Monitoring protease activity in human sputum samples by FRET-based probes via statistics-based fluorescence image analysis

Abstract

The activitiy of proteases play a crucial role in inflammatory processes as they contribute to white blood cell infiltration and the gradual destruction of the extracellular lung matrix in chronic inflammation. The activity levels of certain proteases such as neutrophil elastase (NE), cathepsin S and the matrix metalloproteases 9 and 12 (MMP-9, MMP-12) might be useful indicators for the progression of diseases such as cystic fibrosis or chronic obstructive pulmonary disease (COPD). We recently introduced the small molecule FRET protease reporters NEmo (for NE) and LaRee (for MMP-12) which enable the monitoring of protease activity at the single cell level by means of fluorescence microscopy. However, analysis of the corresponding imaging data and translating the results into easily interpretable measures for clinicians, have been very time-consuming and challenging.