Pustular psoriasis as an autoinflammatory keratinization disease (AiKD): Genetic predisposing factors and promising therapeutic targets

Interventions in cytokine signaling: novel horizons for psoriasis treatment

Intricate interactions between immune cells and cytokines define psoriasis, a chronic inflammatory skin condition that is immunological-mediated. Cytokines, including interleukins (ILs), interferons (IFNs), tumor necrosis factors (TNFs), chemokines, and transforming growth factor-β (TGF-β), are essential for controlling cellular activity and immunological responses, maintaining homeostasis and contributing to the pathogenesis of psoriasis. These molecules modulate the immune microenvironment by either promoting or suppressing inflammation, which significantly impacts therapeutic outcomes. Recent research indicates that treatment strategies targeting cytokines and chemokines have significant potential, offering new approaches for regulating the immune system, inhibiting the progression of psoriasis, and reducing adverse effects of traditional therapies. This review consolidates current knowledge on cytokine and chemokine signaling pathways in psoriasis and examines their significance in treatment. Specific attention is given to cytokines like IL-17, IL-23, and TNF-α, underscoring the necessity for innovative therapies to modulate these pathways and address inflammatory processes. This review emphasizes the principal part of cytokines in the -pathological process of psoriasis and explores the challenges and opportunities they present for therapeutic intervention. Furthermore, we examine recent advancements in targeted therapies, with a particular focus on monoclonal antibodies, in ongoing research and clinical trials.

Recent Advances in Clinical Research on Rare Intractable Hereditary Skin Diseases in Japan

Our Research Group for Rare and Intractable Skin Diseases operates within the Project for Research on Intractable Diseases of the Ministry of Health, Labour, and Welfare of Japan and is conducting research on eight rare intractable skin diseases. Five of these are monogenic disorders (epidermolysis bullosa, congenital ichthyoses, oculocutaneous albinism, pseudoxanthoma elasticum, and hereditary angioedema), and for a sixth [generalized pustular psoriasis (GPP)], genetic predisposing factors are important. This review introduces our activities for raising public awareness of these six intractable hereditary skin diseases and summarizes our recent achievements in clarifying the situation of medical treatments for these diseases in Japan. We note our current progress in elucidating the pathogeneses of these diseases and in developing new treatment methods, and we discuss our progress in establishing clinical practice guidelines. A nationwide survey on epidermolysis bullosa and a clinical survey on congenital ichthyoses are progressing. The Angioedema Activity Score and the Angioedema Quality-of-Life Questionnaire, the latter of which is a quality-of-life evaluation tool, have been established for hereditary angioedema. Registries of patients with oculocutaneous albinism and pseudoxanthoma elasticum have been created, and the registry for the latter has achieved its target of 170 cases. For GPP, the results of our survey on clinical practice were published in 2021. Information regarding all six of these hereditary skin diseases has been disseminated to academic societies, medical professionals, patients, and the general public.

Updated genetic background of generalized pustular psoriasis as an autoinflammatory keratinization disease

Generalized pustular psoriasis (GPP) is a severe autoinflammatory keratinization disease (AiKD) characterized by acute flares of widespread sterile pustules and high fever. GPP is potentially life-threatening. Recently clarified genetic predisposing factors for GPP suggest that the excessive activation of innate immune pathways in the skin, including of interleukin (IL)-1 and IL-36 signaling, plays a significant role in the GPP pathogenesis. IL36RN, CARD14, AP1S3, MPO, SERPINA3, BTN3A3, and MEFV have been identified as GPP-related genes. The pathogenesis of GPP provoked by variants in these seven genes is tightly associated with the excessive activation of innate immune pathways and the resulting autoinflammation in the skin. Various biologics, including inhibitors for the tumor necrosis factor, IL-17, and IL-23 pathways, are used as treatments for GPP. The new understanding of the genetic background of GPP, mentioned above, indicates that the genetic predisposing factors are predominantly related to the excessive activation of innate immunity and autoinflammation. In this context, inhibitors of inflammatory signaling, including of the IL-1 and IL-36 pathways, have been used in clinical practice and investigated as potential future therapies.

Successful Treatment of Linear Psoriasis With the IL-17a-Antagonist Ixekizumab: A Case Report

Linear psoriasis (LP) represents a rare variant of psoriasis. The clinical presentation includes erythematous plaques distributed along the Blaschko lines, reflecting the presence of embryological mosaicism. The clinical and histopathological features of this condition show many similarities with inflammatory linear verrucous epidermal nevus (ILVEN), which presents a challenge in differential diagnosis. Currently there is no disease-specific treatment guidelines causing a challenge in the therapeutic management. In this case report we describe a 28-year-old patient with LP. Clinically characterized by persistent, psoriasiform lesions that proved refractory to treatment with topical corticosteroids, vitamin D analogs, and systemic dimethyl fumarate. The histopathological findings showed psoriasiform epidermal hyperplasia with alternating ortho- and parakeratosis, subepidermal capillary dilatation, and perivascular lymphocytic infiltrates, confirming the diagnosis. Ixekizumab, a IL-17A antagonist, was administered leading to a rapid and significant reduction in disease severity within the first 16 weeks. The Psoriasis Area and Severity Index (PASI) decreased from 12.5 to 1.0 and as well as the Dermatology Life Quality Index (DLQI) improved to 1. Both scores prove significant improvement in quality of life and clinical severity. This case report shows the importance of histological confirmation in differentiating LP from clinically similar appearing diseases like ILVEN and highlights the potential therapeutic benefit of IL-17 blockade in LP. In addition, the findings emphasize the need for systematic studies to develop evidence-based treatment strategies for this rare psoriasis phenotype.

The essential function of cathepsin X of the orange-spotted grouper, Epinephelus coioides during SGIV infection

Cathepsin X, a class of cysteine proteases in the lysosome, involved in intracellular protein degradation processes. Numerous reports revealed that many kinds of cysteine proteases played a crucial role in pathogen invasion. To investigate the relationship between cathepsin X of teleost fish and virus infection, EcCX was cloned and characterized in the orange-spotted grouper, Epinephelus coioides. The open reading frame (ORF) of EcCX included 909 nucleotides and encoded a protein consisting of 302 amino acids, which shared 75% and 56% identity with zebrafish and humans, respectively. The protein EcCX mainly consisted of a signal peptide (1-19 aa), a pro-pre-peptide region (20-55 aa), and a mature cysteine protease region (56-302 aa). Subcellular localization analysis showed that EcCX was mainly distributed in the cytoplasm, but EcCX ectoped to the vicinity of apoptotic vesicles in FHM cells during SGIV infection. Following stimulation with SGIV or Poly (dA:dT), there was a notable rise in the expression levels of EcCX. EcCX overexpression facilitated virus infection, upregulated the production of inflammatory factors, and induced the activation of the NF-κB promoter. Furthermore, the overexpression of EcCX also accelerated the process of SGIV-induced apoptosis, potentially by enhancing the promoter activity of P53 and AP-1. Overall, our findings demonstrated a correlation between the function of EcCX and SGIV infection, providing a new understanding of the mechanisms involved in fish virus infection.

A pediatric case of dupilumab-induced pustular psoriasis

Dupilumab is a novel treatment agent for moderate to severe atopic dermatitis (AD) with few adverse effects. Drug-induced psoriasiform lesions are rare.

We report a 4-year-old boy with AD who developed pustular psoriasis during treatment with dupilumab.

Pustular psoriasis appeared within 1 week of treatment and worsened in the second week. After stopping dupilumab administration, topical corticosteroids (desonide and mometasone furoate creams) and oral desloratadine without relief. Pustular psoriasis was confirmed by pathological examination, and thiamphenicol was administered. After 2 weeks of treatment, the lesions nearly resolved without recurrence in 1-year follow-up.

Dupilumab-induced pustular psoriasis is rare in children.

A case of revertant mosaic-like normal-looking spots in a patient with erythroderma with IL36RN and CARD14 heterozygous mutations

An 89-year-old Japanese woman presented with erythroderma associated with significant scaling. A histological examination showed acanthosis with hyperkeratosis and hyperkeratinization of the hair follicles. Genetic analyses using DNA from the peripheral blood revealed heterozygous mutations in IL36RN (c.115+6T>C) and CARD14 c.2648G>A (p.Arg883His). Based on these findings, we diagnosed her with erythroderma attributable to autoinflammatory keratinization disease. She then developed more than 30 small, round, well-defined, spots on her back and extremities that appeared histologically normal. We suspected that these spots might be revertant mosaicism. Immunohistochemical staining with p65, which is a component of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), revealed nuclear staining in epidermal keratinocytes in erythematous lesions, but not in the normal-looking spots. However, mutations in IL36RN and CARD14 unexpectedly persisted in the epidermis and dermis of the normal-looking spots.

RNA-binding proteins potentially regulate alternative splicing of immune/inflammatory-associated genes during the progression of generalized pustular psoriasis

Generalized pustular psoriasis (GPP) is a rare but severe form of psoriasis. However, the pathogenesis of GPP has not been fully elucidated. Although RNA-binding proteins (RBPs) and the alternative splicing (AS) process are essential for regulating post-transcriptional gene expression, their roles in GPP are still unclear. We aimed to elucidate the regulatory mechanisms to identify potential new therapeutic targets. Here, We analyzed an RNA sequencing (RNA-seq) dataset (GSE200977) of peripheral blood mononuclear cells (PBMCs) of 24 patients with GPP, psoriasis vulgaris (PV), and healthy controls (HCs) from the Gene Expression Omnibus (GEO) database. We found that the abnormal alternative splicing (AS) events associated with GPP were mainly "alt3p/alt5p", and 15 AS genes were differentially expressed. Notably, the proportions of different immune cell types were correlated with the expression levels of regulatory alternatively spliced genes (RASGs): significant differences were observed in expression levels of DTD2, NDUFAF3, NBPF15, and FBLN7 in B cells and ARFIP1, IPO11, and RP11-326L24.9 in neutrophils in the GPP samples. Furthermore, We identified 32 differentially expressed RNA-binding proteins (RBPs) (18 up-regulated and 14 down-regulated). Co-expression networks between 14 pairs of differentially expressed RBPs and RASGs were subsequently constructed, demonstrating that these differentially expressed RBPs may affect the progression of GPP by regulating the AS of downstream immune/inflammatory-related genes such as LINC00989, ENC1 and MMP25-AS1. Our results were innovative in revealing the involvement of inflammation-related RBPs and RASGs in the development of GPP from the perspective of RBP-regulated AS.

New and Emerging Treatments for Generalized Pustular Psoriasis: Focus on IL-36 Receptor Inhibitors

Generalized Pustular Psoriasis (GPP) is a rare and severe subtype of psoriasis that significantly impacts patients' quality of life. Until recently, no specific treatment modalities were available, and treatment for GPP followed the guidelines for the treatment of plaque psoriasis, consisting of conventional treatments, such as retinoids, methotrexate, and even biologics, which although effective in some cases, may be associated with significant side effects, necessitating more effective and safe options. The pathophysiology of Generalized Pustular Psoriasis is complex and not fully understood, but there is some overlap with the pathogenesis of Plaque Psoriasis. In GPP, the innate immune system seems to play a more significant role, with the interleukin (IL)-36 pathway being fundamentally involved. Spesolimab and imsidolimab, two recently developed therapeutic agents, target the IL-36 inflammatory pathway by binding to the IL-36 receptor (IL-36R). Both biologics have already been evaluated in phase 1 and 2 clinical trials and have shown promising results in terms of safety and efficacy. IL-36 receptor inhibitors demonstrated great efficacy and good safety profile in the management of patients with GPP, demonstrating their potential to emerge as a leading treatment option. This review aims to explore and summarize the current scientific literature on the most recently developed treatments for GPP.

Targeted review of IL36RN mutations in patients with generalised pustular psoriasis

Background

Generalised pustular psoriasis (GPP) is a rare and chronic skin disease historically treated with therapies that were originally intended to treat plaque psoriasis (PsO). However, GPP and plaque PsO have distinct pathogeneses and clinical courses.

Objectives

This study aimed to further characterise the unique genetic background of GPP by summarising evidence on the frequency and type of IL36RN gene mutation, a gene that normally suppresses proinflammatory responses, in patients with GPP compared to patients with GPP and plaque PsO, and patients with plaque PsO only.

Methods and Results

A targeted literature review was conducted to identify studies reporting IL36RN mutations and/or HLA-Cw6 allele frequency in patients with GPP. Meta-analyses showed a significantly higher rate of IL36RN mutations in the GPP-only population compared to the GPP + plaque PsO population (OR 3.51; 95% CI 2.29, 5.38). Monoallelic mutations of IL36RN were found in up to 33.3%, and biallelic mutations in up to 73.2% of patients with GPP (GPP-only and GPP + plaque PsO), in contrast with mono- and biallelic frequencies of only 0%-11.9% and 0%, respectively, in patients with plaque PsO only. Mean age-of-onset ranged from 5.9 to 48.9 years old, with most studies reporting a GPP age-of-onset between 20 and 40 years old. Twenty-one mutations were identified in the biallelic state and three in monoallelic. The most reported mutations were c.115 + 6T > C (p. Arg10ArgfsX1) (18 studies); c.227 C > T (p.Pro76Leu) (10 studies); and c.338 C > T (p.Ser113Leu) (8 studies). Mutations varied depending on geography and ethnicity, with the most frequently reported mutation predominantly reported in East Asian studies and international studies that included Asian patients. Rates of HLA-Cw6, the risk allele most strongly associated with plaque PsO, were 0%-28.6% for patients with GPP, similar to rates in the general population (10.5%-20%).

Conclusion

Considering the differences between GPP and plaque PsO in aetiology and disease symptoms, effective, GPP-specific treatment options are needed, and recent research suggests that blockade of IL-36 signalling may be an effective target for treatment of GPP.

Immune cells in the epithelial immune microenvironment of psoriasis: emerging therapeutic targets

Psoriasis is a chronic autoimmune inflammatory disease characterized by erroneous metabolism of keratinocytes. The development of psoriasis is closely related to abnormal activation and disorders of the immune system. Dysregulated skin protective mechanisms can activate inflammatory pathways within the epithelial immune microenvironment (EIME), leading to the development of autoimmune-related and inflammatory skin diseases. In this review, we initially emphasized the pathogenesis of psoriasis, paying particular attention to the interactions between the abnormal activation of immune cells and the production of cytokines in psoriasis. Subsequently, we delved into the significance of the interactions between EIME and immune cells in the emergence of psoriasis. A thorough understanding of these immune processes is crucial to the development of targeted therapies for psoriasis. Finally, we discussed the potential novel targeted therapies aimed at modulating the EIME in psoriasis. This comprehensive examination sheds light on the intricate underlying immune mechanisms and provides insights into potential therapeutic avenues of immune-mediated inflammatory diseases.

Knowledge Mapping and Research Hotspots of Generalized Pustular Psoriasis: A Bibliometric Analysis from 2003 to 2023

Background

Generalised pustular psoriasis (GPP) is a chronic inflammatory skin disease. We aimed to visualize the research hotspots and trends of GPP using bibliometric analysis to enhance our comprehension of the future advancements in both basic science and clinical research.

Methods

Relevant publications from July 2003 to July 2023 were obtained from the Web of Science Core Collection on July 12, 2023. The analysis of countries, institutions, authors, references, and keywords associated with this subject was conducted through the utilisation of CiteSpace 6.2.R4, VOSviewer 1.6.18, and Microsoft Excel 2019.

Results

A total of 578 papers were analyzed, authored by 2758 researchers from 191 countries/regions and 1868 institutions, published in 174 academic journals. There was an overall upward trajectory in the volume of annual publications, accompanied by a gradual intensification of research interest in GPP. The United States, UDICE-French Research Universities, and Akiyama M of Nagoya University were the most productive and influential country, institution, and author, respectively. The Journal of Dermatology ranked first with the highest publications, and the Journal of the American Academy of Dermatology received the most citations. High-frequency keywords included "generalized pustular psoriasis", "psoriasis, interleukin-36", "plaque psoriasis", "skin-disease", and "antagonist deficiency". Recent research focuses have included "safety", "secukinumab", "spesolimab", "ap1s3 mutations", and "interleukin-36". Burst detection analysis of keywords showed that "moderate", "ixekizumab treatment", "mutations", "efficacy", and "safety" are current research frontiers in this field.

Conclusion

This bibliometric analysis delineated the landmark publications in GPP that have defined current research hotspots and development trends, notably the applications, efficacy, and safety of biological agents. Future research endeavors are warranted to explore other biological therapeutic options for both acute GPP and the long-term management of chronic GPP.

The role of the interleukin-36 axis in generalized pustular psoriasis: a review of the mechanism of action of spesolimab

Generalized pustular psoriasis (GPP) is a rare, chronic, inflammatory skin disorder characterized by recurrent flares associated with skin erythema, desquamation, and widespread superficial sterile pustules, which may be severe ("lakes of pus"). Systemic symptoms are often present, including malaise, fever, and skin pain. In GPP, innate immune responses are driven by abnormal activation of the interleukin (IL)-36-chemokine-neutrophil axis and excessive neutrophil infiltration. This review highlights the IL-36 pathway in the context of the IL-1 superfamily and describes how unopposed IL-36 signaling can lead to the development of GPP. Targeted inhibition of the IL-36 receptor (IL-36R) is an attractive therapeutic strategy in the treatment of GPP, including flare prevention and sustained disease control. Spesolimab is a first-in-class, humanized, monoclonal antibody that binds specifically to the IL-36R and antagonizes IL-36 signaling. Spesolimab was approved by the US Food and Drug Administration in September 2022 to treat GPP flares in adults and was subsequently approved for GPP flare treatment in other countries across the world. Anti-IL-36R therapy, such as spesolimab, can mitigate flares and address flare prevention in GPP, presumably through rebalancing IL-36 signaling and modulating the pro-inflammatory response of the downstream effectors.

Cathepsin and cutaneous disorders of cornification and inflammation: their close links

As mentioned above, the cathepsin family is a group of important proteases that are deeply involved in the development of various skin disorders of cornification and inflammation, including AiKDs. The cathepsin family members are considered to play essential roles in the keratinocyte proliferation/differentiation and inflammatory pathways in the skin.

Current management of generalized pustular psoriasis

Generalized pustular psoriasis (GPP) is a rare subset of psoriasis involving episodes of sterile pustules accompanied by inflammation and, often, systemic involvement. The inflammatory nature of GPP has potential for severe multisystem complications including high-output cardiac failure, infections, digestive system issues, and disfiguring or lethal acute flare episodes. The disease tends to have higher prevalence in females and Asians. The IL-1/IL-36 inflammatory pathway is a critical facet of GPP's pathology. Genetic mutations that are associated with GPP include modifications of Interleukin 36 Receptor Antagonist (IL36RN), Caspase Recruitment Domain Family Member 14 (CARD14), Adaptor Related Protein Complex 1 Subunit Sigma 3 (AP1S3), Myeloperoxidase (MPO) and Serpin Peptidase Inhibitor Clade A Member 3 (SERPINA3) genes. Treatment guidelines for GPP are not well-entrenched. Currently, only one GPP-specific treatment, the interleukin-36 receptor antagonist (IL-36Ra) spesolimab, has been approved for use in the United States. Additional anti-IL-36 pathway therapies are currently being developed. Other treatment options include other biologic therapies such as IL-17 inhibitors, IL-23 inhibitors and TNFα inhibitors. Non-biologic therapeutic options include retinoids, cyclosporine and methotrexate. Treatment options differ throughout the world; most countries utilize retinoids, cyclosporine and methotrexate as first-line non-biologic options. China and United Kingdom have no GPP-specific biologic therapies approved for use, while several biologic therapies are approved for use in Japan. This review aims to serve as an update on the current global management of GPP while also including relevant aspects of disease pathogenesis, diagnosis, clinical presentation, histopathology, aetiology and epidemiology.

Sericin coated thin polymeric films reduce keratinocyte proliferation via the mTOR pathway and epidermal inflammation through IL17 signaling in psoriasis rat model

Therapeutic treatment forms can play significant roles in resolving psoriatic plaques or promoting wound repair in psoriatic skin. Considering the biocompatibility, mechanical strength, flexibility, and adhesive properties of silk fibroin sheets/films, it is useful to combine them with anti-psoriatic agents and healing stimulants, notably silk sericin. Here, we evaluate the curative properties of sericin-coated thin polymeric films (ScF) fabricated from silk fibroin, using an imiquimod-induced psoriasis rat model. The film biocompatibility and psoriatic wound improvement capacity was assessed. A proteomics study was performed to understand the disease resolving mechanisms. Skin-implantation study exhibited the non-irritation property of ScF films, which alleviate eczema histopathology. Immunohistochemical and gene expression revealed the depletion of β-defensin, caspase-3 and -9, TNF-α, CCL-20, IL-1β, IL-17, TGF-β, and Wnt expressions and S100a14 mRNA level. The proteomics study suggested that ScF diminish keratinocyte proliferation via the mTOR pathway by downregulating mTOR protein, corresponding to the modulation of TNF-α, Wnt, and IL-1β levels, leading to the enhancement of anti-inflammatory environment by IL-17 downregulation. Hematology data demonstrated the safety of using these biomaterials, which provide a potential therapeutic-option for psoriasis treatment due to desirable effects, especially anti-proliferation and anti-inflammation, functioning via the mTOR pathway and control of IL-17 signaling.

Genetics of Generalized Pustular Psoriasis: Current Understanding and Implications for Future Therapeutics

Psoriasis is a chronic inflammatory skin disease characterized by the appearance of clearly demarcated erythematous and scaly plaques. It can be divided into various types, including plaque, nail, guttate, inverse, and pustular psoriasis. Plaque psoriasis is the most commonly occurring type, though there is another rare but severe pustular autoinflammatory skin disease called generalized pustular psoriasis (GPP), which manifests with acute episodes of pustulation and systemic symptoms. Though the etiopathogenesis of psoriasis is not yet fully understood, a growing body of literature has demonstrated that both genetic and environmental factors play a role. The discovery of genetic mutations associated with GPP has shed light on our comprehension of the mechanisms of the disease, promoting the development of targeted therapies. This review will summarize genetic determinants as known and provide an update on the current and potential treatments for GPP. The pathogenesis and clinical presentation of the disease are also included for a comprehensive discussion.

Targeting IL-36 in Inflammatory Skin Diseases

Interleukin (IL)-36 cytokines are members of the IL-1 superfamily of cytokines. IL-36 cytokines are composed of three agonists (IL-36α, IL-36β, and IL-36γ) and two antagonists (IL-36 receptor antagonist [IL36Ra] and IL-38). These work in innate and acquired immunity and are known to contribute to host defense and to the pathogenesis of autoinflammatory diseases, autoimmune diseases, and infectious diseases. In the skin, IL-36α and IL-36γ are mainly expressed by keratinocytes in the epidermis, although they are also produced by dendritic cells, macrophages, endothelial cells, and dermal fibroblasts. IL-36 cytokines participate in the first-line defense of the skin against various exogenous assaults. IL-36 cytokines play significant roles in the host defense system and in the regulation of inflammatory pathways in the skin, collaborating with other cytokines/chemokines and immune-related molecules. Thus, numerous studies have shown IL-36 cytokines to play important roles in the pathogenesis of various skin diseases. In this context, the clinical efficacy and safety profiles of anti-IL-36 agents such as spesolimab and imsidolimab have been evaluated in patients with generalized pustular psoriasis, palmoplantar pustulosis, hidradenitis suppurativa, acne/acneiform eruptions, ichthyoses, and atopic dermatitis. This article comprehensively summarizes the roles played by IL-36 cytokines in the pathogenesis and pathophysiology of various skin diseases and summarizes the current state of research on therapeutic agents that target IL-36 cytokine pathways.

Newly revealed variants of SERPINA3 in generalized pustular psoriasis attenuate inhibition of ACT on cathepsin G

Generalized pustular psoriasis (GPP) is an autoinflammatory skin disease whose pathogenesis has not yet been fully elucidated. Alpha-1-antichymotrypsin(ACT) is a protein encoded by the SERPINA3 gene and an inhibitor of cathepsin G. One study of a European sample suggested that the loss of ACT function caused by SERPINA3 mutation is implicated in GPP. However, the role of SERPINA3 in the pathogenesis of GPP in other ethnic populations is unclear. To explore this, seventy children with GPP were performed next-generation sequencing to identify rare variants in the SERPINA3 gene. Bioinformatic analysis and functional tests were used to determine the effects of the variants, and a comprehensive analysis was performed to determine the pathogenicity of the variants and whether they are associated with GPP. One rare deletion and three rare missense variants were identified in the SERPINA3 gene in GPP. The deletion variant c.1246_1247del was found to result in a mutant protein with an extension of 10 amino acids and a C-terminal of 20 amino acids that was completely different from the wild-type. This mutant was found to impede secretion of ACT, thus failing to function as an inhibitor of cathepsin G. Two missense variants were found to reduce the ability of ACT to inhibit cathepsin G enzymatic activity. The association analysis suggested that the deletion variant is associated with GPP. This study identified four rare novel mutations of SERPINA3 and demonstrated that three of these mutations result in loss of function, contributing to the pathogenesis of pediatric-onset GPP in the Asian population.

Multitranscriptome analyses of keloid fibroblasts reveal the role of the HIF-1α/HOXC6/ERK axis in keloid development

Background

A keloid is a disease of excessive fibrosis that is characterized by the aberrant proliferation of fibroblasts. However, the molecular mechanisms of fibroblasts during the development of keloids remain unclear. This study aims to identify new molecular targets that promote the proliferation and migration of keloid fibroblasts, providing new ideas for the prevention and treatment of keloids.

Methods

We utilized bioinformatics tools to analyze data from keloid fibroblasts (KFs) available in the Gene Expression Omnibus (GEO) database to identify the key genes involved in keloid development. Homeobox C6 (HOXC6) emerged as a hub gene in KFs from the GEO database was verified in keloid tissue samples and KFs using reverse transcription-quantitative polymerase chain reaction, western blot (WB) and immunohistochemistry. Subsequently, the effects of downregulated HOXC6 expression on the cellular behaviors of KFs were examined by performing Cell Counting Kit-8, flow cytometry, transwell migration and WB assays. Meanwhile, we performed transcriptome sequencing and gene set enrichment analysis (GSEA) to further explore HOXC6-related mechanisms and validated the signaling pathways by performing a series of experiments.

Results

HOXC6 was the top-ranking hub gene of KFs in microarray datasets from GEO and was upregulated in keloid tissue samples and KFs. Downregulation of HOXC6 inhibited proliferation, migration and extracellular matrix (ECM) accumulation and promoted KF apoptosis. GSEA predicted that the hypoxia signaling pathway was associated with HOXC6 in KFs. Transcriptome sequencing suggested that the extracellular regulated protein kinase (ERK) pathway was one of the downstream pathways of HOXC6 in KFs. Our experiments confirmed that hypoxia-inducible factor-1α (HIF-1α) upregulates HOXC6, contributing to KFs proliferation, migration, apoptosis inhibition and collagen accumulation through the ERK signaling pathway.

Conclusions

Our findings first revealed that HOXC6 acts as an oncogenic driver in the molecular mechanisms of fibroblasts in keloids. The HIF-1α/HOXC6/ERK axis promotes proliferation, migration and ECM production by KFs, contributing to the progression of keloids. Taken together, HOXC6 may serve as a promising novel therapeutic target and new focus for research designed to understand the pathogenesis of keloids.