Scientists have revealed that normally harmless Porphyromonas uenonis bacteria play an active role in triggering inflammation and autoimmunity in patients with hidradenitis suppurativa. This discovery improves our understanding of this painful skin condition and paves the way for more effective treatments.
Hidradenitis suppurativa is an extremely painful chronic skin condition experienced by up to 4% of the global population, with women most commonly affected. It is characterized by recurring abscesses, inflamed nodules and deep scarring. To this day, it remains largely incurable.
Bacteria that are no longer considered harmless
Certain bacteria anomalously occurring in hidradenitis suppurativa patients' dermis were long considered just a consequence of the disease with no active role in its development. Although the disease has been known since 1864, not all of these bacteria had been identified until work was carried out in this area by Prof. Join-Lambert and doctors Delage and Nassif. We now know that this skin microbiome becomes invasive in subjects with hidradenitis suppurativa, probably as a result of immunodeficiency in these individuals (see research conducted by Prof. Hovnanian1,2 on doctors Delage and Nassif's hidradenitis suppurativa cohort).
New research published in EMBO Molecular Medicine has been conducted by a team led by Caroline Demangel, Head of the Institut Pasteur’s Immunobiology and Therapy Unit in collaboration with Olivier Join-Lambert from the University of Caen and a broad consortium of skin immunology scientists and two dermatological clinicians at the Institut Pasteur Medical Center. They have jointly demonstrated that normally rare and harmless Porphyromonas uenonis bacteria are able to penetrate patients' skin in severe forms of the disease. Once inside tissues, they trigger intense inflammation. Worse still: "Antibodies produced by the immune system to fight off these bacteria also attack the skin itself, a so-called autoimmune mechanism exacerbating lesions," comments Caroline Demangel.
Porphyromonas uenonis therefore appears to promote chronic inflammation and autoimmunity in hidradenitis suppurativa. "This discovery provides insights on this painful skin condition, and that's just the start," adds Olivier Join-Lambert, co-author of the study. "Hidradenitis suppurativa involves an imbalance of the entire skin microbiota, and Porphyromonas uenonis is just one of many species of bacteria involved in lesions, providing an initial scientific focus for further exploration."
Moves to develop innovative new combined treatments
A clinical trial is currently under way at the Institut Pasteur Medical Center led by doctors Delage and Nassif who are testing a combination of antibiotics used at the Medical Center linked to remission in patients at moderate stages of the disease. Strategies applied at the Institut Pasteur's Medical Centre since 2008 combined with surgery (due to persistent biofilms – or dormant microbes – in scarring) lead to prolonged remission and are recognized to improve patients' quality of life. Recruitment of subjects with Stage 2 hidradenitis suppurativa is ongoing (see below).
With this new study, scientists are suggesting that treatments combining targeted anti-bacterial action and inflammation control could transform the long-term management of this debilitating disease.
Research on hidradenitis suppurativa falls under the "Origins of Diseases" scientific priority of the Pasteur 2030 Strategic Plan.
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Join our clinical trial to help improve your quality of life A clinical trial is under way for patients with Stage 2 hidradenitis suppurativa. It is assessing the efficacy of a novel antibiotic treatment in several centers throughout France. Several factors are being considered to assess its efficacy: lesion regression and drying, improvement of patient quality-of-life, follow-up and treatment of any relapses. Our aim is to improve your treatment. Contact the Institut Pasteur Medical Center in Paris: abcess2@pasteur.fr Read our article on the launch of Phase I of the clinical trial in May 2025 |
Source: A skin colonizer disrupts inflammatory and humoral immune defenses in hidradenitis suppurativa, EMBO Molecular Medicine, March 24, 2026.
1 Miskinyte S, Delage M, Join-Lambert O, Nassif A, Hovnanian A. J Clin Immunol. December 2023. Inborn Errors of Immunity in Hidradenitis Suppurativa: a New Lead for HS Genetics?
2Miskinyte S, Duchatelet S, Delage M, Ungeheuer MN, Auffret N, Binois R, Guillem P, Join-Lambert O, Nassif A, Hovnanian A. J Am Acad Dermatol. February 2025. Clinical characteristics and genetic analysis of 14 patients affected with acne (A) fulminans and hidradenitis suppurativa (SH): ASH syndrome, a new phenotypic entity
