title: S100 A and B expression in normal and inflamed human limbus.
abstract: OBJECTIVE
  To study the expression of S100 A and B family proteins in normal human limbus and to analyze modification of the expression in inflammatory conditions.
  
  
  METHODS
  The total expression of members of the S100 family and the expression of A4, A8, A9, and B individually were evaluated in nine normal human corneal limbi, collected from cadaver healthy donors, in particular in the limbal epithelial crypts (LECs), and in five inflamed limbi obtained from enucleated eyes. S100 protein distribution was determined with immunohistochemistry staining analysis.
  
  
  RESULTS
  Cytoplasmic expression of total S100 proteins was observed in 100% of LECs; in contrast, the inflamed tissues were completely negative, and faint positivity was observed in only one case. Moreover, cytoplasmic expression of S100 A4 and A9 was uniformly found in the entire LECs in all samples analyzed, while S100 A8 positivity was observed in only 44.4% of cases and only in the cells localized in the central area of the LEC. Positivity for S100 B was not observed in all samples analyzed.
  
  
  CONCLUSIONS
  As reported in the literature, normal limbal epithelial cells show strong expression of S100 proteins. A novel finding of this study was the expression for the limbal epithelial crypts. In particular, S100 A4 and A9, which are normally involved in regulating a wide range of biologic effects, including cell motility, survival, and differentiation, are the most expressed members in healthy limbal crypts. In inflamed tissues, expression of S100 proteins was dramatically decreased. S100 proteins, and in particular S100 A4 and S100 A9, can be useful as markers of early changes in stem cell niches due to inflammation.
authors: Department of Medicine and Science of Ageing, Ophthalmology Clinic, University G. D'Annunzio Chieti-Pescara, Italy.
authors: Mario
authors: M
authors: Nubile
authors: Manuela
authors: M
authors: Lanzini
authors: Roberta
authors: R
authors: Calienno
authors: Rodolfo
authors: R
authors: Mastropasqua
authors: Claudia
authors: C
authors: Curcio
authors: Alessandra
authors: A
authors: Mastropasqua
authors: Luca
authors: L
authors: Agnifili
authors: Leonardo
authors: L
authors: Mastropasqua
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D040501:Calgranulin A / Q000235:genetics* / Q000378:metabolism; D040502:Calgranulin B / Q000235:genetics* / Q000378:metabolism; D016022:Case-Control Studies; D003593:Cytoplasm / Q000378:metabolism; D005819:Genetic Markers; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D007634:Keratitis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016850:Limbus Corneae / Q000166:cytology / Q000378:metabolism* / Q000473:pathology*; D008875:Middle Aged; D009414:Nerve Growth Factors / Q000378:metabolism*; D064568:S100 Calcium Binding Protein beta Subunit; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins / Q000235:genetics* / Q000378:metabolism*; D055153:Stem Cell Niche / Q000235:genetics
chemical_list: D040501:Calgranulin A; D040502:Calgranulin B; D005819:Genetic Markers; D018836:Inflammation Mediators; D009414:Nerve Growth Factors; D064568:S100 Calcium Binding Protein beta Subunit; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins; C077591:S100A4 protein, human
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