title: Botulinum toxin B-induced mouse model of keratoconjunctivitis sicca.
abstract: OBJECTIVE
  To develop a mouse model of human chronic dry eye (keratoconjunctivitis sicca [KCS]).
  
  
  METHODS
  Under direct visualization with an operating microscope, CBA/J mice received a transconjunctival injection of saline or 1.25, 5, or 20 milliunits (mU) of botulinum toxin B (BTX-B) into the lacrimal gland. The mice were either left unstressed or were subjected to an air blower for 5 h/d, 5 d/wk in fixed temperature and humidity conditions. Tear production and corneal fluorescein staining were evaluated in all groups before injection and at several time points after. Tear production was measured with phenol red-impregnated cotton threads. Corneal fluorescein staining was photographed under cobalt blue light with a digital camera fitted with a macro lens.
  
  
  RESULTS
  BTX-B-injected mice displayed significantly decreased tear production until the 4-week time point. Throughout all time points, the addition of environmental blower stress did not appear to alter tear production significantly. Linear regression models, used to evaluate the effects of various doses of BTX-B on tear production, showed that doses higher than 1.25 mU did not provide significantly different outcomes. After 3 days, saline-injected mice showed no corneal staining, whereas BTX-B-injected mice displayed various amounts of staining. At the early time point (day 3), there did not appear to be an additional effect of the blower on corneal fluorescein staining. However, at 1, 2, and 4 weeks, the blower stress appeared to increase the amount of corneal fluorescein staining at each BTX-B dose, although not significantly. Furthermore, at 8 to 10 weeks, in the BTX B-injected groups, corneas had persistent staining, even though tear production had already returned to normal levels. Histopathologic analyses revealed no inflammatory cell infiltration of the stroma or acini of the lacrimal glands and conjunctivae of both saline-injected and BTX-B-injected animals.
  
  
  CONCLUSIONS
  Intralacrimal gland injection of BTX-B resulted in persistent corneal fluorescein staining within 3 days, and a significant decrease in aqueous tear production that persisted for 1 month. Intralacrimal gland injection of BTX-B suppressed lacrimation, thereby establishing a dry eye state. This animal model could be a useful tool for investigating the pathogenesis of the chronic condition KCS in humans.
authors.affiliation: Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland 21286, USA.
authors.forename: Olan
authors.initials: O
authors.lastname: Suwan-apichon
authors.forename: Michael
authors.initials: M
authors.lastname: Rizen
authors.forename: Ram
authors.initials: R
authors.lastname: Rangsin
authors.forename: Samantha
authors.initials: S
authors.lastname: Herretes
authors.forename: Johann M G
authors.initials: JM
authors.lastname: Reyes
authors.forename: Kaevalin
authors.initials: K
authors.lastname: Lekhanont
authors.forename: Roy S
authors.initials: RS
authors.lastname: Chuck
mesh_terms: D000818:Animals; D001905:Botulinum Toxins / Q000633:toxicity*; D019274:Botulinum Toxins, Type A; D003315:Cornea / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D019793:Fluorescein / Q000378:metabolism; D015590:Fluorophotometry; D007638:Keratoconjunctivitis Sicca / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D007765:Lacrimal Apparatus / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008808:Mice, Inbred CBA; D013194:Staining and Labeling; D013666:Tears / Q000378:metabolism
chemical_list: C096323:rimabotulinumtoxinB; D001905:Botulinum Toxins; D019274:Botulinum Toxins, Type A; D019793:Fluorescein