title: Milk components inhibit Acanthamoeba-induced cytopathic effect.
abstract: OBJECTIVE
  Acanthamoebae provoke a vision-threatening corneal infection known as Acanthamoeba keratitis (AK). It is thought that Acanthamoeba-specific IgA antibodies present in mucosal secretions such as human tears, milk, and saliva provide protection against infection by inhibiting the adhesion of parasites to host cells. The goal of the present study was to determine whether human mucosal secretions have the potential to provide protection against the Acanthamoeba-induced cytopathic effect (CPE) by an additional mechanism that is independent of IgA.
  
  
  METHODS
  Breast milk was used as a model of human mucosal secretions. In vitro CPE assays were used to examine the CPE inhibitory effect of IgA-depleted milk and various milk fractions obtained by gel filtration. The activity of amebic proteinases was examined by zymography.
  
  
  RESULTS
  IgA-depleted milk inhibited the Acanthamoeba-induced CPE in a concentration-dependent manner. Milk proteins were separated into four major fractions (F1-F4) by gel filtration. Of these four fractions, CPE inhibitory activity was detected largely in fraction F3. In contrast, fractions F1, F2, and F4 lacked CPE inhibitory activity. Moreover, fraction F3, but not F1, F2, or F4, inhibited amebic proteinases.
  
  
  CONCLUSIONS
  These data, in conjunction with published findings showing that amebic proteinases are responsible for the induction of Acanthamoeba CPE, led us to propose that human mucosal secretions have the potential to provide protection against Acanthamoeba-induced CPE by an additional mechanism that is independent of IgA and that involves the inhibition of cytotoxic proteinases of amebae.
authors.affiliation: Department of Anatomy and Cell Biology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA.
authors.forename: Chandrassegar
authors.initials: C
authors.lastname: Saravanan
authors.forename: Zhiyi
authors.initials: Z
authors.lastname: Cao
authors.forename: Janardan
authors.initials: J
authors.lastname: Kumar
authors.forename: Jiazhou
authors.initials: J
authors.lastname: Qiu
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Plaut
authors.forename: David S
authors.initials: DS
authors.lastname: Newburg
authors.forename: Noorjahan
authors.initials: N
authors.lastname: Panjwani
mesh_terms: D000048:Acanthamoeba / Q000187:drug effects* / Q000502:physiology*; D000818:Animals; D002470:Cell Survival; D002478:Cells, Cultured; D002850:Chromatography, Gel; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D019573:Epithelium, Corneal / Q000469:parasitology*; D005260:Female; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000502:physiology; D008858:Microscopy, Phase-Contrast; D008894:Milk Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D008895:Milk, Human / Q000502:physiology*; D008970:Molecular Weight; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors; D011817:Rabbits
chemical_list: D007071:Immunoglobulin A, Secretory; D008894:Milk Proteins; D015800:Protozoan Proteins