Presence and distribution of cytokeratins and filaggrin in human anagen follicles

The presence and distribution of several types of cytokeratins and of filaggrin in human anagen hair follicles were investigated using the following monoclonal antibodies (McAB): KL 1, CK 8.60, CK 8.12, PKK-2, CK 18, CK 19 and anti-filaggrin McAb. Constant and characteristic patterns of McAb labelling were obtained in distinct compartments of the hair follicle, except for CK 18, which failed to label any of the follicular cells. Anti-filaggrin McAb was regularly bound to the Henle's layer of the internal root sheath, showing for the first time the presence of "filament aggregating protein" in the human hair follicle.     

七种细胞角蛋白在皮肤上皮性肿瘤中的表达

目的 观察7种细胞角蛋白在皮肤上皮性肿瘤中的表达,并探讨其意义.方法 应用免疫组化S-P法对54例不同的皮肤上皮性肿瘤和20例正常皮肤进行细胞角蛋白7(K72.2)、细胞角蛋白8(C-51)、细胞角蛋白10(DE-K10)、细胞角蛋白14(LL002)、细胞角蛋白17(E3)、细胞角蛋白18(DC10)、细胞角蛋白19(KS19.1)标记,观察不同细胞角蛋白的表达.结果 54例皮肤上皮性肿瘤包括,鳞状细胞癌10例、基底细胞癌10例、毛发肿瘤19例、皮脂腺癌2例、汗腺肿瘤13例.皮肤上皮性肿瘤中7种细胞角蛋白的表达和分布有所不同.鳞状细胞癌、基底细胞癌和毛发分化的肿瘤中细胞角蛋白多数呈弥漫表达;而汗腺分化的肿瘤中,不同部位表达不同细胞角蛋白,每种肿瘤各有特点.结论 选择地检测一组细胞角蛋白的联合表达,有助于皮肤上皮性肿瘤的诊断和鉴别诊断.     

Cytokeratins as markers of follicular differentiation: an immunohistochemical study of trichoblastoma and basal cell carcinoma.

Trichoblastoma(s) (TB) are benign neoplasms of follicular differentiation frequently found in nevus sebaceus. Many morphologic features are shared with nodular basal cell carcinoma(s) (BCC), sometimes rendering the differential diagnosis difficult. Because both neoplasms can simulate components of mature hair follicles histologically, we attempted to corroborate this by immunohistochemical examination of cytokeratins and hair keratins differentially expressed in the hair follicle. Trichoblastoma(s) and BCC showed homogenous expression of CK14 and CK17. The innermost cells of the tumor nodules in all TB and in 72% of BCC were positive for CK6hf. Using a specific CK15 antibody, 38% of TB showed a focal labeling and all BCC remained negative; 70% of TB and 22% of BCC expressed CK19. CK8 was expressed by numerous Merkel cells present in all TB but in none of the BCC examined. All type I and II hair keratins tested, (especially hHa1, hHa5, and hHa8) remained negative in all tumors examined. Trichoblastoma(s) and BCC show consistent expression of CK6hf, CK14, and CK17; variable expression of CK15 and CK19; and absence of hair keratins. This indicates a differentiation toward the outer root sheath epithelium or the companion layer and not toward the inner root sheath, matrix, or cortex.     

细胞角蛋白在皮肤附属器肿瘤的表达及其诊断意义

目的:观察7种细胞角蛋白(cytokeratins,CK)在皮肤附属器肿瘤的表达,并探讨其意义。方法:应用免疫组织化学S-P法对49例不同皮肤附属器肿瘤进行CK7(K72.2)、CK8(C-51)、CK10(DE-K10)、CK14(LL002)、CK17(E3)、CK18(DC10)、CK19(KS19.1)标记,观察不同细胞角蛋白的表达和分布模式。结果:49例皮肤附属器肿瘤中7种细胞角蛋白的表达和分布有所不同。毛发分化的肿瘤中CK表达多数较弥漫;而汗腺分化的肿瘤中,不同CK表达位置明显不同,每种肿瘤各有特点。结论:综合分析CK1018表达情况,可能有助于汗腺肿瘤与毛囊肿瘤的鉴别,CK10-18 支持为汗腺肿瘤,CK10 18-支持为毛囊肿瘤。     

Carcinoma arising in a proliferating trichilemmal cyst expresses fetal and trichilemmal hair phenotype

Carcinomas that arise in a proliferating trichilemmal cyst (PTC) have been described under a variety of names. Monoclonal antibodies (mAbs) indicating follicular differentiation have become available and were used here in two rare tumors with uncommon biologic behavior. To further elucidate the histogenesis of carcinomas arising in a PTC, mAbs to hair follicle stem cells and to hair follicle differentiation-specific cytokeratins (mAbs to cytokeratin [CK] 7, CK8, CK18, and CK19 as well as mAbs to CD8/CK15 and CD34) were studied on paraffin-embedded sections of two cases of carcinoma arising in a PTC, one anaplastic carcinoma, and one poorly differentiated squamous cell carcinoma (SCC). For comparison, concurrent PTCs and trichilemmal cysts as well as four SCCs from controls were studied. The anaplastic carcinoma showed expression of CK7, indicating a fetal hair root phenotype, and expression of CD34, indicating trichilemmal differentiation. In contrast, the poorly differentiated SCCs as well as the control SCCs stained negative for most of the mAbs applied. Expression of fetal and trichilemmal hair follicle phenotypes suggests differentiation from hair stem cells and might explain differences in biologic behavior.     

Hair cycle-dependent expression of a nonspecific cross reacting antigen (NCA)-50/90-like molecule on follicular keratinocytes

We found a carcinoembryonic antigen (CEA)-related antigen to be strongly expressed on a subset of follicular keratinocytes in normal human skin. The antigen was characterized immunohistochemically using a panel of antibodies against human CEA and CEA-related molecules. The expression of the antigen was studied in different phases of the hair cycle as well as in different hair types. Immunohistochemically, the antigen resembled the nonspecific crossreacting antigen (NCA)NCA-50/90 rather than true CEA. Its expression was limited to the innermost cells of the lowest segment of hair follicles in the catagen/telogen phases, being detected only where the hair shaft was attached to the epithelial hair sac in these phases. The same results were obtained for all hair types, i.e. terminal, vellus and intermediate hair. Coexpression of the antigen with both involucrin and differentiation-associated cytokeratins was noted in the cells in additional studies attempting to identify the exact subpopulations of follicular keratinocytes expressing the antigen in comparison with the expression of other functional markers. However, involucrin and the cytokeratins were also expressed in the upper segments of anagen as well as catagen/telogen hair follicles. Our findings strongly suggest that an NCA-50/90-like molecule is expressed cyclically on the innermost cells in the lowest segment of the outer root sheath only in catagen/telogen hair follicles. The cyclical expression in this specific subset of follicular keratinocytes only, in which the epithelial hair sac is attached to the hair shaft, may be associated with the stability of the attachment through the adhesive or, conversely, the repulsive function of CEA-related molecules, both of which have recently been proposed. Received: 16 January 1996     

Altered cytokeratin expression in actinic cheilitis

BACKGROUND: Actinic cheilitis (AC) is a widely recognized precancerous lesion of the lip. Varying degrees of epithelial dysplasia may be present. However, no studies have correlated epithelial changes with cytokeratin expression that might reflect the disordered maturation that is probably occurring. METHODS: Thirty-four cases diagnosed as AC were classified according to dysplasia degree, and submitted to immunohistochemical staining for the detection of cytokeratins (CKs) 7, 8, 13, 14, 16 and 19. Normal mucosa adjacent to the lesions was also evaluated. RESULTS: The results obtained showed that CK10 immunostained only superficial keratinized epithelial layers in 11 cases, and also intermediate spinous layers in 18 cases. Cytokeratin 14 was expressed in all epithelial layers of 31 cases, in two cases its expression was in the basal and intermediate layers, and one case was negative. Cytokeratin 13 immunostained 26 cases and was negative in eight cases. In these eight cases, CK13 was apparently replaced by CK16. Cytokeratin 16, besides these eight cases, was also expressed in the spinous intermediate layers of a further eight cases. The remaining CKs tested were all negative. No relation between the degree of dysplasia and the CK expression was noted. CONCLUSIONS: Cytokeratin expression in AC is different from that of normal oral mucosa, and is not related to the degree of dysplasia.     

CD10 and CD34 in fetal and adult human hair follicles: dynamic changes in their immunohistochemical expression during embryogenesis and hair cycling

Background  CD10 and CD34 have been detected in both epithelial and mesenchymal components of anagen human hair follicles.
Objectives  To analyse the expression of CD10 and CD34 in human hair follicle development as well as in different phases of the hair cycle.
Methods  Fetal and adult hair follicles at different stages of the hair cycle were examined by immunohistochemistry for CD10 and CD34.
Results  In fetal follicles, CD10 is expressed by the cells of the placodes, and CD34 by the mesenchymal cells of the dermal condensate. As the follicle matures, CD10 can be seen in the matrix cells, inner root sheath and dermal sheath. In adult follicles, the expression of CD10 in the follicular epithelium is present in anagen follicles, but tends to disappear in catagen, and is not detected in telogen. The CD10 positivity of the dermal sheath is more intense in catagen than in anagen follicles. CD34 immunostaining of the external root sheath was seen in adult anagen follicles but not in fetal follicles. This staining of the anagen outer sheath tends to disappear in catagen and is not detected in telogen.
Conclusions  CD10 and CD34 are not proteins constantly present in a specific cell type of the hair follicle, but are proteins that can be expressed by both epithelial and mesenchymal cells depending on the stage of development and hair cycle. The distribution of the immunoreactivity to CD10 in the placode and CD34 in the dermal condensate suggests a role of these proteins in initial stages of hair formation.     

An investigation of cytokeratin expression in skin epithelial cysts and some uncommon types of cystic tumours using chain-specific antibodies

Summary The differentiation state of skin epithelial cysts and some uncommon types of epithelial skin tumours was investigated by immunohistochemical staining, mainly using cytokeratin (CK) polypeptide-specific monoclonal antibodies. Samples of interfollicular epidermis, hair follicles and eccrine sweat glands were included as reference tissues. The CK reactivity in epidermoid cysts and milia is not restricted to CKs involved in epidermal-type differentiation, i.e. CK1, 5, 10 and 14, but in addition CK16, a hyperproliferative keratinocyte marker is suprabasally expressed. CK1 and 10 are other prominent suprabasal markers, while CK14 seems to be preferentially expressed in the basal cell layer. Of the non-epidermal CKs, only CK4 was focally or more extensively detected in about 50% of the cases. In terms of CK reactivity, keratinization of trichilemmal cysts corresponds to the keratinization of the anagen-phase hair follicle in the isthmus. The CK reactivity is again restricted to CK1, 5, 10, 14 and 16. However, the CK1 as well as CK10 reactivity is subject to serious limitations, since both CKs were only convincingly observed in foci of terminal differentiation. Eccrine hydrocystoma obligatorily expresses a complex CK set, including CK7, 8, 14, 18 and 19. This CK set perfectly corresponds to the CK composition observed in acini of eccrine sweat glands. In addition, a discontinuous CK4 and 16 reactivity was seen in about 50% of the sites, while CK1 and 10 displayed a strictly focal appearance. On the other hand, syringoma produces in its distinct structures, a CK pattern reminiscent of the one observed in eccrine sweat gland ducts and includes CK1, 5, 10, 14, 16 and 19. Finally, the CK expression pattern of pilomatricoma includes CK1, 8, 10, 14 and 19, and is reminiscent of the CK staining of hair bulb matrix cells differentiating in the keratogenous zone in the direction of hair cortex. The reactivity of CK1 and 10 was mainly restricted to foci of squamoid differentiation and also to transitional cells bordering on shadow cells, as far as it concerns CK10. Occasionally, CK7 and 16 were observed in individual cells or small cell groups. In our view these CK reactivity patterns are useful to judge the differentiation state reached in pathological conditions, but so far do not allow us unequivocally to determine the site of origin of these lesions.     

Expression of macrophage migration inhibitory factor in rat skin during embryonic development

Abstract:  We have previously shown that human epidermal keratinocytes express macrophage migration inhibitory factor (MIF) mRNA, and immunohistochemical studies showed that MIF is expressed in human epidermis. To explore the possible pathophysiological roles of MIF in skin during rat fetal development, we examined the expression patterns of MIF during rat epidermal development using Northern blot analysis and in situ hybridization. Expression of MIF mRNA was first detected by in situ hybridization in the developing epidermis and hair germ cells from embryonic day (ED) 16. From ED 19, moderate levels of MIF expression were detected in the epidermis and epithelial sheath cells of growing hair follicles. In postnatal rat skin, higher MIF expression was detected in the epidermis and hair follicles on postnatal day 3. These observations were also confirmed by Northern blot analysis. Immunohistochemical analysis with an anti-MIF antibody showed a similar distribution to that of the mRNA. Our results suggest that MIF is associated with epidermal and hair follicle development.     

Dilated pore: a case report and an immunohistochemical study of cytokeratin expression

We report a 71-year-old Japanese female with a dilated pore in the form of a nodule above her right eyebrow. Histologic examination revealed a flask-shaped, keratinous cystic structure that was continuous with the surface epidermis and had numerous elongated rete ridges in the lower portion. An immunohistochemical study using a panel of monoclonal antibodies against cytokeratins (CKs) and involucrin detected CK1 and CK10 in the suprabasal cells of the cystic structure. CK8 and CK19 expression was observed in the outermost layer of some elongated rete ridges; it was composed of pallisading columnar cells. Most parts of the outermost layer of the cystic structure stained positively with AE1 antibody. From these immunohistochemical findings, we speculated that the dilated pore in our case was an isolated clinical entity is a follicular tumor differentiating mainly toward the infundibulum and partly toward the isthmus.     

Early development of human Merkel cells

Human fetal Merkel cells are now generally considered to be epidermal derivatives. Previous studies using antibodies against the simple epithelial cytokeratins (CKs), 8 and 18, have demonstrated the presence of these cells in the epidermis at as early as fetal week 10 to 12. Using antibodies against CK 20 whose expression within the skin is restricted to Merkel cells, we applied immunofluorescence and immunoperoxidase microscopy to analyze earlier embryonic and fetal human skin (wk 7 to 9). We were able to demonstrate the first Merkel cells at as early as fetal wk 8, i.e., at the same time as the epidermis starts to develop an intermediate, third layer, characterized by the expression of CKs 1, 10, and 11. Most of these early Merkel cells were localized above the basal layer. Their shape was round to oval, dendrites being infrequent and short. At fetal wk 9, Merkel cells were considerably more numerous. These results persuasively argue for a much earlier fetal development of Merkel cells within the epidermis than previously thought. A hypothesis concerning the differentiation of Merkel cells from embryonic basal keratinocytes is discussed.     

Immunohistochemical analysis of cytokeratin and human milk fat globulin expression in mucinous carcinoma of the skin

BACKGROUND: Mucinous carcinoma of the skin (MCS) is a rare epithelial tumor which arises primarily in the skin. Metastatic MC from extracutaneous sites, especially breast or colon, mimics MCS and cannot be differentiated from MCS by routine histology alone. METHODS: Nine cases of MCS were analyzed immunohistochemically using monoclonal antibodies against cytokeratins (CKs) and human milk fat globulin 1 (HMFG) in order to clarify their nature and compare the immunophenotypes with those of other MCs studied in the literature. RESULTS: Expression of simple epithelial CKs in most of the tumor cells of all cases studied and co-expression of simple and stratified epithelial CKs in some tumor cells of two cases were recognized. CK 20 expression could not detected in any tumor cells. Focal HMFG expression in the luminal or outer surface of the nests was observed in three cases. CONCLUSION: From CKs expression, MCS was speculated to differentiated mainly toward the secretory cells of the sweat glands, and some tumor cells toward the transient portion between the dermal duct and the secretory portion. Focal HMFG expression suggested either a consequence of malignant transformation or apocrine differentiation. No expression of CK 20 in MCS suggests that we may exclude the diagnosis of metastatic colorectal MC which expressed CK 20.     

Expression of caspase-14 and keratin-19 in the human epidermis and appendages during fetal skin development

Caspase-14 is a seemingly non-apoptotic caspase involved in keratinocyte differentiation and cornification of the skin. Keratin-19 is an epithelial marker and a potential marker of epidermal stem cells that is expressed during human fetal skin development. We examined the immunohistochemical expression of caspase-14 in relation to CK-19 in the human fetal skin during development and perinatally, to assess their role in human skin maturation. Skin samples were received at autopsy. In the fetal epidermis, caspase-14 was predominantly expressed in the more differentiated layers, gradually disappearing from the basal layer toward term. By contrast, keratin-19 expression gradually decreased with epidermal maturation through gestation (rho = ?0.949; p = 0.0001) and was a marker of the germinative layers. Keratin-19 was preserved in scarce basal cell nests at term and postnatally. Caspase-14 and keratin-19 were inversely expressed in the differentiating epidermal layers through gestation (p < 0.0001). Concerning the appendages, in hair follicles and sebaceous glands, caspase-14 located preferentially in the more differentiated layers of the inner root sheath, whereas keratin-19 was expressed in the outer sheath. Eccrine sweat glands showed a variable pattern of caspase-14 and keratin-19 expression. In conclusion, caspase-14 emerged as a marker of human skin differentiation during development, while keratin-19 marked the germinative epithelial layers in the fetal epidermis and appendages and possibly the nests of epidermal stem cells.     

Expression of vascular endothelial growth factor (VEGF) in various compartments of the human hair follicle

Abstract Hair follicle vascularization appears to be closely related to the processes involved in hair cycle regulation, in which growth factors, cytokines and other bioactive molecules are involved. In particular, vascular endothelial growth factor (VEGF), essential for angiogenesis and vascular permeability, may be responsible for maintaining proper vasculature around the hair follicle during the anagen growth phase. The aim of our study was to compare the in vitro angiogenic capacity, i.e. the steady-state expression of the VEGF gene, of different cultured cell types derived from normal human hair follicles, corresponding to different follicular compartments. Human dermal papilla cells (DPC), fibrous sheath fibroblasts, dermal fibroblasts, and follicular and interfollicular keratinocytes were cultured and studied in vitro for VEGF expression at the mRNA level using RT-PCR, and for VEGF protein synthesis by radioimmunoprecipitation and immunocytochemistry. In vivo examination for VEGF expression in human terminal hair follicles was performed using immunohistochemical methods. In the present report the expression of four different VEGF molecular isoforms, differing in their angiogenic capacity, are described in different cultured follicular cell types for the first time. Cultured follicular cells strongly expressed mRNA of four VEGF molecular species identified as the 121-, 145-, 165- and 189-amino acid splice variants, the most prominent being the 121-amino acid molecule. DPC, and also other mesenchymal cells such as fibrous sheath fibroblasts and dermal fibroblasts, in vivo and in vitro strongly expressed VEGF mRNA and synthesized a 46-kDa VEGF protein, whereas follicular and interfollicular keratinocytes in vitro expressed lower levels of VEGF mRNA and proteins than mesenchymal cells. As the highest expression of VEGF was found in DPC, we suggest that DPC are mainly responsible for angiogenic processes possibly related to the human hair cycle. Received: 14 January 1998 / Received after revision: 16 July 1998 / Accepted: 30 July 1998     

Expression of decorin throughout the murine hair follicle cycle: hair cycle dependence and anagen phase prolongation

Decorin is a prototypical member of the small leucine‐rich proteoglycan (SLRP) family, which is involved in numerous biological processes. The role of decorin, as a representative SLRP, in hair follicle morphogenesis has not been elucidated. We present our initial findings on decorin expression patterns during induced murine hair follicle (HF) cycles. It was found that decorin expression is exclusively restricted to the epidermis, outer root sheath and sebaceous glands during the anagen phase, which correlates with the upregulation of decorin mRNA and protein expression in depilated murine dorsal skin. Furthermore, we used a functional approach to investigate the effects of recombinant human decorin (rhDecorin) via cutaneous injection into HFs at various murine hair cycle stages. The local injection of rhDecorin (100 μg/ml) into the hypodermis of depilated C57BL/6 mice at anagen delayed catagen progression. In contrast, rhDecorin injection during the telogen phase caused the premature onset of anagen, as demonstrated by the assessment of the following parameters: (i) hair shaft length, (ii) follicular bulbar diameter, (iii) hair follicle cycling score and (iv) follicular phase percentage. Taken together, our results suggest that decorin may modulate follicular cycling and morphogenesis. In addition, this study also provides insight into the molecular control mechanisms governing hair follicular epithelial–mesenchymal interactions.     

VEGF165 modulates proliferation,adhesion, migration and differentiation of cultured human outer root sheath cells from central hair follicle epithelium through VEGFR-2 activation in vitro

BackgroundThe functional state of vasculature is tightly controlled by vascular endothelial growth factor receptor-2 (VEGFR-2). Recent studies revealed that VEGFR-2 is expressed on hair follicle keratinocytes.ObjectiveWe proposed to investigate its effect on proliferation, adhesion and migration of cultured human outer root sheath cells from central hair follicle epithelium.MethodsThese studies were undertaken in vitro using human outer root sheath cells from central hair follicle epithelium, immunohistochemistry analysis, immunofluorescence microscopy, western blot analysis, MTT, trans well analysis, and RT-PCR.ResultsOur results show that VEGFR-2 is expressed in these cells in vivo and in vitro. Furthermore, proliferation and migration of cultured human outer root sheath cells from central hair follicle epithelium is increased by VEGF₁₆₅, while homotypic adhesion is decreased but heterotypic adhesion is increased. VEGF₁₆₅ upregulates integrin β1 but dowregulates lgr6 expression. In addition, phosphorylation of VEGFR-2, Erk1/2, c-Jun and p38, are increased following VEGF₁₆₅ treatment and these effects are reversed by a VEGFR-2 neutralizing antibody.ConclusionOur results suggest a role of VEGF/VEGFR-2 beyond angiogenesis in hair follicle regulation.     

Proliferative merkel cells were not detected in human skin

The fetal development of Merkel cells-neuroendocrine cells of the skin—has been a matter of debate for a long time. Recent results have helped to confirm their intraepidermal development in humans. Simple epithelial cytokeratins (CK) nos. 8, 18, 19 and 20 are well established markers at the light microscopic level. These cells could be detected from fetal week 8 within the epidermis with an enormous increase during the following weeks. This gives rise to the question as to whether Merkel cells are undergoing mitoses or whether they are derived from basal keratinocytes. We studied fetal and adult skin using antibodies to simple epithelial CK and to Ki67, a human nuclear cell proliferation-associated antigen in an attempt to answer these questions. In human adult and fetal skin of various stages we could not detect any Merkel cells undergoing cell division. These results suggest that Merkel cells are postmitotic cells to be renewed from undifferentiated keratinocytes with stem cell characteristics.     

An immunohistochemical study on cell differentiation in the outer root sheath of the normal human anagen hair follicles with antikeratin monoclonal antibodies]

The expressions of several cytokeratins (CKs) in the outer root sheath (ORS) of the human anagen hair follicles were immunohistochemically studied using 11 antikeratin monoclonal antibodies (MoAbs) and 10 specimens from scalp. CKs 1, 10, 11, which are markers for differentiating keratinocytes, were exclusively found in the intermediate cells and the granular cells at the infundibulum. In cytokeratin expression, a distinct linear demarcation between the infundibulum and the isthmus was observed. Trichilemmal keratinization appeared to go in an inner-upward direction toward the hair canal. CK 19, a marker of undifferentiated stem cells, was found in outermost cells of the ORS at the isthmus and in some cells of the lower ORS. CK 16, a marker of hyperproliferative keratin, was detected in the outermost cells of the infundibulum and all the cells of the ORS below the isthmus. Therefore, the keratinocytes at the infundibulum may show a differentiation similar to that of the interfollicular epidermal keratinocytes. The ORS cells below the isthmus seem to move up to inner-upward direction along the hair axis with differentiation.