title: The preservative polyquaternium-1 increases cytoxicity and NF-kappaB linked inflammation in human corneal epithelial cells.
abstract: OBJECTIVE
  In numerous clinical and experimental studies, preservatives present in eye drops have had detrimental effects on ocular epithelial cells. The aim of this study was to compare the cytotoxic and inflammatory effects of the preservative polyquaternium-1 (PQ-1) containing Travatan (travoprost 0.004%) and Systane Ultra eye drops with benzalkonium chloride (BAK) alone or BAK-preserved Xalatan (0.005% latanoprost) eye drops in HCE-2 human corneal epithelial cell culture.
  
  
  METHODS
  HCE-2 cells were exposed to the commercial eye drops Travatan, Systane Ultra, Xalatan, and the preservative BAK. Cell viability was determined using colorimetric MTT (3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and by release of lactate dehydrogenase (LDH). Induction of apoptosis was measured with a using a colorimetric caspase-3 assay kit. DNA binding of the nuclear factor kappa B (NF-κB) transcription factor, and productions of the proinflammatory cytokines, interleukins IL-6 and IL-8, were determined using an enzyme-linked immunosorbent assay (ELISA) method.
  
  
  RESULTS
  Cell viability, as measured by the MTT assay, declined by up to 50% after exposure to Travatan or Systane Ultra solutions which contain 0.001% PQ-1. BAK at 0.02% rather than at 0.001% concentration evoked total cell death signs on HCE-2 cells. In addition, cell membrane permeability, as measured by LDH release, was elevated by sixfold with Travatan and by a maximum threefold with Systane Ultra. Interestingly, Travatan and Systane Ultra activated NF-κB and elevated the secretion of inflammation markers IL-6 by 3 to eightfold and IL-8 by 1.5 to 3.5 fold, respectively, as analyzed with ELISA.
  
  
  CONCLUSIONS
  Eye drops containing PQ-1 evoke cytotoxicity and enhance the NF-κB driven inflammation reaction in cultured HCE-2 cells. Our results indicate that these harmful effects of ocular solutions preserved with PQ-1 should be further evaluated in vitro and in vivo.
authors.affiliation: Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland.
authors.forename: Tuomas
authors.initials: T
authors.lastname: Paimela
authors.forename: Tuomas
authors.initials: T
authors.lastname: Ryhänen
authors.forename: Anu
authors.initials: A
authors.lastname: Kauppinen
authors.forename: Liisa
authors.initials: L
authors.lastname: Marttila
authors.forename: Antero
authors.initials: A
authors.lastname: Salminen
authors.forename: Kai
authors.initials: K
authors.lastname: Kaarniranta
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001548:Benzalkonium Compounds / Q000633:toxicity*; D053148:Caspase 3 / Q000096:biosynthesis; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003008:Cloprostenol / Q000031:analogs & derivatives / Q000494:pharmacology; D003315:Cornea / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis; D016209:Interleukin-8 / Q000096:biosynthesis; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D000077338:Latanoprost; D016328:NF-kappa B / Q000096:biosynthesis*; D009883:Ophthalmic Solutions / Q000494:pharmacology; D011108:Polymers / Q000633:toxicity*; D011310:Preservatives, Pharmaceutical / Q000633:toxicity*; D011461:Prostaglandins F, Synthetic / Q000494:pharmacology; D013778:Tetrazolium Salts; D013844:Thiazoles; D000069557:Travoprost
chemical_list: D001548:Benzalkonium Compounds; D015850:Interleukin-6; D016209:Interleukin-8; D016328:NF-kappa B; D009883:Ophthalmic Solutions; D011108:Polymers; D011310:Preservatives, Pharmaceutical; D011461:Prostaglandins F, Synthetic; D013778:Tetrazolium Salts; D013844:Thiazoles; D003008:Cloprostenol; D000077338:Latanoprost; C058655:polyquaternium 1; D007770:L-Lactate Dehydrogenase; D053148:Caspase 3; C022616:thiazolyl blue; D000069557:Travoprost