Apoptosis and cutaneous biology

Step-by-Step Regeneration of Tentacles after Injury in Anemonia viridis-Morphological and Structural Cell Analyses

Benthic marine invertebrates, such as corals, are often subjected to injury caused by several sources. Here, the differences and characteristics in injured and health tissues in terms of cellular components are shown through a histological investigation of the soft coral Anemonia viridis at 0 h, 6 h, 24 h, and 7 days after injury caused by tentacle amputation. In addition, a new tool was used for the first time in invertebrates, positron emission tomography, in order to investigate the events that occur during regeneration within a longer time period (0 h, 24 h, and 14 days after the tentacles were cut). Higher integrated density values were measured through a densitometric analysis in sections stained with Fontana-Masson at 24 h after the tentacles were cut. This suggests an increase in melanin-like containing cells and a subsequent increase in fibroblast-like cells differentiated by amoebocytes that converge to the lesion site in the early stages of inflammation and regeneration. This work provides, for the first time, an elucidation of the events that occur during wound-healing and regeneration in basal metazoan, focusing on the characterisation of immune cells and their role. Our results indicate that Mediterranean anthozoan proves to be a valuable model for studying regeneration. Many events highlighted in this research occur in different phyla, suggesting that they are highly conserved.

Once the Light Touch to the Brain: Cytotoxic Effects of Low-Dose Gamma-Ray, Laser Light, and Visible Light on Rat Neuronal Cell Culture

OBJECTIVE

We aimed to evaluate the effects of gamma-ray, laser light, and visible light, which neurons are commonly exposed to during treatment of various cranial diseases, on the viability of neurons.

MATERIALS AND METHODS

Neuronal cell culture was prepared from the frontal cortex of 9 newborn rats. Cultured cells were irradiated with gamma-ray for 1-10 min by (152)Eu, (241)Am, and (132)Ba isotopes, visible light for 1-160 min, and laser light for 0.2-2 seconds. The MTT tetrazolium reduction assay was used to assess the number of viable cells in the neuronal cell cultures. Wavelength dispersive X-ray fluorescence spectrometer was used to determine Na, K, and Ca levels in cellular fluid obtained from neuronal cell culture plaques.

RESULTS

Under low-dose radiation with (152)Eu, (241)Am, and (132)Ba isotopes, cell viability insignificantly decreased with time (p>0.05). On the other hand, exposure to visible light produced statistically significant decrease in cell viability at both short- (1-10 min) and long-term (20-160 min). Cell viability did not change with 2 seconds of laser exposure. Na, K, and Ca levels significantly decreased with gamma-ray and visible light. The level of oxidative stress markers significantly changed with gamma-ray.

CONCLUSION

In conclusion, while low dose gamma-ray has slight to moderate apoptotic effect in neuronal cell cultures by oxidative stress, long-term visible light induces remarkable apoptosis and cell death. Laser light has no significant effect on neurons. Further genetic studies are needed to clarify the chronic effect of visible light on neuronal development and functions.

TUNEL assay to characterize acute histopathological injury following treatment with the active and deep FX fractional short-pulse CO2 devices

BACKGROUND

This is a report of the histopathological evaluation of the acute damage profile in human skin following treatment with two novel short-pulsed fractional carbon dioxide resurfacing devices used independently and in combination in vivo.

METHODS

The panni of eight abdominoplasty patients were treated with either the Active FX, the Deep FX (Lumenis Ltd., Yokneum, Israel), or a combination of the two (Total FX) prior to the start of the excisional surgical procedure. Multiple combinations of energies, pulse widths, and densities were evaluated for each device. After surgical removal (two to five hours), each pannus was immediately biopsied and samples were processed for histopathological evaluation.

RESULTS

The Active FX system resulted in extensive epidermal injury with wide shallow ablation craters that, at higher fluences, extended through the basement membrane of the epidermis into the papillary dermis. The Deep FX fractional treatment caused deep microcolumns of ablation penetrating up to 3 to 4 mm from the epidermal surface into the deep reticular dermis with a variable rim of coagulated collagen surrounding each ablation column.

CONCLUSIONS

The in vivo histopathological evaluation of these devices furthers our understanding of the fundamental laser/tissue interaction following treatment with each device independently and in combination.

Prevalence of apoptotic epidermal keratinocytes in eosinophilic dermatoses of the cat: a retrospective light-microscopic study of 145 skin-biopsy specimens

A retrospective light-microscopic study was performed on skin-biopsy specimens from 145 cats with eosinophilic inflammatory dermatoses in order to determine the prevalence of apoptotic epidermal keratinocytes (AKs), the prevalence of eosinophils in close proximity to AKs, and whether there was a difference in the prevalence of AKs or the prevalence of eosinophils in close proximity to AKs based on histopathological reaction pattern. Overall, 62/145 (43%) specimens had AKs. Of the cases in which AKs were seen, 18% had eosinophils in close proximity to the AKs. The specimens were divided into three groups based on histopathological reaction pattern: perivascular-to-interstitial, diffuse, and nodular. No difference in the prevalence of AKs was found among the three histological groups. Because the sample size containing eosinophils in close proximity to AKs was too small to compare the three histological patterns individually, nodular and non-nodular patterns were compared. No difference in the presence of eosinophils in close proximity to AKs was found in these two subsets. More AKs were present if eosinophils were in close proximity to the AKs (range 1-9 with eosinophils near compared to 0-7 without).

Frequency of apoptotic keratinocytes in the feline epidermis: a retrospective light-microscopic study of skin-biopsy specimens from 327 cats with normal skin or inflammatory dermatoses

A retrospective light-microscopic study was performed on 294 biopsy specimens of haired skin from cats with various feline inflammatory dermatoses and specimens from cats with normal skin. Conditions expected to frequently have apoptotic epidermal keratinocytes (AKs) (including erythema multiforme, systemic lupus erythematosus, thymoma-associated exfoliative dermatitis, solar dermatitis, and viral dermatopathies) were found to have significantly more AKs than other types of inflammatory dermatoses. Nevertheless, we found more than two AKs in many skin-biopsy specimens from inflammatory conditions not expected to have frequent AKs (especially those from ectoparasitic dermatoses). Only a single AK was found in 1/33 cats with normal skin.

Topical isoflavones provide effective photoprotection to skin

BACKGROUND/PURPOSE

Isoflavones, one main group of phytoestrogens, have antioxidative and photoprotective effects in cellular and mouse studies. The aim of this study is to obtain a more comprehensive understanding of the isoflavone-mediated photoprotection with the pig skin model, a more human-resembling model.

METHODS

The pig skin was treated with five well-known isoflavone compounds (genistein, equol, daidzein, biochanin A, and formononetin) and one antioxidant combination solution of 15% vitamin C and 1% vitamin E and 0.5% ferulic acid (CEF) daily for 4 days. Skin was irradiated with solar-simulated UV irradiation, 1 to 5 minimal erythema dose (MED) at 1-MED intervals. Evaluation was carried out 24 h later by colorimeter-measured erythema and sunburn cell numbers.

RESULTS

Topical application of 0.5% solutions of three individual phytoestrogens - genistein, daidzein, biochanin A - are better than similar solutions of equol or formononetin in protecting pig skin from solar-simulated ultraviolet (SSUV)-induced photodamage, as measured by sunburn cell formation and/or erythema. However, the protection was less than that provided by a topical combination antioxidant standard containing 15% L-ascorbic acid, 1%alpha-tocopherol, and 0.5% ferulic acid.

CONCLUSION

Isoflavones provide effective photoprotection and are good candidate ingredients for protection against ultraviolet (UV) photodamage.

Apoptosis, P53 and Bcl-2 expression in response to topical calcipotriol therapy for psoriasis

BACKGROUND

The histopathologic changes characteristic of psoriasis might be related to suppressed apoptosis. The P53 and Bcl-2 proteins play a central role in the regulation of apoptosis. This study aimed to evaluate P53 and Bcl-2 expression and apoptotic cells in the psoriatic skin before and after topical calcipotriol therapy.

METHODS

Skin biopsies were obtained from nonlesional and lesional skin of 10 patients with generalized plaque psoriasis before and after treatment with topical calcipotriol ointment. The P53 and Bcl-2 expression was evaluated using immunoperoxidase technique and apoptotic cells by the terminal deoxynucleotide transferase (TdT) mediated deoxyuridine triphosphate nick end labeling (TUNEL) method.

RESULTS

After topical calcipotriol therapy, keratinocytes of psoriatic skin showed significant decrease of P53 (P = 0.002) and increase of Bcl-2 (P = 0.01) expression. On the other hand lymphocytes showed significant decrease of Bcl-2 (P = 0.01). There were no apoptotic cells before treatment but after calcipotriol therapy, apoptosis was more detectable in keratinocytes than in lymphocytes.

CONCLUSIONS

The results of the study suggested that one of the actions of calcipotriol in psoriasis might be exerted through induction of apoptosis, especially of keratinocytes, through a P53-independent pathway. Meanwhile, suppression of Bcl-2 expression in lymphocytes may promote apoptosis of dermal lymphocytes leading to healing of psoriasis.

The effects of calcipotriol and methylprednisolone aseponate on bcl-2, p53 and ki-67 expression in psoriasis

OBJECTIVE

The decrease of physiological apoptosis in the psoriatic lesions is thought to be involved in the pathogenesis of psoriasis, and induction of apoptosis was shown to contribute to the regression of psoriatic hyperplasia. In the present study, we compared the effects of calcipotriol and methylprednisolone aseponate (MPA) treatments on bcl-2, p53 and ki-67 expressions in psoriatic patients in order to define a relationship between regulation of apoptosis and healing process in psoriasis.

METHODS

Thirty psoriatic patients with stable and moderate chronic plaque psoriasis applied either calcipotriol or MPA ointment for 6 weeks twice daily. Evaluation of bcl-2, p53 and ki-67 positivity was performed at baseline and was repeated at sixth week for each therapy.

RESULTS

The mean percentage of positive keratinocytes was 8.63 +/- 7.15% for p53, 20.66 +/- 14.45% for ki-67, and 3.74 +/- 2.83% for bcl-2 in psoriatic skin at baseline. Normal skin values were 3.27 +/- 3.21% for p53, 4.93 +/- 4.77% for ki-67, and 1.80 +/- 0.41% for bcl-2. The psoriatic skin showed higher ki-67 (P < 0.05) and bcl-2 (P < 0.05) expression rates when compared to normal skin. The p53 positivity observed in psoriatic skin and normal skin was not significantly different (P > 0.05). Following calcipotriol and MPA treatments, there was a significant reduction in p53 and ki-67 positivity accompanied by an increase in bcl-2 positivity (P < 0.05 each). No significant differences were found at sixth week between calcipotriol and MPA groups with respect to p53, ki-67 and bcl-2 positivity (P > 0.05). The post-treatment psoriatic skin showed lower expression of p53, higher expressions of ki-67 and bcl-2 when compared to normal skin (P < 0.05 each).

CONCLUSION

The results of this study provide evidence that both calcipotriol and MPA decrease the p53 and ki-67 expression and increase bcl-2 expression. However, it should further be elucidated if these changes were the common behaviour of psoriatic keratinocytes to any antipsoriatic medication.

Nevi and melanoma in pregnancy

The influence of pregnancy on melanocytic nevi and malignant melanoma (MM) continues to be a controversial issue. Over the past 50 years, case reports and uncontrolled studies have suggested that nevi are more likely to become malignant during pregnancy, and MM diagnosed during pregnancy has a poor prognosis. Clinical and laboratory observations suggested that pregnancy-associated hormones may influence nevi and MM. Recent clinical and laboratory evidence suggests, however, that pregnancy does not influence the prognosis of MM, nor does it seem to cause significant changes in nevi. A clear link between hormones and MM has not been established. An analysis of this evidence is presented along with practical recommendations for the patient.

Apoptosis mediated by cytolytic molecules might be responsible for maintenance of psoriatic plaques

Psoriasis is a chronic hyperproliferative skin disease characterized by keratinocyte hyperproliferation and inflammation. It is generally considered as an autoimmune disease mediated by T cells. The precise mechanism of triggering keratinocyte hyperproliferation is as yet unknown. Apoptosis seems to be important in the maintenance of skin cell homeostasis as well as in the pathogenesis of some skin diseases. We hypothesize how apoptosis mediated by cytolytic mechanisms could be involved in initiating and maintenance of psoriatic plaque. Increased keratinocyte hyperproliferation might develop as a consequence of failure to remove self-reactive T cells by apoptosis that in other way cause significant keratinocyte damage. Apoptotic keratinocytes might trigger an injury response program causing regenerative hyperplasia of epidermal keratinocytes. Another possibility is that the failure to eliminate these abnormal keratinocytes could result in the persistence of chronic inflammatory conditions constantly recruiting specific T cells. Increased epidermal thickness in psoriasis could be also explained by imbalance between the expression of pro- and anti-apoptotic proteins. Epidermal keratinocytes have the ability to produce cytolytic molecules, thus they might also have the potential to protect the epidermis from T cell-mediated damage. In conclusion, hyperproliferation of psoriatic keratinocytes might be partly due to changes in the keratinocyte expression of pro- and anti-apoptotic genes, partly to the damaged keratinocytes triggering an inappropriate wound repair response and partly by the failure to eliminate these abnormal keratinocytes resulting in the persistence of chronic inflammation. Each of the proposed mechanisms might be a possible therapeutic target mainly by new immunomodulatory agents.

The prevalence of apoptotic keratinocytes in equine epidermis: a retrospective light-microscopic study of skin-biopsy specimens from 253 horses with normal skin or inflammatory dermatoses

A retrospective study was performed to assess the prevalence of apoptotic epidermal keratinocytes in biopsy specimens from 226 horses with inflammatory dermatoses and from 27 normal specimens. One or more apoptotic keratinocytes were found in specimens from 28 of 226 (12%) horses with various dermatoses, and in one of 27 (4%) specimens from normal horses. The prevalence (proportion of cases with apoptotic epidermal keratinocytes) of apoptotic keratinocytes in the group composed of discoid lupus erythematosus, erythema multiforme, photodermatitis, and systemic lupus erythematosus was significantly greater (52% prevalence in these cases) than that in a grouping of all other dermatoses (prevalence 8%). There was no correlation between the number of apoptotic keratinocytes and the extent of epidermal hyperplasia or hyperkeratosis.

Efficacy of imiquimod for the expression of Bcl-2, Ki67, p53 and basal cell carcinoma apoptosis

BACKGROUND

Imiquimod is a modifier of the immune response that has been proven to be an effective treatment for basal cell carcinoma (BCC). However, its mechanism of action is still unknown.

OBJECTIVES

To determine whether imiquimod modifies the expression of proteins such as Bcl-2, Ki67, p53 and the BCC apoptotic index.

PATIENTS AND METHODS

Thirty caucasian patients with primary BCCs larger than 8 mm in diameter were included in a double-blind randomized clinical and immunohistochemical study which was designed in a reference university hospital. The 30 BCCs were randomized in two treatment arms between September 2001 and February 2002. Twenty-four BCCs were treated with imiquimod 5% cream and six BCCs with Aldara (3M Pharmaceuticals) excipient. Histological samples were obtained before treatment and on days 8 and 15 during the course of treatment. The BCC expression of Bcl-2, Ki67 and p53 was determined in paraffin samples and the apoptotic index of the BCC was studied using the TUNEL technique (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick end labelling) in frozen samples. All variables were evaluated quantitatively in fields with a magnification x 400.

RESULTS

The BCCs treated with imiquimod showed a decrease in the expression of Bcl-2 (88.7% before treatment, 61.4% day 15, P = 0.01) and an increase in the apoptotic index (0.53% before treatment, 1.66% day 15, P = 0.002), which were not observed in the BCCs treated with the excipient. Ki67 and p53 did not show significant changes in any group.

CONCLUSIONS

Imiquimod reduces the expression of Bcl-2 in the BCC cells and increases the BCC apoptotic index.

[Epidermodysplasia verruciformis--a model of virus induced oncogenesis in the skin]

<zakljucak> U osnovi HPV izazvane onkogeneze u kozi nalaze se visoko specificni mehanizmi HPV adaptacije. Koji su to, pokazace buduca istrazivanja.

Examination of Bcl-2, Bcl-X and bax protein expression in psoriasis

BACKGROUND

Psoriasis is an inflammatory skin disease characterized by epidermal hyperplasia and greatly accelerated epidermal turnover. The blockage of normal apoptotic process in the epidermis is one of the factors implicated in the pathogenesis of psoriasis.

OBJECTIVE

The purpose of the present study was to elucidate whether bcl-family proteins are significantly involved in the hypothetical antiapoptotic cascade in lesional psoriatic epidermis.

METHODS

Twenty-six lesional biopsy samples of 26 patients with psoriasis and five control specimens from normal skin were studied by immunohistochemical method for the differential expression of pro-apoptotic bax and antiapoptotic bcl-2 and bcl-x proteins.

RESULTS

Compared with the normal epidermis, bcl-2 expression was significantly reduced, whereas bax and bcl-x were significantly overexpressed in the psoriatic epidermis. The localization of bcl-2/bax/bcl-x proteins in the psoriatic epidermis did not show a significant deviation from that in the normal epidermis.

CONCLUSION

These findings indicate a discordant expression of bcl-2 and bax/bcl-x in psoriatic epidermis. Increased bcl-x expression might contribute to the antiapoptotic response in psoriatic keratinocytes. The presence of strong bax expression with a concomitant decrease in bcl-2 expression suggests either a functional defect in bax protein or an inherent/acquired resistance to bax-mediated apoptosis in psoriatic keratinocytes.

Differential expression of proliferation- and apoptosis-related markers in lentigo maligna and solar keratosis keratinocytes

Keratinocytes influence the number, morphology, and proliferation of melanocytes. An interference in the melanocyte-keratinocyte relationship may contribute to melanoma development. This study examined the expression of apoptotic and proliferative markers in keratinocytes in lentigo maligna to characterize the epidermis permissive to these lesions. Formalin-fixed and paraffin-embedded tissues from 25 samples of lentigo maligna, 20 samples of solar keratoses, and 5 samples each of normal sun-exposed and non-sun-exposed skin (controls) were immunostained with antibodies directed against the proapoptotic markers bax and p53, the antiapoptotic marker bcl-2, and the proliferation marker ki-67. Eight percent of the lentigo maligna samples were positive for keratinocyte expression of bcl-2, 24% were positive for p53, and 76% were positive for bax; respective findings for solar keratoses were 35%, 85%, and 90%. Comparison with normal sun-exposed skin yielded lower rates of keratinocyte proliferation in 56% of the lentigo maligna samples, similar rates in 36%, and higher rates in 8%; for solar keratoses, proliferation was higher than controls in 60% of samples, similar in 35%, and lower in 5%. All these differences were statistically significant. These findings indicate that there are variable patterns of epidermal reaction to chronic sun exposure. The epidermis in lentigo maligna shows overall low proliferation and an apparently low apoptotic tendency. The dysfunctional epidermis may be permissive to aberrant melanocyte proliferation in the early stages of melanoma development.

Mast cell survival and apoptosis in organ-cultured human skin

Mast cells accumulate and persist predominantly in the upper dermis of the skin but the mechanism for this is obscure. The skin is normally exposed to external air, which is essential for the maturation of the epidermis and probably also the dermis. In order to clarify the importance of air exposure on dermal mast cells, skin organ culture at the air-liquid interface (ALI) and submerged (SM) in medium (10% fetal calf serum and Dulbecco's modification of Eagle's medium) was used to study changes in tryptase-, chymase- and Kit-positive mast cell numbers during cultivation for up to 14 days. In addition, possible apoptosis (TACS TdT in situ apoptosis detection method) in chymase-positive mast cells was studied during the culture. In the less-physiologic SM culture, the number of Kit-positive mast cells decreased rapidly on day 1-2 and tryptase-positive cells decreased markedly on day 14. This decrease in mast cell numbers can be explained by the finding that a rapid increase in the apoptosis index of mast cells was induced on day 1-2. In contrast, in the more physiologic ALI culture, the number of Kit-positive cells was sustained over 1-2 days but then decreased on day 7. In addition, tryptase-positive cells decreased steadily in number but not to the same extent as those in the SM culture. Moreover, the increase in the apoptosis index of mast cells was delayed until day 7 in the ALI culture. Addition of exogenous stem cell factor (up to 200 ng/ml) to the SM culture could not prevent the decay in tryptase- and chymase-positive cells. However, stem cell factor reduced significantly the number of Kit-positive cells already on day 2 indicating that the cells had responded. Addition of histamine (0.25 or 1 mM) or tumor necrosis factor-alpha (500 or 2000 U/ml) caused a decrease in the number of tryptase- and Kit-positive cells in the SM culture. In conclusion, a novel finding was that air exposure in the ALI culture markedly delayed the rapid apoptosis and subsequent decrease in mast cell numbers noted to occur in the SM culture. Stem cell factor could not prevent the rapid decrease in mast cell numbers. Histamine and tumor necrosis factor-alpha are possible factors promoting the decline in mast cells.

'Activation-induced cell death': a special program able to preserve the homeostasis of the skin?

The 'activation-induced cell death' (AICD) is a molecular system leading to death of antigen-activated T lymphocytes, in order to avoid accumulation of harmful cytokine-releasing cells. This article reviews both the molecular mechanisms working in AICD and the role played by such mechanisms in preventing a number of skin diseases. Specifically, because AICD removes activated and autoreactive T cells through a CD95-/CD95-L-mediated suicide, skin diseases were scrutinized in which such valuable machinery could be lacking. Indeed, at least some inflammatory skin diseases, including psoriasis and atopic dermatitis, can be sustained by an increased survival of activated T lymphocytes associated with deficient CD95-/CD95-L-mediated AICD of such strong pro-inflammatory cells. In addition, autoreactive skin diseases, including, e.g. alopecia areata, lichen planus and other lichenoid tissue reactions, can be related to autoreactive T lymphocytes which could be unable to undergo CD95-/CD95-L-mediated AICD. Finally, a lack of AICD may be executive even in favoring cutaneous T cell lymphoma. Thus, because inflammatory, autoreactive and neoplastic skin diseases can be associated with a deficient CD95-/CD95-L-mediated suicide of activated T cells, AICD is likely to represent a fundamental program to preserve the homeostasis of the skin. Therapeutic approaches able to restore the AICD machinery promise to successfully treat such relevant skin diseases.

Amyloid deposition in basal cell carcinoma: a cause of apparent lack of sensitivity to radiotherapy

We describe a patient with a large nodular basal cell carcinoma (BCC), which was excised following apparent failure to respond to radiotherapy. Histological examination of the fully excised lesion demonstrated a solid mass of amyloid, which stained positively for cytokeratins, but there was no residual BCC.

2,3,7,8-Tetrachlorodibenzo-p-dioxin alters the differentiation pattern of human keratinocytes in organotypic culture

Human exposure to the environmental toxin 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) produces a severe skin pathology known as chloracne. In these studies we employed a three-dimensional, organotypic model system to study the effects of TCDD on human skin. This model uses the spontaneously immortalized human keratinocyte cell line NIKS and recapitulates both the three-dimensional microenvironment and epithelial-mesenchymal interactions found in intact human skin. Treatment of the organotypic cultures with TCDD causes alterations in the pattern of keratinocyte terminal differentiation. Analysis at both the light and electron microscope levels reveals a fully differentiated cornified layer in TCDD-treated organotypic cultures at earlier time points than observed in vehicle (dimethyl sulfoxide)-treated controls. Furthermore, TCDD-treated organotypic cultures exhibit aberrant distribution of several differentiation-specific protein markers. Basal cells in TCDD- and DMSO-treated organotypic cultures show no differences in proliferation as measured by quantification of 5-bromo-2'-deoxyuridine (BrdU)-positive nuclei. No aberrant BrdU uptake was detected outside of the basal layer. Neither TUNEL labeling nor immunohistochemical staining with an antibody to active caspase-3 revealed increased apoptosis in TCDD-treated organotypic cultures relative to controls. These data clearly indicate that TCDD modulates homeostasis in a model of human stratifying epithelium independent of changes in proliferation and apoptosis, exclusively by impacting keratinocyte terminal differentiation. This TCDD-induced effect on differentiation-specific proteins results in profound changes in the tissue architecture.

Treatment of normal human keratinocytes with 2,3,7,8-tetrachlorodibenzo-p-dioxin causes a reduction in cell number, but no increase in apoptosis

We have examined the effect of TCDD on the growth of normal human keratinocytes. TCDD is a ubiquitous environmental toxicant that causes a severe dermatopathology in humans, which is known as chloracne. The cell biological basis of this pathology remains unknown. We conducted growth experiments in preconfluent normal human keratinocytes with both low (0.05 mM) and standard (0.66 mM) extracellular calcium concentrations in the media. TCDD treatment reduced the number of adherent keratinocytes relative to controls in media containing 0.05 or 0.66 mM calcium. Based on these observations, we speculated that the decrease in the cell number of TCDD-treated cultures might be the result of increased apoptosis. Analysis of nucleosomal fragmentation, nuclear morphology, and caspase-3 activity in keratinocytes reveals no increase in the characteristics of apoptosis in response to TCDD treatment. We therefore conclude that TCDD impacts on keratinocyte homeostasis independent of apoptosis.

Inflammatory vitiligo in Vogt-Koyanagi-Harada disease

Vogt-Koyanagi-Harada disease is a rare disease characterized by uveitis, meningitis, dysacusis, alopecia, poliosis, and vitiligo. We describe a 48-year-old patient with Vogt-Koyanagi-Harada disease associated with thin inflammatory raised erythema and plaque-type inflammatory erythema superimposed on vitiligo. Interestingly, inflammatory raised erythema was separated from the perfect vitiligo, and the incomplete vitiligo lay between them initially. Thereafter, incomplete vitiligo became completely depigmented with diminution of inflammatory raised erythema. This is the second case of vitiligo with inflammatory raised borders associated with Vogt-Koyanagi-Harada disease. Our results of immunohistochemical and electron microscopic studies suggested the involvement of T-cell-mediated cytotoxicity and apoptosis in the development of skin lesions.

Leukocytoclasis: ultrastructural in situ nick end labeling study in anaphylactoid purpura

In order to characterize leukocytoclasis of polymorphonuclear neutrophils (PMNs), the method of in situ nick end labeling for DNA breakdown was applied on tissue samples from 36 patients with anaphylactoid purpura at ultrastructural, as well as light microscopic, level. Light microscopic immuno-peroxidase technique showed positively labeled PMNs infiltrating in the dermis of 24 cases in which leukocytoclastic vasculitis was fully developed, suggesting that breakdown of DNA strands is triggered in the PMNs. Electron microscopic immuno-gold technique employed in six patients with the fully developed stage of inflammation identified the DNA breaks in the nuclei of PMNs. Ultrastructure of these cells, however, showed that only a minor population ( approximately 1/60) of PMNs showed the condensed and marginated nuclei, being compatible with typical apoptotic change. However, the majority of immuno-gold-labeled cells showed relatively intact nuclei without margination of condensed heterochromatin and with disintegrated cytoplasmic organelles and plasma membrane, suggesting that apoptotic cell removal mechanism may be incomplete. The immuno-gold-positive nuclear debris scattering in the tissue is most likely the remnants of unsatisfactory disposal by apoptosis of potentially injurious PMNs, resulting in the vascular and perivascular damage in leukocytoclastic vasculitis in anaphylactoid purpura.

Autoantigen Ro52 directly interacts with human IgG heavy chain in vivo in mammalian cells

Previously, when we used in vivo yeast two-hybrid and in vitro protein-protein interaction analyses, we demonstrated a direct interaction between autoantigen Ro52 and the human IgG heavy chain. This interaction occurred in the absence of antibody-antigen specific interaction. Here, by employing a novel strategy, we further demonstrated that Ro52 co-localized with IgG in transfected mammalian cells. The co-localization was specific to IgG1 but not IgG3. Co-immunoprecipitating IgG with Ro52 from transfected cell lysates suggested that protein complex containing Ro52 and IgG contributed to the in vivo co-localization. In addition, IgG from normal human serum was shown to bind to the surface of apoptotic keratinocytes and the binding could be competitively blocked by 50-fold excesses of IgG1, not IgG3. With a direct binding study, we also demonstrated that IgG1 could bind to the surface of apoptotic cells while IgG3 bound barely. This binding was not competed by Fcgamma fragments indicating a non-Fcgamma receptor mediated interaction. Finally, in a competition analysis the addition of GST-RFP could reduce the IgG binding to the cell surface. Thus, we suggested that the binding of IgG to the apoptotic keratinocytes might be mediated through the interactions with the surface exposed Ro52. The potential role of forming this protein complex on the apoptotic cells will be discussed.

Melanocytic nevus with pregnancy-related changes in size accompanied by apoptosis of nevus cells: a case report

Melanocytic nevi are commonly believed to undergo changes during pregnancy. This is probably related to hormonal influences; however, few studies have been able to prove it. We observed a case of a benign melanocytic nevus, which showed significant enlargement during pregnancy and immediate postpartum regression associated with increased apoptosis of nevus cells. Estrogen and progesterone receptors were not found in our case, although the clinical course still suggested a close association with hormonal influences.

Expression pattern of the bcl-2 homologous protein bad in normal skin, psoriasis vulgaris and keratinocytic tumors

Previous investigations focused on the mechanisms and regulation of apoptotic process have found that bcl-2 and its homologous proteins are central regulators of the mitochondrial phase of apoptosis. Expression of several members of the bcl-2 family has been studied in various tissues including skin under normal as well as disease conditions. In this report, we investigated the expression of bad, the pro-apoptotic member of the BH3 subfamily, in normal and psoriatic epidermis, keratoacanthoma, and basal and squamous cell carcinomas. Normal and psoriatic epidermis showed accentuation of the staining in the lower suprabasal compartment. A weak, predominantly diffuse staining pattern was observed in the upper epidermis of psoriatic plaques. Keratoacanthoma showed strong but diffuse immunostaining for pro-apoptotic bad, however we found only weak bad expression in squamous cell carcinoma. Seven out of 15 basal cell carcinomas failed to express bad protein. There was no correlation between bad positivity and depth of tumour infiltration. Our observation suggests that the pro-apoptotic bad may function as one of regulators involved in the maintenance of epidermal homeostasis and this function could be altered depending on the disease state.

Evaluation of apoptotic cells induced by ultraviolet light B radiation in epidermal sheets stained by the TUNEL technique

Two major components of epidermal cells, keratinocytes and Langerhans cells, are injured by ultraviolet light B radiation, resulting in sunburn cell (apoptotic cell) formation, impaired function, and a reduced number of Langerhans cells. Quantitative analysis of Langerhans cell damage is usually performed using epidermal sheets, whereas that of keratinocytes has been performed by counting the number of sunburn cells in vertical tissue sections. In this study we assessed the influences of ultraviolet light B radiation on epidermal cells by apoptotic cell formation, using murine epidermal sheets stained by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling technique. Ten to 75 mJ per cm2 of ultraviolet light B radiation induced apoptotic cells in abdominal skin of C3H mice. The cells were induced in 6 h after 50 mJ per cm2 of ultraviolet light B irradiation with the peak in number in 24 h, 18.8 +/- 5.0 per mm2 and 97.7 +/- 7.4 per mm2, respectively. One week later, the apoptotic cells were not visualized. As C3H/He, BALB/C, and C57BL/6 mice showed almost the same frequency of apoptosis in epidermal sheets from 50 mJ per cm2 ultraviolet light B-irradiated skin, the induction of the cells by ultraviolet light B radiation did not depend on the genetic trait of the mouse. Xeroderma pigmentosum type A gene-deficient mice, however, showed a greater induction of apoptotic cells (216.9 +/- 25.2 per mm2) by ultraviolet light B radiation than xeroderma pigmentosum type A wild-type mice (89.5 +/- 13.6 per mm2) and conventional mice. Pretreatment with a SPF 60 sunscreen agent was quite effective in reducing the induction of apoptotic cells. Using confocal laser scanning microscopy and double staining, 1.5 +/- 2.7% of apoptotic cells were Ia-positive cells in 24 h after 50 mJ per cm2 of ultraviolet light B radiation. Apoptotic Ia-positive cells were not observed 48 h after the radiation. On the other hand, no apoptotic dendritic epidermal T cells were observed in up to 75 mJ per cm2 of ultraviolet light B radiated skin. Thus, nearly all apoptotic cells were keratinocytes, and Langerhans cells and dendritic epidermal T cells appeared resistant to ultraviolet light B-induced apoptosis. Compared with the assessment in vertical tissue sections, the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling technique with epidermal sheets appeared to be a more physiologically relevant method for quantitative evaluation of apoptotic epidermal cells induced by ultraviolet light B radiation.

Removal of stem cell factor or addition of monoclonal anti-c-KIT antibody induces apoptosis in murine melanocyte precursors

Previous findings indicate that the protein c-KIT and its ligand, stem cell factor (SCF) play a crucial role in the development of melanocytes from their precursors in the embryonic neural crest cells. Using a monoclonal anti-c-KIT antibody, ACK2, which is an antagonistic blocker of c-KIT function, we and colleagues demonstrated that mouse melanocytes disappeared with the injection of ACK2 during certain periods of embryonic and postnatal life. The precise mechanisms of this disappearance, however, remain unclear. Because melanocytes disappeared without any inflammation in these in vivo studies, we suspect that apoptosis was a main cause of their disappearance. In this study, to clarify the underlying mechanism, we studied whether ACK2 induces apoptosis in c-KIT-positive melanoblasts, which appear in mouse neural crest cells cultured with SCF from 9.5 d old mouse embryos. With an in situ apoptosis detection kit, a significant increase in apoptosis was detected after the removal of SCF, which further increased with the addition of ACK2 during SCF-dependent periods. The occurrence of apoptosis in the cultured cells was also demonstrated by a DNA analysis and electron microscopy. Immunohistochemical double staining confirmed that the apoptotic cells were c-KIT positive, and the electron microscopy showed that these apoptotic cells were melanocyte precursors. It was therefore demonstrated that apoptosis was induced in the SCF-dependent c-KIT-positive melanocytes in vitro when the SCF/c-KIT interaction was obstructed. These findings elucidate the mechanism of the regulation of melanocyte development, and the survival and proliferation of these precursor cells, by SCF/c-KIT interaction.

Incipient intraepidermal cutaneous squamous cell carcinoma: a proposal for reclassifying and grading solar (actinic) keratoses

Actinic keratoses (AKs) are primarily induced by ultraviolet (UV) radiation and are often identified as premalignant lesions. In our opinion, AKs are proliferations of transformed, neoplastic keratinocytes confined to the epidermis that may eventually extend into the dermis, at which point they are termed squamous cell carcinoma (SCC). In contrast to AKs, SCCs have the potential to metastasize and kill. This process is analogous to that of evolving carcinoma of the uterine cervix that has been termed cervical intraepithelial neoplasia (CIN), a time-tested and reliable classification that provides clinicians with accurate information on which to base treatment decisions regarding cervical neoplasms following biopsy testing. A similar classification scheme could provide guidance to clinicians for the diagnosis and treatment of evolving SCC of the skin and as such, we propose a similar classification using the terminology keratinocytic intraepidermal neoplasia (KIN). This system is more reflective of the histology and natural history of SCC and eliminates ambiguity in the terminology of lesions currently referred to as AKs. The KIN classification defines features by which individual specimens can be objectively graded and specific treatment recommendations are made based on the grade of the lesion. We propose that the term keratinocytic intraepidermal neoplasia (KIN) be used to define and describe evolving SCC of the skin and that the term actinic (solar) keratosis be eliminated.

MDM2 overexpression generates a skin phenotype in both wild type and p53 null mice

The MDM2 proto-oncogene is overexpressed in human tumours and regulates the activities of the tumour suppressors p53 and pRB. We created mice that overexpress MDM2 under the control of the CMV promoter. These mice did not display an increased tumour incidence, but rather a specific skin phenotype, characterized by desquamation and hyperkeratosis. Transgenic MDM2 was found to be overexpressed in the epidermis, a tissue that normally expresses high levels of MDM2. The phenotype appeared during the first week after birth and then lessened with age, closely following the level of expression of the transgene. MDM2 overexpression was associated with an increase in proliferation in the basal layer, thickening of the epidermis, altered expression of the differentiation markers cytokeratin CK14, CK10 and CK1, and a decrease in the size and the number of granules that contain products of differentiation. Transgenic mice on a p53 null background displayed similar although not identical changes, showing that the effects of MDM2 are to a certain degree p53 independent. The skin is a major site of MDM2 expression in mice, raising the possibility that MDM2 overexpression perturbs the normal pattern of MDM2 expression and inhibits differentiation of the epidermis.

Apoptosis in primary cutaneous amyloidosis

Amyloid deposits in primary cutaneous amyloidosis (PCA) may be initially derived from cytokeratin. possibly after keratinocyte death. However, the mechanism of keratinocyte death remains obscure. To investigate the potential role of apoptosis in the pathogenesis of PCA, a retrospective study was conducted on the skin tissues from 20 Chinese patients with PCA. We used a terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL) method for detecting the apoptotic cells. Immunohistochemical staining was performed to examine the expression of the B-cell leukemia/lymphoma-2 gene (bcl-2) and Fas. Apoptotic cells were shown in 11 of 20 cases (55%) by TUNEL. Histological sections showed that dyskeratotic cells and vacuolar alteration of the basal cells were more commonly observed in the TUNEL-positive group. In all cases of PCA, epidermal expression of bcl-2 was minimal, while expression of Fas was observed on keratinocytes in the basal to granular layers: however, these findings were not different from those in normal skin. Our results suggest that the keratinocyte destruction in PCA may occur as an initial result of apoptosis, which in turn leads to the amyloid formation.

Apoptosis, Fas and Fas-ligand expression in melanocytic tumors

Impaired regulation of apoptosis is known to be associated with the development of various forms of cancer. Fas binding to its ligand, Fas ligand (Fas-L), has been shown to trigger apoptosis in various cell types. Fas-L is expressed by melanoma cells and has been suggested to play a role in melanoma escape from immune surveillance. In the present study, we assessed apoptotic activity and examined Fas and Fas-L expression in malignant melanomas, Spitz nevi and ordinary melanocytic nevi. We evaluated apoptotic activity using terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling. Apoptotic activity was found to be minimal in melanomas and moderate in Spitz nevi. In contrast, common nevi demonstrated significant levels of apoptosis in the deep parts of the tumor. Fas was found to be expressed by all Spitz nevi, most melanocytic nevi and approximately half of the malignant melanoma specimens. Fas expression was also significantly more pronounced in Spitz nevus cells as compared with the two other tumors. The anti-Fas-L antibody was found to stain all three melanocytic tumors. Staining was shown to be stronger and more frequent in melanoma cells as compared to the nevus cells. Using the Spearman test, no significant correlation between Fas-L expression in melanoma cells and apoptosis in MM-infiltrating mononuclear cells was found, suggesting that Fas-L expression in melanoma cells may not be instrumental in their ability to escape immune mechanisms of defense. In contrast, increased levels of apoptosis in the deep parts of melanocytic nevi may reflect and possibly contribute to their benign nature.

Skin cancer in kidney and heart transplant recipients and different long-term immunosuppressive therapy regimens

BACKGROUND

Nonmelanoma skin cancer occurs frequently in organ transplant recipients, but the relative importance of different immunosuppressive therapy regimens is unclear.

OBJECTIVE

We studied the risk of skin cancer in the complete, single-center Norwegian cohort of kidney and heart transplant recipients (n = 2561).

METHODS

We determined cancer risk estimation by means of standardized incidence ratios and multivariate Cox regression.

RESULTS

Transplant recipients had an increased risk of cutaneous squamous cell carcinoma (SCC) (65-fold), malignant melanoma (3-fold), and Kaposi's sarcoma (84-fold), and of lip SCC (20-fold), compared with the general population. After adjustment for age, kidney transplant recipients receiving cyclosporine, azathioprine, and prednisolone had a significantly (2.8 times) higher risk of cutaneous SCC relative to those receiving azathioprine and prednisolone. After adjustment for age and type of immunosuppressive regimen, heart transplant recipients had a significantly (2.9 times) higher risk than kidney transplant recipients.

CONCLUSION

The risk of cutaneous SCC, malignant melanoma, Kaposi's sarcoma, and lip SCC is increased in kidney and heart transplant recipients. The risk of posttransplant cutaneous SCC is related to the degree of immunosuppression caused by long-term immunosuppressive therapy.

The role of apoptosis in wound healing

Wound healing involves a series of rapid increases in specific cell populations that prepare the wound for repair, deposit new matrices and finally, mature the wound. Upon completing their tasks, these specific cell types must be eliminated from the wound prior to the progression to the next phase of healing. The most logical method of cellular down-regulation is through apoptosis. Apoptosis allows for the eliminations of entire populations without tissue damage or an inflammatory response. This review discusses which cells dominate the various phases of tissue repair and how the cellular pattern may vary after differing types of injury. The potential mechanisms involved in the down-regulation of inflammation and fibrosis are also covered. The studies that support the hypothesis that apoptosis is involved in the regulation of wound healing are discussed. The evidence supporting potential cell signals involved in the induction of apoptosis in tissue repair are examined. Finally, the review ends with a presentation of how dysregulation of apoptosis can lead to pathologic forms of healing such as excessive scarring and fibrosis. By understanding the mechanisms controlling apoptosis and tissue repair, one may eventually develop therapeutic modalities to minimize scarring, a final pathway for many disease processes.