title: Ocular inflammation and corneal permeability alteration by benzalkonium chloride in rats: a protective effect of a myosin light chain kinase inhibitor.
abstract: OBJECTIVE
  The aim of this study was to evaluate the interest of an ophthalmic eyedrop preparation containing a myosin light chain kinase (MLCK) inhibitor, ML-7, in the treatment of ocular surface. The local protective effect on the inflammation and the increase of corneal permeability induced by benzalkonium (BAK) was evaluated.
  
  
  METHODS
  An ocular instillation of 10 lL BAK at a concentration of 0.1% in PBS was performed on rats. The eyes were rinsed with sterilized water, 10 minutes after BAK preceded by instillation at T -24, -12, and -0.5 hours of 10 lL ofML-7: 100 μg (10 μL) into a gel form vehicle. All animals were sacrificed 6 hours after BAK instillation. The eyes were isolated for study in a masked manner. The ocular surface inflammation was assessed by measuring the inflammatory cell infiltration by a histologic quantitative analysis and for total ocular myeloperoxidase (MPO) activity. The tight junction permeability was tested.
  
  
  RESULTS
  Instillation of 0.1% BAK increased the inflammation of the eye. The quantitative analysis showed an increase in the number of eosinophil and neutrophil polynuclears, and MPO activity. Pretreatment with ML-7 reduced inflammation (P < 0.05). The vehicle alone produced no notable effects. BAK instillation also thickened the fluorescent corneal front on frozen sections, indicating an increase of tight junction permeability. Pretreatment with ML-7 suppressed BAK-induced alterations of paracellular permeability while the vehicle had no visible effects.
  
  
  CONCLUSIONS
  Our study indicates that the inhibition of corneal cytoskeleton contraction by an MLCK inhibitor prevents BAK-induced ocular inflammatory response, and that ML-7 may be a new and original preparation in the treatment of ocular surface pathologies.
authors.affiliation: Unité de Neurogastroentérologie INRA - 180, Chemin de Tournefeuille, Toulouse, France.
authors.forename: Marie Thérèse
authors.initials: MT
authors.lastname: Droy-Lefaix
authors.forename: Lionel
authors.initials: L
authors.lastname: Bueno
authors.forename: Philippe
authors.initials: P
authors.lastname: Caron
authors.forename: Eric
authors.initials: E
authors.lastname: Belot
authors.forename: Olivier
authors.initials: O
authors.lastname: Roche
mesh_terms: D000818:Animals; D001381:Azepines / Q000627:therapeutic use*; D001548:Benzalkonium Compounds / Q000633:toxicity*; D003315:Cornea / Q000187:drug effects* / Q000378:metabolism; D015352:Dry Eye Syndromes / Q000188:drug therapy; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D004804:Eosinophils / Q000378:metabolism; D007634:Keratitis / Q000139:chemically induced / Q000378:metabolism / Q000517:prevention & control*; D008297:Male; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors*; D009281:Naphthalenes / Q000627:therapeutic use*; D009504:Neutrophils / Q000378:metabolism; D009883:Ophthalmic Solutions; D010539:Permeability; D009195:Peroxidase / Q000378:metabolism; D011310:Preservatives, Pharmaceutical / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D019108:Tight Junctions / Q000187:drug effects* / Q000378:metabolism
chemical_list: D001381:Azepines; D001548:Benzalkonium Compounds; D004791:Enzyme Inhibitors; D009281:Naphthalenes; D009883:Ophthalmic Solutions; D011310:Preservatives, Pharmaceutical; C070571:ML 7; D009195:Peroxidase; D009219:Myosin-Light-Chain Kinase