Interleukin-10 is a predominant cytokine in atopic dermatitis

Th2 Cytokines and Atopic Dermatitis

Atopic dermatitis (AD), a chronic relapsing inflammatory skin disease, is increasing in prevalence around the world. Intensive research is ongoing to understand the mechanisms involved in the development of AD and offer new treatment options for patients suffering from AD. In this review, we highlight the importance of allergic Th2 responses in the development of the disease and summarize relevant literature, including genetic studies, studies of human skin and mechanistic studies on keratinocytes and mouse models of AD. We discuss the importance of the skin barrier and review recent findings on the pro-Th2 cytokines TSLP, IL-25, and IL-33, notably their ability to polarize dendritic cells and promote Th2 responses. After a brief update on the contribution of different T-cell subsets to AD, we focus on Th2 cells and the respective contributions of each of the Th2 cytokines (IL-4, IL-13, IL-5, IL-31, and IL-10) to AD. We conclude with a brief discussion of the current gaps in our knowledge and technical limitations.

Thymic stromal lymphopoietin is released by human epithelial cells in response to microbes, trauma, or inflammation and potently activates mast cells

Compelling evidence suggests that the epithelial cell-derived cytokine thymic stromal lymphopoietin (TSLP) may initiate asthma or atopic dermatitis through a dendritic cell-mediated T helper (Th)2 response. Here, we describe how TSLP might initiate and aggravate allergic inflammation in the absence of T lymphocytes and immunoglobulin E antibodies via the innate immune system. We show that TSLP, synergistically with interleukin 1 and tumor necrosis factor, stimulates the production of high levels of Th2 cytokines by human mast cells (MCs). We next report that TSLP is released by primary epithelial cells in response to certain microbial products, physical injury, or inflammatory cytokines. Direct epithelial cell-mediated, TSLP-dependent activation of MCs may play a central role in "intrinsic" forms of atopic diseases and explain the aggravating role of infection and scratching in these diseases.

No association of cytokine gene polymorphisms in Chinese patients with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a common chronically relapsing skin disease associated with the activation of T-helper 2 cells. Recent studies have shown that polymorphisms in the genes for interleukin (IL)-4, the IL-4 receptor, IL-13, and signal transducer and activator 6 (STAT6) may contribute to susceptibility of AD. To date, no cytokine gene polymorphism study has been conducted on Chinese patients with AD.

AIMS

To determine whether genetic polymorphisms of the cytokine genes might influence the development of AD.

METHODS

DNA samples were obtained from 94 patients and 186 control subjects. Using direct sequencing and microsatellite genotyping, we examined 22 polymorphisms in eight cytokine genes including the genes for IL-4, -10, -12B and -13, the IL-4 receptor, tumour necrosis factor (TNF)-alpha, STAT6, and interferon (IFN)-gamma.

RESULTS

No significantly different allelic and genotypic distributions of the cytokine gene polymorphisms could be found between patients and controls. Moreover, no association was observed with disease onset, gender, the presence of elevated serum total IgE level or blood eosinophilia.

CONCLUSION

Our study suggests that the analysed genetic polymorphisms of cytokine genes do not appear to be associated with AD susceptibility in our Chinese population.

Early up-regulation of Th2 cytokines and late surge of Th1 cytokines in an atopic dermatitis model

We investigated cytokine profiles in interleukin (IL)-4 transgenic (Tg) mice with a skin inflammatory disease resembling human atopic dermatitis. cDNA microarray revealed that the mRNAs encoding IL-1beta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-10, IL-12p40, IL-13, tumour necrosis factor (TNF)-alpha, TNF-beta and interferon (IFN)-gamma were up-regulated in the skin of late lesion Tg mice and to a lesser degree in non-lesion Tg mice when compared to those of non-Tg mice. Real time reverse transcription-polymerase chain reaction (RT-PCR) analyses indicated that the cDNA copy numbers of IL-1beta, IL-4, IL-6, IL-10, TNF-alpha and IFN-gamma from the skin of late, early and non-lesions increased significantly compared to non-Tg mice. IL-2 and IL-12p40 cDNA copy numbers were increased significantly in early, but not late, lesions. Interestingly, IL-1beta, IL-3, IL-4, IL-5, IL-6, IL-10, IL-13, TNF-alpha, and IFN-gamma cDNAs were increased significantly the skin of before-onset and/or non-lesion mice. Flow cytometry analyses demonstrated an increased percentage of keratinocytes producing IL-4 as the disease progressed. The percentage of IL-2, IL-4, IL-10 and IFN-gamma-producing T cells and IL-12-producing antigen-presenting cells in skin-draining lymph nodes and inflammatory skin also increased, particularly in mice with late lesion. These results suggest that disease induction is primarily triggered by Th2 cytokines and that Th1, Th2 and non-Th proinflammatory cytokines are all involved in the disease process.

Intradermal delivery of antisense oligonucleotides by the pulse depolarization iontophoretic system

The intradermal delivery of an antisense oligonucleotide was examined by iontophoresis. In this experiment, the antisense sequence of [(32)P]-labeled phosphodiester oligonucleotide ([(32)P]D-oligo, 18-mer) hybridizing to mouse interleukin 10 (IL-10) mRNA was used as a model D-oligo. In in vitro iontophoretic experiments, isolated hairless mouse skin was used with a horizontal diffusion cell. The enhancing effect of pulse depolarization (PDP) iontophoresis on the [(32)P]D-oligo permeation through the skin was better, and the skin irritation was less, than those of constant direct current (CDC) iontophoresis. The apparent fluxes of [(32)P]D-oligo were enhanced with the increasing current densities and [(32)P]D-oligo concentrations in the donor solution, whereas the enhanced flux decreased with the increasing NaCl concentrations in the donor solution. An optimum electric current was observed for the intradermal delivery of [(32)P]D-oligo, and intact [(32)P]D-oligo was detected within the skin after iontophoresis for 6 h. These results suggest that PDP iontophoresis may be useful for the intradermal delivery of antisense oligonucleotides.

Intravenous immune globulin effects on serum-soluble CD5 levels in atopic dermatitis

BACKGROUND

Intravenous immune globulin (IVIG) therapy has been tried in the treatment of atopic dermatitis. Recently, the presence of serum-soluble CD5 (ssCD5) in atopic dermatitis was reported.

OBJECTIVE

IVIG effects on ssCD5 levels in atopic dermatitis were examined and the correlation of ssCD5 level changes with clinical and laboratory parameters were investigated.

METHODS

IVIG therapy was tried on 40 atopic dermatitis and 17 recurrent spontaneous abortion patients. Five atopic dermatitis patients received normal saline as a placebo control group. The clinical and laboratory parameters were evaluated on day 0, 1, 7 and 21 after administering the IVIG therapy.

RESULTS

With IVIG therapy, in atopic dermatitis, the ssCD5 level was 5.5 +/- 6.2 ng/mL before infusion (day 0), 15.2 +/- 12.1 ng/mL on day 1, 13.8 +/- 14.1 ng/mL on day 7, and 3.9 +/- 4.1 ng/mL on day 21. The clinical severity score was 350.5 +/- 120.3 on day 0, 420.4 +/- 174.8 on day 1, 250.0 +/- 121.2 on day 7, and 115.5 +/- 53.9 on day 21. White blood cell (WBC) counts and serum IgE levels showed a gradual decrease with IVIG infusions. Blood eosinophil fractions were 5.3 +/- 2.8% on day 0, 8.6 +/- 5.2% on day 1, 7.3 +/- 3.7% on day 7, and 6.8 +/- 4.0% on day 21. Changes in the total eosinophil count were insignificantly parallel with those of blood eosinophil fractions

CONCLUSION

In atopic dermatitis, IVIG therapy increased the ssCD5 levels. Further studies concerning the exact role of ssCD5 are needed.

A rapid flow cytometric assay to detect CD4+ and CD8+ T-helper (Th) 0, Th1 and Th2 cells in whole blood and its application to study cytokine levels in atopic dermatitis before and after cyclosporin therapy

BACKGROUND

The immune response in atopic dermatitis (AD) is thought to be driven by T-helper (Th) 2 cytokines. Using flow cytometry, higher frequencies of peripheral blood CD4+ and CD8+ T cells producing interleukin (IL)-4 and correspondingly lower frequencies of CD4+ T cells producing interferon (IFN)-gamma have been found in patients with AD compared with healthy controls. It would be of interest to know whether other Th1 and Th2 cytokines such as IL-5, IL-13 and tumour necrosis factor (TNF)-alpha are similarly skewed in patients with AD and whether this immune skewing, detected via a simple blood assay, can be correlated with other clinical measurements or treatments in AD.

OBJECTIVES

To use a rapid (4-h) flow cytometric assay to study a wide range of Th1 and Th2 cytokine patterns in peripheral blood lymphocytes from patients with AD, comparing them with non-atopic healthy controls. To correlate cytokine patterns with the degree of eosinophilia observed and in the case of one patient with severe disease, to observe the effect of cyclosporin therapy on peripheral blood cytokine patterns.

METHODS

Peripheral blood from eight patients with AD and 23 healthy controls was examined for the frequencies of CD4+ and CD8+ T cells expressing IL-2, IL-4, IL-5, IL-13, IFN-gamma and TNF-alpha using flow cytometry.

RESULTS

Significantly higher frequencies of CD4+/IL-4+ (P < 0.005) and CD4+/IL-13+ (P < 0.0001) and lower frequencies of CD4+/IFN-gamma+ (P < 0.002) and CD8+/TNF-alpha+ (P < 0.05) T lymphocytes were found in patients with AD compared with controls. There were significant positive correlations with the increased percentages of CD4+/IL-4+ and CD4+/IL-13+ T lymphocytes and the degree of eosinophilia observed (P < 0.05, P < 0.001) and a negative correlation between the percentage of CD4+/IFN-gamma+ T lymphocytes and eosinophilia (P < 0.05). In one patient examined before and 8 days after cyclosporin therapy, 50% or greater reductions were observed in percentages of peripheral blood CD8+/IL-5+, CD8+/IL-13+, CD4+/IL-4+ and CD4+/IL-5+ T lymphocytes following cyclosporin therapy. A smaller reduction of 15% after cyclosporin therapy was found in percentages of CD4+/IL-13+ T cells.

CONCLUSIONS

These data strongly support a Th2 predominance in the peripheral blood of AD. The results suggest that administration of cyclosporin therapy in patients with AD may help to restore the Th2 cytokine imbalance seen in these patients.

Blood eosinophils and serum IgE as predictors for prognosis of interferon-gamma therapy in atopic dermatitis

BACKGROUND

Interferon-gamma (IFN-gamma) therapy has been reported to be effective in atopic dermatitis. However, IFN-gamma therapy in atopic dermatitis has not yet been well established. In this study, immunologic variables were evaluated as predictors for the prognosis of IFN-gamma therapy in atopic dermatitis.

METHODS

Sixty-eight atopic dermatitis patients were each treated 18 times with 2 x 10(6) units/m2 IFN-gamma. Blood IgE level, eosinophil percentage, eosinophil count, and levels of IFN-gamma, interleukin-4 (IL-4), IL-5, and IL-10 were investigated. According to clinical responses, patients were classified into three groups: patients with improved clinical severity scores of over 20% were included in group A; those with improved scores of 20% or less in group B; and those with no improvement in group C.

RESULTS

Serum IgE levels and blood eosinophil percentages were the lowest in group A. Most atopic dermatitis patients with an eosinophil percentage over 9% and IgE level over 1500 IU/ml did not respond to IFN-gamma therapy. Initial IL-10 levels were the highest in group A. IL-4 levels in group A, and IL-5 and IL-10 levels in all groups were significantly decreased by IFN-gamma therapy.

CONCLUSIONS

IFN-gamma therapy may be recommended for atopic dermatitis patients with blood eosinophil percentages less than 9% and serum IgE levels less than 1500 IU/ml.

Decreased frequency of interferon-gamma-producing CD4+ cells in the peripheral blood of patients with atopic dermatitis

Recently, decreased interferon-gamma (IFN-gamma) and increased interleukin (IL)-4 production have been reported in measurements of the content of the cytokines in culture supernatants of peripheral blood mononuclear cells (PBMC) obtained from patients with atopic dermatitis (AD). These data suggest deviation of PBMC into Th2-reactive cells in AD. In the present study, we examined the frequency of IL-2-, IL-4-, and IFN-gamma-producing cells in PBMC with flow cytometry. PBMC from 16 patients with AD and 18 healthy controls were stimulated for 2 days with anti-CD3 and IL-2, and further cultured for 4 days with a maintenance dose of IL-2. Thereafter these cells were restimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin for 4 h in the presence of monensin. After fixation of the cells, the cell membranes were made permeable and intracellular cytokines were stained with anti-IL-2, anti-IL-4 or anti-IFN-gamma antibody. Cytokine-producing cells were analyzed by gating CD4+- or CD8+-subsets. Thus counted frequency of IFN-gamma-producing cells was significantly decreased in CD4+ subsets of AD patients (9.9+/-7.4%) when compared with that in the controls (20.0+/-6.7%). There was no significant difference either in the frequency of IL-2- or IL-4-producing CD4+ subsets or in that of CD8+ subsets. Furthermore, in the enzyme-linked immunosorbent assay, we also found a decreased production of IFN-gamma in the culture of PBMC from AD patients, when compared with those from healthy controls, although it was only at a marginally significant level (P=0.07). Again there was no increase in IL-4 concentration in AD patients. In addition, we found a weak negative relationship between the disease severity and the frequency of these cells. These results suggest that the decreased frequency of IFN-gamma-producing CD4+ cells with subsequently decreased production of IFN-gamma play a crucial role in the pathophysiology of AD.