title: Tear fluid extracellular DNA: diagnostic and therapeutic implications in dry eye disease.
abstract: OBJECTIVE
  To determine the abundance of extracellular DNA (eDNA) in tear fluid of patients with dry eye disease (DED) and to report clinical outcomes after DNase I eyedrops use to reduce excessive tear fluid eDNA.
  
  
  METHODS
  Tear fluid was collected from healthy control subjects and patients with DED. The eDNA abundance was determined with the PicoGreen dye assay. The DED symptoms and clinical signs were recorded and correlated with eDNA abundance. Two patients with DED having excessive eDNA in tear fluid were treated with DNase I eyedrops.
  
  
  RESULTS
  The PicoGreen dye assay measures tear fluid eDNA abundance after a 2-minute incubation time. With longer incubations, admixed cells also contribute to eDNA measurements. The mean (SE) eDNA abundance in healthy control subjects' tear fluid was 1.4 (0.2) μg/mL. The mean (SE) eDNA abundance in tear fluid of patients with nonautoimmune DED, autoimmune DED, and graft versus host disease was significantly higher: the values were 2.9 (0.6), 5.2 (1.2), and 9.1 (2.3) μg/mL, respectively (P < 0.05). In most of these patients, the PicoGreen dye kinetic assay of tear fluid showed an increase in fluorescence signal due to the presence of viable cells in tear fluid. Tear fluid eDNA had the best correlation with corneal Rose Bengal staining (r = 0.55). Treatment of patients having DED with DNase I eyedrops reduced eDNA abundance, abrogated signal increase, and improved comfort.
  
  
  CONCLUSIONS
  Excessive eDNA is present in tear fluid of patients with dry eyes. A novel therapeutic approach for managing DED may be to measure eDNA abundance in tear fluid with the PicoGreen dye assay and reduce excessive amounts with DNase I eyedrops.
authors.affiliation: Corneal Neurobiology Laboratory, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, College of Medicine, Chicago, Illinois.
authors.forename: Sapna
authors.initials: S
authors.lastname: Tibrewal
authors.forename: Joy
authors.initials: J
authors.lastname: Sarkar
authors.forename: Sarmad H
authors.initials: SH
authors.lastname: Jassim
authors.forename: Sonal
authors.initials: S
authors.lastname: Gandhi
authors.forename: Snehal
authors.initials: S
authors.lastname: Sonawane
authors.forename: Shweta
authors.initials: S
authors.lastname: Chaudhary
authors.forename: Yong-Soo
authors.initials: YS
authors.lastname: Byun
authors.forename: Yair
authors.initials: Y
authors.lastname: Ivanir
authors.forename: Joelle
authors.initials: J
authors.lastname: Hallak
authors.forename: John H
authors.initials: JH
authors.lastname: Horner
authors.forename: Martin
authors.initials: M
authors.lastname: Newcomb
authors.forename: Sandeep
authors.initials: S
authors.lastname: Jain
mesh_terms: D004247:DNA / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000008:administration & dosage*; D015352:Dry Eye Syndromes / Q000175:diagnosis* / Q000188:drug therapy* / Q000378:metabolism; D005260:Female; D005456:Fluorescent Dyes; D015590:Fluorophotometry; D006801:Humans; D008297:Male; D008875:Middle Aged; D009883:Ophthalmic Solutions / Q000008:administration & dosage; D009930:Organic Chemicals; D012395:Rose Bengal; D013666:Tears / Q000166:cytology / Q000378:metabolism*
chemical_list: D005456:Fluorescent Dyes; D009883:Ophthalmic Solutions; D009930:Organic Chemicals; C099476:PicoGreen; D012395:Rose Bengal; D004247:DNA; D003850:Deoxyribonuclease I
keywords: DNase I; PicoGreen dye assay; dry eye; extracellular DNA; tear fluid