The evolution of sexual health nursing in Australia: a literature review

Background: The purpose of this paper is to describe and encapsulate the elements of the sexual health nurse’s role in Australia. In Australia, sexual health nursing is a fast evolving speciality operating within a climate of diverse role expectations, settings and population groups. Today’s health care climate demands that nurses’ roles and their impact on patient care be held up to scrutiny. Methods: A literature review was conducted that used descriptive analysis to elicit the recurrent themes appearing in the Australian sexual health nursing literature that would describe the role. Results: A model of sexual health nursing was evident with the two primary themes of professional responsibility and patient care. The professional role included a philosophy of sharing nursing experiences, collaboration, employment in multiple settings, and the development of the role into advanced practice, appropriate academic and clinical preparation and a commitment to research. The patient care role included the provision of individual and holistic patient care, ability to access specific at-risk groups, clinical effectiveness, patient education and community development roles. Conclusion: Australian sexual health nurses make a specific and measurable contribution to the health care system. They are likely to continue to advance their role supported by appropriate research that validates their models of practice, continues their philosophy of sharing their experiences and that documents the impact they have on the health outcomes of individuals and populations.

Tyrosine phosphorylation of human keratinocyte beta-catenin and plakoglobin reversibly regulates their binding to E-cadherin and alpha-catenin

We show that tyrosine phosphorylation, produced by incubation of normal human keratinocytes with the tyrosine phosphatase inhibitor peroxovanadate, directly and reversibly regulates the association of beta-catenin and plakoglobin with E-cadherin and alpha-catenin. Prior studies have demonstrated a correlative, but not causal, association between increased tyrosine phosphorylation and decreased adherens junction mediated cell-cell adhesion. We observed that (i) binding of tyrosine phosphorylated beta-catenin and plakoglobin to E-cadherin and to alpha-catenin was substantially reduced, but could be restored in vitro by removal of phosphate from beta-catenin and plakoglobin with added tyrosine phosphatase, and (ii) tyrosine phosphorylation of beta-catenin and plakoglobin was associated with decreased cell-cell adhesion. These findings support a direct and causal role for tyrosine phosphorylation of beta-catenin and plakoglobin in regulating adherens junction mediated cell-cell adhesion. We propose that tyrosine phosphorylation of specific and probably different residues is responsible for regulating the binding of beta-catenin or plakoglobin to (i) E-cadherin and (ii) alpha-catenin. Additionally, because beta-catenin and plakoglobin have both structural and regulatory functions, the data raise the possibility that beta-catenin or plakoglobin released from the adherens junctions by tyrosine phosphorylation may transduce a signal to the nucleus regarding the adhesive state of the cell.

Hailey-Hailey disease keratinocytes: normal assembly of cell-cell junctions in vitro

The blisters in the inherited disorder, Hailey-Hailey disease, may be caused by defective epidermal junctional complexes. We evaluated these structural complexes in vivo and in vitro. We induced a vesicular lesion in the apparently normal skin of a patient with Hailey-Hailey disease and studied a biopsy of this lesion by transmission electron microscopy. To determine whether acantholysis was related to a defect in the number or assembly of intercellular junctions, we cultured Hailey-Hailey disease keratinocytes in medium containing 0.1 mM Ca2+ and increased the [Ca2+] to 1.1 mM in order to induce assembly of cell-cell junctions. Keratinocytes were examined by double immunofluorescence with antibodies to the desmosome protein, desmoplakin, and the adherens junction protein, vinculin, at intervals after the increase in [Ca2+]. Characteristic Hailey-Hailey disease histopathology was observed by electron microscopy of the patient's skin after trauma, but we found no splitting of desmosomes. Based on the location, intensity, and rate of change of immunofluorescent staining, Hailey-Hailey and normal keratinocytes did not differ in their ability to assemble desmosomes and adherens junctions. Furthermore, we observed no significant morphologic differences between normal and Hailey-Hailey keratinocytes cultured in low and high [Ca2+]-containing media; Hailey-Hailey cells contained abundant normal-appearing desmosomes in 1.1 mM [Ca2+]. Since Hailey-Hailey disease keratinocytes can assemble normal-appearing adherens junctions and desmosomes in vitro, the functional defect may not lie in assembly of cell-cell adhering junctions, or additional perturbation may be required to expose the defect.

An adherens junction protein is a member of the family of lactose-binding lectins

We previously described a pig junction protein of M(r) 37,000 found in oral epithelium but not in epidermis, limited to suprabasal cells, and colocalizing by immunofluorescence with adherens junction proteins. A 1.1-kilobase pair cDNA of the 37-kDa protein yielded an open reading frame encoding a 323-amino acid protein of 35,852 Da, and Northern analysis demonstrated a band of 1.2 kilobases in tongue RNA. Secondary structure predictions indicate that the 37% identical 16-17-kDa N- and C-terminal domains from beta-sheet-rich barrels linked by a compact proline-rich segment. The protein is 72% identical in amino acid sequence and shares symmetrical two-domain structure with L-36, a lectin of unknown function from rat intestine, indicating that the 37-kDa protein is the porcine form of L-36. Of the homologous lactose binding lectins known, two others, invertebrate lectins, share this symmetrical structure. Expression of the C-terminal domain of the pig lectin in bacteria yields a lectin which binds lactosyl-Sepharose, and binding is inhibited by lactose. The expressed protein binds a glycoprotein of 120 kDa from pig tongue epithelium on Western blots, and this is also inhibited by lactose. The findings suggest that the lectin function may be involved in the assembly of adherens junctions.

Talin: adherens junction protein is localized at the epidermal-dermal interface in skin

The interaction between cells of the epidermis and the basal lamina is important for the integrity of the skin. Several hereditary and acquired diseases show changes at the dermal-epidermal interface due to loss of adhesion between basal cells and the basement membrane. The structures mediating this interaction are hemidesmosomes, which have been extensively characterized by biochemical, molecular biologic, and morphologic techniques. Recently, however, a group of adhesion molecules that are distinct from hemidesmosomes and that mediate cell-matrix interactions was described in cultured fibroblasts, keratinocytes, and skin. These adhesion molecules, beta 1 integrins, have been shown to be present in the focal adhesion, a cell-matrix contact associated with microfilaments rather than intermediate filaments characteristic of hemidesmosomes. In cultured cells, integrins of the beta 1 family have been shown to be linked by a protein complex to actin filaments. In this study we describe the localization of talin, the binding protein for beta 1 integrins, and vinculin at the dermal-epidermal interface in skin with immunofluorescence and immunoblotting techniques. These data suggest the presence of a link between the cytoplasmic actin filament system in basal keratinocytes and the extracellular matrix.

Re-epithelialization. Human keratinocyte locomotion

Keratinocyte migration and proliferation both play a role in covering skin wounds by the process of re-epithelialization. Connective tissue components are a powerful influence on keratinocyte locomotion. The mechanisms of keratinocyte locomotion and cellular division are independent. Both connective tissue components and soluble factors may serve to enhance keratinocyte migration. In addition to the field of growth factors, we would like to suggest that there should be the recognition of an entire new class of agents called migration factors.

Trichohyalin: a structural protein of hair, tongue, nail, and epidermis

In the course of studies of desmosomes, we found trichohyalin, a 200-kDa protein of the inner root sheath and medulla, in a citric acid-insoluble fraction ("desmosome preparation") from tongue epithelium. Pig tongue epithelium yielded milligram quantities of pure trichohyalin from about 100 g of keratomed epithelium. The protein has an extended shape as determined by gel filtration, ultracentrifugation, and electron microscopy, with a rod domain and a globular domain at one end and overall dimensions of about 85 nm. Crosslinking studies suggest that the protein may be dimeric in solution. The protein is a doublet in some animals but apparently is a single polypeptide of 220 kDa in humans. Immunofluorescence studies showed that it is a major protein of the filiform papillae of the tongue of mammals and is present in isolated cells of the stratum granulosum of some regions of epidermis in a subset of cells containing filaggrin and in the nail matrix. Similarly, in filiform papillae some cells contain granules that stain for both trichohyalin and filaggrin. Immunoblotting confirmed that trichohyalin is present in tongue and epidermis. Polymerase chain reaction with human genomic DNA using oligonucleotide primers based on sheep trichohyalin resulted in synthesis of multiple DNAs, from which a 504-bp fragment was subcloned and sequenced and found to resemble closely the carboxyl terminus of sheep trichohyalin. Studies with antibody to the carboxyl-terminal 14 amino acids of the human sequence show that, whereas the carboxyl-terminal epitope is present only in the stratum granulosum, in epidermis epitopes detected by a monoclonal antibody are demonstrated in both the stratum granulosum and stratum corneum, suggesting that the carboxyl terminus is cleaved in the stratum corneum.

The structure of human trichohyalin. Potential multiple roles as a functional EF-hand-like calcium-binding protein, a cornified cell envelope precursor, and an intermediate filament-associated (cross-linking) protein

Trichohyalin is an intermediate filament-associated protein that associates in regular arrays with keratin intermediate filaments (KIF) of the inner root sheath cells of the hair follicle and the granular layer of the epidermis and is a known substrate of transglutaminases. We have determined the full-length sequence of human trichohyalin by use of RNA-mediated anchored polymerase chain reaction methods and from a genomic clone and analyzed its potential secondary structure. We show here that trichohyalin may have at least three important functions in these cells. The protein of 248 kDa is unusual in that it contains one of the highest contents of charged residues of any protein. Of several defined domains, domains 2-4, 6, and 8 are almost entirely alpha-helical, configured as a series of peptide repeats of varying regularity, and are thought to form a single-stranded alpha-helical rod stabilized by ionic interactions between successive turns of the alpha-helix. Domain 6 is the most regular and may bind KIF directly by ionic interactions. Domains 5 and 7 are less well organized and may introduce folds in the molecule. Thus, human trichohyalin is predicted to be an elongated flexible rod at least 215 nm long and to function as a KIF-associated protein by cross-linking the filaments in loose networks. In addition, trichohyalin is similar to, but several times longer than, involucrin, a known cell envelope constituent, so that together, involucrin and trichohyalin may serve as scaffold proteins in the organization of the cell envelope of these cells or even anchor the cell envelope to the KIF network. Finally, trichohyalin possesses a pair of functional calcium-binding domains of the EF-hand type at its amino terminus that may be involved in its calcium-dependent postsynthetic processing during terminal differentiation.

Adherens junctions: demonstration in human epidermis

Adherens junctions are intercellular and cell-matrix junctions that, like desmosomes and hemidesmosomes, mediate adhesion of cells to each other or to matrix structures. These junctions have been detected recently in cultured human keratinocytes, indicating that they may be of importance in epidermis. To investigate the localization of adherens junctions in normal epidermis, we examined human epidermis, human oral mucosa, and monkey esophagus for the presence of vinculin, a major protein of the intracellular plaques of adherens junctions that is thought to be present in all adherens junctions. Western blot analysis demonstrated vinculin in extracts of epidermis. Immunohistochemistry of vinculin in these tissues displayed two distinct locations for adherens junctions: i) at the dermal-epidermal junction, and ii) in the region of cell-cell contacts in all layers of the epidermis. The location of vinculin in the region of the epidermal-dermal junction is reminiscent of the distribution of vinculin-containing focal contacts in cultured keratinocytes, and the intercellular staining of vinculin in epidermis is consistent with the presence of vinculin in adherens junctions in cultured keratinocytes at sites of cell-cell contact. These results demonstrate that adherens junctions are present in human epidermis, oral mucosa, and monkey esophagus. Vinculin-containing junctions in epidermis may be important in the pathogenesis of skin diseases involving alterations in intercellular integrity.

Human trichohyalin gene is clustered with the genes for other epidermal structural proteins and calcium-binding proteins at chromosomal locus 1q21

Trichohyalin is a major differentiation product of hard keratinizing tissues such as the inner root sheath and medullary cells of the hair follicle and the filiform papillae of the tongue, as well as terminally differentiating epidermal cells. It consists largely of quasi-repeating peptide repeats and functions primarily as an intermediate filament-associated protein in these tissues. By mapping with human-rodent somatic cell hybrids and fluorescent in situ hybridization, we demonstrate that its gene maps to chromosomal region 1q21. Interestingly, genes encoding several other structural proteins expressed during terminal differentiation in the epidermis map to this region, as do also several members of the S-100 class of small calcium-binding proteins.

Normal molecular weight of type VII collagen produced by recessive dystrophic epidermolysis bullosa keratinocytes

Studies of the recessive dystrophic form of epidermolysis bullosa (RDEB) have suggested that an abnormality in type VII collagen may be involved in the pathogenesis of this disorder. Indirect immunofluorescence studies have shown that the staining for type VII collagen along the dermal-epidermal junction is markedly reduced or absent in all but rare cases of severe, generalized RDEB. These findings imply that the genetic defect may involve type VII collagen but do not exclude the possibility that the alterations demonstrated are secondary, for example, to nonspecific proteolysis of type VII collagen. To evaluate the ability of cells of affected patients to produce type VII collagen, we cultured keratinocytes from a severely affected patient and immunoprecipitated type VII collagen from the cells. Keratinocytes were metabolically labelled with 35S-methionine, and solubilized cell extracts were reacted with antibody to type VII collagen. The results indicate that the patient's keratinocytes synthesize type VII collagen and that the M(r) of the protein synthesized does not differ from that of an unaffected control. Because cultured cells from a patient severely affected with recessive dystrophic epidermolysis bullosa produce type VII collagen, the genetic defect, at least in this patient, is unlikely to reside in a major truncation of the type VII collagen molecule.

Restricted tissue distribution of a 37-kD possible adherens junction protein

A major polypeptide of M(r) 37,000 was purified from a desmosome-enriched citric acid-insoluble pellet of pig tongue epithelium. The polypeptide was solubilized from the 4-M urea-insoluble pellet with 9 M urea, and extracts were separated by carboxymethyl cellulose and gel filtration chromatography. The 37-kD protein was obtained in milligram quantities as a single band on two-dimensional gels in 30% yield after 21-fold purification from the citric acid-insoluble fraction. The protein is not glycosylated and has a pI of approximately 8.7. Although isolated from a fraction rich in desmosomes, the 37-kD protein is not a desmosomal protein. Indirect immunofluorescence analysis of frozen sections of tongue and other tissues demonstrated that antibodies raised to the 37-kD protein bound only to suprabasal cell layers at punctate regions of the periphery of the cell and was absent from most regions of epidermis, whereas antibodies to desmoplakins I and II, desmosomal proteins, bound similarly but in all epidermal layers. Immunoelectron microscopy localized the 37-kD protein to the cell periphery in regions between, but never in, desmosomes. By immunofluorescence, the 37-kD protein colocalized with actin as well as with vinculin and uvomorulin in oral tissues. Like the 37-kD protein, vinculin and uvomorulin were absent from the basal layer. Based on its appearance, localization, and solubility properties, the 37-kD protein is probably a component of adherens junctions; its restriction to suprabasal cells and exclusion from the epidermis are unique.

Trichohyalin: purification from porcine tongue epithelium and characterization of the native protein

Trichohyalin, a protein of Mr between 190 and 220 kDa in different species, was first demonstrated in large granules of the inner root sheath and medulla of hair follicles and may provide a matrix for keratin filaments. We have purified trichohyalin in milligram quantities from a citric acid-insoluble fraction derived from pig tongue epithelium. Trichohyalin was extracted under conditions of low ionic strength from the citric acid-insoluble fraction, separated by gel-filtration chromatography in buffer containing 1 M NaBr, and concentrated by ion-exchange chromatography in buffer containing 4 M urea. The purified material, which is soluble in buffers containing 1 M NaBr, was considered to be trichohyalin because of its characteristic molecular weight and amino acid composition and its localization to hair follicle inner root sheath and medulla by indirect immunofluorescence using antibodies against the purified protein. Immunofluorescence showed that trichohyalin is a major protein of filiform papillae of the tongue. Unlike trichohyalin from other animals examined, the porcine protein is a doublet on SDS polyacrylamide gels of 195 and 210 kDa; both bands are recognized by different antibodies, their two-dimensional peptide maps are nearly identical, and they have nearly identical isoelectric points of about 6.6. Trichohyalin has a Stokes radius of 124 A on gel filtration and a Svedberg constant of 6, consistent with an extended structure. The protein probably associates reversibly in solution, and the native protein we have isolated may be dimeric, because crosslinking of the iodinated purified protein with disuccinimidyl suberate demonstrated the presence of a dimer, which could be dissociated in the presence of high concentrations of urea. Rotary shadowing electron microscopy of the native protein showed a filamentous structure averaging 85 nm in length with a single globular-appearing end-domain. The purification of native trichohyalin provides a basis for future functional studies.

Human autoantibodies against desmoplakins in paraneoplastic pemphigus

Recently, a previously unrecognized autoantibody mediated blistering disease, paraneoplastic pemphigus has been described. Paraneoplastic pemphigus is associated with lymphoid malignancies, thymomas, and poorly differentiated sarcomas. Serum of affected patients contain pathogenic autoantibodies that immunoprecipitate from normal keratinocytes a characteristic complex of four polypeptides with M(r) of 250, 230, 210, and 190 kD. As our preliminary studies indicated that the 250-kD and the 210-kD antigens comigrated with desmoplakins I and II, we investigated the possibility that autoantibodies against the desmoplakins were a component of this autoimmune syndrome. 11 sera from affected patients were tested by indirect immunofluorescence against desmosome containing tissues, immunoprecipitation of metabolically labeled keratinocytes, and Western immunoblotting of desmoplakins I and II that had been purified to homogeneity from pig tongue epithelium. By indirect immunofluorescence, 9 of 11 sera showed strong binding to epithelial and nonepithelial desmosomes, and 2 were weakly reactive. All 11 immunoprecipitated 250- and 210-kD bands of variable intensity that comigrated with bands identified by a murine monoclonal antidesmoplakin antibody, and immunoblotting confirmed binding of the serum autoantibodies to purified desmoplakins. This demonstrates that paraneoplastic pemphigus is the first human autoimmune syndrome in which autoantibodies against the desmoplakins are a prominent component of the humoral autoimmune response.

Skin reactions to radiotherapy--a spectrum resembling erythema multiforme: case report and review of the literature

Eruptions resembling erythema multiforme associated with radiotherapy are rare. Although several case reports are cited in the older literature, only recently has this phenomenon been described in patients receiving external beam radiation therapy both with and without contributory concurrent medications. The eruption typically begins within the radiation port and then generalizes; it is usually self-limited, but serious and fatal outcomes are reported. We review the literature and report a case of an eruption resembling erythema multiforme associated with external beam irradiation and 5-fluorouracil.

Human keratinocyte locomotion: the effect of selected cytokines

Epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) are two powerful mitogens for human keratinocytes that also have been shown to promote the healing of in vivo wounds. Transforming growth factor-beta (TGF-beta) markedly inhibits human keratinocyte proliferation and growth and yet has been shown to promote wound healing. Using a migration assay that evaluates pure cell locomotion independently from cell proliferation, we examined the influence of EGF, bFGF, and TGF-B on human keratinocyte locomotion. Although these agents had profound influences upon the growth potential of keratinocytes in parallel thymidine incorporation assays, they had no significant effect upon keratinocyte locomotion when cells were apposed to either tissue culture plastic or a collagen substratum. In contrast, we found that bovine pituitary extract (BPE), a poorly defined mitogen that is commonly used in keratinocyte cultures, could stimulate keratinocyte locomotion when the cells were apposed to a collagen substrate. These studies demonstrate that i) keratinocyte locomotion and proliferation operate by completely independent mechanisms, ii) the positive effects upon wound healing by EGF, bFGF, and TGF-beta are not due to a direct promotion of keratinocyte locomotion, and iii) that one or more components of BPE are capable of directly promoting keratinocyte locomotion on collagen.

Vitronectin: effects on keratinocyte motility and inhibition of collagen-induced motility

Epibolin, a plasma protein, was initially purified on the basis of its ability to enhance spreading of keratinocytes. It is now known that epibolin is identical to serum spreading factor, S protein, and vitronectin, and the current name for the protein is vitronectin. Studies of vitronectin on cultured keratinocytes showed that it caused spreading and epiboly but not cellular adhesion to the substratum. In studies with other types of cells, vitronectin increased migration of several types of cells in a Boyden chamber. Because some agents that enhance spreading and adhesion, such as collagen and fibronectin, also increase motility, we tested whether vitronectin increased motility of keratinocytes. By photographing and quantitating motility of keratinocytes plated on a bed of colloidal gold particles, we determined that vitronectin increased local movement of keratinocytes in a concentration-dependent fashion, resulting in clearing of gold particles in a circular pattern around the cells, but did not cause the production of tracks found in cultures plated on collagen or fibronectin. The small increases in clearing of the gold particles that occurred in the presence of vitronectin were abolished by antibody to vitronectin. Furthermore, the marked increase in motility produced by type I collagen was significantly reduced when the keratinocytes were treated with vitronectin. Antibody to vitronectin also abrogated the vitronectin-induced reduction in collagen-stimulated motility, confirming that this action was specific for vitronectin. Serum, which contains vitronectin, stimulated motility in a fashion identical to purified vitronectin, but serum lacking vitronectin was inactive. These studies show that vitronectin causes a localized increase in movement associated with spreading resulting in a halo around individual cells, that vitronectin does not enhance directional motility of keratinocytes in this assay but in contrast antagonizes such motility produced by collagen, and that vitronectin is the factor in serum responsible for this effect. The findings with vitronectin and collagen show that these agents stimulate different types of motility. The roles in wound healing of agents stimulating different types of motility are unclear and require further study.

Trichohyalin: presence in the granular layer and stratum corneum of normal human epidermis

Trichohyalin, a protein contained in granules in the cells of the hair-follicle inner root sheath and in the medulla of the hair shaft, has been purified previously from sheep hair bulbs and is also a major protein of filiform papillae of tongue epithelium. Polyclonal affinity-purified antibodies and a monoclonal antibody raised to purified pig tongue trichohyalin both stained the inner root sheath of hair follicles and the medulla of hair fibers and identified human trichohyalin as a single 220-kDa band on immunoblots of human hair bulb proteins. These antibodies were used to examine human epidermis by immunofluorescence and immunoblotting. The antibodies decorate granules in cells in the granular layer and stratum corneum of non-hair-bearing human skin, and immunoblots identify a protein in epidermis comigrating with trichohyalin from human hair and human tongue epithelium. Absorption of antibody to trichohyalin on a trichohyalin affinity column abrogated staining of the epidermis and the bands on the immunoblots. Trypsin-separated epidermis contained 220 and 160 kDa bands identified as trichohyalin, but epidermis shaved from skin and quickly frozen showed only a single 220-kDa band, indicating that the 160-kDa protein was generated by proteolysis. Double immunofluorescence for trichohyalin and filaggrin showed that some cells containing filaggrin also contain trichohyalin. These studies show that trichohyalin is not limited to hair and tongue but is present in isolated cells in the granular layer and stratum corneum of normal epidermis.

Characterization of "neo-dermis" formation beneath cultured human epidermal autografts transplanted on muscle fascia

Cultured human keratinocyte autografts were transplanted to burn wounds that had been completely excised down to muscle fascia such that all cutaneous elements were removed from the wounds. Healing autografts were biopsied from days 6-153 in five patients, and the "neo-dermis" beneath the autografts was examined by immunofluorescent staining using antibody probes to connective tissue molecules, by histochemical staining for elastin fibers, and by electron microscopy. We found that the neo-dermis contained most of the major connective tissue elements early in the post-transplantation period. However, regardless of the time examined, there was a paucity of elastin fibers and poor organization of linkin (microthread-like fibers) in the neo-dermis beneath autografts. The perturbations of these connective tissue components in the neo-dermis may play a role in the poor recoil and elastic properties of burn wounds treated with autografts.

Enhanced synthesis of collagenase by human keratinocytes cultured on type I or type IV collagen

Human keratinocytes in culture are known to produce collagenase. As part of studies to ascertain the physiologic stimuli for collagenase production by keratinocytes, we wanted to determine whether extracellular matrix could modulate the production of collagenase in vitro. Immunoprecipitable collagenase from the conditioned medium of cells grown on different types of matrix was measured. Metabolically labeled human keratinocytes were cultured in 0.1 mM calcium in serum-free medium on colloidal gold-coated coverslips plus type IV collagen, type I collagen, or laminin or in the absence of matrix. Immunoprecipitation of the conditioned medium with anti-collagenase antiserum was performed and the immunoprecipitates were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, fluorography, and densitometry. The keratinocytes cultured on type IV or type I collagen produced more collagenase than did those cultured on laminin or in the absence of matrix. This effect did not reflect a general increase in secreted proteins, because the production of tissue inhibitor of metalloproteinase, or TIMP, did not increase under the same conditions. Phagocytosis of the gold salts by the keratinocytes migrating on types I or IV collagen did not account for the increased collagenase produced by these cells since the effect persisted in the absence of the colloidal gold and phagocytosis of latex beads did not augment collagenase production.

Type IV collagen and fibronectin enhance human keratinocyte thymidine incorporation and spreading in the absence of soluble growth factors

In various cell culture systems, extracellular matrix components have been demonstrated to be mitogenic and, in some cases, to substitute for growth factors. In order to study the effects of various matrices on keratinocyte growth, we assessed the incorporation of tritiated thymidine and cell number on short-term cultures of human keratinocytes plated on different substrata. For determination of whether thymidine incorporation by keratinocytes was related to the ability of the cells to attach and spread on the substratum, experiments to determine the percentage of attached and spread cells on each matrix surface were performed. High levels of attachment and incorporation of thymidine with no preferential attachment to a given matrix were evident when the cells were cultured in the presence of growth factors. When growth factors were absent, keratinocytes likewise showed no preferential attachment to a given matrix component, but demonstrated enhanced thymidine incorporation when apposed to type IV collagen or fibronectin in comparison with tissue culture plastic or laminin. In the absence of epidermal growth factor (EGF) and bovine pituitary extract (BPE), increased spreading on type IV collagen and fibronectin was associated with enhanced incorporation of thymidine. In agreement with the thymidine incorporation results, when keratinocytes were cultured for 7 d, cell numbers were increased in cultures plated on type IV collagen only if growth factors were excluded from the medium. When attachment of cells to substrata with or without growth factors was compared, either EGF or BPE enhanced attachment to all of the substrata tested. It is concluded that under suboptimal growth conditions extracellular matrix components can modulate keratinocyte growth. Also, under these conditions, spreading, but not attachment, correlates with growth potential.

Desmoplakin I and desmoplakin II. Purification and characterization

Desmoplakins I and II (DP1 and DP2), major cytoskeletal structural proteins concentrated in desmosomes, have been purified in milligram quantities from keratomed pig tongue epithelium. DP1 and DP2 extracted from purified desmosomes in 4 M urea were chromatographed on DEAE-cellulose and remained soluble after removal of urea during subsequent chromatography. The two proteins differed by only about 15% in molecular weight (Mr = 285,000 for DP1 and 225,000 for DP2 on sodium dodecyl sulfate-polyacrylamide gels) were found to have similar Svedberg constants, 6.7 S (DP1) and 6.4 S (DP2); nevertheless, separation was readily achieved by gel filtration, since DP1 has a Stokes radius (Rs) of 164 nm, but DP2 has a Rs = 90 nm. Calculated molecular mass was 462,000 daltons for DP1 and 242,000 daltons for DP2, suggesting that DP1 may be a dimer in solution and DP2 a monomer. Cross-linking by disuccinimidyl suberate of 125I-labeled DP1 or DP2 at nanomolar concentrations confirmed that DP1 is a dimer by doubling of its apparent Mr on sodium dodecyl sulfate gels and indicated that DP2, which failed to become cross-linked, is a monomer. DP1 in the presence of 8 M urea could not be cross-linked, indicating that urea dissociated the dimers. Calculated frictional ratios (f/f0 = 3 for DP1 and 2 for DP2) indicate that both proteins are highly asymmetric. Rotary shadowing of DP1 demonstrated flexible dumbbell-like extended shapes with a maximal length of about 180 nm with a central rod and coiled or folded end domains. DP2 showed variable extended shapes of maximal length of 78-93 nm. The increased length and Rs of desmoplakin I is probably accounted for by formation of tail-to-tail dimers. Two-dimensional peptide maps and amino acid analysis showed very similar profiles for the two proteins. Purified keratin filaments failed to bind DP1 or DP2, and prekeratins polymerized in vitro and sedimented failed to remove desmoplakins, suggesting that desmoplakins do not bind keratins directly. These studies provide a basis for functional and detailed structural studies with purified native desmosomal proteins.

Placental keratinocyte growth factor: partial purification and comparison with epidermal growth factor

A water-soluble extract of term human placenta, which was previously shown to promote proliferative growth of human keratinocytes in defined medium, enhanced both cellular attachment and proliferative growth. We have partially purified the activity which enhanced cell growth and examined its action in keratinocytes. Activity was precipitated from the crude extract by (NH4)2SO4 between 33 and 60% saturation and chromatographed by gel filtration. The activity did not bind to heparin-Sepharose at low ionic strength but was adsorbed to DEAE-cellulose from which it was eluted with NaCl and then passed over phenyl-HPLC to remove bovine serum albumin previously added to protect the activity. The active fraction was applied to gel exclusion HPLC in the presence of 0.02% octyl-beta-D-glucopyranoside, which yielded an apparent Mr 35,000 for the factor. Purification was approximately 200-fold with approximately 4% recovery. The factor appears to be a protein, since activity is destroyed by trypsin. Autoradiography of cultures treated with the placental factor or epidermal growth factor (EGF) revealed that approximately 50% of cells were labeled after treatment with either growth factor compared to 9% in control cultures after a [3H]thymidine pulse. Protein synthesis was increased by about 50% 42 h after treatment with either agent, consistent with a 50% increase in nuclear labeling. Cell number was increased fivefold after 6 days in the presence of the partially purified factor, whereas EGF increased cell number eightfold. Stimulation of [3H]thymidine incorporation by the partially purified factor, in contrast, was about twice that produced by EGF, indicating that thymidine incorporation is preferentially stimulated by the placental factor and does not correlate well with other parameters of proliferative growth. The placental keratinocyte growth factor is a unique factor with a novel effect on incorporation of thymidine into DNA.

Constitutive production of procollagenase and tissue inhibitor of metalloproteinases by human keratinocytes in culture

Production of procollagenase and tissue inhibitor of metalloproteinases was demonstrated in human keratinocyte cultures. The two proteins were immunoprecipitated from keratinocyte-conditioned medium with antibodies to human dermal fibroblast collagenase and tissue inhibitor of metalloproteinases and quantitated with enzyme-linked immunosorbent assays. Treatment of the keratinocytes with the phorbol ester, 12-0-tetradecanoylphorbol-13-acetate, produced a six to 34-fold increase in procollagenase synthesis and secretion but only a threefold increase in the production of tissue inhibitor of metalloproteinases. Collagenase and tissue inhibitor of metalloproteinases mRNAs were present in normal keratinocytes, were the same size as their fibroblast counterparts, and both increased in response to treatment with 12-0-tetradecanoylphorbol-13-acetate. These data suggest that remodeling of type I collagen may be an important function of human keratinocytes in vivo.

Laminin inhibits human keratinocyte migration

A quantitative migration assay for human keratinocytes was developed to assess the influence of extracellular matrix molecules on cell motility independently from their effect on cell proliferation. Fibronectin and collagen types I and IV markedly promoted keratinocyte migration, but albumin, type V collagen, and heparan sulfate proteoglycan had little effect. In contrast, laminin inhibited keratinocyte motility and dramatically reduced type IV collagen-induced migration in a concentration-dependent manner. Laminin was not toxic, since it had no apparent effect on morphology, growth, or ability of cells to be passaged. Laminin, a major component of the lamina lucida, may inhibit motility of keratinocytes in vivo. Absence of contact with laminin, which accompanies wounding, may facilitate motility and healing in the epidermis.

Burn wounds resurfaced by cultured epidermal autografts show abnormal reconstitution of anchoring fibrils

We studied epidermal autografts placed on four severely burned patients. All of the patients experienced skin fragility in the autograft sites, and three of the four patients reported spontaneous blisters. Epidermal-dermal adherence was objectively examined in one patient by comparing suction blistering times in the autograft and in a parallel, control, unburned site. Blisters formed in the autograft at 17 minutes, and the cleavage plane of the blister was below the lamina densa of the basement membrane. In contrast, the normal skin blistered at 65 minutes and had a superficial cleavage plane, above the basal lamina. In all four patients, the reconstituted basement membrane zone beneath the autografts was incomplete and lacked type IV (basement membrane) collagen 7-S sites and anchoring fibrils. We conclude that skin fragility, apparent as late as seven months after transplantation, may result from defective anchoring fibrils.

Stimulation of growth of keratinocytes by basic fibroblast growth factor

Numerous heparin-binding growth factors active in different types of cells have recently been shown to belong to the family of fibroblast growth factors. Because these factors are active in some types of epithelial cells, we tested the activity of basic fibroblast growth factor (bFGF) from bovine brain in human keratinocyte cultures. bFGF stimulated thymidine incorporation and cellular proliferation in these cultures with half-maximal activity at approximately 60 pg/ml (4 X 10(-12) M). Stimulation of thymidine incorporation was associated with increased nuclear labeling after 22 h in the presence of bFGF under the same conditions used in the thymidine incorporation assay. bFGF was nearly as effective as epidermal growth factor (EGF) in stimulating keratinocyte growth and substantially less effective than crude placental extract, and was not additive with EGF in stimulating thymidine incorporation or proliferation of cells. The findings indicate that bFGF is a potent growth factor for keratinocytes.

Human dermal fibroblasts synthesize laminin

Laminin, a glycoprotein of approximately 900,000 daltons, is a major component of the basement membrane that separates the epidermis from dermis in human skin. Previous studies have shown that keratinocytes and other epithelial cells synthesize laminin and utilize it for attachment to other extracellular matrices such as heparan sulfate proteoglycan and basement membrane collagen. The relationships between phenotypically normal mesenchymal cells and laminin have been much less emphasized in the literature. In this study, we have used antibodies that specifically label the A and B chains of laminin (but not fibronectin or other unrelated proteins) by Western blot analysis to immunoprecipitate biosynthetically derived laminin from [35S] methionine labeled cultures of neonatal and adult human skin fibroblasts. To be sure that the precipitated bands were laminin and not fibronectin, which has a molecular size very close to that of the laminin B chains, experiments were performed in which fibronectin was removed from the radiolabeled proteins by first immunoprecipitating with antifibronectin antibody and then sequentially immunoprecipitating laminin from the fibronectin-depleted supernates with antilaminin antibody. These experiments definitively demonstrate that human dermal fibroblasts synthesize and secrete laminin.

Stimulation of thymidine incorporation in keratinocytes by insulin, epidermal growth factor, and placental extract: comparison with cell number to assess growth

The results of a thymidine incorporation assay were compared with direct measurement of cell number in assessment of proliferative growth of human keratinocytes in monolayer culture. Keratinocytes were cultured in supplemented MCDB 153 medium in 0.1 mM Ca2+, and plated in 24-well trays. The ability of insulin, placental extract, and epidermal growth factor to enhance growth and thymidine incorporation were compared. Autoradiography was performed to determine the percentage of cells with labeled nuclei. Epidermal growth factor increased thymidine incorporation under the conditions of the assay, and placental extract increased incorporation by up to 50-fold, since the control cells plated in the absence of epidermal growth factor and other growth factors survived but proliferated minimally. Both cell number and thymidine incorporation showed similar concentration dependence upon insulin and placental extract. If placental extract was added to cells plated 28 h earlier, incorporation was maximal after 17 h in the presence of the extract. If cells were plated in the presence of the extract, 85% of nuclei were shown by autoradiography to be labeled after 23 h, but only 24% of nuclei were labeled in the absence of the extract. A plating density of 10(4) cells/2-cm2 well was optimal. The assay permits rapid identification of growth-promoting fractions without prolonged growth periods, and is a valid indicator of these agents in keratinocyte cultures.

Calcium-induced assembly of adherens junctions in keratinocytes

Extracellular calcium concentration has been shown to control the stratification of cultured keratinocytes, presumably by regulation of formation of desmosomes. Previous studies have shown that keratinocytes cultured in medium containing 0.1 mM Ca++ form loose colonies without desmosomes. If the Ca++ is raised to 1 mM, desmosomes are assembled and the distribution of keratin filaments is altered. We have examined the disposition of vinculin and actin in keratinocytes under similar conditions. Using immunofluorescence microscopy we show that raising [Ca++] in the medium dramatically alters the distribution of vinculin and actin and results in the formation of adherens-type junctions within 15 min after switching to high calcium medium. Borders of cells at the edge of colonies, which are not proximal to other cells, are not affected, while cells in the interior of the colony form junctions around their periphery. Attachment plaques in keratinocytes grown in low calcium medium are located at the ventral plane of the cell, but junctions formed after switching to high calcium are not, as demonstrated by interference reflection microscopy. In cells colabeled with antibodies against vinculin and desmoplakin, vinculin-containing adherens junctions were visible before desmosomal junctions when cells were switched to high calcium. Although newly formed vinculin-containing structures in high calcium cells, like desmosomes, colocalize with phase-dense structures, superimposition of video fluorescence images using digitized fluorescence microscopy indicates that adherens junctions and desmosomes are discrete structures. Adherens junctions, like desmosomes, may play an essential role in controlling stratification of keratinocytes.

Specific affinity between fibronectin and the epidermolysis bullosa acquisita antigen

Autoantibodies in the skin and sera of patients with epidermolysis bullosa acquisita bind to a large matrix molecule within the lamina densa region of skin basement membrane. At the site of these immune complexes, the epidermis separates from the dermis, which creates a subepidermal blister just below the lamina densa. The target molecule for the autoantibodies is in close apposition to fibronectin, a major extracellular matrix molecule that is abundant in the upper dermis of skin. In this report, we show specific affinity between fibronectin and the 290,000-D chain of the epidermolysis bullosa acquisita antigen, and that this affinity is mediated by the gelatin/collagen-binding domain of fibronectin (Mr = 60,000). Since blistering in epidermolysis bullosa acquisita often occurs in the absence of clinical and histological inflammation, a direct interruption in the fibronectin-epidermolysis bullosa acquisita antigen bond may be involved in the pathogenesis of epidermal-dermal disadherence that occurs in this bullous disease.

Production of fibronectin by epithelium in a skin equivalent

Although human keratinocytes in vitro have been shown to produce fibronectin, whether keratinocytes can contribute fibronectin to the dermal-epidermal junction or wound matrix is unknown. In order to approach this problem experimentally, we used the "skin equivalent" model composed of a native collagen gel populated with cultured fibroblasts and covered by cultured keratinocytes. By using bovine fibroblasts to populate the gel, fetal bovine serum in the culture medium, and human keratinocytes to form the epithelium, we were able to be certain that any human fibronectin produced in the culture was synthesized by the keratinocytes. A monoclonal antibody to fibronectin was found to recognize human but not bovine fibronectin. When the skin equivalent was stained by indirect immunofluorescence with antifibronectin, fibronectin was visible as an intensely staining band at the dermal-epidermal junction. In sections in which the dermis and epidermis had separated, the staining was usually limited to the dermal aspect of the skin equivalent. The results indicate that epithelium can contribute fibronectin to the dermal-epidermal junction and suggest that dermal staining in skin sections may originate from the epidermis. Since the developing skin equivalent has a rapidly growing epithelium and simulates a healing wound, contribution of fibronectin by the epithelium, in addition to that possibly contributed by serum and fibroblasts, may be of importance in wound healing.

Production of procollagenase by cultured human keratinocytes

Using a collagen film assay utilizing 14C-labeled type I collagen, we demonstrated that cultured human keratinocytes produced a procollagenase after treatment with the tumor-promoting phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA). Production of collagenase paralleled alterations in cellular morphology induced by TPA. When procollagenase was immunoprecipitated with antibody to human fibroblast collagenase and analyzed on sodium dodecyl sulfate-polyacrylamide gels, the zymogen was revealed as a 56- and 51-kDa doublet. The keratinocyte-derived collagenase was a neutral metalloprotease, required activation with trypsin for detection in the collagenase assay and produced the characteristic three-quarter and one-quarter length collagen cleavage products when incubated with type I collagen at 25 degrees C. The enzyme was inhibited by serum and cysteine and was largely unaffected by serine, thiol, and carboxyl protease inhibitors. Cycloheximide inhibited the TPA-induced production of collagenase, suggesting that the procollagenase was not stored preformed in the keratinocytes. Keratinocytes treated with a tumor-promoting analogue of TPA also produced collagenase, but cells treated with cytochalasin B, interleukin-1, or two non-tumor promoting phorbol esters did not. Keratinocyte-derived collagenase may play a role in wound healing and morphogenesis.

Reduced dose of bleomycin in the treatment of recalcitrant warts

The effectiveness of intralesional bleomycin (1 U/ml) in the treatment of warts refractory to conventional methods of treatment has been shown in well-controlled studies. We have now evaluated more dilute concentrations of bleomycin in the treatment of recalcitrant warts. Warts were assigned for therapy with intralesional bleomycin at a concentration of 0.25 U/ml, 0.5 U/ml, or 1 U/ml at 3-week intervals. If warts persisted after three injections or had recurred by 3 months' follow-up, treatment was considered a failure. Twenty-six patients whose warts had persisted after conventional treatment entered the study. Three patients had spontaneous regression of untreated warts during therapy and were not included in the results. Of seventy-nine warts treated with intralesional bleomycin, sixty-two (78%) were cured after one to three injections. Responding warts showed a hemorrhagic eschar even with the lower bleomycin concentrations and healed without complication. Almost all treated warts responded, although not all were cured. Treatment with bleomycin at 0.5 U/ml was as effective as treatment with 1 U/ml. Bleomycin at 0.25 U/ml is effective therapy but not enough warts were treated to permit a conclusion when compared with higher concentrations.

Epidermolysis bullosa acquisita antigen, a major cutaneous basement membrane component, is synthesized by human dermal fibroblasts and other cutaneous tissues

The epidermolysis bullosa acquisita (EBA) antigen is identified as 2 chains: a 290,000-dalton protein and a less prominent 145,000-dalton protein. The 290,000-dalton chain is synthesized by human keratinocytes in culture. In this study, we show that the 290,000-dalton chain is synthesized by human skin fibroblasts and cutaneous human tumors. In contrast, HT1080 cells, a human sarcoma cell line known to produce matrix molecules (such as laminin and type IV collagen), does not synthesize the EBA antigen. Further, the EBA antigen is absent from serum and blood components, placenta, amnion, lung, and the EHS tumor, a murine sarcoma that produces large amounts of laminin, type IV collagen, nidogen, entactin, and basement membrane proteoglycan but is present in cutaneous tumors of adnexal and epithelial origin. These data suggest that while the EBA antigen is synthesized by both human skin keratinocytes and fibroblasts and is therefore not specific for a primordial germ layer, it does appear to be specific for tissue containing a stratified squamous epithelium.

Epidermolysis bullosa acquisita antigen, a new major component of cutaneous basement membrane, is a glycoprotein with collagenous domains

The epidermolysis bullosa acquisita antigen is a major constituent of the basement membrane zone beneath stratified squamous epithelium. The antigen which is recognized in extracts of skin basement membrane by Western blot analysis with polyclonal or monoclonal antiepidermolysis bullosa acquisita antigen antibodies as 2 chains (a major chain of 290,000 and a minor chain of 145,000) has a native molecular weight over 800,000. Both epidermolysis bullosa acquisita antigen chains contain carbohydrate and the 290K chain is sensitive to collagenase.

Platelet-derived growth factor modulates epidermal growth factor receptors by a mechanism distinct from that of phorbol esters

Platelet-derived growth factor (PDGF) and phorbol 12-myristate 13-acetate (PMA) decrease high affinity binding of 125I-labeled epidermal growth factor (EGF) and potentiate mitogenesis in BALB/c 3T3 cells, and both have been shown to induce the phosphorylation of the EGF receptor at threonine residues. These similarities suggest that the actions of PDGF on EGF binding may be mediated by protein kinase C, the cellular effector of PMA. We show that in density-arrested BALB/c 3T3 cells PDGF and PMA induce a rapid, transient, cycloheximide-independent loss of EGF binding activity. As has been previously shown for PDGF, the ability of PMA to reduce EGF binding was enhanced by cholera toxin, a potent activator of adenylate cyclase. In contrast to PMA, however, PDGF induced a further reduction in EGF binding that was strictly dependent upon continued protein synthesis. Furthermore, PDGF effectively reduced EGF binding in cells refractory to PMA. Cells desensitized to PMA, presumably due to the loss of protein kinase C activity, also remained mitogenically responsive to PDGF. These data suggest that the mechanism by which PDGF modulates EGF binding differs from that of PMA and thus, at least in part, is independent of protein kinase C.

Keratinocyte growth-promoting activity from human placenta

Extracts of term human placenta were tested for enhancement of proliferative growth of primary cultures of human keratinocytes. Saline extracts or supernatants from homogenates were dialyzed extensively, lyophilized, and tested in subcultures of keratinocytes in MCDB 153 medium with 0.1 mM Ca++ containing only defined supplements (insulin, hydrocortisone, transferrin, ethanolamine, phosphoethanolamine). Cells plated in the absence of EGF at moderately high densities (1000-3000 cells per cm2) formed colonies and grew in the presence of placental extract at 25-500 micrograms/ml. Extracts of cord serum or maternal serum were inactive, suggesting that the activity is derived from placental tissue. The activity is not EGF, since the activity in the placental extract, unlike EGF, did not promote growth at low cell density, was synergistic with EGF under some conditions, and did not produce changes in colonial morphology which occurred in the presence of EGF. Unlike keratinocyte growth-promoting activity in bovine hypothalamic extract, the activity is non-dialyzable and is destroyed at 100 degrees C. Placental extract could not replace any of the defined components of the medium and is therefore distinct from them. The presence of activity in the placenta with distinctive properties suggests that this is a previously undescribed material with growth-promoting properties for epithelium.