Enhanced biosynthesis of human skin collagenase in fibroblast cultures from recessive dystrophic epidermolysis bullosa

Dystrophic Epidermolysis Bullosa: Secondary Disease Mechanisms and Disease Modifiers

The phenotypic presentation of monogenetic diseases is determined not only by the nature of the causative mutations but also is influenced by manifold cellular, microenvironmental, and external factors. Here, heritable extracellular matrix diseases, including dystrophic epidermolysis bullosa (DEB), are no exceptions. Dystrophic epidermolysis bullosa is caused by mutations in the COL7A1 gene encoding collagen VII. Deficiency of collagen VII leads to skin and mucosal fragility, which progresses from skin blistering to severe fibrosis and cancer. Clinical and pre-clinical studies suggest that targeting of secondary disease mechanisms or employment of natural disease modifiers can alleviate DEB severity and progression. However, since many of these mechanisms are needed for tissue homeostasis, informed, selective targeting is essential for safe and efficacious treatment. Here, we discuss a selection of key disease modifiers and modifying processes active in DEB, summarize the still scattered knowledge of them, and reflect on ways forward toward their utilization for symptom-relief or enhancement of curative therapies.

Nonhealing Wounds—A Therapeutic Dilemma

Chronic wounds of the lower extremity are a therapeutic dilemma. In India, chronic wounds are caused by factors other than impaired circulation and diabetes, which account for most of this clinical problem in Western societies. A study of 2 topical agents, placental extract and phenytoin powder, is presented in this paper. One hundred fifty patients were randomly assigned to these treatments or to saline dressings (control). It was observed that patients receiving active topical treatments responded better than those in the control group. The importance of this finding should be viewed with the perspective that these topical treatments are inexpensive and easily available in India. The study also piloted measurements of angiogenic responses in 1 group, and the findings encourage further exploration with the technique and topical agent.

Expression of collagenase and stromelysin in skin fibroblasts from recessive dystrophic epidermolysis bullosa

Collagenase and stromelysin expression in recessive dystrophic epidermolysis bullosa (RDEB) was studied at both the protein and the gene expression levels in fibroblast cultures. The amount of enzyme protein in the culture medium, as determined using a specific enzyme assay, showed a 9.7-fold increase in collagenase and a 2.7-fold increase in stromelysin in RDEB fibroblasts (n = 4 patients) compared with controls (n = 3 subjects with normal skin). Collagenase activity was extremely high in all RDEB fibroblasts. Gene expression, as assessed by Northern blot hybridization, was increased in two sets of RDEB fibroblasts with respect to collagenase, and in two other sets of RDEB fibroblasts with respect to stromelysin. The effect of interleukin-1 alpha (IL-1 alpha) on metalloproteinase expression was also examined. The results revealed that: 1) collagenase and stromelysin expression was variably increased at both the protein and the gene expression levels in RDEB fibroblasts; (2) the gene expression level did not always reflect the corresponding protein level; and (3) IL-1 alpha produced a differential effect on collagenase and stromelysin expression. Although the causative gene for RDEB is a type VII collagen, the abnormal expression of collagenase and/or stromelysin is still important in considering the pathophysiology of RDEB.

Gene expression of collagenase and stromelysin in skin fibroblasts derived from dystrophic epidermolysis bullosa

We studied expression of collagenase gene and stromelysin gene in skin fibroblasts derived from patients with recessive dystrophic epidermolysis bullosa (RDEB) and dominant dystrophic epidermolysis bullosa (DDEB). Northern blot analyses revealed that collagenase gene expression was markedly increased in two of four RDEB cells, as compared with three normal control cells. Moreover, stromelysin gene expression was also markedly increased in two RDEB cells, as compared with normal controls. In contrast, collagenase and stromelysin gene expression levels in three DDEB cells did not show any significant difference from those of normal controls, except one cell line which showed mild increase of both collagenase and stromelysin mRNA. Quantitative estimates of collagenase mRNA (U/micrograms RNA) determined by slot blot hybridizations showed that those of RDEBs: 0.92-1.81 (mean 1.3 +/- 0.45); DDEBs: 0.18-0.73 (mean 0.60 +/- 0.37); normal controls: 0.26-0.93 (mean 0.64 +/- 0.34). Stromelysin mRNA levels showed that those of RDEBs: 1.75-6.62 (mean 4.06 +/- 2.00); DDEBs: 0.55-3.78 (mean 1.69 +/- 1.81); normal controls: 1.27-2.08 (mean; 1.55 +/- 0.45). These data demonstrated that collagenase and stromelysin gene expression was increased in some, but not all, RDEB cell lines. Our data suggested that collagenase and/or stromelysin could play a certain role for blister formation in RDEB, coordinately or in a distinct manner.

Head and neck manifestations of epidermolysis bullosa

Although considerable attention has focused on the pathophysiology and external dermatologic consequences of epidermolysis bullosa (EB), head and neck mucosal manifestations pose specific management problems. The otolaryngologic aspects of EB, with emphasis on involvement and treatment of the ears, oral cavity and teeth, larynx and trachea, and pharynx and esophagus, are reviewed. Guidelines are presented for specialized dental, anesthetic, and nutritional management in patients with this potentially fatal disease.

Exclusion of linkage between the collagenase gene and generalized recessive dystrophic epidermolysis bullosa phenotype

Generalized recessive dystrophic epidermolysis bullosa (RDEB) is a severe inherited autosomal disease characterized by dermolytic blister formation. Enhanced collagenase and/or abnormal collagenase have been reported in skin from affected patients, suggesting that collagenase could be responsible for the absence of anchoring fibrils in this disorder. We used a genetic linkage approach to test the hypothesis that this disease is due to a defect in the collagenase gene in nine affected families. Analysis of amplified genomic DNA fragments of the collagenase gene by means of denaturing gradient gel electrophoresis (DGGE) allowed us to detect intragenic polymorphisms, which were subsequently characterized by direct genomic sequencing. Segregation analysis of these polymorphic sites showed exclusion of linkage between the collagenase gene and generalized RDEB phenotype in a family with consanguineous parents and three affected children. However, the possibility of linkage with the collagenase gene in the other eight families tested could not be excluded. The genetic markers described here provide a tool for investigating genetic linkage in other affected families. Overall, our results show that generalized RDEB can be caused by a defect in a gene other than the collagenase gene, and support the hypothesis that the genetic defect lies in abnormal anchoring fibril formation.

Revised clinical and laboratory criteria for subtypes of inherited epidermolysis bullosa. A consensus report by the Subcommittee on Diagnosis and Classification of the National Epidermolysis Bullosa Registry

Inherited epidermolysis bullosa encompasses a number of diseases, with the common finding of blister formation after minor mechanical trauma to the skin. In some forms significant, if not eventually fatal, extracutaneous disease activity may occur. In recent years application of newer technologies has contributed substantially to an overall understanding of this collection of inherited diseases. Concurrently, many new phenotypes have been recognized, in part the result of ongoing prospective patient registries in the United States and abroad. Unfortunately, this has resulted in a massive literature that may appear to be confounded by seemingly excessive or arbitrary subdivision of epidermolysis bullosa variants. With these concerns in mind a subcommittee was established by the National Epidermolysis Bullosa Registry to summarize the current literature and to make recommendations as to the best clinical and laboratory criteria for the practical diagnosis and subclassification of patients with inherited epidermolysis bullosa.

Collagen degradation in ischaemic rat hearts

Myocardial extracellular matrix is organized into a complex arrangement of intercellular and pericellular fibres and fibrils that serves as a supporting framework for contracting cells. Recent evidence suggests that changes in ventricular shape and function occurring after ischaemic injury may be related to alterations of this matrix. In this report we describe the rapid and extensive loss of collagen in myocardial infarction produced by ligating the left anterior descending coronary artery of the rat for 1-3 h. The total collagen content in the myocardial infarct zones after 1, 2 and 3 h of ligation was 75 +/- 8%, 65 +/- 7% and 50 +/- 10% respectively (mean +/- S.D.) of that of either the non-infarcted tissue controls or of the same regions in sex- and age-matched normal left ventricles. A marked decrease also occurred in the residual collagens which were not extractable with 6 M-guanidine hydrochloride, suggesting that rapid degradation of insoluble collagen fibres may also occur. The decreased collagen content in the 3 h myocardial infarct coincided with the appearance of several enzyme activities. Collagenase, other neutral proteinase and presumed lysosomal serine proteinase activities were increased by 3, 3 and 2 times the control values respectively. These results suggest that the increased activities of collagenase and other neutral proteinases may be responsible for the rapid degradation of extracellular matrix collagen in myocardial infarct.

Autoantibodies to extracellular collagen matrix components in epidermolysis bullosa and other bullous diseases

In order to determine whether autoantibodies are present in sera from normal individuals and/or patients with selected bullous disorders, a highly sensitive solid-phase radioimmune assay was established using purified native collagen types I-VI, laminin, and fibronectin as substrates. Sixty-four sera were utilized, representing 12 normal controls as well as 4 patients with extensive thermal burns, 18 with autoimmune bullous diseases (11 bullous pemphigoid, 5 pemphigus vulgaris, and 2 epidermolysis bullosa acquisita), and 30 with non-autoimmune mechanobullous diseases [epidermolysis bullosa (EB): 20 simplex, 4 junctional, and 6 dystrophic]. In general, autoantibodies to types I, II and VI collagen and fibronectin were undetectable in any of the patient or control groups. In contrast, autoantibodies to types III and V collagen were noted in 87.5% (28/32) and 90.6% (29/32) of EB sera, respectively, while being only rarely noted in sera from other patient groups. Similarly, autoantibodies to type IV collagen and laminin were detected in 50% (16/32) and 40.6% (13/32) of EB sera, especially from patients with simplex and dystrophic forms of the disease. These data suggest that selected interstitial and basement membrane-associated collagens and laminin may become autoimmunogenic in all three forms of inherited EB in contrast to their relative lack of immunogenicity in at least some of the other intraepidermal and subepidermal blistering disorders. The role, if any, of these autoantibodies in the induction or perpetuation of blistering in EB awaits further studies.

Abnormalities of plasma and erythrocyte essential fatty acid composition in epidermolysis bullosa: influence of treatment with diphenylhydantoin

The fatty acid composition of plasma and erythrocyte phospholipids was determined in children with various subtypes of epidermolysis bullosa (EB) and in their parents. Patients with recessive dystrophic, dominant dystrophic, simplex, or junctional forms of EB had a higher percentage composition of arachidonic acid in plasma and/or erythrocyte phospholipids compared to age-matched controls. Epidermolysis bullosa patients treated with diphenylhydantoin had lower levels of arachidonic acid in plasma and erythrocyte phospholipids than did untreated EB patients. Parents of children with the recessive dystrophic or junctional EB subtypes had higher linoleic and arachidonic acids in plasma and erythrocyte phospholipids than did controls. Plasma and erythrocyte total lipids were within the normal range in children with EB. Plasma zinc was also normal but plasma copper was elevated in children with recessive dystrophic EB. We conclude that higher arachidonic acid in plasma and erythrocytes may be related to the pathology of EB.

Induction and suppression of type I collagenase in cultured human cells

A number of peptide growth factors have been shown to induce the secretion of type I collagenase into the medium of human fibroblast cultures (Chua et al., 1985). In this study the ability of eye-derived growth factor, lectin and tumor-promoting agents on collagenase induction in human fibroblast cells were examined. These agents were found to be able to induce collagenase production to a similar extent as epidermal growth factor. Dexamethasone at 10-100 nM was found to suppress collagenase induction in human fibroblast cells. The cell-type specificity of this enzyme induction by growth factors was studied by using a human epidermoid carcinoma cell line, A-431. An Mr 55,000 band appeared in the medium of A-431 cells upon 22 h exposure to EGF. Two-dimensional peptide pattern of the Mr 55,000 band in A-431 cells was identical to the counterpart in HF cells. Our results indicated that the induction of collagenase was not unique to human fibroblast cultures.

Behavior of epidermolysis bullosa fibroblasts in a hydrated collagen lattice

To determine if an altered ability to contract a hydrated collagen lattice is characteristic of fibroblasts from patients with recessive dystrophic epidermolysis bullosa (RDEB), we examined contraction by fibroblasts from normal subjects and patients with RDEB, dominant dystrophic epidermolysis bullosa (DDEB), and dominant epidermolysis bullosa simplex (DEBS). An extremely broad range of contractility (normal, poor, and hypercontraction) was observed in all types of epidermolysis bullosa (EB). When contraction in control fibroblasts was defined as the mean +/- 2 SD, (all control values were within this range) and the data were analyzed by the chi-square test, only 32% of EB cells fell within this range, with 47% poorly contractile and 21% hypercontractile. These data, derived from 34 patients, indicate that no single genetic defect resulting in altered contractility in the 3 distinct types of EB is likely. Neither cell viability, collagenase expression, nor PGE2 synthesis as correlated with gel contraction in any group. Indomethacin had no effect on contraction in RDEB. It is possible that the genetic defects in EB cause blister formation in vivo and may lead in some way to an abnormal interaction of fibroblasts with the extracellular matrix resulting in an altered collagen lattice contraction in vitro.

Antenatal diagnosis of recessive dystrophic epidermolysis bullosa: collagenase expression in cultured fibroblasts as a biochemical marker

We performed fetoscopy and skin biopsy on a 19-week fetus at risk for recessive dystrophic epidermolysis bullosa (RDEB). Ultrastructural analysis of the tissue revealed dermolytic blister formation in the skin characteristic of the disease. To develop a biochemical test for use in antenatal diagnosis of RDEB, we established skin fibroblast cultures from the 20-week aborted fetus. The collagenase production by fetal RDEB fibroblast cultures was greater than seen in normal fetal fibroblast cultures. The concentration in culture medium from fetal RDEB cultures was 5.42 +/- 0.74 micrograms/ml (mean +/- SE) compared with 2.24 +/- 1.11 micrograms/ml in normal adult control cultures and 2.05 +/- 0.61 micrograms/ml in cultures from patients with other genetic forms of epidermolysis bullosa (p less than 0.025). In contrast, the concentration of collagenase in the fetal RDEB culture medium was not different from that seen in cell cultures from known patients with RDEB (5.34 +/- 1.12 micrograms/ml). Collagenase activity of the fetal RDEB medium was also increased approximately 3.5-fold. These data indicate that enhanced expression of collagenase by fetal RDEB skin fibroblasts can serve as a biochemical adjunct, and possibly an alternative, to morphologic examination of tissue for antenatal diagnosis.

ATP-induced cell contraction with epidermolysis bullosa dystrophica recessive and normal dermal fibroblasts

Human dermal fibroblasts cultured on glass coverslips and permeabilized by glycerol can be induced to undergo cell shrinkage by the addition of ATP in buffer containing calcium and magnesium. They reduce in size by 72% in 10 min. ATP-induced cell contraction is linked to an aggregation of cytoplasmic filaments as demonstrated by rhodamine-phalloidin F-actin staining. Before the addition of ATP, glycerinated cells have parallel arrangements of staining cytoplasmic filaments. Afterward, dermal fibroblasts from patients with epidermolysis bullosa dystrophica recessive (EBdr) show only a 10-20% reduction in cell size, and little F-actin aggregation staining can be demonstrated. Epidermolysis bullosa dystrophica recessive fibroblasts have been reported to produce excess prostaglandin E2 (PGE2) and cAMP. The preincubation of normal dermal fibroblasts for 24-30 h with 10 micrograms/ml PGE2, 10 micrograms/ml cholera toxin, or 1 mM dibutyl cAMP will reduce ATP-induced cell contraction to less than 20%. Treated cells showed little disruption of cytoplasmic F-actin. Epidermolysis bullosa dystrophica recessive fibroblasts preincubated with the cyclooxygenase inhibitor indomethacin at 10 micrograms/ml restored cell contraction to 74%. These treated cells also show aggregation of F-actin filaments. The process of ATP-induced cell contraction can be altered by the intracellular concentrations of cAMP, the levels of which are elevated in the fibroblasts in EBdr patients. A mechanism for cAMP inhibition of cell contraction is discussed.

Age-related changes in collagenase expression in cultured embryonic and fetal human skin fibroblasts

Since skin collagenase is required for initiation of the degradation of types I and III collagens, the major collagens of the human dermis, we examined its expression during embryonic and fetal development. When using skin fibroblasts cultured from human embryos and fetuses, immunoreactive collagenase concentrations were strongly correlated with estimated gestational age (p less than 0.001), with levels at 7-8 weeks of gestation that were about one-twentieth of those in the 29-week cell cultures. In crude culture medium, the apparent catalytic efficiency (activity per unit immunoreactive protein) was variable, an observation attributable in part to variable expression of a collagenase-inhibitory protein. Following chromatographic purification, four of ten fetal collagenases were found to have greater than or equal to 4-fold decrease in specific activity, suggesting that these particular fetal collagenases may be structurally and/or catalytically altered. Since the decreased levels of immunoreactive protein suggested that decreased enzyme synthesis was the major mechanism, we examined collagenase synthesis in a cell-free translation system. Here, we quantitated collagenase expression in the culture medium of intact cells prior to harvesting mRNA. Compared with the intact adult cells, the fetal cells had 3-17 times less collagenase activity in the medium, while in cell-free translation there was a 2- to 3-fold decrease in collagenase synthesis. These data suggest that decreased in vitro expression is correlated with decreased levels of translatable collagenase mRNA but that other factors, such as the collagenase inhibitor and altered specific activity of the enzyme, may be important in modulating collagenase activity.

Origin and properties of the blister formation factor in blister fluids from recessive dystrophic epidermolysis bullosa

The origin and properties of the blister formation factor in recessive dystrophic epidermolysis bullosa (RDEB) blister fluids were investigated. Organ cultures of normal human skin incubated with RDEB dermis extract or with RDEB fibroblast culture medium (FCM) produced a clear subepidermal blister with histology similar to that of a RDEB blister in vivo. The injection of RDEB dermis extract into guinea-pig skin also induced dermal-epidermal separation with similar histology to the skin lesions of RDEB patients. The blister forming activity of RDEB FCM which induces the subepidermal blister was inactivated by heat (60 degrees C for 30 min), trypsin digestion and by treating with EDTA, EGTA, alpha 2-macroglobulin, diisopropyl fluorophosphate and N-ethylmaleimide, but was not affected by dialysis. These results suggest that the RDEB fibroblast produces a blister formation factor(s), and that blister formation may be caused by a combination of a metallo-protease, serine protease and SH protease.

Hereditary epidermolysis bullosa

Hereditary epidermolysis bullosa (EB) is a group of disorders of skin characterized by formation of blisters following minor trauma. There are at least sixteen types of hereditary EB. These types are reviewed in this article. There are several classifications of hereditary EB, and they are discussed, as well as current ideas on pathogenesis. Last, the treatment of this often recalcitrant group of diseases is discussed.

Glucocorticoid modulation of collagenase expression in human skin fibroblast cultures. Evidence for pre-translational inhibition

Glucocorticoids inhibit collagenase accumulation in the medium of human skin explant cultures. To examine the mechanism for this process, skin fibroblasts were placed in serum-free medium containing various steroids. Dexamethasone produced a dose-dependent inhibition of trypsin-activatable collagenase in the culture medium with maximal inhibition of approx. 85% at 10(-6) M. Dexamethasone failed to inhibit collagenase activity directly. The decrease in activity in the medium was paralleled by a decrease in immunoreactive protein, suggesting inhibition of enzyme synthesis. The specificity of the effect was shown in two ways. At 10(-6) M steroid, only dexamethasone and hydrocortisone were inhibitory; estradiol, progesterone and testosterone produced less than 10% inhibition. In biosynthetic studies, exposure to 10(-7) M dexamethasone for 24 h produced approx. 50% inhibition of collagenase synthesis but caused no greater than 10% inhibition of total protein synthesis. The T1/2 for achieving the effect was approx. 16 h after initial exposure to dexamethasone. These kinetics were parallel to the inhibition caused by actinomycin D and cordycepin, two inhibitors of transcription, but were longer than that caused by cycloheximide (T 1/2 less than 3 h). To examine this process, cells were cultured in the presence or absence of 10(-6) M dexamethasone prior to harvesting mRNA for cell-free translation. In each case the inhibition or enzyme activity in the intact cells was paralleled by a reduction in translatable collagenase mRNA from the same cells. At the same time, there was no significant inhibition of total protein translation by the steroid. These data suggest that glucocorticoids regulate collagenase synthesis at a pre-translational level, possibly through inhibition of transcription.

Evaluation of anchoring fibrils and other components of the dermal-epidermal junction in dystrophic epidermolysis bullosa by a quantitative ultrastructural technique

To examine the possibility that differences in the structure and population density of anchoring fibrils (AF) and other components of the dermal-epidermal junction might distinguish between genetically and clinically distinct varieties of dystrophic epidermolysis bullosa (DEB), a controlled ultrastructural morphometric study of nonseparated keratinocyte-associated dermal-epidermal junction was undertaken in a total of 17 patients with DEB. Seven patients had dominant DEB, 3 had localized recessive DEB, and 7 had severe, generalized recessive DEB. Nonlesional, unscarred skin was obtained from standard body regions. Criteria for the identification of AF were a mandatory union with the lamina densa and the presence of central banding and/or fanning of the extremities. No AF were detected in 9 technically suitable samples from patients with severe recessive DEB. Structurally normal AF were present, but significantly reduced in number, in both dominant and localized recessive DEB, compared with site-matched samples from 12 healthy adults. There was no difference in AF characteristics between dominant and localized recessive DEB, or between sites of predilection and nonpredilection for blisters. The presence or absence of albopapuloid lesions in dominant DEB did not influence AF counts. There was no difference in numbers of hemidesmosomes, basal cell plasmalemmal vesicles, or dermal microfibril bundles in any group of DEB patients compared with controls. Thus, although severe mutilating DEB can be distinguished by routine transmission electron microscopy, the dominant and localized recessive forms cannot be differentiated on the basis of AF structure or numbers.

Serine proteinase activation of latent human skin collagenase

Latent and active collagenase were demonstrated following direct extraction from normal skin homogenates with 0.1M calcium chloride at 60 degrees C. 83% of the collagenase activity was in latent form and could be maximally activated with trypsin. Partial activation of the latent enzyme could also be demonstrated by incubation of the skin extract without added trypsin. This endogenous activation was inhibited by the addition of soya bean trypsin inhibitor, trasylol, di-isopropylphosphofluoridate and phenylmethanesulphonylfluoride, none of which inhibited collagenase directly. This suggests that the skin extracts contain a collagenase activating enzyme with the inhibition profile of a serine proteinase. A chymotryptic proteinase with a similar inhibition profile was extracted from normal human skin and partially purified. This enzyme activated fibroblast procollagenase derived from tissue culture of normal skin. The procollagenase was also partially activated by plasmin and chymotrypsin. This is the first demonstration of a collagenase activating enzyme in human skin and raises the possibility that collagenase activation by this mechanism may be responsible for collagen degradation in some disease processes.

Epidermolysis bullosa dystrophica recessive fibroblasts produce increased concentrations of cAMP within a collagen matrix

Human dermal fibroblasts grown in tissue culture can be suspended and cultured in collagen lattices. These fibroblast-populated collagen lattices (FPCL) undergo a reduction in size by the process of lattice contraction. Fibroblasts from patients with epidermolysis bullosa dystrophica recessive, EBdr, produce excessive quantities of cAMP. These high concentrations of cAMP may be related to the inability of the EBdr fibroblast to elongate and spread out when incorporated into the collagen matrix. Fibroblasts with these morphologic characteristics are not effective in contracting collagen lattices. EBdr fibroblasts in FPCL have intracellular concentrations of cAMP 8 times greater than those of normal fibroblasts in FPCL. They also have a dendritic morphology. The addition of cholera toxin or dibutyryl cAMP to normal human fibroblasts will cause elevated levels of intracellular cAMP and will inhibit the elongation and spreading of cells and lattice contraction. The cytoskeletal morphology of EBdr fibroblasts differs from that of normal human fibroblasts in FPCL. The use of rhodamine phalloidin, a specific fluorescent stain for F-actin filaments, reveals that EBdr fibroblasts show a pattern of actin distribution shared by normal fibroblasts cultured in the presence of dibutyryl cAMP or cholera toxin. It is proposed that the contractile forces responsible for lattice contraction are identical to those forces responsible for the spreading and elongation of cells. EBdr fibroblasts fail to spread and elongate within a collagen matrix and are therefore not effective in lattice contraction.

Production of blister in normal human skin in vitro by blister fluids from epidermolysis bullosa

Pathogenic mechanisms involved in the blister formation of epidermolysis bullosa (EB) are not clearly understood at present. In this paper, we attempted to produce experimental blistering in vitro similar to the histologic picture of EB simplex (EBS) and recessive dystrophic EB (RDEB). It was demonstrated by light and electron microscopy that the medium containing fresh blister fluids from the patients with EBS or RDEB could produce similar histologic features in normal human skin (in vitro) to those of the skin lesions of patients (in vivo). This observation may open new avenues of approach to studying these diseases.

Collagen metabolism in two rare forms of epidermolysis bullosa

The collagenase activity in skin fibroblast cultures from three patients with rare forms of epidermolysis bullosa was assayed before and after proteolytic activation of the medium. Two of the patients had the recessive dystrophic form of the disease (REBD), which is generally associated with abnormal collagenase activity. The other patient had an atrophic mitis form of the disease (REBA), which has not previously been associated with defective collagen metabolism. However, a similar increase in collagenase activity was found in all three cases. The total collagen production of EB fibroblasts was also enhanced, being two to five times that of control cell lines, and the intracellular hydroxylases of collagen biosynthesis were higher in the case of two EB-cell lines. These changes reflect the compensatory increase in collagen synthesis which follows the increased degradation caused by excessive free collagenase activity. Diphenylhydantoin treatment of one REBD patient for 9 months improved her condition.

Effects of increased concentrations of prostaglandin E levels with epidermolysis bullosa dystrophica recessive fibroblasts within a populated collagen lattice

Tissue-cultured fibroblasts suspended in a collagen matrix actively reduce the size of that matrix by the process called lattice contraction. Cultured human fibroblasts derived from patients with epidermolysis bullosa dystrophica recessive (EBdr) cannot elongate and spread out when incorporated in a collagen matrix and they are therefore poor at contracting that collagen lattice. Culture medium from EBdr fibroblast-populated collagen lattice (FPCL) shows an increased concentration of prostaglandin, PGE2, compared with that in lattices made with equal numbers of normal human fibroblasts. The addition of the nonsteroid anti-inflammatory drug, indomethacin, to EBdr FPCL inhibits PGE synthesis, and promotes both cell elongation and spreading, as well as lattice contraction. However, the addition of indomethacin to normal FPCL does not stimulate either the spreading and elongation of cells or lattice contraction. PGE1 or PGE2 added to normal FPCL inhibits lattice contraction and cell elongation and spreading. Accordingly, EBdr FPCL does not undergo contraction due to altered elongation and spreading of fibroblasts, which process is related to enhanced PGE synthesis. It is proposed then that the contractile forces responsible for lattice contraction are identical to those responsible for the spreading and elongation of cells. Characteristic of EBdr fibroblasts are elevated levels of PGE2 which result in the failure of cells to spread and elongate within a collagen matrix. PGE2-treated normal cells do not readily spread and elongate and they do not readily contract FPCL.

Generalized dominant epidermolysis bullosa simplex: decreased activity of a gelatinolytic protease in cultured fibroblasts as a phenotypic marker

To characterize biochemical traits associated with various forms of epidermolysis bullosa (EB), we used skin fibroblast cultures to measure a gelatin-specific neutral metalloprotease. Compared to normal cultures, levels of this gelatinase were 7-fold decreased in cell cultures from 3 patients from 3 kindreds with generalized dominant EB simplex of the Koebner type (DEBS-K) (p less than 0.001). The specificity of this trait was shown in several ways. The growth kinetics and total protein synthesis of the cells were unaltered. The activity of lactic dehydrogenase, a cytoplasmic enzyme, was also unaltered, indicating the integrity of the cells was not compromised. The decrease in gelatinase activity is specific for generalized DEBS-K, since cultures from recessive dystrophic EB, recessive junctional EB, dominant dystrophic EB, and a second genetic type of DEBS all fail to show this defect. However, since it has been suggested that DEBS-K and the localized form of DEBS, the Weber-Cockayne type (DEBS-WC), may represent allelic mutations of varying severity, we measured gelatinase activity in cell cultures of 13 patients of this type. The levels displayed a biphasic segregation in which 7 of 13 values were equal to, or greater than, the mean activity of control cells. Cultures from the remaining 6 patients were greater than 1 SD below the mean control value and approximated those seen in the generalized DEBS-K patients. These studies suggest that the decrease in gelatinolytic activity is a marker for DEBS-K and that DEBS-K and DEBS-WC may be closely related genetic disorders in which the defect in gelatinolytic protease represents a pleiotropic effect of the gene for DEBS or is genetically linked to the DEBS gene.

Monoclonal antibodies to anchoring fibrils for the diagnosis of epidermolysis bullosa

Murine monoclonal antibodies to human anchoring fibrils reacted with human and monkey cervix, tongue, esophagus, and vagina. Rat, mouse, and guinea pig tissues were negative. In 11 patients with dystrophic recessive epidermolysis bullosa there was no reaction by immunofluorescence and immunoelectron microscopy. Other forms of epidermolysis bullosa had normal reactivity.

Retinoic acid inhibition of collagenase and gelatinase expression in human skin fibroblast cultures. Evidence for a dual mechanism

Human skin fibroblast cultures have been employed to study the effects of a variety of vitamin A analogues (retinoids) on the expression of two enzymes involved in collagen degradation in the skin, collagenase and a gelatinolytic protease. In normal and recessive dystrophic epidermolysis bullosa fibroblast cultures, retinoic acid compounds were effective inhibitors of the accumulation of both enzymes in the culture medium with half-maximal inhibitions occurring at 0.25-1 microM for collagenase and at 3-6 microM for the gelatinolytic protease. Various retinoids exhibited differing degrees of inhibitory actions, so that at a 1 microM concentration, relative inhibitions were: 13-cis-retinoic acid greater than all-trans-retinoic acid greater than aromatic retinoid (Ro 10-9359) much greater than retinol. The retinoic acid-mediated decrease in collagenase activity was accompanied by a parallel decrease in immunoreactive collagenase protein, suggesting that the retinoic acids were acting to inhibit synthesis of the enzyme. However, an additional effect of these agents was encountered. Although the retinoids themselves had no direct collagenase inhibitory action, medium derived from cultures maintained in these retinoids showed direct inhibitory capacity which was dependent both on the concentration of retinoic acid and on the length of time in culture. The results suggest that the retinoic acids modulate collagenase in vitro by two mechanisms: by decreasing the synthesis of enzyme protein and by modulating the expression of an inhibitory molecule.

Human skin collagenase: assignment of the structural gene to chromosome 11 in both normal and recessive dystrophic epidermolysis bullosa cells using human-mouse somatic cell hybrids

Somatic cell hybrids between mouse cells and human normal skin and corneal fibroblasts and recessive dystrophic epidermolysis bullosa (RDEB) skin fibroblasts have been used to assign the structural gene for collagenase to its human chromosome. A total of 46 hybrid subclones from several hybridization events were isolated in hypoxanthine-aminopterin thymidine (HAT) selection medium and used to measure the production of human collagenase by a specific radioimmunoassay. We have found that both the normal and RDEB human collagenase gene maps to human chromosome 11. This indicates that the abnormal collagenase produced by RDEB cells is probably not a totally distinct form of the enzyme, but is a structural mutation of the normal collagenase enzyme.

Epidermolysis bullosa dystrophica recessive fibroblasts altered behavior within a collagen matrix

Normal human fibroblasts incorporated into a collagen lattice reduce the size of that lattice over a period of time. Lattice size reduction or lattice contraction is directly related to initial cell number. When equal numbers of fibroblasts derived from patients with epidermolysis bullosa dystrophica recessive, (EBdr), are used, there is delayed lattice contraction. The EBdr fibroblasts have an altered cellular shape, when compared to normal cells, in that the EBdr cells fail to flatten out and elongate, but do attach to collagen fibers like normal fibroblasts. EBdr fibroblasts maintain a rounded shape with numerous filopodia radiating from the cell periphery and such filopodia are attached to the collagen fibers of the lattice. In monolayer tissue culture on glass surfaces, EBdr fibroblasts are three times more likely to grow over neighboring fibroblasts. EBdr cell filopodia structures are attached to the cell surfaces lying beneath them, which demonstrates another condition of altered anchorage attachment of EBdr fibroblasts.

Colchicine-induced modulation of collagenase in human skin fibroblast cultures. I. Stimulation of enzyme synthesis in normal cells

Microtubule-active agents affect the secretion of a variety of proteins, including collagenase. To gain insight into the mechanisms involved in this process, we examined the effects of colchicine on the synthesis, secretion, and activity of human skin collagenase. When added to monolayer cultures of human skin fibroblasts, 10(-6) M colchicine produced a mean 3-fold increase in trypsin-activatable collagenase in the culture medium. Stimulation was not observed with lumicolchicine. The enhanced accumulation of collagenase was dose-dependent with 10(-9), 10(-8), 10(-7), and 10(-6) M colchicine giving collagenase activities/mg protein that were 100 +/- 6%, 165 +/- 20%, 186 +/- 34%, and 297 +/- 62% of control, respectively. Although the effect on collagenase was seen under conditions independent of cellular growth (i.e., in serum-free medium), maximum stimulation occurred in subconfluent cultures. The colchicine-induced increase in activity was paralleled by an increase in immunoreactive enzyme protein, suggesting stimulation of enzyme synthesis. The catalytic efficiency of the enzyme (activity per unit immunoreactive protein) was unchanged, however, indicating that a structurally normal enzyme was being synthesized. To examine the process in more detail, the biosynthesis of 3H-labeled collagenase was quantitated in these cultures by specific immunoprecipitation. Although 10(-6) M colchicine produced no increase in total protein synthesis, an increased rate of collagenase synthesis was seen after only 1.5 hr. These data suggest that colchicine has a specific effect on the synthesis of collagenase and may be a useful probe for studying its regulation.

Colchicine-induced modulation of collagenase in human skin fibroblast cultures. II. A probe for defective regulation in epidermolysis bullosa

The addition of colchicine to cultures of normal human skin fibroblasts produces a significant stimulation of collagenase. Because this finding implies a role for the microtubule system in the regulation of normal collagenase synthesis, we have used colchicine as a probe for aberrations in this enzyme in epidermolysis bullosa. In fibroblast cultures from the dominant simplex, dominant dystrophic, and recessive letalis forms of epidermolysis bullosa, 10(-6) M colchicine produced approximately a 2-fold increase in collagenase in the culture medium, a finding shown by biosynthetic studies to be attributable to enhanced synthesis of enzyme protein. In the case of typical recessive dystrophic epidermolysis bullosa, a disease characterized by excessive collagenase synthesis, the fibroblasts could also be stimulated to produce additional collagenase, despite having elevated baseline synthetic rates. In contrast, fibroblasts isolated from one recessive epidermolysis bullosa patient were resistant to the stimulatory effects of colchicine in concentrations up to 5 x 10(-6) M. In the absence of colchicine, collagenase synthesis in this patient's cells (termed REBc-) was 3-4 times that of normal controls, suggesting that the as yet undefined cellular function that is abrogated (or stimulated) by colchicine in normal cells may have been genetically impaired in these REBc- cells. Despite the resistance to colchicine, as manifested by the failure to stimulate collagenase, gross parameters of microtubular function, such as cell replication, were intact. Phenotypically, this patient had a form of epidermolysis bullosa intermediate between typical recessive dystrophic and recessive letalis forms of the disease. Although an experimentally induced blister was located in the lamina lucida, hypoplastic anchoring fibrils were also observed. These findings, in addition to the marked increase in collagenase synthesis, suggest the possibility that this patient may represent a compound heterozygote of two forms of epidermolysis bullosa and that colchicine may be useful in defining other such patients.

Enhanced cell-free translation of human skin collagenase in recessive dystrophic epidermolysis bullosa

The regulatory mechanisms for collagenase synthesis in recessive dystrophic epidermolysis bullosa (RDEB) have been studied using messenger RNA (mRNA) harvested from normal and RDEB skin fibroblasts to direct protein synthesis in a rabbit reticulocyte lysate translation system. Fibroblast mRNA encoded the synthesis of approximately 60,000 and approximately 55,000 dalton forms of procollagenase in cell-free translation. In contrast to biosynthesis by intact cells, there was preferential translation of the approximately 60,000 dalton specie. For quantitative comparisons with mRNA from normal cells, mRNA was harvested from fibroblasts of 2 RDEB patents whose intact cells have been documented to have increased synthesis of collagenase. Although total translational activity was equal in normal and RDEB mRNA preparations, translatable collagenase mRNA was increased 3.5- to 10-fold, suggesting that the enhanced collagenase synthesis characteristic of RDEB is due to increased concentrations or preferential translation of collagenase mRNA.

Abnormalities in collagenase expression as in vitro markers for recessive dystrophic epidermolysis bullosa

In order to correlate a characteristic clinical phenotype with biochemical abnormalities in recessive dystrophic epidermolysis bullosa, fibroblast cultures were established from 4 typical patients with the severe form of the disease. Collagenase, the enzyme implicated in the pathogenesis of blistering, was present in vitro in 2- to 4-fold greater concentrations than in control fibroblast cultures. Partially purified preparations of this enzyme displayed marked thermal lability and diminished affinity for Ca2+, a metal cofactor, suggesting the existence of a mutant enzyme. The data suggest that these 3 biochemical abnormalities, increased synthesis, decreased thermal stability and diminished affinity for Ca2+, should serve as reliable in vitro markers for genetic discrimination of recessive dystrophic epidermolysis bullosa.

Human skin collagenase in recessive dystrophic epidermolysis bullosa. Purification of a mutant enzyme from fibroblast cultures

Recessive dystrophic epidermolysis bullosa, a genodermatosis characterized by dermolytic blister formation in response to minor trauma, is characterized by an incresaed collagenase synthesis by skin fibroblasts in culture. Since preliminary studies of partially purified recessive dystrophic epidermolysis bullosa collagenase suggested that the protein itself was aberrant, efforts were made to purify this enzyme to homogeneity, so that detailed biochemical and immunologic comparisons could be made with normal human skin fibroblast collagenase. Recessive dystrophic epidermolysis bullosa skin fibroblasts obtained from a patient documented to have increased synthesis of the enzyme were grown in large scale tissue culture and both serum-free and serum-containing medium collected as a source of collagenase. The recessive dystrophic epidermolysis bullosa collagenase was purified to electrophoretic homogeneity using a combination of salt precipitation, ion-exchange, and gel-filtration chromatography. In contrast to the normal enzyme, the recessive dystrophic epidermolysis bullosa collagenase bound to carboxymethyl-cellulose at Ca(2+) concentrations at least 10 times higher than those used with the normal enzyme. Additionally, this enzyme was significantly more labile to chromatographic manipulations, particularly when serum-free medium was used. However, rapid purification from serum-containing medium yielded a preparation enzymatically equivalent to normal human skin collagenase. Like the normal enzyme, the recessive dystrophic epidermolysis bullosa collagenase was secreted as a set of two closely related zymogens of approximately 60,000 and approximately 55,000 daltons that could be activated by trypsin to form enzymically active species of approximately 50,000 and approximately 45,000 daltons, respectively. Amino acid analysis suggested slight variations between the normal and recessive dystrophic epidermolysis bullosa collagenases. Cyanogen bromide digests demonstrated peptides unique to the enzyme from each source. The recessive dystrophic epidermolysis bullosa proenzyme was significantly more thermolabile at 60 degrees C than the normal, a finding that correlated with an approximate fourfold decrease in the affinity of the mutant enzyme for Ca(2+), a known activator and stabilizer of human skin collagenase. Aside from the altered affinity for this metal cofactor, kinetic analysis of the structurally altered recessive dystrophic epidermolysis bullosa collagenase revealed that its reaction rates and substrate specificity for human collagen types I-V were identical to those for the normal enzyme. Likewise, enzymes from both sources displayed identical energies of activation and deuterium isotope effects. Antisera were raised to the normal and putatively mutant procollagenases respectively, and, although they displayed a reaction of identity in double diffusion analysis, immunologic differences were present in enzyme inhibition and quantitative precipitation studies. These studies indicate that recessive dystrophic epidermolysis bullosa is characterized by the increased synthesis of an enzymically normal, but structurally aberrant, collagenase.

Inhibition of collagen degradative enzymes by retinoic acid in vitro

The effects of a variety of retinoids on collagenase and gelatinase expression have been examined in skin fibroblast cultures derived from normal volunteers and from patients with the hereditary blistering disorder, recessive dystrophic epidermolysis bullosa. Both 13-cis- and all-trans-retinoic acid were effective inhibitors of collagenase production in both cell types. In the case of collagenase, the inhibition of collagenase activity was paralleled by a reduction in immunoreactive enzyme protein, suggesting that these retinoids act by inhibiting synthesis and/or secretion of the enzyme. Retinoic acid also inhibited production of the second enzyme in the collagen degradative pathway, gelatinase. In this case, the decrease in gelatinase activity was equal to or slightly greater than the achieved in collagenase expression. The observation that certain retinoids modulate the two crucial enzymes in the degradation of collagen in the skin suggests that they might be useful therapeutic agents in recessive dystrophic epidermolysis bullosa, a disease in which the pathogenesis of blistering is in part related to connective tissue destruction.

Phenytoin therapy of recessive dystrophic epidermolysis bullosa. Clinical trial and proposed mechanism of action on collagenase

We administered phenytoin (diphenylhydantoin) by mouth to 17 unselected patients to assess its ability to reduce blistering in recessive dystrophic epidermolysis bullosa (RDEB). Therapeutic response was correlated with blood levels of the drug. Although there was a decrease in blistering of 53 +/- 6 per cent (mean +/- S.E.) among all patients at levels of more than 8 microgram of phenytoin per milliliter, the response was variable, with 12 of 17 patients having a decrease in blistering of more than 40 per cent. Since increased collagenase in human skin has been implicated in the pathogenesis of blistering in RDEB, we examined the effect of phenytoin on this enzyme. Although the drug did not inhibit collagenase activity directly, its addition to human-skin explant and fibroblast cultures produced a 50 to 60 per cent decrease in collagenase activity and immunoreactive protein concentrations. These in vitro studies suggest that phenytoin inhibits synthesis or secretion of collagenase of both, and that the favorable clinical response can be explained by this inhibition.