Objective: Some previous studies have shown important modifications of the basement membrane of psoriatic skin,
which could play a key role in alterations of keratinocyte proliferation and differentiation. Changes in distribution of
the laminin α1 chain, together with fibronectin, might influence keratinocyte growth, and thus could be responsible
for the initiation of psoriasis. In the view of these considerations, we have aimed to determine the expression
pattern of laminin and of fibronectin, besides the structural alterations of the epidermis, dermis, and
dermoepidermal junction in involved psoriatic skin.
Material and methods: Fourteen male psoriasis vulgaris patients and 6 healthy volunteers were studied
retrospectively. All psoriatic patients had chronic and stable psoriatic plaque, which had not been treated. Sections
were stained with haematoxylin and eosin (H-E), and periodic acid Schiff (PAS) reagent, and were stained
immunohistochemically using laminin and fibronectin kits.
Results: Histological examination of psoriatic skin showed elongated rete ridges, parakeratosis, epidermal
intercellular oedema, exositosis of mononuclear cells into the epidermis, and mononuclear cell inflammation in the
dermis. PAS staining revealed the large interruptions of the basement membrane. In psoriatic skin samples, the
staining of laminin showed discontinuous, weak, and an uneven disruption in the basement membrane. Staining for
fibronectin was pronounced below the basement membrane and showed a reticular or fibrillar pattern in the dermis.
Conclusion: The results of our study support the hypothesis that basement membrane alterations together with the
alterations in the distribution pattern of laminin and fibronectin may play an important role in the pathogenesis of
psoriasis.
Key Words: Psoriasis, Laminin, Fibronectin, Basement membrane, Epidermis
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