Ichthyosis vulgaris: the filaggrin mutation disease

Clinical vs. chronological skin age: exploring determinants and stratum corneum protein markers of differential skin ageing in 351 healthy women

Apparent skin age can be determined by several clinical measurements and may differ from chronological age, hence defining age acceleration/deceleration (Age A/D). Using data from 360 women with dermatological scoring of 21 clinical signs, we defined 3 well-separated co-occurring classes capturing the dryness, the elasticity and the oily nature of the skin. We related the risk of each clinical signs to the stratum corneum levels of 5 pre-selected proteins, we identified specific chronological age-adjusted signatures of each clinical sign. Using variable selection approaches, we identified 6 (of the 21) clinical signs which were jointly predictive of chronological age and used to define the clinical skin age, and subsequently age A/D. Applying univariate and multivariate approaches we found that stratum corneum levels of insulin degrading enzyme (IDE) was protective against (β = - 1.74, p = 3.3 × 10-6; selection proportion > 90%) accelerated skin ageing. In conclusion, our results support the fact that molecular markers found in the stratum corneum could predict skin ageing acceleration/deceleration.

Nucleic Acid Therapy for the Skin

Advances in sequencing technologies have facilitated the identification of the genes and mechanisms for many inherited skin diseases. Although targeted nucleic acid therapeutics for diseases in other organs have begun to be deployed in patients, the goal of precise therapeutics for skin diseases has not yet been realized. First, we review the current and emerging nucleic acid-based gene-editing and delivery modalities. Next, current and emerging viral and nanoparticle vehicles for the delivery of gene therapies are reviewed. Finally, specific skin diseases that could benefit optimally from nucleic acid therapies are highlighted. By adopting the latest technologies and addressing specific barriers related to skin biology, nucleic acid therapeutics have the potential to revolutionize treatments for patients with skin disease.

Saikosaponin A Recovers Impaired Filaggrin Levels in Inflamed Skin by Downregulating the Expression of FRA1 and c-Jun

Filaggrin (FLG) is an essential structural protein expressed in differentiated keratinocytes. Insufficient FLG expression contributes to the pathogenesis of chronic inflammatory skin diseases. Saikosaponin A (SSA), a bioactive oleanane-type triterpenoid, exerts anti-inflammatory activity. However, the effects of topically applied SSA on FLG expression in inflamed skin remain unclear. This study aimed to evaluate the biological activity of SSA in restoring reduced FLG expression. The effect of SSA on FLG expression in HaCaT cells was assessed through various biological methods, including reverse transcription PCR, quantitative real-time PCR, immunoblotting, and immunofluorescence staining. TNFα and IFNγ decreased FLG mRNA, cytoplasmic FLG protein levels, and FLG gene promoter-reporter activity compared to the control groups. However, the presence of SSA restored these effects. A series of FLG promoter-reporter constructs were generated to investigate the underlying mechanism of the effect of SSA on FLG expression. Mutation of the AP1-binding site (mtAP1) in the -343/+25 FLG promoter-reporter abrogated the decrease in reporter activities caused by TNFα + IFNγ, suggesting the importance of the AP1-binding site in reducing FLG expression. The SSA treatment restored FLG expression by inhibiting the expression and nuclear localization of FRA1 and c-Jun, components of AP1, triggered by TNFα + IFNγ stimulation. The ERK1/2 mitogen-activated protein kinase signaling pathway upregulates FRA1 and c-Jun expression, thereby reducing FLG levels. The SSA treatment inhibited ERK1/2 activation caused by TNFα + IFNγ stimulation and reduced the levels of FRA1 and c-Jun proteins in the nucleus, leading to a decrease in the binding of FRA1, c-Jun, p-STAT1, and HDAC1 to the AP1-binding site in the FLG promoter. The effect of SSA was evaluated in an animal study using a BALB/c mouse model, which induces human atopic-dermatitis-like skin lesions via the topical application of dinitrochlorobenzene. Topically applied SSA significantly reduced skin thickening, immune cell infiltration, and the expression of FRA1, c-Jun, and p-ERK1/2 compared to the vehicle-treated group. These results suggest that SSA can effectively recover impaired FLG levels in inflamed skin by preventing the formation of the repressor complex consisting of FRA1, c-Jun, HDAC1, and STAT1.

Targeting the Complexity of In Vitro Skin Models: A Review of Cutting-Edge Developments

Skin in vitro models offer much promise for research, testing drugs, cosmetics, and medical devices, reducing animal testing and extensive clinical trials. There are several in vitro approaches to mimicking human skin behavior, ranging from simple cell monolayer to complex organotypic and bioengineered 3-dimensional models. Some have been approved for preclinical studies in cosmetics, pharmaceuticals, and chemicals. However, development of physiologically reliable in vitro human skin models remains in its infancy. This review reports on advances in in vitro complex skin models to study skin homeostasis, aging, and skin disease.

Revisiting X-linked congenital ichthyosis

X-linked recessive ichthyosis (XLI) is a hereditary skin disease characterized by generalized dryness and scaling of the skin, with frequent extracutaneous manifestations. It is the second most common type of ichthyosis, with a prevalence of 1/6,000 to 1/2,000 in males and without any racial or geographical differences. The causative gene for XLI is the steroid sulfatase gene (STS), located on Xp22.3. STS deficiency causes an abnormal cholesterol sulfate (CS) accumulation in the stratum corneum (SC). Excess CS induces epidermal permeability barrier dysfunction and scaling abnormalities. This review summarizes XLI's genetic, clinical, and pathological features, pathogenesis, diagnosis and differential diagnoses, and therapeutic perspectives. Further understanding the role of the STS gene pathogenic variants in XLI may contribute to a more accurate and efficient clinical diagnosis of XLI and provide novel strategies for its treatment and prenatal diagnosis.

Prevalence of ichthyoses in Denmark: a nationwide registry-based study

The results demonstrate a prevalence of 1.6 per 10 000 for all types of ichthyoses, based on large Danish national patient registries, including all patients with relevant diagnoses alive on 31 December 2021. A study of this size and depth has not been completed before but may still underestimate the prevalence and potential burden of the diseases.

Increased loss-of-function filaggrin gene mutation prevalence in atopic dermatitis patients across northern latitudes indicates genetic fitness: A systematic review and meta-analysis

Loss-of-function (LoF) mutations in the filaggrin gene (FLG) constitute the strongest genetic risk for atopic dermatitis (AD). A latitude-dependent difference in the prevalence of LoF FLG mutations was systematically evaluated. A systematic review and meta-analysis were performed to estimate the prevalence of LoF FLG mutations in AD patients and the general population by geography and ethnicity. Risk of bias was assessed by Newcastle-Ottawa Scale and Jadad score. StatsDirect, version 3 software was used to calculate all outcomes. PubMed and EMBASE were searched until 9th December 2021. Studies were included if they contained data on the prevalence of LoF FLG mutations in AD patients or from the general population or associations between AD and LoF FLG mutations and were authored in English. Overall, 248 studies and 229 310 AD patients and individuals of the general population were included in the quantitative analysis. The prevalence of LoF FLG mutations was 19.1% (95% CI, 17.3-21.0) in AD patients and 5.8% (95% CI, 5.3-6.2) in the general population. There was a significant positive association between AD and LoF FLG mutations in all latitudes in the Northern hemisphere, but not in all ethnicities. The prevalence of LoF FLG mutations became gradually more prevalent in populations residing farther north of the Equator but was negligible in Middle Easterners and absent in most African populations. FLG LoF mutations are common and tend to increase with northern latitude, suggesting potential clinical implications for future AD management. The existence of possible genetic fitness from FLG LoF mutations remains unknown.

Identification and Validation of eRNA as a Prognostic Indicator for Cervical Cancer

The survival of CESC patients is closely related to the expression of enhancer RNA (eRNA). In this work, we downloaded eRNA expression, clinical, and gene expression data from the TCeA and TCGA portals. A total of 7936 differentially expressed eRNAs were discovered by limma analysis, and the relationship between these eRNAs and survival was analyzed by univariate Cox hazard analysis, LASSO regression, and multivariate Cox hazard analysis to obtain an 8-eRNA model. Risk score heat maps, KM curves, ROC analysis, robustness analysis, and nomograms further indicate that this 8-eRNA model is a novel indicator with high prognostic performance independent of clinicopathological classification. The model divided patients into high-risk and low-risk groups, compared pathway diversity between the two groups through GSEA analysis, and provided potential therapeutic agents for high-risk patients.

Topical drug delivery strategies for enhancing drug effectiveness by skin barriers, drug delivery systems and individualized dosing

Topical drug delivery is widely used in various diseases because of the advantages of not passing through the gastrointestinal tract, avoiding gastrointestinal irritation and hepatic first-pass effect, and reaching the lesion directly to reduce unnecessary adverse reactions. The skin helps the organism to defend itself against a huge majority of external aggressions and is one of the most important lines of defense of the body. However, the skin's strong barrier ability is also a huge obstacle to the effectiveness of topical medications. Allowing the bioactive, composition in a drug to pass through the stratum corneum barrier as needed to reach the target site is the most essential need for the bioactive, composition to exert its therapeutic effect. The state of the skin barrier, the choice of delivery system for the bioactive, composition, and individualized disease detection and dosing planning influence the effectiveness of topical medications. Nowadays, enhancing transdermal absorption of topically applied drugs is the hottest research area. However, enhancing transdermal absorption of drugs is not the first choice to improve the effectiveness of all drugs. Excessive transdermal absorption enhances topical drug accumulation at non-target sites and the occurrence of adverse reactions. This paper introduces topical drug delivery strategies to improve drug effectiveness from three perspectives: skin barrier, drug delivery system and individualized drug delivery, describes the current status and shortcomings of topical drug research, and provides new directions and ideas for topical drug research.

Filaggrin-Associated Atopic Skin, Eye, Airways, and Gut Disease, Modifying the Presentation of X-Linked Reticular Pigmentary Disorder (XLPDR)

BACKGROUND

X-linked reticular pigmentary disorder (XLPDR) is a rare condition characterized by skin hyperpigmentation, ectodermal features, multiorgan inflammation, and recurrent infections. All probands identified to date share the same intronic hemizygous POLA1 hypomorphic variant (NM_001330360.2(POLA1):c.1393-354A > G) on the X chromosome. Previous studies have supported excessive type 1 interferon (IFN) inflammation and natural killer (NK) cell dysfunction in disease pathogenesis. Common null polymorphisms in filaggrin (FLG) gene underlie ichthyosis vulgaris and atopic predisposition.

CASE

A 9-year-old boy born to non-consanguineous parents developed eczema with reticular skin hyperpigmentation in early infancy. He suffered recurrent chest infections with chronic cough, clubbing, and asthma, moderate allergic rhinoconjunctivitis with keratitis, multiple food allergies, and vomiting with growth failure. Imaging demonstrated bronchiectasis, while gastroscopy identified chronic eosinophilic gastroduodenitis. Interestingly, growth failure and bronchiectasis improved over time without specific treatment.

METHODS

Whole-genome sequencing (WGS) using Illumina short-read sequencing was followed by both manual and orthogonal automated bioinformatic analyses for single-nucleotide variants, small insertions/deletions (indels), and larger copy number variations. NK cell cytotoxic function was assessed using 51Cr release and degranulation assays. The presence of an interferon signature was investigated using a panel of six interferon-stimulated genes (ISGs) by QPCR.

RESULTS

WGS identified a de novo hemizygous intronic variant in POLA1 (NM_001330360.2(POLA1):c.1393-354A > G) giving a diagnosis of XLPDR, as well as a heterozygous nonsense FLG variant (NM_002016.2(FLG):c.441del, NP_0020.1:p.(Arg151Glyfs*43)). Compared to healthy controls, the IFN signature was elevated although the degree moderated over time with the improvement in his chest disease. NK cell functional studies showed normal cytotoxicity and degranulation.

CONCLUSION

This patient had multiple atopic manifestations affecting eye, skin, chest, and gut, complicating the presentation of XLPDR. This highlights that common FLG polymorphisms should always be considered when assessing genotype-phenotype correlations of other genetic variation in patients with atopic symptoms. Additionally, while the patient exhibited an enhanced IFN signature, he does not have an NK cell defect, suggesting this may not be a constant feature of XLPDR.

Inherited ichthyosis as a paradigm of rare skin disorders: Genomic medicine, pathogenesis, and management

Great advances have been made in the field of heritable skin disorders using next-generation sequencing (NGS) technologies (ie, whole-genome sequencing, whole-exome sequencing, whole-transcriptome sequencing, and disease-targeted multigene panels). When NGS first became available, the cost and lack of access to these technologies were limiting factors; however, with decreasing sequencing costs and the expanding knowledge base of genetic skin diseases, fundamental awareness of NGS has become prudent. The heritable ichthyoses comprise a genotypically and phenotypically heterogeneous group of monogenic keratinization disorders characterized by persistent scaling, with at least 55 distinct genes currently implicated in causing nonsyndromic and syndromic forms of the disease. By providing a simplified overview of available NGS techniques and applying them in the context of ichthyosis, one of the most common genodermatoses, we hope to encourage dermatologists to offer, when appropriate, genetic testing earlier in patients with unsolved presentations. With the aid of NGS, dermatologists can provide diagnostic certainty in cases of suspected genodermatoses and offer potentially life-changing genome-guided and targeted therapies as they become available.

Filaggrin gene variants among Saudi patients with ichthyosis vulgaris

Ichthyoses are a heterogeneous group of cornification disorders. The most common form of ichthyoses is ichthyosis vulgaris (IV) ([OMIM] #146,700), which can be inherited as autosomal semi-dominant mutation in the filaggrin gene (FLG). We present the findings of a study involving 35 Saudi patients with a clinical diagnosis of ichthyosis vulgaris. For identifying the pathogenic mutation of their disease, we used Sanger sequencing analysis of the extracted DNA samples. We also identified the underlying 22 FLG variants, which have been seen before. However, the detected mutations do not involve the common p.R501* c. 2282del4 mutations reported in European populations. Indeed, we did not identify any statistical influence of the homozygous or heterozygous genotypes on the phenotype severity of the disease.

The Skin Barrier and Moisturization: Function, Disruption, and Mechanisms of Repair

BACKGROUND

The anatomic layers of the skin are well-defined, and a functional model of the skin barrier has recently been described. Barrier disruption plays a key role in several skin conditions, and moisturization is recommended as an initial treatment in conditions such as atopic dermatitis. This review aimed to analyze the skin barrier in the context of the function model, with a focus on the mechanisms by which moisturizers support each of the functional layers of the skin barrier to promote homeostasis and repair.

SUMMARY

The skin barrier is comprised of four interdependent layers - physical, chemical, microbiologic, and immunologic - which maintain barrier structure and function. Moisturizers target disruption affecting each of these four layers through several mechanisms and were shown to improve transepidermal water loss in several studies. Occlusives, humectants, and emollients occlude the surface of the stratum corneum (SC), draw water from the dermis into the epidermis, and assimilate into the SC, respectively, in order to strengthen the physical skin barrier. Acidic moisturizers bolster the chemical skin barrier by supporting optimal enzymatic function, increasing ceramide production, and facilitating ideal conditions for commensal microorganisms. Regular moisturization may strengthen the immunologic skin barrier by reducing permeability and subsequent allergen penetration and sensitization.

KEY MESSAGES

The physical, chemical, microbiologic, and immunologic layers of the skin barrier are each uniquely impacted in states of skin barrier disruption. Moisturizers target each of the layers of the skin barrier to maintain homeostasis and facilitate repair.

Genotype Study of Filaggrin Gene Loss-of-Function Mutations in Central India Population with Atopic Dermatitis and Ichthyosis Vulgaris

Background

A genotype study of filaggrin gene loss-of-function mutations in central India can provide valuable insights into the prevalence and association of these mutations with atopic dermatitis (AD) and ichthyosis vulgaris (IV) in the region. The FLG R501X and 2282del4 are both genetic variants in the human gene called filaggrin gene (FLG), which encodes a protein that plays an important role in the formation and maintenance of the skin barrier. In this study, we determined the FLG R501X and 2282del4 variants association with both AD and IV in Central Indian populations.

Materials and Methods

This case-control study was conducted in the Departments of Dermatology and Molecular and Virology Research and Diagnostic Laboratory at Sri Aurobindo Medical College and Post Graduate Institute, Indore (Madhya Pradesh). The study was approved by the Clinical Research and Ethics Committee. A total of 180 patients aged between 3 months - 60 years who attended the skin outpatient department between March-2021 to June-2022 were recruited in this study. Among them, 60 patients were in AD-group, 60 patients in IV-group, and 60 patients were in the healthy control group. Polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) was used in genotyping for FLG mutations (R501X and 2282del4).

Results

The most common FLG mutations were R501X (31.6% and 23.3%) and 2282del4 (18.3% and 13.3%) in AD and IV patients with heterozygous (AT) genotype, respectively. The combined mutation (FLG R501X and 2282del4) association was 10% and 5% in the AD and IV groups with heterozygous (AT) genotype, respectively, and in all the patients of control group with wild genotype (AA). There were no significant (P = 0.09) associations found with 2282del14 genotype.

Conclusion

The R501X mutation in the gene encoding filaggrin is one of the robust genetic associations of AD and IV. The 2282del4 polymorphism was marginally less as compared to R501X.

Advanced In Vitro Three-Dimensional Skin Models of Atopic Dermatitis

Atopic dermatitis (AD) is one of the most prevalent inflammatory skin diseases that is characterized by eczematous rashes, intense itching, dry skin, and sensitive skin. Although AD significantly impacts the quality of life and the number of patients keeps increasing, its pathological mechanism is still unknown because of its complexity. The importance of developing new in vitro three-dimensional (3D) models has been underlined in order to understand the mechanisms for the development of therapeutics since the limitations of 2D models or animal models have been repeatedly reported. Thus, the new in vitro AD models should not only be created in 3D structure, but also reflect the pathological characteristics of AD, which are known to be associated with Th2-mediated inflammatory responses, epidermal barrier disruption, increased dermal T-cell infiltration, filaggrin down-regulation, or microbial imbalance. In this review, we introduce various types of in vitro skin models including 3D culture methods, skin-on-a-chips, and skin organoids, as well as their applications to AD modeling for drug screening and mechanistic studies.

Skin barrier immunology from early life to adulthood

Our skin has a unique barrier function, which is imperative for the body's protection against external pathogens and environmental insults. Although interacting closely and sharing many similarities with key mucosal barrier sites, such as the gut and the lung, the skin also provides protection for internal tissues and organs and has a distinct lipid and chemical composition. Skin immunity develops over time and is influenced by a multiplicity of different factors, including lifestyle, genetics, and environmental exposures. Alterations in early life skin immune and structural development may have long-term consequences for skin health. In this review, we summarize the current knowledge on cutaneous barrier and immune development from early life to adulthood, with an overview of skin physiology and immune responses. We specifically highlight the influence of the skin microenvironment and other host intrinsic, host extrinsic (e.g. skin microbiome), and environmental factors on early life cutaneous immunity.

Biallelic mutations in FLG, TGM1, and STS genes segregated with different types of ichthyoses in eight families of Pakistani origin

BACKGROUND

Congenital ichthyosis is a diverse group of keratinization disorders associated with generalized scaling of skin of varying severity. The non-syndromic forms of congenital ichthyosis are further grouped into common ichthyosis (ichthyosis vulgaris and X-linked ichthyosis), autosomal recessive congenital ichthyosis, and keratopathic ichthyosis.

OBJECTIVE

To identify sequence variants involved in different forms of hereditary ichthyoses.

METHODS

We studied eight families with different types of ichthyosis including four families with autosomal recessive congenital ichthyosis and four families with common ichthyosis. Whole exome sequencing and PCR based genotyping was carried out to find out the molecular basis of disease.

RESULTS

In one family, a novel duplication sequence variant NM_002016.2:c.2767dupT; NP_002007.1:p.Ser923PhefsTer2 was identified in FLG gene; in four families a previously reported nonsense sequence variant NM_000359.3:c.232C>T; NP_002007.1:p.Arg78Ter was identified in TGM1 gene, while, in three families of X-linked recessive ichthyosis, the whole STS gene (NM_001320752.2; NP_001307681.2) regions were deleted.

STUDY LIMITATION

Gene expression studies have not been performed that would have strengthened the findings of computational analysis.

CONCLUSION

This study highlights the significance of the c.232C>T variant in the TGM1 gene as a possible founder mutation, complete STS gene deletion as reported previously in Pakistani population, while novel sequence variant in the FLG gene expands the spectrum of variations in this gene. These findings may be used for genetic counseling of the studied families.

Cellular and molecular features related to exceptional therapy response and extreme long-term survival in glioblastoma

Glioblastoma Multiforme (GBM) remains the most common malignant primary brain tumor with a dismal prognosis that rarely exceeds beyond 2 years despite extensive therapy, which consists of maximal safe surgical resection, radiotherapy, and/or chemotherapy. Recently, it has become clear that GBM is not one homogeneous entity and that both intra-and intertumoral heterogeneity contributes significantly to differences in tumoral behavior which may consequently be responsible for differences in survival. Strikingly and in spite of its dismal prognosis, small fractions of GBM patients seem to display extremely long survival, defined as surviving over 10 years after diagnosis, compared to the large majority of patients. Although the underlying mechanisms for this peculiarity remain largely unknown, emerging data suggest that still poorly characterized both cellular and molecular factors of the tumor microenvironment and their interplay probably play an important role. We hereby give an extensive overview of what is yet known about these cellular and molecular features shaping extreme long survival in GBM.

Ichthyosis vulgaris: An updated review

Ichthyosis vulgaris is an inherited, non-syndromic form of ichthyosis that presents with skin problems. Making up more than 95% cases of ichthyosis, ichthyosis vulgaris is caused by heterozygous loss-of-function mutation of the filaggrin gene, raising the fragility and permeability of the stratum corneum. It typically presents in infancy as xerosis, skin lesions, keratosis pilaris, palmoplantar hyper linearity, scaly dermatosis, and erythroderma, clearly identifiable by age 5. Although majority of patients have a normal lifespan, possible complications include a vitamin D deficiency and auditory problems due to scaling in the ears, besides a drop in quality of life due to dermatological changes. Urea-based creams with 10% urea, ceramides, and other ceramides are often the first line therapy in ichthyosis vulgaris. There is no known curative treatment for ichthyosis vulgaris, but lifelong treatment can alleviate the symptoms. Urea-based creams are highly therapeutic, whereas ammonium lactate 12% lotion with a physiological lipid-based repair cream can help with scaling and dryness. There is also evidence in favour of propylene glycol solutions. Risankizumab, an anti-interleukin-23 drug, and enhancement of natural moisturizing factors are also two highly promising solutions that require additional research. This review aims to provide updates on the manifestation, evaluation, and treatment of ichthyosis vulgaris.

Charcot-Marie-Tooth Disease Type 4C and Autosomal Dominant Heterozygous Ichthyosis Vulgaris, with Bilateral Hearing Loss: A Novel Association with Review of Literature

A 3-year-old boy, firstborn to nonconsanguineous parents, presented with motor development delay and floppiness of bilateral lower limbs since birth. No significant family history presented at time of check-up. He could stand with support, eat with a spoon without spillage, and speak in two-word sentences. There was no history suggestive of cranial nerve impairment. Examination revealed normal head circumference, dry, scaly skin lesions on the trunk, distal weakness with sluggish deep tendon reflexes in bilateral lower limbs, and a high stepping gait. Nerve conduction studies revealed demyelinating polyneuropathy. Brain stem-evoked response audiometry testing revealed auditory neuropathy. Clinical exome sequencing revealed a known pathogenic variant of 3325C > T in the SH3TC2 gene suggestive of Charcot-Marie-Tooth disease type 4C and ichthyosis vulgaris with a novel variant of 2218C > T in the FLG gene. We have reviewed the available literature for reported associations of Charcot-Marie-Tooth disease type 4C and ichthyosis vulgaris. This is probably the first reported association of Charcot-Marie-Tooth disease type 4C and ichthyosis vulgaris with bilateral hearing loss.

FRA1:c-JUN:HDAC1 complex down-regulates filaggrin expression upon TNFα and IFNγ stimulation in keratinocytes

Filaggrin (FLG), an essential structural protein for skin barrier function, is down-regulated under chronic inflammatory conditions, leading to disruption of the skin barrier. However, the detailed molecular mechanisms of how FLG changes in the context of chronic inflammation are poorly understood. Here, we identified the molecular mechanisms by which inflammatory cytokines inhibit FLG expression in the skin. We found that the AP1 response element within the -343/+25 of the FLG promoter was necessary for TNFα + IFNγ-induced down-regulation of FLG promoter activity. Using DNA affinity precipitation assay, we observed that AP1 subunit composition binding to the FLG promoter was altered from c-FOS:c-JUN (at the early time) to FRA1:c-JUN (at the late time) in response to TNFα + IFNγ stimulation. Knockdown of FRA1 or c-JUN abrogated TNFα + IFNγ-induced FLG suppression. Histone deacetylase (HDAC) 1 interacted with FRA1:c-JUN under TNFα + IFNγ stimulation. Knockdown of HDAC1 abrogated the inhibitory effect of TNFα + IFNγ on FLG expression. The altered expression of FLG, FRA1, c-JUN, and HDAC1 was confirmed in mouse models of 2,4-dinitrochlorobenzene-induced atopic dermatitis and imiquimod-induced psoriasis. Thus, the current study demonstrates that TNFα + IFNγ stimulation suppresses FLG expression by promoting the FRA1:c-JUN:HDAC1 complex. This study provides insight into future therapeutic strategies targeting the FRA1:c-JUN:HDAC1 complex to restore impaired FLG expression in chronic skin inflammation.

Keratosis pilaris and filaggrin loss-of-function mutations in patients with atopic dermatitis - Results of a Finnish cross-sectional study

Keratosis pilaris (KP) associates with epidermal barrier defects in atopic dermatitis (AD) but its role in disease severity and concomitant atopic diseases seems to vary between populations. We performed a cross‐sectional observational study with 502 randomly selected AD patients of a Finnish tertiary health care center. At a single clinical examination, disease severity (Rajka Langeland severity score and EASI), clinical signs and patient history were evaluated and total IgE levels and frequent filaggrin (FLG) loss‐of‐function mutations were investigated. There was no link with disease severity (p = 0.649, 95% CI 0.569–0.654), asthma (p = 0.230, 95% CI 0.206–0.281) or atopic sensitization (p = 0.351, 95% CI 0.309–0.392). Keratosis pilaris was significantly associated with palmar hyperlinearity (p < 0.000, 95% CI 0.000–0.006, OR 4.664, 95% CI 2.072–10.496) and the filaggrin loss‐of‐function mutation 2282del4 (p < 0.000, 95% CI 0.000–0.009, OR 4.917, 95%CI 1.961–12.330). The prevalence of KP in the cohort was generally low and KP seems to be infrequent in Finnish AD patients. This may be explained by the fact that the tested FLG loss‐of‐function mutations are rarer in the Finnish population compared for example, with central Europe or Asia. Mutations in other locations of the FLG gene or other genes of the epidermal barrier may play a more important role.

Mood symptoms, neurodevelopmental traits, and their contributory factors in X-linked ichthyosis, ichthyosis vulgaris and psoriasis

Background

High rates of adverse mood/neurodevelopmental traits are seen in multiple dermatological conditions, and can significantly affect patient quality of life. Understanding the sex‐specific nature, magnitude, impact and basis of such traits in lesser‐studied conditions like ichthyosis, is important for developing effective interventions.

Aim

To quantify and compare relevant psychological traits in men with X‐linked ichthyosis (XLI, n = 54) or in XLI carrier women (n = 83) and in patients with ichthyosis vulgaris (IV, men n = 23, women n = 59) or psoriasis (men n = 30, women n = 122), and to identify factors self‐reported to contribute most towards depressive, anxious and irritable phenotypes.

Methods

Participants recruited via relevant charities or social media completed an online survey of established questionnaires. Data were analysed by sex and skin condition, and compared with general population data.

Results

Compared with the general population, there was a higher rate of lifetime prevalence of mood disorder diagnoses across all groups and of neurodevelopmental disorder diagnoses in the XLI groups. The groups exhibited similarly significant elevations in recent mood symptoms (Cohen d statistic 0.95–1.28, P < 0.001) and neurodevelopmental traits (d = 0.31–0.91, P < 0.05) compared with general population controls, and self‐reported moderate effects on quality of life and stigmatization. There were strong positive associations between neurodevelopmental traits and recent mood symptoms (r > 0.47, P < 0.01), and between feelings of stigmatization and quality of life, particularly in men. Numerous factors were identified as contributing significantly to mood symptoms in a condition or sex‐specific, or condition or sex‐independent, manner.

Conclusion

We found that individuals with XLI, IV or psoriasis show higher levels of mood disorder diagnoses and symptoms than matched general population controls, and that the prevalence and severity of these is similar across conditions. We also identified a number of factors potentially conferring either general or condition‐specific risk of adverse mood symptoms in the three skin conditions, which could be targeted clinically and/or through education programmes. In clinical practice, recognizing mood/neurodevelopmental problems in ichthyosis and psoriasis, and addressing the predisposing factors identified by this study should benefit the mental health of affected individuals.

New Treatments for Atopic Dermatitis Targeting Skin Barrier Repair via the Regulation of FLG Expression

Atopic dermatitis (AD) is one of the most common chronic, inflammatory skin disorders with a complex etiology and a broad spectrum of clinical phenotypes. Despite its high prevalence and effect on the quality of life, safe and effective systemic therapies approved for long-term management of AD are limited. A better understanding of the pathogenesis of atopic dermatitis in recent years has contributed to the development of new therapeutic approaches that target specific pathophysiological pathways. Skin barrier dysfunction and immunological abnormalities are critical in the pathogenesis of AD. Recently, the importance of the downregulation of epidermal differentiation complex (EDC) molecules caused by external and internal stimuli has been extensively emphasized. The purpose of this review is to discuss the innovations in the therapy of atopic dermatitis, including biologics, small molecule therapies, and other drugs by highlighting regulatory mechanisms of skin barrier-related molecules, such as filaggrin (FLG) as a crucial pathway implicated in AD pathogenesis.

Atopic dermatitis among children and adolescents in the Arctic region - a systematic review and meta-analysis

The prevalence of atopic dermatitis (AD) varies across the globe, and the clinical phenotype with racial background and ethnicity. AD in the Arctic region has only been scarcely studied. We performed a systematic review and meta-analysis to examine the prevalence, clinical manifestations and risk factors for AD among children and adolescents in the Arctic. Three medical databases PubMed, Embase and Web of Science were screened. All studies published between 1990 to 2020 with epidemiologic data on AD in children and adolescents in the Arctic region, were included. Data were extracted and a meta-analysis was performed to obtain pooled proportions and incidences with 95% confidence intervals (CI). We identified 21 studies from 8 different Arctic regions with 31 403 participants. The cumulative incidence of AD was 23% (95% CI 20-26) and 1-year prevalence was 19% (95% CI 15-25). The incidence of AD was higher in the Arctic parts of Scandinavia and lower in Greenland and Russia. Children of indigenous descent had a slightly lower incidence of AD (19%, 95% CI 13-26) compared to the overall population. The dominant phenotype of AD was mild to moderate flexural dermatitis with facial involvement. Asthma and allergic rhinitis were common and observed in 20-30% of children with AD. In conclusion, AD is highly prevalent in the Arctic, but varies between regions and races. Indigenous children living in less urbanized countries appear to have a slightly lower risk of AD. Future studies should confirm this and examine whether this correlation relates to behavioural differences or genetic signature.

Utilization of patterned bioprinting for heterogeneous and physiologically representative reconstructed epidermal skin models

Organotypic skin tissue models have decades of use for basic research applications, the treatment of burns, and for efficacy/safety evaluation studies. The complex and heterogeneous nature of native human skin however creates difficulties for the construction of physiologically comparable organotypic models. Within the present study, we utilized bioprinting technology for the controlled deposition of separate keratinocyte subpopulations to create a reconstructed epidermis with two distinct halves in a single insert, each comprised of a different keratinocyte sub-population, in order to better model heterogonous skin and reduce inter-sample variability. As an initial proof-of-concept, we created a patterned epidermal skin model using GPF positive and negative keratinocyte subpopulations, both printed into 2 halves of a reconstructed skin insert, demonstrating the feasibility of this approach. We then demonstrated the physiological relevance of this bioprinting technique by generating a heterogeneous model comprised of dual keratinocyte population with either normal or low filaggrin expression. The resultant model exhibited a well-organized epidermal structure with each half possessing the phenotypic characteristics of its constituent cells, indicative of a successful and stable tissue reconstruction. This patterned skin model aims to mimic the edge of lesions as seen in atopic dermatitis or ichthyosis vulgaris, while the use of two populations within a single insert allows for paired statistics in evaluation studies, likely increasing study statistical power and reducing the number of models required per study. This is the first report of human patterned epidermal model using a predefined bioprinted designs, and demonstrates the relevance of bioprinting to faithfully reproduce human skin microanatomy.

Experimental Models for the Study of Hereditary Cornification Defects

Ichthyoses comprise a broad spectrum of keratinization disorders due to hereditary defects of cornification. Until now, mutations in more than 50 genes, mostly coding for structural proteins involved in epidermal barrier formation, have been identified as causes for different types of these keratinization disorders. However, due to the high heterogeneity and difficulties in the establishment of valid experimental models, research in this field remains challenging and translation of novel findings to clinical practice is difficult. In this review, we provide an overview of existing models to study hereditary cornification defects with focus on ichthyoses and palmoplantar keratodermas.

A review of quality of life of patients suffering from ichthyosis

Introduction

Ichthyoses include a heterogeneous group of skin diseases often characterized by persistent scaling and hyperkeratosis with variable erythema, pruritus, and sweating impairment. The aim of our review was to assess the quality of life in patients with ichthyosis.

Methods

In July 2018 we performed a systematic search in the electronic database PubMed (MEDLINE). The MESH term “quality of life” was combined, through the Boolean operator AND with the key word “ichthyosis”. We considered eligible for the systematic review studies written in English.

Results

The literature search yielded 63 publications, but 7 studies were included in the review. Studies were published in 2003-2014 and involved a minimum of 10 and a maximum of 235 patients. Authors used 5 types of tools: Dermatology Life Quality Index (DLQI), Dermatitis Family Impact Questionnaire (DFI), Nottingham Health Profile (NHP) questionnaire, Short Form Questionnaire 36 and 12 (SF-36, SF-12). Many patients reported worse scores than general population. Patients referred physical problems related to pain (which negatively influenced the mobility).

Conclusions

Ichthyosis considerably impaired the QoL, especially for paediatric patients. Further studies and efforts should be done to manage and treat the pain.

Could cellular and signaling abnormalities converge to provoke atopic dermatitis?

Diverse inherited and acquired abnormalities in epidermal structural and enzymatic proteins compromise permeability, barrier function and antimicrobial defense in atopic dermatitis (AD). Though several mutations in filaggrin (FLG) predominate, alterations in other S-100, cornified envelope precursor proteins (hornerin [HRNR], filaggrin 2 [FLG2], SPRR3, mattrin) which regulate lamellar body formation; SPINK5, which encodes the serine protease inhibitor, LEKTI1, and a fatty acid transporter, FATP4, are all separately associated with an AD phenotype. Exogenous and endogenous stressors, such as prolonged psychological stress, a low environmental humidity, or exposure to basic soaps and surfactants can further compromise barrier function and are often required to trigger disease. In the immunologists' view, the barrier abnormality is relevant only because it allows antigen and pathogen access, while stimulating Th2 cytokine production. These proteins in turn downregulate lipid synthetic enzyme and antimicrobial peptide levels, as well as multiple epidermal structural proteins, including filaggrin. Each inherited and acquired abnormality can independently compromise lamellar body secretion production, resulting in defective lamellar membrane organization and antimicrobial defense. Furthermore, elevated pH of the SC is critical for AD pathogenesis, compromising post-secretory lipid processing, while also enhancing inflammation. There are various therapeutic options that interdict different stages in this pathogenic paradigm.

Changes in nano-mechanical properties of human epidermal cornified cells in children with atopic dermatitis

Background: Impaired skin barrier is an important etiological factor in atopic dermatitis (AD). The structural protein filaggrin (FLG) plays a major role in maintenance of the competent skin barrier and its deficiency is associated with enhanced susceptibility to mechanical injury. Here we examined biomechanical characteristics of the corneocytes in children with AD and healthy controls. Methods: We recruited 20 children with AD and 7 healthy children. They were genotyped for filaggrin gene ( FLG) loss-of-function mutations. Stratum corneum was collected from clinically unaffected skin by adhesive tapes. Cell stiffness (apparent elastic modulus, Ea) was determined by atomic force microscopy and filaggrin degradation products (NMF) by liquid chromatography. Skin barrier function was assessed through trans-epidermal water loss (TEWL) and disease severity by the SCORing Atopic Dermatitis (SCORAD) tool. Results:  Corneocytes collected from AD patients showed a decreased elastic modulus which was strongly correlated with NMF and TEWL, but not with SCORAD. As compared with healthy controls, AD patients had reduced TEWL and NMF levels regardless of FLG mutations. NMF was strongly correlated with TEWL. Conclusion: Our findings demonstrate that AD patients have decreased corneocyte stiffness which correlates with reduced levels of filaggrin degradation products, NMF and skin barrier function. Altered mechanical properties of the corneocytes likely contribute to the loss of mechanical integrity of the SC and to reduced skin barrier function in AD.

Changes in nano-mechanical properties of human epidermal cornified cells in children with atopic dermatitis

Background: Impaired skin barrier is an important etiological factor in atopic dermatitis (AD). The structural protein filaggrin (FLG) plays a major role in maintenance of the competent skin barrier and its deficiency is associated with enhanced susceptibility to mechanical injury. Here we examined biomechanical characteristics of the corneocytes in children with AD and healthy controls. Methods: We recruited 20 children with AD and 7 healthy children. They were genotyped for filaggrin gene ( FLG) loss-of-function mutations. Stratum corneum was collected from clinically unaffected skin by adhesive tapes. Cell stiffness (apparent elastic modulus, Ea) was determined by atomic force microscopy and filaggrin degradation products (NMF) by liquid chromatography. Skin barrier function was assessed through trans-epidermal water loss (TEWL) and disease severity by the SCORing Atopic Dermatitis (SCORAD) tool. Results:  Corneocytes collected from AD patients showed a decreased elastic modulus which was strongly correlated with NMF and TEWL, but not with SCORAD. As compared with healthy controls, AD patients had reduced TEWL and NMF levels regardless of FLG mutations. NMF was strongly correlated with TEWL. Conclusion: Our findings demonstrate that AD patients have decreased corneocyte stiffness which correlates with reduced levels of filaggrin degradation products, NMF and skin barrier function. Altered mechanical properties of the corneocytes likely contribute to the loss of mechanical integrity of the SC and to reduced skin barrier function in AD.

E. coli Monomicrobial Necrotizing Fasciitis in an Iron-Overloaded Adolescent

Escherichia coli is an extremely unusual cause of monomicrobial necrotizing fasciitis of the extremities in children. We report a transfusion-dependent adolescent boy with iron-overload secondary to congenital dyserythropoietic anemia who developed severe E. coli monomicrobial necrotizing fasciitis of the leg following a minor trauma. Combined surgical, antimicrobial and supportive care resulted in a good outcome.

A unique case of a digital tourniquet in ichthyosis vulgaris

We report a unique case of a digital tourniquet in a patient with ichthyosis vulgaris. We have identified no previous case reports documenting the occurrence of a digital tourniquet in patients caused by this condition. Ichthyosis vulgaris is a skin condition which causes increased scaling of the skin and in this case, resulted in the formation of a tourniquet-like circumferential constriction to one of the patient's digits.

Non‑invasive proteome‑wide quantification of skin barrier‑related proteins using label‑free LC‑MS/MS analysis

A number of epidermal proteins are closely related to skin barrier function, the abnormalities of which can lead to specific skin diseases. These proteins must be quantified to further investigate the changes in the skin barrier between healthy and disease states. However, the non-invasive and proteome-wide quantification of skin proteins without any labelling steps remains a challenge. In this study, 3M medical adhesive tapes were used to obtain skin samples from volunteers. Proteins were extracted from fresh skin samples and digested with trypsin. Each tryptic peptide was analysed in three replicates using liquid chromatography with tandem mass spectrometry analysis and label-free quantification. The data were searched against the Human Universal Protein Resource (UniProt) to match with known proteins. Using this method, 1,157 skin proteins recorded in the UniProt were quantified. A total of 50 identical proteins were identified in the three replicate analyses of all samples with no significant differences in abundance. The results provided an objective metric for further study of skin ageing and various skin diseases. Specifically, the non-invasive proteome-wide method used in this study can be applied to future studies of skin diseases related to barrier destruction by monitoring the changes in the levels of epidermal proteins.

Filaggrin loss-of-function mutations and levels of filaggrin degradation products in adult patients with atopic dermatitis in Croatia

BACKGROUND

FLG loss-of-function mutations (FLG LOF) represent the strongest genetic risk factor for atopic dermatitis (AD) and are associated with early-onset and more severe disease. The prevalence of FLG mutations varies greatly across Europe. At present, there are no data on FLG mutation prevalence in Croatian AD patients.

OBJECTIVES

To investigate the prevalence of FLG LOF mutations in adult patients with AD and healthy controls. Next to measure the stratum corneum (SC) levels of filaggrin degradation products (NMF), transepidermal water loss (TEWL) and pH in lesional and non-lesional skin.

METHODS

We recruited 100 AD patients with moderate to severe disease and 50 healthy controls. They were screened for three FLG mutations (R501X, 2282del4 and R2447X). Samples of the SC for NMF analysis were collected by adhesive tapes. TEWL and skin surface pH levels were determined on the lesional and non-lesional skin.

RESULTS

The combined mutation frequency was 4% in the AD group, and all patients with FLG mutations were homozygous carriers. In the control group, no mutations were found. The most common FLG mutation in AD patients was 2282del4 (3%), followed by R501X (1%). As compared to healthy controls, NMF values were strongly reduced in lesional skin; however, no significant difference was found for non-lesional skin. AD patients had elevated TEWL in both lesional and non-lesional skin. The same pattern was observed for pH.

CONCLUSIONS

Our study expands understanding of the landscape of FLG mutations in the European population. The low frequency of FLG mutations and similar levels of filaggrin degradation products in healthy controls and in non-lesional skin of AD patients suggest that filaggrin deficiency does not confer a major risk for AD in the Croatian population.

A novel nonsense mutation in the STS gene in a Pakistani family with X-linked recessive ichthyosis: including a very rare case of two homozygous female patients

Background

X-linked ichthyosis (XLI; OMIM# 308100) is a recessive keratinization disorder characterized by the presence of dark brown, polygonal, adherent scales on different parts of the body surface. It almost exclusively affects males and the estimated prevalence ranges from 1:2000–6000 in males worldwide. Extracutaneous manifestations are frequent including corneal opacities, cryptorchidism, neuropsychiatric symptoms or others. Up to 90% of XLI cases are caused by recurrent hemizygous microdeletion encompassing entire STS gene on chromosome Xp22.3, while only a minority of patients shows partial deletions or loss of function point mutations in STS. Larger deletions also involving contiguous genes are identified in syndromic patients.

Methods

Here, we report clinical and genetic findings of a large Pakistani family having 16 affected individuals including 2 females with XLI. Molecular karyotyping and direct DNA sequencing of coding region of the STS gene was performed.

Results

The clinical manifestations in affected individuals involved generalized dryness and scaling of the skin with polygonal, dark scales of the skin on scalp, trunk, limbs, and neck while sparing face, palms and soles. There were no associated extra-cutaneous features such as short stature, cryptorchidism, photophobia, corneal opacities, male baldness, and behavioral, cognitive, or neurological phenotypes including intellectual disability, autism or attention deficit hyperactivity disorder. Molecular karyotyping was normal and no copy number variation was found. Sanger sequencing identified a novel hemizygous nonsense mutation (c.287G > A; p.W96*), in exon 4 of STS gene in all affected male individuals. In addition, two XLI affected females in the family were found to be homozygous for the identified variant.

Conclusions

This study is useful for understanding the genetic basis of XLI in the patients studied, for extending the known mutational spectrum of STS, diagnosis of female carriers and for further application of mutation screening in the genetic counseling of this family.

Prevalence of FLG loss-of-function mutations R501X, 2282del4, and R2447X in Spanish children with atopic dermatitis

BACKGROUND/OBJECTIVES

Atopic dermatitis (AD) is the most prevalent inflammatory skin disorder, and is often associated with a personal or family history of atopic disease. The presence of loss-of-function mutations in the filaggrin gene (FLG) is the main predisposing factor for AD FLG mutations show ethnic and geographical variations, even between European populations. We sought to determine the frequency of the 3 most common FLG null mutations in a population of Spanish children consisting of healthy controls and AD patients. We also investigated the association between these 3 FLG mutations and AD.

METHODS

A total of 214 participants (111 AD patients and 103 healthy controls) were enrolled in this study. Genotyping for 3 FLG null mutations (R501X, 2282del4, and R2447X) was performed by conventional Sanger sequencing.

RESULTS

The combined mutation frequency was 1.9% in the control group and 12.6% in the AD group. The most common FLG mutation in AD patients was R501X (9.9%), followed by R2447X (2.7%) and 2282del4 (1.8%).

CONCLUSION

These findings further our understanding of the prevalence of FLG null mutations in the Spanish population, and suggest that the frequency of FLG mutations in AD patients in Spain is slightly higher than that of other Mediterranean countries.

3D-Organotypic Cultures to Unravel Molecular and Cellular Abnormalities in Atopic Dermatitis and Ichthyosis Vulgaris

Atopic dermatitis (AD) is characterized by dry and itchy skin evolving into disseminated skin lesions. AD is believed to result from a primary acquired or a genetically-induced epidermal barrier defect leading to immune hyper-responsiveness. Filaggrin (FLG) is a protein found in the cornified envelope of fully differentiated keratinocytes, referred to as corneocytes. Although FLG null mutations are strongly associated with AD, they are not sufficient to induce the disease. Moreover, most patients with ichthyosis vulgaris (IV), a monogenetic skin disease characterized by FLG homozygous, heterozygous, or compound heterozygous null mutations, display non-inflamed dry and scaly skin. Thus, all causes of epidermal barrier impairment in AD have not yet been identified, including those leading to the Th2-predominant inflammation observed in AD. Three dimensional organotypic cultures have emerged as valuable tools in skin research, replacing animal experimentation in many cases and precluding the need for repeated patient biopsies. Here, we review the results on IV and AD obtained with epidermal or skin equivalents and consider these findings in the context of human in vivo data. Further research utilizing complex models including immune cells and cutaneous innervation will enable finer dissection of the pathogenesis of AD and deepen our knowledge of epidermal biology.

Palmar hyperlinearity in early childhood atopic dermatitis is associated with filaggrin mutation and sensitization to egg

BACKGROUND/OBJECTIVES

Palmar hyperlinearity is a typical clinical feature of Filaggrin gene (FLG) null mutations. There are reports of FLG mutations and allergic sensitization; however, reports on the relationship between palmar hyperlinearity to sensitization are limited. This study aimed to examine the association between palmar hyperlinearity and sensitization in atopic dermatitis (AD) children.

METHODS

This cross-sectional, case-control study included children ˂ 6 years old with moderate-severe AD whose parents consented for mutation analysis and photographic documentation. Each child underwent genotyping to detect the eight most prevalent FLG mutations in the Japanese population: R501X, 3321delA, S1695X, Q1701X, S2554X, S2889X, S3296X, and K4022X. Clinical features and parameters including egg-specific IgE were examined, and palm photographs were evaluated by 12 trained dermatologists blinded to genotyping results.

RESULTS

Of the 57 patients (age range, 2 months to 5 years; median, 22 months), 16 were heterozygotes and three were compound heterozygotes. Palmar hyperlinearity, as recognized by more than two-thirds of dermatologists, was significantly associated with FLG mutation (P = 0.002, OR = 6.98, 95% CI = 2.1-23.7), and this association was observed especially in children over 2 years. Cross-shaped crease of the thenar eminence, as known in previous reports, also demonstrated significant correlation with FLG mutation. When the children were divided according to the presence or absence of palmar hyperlinearity, the egg white-specific IgE was significantly higher in the hyperlinearity group (55.9 vs 18.3 IU/mL, P < 0.05).

CONCLUSIONS

Palmar hyperlinearity indicates possible inherited barrier abnormalities of the skin in early childhood. Its identification may help to predict a more accurate prognosis, such as sensitization.

Genetic variants of filaggrin are associated with occupational dermal exposure and blood DNA alterations in hairdressers

Hairdressers are exposed to high levels of chemicals, including possible carcinogens. For dermal exposure, the skin protects against the uptake of chemicals and the protein filaggrin (encoded by FLG) has a key role in skin barrier function. This study investigated if variants of FLG previously linked to impaired skin barrier function, i.e. null mutations and copy number variation (CNV) alleles (CNV10), are associated with cancer-related DNA changes. Blood and questionnaire data were collected from hairdressers (n = 295) and controls (n = 92). Exposure to aromatic amines was measured as hemoglobin adducts by gas chromatography tandem mass spectrometry. DNA from peripheral blood was used to test for FLG null mutations and CNV (10, 11, or 12 repeats), telomere length, and methylation of selected cancer-related genes. Hairdressers had a lower frequency of FLG null mutations (4.1 vs. 7.6%, P = 0.18) and CNV10 (43.2 vs. 56%, P = 0.0032) than controls. In hairdressers, CNV10 carriers had a decreased risk of high ortho-toluidine adducts in blood compared with non-carriers (odds ratio, OR = 0.49, 95% CI = 0.30-0.81). Further, telomere length was shorter for carriers of any FLG null allele (β = -0.18, 95% CI = -0.31 to -0.044) and CNV10 carriers (β = -0.054, 95% CI = -0.11 to -0.00051, linear regression adjusted for age, passive smoking, residence, and education) compared to non-carriers. Carriers of any FLG null allele showed higher methylation of the cyclin-dependent kinase inhibitor 2A gene CDKN2A (OR = 6.26, CI = 1.13-34.7), but not of the other genes analyzed. These associations were not found among the controls. Our study showed that the frequency of FLG CNV10 was lower among hairdressers than controls, which may indicate a healthy worker selection. Moreover, FLG null and CNV10 were associated with cancer-related DNA changes in hairdressers, which may influence their risk of cancer.

Knock-down of filaggrin influences the mitogen-activated protein kinases signaling pathway in normal human epidermal keratinocytes

BACKGROUND

Filaggrin is an essential structural protein of the stratum corneum binding to the keratin intermediate filaments to form a dense protein-lipid matrix. However, the function of filaggrin in epidermal terminal differentiation is not completely understood.

AIM

To evaluate the effects of filaggrin on normal human epidermal keratinocytes (NHEKs) and to investigate the relevant mechanisms.

METHODS

Short hairpin RNA (shRNA) technology was used to knock-down filaggrin in normal human epidermal keratinocytes (NHEKs). Western blot and real-time quantitative PCR (qRT-PCR) were performed to detect expression of filaggrin, differentiation-related proteins and MAPK-related proteins.

RESULTS

Filaggrin was successfully knocked down in NHEKs (99% efficiency). We found that the lack of filaggrin significantly decreased the expression of some differentiation-related proteins, including Cytokeratin 5 protein, Cytokeratin 14 protein, ST14 protein and SPRR3 protein (P<0.05). In addition, filaggrin knock-down significantly decreased expression of p-p38, p-ERK1/2, p-JNK, p-Akt, and p-NF-κB in NHEKs.

CONCLUSION

Our study shows that filaggrin regulates epidermal terminal differentiation and impairs MAPK signaling pathway in normal human epidermal keratinocytes.

Exacerbation of ichthyosis vulgaris phenotype by co-inheritance of STS and FLG mutations in a Chinese family with ichthyosis: a case report

Background

X-linked ichthyosis (XLI) is a recessive keratinization condition caused by deficient activity of steroid-sulfatase due to mutations in steroid sulfatase (STS) gene located on the X chromosome. In contrast, ichthyosis vulgaris (IV) is caused by filaggrin deficiency due to semi-dominant loss-of-function mutations of filaggrin (FLG) gene. Filaggrin defects could synergize with XLI to exacerbate its phenotype.

Case presentation

We report a Chinese family with patients presenting diverse phenotype of Keratosis pilaris. A next-generation sequencing panel interrogating 25 ichthyosis related genes with sequencing coverage of the coding regions and splice site junctions, was applied to screen genetic mutations. A gross deletion encompassing the STS gene ranging from exon 1–10 and the FLG c.3321delA mutation were identified in a 31-year old male proband, one of his sister, and his mother, and all the three patients showed obvious symptom. The deletion of STS gene was confirmed by real-time quantitative PCR. The proband’s another sister and his two nephews carried only FLG c.3321delA mutation. Patients carried both mutations presented more severe symptom, while those only carried FLG c.3321delA mutation showed slight or normal phenotype.

Conclusions

In conclusion, we found that the IV phenotype was exacerbated by co-inheritance of STS and FLG mutations in a Chinese family with ichthyosis. Other genomic regions no included in the study might be also involved in phenotypic modifications.