Eradication of damaged keratinocytes in cutaneous lichen planus forms demonstrated by evaluation of epidermal and follicular expression of CK15, indices of apoptosis and regulatory protein S100.
The study of cytoskeleton arrangement and its contribution to survival of cell-to-cell contacts appears to be essential for understanding of numerous cellular and tissue processes. Applying CK15, S100 labeling and TUNEL reaction to cutaneous lichen planus subtypes, we found CK15 expression in the outer and inner root sheath of hair follicles, the basal epidermal layer, and eccrine glands. Its follicular expression was decreased in nearby inflammatory infiltrates. The CK15 immunopositivity was mostly described as weak (92.3%) for lichen planus but equally subdivided into weak, moderate and strong in lichen planopilaris (2 = 32.514; df = 4; p < 0.001). The greatly varying apoptotic index was the highest in the lichen planopilaris involving the scalp: 81.2 ±10.7; 87.8 ±10.7 and 88.0 ±10.5 for the basal, spinous and upper epidermal layers, respectively. S100 positive epidermal and follicular cells did not differ in the lesions demonstrated in the study groups; still immunoreactivity was more pronounced in the scalp region of lichen planopilaris. Damage of cell-to-cell contacts was confirmed by electron microscopy. Apart from immunocyte-mediated keratinocyte death, cytoskeleton-based injury and loss of cell-to-cell and matrix contacts may be of great importance, leading to eradication of degrading cells and thus contributing to the pathogenesis of lichen planus.
Department of Infectology and Dermatology, Riga Stradins University, Riga, Latvia. dr.ilzeupeniece@gmail.com.
Ilze
I
Upeniece
Laboratory of Electron Microscopy, Institute of Anatomy and Anthropology, Riga Stradins University, Riga, Latvia.
Valerie
V
Groma
Laboratory of Electron Microscopy, Institute of Anatomy and Anthropology, Riga Stradins University, Riga, Latvia.
Sandra
S
Skuja
Department of Physics, Riga Stradins University, Riga, Latvia.
Vinita
V
Cauce
D000328:Adult; D000368:Aged; D017209:Apoptosis / Q000502:physiology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D053569:Keratin-15 / Q000032:analysis / Q000096:biosynthesis; D015603:Keratinocytes / Q000473:pathology*; D008010:Lichen Planus / Q000473:pathology*; D008297:Male; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D009418:S100 Proteins / Q000032:analysis; D055815:Young Adult
C116015:KRT15 protein, human; D053569:Keratin-15; D009418:S100 Proteins
 apoptosis;  lichen planus;  loss of cell-to-cell contacts;  scarring alopecia; CK15