In-vitro DNA synthesis of keratinocytes in normal human skin, psoriasis, seborrhoeic keratosis, Bowen's disease and basal cell carcinoma

Protection of rabbits against cutaneous papillomavirus infection using recombinant tobacco mosaic virus containing L2 capsid epitopes

Cottontail rabbit papillomavirus (CRPV) and rabbit oral papillomavirus (ROPV) represent distantly related, cutaneous and mucosal tissue tropic papillomaviruses respectively that can infect the same host. These two viruses were used to test the effectiveness of an L2 peptide-based vaccine (aa 94-122) that was delivered on the surface of recombinant tobacco mosaic virus (rTMV) particles. Groups of NZW rabbits received combinations of CRPVL2, ROPVL2 and CRPV+ROPVL2 rTMV vaccines, and were then challenged with infectious CRPV and ROPV. The rabbits developed antibodies that reacted to whole L2 protein and these sera were able to neutralize CRPV pseudovirions at half-maximal titers that were between 50 and 500. Rabbits receiving the CRPV L2 vaccine alone or in combination with ROPV L2 vaccines were completely protected against CRPV infections. Those rabbits vaccinated with the ROPV L2 vaccines showed a weak response in some rabbits against CRPV infection. These studies demonstrate that L2-based vaccines provide strong protection against experimental papillomavirus infection that is most likely based upon the induction of virus-neutralizing antibody. Notably, we observed some limited cross-protection induced by the L2 sequences tested in these vaccines. Finally, the study demonstrated that rTMV were excellent agents for the induction of strong protection in a pre-clinical disease model of papillomavirus infection.

Structure and function of human sweat glands studied with histochemistry and cytochemistry

The basic structure and the physiological function of human sweat glands were reviewed. Histochemical and cytochemical techniques greatly contributed the elucidation of the ionic mechanism of sweat secretion. X-ray microanalysis using freeze-dried cryosections clarified the level of Na, K, and Cl in each secretory cell of the human sweat gland. Enzyme cytochemistry, immunohistochemistry and autoradiography elucidated the localization of Na,K-ATPase. These data supported the idea that human eccrine sweat is produced by the model of N-K-2Cl cotransport. Cationic colloidal gold localizes anionic sites on histological sections. Human eccrine and apocrine sweat glands showed completely different localization and enzyme sensitivity of anionic sites studied with cationic gold. Human sweat glands have many immunohistochemical markers. Some of them are specific to apocrine sweat glands, although many of them stain both eccrine and apocrine sweat glands. Histochemical techniques, especially immunohistochemistry using a confocal laser scanning microscope and in situ hybridization, will further clarify the relationship of the structure and function in human sweat glands.

CD1a+, CD3+, CD4+, CD8+, CD68+ and cutaneous lymphocyte-associated antigen-positive cells in Bowen's disease

BACKGROUND

Bowen's disease (BD) is a squamous cell carcinoma in situ that rarely invades into the underlying dermis. However, little is known about its immunohistology. Objectives To evaluate the relationship between the cytological properties of the tumour cells in BD and the host immune response.

METHODS

We examined the expression of p53, proliferating cell nuclear antigen (PCNA) and Ki67 antigen, and the number of mitotic cells, together with the number of intratumoral and dermal infiltrating CD1a+, CD3+, CD4+, CD8+, CD68+ and cutaneous lymphocyte-associated antigen (CLA)+ cells in 18 cases of genital BD.

RESULTS

When compared with normal genital skin (n = 10), there was a significantly higher number of mitotic cells as well as higher expression of p53+, PCNA+ and Ki67+ cells in BD. There was significant mutual correlation between CD3+, CD4+ and CD68+ cells in the tumoral epidermis. The number of CD1a+ Langerhans cells significantly decreased in BD epidermis; however, dermal CD1a+ cells were increased. Interestingly, numbers of dermal CD1a+ cells significantly correlated with those of intratumoral CD3+, CD4+ and CD68+ cells. In situ hybridization for human papillomavirus (HPV) demonstrated that HPV-infected BD had significantly less infiltration of intratumoral CD3+ cells and CLA+ cells.

CONCLUSIONS

The present data suggest that dermal CD1a+ cells may participate in the immune surveillance and that HPV infection may interfere with the intratumoral infiltration of CLA+ cells in BD.

The proliferative properties of tumor cells differentially correlate with the host immune responses in anogenital Bowen's disease

Bowen's disease is a squamous cell carcinoma in situ that rarely invades into the underlying dermis. In order to evaluate the relationship between the cytological properties of the tumor cells and the host immune response, we have examined the expression of p53 and proliferating cell nuclear antigen (PCNA), and the number of mitotic cells, clumping cells, koilocytes, Langerhans cells (LCs) and dermal lymphoid cell infiltration in 18 cases of anogenital Bowen's disease. When compared with normal anogenital skins (n = 10), a statistically significant number of p53-positive cells, PCNA-positive cells, mitotic cells, clumping cells, koilocytes and dermal lymphoid cells was observed in the cases of Bowen's disease. Importantly, there existed a very strong correlation between the number of PCNA-positive tumor cells and the number of infiltrated dermal lymphoid cells. Moreover, the number of mitotic cells significantly correlated with the number of intratumoral LCs. The in situ hybridization technique for human papilloma virus (HPV) demonstrated that the HPV-infected Bowen's disease showed a similar histological and immunohistological pattern as the HPV-non-infected counterparts, except for increased koilocyte formation and decreased p53 positivity. The present data suggest that the proliferative activity of Bowen's disease significantly correlates with the host immune reaction, and that the host immune system may differentially recognize the different cytological properties of tumor cells in the Bowen's disease.

Serum-free conditions for the long term growth and differentiation of neoplastic canine keratinocytes

Long term cultures of canine keratinocytes have been established but culture conditions currently used require supplementation with fetal bovine serum (FBS). Unfortunately, FBS contains many non-defined components which may interfere with in vitro studies. This study describes the development of defined serum-free culture conditions for neoplastic canine keratinocytes grown submerged and at the air-liquid interface. Two commercially available serum-free media established for human epidermal cells failed to support canine keratinocyte growth. In contrast, a defined serum-free medium developed in our laboratory successfully supported proliferation of neoplastic canine keratinocytes for at least 40 passages. Cells showed a slower growth rate, but reached similar final densities and were morphologically identical to those cultured in FBS. Grown at the air-liquid interface, the cells reached the same degree of differentiation as in vivo stratified squamous epithelium and cultures grown in FBS. These results demonstrate that canine keratinocytes require different serum-free growth conditions than human cells. Neoplastic canine keratinocyte cultures, grown under serum-free culture conditions, provide an ideal in vitro system for comparative studies of keratinocyte biology and pathogenesis of various dermatoses.

Novel method to investigate kinetics of rat skin cells by means of an occlusive dressing method using bromodeoxyuridine

We developed a novel technique to detect S-phase skin cells by applying bromodeoxyuridine (BrdU) epicutaneously using an occlusive dressing (OD) method. BrdU was scarcely absorbed from the skin with a simple epicutaneous application, whereas the incorporation of BrdU was very well promoted with the use of our OD method. We applied BrdU on the backs of rats using this method and investigated the conditions required for an optimal response, with a special focus on the period of application, the concentration of BrdU used and vehicles suitable for the immunocytochemical staining of this agent. From these experiments, we were able to determine that an application time of at least 60 min was necessary to liable S-phase cells, a 2% concentration of BrdU was needed to obtain consistent labeling and aqueous vehicles are satisfactory solvents for BrdU preparations. Epidermal keratinocytes and S-phase cells in the upper portion of dermis were clearly labeled after either intraperitoneal injection of BrdU or after administration by means of the OD method. To ascertain whether this latter method could provide an effective alternative to intraperitoneal injection, we compared the labeling patterns of both methods with respect to the speed of migration of BrdU-labeled basal cells from the basal layer to the horny layer of epidermis. Using either of these two methods, basal keratinocytes were labeled immediately after administration. Three days after the first administration, BrdU-labeled cells were detected in the middle layer of the epidermis, but after 8 days, they were no longer evident in epidermal tissue. As another means of comparing both methods, we used antibody to proliferating cell nuclear antigen (PCNA) and compared the ratio of PCNA-positive basal cells to BrdU-labeled basal cells. The number of PCNA-positive cells was about 4.6 times greater than the number of BrdU-labeled basal cells by both methods. We concluded that the OD method could be used as a substitute for intraperitoneal injection in order to observe cell kinetics using bromodeoxyuridine.

Bcl-2 overexpression in basaloid proliferations overlying dermatofibromas and basal cell carcinomas

Basaloid proliferations overlying dermatofibromas resembling superficial basal cell carcinomas have been interpreted both as reactive/regressive and frankly malignant. Basal cell carcinoma is a slow-growing tumour, which so far has been regarded as an actively proliferating lesion with a high apoptotic activity. We examined immunohistochemically 6,dermatofibromas with overlying simple hyperplasia, 12 dermatofibromas with overlying basaloid proliferations, and 24 basal cell carcinomas for expression of Ki-67 protein, and bcl-2 protein. The Ki-67 labelling index represents an estimate of proliferative activity. Bcl-2 protein suppresses apoptosis. The Ki-67 labelling indexes of basaloid proliferations, basal cell carcinomas, and normal epidermis were similar (11-15%, p < 0.05, Mann-Whitney test). Bcl-2 protein was expressed in all cells of basaloid proliferations, similar to the expression pattern in basal cell carcinomas. We suggest that basaloid proliferations overlying dermatofibromas might have achieved a phenotype that equals an early stage of BCC carcinogenesis.

Bromodeoxyuridine: a diagnostic tool in biology and medicine, Part III. Proliferation in normal, injured and diseased tissue, growth factors, differentiation, DNA replication sites and in situ hybridization

This paper is a continuation of parts I (history, methods and cell kinetics) and II (clinical applications and carcinogenesis) published previously (Dolbeare, 1995 Histochem. J. 27, 339, 923). Incorporation of bromodeoxyuridine (BrdUrd) into DNA is used to measure proliferation in normal, diseased and injured tissue and to follow the effect of growth factors. Immunochemical detection of BrdUrd can be used to determine proliferative characteristics of differentiating tissues and to obtain birth dates for actual differentiation events. Studies are also described in which BrdUrd is used to follow the order of DNA replication in specific chromosomes, DNA replication sites in the nucleus and to monitor DNA repair. BrdUrd incorporation has been used as a tool for in situ hybridization experiments.

Prognostic value of Ki67 antigen expression in basal cell carcinomas

Recurrence of basal cell carcinoma (BCC) following treatment is a common event and long-term follow-up of all patients presenting with a primary BCC has been recommended. Proliferation indices have been recognized as important prognostic factors in several tumour types in a variety of cancer systems, being significantly elevated in more aggressive lesions. We have examined 51 BCCs (17 non-recurrent tumours [group 1], 17 original tumours which later recurred [group 2-O], and the corresponding 17 recurrent specimens [group 2-R]) for Ki67 antigen expression, a proliferation-associated antigen using immunohistochemistry with the monoclonal antibody MIB1. There was a significant increase in the percentage positive for MIB1 in the Group 2-O as compared with the group 1 BCCs (P < 0.05). p53 protein expression, as assessed by immunohistochemistry with the monoclonal antibody DO7, was similar in each group. These results show that Ki67 antigen expression differs between BCCs which later recur and BCCs that do not recur.

Proliferating activity of the hair follicular melanocytes at the early and anagen III stages in the hair growth cycle: detection by immunocytochemistry for bromodeoxyuridine combined with DOPA reaction cytochemistry

In order to demonstrate the existence of proliferating activity in hair follicular melanocytes during the early and anagen III stages, immunocytochemistry for bromodeoxyuridine (BrdU) incorporated in the nuclei of the melanocytes for 1 hr was undertaken at the light and electron microscopic levels in combination with DOPA reaction cytochemistry. Light microscopically, about 30% of the nuclei of the DOPA reaction positive melanocytes at the anagen III stage of the hair growth cycle were labeled by anti-BrdU antibody. These melanocytes were observed in about one hundred hair follicles. Electron microscopically, the nuclei of a few undifferentiated melanocytes at the anagen II stage were labeled by anti-BrdU antibody-affiliated secondary antibody-gold particles. At the anagen III stage, localization of the immunogold particles in the DNA replication domains of the nuclei of the undifferentiated and redifferentiating melanocytes covered the patterns of the early, middle, and late S-phase. These findings suggest that the hair follicular melanocytes begin proliferation at the anagen II stage and that the melanocytes proliferate actively at the anagen III stage to repopulate the hair matrix during subsequent hair growth.

Use of in situ detection of histone mRNA in the assessment of epidermal proliferation: comparison with the Ki67 antigen and BrdU incorporation

The labelling index is commonly used as a measure of proliferation. However, the use of tritiated thymidine or BrdU labelling of S-phase cells is limited to prospective samples. We have employed an oligonucleotide cocktail complementary to the mRNA species encoding the replication-dependent histones H2B, H3 and H4 for non-isotopic in situ hybridization (NISH), and have compared the resultant proliferation indices in normal skin with those obtained by bromodeoxyuridine (BrdU) incorporation and by Ki67 immunohistochemistry (IHC) using the monoclonal antibody MIB1. In addition, we compared the staining characteristics of histone NISH and Ki67 IHC in a further 25 samples from a variety of inflammatory dermatoses and neoplastic conditions, as well as from normal skin. In normal skin, S-phase (histone NISH and BrdU) and cycling (Ki67) cells were confined to the basal and low suprabasal layers. The labelling indices determined by histone NISH and BrdU incorporation were similar, whereas that of Ki67 IHC was four times greater. In biopsies from hyperproliferative dermatoses and dysplastic or malignant lesions, the number of histone NISH- and Ki67 IHC-positive cells was generally elevated; in accordance with the differential expression of these two markers during the cell cycle, MIB1 consistently gave higher results. The advantage of histone NISH over Ki67 IHC is that it is a marker of the same part of the cell cycle as BrdU incorporation. However, the combined use of both histone NISH and Ki67 IHC to measure two cell cycle parameters, namely S-phase and the number of cycling cells, allows more detailed retrospective study of epidermal proliferation than has been possible previously.

A histological study of cutaneous thermal wounds using a Clostridium perfringens-derived wound healing substance with wound healing stimulation activity

We studied the effects of a Clostridium perfringens-derived wound-healing substance (WHS) on the healing of thermal burn wounds. Third-degree burn injuries were inflicted on the back skin of rats. We histologically evaluated the effects of WHS ointments and compared them with those of lysozyme chloride ointment. We observed the formation of dermal collagen fibers and the increase of capillaries in the WHS ointment treated groups. From the results of hematoxylin and eosin staining and silver staining, an increase in capillaries was observed one week after the application of WHS ointment. Three weeks after the application, when the epithelization was in the final stage, capillary formation ceased. In the WHS ointment-applied groups, electron microscopic observation showed that new collagen fibers were regularly formed in the dermis. On the other hand, in the lysozyme chloride ointment-applied groups, new collagen fibers were present, but were irregularly formed. The main wound healing stimulative action of the WHS ointment could be due to its acceleration of new capillary formation.

Proliferating cell nuclear antigen (PCNA) and p53 protein expression in Bowen's disease

Bowen's disease is a premalignant dermatosis comprised of a clonal proliferation of atypical keratinocytes in the full thickness of the epidermis. To elucidate the relationship between the alteration of the p53 tumor suppressor protein and cell proliferation rate, we immunohistochemically examined the expression of proliferating cell nuclear antigen (PCNA) and p53 protein in 30 cases of Bowen's disease. All the cases exhibited the full-thickness distribution of PCNA-positive cycling cells in the lesional epidermis. Quantitation of PCNA staining by image cytometry revealed a mean labeling index (LI) of 75.1 +/- 20.3. p53 expression was detected in 13 cases (43%). Expression was diffuse (p53 LI > 50) in 9 cases, but focal (p53 LI < 30) in the other four. The mean PCNA LI of p53 diffusely positive cases was significantly greater than that of both p53 focally positive and p53 negative cases (89.3 +/- 10.1 vs 62.7 +/- 21.2, and 70.5 +/- 21.6; p < 0.01, respectively). These findings suggest that a high-level accumulation of p53 protein results in a more increased cell proliferation in Bowen's disease.

Comparative analysis of normal and psoriatic skin both in vivo and in vitro

The morphological and biochemical characteristics of psoriasis are well documented, but the pathogenesis of this disease is not clearly understood. A variety of in vitro models of psoriasis have been developed in attempts to identify the trigger factors, but no model so far reproduces the stable psoriatic phenotype accurately. In the present work, we initially checked the immunohistochemical distribution of proliferation/differentiation markers in psoriatic skin in vivo, and our results largely confirm previously reported data. However the study was performed using a new series of monoclonal antibodies to keratin. Subsequently we took normal or psoriatic skin biopsies, reconstructed skin equivalents using a recently described model and analysed the proliferation/differentiation status of the resulting epidermis. Dramatic morphological and antigenic differences were found between normal and psoriatic skin in vivo, but whatever the source of the initial biopsy, a unique in vitro phenotype was obtained in the reconstructed epidermis. This phenotype was marked by mild hyperproliferation and an altered distribution of differentiation-associated antigens suggesting a need for extracutaneous stimuli to maintain the psoriatic phenotype in vitro.

Expression of proliferation-associated proteins (proliferating cell nuclear antigen and Ki-67 antigen) in Bowen's disease

Bowen's disease and invasive squamous cell carcinoma arising in Bowen's disease (Bowen's carcinoma) were investigated immunohistochemically with regard to their expression of proliferating cell nuclear antigen (PCNA) and the Ki-67 antigen. Both proliferation-associated proteins were found in all layers of the tumours, and were present in nuclei of any size and shape. The nucleoli lacked PCNA immunoreactivity, but they expressed the Ki-67 antigen. The PCNA labelling index was 36.9 +/- 12.6% in Bowen's disease (n = 16), and 40.7 +/- 11.0% in Bowen's carcinoma (n = 3). The Ki-67 antigen labelling index was 43.6 +/- 16.7% in Bowen's disease (n = 16), and 51.7 +/- 11.6% in Bowen's carcinoma (n = 3). Dyskeratotic cells were positive for PCNA and the Ki-67 antigen, suggesting that these cells are not in a post-mitotic state. We conclude that in dyskeratotic cells of Bowen's disease the cell cycle is interrupted by nuclear disorganization.

Cellular kinetics and lectin distribution in hamster buccal carcinomas

As part of an evaluation of the progression to malignancy, the cellular kinetics of DMBA-induced tumors in the buccal mucosa of hamsters were examined using 5-bromodeoxyuridine (BrdU), peanut agglutinin (PNA), Ulex europaeus agglutinin I (UEA-I) and wheat germ agglutinin (WGA). BrdU-positive cells were localized in the basal layer in both normal and hyperplastic epithelium, whereas they were distributed from the basal to the prickle cell layer in squamous cell carcinoma (SCC). The extent of BrdU labeling increased as the tissues progressed towards malignancy. PNA and UEA-I showed binding only in the prickle cell layer of normal and hyperplastic epithelium, and WGA showed binding mainly in the prickle cell layer. However, in SCC, PNA and UEA-I showed no binding in the prickle cell layer and WGA binding was observed throughout the epithelium. A study of cellular kinetics using BrdU labeling and the lectin binding pattern may be useful in the evaluation of tissue changes on the way to malignancy.