Prevalence of inherited ichthyosis in France: a study using capture-recapture method

Background

Inherited ichthyoses represent a group of rare skin disorders characterized by scaling, hyperkeratosis and inconstant erythema, involving most of the tegument. Epidemiology remains poorly described. This study aims to evaluate the prevalence of inherited ichthyosis (excluding very mild forms) and its different clinical forms in France.

Methods

Capture – recapture method was used for this study. According to statistical requirements, 3 different lists (reference/competence centres, French association of patients with ichthyosis and internet network) were used to record such patients. The study was conducted in 5 areas during a closed period.

Results

The prevalence was estimated at 13.3 per million people (/M) (CI95%, [10.9 – 17.6]). With regard to autosomal recessive congenital ichthyosis, the prevalence was estimated at 7/M (CI 95% [5.7 – 9.2]), with a prevalence of lamellar ichthyosis and congenital ichthyosiform erythroderma of 4.5/M (CI 95% [3.7 – 5.9]) and 1.9/M (CI 95% [1.6 – 2.6]), respectively. Prevalence of keratinopathic forms was estimated at 1.1/M (CI 95% [0.9 – 1.5]). Prevalence of syndromic forms (all clinical forms together) was estimated at 1.9/M (CI 95% [1.6 – 2.6]).

Conclusions

Our results constitute a crucial basis to properly size the necessary health measures that are required to improve patient care and design further clinical studies.     

Impact of Metalloproteinase 1 Deficiency Induced by Specific Small Hairpin RNA on the Physiological Effects of Tumor Necrosis Factor

Matrix metalloproteinases play an important role in the pathogenesis of psoriasis. The aim of this paper was to explore the influence of MMP1 silencing with a specific shRNA on migration and proliferation of epidermal keratinocytes exposed to tumor necrosis factor, as well as changes in the expression of genes involved in their terminal differentiation. Changes in gene expression were analyzed by real-time PCR. The cell proliferation was assessed by comparative analysis of the growth curves. The cell migration was explored by scratch assay. To quantify cell migration, the representative areas of cell cultures were photographed in the equal periods of time and compared to each other. The obtained results demonstrated that an exposure of control cell line to tumor necrosis factor caused changes in the expression of several genes similar to ones that were previously observed in lesional psoriatic skin. Particularly, the expression of MMP9, IVL and KRT16 increased whereas the expression of LOR, KRT1 and-10—decreased. In contrast, MMP1-deficient cells treated with tumor necrosis factor exhibited higher levels of LOR, KRT1 and -10, as well as lower levels KRT16 and -17 compared to control cells treated with the same cytokines. Moreover, MMP1-deficient cells exhibited a lower level of CCNА2 and higher level of CCND1. In this respect, knocking MMP1 down resulted in a lower cell proliferation and migration rates of TNF-treated epidermal keratinocytes. In conclusion, this study demonstrated that MMP1 silencing with specific shRNA can be beneficial for psoriasis. We found that knocking MMP1 down has an antiproliferative effect on epidermal keratinocytes and partially normalizes the expression of cyclins CCNA2, and -D1, as well as the genes involved in the terminal differentiation of this kind of cells (LOR, KRT1, -10, -16 and -17).     

Molekulare Charakterisierung der Ichthyosen

Ichthyoses comprise an etiologically heterogeneous group of Mendelian disorders of cornification (MEDOC) that affect the entire integument and are characterized by hyperkeratosis and/or visible scaling. In recent years basic research has elucidated the genetic basis of almost all ichthyosis forms and enormously improved diagnostic facilities. The Network for Ichthyoses and Related Keratinization Disorders (NIRK; www.netzwerk-ichthyose.de) and the patient support organization Selbsthilfe Ichthyose e. V. (www.ichthyose.de) provide helpful contact points for physicians and patients in Germany. The first worldwide Ichthyosis Consensus Classification was approved in August 2009. Its nosology is based on clinical presentation but also reflects pathogenic aspects. The major criterion is the distinction between syndromic and non-syndromic forms. Controversial disease names have been re-defined: Ichthyoses due to keratin mutations are referred to under the new umbrella term keratinopathic ichthyosis (KPI), which comprises epidermolytic ichthyosis (mutation in keratin 1 or 10) and superficial epidermolytic ichthyosis (keratin 2). The term autosomal recessive congenital ichthyosis (ARCI) represents the umbrella for harlequin ichthyosis and for the group of lamellar ichthyosis and congenital ichthyosiform erythroderma. The international classification should serve as a reference for future research into these diseases, including further genotype-phenotype correlation studies.     

Loss of Corneodesmosin Leads to Severe Skin Barrier Defect, Pruritus, and Atopy: Unraveling the Peeling Skin Disease

Generalized peeling skin disease is an autosomal-recessive ichthyosiform erythroderma characterized by lifelong patchy peeling of the skin. After genome-wide linkage analysis, we have identified a homozygous nonsense mutation in CDSN in a large consanguineous family with generalized peeling skin, pruritus, and food allergies, which leads to a complete loss of corneodesmosin. In contrast to hypotrichosis simplex, which can be associated with specific dominant CDSN mutations, peeling skin disease is characterized by a complete loss of CDSN expression. The skin phenotype is consistent with a recent murine Cdsn knockout model. Using three-dimensional human skin models, we demonstrate that lack of corneodesmosin causes an epidermal barrier defect supposed to account for the predisposition to atopic diseases, and we confirm the role of corneodesmosin as a decisive epidermal adhesion molecule. Therefore, peeling skin disease will represent a new model disorder for atopic diseases, similarly to Netherton syndrome and ichthyosis vulgaris in the recent past.     

The roles of ABCA12 in epidermal lipid barrier formation and keratinocyte differentiation

ATP-binding cassette (ABC) transporters form a large superfamily of transporters that bind and hydrolyze ATP to transport various molecules across limiting membranes or into vesicles. The ABCA subfamily members are thought to transport lipid materials. ABCA12 is a keratinocyte transmembrane lipid transporter protein associated with the transport of lipids via lamellar granules. ABCA12 is considered to transport lipids including ceramides to form extracellular lipid layers in the stratum corneum of the epidermis, which is essential for skin barrier function. ABCA12 mutations are known to underlie the three major types of autosomal recessive congenital ichthyoses: harlequin ichthyosis, lamellar ichthyosis and congenital ichthyosiform erythroderma. ABCA12 mutations result in defective lipid transport via lamellar granules in the keratinocytes, leading to ichthyosis phenotypes from malformation of the stratum corneum lipid barrier. Studies on ABCA12-deficient bioengineered models have revealed that lipid transport by ABCA12 is required for keratinocyte differentiation and epidermal morphogenesis. Defective lipid transport due to loss of ABCA12 function leads to the accumulation of intracellular lipids, including glucosylceramides and gangliosides, in the epidermal keratinocytes. The accumulation of gangliosides seems to result in the apoptosis of Abca12^−/− keratinocytes. It was reported that AKT activation occurs in Abca12^−/− granular-layer keratinocytes, which suggests that AKT activation serves to prevent the cell death of Abca12^−/− keratinocytes. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.     

Cyclic ichthyosis with epidermolytic hyperkeratosis: A phenotype conferred by mutations in the 2B domain of keratin K1

Bullous congenital ichthyosiform erythroderma (BCIE) is characterized by blistering and erythroderma in infancy and by erythroderma and ichthyosis thereafter. Epidermolytic hyperkeratosis is a hallmark feature of light and electron microscopy. Here we report on four individuals from two families with a unique clinical disorder with histological findings of epidermolytic hyperkeratosis. Manifesting erythema and superficial erosions at birth, which improved during the first few months of life, affected individuals later developed palmoplantar hyperkeratosis with patchy erythema and scale elsewhere on the body. Three affected individuals exhibit dramatic episodic flares of annular, polycyclic erythematous plaques with scale, which coalesce to involve most of the body surface. The flares last weeks to months. In the interim periods the skin may be normal, except for palmoplantar hyperkeratosis. Abnormal keratin-filament aggregates were observed in suprabasal keratinocytes from both probands, suggesting that the causative mutation might reside in keratin K1 or keratin K10. In one proband, sequencing of K1 revealed a heterozygous mutation, 1436T-->C, predicting a change of isoleucine to threonine in the highly conserved helix-termination motif. In the second family, a heterozygous mutation, 1435A-->T, was found in K1, predicting an isoleucine-to-phenylalanine substitution in the same codon. Both mutations were excluded in both a control population and all unaffected family members tested. These findings reveal that a clinical phenotype distinct from classic BCIE but with similar histology can result from K1 mutations and that mutations at this codon give rise to a clinically unique condition.     

Ceramide Analysis in Combination With Genetic Testing May Provide a Precise Diagnosis for Self-Healing Collodion Babies

Self-healing collodion baby (SHCB), also called “self-improving collodion baby”, is a rare mild variant of autosomal recessive congenital ichthyosis and is defined as a collodion baby who shows the nearly complete resolution of scaling within the first 3 months to 1 year of life. However, during the neonatal period, it is not easy to distinguish SHCB from other inflammatory forms of autosomal recessive congenital ichthyosis, such as congenital ichthyosiform erythroderma. Here, we report a case study of two Japanese SHCB patients with compound heterozygous mutations, c.235G>T (p.(Glu791))/ c.1189C>T (p.(Arg397Cys)) and c.1295A>G (p.(Tyr432Cys))/ c.1138delG (p.(Asp380Thrfs13)), in CYP4F22, which encodes cytochrome P450, family 4, subfamily F, polypeptide 22 (CYP4F22). Immunohistochemically, inflammation with the strong expression of IL-17C, IL-36γ, and TNF-α was seen in the skin at birth. CYP4F22 is an ultra-long-chain FA ω-hydroxylase responsible for ω-O-acylceramide (acylceramide) production. Among the epidermal ceramides, acylceramide is a key lipid in maintaining the epidermal permeability barrier function. We found that the levels of ceramides with ω-hydroxy FAs including acylceramides and the levels of protein-bound ceramides were much lower in stratum corneum samples obtained by tape stripping from SHCB patients than in those from their unaffected parents and individuals without SHCB. Additionally, our cell-based enzyme assay revealed that two mutants, p.(Glu791) and p.(Arg397Cys), had no enzyme activity. Our findings suggest that genetic testing coupled with noninvasive ceramide analyses using tape-stripped stratum corneum samples might be useful for the early and precise diagnosis of congenital ichthyoses, including SHCB.     

A Spontaneous Fatp4/Scl27a4 Splice Site Mutation in a New Murine Model for Congenital Ichthyosis

Congenital ichthyoses are life-threatening conditions in humans. We describe here the identification and molecular characterization of a novel recessive mutation in mice that results in newborn lethality with severe congenital lamellar ichthyosis. Mutant newborns have a taut, shiny, non-expandable epidermis that resembles cornified manifestations of autosomal-recessive congenital ichthyosis in humans. The skin is stretched so tightly that the newborn mice are immobilized. The genetic defect was mapped to a region near the proximal end of chromosome 2 by SNP analysis, suggesting Fatp4/Slc27a4 as a candidate gene. FATP4 mutations in humans cause ichthyosis prematurity syndrome (IPS), and mutations of Fatp4 in mice have previously been found to cause a phenotype that resembles human congenital ichthyoses. Characterization of the Fatp4 cDNA revealed a fusion of exon 8 to exon 10, with deletion of exon 9. Genomic sequencing identified an A to T mutation in the splice donor sequence at the 3′-end of exon 9. Loss of exon 9 results in a frame shift mutation upstream from the conserved very long-chain acyl-CoA synthase (VLACS) domain. Histological studies revealed that the mutant mice have defects in keratinocyte differentiation, along with hyperproliferation of the stratum basale of the epidermis, a hyperkeratotic stratum corneum, and reduced numbers of secondary hair follicles. Since Fatp4 protein is present primarily at the stratum granulosum and the stratum spinosum, the hyperproliferation and the alterations in hair follicle induction suggest that very long chain fatty acids, in addition to being required for normal cornification, may influence signals from the stratum corneum to the basal cells that help to orchestrate normal skin differentiation.     

Downregulation of expression of mater genes <Emphasis Type="Italic">SOX9, FOXA2</Emphasis>, and <Emphasis Type="Italic">GATA4</Emphasis> in pancreatic cancer cells stimulated with TGFβ1 epithelial–mesenchymal transition

We show characteristic morphological changes corresponding to epithelial–mesenchymal transition (EMT) program fulfillment in PANC1 cell line stimulated with TGFβ1. Our results support downregulation of E-cadherin protein. We show 5- and 28-fold increase in SNAI1 and SNAI2 expression levels and 25- and 15-fold decrease in CDH1 and KRT8 expression levels, respectively, which confirms the EMT-program fulfillment. We demonstrate downregulation of expression of pancreatic master genes SOX9, FOXA2, and GATA4 (2-, 5-, and 4-fold, respectively) and absence of significant changes in HES1, NR5A2, and GATA6 expression levels in the cells stimulated with TGFβ1. Our results indicate the absence of induction of expression of PTF1A, PDX1, HNF1b, NEUROG3, RPBJL, NKX6.1, and ONECUT1 genes, which are inactive in PANC1 cell line after the EMT stimulated by TGFβ1.     

Structure and diversity of bacterial communities in the fermentation of da-jiang

Da-jiang is the traditional soybean fermented food which is popular in the world for a long time. In order to improve the quality and nutritional value of da-jiang, structure and diversity of bacterial communities in the fermentation of da-jiang were analyzed. Illumina MiSeq platforms coupled with bioinformatics approach were used in this study. In the first 28 days, the trends of bacterial abundance were similar in different regions which are increasing firstly, decreasing secondly, and rising again. The quantity of bacteria in post-fermentation is lower than pre-fermentation. In the fermentation of da-jiang, Firmicutes and Proteobacteria are the dominant phyla. The dominant genera in da-jiang from different regions are different: Tetragenococcus (58.1–73.0%) is the dominant genus in da-jiang from Xinmin; Leuconostoc (9.2–25.7%) is the dominant genus in da-jiang from Tieling; Acinetobacter (8.7–25.1%) and Leuconostoc (12.4–22.0%) are the dominant genera in da-jiang from Shenyang. Additionally, Weissella, Lactobacillus, Staphylococcus, Erwinia, and Pseudomonas also were found in da-jiang. It is identified that Leuconostoc steadily existed in all da-jiang samples. These results demonstrate the diversity of microbes in traditional fermented da-jiang, which will probably provide a data basis for choosing starter culture for da-jiang industrial fermentation.     

Arginine‐ but not alanine‐rich carboxy‐termini trigger nuclear translocation of mutant keratin 10 in ichthyosis with confetti

Ichthyosis with confetti (IWC) is a genodermatosis associated with dominant‐negative variants in keratin 10 (KRT10) or keratin 1 (KRT1). These frameshift variants result in extended aberrant proteins, localized to the nucleus rather than the cytoplasm. This mislocalization is thought to occur as a result of the altered carboxy (C)‐terminus, from poly‐glycine to either a poly‐arginine or ‐alanine tail. Previous studies on the type of C‐terminus and subcellular localization of the respective mutant protein are divergent. In order to fully elucidate the pathomechanism of IWC, a greater understanding is critical. This study aimed to establish the consequences for localization and intermediate filament formation of altered keratin 10 (K10) C‐termini. To achieve this, plasmids expressing distinct KRT10 variants were generated. Sequences encoded all possible reading frames of the K10 C‐terminus as well as a nonsense variant. A keratinocyte line was transfected with these plasmids. Additionally, gene editing was utilized to introduce frameshift variants in exon 6 and exon 7 at the endogenous KRT10 locus. Cellular localization of aberrant K10 was observed via immunofluorescence using various antibodies. In each setting, immunofluorescence analysis demonstrated aberrant nuclear localization of K10 featuring an arginine‐rich C‐terminus. However, this was not observed with K10 featuring an alanine‐rich C‐terminus. Instead, the protein displayed cytoplasmic localization, consistent with wild‐type and truncated forms of K10. This study demonstrates that, of the various 3′ frameshift variants of KRT10, exclusively arginine‐rich C‐termini lead to nuclear localization of K10.     

Identification of novel mutations in the ABCA12 gene,c.1857delA and c.5653–5655delTAT,causing harlequin ichthyosis

Harlequin ichthyosis (HI) is a severe autosomal recessive developmental disorder of the skin that is frequently but not always fatal in the first few days of life. In HI, mutations in both ABCA12 gene alleles must have a severe impact on protein function and most mutations are truncating. The presence of at least one nontruncating mutation (predicting a residual protein function) usually causes a less severe congenital ichthyosis (lamellar ichthyosis or congenital ichthyosiform erythroderma). Here we report on a girl with severe HI diagnosed by prenatal ultrasound at 33 5/7 week gestation. Ultrasound findings included ectropion, eclabium, deformed nose, hands and feet, joint contractures, hyperechogenic amniotic fluid and polyhydramnion. After birth, palliative treatment was provided and she died on her first day of life. Sequence analysis of the ABCA12 gene identified two novel mutations, c.1857delA (predicting p.Lys619*) in exon 15 and c.5653–5655delTAT (predicting p.1885delTyr) in exon 37, each in heterozygous state. The c.5653–5655delTAT mutation is not truncating, but the deleted tyrosine at position 1885 is perfectly conserved among vertebrates and molecular studies evaluated the mutation as probably disease causing and damaging.     

Are zoonotic <Emphasis Type="Italic">Staphylococcus pseudintermedius</Emphasis> strains a growing threat for humans?

Staphylococcus pseudintermedius is a species often isolated from animals, as a common element of their microbiota or an agent of infection, and from people associated with an animal habitat, including owners of home pets—dogs and cats. As with many other species, adaptation of these bacteria to the human body can occur, and they become important human pathogens. 59 S. pseudintermedius strains were investigated in this study to determine the factors contributing to human body colonization: inhibition growth of human skin residents isolated from human skin (Staphylococcus epidermidis, Corynebacterium spp., Cutibacterium acnes (formerly Propionibacterium acnes)), biofilm formation, and the presence of ten genes encoding infection-promoting features (including ebpS, spsE, lukS, lukF, pvl, lip, hlgA, hlgB). The ability of human skin to be colonized and the presence of genes that promote the development of skin infections showed the significant potential of the studied strains in their adaptation to the host. However, while a comparison of the characteristics of animal strains and those isolated from human infections does not allow us to claim that we are the witnesses of the speciation of a new human pathogen, it does indicate their gradual adaptation to the human organism.     

Lessons from disorders of epidermal differentiation-associated keratins

A number of diseases have been associated with mutations in genes encoding keratin intermediate filaments. Several of these disorders have skin manifestations, in which histological changes highlight the role of various different keratins in epidermal differentiation. For example, mutations in either K1 or K10 (the major keratin pair expressed in differentiated keratinocytes) usually lead to clumped keratin filaments and cytolysis. Furthermore, the precise nature of the mutation has direct implications for disease phenotype. Specifically, mutations in the H1 and alpha-helical rod domains of K1/K10 result in bullous congenital ichthyosiform erythroderma, underscoring the critical role for this keratin filament domain in maintaining cellular integrity. However, a lysine to isoleucine substitution in the V1 domain of K1 underlies a form of palmoplantar keratoderma, which has different cell biological implications. Keratins are cross-linked into the cornified cell envelopes through this particular lysine residue and the consequences of the mutation lead to changes in keratin-desmosome association and cornified cell morphology, suggesting a role for this keratin subdomain in cornified cell envelope formation. Recently, to extend genotype-phenotype correlation, a frameshift mutation in the V2 region of the K1 tail domain was identified in ichthyosis hystrix (Curth-Macklin type), in which keratin filaments show a characteristic shell-like structure and fail to form proper bundles. In this case, the association of desmosomes with loricrin was also altered, implicating this keratin domain in organizing the intracellular distribution of loricrin during cornification. Collectively, these mutations in K1/K10 provide a fascinating insight into both normal and abnormal processes of epidermal differentiation.     

Effect of genetic background on the ratios between different types of dermatoglyphic patterns: recessive genodermatoses

The ratios between dermatoglyphic patterns of different types were studied in males and females with and without hereditary diseases of the skin. It was found that ridge patterns of fingers are determined by special polygenes. Patients with monogenic dermatoses (X-linked ichthyosis and autosomal recessive ichthyosiform erythroderma) exhibited a suppressed formation of the loop pattern compared to control subjects.     

Genomic organization and amplification of the human epidermal type II keratin genes K1 and K5

Keratins are a family of structurally related proteins that form the intermediate filament cytoskeleton in epithelial cells. Mutations in K1 and K5 result in the autosomal dominant disorders epidermolytic hyperkeratosis/bullous congenital ichthyosiform erythroderma and epidermolysis bullosa simplex, respectively. Most disease-associated mutations are within exons encoding protein domains involved in keratin filament assembly. However, some mutations occur outside the mutation hot-spots and may perturb intermolecular interactions between keratins and other proteins, usually with milder clinical consequences. To screen the entire keratin 1 and keratin 5 genes we have characterized their intron-exon organization. The keratin 1 gene comprises 9 exons spanning approximately 5.6 kb on 12q, and the keratin 5 gene comprises 9 exons spanning approximately 6.1 kb on 12q. We have also developed a comprehensive PCR-based mutation detection strategy using primers placed on flanking introns followed by direct sequencing of the PCR products.     

The multispecies formicary association: the transition from an incomplete to a complete association

This work describes the transformation of the nest complex of a facultatively dominant species, Formica cunicularia, which was naturally colonized by the families of obligate dominants, Formica pratensis and Lasius fuliginosus. The complex was under observation from 2003 to 2013. During this period, F. pratensis families almost completely replaced F. cunicularia in the tenth part of the territory of this multispecies association. The family L. fuliginosus did not exert such an effect on the settlement of the facultative dominant. The study addresses the interaction of foragers of the species that found themselves in the zone of F. pratensis invasion, the dynamics of expansion of the dominant’s foraging areas, and the changes in the multispecies formicary association on the whole. It is shown that, even with different peaceful coexistence mechanisms at work, the alteration of the association occurs through attacks of the obligate dominant on the neighboring families. The progress of this process and possible key situations are considered.     

Effects of genes that control the length of vernalization (Vrd) from agronomic features in soft winter soft wheat

A reduction in the time to heading, a decrease in plant height, and a reduction in frost resistance, especially in the second half of winter and in spring, is demonstrated in near-isogenic lines and cultivars that are monogenic dominant for gene Vrd1 or gene Vrd2. A greater effect with respect to these traits is typical of the Vrd1 gene and a lesser effect for the Vrd2 gene. The two genes Vrd1 and Vrd2 have practically no influence on the quantitative characteristics of the structural elements of wheat, except for the 1000 kernel weight. It is recommended that genotypes that are monogenic dominant in the Vrd2 gene be used to develop new dwarf cultivars for the southern steppe of Ukraine.     

Effect of Genetic Background on the Ratios between Different Types of Dermatoglyphic Patterns: Recessive Genodermatoses

The ratios between dermatoglyphic patterns of different types were studied in males and females with and without hereditary diseases of the skin. It was found that ridge patterns of fingers are determined by special polygenes. Patients with monogenic dermatoses (X-linked ichthyosis and autosomal recessive ichthyosiform erythroderma) exhibited a suppressed formation of the loop pattern compared to control subjects.