Shotaro Suzuki

Impaired Epidermal Permeability Barrier in Mice Lacking Elovl1, the Gene Responsible for Very-Long-Chain Fatty Acid Production

ABSTRACT The sphingolipid backbone ceramide (Cer) is a major component of lipid lamellae in the stratum corneum of epidermis and has a pivotal role in epidermal barrier formation. Unlike Cers in other tissues, Cers in epidermis contain extremely long fatty acids (FAs). Decreases in epidermal Cer levels, as well as changes in their FA chain lengths, cause several cutaneous disorders. However, the molecular mechanisms that produce such extremely long Cers and determine their chain lengths are poorly understood. We generated mice deficient in the Elovl1 gene, which encodes the FA elongase responsible for producing C20 to C28 FAs. Elovl1 knockout mice died shortly after birth due to epidermal barrier defects. The lipid lamellae in the stratum corneum were largely diminished in these mice. In the epidermis of the Elovl1-null mice, the levels of Cers with ≥C26 FAs were decreased, while those of Cers with ≤C24 FAs were increased. In contrast, the levels of C24 sphingomyelin were reduced, accompanied by an increase in C20 sphingomyelin levels. Two ceramide synthases, CerS2 and CerS3, expressed in an epidermal layer-specific manner, regulate Elovl1 to produce acyl coenzyme As with different chain lengths. Elovl1 is a key determinant of epidermal Cer chain length and is essential for permeability barrier formation.

An annexin A1–FPR1 interaction contributes to necroptosis of keratinocytes in severe cutaneous adverse drug reactions

Annexin A1 secreted from drug-stimulated monocytes contributes to keratinocyte necroptosis in serious drug-related adverse events in skin. Subduing a Severe Skin Side Effect Certain pain relievers and antiepileptic drugs can cause a very rare, but sometimes fatal, side effect in which skin painfully blisters and peels, caused by the patients’ immune response to the drug. Saito et al. now find that, in susceptible patients, the drug causes secretion of the protein annexin A1 from immune cells, with deadly effect on skin cells. Annexin acts on these cells to cause necroptosis, a programmed form of cell death. The authors confirmed their results in mice, showing that an inhibitor of necroptosis blocked skin blistering. With these findings, Saito et al. lay the groundwork for a countermeasure to this dangerous side effect of otherwise extremely beneficial drugs. Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening, cutaneous adverse drug reactions that are accompanied by keratinocyte cell death. Dead keratinocytes from SJS/TEN lesions exhibited necrosis, by morphological criteria. Supernatant from peripheral blood mononuclear cells (PBMCs) that had been exposed to the causative drug from patients with SJS/TEN induced the death of SJS/TEN keratinocytes, whereas supernatant from PBMCs of patients with ordinary drug skin reactions (ODSRs) exposed to the same drug did not. Keratinocytes from ODSR patients or from healthy controls were unaffected by supernatant from SJS/TEN or ODSR PBMCs. Mass spectrometric analysis identified annexin A1 as a key mediator of keratinocyte death; depletion of annexin A1 by a specific antibody diminished supernatant cytotoxicity. The necroptosis-mediating complex of RIP1 and RIP3 was indispensable for SJS/TEN supernatant–induced keratinocyte death, and SJS/TEN keratinocytes expressed abundant formyl peptide receptor 1 (FPR1), the receptor for annexin A1, whereas control keratinocytes did not. Inhibition of necroptosis completely prevented SJS/TEN-like responses in a mouse model of SJS/TEN. Our results demonstrate that a necroptosis pathway, likely mediated by annexin 1 acting through the FPR1 receptor, contributes to SJS/TEN.

Comprehensive screening for a complete set of Japanese‐population‐specific filaggrin gene mutations

Mutations in FLG coding profilaggrin cause ichthyosis vulgaris and are an important predisposing factor for atopic dermatitis. Until now, most case–control studies and population‐based screenings have been performed only for prevalent mutations. In this study, we established a high‐throughput FLG mutation detection system by real‐time PCR with a set of two double‐dye probes and conducted comprehensive screening for almost all of the Japanese‐population‐specific FLG mutations (ten FLG mutations). The present comprehensive screening for all ten FLG mutations provided a more precise prevalence rate for FLG mutations (11.1%, n = 820), which seemed high compared with data of previous reports based on screening for limited numbers of FLG mutations. Our comprehensive screening suggested that population‐specific FLG mutations may be a significant predisposing factor for hay fever (odds ratio = 2.01 [95% CI: 1.027–3.936, P < 0.05]), although the sample sizes of this study were too small for reliable subphenotype analysis on the association between FLG mutations and hay fever in the eczema patients and the noneczema individuals, and it is not clear whether the association between FLG mutations and hay fever is due to the close association between FLG mutations and hay fever patients with eczema.

Type XVII collagen coordinates proliferation in the interfollicular epidermis

Type XVII collagen (COL17) is a transmembrane protein located at the epidermal basement membrane zone. COL17 deficiency results in premature hair aging phenotypes and in junctional epidermolysis bullosa. Here, we show that COL17 plays a central role in regulating interfollicular epidermis (IFE) proliferation. Loss of COL17 leads to transient IFE hypertrophy in neonatal mice owing to aberrant Wnt signaling. The replenishment of COL17 in the neonatal epidermis of COL17-null mice reverses the proliferative IFE phenotype and the altered Wnt signaling. Physical aging abolishes membranous COL17 in IFE basal cells because of inactive atypical protein kinase C signaling and also induces epidermal hyperproliferation. The overexpression of human COL17 in aged mouse epidermis suppresses IFE hypertrophy. These findings demonstrate that COL17 governs IFE proliferation of neonatal and aged skin in distinct ways. Our study indicates that COL17 could be an important target of anti-aging strategies in the skin. DOI: http://dx.doi.org/10.7554/eLife.26635.001

Highly prevalent SERPINB7 founder mutation causes pseudodominant inheritance pattern in Nagashima‐type palmoplantar keratosis

Nagashima‐type palmoplantar keratosis (NPPK) is a distinct autosomal recessive genodermatosis characterized by diffuse transgressive palmoplantar keratoderma (PPK). Very recently, putative loss‐of‐function mutations in SERPINB7, which encodes a member of the serine protease inhibitor superfamily and is abundantly expressed in the epidermis, have been identified as a cause of NPPK.

A novel NCSTN mutation alone may be insufficient for the development of familial hidradenitis suppurativa.

Familial hidradenitis suppurativa (familial HS; OMIM #142690) an autosomal dominant chronic inflammatory follicular occlue disease. The clinical features include comedones, recurrent aining sinuses, painful nodules, skin abscesses, dermal contracinvasive squamous cell carcinoma, based on the pathological findings. Genomic DNA of two affected and four unaffected members of the family with HS were obtained from peripheral blood or saliva using QIAamp DNA Blood Maxi Kit (Qiagen, Germantown, MD) or Oragene DNA Self-Collection Kit (DNA Genotek, Kanata, ON), respectively (Fig. 1C). The participants or their legal guardians gave written informed consent for mutation analysis in compliance w ap Un en Pr (N ph po 31 de p. id br Fi NC w et w (d w m en 16 pr res and disfiguring scars, mainly on the scalp, neck, axilla, groin d/or perianal and perineal regions. Familial cases showing tosomal dominant inheritance have been reported in one third HS patients. Recent studies have demonstrated that mutations the genes encoding g-secretase underlie some familial cases ith HS with complete penetrance, while significant interdividual variability of the disease severity was reported [1]. re we describe the first family with HS in which a g-secretase ne mutation does not completely segregate with the disease. A 62-year-old Japanese man presented with the chief complaint 7-cm-diameter ulcerative reddish-colored skin tumor on e anterior neck (Fig. 1A). Physical examination also revealed idespread sinuses, comedones, pustules, inflamed cysts, skin scesses, disfiguring scars and post-inflammatory hyperpigmention on the face, neck, trunk and buttocks (Fig. 1A and B), where had had recurrent episodes of bacterial skin infection since the e of 15. The patient has no significant past medical history cluding diabetes mellitus. He has a positive family history, as his der brother (II-1) and his son (III-1) had similar infectious skin sions on the neck and back (Fig. 1C). A diagnosis of familial HS as made, as the patient and two other individuals in his family lfilled the diagnostic criteria of HS [2], the other individuals in e family did not meet the criteria (Fig. 1C). The skin tumor on the ck was completely excised and subsequently diagnosed as

Loss-of-function mutations in the gene encoding filaggrin underlie a Japanese family with food-dependent exercise-induced anaphylaxis.

Food‐dependent exercise‐induced anaphylaxis (FDEIA) is a serious food allergy in which anaphylaxis develops when exercise is performed within several hours after food intake. The precise mechanism underlying allergic sensitization in FDEIA has been an important issue but remains poorly understood.

Punctate palmoplantar keratoderma type 1: a novel AAGAB mutation and efficacy of etretinate.

Punctate palmoplantar keratoderma type 1 (PPKP1, OMIM#148600), also known as the Buschke-FischerBraurer type, is a rare form of palmoplantar keratoderma that is autosomal dominantly inherited (1). PPKP1 is clinically characterised by multiple punctate hyperkeratotic papules affecting the palmar and plantar skin, with considerable phenotypic variation among patients (2). These circumscribed papules gradually coalesce and increase in number with age (2). The lesions typically start to appear in early adolescence but sometimes develop later in life. In 2012, linkage analysis and whole-exome sequencing identified heterozygous null mutations within AAGAB as a cause of PPKP1 (2, 3). AAGAB encodes αand γ-adaptin binding protein p34, which is involved in clathrin-mediated vesicle transport (2). Loss-of-function mutations in AAGAB result in haploinsufficiency of p34 (2). To date, 20 AAGAB null variants have been identified in Scottish, Irish, English, German, Tunisian, Chinese Mexican and Japanese populations (2–8). Here we report a Japanese case with PPKP1 carrying a novel AAGAB null mutation.

Filaggrin Mutation in Korean Patients with Atopic Dermatitis

Purpose Atopic dermatitis (AD) is a chronic, relapsing eczematous inflammatory skin disease. Mutations in the filaggrin gene (FLG) are major predisposing factors for AD. Ethnic differences exist between Asian and European populations in the frequency and spectrum of FLG mutations. Moreover, a distinct set of FLG mutations has been reported in Asian populations. The aim of this study was to examine the spectrum of FLG mutations in Koreans with AD. We also investigated the association of FLG mutations and clinical features of AD and compared the Korean FLG landscape with that of other East Asian countries. Materials and Methods Seventy Korean patients with AD were enrolled in this study. Fourteen FLG mutations previously detected in Korean, Japanese, and Chinese patients were screened by genotyping. Results Four FLG null mutations (3321delA, K4022X, S3296X, and S2889X) were identified in eleven patients (15.7%). The most commonly detected mutations in Korean patients with AD were 3321delA (n=6, 9.1%) and K4022X (n=3, 4.5%). FLG mutations were significantly associated with elevated IgE (≥200 KIU/L and/or MAST-CLA >3+, p=0.005), palmar hyperlinearity (p<0.001), and a family history of allergic disease (p=0.021). Conclusion This study expanded our understanding of the landscape of FLG mutations in Koreans and revealed an association between FLG mutations and AD phenotype.

Establishment of integration-free induced pluripotent stem cells from human recessive dystrophic epidermolysis bullosa keratinocytes

BACKGROUND Induced pluripotent stem cell (iPSC) technology enables patient-specific pluripotent stem cells to be derived from adult somatic cells without the use of an embryonic cell source. To date, recessive dystrophic epidermolysis bullosa (RDEB)-specific iPSCs have been generated from patients using integrating retroviral vectors. However, vector integration into the host genome can endanger the biosafety and differentiation propensities of iPSCs. Although various integration-free reprogramming systems have been reported, their utility in reprogramming somatic cells from patients remains largely undetermined. OBJECTIVE Our study aims to establish safe iPSCs from keratinocytes of RDEB patients using non-integration vector. METHOD We optimized and infected non-integrating Sendai viral vectors to reprogram keratinocytes from healthy volunteers and RDEB patients. RESULTS Sendai vector infection led to the reproducible generation of genomic modification-free iPSCs from these keratinocytes, which was proved by immunohistochemistry, reverse transcription polymerase chain reaction, methylation assay, teratoma assay and embryoid body formation assay. Furthermore, we confirmed that these iPSCs have the potential to differentiate into dermal fibroblasts and epidermal keratinocytes. CONCLUSION This is the first report to prove that the Sendai vector system facilitates the reliable reprogramming of patient keratinocytes into transgene-free iPSCs, providing another pluripotent platform for personalized diagnostic and therapeutic approaches to RDEB.