Epidermal and dermal integration into sphere-templated porous poly(2-hydroxyethyl methacrylate) implants in mice.

Percutaneous medical devices remain susceptible to infection and failure. We hypothesize that healing of the skin into the percutaneous device will provide a seal, preventing bacterial attachment, biofilm formation, and subsequent device failure. Porous poly(2-hydroxyethyl methacrylate) [poly(HEMA)] with sphere-templated pores (40 microm) and interconnecting throats (16 microm) were implanted in normal C57BL/6 mice for 7, 14, and 28 days. Poly(HEMA) was either untreated, keeping the surface nonadhesive for cells and proteins, or modified with carbonyldiimidazole (CDI) or CDI reacted with laminin 332 to enhance adhesion. No clinical signs of infection were observed. Epidermal and dermal response within the poly(HEMA) pores was evaluated using light and transmission electron microscopy. Cells (keratinocytes, fibroblasts, endothelial cells, inflammatory cells) and basement membrane proteins (laminin 332, beta4 integrin, type VII collagen) could be demonstrated within the poly(HEMA) pores of all implants. Blood vessels and dermal collagen bundles were evident in all of the 14- and 28-day implants. Fibrous capsule formation and permigration were not observed. Sphere-templated polymers with 40 microm pores demonstrate an ability to recapitulate key elements of both the dermal and the epidermal layers of skin. Our morphological findings indicate that the implant model can be used to study the effects of biomaterial pore size, pore interconnect (throat) size, and surface treatments on cutaneous biointegration. Further, this model may be used for bacterial challenge studies.

Novel transglutaminase-1 mutations and genotype-phenotype investigations of 104 patients with autosomal recessive congenital ichthyosis in the USA.

BACKGROUND: Autosomal recessive congenital ichthyosis (ARCI) is a rare hereditary disorder of cornification. Mutations in the transglutaminase-1 (TGM1) gene, which encodes for the epidermal enzyme transglutaminase-1 (TGase-1), are one of the causes of ARCI. METHODS: The TGM1 mutation spectrum was characterised and genotype-phenotype correlations investigated in 104 patients with ARCI ascertained through the National Registry for Ichthyosis and Related Disorders in the USA. Methods: Germline mutations in TGM1 were identified in 55% (57/104) of patients with ARCI. Arginine residues in TGase-1 were mutated in 39% (22/57) of patients overall and 54% (20/37) of those with missense mutations. In total, 55% (12/22) of missense mutations were within CpG dinucleotides and 92% (11/12) of these mutations were C-->T or G-->A transitions. The genotype-phenotype investigation found that ARCI with TGM1 mutations was significantly associated with presence of collodion membrane at birth (p = 0.006), ectropion (p = 0.001), plate-like scales (p = 0.005) and alopecia (p = 0.001). Patients who had at least one mutation predicted to truncate TGase-1 were more likely to have more severe hypohidrosis (p = 0.001) and overheating (p = 0.0007) at onset of symptoms than were those with exclusively TGM1 missense mutations. A logistic model was developed, which predicted that individuals with collodion membrane, alopecia and/or eye problems are about four times more likely to have TGM1 mutations than patients without these findings. CONCLUSION: This is the largest investigation of patients with ARCI to date. It expands the TGM1 mutation spectrum and confirms that despite genetic and phenotypic heterogeneity in ARCI, TGM1 is the main causative gene for this disorder. The high frequency of mutated arginine codons in TGM1 may be due to the deamination of CpG dinucleotides.

Models for the histologic study of the skin interface with percutaneous biomaterials.

Percutaneous devices are critical for health care. Access to tissue, vessels and internal organs afforded by these devices provides the means to treat and monitor many diseases. Unfortunately, such access is not restricted, and infection may compromise the usefulness of the device and even the life of the patient. New biomaterials offer the possibility of maintaining internal access while limiting microbial access, but understanding of the cutaneous/biomaterial interface and models to study this area are limited. This paper focuses on models useful for studying the morphology and biology of the intersection of skin and percutaneous biomaterials. An organ culture and a mouse model are described that offer promising possibilities for improved understanding of this critical interface.

A mouse model to evaluate the interface between skin and a percutaneous device.

Percutaneous medical devices are integral in the management and treatment of disease. The space created between the skin and the device becomes a haven for bacterial invasion and biofilm formation and results in infection. We hypothesize that sealing this space via integration of the skin into the device will create a barrier against bacterial invasion. The purpose of this study was to develop an animal model in which the interaction between skin and biomaterials can be evaluated. Porous poly(2-hydroxyethyl methacrylate) [poly(HEMA)] rods were implanted for 7 days in the dorsal skin of C57 BL/6 mice. The porous poly(HEMA) rods were surface-modified with carbonyldiimidazole (CDI) or CDI plus laminin 5; unmodified rods served as control. Implant sites were sealed with 2-octyl cyanoacrylate; corn pads and adhesive dressings were tested for stabilization of implants. All rods remained intact for the duration of the study. There was histological evidence of both epidermal and dermal integration into all poly(HEMA) rods regardless of treatment. This in vivo model permits examination of the implant/skin interface and will be useful for future studies designed to facilitate skin cell attachment where percutaneous devices penetrate the skin.

Management of the ichthyoses.

The ichthyoses are a heterogeneous group of inherited scaling skin disorders that can also affect other organs. Management should be directed at both the skin and other sites. Skin therapy is not specific at this time, although new products may offer more directed therapy in the future. Moisturizers and keratolytics are the mainstay of topical therapy. Calcipotriene, retinoids, and for select types, anti-inflammatories such as topical steroids and calcineurin inhibitors have also been used. Systemic therapy is limited to the retinoids. Superinfection of the skin should be anticipated and treated. Pruritus can be disabling. Failure to sweat normally may result in heat intolerance. Eye care should seek to prevent corneal changes resulting from ectropion and more specific changes associated with specific disorders. Haring can be impaired by the accumulation of material in the external auditory canal. Severely affected children may require caloric supplementation to avoid growth retardation. Affected individuals and their family should be counseled about the long term outlook and the genetic nature of their disorder, and informed of FIRST, the Foundation for Ichthyosis and Related Skin Types, the lay foundation that offers support and information.

Regulated expression of human filaggrin in keratinocytes results in cytoskeletal disruption, loss of cell-cell adhesion, and cell cycle arrest.

Filaggrin is an intermediate filament (IF)-associated protein that aggregates keratin IFs in vitro and is thought to perform a similar function during the terminal differentiation of epidermal keratinocytes. To further explore the role of filaggrin in the cytoskeletal rearrangement that accompanies epidermal differentiation, we generated keratinocyte cell lines that express human filaggrin using a tetracycline-inducible promoter system. Filaggrin expression resulted in reduced keratinocyte proliferation and caused an alteration in cell cycle distribution consistent with a post-G1 phase arrest. Keratin filament distribution was disrupted in filaggrin-expressing lines, while the organization of actin microfilaments and microtubules was more mildly affected. Evidence for direct interaction of filaggrin and keratin IFs was seen by overlay assays of GFP-filaggrin with keratin proteins in vitro and by filamentous filaggrin distribution in cells with low levels of expression. Cells expressing moderate to high levels of filaggrin showed a rounded cell morphology, loss of cell-cell adhesion, and compacted cytoplasm. There was also partial or complete loss of the desmosomal proteins desmoplakin, plakoglobin, and desmogleins from cell-cell borders, while the distribution of the adherens junction protein E-cadherin was not affected. No alterations in keratin cytoskeleton, desmosomal protein distribution, or cell shape were observed in control cell lines expressing beta-galactosidase. Filaggrin altered the cell shape and disrupted the actin filament distribution in IF-deficient SW13 cells, demonstrating that filaggrin can affect cell morphology independent of the presence of a cytoplasmic IF network. These studies demonstrate that filaggrin, in addition to its known effects on IF organization, can affect the distribution of other cytoskeletal elements including actin microfilaments, which can occur in the absence of a cytoplasmic IF network. Further, filaggrin can disrupt the distribution of desmosome proteins, suggesting an additional role(s) for this protein in the cytoskeletal and desmosomal reorganization that occurs at the granular to cornified cell transition during terminal differentiation of epidermal keratinocytes.

Surgical anatomy of the nail unit.

Surgical procedures in the nail unit require intimate knowledge of the gross and microscopic anatomy of the distal digit in order to obtain accurate diagnostic information and achieve the desired results with minimal impact on appearance and function. This review of the surgical anatomy of the nail unit discusses normal anatomy with an emphasis on those aspects necessary to perform surgery with minimal residual impact.

Histopathology of the nail.

Patients are often very concerned about the diagnosis and treatment of an unsightly nail problem. Nail biopsy findings can enhance the accuracy of clinical diagnosis, just as skin biopsy is often crucial to the diagnosis of skin disease. In addition, nail biopsy may be necessary for the early detection of a malignant tumor. A skillfully performed adequate nail biopsy, handled and processed and interpreted properly, can be an important part of a dermatologist's armamentarium in providing excellent comprehensive patient care.

Loss of normal profilaggrin and filaggrin in flaky tail (ft/ft) mice: an animal model for the filaggrin-deficient skin disease ichthyosis vulgaris.

Flaky tail (gene symbol ft) is an autosomal recessive mutation in mice that results in a dry, flaky skin, and annular tail and paw constrictions in the neonatal period. Previous studies demonstrated that the ft mutation maps to the central region of mouse chromosome 3, in the vicinity of the epidermal differentiation complex, a gene locus that includes many nonkeratin genes expressed in epidermis. In this study we report a detailed characterization of the flaky tail mouse. Affected homozygous ft/ft mice exhibit large, disorganized scales on tail and paw skin, marked attenuation of the epidermal granular layer, mild acanthosis, and orthokeratotic hyperkeratosis. Biochemical analysis demonstrated that ft/ft mice lacked normal high molecular profilaggrin (approximately 500 kDa), and instead expressed a lower molecular weight form of profilaggrin (220 kDa) that is not proteolytically processed to profilaggrin intermediates or filaggrin. Mutant mice lacked the large, irregular F-type keratohyalin granules that contain profilaggrin, and filaggrin was absent from the cornified layers of ft/ft epidermis. The expression of epidermal keratins was unchanged, whereas the cornified envelope proteins involucrin and loricrin were increased in ft/ft epidermis. Cultured ft/ft keratinocytes also synthesized reduced amounts of profilaggrin mRNA and protein, demonstrating that the defect in profilaggrin expression is intrinsic to epidermal cells. These findings demonstrate that flaky tail mice express an abnormal profilaggrin polypeptide that does not form normal keratohyalin F-granules and is not proteolytically processed to filaggrin. We propose that the absence of filaggrin, and in particular the hygroscopic, filaggrin-derived amino acids that are thought to function in epidermal hydration, underlies the dry, scaly skin characteristic of ft/ft mice. This animal model provides a tool for understanding the role of filaggrin in normal epidermal function and may provide insight into the molecular basis of the filaggrin-deficient human skin disorder ichthyosis vulgaris. J Invest Dermatol 115:1072-1081 2000

Ciclopirox nail lacquer topical solution 8% in the treatment of toenail onychomycosis.

BACKGROUND: Onychomycosis is a relatively common condition affecting toenails more than fingernails. It is caused predominantly by dermatophytes. Onychomycosis can cause pain and discomfort and has the potential to be a source of morbidity. OBJECTIVE: We evaluated the efficacy and safety of ciclopirox nail lacquer solution 8% used to treat onychomycosis of the toe in the United States and in centers worldwide. METHODS: Two identically designed, double-blind, vehicle controlled, parallel group multicenter studies were performed in the United States to evaluate the use of ciclopirox nail lacquer to treat mild to moderate toe onychomycosis caused by dermatophytes. In the first study, 223 patients were randomized to treatment (ciclopirox group: 112, vehicle group: 111), and in the second study, 237 subjects were randomized (ciclopirox group: 119, vehicle group: 118). Before randomization, patients were to have clinical features of onychomycosis in at least one great toe with positive light microscopic examination and a positive dermatophyte culture. The test material was applied daily for a period of 48 weeks to all toenails and affected fingernails, covering the entire nail plate and approximately 5 mm of surrounding skin. At baseline, subjects had between 20% to 65% area of target nail involved. Physician's assessments were carried out every 4 weeks, and mycologic evaluation and photographic planimetry using standardized photographs were performed every 12 weeks during the 48 weeks of treatment. In studies conducted outside the United States, patients were also to have clinical, microscopic, and culture evidence of onychomycosis. However, these studies included some patients infected with nondermatophyte organisms (eg, Candida species), and the area of nail involvement was generally greater than observed in the US studies. Treatment regimens also varied in the non-US studies with lacquer applications that were sometimes less frequent than the once daily treatment used in the US studies (eg, alternate day or twice weekly). In addition, the typical duration of treatment was 6 months in the non-US studies as compared with 48 weeks in the United States. Outcome measures were similar to those used in the US trials, although a non-photographic planimetric method was used to quantify disease extent. RESULTS: Data from the pivotal US trials have demonstrated that ciclopirox nail lacquer 8% topical solution is significantly more effective than placebo in the treatment of onychomycosis caused by Trichophyton rubrum, and of mild to moderate toe onychomycosis without lunula involvement. At the end of the 48-week treatment period, the mycologic cure rate (negative culture and negative light microscopy) in study I was 29% vs 11% in the ciclopirox and vehicle groups, respectively. Similarly, the mycologic cure rate for study II was 36% vs 9%, respectively. In the non-US studies, the mycologic cure rates ranged from 46.7% to 85.7%. In addition, ciclopirox nail lacquer has demonstrated a broad spectrum of activity with efficacy against Candida species and some nondermatophytes in non-US studies. Ciclopirox nail lacquer is considered extremely safe regarding causally related treatment emergent adverse-effects (TEAEs), with most TFAEs transient and localized to the site of action (eg, erythema and application site reaction). In the US studies, TFAEs were generally mild and cleared while the patient continued to use the nail lacquer. CONCLUSIONS: Studies conducted worldwide demonstrate the efficacy of ciclopirox nail lacquer for the treatment of finger and toe onychomycosis. Both controlled and open-label studies confirm the excellent safety profile of this topical therapy. Thus, the nail lacquer provides a treatment choice with a favorable benefit-to-risk ratio. With its novel mechanism of action and its topical route of administration, ciclopirox nail lacquer offers an innovative approach to the treatment of this often difficult-to-manage disease

A large-scale North American study of fungal isolates from nails: the frequency of onychomycosis, fungal distribution, and antifungal susceptibility patterns.

BACKGROUND: Onychomycosis, a fungal infection of the nail bed, is responsible for up to 50% of nail disorders. Although several surveys have been conducted in different parts of the world, there have been no multicenter epidemiologic surveys of onychomycosis in North America. OBJECTIVE: A 12-center study was undertaken to (1) determine the frequency of onychomycosis, (2) identify organisms recovered from the nails, and (3) determine the antifungal susceptibility of isolates. METHODS: A total of 1832 subjects participated in this study and completed a comprehensive questionnaire, and nail clippings were collected for potassium hydroxide examination and culturing. RESULTS: The frequency of onychomycosis, as defined by the presence of septate hyphae on direct microscopy and/or the recovery of a dermatophyte, was found to be 13.8%. In general, the dermatophyte isolates were susceptible to the antifungals tested. CONCLUSION: Because of the limited number of large-scale studies, the baseline incidence is not firmly established. However, the higher frequency of onychomycosis in this study may confirm the suspected increase in incidence of disease in North America.

Inducible expression of filaggrin increases keratinocyte susceptibility to apoptotic cell death.

Filaggrin is an intermediate filament associated protein that aids the packing of keratin filaments during terminal differentiation of keratinocytes. Premature aggregation of keratin filaments is prevented by filaggrin expression as the inactive precursor, profilaggrin, which is localized in keratohyalin granules in vivo. We have previously shown that filaggrin constructs, when transiently transfected into epithelial cells, lead to a collapsed keratin cytoskeletal network and dysmorphic nuclei with features of apoptosis. The apparent transfection rate is low with filaggrin constructs, supporting their disruptive role but hindering further study. To bypass this problem, we generated stable keratinocyte cell lines that express mature human filaggrin using a tetracycline-inducible promoter system. We found that cell lines expressing filaggrin, but not control cell lines, exhibited increased sensitivity to multiple apoptotic stimuli as measured by morphologic and biochemical criteria. None of the cell lines showed an increase in endogenous expression of filaggrin in response to the same stimuli. Filaggrin expression alone was insufficient to induce apoptosis in these keratinocyte cell lines. We conclude that filaggrin, due to its keratin binding ability, primes cells for apoptosis. Because filaggrin is expressed at a level of the epidermis where keratinocytes are in transition between the nucleated granular and the anucleate cornified layers, we hypothesize that filaggrin aids in the terminal differentiation process by facilitating apoptotic machinery.

The calcium-activated neutral protease calpain I is present in normal foetal skin and is decreased in neonatal harlequin ichthyosis.

Calcium concentration is a critical factor for epidermal differentiation and is implicated in the expression and post-translational modification of numerous proteins in suprabasal cells of the epidermis. Calpains (calcium-activated neutral proteases) are believed to participate in signal transduction via highly regulated cytoplasmic protease activity. Here we investigate the expression of calpain I in normal human skin development and in neonatal harlequin ichthyosis (HI), a disorder of altered epidermal differentiation, especially the transition from the granular to the fully differentiated cornified layer. Calpain I was detected in developing foetal epidermis at 54 days estimated gestational age in the basal layer and the periderm of the developing foetal epidermis. By 125 days, calpain I was also detected in the granular layer. This pattern was maintained in newborn skin, but expression was significantly weaker in HI biopsies (n = 7). Reduced expression of calpain was specific to HI and was not observed in other skin diseases. Calpain was also normally expressed in the outer root sheath of hair follicles, in sebaceous glands and in sweat ducts and glands. Immunoblots of epidermal and keratinocyte extracts showed that the 78-kDa and 76-kDa active forms were generated via limited proteolysis of the 80-kDa inactive subunit; however, all forms were diminished in HI, consistent with findings in tissue sections. Our results show that calpain is present throughout the epidermis and is expressed from the early stages of development. These findings implicate calcium-mediated signalling events in the alteration of differentiation that occurs in HI.

Role of keratinocyte injury in adherence of Streptococcus pyogenes.

Keratinocytes injured acutely by UVB light or lipopolysaccharide were used to test the hypothesis that keratinocyte injury promotes bacterial adherence and the development of group A streptococcal skin infections. Injury did not affect adherence to undifferentiated and differentiated keratinocytes, but keratinocyte differentiation promoted adherence four- to fivefold.

Tumor necrosis factor-alpha and interleukin-1alpha decrease the adherence of Streptococcus pyogenes to cultured keratinocytes.

We hypothesized that the primary epidermal cytokines, tumor necrosis factor (TNF)-alpha and interleukin (IL)-1alpha, which are produced after skin injury, modulate bacterial adherence and the initiation of group A streptococcal skin infections. Streptococcus pyogenes binds preferentially to highly differentiated keratinocytes in vitro, simulating the superficial human skin infection, impetigo, and providing a model system for testing this hypothesis. Exposure of keratinocytes to 10 ng/mL TNF-alpha for 20 h decreased adherence to undifferentiated and differentiated keratinocytes by 33% and 38%, respectively. Treatment with 1 ng/mL IL-1alpha decreased adherence to undifferentiated and differentiated keratinocytes by 23% and 18%, respectively. Exposure to both cytokines simultaneously produced an additive 50% reduction in adherence. These data suggest that TNF-alpha and IL-1alpha may play a role in cutaneous host defense by impeding streptococcal adherence and decreasing its ability to form a nidus of infection in the skin.

The impact of onychomycosis on quality of life: development of an international onychomycosis-specific questionnaire to measure patient quality of life.

BACKGROUND: Onychomycosis is a widespread refractory disease deleteriously affecting quality of life via social stigma and disrupting daily activities. Many physicians perceive onychomycosis as a cosmetic rather than a medical problem. OBJECTIVE: Our purpose was to develop a questionnaire-based instrument to quantify the impact of onychomycosis on patients' quality of life. METHODS: The questionnaire was developed and validated in a multinational cross-sectional study. Completed questionnaires from 532 patients were analyzed: 284 toenail, 248 fingernail (onychomycosis or paronychia). RESULTS: The degree of quality of life impairment from onychomycosis varied by country studied, possibly reflecting cross-national health perception differences. Longer duration of disease, greater involvement of individual nails, and greater number of nails involved were associated with more serious adverse effects. Many physicians underestimated the associated degree of pain. CONCLUSION: The study confirms that onychomycosis physically and psychologically affects patients' lives. The questionnaire may be a valuable tool in evaluating the effect of therapeutic agents on quality of life of patients with onychomycosis.

Current and future nail research - areas ripe for study.

This discussion examines five common topics that affect nails adversely, onychomycosis, brittle nails, developmental nail disorders, chronic paronychia and onycholysis. What is known about these processes, what areas of research, old and new, might lead to improved understanding of the underlying basis of the problems and what prospects the future might hold are considered.