Dynamic changes in epidermal Ia-positive cells in allergic contact sensitivity reactions in mice

In mice sensitized with trinitrochlorobenzene, serial changes in epidermal Ia-positive cells were studied at various times after challenge. Until 3 days post-challenge, the Ia-positive cells consisted only of dendritic Langerhans cells; their number was decreased but they were significantly enlarged, with extending dendrites. Some Langerhans cells were also found surrounding a hair follicle, extending their dendrites toward the follicle like the spokes of a wheel. From 3 to 9 days after challenge, keratinocytes also began to express Ia antigens in the epidermis in addition to Langerhans cells, whose size diminished. This suggests that there are two phases in the response of the epidermal Ia antigens in contact sensitivity reactions, i.e. an early phase in which enlarged Langerhans cells are the only Ia-positive cells in the epidermis, and a late phase in which keratinocytes take over as the major Ia-positive cells, while Langerhans cells resume their original size. Ia antigen expression on keratinocytes in this late phase probably plays a crucial role in completely eliminating allergens deposited on the keratinocytes.     

Apoeccrine sweat duct obstruction as a cause for Fox-Fordyce disease

The pathogenesis of Fox-Fordyce disease has been reported to be hyperkeratosis and obstruction of the upper hair follicle, where the duct of the apocrine sweat gland opens. We report a case of Fox-Fordyce disease with full clinical manifestation. It appeared to be caused by the obstruction of intraepidermal apoeccrine sweat ducts by apoeccrine secretory cells detached and released from the secretory epithelium. A 24-year-old woman visited our clinic with intensely pruritic papules on axillae, mammary areolae, and pubic areas. Histopathologic examination revealed an obstruction of the sweat duct in the epidermis, which opened directly to the skin surface. The closing substance of the duct was an aggregate of epithelial cells, probably derived from the secretory portion. In the dermis, the secretory cells of apocrinelike sweat glands had been detaching from the secretory epithelia. These findings suggest that Fox-Fordyce disease can occur by the mechanism in which apoeccrine secretory cells obstruct sweat ducts.     

Comparison between the expression of basement membrane zone antigens of human interfollicular epidermis and anagen hair follicle using indirect immunofluorescence

BACKGROUND: The composition of the basement membrane zone (BMZ) or dermal-epidermal junction in the interfollicular skin has been well documented. However, little is known about the BMZ or connective tissue-epithelial junction along the hair follicle. OBJECTIVES: To determine whether the BMZ antigens in the interfollicular epidermis are also present in the BMZ of the anagen hair follicle and to compare whether the expression and distribution of the BMZ components vary between the interfollicular epidermis and the anagen follicle and within different regions of the hair follicle. METHODS: Longitudinal cryostat sections of scalp margin specimens from four adult patients undergoing cosmetic surgery, and without known pathology were stained with a panel of monoclonal and polyclonal antibodies to different BMZ constituents using standard indirect immunofluorescence. RESULTS: All the BMZ antigens found in the normal interfollicular epidermis were expressed in the anagen follicle; however, there were regional variations in the intensity and patterns of fluorescence. All the antigens were expressed in a continuous linear pattern along the BMZ of the interfollicular skin, the infundibulum, and the middle part of the hair follicle. Differences were observed in the lower follicle and the hair bulb. There was continuous expression throughout the BMZ of the follicle of laminin-1 and collagen IV, but in contrast, expression of other antigens decreased down the lower follicle. There was weak or even negative staining with antibodies to alpha 6 beta 4 integrin, laminin-5, anchoring filaments, and type VII collagen in the outer aspect of the bulb compared with the hair papilla. In addition, there were special patterns observed along the bilateral middle and lower follicle. CONCLUSIONS: Despite the common embryological origin between the interfollicular epidermis and the hair follicle, there is variation in the expression of the BMZ antigens. This may be explained by the histological specialization and functional requirements that reflect the dynamic hair growth cycle.     

活血化瘀法治愈Fox—Fordyce病1例报告

报告1例Fox—Fordyce病。患者女，37岁，因腋窝、乳晕、外阴瘙痒性丘疹lO年余而就诊，皮肤科检查可见双侧腋窝、乳晕、外阴对称性多发米粒至绿豆大毛囊性圆形丘疹，组织病理检查符合Fox-Fordyce病。本例患者用活血化瘀中药治疗取得显著效果，随访3个月无复发。     

Anti-hair keratin monoclonal antibody (HKN-2)

BALB/c mice were immunized with human hair fibrous proteins. Then their spleen cells were fused with Sp2/0-Agl4 mouse myeloma cells. Antibody-producing hybridomas were selected by ELISA method and cloned by limiting dilution. A monoclonal antibody was chosen and designated as HKN-2. Immunohistochemically, on frozen sections of normal human skin, HKN-2 was found to recognize the suprabasal cells of epidermis and hair follicle, the cells in the keratogenous zone of hair shaft, the sebaceous cells and the ductal and myoepithelial cells of sweat glands. The basal cells of the epidermis and lower hair follicle, hair matrix cells and secretory cells of sweat glands did not react with HKN-2. An immunoelectron microscopic method showed that the positive reaction to HKN-2 was located on the tonofilaments in the cytoplasm. It was concluded that there might be a common antigenic determinant between hair and other skin epithelial tissues. A complexity in keratin manifestation in each epithelial tissue of the skin was suspected.     

Immunohistochemical study of calretinin in normal skin and cutaneous adnexal proliferations

Calretinin is a calcium-binding protein member of the EF-hand family. The presence of calretinin has been demonstrated in certain stages of the cellular cycle in a wide variety of normal and neoplastic tissues. The main aims of our study were (1) to investigate what structures of the normal skin and cutaneous adnexal proliferations express immunoreactivity for calretinin and (2) to determine the value of immunohistochemical expression for calretinin as a marker for follicular, sebaceous, apocrine, and eccrine differentiation in cutaneous adnexal proliferations. We studied 139 biopsy specimens, including 10 cases of normal skin of different locations and 129 benign and malignant cutaneous adnexal proliferations. In normal skin, we found that calretinin is expressed in the innermost cell layer of the outer root sheath in anagen hair follicle, in both the duct and sebolemma of the sebaceous gland, in the secretory portion of eccrine glands, and in mast cells of the stroma. In cutaneous adnexal proliferations, we found strong immunoreactivity for calretinin in tricholemmal cysts, tricholemmomas/inverted follicular keratoses, tumors of follicular infundibulum, and in some basal cell carcinomas. Focal positivity was also seen in trichoadenomas, trichoblastomas/trichoepitheliomas, pilomatricomas, proliferating tricholemmal tumors, pilar sheath acanthomas, trichofolliculomas, follicular hybrid cysts, cutaneous mixed tumors, steatocystomas, sebaceous hyperplasias, and sebaceomas. These results demonstrate that immunohistochemical study for calretinin may be helpful to identify the innermost cell layer of the outer root sheath in anagen hair follicle and the cutaneous adnexal proliferations showing differentiation toward this structure. Calretinin immunoreactivity supports eccrine differentiation in some sweat gland neoplasms, and it is also useful in identifying neoplasms with ductal sebaceous differentiation.     

Distribution of metallothionein in normal and pathological human skin

The expression and distribution of metallothionein (MT) in frozen sections of normal and pathological human skin was studied using the monoclonal antibody L2E3 directed against MT derived from human fetal liver. Immunohistochemical staining of normal fetal and adult skin revealed strong reactivity in basal keratinocytes of epidermis and outer hair root sheath, hair matrix cells and the secretory coil, but not the exocrine portion of eccrine glands; myoepithelial cells around apocrine sweat glands were similarly stained. In epidermal hyperplasia, variable numbers of suprabasal keratinocytes were stained, whereas in interface dermatitis, interrupted staining was found in the basal layer. Weak or scattered staining was observed in squamous tumours, whereas basal cell carcinomas did not show consistent staining. The distribution of MT in normal skin was in line with the germinative role of basal keratinocytes and hair matrix cells, whereas its distribution in hyperplastic epidermis was in line with experimental animal data, and reflected the increase in the germinative pool in these conditions. It is concluded that monoclonal antibody L2E3 may serve as a valuable immunohistochemical marker in diagnostic cutaneous pathology since it labels basal keratinocytes selectively, and since it discriminates between eccrine and apocrine sweat glands.     

Anti-keratin monoclonal antibody against basal cell epithelioma keratin: BKN-1

A BALB/c mouse was immunized with fibrous proteins (FP) extracted from basal cell epithelioma (BCE) and anti-keratin monoclonal antibodies were produced by a hybridoma technique with a mouse myeloma cell line. One monoclonal antibody was designated as BKN-1. Immunohistochemically, in 17 cases of BCE, the cytoplasm of all the tumor cells was always stained by BKN-1. In the normal human skin tissue, BKN-1 specifically reacted with the basal cells in the epidermis and in the infundibular epithelium of the hair follicle, the entire follicular cells below the isthmus portion in the anagen hair follicle, the peripheral cells of sebaceous glands, and sweat gland cells. The reaction of BKN-1 was immunoelectron microscopically located on the tonofilaments in the cytoplasm. By immunoblot analysis, BKN-1 stained either a band of 56–56.5K in FP from BCE or several bands in normal epidermal FP. These results suggest that the keratin expression of BCE may resemble that of the follicular epithelium below the isthmus portion.     

Human beta defensin-1 and -2 expression in human pilosebaceous units: upregulation in acne vulgaris lesions.

A rich residential microflora is harboured by the distal outer root sheath of the hair follicle and the hair canal - normally without causing skin diseases. Although the basic mechanisms involved in the development of inflammation during acne vulgaris remain unclear, microbial agents might play an important role in this process. In this study we have analyzed by in situ hybridization and immunohistochemistry the expression patterns of two antimicrobial peptides, human beta defensin-1 and human beta defensin-2, in healthy human hair follicles as well as in perilesional and intralesional skin of acne vulgaris lesions such as comedones, papules, and pustules. Strong defensin-1 and defensin-2 immunoreactivity was found in all suprabasal layers of the epidermis, the distal outer root sheath of the hair follicle, and the pilosebaceous duct. Marked defensin-1 and defensin-2 immunoreactivity was also found in the sebaceous gland and in the basal layer of the central outer root sheath including the bulge region. The majority of acne biopsies displayed a marked upregulation of defensin-2 immunoreactivity in the lesional and perilesional epithelium - in particular in pustules - and a less marked upregulation of defensin-1 immunoreactivity. The upregulation of beta-defensin expression in acne vulgaris lesions compared to controls suggests that beta-defensins may be involved in the pathogenesis of acne vulgaris.     

Desmoglein isotype expression in the hair follicle and its cysts correlates with type of keratinization and degree of differentiation

Within stratified squamous epithelia, such as the epidermis, desmogleins are generally expressed in a differentiation-specific manner. Similar to the epidermis, the hair follicle is compartmentalized into a hierarchy of cell types based on their level of differentiation. Relatively undifferentiated stem cells in the bulge can generate epidermis, sebaceous gland, and hair bulb matrix cells. The latter give rise to at least six different cell types that keratinize as they move up the hair shaft and inner root sheath. Here, we examined expression patterns of the desmoglein isotypes, desmogleins 1, 2, and 3 in the cutaneous epithelium, and discovered that desmoglein 1 and 2 expression correlated with the state of differentiation of defined populations within the hair follicle. Desmoglein 2 was highly expressed by the least differentiated cells of the cutaneous epithelium, including the hair follicle bulge of the fetus and adult, bulb matrix cells, and basal layer of the outer root sheath. In contrast, desmoglein 1 defined more differentiated cell populations, and was expressed in epidermal suprabasal cells, the inner root sheath, and the innermost layers of the outer root sheath. We found that the expression pattern of desmoglein 3 correlated with different types of keratinization. In areas of trichilemmal keratinization in the follicle, and in cysts arising from these areas, desmoglein 3 was expressed throughout all layers of the outer root sheath and cyst wall. In areas of epidermal-like keratinization, such as in the infundibulum and in epidermal inclusion cysts, desmoglein 3 expression was limited mainly to the basal layer. We conclude that desmoglein expression patterns define compartments of cells in similar states of differentiation within the cutaneous epithelium, and reveal a hierarchy of differentiation among these compartments.     

Immunohistochemical evidence for differential distribution of 5α-reductase isoenzymes in human skin

Antibodies raised against fragments of synthetic peptides of human 5α-reductase isoenzymes 1 (h5αrl) and 2 (h5αr2) were applied to paraffin sections of human skin (scalp, eyelid, lip, breast, scrotum). Immunoreactive sites were differentially distributed, in that h5αrl immunoreactivity was present in the nuclei of cells in the stratum germinativum (basal and lower portion of the spinous layer) of the epidermis, subepithelial tibroblasts, adipocytes, smooth muscle cells of the scrotal tunica dartos, basal cells of sebaceous glands, excretory duct cells of sweat glands, cells of the dermal papilla and fibrous and outer epithelial sheath of hair roots, as well as endothelial cells of small vessels and Schwann cells of cutaneous myelinated nerves. In contrast, immunoreactivity for h5αr2 was found in the cytoplasm of the cells of the spinous layer (and far less intensely in the basal layer) of the epidermis, subepidermal fibrocytes, and especially in subcutaneous adipocytes. Immunoreactivity was strongest in the non-keratinized portion of the inner epithelial sheath and the cuticle of hair follicles, whereas other portions of the hair root were negative. Sweat glands were stained, whereas sebaceous glands showed only weak diffuse immunoreactivily. In mucoculaneous zones, salivary glands and conjunctival epithelium showed immunoreactive cells. Vascular endothelium displayed immunoreactivity only in the genital region. We present experimental evidence for a differential distribution of 5α-reductase isoenzymes in human skin. This might reflect a diversity in the response of different areas of the skin to androgenic challenge.     

Location of HLA-A,B,C antigens in dendritic cells of normal human skin: an immunoelectron microscopic study

The distribution of the major histocompatibility antigens HLA-A,B,C, (HLA) on dendritic cells of normal human skin was studied by immunoelectron microscopy and a 4-step immunoperoxidase technique utilizing monoclonal antibodies. Light microscopy revealed peripheral staining for HLA of epidermal and pilar infundibular keratinocytes. In the epidermis, the staining was present from the basal layer to the upper stratum spinosum. In the follicles below the level of the infundibulum, HLA was detected only on rare intraepithelial dendritic cells. These dendritic cells could not be identified in the epidermis due to the HLA staining of the surrounding keratinocytes. Similar cells stained diffusely with anti-T6 antibody; the keratinocytes did not. Immunoelectron microscopy demonstrated: (1) the presence of HLA staining of keratinocyte membranes from the stratum basalis to the level of the upper stratum spinosum and in the pilar infundibulum, (2) the possible absence of HLA on melanocytes, (3) the presence of focal HLA staining of the membranes of epidermal and follicular dendritic cells that contained Birbeck granules and were, therefore, Langerhans cells, (4) dendritic mononuclear cells within the follicular epithelium, which although devoid of Birbeck granules, exhibited similar reactivity with anti-HLA antibody. These findings suggest that HLA antigens are present on the membranes of Langerhans cells, but are not demonstrable on melanocytes in normal human skin.     

Nicastrin基因突变的反常性痤疮患者皮损Notch-HES信号通路的表达

目的 检测nicastrin基因突变的反常性痤疮患者皮损标本中,nicastrin及其下游Notch-HES信号通路蛋白的表达。 方法 免疫组化法检测nicastrin及 Notch-HES信号通路分子在4例nicastrin基因突变的患者皮损石蜡标本的表达,并用6例正常皮肤组织作对照,同时采用Spearman相关分析,分析nicastrin与Notch-HES信号通路分子表达的相关性。 结果 Nicastrin蛋白广泛表达于表皮全层、皮肤附属器,如,毛囊皮脂腺单位、大汗腺及小汗腺。在携带nicastrin基因突变的患者皮损中,表皮及毛囊漏斗部nicastrin表达较正常对照明显减少;同时,Notch-HES信号通路分子表达亦较正常对照明显减少。Nicastrin蛋白与Notch1、Notch3以及HES-1的表达呈明显正相关（r分别为0.831、0.748、0.807,P值分别 < 0.01, < 0.05、 < 0.01）,而与Notch2、HES-5的表达之间的相关性,差异无统计学意义（r分别为0.597和0.591,均P > 0.05）。 结论 Nicastrin基因突变患者的皮损中nicastrin低表达,且与多种Notch-HES信号通路分子表达呈正相关,提示nicastrin表达减少可能通过影响下游Notch-HES信号通路的表达参与反常性痤疮的发病。     

Immunofluorescence analysis of the basement membrane zone components in human anagen hair follicles

The ultrastructure and constituent components of the basement membrane zone (BMZ) of the interfollicular epidermis have been well characterized. However, little is known about the junctions between dermal papilla and the surrounding epithelial cells of the hair bulb, as well as those junctions between connective tissues and epithelial cells outside the hair follicle. In the present study, immunofluorescence was used to determine the expression of various BMZ components, particularly plectin, BP230, BP180, alpha6beta4 integrin, laminin 5 and type VII collagen, in anagen hair follicles from human scalp. All the BMZ components examined showed essentially the same immunofluorescence staining pattern. Specifically, staining of the upper portion of the hair follicle demonstrated expression of all BMZ components with a labeling intensity similar to that found in the interfollicular epidermis. Staining in the lower portion of the hair follicle, however, was markedly different: all the BMZ components showed a gradual decrease in staining intensity. Particularly, outside the hair bulb, the linear staining was diminished and even discontinuous in some areas. Finally, between dermal papilla and epithelial cells inside the hair bulb, there was a strong immunoreactivity for all the BMZ components except for BP230, which was completely negative. The present study also confirmed a previous reported ultrastructural finding that hemidesmosomes are not apparent in the hair bulb's exterior BMZ nor in the dermal papilla junctions. Instead, peculiar cloudy materials were seen in both the lamina densa and the adjacent epithelium outside the hair bulb. Taken together, the diminished expression of all the BMZ components outside the hair bulb, as well as the complete absence of BP230 at the dermal papilla junction, seem to be responsible for the incomplete ultrastructure of hemidesmosomes in these regions. Furthermore, the results in the present study led us to speculate that the expression of BMZ components inside and outside the hair bulb are markedly decreased in the transient regions of the hair follicle as compared with their expression in the permanent region, signified by the upper portion of the hair follicle. When the hair follicle moves upward in catagen or downward in anagen, the complete structure of the hemidesmosome may stabilize the upper portion to the surrounding connective tissues, while the incomplete hemidesmosome may facilitate the movement of the transient region.     

A niche in the spotlight: Could external factors critically disturb hair follicle homeostasis and contribute to inflammatory hair follicle diseases?

The anatomy of the hair follicle and the dynamics of its barrier provide a special space for interactions between macromolecules and the underlying tissue. Translocation across the hair follicle epithelium and immune recognition has been confirmed for proteins, nucleic acids, engineered particles, virus particles and others. Tissue responses can be modulated by pro-inflammatory stimuli as demonstrated in penetration and transcutaneous immunization studies. Even under physiological conditions, hair follicle openings are filled with exogenous material ranging from macromolecules, engineered particles to natural particles including diverse communities of microbes. The exposed position of the infundibulum suggests that local inflammatory insults could disturb the finely tuned balance and may trigger downstream responses that initiate or facilitate local outbreaks of inflammatory hair diseases typically occurring in close spatial association with the infundibulum as observed in cicatricial alopecia. The question as to how microbial colonization or deposition of contaminants on the surface of the hair follicle epithelium interact with the barrier status under the influence of individual predisposition may help us understand local flare-ups of inflammatory hair diseases. Specifically, learning more about skin barrier alterations in the different types of inflammatory hair diseases and cross-talk with exogenous compounds could give new insights in this less explored aspect of hair follicle homeostasis. Such knowledge may not only be used to develop supportive measures to maintain a healthy scalp. It may have wider implications for our understanding on how external factors influence inflammation and immunological responses in the skin.     

Multiple tumors of follicular infundibulum with sweat duct differentiation

A 67-year-old man is reported with multiple tumors of follicular infundibulum containing ducts. Approximately 30 hypopigmented, scaling macules and minimally elevated papules were present on the face. Skin biopsy specimens from 5 representative lesions revealed similar findings. There was a proliferation of ramifying strands of pale-staining keratinocytes in the upper dermis showing connections with follicular infundibula of vellus follicles and epidermis. There was evidence of hair follicle differentiation with small follicular bulbs, papillary mesenchymal bodies, keratocysts, and occasional hair shafts in the tumor. These findings are characteristic of prior reports of TFI. Ducts were also present within the epithelial cords. Carcinoembryonic antigen, gross cystic disease fluid protein-15, epithelial membrane antigen, and S-100 protein were identified within the tumor. We theorize that the ductal elements within these TFI reflect the multipotential differentiating capacity of portions of infundibular epithelium.
Horn TD, Vennos EM, Bernstein BD, Cooper PH. Multiple tumors of follicular infundibulum with sweat duct differentiation.     

Activity of 17β-hydroxysteroid dehydrogenase in various tissues of human skin

The activity of 17β-hydroxysteroid dehydrogenase (17β-HSD) was assayed in various tissues microdissected from the freeze-dried human skin of fourteen subjects. The apocrine sweat gland, sebaceous gland and hair follicle possessed a high activity of 17β-HSD. The enzyme activity was negligible in the epidermis, except that the scalp epidermis showed much the same activity as the hair follicle. The dermis showed variable activity because of contamination with other components.     

TGF-alpha is widely expressed in differentiated as well as hyperproliferative skin epithelium

Transforming growth factor-alpha (TGF-alpha) is a potent mitogen for epithelial cells that is expressed at low levels in normal epidermis and overexpressed in psoriasis. Epidermal growth factor (EGF) has been shown to inhibit hair growth but stimulate the growth of sebaceous and sweat glands, suggesting a potential role for a member of the EGF/TGF-alpha family in the normal development and function of skin appendages as well as epidermis. The present work demonstrates TGF-alpha protein in eccrine ducts, and eccrine, sebaceous, and apocrine glands. The proliferative dermal hair bulb does not express TGF-alpha in contrast to the differentiated outer root sheath hair follicle epithelia. In addition, hyperproliferative skin diseases including bullous congenital ichthyosiform erythroderma, squamous cell carcinoma, and psoriasis show increased TGF-alpha expression. Thus, TGF-alpha may play a role in the morphogenesis and function of normal skin appendages and its overexpression is common in benign and malignant hyperproliferative skin diseases.