Pachyonychia congenita - pathogenesis of pain and approaches to treatment.

Pachyonychia congenita is an autosomal dominant genodermatosis characterized by a triad of chronic severe plantar pain, focal palmoplantar keratoderma, and hypertrophic nail dystrophy. Plantar pain can be debilitating and have a profound impact on quality of life. Current therapeutic options for pain in PC are limited to lifestyle adjustment and mechanical techniques, with a small subgroup of patients benefiting from oral retinoids. This review investigates the pathogenesis of pain in pachyonychia congenita and provides a summary of the current and future therapeutic options.

Loss of Function Filaggrin Mutations are Associated with Reduced History of Acne Vulgaris in a Cohort of Bangladeshi Atopic Eczema Patients in East London.

Acne vulgaris (AV) is the eighth most common non-fatal disease globally. Previous work identified an association between AV and increased Filaggrin (FLG) expression in the follicular epidermis, but further work did not find a clear link between loss of function (LoF) Filaggrin gene (FLG) mutations and protection from AV. In this work we aimed to explore any association between AV and FLG LoF mutations using a cohort of genotyped Bangladeshi patients with atopic eczema (AE) in East London. Retrospective notes review was performed on 245 patients who had been genotyped for FLG LoF mutations and undergone clinical assessment. The Chi squared or Fisher's exact test was used to determine differences between groups. We found a significant reduction in history of AV in AE patients with FLG LoF mutations relative to AE patients without FLG mutations (p = 0.02). We showed a non-significant reduction in AV diagnosis in patients with impaired barrier function (measured by trans epidermal water loss) and palmar hyperlinearity. We found that patients with severe AE were less likely to have a history of AV only if they had an existing FLG LoF mutation (p = 0.02). In the context of AE, our work suggests that FLG LoF mutations protect patients from developing AV.

Ichthyosis linked to sphingosine 1-phosphate lyase insufficiency is due to aberrant sphingolipid and calcium regulation.

Sphingosine 1-phosphate lyase (SGPL1) insufficiency (SPLIS) is a syndrome which presents with adrenal insufficiency, steroid-resistant nephrotic syndrome, hypothyroidism, neurological disease, and ichthyosis. Where a skin phenotype is reported, 94% had abnormalities such as ichthyosis, acanthosis, and hyperpigmentation. To elucidate the disease mechanism and the role SGPL1 plays in the skin barrier we established clustered regularly interspaced short palindromic repeats-Cas9 SGPL1 KO and a lentiviral-induced SGPL1 overexpression (OE) in telomerase reverse-transcriptase immortalised human keratinocytes (N/TERT-1) and thereafter organotypic skin equivalents. Loss of SGPL1 caused an accumulation of S1P, sphingosine, and ceramides, while its overexpression caused a reduction of these species. RNAseq analysis showed perturbations in sphingolipid pathway genes, particularly in SGPL1_KO, and our gene set enrichment analysis revealed polar opposite differential gene expression between SGPL1_KO and _OE in keratinocyte differentiation and Ca2+ signaling genesets. SGPL1_KO upregulated differentiation markers, while SGPL1_OE upregulated basal and proliferative markers. The advanced differentiation of SGPL1_KO was confirmed by 3D organotypic models that also presented with a thickened and retained stratum corneum and a breakdown of E-cadherin junctions. We conclude that SPLIS associated ichthyosis is a multifaceted disease caused possibly by sphingolipid imbalance and excessive S1P signaling, leading to increased differentiation and an imbalance of the lipid lamellae throughout the epidermis.

Dermatology Quality of Life Index scores in Bangladeshi patients with atopic eczema and their families in East London.

BACKGROUND: Atopic eczema (AE) is a chronic relapsing, pruritic disease that greatly affects the child and family's quality of life (QoL). It is usually common and severe among children of Bangladeshi ethnicity. OBJECTIVES: This is a cross-sectional quantitative study in patients with AE of Bangladeshi origin, which aims to analyse different components of the family, children and adult quality-of-life indices and their relationship to patient age, sex, eczema severity and distribution, other allergic associations, parental education and socioeconomic level. METHODS: Children and young adults of Bangladeshi origin aged 0-30 years, clinically diagnosed with AE were recruited as part of the Tower Hamlets Eczema Assessment project, a clinical phenotyping study of AE in the Bangladeshi population living in East London. Questionnaires completed by children/parents included the Family Dermatology Life Quality Index (FDLQI), Infant's Dermatology Quality of Life (IDQOL) and the Children's Dermatology Life Quality Index (CDLQI). Young adults completed the Dermatology Life Quality Index (DLQI). The disease severity was assessed objectively using the Eczema Area Severity Index (EASI). Patients and parents who did not read or speak English were aided by Bengali/Sylheti-speaking research assistants. RESULTS: Overall, 460 Bangladeshi children and 98 adults with AE were recruited. Burden of care, extra housework and emotional distress were the highest affected domains in parental QoL, while itching and sleep were the highest for children. Significant factors influencing FDLQI score were EASI [marginal effect (ME) 1.01, 95% confidence interval (CI) 1.00-1.03; P = 0.004], age (ME 0.98, 95% CI 0.97-0.99; P = 0.004), extensor eczema distribution (ME 1.25, 95% CI 1.03-1.52; P = 0.023), parental English fluency (ME 1.29, 95% CI 1.10-1.52; P = 0.002) and atopic comorbidities (ME 1.10, 95% CI 1.04-1.17; P = 0.001). Parental socioeconomic class was a nonsignificant factor. IDQOL/CDLQI was influenced significantly by the child's age (ME 0.99, 95% CI 0.97-1.00, P = 0.023), 'nonclear' eczema distribution clusters especially the 'severe extensive' cluster (ME 1.46, 95% CI 1.15-1.84; P = 0.002) and nonsignificantly by EASI and parental English literacy and socioeconomic levels. DLQI was affected significantly by nonclear eczema distribution groups especially 'severe extensive' (ME 2.49, 95% 1.76-3.53; P < 0.001) and nonsignificantly by patient age, and female sex. CONCLUSIONS: AE is a chronic disease where many external factors other than disease severity affect QoL of patients and their families, -especially in under-represented minority groups who face different linguistic and cultural barriers.

Deep palmar phenotyping in atopic eczema: patterns associated with filaggrin variants, disease severity and barrier function in a South Asian population.

BACKGROUND: Hyperlinear palms are described as a feature of loss-of-function (LoF) variants in filaggrin (FLG). OBJECTIVES: To explore the phenotype of participants (age < 31 years) with atopic eczema of Bangladeshi ancestry from East London and investigate which factors best associate with LoF FLG variants. METHODS: A cross-sectional study with participants recruited between May 2018 and December 2020. Patterns of palmar linearity were categorized and modelled with the Eczema Area and Severity Index (EASI), transepidermal water loss (TEWL), skin hydration (SH) and LoF FLG variants. RESULTS: There were 506 complete cases available. Five palm patterns were noted. The 'prominent diamond' pattern associated best with EASI [marginal effects (ME) 2.53, 95% confidence interval (CI) 1.74-3.67], SH (ME 0.85, 95% CI 0.78-0.96) and TEWL (ME 1.32, 95% CI 1.11-1.62). Using five palm patterns had some ability to discriminate LoF FLG variants [area under the receiver operator characteristic (AUROC) 76.32%, 95% CI 71.91-80.73], improving to 77.99% (73.70-82.28) with the addition of SH. In subgroup analysis with only fine perpendicular/prominent diamond patterns the AUROC was 89.11% (95% CI 84.02-94.19). CONCLUSIONS: This was a single-centre study design with humans classifying clinical patterns. The stability of temperature and humidity was not guaranteed across TEWL and SH measurements despite using a climate-controlled room. Palm patterns associate with EASI and TEWL. The fine perpendicular/prominent diamond patterns are markers to detect the absence/presence of LoF FLG variants, respectively.

Over-expression of stromal periostin correlates with poor prognosis of cutaneous squamous cell carcinomas.

Periostin, an extracellular matrix macromolecule implicated in tumorigenesis, serves as a prognostic marker for many cancer types. However, there are no data on periostin expression in cutaneous squamous cell carcinoma (cSCC). This study examined periostin expression in patients with cSCC and explored its clincopathological relationship and prognosis. Using immunohistochemistry and ImageJ analysis, we compared periostin expression in 95 cSCCs across a spectrum of cSCC aggressiveness: cSCC in situ (SCCIS) (n = 25), low-risk cSCC (LR-cSCC) (n = 26), high-risk cSCC (HR-cSCC) (n = 38), and cSCC in recessive dystrophic epidermolysis bullosa patients (RDEB cSCC) (n = 6). Immunohistochemistry demonstrated periostin expression within the intra-tumoral stroma but not within tumor cells. Periostin levels significantly (P < 0.001) increased from SCCIS, LR-cSCC, HR-cSCC to RDEB SCC. The stroma of most of the cSCCs we evaluated contained cancer-associated fibroblasts with a myofibroblastic (α -SMA-positive) phenotype. Co-localization of periostin with α-SMA, evidence of fibroblast periostin expression, and absence of keratinocyte or tumor cell periostin expression suggest that, in cSCC, periostin is a product of the peritumoral microenvironment and not the tumor cells themselves. Our data indicate that fibroblast periostin expression is highly correlated with the aggressiveness of cSCC, and may thereby provide a molecular marker that will be useful for subtyping and diagnosing cSCCs according to their biological nature.

Proteomic signatures for perioperative oxygen delivery in skin after major elective surgery: mechanistic sub-study of a randomised controlled trial.

BACKGROUND: Maintaining adequate oxygen delivery (DO2) after major surgery is associated with minimising organ dysfunction. Skin is particularly vulnerable to reduced DO2. We tested the hypothesis that reduced perioperative DO2 fuels inflammation in metabolically compromised skin after major surgery. METHODS: Participants undergoing elective oesophagectomy were randomised immediately after surgery to standard of care or haemodynamic therapy to achieve their individualised preoperative DO2. Abdominal punch skin biopsies were snap-frozen before and 48 h after surgery. On-line two-dimensional liquid chromatography and ultra-high-definition label-free mass spectrometry was used to characterise the skin proteome. The primary outcome was proteomic changes compared between normal (≥preoperative value before induction of anaesthesia) and low DO2 (

Diagnosis and Management of Inherited Palmoplantar Keratodermas.

Inherited monogenic palmoplantar keratodermas are a heterogeneous group of conditions characterised by persistent epidermal thickening of the palmoplantar skin. Palmoplantar keratodermas are grouped depending on the morphology of the keratoderma into diffuse, focal/striate or papular/punctate. Some palmoplantar keratodermas just affect the skin of the palms and soles and others have associated syndromic features which include changes in hair, teeth, nails, hearing loss or cardiomyopathy. Next generation sequencing has helped discover genes involved in many of these conditions and has led to reclassification of some palmoplantar keratodermas. In this review, we discuss the diagnostic features of palmoplantar keratodermas and management options.

Loss-of-function mutations in CAST cause peeling skin, leukonychia, acral punctate keratoses, cheilitis, and knuckle pads.

Calpastatin is an endogenous specific inhibitor of calpain, a calcium-dependent cysteine protease. Here we show that loss-of-function mutations in calpastatin (CAST) are the genetic causes of an autosomal-recessive condition characterized by generalized peeling skin, leukonychia, acral punctate keratoses, cheilitis, and knuckle pads, which we propose to be given the acronym PLACK syndrome. In affected individuals with PLACK syndrome from three families of different ethnicities, we identified homozygous mutations (c.607dup, c.424A>T, and c.1750delG) in CAST, all of which were predicted to encode truncated proteins (p.Ile203Asnfs∗8, p.Lys142∗, and p.Val584Trpfs∗37). Immunohistochemistry shows that staining of calpastatin is reduced in skin from affected individuals. Transmission electron microscopy revealed widening of intercellular spaces with chromatin condensation and margination in the upper stratum spinosum in lesional skin, suggesting impaired intercellular adhesion as well as keratinocyte apoptosis. A significant increase of apoptotic keratinocytes was also observed in TUNEL assays. In vitro studies utilizing siRNA-mediated CAST knockdown revealed a role for calpastatin in keratinocyte adhesion. In summary, we describe PLACK syndrome, as a clinical entity of defective epidermal adhesion, caused by loss-of-function mutations in CAST.

Analysis of hedgehog signaling in periocular sebaceous carcinoma.

PURPOSE: Sebaceous carcinoma (SC) is a clinical masquerader of benign conditions resulting in significant eye morbidity, sometimes leading to extensive surgical treatment including exenteration, and even mortality. Little is known about the genetic or molecular basis of SC. This study identifies the involvement of Hedgehog (Hh) signaling in periocular SC. METHODS: Fifteen patients with periocular SC patients were compared to 15 patients with eyelid nodular basal cell carcinoma (nBCC; a known Hh tumor), alongside four normal individuals as a control for physiological Hh expression. Expression of Patched 1 (PTCH1), Smoothened (SMO), and glioma-associated zinc transcription factors (Gli1 and Gli2) were assessed in histological sections using immunohistochemistry and immunofluorescence (IF) techniques. Antibody specificity was verified using Western-blot analysis of a Gli1 over-expressed cancer cell line, LNCaP-Gli1. Semi-quantification compared tumors and control tissue using IF analysis by ImageJ software. RESULTS: Expression of the Hh pathway was observed in SC for all four major components of the pathway. PTCH1, SMO, and Gli2 were more significantly upregulated in SC (P < 0.01) compared to nBCC. Stromal expression of PTCH1 and Gli2 was observed in SC (P < 0.01). In contrast, stromal expression of these proteins in nBCC was similar or down-regulated compared to physiological Hh controls. CONCLUSIONS: The Hh signaling pathway is significantly more upregulated in periocular SC compared to nBCC, a known aberrant Hh pathway tumor. Furthermore, the stroma of the SC demonstrated Hh upregulation, in particular Gli2, compared to nBCC. Targeting of this pathway may be a potential treatment strategy for SC.

Epidermal grafting for wound healing: a review on the harvesting systems, the ultrastructure of the graft and the mechanism of wound healing.

Epidermal grafting for wound healing involves the transfer of the epidermis from a healthy location to cover a wound. The structural difference of the epidermal graft in comparison to the split-thickness skin graft and full-thickness skin graft contributes to the mechanism of effect. While skin grafting is an epidermal transfer, little is known about the precise mechanism of wound healing by epidermal graft. This paper aims to explore the evolution of the epidermal graft harvesting system over the last five decades, the structural advantages of epidermal graft for wound healing and the current hypotheses on the mechanism of wound healing by epidermal graft. Three mechanisms are proposed: keratinocyte activation, growth factor secretion and reepithelialisation from the wound edge. We evaluate and explain how these processes work and integrate to promote wound healing based on the current in vivo and in vitro evidence. We also review the ongoing clinical trials evaluating the efficacy of epidermal graft for wound healing. The epidermal graft is a promising alternative to the more invasive conventional surgical techniques as it is simple, less expensive and reduces the surgical burden for patients in need of wound coverage.

iRHOM2-dependent regulation of ADAM17 in cutaneous disease and epidermal barrier function.

iRHOM2 is a highly conserved, catalytically inactive member of the Rhomboid family, which has recently been shown to regulate the maturation of the multi-substrate ectodomain sheddase enzyme ADAM17 (TACE) in macrophages. Dominant iRHOM2 mutations are the cause of the inherited cutaneous and oesophageal cancer-susceptibility syndrome tylosis with oesophageal cancer (TOC), suggesting a role for this protein in epithelial cells. Here, using tissues derived from TOC patients, we demonstrate that TOC-associated mutations in iRHOM2 cause an increase in the maturation and activity of ADAM17 in epidermal keratinocytes, resulting in significantly upregulated shedding of ADAM17 substrates, including EGF-family growth factors and pro-inflammatory cytokines. This activity is accompanied by increased EGFR activity, increased desmosome processing and the presence of immature epidermal desmosomes, upregulated epidermal transglutaminase activity and heightened resistance to Staphylococcal infection in TOC keratinocytes. Many of these features are consistent with the presence of a constitutive wound-healing-like phenotype in TOC epidermis, which may shed light on a novel pathway in skin repair, regeneration and inflammation.

Mutations in AQP5, encoding a water-channel protein, cause autosomal-dominant diffuse nonepidermolytic palmoplantar keratoderma.

Autosomal-dominant diffuse nonepidermolytic palmoplantar keratoderma is characterized by the adoption of a white, spongy appearance of affected areas upon exposure to water. After exome sequencing, missense mutations were identified in AQP5, encoding water-channel protein aquaporin-5 (AQP5). Protein-structure analysis indicates that these AQP5 variants have the potential to elicit an effect on normal channel regulation. Immunofluorescence data reveal the presence of AQP5 at the plasma membrane in the stratum granulosum of both normal and affected palmar epidermis, indicating that the altered AQP5 proteins are trafficked in the normal manner. We demonstrate here a role for AQP5 in the palmoplantar epidermis and propose that the altered AQP5 proteins retain the ability to form open channels in the cell membrane and conduct water.

RNA-seq analysis of host and viral gene expression highlights interaction between varicella zoster virus and keratinocyte differentiation.

Varicella zoster virus (VZV) is the etiological agent of chickenpox and shingles, diseases characterized by epidermal skin blistering. Using a calcium-induced keratinocyte differentiation model we investigated the interaction between epidermal differentiation and VZV infection. RNA-seq analysis showed that VZV infection has a profound effect on differentiating keratinocytes, altering the normal process of epidermal gene expression to generate a signature that resembles patterns of gene expression seen in both heritable and acquired skin-blistering disorders. Further investigation by real-time PCR, protein analysis and electron microscopy revealed that VZV specifically reduced expression of specific suprabasal cytokeratins and desmosomal proteins, leading to disruption of epidermal structure and function. These changes were accompanied by an upregulation of kallikreins and serine proteases. Taken together VZV infection promotes blistering and desquamation of the epidermis, both of which are necessary to the viral spread and pathogenesis. At the same time, analysis of the viral transcriptome provided evidence that VZV gene expression was significantly increased following calcium treatment of keratinocytes. Using reporter viruses and immunohistochemistry we confirmed that VZV gene and protein expression in skin is linked with cellular differentiation. These studies highlight the intimate host-pathogen interaction following VZV infection of skin and provide insight into the mechanisms by which VZV remodels the epidermal environment to promote its own replication and spread.

Keratins and skin disease.

Mutations in keratin genes cause a diverse spectrum of skin, hair and mucosal disorders. Cutaneous disorders include epidermolysis bullosa simplex, palmoplantar keratoderma, epidermolytic ichthyosis and pachyonychia congenita. Both clinical and laboratory observations confirm a major role for keratins in maintaining epidermal cell-cell adhesion. When normal tissue homeostasis is disturbed, for example, during wound healing and cancer, keratins play an important non-mechanical role. Post-translational modifications including glycosylation and phosphorylation of keratins play an important role in protection of epithelial cells from injury. Keratins also play a role in modulation of the immune response. A current focus in the area of keratins and disease is the development of new treatments including small inhibitory RNA (siRNA) to mutant keratins and small molecules to modulate keratin expression.