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Etiologic aspect of sarcoidosis as an allergic endogenous infection caused by Propionibacterium acnes

Yoshinobu Eishi1

  • 1Department of Human Pathology, Tokyo Medical and Dental University Graduate School, Bunkyo-ku, Tokyo, Japan. eishi.path@tmd.ac.jp

Biomed Research International
|July 12, 2013
PubMed

Insights

Propionibacterium acnes (P. acnes) is implicated in sarcoidosis development. This bacterium can cause latent infections that reactivate, leading to systemic granulomatous inflammation.

Area of Science:

  • Immunology
  • Microbiology
  • Pulmonology

Background:

  • Sarcoidosis is a systemic granulomatous disease with an unknown cause.
  • Propionibacterium acnes (P. acnes) is the sole microorganism consistently isolated from sarcoid lesions.
  • P. acnes is a common commensal bacterium in the lungs and lymph nodes.

Purpose of the Study:

  • To investigate the role of Propionibacterium acnes in the etiology of sarcoidosis.
  • To explore the mechanism by which P. acnes may trigger granulomatous inflammation in susceptible individuals.

Main Methods:

  • Quantitative PCR and in situ hybridization to detect P. acnes in sarcoid tissues.
  • Immunological assays to assess cellular immune responses to P. acnes trigger factor protein.
  • Murine model of sarcoidosis using P. acnes sensitization and adjuvant.

Main Results:

  • P. acnes was detected in sarcoid lymph nodes and granulomas.
  • P. acnes trigger factor protein elicited a specific cellular immune response in sarcoid patients.
  • Antibiotic eradication of P. acnes prevented granuloma formation in an experimental model.
  • P. acnes can establish latent infections, persisting in a cell-wall-deficient form, which can be reactivated.

Conclusions:

  • Propionibacterium acnes plays a significant role in the pathogenesis of sarcoidosis.
  • Latent P. acnes infection, when reactivated, can trigger systemic granulomatous inflammation.
  • Understanding P. acnes' role offers potential therapeutic targets for sarcoidosis.

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