Photodynamic therapy as a new treatment modality for inflammatory and infectious conditions

Abstract

Photodynamic therapy (PDT) is currently used as a minimally invasive therapeutic modality for cancer. Whereas antitumor treatment regimens require lethal doses of photosensitizer and light, sublethal doses may have immunomodulatory effects, antibacterial action and/or regenerative properties. A growing body of evidence now indicates that non-lethal PDT doses can alleviate inflammation or treat established soft-tissue infections in various murine models of arthritis, experimental encephalomyelitis, inflammatory bowel disease and chronic skin ulcers. Furthermore, PDT is already used in clinical application and clinical trial for the treatment of psoriasis, chronic wounds and periodontitis in humans. Sublethal PDT should be regarded as a new viable option for the treatment of inflammatory conditions.

Keywords:

• antimicrobial
• immune modulation
• inflammation
• • photodynamic therapy
• wound healing

Financial & competing interests disclosure

The authors were supported by Université de Lorraine, Centre de recherche en automatique de Nancy, 54506 Vandoeuvre-lès-Nancy, France; Centre national de la recherche scientifique, UMR 7039, 54506 Vandœuvre-lès-Nancy, France; Division of Gastroenterology, University of California San Diego, La Jolla, California; Institut National de la Santé et de la Recherche Médicale, U954, 54500 Vandoeuvre-lès-Nancy, France; and Institut Pasteur de Lille, Centre d’Infection et d’Immunité de Lille, 59019 Lille, France. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. Writing assistance was utilized in the production of this manuscript, and was performed by D Fraser, Biotech Communicatio, (Damery, France) and funded by the inserm Unit of Mathias Chamaillard.

Key issues

• Sublethal photodynamic therapy (PDT) can directly alter immune cell function and thus alleviate immune-mediated disease:

  • – Activated T- and B-lymphocytes may be more vulnerable to the cytotoxic effects of PDT – even with sublethal PDT regimens.

  • – Sublethal PDT may alter cell–cell interactions by modifying the immune cells’ surface receptor expression.

  • – Sublethal PDT modified cytokine expression levels.

• Sublethal PDT appears to hasten the process of wound healing.

• Sublethal PDT mediated enhancement of antibacterial immunity.

• PDT appears to be a promising therapeutic modality in infectious and chronic inflammatory diseases such as inflammatory bowel disease and arthritis.

Notes