Novel sporadic and recurrent mutations in KRT5 and KRT14 genes in Polish epidermolysis bullosa simplex patients: further insights into epidemiology and genotype-phenotype correlation

Epidermolysis bullosa simplex (EBS) is a hereditary genodermatosis characterised by trauma-induced intraepidermal blistering of the skin. EBS is mostly caused by mutations in the KRT5 and KRT14 genes. Disease severity partially depends on the affected keratin type and may be modulated by mutation type and location. The aim of our study was to identify the molecular defects in KRT5 and KRT14 in a cohort of 46 Polish and one Belarusian probands with clinical suspicion of EBS and to determine the genotype-phenotype correlation. The group of 47 patients with clinical recognition of EBS was enrolled in the study. We analysed all coding exons of KRT5 and KRT14 using Sanger sequencing. The pathogenic status of novel variants was evaluated using bioinformatical tools, control group analysis (DNA from 100 healthy population-matched subjects) and probands' parents testing. We identified mutations in 80 % of patients and found 29 different mutations, 11 of which were novel and six were found in more than one family. All novel mutations were ascertained as pathogenic. In the majority of cases, the most severe genotype was associated with mutations in highly conserved regions. In some cases, different inheritance mode and clinical significance, than previously reported by others, was observed. We report 11 novel variants and show novel genotype-phenotype correlations. Our data give further insight into the natural history of EBS molecular pathology, epidemiology and mutation origin.

Pemphigus. S2 Guideline for diagnosis and treatment--guided by the European Dermatology Forum (EDF) in cooperation with the European Academy of Dermatology and Venereology (EADV)

BACKGROUND

Pemphigus encompasses a group of life-threatening autoimmune bullous diseases characterized by blisters and erosions of the mucous membranes and skin. Before the era of immunosuppressive treatment, the prognosis of pemphigus was almost fatal. Due to its rarity, only few prospective controlled therapeutic trials are available.

OBJECTIVES

For this reason, a group of European dermatologists with a long-standing interest and expertise in basic and clinical pemphigus research has sought to define diagnostic and therapeutic guidelines for the management of patients with pemphigus.

RESULTS

This group identified the statements of major agreement or disagreement regarding the diagnostic and therapeutic management of pemphigus. The revised final version of the pemphigus guideline was finally passed on to the European Dermatology Forum (EDF) for a final consensus with the European Academy of Dermatology and Venereology (EADV) and the European Union of Medical Specialists (UEMS).

Under-recognition of acral peeling skin syndrome: 59 new cases with 15 novel mutations

BACKGROUND

Acral peeling skin syndrome (APSS) is a rare skin fragility disorder usually caused by mutations in the transglutaminase 5 gene (TGM5).

METHODS

We investigated the mutation spectrum of APSS in the U.K., Germany and Poland.

RESULTS

We identified 59 children with APSS from 52 families. The phenotype was readily recognizable, with some variation in severity both within and between families. Most cases had been misdiagnosed as the localized form of epidermolysis bullosa simplex (EBS-loc). Eighteen different TGM5 mutations were identified, 15 of which were novel. Eight mutations were unique to a single family, nine each occurred in two families, while the common p.Gly113Cys mutation linked to a second missense variant p.Thr109Met occurred in 47 of the 52 families and was homozygous in 28. Most patients were of nonconsanguineous white European origin.

CONCLUSIONS

We propose that APSS is under-reported and widely misdiagnosed as EBS-loc, with significant counselling implications as APSS is autosomal recessive while EBS-loc is dominant. We recommend screening for TGM5 mutations when EBS-loc is suspected but not confirmed by mutations in KRT5 or KRT14. Our report trebles the number of known TGM5 mutations. It provides further evidence that p.Gly113Cys is a founder mutation in the European population. This is consistent with the striking ethnic distribution of APSS in U.K., where the majority of patients are of nonconsanguineous white European origin, in contrast to the pattern of other recessive skin disorders.

Conformal nano-thin modified polyelectrolyte coatings for encapsulation of cells

Encapsulation of cells in polymeric shells allows for separation of biological material from produced factors, which may find biotechnological and biomedical applications. Human T-lymphocyte cell line Jurkat as well as rat pancreatic islets were encapsulated using LbL technique within shells of polyelectrolyte modified by incorporation of biotin complexed with avidin to improve cell coating and to create the potential ability to elicit specific biochemical responses. The coating with nano-thin modified shells allowed for maintenance of the evaluated cells' integrity and viability during the 8-day culture. The different PE impact may be observed on different biological materials. The islets exhibited lower mitochondrial activity than the Jurkat cells. Nevertheless, coating of cells with polyelectrolyte modified membrane allowed for functioning of both model cell types: 10 μm leukemia cells or 150 μm islets during the culture. Applied membranes maintained the molecular structure during the culture period. The conclusion is that applied modified membrane conformation may be recommended for coating shells for biomedical purposes.

Alterations of basement membrane zone in autoimmune subepidermal bullous diseases

BACKGROUND

Pemphigoid (BP), mucous membrane pemphigoid (MMP) and epidermolysis bullosa acquisita (EBA) are characterized by the presence of in vivo bound and circulating anti-basement membrane zone (BMZ) antibodies directed against different antigens localized in the upper part of the lamina lucida, lamina lucida-lamina densa border and in sublamina densa region, respectively. The alterations of BMZ lead to blister formation.

OBJECTIVES

The aim of the present study was to compare the alterations of various regions of the BMZ in BP, MMP and EBA using laser scanning confocal microscopy (LSCM).

METHODS

Biopsy specimens taken from perilesional patients' skin were cut into 40mum thick slides, followed by double immunofluorescence labeling with antibodies against different BMZ structures and anti-human IgG antibody. Three-dimensional reconstruction (3DR) of various regions of BMZ and of in vivo bound IgG was performed by computer program integrated with LSCM.

RESULTS

In BP and MMP, LSCM studies revealed numerous invaginations of BMZ, most pronounced at the level of lamina lucida. Integrity of BMZ was preserved at the level of lamina lucida, lamina densa and sublamina densa. In EBA, continuity of lamina lucida was preserved and numerous invaginations were present. More pronounced invaginations of BMZ were observed at the level of lamina densa, whereas at the level of the sublamina densa region the staining along BMZ was discontinuous. Moreover, large clumps composed of collagen VII vertically oriented to the dermal-epidermal junction extending into the mid dermis were observed.

CONCLUSIONS

The study showed that alterations of BMZ in BP and MMP occur mainly in the lamina lucida, and in EBA in the sublamina densa region. These alterations in various regions of BMZ in BP, MMP and EBA could be responsible for the differences in the level of blister formation and in the clinical course of the diseases.

Internalization of gap junctions in benign familial pemphigus (Hailey-Hailey disease) and keratosis follicularis (Darier's disease)

Hereditary skin disorders involving acantholysis, such as Hailey-Hailey disease and Darier's disease, have been genetically linked to distinct chromosomal parts which do not code for known structural proteins. Such evidence suggests that the genomic abnormalities underlying these dermatoses may concern functional/regulatory mechanisms of keratinocyte cohesion. Epidermal communication junctions (gap junctions) are responsible for direct coupling of cells and, thus, co-ordinate the behaviour of keratinocytes within the tissue. Consequently, they remain one of the potential, and poorly studied, elements in the pathogenesis of hereditary acantholytic diseases. We have investigated the distribution and fate of gap junctions during non-immune acantholysis, using fine immunolocalization methods at the light and electron microscopic levels. Our results demonstrate normal expression of epidermal gap junction proteins, connexins 26 and 43, in non-lesional skin of Hailey-Hailey and Darier's diseases. The gap junctions were not primarily dismantled during acantholysis, typical of both of the studied dermatoses, but underwent internalization and subsequent cytoplasmic dispersion in the portions of cells which were no longer attached to the rest of the tissue. In Darier's disease, perifollicular acantholysis did not specifically concern epithelium of appendages coexpressing connexin 26 in addition to connexin 43, further indicating that the observed changes in gap junction localization were secondary to the loss of cell-cell contact. We demonstrated that the sequence of changes was identical in both diseases and that the previously described putative differences were apparently related to the degree of acantholysis present in the studied biopsies. The fate of the junctional structures and proteins, documented in the present study, is most probably a form of recycling process also used by normal keratinocytes during organogenesis and tissue differentiation.

Protein kinase C--a potential modifier of carotid body function

This article deals with the potential role of protein kinase C (PKC) in signal transduction in the carotid body. The carotid body is a chemosensory organ which, by sensing reductions in arterial blood oxygen tension, is primarily responsible for the hyperventilation of hypoxia. The mechanisms of transduction of the hypoxic stimulus into a neural signal regulating respiration are not clear. Hypoxia increases the phosphoinositide-specific phospholipase C (PLC) activity in the carotid body. The PLC-derived signalling molecules are known to activate PKC. The enzyme might, thus, have the potential to interact with the process of chemoreception. This article demonstrates that PKC is present in the chemoreceptor cells of the cat carotid body and discusses the biology of the enzyme relevant to chemosensory function. This gives rise to the hypothesis that PKC-mediated mechanisms alter chemoreceptor cell function to a sufficient extent to metamorphose the hypoxic signal into an increased discharge frequency in the apposed sinus nerve endings.

Ultrastructural localization of binding sites of sera from patients with linear IgA bullous dermatosis

The localization of the antigen recognized by IgA basement membrane zone (BMZ) antibodies from patients with linear IgA bullous dermatosis (LABD) has not been established. The aim of our study was to find out the binding sites for IgA-BMZ antibodies in LABD in adults and children and, for comparison, the binding sites for IgA antibodies in IgA cicatricial pemphigoid (IgA-CP). Our series comprised 21 sera from adult LABD, 4 sera from childhood LABD, and 2 sera from IgA-CP. The studies were performed using the sodium chloride split-skin method and indirect immunoelectron microscopy (IEM) with the use of the pre-embedding immunoperoxidase technique on two substrates: monkey oesophagus and normal human skin. Of the 27 sera, 24 reacted with the epidermis (19 from adult, 4 from childhood LABD and 1 from IgA-CP) and at the electron microscopic level labelled the upper part of the lamina lucida (LL) and/or hemidesmosomes, and 2 reacted with the dermis (1 from typical adult LABD and 1 from IgA-CP) and labelled the sublamina densa (SLD) region. Two sera were negative in IEM. In conclusion, the study indicated that the localization of the antigens is similar in adult and childhood LABD, and in IgA-CP.

Immunogold localization of the 97-kD antigen of linear IgA bullous dermatosis (LABD) detected with patients' sera

The classification of linear IgA bullous dermatosis in the group of subepidermal blistering diseases is still a matter of controversy. This situation is due partly to the considerable clinical heterogeneity of the disease but also results from the difficulties in characterization and localization of the specific basement membrane zone antigen(s) recognized by immunoglobulin (Ig)A antibodies. In the present study, we have combined the Western blot detection of circulating autoantibodies with an ultrastructural immunogold labeling of human skin antigens using the same patients' sera. Our results, obtained with a short series of sera showing exclusive IgA class reactivity with the epidermal portion of salt-split skin, indicate that the antibodies recognizing the 97-kD antigen on immunoblot bind to the hemidesmosomal plaques of basal keratinocytes and the adjacent lamina lucida. These homogeneous laboratory results remain in striking contrast to the heterogeneity of clinical pictures in the patients studied, suggesting a participation of complementary, possibly not humoral, phenomena in the pathogenesis of linear IgA bullous dermatosis.

IgA pemphigus foliaceus with a clinical presentation of pemphigus herpetiformis

A patient with clinical features of herpetiform pemphigus of the foliaceus type had histologic findings consistent with pemphigus. Intercellular IgA deposits in a pattern like that of IgG in pemphigus were present. Circulating pemphigus-type IgA-class antibodies reacted first only with guinea pig and later in the disease also with monkey esophagus sections. IgG-class pemphigus antibodies were blocked by the IgA-class antibodies of this patient. In addition, the IgA-class pemphigus antibodies in this patient were blocked by the IgG-class pemphigus antibodies in tests on guinea pig and monkey esophagus. This indicates that the IgA-class antibodies in this patient were directed either to the same antigen as the IgG-class pemphigus foliaceus antibodies or to one that is close enough to it to give steric hindrance. The skin lesions responded poorly to systemic corticosteroid therapy. Dapsone therapy initially produced dramatic improvement, but the condition flared to the point that plasmapheresis, in addition to high doses of corticosteroids and cyclophosphamide, had to be used to control it.

Detection of anti-basement membrane zone antibodies in bullous systemic lupus erythematosus

We describe a 42-year-old black woman with long-standing systemic lupus erythematosus in whom vesiculobullous lesions developed. Routine histologic and immunologic studies fulfilled the criteria for the diagnosis of bullous systemic lupus erythematosus. Indirect immunofluorescence showed antinuclear antibodies without basement membrane zone fluorescence. We destroyed the nuclear antigens of the indirect immunofluorescence substrate with 2 mol/L sodium chloride, which unmasked basement membrane zone linear IgG staining. We also confirmed anti-basement membrane zone antibodies by employing a new technique of direct immunofluorescence on sodium chloride-split skin. Our finding prove that a thorough search for anti-basement membrane zone antibodies can be revealing. Our results support the idea that a subset of bullous systemic lupus erythematosus has the staining characteristics of epidermolysis acquisita, with the dermal side of the split skin showing linear immunoglobulin deposition.

Direct immunofluorescence studies of sodium chloride-separated skin in the differential diagnosis of bullous pemphigoid and epidermolysis bullosa acquisita

Bullous pemphigoid and epidermolysis bullosa acquisita may have indistinguishable clinical, histologic, and routine immunohistologic features. In those cases these two diseases can be reliably distinguished in routine diagnostic studies only in seropositive cases by tests on lamina lucida-split skin and in research studies by direct immunoelectron microscopy or, in patients with circulating autoantibodies, by immunoblotting studies. The use of these methods is limited by the expense and unavailability of the methods, the requirement for circulating autoantibodies, or both. We describe a method to distinguish between the two diseases on the basis of findings of direct immunofluorescence of a biopsy specimen after separation through the lamina lucida with 1.0 mol/L sodium chloride. The IgG appeared in the dermal side of the split specimens in epidermolysis bullosa acquisita and predominantly or exclusively in the epidermal side in pemphigoid. The method was found to be relatively simple, inexpensive, applicable to specimens preserved in transport media, and 100% reliable in our group of 22 patients.

Intraepidermal leakage of plasma proteins after tape stripping of normal skin and uninvolved psoriatic skin

Following tape stripping of normal skin and uninvolved psoriatic skin, there was an early leakage of plasma proteins such as fibrinogen, fibronectin and immunoglobulins. This was accompanied by migration of mononuclear and polymorphonuclear cells into the epidermis. Both events appeared earlier, were more pronounced and lasted longer in psoriatic subjects than in controls.