E2 represses the late gene promoter of human papillomavirus type 8 at high concentrations by interfering with cellular factors

The late gene promoter P7535 of the epidermodysplasia verruciformis-associated human papillomavirus type 8 (HPV8) is regulated by the viral E2 protein. Transfection experiments performed with the human skin keratinocyte cell line RTS3b and P7535 reporter plasmids revealed transactivation at low amounts and a repression of basal promoter activity at high amounts of E2 expression vector. This repression was promoter specific and correlated with the amount of transiently expressed E2 protein. Mutational analyses revealed that the negative regulation of P7535 activity is mediated by the low-affinity E2 binding site P2, which is separated by one nucleotide from the P7535 TATA box. Biochemical and genetic analyses suggested that repression is due to a displacement of the TATA-box binding protein by E2 and an interference of E2 with promoter-activating cellular factors that specifically recognize the P2 sequence. The high conservation of the P2 sequence among several papillomaviruses (epidermodysplasia verruciformis-associated HPVs, HPV1, cottontail rabbit papillomavirus, and bovine papillomavirus type 1) in the vicinity of the late gene promoter cap site suggests that an interplay of E2 and cellular factors at this sequence element is important for the expression of structural proteins.

Keratin expression in discoid lupus erythematosus

21 lesions from 16 patients with discoid lupus erythematosus (DLE) were examined immunohistologically using monoclonal antibodies to keratins (K). Markers of basal epithelial cells (the keratin conformation specific basal markers LH6 and LH8), differentiating keratinocytes (K1 and K10), hyperproliferating keratinocytes (K16) and panepidermal keratin (K14), were used. A monoclonal antibody to type VII collagen was used as a guide to the state of the basement membrane zone (BMZ). Keratin distribution in DLE differed from controls. Suprabasal cells were labelled by LH6 in 95% of specimens (19/20) and LH8 in 79% (15/19) in contrast to the basal distribution in normal skin. Reduction of suprabasal LL017 (K1) expression was seen in 59% (10/17) of lesions. An increase of LL025 (K16) expression was seen in 33% (5/15) of specimens. Where LL025 (K16) expression was increased, LL017 (K1) expression was reduced in 80% (4/5). Dermal colloid bodies expressed both basal and suprabasal keratins and were present at sites of maximal basement membrane disruption. These findings are consistent with a model of DLE in which there is an increase in the proliferative basal compartment. This compartment and the associated BMZ suffer fragmentation and loss of colloid bodies to the dermis which express a range of keratins not uniformly associated with basal keratinocytes.

Epidermal differentiation and dermal changes in healing following treatment of surgical wounds with sheets of cultured allogeneic keratinocytes

AIMS

To establish the structural changes that occur in deep surgical wounds engrafted with allogeneic sheets, their time course and inter-relation.

METHODS

Deep surgical wounds following shave excision of tattoos (down to deep dermis/subcutaneous fat) were treated with sheets of sex mismatched allogeneic keratinocytes in 19 patients and then biopsied weekly until wound healing was complete. More superficial surgical wounds--that is, 20 standard skin graft donor sites, were biopsied at seven to 10 days (all healed) following application of keratinocyte allografts. All biopsy specimens were examined with a large panel of monoclonal antibodies to keratins, envelope proteins, basement membrane components, and to extracellular matrix components.

RESULTS

The hyperproliferative keratin pair K6/16 was expressed in all wounds, for up to six weeks in keratinocyte grafted deep wounds, and up to six months in split thickness skin grafted wounds.

CONCLUSIONS

Keratins 6 and 16 have not been detected in normal skin, although the relevant mRNA has. This raises the possibility of regulation at a post-transcriptional level allowing a rapid response to injury with cytoskeletal changes that may aid cell migration. This keratin pair offers the most sensitive marker for altered epidermis following wounding.

Immortalisation of human urothelial cells

A cell line derived from the urothelium lining the ureter of a 12-year-old girl was immortalised using a temperature-sensitive SV40 large T-antigen gene construct, and designated UROtsa. Following immortalisation, UROtsa cells expressed SV40 large T-antigen, but did not acquire characteristics of neoplastic transformation, including growth in soft agar or the development of tumours in nude mice. Metaphase spreads had a normal chromosomal appearance and number. UROtsa cells remained permissive for cell growth at 39 degrees C, indicating that they did not retain temperature sensitivity. UROtsa provides an in vitro model of "normal" urothelium.

Temperature sensitivity of the keratin cytoskeleton and delayed spreading of keratinocyte lines derived from EBS patients

Point mutations in the keratin intermediate filament genes for keratin 5 or keratin 14 are known to cause hereditary skin blistering disorders such as epidermolysis bullosa simplex, in which epidermal keratinocytes are extremely fragile and the skin blisters on mild trauma. We show that in 2 phenotypically diverse cases of epidermolysis bullosa simplex, the keratin mutations result in a thermoinstability of the intermediate filament cytoskeleton which can be reproducibly demonstrated even in the presence of tissue culture-induced keratins and in conditions where filament fragility is not otherwise obvious. SV40-T antigen and HPV16 (E6--E7) immortalised keratinocyte cell lines were examined, established from control and epidermolysis bullosa simplex-affected individuals with either severe (Dowling-Meara) or mild (Weber-Cockayne) forms of the disease. In standard tissue culture conditions no significant and consistent abnormality of the keratin cytoskeleton could be demonstrated. However after thermal stress a reduced stability of the keratin filaments was demonstrable in the epidermolysis bullosa simplex cell lines, with filaments breaking into aggregates similar to those seen in skin from EBS patients. These aggregates were maximal at 15 minutes after heat shock and the filament network structure was substantially reversed by 60 minutes. Differences were also seen in the cells during respreading after replating: cells containing mutant keratins were slower to respread than controls and fine aggregates were seen at the cell margins in the Dowling-Meara derived cell line. Such delays in restoring the normal intermediate filament network after physiological processes involving cytoskeleton remodelling may render the cells vulnerable to cytolysis in vivo if physically challenged during this time window. The steady reduction in the mitotic index of the epidermis during the first few years of life could then explain the clinical improvement which is frequently observed in growing children.

Oral keratinocytes immortalized with the early region of human papillomavirus type 16 show elevated expression of interleukin 6, which acts as an autocrine growth factor for the derived T103C cell line

Interleukin 6 (IL-6) is a pleiotropic cytokine produced by cells in response to injurious stimuli including viral infections and UV light. Numerous human keratinocyte-derived lines overexpress IL-6 and have been shown to respond to IL-6 as a mitogen. In a survey of such lines, we discovered that two lines, SiHa and Caski, which harbor human papillomavirus (HPV) type 16 genomes, showed the highest levels of secretion. We have, therefore, asked whether immortalization of human keratinocytes with HPV 16 could result in elevated secretion of IL-6. Oral keratinocytes were transfected with a plasmid expressing the entire HPV type 16 early region under the control of the Moloney leukemia virus long terminal repeat promoter. Three immortal lines were derived and tested for their ability to secrete biologically active IL-6. These lines showed 2-, 3-, and 9-fold increases in detectable IL-6 when compared with parental strains of keratinocytes. Cells from one of these lines, T103C, showed a negative growth response to IL-6-neutralizing antisera, suggesting that the secreted IL-6 acted as an autocrine growth stimulator.

Keratins (K16 and K17) as markers of keratinocyte hyperproliferation in psoriasis in vivo and in vitro

Keratinocyte differentiation in psoriasis was examined using a panel of monospecific monoclonal antibodies to keratins (K), including two recently developed monoclonal antibodies raised to carboxy terminal peptides of K6 (LL020) and K16 (LL025). Keratinocytes from normal skin, untreated psoriatic plaques and non-lesional psoriatic skin, were cultured using multiple in vitro systems. Time-lapse cinephotography was used to measure the intermitotic time of normal and psoriatic keratinocytes in both low calcium-defined and serum-containing media. The intermitotic time did not differ significantly between psoriatic and normal keratinocytes. Keratin expression of psoriatic and normal keratinocytes in vitro was examined by both gel electrophoresis and immunocytochemistry. K6, K16 and K17 were detected suprabasally in all culture systems in vitro, but only in interfollicular psoriatic epidermis in vivo, and not in normal skin. Small subpopulations of keratinocytes expressed simple epithelial keratins K7, K8, K18 and K19 in cultures on plastic substrates, but these keratins were absent in skin equivalents of normal or psoriatic skin. No psoriasis-specific pattern of differentiation was found in vitro. As the K6 peptide antibody reacted with basal cells of normal skin, probably due to K5 cross-reactivity, K16 expression determined by LL025 was found to be the most sensitive indicator of the psoriatic state of differentiation, and this antibody is recommended for future work on psoriasis. K17 had a distinct pattern of tissue distribution in normal skin: K17, but not K16, was present in basal myoepithelial cells in sweat glands, and the deep outer root sheath, but K17 distribution paralleled that of K16 in suprabasal psoriatic epidermis. As keratins K6, K16 and K17 are expressed in keratinocyte hyperproliferation, when high levels of certain cytokines are also expressed, the role of growth factors and regulatory nuclear transcription factors in the control of K6, K16 and K17 expression in psoriasis requires further study, in order to provide insight into the relationship between proliferation and differentiation.

Genetic linkage studies in non-epidermolytic palmoplantar keratoderma: evidence for heterogeneity

The palmoplantar keratodermas (PPK) are a group of skin diseases characterized by thickening of the skin of the palms and soles due to abnormal keratinization. We have performed linkage analysis on families affected with three distinct forms of non-epidermolytic PPK (NEPPK): focal, diffuse and punctate. Genetic heterogeneity was demonstrated, with focal NEPPK linked to the region on chromosome 17 harbouring the type I keratin cluster, diffuse NEPPK linked to the region on chromosome 12 containing the type II keratin cluster, and in the punctate NEPPK pedigrees, linkage was excluded to both of these keratin clusters. This study provides evidence for genetic differences between these forms of NEPPK and also between NEPPK and epidermolytic PPK (EPPK) in which mutations in keratin 9 have been demonstrated.

Increased prevalence of dysplastic and malignant lip lesions in renal-transplant recipients

BACKGROUND

Renal-transplant recipients are known to have increased rates of skin cancer associated with exposure to the sun. Little is known, however, about the prevalence and histologic features of lesions of the lips in these patients, or about risk factors for such lesions.

METHODS

We examined the lips of 160 renal-transplant recipients (105 men and 55 women; mean [+/- SD] age, 48 +/- 13 years) and 160 normal subjects matched with the transplant recipients for age, sex, and skin type. The mean length of time between transplantation and the examination was 69 +/- 52 months; 58 percent of the recipients had received their grafts more than 60 months earlier.

RESULTS

Among the 160 renal-transplant recipients, 21 (13 percent) had leukoplakia; in 2 (1.2 percent) the leukoplakia contained squamous-cell carcinoma. In contrast, only one normal subject (0.6 percent) had leukoplakia. Histologically, 13 of the 21 leukoplakias (62 percent) in the renal-transplant recipients who underwent biopsy were dysplastic, and 2 (10 percent) contained squamous-cell carcinoma. Actinic change was evident in 91 percent of the dysplastic lesions but not in the nondysplastic lesions (P < 0.001). Exposure to the sun and smoking were risk factors for dysplastic and malignant lip lesions in the renal-transplant recipients (P < 0.001 and P = 0.003, respectively). Among these recipients, only men had dysplastic or malignant lip lesions (P = 0.006); lipstick was used frequently by 73 percent of the women. The clinical appearance of lip lesions did not predict the presence of dysplasia or cancer.

CONCLUSIONS

Renal-transplant recipients have an increased prevalence of leukoplakia, dysplasia, and cancer of the lip.

Altered laminin 5 expression due to mutations in the gene encoding the beta 3 chain (LAMB3) in generalized atrophic benign epidermolysis bullosa

The anchoring filament component laminin 5 (kalinin/nicein) is a candidate protein for mutations in some hereditary blistering skin disorders. In this study, laminin 5 expression was assessed in a family with generalized atrophic benign epidermolysis bullosa, a non-lethal variant of the junctional form of epidermolysis bullosa. Immunofluorescence microscopy of the skin basement-membrane zone with a monoclonal antibody (GB3) revealed reduced anti-laminin 5 staining compared to normal controls. The labeling, when examined by immunoelectron microscopy, was present within the lower lamina lucida, immediately below the plane of blister formation. Numerous hemidesmosomes and well-formed anchoring filaments were seen on transmission electron microscopy. Polymerase chain reaction amplification of genomic DNA encoding the beta 3 subunit (LAMB3) of laminin 5, heteroduplex analysis of the polymerase chain reaction products, and nucleotide sequencing of the heteroduplexes revealed two putative mutations within the LAMB3 gene; these consisted of a premature termination codon in exon 3 and a missense mutation in exon 7. Exons 3 and 7 encode part of domain VI of the laminin 5 beta 3 chain short arm. This globular domain of the protein has been postulated to have an important function in the interaction of laminin 5 with other structural components of the basement membrane zone, such as laminin 6 (K-laminin). Thus the mutations delineated in this family may have a critical pathogenetic significance in reducing adhesion between the epidermis and the dermis.

Ultrastructural changes resulting from keratin-9 gene mutations in two families with epidermolytic palmoplantar keratoderma

Palmoplantar keratoderma of Voerner type (or epidermolytic palmoplantar keratoderma) is an autosomal dominant inherited disorder of keratinization with histologic features of epidermolytic hyperkeratosis. We studied members of two large unrelated kindreds with epidermolytic palmoplantar keratoderma, and biopsy specimens of lesional palmar skin from both families confirmed the histologic changes of epidermolytic hyperkeratosis. Whorls of abnormally aggregated keratin filaments were seen ultrastructurally to be associated with signs of cellular disintegration in spinous and granular cells. Direct sequencing of genomic DNA samples obtained from several members of each family established the substitution of a highly conserved arginine by tryptophan (R162W) in the 1A region of the alpha-helical rod domain of keratin 9. This arginine residue in a highly conserved region of keratins 1 and 10 is affected by disruptive missense point mutations in many patients with bullous ichthyosiform erythroderma. An equivalent position in the sole and palm restricted keratin 9 appears to be the mutation hot spot in epidermolytic palmoplantar keratoderma. To date, R162W is the most prevalent genetic defect reported in this genodermatosis.

Regeneration pattern of blood vessels and nerves in cultured keratinocyte grafts assessed by confocal laser scanning microscopy

The aim of this study was to investigate the pattern of both neovascularization and reinnervation, and the relationship between the two processes, in keratodermal grafts, using confocal laser scanning microscopy, at different time points during the healing process. Keratodermal grafts were prepared in pigs by combining autologous dermis with cultured autologous keratinocytes. Immunohistochemistry was carried out on thick cryostat sections (100-150 microns), using antisera to the endothelial marker von Willebrand factor (vWf) and the pan-neuronal marker protein gene product 9.5 (PGP9.5). The results suggest that the neovascularization and reinnervation in the cultured keratodermal graft is almost complete at 6 weeks. Neovascularization precedes innervation, reaching the surface covered by the keratinocytes at 2 weeks, initially with a linear vascular pattern. From 3 weeks, there is a gradual arborization of the vessels to form a typical vascular plexus. The process of reinnervation is similar in pattern to that of neovascularization, although slower in developing a full network of fibres. In conclusion, the use of confocal microscopy allows the precise definition of complex patterns of neovascularization and nerve growth, which are not fully apparent when using conventional microscopy. Because angiogenesis occurs first, it probably plays a leading role in the survival of keratodermal grafts during wound healing. Indeed, new blood vessels form a pathway for the subsequent innervation process, and quickly reach the epidermal layer which, in turn, may play a key role in the tropism of both blood vessels and nerves.

Culturing skin in vitro for wound therapy

Current tissue-culture techniques enable keratinocytes from a small piece of skin to be grown into sheets of epithelium, or cultured keratinocyte grafts, that are suitable for treating wounds. Serial subculture enables rapid expansion of a cell population, such that grafts of a total area equivalent to that of the surface of an adult can be obtained from an initial skin biopsy of approximately 2 cm2 in under one month. In this article, the methods currently used for culturing keratinocytes, the search for a fully functional replacement for the dermal elements of skin, and the prospects for clinical development of these technologies in the near future are discussed.

Upregulation of integrin expression in benign vulvar warts

Benign anogenital warts demonstrate features both of hyperproliferation and of aberrant differentiation associated with human papillomavirus (HPV) infection. The expression of integrins has been examined in normal vulvar epithelium and benign vulvar warts to determine whether HPV infection is associated with changes in integrin expression, either during terminal differentiation or among the proliferating cell population. The expression of integrins in normal vulvar epithelium was similar to that seen in the epidermis, with little expression of alpha 1 and expression of alpha 2, alpha 3, and beta 1 at the periphery of basal cells. In vulvar wart epithelium, alpha 1 was not significantly expressed, but upregulation of alpha 2, alpha 3, and beta 1 was seen at the periphery of cells throughout the basal and spinous layers. In addition, alpha 2 staining was greater at foci along the basal layer of normal vulva, whilst such heterogeneity was not detected in wart sections. Expression of beta 4 and alpha V was confined to the basal and lateral aspects of normal basal cells, but expressed at the periphery of basal cells and to a lesser extent in epibasal and spinous layers of warts. The observed differences in integrin expression are consistent with those reported in other hyperproliferative epithelia.

Keratin expression in cutaneous lichen planus

The characteristic expression of keratins by keratinocytes is well documented. A typical 'hyperproliferative' profile of epidermal keratin expression occurs in psoriasis, wound healing and warts. This study analyses keratin expression in cutaneous lichen planus to determine abnormalities of differentiation occurring in this inflammatory disorder. Using a panel of monoclonal antibodies 28 samples (20 patients) were studied. The results showed that squamous differentiation was unaffected, with keratins K1 and K10 being expressed normally for the site sampled. The main abnormalities included extension of reactivity of the basal cell marker, LH8, into the suprabasal compartment. Keratin K17, usually restricted to adnexal structures, was variably expressed in the basal and suprabasal layers of the interfollicular epithelium of affected epidermis. Keratins K6 and K16, found suprabasally in hyperproliferative states, were detected both basally and suprabasally in all diseased samples. The keratin profile in lichen planus is analogous to the wound healing response. Suprabasal keratin K17 is found in psoriasis, wound healing and viral warts so the changes in keratin K17 may reflect hyperproliferative changes. It is likely that the changes in epidermal keratin expression are due to up-regulation of specific keratin genes by the production of cytokines and inflammatory mediators from the lymphocytic infiltrate typical of lichen planus.

Cutaneous warts and tumours in immunosuppressed patients

As increasing numbers of recipients of renal allografts survive long term, complications of prolonged immunosuppression have become apparent. Of particular concern are the high rates of non-melanoma skin cancer (NMSC) and carcinoma of the cervix, vulva and perineum.

A double-blind, placebo-controlled trial of continuous acyclovir therapy in recurrent erythema multiforme

Twenty patients who suffered from more than four attacks of erythema multiforme (EM) per year were enrolled in a 6-month double-blind, placebo-controlled trial of acyclovir 400 mg twice daily. Fifteen patients had disease precipitated by recurrent herpes simplex. In the acyclovir-treated group the median number of EM attacks during the treatment period was zero, compared with three in the placebo-treated group (P < 0.0005, Wilcoxon rank sum test). Seven of the 11 patients treated with continuous acyclovir did not have any attacks of EM while taking the drug, and one showed almost complete disease suppression. Following treatment with acyclovir, two patients went into complete remission, whereas all individuals in the placebo group continued to have attacks. In the acyclovir-treated group nine of the 11 patients had herpes simplex-precipitated disease. One of the two patients with idiopathic disease showed complete disease suppression while on acyclovir, lending support to the view that idiopathic recurrent EM may be related to subclinical herpetic infection. In this study, we have shown that continuous acyclovir therapy can completely suppress attacks of recurrent EM and, in some cases, may induce disease remission.

Nerve growth factor levels in cultured human skin cells: effect of gestation and viral transformation

Extracts of cultured human keratinocytes and fibroblasts were assayed for nerve growth factor-like immunoreactivity (NGF) by a specific enzyme-linked immunoabsorbant assay. NGF levels were higher in primary cultured keratinocytes than in freshly isolated keratinocytes or culture through multiple passages. Viral transformation of keratinocytes with the human papilloma virus (HPV16) significantly increased NGF levels, whilst transformation with the simian virus (SV40), which induces simple epithelial differentiation, reduced the concentration of NGF. Passaged epidermal keratinocytes contained more than twice as much NGF as did passaged fibroblasts. Oral keratinocytes and fibroblasts, and psoriatic fibroblasts, all from high turnover tissues, did not contain significantly different levels of NGF in culture than dermal keratinocytes or fibroblasts. Foetal fibroblasts contained five times as much NGF as did adult fibroblasts. These results suggest that basal keratinocytes are a major but not sole source of NGF in human skin, and that NGF may play a role in human skin development.

Skin cancer and warts in immunosuppressed renal transplant recipients

Non-melanoma skin cancer (NMSC) is increasingly recognised as a complication of long-term immunosuppression and has been particularly studied in renal transplant recipients (RTR). A population study of renal transplant recipients has been performed with analysis of those features contributing to a high rate of detection of NMSC, such that 40% patients with fair skin have NMSC 5 years after transplantation. 90% of the total patient population have warts 5 years after transplantation, many being atypical and in sun-exposed sites. Therefore, contributory factors in these patients include not only the global immunosuppression, ultraviolet radiation (UVR)-induced mutagenesis and photoimmunosuppression, but also the widespread presence of human papillomavirus (HPV) infection, including the unusual epidermodysplasia verruciformis (EV)-associated cutaneous oncogenic HPV.

Characteristics of the oral lesions in patients with cutaneous recurrent erythema multiforme

Erythema multiforme may be recurrent and the oral cavity is often affected. A series of 82 patients with unequivocal recurrent cutaneous erythema multiforme were examined to determine the incidence and nature of oral lesions. Seventy per cent of patients had oral lesions, comprising multiple, large, shallow, extremely painful and debilitating ulcers, which affected the entire oral mucosa in over 20%. The buccal mucosa and tongue were the most frequently affected sites in the remainder and the lips were affected in 13% of patients. Lesions generally lasted for 1-3 weeks. In over 60% of cases these attacks followed an episode of herpes simplex virus infection during the preceding fortnight. Recurrent attacks showed a different site distribution from the initial attacks, with a greater proportion having genital as well as skin and oral mucosal involvement. Detailed case histories of five patients are presented to illustrate the role of azathioprine in treating oral lesions and to document a familial case of recurrent erythema multiforme, with severe mucosal involvement.

Keratin expression in the normal anal canal

The pattern of epithelial keratin expression in the normal anal canal has not been extensively defined and is a necessary prerequisite to the interpretation of alterations in these intermediate filaments in pathological anal epithelial lesions. Thirty-five frozen tissue specimens of resected haemorrhoids were investigated immunohistologically for expression of 14 individual keratins (K) using a panel of 17 monoclonal antibodies. Perianal skin showed basal expression of keratinocyte Ks 5, 14 and 17, and suprabasal expression of keratinocyte Ks 14, 10, 1 and 16. Anal squamous epithelium showed persistent basal K5 and 17, basal and suprabasal K4, 13 and 16 positivity, with sporadic expression of K1 and 10. The expression of simple epithelial keratins in squamous epithelium adjacent to the anal transitional zone varied with basal expression of K7, K8, K18 and K19 and sporadic suprabasal expression of K7 and K19. The anal transitional zone (ATZ) expressed K19, as found in transitional epithelia elsewhere. The full thickness of epithelium was positive for the simple epithelial Ks 7, 8 18 and 19. Marked heterogeneity of keratinocyte keratin expression was seen. Basal layers expressed Ks 4, 13, 14 and 17 and variably K16, while suprabasal layers expressed Ks 4 and 13, 14 and 17 and variably K16, while suprabasal layers expressed Ks 4 and 13 and variably K14, 16 and 17. This anomalous expression of keratinocyte K4 and 13 has also been documented in transitional epithelium of the bladder. The anal glands and ducts showed a keratin distribution similar to the transition zone.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence and risk factors associated with leukoplakia, hairy leukoplakia, erythematous candidiasis, and gingival hyperplasia in renal transplant recipients

The aims of this study were to determine the prevalence of intraoral lesions in renal transplant recipients and to identify possible risk factors. The oral mucosa of 159 renal transplant recipients and 160 control patients was examined. The most common lesion in renal transplant recipients was cyclosporin-induced gingival hyperplasia (prevalence 22%) and patients with gingival hyperplasia were found to be taking significantly more cyclosporin-A than those without (p < 0.001). The prevalence of hairy leukoplakia and leukoplakia in renal transplant recipients was 11.3% and 10.7%, respectively, compared with 0% and 5.6% in the controls. Oral candidiasis was observed in 9.4% of renal transplant recipients compared with 2.5% of the controls; 3.8% of renal transplant recipients exhibited erythematous candidiasis, but this was not seen in the controls. Renal transplant recipients had a significantly increased risk of developing gingival hyperplasia (p < 0.0001), oral candidiasis (p < 0.0005), and two other conditions that have a well-established association with the immune suppression accompanying HIV infection, hairy leukoplakia (p < 0.0001) and erythematous candidiasis (p < 0.01).

A functional "knockout" of human keratin 14

The importance of keratins and other intermediate filaments in the maintenance of tissue structure is emphasized by the discovery that many hereditary skin-blistering diseases are caused by mutations in keratin genes. Here, we describe a situation in which keratin 14 (K14) is missing altogether in the epidermis: A homozygous 2-nucleotide deletion in exon I of the K14 gene causes premature termination of the mRNA transcripts upstream from the start of the rod domain and results in a K14 null phenotype. In this individual no keratin intermediate filaments are visible in basal epidermal cells, although filaments are present in the upper layers of the epidermis. No compensating keratin expression is detected in vivo, and K14 mRNA is down-regulated. The individual, diagnosed as Köbner (generalized) EBS, suffers from severe widespread keratinocyte fragility and blistering at many body sites, but although the phenotype is severe, it is not lethal. This K14-/- phenotype confirms that only one K14 gene is expressed in human epidermis and provides an important model system for examining the interdependence of different keratin filament systems and their associated structures in the skin.

Nuclear transcription factors: potential targets for new modes of intervention in skin disease

Many drugs already in use for the treatment of skin disease, including steroids, retinoids, vitamin D derivatives and cyclosporin (CyA), exert effects on gene transcription. In this review we briefly outline how these drugs work, before proceeding to a consideration of how new drugs acting on the transcription process might be used to influence skin disease.