Expression of transferrin receptor in normal human skin, psoriatic skin and various skin tumors

The distribution of transferrin receptor in normal human skin and its expression in psoriatic skin and various skin tumors have been investigated. Immuno-peroxidase staining was performed on biopsy specimens using monoclonal OKT 9 antibody, which reacts with transferrin receptor. Normal human skin showed positive staining with OKT 9 in eccrine glands and outer root sheaths of the hair. Sebaceous glands were also strongly positive. The basal layer stained very weakly. Psoriatic skin expressed OKT 9 strongly in the epidermis, especially in the area of the rete ridge. In squamous cell carcinoma, Bowen's disease, and malignant melanoma, a widespread and strong labelling reaction was found. Basal cell epithelioma and genital Paget's disease were partially and moderately positive in their staining pattern. No such positive staining pattern could be found in either nevus cell nevi or seborrhoic keratosis. These findings indicate that, in normal skin, transferrin receptor exists in eccrine glands, sebaceous glands, and outer root sheaths of the hair in greater amounts. High amounts of expression of this receptor in psoriatic epidermis and malignant tumors suggests that immunohistochemical demonstration of transferrin receptor parallels the proliferating activity of the tissue or tumor of the skin and may provide an useful aid for detecting such conditions.     

Immunolocalization of aquaporin-5 in normal human skin and hypohidrotic skin diseases

Aquaporin (AQP)‐5 has been shown to be expressed in the secretory parts of mouse, rat and horse sweat glands. However, the precise localization of AQP‐5 in normal and diseased human skin has not been fully determined. The aim of the present study was to further clarify the immunolocalization of AQP‐5 in normal human skin and hypohidrotic skin diseases. Normal human scalp skin and biopsies from skin affected by hypohidrotic diseases were analyzed for AQP‐5 and/or dermcidin expression by immunohistochemistry, immunofluorescence and/or immunoelectronmicroscopy. AQP‐5 was expressed on the apical and basolateral plasma membranes of the clear cells in eccrine sweat coils, but not in ductal components or apocrine glands. Numbers of AQP‐5‐positive coils in the secretory part of eccrine sweat glands were decreased in Sjögren’s syndrome, but not in skin affected by idiopathic segmental anhidrosis or idiopathic pure sudomotor failure. AQP‐5 was mostly localized to the plasma membranes of clear cells in the secretory coils of eccrine sweat glands, suggesting that it plays a role in producing the primary sweat fluid.     

Comparison of bacterial microbiota in skin biopsies from normal and psoriatic skin

Microorganisms have been implicated in the pathogenesis of psoriasis. Previous studies of psoriasis and normal skin have used swabs from the surface rather than skin biopsies. In this study, biopsies were taken from 10 patients with psoriasis and 12 control subjects from unmatched sites. Samples were analysed with massive parallel pyrosequencing on the 454 platform targeting the 16S rRNA gene and the variable regions V3–V4. The samples grouped into 19 phyla, 265 taxon and 652 operational units (OTUs) at 97% identity. A cut-off abundance level was set at 1%. The three most common phyla in both normal and psoriasis skin were Firmicutes (39% psoriasis, 43% normal skin), Proteobacteria (38% psoriasis, 27% normal skin) and Actinobacteria (5% psoriasis, 16% normal skin, p = 0.034). In trunk skin, Proteobacteria were present at significantly higher levels in psoriasis compared to controls (52 vs. 32%, p = 0.0113). The commonest genera were Streptococci in both psoriasis (32%) and normal skin (26%). Staphylococci were less common in psoriasis (5%) than in controls (16%), as were Propionibacteria (psoriasis 0.0001669%, controls 0.0254%). Both Staphylococci and Propionibacteria were significantly lower in psoriasis versus control limb skin (p = 0.051, 0.046, respectively). This study has shown some differences in microbiota between psoriasis and normal skin. Whether these are of primary aetiological significance, or secondary to the altered skin of psoriasis remains to be determined.     

Immunolocalization of collagenase inhibitor in normal skin and basal cell carcinoma

Human collagenase inhibitor is a ubiquitous glycoprotein capable of blocking the action of several connective tissue metalloproteinases, including collagenase, gelatinase, and proteoglycanase. The action of this proteinase inhibitor may constitute a pivotal step in the control of connective tissue matrix degradation. Using monospecific antibody to collagenase inhibitor as an immunocytochemical probe, we determined its in vivo localization in normal human skin and in a pathologic state, the altered connective tissue stroma surrounding basal cell carcinoma. Collagenase inhibitor was localized diffusely throughout the dermis and appeared to be associated with the extracellular matrix components, both in normal skin and in basal cell carcinoma. Intense staining was present in the stroma surrounding islands of basal cell carcinoma. The increased amounts of collagenase inhibitor may be a result of its production by stromal fibroblasts stimulated by cytokines of tumor or inflammatory cell origin. These findings are similar to those previously described for dermal collagenase. Both collagenase inhibitor and collagenase itself appear to be normal components of the extracellular matrix, and amounts of both are increased in the altered stroma surrounding neoplastic cells. Thus we suggest that the balance of degradative proteinase(s) to specific inhibitor may be an important factor in determining the composition of the extracellular matrix.     

Immunolocalization of 5alpha-reductase isozymes in acne lesions and normal skin

BACKGROUND: Dihydrotestosterone mediates androgen-dependent diseases, such as acne, hirsutism, and androgenetic alopecia. This hormone is produced from testosterone by the 5alpha-reductase enzyme. There are 2 isozymes of 5alpha-reductase (types 1 and 2) that differ in their localization within the body and even within the skin. Activity of the type 1 isozyme predominates in sebaceous glands, where it may be involved in regulation of sebum production. Since specific inhibition of 5alpha-reductase type 1 may represent a novel therapeutic approach to acne, it is important to define the localization of these isozymes in normal sebaceous follicles and acne lesions. OBSERVATIONS: Skin biopsy specimens were obtained from the backs of 11 subjects: 8 with acne and 3 without acne. Sections of normal follicles, open comedones, closed comedones, and inflammatory lesions were incubated with antibodies to types 1 and 2 5alpha-reductase. In all samples, the type 1 antibody localized specifically to sebaceous glands, and the type 2 antibody localized to the companion layer of the hair follicle (the innermost layer of the outer root sheath) and granular layer of the epidermis. Localization of the type 2 isozyme was also noted within the walls of open and closed comedones and in endothelial cells from sections of inflammatory lesions. CONCLUSIONS: The immunolocalization of 5alpha-reductase isozymes in normal sebaceous follicles and acne follicles is similar to the pattern described in terminal hair follicles and corresponds with the findings of biochemical studies that have demonstrated predominance of type 1 activity in sebaceous glands. The function of type 2 5alpha-reductase in comedones or endothelial cells in inflammatory lesions is unknown.     

Immunohistochemical localization of lipocortins in normal and psoriatic human skin

The distribution of lipocortin I, a steroid-induced inhibitory protein of phospholipase A₂, was examined in normal and psoriatic human skin. Using immunoblotting analysis with specific antibody against human lipocortin I purified from human placenta, lipocortin I was detected as a 37 kDa protein in cultured epidermal cells, whole skin and epidermis. In the dermis and stratum corneum, lipocortin I was only weakly detectable by Western blotting. In contrast to normal skin, much less lipocortin I was detected by Western blotting analysis in psoriatic skin. Using immunoperoxidase immunohistochemical analysis, lipocortin I was demonstrated in the cytoplasm of keratinocytes in the upper and middle layers of the epidermis and in some infiltrating cells in the dermis in normal skin. In involved psoriatic skin, by contrast, lipocortin I was almost undetectable in the epidermis, although it was demonstrated in some infiltrating cells in the dermis. No immunostaining of lipocortin I was observed in the stratum corneum of normal or psoriatic skin. These results, together with the finding that phospholipase A₂ activity is higher in psoriatic epidermis than in normal epidermis, suggest that lipocortin I plays an important role in the regulation of differentiation and proliferation of epidermal keratinocytes.     

Expression of interferon-gamma receptors in normal and psoriatic skin.

Psoriatic keratinocytes have a reduced antiproliferative response to interferon (IFN)-gamma, and HLA-DR expression is usually not observed on keratinocytes in psoriatic plaques despite the presence of activated T cells. We have therefore compared the expression of IFN-gamma receptors in psoriatic skin with that of normal human skin. Using mouse monoclonal antibodies and immunoperoxidase staining on cryostat cut sections, we detected IFN-gamma receptors on keratinocytes throughout the epidermal layers except stratum corneum in normal skin (n = 11). Biopsy specimens from involved psoriatic skin (n = 17) consistently showed a staining pattern that differed from that of normal skin in that only the lower part of epidermis reacted with the antibodies to IFN-gamma receptors, whereas the upper layers showed no or minimal staining. Expression of IFN-gamma receptors in uninvolved psoriatic skin (n = 16) did not differ from that of healthy controls. Forty-five percent of the biopsies from lesional psoriatic skin displayed ICAM-1 positive keratinocytes, and only two specimens had a limited expression of HLA-DR reactive keratinocytes. The decreased binding of antibodies against the IFN-gamma receptors in the upper part of psoriatic epidermis might be secondary to abnormal maturation of psoriatic keratinocytes or a primary defect involving abnormal modulation of IFN-gamma receptors.     

Chromosome studies of normal and psoriatic skin fibroblasts.

A method for obtaining large numbers of fibroblasts from punch biopsies of skin tissue and a procedure for the visualization of chromosomes from these cells are presented in detail. The chromosomes are well separated, and fine details of their structure are seen. A study was made of 275 cells from apparently normal and from involved areas of skin from patients with psoriasis. No changes either in the number or in the fine structure of the chromosomes were observed.     

In vivo quantification of microvessels in clinically uninvolved psoriatic skin and in normal skin

BACKGROUND: Microvascular abnormalities (capillary elongation, widening and tortuosity) are a characteristic feature of psoriasis and form one of the pathological diagnostic criteria. However, it is still not entirely clear when these microcirculatory changes appear in the skin of psoriatic subjects. Some studies suggest that capillary dilatation and elongation are present in the clinically uninvolved skin of psoriatic patients even at sites at which psoriatic plaques rarely occur. OBJECTIVES: To determine, using noninvasive techniques in vivo, the nature of any microvascular changes in the clinically uninvolved skin of psoriatic subjects and to quantify the dermal microvasculature in the clinically uninvolved skin of psoriatic subjects, in vivo. METHODS: Dermal microvessels in both the clinically uninvolved skin of psoriatic subjects and in the skin of normal volunteers (i.e. individuals without any clinical evidence of psoriasis or other inflammatory dermatoses) were directly visualized by native video-capillaroscopy, in vivo. Images were analysed using a combination of nonstereological and stereological measurements. The findings in each group were then compared to determine if there were any differences in microvascular parameters. RESULTS: Quantitative analysis of capillaroscopic images showed that there were no significant differences in microvessel density (P = 0.9), image area fraction (P = 0.6), microvessel length density (P = 0.7) and vessel image width (P = 1.0) in the clinically uninvolved skin of psoriatic subjects and the normal skin of healthy volunteers, when extensor forearm skin was examined. CONCLUSIONS: These findings indicate that prior to the development of clinical lesions there are no significant morphological differences between the dermal microvessels in the clinically uninvolved skin of psoriatic subjects and the dermal microvessels in the normal skin of healthy volunteers. However, during plaque formation, the superficial papillary microvessels in plaque skin undergo a striking, characteristic change, i.e. elongation, widening and tortuosity. These blood vessels must therefore, at least in part, play an important, necessary, but probably secondary role in the pathogenesis of clinical lesions in psoriasis.     

Increased expression of adhesion receptors in both lesional and non-lesional psoriatic skin

Adhesion receptors and their ligands play a vital role in the immune system. We studied the expression of different adhesion receptors, using single- and double-staining immunohistochemical techniques, in both lesional and non-lesional skin specimens from seven psoriasis patients and in skin biopsy specimens from eight normal healthy controls. Our results showed an overall increased expression of several adhesion receptors in both lesional and non-lesional psoriatic skin. We consistently found an increased expression in particular of ICAM-1 and E-selectin on endothelial cells, and ICAM-1 on T cells and Langerhans cells. In contrast, a weak expression of VCAM-1 was found on endothelial cells and mononuclear cells in lesional psoriatic skin specimens alone. Interestingly, LFA-1 was also expressed on Langerhans cells, with a greater frequency in skin from lesional than from non-lesional sites, but was never expressed in skin from normal healthy individuals. Furthermore, significantly increased numbers of Langerhans cells and T cells with a positive reactivity for MAb HECA-452 were found in both lesional and non-lesional psoriatic skin. We hypothesize that the enhanced expression of adhesion receptors on migrating immunocompetent cells and endothelial cells of psoriatic skin in general facilitates the increased influx of activated T lymphocytes and other immunocomponent cells into the skin, and thus underscores the generalized character of the disease.     

Immunolocalization of fibroblast growth factor receptors in normal and wounded human skin

Fibroblast growth factors (FGFs) have been shown to play diverse roles in various tissues. To define their sites of action in normal human skin and during wound healing, we determined the protein expression of the four known fibroblast growth factor receptors (FGFRs) in normal and wounded human skin by immunohistochemistry. Four receptors (FGFR-1 to FGFR-4) showed distinct patterns of expression in normal skin. Expression of FGFR-1 was widespread in the epidermis, appendages, arrector pili muscles, blood vessels, and dermal fibroblasts. Intense expression of FGFR-2 and FGFR-4 was seen in the arrector pili muscles and smooth muscle cells of vessels. In the epidermis, the basal layer showed immunoreactivity for FGFR-2, whereas the suprabasal layers and the inner layers of hair follicles showed strong immunoreactivity for FGFR-3. In wounded skin, there was strong expression of FGFR-1 and FGFR-3, and moderate expression of FGFR-2 and FGFR-4 in the basal layer in newly forming epidermis. In granulation tissues, neocapillaries expressed all four FGFRs, fibroblasts/myofibroblasts expressed FGFR-1 and FGFR-3, and mononuclear inflammatory cells expressed FGFR-1 and FGFR-3. Our results suggest that the differences in the spatial patterns of FGFR expression in normal skin may generate functional diversity in response to FGFs and that in wounded skin, FGFs may function in wound healing via the induced FGFRs.