Hidradenitis suppurativa presents a methylome dysregulation capable to explain the pro-inflammatory microenvironment: Are these DNA methylations potential therapeutic targets?

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic, systemic, inflammatory skin condition with elusive pathogenesis that affects therapeutic intervention directly. OBJECTIVE: To characterize epigenetic variations in cytokines genes contributing to HS. METHODS: Epigenome-wide DNA methylation profiling with the Illumina Epic array was performed on blood DNA samples from 24 HS patients and 24 age- and sex-matched controls to explore DNA methylation changes in cytokine genes. RESULTS: We identified 170 cytokine genes including 27 hypermethylated CpG sites and 143 genes with hypomethylated sites respectively. Hypermethylated genes, including LIF, HLA-DRB1, HLA-G, MTOR, FADD, TGFB3, MALAT1 and CCL28; hypomethylated genes, including NCSTN, SMAD3, IGF1R, IL1F9, NOD2, NOD1, YY1, DLL1 and BCL2 may contribute to the pathogenesis of HS. These genes were enriched in the 117 different pathways (FDR p-values ≤ 0.05), including IL-4/IL-13 pathways and Wnt/ß-catenin signalling. CONCLUSIONS: The lack of wound healing, microbiome dysbiosis and increased tumour susceptibility are all sustained by these dysfunctional methylomes, hopefully, capable to be targeted in the next future. Since methylome describes and summarizes genetic and environmental contributions, these data may represent a further step towards a feasible precision medicine also for HS patients.

CSL324, a granulocyte colony-stimulating factor receptor antagonist, blocks neutrophil migration markers that are upregulated in hidradenitis suppurativa.

BACKGROUND: Neutrophils have been shown to contribute to the pathophysiology of hidradenitis suppurativa (HS), a chronic, painful and debilitating inflammatory skin disease, yet their exact role remains to be fully defined. Granulocyte colony-stimulating factor (G-CSF), a major regulator of neutrophil development and survival, can be blocked by the novel, fully human anti-G-CSF receptor (G-CSFR) monoclonal antibody CSL324. OBJECTIVES: We investigated the activation and migration of neutrophils in HS and the impact of blocking G-CSFR with CSL324. METHODS: Biopsy and peripheral blood samples were taken from participants of two studies: 2018.206, a noninterventional research study of systemic and dermal neutrophils and inflammatory markers in patients with neutrophilic skin diseases, and CSL324_1001 (ACTRN12616000846426), a single-dose ascending and repeated dose, randomized, double-blind, placebo-controlled study to assess the safety, pharmacokinetics and pharmacodynamics of CSL324 in healthy adult subjects. Ex vivo experiments were performed, including neutrophil enumeration and immunophenotyping, migration, receptor occupancy and transcriptome analysis. RESULTS: The number of cells positive for the neutrophil markers myeloperoxidase (MPO) and neutrophil elastase (NE) was significantly higher in HS lesions compared with biopsies from healthy donors (HDs) (P < 0.0001 and P = 0.0223, respectively). In peripheral blood samples, mean neutrophil counts were significantly higher in patients with HS than in HDs (2.98 vs. 1.60 × 109 L-1, respectively; P = 8.8 × 10-4). Neutrophil migration pathways in peripheral blood were increased in patients with HS and their neutrophils demonstrated an increased migration phenotype, with higher mean CXCR1 on the surface of neutrophils in patients with HS (24453.20 vs. 20798.47 for HD; P = 0.03). G-CSF was a key driver of the transcriptomic changes in the peripheral blood of patients with HS and was elevated in serum from patients with HS compared with HDs (mean 6.61 vs. 3.84 pg mL-1, respectively; P = 0.013). Administration of CSL324 inhibited G-CSF-induced transcriptional changes in HDs, similar to those observed in the HS cohort, as highlighted by expression changes in genes related to neutrophil migratory capacity. CONCLUSIONS: Data suggest that neutrophils contribute to HS pathophysiology and that neutrophils are increased in lesions due to an increase in G-CSF-driven migration. CSL324 counteracted G-CSF-induced transcriptomic changes and blocked neutrophil migration by reducing cell-surface levels of chemokine receptors.

Neutrophilic granulocyte-derived B-cell activating factor supports B cells in skin lesions in hidradenitis suppurativa.

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 M0 and M1 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.

A rare loss-of-function genetic mutation suggest a role of dermcidin deficiency in hidradenitis suppurativa pathogenesis.

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease with a multifactorial aetiology that involves a strict interplay between genetic factors, immune dysregulation and lifestyle. Familial forms represent around 40% of total HS cases and show an autosomal dominant mode of inheritance of the disease. In this study, we conducted a whole-exome sequence analysis on an Italian family of 4 members encompassing a vertical transmission of HS. Focusing on rare damaging variants, we identified a rare insertion of one nucleotide (c.225dupA:p.A76Sfs*21) in the DCD gene encoding for the antimicrobial peptide dermcidin (DCD) that was shared by the proband, his affected father and his 11-years old daughter. Since several transcriptome studies have shown a significantly decreased expression of DCD in HS skin, we hypothesised that the identified frameshift insertion was a loss-of-function mutation that might be associated with HS susceptibility in this family. We thus confirmed by mass spectrometry that DCD levels were diminished in the affected members and showed that the antimicrobial activity of a synthetic DCD peptide resulting from the frameshift mutation was impaired. In order to define the consequences related to a decrease in DCD activity, skin microbiome analyses of different body sites were performed by comparing DCD mutant and wild type samples, and results highlighted significant differences between the groins of mutated and wild type groups. Starting from genetic analysis conducted on an HS family, our findings showed, confirming previous transcriptome results, the potential role of the antimicrobial DCD peptide as an actor playing a crucial part in the etio-pathogenesis of HS and in the maintenance of the skin's physiological microbiome composition; so, we can hypothesise that DCD could be used as a novel target for personalised therapeutic approach.

Serum high-sensitivity C-reactive protein, tumor necrosis factor-α, interleukin (IL)-1ß, IL-17A and IL-23 levels in patients with hidradenitis suppurativa.

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic, recurrent inflammatory skin disease that leads to scar formation. The immune pathogenesis of HS is not fully understood and inhibitors of tumor necrosis factor (TNF)-α, interleukin (IL)-17, IL-1, IL-23 can be used for treating HS. Identification of serum biomarkers may help understanding individual differences in HS pathogenesis, evaluating disease severity and developing more effective treatment methods. OBJECTIVES: To assess the serum levels of proinflammatory cytokines TNF-α, IL-1ß, IL-17A, IL-23 and high-sensitivity C-reactive protein (hs-CRP) in patients with HS and to evaluate the impact of treatment on cytokine levels. METHODS: Serum proinflammatory cytokine and hs-CRP levels were measured using enzyme-linked immunosorbent assay kits in 24 healthy controls and in 26 HS patients at baseline and after a 3-month treatment. Patients were treated with clindamycin, adalimumab, dapsone, doxycycline and acitretin, based on HS condition and laboratory results. Control, pre-treatment and post-treatment values were compared. RESULTS: HS patients had significantly higher hs-CRP levels than controls which decreased following treatment (p = 0,010, p = 0,007). No significant difference was found in serum levels of TNF-α, IL-1ß, IL-17A, IL-23 compared to controls and post-treatment levels. CONCLUSIONS: There is insufficient data to suggest TNF-α, IL-1ß, IL-17A and IL-23 as serum biomarkers in HS. hs-CRP can be used as an indicator of treatment response and systemic inflammation.

What causes hidradenitis suppurativa ?-15 years after.

The 14 authors of the first review article on hidradenitis suppurativa (HS) pathogenesis published 2008 in EXPERIMENTAL DERMATOLOGY cumulating from the 1st International Hidradenitis Suppurativa Research Symposium held March 30-April 2, 2006 in Dessau, Germany with 33 participants were prophetic when they wrote "Hopefully, this heralds a welcome new tradition: to get to the molecular heart of HS pathogenesis, which can only be achieved by a renaissance of solid basic HS research, as the key to developing more effective HS therapy." (Kurzen et al. What causes hidradenitis suppurativa? Exp Dermatol 2008;17:455). Fifteen years later, there is no doubt that the desired renaissance of solid basic HS research is progressing with rapid steps and that HS has developed deep roots among inflammatory diseases in Dermatology and beyond, recognized as "the only inflammatory skin disease than can be healed". This anniversary article of 43 research-performing authors from all around the globe in the official journal of the European Hidradenitis Suppurativa Foundation e.V. (EHSF e.V.) and the Hidradenitis Suppurativa Foundation, Inc (HSF USA) summarizes the evidence of the intense HS clinical and experimental research during the last 15 years in all aspects of the disease and provides information of the developments to come in the near future.

The role of hypothalamus-pituitary-adrenal (HPA)-like axis in inflammatory pilosebaceous disorders.

Skin is the largest peripheral endocrine organ and functions as a hormone target and endocrine gland. A cutaneous hypothalamus-pituitary-adrenal (HPA)-like axis enables the skin to respond to stress and regulates its steroidogenic activity. The pilosebaceous unit is a site for production and metabolism of a number of steroid hormones, including stress and sex hormones. This is an overview of the important role that the cutaneous HPA-like-axis plays in the pathogenesis and treatment of inflammatory pilosebaceous disorders, including acne, rosacea, seborrheic dermatitis, and hidradenitis suppurativa.

Essential requirement for nicastrin in marginal zone and B-1 B cell development.

γ-secretase is an intramembrane protease complex that catalyzes the proteolytic cleavage of amyloid precursor protein and Notch. Impaired γ-secretase function is associated with the development of Alzheimer's disease and familial acne inversa in humans. In a forward genetic screen of mice with N-ethyl-N-nitrosourea-induced mutations for defects in adaptive immunity, we identified animals within a single pedigree exhibiting both hypopigmentation of the fur and diminished T cell-independent (TI) antibody responses. The causative mutation was in Ncstn, an essential gene encoding the protein nicastrin (NCSTN), a member of the γ-secretase complex that functions to recruit substrates for proteolysis. The missense mutation severely limits the glycosylation of NCSTN to its mature form and impairs the integrity of the γ-secretase complex as well as its catalytic activity toward its substrate Notch, a critical regulator of B cell and T cell development. Strikingly, however, this missense mutation affects B cell development but not thymocyte or T cell development. The Ncstn allele uncovered in these studies reveals an essential requirement for NCSTN during the type 2 transitional-marginal zone precursor stage and peritoneal B-1 B cell development, the TI antibody response, fur pigmentation, and intestinal homeostasis in mice.

Hidradenitis Suppurativa and Thyroid Disease: Systematic Review and Meta-Analysis.

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic inflammatory disease characterized by painful nodules, sinus tracts, and significant scarring. Although the pathogenesis of this disease is not well established, there is increasing evidence to suggest that it is an immune-mediated disorder. Previous studies have suggested a relationship between HS and thyroid disease, which is also driven by an autoimmune process. We sought to assess whether an association exists between HS and thyroid disease. OBJECTIVES: To determine whether HS is associated with thyroid disease via meta-analysis of case-control studies. METHODS: A systematic review and meta-analysis was performed according to recommended PRISMA guidelines. Electronic searches were performed using 6 electronic databases from their inception until August 2018. Data were extracted and analyzed according to predefined clinical endpoints. Odds ratio (OR) was used as the summary effect size. RESULTS: We identified 5 case-controls studies included for meta-analysis. There were a total of 36 103 HS cases compared with 170 517 control cases. We found a significant association between HS and thyroid disease (OR 1.36, 95% CI 1.13-1.64, I 2 = 78%, P = .001). CONCLUSIONS: This pooled analysis of existing case-control studies to date supports an association between HS and any thyroid disease. Clinicians treating patients with HS should be aware of this potential association with thyroid disease.

Circulating levels of adiponectin, leptin, resistin and visfatin in non-diabetics patients with hidradenitis suppurativa.

Hidradenitis suppurativa (HS) is a chronic inflammatory disease associated with insulin resistance (IR), metabolic syndrome and increased cardiovascular risk. Adipokines are biologically active, pleotropic molecules which have been involved in the development of IR and in the pathogenesis of several chronic inflammatory conditions. The aim of the present study was to analyze serum concentrations of adiponectin, leptin, resistin and visfatin in patients with HS, and investigate their possible associations with IR, HS risk and disease severity. This case-control study enrolled 137 non-diabetic individuals (76 HS-patients and 61 age and sex-matched controls). Serum concentrations of adiponectin, leptin, resistin and visfatin, and the homeostasis model assessment of IR (HOMA-IR) were measured in all the participants. Serum adiponectin concentrations were found to be significantly lower, and leptin, resistin and visfatin levels were significantly higher in HS-patients than in controls. These differences remained significant even after adjusting for age, sex and body mass index, except for leptin. In a multivariate regression analysis, HOMA-IR was inversely correlated with adiponectin and positively associated with resistin levels. Furthermore, serum levels of resistin and visfatin were independently associated with HS risk. However, we found no association between serum levels of adipokines and HS severity. Our results suggest that reduced adiponectin and increased resistin serum levels may be surrogate biomarkers for IR in patients with HS. Moreover, resistin and visfatin might be independent risk factors for the development of HS.

Integrating complement into the molecular pathogenesis of Hidradenitis Suppurativa.

Complement inhibition has been identified as a potential therapeutic target for multiple inflammatory disorders including Hidradenitis Suppurativa (HS). It is currently unclear how complement integrates into our current model of molecular pathogenesis in HS and whether it represents a central component of pathogenesis, or a neutrophil-associated bystander. Levels of C5a in serum and tissue correlate with disease activity and degree of neutrophilic infiltrates in HS. C5a has been associated with Th17 immune axis activation in psoriasis, rheumatoid arthritis and Crohn's disease with strong similarities to TH17 activation in HS. Porphyromonas species (which are identified in the HS microbiome) are able to cleave inactive C5 into C5a implicating the cutaneous microbiome as an activator of complement. C3a and C5a are associated with activation of the NLRP3 inflammasome, implicated in the inflammatory drive in HS. Complement receptors are present upon dendritic cells, monocytes, fibroblasts and adipocytes, which may broaden the potential contribution of complement to multiple aspects of HS pathogenesis. Dysregulation of complement receptor pathways has been documented in obesity, insulin resistance and polycystic ovarian syndrome leading to the possibility that complement may explain the epidemiological associations between these conditions and HS. The therapeutic potential of complement inhibitors in HS may be related to the therapeutic target (complement receptor or complement subunit) and the presence of alternate receptors (such as C5aR2) or ligands (including C3a, PAMPs and DAMPs). Integrating complement into the known pathogenesis of HS may aid in explaining the contradictory results between Phase 2 studies of C5a antagonists. It also allows for the identification of existing knowledge gaps to target further clinical investigation and research.

Transcriptome patterns in hidradenitis suppurativa: support for the role of antimicrobial peptides and interferon pathways in disease pathogenesis.

BACKGROUND: Hidradenitis suppurativa (HS) is a recurrent inflammatory disease of the apocrine sweat glands. Immune dysregulation probably contributes to the pathogenesis of HS. AIM: To harness mRNA expression arrays to investigate the transcriptome profile in HS compared with control skin. METHODS: Illumina® HumanHT-12 v4 Expression BeadChips were used to measure mRNA expression in skin samples from HS (n = 10) and abdominoplasty (n = 11) skin specimens. Differentially expressed genes were detected by fitting genewise linear models to the normalized expression data and then modelling using the web-based software Ingenuity® Pathway Analysis. RESULTS: The antimicrobial peptide Dermcidin and the cytokine regulator interleukin (IL)-37 were both significantly downregulated in the HS specimens (Dermcidin expression log ratio -3.93, expression P = 0.04; IL-37 expression log ratio -3.29, expression P < 0.001). Pathway analysis revealed the interferon-signalling pathway, leucocyte extravasation pathway, T helper 1 and 2 pathways and nuclear factor of activated T cells as the top-five upregulated pathways in the HS samples. CONCLUSION: Evaluation of transcriptome patterns in HS compared with normal skin demonstrated downregulation of the antimicrobial peptide Dermcidin and the innate immune regulator IL-37, as well as upregulation of interferon pathways and pathways of leucocyte activation.

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-1ß concentration was observed in all skin samples after 4 days of culture, although IL-1ß 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.

Nicastrin/miR-30a-3p/RAB31 Axis Regulates Keratinocyte Differentiation by Impairing EGFR Signaling in Familial Acne Inversa.

Nicastrin (NCSTN) mutations are associated with familial acne inversa (AI), and emerging evidence suggests that microRNAs (miRNAs) are involved in various skin diseases. However, whether NCSTN mutations affect miRNA levels and their subsequent signaling pathways in familial AI patients has not been studied. We aimed to elucidate the relationship between NCSTN mutations and familial AI pathogenesis by investigating differential miRNA expression and their related pathways. Combined with miRNA microarray data from familial AI patients, Ncstn keratinocyte-specific-knockout (NcstnΔKC) mice and bioinformatics predictions showed that NCSTN mutations led to decreased miR-30a-3p levels, which negatively regulated RAB31 expression. Moreover, enhanced RAB31 levels accelerated degradation of activated EGFR, leading to abnormal differentiation in keratinocytes. The impaired EGFR signaling and its effects on epidermal differentiation were also observed in familial AI patients and NcstnΔKC mice. Thus, our study showed that miR-30a-3p/RAB31/EGFR signaling pathway may play a key role in the pathogenesis of familial AI with NCSTN mutations.

Apremilast for moderate hidradenitis suppurativa: no significant change in lesional skin inflammatory biomarkers.

BACKGROUND: Treatment with apremilast has recently demonstrated clinically meaningful improvement in moderate hidradenitis suppurativa (HS). OBJECTIVE: To evaluate the change in expression of inflammatory markers in lesional skin of HS patients receiving apremilast 30 mg twice daily (n = 15) for 16 weeks compared with placebo (n = 5). METHODS: At baseline, 5-mm punch biopsies were obtained from an index lesion (HSL) and non-lesional (HSN) skin in the same anatomical area. Subsequent HSL samples were taken as close as possible to the previously biopsied site at week 4 and week 16. After sampling, biopsies were split; one half was processed for in vivo mRNA analysis using real-time quantitative PCR; the other half was cultured for ex vivo protein analysis using a proximity extension assay (Olink). Linear mixed effects models were calculated to compare the levels of inflammatory markers in HSL skin between apremilast and placebo over time. RESULTS: At baseline, 17 proteins with a fold change >2 in HSL vs. HSN skin were identified in 20 patients. The top five were IL-17A (5), S100A12, CST5, IL-12/23p40, CD6 (1) with fold changes ranging from 6.6 to 1638, respectively (FDR <0.044). Linear mixed effects models for 75 assays were calculated. Protein levels of S100A12 decreased during treatment in the apremilast group compared with the placebo group (p = 0.014, FDR = 0.186). None of the 14 genes exhibited significant changes in expression over time. However, an evident downward trend in relative mRNA expression of IL-17A and IL-17F was demonstrated in patients receiving apremilast. CONCLUSION: We did not detect statistically significant changes in inflammatory markers in HSL skin of HS patients receiving apremilast compared with placebo, despite clinical improvement in the apremilast group. Nonetheless, S100A12 and IL-17A were significantly elevated in HSL skin and showed a decrease in response to apremilast. The translational model in clinical trials involving HS clearly needs further improvement.

Reduced ten-eleven translocation and isocitrate dehydrogenase expression in inflammatory hidradenitis suppurativa lesions.

BACKGROUND: As environmental factors appear to predispose patients to hidradenitis suppurativa (HS), studying epigenetic modifications is of interest to further understand the pathogenesis of HS. OBJECTIVES: To study the expression of DNA hydroxymethylation regulators, namely the ten-eleven translocation (TET) and isocitrate dehydrogenase (IDH) family, in the skin of HS patients. MATERIALS & METHODS: Twenty patients with HS and 12 healthy subjects were recruited. We analysed the expression of TET1, TET2, TET3, IDH1, IDH2, IDH3a, and IDH3b in lesional and perilesional HS tissue as well as tissue from healthy controls by quantitative real-time reverse transcription polymerase chain reaction (RT-PCR). In addition, immunohistochemistry was performed for TET1, TET2, and TET3. RESULTS: RT-PCR analysis showed that mRNA of all the studied genes was significantly under-expressed in lesional HS skin compared to healthy skin. IDH1 and IDH2 mRNA expression was also significantly lower in perilesional HS skin compared to healthy skin, and TET3 mRNA expression was significantly lower in lesional HS skin compared to perilesional HS skin. RT-PCR analysis for TET1, TET2, and TET3 mRNA expression was confirmed by immunohistochemical analysis. Correlation analysis revealed a significant positive correlation between TET and IDH gene expression in perilesional and lesional HS skin. CONCLUSIONS: Our results suggest that epigenetic changes occur in HS tissue and that aberrant expression of the DNA hydroxymethylation regulators may play a role in the pathogenesis of HS. As epigenetic modifications are reversible, further research into the cause of these aberrant expression patterns is warranted in order to develop possible novel therapeutic approaches.

Thyroid function in hidradenitis suppurativa: a population-based cross-sectional study from Denmark.

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic inflammatory disease. Numerous studies have associated HS with obesity, and recently with metabolic syndrome (MetS). Both obesity and MetS are linked with metabolic changes. Thyroid hormones play a central role in metabolism and exert pleiotropic effects on adipogenesis and the basal metabolism of lipids and glucose. We hypothesized that patients with HS have an altered or dysfunctional metabolism expressed as thyroid function. AIM: To investigate thyroid function in individuals with HS compared with healthy controls (HCs). METHODS: We conducted a retrospective comparative cross-sectional study using blood samples and questionnaire-based self-reported information to assess thyroid function. RESULTS: Our study comprised 430 patients in a population-based HS group, and 20 780 HCs. The age/sex-adjusted analysis showed a significantly lower level (P < 0.001) of thyroid-stimulating hormone (TSH) and a significantly higher level (P < 0.0001) of total triiodothyronine (tT3) for the HS compared with the HC group. The age/sex-adjusted analysis also showed a significant association between clinical hyperthyroidism and HS (an OR = 1.91, 95% CI 1.19-3.07; P = 0.02). When this analysis was adjusted further for the potential confounders of body mass index, smoking and oral contraception, the results remained significant. CONCLUSION: This study suggests that HS is associated with hyperthyroidism. Hyperthyroidism may indicate an altered or dysfunctional metabolism.

Association of Hidradenitis Suppurativa With T Helper 1/T Helper 17 Phenotypes: A Semantic Map Analysis.

Importance: In spite of progress in understanding the mechanisms underlying hidradenitis suppurativa (HS) as an inflammatory skin disease, there is still a demand for an overview on immunopathogenesis of HS. Objective: To demonstrate the importance of the type 1/type 17 immune response in lesional HS skin by drawing a semantic connectivity map. Design, Setting, and Participants: Single-center case series of 24 patients with HS. Association of HS with T helper 1/T helper 17 (TH1/TH17) phenotype was assessed using semantic map analysis. Main Outcomes and Measures: Association of HS with TH1/TH17 phenotype. Results: The analysis was performed on 24 lesional HS biopsy samples from untreated patients with HS (16 [67%] female; median age, 36.5 years [range, 21-51 years]) with a mean (SD) Hurley stage of 2.29 (0.62) and 9 punch biopsy samples from healthy controls (6 [67%] female; median age, 43 years [range, 23-66 years]). The map shows a clustering of all TH1/TH17-associated cytokines (interleukin 17 [IL-17], interferon γ, IL-12, IL-23, IL-32, IL-1ß, tumor necrosis factor) around overall lesional inflammation. Tumor necrosis factor, IL-12, and IL-17 are even directly connected via interferon γ. In contrast, IL-13, a TH2-associated cytokine, was inversely correlated with the presence of TH1/TH17-associated cytokines, further highlighting the importance of the TH1/TH17 cytokines in HS pathogenesis. Conclusions and Relevance: These findings suggest that HS may be a TH1/TH17-driven inflammatory skin disease.