Tenascin expression in hyperproliferative skin diseases

The expression of tenascin, a recently discovered extracellular matrix glycoprotein, was studied by immunohistochemistry in normal human skin and in a number of skin diseases with epidermal hyperproliferation such as psoriasis, basal cell carcinoma, Bowen's disease and solar keratosis. Tenascin expression in the upper dermis of normal skin was found to vary from almost absent to patchy along the basal membrane. Staining was continuous and intense around blood vessels, hair follicles and eccrine sweat ducts. In basal cell carcinoma a marked expression of tenascin was found in the tumour stroma, especially adjacent to the basal membrane surrounding the tumour cell nests. In Bowen's disease and solar keratosis, tenascin expression was found in the dermis next to the keratinocytes. In psoriasis the dermal papillae of clinically involved skin were intensely stained and a continuous band of tenascin was present in the upper dermis along the basal membrane. The distribution of tenascin differed from other known extracellular matrix components.     

Increased expression of tenascin C by keloids in vivo and in vitro

Tenascin C, undulin, collagen XIV and fibronectin are extracellular matrix glycoproteins with a partial DNA sequence homology. During embryogenesis, tenascin C is abundant in mesenchymal tissues but its distribution in human adult tissue is severely restricted. The levels of tenascin C expression are enhanced with skin inflammation, wound healing and hyperproliferative skin diseases and return to normal in normal scar tissue after wound contraction is completed. Undulin/collagen XIV is associated with collagen fibrils and fibronectin is present throughout the dermis in adult skin but it is produced by keloidal fibroblasts in an increased amount. In this study we investigated by immunohistochemistry the expression of the three extracellular matrix proteins in keloids and normal skin as well as in keloidal and normal fibroblasts in vitro. In keloids, increased tenascin C expression was observed especially in the reticular dermis associated with collagen fibrils sharply demarcating the limit of the lesion. In normal tissue, tenascin C was only expressed beneath the basal lamina and dermal-epidermal junction. Corresponding to the in vivo findings, tenascin C expression was increased in keloidal fibroblasts compared with normal fibroblasts in vitro (P < 0.003), whereas undulin/collagen XIV and fibronectin expression in keloids and keloidal fibroblasts was similar to that in normal tissue and normal fibroblasts, respectively. Therefore, tenascin C is a marker associated with keloids and we suggest that keloidal fibroblasts, once stimulated, continue to produce tenascin C independently from circulating factors.     

Alterations in distribution of tenascin, fibronectin and fibrinogen in vulval lichen sclerosus

BACKGROUND: The pathophysiology of lichen sclerosus remains uncertain. The clinical features, including increased fragility and scarring, and the histology suggest that significant reorganisation of the extracellular matrix is occurring. Tenascin, fibrinogen and fibronectin are extracellular matrix components that play a significant role in tissue remodelling, for example during wound repair. Aim: To examine the distribution of tenascin, fibrinogen and fibronectin in vulval lichen sclerosus. MATERIALS AND METHODS: Immunohistochemical staining was performed to study the distribution of tenascin, fibronectin and fibrinogen in 16 specimens of untreated vulval lichen sclerosus and 1 specimen of extragenital lichen sclerosus. Haematoxylin and eosin staining of the specimens was also performed to identify the position of the pale staining homogenous zone/zone of sclerosis and the inflammatory infiltrate below this. The control tissues studied included biopsies taken from the uninvolved thigh of 13 of the lichen sclerosus patients and 6 samples of normal vulva tissue obtained during gynaecological procedures from women of similar age to the lichen sclerosus women. RESULTS: All the lichen sclerosus specimens demonstrated increased immunostaining of tenascin in the upper dermis and comparing this with the haematoxylin and eosin staining this corresponded to the zone of sclerosis with relatively little tenascin staining associated with the inflammatory band. In 14 out of the 16 vulval lichen sclerosus specimens and the extragenital lichen sclerosus specimen fibrinogen immunostaining was increased in the upper dermis which corresponded--in haematoxylin and eosin staining --to the zone of sclerosis. There was also slightly increased fibrinogen staining in the mid dermis which corresponded to the inflammatory band. Fibronectin staining was reduced in the upper dermis of 12 of the vulval lichen sclerosus specimens and the extragenital lichen sclerosus specimen which corresponded to the zone of sclerosis. However, in 14 of the vulval lichen sclerosus specimens and the extragenital lichen sclerosus specimen, fibronectin was slightly increased in the mid and deeper dermis which corresponded to the zone of inflammatory cells and the area below this. There was also increased fibronectin staining around blood vessel walls both in the mid dermis and within the zone of sclerosis. CONCLUSION: The distribution of tenascin, fibrinogen and fibronectin is altered in lichen sclerosus and the alteration in these extracellular matrix components may be relevant to the initiation of scarring in lichen sclerosus and the associated increased skin fragility.     

Activity of type 1 5α–reductase is greater in the follicular infrainfundibulum compared with the epidermis

The enzyme 5α–reductase converts testosterone (T) to dihydrotestosterone (DHT). Although this enzyme has been localized to various regions of the pilosebaceous unit, its activity has not been studied in the follicular portion of either vellus or sebaceous follicles. The goal of our study was to determine the relative activities of 5α–reductase within various regions of these follicles with particular emphasis on the infrainfundibulum. A finding of increased 5α–reductase activity in upper follicles compared to epidermis might support the hypothesis that increased follicular production of DHT is involved in the hyperkeratinization observed in this region of the follicle in acne vulgaris. 5α–reductase activity was determined at pH 5 (optimal for the type 2 isozyme) and pH 7 (optimal for the type 1 isozyme) in isolated infrainfundibular segments from sebaceous and vellus follicles, homogenized epidermis from various anatomical areas and in microdissected segments of the pilosebaceous unit from breast skin of normal subjects. Enzyme activity was also determined at pH 7 in cultured infrainfundibular keratinocytes and in interfollicular epidermal keratinocytes. Homogenates of infrainfundibular segments demonstrated significantly greater activity at pH 7 compared to pH 5 (P < 0.001), confirming activity of the type 1 5α–reductase in this region. Activity of 5α–reductase was much lower in homogenized epidermis and did not demonstrate a clear pH preference. Keratinocytes cultured from the infrainfundibulum demonstrated significantly greater 5α–reductase activity compared to keratinocytes from interfollicular epidermis (P = 0.04). In the dissected segments of pilosebaceous units from breast skin, 5α–reductase activity was greatest in the sebaceous gland followed by the sebaceous duct, infrainfundibulum, whole skin and epidermis. These data indicate that 5α–reductase activity varies within regions of the pilosebaceous unit and compared with interfollicular epidermal cells, infrainfundibular keratinocytes have an increased capacity for producing androgens which may play a role in the follicular hyperkeratinization seen in acne.     

Expression of tenascin, biglycan and decorin in disorders of keratinization

Summary The distribution of three (recently discovered) extracellular matrix components (tenascin, biglycan and decorin) was studied in normal adult human skin and in a number of monogenic disorders of keratinization, using immunohistology. The expression of tenascin, which is sparsely distributed in normal human dermis, was found to be grossly increased in epidermolytic hyperkeratoses and in Darier's disease. Tenascin expression in three types of ichthyosis (X-linked recessive ichthyosis. autosomal dominant ichthyosis vulgaris. non-erythrodermic lamellar ichthyosis) was similar to that of normal skin. The presence of biglycan and decorin did not show a marked variation between the different disorders studied, suggesting that their expression is subject to regulatory mechanisms distinct from those of tenascin.
The increased expression of tenascin in two disorders of keratinization with a hyperproliferative phenotype, lends further support to the hypothesis that dermal tenascin expression is increased as a result of epidermal hyperproliferation.     

Increased tenascin expression in melanocytic tumors

Tenascin is a large extracellular matrix glycoprotein which is widely distributed in normal, hyperplastic and neoplastic tissues. Its function is unknown but it has been associated with the epithelial-stromal interactions, such as cell adhesion and movement which take place, e.g. in morphogenesis, cellular proliferation and neoplasia. In this study, we investigated tenascin expression in 70 benign, dysplastic and malignant melanocytic tumors by using immunohistochemistry and monoclonal anti-tenascin L43DB7C8 antibody on paraffin sections. In all types of benign nevi, both intradermal, compound and functional, there was a moderate expression of tenascin at the dermoepidermal junction and in the papillary dermis. In dysplastic nevi, the fibrotic areas in the papillary clermis also showed a moderate staining for tenascin. Invasive malignant melanomas showed the strongest expression of tenascin. In addition to the staining at the dermo-epidermal junction and in the papillary clermis, there was a variable expression of tenascin in the reticular dermis. Intracyloplasmic tenascin was detected both in primary melanomas and melanoma metastases. In conclusion, we have shown that tenascin expression is moderately increased in benign and dysplastic melanocytic tumors and greatly increased in malignant melanomas and melanoma metastases. The function of tenascin may be related to the cellular-stromal interactions and it is possibly associated with the proliferation and spread of the melanocytic tumors.     

细胞分化标志分子在扁平苔藓皮损中异常表达的研究

通过研究扁平苔藓皮损中角质形成细胞分化标志的表达情况，分析扁平苔藓的病理机制。本实验应用免疫组化方法以银屑病和正常皮肤为对照，检测扁平苔藓中TGk、Filaggrin、K17和K16的原位表达。结果显示TGk和Filaggrin在扁平苔藓皮损表皮中表达增强，K17和K16在扁平苔藓皮损表皮中出现阳性染色，银屑病皮损中上述标志分子有类似表达，而正常皮肤中则无此现象。提示扁平苔藓皮损中角质形成细胞存在着过度增生和异常分化，上述增生分化标志可能是其病理改变的分子基础。     

Increased expression of tenascin in the dermis in scleroderma

The expression of tenascin, a recently discovered extracellular matrix protein, was studied by immunohistochemical techniques in scleroderma skin and compared with its distribution in normal skin. In progressive systemic sclerosis, a marked increase in tenascin content was observed in the superficial reticular dermis. In localized scleroderma, the deposition of tenascin was increased both in the superficial and deep dermis of involved skin, whereas in clinically uninvolved skin the distribution of tenascin was the same as in normal control skin, i.e. the papillary dermis and peri-appendiceal zone. The distribution of tenascin did not strictly parallel that of fibronectin. These findings and the current knowledge of tenascin biology suggest that the overproduction of tenascin in scleroderma dermis could be secondary to stimulation of fibroblasts by immune cell-derived cytokines, or could be due to abnormal fibroblasts, or a subpopulation of fibroblasts, producing high levels of this extracellular matrix protein.     

Coordinate upregulation of tenascin C expression with degree of photodamage in human skin

Tenascin C is a large extracellular matrix glycoprotein involved in morphogenesis and wound healing. The distribution and expression levels of tenascin were examined in photodamaged skin to investigate the hypothesis that photoaged skin displays characteristics of wound repair. In situ hybridization and semiquantitative immunohistochemistry were performed on paired skin biopsies from patients with varying levels of photodamage, using monoclonal antibodies and cRNA probes for tenascin and its large isoform. In sun-protected skin, tenascin protein was distributed adjacent to the dermoepidermal junction, usually sparsely and discontinuously; tenascin mRNA was detected in dermal fibroblasts and some keratinocytes. In photodamaged skin, tenascin protein was increased in proportion to the clinical level of photodamage (analysis of variance: P < 0.0001, n = 29). With increased photodamage, tenascin protein expression became continuous along the dermoepidermal junction, extending deeper into and sometimes throughout the papillary dermis; tenascin mRNA was detected throughout the epidermis. Large tenascin isoform protein and mRNA distribution mirrored that of pantenascin, suggesting that it may be the predominant species in photodamaged skin. There was no correlation between tenascin expression levels and age or sex, and no seasonal variation was noted. The results indicate that photodamaged skin demonstrates tenascin increases consistent with an early wound healing response. However, tenascin increases in photodamage appear to be permanent and may therefore interfere with effective repair of ultraviolet-induced damage. In conclusion, this study has shown that dermal tenascin expression increases in proportion to the degree of photodamage. In normal skin, the temporal and spatial patterns of tenascin expression during morphogenesis and tissue remodelling are crucial to their correct progression. In photoageing, the 'normal' control of tenascin expression seems to be abrogated.     

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.     

Serial sections of atrophic acne scars help in the interpretation of microscopic findings and the selection of good therapeutic modalities

Background Acne scar causes problems cosmetically and psychologically. Although microscopic examination of acne scars is a necessity for understanding and treatment of them, and it is not easy to find a paper reporting the microscopic characterization of acne scars. Objective The aim of this study was to examine the microscopic findings of acne scars and to select a good therapeutic modality based on the findings. Methods Thirty‐one atrophic scars obtained from five patients for cosmesis and 18 serial sections were made from each atrophic scar. The sections were stained with H&E, Masson‐trichrome or Verhoeff van Gieson stains. Immunohistochemistry was done with antibodies against transforming growth factor‐β, metalloproteinase‐1 (MMP‐1), MMP‐2, MMP‐9 and MMP‐13. The stained sections were examined under the microscope. Results The epidermis of the acne scar was characterized by keratin plugging in the hair follicle orifice (32%) and multi‐channelled tracts (29%). The dermis of the acne scar had characteristics including a decrease in the dermal thickness and loss of pilosebaceous units. In addition, inflammatory cell infiltrates were seen in the dermis (77%), and insufficient dense collagen fibre deposition was found in the whole dermis (29%). Other findings such as calcium deposition and foreign body reaction were discovered. Conclusion We have found the characteristics of acne scar through the serial sections of several atrophic scars, and suggest that the treatment must reflect several considerations, including the understanding of histopathological findings and the use of combination therapy.     

Fibronectin distribution in nailfold biopsies of scleroderma (systemic sclerosis) patients

The distribution of fibronectin (FN) was studied in skin biopsies of 13 patients with scleroderma (SD), 7 patients with dermatomyositis (D), and 10 normal controls (NC) by direct immunofluorescence. In normal tissues, continuous or segmental linear staining of the dermal-epidermal junction (DEJ) was seen. Papillary, subpapillary dermis, and papillary capillary loops showed a reticular pattern of deposition with fibronectin. Scleroderma patients revealed similar staining in the dermis and DEJ. The reticular distribution of FN appeared to stain more intensely in the dermis than in controls, especially in deeper layers. The amount of FN in walls of blood vessels from SD patients was markedly increased; all dermal vessels stained with FN and revealed considerably thicker walls and larger lumens. FN distribution in DM patients was similar to that seen in SD with an increased amount of FN staining in capillary walls.     

The expression of the c-kit receptor by epidermal melanocytes may be reduced in vitiligo

Summary The proto-oncogene c-kit encodes the transmembrane tyrosine kinase receptor that has a role in the growth regulation of various cell types including melanocytes. In the present study we have examined the expression of the c-kit protein in the skin of seven patients with vitiligo. Melanocytes positive for c-kit protein were observed in the basal layer in non-lesional skin and the mean number of 25.8 ± 5·2 (per 200 basai ceils) compared with that of 21·8 ± 3·5 from six control subjects. In perilesional skin there was a reduction in the numbers of c-kit positive melanocytes (6·7±2·6) and this was especially noticeable in six of the seven patients. Such a reduction was less obvious following staining with MEL-5 and in only two subjects were the numbers of melanocytes below the normal range. This suggests that the reduction in c-kit staining was the result of decreased expression of the protein rather than a loss of melanocytes. No melanocytes. positive for c-kit protein, or after staining with MEL-5. were identified in lesional skin although isolated tyrosinase-positive melanocytes were seen in one subject. There was no apparent change in the numbers of mast ceils expressing c-kit protein and the intensity of staining in the dermis even in lesional skin was similar to that in the controls. These results demonstrate that c-kit protein is present on melanocytes in adult human skin and that in perilesional skin of some vitiligo patients there is a reduction in the numbers of melanocytes expressing this receptor. Whether this may contribute to the defective melanocyte growth and/or survival that occurs in vitiligo or whether it is a consequence of melanocyte damage remains to be seen.     

The role of nutrition in inflammatory pilosebaceous disorders: Implication of the skin-gut axis

Nutrition plays a critical role in the manifestation and management of inflammatory pilosebaceous disorders. There is rich potential for insight into the impact of dietary effects on the pathophysiology of inflammatory pilosebaceous disorders including acne vulgaris, hidradenitis suppurativa, rosacea, and the closely related seborrhoeic dermatitis. Acne vulgaris and hidradenitis suppurativa are thought to have similar diet-modulating pathogenic pathways. Western diet influences Acne vulgaris and hidradenitis suppurativa by increasing insulin and modulating FOX01/mTOR, resulting in over-expression of cytokeratins, hyperproliferation of keratinocytes, and hypercornification of the follicular wall. Key receptors in rosacea are alternatively activated by UV radiation, hot beverages, spicy foods, vanilla, cinnamon, caffeine, alcohol, cold temperatures, and niacin- and formalin-containing foods, to increase oedema and flushing, resulting in erythema, telangiectasia, and warmth, characteristic features of the condition. Seborrhoeic dermatitis, while not a follicular disorder, is closely related, and can be modulated by dietary influences, such as biotin and probiotics. This overview summarizes the role that nutrition plays on these disorders, and identifies dietary modifications as potential adjunctive therapies.     

Immunohistochemical study of desmosomes in acne vulgaris

Desmosomes contribute towards adhesion beween adjacent keratinocytes. In acne vulgaris, increased intercellular adhesion is thought to contribute to the retention of keratinocytes within the follicular lumen during comedogenesis. Therefore, the distribution of different desmosomal components was investigated in normal and acne subjects. Biopsies were cryostat-sectioned (6 μm), and stained with antibodies to different desmosomal components: desmoplakin 1/2, desmoglein 1, desmocollin 3a/3b, and a late desmosomal antigen, G36–19. Desmoplakin 1/2, desmoglein 1 and desmocollin 3a/3b shared a similar distribution in follicles from control skin, from acne-affected skin, and in non- intlamed lesions. All three proteins were expressed around the periphery of keratinocytes of all the intrafollicular epidermis, except the basal lamina and the upper stratum corneum. In inflamed lesions, the expression of desmoglein 1 and desmocollin 3a/3b was diminished; in 12.5%, staining for these two proteins was completely abolished, and in 81.25% of the lesions investigated the staining was patchy. The antibody G36–19 bound to an antigen in the upper granular layer in the infundibular epidermis. No differences were noted in the staining pattern of the follicular epithelia of controls, non- inflamed, and inflamed lesions. This study, using monoclonal antibodies, did not identify any changes in the desmosomal components which might explain the increased adhesion between follicular keratinocytes during comedogenesis.     

Delayed skin test reaction to injectable collagen implant (Zyderm). The histopathologic comparative study

Ten cases of persistent positive test site responses to enzyme-digested purified bovine collagen solution (EPC; Zyderm Collagen Implant) were reviewed. Specimens were stained with hematoxylin and eosin, Gomori's trichrome, colloidal iron, elastic van Gieson, Snook 's reticulum, and polarized light. These granulomatous-like reactions were compared with cases of granuloma annulare, hypertrophic scarring, keloids, and rheumatoid nodules. These studies make it possible to differentiate a normal EPC implant from normal reticular dermis. The granulomatous reaction around the EPC implant can be differentiated from granuloma annulare, scars and keloids, and rheumatoid nodules. It is our conclusion that the granulomatous material is probably a combination of EPC and small amounts of altered human collagen.     

Studies on fibronectin in the skin

Fibronectin is a glycoprotein mediating contact between cellular elements and collagen. As judged by indirect immunofluorescence studies fibronectin is abundantly present in normal human skin. It is located in the dermo-epidermal junction area, in the papillary and reticular dermis, about epidermal appendages (pilosebaceous units and eccrine sweat glands) and in the vascular and neural structures.     

Acne vulgaris: an investigation into the number of anaerobic diphtheroids and members of Micrococcaceae the in normal and acne skin

A quantitative study was made of the microflora of 174 acne and 68 non-acne subjects. Two groups of organisms were investigated, the anaerobic diphtheroids and members of the Micrococcaceae. The results showed high numbers of both groups of bacteria in skin bearing blackheads, papules or pustules and in non-acne adolescent skin. There were significantly lower numbers of bacteria in the pilosebaceous ducts of normal looking skin in acne areas and in pre-adolescent skin when compared with non-acne adolescent skin. It is suggested that increased numbers of bacteria alone do not predispose to acne, but that their interaction with the skin, which is a function of the localized skin environment, may be important.     

金属硫蛋白I、II在正常人皮肤中的表达及其意义

目的:探讨金属硫蛋白II、I(Metallothionein II、I,MT-I、II)在正常人皮肤的表达及其意义。方法:采用组织芯片、免疫组化灰度分析方法,研究正常皮肤MT-II、I表达情况。结果:(1)正常皮肤MT-II、I主要表达于表皮基底层和基底层上1~2层角质形成细胞。真皮极少数成纤维细胞、外毛根鞘、小汗腺导管上皮细胞以及皮脂腺外单层嗜碱性细胞也有MT表达。(2)同性别同部位正常皮肤MT-II、I表达强度与年龄呈显著负相关(面r=-0.73,臀部r=-0.98,P<0.01),40岁之前面部皮肤表达强度随年龄增长而快速下降。(3)同年龄同部位正常皮肤MT-II、I表达强度男性显著高于女性(t=6.95,P<0.01)。(4)同年龄同性别正常皮肤MT-II、I表达强度遮光部位显著高于曝光部位(t=4.14,P<0.01)。结论:正常皮肤MT-II、I的表达可能存在人种、性别和年龄差异。老化皮肤合成MT的能力降低,MT-II、I在对抗皮肤老化方面可能有重要作用。皮肤光老化与MT-II、I表达降低有关。