Expression of caspase-3 and structural changes associated with apoptotic cell death of keratinocytes in oral lichen planus.
OBJECTIVE
Apoptosis appears to be the mode of cell death by which damaged cells are removed from the lesional tissue. The aim of this study was to examine keratinocyte apoptosis and caspase-3 (CPP32) expression in oral lichen planus (OLP).


METHODS
Paraffin-embedded samples of OLP (n = 30) and normal oral mucosa (NOM; n = 5) were prepared for haematoxylin-eosin (H & E), immunohistochemistry and electron microscopy. The number of apoptotic cells and the proportion of total cells that were either apoptotic (apoptotic index; AI) or mitotic (mitotic index; MI) were assessed in H & E stained sections. An immunostaining-intensity-distribution index (IIDI; proportion of stained cells x staining intensity) was used to assess CPP32 immunoreactivity.


RESULTS
Results showed a significant increase in the number of apoptotic cells in OLP (P < 0.001). In OLP, all apoptotic bodies were found in the basal and prickle epithelial layers. Compared with NOM, the AI was significantly greater in atrophic (P < 0.05), reticular (P < 0.001) and plaque-like (P < 0.01) OLP. The MI was significantly greater in plaque-like OLP (P < 0.01). The proportion of CPP32-positive cells and the IIDI were significantly greater in all forms of OLP compared with NOM (P < 0.05). No difference in CPP32 expression was evident between clinical forms of OLP. Electron microscopy confirmed the light microscopic finding of apoptosis.


CONCLUSIONS
Keratinocyte apoptosis and caspase-3 expression co-localized to the basal and parabasal epithelial layers, suggesting that proliferating epithelial cells may be targeted for destruction in OLP. Differences in epithelial AI and MI may underlie the various clinical and histological appearances of OLP.
Tobón-Arroyave
S I
SI
Laboratorio de Inmunodetección y Bioanálisis, Facultad de Odontología, Universidad de Antioquia, Medellín, Colombia. labinbio@chami.udea.edu.co
Villegas-Acosta
F A
FA
Ruiz-Restrepo
S M
SM
Vieco-Durán
B
B
Restrepo-Misas
M
M
Londoño-López
M L
ML
D000328:Adult; D000368:Aged; D017209:Apoptosis; D001284:Atrophy; D053148:Caspase 3; D020169:Caspases / Q000032:analysis*; D002467:Cell Nucleus / Q000201:enzymology / Q000648:ultrastructure; D002843:Chromatin / Q000201:enzymology / Q000648:ultrastructure; D004396:Coloring Agents; D003593:Cytoplasm / Q000201:enzymology / Q000648:ultrastructure; D004792:Enzyme Precursors / Q000032:analysis*; D004847:Epithelial Cells / Q000201:enzymology / Q000473:pathology; D005456:Fluorescent Dyes; D006801:Humans; D015603:Keratinocytes / Q000201:enzymology* / Q000473:pathology; D017676:Lichen Planus, Oral / Q000201:enzymology* / Q000473:pathology; D008214:Lymphocytes / Q000201:enzymology / Q000473:pathology; D008854:Microscopy, Electron; D008875:Middle Aged; D008938:Mitosis; D009061:Mouth Mucosa / Q000201:enzymology / Q000473:pathology
D002843:Chromatin; D004396:Coloring Agents; D004792:Enzyme Precursors; D005456:Fluorescent Dyes; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases