Increased expression profile of NCSTN, Notch and PI3K/AKT3 in hidradenitis suppurativa

A state-of-the-art systematic review of cancer in hidradenitis suppurativa

PURPOSE

Hidradenitis suppurativa (HS) is a chronic inflammatory disease associated with an increased risk of malignancy. The aim of this systematic review was to investigate the prevalence of different malignancies in HS.

METHODS

This review meets the PRISMA criteria. A data-driven approach was used to conduct the research, which involved a detailed keyword search. The study considered meta-analyses, experimental studies, case-control studies, cross-sectional studies, cohort studies, and recently published cases, published in English or German. Excluded were reviews, summaries, and letters to the editor, as well as studies, which are not based on the human population.

RESULTS

Out of the initial 443 publications found, 25 met the inclusion criteria for this systematic review. Patients with HS have a significantly increased risk of cancer, up to 50%. Additionally, the risk of oropharyngeal, central nervous system, colorectal, prostate, vulvar and non-melanocytic skin cancers increase with the severity of HS. The likelihood of comorbid lymphoma in patients with HS is significantly higher compared to healthy controls. In severe cases of HS, malignant degeneration of lesions in the groin, perianal, perineal, and gluteal region can occur in up to 4.6% of cases. This leads to the development of cSCC, which often have a complicated course, are more refractory to treatment and associated with a poorer outcome. The pathogenic mechanisms responsible for the malignant transformation of HS are currently unknown.

CONCLUSIONS

Patients with HS have a higher risk of cancer compared to the general population. Untreated, long-standing HS lesions can lead to complicated malignant degeneration resulting in cutaneous squamous cell carcinoma. The mechanisms underlying this malignant degeneration are not fully understood. HS patients also have an increased risk of developing other cancers, including prostate, oral, pharyngeal and colorectal cancers of the central nervous system and lymphomas.

Comprehensive Catalog of Variants Potentially Associated with Hidradenitis Suppurativa, Including Newly Identified Variants from a Cohort of 100 Patients

Hidradenitis suppurativa (HS) is a chronic skin disease characterized by painful, recurrent abscesses, nodules, and scarring, primarily in skin folds. The exact causes of HS are multifactorial, involving genetic, hormonal, and environmental factors. It is associated with systemic diseases such as metabolic syndrome and inflammatory bowel disease. Genetic studies have identified mutations in the γ-secretase complex that affect Notch signaling pathways critical for skin cell regulation. Despite its high heritability, most reported HS cases do not follow a simple genetic pattern. In this article, we performed whole-exome sequencing (WES) on a cohort of 100 individuals with HS, and we provide a comprehensive review of the variants known to be described or associated with HS. 91 variants were associated with the γ-secretase complex, and 78 variants were associated with other genes involved in the Notch pathway, keratinization, or immune response. Through this new genetic analysis, we have added ten new variants to the existing catalogs. All variants are available in a .vcf file and are provided as a resource for future studies.

Neutrophil extracellular traps activate Notch-γ-secretase signaling in hidradenitis suppurativa

BACKGROUND

Hidradenitis suppurativa (HS) is an inflammatory chronic skin disorder of unknown etiology characterized by inflamed abscess-like nodules and boils resulting in sinus tract formation, tissue scarring, and massive infiltration of neutrophils. Multiple lines of evidence have highlighted the potential association between alterations in the Notch pathway and HS pathogenesis, but the mechanisms remain incompletely characterized.

OBJECTIVE

We aimed to elucidate the role of neutrophil extracellular traps in Notch-γ-secretase signaling.

METHODS

Twenty-six HS lesional tissues, primary HS macrophages, and skin fibroblasts were interrogated by quantitative PCR, Western blot, and ELISA analyses. γ-Secretase and TNF-α converting enzyme activities were measured in HS skin lesions, macrophages, and skin fibroblasts. Immunofluorescence and RNAscope analyses were performed in HS and control skin.

RESULTS

A prominent presence of Notch ligands, Delta-like ligand 4 (DLL4), and Jagged (JAG) 2 were detected at the protein and mRNA levels in HS skin lesion compared to control. Levels of DLL4, JAG1, citrullinated histone H3 DNA, and γ-secretase activity correlated with HS disease severity. Additionally, significantly elevated levels of Notch ligands and γ-secretase activity were found in dissected sinus tracts compared to the rest of HS tissue. Immunofluorescence microscopy of HS skin lesions revealed activation of Notch-1 signaling in macrophages and skin fibroblasts. Neutrophil extracellular traps (NETs) purified from HS patients displayed elevated levels of DLL4. HS NETs activated the Notch pathway in macrophages and dermal fibroblasts isolated from HS patients. HS skin fibroblasts displayed elevated levels of CD90 and DPP4 in association with increased migratory capacity and Notch activation. Inhibition of Notch decreased migratory capacity and profibrotic markers in HS fibroblasts.

CONCLUSION

These data support a pathogenic connection between NETs, Notch-γ-secretase activation, and the release of profibrotic molecules that promote dysregulation of macrophages and skin fibroblasts in HS. Unveiling the relevance of these molecular events not only expands our understanding of HS but also opens new venues for the development of targeted therapies to address the fibrotic complications of advanced stages of HS.

[Hidradenitis suppurativa]

Hidradenitis suppurativa (HS) is a chronic inflammatory skin and systemic disease that is associated with considerable discomfort and a significant reduction in the quality of life. Despite a significantly increased understanding of the disease, the diagnosis is still delayed for many years. Delayed patient access to suitable treatment often leads to disease progression with increased surgical interventions and the occurrence of possible comorbidities. In recent years, there has been an improved understanding of the pathophysiology and, as a result the authorization of modern therapeutic agents for HS. The treatment of HS is based on three treatment pillars: surgery, antibiotics and biologics. Additionally, risk factors, such as smoking and obesity should be positively influenced. Knowledge of comorbidities and their interdisciplinary treatment is important for the individualized care of patients.

Detection of native, activated Notch receptors in normal human apocrine-bearing skin and in hidradenitis suppurativa

Notch signalling has generated considerable interest as a pathogenetic factor and a drug target in a range of human diseases. The gamma-secretase complex is crucial in the activation of Notch receptors by cleaving the intracellular domain allowing nuclear translocation. In recent years several mutations in gamma-secretase components have been discovered in patients with familial hidradenitis suppurativa (HS). This has led to hypotheses that impaired Notch signalling could be an important driver for HS in general, not only in the monogenic variants. However, no study has examined in situ Notch activation per se in HS, and some reports with conflicting results have instead been based on expression of Notch receptors or indirect measures of Notch target gene expression. In this study we established immunostaining protocols to identify native, activated Notch receptors in human skin tissue. The ability to detect changes in Notch activation was confirmed with an ex vivo skin organ model in which signal was reduced or obliterated in tissue exposed to a gamma-secretase inhibitor. Using these methods on skin biopsies from healthy volunteers and a general HS cohort we demonstrated for the first time the distribution of active Notch signalling in human apocrine-bearing skin. Quantification of activated NOTCH1 & NOTCH2 revealed similar levels in non-lesional and peri-lesional HS to that of healthy controls, thus ruling out a general defect in Notch activation in HS patients. We did find a variable but significant reduction of activated Notch in epidermis of lesional HS with a distribution that appeared related to the extent of surrounding tissue inflammation.

Overexpression of hypoxia-inducible factor-1α in hidradenitis suppurativa: the link between deviated immunity and metabolism

Hypoxia-inducible factor-1α (HIF-1α) is the master transcription factor of glycolysis, Th17 cell differentiation and suppression of regulatory T cells. In the skin and serum of patients with psoriasis vulgaris, increased expression of HIF-1α has been reported, whereas HIF-1α expression in the skin and serum of patients with hidradenitis suppurativa (HS) has not yet been studied. The objective of the study is to demonstrate is there a role for HIF-1α in the pathogenesis of hidradenitis suppurativa, and its relation to HS severity. Twenty patients suffering from hidradenitis suppurativa were included in the study. Punch biopsies were taken from lesional skin for the determination of HIF-1α expression by immunohistochemical staining, and HIF-1α gene expression by quantitative reverse transcription real time PCR. Quantification of HIF-1α protein concentration was done by enzyme-linked immunosorbent assay. Twenty socio-demographically cross-matched healthy volunteers served as controls. We found increased serum levels of HIF-1α. Literature-derived evidence indicates that the major clinical triggering factors of HS, obesity, and smoking are associated with hypoxia and enhanced HIF-1α expression. Pro-inflammatory cytokines such as tumor necrosis factor-[Formula: see text] via upregulation of nuclear factor [Formula: see text]B enhance HIF-1α expression. HIF-1α plays an important role for keratinocyte proliferation, especially for keratinocytes of the anagen hair follicle, which requires abundant glycolysis providing sufficient precursors molecules for biosynthetic pathways. Metformin via inhibition of mTORC1 as well as adalimumab attenuate HIF-1α expression, the key mediator between Th17-driven deviated immunity and keratinocyte hyperproliferation. In accordance with psoriasis, our study identifies HS as an HIF-1α-driven inflammatory skin disease and offers a new rationale for the prevention and treatment of HS by targeting HIF-1[Formula: see text] overexpression.

The genetic aspects of hidradenitis suppurativa

Genetic aspects have a substantial role in hidradenitis suppurativa (HS) pathogenesis. A positive family history of HS occurs in about one-third of HS cases and is significantly higher in patients with early onset of the disease. Recent twin studies have shown a high heritability in HS, fortifying the importance of genetic factors in disease pathogenesis. Based on existing knowledge on the genomics of HS, the disease can be categorized as familial HS, sporadic, syndromic HS, and "HS plus" associated with other syndromes. In familial HS, autosomal dominant transmission is proposed, and monogenic inheritance is rare. This monogenic trait is related to mutations of γ-secretase component genes and Notch signaling or defects in inflammasome function. With newly discovered gene mutations, such as those related to innate and adaptive immunity, skin microbiome, inflammasome, epidermal homeostasis, and keratinization pathway, we can define HS as a polygenic, multifactorial, autoinflammatory disease. To fully elucidate the genetic aspects of HS, we need extensive, long-term global collaborations.

Identification and verification of diagnostic biomarkers in recurrent pregnancy loss via machine learning algorithm and WGCNA

Background

Recurrent pregnancy loss defined as the occurrence of two or more pregnancy losses before 20-24 weeks of gestation, is a prevalent and significant pathological condition that impacts human reproductive health. However, the underlying mechanism of RPL remains unclear. This study aimed to investigate the biomarkers and molecular mechanisms associated with RPL and explore novel treatment strategies for clinical applications.

Methods

The GEO database was utilized to retrieve the RPL gene expression profile GSE165004. This profile underwent differential expression analysis, WGCNA, functional enrichment, and subsequent analysis of RPL gene expression using LASSO regression, SVM-RFE, and RandomForest algorithms for hub gene screening. ANN model were constructed to assess the performance of hub genes in the dataset. The expression of hub genes in both the RPL and control group samples was validated using RT-qPCR. The immune cell infiltration level of RPL was assessed using CIBERSORT. Additionally, pan-cancer analysis was conducted using Sangerbox, and small-molecule drug screening was performed using CMap.

Results

A total of 352 DEGs were identified, including 198 up-regulated genes and 154 down-regulated genes. Enrichment analysis indicated that the DEGs were primarily associated with Fc gamma R-mediated phagocytosis, the Fc epsilon RI signaling pathway, and various metabolism-related pathways. The turquoise module, which showed the highest relevance to clinical symptoms based on WGCNA results, contained 104 DEGs. Three hub genes, WBP11, ACTR2, and NCSTN, were identified using machine learning algorithms. ROC curves demonstrated a strong diagnostic value when the three hub genes were combined. RT-qPCR confirmed the low expression of WBP11 and ACTR2 in RPL, whereas NCSTN exhibited high expression. The immune cell infiltration analysis results indicated an imbalance of macrophages in RPL. Meanwhile, these three hub genes exhibited aberrant expression in multiple malignancies and were associated with a poor prognosis. Furthermore, we identified several small-molecule drugs.

Conclusion

This study identifies and validates hub genes in RPL, which may lead to significant advancements in understanding the molecular mechanisms and treatment strategies for this condition.

Inborn Errors of Immunity in Hidradenitis Suppurativa Pathogenesis and Disease Burden

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

Mechanism underlying follicular hyperproliferation and oncogenesis in hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a skin disorder that causes chronic painful inflammation and hyperproliferation, often with the comorbidity of invasive keratoacanthoma (KA). Our research, employing high-resolution immunofluorescence and data science approaches together with confirmatory molecular analysis, has identified that the 5'-cap-dependent protein translation regulatory complex eIF4F is a key factor in the development of HS and is responsible for regulating follicular hyperproliferation. Specifically, eIF4F translational targets, Cyclin D1 and c-MYC, orchestrate the development of HS-associated KA. Although eIF4F and p-eIF4E are contiguous throughout HS lesions, Cyclin D1 and c-MYC have unique spatial localization and functions. The keratin-filled crater of KA is formed by nuclear c-MYC-induced differentiation of epithelial cells, whereas the co-localization of c-MYC and Cyclin D1 provides oncogenic transformation by activating RAS, PI3K, and ERK pathways. In sum, we have revealed a novel mechanism underlying HS pathogenesis of follicular hyperproliferation and the development of HS-associated invasive KA.

miR-27a Targeting PIK3R3 Regulates the Proliferation and Apoptosis of Sheep Hair Follicle Stem Cells

Micro RNAs are regulatory factors in tissue development, organ formation, cell growth, apoptosis and other biological processes. In particular, several miRNAs are related to the development of hair follicles. Here, we investigated the effect of the targeting of PIK3R3 by miR-27a on the AKT/MTOR pathway and on the proliferation and apoptosis of hair follicle stem cells (HFSCs) in sheep. Knockdown of the expression of PIK3R3 was found to significantly inhibit the proliferation and promote the apoptosis of HFSCs. Similarly, a miR-27a mimic significantly inhibited the proliferation and promoted the apoptosis of HFSCs. The miR-27a mimic was also shown to significantly inhibit the expression of PIK3R3, AKT, and MTOR and the phosphorylation of AKT and MTOR, while a miR-27a inhibitor increased the expression of these genes. The presence of an miR-27a binding site in the 3' UTR of PIK3R3 was identified by a bioinformatics analysis, and the interaction was verified with a dual-luciferase reporter assay. The expression of PIK3R3 mRNA and protein was negatively correlated with the presence of miR-27a, which suggests that this interaction may be involved in the biological impacts on proliferation and apoptosis. Thus, this study demonstrates that miR-27a plays a potential role in the proliferation and apoptosis of sheep hair follicle stem cells by targeting PIK3R3, which can be used to design new methods to improve sheep wool.

Advances in pathogenesis and nanoparticles (NPs)-mediated treatment of psoriasis

Psoriasis is a chronic papulosquamous skin disease with an autoimmune pathogenic traits and strong genetic predisposition. In the past few decades, with the rapid development of molecular biology and cell biology, the inherent pathogenesis of psoriasis has been gradually elucidated, in which cytokine inflammatory loops, cell signaling pathways, and epigenetic factors such as miRNAs have been demonstrated to play important roles in regulating the development and progression of psoriasis. More importantly, understanding the pathogenesis of psoriasis has promoted the development of effective treatment for psoriasis. In this review, we systemically summarized the molecular mechanisms regulating the development and progression psoriasis, introduced various therapeutics used for clinical psoriasis therapy, and highlighted the recent advances in nanoparticles (NPs)-mediated drug delivery for psoriasis treatment.

Sex-disaggregated population analysis in patients with hidradenitis suppurativa

BACKGROUND

Hidradenitis suppurativa (HS) is a common chronic inflammatory skin disease, which affects both sexes.

OBJECTIVES

Identification of sex-specific risk factors, comorbidity, clinical manifestations, and treatments in HS patients.

METHODS

A non-interventional, cross-sectional, mono-centric study with 500 HS patients. All patients were examined by dermatologists. Prospectively collected demographic, anamnestic, clinical data, and blood parameters were evaluated.

RESULTS

There were no significant differences in age at HS onset and in disease duration between female and male patients. Furthermore, no differences regarding the family history for HS were found between sexes. Regarding further risk factors for HS, central obesity was more frequent in women while extensive cigarette smoking and acne vulgaris were more commonly found among male patients. Regarding comorbidity, lower HDL-levels were significantly more frequent in men. Female patients were found to suffer significantly more often from back pain, especially in the neck/shoulder region and lower back. Analyzing the clinical manifestation of HS, the groin was more frequently involved in women and the axillae in men. Women showed a higher number of skin sites with inflammatory nodules, whereas fistulas were observed more frequently in men. Nevertheless, there was no difference in HS treatment applied to female vs. male patients.

LIMITATIONS

Data were obtained from a mono-centric study.

CONCLUSION

Significant differences in HS risk factors, comorbidity, and clinical manifestation exist between female and male patients. Thus, sex-specific differences should be taken into account in the prevention as well as medical and surgical treatment of HS patients.

Hidradenitis Suppurativa: A Perspective on Genetic Factors Involved in the Disease

Hidradenitis Suppurativa (HS) is a chronic inflammatory skin disease of the pilosebaceous unit, clinically consisting of painful nodules, abscesses, and sinus tracts mostly in, but not limited to, intertriginous skin areas. HS can be defined as a complex skin disease with multifactorial etiologies, including—among others—genetic, immunologic, epigenetic, and environmental factors. Based on genetic heterogeneity and complexity, three different forms can be recognized and considered separately as sporadic, familial, and syndromic. To date, several genetic variants associated to disease susceptibility, disease-onset, and/or treatment response have been reported; some of these reside in genes encoding the gamma-secretase subunits whereas others involve autoinflammatory and/or keratinization genes. The aim of this perspective work is to provide an overview of the contribution of several genetic studies encompassing family linkage analyses, target candidate gene studies, and -omic studies in this field. In our viewpoint, we discuss the role of genetics in Hidradenitis suppurativa considering findings based on Sanger sequencing as well as the more recent Next Generation Sequencing (i.e., exome sequencing or RNA Sequencing) with the aim of better understanding the etio-pathogenesis of the disease as well as identifying novel therapeutic strategies.

A Novel NCSTN Mutation in a Three-Generation Chinese Family with Hidradenitis Suppurative

Objective

Hidradenitis suppurativa (HS) is a rare autosomal dominant condition characterized by inflamed nodules, cysts, deep abscesses, draining sinuses in the axillae, inguinal, and anogenital regions. Mutations in the NCSTN gene have been perceived to be responsible for the major underlying changes in the disorder. The purpose of this study is to identify a novel gene mutation in a Chinese family with HS.

Methods

A Chinese family with HS present was investigated. The proband had manifested with multiple draining sinuses on the posterior neck, chest, bilateral axillae, and perineal regions. DNA was isolated from the peripheral blood of the family members. The encoding exons with introns of the NCSTN gene were analyzed by polymerase chain reactions (PCR) and direct DNA sequencing. Sanger sequencing was performed to confirm the next-generation sequencing results and to analyze each mutation's familial segregation. Furthermore, the identified mutation was localized onto a 3D structure model using the DeepView Swiss-PdbViewer 4.1 software.

Results

In this family comprising 10 HS patients, one novel mutation of the NCSTN gene was identified, involving a deletion mutation (c.447delC(p.N150Ifs∗52)) in the NCSTN gene resulting in a frameshift and the new formation of a hydrogen bond.

Conclusion

Our study reports the identification of a novel mutation that causes familial HS and could expand the spectrum of mutations in the γ-secretase genes underlying HS.

The Genomic Architecture of Hidradenitis Suppurativa-A Systematic Review

Hidradenitis suppurativa is a chronic, suppurative condition of the pilosebaceous unit manifesting as painful nodules, abscesses, and sinus tracts mostly in, but not limited to, intertriginous skin. Great strides have been made at elucidating the pathophysiology of hidradenitis suppurativa, which appears to be the product of hyperkeratinization and inflammation brought about by environmental factors and a genetic predisposition. The identification of familial hidradenitis suppurativa has sparked research aimed at identifying underlying pathogenic variants in patients who harbor them. The objective of this review is to provide a broad overview of the role of genetics in various aspects of hidradenitis suppurativa, specifically the pathophysiology, diagnosis, and clinical application.

Mechanism of anti-inflammatory effects of Rifampicin in an ex vivo culture system of Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease of the hair follicles leading to painful lesions, associated with increased levels of pro-inflammatory cytokines. Numerous guidelines recommend antibiotics like clindamycin and rifampicin in combination, as first-line systemic therapy in moderate to severe forms of inflammation. HS has been proposed to be mainly an auto-inflammatory disease associated with but not initially provoked by bacteria. Therefore, it has to be assumed that the pro-inflammatory milieu previously observed in HS skin is not solely dampened by the bacteriostatic inhibition of DNA-dependent RNA polymerase. To further clarify the mechanism of anti-inflammatory effects of rifampicin, ex vivo explants of lesional HS from 8 HS patients were treated with rifampicin, and its effect on cytokine production, immune cells as well as the expression of Toll-like receptor 2 (TLR2) were investigated. Analysis of cell culture medium of rifampicin treated HS explants revealed an anti-inflammatory effect of rifampicin that significantly inhibiting interleukin (IL)-1β, IL-6, IL-8, IL-10, and tumour necrosis factor (TNF) -α production. Immunohistochemistry of the rifampicin-treated explants suggested a tendency for it to reduce the expression of TLR2 while not affecting the number of immune cells.

Hidradenitis Suppurativa: Host-Microbe and Immune Pathogenesis Underlie Important Future Directions

Hidradenitis suppurativa (HS) is an inflammatory disease of the skin with a chronic, relapsing-remitting course. The pathogenesis of the disease is poorly understood and involves multiple factors, including genetics, environment, host-microbe interactions, and immune dysregulation. In particular, the composition of the cutaneous microbiome shifts as the disease progresses, although it is unclear whether this is a primary or secondary process. Trials with immunomodulatory therapy elucidate the role of specific immune pathways and cytokine signaling in disease mechanism, such as TNF-α, IL-1β, IL-12, IL-17, IL-23, and complement. Future studies should continue examining the causes of and contributing factors to microbial changes and immune dysregulation in HS pathogenesis.

Metabolic syndrome and hidradenitis suppurativa: epidemiological, molecular, and therapeutic aspects

Hidradenitis suppurativa (HS) is a chronic, suppurative condition of the pilosebaceous unit. Patients suffering from HS demonstrate a molecular profile in keeping with a state of systemic inflammation and are often found to fit the criteria for a diagnosis of metabolic syndrome (MetS). In this paper, we review the literature with regards to established data on the prevalence of MetS in HS patients and revise the odds ratio of comorbid disease. Furthermore, we attempt to draw parallels between inflammatory pathways in HS and MetS and evaluate how convergences may explain the risk of comorbid disease, necessitating the need for multidisciplinary care.

Insights from γ-Secretase: Functional Genetics of Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic, relapsing, and remitting inflammatory disease of the skin with significant heritability and racial disposition. The pathogenesis of HS remains enigmatic, but occlusion of the terminal hair follicle and dysregulation of the local innate immune response may contribute to pathogenesis. Genetic predisposition might also contribute to disease susceptibility and phenotypic heterogeneity because mutations in γ-secretase have been found to underlie a minor but characteristic subset of patients with HS. In this review, we synthesized the current data on γ-secretase in HS, evaluated its importance in the context of disease pathobiology, and discussed avenues of future studies.

[Pathogenesis of hidradenitis suppurativa/acne inversa]

Hidradenitis suppurativa/acne inversa (HS) has a multifactorial pathogenesis. In addition to a sporadic form, a familial form is reported in around 40% of patients, for whom an autosomal dominant (AD) inheritance with reduced gene penetrance is assumed. The phenotype of the disease with inflammatory nodules, abscesses and secreting sinus tracts suggests an infectious origin, but the exact role of the bacteria detected in HS pathogenesis remains unclear. Smoking and metabolic syndrome are regarded as important trigger factors in HS, with obesity and hormonal changes playing a pathogenic role in the latter. Ultimately, Toll-like receptors, antimicrobial peptides, immune cells and key cytokines are involved in the excessive inflammatory reaction of HS and are also the targets of future therapies.

Mutations in γ-secretase subunit-encoding PSENEN gene alone may not be sufficient for the development of acne inversa

BACKGROUND

The effects of PSENEN mutations in patients with acne inversa (AI) are poorly understood. Hyperproliferation of follicular keratinocytes and resulting occlusion may constitute the initial pathophysiology.

OBJECTIVE

To investigate the effects of PSENEN knockdown on γ-secretase subunits, biological behaviors, and related signaling pathways in keratinocytes.

METHODS

HaCaT cells were divided into an experimental group (PSENEN knock down), a negative control group, and a blank control group. Whole transcriptome sequencing was used to measure differences in mRNA expression of the whole genome; real-time PCR and Western blotting were performed to determine the interference efficiency and the effects of interference on the components of γ-secretase and related molecules. CCK-8 was used to measure cell proliferation, and flow cytometry was used to measure apoptosis and the cell cycle.

RESULTS

A comparison of five healthy controls with three patients with PSENEN mutation (c.66delG, c.279delC, c.229_230insCACC) revealed decreased expression of mRNA and protein in skin lesions of the experimental group. In this group, expression of the other components of γ-secretase presenilin C-terminal fragment decreased, expression of immature nicastrin increased, expression of mature nicastrin decreased, and expression of anterior pharynx defective-1 remained unchanged. KEGG analysis revealed that differentially expressed molecules were enriched in m-TOR signaling pathways. Subsequent verification confirmed that differences in PI3K-AKT-mTOR signaling pathway molecules, cell proliferation, apoptosis, cell cycle and the expression levels of Ki-67, KRT1, and IVL between the groups were not statistically significant.

CONCLUSIONS

PSENEN mutations alone may be insufficient to cause the development of AI, or they may only induce a mild phenotype of AI.

NOD2 signalling in hidradenitis suppurativa

BACKGROUND

Hidradenitis suppurativa (HS) is associated with dysregulated immune responses including altered expression of cytokines, chemokines, and antimicrobial peptides and proteins (AMPs).

AIMS

To evaluate the expression of nucleotide-binding oligomerization domain-containing (NOD)2 and related factors in HS skin samples and keratinocyte cultures.

METHODS

We performed real-time PCR for NOD2, receptor-interacting serine/threonine-protein kinase (RIP)2, cyclic amine resistance locus (CARL), skin-derived antileukoproteinase (SKALP)/elafin, human β-defensin (hBD)2, LL37, psoriasin and RNAse7 in lesional and nonlesional skin of 19 patients with HS and in keratinocyte cultures [unstimulated, muramyl dipeptide (MDP)-stimulated or Pam2CSK4 (Pam2)-stimulated] from and nonlesional skin.

RESULTS

We observed significantly elevated mRNA expression for NOD2 (P < 0.01), hBD2 (P = 0.02), RNase7 (P < 0.001), psoriasin (P < 0.01) and SKALP/elafin (P = 0.02) in lesional compared with nonlesional skin. We found a significant correlation between NOD2 mRNA and hBD2 (r = 46; P = 0.04), psoriasin (r = 0.67; P < 0.01) and SKALP/elafin (r = 0.65; P < 0.01). In unstimulated, Pam2-stimulated and MDP-stimulated normal keratinocytes, NOD2, RIP2, CARL and SKALP/elafin expression significantly (P < 0.05) increased from 6 to 48 h, whereas in unstimulated, Pam2-stimulated and MDP-stimulated HS keratinocytes, RIP2, CARL and SKALP/elafin expression significantly (P < 0.05) declined from 6 to 48 h. mRNA expression of NOD2 (unstimulated, Pam2-stimulated, MDP-stimulated), CARL (unstimulated, Pam2-stimulated, MDP-stimulated) and SKALP/elafin (unstimulated, Pam2-stimulated) at 6 h was significantly increased in HS compared with normal keratinocytes.

CONCLUSION

We have shown for the first time that NOD2 signalling is activated in HS and might contribute to the pathogenesis via induction of AMPs and activation of other pathways such as nuclear factor κB signalling.