title: The effect of liposome encapsulation on the pharmacokinetics of recombinant secretory leukocyte protease inhibitor (rSLPI) therapy after local delivery to a guinea pig asthma model.
abstract: OBJECTIVE
  Inhaled recombinant Secretory Leukocyte Protease Inhibitor (rSLPI) has shown potential for treatment of inflammatory lung conditions. Rapid inactivation of rSLPI by cathepsin L (Cat L) and rapid clearance from the lungs have limited clinical efficacy. Encapsulation of rSLPI within 1,2-Dioleoyl-sn-Glycero-3-[Phospho-L-Serine]:Cholesterol liposomes (DOPS-rSLPI) protects rSLPI against Cat L inactivation in vitro. We aimed to determine the effect of liposomes on rSLPI pharmacokinetics and activity in vitro and after local delivery to the airways in vivo.
  
  
  METHODS
  Transport of DOPS-rSLPI and free-rSLPI across a polarised air-liquid epithelial monolayer was measured. An asthma guinea pig model was administered either DOPS-rSLPI liposomes or free-rSLPI by intratracheal instillation.
  
  
  RESULTS
  Apparent permeability (P(app)) of free-rSLPI was significantly higher at 4.9 x 10⁻⁶ cm/s than for DOPS-rSLPI, P(app) of 2.05 x 10⁻⁷ cm/s, confirmed by in vivo studies. Plasma rSLPI concentrations were highest in free-rSLPI-treated animals compared with those treated with DOPS-rSLPI; there also appeared to be a trend for higher intracellular rSLPI content in animals dosed with DOPS-rSLPI compared to free-rSLPI. Eosinophil influx was recorded as a measure of inflammation. Pre-dosing with either free-rSLPI or DOPS-rSLPI prevented inflammatory response to antigen challenge to levels comparable to control animals.
  
  
  CONCLUSIONS
  Encapsulation of rSLPI in DOPS:Chol liposomes improves stability, reduces clearance and increases residence time in the lungs after local delivery.
authors.affiliation: School of Pharmacy, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Aileen
authors.initials: A
authors.lastname: Gibbons
authors.forename: Danielle
authors.initials: D
authors.lastname: Padilla-Carlin
authors.forename: Ciara
authors.initials: C
authors.lastname: Kelly
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Hickey
authors.forename: Clifford
authors.initials: C
authors.lastname: Taggart
authors.forename: Noel G
authors.initials: NG
authors.lastname: McElvaney
authors.forename: Sally-Ann
authors.initials: SA
authors.lastname: Cryan
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D018927:Anti-Asthmatic Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy* / Q000235:genetics; D001692:Biological Transport; D002460:Cell Line; D002463:Cell Membrane Permeability; D004195:Disease Models, Animal; D004339:Drug Compounding; D016503:Drug Delivery Systems / Q000379:methods*; D004355:Drug Stability; D017097:Electric Impedance; D004797:Enzyme-Linked Immunosorbent Assay; D006168:Guinea Pigs; D006801:Humans; D008081:Liposomes; D008297:Male; D020545:Respiratory Mucosa / Q000378:metabolism / Q000502:physiology; D053481:Secretory Leukocyte Peptidase Inhibitor / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000627:therapeutic use
chemical_list: D018927:Anti-Asthmatic Agents; D008081:Liposomes; D053481:Secretory Leukocyte Peptidase Inhibitor