Hidradenitis suppurativa: a disease of follicular epithelium, rather than apocrine glands

Apocrine Gland Damage and the Release of Specific Keratins in Early Stage Indicate the Crucial Involvement of Apocrine Glands in Hidradenitis Suppurativa

The apocrine glands (AGs) are not considered to be primarily involved in hidradenitis suppurativa (HS). This study investigated the potential role of AGs in HS pathogenesis using immunohistochemistry and single-cell sequencing of nonlesional skin and early lesional skin (LS) from patients with HS (n = 12) and healthy controls (n = 8). AG cell destruction was more frequent, and AG size was significantly reduced in the nonlesional skin and LS. Barrier-related genes (eg, CLDN1 and CDH1) were downregulated in the AGs of the nonlesional skin and LS. Damaged AGs in the LS primarily recruited and activated neutrophils through the CXCL-CXCR and SAA1-FPR2 pathways. Elevated levels of specific keratins (keratin 18 and keratin 19) released from damaged AGs were observed on the skin surface of patients and were associated with disease severity. Keratin 19 was also detected in the dermis of the nonlesional skin and LS and was surrounded by neutrophils and macrophages. Moreover, serum keratin 19 levels in patients (N = 20) were significantly negatively correlated with the age at HS onset. Collectively, our findings provide previously unreported evidence that the AGs are damaged and release specific keratins in early HS lesions, indicating a crucial role of the AGs in HS pathogenesis.

Lifestyle Modifications and Nonpharmacological Treatments in Hidradenitis Suppurativa

Multimodal treatment plans are essential for effectively managing hidradenitis suppurativa (HS). To optimize patient outcomes, conventional medical and surgical treatments should be integrated with lifestyle changes and nonpharmacologic modalities. This review offers an evidence-based guide to the most studied and recommended lifestyle changes and complementary and alternative medicine (CAM) modalities for patients with HS.

Hidradenitis suppurativa

Hidradenitis suppurativa is a chronic inflammatory disease characterised by painful, deep-seated nodules, abscesses, and draining tunnels in the skin of axillary, inguinal, genitoanal, or inframammary areas. In recent years, the body of knowledge in hidradenitis suppurativa has advanced greatly. This disorder typically starts in the second or third decade of life. The average worldwide prevalence is 1% but varies geographically. Hidradenitis suppurativa has a profound negative effect on patients' quality of life and on the gross value added to society. Comorbidities (eg, metabolic syndrome, inflammatory arthritis, and inflammatory bowel disease) frequently accompany skin alterations, because of systemic inflammation. Pathogenesis of hidradenitis suppurativa is complex and includes innate immune mechanisms (eg, macrophages, neutrophils, IL-1β, tumour necrosis factor [TNF], and granulocyte colony-stimulating factor), T-cell mechanisms (eg, IL-17 and IFN-γ), and B-cell mechanisms (eg, associated with dermal tertiary lymphatic structures and autoantibodies). Chronic inflammation leads to irreversible skin damage with tunnel formation and morbid scarring. Current treatment includes drug therapy (for the initial, purely inflammatory phase), combined drug and surgical therapy (for the destructive phase), or surgery alone (for the burnout phase). The first systemic therapies approved for hidradenitis suppurativa targeting TNF (adalimumab) and IL-17 (secukinumab and bimekizumab) have expanded drug therapy options for moderate-to-severe disease, which were previously mainly restricted to oral antibiotics. Moreover, there is a robust pipeline of immunomodulatory drugs in various stages of development for hidradenitis suppurativa. Aims of management should include early intervention to prevent irreversible skin damage, adequate control of symptoms including pain, and mitigation of extra-cutaneous comorbidities, all requiring early diagnosis and an interdisciplinary, holistic and personalised approach.

Hidradenitis Suppurativa: Radical Surgical Excisions with Staged Reconstructions: A Single-Surgeon Retrospective Review of 71 Patients

BACKGROUND

Hidradenitis suppurativa is a chronic, inflammatory disease involving the pilosebaceous unit of apocrine gland-bearing skin. Wide surgical excision, wherein margins extend beyond active lesions, is considered curative.

OBJECTIVE

To evaluate the safety and efficacy of wide surgical excision in the treatment of hidradenitis suppurativa.

METHODS

This single-surgeon, single-site analysis included all patients undergoing radical surgical excision of hidradenitis suppurativa between 2015 and 2019. Using paper case notes and electronic health records, researchers identified a total of 71 patients who underwent 262 surgeries.

RESULTS

The mean number of surgeries per patient was 3.7, and the total number of sites addressed was 309. Wound dehiscence, infection, and flap necrosis were the most common complications. Disease recurrence in surgically treated areas was noted in two patients (3%).

CONCLUSIONS

For patients with failed medical management of hidradenitis suppurativa or who have otherwise developed severe disease, wide surgical excision remains a safe, effective treatment with comparatively low recurrence rates. Surgeons should consider staging surgeries, rather than performing a single-stage reconstruction, and anticipate complications.

Effect of adalimumab treatment on inflammatory and hematological parameters in patients with Hidradenitis suppurativa

OBJECTIVE

Hidradenitis suppurativa (HS), a chronic inflammatory disease that typically manifests after puberty, is characterised by painful nodules, abscesses, draining sinus tracts, and scars in areas rich in apocrine glands such as the axillary and inguinal regions. In recent years, blood-based biomarkers such as the Neutrophil/Lymphocyte Ratio (NLR), Platelet/Lymphocyte Ratio (PLR), Monocyte/Lymphocyte Ratio (MLR), Mean Platelet Volume (MPV), Systemic Immune-Inflammation Index (SII) and Pan-Immune-Inflammation Value (PIV) have been used as significant indicators of systemic inflammation. While there are few studies evaluating these biomarkers in HS, the response of these markers to treatment has only been assessed in one study to date. Our study aims to investigate the effect of adalimumab treatment on blood-based systemic inflammation biomarkers in HS, where inflammation plays a significant role.

METHODS

The study included 42 adult patients who received adalimumab treatment at our dermatology and venereology clinic between January 2020 and January 2023. Medical records for complete blood count results of the patients were retrospectively reviewed. All systemic inflammation-based biomarkers were calculated from the absolute values of the complete blood count. The SII was calculated with the following formula: (neutrophil count × platelet count/lymphocyte count). The PIV was calculated as follows: (neutrophil count × platelet count × monocyte count/lymphocyte count). Values before the treatment and at the 12th week of treatment were compared.

RESULTS

When the changes in the inflammatory parameters of the patients were examined, it was found that NLR (2.13 ± 0.87 vs 2.26 ± 1.12), PLR (111.01 ± 39.89 vs 99.43 ± 35.34), MLR (0.27 ± 0.11 vs 0.28 ± 0.12), MPV (9.59 ± 0.71 vs 9.70 ± 0.79), SII (680.79 ± 330.18 vs 687.89 ± 442.66), and PIV (552.02 ± 330.71 vs 605.05 ± 415.96) values did not change statistically significantly after treatment (p > 0.05). While there was a significant decrease in platelet count compared to before treatment, no statistically significant difference was found in the other evaluated blood cells.

CONCLUSION

Adalimumab treatment has not had a significant effect on systemic inflammation markers in HS, an inflammatory disease. More studies are needed to evaluate the effect of adalimumab on these markers in HS.

New treatment of pyoderma gangrenosum and hidradenitis suppurativa: A review

Pyoderma gangrenosum (PG) and hidradenitis suppurativa (HS) are stubborn inflammatory skin diseases categorized as neutrophilic hypodermal dermatoses. These conditions exhibit connections with other autoinflammatory disorders driven by immune responses. Their pathogenesis is complex, rooted in significant imbalances in both innate and adaptive immune systems, particularly featuring elevated levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1, IL-8, IL-17, and IL-23. Studies involving skin tissue pathology and serology have indicated that targeting specific cytokines can bring therapeutic benefits. Indeed, many patients in clinical settings have responded positively to such interventions. Yet, given the diverse cytokines in play, focusing on a single one with antibody therapy might not always be effective. When resistance to biologics emerges, a combined approach targeting multiple overactive cytokines with immunosuppressants, for example cyclosporine and Janus kinase inhibitors, could be an option. In the current review, we explore recent therapeutic developments for PG and HS.

Upregulation of Caveolae-Associated Proteins in Lesional Samples of Hidradenitis Suppurativa: A Case Series Study

Hidradenitis suppurativa (HS) is a chronic, inflammatory skin condition. HS disease management has proven difficult owing to an insufficient understanding of the immunological processes that drive its pathogenesis. We have demonstrated that misregulation of caveolae perturbs inflammatory responses, inhibits cutaneous wound healing, and contributes to immune privilege collapse in other hair follicle-related diseases. However, nothing is known about its role or the role of structural components of caveolae (caveolin [Cav1] 1, Cav2, and Cavin-1) in the pathophysiology of HS. We aimed to identify whether Cav1, Cav2, and Cavin-1 may serve as immunohistochemical markers of HS. Lesional and perilesional HS skin samples from patients (n = 7, mean age = 35.7 years, range = 20-57 years) with active HS and normal skin from control participants (n = 4, mean age = 36.7 years, range = 23-49 years) were used to assess Cav1, Cav2, and Cavin-1 expression and localization by immunofluorescence staining. HS samples demonstrated increased levels of Cav1 compared with normal skin, whereas Cav1, Cav2, and Cavin-1 were all elevated in hair follicles of lesional versus perilesional HS samples, suggesting a potentially novel therapeutic target and highlighting caveolae as potential biomarkers of HS.

Rare missense variants in the SH3 domain of PSTPIP1 are associated with hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic, debilitating skin disease for which few treatment options are available. While most HS is sporadic, some rare kindred show a high-penetrance, autosomal-dominant inheritance. We wanted to identify rare variants that could contribute to HS risk in sporadic cases using candidate gene sequencing. We ultimately identified 21 genes for our capture panel. We included genes of the γ-secretase complex (n = 6) because rare variants in these genes sometimes cause familial HS. We added Notch receptor and ligand genes (n = 13) because γ-secretase is critical for processing Notch receptor signaling. Clinically, some people with PAPA (pyogenic arthritis, pyoderma gangrenosum, and acne) syndrome, a rare inflammatory disease, have concurrent HS. Rare variants in PSTPIP1 are known to cause PAPA syndrome, so we included PSTPIP1 and PSTPIP2 in the capture panel. We screened 117 individuals with HS for rare variations and calculated the expected burden using Genome Aggregation Database (gnomAD) allele frequencies. We discovered two pathogenic loss-of-function variants in NCSTN. This class of NCSTN variant can cause familial HS. There was no increased burden of rare variations in any γ-secretase complex gene. We did find that individuals with HS had a significantly increased number of rare missense variants in the SH3 domain of PSTPIP1. This finding, therefore, implicates PSTPIP1 variation in sporadic HS and further supports dysregulated immunity in HS. Our data also suggests that population-scale HS genetic research will yield valuable insights into disease pathology.

Tertiary Lymphoid Structures Sustain Cutaneous B cell Activity in Hidradenitis Suppurativa

Background

Hidradenitis suppurativa (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 contribution of these cells in HS pathogenesis is unclear.

Objective

We aimed to investigate the dynamics and microenvironmental interactions of B cells within cutaneous HS lesions.

Methods

We combined histological analysis, single-cell RNA-sequencing (scRNAseq), and spatial transcriptomic profiling of HS lesions to define the tissue microenvironment relative to B cell activity within this disease.

Results

Our findings identify tertiary lymphoid structures (TLS) within HS lesions and describe organized interactions between T cells, B cells, antigen presenting cells and skin stroma. We find evidence that B cells within HS TLS actively undergo maturation, including participation in germinal center reactions and class switch recombination. Moreover, skin stroma and accumulating T cells are primed to support the formation of TLS and facilitate B cell recruitment during HS.

Conclusion

Our data definitively demonstrate the presence of TLS 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 non-lymphoid tissue.

The Development of Systemic Inflammatory Diseases in Hidradenitis Suppurativa

It is understood that the skin is a peripheral lymphoid tissue that defends against external environmental stimuli. Continuous activation from these factors, on the other hand, promotes persistent inflammation at the local location and, occasionally, tissue damage. Hidradenitis suppurativa (HS) is a typical inflammatory skin disease and becomes a source of numerous inflammatory cytokines due to the chronic intractable repeated inflamed tissues. Because inflammatory cells and cytokines circulate throughout the body from the inflamed organ, it has been hypothesized that HS-mediated skin inflammation impacts the systemic functioning of numerous organs. Recent updates to clinical and experimental investigations revealed that HS has a significant connection with systemic inflammatory disorders. We provide the details and comprehensive molecular mechanisms associated with systemic inflammatory illnesses due to HS.

Effects of NCSTN Mutation on Hair Follicle Components in Mice

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.

Histopathology of Hidradenitis Suppurativa: A Systematic Review

Hidradenitis suppurativa (HS) is a chronic inflammatory scarring disease felt to be related to occlusion of the hair follicle unit in intertriginous areas. We perform a systematic review on HS histopathology to evaluate current knowledge and discuss future directions. PubMed and Scopus databases were searched for relevant articles published from January 1985 to January 2021 that discussed the pathology of HS. Additional articles were identified by hand-searching, which entailed manually scanning selected journals. A total of 355 citations were identified in the primary search within the main databases. Two hundred and seventy-nine articles were excluded after a review of titles, abstracts, and duplicates. Sixty-one studies did not meet the inclusion criteria or were found to be duplicates, resulting in a total of 15 articles for analysis. Three articles were hand-searched. This comprehensive systematic review of the histopathology of HS confirms a high prevalence of follicular occlusion, follicular hyperkeratosis, and hyperplasia of the follicular epithelium. These findings support the central role of follicular occlusion in the development and progression of HS while providing a potential path to directing therapeutics against follicular occlusion.

Tetracyclines-An Important Therapeutic Tool for Dermatologists

Tetracyclines are a group of antibiotics whose first representative was discovered over 70 years ago. Since then, they have been of great interest in dermatology. In addition to their antibacterial activity, they are able to inhibit metalloproteinases and exhibit anti-inflammatory, anti-apoptotic and antioxidant effects. The side effects have been thoroughly studied over the years, the most characteristic and important ones in daily dermatological practice being: phototoxicity, hyperpigmentation, onycholysis, photoonycholysis, induced lupus erythematosus, and idiopathic intracranial hypertension. In this article, we summarize the use of tetracyclines in infectious diseases and inflammatory dermatoses, and further discuss the instances where the efficacy and safety of tetracyclines have been highlighted over the past few years.

Insights into hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic, debilitating, inflammatory skin disorder with a prevalence of around 1% and a profound impact on patients' quality of life. Characteristic lesions such as inflammatory nodules, abscesses, and sinus tracts develop in the axillae, inguinal, and gluteal areas, typically during or after puberty. A complex interplay of genetic predisposition, hormonal factors, obesity, and smoking contributes to development and maintenance of the disease. HS is considered to arise from an intrinsic defect within the hair follicle, leading to follicular plugging, cyst formation, and subsequent rupture that in turn induce an acute inflammatory response characterized by elevated levels of IL-1β, IL-17, and TNF. Over time, acute lesions transition into chronic disease, with active draining sinus tracts accompanied by extensive fibrosis. HS is associated with other immune-mediated inflammatory diseases, metabolic and cardiovascular disorders, and psychiatric comorbidities. Treatment of HS often requires a combination of antibiotic or immunosuppressing therapies and surgical intervention. Nonetheless, the currently available treatments are not universally effective, and many drugs, which are often repurposed from other inflammatory diseases, are under investigation. Studies into the early stages of HS may yield treatments to prevent disease progression; yet, they are hampered by a lack of appropriate in vitro and animal models.

Radiation therapy in chronic hidradenitis suppurativa: case report

A 26-year-old female presented recurrent painful, carbuncles at both axillae for 10 years. It caused offensive odor and scar. Tissue diagnosis was chronic hidradenitis suppurativa. She was treated using antibiotics followed by multiple excisions with drainage but showed no improvement. Isotretinoin provided no benefit. She was socially isolated and experienced lower quality of life. Consequently, she was sent for radiation therapy. Computed tomography simulation was performed revealing an ulcer with deep chronic pus tracts at her axilla. Three-dimensional conformal radiation therapy was provided with 6 MV photon (7.5 Gy in 3 fractions) covering all ulcers and pus tracts. On the last day of radiation therapy, carbuncles and wounds at the left axilla exhibited much improvement without pus. Three months follow-up showed much improvement of the lesions. The skin was smoother without pus or odor. Radiation therapy was confirmed one treatment option for chronic hidradenitis suppurativa.

Hidradenitis suppurativa: Disease pathophysiology and sex hormones

Hidradenitis suppurativa is a cutaneous chronic inflammatory disease that is estimated to affect about 1% of the population and caused pain, malodorous discharge, disfigurement, and poor quality of life with psychosocial problems. The typical features are recurrent painful nodules, abscesses, and sinus tracts on the axillae, groins, gluteal areas, and anogenital regions since postpuberty. Smoking and obesity are two major triggering factors of hidradenitis suppurativa. Women are prone to have hidradenitis suppurativa than men in Western countries, but the male-to-female ratio is reversed in oriental countries. The disease severity can be affected by menstruation, pregnancy, and menopause. Furthermore, the phenotypes are different among men and women with hidradenitis suppurativa. Men are prone to have buttock involvement while women are prone to have axillary, groins, and submammary lesions. This review introduces the skin appendages and pathophysiology of hidradenitis suppurativa and then focuses on the sex difference and the effects of sex hormones on hidradenitis suppurativa and current hormone-associated treatments.

Insights into the Pathogenesis of HS and Therapeutical Approaches

Hidradenitis suppurativa (HS) is a debilitating, chronic, (auto)inflammatory disease primarily affecting apocrine gland-rich areas of the body. Although pathogenic mechanisms responsible for HS have not yet been fully elucidated, it is a multifactorial process whose main target is the terminal follicle. The role of the inflammatory process (and consequently of cytokine milieu) and of several other factors (genetics, lifestyle, hormonal status, microbiome, innate and adaptive immune systems) involved in HS pathogenesis has been investigated (and often defined) over the years with a view to transferring research results from bench to bedside and describing a unique and universally accepted pathogenetic model. This review will update readers on recent advances in our understanding of HS pathogenesis and novel (potential) medical therapies for patients with moderate-to-severe HS.

Hidradenitis suppurativa: A folliculotropic disease of innate immune barrier dysfunction?

The innate immune system of human skin consists of a multi-layered barrier consisting of cells and soluble effector molecules charged with maintaining homeostasis and responding to insults and infections. It has become increasingly clear that these barrier layers become compromised in skin diseases, especially in disorders of an (auto)inflammatory nature. In the case of hidradenitis suppurativa, great strides have been made in recent years in characterizing the underlying breakdown in homeostatic innate immunity, including an increasing understanding of the central role of the hair follicle in this process. This breakdown appears to occur at multiple levels: the pilosebaceous unit, associated epithelium, the cutaneous microbiome, alteration of immune cell function and local molecular events such as complement activation. This review seeks to summarize, contextualize and analyse critically our current understanding of how these innate immune barriers become dysregulated in the early stage(s) of hidradenitis suppurativa, and to speculate on where potential hidradenitis suppurativa research could be most fruitful.

[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.

Histopathological progression of hidradenitis suppurativa/acne inversa : A morphological study with a closer look on the early changes of the folliculosebaceous apocrine apparatus

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.

Efficacy of non-surgical monotherapies for hidradenitis suppurativa: a systematic review and network meta-analyses of randomized trials

OBJECTIVE

We determined the relative efficacy of non-surgical monotherapies for hidradenitis suppurativa (HS).

METHODS

Network meta-analyses were conducted to determine treatments' surface under the cumulative ranking curve (SUCRA) value (i.e., an estimate that ranks efficacy); pairwise comparisons were conducted.

RESULTS AND CONCLUSIONS

Ten trials were eligible for quantitative analyses; however, all did not have a common endpoint. Outcomes corresponded to pain severity, clinical response, quality of life and abscess count. For pain reduction, infliximab was ranked most efficacious (SUCRA =94%) compared to bermekimab, anakinra and placebo; infliximab reduced pain more significantly (p < 0.05) than anakinra and than placebo. For occurrence of clinical response, bimekizumab had the highest SUCRA (67%) relative to adalimumab, anakinra and placebo; bimekizumab was more efficacious than placebo (p < 0.05). For quality of life in mild HS, Botox had the highest SUCRA (94%) compared to adalimumab and placebo; Botox was more efficacious than placebo (p < 0.05). For reduction in abscess count, oral tetracycline had the highest SUCRA (48%) compared to topical clindamycin and vehicle. Our work-being the first NMA study on non-surgical HS monotherapies-contributes to the comparative effectiveness literature for this condition.

Chronic Systemic Inflammatory Skin Disease as a Risk Factor for Cardiovascular Disease

Chronic systemic skin disease and cardiovascular disease are multisystem disorders which have been associated with each other for centuries. Recent research has strengthened this association, particularly in systemic inflammatory disease. Here we explore the current literature on psoriasis, hidradenitis suppurativa, lupus erythematosus, acanthosis nigricans, atopic dermatitis, and bullous pemphigoid. Psoriasis is a chronic inflammatory disorder that has been labeled as a risk-modifier for hyperlipidemia and coronary artery disease by the American College of Cardiology ACC lipid guidelines. Cardiovascular disease is also found at a significantly higher rate in patients with hidradenitis suppurativa and lupus erythematosus. Some associations have even been noted between cardiovascular disease and acanthosis nigricans, atopic dermatitis, and bullous pemphigoid. While many of these associations have been attributed to a shared underlying disease process such as chronic systemic inflammation and shared underlying risk factors, these dermatologic manifestations can help to identify patients at higher risk for cardiovascular disease.

Concomitant psoriasis and hidradenitis suppurativa responsive to adalimumab therapy: A case series

Psoriasis and hidradenitis suppurativa are inflammatory dermatoses that have been associated with arthritis, metabolic syndrome, obesity, and smoking. They share common pathogenic mechanisms such as elevated levels of several proinflammatory cytokines including tumor necrosis factor (TNF), interleukin-17A, and impaired Notch pathway. Thus, treatments for both diseases are sometimes overlapping. Biological therapy such as adalimumab is effective for patients with hidradenitis suppurativa and psoriasis. Adalimumab is a monoclonal antibody that binds to TNF and inhibits the cytokine interaction with the TNF receptors, thus inhibiting the inflammatory cascade. Currently, data are lacking on the treatment for co-occurrence of psoriasis and hidradenitis suppurativa. This case series describes three patients with a diagnosis of concomitant psoriasis and hidradenitis suppurativa. In these cases, after 12 weeks of treatment with adalimumab 40 mg every other week, the average Psoriasis Area Severity Index score reduced from 21.4 to 2.9 for psoriasis, Hidradenitis Suppurativa-Physician's Global Assessment from 3.3 to 0.7, and pain Visual Analog Scale for hidradenitis suppurativa from 4.6 to 2. The results suggest that adalimumab is a treatment of choice for patients with concomitant hidradenitis suppurativa and psoriasis.

Histologic progression of acne inversa/hidradenitis suppurativa: Implications for future investigations and therapeutic intervention

Since first recognized in 1839, the pathogenesis of acne inversa (AI) has undergone repeated revisions. Although there is agreement that AI involves occlusion of hair follicles with subsequent inflammation and the formation of tracts, the histologic progression of this disease still requires refinement. The objective of this study was to examine the histologic progression of AI based on the examination of a large cohort of punch biopsies and excisional samples that were examined first by hematoxylin and eosin staining. The most informative of these samples were step‐sectioned and stained by immunohistochemistry for epithelial and inflammatory markers. Based on this examination, the following observations were made: 1) AI arises from the epithelium of the infundibulum of terminal and vellus hairs; 2) These form cysts and epithelial tendrils that extend into soft tissue; 3) Immunohistochemical staining demonstrates the epithelium of AI is disordered with infundibular and isthmic differentiation and de novo expression of stem cell markers; 4) The inflammatory response in AI is heterogeneous and largely due to cyst rupture. The conclusions of this investigation were that AI is an epithelial‐driven disease caused by infiltrative, cyst forming tendrils and most of the inflammation is due to cyst rupture and release of cornified debris and bacteria. Cyst rupture often occurs below the depths of punch biopsy samples indicating their use for analysis may give an incomplete picture of the disease. Finally, our data suggest that unless therapies inhibit tendril development, it is unlikely they will cause prolonged treatment‐induced remission in AI.

The Efficacy and Effectiveness of Non-ablative Light-Based Devices in Hidradenitis Suppurativa: A Systematic Review and Meta-Analysis

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disorder that may be treated with non-ablative light-based devices; however, no systematic reviews on the topic exist to date. We conducted a systematic review and meta-analysis to determine efficacy of non-ablative light-based devices in treating HS. Specifically, a systematic review was conducted using MEDLINE, EMBASE, Web of Science and CINAHL. We analyzed the use of non-ablative light-based devices in the treatment of HS. At least two investigators performed title/abstract review and data extraction. Meta-analysis was conducted using comprehensive meta-analysis software. 5 RCTs and 11 case reports/series were included (n = 211 unique patients). No observational studies were found. For Nd:YAG laser, meta-analysis of 3 RCTs reported improvement in modified HS Lesion Area and Severity Index (HS-LASI) when compared to control subjects. In addition, three case reports/series reported HS-LASI, Physician Global Assessment (PGA) scores and number-of-lesion improvements in treated patients. For intense pulsed light (IPL), two RCTs reported HS-LASI and Dermatology Life Quality Index (DLQI) score improvements. For Alexandrite laser, one case report showed lesion improvement. In conclusion, meta-analysis of Nd:YAG laser in HS patients suggests significant improvement in HS-LASI scores. For IPL, evidence is limited, but suggests improvement in HS-LASI and DLQI scores. For Alexandrite laser, evidence precludes conclusions. Given small sample sizes and inconsistent reporting scales, larger RCTs are required to better determine the efficacy of these modalities in treating HS.

Aetiology and pathogenesis of hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic inflammatory disorder. Patients develop inflamed nodules and abscesses and, at later stages of disease, epithelialized tunnels and scars in skinfolds of axillary, inguinal, gluteal and perianal areas. Quality of life is affected due to severe pain, purulent secretion, restricted mobility and systemic involvement. Genetics and lifestyle factors including smoking and obesity contribute to the development of HS. These factors lead to microbiome alteration, subclinical inflammation around the terminal hair follicles, and infundibular hyperkeratosis, resulting in plugging and rupture of the follicles. Cell-damage-associated molecules and propagating bacteria trigger inflammation and lead to massive immune cell infiltration that clinically manifests as inflamed nodules and abscesses. The immune system plays a key role also in the progression and chronification of skin alterations. Innate proinflammatory cytokines (e.g. interleukin-1β and tumour necrosis factor-α), mediators of activated T helper (Th)1 and Th17 cells (e.g. interleukin-17 and interferon-γ), and effector mechanisms of neutrophilic granulocytes, macrophages and plasma cells are involved. Simultaneously, skin lesions contain anti-inflammatory mediators (e.g. interleukin-10) and show limited activity of Th22 and regulatory T cells. The inflammatory vicious circle finally results in pain, purulence, tissue destruction and scarring. Chronic inflammation in patients with HS is also frequently detected in organs other than the skin, as indicated by their comorbidities. All these aspects represent a challenge for the development of therapeutic approaches, which are urgently needed for this debilitating disease. This scholarly review focuses on the causes and pathogenetic mechanisms of HS and the potential therapeutic value of this knowledge.

Matrix remodelling and MMP expression/activation are associated with hidradenitis suppurativa skin inflammation

Hidradenitis suppurativa/acne inversa (HS) is a chronic, inflammatory, recurrent, debilitating skin disease of the hair follicle, associated with considerable tissue remodelling. Although abnormal cytokine expression was detected both in perilesional and in uninvolved skin, up to now there is no model allowing a better understanding of the implicit inflammatory mechanisms in HS. The aim of this study was to investigate the inflammatory response in HS skin by mean of an ex vivo model culture. To that purpose, nine skin biopsy specimens from patients suffering from HS and controls were cultured up to 4 days. Microscopy imaging investigations showed variations of collagen I and III organization, and an increase in elastin fibres fragmentation in HS skin after 4 days of culture. The HS matrix structure remodelling was associated with high level of MMP-2 and MMP-9 in HS lesional skin. After 4 days of culture, the MMP expression in HS perilesional skin reached the level observed in HS lesional skin. Concomitantly, an increase in IL-1β concentration was observed in all skin samples after 4 days of culture, although IL-1β concentrations remained significantly higher in HS lesional skin as compared with control skin. Meanwhile, neither IL-17 concentrations nor the inflammasome components NLRP3 and caspase-1 varied. Thus, our HS skin model culture showed that MMP-induced matrix alteration could participate in HS inflammation by releasing biological active peptides and inflammatory factors from the extracellular matrix (ECM), and open new opportunities to investigate the regulation of the inflammatory mechanism associated with HS.

Altered keratinization and vitamin D metabolism may be key pathogenetic pathways in syndromic hidradenitis suppurativa: a novel whole exome sequencing approach

BACKGROUND

Diagnosis of pyoderma gangrenosum, acne and hidradenitis suppurativa (PASH) and pyogenic arthritis, pyoderma gangrenosum, acne, and hidradenitis suppurativa (PAPASH) patients, in spite of recently identified genetic variations, is just clinical, since most patients do not share the same mutations, and the mutations themselves are not informative of the biological pathways commonly disrupted in these patients.

OBJECTIVE

To reveal genetic changes more closely related to PASH and PAPASH etiopathogenesis, identifying novel common pathways involved in these diseases.

METHODS

Cohort study on PASH (n = 4) and PAPASH (n = 1) patients conducted using whole exome sequencing (WES) approach and a novel bioinformatic pipeline aimed at discovering potentially candidate genes selected from density mutations and involved in pathways relevant to the disease.

RESULTS

WES results showed that patients presented 90 genes carrying mutations with deleterious and/or damage impact: 12 genes were in common among the 5 patients and bared 237 ns ExonVar (54 and 183 in homozygosis and heterozygosis, respectively). In the pathway enrichment analysis, only 10 genes were included, allowing us to retrieve 4 pathways shared by all patients: (1) Vitamin D metabolism, (2) keratinization, (3) formation of the cornified envelope and (4) steroid metabolism. Interestingly, all patients had vitamin D levels lower than normal, with a mean value of 10 ng/mL.

CONCLUSION

Our findings, through a novel strategy for analysing the genetic background of syndromic HS patients, suggested that vitamin D metabolism dysfunctions seem to be crucial in PASH and PAPASH pathogenesis. Based on low vitamin D serum levels, its supplementation is envisaged.

Hidradenitis Suppurativa as a Potential Subtype of Autoinflammatory Keratinization Disease

Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition, clinically characterized by boiled cysts, comedones, abscesses, hypertrophic scars, and/or sinus tracts typically in the apocrine-gland-rich areas such as the axillae, groin, and/or buttocks. Although its precise pathogenic mechanisms remain unknown, I herein emphasize the importance of the following three recent discoveries in the pathogenesis of HS: First, heterozygous loss-of-function mutations in the genes encoding γ-secretase, including NCSTN, PSENEN, and PSEN1, have been identified in some patients with HS. Such genetic alterations result in hyperkeratosis, dysregulated hair follicle differentiation, and cyst formation via aberrant Notch signaling. Furthermore, Psen1-/Psen2-, Psen1-, Ncstn+/-, and Notch1-/Notch2- mice share common phenotypes of human HS, suggesting a role of aberrant keratinization in the development of HS. Second, upregulation of interleukin 1β, interleukin-36, caspase-1, and NLRP3 and dysregulation of the Th17:Treg cell axis have been demonstrated in HS samples, suggesting that autoinflammation is a key event in the pathophysiology of the disease. Notably, HS may be complicated with other autoinflammatory diseases such as inflammatory bowel diseases and pyoderma gangrenosum, again highlighting the importance of autoinflammation in HS. Last, biologics such as adalimumab, infliximab, anakinra, ustekinumab, and secukinumab are reportedly effective for moderate-to-severe HS. These findings collectively suggest that HS is closely linked with aberrant keratinization and autoinflammation, raising the question whether it represents an autoinflammatory keratinization disease, a recently proposed disease entity. In this mini review, I introduce the concept of autoinflammatory keratinization disease and attempt to address this clinically important question.

Seventy-MHz Ultrasound Detection of Early Signs Linked to the Severity, Patterns of Keratin Fragmentation, and Mechanisms of Generation of Collections and Tunnels in Hidradenitis Suppurativa

OBJECTIVES

To test the capability of 70-MHz ultrasound for detecting initial ultrasound signs of hidradenitis suppurativa (HS) linked to severity.

METHODS

A cross-sectional study of the ultrasound images of patients with HS was conducted and compared with a healthy control group. Detection and identification of early subclinical ultrasound signs in the lesional and perilesional areas of the HS cases in comparison with the control group were performed. Statistical analyses included mean, dispersion measures, the Kruskal-Wallis test, and bivariate and multivariate ordered logistic regression studies. Significance was assessed at P < .05.

RESULTS

A total of 139 patients with HS met the criteria and showed abnormalities of the hair follicles such as a curved shape, ballooning, and protrusion into pseudocysts, collections, or tunnels (donor of keratin sign). Significant increases in the sizes of the hair follicles and hair shafts were found in HS cases. The following ultrasound signs were significantly linked to severity: a connecting band between the base of adjacent hair follicles (bridge sign), a fragment of the hair shaft extruding through a dilated hair follicle (sword sign), and retained cylindrical fragments of keratin in the dermis. Two patterns of fragmentation of the keratin were detected: multifragment and cylindrical.

CONCLUSIONS

Ultrasound can detect early HS signs that are significantly linked to severity and 2 types of fragmentation of the keratin, which could support the generation and perpetuation of the fluid collections and tunnels. These ultrasound signs can help prompt diagnosis and management, the development and testing of medications, and the measure of treatment outcomes in HS.

Laser and Light-Based Treatment Modalities for the Management of Hidradenitis Suppurativa

Hidradenitis suppurativa is a chronic inflammatory skin disease characterized by inflammatory nodules, abscesses, and sinus tracts in intertriginous areas that has a significant impact on patient quality of life. Treatments range from topical, intralesional, systemic, and surgical. Furthermore, laser and light-based treatment options have become increasingly popular because of the limitations of adverse effects associated with systemic therapy and decreased down-time associated with laser and light therapy. These modalities are thought to work through a variety of mechanisms including decreasing inflammation, destroying hair follicles, targeting sebaceous glands, killing bacteria, and debulking lesions through ablation. This review explores these laser and light-based treatment modalities for the treatment of hidradenitis suppurativa.

A novel nicastrin mutation in a three-generation Dutch family with hidradenitis suppurativa: a search for functional significance

Background

Mutations in the γ‐secretase enzyme subunits have been described in multiple kindreds with familial hidradenitis suppurativa (HS).

Objective

In this study, we report a novel nicastrin (NCSTN) mutation causing HS in a Dutch family. We sought to explore the immunobiological function of NCSTN mutations using data of the Immunological Genome Project.

Methods

Blood samples of three affected and two unaffected family members were collected. Whole‐genome sequencing was performed using genomic DNA isolated from peripheral blood leucocytes. Sanger sequencing was done to confirm the causative NCSTN variant and the familial segregation. The microarray data set of the Immunological Genome Project was used for thorough dissection of the expression and function of wildtype NCSTN in the immune system.

Results

In a family consisting of 23 members, we found an autosomal dominant inheritance pattern of HS and detected a novel splice site mutation (c.1912_1915delCAGT) in the NCSTN gene resulting in a frameshift and subsequent premature stop. All affected individuals had HS lesions on non‐flexural and atypical locations. Wildtype NCSTN appears to be upregulated in myeloid cells like monocytes and macrophages, and in mesenchymal cells such as fibroblastic reticular cells and fibroblasts. In addition, within the 25 highest co‐expressed genes with NCSTN we identified CAPNS1,ARNT and PPARD.

Conclusion

This study reports the identification a novel NCSTN gene splice site mutation which causes familial HS. The associated immunobiological functions of NCSTN and its co‐expressed genes ARNT and PPARD link genetics to the most common environmental and metabolic HS risk factors which are smoking and obesity.

Hidradenitis suppurativa

Hidradenitis suppurativa (HS; also designated as acne inversa) is a chronic inflammatory disorder, which affects the intertriginous skin and is associated with numerous systemic comorbidities. The estimated prevalence of HS is ~1% in most studied countries. Typically starting in early adulthood, cutaneous inflamed nodules, abscesses and pus-discharging tunnels develop in axillary, inguinal, gluteal and perianal body sites. The comorbidities of HS include metabolic and cardiovascular disorders, which contribute to reduced life expectancy. A genetic predisposition, smoking, obesity and hormonal factors are established aetiological factors for HS. Cutaneous changes seem to start around hair follicles and involve activation of cells of the innate and adaptive immune systems, with pivotal roles for pro-inflammatory cytokines such as tumour necrosis factor, IL-1β and IL-17. The unrestricted and chronic immune response eventually leads to severe pain, pus discharge, irreversible tissue destruction and scar development. HS has profound negative effects on patients' quality of life, which often culminate in social withdrawal, unemployment, depression and suicidal thoughts. The therapeutic options for HS comprise antibiotic treatment, neutralization of tumour necrosis factor and surgical intervention together with lifestyle modification. Nevertheless, there is an enormous need for awareness of HS, understanding of its pathogenesis and novel treatments.

Hidradenitis suppurativa and acne vulgaris and conglobata—systematic review and meta-analysis

Background

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disorder which involves painful nodules and draining abscesses in flexural areas. Acne vulgaris and its more severe variants including acne conglobata and acne fulminans are also disorders involving the follicular unit. Given that follicular obstruction, dilatation and inflammation feature in both HS and acne vulgaris/conglobata, it has been suggested that HS is associated with acne vulgaris/conglobata.

Methods

The present systematic review and meta-analysis was performed according to recommended PRISMA guidelines. All eligible case-control studies comparing patients with HS vs non-HS were included in the present review. All studies must have included either the proportion of patients with acne vulgaris/conglobata in each group, or the summary effect size for association between HS and acne vulgaris/conglobata. The odds ratio (OR) was used as a summary statistic.

Results

From pooled unadjusted meta-analysis, we found a significantly higher proportion of patients with acne vulgaris/conglobata in HS cases compared to controls (OR 3.44, 95% CI 1.95–6.07, P < 0.0001, I2 = 100%). Pooled meta-analysis was also performed with adjusted effect sizes. This demonstrated that HS was significantly associated with acne vulgaris/conglobata after adjustment for potential confounders (OR 3.44, 95% CI 2.43–4.87, P < 0.00001, I2 = 99%).

Conclusions

In summary, a significant association was found between HS and acne vulgaris/conglobata. This has implications in terms of understanding the burden of disease on patient quality of life as well as consideration of optimal management strategies to target both disorders. Physicians taking care of patients with HS should be aware of this association.

Hidradenitis Suppurativa: Comprehensive Review of Predisposing Genetic Mutations and Changes

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disorder. A genetic component in the pathogenesis is highly likely considering that ~30% to 40% of patients with HS report a family history of the disease. The genetic mutations related to HS that have been reported to date suggest HS can be inherited as a monogenic trait because of a defect in either the Notch signaling pathway or inflammasome function, or as a polygenic disorder resulting from defects in genes regulating epidermal proliferation, ceramide production, or in immune system function. This review provides a summary of genetic mutations reported in patients diagnosed with HS and discusses the mechanisms by which these genes are involved in its pathogenesis.

Successful treatment of stage III hidradenitis suppurativa with botulinum toxin A

A 41-year-old obese Native American woman presented with hidradenitis suppurativa (HS) after failing all available treatment options. Her HS was more pronounced in the axillary and groin regions (Hurley stage III) and was a major source of her pain and a barrier for home exercise and aquatic therapy. She received a botulinum toxin A injection every 3 months (four times thus far), which has significantly helped alleviate her pain and curb the progress of her HS by resolving abscesses and healing draining sinuses.

Current and future treatment of hidradenitis suppurativa

This scholarly review on the current and future treatment of hidradenitis suppurativa (HS) focuses on medical and surgical treatment options, while novel pipeline drugs are also discussed. Treatment goals are to limit the incidence and duration of flares, reducing inflammation and suppuration, achieving local cure after surgery and, most importantly, to improve the quality of life of patients with HS. The type of medication and/or surgery should be chosen based on the stage of the disease and the degree of inflammation. However, the lack of a simple scoring system and the lack of clear surgical outcome definitions hamper the interpretation of treatment efficacy and the comparison between different treatment strategies. The therapeutic pipeline for HS is gradually expanding, and will probably lead to a broader panel of more effective therapeutic options.

T helper 17 cell/regulatory T-cell imbalance in hidradenitis suppurativa/acne inversa: the link to hair follicle dissection, obesity, smoking and autoimmune comorbidities

BACKGROUND

Disintegration of the infundibula of terminal hair follicles (HFs) in intertriginous skin areas exhibits the histological hallmark of hidradenitis suppurativa (HS)/acne inversa, featuring a dissecting terminal hair folliculitis. Elevated serum levels of interleukin (IL)-17 and local increase in the ratio of proinflammatory T helper (Th)17 cells and anti-inflammatory regulatory T cells (Tregs) have been reported. Perifollicular Tregs play a key role in HF stem cell homeostasis and infundibular integrity.

OBJECTIVES

In this review, we evaluate the Th17/Treg ratio in HS, its aggravating conditions and associated comorbidities. Furthermore, we intended to clarify whether drugs with reported beneficial effects in the treatment of HS readjust the deviated Th17/Treg axis.

METHODS

PubMed-listed, peer-reviewed original research articles characterizing Th17/Treg regulation in HS/acne inversa and associated comorbidities were selected for this review.

RESULTS

This review presents HS as a disease that exhibits an increased Th17/Treg ratio. Perifollicular deficiencies in Treg numbers or function may disturb HF stem cell homeostasis, initiating infundibular dissection of terminal HFs and perifollicular inflammation. The Th17/Treg imbalance is aggravated by obesity, smoking and decreased Notch signalling. In addition, HS-associated autoimmune diseases exhibit a disturbed Th17/Treg axis resulting in a Th17-dominant state. All drugs that have beneficial effects in the treatment of HS normalize the Th17/Treg ratio.

CONCLUSIONS

HS immunopathogenesis is closely related to deviations of the Th17/Treg balance, which may negatively affect Treg-controlled HF stem cell homeostasis and infundibular integrity. Pharmacological intervention should not only attenuate Th17/IL-17 signalling, but should also improve Treg function in order to stabilize HF stem cell homeostasis and infundibular integrity.

Investigational drugs in clinical trials for Hidradenitis Suppurativa

INTRODUCTION

Hidradenitis suppurativa is a chronic skin disease with a significant unmet need for treatment options. Randomized controlled trials are few and only a single drug (adalimumab) has Hidradenitis as a registered indication.

AREAS COVERED

The clinicaltrials.gov and the EudraCT clinical trials register for reported trials on Hidradenitis Suppurativa was searched on the 22-06-2017. Trials for upcoming new drugs for HS are reported focusing on drugs in phase I and II trials.The clinicaltrials.gov and the EudraCT clinical trials register for reported trials on Hidradenitis Suppurativa was searched on the 22-06-2017. Trials for upcoming new drugs for HS are reported focusing on drugs in phase I and II trials.

EXPERT OPINION

Currently, MABp1, Secukinumab, CJM112, Apremilast and IFX-1 are being investigated in Phase I and II trials and offer theoretical and promising new treatment options. A trial with the drug MEDI8968 has been terminated with disappointing results. Metformin, Botulinum Toxin B, Provodine, Benzoyl Peroxide and intralesional triamcinolone are being tested as well. Treatment of Hidradenitis remains a challenge and quality RTCs are needed. Studies indicates a range of potential targets for therapy such as interleukin-1 and interleukin-17, but 'broad-spectrum' immunosuppressants like phosphodiesterase-4 inhibitors are being examined as well. A range of outcomes, including Physician Global Assessment, Sartorius scores and hidradenitis suppurativa clinical response are used in these trials, making future meta-analysis of the data difficult.