Differences in involucrin immunolabeling within cornified cell envelopes in normal and psoriatic epidermis

Area of Science:

• Dermatology
• Cell Biology
• Biochemistry

Background:

• Epidermal keratinocytes form a cornified cell envelope (CE) crucial for skin barrier function.
• CEs are stabilized by cross-linked precursor proteins, including involucrin.
• Psoriasis exhibits altered expression of CE proteins, with increased involucrin and decreased loricrin.

Purpose of the Study:

• To ultrastructurally evaluate the role of involucrin in normal and psoriatic cornified cell envelopes (CEs).
• To compare CE formation and involucrin localization in normal versus psoriatic epidermis.

Main Methods:

• Light and electron microscopic immunohistochemistry.
• Conventional transmission electron microscopy.
• Analysis of normal and psoriatic epidermal tissue.

Main Results:

• Psoriatic CE formation initiated earlier and showed persistent involucrin immunoreactivity.
• Normal CEs displayed involucrin positivity only in early assembly stages.
• Psoriatic CEs were thinner with constant high electron density compared to normal CEs.

Conclusions:

• In normal skin, involucrin is a major CE constituent only during early assembly.
• In psoriatic skin, premature CE formation leads to persistent involucrin presence throughout maturation.
• Aberrant involucrin dynamics contribute to altered CE structure in psoriasis.