Deciphering the microbiology of hidradenitis suppurativa: a step forward towards understanding an enigmatic inflammatory skin disease

Inborn Errors of Immunity in Hidradenitis Suppurativa Pathogenesis and Disease Burden

Hidradenitis suppurativa (HS), also known as Verneuil's disease and acne inversa, is a prevalent, debilitating, and understudied inflammatory skin disease. It is marked by repeated bouts of pathological inflammation causing pain, hyperplasia, aberrant healing, and fibrosis. HS is difficult to manage and has many unmet medical needs. There is clinical and pharmacological evidence for extensive etiological heterogeneity with HS, suggesting that this clinical diagnosis is capturing a spectrum of disease entities. Human genetic studies provide robust insight into disease pathogenesis. They also can be used to resolve etiological heterogeneity and to identify drug targets. However, HS has not been extensively investigated with well-powered genetic studies. Here, we review what is known about its genetic architecture. We identify overlap in molecular, cellular, and clinical features between HS and inborn errors of immunity (IEI). This evidence indicates that HS may be an underrecognized component of IEI and suggests that undiagnosed IEI are present in HS cohorts. Inborn errors of immunity represent a salient opportunity for rapidly resolving the immunological landscape of HS pathogenesis, for prioritizing drug repurposing studies, and for improving the clinical management of HS.

Consistency of Bacterial Triggers in the Pathogenesis of Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is an inflammatory skin disease whose pathogenesis remains poorly defined. Over the past decades, the bacterial role in HS patients has been a focus of research. According to the literature, the HS skin (and probably gut) bacterial composition is different to that of healthy controls. To date, a key question is whether compositional changes in the microbial populations are responsible for the development of HS (primum movens), or only secondarily reflect the ongoing inflammatory process. The great diversity of methodologies that have been used to study microbial role in HS have led to an accumulation of conflicting results. Thus, in view of these considerations, the aim of this article is to provide the reader with an overview about different hypotheses proposed to explain the bacterial role in HS pathogenesis.

Management of Severe Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a devastating and disfiguring disease of the skin involving the terminal follicular epithelium within the apocrine-gland-bearing skin. We present an interesting case of a 58-year-old female who presented with a 10-year history of refractory HS of the gluteal, perineal, perianal, and groin region. She had been chronically treated with multiple antibiotics in the past with no improvement. The patient subsequently underwent surgical local excision with complex closure. Medical management alone may not be optimal, especially in refractory disease. Early and aggressive surgical intervention and interdisciplinary approach are needed for patients with chronic and advanced stage of HS.

Adalimumab medium-term dosing strategy in moderate-to-severe hidradenitis suppurativa: integrated results from the phase III randomized placebo-controlled PIONEER trials

Background

Weekly adalimumab (Humira^®) is approved for the treatment of hidradenitis suppurativa (HS) based on the 12‐week placebo‐controlled periods of the two phase III PIONEER trials.

Objectives

Using PIONEER integrated trial results, we aimed to evaluate the optimal medium‐term adalimumab maintenance dosing strategy for moderate‐to‐severe HS.

Methods

Each trial had two double‐blind periods; 12‐week Period A and 24‐week Period B. Patients randomized to adalimumab 40 mg every week (ADAew) (Period A), were rerandomized in Period B to ADAew (ADAew/ew), ADA every other week (ADAew/eow), or placebo (ADAew/pbo). Placebo‐randomized patients were reassigned in Period B to ADAew (PIONEER I) or placebo (PIONEER II). The primary outcome was HS Clinical Response (HiSCR). Patients who lost response during Period B were discontinued from the study and offered an option to enter the open‐label extension (OLE) to receive ADAew. Results are reported across the two study periods, and data were combined from the two study periods and the OLE.

Results

For week‐12 HiSCR achievers, the HiSCR week‐36 rate was 48·1% (ADAew/ew) vs. 46·2% (ADAew/eow) and 32·1% (ADAew/pbo). Combining (post hoc) these patients with week‐12 partial responders further differentiated outcomes in Period B (ADAew/ew 55·7% vs. ADAew/eow 40·0% and ADAew/pbo 30·1%). Period‐B adverse‐event rates were ADAew/ew 59·6% vs. ADAew/eow 57·4% and ADAew/pbo 65·0%. One patient (ADAew/ew) reported a serious infection.

Conclusions

Weekly adalimumab treatment, effective throughout 36 weeks, was the optimal maintenance medium‐term dosing regimen for this population. At least partial response after 12 weeks with continued weekly dosing had better outcomes than dose reduction or interruption. Patients who do not show at least a partial response to weekly adalimumab by week 12 are unlikely to benefit from continued therapy. No new safety risks were identified.

What's already known about this topic?

Hidradenitis suppurativa (HS) is a chronic inflammatory disease, commonly misinterpreted as an infection and treated with long‐term antibiotic regimens or surgical incisions.

Based on the chronicity of HS and the lack of evidence for efficacious and safe long‐term HS treatments, it is important to evaluate medium‐ to long‐term therapies for HS.

Weekly adalimumab (Humira^®) is approved for the treatment of moderate‐to‐severe HS based on the two phase III PIONEER trials.

What does this study add?

This study pooled data from the two PIONEER trials, providing a more robust assessment of outcomes.

After at least partial treatment success with weekly adalimumab short‐term therapy (12 weeks), continuing weekly dosing during the subsequent 24 weeks had better outcomes than dose reduction or treatment interruption.

Patients who do not show at least a partial response to weekly adalimumab by week 12 are unlikely to benefit from continued therapy.

Linked Comment: https://doi.org/10.1111/bjd.18437.

https://www.bjdonline.com/article/adalimumab-medium-term-dosing-strategy-in-moderate-to-severe-hidradenitis-suppurativa-integrated-results-from-the-phase-iii-randomized-placebo-controlled-pioneer-t/

Proceeding report of the third symposium on Hidradenitis Suppurativa advances (SHSA) 2018

The 3rd Annual Symposium on Hidradenitis Suppurativa Advances (SHSA) took place on 12-14 October 2018 at the Women's College Hospital in Toronto, Ontario, Canada. This symposium was a joint meeting of the Hidradenitis Suppurativa Foundation (HSF) founded in the USA and the Canadian Hidradenitis Suppurativa Foundation (CHSF). This cross-disciplinary meeting with experts from around the world was an opportunity to discuss the most recent advances in the study of hidradenitis suppurativa pathogenesis, epidemiology, classification, scoring systems, radiologic diagnosis, treatment approaches and psychologic assessment. Two special sessions this year were HS as a systemic disease and HS management guidelines. There were focused workshops on wound healing and ultrasound. There were two sessions primarily for patients and their families in the HS School programme: One workshop focused on mindfulness, and the second involved discussion among clinicians and patients about various disease aspects and the latest management. To facilitate networking between clinical and research experts and those early in their career, a mentoring breakfast was held.

Are Bacteria Infectious Pathogens in Hidradenitis Suppurativa? Debate at the Symposium for Hidradenitis Suppurativa Advances Meeting, November 2017

In November 2017, a formal debate on the role of bacteria in the pathogenesis of hidradenitis suppurativa (HS) was held at the 2nd Symposium on Hidradenitis Suppurativa Advances (SHSA) in Detroit, Michigan. In this report, we present both sides of the argument as debated at the SHSA meeting and then discuss the potential role of bacteria as classic infectious pathogens versus an alternative pathogenic role as activators of dysregulated commensal bacterial-host interactions. Although there was consensus that bacteria play a role in pathogenesis and thus are pathogenic, there was a compelling discussion about whether bacteria in HS incite an infectious disease as we classically understand it or whether bacteria might play a different role in HS pathogenesis.