title: Lacritin, a novel human tear glycoprotein, promotes sustained basal tearing and is well tolerated.
abstract: OBJECTIVE
  Lacritin is a novel human tear glycoprotein that promotes basal tear peroxidase secretion by rat lacrimal acinar cells in vitro. This study investigates whether lacritin is prosecretory when added topically to the ocular surface of normal living rabbits, and if so, what is its efficacy and tolerability versus cyclosporine and artificial tears.
  
  
  METHODS
  Purified recombinant human lacritin (1, 10, 50, or 100 μg/mL), inactive lacritin truncation mutant C-25 (10 μg/mL), cyclosporine (0.05%), or artificial tears were topically administered to eyes of normal New Zealand White rabbits either as a single dose or three times daily for 14 days with monitoring of basal tear production. Basal tearing under proparacaine anesthesia was repeatedly assessed throughout and 1 week after chronic treatment ceased. Eyes were examined weekly by slit-lamp biomicroscopy.
  
  
  RESULTS
  Lacritin acutely increased basal tearing to 30% over vehicle at 240 minutes. Three times daily treatment with 10-100 μg/mL lacritin was well tolerated. Basal tearing became progressively elevated 4, 7, and 14 days later and was 50% over baseline (50 μg/mL lacritin) 1 week after treatment had ceased. Cyclosporine elevated tearing to a similar level on days 4 and 7 but had little or no effect on day 14 and had returned to baseline 1 week after ending treatment. C-25 and artificial tears had no effect.
  
  
  CONCLUSIONS
  Lacritin acutely stimulates basal tear flow that is sustained for at least 240 minutes. Two weeks of lacritin treatment three times daily was well tolerated and progressively elevated the basal tear flow. One week after treatment ended, basal tearing was still 50% over baseline. In contrast, cyclosporine triggered mild to moderate corneal irritation and a temporary elevation in tearing.
authors.affiliation: Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia 23501, USA. samudrss@evms.edu
authors.forename: Sandeep
authors.initials: S
authors.lastname: Samudre
authors.forename: Frank A
authors.initials: FA
authors.lastname: Lattanzio
authors.forename: Victoria
authors.initials: V
authors.lastname: Lossen
authors.forename: Alireza
authors.initials: A
authors.lastname: Hosseini
authors.forename: John D
authors.initials: JD
authors.lastname: Sheppard
authors.forename: Robert L
authors.initials: RL
authors.lastname: McKown
authors.forename: Gordon W
authors.initials: GW
authors.lastname: Laurie
authors.forename: Patricia B
authors.initials: PB
authors.lastname: Williams
mesh_terms: D000287:Administration, Topical; D000818:Animals; D016572:Cyclosporine / Q000008:administration & dosage / Q000009:adverse effects; D005136:Eye Proteins / Q000008:administration & dosage* / Q000009:adverse effects; D006023:Glycoproteins / Q000008:administration & dosage* / Q000009:adverse effects; D007429:Intraocular Pressure; D007765:Lacrimal Apparatus / Q000187:drug effects* / Q000378:metabolism; D009883:Ophthalmic Solutions; D011817:Rabbits; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000009:adverse effects; D013666:Tears / Q000378:metabolism*; D013997:Time Factors; D014065:Tonometry, Ocular
chemical_list: D005136:Eye Proteins; D006023:Glycoproteins; C431764:LACRT protein, human; D009883:Ophthalmic Solutions; D011994:Recombinant Proteins; C042434:tear proteins; D016572:Cyclosporine