Basement Membrane Zone Of Skin Research Articles

S2k guidelines on diagnosis and treatment of linear IgA dermatosis initiated by the European Academy of Dermatology and Venereology.

Linear IgA dermatosis (LAD) is a rare subepidermal autoimmune bullous disease (AIBD) defined by predominant or exclusive immune deposits of immunoglobulin A at the basement membrane zone of skin or mucous membranes. This disorder is a rare, clinically and immunologically heterogeneous disease occurring both in children and in adults. The aim of this project is to present the main clinical features of LAD, to propose a diagnostic algorithm and provide management guidelines based primarily on experts' opinion because of the lack of large methodologically sound clinical studies. These guidelines were initiated by the European Academy of Dermatology and Venereology (EADV) Task Force Autoimmune Bullous Diseases (AIBD). To achieve a broad consensus for these S2k consensus-based guidelines, a total of 29 experts from different countries, both European and non-European, including dermatologists, paediatric dermatologists and paediatricians were invited. All members of the guidelines committee agreed to develop consensus-based (S2k) guidelines. Prior to a first virtual consensus meeting, each of the invited authors elaborated a section of the present guidelines focusing on a selected topic, based on the relevant literature. All drafts were circulated among members of the writing group, and recommendations were discussed and voted during two hybrid consensus meetings. The guidelines summarizes evidence-based and expert opinion-based recommendations (S2 level) on the diagnosis and treatment of LAD. These guidelines will support dermatologists to improve their knowledge on the diagnosis and management of LAD.

Emerging Gene Therapeutics for Epidermolysis Bullosa under Development.

The monogenetic disease epidermolysis bullosa (EB) is characterised by the formation of extended blisters and lesions on the patient's skin upon minimal mechanical stress. Causal for this severe condition are genetic mutations in genes, leading to the functional impairment, reduction, or absence of the encoded protein within the skin's basement membrane zone connecting the epidermis to the underlying dermis. The major burden of affected families justifies the development of long-lasting and curative therapies operating at the genomic level. The landscape of causal therapies for EB is steadily expanding due to recent breakthroughs in the gene therapy field, providing promising outcomes for patients suffering from this severe disease. Currently, two gene therapeutic approaches show promise for EB. The clinically more advanced gene replacement strategy was successfully applied in severe EB forms, leading to a ground-breaking in vivo gene therapy product named beremagene geperpavec (B-VEC) recently approved from the US Food and Drug Administration (FDA). In addition, the continuous innovations in both designer nucleases and gene editing technologies enable the efficient and potentially safe repair of mutations in EB in a potentially permanent manner, inspiring researchers in the field to define and reach new milestones in the therapy of EB.

Epidermolysis Bullosa Acquisita Presenting a Mix of Classical and Atopiform Features

Epidermolysis bullosa acquisita (EBA) is a rare acquired autoimmune bullous disorder. This disease is characterised by the presence of autoantibodies targeted against Collagen VII of the anchoring fibrils in the basement membrane zone of skin and mucous membranes. The two most common presentations of EBA are the classical or mechano-bullous and the bullous pemphigoid (BP) like forms. Patients with BP-like form of EBA have generally profuse skin lesions suggestive of BP in some areas and EBA in others. We present a case of inflammatory BP like EBA, in a young woman, who presented with classical and also atypical atopiform features.

011 Targeted inhibition of complement C3 deposition at the basement membrane zone in pemphigoid disease

Autoantibodies against structural proteins of the basement membrane zone (BMZ) cause dermal-epidermal adhesion loss in pemphigoid diseases. Biopsies usually show IgG and C3 at the BMZ, indicating complement (C) activation that facilitates attraction and activation of inflammatory cells and blister formation. We generated 23 anti BP180 antibody (ab) clones from two bullous pemphigoid (BP) patients by phage display. All ab clones were validated by ELISA and immunofluorescence (IF). Unexpectedly, our monovalent scFv abs displaced patient IgG from immobilized antigen in vitro. When injected into human skin organ culture, anti BP180 scFvs were non pathogenic, because for pathogenicity bivalent abs with cross linking and C fixing properties are required. As a proof of concept we exploited this non pathogenicity by designing proteins that allow targeted C inhibition at the BMZ: An anti BP180 scFv was fused with a C1s inhibiting domain and tested for targeted inhibition of the classical C activation pathway at the BMZ, in an ex vivo assay. Our recombinant molecule bound to normal human skin sections preincubated with BP sera and efficiently inhibited C3 fixation and C5a anaphylatoxin liberation. Another fusion protein designed for targeted inhibition of the alternative pathway was not effective in our model, illustrating the dependence on the classical C activation pathway in human BP. Because BP180 is expressed at the BMZ of skin, mucous membranes, and the retina, this innovative approach may be translated to various C dependent diseases affecting these tissues, e.g., mucous membrane pemphigoid, epidermolysis bullosa acquisita, or age related macular degeneration. Alternatively, the compound domain may be exchanged for other pharmaceutically active drugs, allowing for targeted delivery to the BMZ in a broad range of other diseases of the skin and mucous membranes.

Ocular involvement in a case of dystrophic epidermolysis bullosa with conjunctival blistering without eyelid or corneal disease: A rare case report

Epidermolysis bullosa (EB) is an autoimmune mucocutaneous disorder associated with abnormalities of the basement membrane zone of skin and mucous membranes, characterized by blister formation in response to minor trauma. Ocular involvement is common in autosomal dominant variant of dystrophic EB (DDEB), but the incidence of involvement of ocular structures varies widely among different patients as well as among different subtypes. Conjunctival blistering without eyelid or corneal disease is one of the most common ocular manifestations. Here, we present a rare case of DDEB in a 4-year-old boy with conjunctival blister formation without eyelid or corneal involvement. The patient was managed conservatively with lubricating eye drops, and the conjunctival blister resolved subsequently. The major treatment modality is the use of ocular lubricants. Protection of eye from minor trauma such as rubbing is most important to prevent ocular complications.

Gene silencing of extracellular matrix protein 1 (ECM1) results in phenotypic alterations of dermal fibroblasts reminiscent of clinical features of lichen sclerosus

BackgroundLichen sclerosus (LS) is an acquired inflammatory mucocutaneous disease affecting the anogenital area, characterized histologically by hyalinosis and thickened vessel walls in the dermis. The presence of serum autoantibodies against extracellular matrix protein 1 (ECM1) in LS patients may suggest its involvement in disease pathogenesis. ObjectiveTo examine if reduced ECM1 production by dermal fibroblasts contributes to the pathogenic features of LS. MethodsGene expression in ECM1 knockdown human dermal fibroblasts was analyzed by cDNA microarray. Functional enrichment for genes involved in cellular functions was conducted. Protein expression was analyzed by ELISA and confocal laser scanning microscopy using LS skin. ResultsMicroarray analysis identified 3035 differentially expressed genes in ECM1 knockdown cells, wherein 1471 were upregulated genes related exclusively to cell adhesion, proliferation, apoptosis, intracellular signaling, and extracellular matrix organization. Further narrowing with criteria specific for localization and function of ECM1 identified 48 upregulated genes identified to have structural, fibrogenic, and carcinogenic properties. Of these, laminin-332 and collagen-IV displayed altered immunolabeling within the basement membrane zone (BMZ) and dermal vessels in LS skin, similar to that of collagen-VII, which exhibited unchanged transcription levels in ECM1-knockdown fibroblasts. Collagen-VII bound to recombinant ECM1 in a solid-phase immunoassay and colocalized with ECM1 in the skin BMZ. Further, ECM1-knockdown fibroblasts exhibited a marked delay in cell migration and gel contraction. ConclusionIn the absence of ECM1 expression in fibroblasts there is selective dysregulation and disassembly of structural and extracellular matrix molecules, which may result in microstructural abnormalities reminiscent of LS.

Matrix Metalloproteinase 9 (MMP9) Inhibitor Prevents Mustard Induced Microvesication and Promotes Cutaneous Wound Healing

Skin exposure to the chemical warfare agent, sulfur mustard (bis‐2‐chloroethylsulfide, SM), is characterized by severe blister formation and a prolonged inflammatory response. The mechanisms of these SM toxic effects are still poorly defined, and effective medical countermeasures against SM‐induced cutaneous injury have yet to be established. Animal models demonstrate disruption of the skin architecture at the dermal‐epidermal junction (DEJ) when exposed to the vesicant, SM; the damage may be further exacerbated by overexpression of MMP9. Studies show MMP9 degrades basement membrane (BM) components and regulates inflammation in tissue injuries; inhibition of MMP9 suppresses inflammation and promotes wound repairs in tumors and various wound models. In the present studies, ([N‐hydroxy‐3‐phenyl‐2‐(4‐phenylbenzenesulfonamido) propanamide], BiPS), a specific MMP9 inhibitor, was evaluated for its ability to prevent microvesication, suppress inflammation, and promote wound healing following SM exposure using the mouse ear vesicant model. Treatment of male CD1 mouse ear skin with SM (0.08 mg) caused a characteristic SM induced injury including edema, inflammatory cell infiltration, and the formation of microvesicles at the DEJ. Expression of MMP9 mRNA and protein in the skin progressively increased with time 24–168 h following SM exposure. Immunofluorescence studies showed disruption of the BM molecule type IV collagen (COL4), increased expression of inflammation marker, COX2, and upregulation of the skin wound marker keratin 6 (K6) in SM induced skin wounds. SM also caused macrophage (F4/80) accumulation in the tissue which persisted up to 168 h post exposure. Pretreatment of ear skin with BiPS significantly reduced SM‐induced dermal edema and maintained the integrity of the DEJ‐BM as evidenced by contiguous expression of COL4. At 168 h post SM exposure, mRNA and protein expression of MMP9 was significantly downregulated in BiPS treated mice. BiPS treatment also reduced the number of macrophages accumulating in the tissue, and suppressed expression of COX2, and downregulated expression of K6. Taken together, these data indicate that BiPS treatment was able to suppress both inflammation and degradation of BM zone in skin due to SM. This compound was effective in targeting MMP9 to protect against SM induced microvesication and promote wound repairs. MMP9 inhibitors may be useful as medical countermeasure against SM‐induced cutaneous injury.Support or Funding InformationSupported by NIH grants ES005022 and AR055073.

Ultrastructural characterization of damage in the basement membrane of facial melasma.

The pathogenesis of melasma is not fully understood, and the role of skin basement membrane zone (BMZ) alterations in disease development and the maintenance of hypermelanogenesis are also poorly known. We performed a comparative study to characterize the ultrastructural alterations that occur in BMZ in melasma and adjacent normal skin, as well as we discuss the implications of these changes in the physiopathology of the disease. Pairs of facial skin biopsies (2 mm) from 10 women with melasma and normal skin (< 2 cm apart) were processed by Transmission Electronic Microscopy or immunohistochemistry for Melan-A counterstained with Periodic acid-Schiff stain. Cytoplasmic organelles (from keratinocyte or melanocyte), BMZ damage were assessed and melanocyte counting (total and pendulous) was done. There was greater amount of cytoplasmic organelles inside basal keratinocytes and melanocytes in melasma, as well as structural damaged areas in the lamina densa (disruptions, gaps, lower density and thinning) and anchoring fibrils (lamina lucida), compared to healthy adjacent skin. Areas with pendulous melanocytes are characterized by discontinuity of BMZ ultrastructure. The prominence of cytoplasmic organelles from melanocytes and keratinocytes evidences the involvement of both cell groups in melasma. The damage in the lamina densa and lamina lucida suggest the role of upper dermis injury/repair process in the pathogenesis of the disease.

The direct binding of collagen XVII and collagen IV is disrupted by pemphigoid autoantibodies

The basement membrane zone (BMZ) is framed by hemidesmosomes and extracellular matrix (ECM) including collagen IV (COL4). Hemidesmosomes are multiprotein complexes that include collagen XVII (COL17). BMZ proteins can be targeted in autoimmune subepidermal blistering diseases, e.g., pemphigoid targeting COL17. The blistering mechanisms in pemphigoid have not been fully elucidated, especially in mucous membrane pemphigoid (MMP), which mainly affects the mucosa. In this study, we showed that oral lesions in pemphigoid may be attributed to the inhibition of protein–protein interactions by autoantibodies. Using immunoprecipitation, we revealed that COL17 directly binds to COL4 in normal human keratinocytes and normal human oral keratinocytes. In particular, the C-terminus of COL17 is binding site to COL4 in oral keratinocytes. The precise COL4-binding region on COL17 was determined by protein–protein binding assay to be from amino acid Gly1175 to Asp1340 on the C-terminus. MMP-IgG or mAb recognizing the C-terminus hindered the interaction of COL17 with COL4 in oral keratinocytes. Furthermore, keratinocyte adhesion strength to COL4-coated plates was significantly reduced by the treatment of mAb against the C-terminus. In addition, the inflammatory infiltrates around perilesions were significantly less in MMP compared to BP. These results indicate that pemphigoid IgG targeting the C-terminus plays a pathogenic role in blister formation in the oral mucosa to inhibit protein interactions with less inflammation.Collagen XVII directly binds to collagen IV at the basement membrane zone in both skin and oral mucosa. Mucous membrane pemphigoid autoantibodies targeting the C-terminus of collagen XVII hinder this binding and induce the detachment of basal cells in the oral mucosa. This mechanism leads to oral lesions that show less inflammation than the skin lesions show.

Bleomycin-induced epithelial–mesenchymal transition in sclerotic skin of mice: Possible role of oxidative stress in the pathogenesis

Epithelial–mesenchymal transition (EMT) derived myofibroblasts are partly responsible for the increased collagen synthesis and deposition that occur in tissue fibrosis; however EMT occurrence in skin fibrosis and its mechanism remain unknown. The aim of this study was to investigate whether epithelial cells undergo EMT and determine the role of oxidative stress in this process. BALB/c mice were subcutaneously injected with bleomycin (BLM) or phosphate buffer saline (PBS) into the shaved back daily for 2, 3, and 4weeks. Skin collagen deposition was evaluated by histopathology and Western blotting. EMT characteristics in the skin were determined by histopathology and immunofluorescent staining for E-cadherin and vimentin, which were further evaluated by Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR). To investigate the role of oxidative stress in EMT, the antioxidant N-acetylcysteine (NAC) was intraperitoneally (100mg/kg body weight/day) injected daily for 3weeks. The epithelial suprabasal cells were detached from the basement membrane zone (BMZ) in the sclerotic skin treated with BLM. Immunofluorescent staining indicated vimentin-positive epithelial cells frequently occurring in the thickened epidermis of BLM-treated mice. Western blotting and RT-PCR showed that the expression of E-cadherin was significantly decreased but that of vimentin significantly increased in the skin treated with BLM. NAC attenuated BLM induced oxidative damage, changes in E-cadherin and vimentin expressions and collagen deposition in the sclerotic skin of mice. This study provides the first evidence that BLM induces the EMT of the epithelial cells superficial to the basement membrane zone in the skin fibrosis. Oxidative stress may contribute, at least in part, to BLM induced EMT and skin fibrosis in mice.

Differences in basement membrane zone components of normal conjunctiva, conjunctiva in glaucoma and normal skin

To describe the distribution of basement membrane zone (BMZ) components in normal conjunctiva, conjunctiva of patients with glaucoma and normal skin. Thirty-five normal conjunctival biopsies and 16 conjunctival biopsies of patients with glaucoma under topical anti-glaucomatous therapy were examined by immunohistochemistry. Antibodies were directed against laminin α chains, laminin subchains α1, α2, α3, β1, β3, γ1, γ2, γ3, kalinin, β4-integrin, and collagens IV and VII. Results were compared to the antigen distribution at the BMZ in normal skin. The BMZ of skin stained positive for all antibodies tested. In contrast to skin, the BMZ of normal conjunctiva was negative for laminin subunits α2, β1, β3, γ2 and γ3 in most or all specimens. Positive findings at the conjunctival BMZ of patients with glaucoma were comparable to normal conjunctiva for laminin α, α1, β3, γ1, γ3, laminin 5, β4-integrin, collagen IV and collagen VII. However, staining of the BMZ with antibodies to laminin β1 (p=0.002) and γ2 (p=0.017) was seen in a significantly higher rate in glaucoma compared to controls. Characteristic differences exist in the antigenicity of the BMZ in normal skin, normal conjunctiva and conjunctiva from patients with glaucoma, especially for laminin subchains. These differences may explain the variable ocular involvement in diseases of the BMZ. Moreover, they may explain the susceptibility of patients with glaucoma to develop mucous membrane pemphigoid-like disease. Alterations in conjunctival BMZ in glaucoma may be induced by long-term topical anti-glaucoma medications including various preservation agents.

Functional Characterization of an IgE-Class Monoclonal Antibody Specific for the Bullous Pemphigoid Autoantigen, BP180

BP180 (collagen XVII) is the target antigen in several autoimmune diseases including bullous pemphigoid (BP). Both IgE and IgG class autoantibodies have been shown to be pathogenic in BP; however, studies designed to elucidate the patho-mechanisms mediated specifically by the IgE-class autoantibodies are limited by the low levels (ng/mL) of IgE in human sera. In this report, we developed mouse IgE class monoclonal antibodies (MAbs) against the immunodominant NC16A domain of the human BP180 protein and characterized two of the resultant MAbs, designated 395A5 and 395D2. Epitope mapping studies revealed that both MAbs target segment 2 of NC16A, as was described for IgE and IgG class BP autoantibodies. Also similar to BP IgE, MAb 395A5 showed indirect immunofluorescence labeling of the basement membrane zone (BMZ) of human skin, stimulated histamine release from mast cells when triggered with NC16A, and induced keratinocyte production of IL-8. The 395D2 MAb was also able to trigger antigen-specific histamine release from mast cells; however, in contrast to BP IgE and 395A5, 395D2 did not label the cutaneous BMZ, nor did it induce IL-8 production in keratinocytes. In summary, these studies underscore the importance of functionally characterizing MAbs generated for use in human disease models. The 395A5 IgE class murine MAb was shown to share several key functional properties with the pathogenically active IgE produced by BP patients. We therefore expect that this MAb will prove to be a useful tool for dissecting the mechanisms used by BP180-NC16A-specific IgE antibodies in the induction of BP skin lesions.

Purification and identification of anti-BP180 NC16A antibodies from the sera of patients with bullous pemphigoid or herpes gestationis

Objective To develop a method to purify and identify anti-BP180 NC16A antibodies from the sera of patients with bullous pemphigoid (BP) or herpes gestationis.Methods The GST/NC16A fusion protein was expressed in a prokaryotic expression vector pGEX-2TBP180NC16A,and then crosslinked to glutathione sepharose beads.Anti-BP180 NC16A antibodies were isolated from the sera of 3 patients with BP and 2 patients with herpes gestationis by affinity chromatography,and analyzed by immunofluorescence,Western blot and enzyme linked immunosorbent assay (ELISA).Results The GST/NC16A fusion protein with a relative molecular mass of 37 000 was successfully expressed by the prokaryotic vector pGEX-2TBP180NC16A.Purified anti-BP180 NC16A antibodies were obtained from the sera of patients by the affinity chromatography,and ELISA revealed that the concentration of anti-BP180 NC16A was 2.4 mg/ml.The purified antibody could bind to the basement membrane zone of human skin,suggesting a strong biological activity of the antibodies.Western blot showed a single band corresponding to the expected molecular mass for anti-BP180 NC16A antibodies,indicating a high purity of the isolated antibodies.Conclusion The anti-BP180 NC16A antibodies purified by microbead-based affinity chromatography from the sera of patients with BP or herpes gestationis are highly active and specific. Key words: Pemphigoid, bullous; Pemphigoid gestationis; BP180 NC16A

Pemphigoid gestationis

Pemphigoid gestationis is a rare autoimmune subepidermal bullous dermatosis that occurs during pregnancy and postpartum. Diagnosis is made on the basis of the presence of a subepidermal vesicle on routine histologic examination and of linear deposition of complement along the basement membrane zone of perilesional skin. The disorder is accompanied by severe pruritus and polymorphous bullous skin lesions. Clinical diagnosis is confirmed by histology and positive cutaneous immunofluorescence and immunoelectron microscopy tests (linear deposition of C3, with or without immunoglobulin G, along the basement membrane zone, within the lamina lucida, and localized to the proximal part of anchoring filaments of the epidermal fragment of salt-split skin). Enzyme-linked immunosorbent assay for pemphigoid gestationis antibody (BP180) is commercially available. If local treatment fails, systemic corticosteroid therapy should be administered. Oral corticosteroids are the therapeutic mainstay in pregnancy and postpartum. The prognosis is good for mother and child, except that there is a risk of preterm delivery and of moderate fetal growth restriction. Recurrence is possible during subsequent pregnancies. There is no significant maternal morbidity or mortality.

Early intra-amniotic gene transfer using lentiviral vector improves skin blistering phenotype in a murine model of Herlitz junctional epidermolysis bullosa

Mutations of the LAMB3 gene cause a lethal form of junctional epidermolysis bullosa (JEB). We hypothesized that early intra-amniotic gene transfer in a severe murine model of JEB would improve or correct the skin phenotype. Time-dated fetuses from heterozygous LAMB3(IAP) breeding pairs underwent ultrasound guided intra-amniotic injection of lentiviral vector encoding the murine LAMB3 gene at embryonic day 8 (E8). Gene expression was monitored by immunohistochemistry. The transgenic laminin-β3 chain was shown to assemble with its endogenous partner chains, resulting in detectable amounts of laminin-332 in the basement membrane zone of skin and mucosa. Ultrastructually, the restoration of ∼60% of hemidesmosomal structures was also noted. Although we could correct the skin phenotype in 11.9% of homozygous LAMB3(IAP) mice, none survived beyond 48 h. However, skin transplants from treated E18 homozygous LAMB3(IAP) fetuses maintained normal appearance for 6 months with persistence of normal assembly of laminin-332. These results demonstrate for the first time long-term phenotypic correction of the skin pathology in a severe model of JEB by in vivo prenatal gene transfer. Although survival remained limited due to the limitations of this mouse model, this study supports the potential for treatment of JEB by prenatal gene transfer.

Role of Dermal-Epidermal Basement Membrane Zone in Skin, Cancer, and Developmental Disorders

The dermal-epidermal basement membrane zone is an important epithelial and stromal interface, consisting of an intricately organized collection of intracellular, transmembrane, and extracellular matrix proteins. The basement membrane zone has several main functions including acting as a permeability barrier, forming an adhesive interface between epithelial cells and the underlying matrix, and controlling cellular organization and differentiation. This article identifies key molecular players of the dermal-epidermal membrane zone, and highlights recent research studies that have identified structural and functional roles of these components in the context of various blistering, neoplastic, and developmental syndromes.

Epidermolysis Bullosa

Inherited epidermolysis bullosa (EB), having an overall incidence of only about 19 in every 1 million live births, encompasses many phenotypically and genotypically distinct diseases characterized by the presence of recurrent blisters, mechanical fragility of the skin and other epithelial structures (most notably the cornea and gastrointestinal tract), and scar formation. Each disease is the result of mutations within any of 10 specific structural proteins (keratins, laminins, collagens, integrins) within the basilar keratinocyte or the skin basement membrane zone. Two of the more severe subtypes, junctional and dystrophic EB, often involve many extracutaneous tissues. If severe, these conditions may be life threatening. Recent studies in wounds that had been artificially induced on normal skin, both in rodents and in human volunteers, have suggested that thymosin beta4 may be effective in promoting epithelial migration across the wounds. A randomized double-blind clinical trial has been recently organized to determine whether this novel biologic agent may be beneficial in promoting wound healing in patients with junctional and dystrophic EB. To do so, a solitary noninfected cutaneous wound of standardized size will be treated topically on a daily basis with either one of three concentrations of thymosin beta4 or a placebo control. Serial wound healing will be quantitated by computerized digital-imaging technique. At the same time, the occurrence of adverse effects will be sought, so as to confirm the safety of thymosin beta4 when applied to EB skin, both in children and in adults. Although as yet unproven, topically applied thymosin beta4 may prove to be an extremely important addition to the overall management of patients with this potentially devastating disease.

Genkwanin up‐regulates the transcriptional activation of human type vii collagen gene promoter

In a recent study, stimulating the formation of anchoring fibrils at the basement membrane zone in skin contributed to preventing skin ageing, such as wrinkle formation. Expression of the type VII collagen gene induces the formation of anchoring fibrils composed mainly of collagen type VII. We therefore transiently transfected a keratinocyte cell line with the plasmids containing type VII collagen gene promoter located upstream of the luciferase gene. We investigated the promoter activity under the presence of flavonoids and we found that Genkwanin up‐regulates the transcriptional activation of human type VII collagen gene promoter.

Intravenously Injected Human Fibroblasts Home to Skin Wounds, Deliver Type VII Collagen, and Promote Wound Healing

Patients with dystrophic epidermolysis bullosa (DEB) have incurable skin fragility, blistering, and multiple skin wounds because of mutations in the gene that encodes for type VII collagen (C7), which holds together the epidermal and dermal layers of human skin. The intradermal injection of gene-corrected DEB fibroblasts, recombinant C7 protein, or lentiviral vectors expressing C7 is a potential therapy for DEB. Nevertheless, severe DEB causes widespread wounds and treatment would require multiple injections. An alternative strategy might be to inject genetically engineered cells into the patient's circulation that home to the skin wounds and deposit the transgene product. In this study, we demonstrated that intravenously (IV) injected, molecularly engineered DEB fibroblasts (overexpressing human C7) homed to murine skin wounds and continuously delivered C7 at the wound site, where it incorporated into the skin's basement membrane zone and formed anchoring fibril structures. Wounds made on murine or grafted human skin demonstrated accelerated healing when the animals were IV injected with gene-corrected DEB fibroblasts. Our data demonstrate that abundant C7 promotes wound healing. This is also the first evidence that IV injected, molecularly engineered skin fibroblasts can deliver C7 to skin wounds. This strategy could be useful for treating DEB patients.

Defective in vivo expression and apparently normal in vitro expression of a newly identified 105-kDa lower lamina lucida protein in dystrophic epidermolysis bullosa.

We have previously identified a novel 105-kDa lower lamina lucida protein detected by the autoantibodies from a group of patients who developed a unique immune-mediated subepidermal bullous dermatosis. We sought to determine if this novel basement membrane zone (BMZ) protein is normally expressed in the skin of patients with various subsets of epidermolysis bullosa (EB). Indirect immunofluorescence microscopy performed on non-lesional skin sections from patients with three major EB subsets revealed absence or significantly reduced expression of this novel BMZ protein in 20 out of 23 skin sections from patients with generalized dominant and recessive dystrophic EB. However, immunoblot analyses with the autoantibodies on Western-blotted proteins revealed that a comigrating 105-kDa protein is present in both cytosol extracts (n = 6) and conditioned media (n = 3) of cultured dermal fibroblasts derived from patients with dystrophic EB, as well as those cultured from two healthy individuals. Although the reason for such disparate findings is not known, the defective in vivo expression of this novel 105-kDa protein in dystrophic EB is presumably not due to a failure of fibroblasts to synthesize or secrete the protein. It is possible, however, that the 105-kDa protein may be unable to incorporate into the BMZ because it is produced in a dysfunctional form, or its BMZ binding site is missing. It is also possible that other structural alterations in skin BMZ, which occur in dystrophic EB, result in masking of the antigenic binding by the autoantibody when intact BMZ is probed.(ABSTRACT TRUNCATED AT 250 WORDS)