chronic inflammation against the healing process, due to their resistance to plasma inhibitors and the shortage of thiol protease inhibitors. Protease activity in the secretions of nasal allergy patients was very weak, and the reaction between proteases and inhibitors appeared to be weak.