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Psoriasis--as an autoimmune disease caused by molecular mimicry

Helgi Valdimarsson1, Ragna H Thorleifsdottir, Sigrun L Sigurdardottir

  • 1Department of Immunology, Landspitali University Hospital, Reykjavik, Iceland. helgiv@landspitali.is

Trends in Immunology
|September 29, 2009
PubMed

Insights

Psoriasis patients often have streptococcal throat infections. This study suggests T cells recognizing both streptococcal and skin proteins may drive psoriasis, potentially improving after tonsillectomy.

Area of Science:

  • Immunology
  • Dermatology
  • Microbiology

Background:

  • Psoriasis exhibits a strong association with streptococcal throat infections.
  • Patients with psoriasis experience a higher incidence of these infections.
  • T cells in psoriatic lesions are oligoclonal, with some recognizing determinants shared by streptococcal M-protein and keratin.

Purpose of the Study:

  • To investigate the role of T cells recognizing shared determinants between Streptococcus and keratin in psoriasis pathogenesis.
  • To elucidate the differential roles of CD8(+) and CD4(+) T cells in response to streptococcal antigens in psoriasis.
  • To explore the potential impact of tonsillectomy on T cell recognition of these determinants.

Main Methods:

  • Analysis of T cell populations in psoriatic lesions and blood.
  • Detection of T cells recognizing common determinants between streptococcal M-protein and keratin.
  • Investigation of T cell responses to streptococcal peptidoglycan.

Main Results:

  • CD8(+) T cells in psoriatic epidermis likely respond to determinants mimicking keratin.
  • CD4(+) T cells in the dermis may recognize streptococcal peptidoglycan, acting as an adjuvant.
  • The streptococcal association may involve superantigens, molecular mimicry, and adjuvant effects.

Conclusions:

  • The study proposes a mechanism where T cells recognizing shared streptococcal and keratin determinants contribute to psoriasis.
  • Improvement in psoriasis post-tonsillectomy may correlate with reduced T cell recognition of these shared determinants.

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