Psoriasin: a novel chemotactic protein

Area of Science:

• Immunology
• Dermatology
• Molecular Biology

Background:

• Inflammatory skin conditions like psoriasis involve significant infiltration of neutrophils and T lymphocytes into the epidermis.
• The specific factors governing the composition of these leukocyte infiltrates remain incompletely understood.
• Psoriasin, a small calcium-binding protein (S100 family) upregulated in psoriatic keratinocytes, was previously implicated in inflammatory responses.

Purpose of the Study:

• To investigate the role of psoriasin as a potential mediator in inflammatory skin disorders.
• To determine the specific immune cell types targeted by psoriasin and its potency.
• To ascertain if psoriasin belongs to known chemokine families.

Main Methods:

• Characterization of human psoriasin's biological activity.
• Chemotaxis assays using CD4+ T lymphocytes and neutrophils.
• Structural analysis to compare psoriasin with known chemokine families (alpha, beta, lymphotactin).

Main Results:

• Human psoriasin demonstrated potent and selective chemotactic activity for CD4+ T lymphocytes and neutrophils at nanomolar concentrations.
• Psoriasin is not structurally homologous to the alpha or beta chemokine subfamilies or lymphotactin.
• These findings indicate psoriasin functions independently of known chemokine signaling pathways.

Conclusions:

• Psoriasin acts as a significant chemoattractant for key inflammatory cells, including T lymphocytes and neutrophils.
• Psoriasin represents a novel class of inflammatory mediator, distinct from established chemokines.
• This protein could be a crucial new target for therapeutic interventions in inflammatory skin diseases.