Apoptosis in established and healing psoriasis

Area of Science:

• Dermatology
• Cell Biology
• Molecular Biology

Background:

• Apoptosis (programmed cell death) is documented in the stratum granulosum and corneum, but its role in the germinative compartment of normal skin is unclear.
• Psoriasis exhibits increased epidermal apoptosis in differentiated layers, suggesting a role in counteracting cell overproduction.
• Limited knowledge exists regarding apoptosis within the germinative compartment in both normal and psoriatic skin.

Purpose of the Study:

• To investigate the presence and significance of apoptosis in the germinative compartment of normal and psoriatic epidermis.
• To evaluate the impact of apoptosis on cell production and tissue architecture in the context of psoriasis and its treatment.

Main Methods:

• Utilized the transferase-mediated uridine nick end labeling (TUNEL) method to detect fragmented DNA, indicative of apoptosis.
• Employed electron microscopy for detailed cellular analysis.
• Quantified apoptotic cells specifically within the germinative compartment, defined by Mib1 staining.

Main Results:

• The apoptotic index in normal epidermis was 0.12%.
• Established psoriatic lesions showed a significantly lower apoptotic index of 0.035%.
• Regressive psoriasis, post-PUVA therapy, exhibited an increased apoptotic index of 0.31%.

Conclusions:

• Apoptosis is physiologically present in the germinative compartment of normal epidermis.
• The induction of apoptosis appears crucial for the regression of psoriatic hyperplasia following PUVA treatment.
• A decrease in physiological apoptosis within psoriatic lesions may contribute to the development of psoriatic hyperplasia.