Inflammatory Skin Diseases: The Importance of Immunological Signatures.

Background: The understanding and classification of inflammatory skin diseases is shifting from a historical-descriptive perspective to a molecular-pathophysiological one based on immune response patterns. These are derived from a few key immunological mediators, each of which induces its own characteristic clinical, histopathological, and molecular patterns in the skin.

Methods: This discussion of the definition of the immune response patterns of inflammatory skin diseases is based on information from pertinent publications retrieved by a selective literature search. A systematic literature search was also conducted on the response of inflammatory skin diseases to treatment with specific biologic agents.

Results: The described immune response patterns are: autoinflammation; type 1, cytotoxic; type 2a, eczematous; type 2b, blistering; type 3, psoriasiform; type 4a, fibrosing; and type 4b, granulomatous. Each signature can usually be treated in a targeted manner. In general, each therapeutic target structure is associated with an adequate treatment response if and only if the skin disease under treatment has the relevant signature type. Hardly any biomarkers are currently available for the determination of immune response patterns in routine clinical practice.

Conclusion: The classification of inflammatory skin diseases by their immune response patterns opens up the prospect of specifically targeted immunotherapy for each immune response pattern regardless of the historical-descriptive disease entity. Targeting is intended to improve response rates. Initial findings suggest that this strategy is likely to succeed.