Histone deacetylase inhibition mitigates fibrosis-driven disease progression in recessive dystrophic epidermolysis bullosa.

BACKGROUND: Recessive dystrophic epidermolysis bullosa (RDEB) is a blistering disease caused by mutations in the gene encoding type VII collagen (C7). RDEB is associated with fibrosis, which is responsible for severe complications. The phenotypic variability observed in siblings with RDEB suggests that epigenetic modifications contribute to disease severity. Identifying epigenetic changes may help to uncover molecular mechanisms underlying RDEB pathogenesis and new therapeutic targets. OBJECTIVES: To investigate histone acetylation in RDEB skin and to explore histone deacetylase inhibitors (HDACi) as therapeutic molecules capable of counteracting fibrosis and disease progression in RDEB mice. METHODS: Acetylated histone levels were detected in human skin by immunofluorescence and in RDEB fibroblasts by enzyme-linked immunosorbent assay (ELISA). The effects of givinostat and valproic acid (VPA) on RDEB fibroblast fibrotic behaviour were assessed by a collagen-gel contraction assay, Western blot and immunocytofluorescence for α-smooth muscle actin, and ELISA for released transforming growth factor (TGF)-ß1. RNA sequencing was performed in HDACi- and vehicle-treated RDEB fibroblasts. VPA was systemically administered to RDEB mice and effects on overt phenotype were monitored. Fibrosis was investigated in the skin using histological and immunofluorescence analyses. Eye and tongue defects were examined microscopically. Mass spectrometry proteomics was performed on skin protein extracts from VPA-treated RDEB and control mice. RESULTS: Histone acetylation decreases in RDEB skin and primary fibroblasts. RDEB fibroblasts treated with HDACi lowered fibrotic traits, including contractility, TGF-ß1 release and proliferation. VPA administration to RDEB mice mitigated severe manifestations affecting the eyes and paws. These effects were associated with fibrosis inhibition. Proteomic analysis of mouse skin revealed that VPA almost normalized protein sets involved in protein synthesis and immune response, processes linked to the increased susceptibility to cancer and bacterial infections seen in people with RDEB. CONCLUSIONS: Dysregulated histone acetylation contributes to RDEB pathogenesis by facilitating the progression of fibrosis. Repurposing of HDACi could be considered for disease-modifying treatments in RDEB.

Recessive dystrophic epidermolysis bullosa (or 'RDEB') is a rare skin disease that affects fewer than 5,000 people in the USA. A similar number of people in Europe are affected. RDEB is caused by mutations in the gene that controls the production of a protein called 'type VII collagen' (or 'C7'). A shortage of C7 causes fragile skin that blisters. In severe forms of RDEB, wounds heal slowly and can even affect a person's life expectancy. Differences in the disease are common in people (even identical twins) with RDEB who have similar levels of C7. This suggests that how severe the disease is could be affected by molecular processes that control other genes. Understanding these processes may help us to find treatments for RDEB. This study was done in Italy, in collaboration with centres in Germany and Switzerland. We wanted to see whether a chemical modification called 'histone acetylation' (which influences gene activity) is different in RDEB and whether it can be targeted by a specific treatment. We found that histone acetylation is reduced in RDEB skin and in skin cells grown in the lab called 'fibroblasts'. When we increased histone acetylation in fibroblasts with two drugs called givinostat and valproic acid, the amount of scar tissue produced decreased. This is important because scar tissue can lead to severe symptoms. We carried out more experiments to study the effects of givinostat and valproic acid in mice with RDEB. We found that valproic acid reduces the severity of RDEB by decreasing the disease's harmful effects and reducing the amount of scar tissue. Our findings suggest that abnormal histone acetylation contributes to the scar tissue seen in RDEB. Our study shows that valproic acid could be useful in treating the scarring seen in RDEB and in reducing the effects of the disease. As this drug is used to treat other diseases, there could be potential for rapid repurposing of it for RDEB.

Multiple Skin Squamous Cell Carcinomas in Junctional Epidermolysis Bullosa Due to Altered Laminin-332 Function.

Variably reduced expression of the basement membrane component laminin-332 (α3aß3γ2) causes junctional epidermolysis bullosa generalized intermediate (JEB-GI), a skin fragility disorder with an increased susceptibility to squamous cell carcinoma (SCC) development in adulthood. Laminin-332 is highly expressed in several types of epithelial tumors and is central to signaling pathways that promote SCC tumorigenesis. However, laminin-332 mutations and expression in individuals affected by JEB-GI and suffering from recurrent SCCs have been poorly characterized. We studied a JEB-GI patient who developed over a hundred primary cutaneous SCCs. Molecular analysis combined with gene expression studies in patient skin and primary keratinocytes revealed that the patient is a functional hemizygous for the p.Cys1171* mutant allele which is transcribed in a stable mRNA encoding for a ß3 chain shortened of the last two C-terminal amino acids (Cys1171-Lys1172). The lack of the Cys1171 residue involved in the C-terminal disulphide bond to γ2 chain did not prevent assembly, secretion, and proteolytic processing of the heterotrimeric molecule. Immunohistochemistry of SCC specimens revealed accumulation of mutant laminin-332 at the epithelial-stromal interface of invasive front. We conclude that the C-terminal disulphide bond is a structural element crucial for laminin-332 adhesion function in-vivo. By saving laminin-332 amount, processing, and signaling role the p.Cys1171* mutation may allow intrinsic pro-tumorigenic properties of the protein to be conveyed, thus contributing to invasiveness and recurrence of SCCs in this patient.

T-lymphocytes are directly involved in the clinical expression of migratory circinate erythema in epidermolysis bullosa simplex patients.

Epidermolysis bullosa simplex with migratory circinate erythema (EBS-MCE) is a rare EBS subtype characterised by migratory blistering lesions that resolve with brownish pigmentation. It is caused by a recurrent readthrough mutation, c.1649delG, in the tail of keratin 5. Here, we report a child with EBS-MCE and investigated the immunologic mechanisms underlying the migratory lesions in this patient. A skin biopsy from the patient from an active border of an erythematous lesion was used for the immunohistochemical characterisation of the inflammatory infiltrate and for TUNEL assay to detect apoptotic cells. We found abundant CD4+ and CD8+ T lymphocytes infiltrating the papillary dermis and lining the dermal-epidermal junction. A number of these cells expressed the activation marker CD69. CD83+ dendritic cells were present both in the epidermis and papillary dermis. Finally, TUNEL staining showed apoptosis of basal and suprabasal keratinocytes. These findings suggest a critical role of the cellular immunity in determining the EBS-MCE phenotype.

Early immunopathological diagnosis of ichthyosis with confetti in two sporadic cases with new mutations in keratin 10.

Ichthyosis with confetti (IC) is a severe non-syndromic ichthyosis due to heterozygous mutations in the KRT10 gene. The disease manifests at birth with erythroderma and scaling and is characterised by the gradual development of numerous confetti-like spots of normal skin. Diagnosis of IC is frequently delayed until adolescence or even adulthood. We report 2 young children who were first diagnosed as having congenital ichthyosiform erythroderma. However, the development of thick, confluent hyperkeratotic plaques together with the histopathological finding of keratinocyte vacuolisation in the suprabasal epidermis evoked IC. Immunofluorescence analysis showed a highly reduced keratin 10 expression within the cytoplasm of suprabasal keratinocytes and its characteristic mislocalisation to the nuclei. The diagnosis was confirmed by the identification of 2 previously unreported mutations in intron 6 and exon 7 of KRT10. Careful clinical examination then showed the presence of the first spots of normal skin in both patients at the age of 2.5 and 5 years, respectively. These cases point to the usefulness of immunofluorescence analysis of keratin 10 expression for an early diagnosis of IC.

Case report: Bullous pemphigoid arising in a patient with scleroderma and multiple sclerosis.

Background: Bullous pemphigoid (BP) is the most common autoimmune-blistering disease, clinically characterized by erythematous urticarial plaques, blisters, and intense pruritus, induced by autoantibodies against two proteins of the dermo-epidermal junction, BP180 and BP230. A large number of autoimmune diseases are reported in the literature as BP comorbidities, such as multiple sclerosis, but only a few cases are in association with scleroderma and none in association with both. Case presentation: We present the case of a 68-year-old woman affected by multiple sclerosis and scleroderma who developed severe bullous pemphigoid with a bullous pemphigoid disease area index of 60 and high titers of anti-BP180 and anti-BP230 autoantibodies by enzyme-linked immunosorbent assays. After 2 months of therapy with both intravenous and oral corticosteroids, the active lesions of bullous pemphigoid were remitted with no relapse. Conclusion: Autoimmune diseases affecting the skin or organs where BP180 and BP230 are present could trigger an immune response to these antigens through an epitope-spreading phenomenon and, over the years, induce bullous pemphigoid onset.

A Novel Phenotype of Junctional Epidermolysis Bullosa with Transient Skin Fragility and Predominant Ocular Involvement Responsive to Human Amniotic Membrane Eyedrops.

Junctional epidermolysis bullosa (JEB) is a clinically and genetically heterogeneous skin fragility disorder frequently caused by mutations in genes encoding the epithelial laminin isoform, laminin-332. JEB patients also present mucosal involvement, including painful corneal lesions. Recurrent corneal abrasions may lead to corneal opacities and visual impairment. Current treatments are merely supportive. We report a novel JEB phenotype distinguished by the complete resolution of skin fragility in infancy and persistent ocular involvement with unremitting and painful corneal abrasions. Biallelic LAMB3 mutations c.3052-5C>G and c.3492_3493delCG were identified as the molecular basis for this phenotype, with one mutation being a hypomorphic splice variant that allows residual wild-type laminin-332 production. The reduced laminin-332 level was associated with impaired keratinocyte adhesion. Then, we also investigated the therapeutic power of a human amniotic membrane (AM) eyedrop preparation for corneal lesions. AM were isolated from placenta donors, according to a procedure preserving the AM biological characteristics as a tissue, and confirmed to contain laminin-332. We found that AM eyedrop preparation could restore keratinocyte adhesion in an in vitro assay. Of note, AM eyedrop administration to the patient resulted in long-lasting remission of her ocular manifestations. Our findings suggest that AM eyedrops could represent an effective, non-invasive, simple-to-handle treatment for corneal lesions in patients with JEB and possibly other EB forms.

Concomitant activation of Wnt pathway and loss of mismatch repair function in human melanoma.

Constitutive activation of the Wnt pathway plays a key role in the development of colorectal cancer and has also been implicated in the pathogenesis of other malignancies. Deregulation of Wnt signaling mainly occurs through genetic alterations of APC, the beta-catenin gene (CTNNB1), AXIN1 and AXIN2, leading to stabilization of beta-catenin. Physiologically, AXIN2 is transcriptionally induced on Wnt signaling activation and acts as a negative feedback regulator of the pathway. In colorectal cancer, mutations in CTNNB1 and AXIN2 occur preferentially in tumors with inactivation of the mismatch repair (MMR) genes MSH2, MLH1, or PMS2. In this study, the expression of beta-catenin and AXIN2, and the mutational status of CTNNB1, APC, and AXIN2 were evaluated in two MMR-deficient (PR-Mel and MR-Mel) and seven MMR-proficient human melanoma cell lines. Only PR-Mel and MR-Mel cells showed nuclear accumulation of beta-catenin and expression of the AXIN2 gene, and hence, constitutive activation of Wnt signaling. Mutational analysis identified a somatic heterozygous missense mutation in CTNNB1 exon three and a germline heterozygous deletion within AXIN2 exon seven in PR-Mel cells, and a somatic biallelic deletion within APC in MR-Mel cells. Deregulation of Wnt signaling and a defective MMR system were also present in the original tumor of PR and MR patients. Thus, we describe additional melanomas with mutations in CTNNB1 and APC, identify for the first time a germline AXIN2 mutation in a melanoma patient and suggest that inactivation of the MMR system and deregulation of the Wnt/beta-catenin signaling pathway cooperate to promote melanoma development and/or progression.

Bullous pemphigoid with hyperkeratosis and palmoplantar keratoderma: Three cases.

The clinical features of bullous pemphigoid are extremely polymorphous. Several atypical forms of bullous pemphigoid have been described, and the diagnosis critically relies on immunopathological findings. We describe three bullous pemphigoid patients characterized by palmoplantar keratoderma, diffused hyperkeratotic cutaneous lesions and extremely high levels of immunoglobulin E serum. The diagnosis of bullous pemphigoid should be taken into account in patients presenting diffused hyperkeratotic cutaneous lesions and palmoplantar keratoderma, even in the absence of blisters. Alteration of the keratinization process, that could occur in patients with genetic mutations in desmosomal and hemidesmosomal genes, may also be due to circulating autoantibodies against hemidesmosomal proteins in these bullous pemphigoid patients.

Differential role of transcription-coupled repair in UVB-induced response of human fibroblasts and keratinocytes.

Most solar radiation-induced skin cancers arise in keratinocytes. In the human epidermis, protection against cancer is thought to be mediated mainly by nucleotide excision repair (NER) of UVB-induced cyclobutane pyrimidine dimers, and by elimination of the damaged cells by apoptosis. NER consists of two subpathways: global genome repair (GGR) and transcription-coupled repair (TCR). Here, we investigate the impact of defects in NER subpathways on the cellular response to UVB-induced damage by comparing primary human keratinocytes and fibroblasts from normal, XP-C (GGR-defective), and CS-A (TCR-defective) individuals. We show that human keratinocytes are more resistant to UVB killing than fibroblasts and present higher levels of UVB-induced DNA repair synthesis due to a more efficient GGR. The CS-A defect is associated with a strong apoptotic response in fibroblasts but not in keratinocytes. Following an UVB dose of 1,000 J/m(2), no p53-mediated transactivation of mdm2 is observed in CS-A fibroblasts, whereas the p53-mdm2 circuit is fully activated in CS-A keratinocytes. Thus, in fibroblasts, the signal for apoptosis originates from DNA photoproducts in the transcribed strand of active genes, whereas in keratinocytes, it is largely TCR-independent. This study shows that the response to UVB radiation is cell type-specific in humans and provides the first evidence that a deficiency in TCR has a different impact depending on the cell type. These findings have important implications for the mechanism of skin cancer protection after UVB damage and may explain the lack of skin cancer in patients with Cockayne syndrome.

Laminin-5 mutational analysis in an Italian cohort of patients with junctional epidermolysis bullosa.

Junctional epidermolysis bullosa (JEB) is a rare genodermatosis characterized by dermal-epidermal separation that is caused by mutations in the genes encoding hemidesmosomal components and laminin-5, the major epithelial adhesion ligand. Here, we report on the mutational analysis of LAMA3, LAMB3, and LAMC2 genes encoding laminin-5 chains in 19 Italian patients, 11 affected with the severe Herlitz (H JEB) and eight with the mild non-Herlitz variant of JEB (non-H JEB). Eighteen mutations, seven of which were novel, were identified and their consequences analyzed at the mRNA and protein level. Premature termination codon mutations in both alleles of LAMB3 or LAMC2 genes were found in nine of the 11 H JEB patients, with a prevalence of mutations in LAMC2. In one case, a homozygous frameshift mutation in LAMB3 was associated to illegitimate splicing leading to non-H JEB. One H JEB patient showed a large intragenic duplication within LAMC2, a genetic defect so far uncovered in laminin-5 genes. Splicing or missense mutations, were prevalent in non-H JEB patients. Collectively, five mutations appeared to be frequent in laminin-5 JEB patients: R635X, 29insC, E210K, W143X in LAMB3 and R95X in LAMC2. These recurrent mutations account for approximately 44% of laminin-5 JEB alleles in Italian patients.

The atypical retinoid E-3-(3'-Adamantan-1-yl-4'-methoxybiphenyl-4-yl)-2-propenoic acid (ST1898) displays comedolytic activity in the rhino mouse model.

Retinoids represent the first-line therapy for the treatment of acne vulgaris. Their effect is comedolytic and anti-comedogenic, and associates with hyperplasia and deregulated differentiation of the epidermis, and decreased inflammation. We here tested the comedolytic effect of the novel atypical retinoid E-3-(3'-Adamantan-1-yl-4'-methoxybiphenyl-4-yl)-2-propenoic acid (ST1898) in the rhino mouse, as a model of comedogenic acne, and compared this effect to that of adapalene (Differin® gel), as reference compound. Topical administration of 0.1% ST1898 for three weeks exerted a comedolytic effect comparable to that of adapalene 0.1%. In ST1898-treated mice, epidermal hyperplasia was significantly reduced and the expression of keratinocyte differentiation markers was less perturbed compared to adapalene-treated animals. Moreover, keratin 6, which stains activated keratinocytes, was strongly and uniformly induced in interfollicular epidermis of adapalene-treated mice, while only faintly and focally expressed in ST1898-treated ones. Our data indicate that ST1898 has strong comedolytic activity but modest topical side effects.

Impaired keratinocyte proliferative and clonogenic potential in transgenic mice overexpressing 14-3-3σ in the epidermis.

The 14-3-3 protein family controls diverse biochemical processes through interaction with phosphorylated consensus sequences in protein targets. Its epithelial specific member, 14-3-3σ, also known as stratifin, is highly expressed in differentiated keratinocytes, and in vitro evidence indicates that 14-3-3σ downregulation leads to keratinocyte immortalization. To define the role of 14-3-3σ in skin homeostasis in vivo, we generated transgenic mice overexpressing 14-3-3σ in proliferating keratinocytes of the epidermis and hair follicle. Transgenic animals show decreased epidermal thickness and hair follicle density associated with reduced number of proliferating keratinocytes and decreased levels of keratins 14, 5, and 15. Primary keratinocytes isolated from transgenic mice manifest reduced proliferation and migration. Moreover, clonogenicity assessment and label-retaining analysis reveal a reduction in keratinocyte progenitor cell number in transgenic mice. Response to IGF-1 is strongly impaired in cultured transgenic keratinocytes compared with wild-type cells. Consistently, activation of phosphoinositol 3-kinase (PI3K), AKT, and Rac1, all IGF-1 downstream mediators, is reduced. Our results demonstrate that 14-3-3σ controls the in vivo epidermal proliferation-differentiation switch by reducing proliferative potential and forcing keratinocytes to exit the cell cycle, and that this effect associates with inhibition of the IGF-1 pathway.

Increased melanoma growth and metastasis spreading in mice overexpressing placenta growth factor.

Placenta growth factor (PlGF), a member of the vascular endothelial growth factor family, plays an important role in adult pathological angiogenesis. To further investigate PlGF functions in tumor growth and metastasis formation, we used transgenic mice overexpressing PlGF in the skin under the control of the keratin 14 promoter. These animals showed a hypervascularized phenotype of the skin and increased levels of circulating PlGF with respect to their wild-type littermates. Transgenic mice and controls were inoculated intradermally with B16-BL6 melanoma cells. The tumor growth rate was fivefold increased in transgenic animals compared to wild-type mice, in the presence of a similar percentage of tumor necrotic tissue. Tumor vessel area was increased in transgenic mice as compared to controls. Augmented mobilization of endothelial and hematopoietic stem cells from the bone marrow was observed in transgenic animals, possibly contributing to tumor vascularization. The number and size of pulmonary metastases were significantly higher in transgenic mice compared to wild-type littermates. Finally, PlGF promoted tumor cell invasion of the extracellular matrix and increased the activity of selected matrix metalloproteinases. These findings indicate that PlGF, in addition to enhancing tumor angiogenesis and favoring tumor growth, may directly influence melanoma dissemination.

A missense mutation (G1506E) in the adhesion G domain of laminin-5 causes mild junctional epidermolysis bullosa.

Laminin-5 is the major adhesion ligand for epithelial cells. Mutations in the genes encoding laminin-5 cause junctional epidermolysis bullosa (JEB), a recessive inherited disease characterized by extensive epithelial-mesenchymal disadhesion. We describe a JEB patient compound heterozygote for two novel mutations in the gene (LAMA3) encoding the laminin alpha3 chain. The maternal mutation (1644delG) generates mRNA transcripts that undergo nonsense-mediated decay. The paternal mutation results in the Gly1506-->Glu substitution (G1506E) within the C-terminal globular region of the alpha3 chain (G domain). Mutation G1506E affects the proper folding of the fourth module of the G domain and results in the retention of most of the mutated polypeptide within the endoplasmic reticulum (ER). However, scant amounts of the mutated laminin-5 are secreted, undergo physiologic extracellular maturation, and correctly localize within the cutaneous basement membrane zone in patient's skin. Our findings represent the first demonstration of an ER-retained mutant laminin-5 leading to a mild JEB phenotype.