Summary
Background
Peeling skin syndrome type 1 (PSS1) is a rare and severe autosomal recessive form of congenital ichthyosis. Patients are affected by pronounced erythroderma accompanied by pruritus ...and superficial generalized peeling of the skin. The disease is caused by nonsense mutations or complete deletion of the CDSN gene encoding for corneodesmosin (CDSN). PSS1 severely impairs quality of life and therapeutic approaches are totally unsatisfactory.
Objectives
The objective of this study was to develop the first steps towards a specific protein replacement therapy for CDSN deficiency. Using this approach, we aimed to restore the lack of CDSN and improve cell–cell cohesion in the transition area of the stratum granulosum (SG) to the stratum corneum.
Methods
Human CDSN was recombinantly expressed in Escherichia coli. A liposome‐based carrier system, prepared with a cationic lipopeptide to mediate the transport to the outer membrane of keratinocytes, was developed. This formulation was chosen for CDSN delivery into the skin. The liposomal carrier system was characterized with respect to size, stability and toxicity. Furthermore, the interaction with primary keratinocytes and human epidermal equivalents was investigated.
Results
The liposomes showed an accumulation at the membranes of keratinocytes. CDSN‐deficient epidermal equivalents that were treated with liposomal encapsulated CDSN demonstrated presence of CDSN in the SG. Finally, the penetration assay and histological examinations revealed an improved epidermal integrity for CDSN‐deficient epidermal equivalents, if they were treated with liposomal encapsulated CDSN.
Conclusions
This study presents the first preclinical in vitro experiments for a future specific protein replacement therapy for patients affected by PSS1.
What is already known about this topic?
Peeling skin syndrome type 1 (PSS1) refers to Mendelian disorders of cornification and is characterized by pruritus, pronounced erythroderma with skin abnormalities and lifelong patchy peeling of the skin.
The disease is caused by autosomal recessive nonsense mutations in the gene encoding corneodesmosin (CDSN). Histopathologically, the absence of CDSN is characterized by subcorneal splitting and enhanced detachment of corneocytes.
What does this study add?
We present a liposomal formulation, which can be used for topical delivery of recombinant CDSN.
Our in vitro study shows that the impaired barrier of CDSN‐deficient human epidermal equivalents can be improved when treated with liposomal human CDSN.
What is the translational message?
This study presents, for the first time, preclinical in vitro experiments for a specific protein replacement therapy in patients with PSS1.
Linked Comment: Schmuth. Br J Dermatol 2021; 184:998–999.
Summary
The proteinase mucosa‐associated lymphoid tissue lymphoma translocation protein 1 (MALT1), which forms part of the caspase recruitment domain‐containing protein 11–B‐cell lymphoma 10–MALT1 ...signalosome complex, plays a direct role in nuclear factor kappa B activation. Here, we describe the case of a female infant with severe immune dysregulation leading to recurrent systemic infections, failure to thrive and severe crises of ichthyosiform erythroderma with high levels of serum IgE. Hence, initial symptoms indicated Netherton syndrome or Omenn syndrome. Surprisingly, sequence analyses of SPINK5 and RAG1/RAG2, respectively, excluded these diseases. During the hospital stay the patient's health deteriorated, despite intensive care therapy, and she died. In order to delineate the diagnosis, whole‐exome sequencing was performed. Two compound heterozygous mutations in MALT1 were found and verified by Sanger sequencing (exon 2 c.245T>C, exon 2 c.310dup), which led to a MALT1 deficiency at the protein level. Based on these results, an immunological analysis was performed, as was immunofluorescence staining of key skin proteins, to confirm a diagnosis of MALT1 deficiency. This case report provides a closer description of the clinical and histological skin phenotype of MALT1 deficiency, and we conclude that MALT1 deficiency must be considered a possible differential diagnosis of Netherton and Omenn syndromes.
What's already known about this topic?
Mucosa‐associated lymphoid tissue lymphoma translocation protein 1 (MALT1) deficiency is a combined immunodeficiency.
MALT1 is part of the caspase recruitment domain‐containing protein 11–B‐cell lymphoma 10–MALT1 signalosome complex, which is essential for nuclear factor kappa B activation.
Current publications describe a phenotype of recurrent systemic infections; only in a few cases has an inflammatory involvement of the integument been described.
What does this study add?
A closer description of the cutaneous phenotype of MALT1 deficiency in a patient with two novel MALT1 mutations.
Immune mapping of follicular epidermis shows lympho‐epithelial Kazal‐type‐related inhibitor is reduced in MALT1 deficiency and absent on interfollicular staining.
Clinically, MALT1 deficiency mimics Netherton syndrome and Omenn syndrome, and should be considered a differential diagnosis
Background
Autosomal‐recessive congenital ichthyosis (ARCI) is a heterogeneous group of ichthyoses presenting at birth. Self‐improving congenital ichthyosis (SICI) is a subtype of ARCI and is ...diagnosed when skin condition improves remarkably (within years) after birth. So far, there are sparse data on SICI and quality of life (QoL) in this ARCI subtype. This study aims to further delineate the clinical spectrum of SICI as a rather unique subtype of ARCI.
Objectives
This prospective study included 78 patients (median age: 15 years) with ARCI who were subdivided in SICI (n = 18) and non‐SICI patients (nSICI, n = 60) by their ARCI phenotype.
Methods
Quality of life (QoL) was assessed using the (Children’s) Dermatology Life Quality Index. Statistical analysis was performed with chi‐squared and t‐Tests.
Results
The genetically confirmed SICI patients presented causative mutations in the following genes: ALOXE3 (8/16; 50.0%), ALOX12B (6/16; 37.5%), PNPLA1 (1/16; 6.3%) and CYP4F22 (1/16; 6.3%). Hypo‐/anhidrosis and insufficient vitamin D levels (<30 ng/mL) were often seen in SICI patients. Brachydactyly (a shortening of the 4th and 5th fingers) was statistically more frequent in SICI (P = 0.023) than in nSICI patients. A kink of the ear’s helix was seen in half of the SICI patients and tends to occur more frequently in patients with ALOX12B mutations (P = 0.005). QoL was less impaired in patients under the age of 16, regardless of ARCI type.
Conclusions
SICI is an underestimated, milder clinical variant of ARCI including distinct features such as brachydactyly and kinking of the ears. Clinical experts should be aware of these features when seeing neonates with a collodion membrane. SICI patients should be regularly checked for clinical parameters such as hypo‐/anhidrosis or vitamin D levels and monitored for changes in quality of life.
Summary
These guidelines for the management of congenital ichthyoses have been developed by a multidisciplinary group of European experts following a systematic review of the current literature, an ...expert conference held in Toulouse in 2016, and a consensus on the discussions. These guidelines summarize evidence and expert‐based recommendations and intend to help clinicians with the management of these rare and often complex diseases. These guidelines comprise two sections. This is part two, covering the management of complications and the particularities of some forms of congenital ichthyosis.
What's already known about this topic?
Various symptomatic treatment options exist for congenital ichthyoses, but there are no European guidelines.
What does this study add?
These European guidelines for the management of congenital ichthyosis may help to improve outcomes and quality of life for patients.
Linked Comment: Akiyama. Br J Dermatol 2019; 180:449–450.
Plain language summary available online
Summary
These guidelines for the management of congenital ichthyoses have been developed by a multidisciplinary group of European experts following a systematic review of the current literature, an ...expert conference held in Toulouse in 2016 and a consensus on the discussions. They summarize evidence and expert‐based recommendations and are intended to help clinicians with the management of these rare and often complex diseases. These guidelines comprise two sections. This is part one, covering topical therapies, systemic therapies, psychosocial management, communicating the diagnosis and genetic counselling.
Linked Comment: Levy. Br J Dermatol 2019; 180:253.
Summary
Background
Rare variants in the genes IL36RN, CARD14 and AP1S3 have been identified to cause or contribute to pustular skin diseases, primarily generalized pustular psoriasis (GPP).
...Objectives
To better understand the disease relevance of these genes, we screened our cohorts of patients with pustular skin diseases primarily GPP and palmoplantar pustular psoriasis (PPP) for coding changes in these three genes. Carriers of single heterozygous IL36RN mutations were screened for a second mutation in IL36RN.
Methods
Coding exons of IL36RN, CARD14 and AP1S3 were sequenced in 67 patients – 61 with GPP, two with acute generalized exanthematous pustulosis and four with acrodermatitis continua of Hallopeau. We screened IL36RN and AP1S3 for intragenic copy‐number variants and 258 patients with PPP for coding changes in AP1S3. Eleven heterozygous IL36RN mutations carriers were analysed for a second noncoding IL36RN mutation. Genotype–phenotype correlations in carriers/noncarriers of IL36RN mutations were assessed within the GPP cohort.
Results
The majority of patients (GPP, 64%) did not carry rare variants in any of the three genes. Biallelic and monoallelic IL36RN mutations were identified in 15 and five patients with GPP, respectively. Noncoding rare IL36RN variants were not identified in heterozygous carriers. The only significant genotype–phenotype correlation observed for IL36RN mutation carriers was early age at disease onset. Additional rare CARD14 or AP1S3 variants were identified in 15% of IL36RN mutation carriers.
Conclusions
The identification of IL36RN mutation carriers harbouring additional rare variants in CARD14 or AP1S3 indicates a more complex mode of inheritance of pustular psoriasis. Our results suggest that, in heterozygous IL36RN mutation carriers, there are additional disease‐causing genetic factors outside IL36RN.
What's already known about this topic?
The genes IL36RN, CARD14 and AP1S3 have been implicated in pustular skin disease with IL36RN having a major role.
Most studies have analysed variants in different genes separately.
Significant subsets of patients with a pustular skin disease carry a single heterozygous mutation in IL36RN, leaving unanswered whether and how the variant is disease‐contributing.
What does this study add?
Intragenic copy‐number variants or noncoding mutations in carriers of single IL36RN mutations were not found.
In total, 15% of patients with generalized pustular psoriasis (GPP) with IL36RN mutations carried variants in CARD14 or AP1S3, providing evidence for a complex inheritance.
Lack of causal /disease‐contributing variants in 64% of GPP patients suggests a role for other, not yet identified genes.
Genotype–phenotype correlation did not reveal significant correlations aside from the presence of IL36RN mutations with age at onset.
What is the translational message?
This study of three genes provides evidence that the inheritance of GPP is more complex than previously understood.
The role of known genes in GPP is rather limited, as almost two‐thirds of patients do not carry a variant in any of these genes.
In palmoplantar pustular psoriasis, the percentage of noncarriers is even lower.
Further genetic studies will reveal the diseases’ pathogenesis and provide a basis to use/develop more specific treatments.
Linked Comment: Capon. Br J Dermatol 2018; 178:589–590
Respond to this article
Summary
Background
Transglutaminase (TG)1 plays a key role in the formation of the cornified envelope and thus in the maintenance of the epidermal barrier. Patients with Netherton syndrome (LEKTI ...deficiency) have increased activity of both TG1 and serin proteases.
Objectives
To determine whether there is a functional biochemical link between TG1 and LEKTI and whether LEKTI domains could possibly serve as substrates for TG1.
Methods
We analysed the protein sequence of LEKTI for possible TG1 recognition sites using bioinformatics. Synthetic peptides and recombinant LEKTI domains D6, D7 and D8+9 were examined in vitro and in situ for possible substrate specificity. The recombinant LEKTI domains were studied for inhibitory activity in a kallikrein (KLK)5 activity test.
Results
We identified possible TG1 consensus sequences in LEKTI domains D6, D7 and D8+9, pointing to a novel biological link between these two proteins. Indeed, synthesized short peptides from these consensus sequences were incorporated into the TG1 activity zone of the epidermis. In vitro the entire recombinant domains of LEKTI showed substrate specificity for TG1, which was again confirmed in situ. The inhibitory activity of the recombinant LEKTI domains was confirmed by a KLK5 inhibition test. The strongest inhibition was observed for domains D8+9.
Conclusions
There are specific domains of LEKTI that are recognized and processed by TG1. LEKTI domains D6, D7 and D8+9 contribute to the formation and protection of the cornified envelope. These results impact the development of protein replacement therapy approaches for Netherton syndrome.
What's already known about this topic?
LEKTI and transglutaminase (TG)1 are key proteins involved in the terminal differentiation of the epidermis.
Lack of LEKTI causes Netherton syndrome; TG1 deficiency causes lamellar ichthyosis.
The serine protease inhibitor LEKTI is processed into different functional units.
Among different target proteases, kallikrein (KLK)5 appears to be a key player in disease pathology.
It has been demonstrated that LEKTI domain 6 inhibits KLK5 and KLK7; LEKTI domains 8–11 also inhibit KLK14.
What does this study add?
The single LEKTI domains 6, 7 and the functional unit of domains 8 and 9 contain recognition motifs for TG1.
We show that these domains and unit are crosslinked into the epidermis by TG1.
Functional analyses of the recombinant LEKTI domains revealed that LEKTI D8+9 has the strongest inhibitory effect on KLK5.
What is the translational message?
The novel functional link between LEKTI and TG1 should be taken into account when considering the development of a targeted topical protein therapy for Netherton syndrome.
The unit of domains D8+9 may be sufficient for this purpose.
Respond to this article
Patients with inherited ichthyosis suffer from scaling due to mutations affecting the epidermal barrier. Symptomatic treatment with ointments, bathing and mechanical scale removal can alleviate the ...disease, but therapy is time and cost intensive.
We investigated costs, time and disease burden of ichthyoses. The study addresses difficulties of the healthcare situation for patients with ichthyoses and reveals potential improvements.
We developed a questionnaire addressing time and financial effort for the treatment. Additionally, we collected data of the Dermatology Life Quality Index (DLQI) and the Pruritus Life Quality (5PLQ) questionnaires to determine the impact of ichthyosis and associated pruritus on quality of life (QoL).
We recruited 144 patients with ichthyosis (median age: 23; 53.5% female) from the Department of Dermatology in Muenster (Germany) and the German patient support group including common, rare and syndromic subtypes. Eighty-seven percent reported applying topical therapeutics at least once per day, 66.4% several times with an overall median duration of 15 min. Highest single expenditure of time was due to balneotherapy (n = 115; median bathing time: 40 min). In 81.9%, the health insurance did not completely cover the costs for topical treatment causing additional financial burden to the patient with a median of 71 € per quarter, herein creams being the largest cost factor (50 €). Patients with Netherton syndrome showed the highest median expenditure (170 €). The QoL impairment under treatment was moderate (median DLQI: 8.5 points). Pruritus was prevalent in 79.9% and showed a distinct impact on QoL (median 5PLQ: 7.5 points) without any significant difference between the subtypes (p = 0.37).
Patients suffering from ichthyoses have a large and lifelong overall burden in mild and severe subtypes. Since continuous topical treatment is required, financial and psychosocial support needs to be considered beyond dermatological care.
Twenty-six families with keratinopathic ichthyoses (epidermolytic ichthyosis, superficial epidermolytic ichthyosis or congenital reticular ichthyosiform erythroderma) were studied. Epidermolytic ...ichthyosis is caused by mutations in the genes KRT1 or KRT10, mutations in the gene KRT2 lead to superficial epidermolytic ichthyosis, and congenital reticular ichthyosiform erythroderma is caused by frameshift mutations in the genes KRT10 or KRT1, which lead to the phenomenon of revertant mosaicism. In this study mutations were found in KRT1, KRT2 and KRT10, including 8 mutations that are novel pathogenic variants. We report here the first case of a patient with congenital reticular ichthyosiform erythroderma carrying a mutation in KRT10 that does not lead to an arginine-rich reading frame. Novel clinical features found in patients with congenital reticular ichthyosiform erythroderma are described, such as mental retardation, spasticity, facial dysmorphisms, symblepharon and malposition of the 4th toe.
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