TNF Is Partially Required for Cell-Death-Triggered Skin Inflammation upon Acute Loss of cFLIP

Area of Science:

• Dermatology
• Immunology
• Molecular Biology

Background:

• Cellular FLIP (cFLIP) is crucial for maintaining epidermal integrity.
• cFLIP normally prevents tumor necrosis factor (TNF)-induced apoptosis in keratinocytes, thereby silencing skin inflammation.

Purpose of the Study:

• To investigate the role of TNF signaling in the skin pathology of cFLIP-deficient mice.
• To elucidate the mechanisms by which cFLIP regulates epidermal inflammation and keratinocyte apoptosis.

Main Methods:

• Generation and analysis of cFLIP epidermal knockout (KO) mice with concurrent TNF deficiency.
• Assessment of pathological phenotypes, including weight loss, mortality, epidermal hyperkeratosis, and keratinocyte apoptosis.
• Evaluation of cytokine and chemokine expression and immune cell infiltration.

Main Results:

• Ablation of TNF rescued cFLIP-deficient mice from severe weight loss and mortality.
• TNF deficiency significantly reduced and delayed epidermal hyperkeratosis and keratinocyte apoptosis.
• TNF signaling in cFLIP-deficient keratinocytes critically regulates skin inflammation by modulating immune cell attraction, particularly neutrophils.

Conclusions:

• cFLIP negatively regulates TNF-dependent apoptosis and partially controls epidermal inflammation.
• TNF signaling is a critical factor in the development of skin disease in cFLIP-deficient keratinocytes.
• Further research is warranted to explore cFLIP/TNF roles in inflammatory skin diseases like toxic epidermal necrolysis (TEN).