Hair follicle stem cell progeny heal blisters while pausing skin development.

Injury in adult tissue generally reactivates developmental programs to foster regeneration, but it is not known whether this paradigm applies to growing tissue. Here, by employing blisters, we show that epidermal wounds heal at the expense of skin development. The regenerated epidermis suppresses the expression of tissue morphogenesis genes accompanied by delayed hair follicle (HF) growth. Lineage tracing experiments, cell proliferation dynamics, and mathematical modeling reveal that the progeny of HF junctional zone stem cells, which undergo a morphological transformation, repair the blisters while not promoting HF development. In contrast, the contribution of interfollicular stem cell progeny to blister healing is small. These findings demonstrate that HF development can be sacrificed for the sake of epidermal wound regeneration. Our study elucidates the key cellular mechanism of wound healing in skin blistering diseases.

Detection of revertant mosaicism in epidermolysis bullosa through Cas9-targeted long-read sequencing.

Revertant mosaicism (RM) is a phenomenon in which inherited mutations are spontaneously corrected in somatic cells. RM occurs in some congenital skin diseases, but genetic validation of RM in clinically revertant skin has been challenging, especially when homologous recombination (HR) is responsible for RM. Here, we introduce nanopore Cas9-targeted sequencing (nCATS) for identifying HR in clinically revertant skin. We took advantage of compound heterozygous COL7A1 mutations in a patient with recessive dystrophic epidermolysis bullosa who showed revertant skin spots. Cas9-mediated enrichment of genomic DNA (gDNA) covering the two mutation sites (>8 kb) in COL7A1 and subsequent MinION sequencing successfully detected intragenic crossover in the epidermis of the clinically revertant skin. This method enables the discernment of haplotypes of up to a few tens of kilobases of gDNA. Moreover, it is devoid of polymerase chain reaction amplification, which can technically induce recombination. We, therefore, propose that nCATS is a powerful tool for understanding complicated gene modifications, including RM.

Cas9-guided haplotyping of three truncation variants in autosomal recessive disease.

An autosomal recessive disease is caused by biallelic loss-of-function mutations. However, when more than two disease-causing variants are found in a patient's gene, it is challenging to determine which two of the variants are responsible for the disease phenotype. Here, to decipher the pathogenic variants by precise haplotyping, we applied nanopore Cas9-targeted sequencing (nCATS) to three truncation COL7A1 variants detected in a patient with recessive dystrophic epidermolysis bullosa (EB). The distance between the most 5' and 3' variants was approximately 19 kb at the level of genomic DNA. nCATS successfully demonstrated that the most 5' and 3' variants were located in one allele while the variant in between was located in the other allele. Interestingly, the proband's mother, who was phenotypically intact, was heterozygous for the allele that harbored the two truncation variants, which could otherwise be misinterpreted as those of typical recessive dystrophic EB. Our study highlights the usefulness of nCATS as a tool to determine haplotypes of complicated genetic cases. Haplotyping of multiple variants in a gene can determine which variant should be therapeutically targeted when nucleotide-specific gene therapy is applied.

Collagen XVII deficiency alters epidermal patterning.

Vertebrates exhibit patterned epidermis, exemplified by scales/interscales in mice tails and grooves/ridges on the human skin surface (microtopography). Although the role of spatiotemporal regulation of stem cells (SCs) has been implicated in this process, the mechanism underlying the development of such epidermal patterns is poorly understood. Here, we show that collagen XVII (COL17), a niche for epidermal SCs, helps stabilize epidermal patterns. Gene knockout and rescue experiments revealed that COL17 maintains the width of the murine tail scale epidermis independently of epidermal cell polarity. Skin regeneration after wounding was associated with slender scale epidermis, which was alleviated by overexpression of human COL17. COL17-negative skin in human junctional epidermolysis bullosa showed a distinct epidermal pattern from COL17-positive skin that resulted from revertant mosaicism. These results demonstrate that COL17 contributes to defining mouse tail scale shapes and human skin microtopography. Our study sheds light on the role of the SC niche in tissue pattern formation.

Type XVII collagen interacts with the aPKC-PAR complex and maintains epidermal cell polarity.

Type XVII collagen (COL17) is a transmembrane protein expressed in the basal epidermis. COL17 serves as a niche for epidermal stem cells, and although its reduction has been implicated in altering cell polarity and ageing of the epidermis, it is unknown how COL17 affects epidermal cell polarity. Here, we uncovered COL17 as a binding partner of the aPKC-PAR complex, which is a key regulating factor of cell polarity. Immunoprecipitation-immunoblot assay and protein-protein binding assay revealed that COL17 interacts with aPKC and PAR3. COL17 deficiency or epidermis-specific aPKCλ deletion destabilized PAR3 distribution in the epidermis, while aPKCζ knockout did not. Asymmetrical cell division was pronounced in COL17-null neonatal paw epidermis. These results show that COL17 is pivotal for maintaining epidermal cell polarity. Our study highlights the previously unrecognized role of COL17 in the basal keratinocytes.

Two Cases of Interleukin-7-Deficient Generalized Verrucosis.

We report 2 generalized verrucosis (GV) patients homozygous for a novel mutation in the start codon of IL7. Unlike the previous report in which IL-7 deficiency accompanied CD4 T lymphocytopenia, circulating CD4 T cells were not depleted in one of our patients, suggesting a GV pathogenesis other than poor T-cell development.

Electron Microscopic and Immunohistochemical Findings of the Epidermal Basement Membrane in Two Families with Nail-patella Syndrome.

Nail-patella syndrome is an autosomal dominant disorder characterized by nail dysplasia and skeletal anomaly. Some patients have been shown to have ultrastructural abnormalities of the glomerular basement membrane that result in nephrosis. However, little has been reported on the epidermal basement membrane in this condition. This paper reports 2 families with nail-patella syndrome. Direct sequencing analysis of LMX1B revealed that family 1 and family 2 were heterozygous for the mutations c.140-1G>C and c.326+1G>C, respectively. To evaluate the epidermal basement membrane zone, ultrastructural and immunohistochemical analyses were performed using skin specimens obtained from the dorsal thumb. Electron microscopy showed intact hemidesmosomes, lamina lucida, lamina densa, and anchoring fibrils. Immunofluorescence studies with antibodies against components of the epidermal basement membrane zone revealed a normal expression pattern among the components, including type IV collagen. These data suggest that nail dysplasia in patients with nail-patella syndrome is not caused by structural abnormalities of the epidermal basement membrane.

Alternative mRNA splicing events and regulators in epidermal differentiation.

Alternative splicing (AS) of messenger RNAs occurs in ∼95% of multi-exon human genes and generates diverse RNA and protein isoforms. We investigated AS events associated with human epidermal differentiation, a process crucial for skin function. We identified 6,413 AS events, primarily involving cassette exons. We also predicted 34 RNA-binding proteins (RBPs) regulating epidermal AS, including 19 previously undescribed candidate regulators. From these results, we identified FUS as an RBP that regulates the balance between keratinocyte proliferation and differentiation. Additionally, we characterized the function of a cassette exon AS event in MAP3K7, which encodes a kinase involved in cell signaling. We found that a switch from the short to long isoform of MAP3K7, triggered during differentiation, enforces the demarcation between proliferating basal progenitors and overlying differentiated strata. Our findings indicate that AS occurs extensively in the human epidermis and has critical roles in skin homeostasis.

Dermal discoloration due to osmium tetroxide.

INTRODUCTION: Osmium tetroxide is a strong oxidizing agent. After dermal exposure to osmium tetroxide, skin discoloration and red papules can occur. We describe a patient with skin discoloration due to osmium tetroxide. CASE SUMMARY: A 25-year-old postgraduate student unintentionally exposed his hand to osmium tetroxide while working in a laboratory setting. After immediate washing, he sought medical care due to left middle finger discoloration. He reported no discomfort in the affected area. Thorough water rinsing was continued, and corticosteroid ointment was applied. IMAGES: Our patient developed dark brown pigmentation on the ventral side of the left middle finger. The pigmentation disappeared one week later. CONCLUSION: Osmium tetroxide may induce dark brown skin discoloration.

Development of a nutritionally balanced, melt-in-the-mouth chocolate for patients with epidermolysis bullosa.

Epidermolysis bullosa (EB) is a group of inherited blistering disorders that primarily affect the skin and mucous membranes of the digestive tract, which can lead to poor nutritional status. Dietary supplements and nutritional support methods, such as nasogastric tubes and gastrostomy, have been employed to improve the nutritional status of patients with EB; however, few foods are suitable for enjoyable eating with family and friends. Here, we introduce a nutritionally balanced, melt-in-the-mouth chocolate called andew, which was specifically designed for patients with EB. The andew chocolate is nutritionally superior and melts more easily than traditional chocolates, thus it is suitable for patients with EB, who are prone to oral erosions. Patients responded more favorably to the taste and texture of andew than to those of other dietary supplements. Not only does andew provide nutritional benefits, but it also promotes enjoyable eating with family members and friends, which could positively impact patients' mental health.

Safety and dose-sparing effect of Japanese encephalitis vaccine administered by microneedle patch in uninfected, healthy adults (MNA-J): a randomised, partly blinded, active-controlled, phase 1 trial.

BACKGROUND: It is unclear whether microneedle vaccinations of Japanese encephalitis virus can induce sufficient neutralising antibodies and reduce the amount of vaccine needed. We aimed to assess the safety and dose-sparing effect of a microneedle vaccine patch against Japanese encephalitis in healthy individuals who are naive to both the vaccine and natural infection. METHODS: The MNA-J study was a randomised, partly blinded, active-controlled, phase 1 clinical trial at Hokkaido University (Sapporo, Japan) that enrolled healthy adults aged 20-34 years with no history of Japanese encephalitis vaccination nor of infection as confirmed by seronegativity. We excluded individuals who had been infected with or vaccinated against Japanese encephalitis. Eligible participants were randomly assigned (1:1:1) to one of three groups to receive inactivated Japanese encephalitis vaccine administered twice, 3 weeks apart, by either 2·5 µg per injection by subcutaneous injection, 0·63 µg per patch by high-dose microneedle array (MNA-25%), or 0·25 µg per patch by low-dose microneedle array (MNA-10%). The randomisation sequence, using stratification by cohort and blocks of six, was computer-generated by a statistician who was unaware of group assignment. After administration, the remaining amount of unadministered vaccine was measured by ELISA and calculated as the delivered amount of vaccine. The primary outcome was the neutralising antibody titre at day 42 after first immunisation. Successful seroconversion was defined as post-vaccination titres of 1·3 (log10) or higher in individuals whose pre-vaccination titres had been less than 1 (log10). This study is registered with the Japan Registry of Clinical Trials (s011190004). FINDINGS: Between Aug 31 and Sept 2, 2019, 39 participants were enrolled and each was randomly assigned to a group (n=13 per group). No serious adverse events were observed. All participants in the microneedle array groups had a localised erythematous reaction. The amount of vaccine delivered by microneedle array to each participant was 0·63-1·15 µg (50-92%) of the full 1·26 µg for the MNA-25% group and 0·25-0·41 µg (51-84%) of the full 0·50 µg for the MNA-10% group. All participants demonstrated seroconversion at day 42, and the mean titres (log10) were 2·55 for MNA-25%, 2·04 for MNA-10%, and 2·08 for subcutaneous injection. INTERPRETATION: A microneedle patch of the Japanese encephalitis vaccine is safe, well tolerated, and immunogenically effective. The dose-sparing effect suggests a significant potential to reduce the amount of immunogens needed. However, improved delivery is needed to make it more tolerable and user friendly. FUNDING: FUJIFILM.

Dominance of Methicillin-Resistant Staphylococcus aureus in a Japanese Infant with Recessive Dystrophic Epidermolysis Bullosa.

A male infant had the very fragile skin and easily formed bullas by rubbing and scratching from his birth. He was diagnosed with severe recessive dystrophic epidermolysis bullosa (RDEB) due to the lack of type VII collagen by performing an immunofluorescence mapping method from a skin biopsy specimen of the patient's bulla. We analyzed the skin microbiome using next-generation sequencer. The species from the patient's skin revealed the dominance of Staphylococcus aureus (S. aureus) similar to the reports from Austria and Chile severe RDEB patients, and these results are same as the pattern isolated from the skin of atopic dermatitis (AD) patients with flares. The interaction of microbiome and skin microenvironment may be similar between RDEB and AD worldwide.

Efficient Gene Reframing Therapy for Recessive Dystrophic Epidermolysis Bullosa with CRISPR/Cas9.

The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system induces site-specific double-strand breaks, which stimulate cellular DNA repair through either the homologous recombination or non-homologous end-joining pathways. The non-homologous end-joining pathway, which is activated more frequently than homologous recombination, is prone to introducing small insertions and/or deletions at the double-strand break site, leading to changes in the reading frame. We hypothesized that the non-homologous end-joining pathway is applicable to genetic diseases caused by a frameshift mutation through restoration of the reading frame. Recessive dystrophic epidermolysis bullosa is a hereditary skin disorder caused by mutations in COL7A1. In this study, we applied gene reframing therapy to a recurrent frameshift mutation, c.5819delC, in COL7A1, which results in a premature termination codon. CRISPR/Cas9 targeting this specific mutation site was delivered to recessive dystrophic epidermolysis bullosa patient fibroblasts. After genotyping a large collection of gene-edited fibroblast clones, we identified a significant number (17/50) of clones in which the frameshift in COL7A1 was restored. The reframed COL7 was functional, as shown by triple-helix formation assay in vitro, and was correctly distributed in the basement membrane zone in mice. Our data suggest that mutation site-specific non-homologous end-joining might be a highly efficient gene therapy for inherited disorders caused by frameshift mutations.

Cultured Epidermal Autografts from Clinically Revertant Skin as a Potential Wound Treatment for Recessive Dystrophic Epidermolysis Bullosa.

Inherited skin disorders have been reported recently to have sporadic normal-looking areas, where a portion of the keratinocytes have recovered from causative gene mutations (revertant mosaicism). We observed a case of recessive dystrophic epidermolysis bullosa treated with cultured epidermal autografts (CEAs), whose CEA-grafted site remained epithelized for 16 years. We proved that the CEA product and the grafted area included cells with revertant mosaicism. Based on these findings, we conducted an investigator-initiated clinical trial of CEAs from clinically revertant skin for recessive dystrophic epidermolysis bullosa. The donor sites were analyzed by genetic analysis, immunofluorescence, electron microscopy, and quantification of the reverted mRNA with deep sequencing. The primary endpoint was the ulcer epithelization rate per patient at 4 weeks after the last CEA application. Three patients with recessive dystrophic epidermolysis bullosa with 8 ulcers were enrolled, and the epithelization rate for each patient at the primary endpoint was 87.7%, 100%, and 57.0%, respectively. The clinical effects were found to persist for at least 76 weeks after CEA transplantation. One of the three patients had apparent revertant mosaicism in the donor skin and in the post-transplanted area. CEAs from clinically normal skin are a potentially well-tolerated treatment for recessive dystrophic epidermolysis bullosa.

The development of induced pluripotent stem cell-derived mesenchymal stem/stromal cells from normal human and RDEB epidermal keratinocytes.

BACKGROUND: Epidermolysis bullosa (EB) is a group of hereditary disorders caused by mutations in the genes encoding structural molecules of the dermal-epidermal junction (DEJ). Cell-based therapies such as allogeneic mesenchymal stem/stromal cell (MSC) transplantation have recently been explored for severe EB types, such as recessive dystrophic EB (RDEB). However, hurdles exist in current MSC-based therapies, such as limited proliferation from a single cell source and limited cell survival due to potential allogenic rejection. OBJECTIVES: We aimed to develop MSCs from keratinocyte-derived induced pluripotent stem cells (iPSCs). METHODS: Keratinocyte-derived iPSCs (KC-iPSCs) of a healthy human and an RDEB patient were cultured with activin A, 6-bromoindirubin-3'-oxime and bone morphogenetic protein 4 to induce mesodermal lineage formation. These induced cells were subjected to immunohistochemical analysis, flow cytometric analysis and RNA microarray analysis in vitro, and were injected subcutaneously and intravenously to wounded immunodeficient mice to assess their wound-healing efficacy. RESULTS: After their induction, KC-iPSC-induced cells were found to be compatible with MSCs. Furthermore, with the subcutaneous and intravenous injection of the KC-iPSC-induced cells into wounded immunodeficient mice, human type VII collagen was detected at the DEJ of epithelized areas. CONCLUSIONS: We successfully established iPSC-derived MSCs from keratinocytes (KC-iPSC-MSCs) of a normal human and an RDEB patient. KC-iPSC-MSCs may have potential in therapies for RDEB.