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Background/aims: Aquaporin-3 (AQP3) is an aquaglyceroporin and peroxiporin that plays a crucial role in skin barrier homeostasis. Dysregulated AQP3 expression has been observed in different inflammatory skin conditions. Hidradenitis Suppurativa (HS) is an autoinflammatory keratinization disease that typically appears between 10 and 21 years of age, characterized by alteration of skin barrier homeostasis., Methods: To evaluate in vitro the role of AQP3 in the development of HS, we performed real-time PCR and Western blot to analyze gene and protein levels in human keratinocyte cell lines knock-out (KO) for NCSTN and PSENEN genes, simulating genetic-associated HS. Additionally, we investigated the impact of Glyceryl Glucoside (GG) on biological processes by performing MTT, scratch, proliferation assays and proteome studies., Results: We detected a significant decrease of the levels of AQP3 gene and protein in KO cell lines. GG effectively elevated the levels of mRNA and protein, significantly decreased the hyperproliferation rate, and enhanced cell migration in our in vitro model of genetic Hidradenitis Suppurativa. Pathway enrichment analysis further confirmed GG's role in the migration and proliferation pathways of keratinocytes., Conclusion: Our results suggest that AQP3 may act as a new novel actor in HS etio-pathogenesis, and GG could be further explored as potential treatment option for managing HS in patients., Competing Interests: The authors have no conflicts of interest to declare., (© Copyright by the Author(s). Published by Cell Physiol Biochem Press.)

Competing Interests: Competing interests statement:The authors declare no competing interest.

Background: Hidradenitis suppurativa (HS) is a chronic inflammatory and scarring disease with a wide spectrum of disease severity. The amount of scarring is proportional to the preceding tissue damage and poses a challenge to patients. Severe HS is most often treatment recalcitrant, but hypothetically avoidable through early biologic treatment. Early prediction of individual risk of disease progression is therefore essential for patient management., Objectives: To investigate risk factors associated with disease progression and to design an algorithm capable of predicting disease -progression., Methods: A prospective cohort study of 335 Hurley III-naïve patients with HS, not treated with biologics, was followed for a median of 2 years. Potential risk factors covered basic demographics, HS anamnestic factors and clinical HS factors collected during physical examination. Two separate Cox proportional hazard regression (CPHR) analyses were conducted. A summated 'progression score' was calculated and used in the predictive algorithm of severe disease. Subsequent bootstrap sampling was used to validate the predictability of the predictive algorithm., Results: The CPHR analysis of Transition to severe disease found that active smoking [hazard ratio (HR) 4.01, 95% confidence interval (CI) 1.71-9.40, P = 0.001]; body mass index (BMI) points > 25 at baseline (each point: HR 1.06, 95% CI 1.02-1.09, P < 0.001); active disease in 2 (HR 4.26, 95% CI 1.23-14.84, P = 0.02) and ≥ 3 areas (HR 6.54, 95% CI 1.89-22.72, P = 0.003) all constituted substantial risk factors. Conversely, the CPHR analysis of Disease progression did not yield results of clinical relevance. A 'progression score' of 3.04 was used as a threshold in the predictive algorithm of Transition to severe disease and achieved the following test specifics: sensitivity = 0.51, specificity = 0.86, positive predictive value = 0.50, negative predictive value = 0.86., Conclusions: We found a disparity between factors increasing the risk of simple Disease progression and those increasing the risk of Transition to severe disease. For the latter, active smoking, BMI points > 25, active disease in 2 or ≥ 3 areas were all shown to be the clinically relevant factors that could be used to construct an algorithm that correctly predicted progression to severe HS in more than half of all instances., Competing Interests: Conflicts of interest R.K.A. reports that his attendance at the 2022 Nordic Congress of DermatoVenerology was funded by Eli Lilly. O.B.P. reports no conflicts of interest. L.E. has received speaker honoraria from Janssen, Leo Pharma, Lilly and Novartis, and has been a consultant for advisory boards and received research grants from Novartis. G.B.E.J. has received honoraria from AbbVie, Chemocentryx, Coloplast, Incyte, Inflarx, Novartis, Pierre Fabre and UCB for participation on advisory boards; grants from AbbVie, Astra-Zeneca, Inflarx, Janssen-Cilag, Leo Pharma, Novartis, Regeneron and Sanofi for participation as an investigator; and speaker honoraria from AbbVie, Boehringer-Ingelheim, Galderma and MSD. He has also received unrestricted departmental grants from AbbVie, Leo Pharma and Novartis. D.M.L.S. has, over the past 3 years, received honoraria as a consultant for advisory board meetings from AbbVie, Janssen, Leo Pharma, Novartis and Sanofi; and honoraria as a speaker and/or received grants from the following: AbbVie, Jamjoom Pharma, Janssen, Leo Pharma, Novartis, Pfizer, Sanofi and UCB., (© The Author(s) 2024. Published by Oxford University Press on behalf of British Association of Dermatologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Hidradenitis suppurativa is a disease in great need of novel therapies. Given the heterogeneous nature of the disease and the variable response to therapies, biomarkers are essential to predict response to therapies and increase our understanding of disease pathogenesis. Our recent phase 2 clinical trial of spleen tyrosine kinase antagonism using fostamatinib in hidradenitis suppurativa demonstrated a 75% clinical response, with the greatest benefit in individuals with elevated serum inflammation and IgG. In this study, we present results of an in-depth serum proteomic analysis in this patient cohort identifying downregulation of IL-12B as well as B-cell-associated proteins CCL19 and CCL20 and IFN-γ-mediated proteins CXCL10 and CX3CL1. Clinical responders demonstrated greater reduction in serum IL-17A, IL-6, IL-8, and CX3CL1 compared with clinical nonresponders. Baseline levels of CCL28 were associated with clinical response to fostamatinib therapy at week 12. Overall, this suggests that fostamatinib, by targeting B-cell receptor and Fc receptor activity in B cells, monocytes, and macrophages, has a significant molecular impact on the inflammatory serum proteome of hidradenitis suppurativa. In addition, potential therapeutic biomarkers may aid in patient selection for targeted therapy., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Hidradenitis suppurativa is a chronic, inflammatory condition of the pilosebaceous unit in which patients manifest multiple, painful cutaneous nodules, abscesses and tunnels. These lesions are described to affect the intertriginous zones, however, the condition exhibits significant phenotypic variability. Such variability is influenced by the patients lifestyle, genetic predisposition and sex. In this cross-sectional study, we investigate sex differences in patterns of hidradenitis suppurativa skin involvement, specifically at site of first involvement and most bothersome cutaneous site of involvement., (Copyright © 2024 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.)

Hidradenitis suppurativa (HS) is a chronic skin condition affecting approximately 1% of the US population. HS skin lesions are highly inflammatory and characterized by a large immune infiltrate. While B cells and plasma cells comprise a major component of this immune milieu, the biology and the contribution of these cells in HS pathogenesis are unclear. We aimed to investigate the dynamics and microenvironmental interactions of B cells within cutaneous HS lesions. Combining histological analysis, single-cell RNA sequencing, and spatial transcriptomics profiling of HS lesions, we defined the tissue microenvironment relative to B cell activity within this disease. Our findings identified tertiary lymphoid structures (TLSs) within HS lesions and described organized interactions among T cells, B cells, antigen-presenting cells, and skin stroma. We found evidence that B cells within HS TLSs actively underwent maturation, including participation in germinal center reactions and class switch recombination. Moreover, skin stroma and accumulating T cells were primed to support the formation of TLSs and facilitate B cell recruitment during HS. Our data definitively demonstrated the presence of TLSs in lesional HS skin and point to ongoing cutaneous B cell maturation through class switch recombination and affinity maturation during disease progression in this inflamed nonlymphoid tissue.

Hidradenitis suppurativa (HS) is a chronic autoinflammatory follicular disease, affecting body areas that are rich in apocrine glands. Moderate-to-severe HS may severely impair patients' quality of life also because the available therapies are often unsatisfactory. Several lines of evidence suggest that inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin (IL)-17 play a pivotal role in the physiopathology of HS. TNF-α inhibitors have long been used with benefit in moderate-severe forms of HS. However, several monoclonal antibodies against IL-17 isoforms are currently being investigated for HS. We report the case of a 50-year-old man with long-standing HS and concomitant palmo-plantar psoriasis treated with brodalumab after failure of various TNF-α inhibitors. The HS lesions and the patient's quality of life improved steadily over time until week-136. Interestingly, the clinical benefit was confirmed by radiological improvement with MRI evaluation. Our case report demonstrates the long-term efficacy and safety of brodalumab in HS encouraging the use of drugs to inhibit the T helper-type 17 immune axis, especially in cases of HS refractory to therapy with TNF-α inhibitors.

Skin disorders affect ∼40% of the human population. One of the most debilitating cutaneous disorders is Hidradenitis suppurativa (HS), a noncommunicable chronic inflammatory disease with an estimated global prevalence of 0.4% to 2.5%. In January 2011, high levels of IL-17 were discovered in skin lesions of HS patients. In the following years, translational and clinical research led to a better understanding of the pathogenesis of HS. In June 2023, more than 12 years after the initial note, secukinumab, an anti-IL-17A monoclonal antibody, was approved for the treatment of moderate to severe HS. This is the next milestone in improving the treatment of these patients after the approval of the anti-TNF-α monoclonal antibody adalimumab in 2015. In this review article, we present the IL-17 pathway in HS and discuss the use of secukinumab as a therapeutic option for this disease. Our review starts with a description of the epidemiology, clinical features, etiology, and pathogenesis of HS. An overview of the IL-17/IL-17 receptor system in general and a detailed description of the known facts about the expression and action of IL-17 in HS follow. Afterward, we consider the results of clinical trials evaluating the safety and efficacy of IL-17 inhibitors in HS. Finally, a comparison is made between secukinumab and adalimumab and the characteristics of the patients that may be particularly suitable for each of these biologics are described.

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease affecting patients of reproductive age. Although HS shares risk factors with male infertility, only 1 epidemiological study has evaluated this association. To further evaluate this potential association, findings on semen and hormonal analysis, testicular ultrasound, and the International Index of Erectile Function (IIEF-15) were compared between 28 men attending a tertiary HS clinic during the period April 2019 to April 2021, and 44 healthy controls, spouses of infertile women undergoing semen evaluation before in vitro fertilization. Patients with HS were divided based on the absence or presence of gluteal and genital lesions. Patients with HS were younger than controls (median 27 vs 34 years, p < 0.0004) and had a higher proportion of smokers (86% vs 33%, p < 0.0001). Semen parameters in patients with gluteal-genital lesions, specifically those with severe scrotal involvement necessitating surgery, were lower than the WHO reference values and significantly lower than in patients without gluteal-genital lesions and controls. Erectile dysfunction was reported by 93% of patients with HS. These findings suggest that spermatogenesis and sexual function may be impaired in young men with HS. Therefore, multidisciplinary management of HS should include their evaluation to identify patients who might benefit from semen cryopreservation and sexual treatment.

Background: Hidradenitis suppurativa (HS) is a chronic skin condition causing lesions in which high levels of interleukin (IL)-23 and T-helper17 cells are found. Adalimumab remains the only approved treatment. Guselkumab, an antibody targeting the p19 protein subunit of extracellular IL-23, is approved for the treatment of moderate-severe psoriasis, but evidence on its efficacy in treating HS is limited., Objectives: To assess the effectiveness and safety of guselkumab in treating moderate-severe HS under clinical practice conditions., Methods: A multicentre retrospective observational study was carried out in 13 Spanish hospitals including adult HS patients treated with guselkumab within a compassionate use programme (March 2020-March 2022). Data referred to patient demographic and clinical characteristics at treatment initiation (baseline), patient-reported outcomes (Numerical Pain Rating Scale [NPRS] and Dermatology Life Quality Index [DLQI]), physician scores (International Hidradenitis Suppurativa Severity Score System [IHS4], HS Physical Global Score [HS-PGA] and Hidradenitis Suppurativa Clinical Response [HiSCR]) were recorded at baseline and at 16, 24, and 48weeks of treatment., Results: A total of 69 patients were included. Most (84.10%) had severe HS (HurleyIII) and had been diagnosed for over ten years (58.80%). The patients had been subjected to multiple non-biological (mean: 3.56) or biological (mean: 1.78) therapies, and almost 90% of those treated with biologics had received adalimumab. A significant decrease in IHS4, HS-PGA, NPRS, and DLQI scores was observed from baseline to 48weeks of guselkumab treatment (all P<.01). HiSCR was achieved in 58.33% and 56.52% of the patients at 16 and 24weeks, respectively. Overall, 16 patients discontinued treatment, mostly due to inefficacy (n=7) or loss of efficacy (n=3). No serious adverse events were observed., Conclusions: Our results indicate that guselkumab may be a safe and effective therapeutic alternative for patients with severe HS that fail to respond to other biologics., (Copyright © 2023 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.)

Background: Hidradenitis suppurativa (HS) is a chronic skin condition causing lesions in which high levels of interleukin (IL)-23 and T-helper 17 cells are found. Adalimumab remains the only approved treatment. Guselkumab, an antibody targeting the p19 protein subunit of extracellular IL-23, is approved for the treatment of moderate-severe psoriasis, but evidence on its efficacy in treating HS is limited., Objectives: To assess the effectiveness and safety of guselkumab in treating moderate-severe HS under clinical practice conditions., Methods: A multicentre retrospective observational study was carried out in 13 Spanish Hospitals including adult HS patients treated with guselkumab within a compassionate use programme (March 2020-March 2022). Data referred to patient demographic and clinical characteristics at treatment initiation (baseline), patient-reported outcomes (Numerical Pain Rating Scale [NPRS] and Dermatology Life Quality Index [DLQI]), physician scores (International Hidradenitis Suppurativa Severity Score System [IHS4], HS Physical Global Score [HS-PGA] and Hidradenitis Suppurativa Clinical Response [HiSCR]) were recorded at baseline and at 16, 24, and 48 weeks of treatment., Results: A total of 69 patients were included. Most (84.10%) had severe HS (Hurley III) and had been diagnosed for over ten years (58.80%). The patients had been subjected to multiple non-biological (mean 3.56) or biological (mean 1.78) therapies, and almost 90% of those treated with biologics had received adalimumab. A significant decrease in IHS4, HS-PGA, NPRS, and DLQI scores was observed from baseline to 48 weeks of guselkumab treatment (all p<0.01). HiSCR was achieved in 58.33% and 56.52% of the patients at 16 and 24 weeks, respectively. Overall, 16 patients discontinued treatment, mostly due to inefficacy (n=7) or loss of efficacy (n=3). No serious adverse events were observed., Conclusions: Our results indicate that guselkumab may be a safe and effective therapeutic alternative for patients with severe HS that fail to respond to other biologics., (Copyright © 2023 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.)

Importance: Hidradenitis suppurativa (HS) is a common and severely morbid chronic inflammatory skin disease that is reported to be highly heritable. However, the genetic understanding of HS is insufficient, and limited genome-wide association studies (GWASs) have been performed for HS, which have not identified significant risk loci., Objective: To identify genetic variants associated with HS and to shed light on the underlying genes and genetic mechanisms., Design, Setting, and Participants: This genetic association study recruited 753 patients with HS in the HS Program for Research and Care Excellence (HS ProCARE) at the University of North Carolina Department of Dermatology from August 2018 to July 2021. A GWAS was performed for 720 patients (after quality control) with controls from the Add Health study and then meta-analyzed with 2 large biobanks, UK Biobank (247 cases) and FinnGen (673 cases). Variants at 3 loci were tested for replication in the BioVU biobank (290 cases). Data analysis was performed from September 2021 to December 2022., Main Outcomes and Measures: Main outcome measures are loci identified, with association of P < 1 × 10-8 considered significant., Results: A total of 753 patients were recruited, with 720 included in the analysis. Mean (SD) age at symptom onset was 20.3 (10.57) years and at enrollment was 35.3 (13.52) years; 360 (50.0%) patients were Black, and 575 (79.7%) were female. In a meta-analysis of the 4 studies, 2 HS-associated loci were identified and replicated, with lead variants rs10512572 (P = 2.3 × 10-11) and rs17090189 (P = 2.1 × 10-8) near the SOX9 and KLF5 genes, respectively. Variants at these loci are located in enhancer regulatory elements detected in skin tissue., Conclusions and Relevance: In this genetic association study, common variants associated with HS located near the SOX9 and KLF5 genes were associated with risk of HS. These or other nearby genes may be associated with genetic risk of disease and the development of clinical features, such as cysts, comedones, and inflammatory tunnels, that are unique to HS. New insights into disease pathogenesis related to these genes may help predict disease progression and novel treatment approaches in the future.

Background: Hidradenitis suppurativa (HS) is an inflammatory disease of the inverse skin regions that occurs in young women, in particular, and affects approximately 1% of the population. Outpatient care is often inadequate and usually cannot prevent progression., Objectives: To evaluate in the EsmAiL ('Evaluation eines strukturierten und leitlinienbasierten multmodalen Versorgungskonzepts für Menschen mit Akne inversa') trial whether an innovative care concept can decrease disease activity and burden, and improve patient satisfaction., Methods: EsmAiL was conducted as a two-arm, multicentre, prospective, randomized controlled trial that included 553 adults with HS. Inclusion criteria were a minimum of three inflammatory lesions and at least a moderate impact of the disease on quality of life. The control group (CG) remained under standard care, while patients in the intervention group (IG) were treated according to a trial-specific, multimodal concept. The primary endpoint was the absolute change in International Hidradenitis Suppurativa Severity Score System (IHS4)., Results: In total, 274 patients were randomized to the IG and 279 to the CG. Altogether, 377 attended the final assessment after 12 months of intervention. Participants in the IG (n = 203) achieved a mean improvement in IHS4 of 9.3 points, while the average decrease in IHS4 in patients in the CG (n = 174) was 5.7 points (P = 0.003). Patients treated under the new care concept also reported a statistically significantly higher decrease in pain, Dermatology Life Quality Index and Hospital Anxiety and Depression Scale scores compared with those in the CG (P < 0.001). Patient satisfaction was also statistically significantly higher in the IG compared with the CG (P < 0.001)., Conclusions: The establishment of standardized treatment algorithms in so-called 'acne inversa centres' in the ambulatory setting has a substantial, positive impact on the course of HS and significantly improves patient satisfaction., Competing Interests: Conflicts of interest M.S. reports auditor activity on the implementation of the contract ‘AOK-Priomed Acne inversa’ for LENICURA; the receipt of honoraria for lectures from AbbVie; and the funding of travel, congress and hotel fees from AbbVie and Pfizer. P.S. has received grants or contracts from Novartis and Almirall; consulting fees from AbbVie, Allergika, Almirall-Hermal, Amgen, Beiersdorf, Biocryst, BMS, Boehringer Ingelheim, Celgene, CSL Behring, Eli Lilly, Falk, Galderma, Hexal, Janssen, Klinge, Klosterfrau, LEO Pharma, LETI Pharma, L’Oréal, Novartis, Octapharma, Pfizer, Pflüger, Pharming, Regeneron, Shire, Takeda, Sanofi–Genzyme and UCB Pharma; and has had a leadership or fiduciary role for the Society of dermopharmazie, unrelated to work presented here. G.N. reports consulting fees from Dessau Medical Center, which received a consulting fee from Mölnlycke Health Care GmbH, for which he served as a consulting physician; has received speaker fees for attending the European Academy of Dermatology and Venerology (EADV) hidradenitis suppurativa course held on 28–30 November 2022 in Porto, Portugal; and has received an Eli Lilly scholarship for attending the EADV Congress 2021. F.B. has received consulting fees from AbbVie, Incyte, AbbVie Deutschland, MoonLake, Novartis Pharma, Janssen Cilag and UCB Pharma; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events for AbbVie, Incyte, AbbVie Deutschland, Novartis Pharma, Janssen Cilag and UCB Pharma; support for attending meetings and/or travel from AbbVie, Incyte, AbbVie Deutschland, Novartis Pharma, Janssen Cilag and UCB Pharma; and has participated on a data protection monitoring board or advisory board for AbbVie, Incyte, AbbVie Deutschland, Novartis Pharma, Janssen Cilag, UCB Pharma and Boehringer Ingelheim Pharma. U.K. has received consulting fees from Novartis; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Novartis; has participated on a data protection monitoring board or advisory board for Novartis, EsmAiL and EpiCAi; and has had a leadership or fiduciary role for Deutsche Gesellschaft für Wundheilung und Wundbehandlung. K.H. has patents planned, issued or pending (DE102015000150B4); and has stocks or stock options in LENICURA (CEO and stockholder of the company). M.G. has received grants or contracts for clinical studies on hidradenitis suppurativa as deputy Principal Investigator (PI) sponsored by Novartis, Janssen and UCB, and for clinical studies on pemphigus vulgaris and bullous pemphigoid as PI sponsored by Argenx, and for a clinical study on prurigo nodularis as PI sponsored by Galderma (institutional contract; no personal payment); consulting fees from Almirall (personal payment) and Argenx (payment to institution); payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from GSK, Eli Lilly and Janssen (personal payment); support for attending meetings and/or travel from UCB (travel support); has participated in data protection monitoring or advisory boards for UCB, GSK and LEO (personal payment); and is a member of the Board of Directors and Treasurer of the German Society of Dermatology (‘Deutsche Dermatologische Gesellschaft’), Section Editor of the Journal der Dt. Dermatologischen Gesellschaft and a member of the Board of Directors of the University Hospital Würzburg (all unpaid). S.G. reports grants or contracts from Novartis and Pierre Fabre; consulting fees from AbbVie, BMS, MSD, Genzyme, Klinge Pharma, Sun Pharma, Kyowa-Kirin, Novartis and Pierre Fabre; has participated on a data safety monitoring or advisory board for Alcedis; and is a member of DeCOG (German dermatological cooperative oncology group), unrelated to the work presented herein., (© The Author(s) 2023. Published by Oxford University Press on behalf of British Association of Dermatologists.)

The etiopathogenesis of autoimmune skin diseases is complex and still not fully understood. The role of epigenetic factors is emphasized in the development of such diseases. MicroRNAs (miRNAs), a group of non-coding RNAs (ncRNAs-non-coding RNAs), are one of the important post-transcriptional epigenetic factors. miRNAs have a significant role in the regulation of the immune response by participating in the process of the differentiation and activation of B and T lymphocytes, macrophages, and dendritic cells. Recent advances in research on epigenetic factors have provided new insights into the pathogenesis and potential diagnostic and therapeutic targets of many pathologies. Numerous studies revealed a change in the expression of some microRNAs in inflammatory skin disorders, and the regulation of miRNA expression is a promising therapeutic goal. This review presents the state of the art regarding changes in the expression and role of miRNAs in inflammatory and autoimmune skin diseases, including psoriasis, atopic dermatitis, vitiligo, lichen planus, hidradenitis suppurativa, and autoimmune blistering diseases.

Hidradenitis suppurativa (HS) is an inflammatory skin disease characterized by painful lesions on intertriginous body areas such as the axillary, inguinal, and perianal sites. Given the limited treatment options for HS, expanding our knowledge of its pathogenetic mechanisms is a prerequisite for novel therapeutic developments. T cells are assumed to play a crucial role in HS pathogenesis. However, it is currently unknown whether blood T cells show specific molecular alterations in HS. To address this, we studied the molecular profile of CD4 + memory T (Th mem ) cells purified from the blood of patients with HS and matched healthy participants. About 2.0% and 1.9% of protein-coding transcripts were found to be up- and down-regulated in blood HS Th mem cells, respectively. These differentially expressed transcripts (DETs) are known to be involved in nucleoside triphosphate/nucleotide metabolic processes, mitochondrion organization, and oxidative phosphorylation. The detected down-regulation of transcripts involved in oxidative phosphorylation suggest a metabolic shift of HS Th mem cells towards glycolysis. The inclusion of transcriptome data from skin from HS patients and healthy participants in the analyses revealed that in HS skin lesions, the expression pattern of transcripts identified as DETs in blood HS Th mem cells was very similar to the expression pattern of the totality of protein-coding transcripts. Furthermore, there was no significant association between the extent of the expressional changes in the DETs of blood HS Th mem cells and the extent of the expressional changes in these transcripts in HS skin lesions compared to healthy donor skin. Additionally, a gene ontology enrichment analysis did not demonstrate any association of the DETs of blood HS Th mem cells with skin disorders. Instead, there were associations with different neurological diseases, non-alcoholic fatty liver disease, and thermogenesis. The levels of most DETs linked to neurological diseases showed a positive correlation to each other, suggesting common regulatory mechanisms. In summary, the transcriptomic changes in blood Th mem cells observed in patients with manifest cutaneous HS lesions do not appear to be characteristic of the molecular changes in the skin. Instead, they could be useful for studying comorbidities and identifying corresponding blood biomarkers in these patients.

Janus kinase (JAK)/signal transducer and activator of transcription signaling (STAT) has been implicated in the pathophysiology of hidradenitis suppurativa (HS). This study evaluated treatment-related transcriptomic and proteomic changes in patients with moderate-to-severe HS treated with the investigational oral JAK1-selective inhibitor povorcitinib (INCB054707) in two phase 2 trials. Lesional skin punch biopsies (baseline and Week 8) were taken from active HS lesions of patients receiving povorcitinib (15 or 30 mg) once daily (QD) or a placebo. RNA-seq and gene set enrichment analyses were used to evaluate the effects of povorcitinib on differential gene expression among previously reported gene signatures from HS and wounded skin. The number of differentially expressed genes was the greatest in the 30 mg povorcitinib QD dose group, consistent with the published efficacy results. Notably, the genes impacted reflected JAK/STAT signaling transcripts downstream of TNF-α signaling, or those regulated by TGF-β. Proteomic analyses were conducted on blood samples obtained at baseline and Weeks 4 and 8 from patients receiving povorcitinib (15, 30, 60, or 90 mg) QD or placebo. Povorcitinib was associated with transcriptomic downregulation of multiple HS and inflammatory signaling markers as well as the reversal of gene expression previously associated with HS lesional and wounded skin. Povorcitinib also demonstrated dose-dependent modulation of several proteins implicated in HS pathophysiology, with changes observed by Week 4. The reversal of HS lesional gene signatures and rapid, dose-dependent protein regulation highlight the potential of JAK1 inhibition to modulate underlying disease pathology in HS.

Hidradenitis suppurativa (HS) is a common, debilitating inflammatory skin disease linked to immune dysregulation and abnormalities in follicular structure and function. Several studies have characterized the transcriptomic profile of affected and unaffected skin in small populations. In this study of 20 patients, RNA from lesional and matching non-lesional skin biopsies in 20 subjects were used to identify an expression-based HS disease signature. This was followed by differential expression and pathway enrichment analyses, as well as jointly reanalyzing our findings with previously published transcriptomic profiles. We establish an RNA-Seq based HS expression disease signature that is mostly consistent with previous reports. Bulk-RNA profiles from 104 subjects in 7 previously reported data sets identified a disease signature of 118 differentially regulated genes compared to three control data sets from non-lesional skin. We confirmed previously reported expression profiles and further characterized dysregulation in complement activation and host response to bacteria in disease pathogenesis. Changes in the transcriptome of lesional skin in this cohort of HS patients is consistent with smaller previously reported populations. The findings further support the significance of immune dysregulation, in particular with regard to bacterial response mechanisms. Joint analysis of this and previously reported cohorts indicate a remarkably consistent expression profile., Competing Interests: Christopher Sayed discloses that he is speaker for Abbvie and Novartis; on advisory boards for Abbvie, UCB and InflaRx; a co-investigator for Abbvie and Novartis; and an investigator for InflaRx, Chemocentryx, Incyte, GlaxoSmithKline and UCB. Johannes Freudenberg, Deepak Rajpal, Elizabeth Thomas, Christopher Traini are current or former employees and shareholders of GlaxoSmithKline. Zhi Liu reports no conflict of interest. This does not alter our adherence to PLOS ONE policies on sharing data and materials., (Copyright: © 2023 Freudenberg et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objective: It is suggested that hidradenitis suppurativa (HS) is more prevalent and causes greater morbidity in Black patients than in White. Clinical data are however lacking., Patients and Methods: We therefore describe HS risk factors, disease severity and clinical phenotypes in the Blacks and Whites. Patients referred for HS between 1984 and 2019 at the Johns Hopkins Hospital were identified using the Pathology Data System (PDS). Clinical and sociodemographic characteristics were extracted and the van der Zee & Jemec HS clinical phenotypes were recovered., Results: A total of 278 patients were identified. Ethnically, 108 (38.8%) were White, and 170 (61.2%) Black. The following HS phenotypes were found: Regular (n=193, 69.4%), scarring folliculitis (n=40, 1.4%) frictional furuncle (11.2%), conglobata (n=9, 3.2%), syndromic (n=3, 1.1%) and ectopic (n=2, 0.7%). No statistically significant ethnic differences in clinical presentation were found. Blacks however had more severe diseases than Whites (p= 0.024 for trend). With multivariate logistic regression analysis, we found that male sex, disease duration, and smoking were independent predictors of regular HS phenotype. Major limitations are the limited number of cases studied and the lack of data regarding response to therapies., Conclusions: Demographics and phenotypical presentation of HS patients do not seem to be associated with Black ethnicity. However, there is a significant trend for Blacks to present with more Hurley stage 2 and 3 disease compared to White patients. It is speculated that ethnic differences are epiphenomena to social factors, highlighting the broader importance of ethnicity.

Background: Suppurative hidradenitis (HS) is a chronic, inflammatory skin disease of the hair follicle unit. Adalimumab (ADA), an anti-tumor necrosis factor (TNF) alpha, is the only FDA-approved biologic available for the management of HS. TNF-α can also affect glucose and lipid metabolism, promoting insulin resistance and obesity by negatively regulating irisin, a new adipomyokine., Methods: A total of 17 HS patients were enrolled in the study. Blood samples were collected from all patients at baseline and week-16. Plasma irisin levels were detected by ELISA assay., Results: Plasma irisin levels were significantly increased after 16 weeks of ADA therapy in HS patients compared to baseline. Interestingly, plasma irisin levels correlated with clinical response., Conclusions: The link between skin inflammatory diseases and metabolic disorders has aroused great interest in order to research new biomarkers able to early identify metabolic comorbidities. Among these emerging biomarkers, irisin is one of the most recently discovered. We examined a group of patients affected by moderate-severe HS treated with anti-TNF-α, demonstrating for the first time how a therapy able to block an inflammatory cytokine can also affect the metabolic profile by modifying levels of irisin.

Background: Association between Hidradenitis Suppurativa (HS) and Inflammatory Bowel Disease (IBD) has been suggested., Aims: To assess characteristics of HS and IBD in patients with or without concomitant IBD., Methods: In a prospective, nested case-control study, each IBD patient with concomitant HS (Case) was retrospectively matched with 4 patients with HS and no IBD (Controls) for gender and age (±5 years).HS was classified according to the Hurley score and the International Hidradenitis Suppurativa Severity Score System (IHS4). Data were expressed as mean (Standard Deviation). Statistical analysis included Student-t Test or Mann-Whitney Test, χ2 test, univariate and multivariate logistic regression., Results: The study population included 125 patients with HS: 25 with IBD, 100 matched Controls with no IBD. IBD group included 19 (76%) Crohn's disease and 6 (24%) Ulcerative Colitis patients. Obesity, familial HS and perianal HS were less frequent in Cases than in Controls (1[4%] vs 25(25%];p = 0.02; 1[4%] vs 21(21%];p = 0.04; 1[4%] vs 31(31%];p = 0.005, respectively).HS was less severe in Cases when assessed by the IHS4 (5.9 ± 4 vs 9 ± 6.7;p = 0.04).Complete drug-induced response for HS was more frequent in IBD (13[53%] vs28 (28%]; p = 0.04)., Conclusion: Clinical characteristics of HS and of patients differed between Cases and Controls. Present findings suggest the need to appropriately search and assess skin lesions compatible with HS in IBD., Competing Interests: Conflict of interest All authors declare no disclosures specifically related to the study. Biancone L: speaker fee from Takeda, Janssen, ViforPharma, Celltrion; Monteleone G: consultant for First Wave BioPharma and filed a patent related to the treatment of inflammatory bowel diseases with Smad7 antisense oligonucleotides; Calabrese E: speaker fee from Takeda, Janssen, MSD; Bianchi L: speaker or board member for Abbvie, Amgen, Novartis, Almirall, Sunpharma, Sanofi Genzyme, Biogen, Eli Lilly, Janssen, Leo Pharma; Campione E: advisory boards, lectures lee and research grants from Amgen, Almirall, Leo Pharma, UCB., (Copyright © 2022 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.)

Background: Hidradenitis suppurativa (HS) is a chronic inflammatory disease characterized by painful inflamed nodules, abscesses, and pus-draining tunnels appearing in axillary, inguinal, and perianal skin areas. HS lesions contain various types of immigrated immune cells., Objective: This study aimed to characterize mediators that support lesional B/plasma cell persistence in HS., Methods: Skin samples from several cohorts of HS patients and control cohorts were assessed by mRNA sequencing, quantitative PCR on reverse-transcribed RNA, flow cytometry, and immunohistofluorescence. Blood plasma and cultured skin biopsy samples, keratinocytes, dermal fibroblasts, neutrophilic granulocytes (neutrophils), monocytes, and B cells were analyzed. Complex systems biology approaches were used to evaluate bulk and single-cell RNA sequencing data., Results: Proportions of B/plasma cells, neutrophils, CD8 + T cells, and M 0 and M 1 macrophages were elevated in HS lesions compared to skin of healthy and perilesional intertriginous areas. There was an association between B/plasma cells, neutrophils, and B-cell activating factor (BAFF, aka TNFSF13B). BAFF was abundant in HS lesions, particularly in nodules and abscesses. Among the cell types present in HS lesions, myeloid cells were the main BAFF producers. Mechanistically, granulocyte colony-stimulating factor in the presence of bacterial products was the major stimulus for neutrophils' BAFF secretion. Lesional upregulation of BAFF receptors was attributed to B cells (TNFRSF13C/BAFFR and TNFRSF13B/TACI) and plasma cells (TNFRSF17/BCMA). Characterization of the lesional BAFF pathway revealed molecules involved in migration/adhesion (eg, CXCR4, CD37, CD53, SELL), proliferation/survival (eg, BST2), activation (eg, KLF2, PRKCB), and reactive oxygen species production (eg, NCF1, CYBC1) of B/plasma cells., Conclusion: Neutrophil-derived BAFF supports B/plasma cell persistence and function in HS lesions., (Copyright © 2022. Published by Elsevier Inc.)

Hidradenitis suppurativa (HS) is a chronic inflammatory condition of the apocrine glands primarily affecting the axillae, perineum, and inframammary regions. It is characterized by painful, inflamed cutaneous lesions causing nodules, sinus tracts, and abscesses. Cervicofacial HS is an atypical presentation of HS in the head and neck region and is scarcely reported in the literature. We present a 34-year-old male who developed a large facial swelling overlying the left inferior mandibular border. Management included surgical incision and drainage, antibiotic therapy, followed by infliximab (Remicade). The purpose of this case report was to highlight the presentation, pathophysiology, interdisciplinary approach to treatment and follow-up of patients with cervicofacial HS, and finally, review the cervicofacial HS literature., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background and Objectives: Hidradenitis suppurativa (HS)/acne inversa is an intractable skin disease that is characterized by destructive lesions - primarily on the flexural areas. Although its etiology is unknown, genetics is considered to be a factor of its pathology - mutations in γ-secretase genes have been identified in certain familial HS patients, and follicular occlusion is widely accepted as the primary cause of HS. But, no relationship between these mutations and the components of hair follicles has been reported. Thus, we examined changes in these components in mice with a mutation in NCSTN (a γ-secretase gene)., Methods: We generated C57BL/6 mice with an NCSTN mutation and examined their expression of hair cortex cytokeratin and trichohyalin by Western blot and immunohistochemistry, in addition to nicastrin, the product of NCSTN, and NICD compared with wild-type mice. The structure of hair follicles was analyzed by hematoxylin-eosin staining and transmission electron microscopy., Results: In mice with an NCSTN mutation, HS-like skin lesions appeared after age 6 months, the pathological manifestations of which were consistent with the features of human HS. The structure of hair follicles was abnormal in mice with an NCSTN mutation versus wild-type mice, and hair cortex cytokeratin, trichohyalin, nicastrin, and NICD were downregulated in these mice., Conclusions: This NCSTN mutant mouse model could be an improved model to study early lesion development aspects of human HS pathogenesis and could perhaps be a better alternative for evaluating early-acting and preventive therapeutics for HS experimentally before clinical trials in HS patients. NCSTN mutations disrupt the development of hair follicles, leading to abnormal hair follicle structures, perhaps resulting in the onset of HS., (© 2022 S. Karger AG, Basel.)

Background: Paradoxical psoriasis (PP) has been mainly described in patients receiving tumor necrosis factor-α (TNFα) inhibitors for inflammatory bowel disease or psoriasis vulgaris, while such data in the context of hidradenitis suppurativa (HS) are scarce. The purpose of this study was to demonstrate the course of PP and the underlying HS upon switching from adalimumab to a biologic agent targeting the interleukin (IL)-17/IL-23 axis., Methods: The electronic medical database of the outpatient department for HS of a tertiary hospital for skin diseases was searched to identify patients with moderate-to-severe HS under treatment with adalimumab, who developed PP and were switched to biological therapy with an IL-17 or IL-23 inhibitor between February 2016 and January 2022. Disease assessment scores were evaluated at baseline, at time of PP development, as well as six and 12 months thereafter., Results: Among the 83 patients who received adalimumab for the treatment of HS between February 2016 and January 2022, 10 patients (12%) developed paradoxical psoriasiform skin reactions after a median time of seven (range, 2-48) months. There were four females (40%) and six males (60%) with a median age of 42.5 (range, 33-56) years. Five patients presented with plaque psoriasis and five with palmoplantar pustulosis, while four had intertriginous and three nail involvement. In most of the patients, HS responded well to adalimumab at onset of PP. Eight patients were changed to secukinumab, one to ustekinumab, and one to risankizumab. HS further improved in all but 2 patients, one receiving secukinumab and one receiving risankizumab. In addition, all patients achieved improvement of PP., Conclusion: Despite the small number of patients, this study provides support that patients with adalimumab-induced PP may benefit from biologics targeting the IL-17/IL-23 axis. Further studies are needed to establish the optimal therapeutic strategy of the anti-TNFα-induced PP in the context of HS., (© 2023 S. Karger AG, Basel.)

Background: The pathogenetic factors generating the innate immune signal necessary for T-cell activation, initiation and chronification of Hidradenitis suppurativa (HS, also known as Acne inversa) are still poorly understood. Emerging evidence suggests that a defective keratinocyte function critically contributes to HS disease development and progression., Objectives: To elucidate the role of keratinocytes in HS lesion formation, we compared the transcriptomes of lesional and perilesional epidermis isolated from HS patients by RNA sequencing (RNA Seq)., Methods: Pairwise-matched lesional and perilesional HS skin samples of five different donors were obtained and epidermal keratinocytes freshly isolated and processed for RNA extraction and RNA seq. Lesionally regulated genes were analysed by large-scale promoter analysis and functional annotation clustering to identify epidermally overrepresented transcription factor binding sites and functionally related gene groups. Results were experimentally validated with independent epidermal isolates of patient-matched lesional and perilesional HS skin employing qRT-PCR, cell culture, immunoblot and immunostaining., Results: We show that HS is characterized by a strong epidermal stress state evident by a significant overrepresentation of an AP-1-driven gene signature and a substantial activation of the stress-activated cJun N-terminal kinase (JNK) pathway in lesional epidermis. Additionally, our data reveal a strong induction of STAT1 activation in lesional HS epidermis that likely results from IFNγ production and triggered expression of key inflammatory genes coordinating innate immune activation and the adaptive T-cell response in HS., Conclusions: Our data implicate a key role of stress signalling and JAK/STAT1 activation in disease progression of HS and suggest interference with JAK/STAT1 signalling as a potentially promising therapeutic approach for HS., (© 2022 The Authors. Journal of the European Academy of Dermatology and Venereology published by John Wiley & Sons Ltd on behalf of European Academy of Dermatology and Venereology.)

Importance: Hidradenitis suppurativa (HS) is associated with considerable diagnostic delay. Although most patients report adolescent onset, existing HS diagnostic criteria may not adequately capture disease in pediatric populations., Objectives: To determine the proportion of physician-diagnosed pediatric patients with HS who met diagnostic criteria, and describe demographics, disease characteristics, and diagnostic patterns among pediatric patients with HS., Design, Setting, and Participants: In this retrospective, cross-sectional study, electronic medical records from 2 sites of a single academic tertiary care center were included. Eligible patients were those born after January 1, 1993, and assigned International Classification of Diseases, Ninth and Tenth Revisions (ICD-9/10) codes for HS (ICD-9 705.83/ICD-10 L73.2) between January 1, 2012, and July 1, 2021. Patients were excluded if they were older than 18 years at diagnosis, had inaccessible diagnostic visit notes, or were unintentionally assigned an HS ICD code., Exposures: Pediatric patients with HS., Main Outcomes and Measures: Fulfillment of diagnostic criteria in pediatric patients with HS., Results: A total of 297 adolescents with HS were included in the study; 123 patients were female (78.1%), 78 self-identified as Black (26.3%), and 116 self-identified as Hispanic (39.1%). The median (IQR) age at diagnosis was 14.0 (13.0-16.0) years. Documentation from the diagnostic visit demonstrated that 127 (42.8%) patients did not meet all 3 major HS diagnostic criteria. Of these patients, 122 (96.1%) did not meet the recurrence interval criterion (≥2 lesions within 6 months). Overall, 96 patients who did not meet the recurrence interval criterion had documentation from additional visits in the health system; 59 (61.5%) had documentation of 1 or more additional lesions consistent with HS. Review of these additional records demonstrated that 26 of these 59 (44.1%) patients met the recurrence interval criterion after diagnosis, and 44 (74.6%) had recurrent lesions within a 1-year interval (median, 6.5 months; interquartile range, 3.5-12.2 months). Medical chart review was conducted from November 22, 2021, to January 12, 2022. Analysis was conducted from January 12, 2022, to January 15, 2022., Conclusions and Relevance: Overall, 118 (40%) of 297 pediatric patients with HS in this retrospective cross-sectional study did not meet all major diagnostic criteria at the time of diagnosis, largely due to failure to fulfill the 6-month recurrence interval criterion. Future studies are needed to determine the appropriate recurrence interval to facilitate timely diagnosis and promote clinical trial eligibility for pediatric patients with HS.

Hidradenitis suppurativa (HS) is a chronic, inflammatory skin disease comprising painful abscesses, deep nodules, fistulas, and scarring predominantly in the axilla and groin. Bacterial colonization of HS lesions has been well characterized and may lead to chronic infection of lesions. While disease pathogenesis of HS is not fully understood, there is increasing evidence that microbial dysbiosis may be occurring in numerous locations, including the skin and gut. The skin-gut microbiome has been proposed as a mechanism by which inflammatory skin disorders, including HS, can be exacerbated. This is evidenced by HS patients being significantly more likely to develop inflammatory bowel disease as well as the well documented cutaneous manifestations in inflammatory bowel disease. In this review, we discuss the current literature regarding HS skin and gut microbiome research. Furthermore, we discuss further considerations for microbiome research in HS, including the potential role of bacterial metabolites in disease progression and future therapeutic avenues like probiotics., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The role of sweat glands in hidradenitis suppurativa has been largely neglected, despite the fact that its original designation, as "hidrosadénite phlegmoneuse", implied an inflammatory malfunction of the apocrine sweat glands as the underlying pathogenic driver. The aim of this study was to evaluate the role of apocrine sweat glands with respect to the proinflammatory environment of hidradenitis suppurativa. Therefore, gravimetric assessment and multiplex cytokine assays from sweat obtained from patients with hidradenitis suppurativa along with immunofluorescence cytokine/chemokine analysis of lesional apocrine glands- bearing hidradenitis suppurativa skin were performed. Gravimetric assessment of 17 patients with hidradenitis suppurativa revealed that the condition is not associated with hyperhidrosis. However, patients seem to be more affected by subjective sweating. The current data identified a complex proinflammatory signature in hidradenitis suppurativa sweat characterized by a significant upregulation of monocyte chemoattractant protein-1, interleukin-8 (CXCL8), and interferon-γ. In agreement with this, a strong in situ expression of these mediators could be observed in apocrine glands of lesional hidradenitis suppurativa skin. These data shed new light on the proinflammatory capacity of apocrine sweat glands in hidradenitis suppurativa, which may lead to reconsideration of the role of sweat glands in hidradenitis suppurativa pathology.

Recently, interest in the microbiome of cutaneous diseases has increased tremendously. Of particular interest is the gut-brain-skin axis proposed by Stokes and Pillsbury in 1930. The microbiome has been suggested in the pathogenesis of hidradenitis suppurativa, however the link between the commensals and the host is yet to be established. Across all studies, the increased abundance of Porphyromonas , Peptoniphilus, and Prevotella spp., and a loss of skin commensal species, such as Cutibacterium in HS lesions, is a consistent finding. The role of gut and blood microbiome in hidradenitis suppurativa has not been fully elucidated. According to studies, the main link with the intestine is based on the increased risk of developing Crohn's disease and ulcerative colitis, however, further research is highly needed in this area. Lifestyle, dietary approaches, and probiotics all seem to influence the microbiome, hence being a promising modality as adjuvant therapy. The aim of this review was to present the latest reports in the field of research on skin, blood, and gut microbiome in terms of hidradenitis suppurativa.

In the late 1960s, palmoplantar pustulosis (PPP) with sternocostoclavicular arthropathy was first described in Japan, predominantly affecting women in the perimenopausal age. In the 1970s, the chronic non-bacterial osteomyelitis and chronic recurrent multifocal osteomyelitis were initially observed in paediatric patients with approximately 70% girls. Acne fulminans accompanied by polyarthralgia have been observed since early 1970s, which almost exclusively occurs in adolescent boys. Report on spondyloarthropathy associated with hidradenitis suppurativa can be traced back to 1982. The SAPHO syndrome was coined in 1987 to lump together synovitis, acne, pustulosis, hyperostosis and osteitis to conceptualize a group of inflammatory osteocutaneous diseases of unclear etiopathogenesis and ill-defined associations spanning disparate age and gender groups. From historical view, Sasaki syndrome is proposed to replace SAPHO syndrome to represent PPP with sternocostoclavicular arthropathy in the absence of other skin manifestations. Hidradenitis suppurativa is folliculitis in pathogenesis and no longer classified as acne. PPP accompanied by psoriasis vulgaris is more likely psoriasis pustulosa palmoplantaris in dermatological aspect, and the associated arthritis is part of psoriatic arthropathy. Pathophysiology of these disorders is incompletely understood. To echo the advancement of high-throughput sequencing, splitting but not lumping of clinical findings would be a better strategy to decipher these multigenic complex inflammatory disorders., (© 2022 European Academy of Dermatology and Venereology.)

Hidradenitis suppurativa (HS) is a pathology characterized by chronic inflammation and skin lesions. The molecular basis of the inflammatory network remains unclear; however, since microRNAs (miRNAs) are involved in the modulation of inflammation, the composition of a micro-transcriptome RNA library using the blood of HS patients was analysed here. The total miRNA expression profiles of miRNAs from HS patients was assayed by real-time qPCR. Here, compared to healthy controls, miR-24-1-5p, miR-146a-5p, miR26a-5p, miR-206, miR338-3p, and miR-338-5p expression was found significantly different in HS. Knowing the significance of the miRNA mechanism in inflammatory and immune progression, we suggest that miRNA profiles found in HS patients can be significant in understanding the pathogenesis modality and establishing efficient biomarkers for HS early diagnosis. In particular, miR-338-5p was closely related to HS invasiveness and production of cytokines and was atypically overexpressed. miR-338-5p may represent a good promise as a non-invasive clinical biomarker for HS.

Hidradenitis suppurativa (HS; also designated as acne inversa) is a chronic inflammatory disease characterized by painful skin lesions that occur in the axillary, inguinal, gluteal and perianal areas of the body. These lesions contain recurring deep-seated, inflamed nodules and pus-discharging abscesses and fistulas. Affecting about 1% of the population, this common disease has gained appropriate clinical attention in the last years. Associated with numerous comorbidities including metabolic syndrome, HS is considered a systemic disease that severely impairs the quality of life and shortens life expectancy. Therapeutic options for HS are limited, comprising long-term antibiotic treatment, the surgical removal of affected skin areas, and neutralization of TNF-α, the only approved systemic treatment. Novel treatment options are needed to close the therapeutic gap. HS pathogenesis is increasingly better understood. In fact, neutrophilic granulocytes (neutrophils) seem to be decisive for the development of the purulent destructive skin inflammation in HS. Recent findings suggest a key role of the immune mediators IL-1β, IL-17A and G-CSF in the migration into and activation of neutrophils in the skin. Although phytomedical drugs display potent immunoregulatory properties and have been suggested as complementary therapy in several chronic disorders, their application in HS has not been considered so far. In this review, we describe the IL-1/IL-17/G-CSF axis and evaluate it as potential target for an integrated phytomedical treatment of HS.

Hidradenitis suppurativa (HS) is characterized by deep-seated, highly inflamed, and painful lumps/abscesses, fistulae, and sinus tracts that grow extensively deep in the dermis and are highly immunogenic in nature. In about one-third of the HS patients there is strong evidence for the role of γ-secretase mutations along with dysregulated Notch signaling. However, the contribution of dysregulated Notch signaling in HS pathogenesis in relation to hair follicle alterations and hyper-activation of the immune system remains undefined. A genome-wide association study (GWAS), proteomic data and functional investigations of identified sequence variants in HS pathology are not fully revealing. The disease initiation or progression may involve bacterial infection besides intrinsic functional defects in keratinocytes, which may be key to further exacerbate immune cell infiltration and cytokine production in and around the lesional tissue. The absence of a suitable animal model that could fully recapitulate the pathogenesis of HS is a major impediment for proper understanding the underlying mechanisms and development of effective treatments. The presence of extracellular matrix (ECM) degradation products along with dysregulation in keratinocytes and, dermal fibroblasts ultimately affect immune regulation and are various components of HS pathogenesis. Bacterial infection further exacerbates the complexity of the disease progression. While anti-TNFα therapy shows partial efficacy, treatment to cure HS is absent. Multiple clinical trials targeting various cytokines, complement C5a and ECM products are in progress. This review provides state-of-the-art information on these aspects with a focus on dysregulated keratinocyte and immune cells; and role of ECM, and Keratin functions in this regard., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Hidradenitis Suppurativa (HS) is a chronic multifactorial inflammatory skin disease with incompletely understood mechanisms of disease pathology. HS is characterized by aberrant activation of the innate immune system, resulting in activation of pathways that aim to protect against pathogenic microorganisms, and also contribute to failure to resolve inflammation. Imbalance in innate immunity is evident in deregulation of host antimicrobial peptides (AMPs) and the complement system associated with the microbiome dysbiosis. The pathology is further complicated by ability of pathogens associated with HS to overcome host immune response. Potential roles of major AMPs, cathelicidin, defensins, dermcidin, S100 proteins, RNAse 7 and complement proteins are discussed. Dysregulated expression pattern of innate immunity components in conjunction with bacterial component of the disease warrants consideration of novel treatment approaches targeting both host immunity and pathogenic microbiome in HS., Competing Interests: ML has served on the advisory boards for Abbvie, InflaRx, Janssen, and Viela Bio, and consulted for Almirall, BSN medical, Incyte, Janssen, Kymera, Phoenicis, and XBiotech. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Chopra, Arens, Amornpairoj, Lowes, Tomic-Canic, Strbo, Lev-Tov and Pastar.)

Ultrasonography (US) is a modern, in vivo imaging method, which is increasingly being used in dermatology as a complementary tool to clinical examination and dermoscopy. At higher frequencies (15 MHz and above), US is an established method for assessing benign and malignant skin lesions, locoregional staging, monitoring the therapeutic efficacy in various inflammatory skin conditions, and patient follow-up. One field, which may increasingly benefit from performant imaging techniques such as US is dermatologic surgery. Preoperative imaging of cutaneous tumors, inflammatory skin conditions (hidradenitis suppurativa, abscesses, etc.), or nail pathology provide dermatologic surgeons with relevant information for an optimal surgical planning, identifying potential complex aspects which might require interdisciplinary approaches, herein sparing unnecessary surgical interventions and increasing patients' compliance. In this review, we discuss the increasing significance of US in the field of dermatologic surgery, as well as the spectrum of cutaneous pathology where sonography can aid in the preoperative setting to provide a more precise, individualized surgical planning for better counseling to our patients and improved surgical results., (© 2022 The Authors. Journal der Deutschen Dermatologischen Gesellschaft published by John Wiley & Sons Ltd on behalf of Deutsche Dermatologische Gesellschaft.)

Hidradenitis suppurativa (HS) is a complex and debilitating inflammatory skin disease for which no effective treatment is available currently. This is partly because of the lack of adequate human or animal models for defining the pathobiology of the disease. Here, we describe the development of air-liquid (A-L) interface, liquid-submersion (L-S), and bioreactor (Bio) ex vivo skin culture models. All three ex vivo platforms were effective for culturing skin samples for up to 14 days. Tissue architecture and integrity remained intact for at least 3 days for healthy skin and 14 days for HS skin. Up to day 3, no significant differences were observed in % early apoptotic cells among all three platforms. However, late apoptotic/necrotic cell death was increased in HS skin at day 3 in A-L and Bio culture. These cultures efficiently support the growth of various cells populations, including keratinocytes and immune cells. Profiling inflammatory gene signatures in HS skin from these ex vivo cultures showed dynamic changes in expression at day 3 and day 14. All three culture platforms were necessary to represent the inflammatory gene status of HS skin at day 0, suggesting that not all gene clusters were identically altered in each culture method. Similarly, cytokine/chemokine profiling of the supernatants from vehicle- and drug-treated ex vivo HS cultures again showed a better prediction of drug efficacy against HS. Overall, development of these three culture systems collectively provides a powerful tool to uncover the pathobiology of HS progression and screen various drugs against HS., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: It is generally acknowledged that the first morphological change of hidradenitis suppurativa/acne inversa (HS/AI) consists of infundibular plugging of the folliculosebaceous apocrine apparatus, which is followed by acute and chronic inflammation, cysts with sinus formation, and fibrosis. Alternatively, it has been hypothesized that HS/AI is primarily a neutrophilic autoinflammatory disease and that the follicular plugging typical of this disease is secondary to inflammation., Objective: To review the sequence of the changes that mark the disease development, we have performed a histopathologic study on the surgical material from a series of axillary and inguinal/perineal cases., Methods: The histologic material from surgery on Hurley's second and third stage HS/AI was retrieved and collected with the patients' clinical images. The virtually uninvolved skin peripheral to the lesions was studied together with the main inflammatory foci on vertical sections stained with hematoxylin-eosin and immunohistochemistry for the follicle sheaths., Results: The fully developed lesions showed acute and chronic, suppurative and granulomatous inflammation overlapping fibrosis, cysts, and sinuses. Instead, the skin adjacent to florid inflammation showed plugging and dysmorphic alterations of the hair follicles associated with immunopathological changes of the inner root sheath keratin expression., Conclusion: Our observations coincide with the classical pathological studies on the progressive changes of HS/AI; however, in our specimens, the virtually normal skin peripheral to the fully developed lesions show seemingly initial follicular changes that suggest development error. This finding would support the hypothesis of combined mutation-induced epithelial differentiative defects and immunological derangement in HS/AI pathogenesis., (© 2021. Springer-Verlag GmbH Austria, ein Teil von Springer Nature.)

Hidradenitis suppurativa (HS) is a chronic, recurrent, inflammatory skin disease deriving from the hair follicles. The formation of inflammatory nodules, abscesses, fistulas, and sinus tracts is characterized by a large inflow of key pro-inflammatory mediators, such as IFN-γ, TNF-α, IL-1, IL-17, and IL-12/23. Adalimumab is currently the only Food and Drug Administration (FDA)- and European Medicines Agency (EMA)-approved biologic therapy for moderate to severe HS in adults and adolescents. However, the long-term effectiveness of this TNF-α inhibitor in HS patients has shown to be highly variable. This review aims to review the evidence for emerging therapies that target the main pro-inflammatory cytokines in HS pathogenesis. A review of the literature was conducted, using the PubMed and Google Scholar repositories, as well as Clinicaltrials.gov. Presently, the most promising biologics in phase III trials are anti-IL-17 antibodies, secukinumab, and bimekizumab. Furthermore, an anti-IL-1 biologic, bermekimab, is currently in phase II trials, and shows encouraging results. Overall, the clinical efficacies of all new targeted therapies published up to this point are limited. More studies need to be performed to clarify the precise molecular pathology, and assess the efficacy of biological therapies for HS.

The typical Hidradenitis Suppurativa (HS) patient is a young woman with axillary and groin involvement, but the spectrum of the disease presentation is broad and no internationally acknowledged sub-classification of the disease exists to date. It is however speculated that different, yet unidentified, subtypes may respond differently to different treatments or carry a different prognosis. Classification according to self-reported clinically meaningful outcomes for patients offer practical advantages. Our objective was to build an empirical framework for sub-classification of HS patients based on the frequency of HS flares in various anatomic locations, using a cross-sectional questionnaire-based design. All patients with a clinically confirmed diagnosis of HS registered at our department until March 1, 2017 were invited to participate. The frequency of HS flares in various anatomic locations was used for identification of possible HS subtypes using Principal Component Analysis (PCA) and cluster analysis. A total of 524 (62%) of 845 invited patients answered the questionnaire; 402 (76.7%) were female. From the cluster analysis, we identified two possible subtypes of HS, labeled the "upper type" and the "lower type". The "upper type" was characterized by repeated outbreaks in axillary and mammary regions. Meanwhile, the "lower type" was characterized by outbreaks in the inguinal, genital, perianal, and gluteal regions. Our findings support the notion that HS can be sub-classified and imply that the pattern of where lesions are located may be an important element in future HS sub-classification systems., (© 2020. Springer-Verlag GmbH Germany, part of Springer Nature.)

&lt;b&gt;Introduction:&lt;/b&gt; As a rule, the treatment of pilonidal cysts is based on a surgical approach. Surgical treatment depends on the form of the disease and surgeon&apos;s preferences regarding the method. The treatment process does not consider preoperative treatment that would affect the structural components of the skin involved in the pathological process. The results of surgical treatment remain unsatisfactory, leading to a significant number of recurrences and long-term healing of the postoperative wound. &lt;/br&gt;&lt;/br&gt; &lt;b&gt; Materials and methods:&lt;/b&gt; Morphological examination of the pieces of skin with altered sacrococcygeal tissues after radical surgical treatment of 46 patients with pilonidal cyst of the sacrococcygeal region was performed, and 46 patients with acne inversa of the intergluteal cleft, groin and scalp were selected. The sex distribution of patients with pilonidal cysts was as follows: 43 (91.3%) male patients, 3 (6.5%) female patients. Among 46 patients with acne inversa and dissecting cellulitis, the distribution was as follows: 32 (69.6%) male patients and 14 (30.4%) female patients. Patients with pilonidal cysts of the sacrococcygeal region underwent surgical treatment according to the developed method of economical median resection using sutures with internal fixation. &lt;/br&gt; &lt;/br&gt; &lt;b&gt; Results:&lt;/b&gt; Considering and comparing the morphological picture observed in the pathomorphological examination of histological specimens in patients with pilonidal cysts, acne inversa, dissecting cellulitis, the similarity of changes in most patients is noteworthy. "Acne inversa" was first described in 1839 by Velpeau, who originally called the disease "hydradenitis suppurativa", believing that inflammatory changes occur in the sweat glands [1-3]. In 1854, surgeon Verneuil described this disease, and later it was named after him. We observed chronic proliferative inflammation in different layers of the dermis and subcutaneous tissue (the main focus is in the subcutaneous tissue, but closely related to the dermis and epidermis). &lt;/br&gt;&lt;/br&gt; &lt;b&gt;Discussions:&lt;/b&gt; Pilonidal cyst of the sacrococcygeal region, especially without hair in the cavity of the cyst, can be considered as a type of acne inversa with appropriate location. We believe that the use of local and systemic retinoids, namely isotretinoin, in the treatment of patients with this disease other than surgery, together with other groups of drugs traditionally used in the treatment of pilonidal cysts, may be promising in the treatment of pilonidal cysts.

Background: Hidradenitis suppurativa (HS) is a devastating chronic inflammatory skin disease with frequent recurrences. Various systemic treatments and procedures have been used but the efficacy of fractional microneedling radiofrequency (FMR) has not been reported., Aim: To evaluate the clinical and histological efficacy of FMR in the treatment of HS lesions., Methods: An 8-week, prospective, split-body, unblinded study was conducted, which enrolled 10 adult patients with mild to moderate HS to receive 3 sessions of FMR treatment biweekly. HS severity was assessed using the number and type of lesions, HS Physician Global Assessment (HS-PGA) and the modified Sartorius score (mSS). Skin biopsies were performed on participants to assess change in inflammation before and after FMR., Results: Severity of HS was significantly reduced on the FMR-treated side of the body, but not on the control side. Inflammatory HS lesions were significantly reduced after 4 weeks, while HS-PGA and mSS were significantly decreased after 6 weeks. Immunohistochemistry staining showed decreased expression of inflammatory markers including neutrophil elastases, interleukin (IL)-8 and IL-17, tumour necrosis factor-α, transforming growth factor-β1 and matrix metalloproteinases., Conclusion: FMR may be a viable treatment option for mild to moderate HS., (© 2021 British Association of Dermatologists.)