lactoferrin and Acanthamoeba-Keratitis

Lactoferrin (LF) is an iron-binding basic glycoprotein that has an antimicrobial effect against certain microbes. The purpose of this study is to evaluate the amoebicidal effect of bovine milk LF (bLF) against Acanthamoeba clinical-isolate trophozoites, which cause severe keratitis. Most of the risk factor for Acanthamoeba keratitis is from wearing soft contact lenses (SCLs). Acanthamoeba trophozoites were incubated in bovine LF (bLF) solution, and the ratios of viability and encystment were determined with microscopic analysis of cyst formation. The amoebicidal effect of bLF was assessed by Trypan blue assay. The ratios of viable cells in the presence of iron-free bLF (apo-bLF), native-bLF, and iron-saturated bLF (Fe-bLF) at the concentration of 10 μmol/L for 60 min were 7.7% ± 4.6%, 80.7% ± 10.1%, and 97.3% ± 1.5%, respectively. Apo-bLF showed potent amoebicidal effect against Acanthamoeba trophozoites, but Fe-bLF did not have this effect. After treating with apo-bLF, most dead cells were nonglobular forms of trophozoites but not cystic forms. Encystment of Acanthamoeba was assessed by the sarkosyl-calcofluor white assay. The encystment ratios treated with 0.5% propylene glycol (positive control) and 10 μmol/L apo-bLF for 24 h were 96.12% ± 10.6% and 0.47% ± 0.5%, respectively. These results suggest that the amoebicidal effect of apo-bLF without encystment might lead to the prevention of contamination of Acanthamoeba in SCL stock cases.

Topics: Acanthamoeba; Acanthamoeba Keratitis; Amebicides; Animals; Anti-Infective Agents; Cattle; Lactoferrin; Milk; Trophozoites

Acanthamoeba keratitis is a painful and progressive sight-threatening infection. However, the precise mechanisms associated with the pathogenesis and pathophysiology of Acanthamoeba keratitis remain incompletely understood. Using tears from healthy individuals and an Acanthamoeba keratitis patient, we demonstrated that both subjects exhibited similar levels of Acanthamoeba-specific IgA as demonstrated by Western blotting and enzyme-linked immunosorbent assays. However, normal tears were slightly more potent in reducing Acanthamoeba binding to human corneal epithelial cells, compared with tears from Acanthamoeba keratitis patient (P>0.05 using paired T-test, one-tail distribution). Neither normal tears nor Acanthamoeba keratitis tears had any protective effects on Acanthamoeba-mediated corneal epithelial cell cytotoxicity. Both lysozyme and lactoferrin which are major constituents of the tear film and possess antibacterial properties exhibited no significant effects on Acanthamoeba binding to and cytotoxicity of human corneal epithelial cells. The role of contact lens wear in Acanthamoeba keratitis is discussed further.

Topics: Acanthamoeba; Acanthamoeba Keratitis; Adult; Animals; Cell Survival; Contact Lenses; Epithelium, Corneal; Humans; Immunoglobulin A, Secretory; Lactoferrin; Male; Muramidase; Tears