The combination of the Zenon labeling technique and microscopic image analysis to study cell populations in normal and psoriatic epidermis

Two distinct expression patterns of urokinase, urokinase receptor and plasminogen activator inhibitor-1 in colon cancer liver metastases

Metastatic growth and invasion by colon cancer cells in the liver requires the ability of the cancer cells to interact with the new tissue environment. Plasmin(ogen) is activated on cell surfaces by urokinase-type PA (uPA), and is regulated by uPAR and plasminogen activator inhibitor-1 (PAI-1). To compare the expression patterns of uPA, uPAR and PAI-1 in colon cancer with that in their liver metastases, we analysed matched samples from 14 patients. In all 14 primary colon cancers, we found upregulation of uPAR, uPA mRNA and PAI-1 in primarily stromal cells at the invasive front. In 5 of the 14 liver metastases, we found intense expression of uPAR, uPA-mRNA and PAI-1 in primarily stromal cells at the metastases periphery, and in an expression pattern similar to that found in the primary tumours. In the remaining 9 liver metastases, uPAR and uPA-mRNA were only seen associated with the presence of necrosis within the liver metastases. In addition, PAI-1-immunoreactivity was in all liver metastases seen in hepatocytes at the metastases periphery. Interestingly, the former 5 liver metastases positive for uPAR, uPA mRNA and PAI-1 at the metastasis periphery all had a predominantly desmoplastic reaction, whereas 8 of the remaining 9 showed direct contact between the cancer cells and the liver parenchyma. We conclude that there are 2 distinct patterns of expression of uPAR, uPA and PAI-1 in colon cancer liver metastases and that these correlate closely with 2 morphological growth patterns. These findings may have implication for the treatment of patients with metastatic disease.

Assessment of epidermal subpopulations and proliferation in healthy skin, symptomless and lesional skin of spreading psoriasis

BACKGROUND

The margin zone in spreading psoriatic lesions has frequently been used as a model to study the changes in epidermal proliferation, keratinization and inflammation during the transition from symptomless to lesional skin. However, the dynamics of the changes in the epidermal subpopulations-basal cells, transit amplifying cells and differentiated cells-have not been studied in the transition between symptomless and lesional skin.

OBJECTIVES

To quantify in a dynamic model of the margin zone in psoriasis the characteristics of these subpopulations with respect to epidermal proliferation and differentiation.

METHODS

From seven patients with active psoriasis, biopsies were taken from the distant uninvolved skin, outer margin, inner margin and centre of a spreading psoriatic plaque. Frozen sections were labelled immunofluorescently using direct immunofluorescence for Ki-67 and beta1 integrin and the Zenon labelling technique for keratin 6, 10 and 15. Digital photographs of the stained sections were quantitatively analysed.

RESULTS

In the distant uninvolved skin the expression of beta1 integrin was decreased and keratin 15 expression was lost. In this area suprabasal cells expressed beta1 integrin and in the outer margin suprabasal cells expressed Ki-67. From the outer to the inner margin of the psoriasis plaque, which coincided with the appearance of the clinical lesion, there was a significant change in the various markers. The patchy expression of keratin 6 in the inner margin became homogeneous in the centre of the psoriasis plaque and here was also coexpression of keratin 6 and keratin 10 in a single cell.

CONCLUSIONS

The present study provides additional evidence that the distant uninvolved skin has a prepsoriatic phenotype, which is the first step in a psoriatic cascade. The cascade between symptomless and lesional skin comprises first an abnormality in inflammation with involvement of beta1 integrin-dim cells (transit amplifying cells) subsequently eliciting an enlarged germinative compartment with increased recruitment of cycling epidermal cells and focal expression of proliferation-associated keratins, ultimately culminating in a more-or-less homogeneous epidermis with massive recruitment of cycling epidermal cells and proliferation-associated keratinization.

A double-blind, randomized quantitative comparison of calcitriol ointment and calcipotriol ointment on epidermal cell populations, proliferation and differentiation

BACKGROUND

Calcitriol and calcipotriol are widely used in the topical treatment of psoriasis. However, studies comparing both treatment modalities are scarce. Especially, there are almost no studies comparing the effects on epidermal cell populations in a quantitative manner.

OBJECTIVES

The aim of this study was to quantitatively compare the effects of topical calcitriol and topical calcipotriol on clinical scores and epidermal subpopulations.

PATIENTS AND METHODS

From five patients with stable plaque psoriasis, skin biopsies were taken from two symmetrical regions on the trunk or extremities before and after treatment with either calcitriol or calcipotriol. Frozen sections were labelled immunofluorescently using direct immunofluorescence for beta-1 integrin and the Zenon labelling technique for keratin (K) 6, K10 and K15. The digital photographs of the stained sections were quantitatively analysed and the results of both treatments were compared.

RESULTS

The clinical SUM-score improved significantly for both the calcitriol- and the calcipotriol-treated lesions. In the calcipotriol-treated group the expression of K10 and K15 increased and the expression of K6 decreased significantly. No changes were seen for the marker beta-1 integrin. In the calcitriol-treated group none of the markers changed significantly. A tendency towards significance was seen for the changes in the expression of K6 and K15 in favour of calcipotriol.

CONCLUSIONS

Both calcitriol and calcipotriol gave a significant improvement in clinical scores. However, treatment with calcipotriol resulted in a normalization of K6, K10 and K15, whereas treatment with calcitriol did not. Comparison of both treatments showed a tendency towards significance for the above-mentioned markers for calcipotriol only.

Identification of lesional CD4+ CD25+ Foxp3+ regulatory T cells in Psoriasis

BACKGROUND

Depletion of CD4+ CD25+ Foxp3+ naturally occurring regulatory T cells (T(reg)) induces autoimmune phenomena. These cells have not yet been fully characterized in the skin of psoriatic patients.

OBJECTIVES

To prove that the Zenon immunofluorescent labeling technique is suitable for the demonstration of co-localization of T-cell markers and in particular to show the distribution of T(reg) in psoriatic skin.

METHODS

In biopsies derived from normal and psoriatic skin, CD4+ CD25+, CD4+ CD45RO+, CD8+ CD25+, CD8+ CD45RO+ and CD4+ CD25+ Foxp3+ cells in the dermis and in the epidermis were immunophenotyped, using a quantitative immunofluorescent labeling technique (Zenon), analyzed and compared using image analysis.

RESULTS

The immunofluorescent labeling technique was shown to be an easy and reliable tool to demonstrate co-localization of T-cell markers. In psoriasis, all pathogenic T-cell subsets (CD4+ CD25+, CD4+ CD45RO+, CD8+ CD25+ and CD8+ CD45RO+ cells) were significantly increased in the dermis and in the epidermis, as compared to normal skin (all p < 0.05). Using this labeling technique we were able to reveal CD4+ CD25+ Foxp3+ T(reg) in psoriatic dermis, but not in the dermis of normal skin (p < 0.0001).

CONCLUSIONS

The Zenon immunofluorescence technique in combination with image analysis is suitable for the demonstration of co-localization of T-cell markers in tissue. Increased numbers of pathogenic T cells (CD4+ CD25+, CD4+ CD45RO+, CD8+ CD25+ and CD8+ CD45RO+) were shown in the dermis and epidermis, whereas CD4+ CD25+ Foxp3+ T(reg) were identified in psoriatic skin with a predilection for the upper dermis.

Six-colour fluorescent imaging of lymphoid tissue based on colour addition theory

Multi-colour imaging of immunofluorescently labelled tissue using confocal microscopy was accomplished by using colour addition theory. This new technique includes several improvements for immunolabelling: (1) the co-localization of two or more markers on one cell for the identification of specific cell populations; (2) the co-localization of two fluorescent dyes from secondary reagents for the identification of the cells; (3) a multi-step staining protocol with two primary antibodies originating from the same host species or with two or three biotin-conjugated primary antibodies. After image acquisition, colour segmentation/unmixing are applied to the single multi-colour image to generate multi-pseudo-channels for individual or co-localized fluorescent dyes. With this new technique, we have been able to visualize six cell populations simultaneously in the mouse lymph node and intestine. The efficiency of this method has also been demonstrated in the three-dimensional reconstruction of thick sections from mouse ileum. Our method is simple, efficient, and may be indispensable in experimental cell and tissue studies requiring multiple immunolabelling.

Effect of calcipotriol on epidermal cell populations in alefacept-treated psoriatic lesions

BACKGROUND AND OBJECTIVES

The effect of the established antipsoriatic treatment with topical calcipotriol (with a maximum of 100 g per week) in addition to systemic treatment with alefacept, a new biological agent for psoriasis, on epidermal cell populations in the psoriatic lesion was investigated using a combination of the Zenon labelling technique and microscopic image analysis. Epidermal cell populations were measured quantitatively with this sensitive method.

PATIENTS/METHODS

Frozen sections of non-treated psoriatic epidermis and psoriatic epidermis treated with either alefacept intramuscular or alefacept intramuscular in combination with topical calcipotriol for 12 weeks were compared immunohistochemically. Antibodies against keratin 6, 10 and 15 were labelled with the Zenon technique, whereas antibodies against the Ki-67 antigen and beta-1 integrin were covalently Fluorescein Isothiocyanate (FITC)-labelled. Using image analysis, these markers were measured in the epidermis in a standardized manner.

RESULTS AND CONCLUSIONS

Treatment of psoriasis with alefacept resulted in a good clinical response in several patients and in a normalization of epidermal expression of the immunohistochemical parameters for differentiation and proliferation. The addition of topical calcipotriol resulted in a faster clinical improvement with a similar overall clinical response and a similar response of epidermal cell populations as compared to treatment with alefacept monotherapy after 12 weeks of treatment. This study also suggests that the appearance of keratin 15 has a predictive value for the duration of remission. It can be concluded that the addition of a low-dose calcipotriol treatment does not contribute to the clinical efficacy of alefacept, both at the clinical level and with respect to markers for epidermal proliferation and differentiation.