Ex vivo human models of hidradenitis suppurativa/acne inversa for laboratory research and drug screening

HS 3D-SeboSkin Model Enables the Preclinical Exploration of Therapeutic Candidates for Hidradenitis Suppurativa/Acne Inversa

Despite the rapid development in hidradenitis suppurativa (HS) research, the immediate introduction of potent therapeutic compounds in clinical trials and the lack of definitive outcome measures have led to the discontinuation of potential therapeutic compound studies. HS is a solely human disease, and therefore, the search for preclinical human models has been given priority. The 3D-SeboSkin model, a co-culture of human skin explants with human SZ95 sebocytes as a feeder layer, has been shown to prevent the rapid degeneration of human skin in culture and has been validated for HS preclinical studies. In this work, the HS 3D-SeboSkin model has been employed to characterize cellular and molecular effects of the EMA- and FDA-approved biologic adalimumab. Adalimumab, a tumor necrosis factor-α inhibitor, was shown to target inflammatory cells present in HS lesions, inducing a prominent anti-inflammatory response and contributing to tissue regeneration through a wound healing mechanism. Adalimumab inhibited the lesional tissue expression of TNF-α, IL-3, IL-15, and MCP-3 and downregulated the secretion of IL-1α, IL-5, RANTES, MCP-2, TNF-α, TNF-β, TGF-β, and IFN-γ. In contrast, IL-6 was stimulated. The compound failed to modify abnormal epithelial cell differentiation present in the HS lesions. Patients with Hurley stage II lesions exhibited stronger expression of autophagy proteins in perilesional than in lesional skin. Adalimumab modified the levels of the pro-apoptotic proteins LC3A, LC3B, and p62 in an individual, patient-dependent manner. Finally, adalimumab did not modify the NFκB signal proteins in SZ95 sebocytes and NHK-19 keratinocytes, used to study this specific pathway. The administration of the validated HS 3D-SeboSkin model in ex vivo studies prior to clinical trials could elucidate the individual pathogenetic targets of therapeutic candidates and, therefore, increase the success rates of clinical studies, minimizing HS drug development costs.

Holistic health record for Hidradenitis suppurativa patients

Hidradenitis suppurativa (HS) is a recurrent inflammatory skin disease with a complex etiopathogenesis whose treatment poses a challenge in the clinical practice. Here, we present a novel integrated pipeline produced by the European consortium BATMAN (Biomolecular Analysis for Tailored Medicine in Acne iNversa) aimed at investigating the molecular pathways involved in HS by developing new diagnosis algorithms and building cellular models to pave the way for personalized treatments. The objectives of our european Consortium are the following: (1) identify genetic variants and alterations in biological pathways associated with HS susceptibility, severity and response to treatment; (2) design in vitro two-dimensional epithelial cell and tri-dimensional skin models to unravel the HS molecular mechanisms; and (3) produce holistic health records HHR to complement medical observations by developing a smartphone application to monitor patients remotely. Dermatologists, geneticists, immunologists, molecular cell biologists, and computer science experts constitute the BATMAN consortium. Using a highly integrated approach, the BATMAN international team will identify novel biomarkers for HS diagnosis and generate new biological and technological tools to be used by the clinical community to assess HS severity, choose the most suitable therapy and follow the outcome.

Hidradenitis Suppurativa: Where We Are and Where We Are Going

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease primarily affecting apocrine gland-rich areas of the body. It is a multifactorial disease in which genetic and environmental factors play a key role. The primary defect in HS pathophysiology involves follicular occlusion of the folliculopilosebaceous unit, followed by follicular rupture and immune responses. Innate pro-inflammatory cytokines (e.g., IL-1β, and TNF-α); mediators of activated T helper (Th)1 and Th17 cells (e.g., IFN-γ, and IL-17); and effector mechanisms of neutrophilic granulocytes, macrophages, and plasma cells are involved. On the other hand, HS lesions contain anti-inflammatory mediators (e.g., IL-10) and show limited activity of Th22 cells. The inflammatory vicious circle finally results in pain, purulence, tissue destruction, and scarring. HS pathogenesis is still enigmatic, and a valid animal model for HS is currently not available. All these aspects represent a challenge for the development of therapeutic approaches, which are urgently needed for this debilitating disease. Available treatments are limited, mostly off-label, and surgical interventions are often required to achieve remission. In this paper, we provide an overview of the current knowledge surrounding HS, including the diagnosis, pathogenesis, treatments, and existing translational studies.

[Clinical, pathology-associated and molecular biomarkers of hidradenitis suppurativa/acne inversa]

Hidradenitis suppurativa/acne inversa is a scarring disease of the intertrigines that is now intensively researched. Improved pathogenetic understanding has led to the introduction of tumor necrosis factor alpha (TNF‑α) inhibition, which represents a major advance over traditional broad immunosuppression and antibiotic administration. In addition, a wide range of newer and promising treatments is or is about to be clinically evaluated. These include various specific antibodies against cytokines and the complement system and small molecules. Successful use of the individual drugs depends on the stratification of suitable patient groups with the help of clinically relevant biomarkers. While molecular investigations have shown a number of possible biomarkers and/or therapeutic target molecules, the detection of robust predictive biomarkers is still in its initial phase. In summary, the therapeutic options for hidradenitis suppurativa/acne inversa are improving through the introduction of new drugs, possibly in combination with surgical interventions, whereby the possibilities for predictive therapeutic decisions through the discovery of biomarkers would revolutionize the chances of therapeutic success.

Quality of Life in Hidradenitis Suppurativa: An Update

Knowledge on hidradenitis suppurativa/acne inversa (HS) is rapidly increasing. HS has a profound impact on patients and their family life. Several factors, such as comorbidities, unemployment and HS severity, make this impact even more severe. The most widely used instrument to measure this impact is the dermatology-specific DLQI. We also identified six HS-specific health-related quality of life (HRQoL) instruments. Of them, HIDRAdisk, HSIA, HiSQOL and HSQoL-24 are better validated but there is still lack of experience of its use. Several treatment methods showed positive effect on patients’ HRQoL. Surgery remains a method with a substantial positive effect on HRQoL. Several studies confirming a positive effect of adalimumab on the HRQoL of patients with HS were published during the last three years. Data on the influence of several other biologics on HRQoL of HS patients are controversial or based on studies with a small number of patients.

Target molecules for future hidradenitis suppurativa treatment

The registration of the tumour necrosis factor-α inhibitor adalimumab in 2015 was a major step forward in the treatment of hidradenitis suppurativa/acne inversa (HS). However, it soon became evident that the effectiveness of adalimumab in daily practice was highly variable. A significant unmet medical need of HS patients remained, and the search for novel therapeutic targets was intensified. During the 10th European Hidradenitis Suppurativa Foundation (EHSF) e.V. Conference, reknown international HS investigators virtually presented and discussed the published data on these potential target molecules for future HS treatment. This article addresses the most promising molecules currently under investigation from a pathophysiological and clinical point of view. With phase III trials ongoing, the anti- interleukin (IL)-17 biologics bimekizumab and secukinumab are in the most advanced stage of clinical development showing promising results. In addition, targeting IL-1α with bermekimab has shown encouraging results in two clinical trials. Directing treatment at neutrophil recruitment and activation by targeting IL-36 with spesolimab fits well in the pathogenic concept of HS and clinical phase II trial results are pending. In contrast to in situ evidence, Complement 5a (C5a) and C5a receptor blockade have only shown greater clinical benefit in patients with severe HS. Inhibition of Janus kinase (JAK) 1 signalling in HS showed clinical efficacy only in the highest dosage, highlighting that careful surveillance of the balance between safety and efficacy of JAK inhibition is warranted. Overall, clinical efficacies of all novel treatments reported so far are modest. To guide drug development, more and better-defined translational data on the pathogenesis of this severe and enigmatic inflammatory skin disease are required.

3D-SeboSkin Model for Human ex vivo Studies of Hidradenitis Suppurativa/Acne Inversa

BACKGROUND

Hidradenitis suppurativa/acne inversa (HS) is a chronic, recurrent inflammatory skin disease. Its pivotal pathogenetic event is believed to be the occlusion of the hair follicle generating a perifollicular lympho-histiocytic inflammation. However, knowledge of the exact HS pathogenesis requires further research.

OBJECTIVE

To develop a human HS model applicable in preclinical research which could help to understand the pathophysiology of HS and to determine the action of therapeutic candidates.

METHODS

The 3D-SeboSkin technology was applied to maintain explants of involved and uninvolved skin of HS patients ex vivo for 3 days. Detection of differential expression of previously detected HS biomarkers was performed by immunohistochemistry in a group of female patients (n = 9, mean age 37.2 ± 8.4 years).

RESULTS

The application of the 3D-SeboSkin model preserved the structural integrity of lesional and perilesional HS skin ex vivo, as previously described for healthy skin. Moreover, the HS 3D-SeboSkin setting maintained the differential expression and pattern of several HS biomarkers (S100A9, KRT16, SERPINB3) in epidermal and dermal tissue and the appendages.

CONCLUSION

We have validated HS 3D-SeboSkin as a reproducible, human model, which is appropriate for preclinical lesional and perilesional HS skin studies ex vivo.