Granzyme B inhibition reduces disease severity in autoimmune blistering diseases

Pemphigoid diseases refer to a group of severe autoimmune skin blistering diseases characterized by subepidermal blistering and loss of dermal-epidermal adhesion induced by autoantibody and immune cell infiltrate at the dermal-epidermal junction and upper dermis. Here, we explore the role of the immune cell-secreted serine protease, granzyme B, in pemphigoid disease pathogenesis using three independent murine models. In all models, granzyme B knockout or topical pharmacological inhibition significantly reduces total blistering area compared to controls. In vivo and in vitro studies show that granzyme B contributes to blistering by degrading key anchoring proteins in the dermal-epidermal junction that are necessary for dermal-epidermal adhesion. Further, granzyme B mediates IL-8/macrophage inflammatory protein-2 secretion, lesional neutrophil infiltration, and lesional neutrophil elastase activity. Clinically, granzyme B is elevated and abundant in human pemphigoid disease blister fluids and lesional skin. Collectively, granzyme B is a potential therapeutic target in pemphigoid diseases.

Interstitial collagenase is expressed by keratinocytes that are actively involved in reepithelialization in blistering skin disease

Migrating keratinocytes actively involved in reepithelialization in dermal wounds acquire a collagenolytic phenotype upon contact with the dermal matrix. To determine whether this phenotype is associated with repair in other forms of wounds, we assessed collagenase expression in 50 specimens representing a variety of blistering skin diseases, including subtypes of epidermolysis bullosa, porphyria cutanea tarda, bullous pemphigoid, pemphigus, transient acantholytic dermatosis, and suction blisters. Distinct from that seen in chronic ulcers or in normal healing by second intention, reepithelialization in these blistering conditions was not necessarily associated with a complete loss of basement membrane, as determined by immunostaining for type IV collagen. Collagenase mRNA was detected in the basal keratinocytes of several specimens of epidermolysis bullosa simplex (six of 10) and of pemphigus (three of seven), as well as in one quarter of transient acantholytic dermatosis samples in the presence of an intact basement membrane. In contrast, three of nine porphyria cutanea tarda, one third of epidermolysis bullosa acquisita, and one of 10 bullous pemphigoid samples had collagenase-positive basal keratinocytes with the basement membrane disrupted. The collagenase-positive lesions generally represented older blisters with evidence of epithelial regeneration. Collagenase was also expressed in suction blisters at 2 and 5 d after induction of the blister, but was shut off when the epidermis had healed. Other metalloproteinases were expressed occasionally, if at all. Our results suggest that keratinocyte migration is associated with collagenase expression and that contact of keratinocytes with the dermal matrix is not necessarily needed for collagenase induction.

Cleavage of type VII collagen by interstitial collagenase and type IV collagenase (gelatinase) derived from human skin

Type VII collagen is the major structural protein of anchoring fibrils, which are believed to be critical for epidermal-dermal adhesion in the basement membrane zone of the skin. To elucidate possible mechanisms for the turnover of this protein, we examined the capacities of two proteases, human skin collagenase, which degrades interstitial collagens, and a protease with gelatinolytic and type IV collagenase activities, to cleave type VII collagen. At temperatures below the denaturation temperature, pepsin cleaves type VII collagen into products of approximately 95 and approximately 75 kDa. Human skin collagenase cleaved type VII collagen into two stable fragments of approximately 83 and approximately 80 kDa, and the type IV collagenase (gelatinase) produced a broad band of approximately 80 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cleavage of type VII collagen was linear with time and enzyme concentration for both enzymes. Although the Km values were similar for both enzymes, the catalytic rate of cleavage by type IV collagenase is much faster than by interstitial collagenase, and shows a greater rate of increase with increasing temperature. Sequence analysis of the cleavage products from both enzymes showed typical collagenous sequences, indicating a relaxation in the helical part of the type VII collagen molecule at physiological temperature which makes it susceptible to gelatinolytic degradation. Interstitial collagenase from both normal skin cells and cells from patients with recessive dystrophic epidermolysis bullosa, a severe hereditary blistering disease in which both an anchoring fibril defect and excessive production of collagenase can be observed, produced identical cleavage products from type VII collagen. These data suggest a pathophysiological link between increased enzyme levels and the observed decrease or absence of anchoring fibrils.

Collagenase expression in skin fibroblasts from families with recessive dystrophic epidermolysis bullosa

The collagenase production of cultured skin fibroblasts from Scandinavian families with dominant (D-EBD) and recessive (R-EBD) epidermolysis bullosa dystrophica has been investigated. Heterogeneity as a result of body location origin has been ruled out as fibroblasts obtained from predilection sites produce the same amount of immunoreactive collagenase as those obtained from non-predilection sites of the same subjects. Large variations in in vitro collagenase production were found between individuals and families. Within the R-EBD group, four out of eighteen patients showed an in vitro elevated level of immunoreactive collagenase compared to their healthy relatives, other EB types, and the control group. This shows that an in vitro elevated collagenase production is not a marker for the entire disease group and that the disease denoted as R-EBD probably is etiologically and pathogenetically heterogeneous.

A perspective on the role of collagenase in recessive dystrophic epidermolysis bullosa

The pathophysiology of tissue fragility in recessive dystrophic epidermolysis bullosa may be due in part to excessive destruction of interstitial collagens by a structurally altered, but catalytically active, form of human skin collagenase. Therapeutic attempts directed toward reducing the expression of this enzyme have resulted in clinical improvement in some patients with the disease.

Response of epidermolysis bullosa fibroblasts to factors derived from macrophages and polymorphonuclear leukocytes in terms of collagenase production

In order to investigate the role of inflammatory cells in altering the collagenase production by epidermolysis bullosa (EB) fibroblasts, macrophage and polymorphonuclear leukocyte (PMN) factors obtained from mouse peritoneal fluids were added to the fibroblast culture system, and collagenase activity was assayed after a 48-h incubation. Data obtained here revealed that the response of collagenase production by fibroblasts was quite different, depending on the type of EB. Namely, EB dystrophica recessiva (EBDR) (n = 2) fibroblasts produced significant amounts of collagenase in the range of 5.07 (U/ml) to 6.04 in response to macrophage-conditioned medium, macrophage lysate, and PMN lysate, compared with 0.13 in the absence of these. On the other hand, EB dystrophica dominans (EBDD) (n = 1) fibroblasts showed little or no overt increase in enzyme production in the presence of macrophage lysate and PMN lysate, which resulted in a moderate increase to 3.82 in response to macrophage-conditioned medium. Furthermore, EB simplex (EBS) (n = 1) fibroblasts produced collagenase up to 3.84 in response to these three factors. These factors can be inactivated by treating with trypsin, pronase, and phenylglyoxal. Our data clearly indicated that, in the comparisons of EBDD and EBS fibroblasts, EBDR fibroblasts showed quite high response to factors derived from macrophages and PMNs in terms of collagenase production. This fact may raise a clue that accounts for the high levels of tissue collagenase activity, which plays a potentially major role in blister formation in EBDR.

The association of congenital skin disorders with acetylcholinesterase in amniotic fluid

We describe a fetus with epidermolysis bullosa dystrophica and a fetus with aplasia cutis congenita who were normal by careful ultrasound examination but whose midtrimester amniotic fluids exhibited elevated concentrations of alpha-fetoprotein and presence of acetylcholinesterase. These cases show that serious fetal skin pathology can be a source of amniotic fluid acetylcholinesterase and elevated alpha-fetoprotein concentration and should be considered as part of the differential diagnosis of these amniotic fluid findings.

Elevated serum chymotrypsin levels in a patient with junctional epidermolysis bullosa. Normalization after UVB therapy with good clinical response

A 36-year-old Hispanic woman, covered with blisters since birth, was found to have markedly elevated chymotrypsin levels in her serum. This proteolytic enzyme is thought to digest laminin, thus causing separation of the basement membrane at the level of the lamina lucida, corroborating findings on electron microscopy. On the basis that the sun-exposed areas of the skin were relatively less involved, she received a course of UVB therapy, with total clinical clearance of her lesions after 3 weeks. A repeat estimation of serum chymotrypsin at this time revealed normal levels of this enzyme. It is thought that the elevated chymotrypsin levels were either released from the Langerhans cells themselves or from lymphocytes or keratinocytes as a result of Langerhans cell activity, and that the suppression of Langerhans cell activity by UVB inhibited the release of this proteolytic enzyme, resulting in the suppression of blister formation in our patient.

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.

Gelatinase expression in generalized epidermolysis bullosa simplex fibroblasts

The use of gelatinase expression in dermal fibroblast cultures as a marker for generalized epidermolysis bullosa simplex (D-EBS-Köbner) has been tested. None of the 6 Köbner patients tested (from 3 families) produced reduced amounts of gelatinase compared with their healthy relatives and other control groups. This shows that a reduced production of gelatinase from dermal fibroblasts is not uniformly a marker for D-EBS-K.

Proteases are responsible for blister formation in recessive dystrophic epidermolysis bullosa and epidermolysis bullosa simplex

The specific factors which induce blister formation in recessive dystrophic epidermolysis bullosa (RDEB) and epidermolysis bullosa simplex (EBS) were studied by culturing normal human skin with blister fluid from patients with RDEB and EBS. When skin from a healthy person was cultured with RDEB blister fluid, it developed a clean subepidermal blister with histology similar to that of a RDEB blister. The specific factor(s) which induced this subepidermal blister was inactivated by heat (60 degrees C, 30 min), trypsin digestion and by treating with EDTA, EGTA, alpha 2-macroglobulin, soybean trypsin inhibitor (SBTI) or N-ethylmaleimide (NEM), but was not affected by dialysis. These findings suggest that the active factor(s) in the blister fluid from patients with RDEB might include collagenase, neutral thiol protease and trypsin-like protease. By contrast, when normal skin was cultured with EBS blister fluid, this produced a clean intra-epidermal blister with histology similar to that of an EBS blister. The specific factor(s) inducing the intra-epidermal blister was inactivated by heat (60 degrees C, 30 min), trypsin digestion and by treating with NEM, but was not affected by dialysis, divalent cation chelators (EGTA, EDTA), alpha 2-macroglobulin, SBTI and pepstatin. These results suggest that the active factor(s) inducing the intra-epidermal blister in EBS might be a neutral SH-protease.

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.

N-acetyl-beta-glucosaminidase activity in serum of patients with epidermolysis bullosa

A spectrophotometric study for serum N-acetyl-beta-glucosaminidase activity in patients with different types of epidermolysis bullosa and other bullous diseases was carried out. The activity in recessive type of epidermolysis bullosa dystrophica was higher than in dominant type of epidermolysis bullosa dystrophica and other bullous diseases. High levels of this enzymatic activity may be related to the metabolism of glycosaminoglycans, especially hyaluronic acid in recessive type of epidermolysis bullosa dystrophica.

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.

The activity of arylsulphatases in serum of patients with several bullous diseases

Spectrophotometric estimations of levels of activities of arylsulphatases A and B in serum of patients with several bullous diseases were carried out. The activities of these enzymes in cases of bullous pemphigoid were at high levels in comparison with those in cases of other bullous diseases and in the control group. Especially, the activity of arylsulphatase B was remarkably increased. It seems likely that there is some relationship between these disturbances and the pathogenesis of bullous pemphigoid.

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.

Increased neutral protease and collagenase activity in recessive dystrophic epidermolysis bullosa

The enzyme activities of normal-looking skin and blister fluid from a patient with recessive dystrophic epidermolysis bullosa (RDEB) were measured. Of the hydrolytic enzymes measured, both collagenase and neutral protease activities were considerably increased in the skin and blister fluid samples compared with values found in normal control skin and in blister fluid from a patient with a burn. In addition, skin from a healthy person cultured with RDEB blister fluid showed dermal-epidermal separation. These findings suggest that collagenase and neutral protease may be involved in the formation of blisters in RDEB.

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.

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.

[Progress in dermatology: new biochemical aspects]

Recent biochemical advances have contributed to clarification of certain skin diseases and metabolic disturbances with predominantly cutaneous symptoms. This is illustrated by the various forms of porphyria. Today we differentiate four hepatic forms: acute intermittent porphyria, variegate porphyria, hereditary coproporphyria and porphyria cutanea tarda, and two erythropoietic forms: congenital erythropoietic porphyria and erythropoietic protoporphyria, all of which are due to an inborn enzymatic deficiency of the heme biosynthesis. From the different forms of ichthyosis, the X-recessive ichthyosis has an underlying enzymatic deficiency of the steroid sulfatase, which seems of significance in the disturbance of keratinization. In epidermolysis bullosa dystrophica type Hallopeau-Siemens an increased collagenase activity was detected. Inhibition of this enzyme by phenytoin results in improvement of the blistering in this genodermatosis. The etiology and pathogenesis of psoriasis are unclear despite extensive efforts. The recently detected deficiency of the arylhydrocarbon-hydroxylase and its inducibility must be confirmed, additionally its significance in the pathogenesis of this disease is yet to be evaluated.

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.

Assay of collagenase activity by a rapid, sensitive, and specific method

A new method for the assay of collagenase activity has been developed, whereby the collagen cleavage products, after initial collagenase digestion, are degraded further by a mixture of trypsin and alpha-chymotrypsin. The degradation products are soluble in TCA and can be conveniently separated from the remaining uncleaved collagen substrate by rapid filtration. The enzyme assay is shown to be reproducible and sensitive, and it lends itself to a convenient and rapid determination of collagenase activity in relatively large numbers of samples. The applicability of this method is demonstrated by the detection of increased collagenase activity in skin fibroblast cultures derived from a patient with recessive dystrophic epidermolysis bullosa.

Deficiency of galactosylhydroxylysyl glucosyltransferase, an enzyme of collagen synthesis, in a family with dominant epidermolysis bullosa simplex

Members of a family with dominant epidermolysis bullosa simplex were found to have a deficiency of galactosylhydroxylysyl glucosyltransferase (GGT), an enzyme catalyzing the glucosylation of galactosylhydroxylysyl residues in the biosynthesis of collagen. The enzyme's activity was low in serum, skin tissue, and cultured skin fibroblasts, although no abnormality was found in three other intracellular enzymes of collagen biosynthesis. Mixtures of serum samples from patients and healthy controls gave the expected GGT activity, indicating that the low values were not due to inhibitors. GGT deficiency was accompanied by decreased product formation in vivo, as shown by a markedly decreased urinary excretion of glucosylgalactosylhydroxylysine. Six of 12 affected members had definite GGT deficiency, and five had some evidence suggestive of this abnormality; 13 of 15 unaffected members had no such manifestations. No similar GGT deficiency was found in three other families with the same disease. We conclude that GGT deficiency may be etiologically related to this disease in some families, but that different defects must be the cause in other cases.

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.

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

Using a sensitive, specific immunoprecipitation method, the biosynthesis of human skin collagenase was studied in fibroblast cultures from patients with recessive dystrophic epidermolysis bullosa. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of solubilized immunoprecipitates showed two 3H-labeled procollagenase species that comigrated with those harvested from control cultures. Recessive dystrophic epidermolysis bullosa cultures accumulated increased amounts of collagenase. Both the initial rate of accumulation of intracellular enzyme and the rate of secretion were enhanced, suggesting that excessive accumulation is related to increased synthesis. Because the turnover of labeled collagenase was unaltered, the accumulation could not be attributed to diminishing enzyme degradation. No preferential incorporation of [3H]leucine into recessive dystrophic epidermolysis bullosa collagenase occurred. Furthermore, the mutant cultures displayed no alteration in total protein synthesis, the intracellular leucine pool, or the growth kinetics of the cells. Cells from a patient with dominant epidermolysis bullosa did not show enhanced accumulation of collagenase. The levels of collagenase synthesized in vitro correlated with those observed previously in vivo in recessive dystrophic epidermolysis bullosa patients, suggesting that this biochemical trait is pathogenetically significant in the disorder.

[The effect of collagenase inhibition on bullous eruption and healing process in epidermolysis bullosa]

The collagenase inhibiting effect of erythromycin already observed in vitro was demonstrated also after oral administration of the drug in vivo in one child with epidermolysis bullosa letalis and one child with epidermolysis bullosa dystrophica. Despite inhibition of skin collagenase activity during administration of the drug the frequency of bullous eruptions and healing process of affected skin areas remained unchanged. This suggests no direct causal relation existing between skin collagenase activity and epidermolysis bullosa. Whether increased collagenase activity reflects a secondary reaction of the organism cannot be concluded from this study.

[In-vitro inhibition of collagenase activity in epidermolysis bullosa hereditaria dystrophica]

By means of a biological collagenase assay we estimated collagenolytic activity of the vesicular fluid of patients with epidermolysis bullosa hereditaria dystrophica. All the 5 examined patients showed increased collagenolysis. Inhibition studies were performed applying ethylendiaminetetraacetate inhibition 11,15%, normal human serum in 12.15% (means). o-Phenanthroline as well as erythromycine in an aequimolar ratio stopped the collagenolytic activity completely in the 5 specimen. It was the aim of our study to indicate that erythromycine, in contrast to other collagenase inhibitors relatively atoxic, is able to inhibit collagenase activity which is suggested to play a pathogenetic role in that disease.

Recessive dystrophic epidermolysis bullosa. Evidence for increased collagenase as a genetic characteristic in cell culture

Fibroblast cultures from patients with recessive dystrophic epidermolysis bullosa (RDEB) demonstrated an increased capacity to synthesize and secrete collagenase. This phenotypic trait appeared to distinguish RDEB from other genetically distinct forms of epidermolysis bullosa. The finding of increased collagenase may be a specific manifestation of these cells in that prototypic lysosomal and cytoplasmic enzymes were present in approximately normal concentrations. In addition, this trait persisted through many cell passages, suggesting that the property was genetically determined. The elevated concentrations of immunoreactive collagenase in fibroblast cultures of patients with RDEB reflected those previously observed in vivo (4) and support the concept of a pathogenetic role for the enzyme in the blistering phenomenon. In three of the cell lines, the increase in enzyme protein occurred in association with a structurally defective enzyme. The data suggest that this may be a characteristic of all RDEB cells.

Recessive dystrophic epidermolysis bullosa: evidence for an altered collagenase in fibroblast cultures

Collagenase has been implicated in the pathogenesis of blister formation in recessive dystrophic epidermolysis bullosa. In order to examine whether aberrations in this enzyme are important in the disease, fibroblast cultures from two patients were used to compare the properties of the collagenases from the mutant cells with those from control fibroblast lines. Purified procollagenase preparations from the mutant fibroblasts were significantly more thermolabile at low Ca2+ concentration than control enzymes. They also showed a decrease in affinity for Ca2+, a cofactor required both for enzyme activity and thermal stability. In addition, the collagenase from each mutant line displayed diminished specific activity, expressed as activity per unit of immunoreactive protein, with a mean value of 39% of control for one patient's enzyme and 16% for the other. The data support the postulate that, in these two patients, the altered collagenase is the result of a structural gene mutation, a defect in the post-translational modification of the enzyme, or a mutation in a gene regulating the normal degradation of collagenase.

[Vesicular fluid of hereditary bullous dystrophic epidermolysis splits alpha 1-antitrypsin]

In epidermolysis hereditaria bullosa dystrophica increased collagenase activity can be detected and seems to be one of the pathogenetic mechanisms of this disease. Neither the origin nor the mechanism of increased collagenolysis is known. Whether the cause of the enzymatic imbalance is the increased collagenase production or decreased collagenase-inhibitor activity cannot be decided. Factors of decreased protease inhibitor activity could be the quantitative or qualitative defect or the inactivation of the inhibitor. Clear, sterile vesicular fluid was incubated with alpha-1-antitrypsin, which is known to inhibit collagenase. By means of an immunoelectrophoretic method the cleaving of the inhibitor into two antigenic split products was found. We suggest that this might be responsible for the increased collagenolysis in this form of epidermolysis.

The role of human skin collagenase in epidermolysis bullosa

Human skin collagenase was quantitated by radioimmunoassay in 40 patients with various forms of epidermolysis bullosa to compare levels of the enzyme in blistered and clinically unaffected skin. Immunoreactive human skin collagenase was significantly elevated in the blistered skin of patients with both recessive and dominant forms of dystrophic epidermolysis bullosa (DEB). In addition, patients with generalized recessive DEB manifested a 4-fold increase in collagenase protein in normal-appearing skin, and patients with localized recessive DEB or epidermolysis bullosa letalis showed a 3-t to 3.5-fold elevation in the enzyme. However, patients with dominantly inherited DEB failed to displays a statistically significant increase in immunoreactive collagenase in nonblistered skin. Although it cannot be definitely stated whether the elevated collagenase content in the blistered skin represents a primary or secondary event, such as part of a wound healing response, the demonstration of markedly increased levels of collagenase in normal-appearing skin could, in part, provide an explanation at the molecular level for the formation of blisters in this disease.

Epidermal neoplasms with epidermolysis bullosa dystrophica with the first report of carcinoma with the acquired type

Carcinoma, usually always squamous cell carcinoma, is one of the most serious complications in epidermolysis bullosa dystrophica. It can occur on the skin, mucous membranes, the esophagus and possibly the upper part of the bronchial tree. We are reporting on four new patients; one, the youngest to be so reported, one with a definite autosomal dominant inheritance and one with a chronic acquired dystrophica epidermolysis bullosa. Most cases have an autosomal recessive inheritance, but the disorder is probably more hetereogeneous in its inheritance than has been reported. Studies of the collagen indicate a disturbance, but present studies indicate the defect to be more a cellular defect in the fibroblast yet undetermined. The carcinomas, usually multiple, appear to arise on scarred tissue and to metastasize rapidly with death.