Inhibition of Glucose Metabolism Abrogates the Effector Phase of Bullous Pemphigoid-Like Epidermolysis Bullosa Acquisita.

Bullous pemphigoid-like epidermolysis bullosa acquisita (EBA) is an autoantibody-driven, granulocyte-mediated skin disease. The role of cellular metabolism and its potential as a therapeutic target in EBA are unknown. We investigated the effect of 2-deoxy-D-glucose and metformin in the antibody transfer model of EBA. Both metformin and 2-deoxy-D-glucose attenuated disease in this model. Subsequently, we demonstrate that the stimulation of neutrophils by immune complexes increases the rate of aerobic glycolysis and that this increase is required to induce the release of leukotriene B4 and ROS critical for EBA. Accordingly, 2-deoxy-D-glucose as an inhibitor of the glycolytic enzymes hexokinase and phosphoglucose isomerase and heptelidic acid, an inhibitor of glyceraldehyde-3-phosphate dehydrogenase, blunted this neutrophil response. Decreasing oxidative phosphorylation, metformin also inhibited this neutrophil response but only when applied in suprapharmacological doses, rendering a direct effect of metformin on neutrophils in vivo unlikely. Considering that the oxidative phosphorylation inhibitor oligomycin likewise inhibits these neutrophil responses and that immune complex stimulation does not alter the rate of oxidative phosphorylation, these results, however, suggest that intact mitochondria are necessary for neutrophil responses. Collectively, we highlight 2-deoxy-D-glucose and metformin as potential drugs and both glycolysis and oxidative phosphorylation in neutrophils as promising therapeutic targets in EBA.

A Mitochondrial Polymorphism Alters Immune Cell Metabolism and Protects Mice from Skin Inflammation.

Several genetic variants in the mitochondrial genome (mtDNA), including ancient polymorphisms, are associated with chronic inflammatory conditions, but investigating the functional consequences of such mtDNA polymorphisms in humans is challenging due to the influence of many other polymorphisms in both mtDNA and the nuclear genome (nDNA). Here, using the conplastic mouse strain B6-mtFVB, we show that in mice, a maternally inherited natural mutation (m.7778G > T) in the mitochondrially encoded gene ATP synthase 8 (mt-Atp8) of complex V impacts on the cellular metabolic profile and effector functions of CD4+ T cells and induces mild changes in oxidative phosphorylation (OXPHOS) complex activities. These changes culminated in significantly lower disease susceptibility in two models of inflammatory skin disease. Our findings provide experimental evidence that a natural variation in mtDNA influences chronic inflammatory conditions through alterations in cellular metabolism and the systemic metabolic profile without causing major dysfunction in the OXPHOS system.

Structural and biophysical characterization of the type VII collagen vWFA2 subdomain leads to identification of two binding sites.

Type VII collagen is an extracellular matrix protein, which is important for skin stability; however, detailed information at the molecular level is scarce. The second vWFA (von Willebrand factor type A) domain of type VII collagen mediates important interactions, and immunization of mice induces skin blistering in certain strains. To understand vWFA2 function and the pathophysiological mechanisms leading to skin blistering, we structurally characterized this domain by X-ray crystallography and NMR spectroscopy. Cell adhesion assays identified two new interactions: one with ß1 integrin via its RGD motif and one with laminin-332. The latter interaction was confirmed by surface plasmon resonance with a KD of about 1 mm. These data show that vWFA2 has additional functions in the extracellular matrix besides interacting with type I collagen.

Optimization of reference gene panels for gene expression analysis in preclinical models of inflammatory skin diseases.

Reverse transcriptase qPCR is the most common method to determine and compare mRNA expression levels and relies on normalization using reference genes. The expression levels of the latter, however, are themselves often variable between experimental conditions, thus compromising the results. Using the geNorm algorithm, we have examined seven genes with respect to their suitability as reference genes for gene analysis in mouse models of skin inflammation, using the antibody transfer model of epidermolysis bullosa acquisita and in the Aldara™ -induced psoriasiform dermatitis. Our results indicate that the combination of at least 2-3 reference genes is required for stable normalization. Notably, the expression of reference genes changed when comparing lesional skin of both models or when comparing lesional to non-lesional skin within one model. This highlights the need for precise selection of reference genes dependent on the specific experimental setup.

Meta-analysis of the clinical and immunopathological characteristics and treatment outcomes in epidermolysis bullosa acquisita patients.

BACKGROUND: Epidermolysis bullosa acquisita (EBA) is an orphan autoimmune disease. Several clinical phenotypes have been described, but subepidermal blistering is characteristic of all variants. Limited data on clinical and immunopathological characteristics and treatment outcomes in EBA are available. To fill this gap, we collected this information from EBA cases, meeting current diagnostic criteria, published between 1971 and 2016. RESULTS: We identified 1159 EBA cases. This number must be, however, interpreted with caution, as it is not possible to check for multiple reporting. The analysis of all cases indicated that EBA affects all age groups (median: 50 years, range: 1 to 94 years) at an equal gender distribution. Non-mechanobullous (non-MB) forms of EBA were observed in 55% of patients, whereas the mechanobullous variant (MB-EBA) or a combination of both variants was described in 38 or 7% of patients, respectively. Type VII collagen (COL7)-specific autoantibodies were primarily of the IgG isotype, but anti-COL7 IgA, IgM and IgE were also documented. Comparison of the 2 clinical EBA types showed a higher frequency of IgA deposits in non-MB EBA as opposed to MB EBA. Mucous membrane involvement was observed in 23% of patients, and 4.4% of cases were associated with other chronic inflammatory diseases. Of note, IgA deposits were more frequently observed in cases with mucous membrane involvement. Our analysis indicated that EBA is difficult to treat and that the choice of treatment varies widely. Chi square was applied to identify medications associated with complete remission (CR). Considering all EBA cases, intravenous immunoglobulin (IVIG, p = 0.0047) and rituximab (p = 0.0114) were associated with CR. Subgroup analysis demonstrated that no treatment was associated with CR for non-MB EBA, while IVIG (p = 0.003) was associated with CR in MB EBA. CONCLUSIONS: Within the limitations of the study, we here document the clinical and immunopathological characteristics and treatment outcomes in a large cohort of EBA patients. The observed associations of single drugs with treatment outcome may serve as a guide to develop clinical trials.

The Immunometabolomic Interface Receptor Hydroxycarboxylic Acid Receptor 2 Mediates the Therapeutic Effects of Dimethyl Fumarate in Autoantibody-Induced Skin Inflammation.

The drug dimethyl fumarate (DMF) is in clinical use for the treatment of psoriasis and multiple sclerosis. In addition, it has recently been demonstrated to ameliorate skin pathology in mouse models of pemphigoid diseases, a group of autoimmune blistering diseases of the skin and mucous membranes. However, the mode of action of DMF in inflammatory skin diseases has remained elusive. Therefore, we have investigated here the mechanisms by which DMF improves skin pathology, using the antibody transfer model of bullous pemphigoid-like epidermolysis bullosa acquisita (EBA). Experimental EBA was induced by transfer of antibodies against collagen VII that triggered the infiltration of immune cells into the skin and led to inflammatory skin lesions. DMF treatment reduced the infiltration of neutrophils and monocytes into the skin explaining the improved disease outcome in DMF-treated animals. Upon ingestion, DMF is converted to monomethyl fumarate that activates the hydroxycarboxylic acid receptor 2 (HCA2). Interestingly, neutrophils and monocytes expressed Hca2. To investigate whether the therapeutic effect of DMF in EBA is mediated by HCA2, we administered oral DMF to Hca2-deficient mice (Hca2-/-) and wild-type littermates (Hca2+/+) and induced EBA. DMF treatment ameliorated skin lesions in Hca2+/+ but not in Hca2-/- animals. These findings demonstrate that HCA2 is a molecular target of DMF treatment in EBA and suggest that HCA2 activation limits skin pathology by inhibiting the infiltration of neutrophils and monocytes into the skin.

The Value of Type IV Collagen Immunohistochemical Staining in the Differential Diagnosis of Autoimmune Subepidermal Bullous Diseases.

Autoimmune subepidermal bullous diseases (AISBDs) exhibit various clinical presentations, histological appearances, prognoses, and responses to treatment. Many diagnostic techniques, such as direct immunofluorescence (IF), indirect salt-split skin IF, and enzyme-linked immunosorbent assays, are used in the differential diagnoses of AISBDs. However, these techniques require fresh frozen tissue, expensive laboratory equipment, and sophisticated laboratory techniques. The purpose of this study was to evaluate the value of type IV collagen immunohistochemical (IHC) staining for the differential diagnosis of AISBDs. Paraffin-embedded blocks of skin biopsies were selected from 28 patients with autoimmune subepidermal bullous diseases. Among these 28 cases, 24 patients exhibited bullous pemphigoid (BP), 2 exhibited epidermolysis bullosa acquisita (EBA), 1 exhibited linear immunoglobulin A dermatosis (LAD), and 1 exhibited bullous systemic lupus erythematosus (BSLE). Sections were stained for type IV collagen and examined to determine the location of type IV collagen in the subepidermal blister. Type IV collagen positivity was observed on the base of the subepidermal blister in patients with BP (24 of 24 cases) and LAD (1 of 1 case). Staining was observed on the roof of the blister in patients with EBA (2 of 2 cases) and BSLE (1 of 1 case), and irregular staining was also observed on the base in patients with EBA. In conclusion, type IV collagen IHC staining is a simple and useful diagnostic technique for the differential diagnosis of AISBDs.

Neutrophil Adhesion Is a Prerequisite for Antibody-Mediated Proteolytic Tissue Damage in Experimental Models of Epidermolysis Bullosa Acquisita.

Although uncontrolled proteolytic activity mediated by activated neutrophils is a major reason for tissue damage, therapeutic approaches using protease inhibitors are inefficient. Here, we investigated the role of the immune complex-induced neutrophil adhesion and protease release in tissue damage. We show both in vitro and in vivo that immune complex-mediated neutrophil adhesion to the target tissue depends on ß2 integrins. Without affecting elastase or reactive oxygen species release, blocking of adhesion drastically inhibited tissue damage in an experimental model of autoantibody-mediated skin blistering disease. By using a cell-bound fluorescent resonance energy transfer-based elastase sensor, we detected elastase enzyme activity on the surface of adherent cells resistant to protease inhibitors. Inhibitor resistance was lost by CD18 blockade or deficiency in vitro and in vivo. Immune complex-induced neutrophil adhesion created an enclosed protected space between the cell and its target structure where proteinases and reactive oxygen species can execute their tissue-damaging effect. Because immune complex-induced neutrophil adhesion represents an indispensable step for tissue damage of many diseases, our findings may facilitate the development of strategies for the treatment of such disorders.

The Syk Tyrosine Kinase Is Required for Skin Inflammation in an In Vivo Mouse Model of Epidermolysis Bullosa Acquisita.

The inflammatory form of epidermolysis bullosa acquisita is caused by autoantibodies against type VII collagen (C7), a component of the dermal-epidermal junction. We have previously shown that myeloid Src family kinases mediate skin inflammation triggered by anti-C7 antibodies. Here we identify the Syk tyrosine kinase as a critical component of autoantibody-induced skin inflammation downstream of Src family kinases. Immobilized C7-anti-C7 immune complexes triggered neutrophil activation and Syk phosphorylation in a Src family kinase-dependent manner. Bone marrow chimeric mice lacking Syk in their hematopoietic compartment were completely protected from skin inflammation triggered by anti-C7 antibodies despite normal circulating anti-C7 levels. Syk deficiency abrogated the accumulation of CXCL2, IL-1ß, and leukotriene B4 at the site of inflammation and resulted in defective in vivo neutrophil recruitment. Syk-/- neutrophils had a normal intrinsic migratory capacity but failed to release CXCL2 or leukotriene B4 upon activation by immobilized C7-anti-C7 immune complexes, indicating a role for Syk in the amplification of the inflammation process. These results identify Syk as a critical component of skin inflammation in a mouse model of epidermolysis bullosa acquisita and as a potential therapeutic target in epidermolysis bullosa acquisita and other mechanistically related inflammatory skin diseases such as bullous pemphigoid.

Usefulness of a Simple Immunohistochemical Staining Technique to Differentiate Anti-p200 Pemphigoid From Other Autoimmune Blistering Diseases: A Report of 2 Cases. / Descripción de 2 casos de penfigoide anti-p200. Utilidad de una técnica inmunohistoquímica sencilla en el diagnóstico diferencial con otras enfermedades ampollosas autoinmunes.

Anti-p200 pemphigoid is a rare autoimmune subepidermal blistering disease characterized by the presence of circulating immunoglobulin G antibodies directed against laminin gamma-1, a 200-kDa protein located in the lamina lucida of the basement membrane. We review the clinical, histopathological and immunological characteristics of the first 2 cases described in Spain. Anti-p200 pemphigoid shares histopathological and immunopathological findings with epidermolysis bullosa acquisita, the main entity in the differential diagnosis. However, its management follows the same guidelines as those used for bullous pemphigoid. The diagnosis is confirmed by immunoblotting, which is a complex technique available in few centers. We propose the immunohistochemical detection of collagen type IV on the floor of the blister, combined with standard immunofluorescence techniques, as a simple, accessible alternative to differentiate anti-p200 pemphigoid from epidermolysis bullosa acquisita.

PDE4 Inhibition as Potential Treatment of Epidermolysis Bullosa Acquisita.

Pemphigoid diseases such as epidermolysis bullosa acquisita (EBA) may be difficult to treat. In pemphigoid diseases, mucocutaneous blistering is caused by autoantibodies to hemidesmosomal antigens; in EBA the autoantigen is type VII collagen. Despite growing insights into pemphigoid disease pathogenesis, corticosteroids are still a mainstay of treatment. In experimental EBA, myeloid cell activation is a key event leading to blistering. Activation of these cells depends on phosphodiesterase (PDE) 4. We therefore evaluated the potential for PDE4 inhibition in EBA: PDE4 was highly expressed in inflammatory cells and in the epidermis of patients compared with healthy skin samples. PDE4 inhibitors rolipram, roflumilast, and roflumilast N-oxide prevented the release of immune complex-induced reactive oxygen species from polymorphonuclear leukocytes and separation of the dermal-epidermal junction of skin incubated with antibodies to collagen type VII and polymorphonuclear leukocytes. The PDE4 inhibitors also impaired CD62L shedding and decreased CD11b expression on immune complex-stimulated polymorphonuclear leukocytes. For in vivo validation, experimental EBA was induced in mice by transfer of anti-collagen type VII IgG or immunization with collagen type VII. Roflumilast dose-dependently reduced blistering in antibody transfer-induced EBA and also hindered disease progression in immunization-induced EBA. PDE4 inhibition emerges as a new treatment modality for EBA and possibly other neutrophil-driven pemphigoid diseases.

Myeloid-related proteins-8 and -14 are expressed but dispensable in the pathogenesis of experimental epidermolysis bullosa acquisita and bullous pemphigoid.

BACKGROUND: Myeloid-related protein-8 (MRP-8) and its heterodimeric partner, MRP-14 belong to the group of danger-associated molecular patterns (DAMPs) and are associated with numerous chronic human disorders. However, their functional role in autoimmunity remains largely unclear. OBJECTIVE: Here, we examined the involvement of MRP-8/-14 in two difficult-to-treat autoimmune blistering diseases, epidermolysis bullosa acquisita (EBA) and bullous pemphigoid (BP). METHODS: MRP-8/-14 concentrations in the sera of EBA and BP patients were quantified by ELISA. Experimental EBA and BP in mice were induced by transfer of antibodies directed against type VII or XVII collagen, respectively. Expression of MRP-8/-14 was analyzed in skin samples of these experimental mouse models. The functional role of MRP-8/-14 proteins was evaluated by the induction of experimental EBA and BP in MRP-14-deficient mice. RESULTS: We found serum levels of MRP-8/-14 to be elevated in both, EBA and BP patients. Furthermore, in the lesional skin of mice with experimental diseases expression of MRP-8/-14 was increased as compared to healthy controls. However, MRP-14-deficient mice were fully susceptible to experimental disease with a phenotype comparable to that of wild type controls. CONCLUSION: Although MRP-8/-14 expression is highly increased in experimental as well as human disease, these proteins do not contribute to the pathogenesis in the effector phase of EBA and BP.

[Expression of transient receptor potential lvanilloidreceptor 4 protein in autoimmune bullous skin disorders].

OBJEVTIVE: To investigate the expression of transient receptor potential lvanilloidreceptor 4 (TRPV4) protein in pemphigus vulgaris (PV), bullous pemphigoid (BP), dermatitis herpetiformis (DH), and epidermolysis bullosa acquisita (EBA), and explore the role of TRPV4 in the pathogenesis of these diseases. METHODS: TRPV4 protein in normal skin tissues and lesions of PV, BP, DH, and EBA were detected with immunohistochemistry. RESULTS: The positivity rate of TRPV4 protein expression was 61.90% in PV, 81.81% in BP, 72.22% in DH, and 68.42% in EBA. TRPV4-positive rates in these lesions were significantly lower than the rate in normal skin tissues (93.33%) and also differed significantly among these lesions (PV

The retinoid-related orphan receptor alpha is essential for the end-stage effector phase of experimental epidermolysis bullosa acquisita.

Genetic studies have added to the understanding of complex diseases. Here, we used a combined genetic approach for risk-loci identification in a prototypic, organ-specific, autoimmune disease, namely experimental epidermolysis bullosa acquisita (EBA), in which autoantibodies to type VII collagen (COL7) and neutrophil activation cause mucocutaneous blisters. Anti-COL7 IgG induced moderate blistering in most inbred mouse strains, while some showed severe disease or were completely protected. Using publicly available genotyping data, we identified haplotype blocks that control blistering and confirmed two haplotype blocks in outbred mice. To identify the blistering-associated genes, haplotype blocks encoding genes that are differentially expressed in EBA-affected skin were considered. This procedure identified nine genes, including retinoid-related orphan receptor alpha (RORα), known to be involved in neurological development and function. After anti-COL7 IgG injection, RORα+/- mice showed reduced blistering and homozygous mice were completely resistant to EBA induction. Furthermore, pharmacological RORα inhibition dose-dependently blocked reactive oxygen species (ROS) release from activated neutrophils but did not affect migration or phagocytosis. Thus, forward genomics combined with multiple validation steps identifies RORα to be essential to drive inflammation in experimental EBA.

Autoantibodies to Multiple Epitopes on the Non-Collagenous-1 Domain of Type VII Collagen Induce Blisters.

Epidermolysis bullosa acquisita (EBA) is an autoimmune blistering disease of the skin and mucous membranes, characterized by autoantibodies against type VII collagen (COL7), a major component of anchoring fibrils. Different clinical EBA phenotypes are described, including mechanobullous and inflammatory variants. Most EBA patients' sera react with epitopes located within the non-collagenous 1 (NC1) domain of human COL7. However, it has remained unclear whether antibody binding to these different epitopes is pathogenically relevant. To address this issue, we generated recombinant proteins covering the entire NC1 domain. IgG reactivity with these proteins was analyzed in sera of 69 EBA patients. Most recognized clusters of epitopes throughout the NC1 domain. No correlation was detected between antibody specificity and clinical phenotype. To study the pathogenicity of antibodies specific to different NC1 subdomains, rabbit antibodies were generated. All these antibodies caused dermal-epidermal separation ex vivo. Antibodies against two of these subdomains were injected into mice carrying null mutations of mouse COL7 and the human COL7 transgene and induced subepidermal blisters. We here document that autoantibodies to COL7, independent of the targeted epitopes, induce blisters both ex vivo and in vivo. In addition, using COL7-humanized mice, we provide in vivo evidence of pathogenicity of autoantibodies binding to human COL7.

Effects of intravenous immunoglobulins on mice with experimental epidermolysis bullosa acquisita.

Although well-designed prospective trials are generally lacking, intravenous immunoglobulins (IVIG) seem an effective adjuvant treatment for autoimmune bullous skin diseases. Here, efficacy of IVIG monotherapy was compared with corticosteroid treatment in mice with immunization-induced experimental epidermolysis bullosa acquisita (EBA), an autoimmune bullous skin disease characterized by autoantibodies against type VII collagen. We found that IVIG significantly ameliorated clinical disease severity and skin neutrophil infiltration compared with vehicle-treated mice, whereas methylprednisolone showed comparatively less pronounced effects. Efficacy of IVIG was accompanied by reduced levels of autoantibodies, a shift toward noncomplement-fixing autoantibodies, and lower complement deposition at the dermal-epidermal junction. In addition, peripheral Gr-1-positive cells of IVIG-treated animals showed reduced expression of the activating Fcγ receptor IV, which we recently described as a major mediator of tissue injury in experimental EBA. These data show that treatment with IVIG is superior to systemic corticosteroids in experimental EBA and that the effects of IVIG are pleiotropic involving modulation of both the adaptive and innate immune response, although the detailed mode of action of IVIG in this model remains in need of further elucidation.

Metabolite analysis distinguishes between mice with epidermolysis bullosa acquisita and healthy mice.

BACKGROUND: Epidermolysis bullosa acquisita (EBA) is a rare skin blistering disease with a prevalence of 0.2/ million people. EBA is characterized by autoantibodies against type VII collagen. Type VII collagen builds anchoring fibrils that are essential for the dermal-epidermal junction. The pathogenic relevance of antibodies against type VII collagen subdomains has been demonstrated both in vitro and in vivo. Despite the multitude of clinical and immunological data, no information on metabolic changes exists. METHODS: We used an animal model of EBA to obtain insights into metabolomic changes during EBA. Sera from mice with immunization-induced EBA and control mice were obtained and metabolites were isolated by filtration. Proton nuclear magnetic resonance (NMR) spectra were recorded and analyzed by principal component analysis (PCA), partial least squares discrimination analysis (PLS-DA) and random forest. RESULTS: The metabolic pattern of immunized mice and control mice could be clearly distinguished with PCA and PLS-DA. Metabolites that contribute to the discrimination could be identified via random forest. The observed changes in the metabolic pattern of EBA sera, i.e. increased levels of amino acid, point toward an increased energy demand in EBA. CONCLUSIONS: Knowledge about metabolic changes due to EBA could help in future to assess the disease status during treatment. Confirming the metabolic changes in patients needs probably large cohorts.

Persistent autoantibody-production by intermediates between short-and long-lived plasma cells in inflamed lymph nodes of experimental epidermolysis bullosa acquisita.

Autoantibodies are believed to be maintained by either the continuous generation of short-lived plasma cells in secondary lymphoid tissues or by long-lived plasma cells localized in bone marrow and spleen. Here, we show in a mouse model for the autoimmune blistering skin disease epidermolysis bullosa acquisita (EBA) that chronic autoantibody production can also be maintained in inflamed lymph nodes, by plasma cells exhibiting intermediate lifetimes. After EBA induction by immunization with a mCOL7c-GST-fusion protein, antigen-specific plasma cells and CD4 T cells were analyzed. Plasma cells were maintained for months in stable numbers in the draining lymph nodes, but not in spleen and bone marrow. In contrast, localization of mCOL7c-GST -specific CD4 T cells was not restricted to lymph nodes, indicating that availability of T cell help does not limit plasma cell localization to this site. BrdU-incorporation studies indicated that pathogenic mCOL7c- and non-pathogenic GST-specific plasma cells resemble intermediates between short-and long-lived plasma cells with half-lives of about 7 weeks. Immunization with mCOL7c-GST also yielded considerable numbers of plasma cells neither specific for mCOL7c- nor GST. These bystander-activated plasma cells exhibited much shorter half-lives and higher population turnover, suggesting that plasma cell lifetimes were only partly determined by the lymph node environment but also by the mode of activation. These results indicate that inflamed lymph nodes can harbor pathogenic plasma cells exhibiting distinct properties and hence may resemble a so far neglected site for chronic autoantibody production.

Overexpression of the Flii gene increases dermal-epidermal blistering in an autoimmune ColVII mouse model of epidermolysis bullosa acquisita.

Epidermolysis bullosa (EB) is a severe genetic skin fragility syndrome characterized by blister formation. The molecular basis of EB is still largely unknown and wound healing in patients suffering from EB remains a major challenge to their survival. Our previous studies have identified the actin remodelling protein Flightless I (Flii) as an important mediator of wound repair. Here we identify Flii as a novel target involved in skin blistering. Flii expression was significantly elevated in 30 patients with EB, most prominently in patients with recessive dystrophic EB (RDEB) who have defects in production of type VII collagen (ColVII). Using an autoimmune ColVII murine model of EB acquisita (EBA) and an immunocompetent-ColVII-hypomorphic genetic mouse model of RDEB together with murine Flii alleles, we investigated the contribution of Flii to EB. Overexpression of Flii produced severe blistering post-induction of EBA, while decreased Flii reduced blister severity, elevated integrin expression, and improved ColVII production. Flii(+/-) blistered skin showed reduced α-SMA, TGF-ß1, and Smad 2/3 expression, suggesting that decreasing Flii may affect fibrosis. In support of this, Flii-deficient fibroblasts from EBA mice were less able to contract collagen gels in vitro; however, addition of TGF-ß1 restored collagen contraction, suggesting an interplay between Flii and TGF-ß1. Elevated Flii gene and protein expression was further observed in the blisters of ColVII hypomorphic mice, a murine model of RDEB, suggesting that reducing Flii in blistered skin could be a potential new approach for treating patients with EB.