RhDNase and Biodistribution of PMN Serine Proteases in Cystic Fibrosis Sputum
RhDNase and Biodistribution of PMN Serine Proteases in Cystic Fibrosis Sputum
Serine proteases belonging to the elastase family are mainly responsible for lung tissue
 destruction as observed during cystic fibrosis. But anti-inflammatory therapies based on
 systemic or aerosolized protease-inhibitors administration, have not given the expected
 results until now. One reason would be the impaired access of therapeutic inhibitors to their
 molecular targets. It was recently shown that neutrophils actively secrete neutrophil
 extracellular traps (NETs) made of DNA that binds cationic proteases among other molecules.
 NETs together with DNA passively released from dead neutrophils contribute to the viscosity
 of CF expectorations which explains that rhDNase treatment fluidifies expectorations and
 improves the patient status. Preliminary experiments in our laboratory have shown that DNA
 degradation was associated with a significant increase of proteolytic activity in the sputum
 soluble fraction. However the efficacy of exogenous inhibitors is also improved in these
 conditions. Using the specific substrates and methodologies that we developed previously to
 measure cell-surface associated proteolytic activities, we will study the effects of DNase on
 the activity of individual proteases, their biodistribution in sputum and their regulation by
 potential therapeutic inhibitors. Enzymatic, immunochemical and microscopic (confocal and
 scanning) techniques will first be used for ex vivo studies on sputa freshly collected at the
 adult and paediatric CRCM in Tours, then on sputa from patients before and after
 administration of aerosolized rhDNase. We hypothesize that a better understanding of the
 biodistribution of neutrophil serine proteases and especially their binding to DNA will help
 designing new therapeutic strategies that facilitate inhibitor access to their protease
 targets.
Inclusion Criteria:

 -  cystic fibrosis disease

 -  with rhDNase treatment

 Exclusion Criteria:

 -  Acute push of the bronchopulmonary attack or hospitalization for treatment of the
 disease during 2 weeks previous

 -  Exposure to a antibiotherapy or treatment by corticoids