title: The bacterial cell envelope as delimiter of anti-infective bioavailability - An in vitro permeation model of the Gram-negative bacterial inner membrane.
abstract: Gram-negative bacteria possess a unique and complex cell envelope, composed of an inner and outer membrane separated by an intermediate cell wall-containing periplasm. This tripartite structure acts intrinsically as a significant biological barrier, often limiting the permeation of anti-infectives, and so preventing such drugs from reaching their target. Furthermore, identification of the specific permeation-limiting envelope component proves difficult in the case of many anti-infectives, due to the challenges associated with isolation of individual cell envelope structures in bacterial culture. The development of an in vitro permeation model of the Gram-negative inner membrane, prepared by repeated coating of physiologically-relevant phospholipids on Transwell®filter inserts, is therefore reported, as a first step in the development of an overall cell envelope model. Characterization and permeability investigations of model compounds as well as anti-infectives confirmed the suitability of the model for quantitative and kinetically-resolved permeability assessment, and additionally confirmed the importance of employing bacteria-specific base materials for more accurate mimicking of the inner membrane lipid composition - both advantages compared to the majority of existing in vitro approaches. Additional incorporation of further elements of the Gram-negative bacterial cell envelope could ultimately facilitate model application as a screening tool in anti-infective drug discovery or formulation development.
authors: Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Center for Infection Research (HZI), Department of Drug Delivery, Campus E8 1, 66123 Saarbrücken, Germany. Electronic address: Florian.Graef@hemholtz-hzi.de.
authors: Florian
authors: F
authors: Graef
authors: Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Center for Infection Research (HZI), Department of Drug Delivery, Campus E8 1, 66123 Saarbrücken, Germany. Electronic address: Branko.Vukosavljevic@helmholtz-hzi.de.
authors: Branko
authors: B
authors: Vukosavljevic
authors: Institut Galien Paris Sud, UMR 8612, Univ Paris-Sud, CNRS, Université Paris-Saclay, 5 rue J.B. Clément, F-92290 Châtenay-Malabry, France. Electronic address: jean-philippe.michel@u-psud.fr.
authors: Jean-Philippe
authors: JP
authors: Michel
authors: Saarland University, Department of Pharmacy, Pharmaceutical and Medicinal Chemistry, Campus C2 3, 66123 Saarbrücken, Germany. Electronic address: marius.wirth@uni-saaland.de.
authors: Marius
authors: M
authors: Wirth
authors: Saarland University, Department of Pharmacy, Pharmaceutical and Medicinal Chemistry, Campus C2 3, 66123 Saarbrücken, Germany.
authors: Oliver
authors: O
authors: Ries
authors: Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Center for Infection Research (HZI), Department of Drug Delivery, Campus E8 1, 66123 Saarbrücken, Germany. Electronic address: Chiara.DeRossi@helmholtz-hzi.de.
authors: Chiara
authors: C
authors: De Rossi
authors: Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Center for Infection Research (HZI), Department of Drug Delivery, Campus E8 1, 66123 Saarbrücken, Germany. Electronic address: Maike.Windbergs@helmholtz-hzi.de.
authors: Maike
authors: M
authors: Windbergs
authors: Institut Galien Paris Sud, UMR 8612, Univ Paris-Sud, CNRS, Université Paris-Saclay, 5 rue J.B. Clément, F-92290 Châtenay-Malabry, France. Electronic address: veronique.rosilio@u-psud.fr.
authors: Véronique
authors: V
authors: Rosilio
authors: Saarland University, Department of Pharmacy, Pharmaceutical and Medicinal Chemistry, Campus C2 3, 66123 Saarbrücken, Germany. Electronic address: christian.ducho@uni-saarland.de.
authors: Christian
authors: C
authors: Ducho
authors: Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Center for Infection Research (HZI), Department of Drug Delivery, Campus E8 1, 66123 Saarbrücken, Germany. Electronic address: Sarah.Gordon@helmholtz-hzi.de.
authors: Sarah
authors: S
authors: Gordon
authors: Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Center for Infection Research (HZI), Department of Drug Delivery, Campus E8 1, 66123 Saarbrücken, Germany; Saarland University, Department of Pharmacy, Biopharmacy and Pharmaceutical Technology, Campus E8 1, 66123 Saarbrücken, Germany. Electronic address: Claus-Michael.Lehr@helmholtz-hzi.de.
authors: Claus-Michael
authors: CM
authors: Lehr
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000494:pharmacology; D001682:Biological Availability; D002462:Cell Membrane / Q000378:metabolism*; D002463:Cell Membrane Permeability; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D010743:Phospholipids
keywords: Gram-negative bacterial cell envelope; In vitro permeation model; Permeability investigations; Permeation kinetics