title: Mucin deficiency causes functional and structural changes of the ocular surface.
abstract: MUC5AC is the most abundant gel-forming mucin in the ocular system. However, the specific function is unknown. In the present study, a Muc5ac knockout (KO) mouse model was subject to various physiological measurements as compared to its wide-type (WT) control. Interestingly, when KO mice were compared to WT mice, the mean tear break up time (TBUT) values were significantly lower and corneal fluorescein staining scores were significantly higher. But the tear volume was not changed. Despite the lack of Muc5ac expression in the conjunctiva of KO mice, Muc5b expression was significantly increased in these mice. Corneal opacification, varying in location and severity, was found in a few KO mice but not in WT mice. The present results suggest a significant difference in the quality, but not the quantity, of tear fluid in the KO mice compared to WT mice. Dry eye disease is multifactorial and therefore further evaluation of the varying components of the tear film, lacrimal unit and corneal structure of these KO mice may help elucidate the role of mucins in dry eye disease. Because Muc5ac knockout mice have clinical features of dry eye, this mouse model will be extremely useful for further studies regarding the pathophysiology of the ocular surface in dry eye in humans.
authors.affiliation: Department of Pharmacology and Toxicology, University of Arizona, Tucson, Arizona, United States of America.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Floyd
authors.forename: Xu
authors.initials: X
authors.lastname: Zhou
authors.forename: Christopher
authors.initials: C
authors.lastname: Evans
authors.forename: Olivia J
authors.initials: OJ
authors.lastname: Rompala
authors.forename: Lingxiang
authors.initials: L
authors.lastname: Zhu
authors.forename: Mingwu
authors.initials: M
authors.lastname: Wang
authors.forename: Yin
authors.initials: Y
authors.lastname: Chen
mesh_terms: D000818:Animals; D001706:Biopsy; D017931:DNA Primers / Q000235:genetics; D015352:Dry Eye Syndromes / Q000235:genetics / Q000378:metabolism; D005123:Eye / Q000378:metabolism* / Q000503:physiopathology; D005128:Eye Diseases / Q000235:genetics / Q000378:metabolism; D019793:Fluorescein / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D018895:Microsatellite Repeats / Q000235:genetics; D055271:Mucin 5AC / Q000235:genetics / Q000378:metabolism*; D009077:Mucins / Q000172:deficiency*; D009154:Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D013666:Tears / Q000378:metabolism
chemical_list: D017931:DNA Primers; C524679:Muc5ac protein, mouse; D055271:Mucin 5AC; D009077:Mucins; D019793:Fluorescein