Karen Bang

Telomerase Activity Is Increased and Telomere Length Shortened in T Cells from Blood of Patients with Atopic Dermatitis and Psoriasis

We studied telomerase activity and telomere length in PBMC and purified CD4+ and CD8+ T cells from blood obtained from a total of 32 patients with atopic dermatitis, 16 patients with psoriasis, and 30 normal controls. The telomerase activity was significantly increased in PBMC from the patients compared with PBMC from normal donors. This increase was most pronounced in the subpopulation of CD4+ T cells, which were significantly above the activity of the CD8+ T cells in atopic dermatitis, psoriasis patients, and control persons. The telomere length was significantly reduced in all T cell subsets from both atopic dermatitis and psoriasis patients compared with normal individuals. Furthermore, the telomere length was found to be significantly shorter in CD4+ memory T cells compared with the CD4+ naive T cells, and both of the cell subsets from diseases were shown to be of significantly shorter telomere length than the same cell subsets from normal controls. No significant difference was observed between CD8+CD28− and CD8+CD28+ T cell populations in both diseases. However, the telomere length of CD8+CD28+ T cells from both diseases was significantly shorter than CD8+CD28+ T cell subsets from normal donors. In conclusion, the increased telomerase activity and shortened telomere length indicates that T lymphocytes in atopic dermatitis and psoriasis are chronically stimulated and have an increased cellular turnover in vivo.

Stable Incidence of Atopic Dermatitis among Children in Denmark during the 1990s

An increase in the prevalence of atopic dermatitis (AD) has been reported since the 1960s. The increase could be due to many factors including a genuine increase of incidence or duration of AD. We decided to study if the increasing trend persisted during the 1990s by comparing the cumulative incidence of AD in 1993 and 1998. Further, we studied the severity and management of AD among children. Two samples of children born in Denmark were drawn from the Danish Medical Birth Register. In the 1993 and 1998 studies a mailed questionnaire with identical questions concerning AD was sent out. In the 1998 follow-up study the questionnaire included a severity score and questions concerning management of AD. In the 1993 study the cumulative incidence of AD at age 7 was 18.9% and in 1998 it was 19.6%. There was no difference in the age-adjusted AD incidence in the 5-year observation period. In the 1998 study, 81% had mild to moderate AD, 90% had been seen by a doctor at least once, 36% had mainly been treated by a dermatologist, and 2% had been hospitalized. It should be kept in mind that we base most of our common knowledge of the disease on AD patients selected for management in dermatology clinics and departments.

CD4+ CD8+ (thymocyte-like) T lymphocytes present in blood and skin from patients with atopic dermatitis suggest immune dysregulation.

Background Atopic dermatitis (AD) is a chronic inflammatory skin disease expressed early in life. Disease development is primarily determined by as yet unknown genetic factors, leading to the accumulation of activated T lymphocytes in the skin.Objectives To investigate the nature of these T cells.Methods T‐cell lines could be established from AD skin biopsies, but not from normal skin or AD peripheral blood, when placed in RPMI 1640 medium with 10% human AB serum, antibiotics, and the T‐lymphocyte growth factors interleukins 2 and 4. The cell lines were subjected to phenotypic analysis using a fluorescence‐activated cell sorter and compared with lymphocytes from AD and normal control peripheral blood.Results T‐cell lines from 22 of 24 consecutive skin biopsies taken from 24 adult patients with AD were established. All cells were T lymphocytes expressing several activation markers. A significant proportion of the lymphocytes had stable expression of a CD4+ CD8+ phenotype (26% ± 6%; mean ± SEM). Such double‐positive T lymphocytes are normally only seen in the thymus and not in the peripheral immune system. CD4+ CD8+ cells in peripheral blood of the patients (12·5% ± 3·3%) were also detected.Conclusions We suggest that a basic pathophysiological change in AD may be a faulty maturation of the T‐lymphocyte system, leading to skin inflammation with CD4+ CD8+ T lymphocytes resembling immature T cells. This is likely to lead to skewing of many immune reactions in the patients.

Cytokine expression of skin T-lymphocytes from patients with atopic dermatitis

We analysed the cytokine profile of skin T cells by establishing 11 T-cell lines from adult patients with moderate-to-severe atopic eczema using T-cell growth factors interleukin-2 and interleukin-4. We compared T-cell lines from lesional skin of atopic dermatitis patients with those from non-atopic skin of patients with other skin diseases, observing that T-cell lines of patients with atopic dermatitis unstimulated cultures expressed a Th1 profile. After stimulation with anti-CD3 and anti-CD28 monoclonal antibodies, the cytokine expression showed rapid initial upregulation of Th2 followed by a Th1 profile. Furthermore, strong upregulation of interleukin-10 was observed after 24 h stimulation. Our findings suggest that skin T-lymphocytes from atopic dermatitis patients seem to consist of a heterogenous population of Th1 and Th2 or Th0 cells and the results for secreted cytokines indicate that T-cell lines from each inflammatory skin disease showed the corresponding disease-specific original cytokine profile.

Development and Validation of a Questionnaire for Diagnosing Atopic Dermatitis

In this paper we describe the development and validation of a questionnaire for atopic dermatitis used in population surveys in Denmark. The Danish questionnaire was developed from the UK Working Partys questionnaire for atopic dermatitis and includes a severity score. The study included 61 children aged 3 to 14 years recruited from our Department of Dermatology, two kindergartens and a primary school. A validator was appointed to evaluate whether each child had current or previous atopic dermatitis. Compared to the validators diagnosis, the sensitivity of the UK Working Party criteria was 90% (95% CI; 74-98) and the specificity was 97% (95% CI; 82-99). The criteria for atopic dermatitis have a satisfactory sensitivity and specificity for diagnosing current atopic dermatitis, but the natural course of the disease complicates the validation of investigational instruments. We suggest that future epidemiological studies aimed at establishing new knowledge on atopic dermatitis should include history, current symptoms and findings and a severity score.

Telomerase activity is spontaneously increased in lymphocytes from patients with atopic dermatitis and correlates with cellular proliferation

Telomerase is a ribonucleoprotein enzyme involved with cellular proliferation and cellular senescence. The aim of the present study was to investigate telomerase activity in lymphocytes from patients with atopic dermatitis (AD) and to observe its regulation of cellular proliferation. Peripheral blood mononuclear cells (PBMC) were isolated from 15 patients with AD and 13 healthy donors. Cells were stimulated with purified protein derivative (PPD) of tuberculin (10 microg/ml), interleukin 2 (IL-2) (100 U/ml), anti-CD3 monoclonal antibody (anti-CD3) (1 microg/ml), anti-CD3 plus IL-2, and staphylococcal enterotoxin A (SEA) (0.1 microg/ml). Telomerase activity was measured by the telomeric repeat amplification protocol-based telomerase polymerase chain reaction enzyme-linked immunosorbent assay at 0 and 72 h of incubation. In addition, DNA synthesis of the cells was assayed using 3H-thymidine incorporation. We found that telomerase activity in non-stimulated PBMC from patients with AD was significantly up-regulated without any stimulation during the 72 h of in vitro incubation. The most potent stimulator of telomerase activity was SEA, followed by anti-CD3 plus IL-2, anti-CD3 alone, and PPD. IL-2 did stimulate telomerase activity and DNA proliferation with increasing dosage of IL-2. The DNA proliferation was paralleled by increase in telomerase activity. There was no significant difference between telomerase activity in stimulated lymphocytes from AD patients and normal donors, but the relative increase in telomerase activity tended to be less in AD patients. A spontaneously higher telomerase activity in lymphocytes from AD patients could indicate that T lymphocytes are already stimulated in vivo or that a population of T cells in peripheral blood exhibits an increased telomerase activity compatible with cellular immaturity.

Proliferation of T lymphocytes from atopic dermatitis skin is enhanced upon anti-CD3, reduced upon mitogen and superantigen, and negligible upon tuberculin stimulation

Knowledge about the nature of lymphocytes infiltrating atopic dermatitis skin is restricted to allergen-specific T cells. We investigated the proliferative capacities of T lymphocytes cultured in an antigen-independent way from biopsies of atopic dermatitis skin. When compared with peripheral blood mononuclear cells (PBMC) from healthy donors or atopic dermatitis patients, the skin-homing lymphocytes proliferated more vigorously in response to stimulation with anti-CD3 antibodies (1 microglml), reflecting their high response capacity. When stimulated with phytohemagglutinin (10 microg/ml) or staphylococcal enterotoxin A (0.1 microg/ml) the skin-homing lymphocytes achieved significantly lower proliferation levels than PBMC. In contrast to normal and atopic PBMC the skin-homing lymphocytes did not respond to tuberculin purified protein derivative (10 microg/ml). In the mixed lymphocyte reaction the skin-homing lymphocytes did not stimulate autologous PBMC to proliferate. We conclude that skin-homing lymphocytes have more pronounced immune deviations than PBMC in patients with atopic dermatitis. They represent a valuable approach for further investigating the pathogenesis of the disease.