title: Impact of β-1,3-glucan isolated from Euglena gracilis on corneal epithelial cell migration and on wound healing in a rat alkali burn model.
abstract: OBJECTIVE
  To determine the impact of β-1,3-glucan isolated from Euglena gracilis on corneal epithelial cell migration and on wound healing in a rat alkali burn model.
  
  
  METHODS
  Immortalized human corneal epithelial cells (HCECs) were cultured in media with 50, 100 and 200 μg/mL laminarin (β-1,3- and β-1,6-glucans), β-1,3-glucan and hyaluronic acid (HA)-conjugated β-1,3-glucan; Dulbecco's modified Eagle's medium (DMEM)/nutrient mixture F-12 (negative control) and serum containing DMEM/nutrient mixture F-12 (positive control). Migration assays were conducted via the manual scraping of HCECs. Next, alkali injuries were induced using 1 N NaOH in 40 eyes of 40 Sprague-Dawley male rats. The injury-only group (n = 10) received topical phosphate-buffered saline four times a day for 2 d. The study groups received 200 μg/mL topical laminarin (n = 10), β-1,3-glucan (n = 10) and β-1,3-glucan HA (n = 10). Using slit-lamp biomicroscopy, injured corneas were evaluated in terms of re-epithelialization and opacity, and tissue sections were histologically analyzed.
  
  
  RESULTS
  Migration assay rates were enhanced as laminarin and β-1,3-glucan increased, compared to negative control cells (all p < 0.05). In the comparison between β-1,3-glucan and its HA conjugate form, β-1,3-glucan-HA showed more enhanced migration rate than β-1,3-glucan (p < 0.05). In rat alkali burn model, wound-healing ratio was greatest in β-1,3-glucan-HA groups (96.0 ± 4.1%), followed by β-1,3-glucan (86.0 ± 6.5%), laminarin (67.0 ± 7.5%) and injury-only group (54.0 ± 6.5%) (p < 0.0001; ANOVA). The opacity score was also lowest in β-1,3-glucan-HA groups (3.0 ± 0.75), followed by β-1,3-glucan (3.4 ± 0.5), laminarin (3.7 ± 0.8) and injury-only group (4.7 ± 0.46) (p < 0.0001; ANOVA) Histologically, relatively fewer polymorphonuclear leukocytes infiltrated the corneal stroma in the β-1,3-glucan and β-1,3-glucan-HA groups, compared to the injury-only group.
  
  
  CONCLUSIONS
  β-1,3-Glucan, particularly when conjugated with HA, promoted epithelial wound healing in vitro and suppressed the acute inflammatory reaction in corneal alkali burns.
authors.affiliation: Department of Ophthalmology, St. Vincent Hospital, College of Medicine, The Catholic University of Korea , Seoul , Korea .
authors.forename: Jin A
authors.initials: JA
authors.lastname: Choi
authors.forename: Tae-Hoon
authors.initials: TH
authors.lastname: Oh
authors.forename: Jun-Sub
authors.initials: JS
authors.lastname: Choi
authors.forename: Dong-Jin
authors.initials: DJ
authors.lastname: Chang
authors.forename: Choun-Ki
authors.initials: CK
authors.lastname: Joo
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000468:Alkalies / Q000633:toxicity; D000818:Animals; D002057:Burns, Chemical / Q000188:drug therapy* / Q000473:pathology; D002461:Cell Line, Transformed; D002465:Cell Movement / Q000187:drug effects; D003318:Corneal Opacity / Q000139:chemically induced / Q000188:drug therapy / Q000473:pathology; D004195:Disease Models, Animal; D019573:Epithelium, Corneal / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D005056:Euglena gracilis / Q000737:chemistry; D005126:Eye Burns / Q000139:chemically induced* / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014945:Wound Healing / Q000187:drug effects*; D047071:beta-Glucans / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D000276:Adjuvants, Immunologic; D000468:Alkalies; D047071:beta-Glucans; C033363:beta-1,3-glucan