State of the art of blue light effects on hidradenitis suppurativa: a concise systematic review

Abstract

Introduction: In the setting of inflammatory diseases, hidradenitis suppurativa (HS), or acne inversa, is an immune-mediated skin disease with a prevalence of 0.1-1% and characterized by nodules and abscesses in the armpits, groin, and inframammary areas, which may evolve for fistulas and scars. Still, an update is needed on the recent understanding of the pathogenesis of HS, including the central role of inflammatory cytokines and other contributing factors such as genetics, hormones, and pathogenic microorganisms. As an innovative approach, antimicrobial blue light in the 400-470 nm spectrum has demonstrated its intrinsic antimicrobial properties resulting from the presence of endogenous photosensitizing chromophores in pathogenic microorganisms. Objective: To carry out a narrative and systematic review of the literature to explore the main clinical and experimental results of the use of photobiomodulation with blue light for the treatment of hidradenitis suppurativa by antibacterial action. Methods: The present study followed a model of narrative and systematic review, according to PRISMA rules, to gather the main information about the efficiency and safety of blue light in the treatment of HS. The research was carried out from January 2018 to May 2019 and developed based on Google Scholar, Scopus, PubMed, Scielo, and Cochrane Library. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results: Microorganisms are less able to develop resistance to antimicrobial blue light than to traditional antibiotics, due to the multi-targeting characteristics of antimicrobial blue light. Furthermore, it is well accepted that antimicrobial blue light is much less harmful to host cells than UV irradiation. Clinical studies have presented scientific evidence of treatment for HS with light-based therapy, showing efficacy and safety through articles published in quality journals in scientific evidence. A meta-analysis published in 2019, based on the quality of the evidence, showed that the most recommended treatments for HS include adalimumab and laser (blue light) therapy. For intense pulsed light with blue light, two RCTs reported improvements in HS-LASI scores and the Dermatology Quality of Life Index. Conclusion: The use of blue light for dermal treatments, particularly for HS, is finding an increasing role in dermatology. However, more robust and consistent studies are still needed to better demonstrate the antibacterial effects of blue light on HS.