Cutaneous lymphocyte-associated antigen expression in children with atopic dermatitis and non-atopic healthy children

MiRNA in atopic dermatitis

MicroRNAs are relatively new molecules that have been widely studied in recent years as to determine their exact function in the human body. It is suggested that microRNAs control approx. 30% of all genes, making them one of the largest groups that control the expression of proteins. Various functions of miRNAs have already been described. In skin diseases, there are more and more studies describing an altered expression of microRNAs in the skin or serum. Relatively little is known about the function of these molecules in atopic dermatitis, which prompted us to gather current reports on this subject.

CCR4 and CXCR3 play different roles in the migration of T cells to inflammation in skin, arthritic joints, and lymph nodes

CCR4 and CXCR3 are expressed on several T-cell subsets in inflamed tissues, yet their role in tissue-specific recruitment is unclear. We examined the contributions of CCR4 and CXCR3 to T-cell recruitment into inflamed joints in collagen-induced arthritis, antigen-draining lymph nodes (LNs) and dermal inflammatory sites (poly I:C, LPS, concanavalin A, and delayed type hypersensitivity), using labeled activated T cells from CXCR3(-/-), CCR4(-/-), and WT mice. Both CXCR3 and CCR4 deficiency reduced the development of arthritis, but did not affect Th1-cell recruitment to the inflamed joints. Accumulation in inflamed LNs was highly CXCR3 dependent. In contrast, CCR4-deficient Th1 cells had an increased accumulation in these LNs. Migration to all four dermal inflammatory sites by activated Th1 and T cytotoxic cells and memory CD4(+) T cells was partially CXCR3-dependent, but Treg-cell migration was independent of CXCR3. The subset of cells expressing CCR4 has skin-migrating properties, but CCR4 itself is not required for the migration. Thus, migration into these inflamed tissues is CCR4-independent, and partially dependent on CXCR3, except for Treg cells, which require neither receptor. CCR4 may therefore affect retention of T cells in different tissues rather than trafficking out of the blood.

Suppression of inflammation by recombinant Salmonella typhimurium harboring CCL22 microRNA

Atopic dermatitis (AD) is an inflammatory, chronically relapsing, puritic skin disorder. These syndromes result from multifactorial inheritance, with interaction between genetic and environmental factors. In particular, the macrophage-derived chemokine CCL22 is directly implicated in skin inflammatory reactions and its levels are significantly elevated in serum and correlated with disease severity in AD. We tested the suppression of the CCL22 gene by microRNA (miRNA) and observed the effects in mice with inflammation similar to AD. We used Salmonella as a vector to deliver miRNA. The recombinant strain of Salmonella typhimurium expressing CCL22 miRNA (ST-miRCCL22) was prepared for in vivo knockdown of CCL22. ST-miRCCL22 was orally inoculated into mice and the CCL22 gene suppressed with CCL22 miRNA in the activated lymphocytes. IgE and interleukin-4 were inhibited and interferon-γ was induced after treatments with ST-miRCCL22 and CCL22 was suppressed. Further, Th17 cells were suppressed in the atopic mice treated with ST-miRCCL22. These results suggested that suppression of the CCL22 gene using Salmonella induced anti-inflammatory effects.

Therapeutic effects of recombinant Salmonella typhimurium harboring CCL22 miRNA on atopic dermatitis-like skin in mice

Th-2-biased immune responses are known to play a key role in the pathogenesis of atopic dermatitis. In particular, the macrophage-derived chemokine CCL22 is directly implicated in Th-2-associated skin inflammatory reactions, and its levels are significantly elevated in serum and are correlated with disease severity in atopic dermatitis. In this study, we tested the development of genetic therapeutic options to treat atopic dermatitis using bacteria expressing miRNA. We constructed a recombinant strain of Salmonella typhimurium expressing CCL22 miRNA (ST-miRCCL22) for the in vivo knockdown of CCL22. The CCL22 gene was downregulated with CCL22 miRNA in activated lymphocytes. In mice with a cutaneous disease similar to atopic dermatitis, interleukin-4 was inhibited and interferon-g was induced after treatments with ST-miRCCL22. Furthermore, CCL22 levels were suppressed in the atopic mice treated with ST-miRCCL22. These results suggest that ST-miRCCL22 may be an effective genetic agent for treating atopic dermatitis.

Isolation and phenotypic characterization of mucosal nasal lymphocytes by direct ex vivo analysis

Cellular inflammation of the nasal mucosa demonstrates a local immune response which plays an important role in allergic rhinitis. The aim of the present study was to characterize nasal mucosal lymphocytes regarding their activation and differentiation state by direct ex vivo flowcytometric analysis. Lymphocytes from the inferior turbinates were isolated by a mechanical method of preparation and, for comparison, from peripheral blood by Ficoll gradient centrifugation. Patients suffering from rhinitis or difficulty in nasal breathing were divided into an allergic (pollen-allergy, n = 13) and non-allergic group (n = 24). Expression of different T- and B-cell markers was determined by flowcytometric analysis. CD4+ T-cells from the nasal mucosa exhibited a memory phenotype (CD45RO+, 97%), were highly activated (CD69+, 43-73%), and showed low expression of the cutaneous lymphocyte antigen (CLA+, 5%). Nasal CD20+ B-lymphocytes expressed significantly higher levels of mIgE and lower levels of CD23 and CD80 than peripheral B-cells. Subsets of CD80+ (4%) and CD86+ (6%) CD20+ B-lymphocytes were identified in the nasal mucosa. No significant differences between allergic and non-allergic individuals were determined. As expected, the data show profound phenotypical differences between circulating peripheral blood and nasal mucosal lymphocytes. Activated memory lymphocytes are present in the nasal mucosa from allergic, but also non-allergic patients and may indicate to a significant role of a local inflammatory state without systemic criteria for allergy. In our study, we show that direct ex vivo isolation of lymphocytes is practicable method and offers a new technique to examine the local nasal allergic immune response using a multiparametric phenotypical analysis.

Antigen specific cytokine response in pediatric patients with atopic dermatitis

The physiopathology of atopic dermatitis (AD) has still to be elucidated. T effector cells with cutaneous homing receptors or T-cell derived cytokines have been assumed to be implicated in the pathogenetic mechanisms in AD and to be responsible for the different immunologic responses of patients. In fact, the large majority of AD patients display high IgE levels while others do not develop an abnormal IgE response. Although, there are not significant clinical features characterizing the two different groups, patients with normal IgE belong to a younger age range, raising the possibility that the hypothesized dichotomy of AD might be due to age. In the present study we included 172 outpatient children attending the Pediatric Department of our institution. Serum IgE levels and percentages of peripheral T lymphocytes expressing the cutaneous homing antigen (CLA) were evaluated and results were analyzed in relation to the activity of the disease (SCORAD index) or age. In the overall patients, the IgE levels increased significantly with age (0-1 yr: 19.50 IU/ml; 1-3 yr: 62.0 IU/ml; 3-8 yr: 96.0 IU/ml; >8 yr: 148.5 IU/ml; p<0.001) and with the severity of the disease (SCORAD low: 46.80 IU/ml; medium: 42.90 IU/ml; high: 148.5 IU/ml; p=0.01). Percentages of CLA+ peripheral T lymphocytes also increased with age (0-1 yr: 3.3; 1-3 yr: 4.85; 3-8 yr: 10.6; >8 yr: 12.5; p<0.001), although they were not significantly different in patients with different SCORAD (p=0.89). We further investigated the cellular immune response to a specific antigen in 25 subjects, matched for age, SCORAD, and CLA+ T-cell percentages. Among them, 13 patients had casein serum specific IgE and 12 had no evidence of casein sensitization. Peripheral blood mononuclear cells were kept in short-term culture with endotoxin-free casein fractions and IFN-gamma, TNF-alpha, IL-5, IL-10 cytokine-producing cells were detected by ELISpot. Statistical analysis showed significant higher numbers of TNF-alpha- or IL-10-producing cultures (stimulation index >3) in the 'allergic' patients than in the milk tolerant subjects (p=0.01 and 0.05). The analysis of individual responses confirmed this finding but also provide evidence of a significant increase in IFN-gamma-producing cells (p=0.05) induced by casein stimulation in the group of 'non-allergic' children. Our data showed that immunologic parameters as IgE levels or CLA+ T cells in AD pediatric patients are influenced by the age, confirming that age could represent a bias in the analysis of immune response in those patients. Although, we demonstrated in children with AD the existence of different cytokine patterns of the lymphocyte response that could account for the different immunologic features between the two hypothesized forms of AD, which are not dependent on age.

Expression of intercellular adhesion molecules on circulating lymphocytes in relation to different manifestations of cow's milk allergy

BACKGROUND

The complex interactions between immune cells are partly mediated by different adhesion molecules, but little is known about their role in the systemic immunoinflammatory process following sensitization to food antigens in early infancy.

OBJECTIVE

The aim of this study was to investigate the expression of intercellular adhesion molecule-1 (ICAM-1or CD54) and the alpha subunits of its ligands' lymphocyte function-associated antigen-1 (LFA-1) (alphaL subunit or CD11a) and Mac-1 (alphaM subunit or CD11b) on peripheral blood leucocytes in infants with cow's milk allergy (CMA) and in healthy controls.

METHODS

Thirty-nine breastfed infants, aged from 0.6 to 8.3 months, and their lactating mothers were included in the study from delivery onwards. During follow-up, 25 infants developed CMA and 14 remained healthy. Expressions of CD54 and CD11b on peripheral blood leucocytes were evaluated by flow cytometry. In addition, the expression of CD11a on peripheral blood leucocytes was analysed by immunocytochemistry. Mothers' milk samples were collected and their leucocyte content was evaluated using a light microscope.

RESULTS

The frequency of ICAM-1 expressing peripheral blood lymphocytes was significantly higher in patients with CMA than in healthy infants (P=0.03, Mann-Whitney U-test). Furthermore, the high proportion of ICAM-1-expressing cells was associated with gastrointestinal and multiorgan symptoms in the CMA infants. There was no significant difference in the expression of Mac-1 alphaM on lymphocytes in our study groups, but the LFA-1 alphaL expression seemed to be higher in the IgE-mediated CMA.

CONCLUSION

We suggest that the high expression of ICAM-1 on peripheral blood lymphocytes may reflect enhanced stimulation of T cells in vivo and their migration to the effector tissues in an early-phase of developing CMA. Furthermore, high ICAM-1 expression may be associated with the presence of multiorgan manifestations of CMA, whereas high LFA-1 expression may reflect the IgE-mediated disease.

Milk-induced urticaria is associated with the expansion of T cells expressing cutaneous lymphocyte antigen

BACKGROUND

Two forms of IgE-mediated skin reactions, atopic dermatitis (AD) and urticaria, have been associated with milk allergy. The reason for these distinct reactions is poorly understood. T cells expressing cutaneous lymphocyte antigen (CLA), a unique skin-homing receptor, are known to play an important role in AD. In contrast, the role of lymphocytes in patients with milk-induced urticaria is unclear.

OBJECTIVE

The expression of the skin-specific homing receptor CLA after in vitro milk protein-specific stimulation was investigated to determine whether T-lymphocyte homing to the skin plays a role in food-induced urticaria.

METHODS

Fourteen patients with milk-induced urticaria but no evidence of AD were included in the study and compared with 6 children with milk-induced AD, 6 children with milk-induced gastrointestinal diseases, and 6 nonatopic and 6 atopic individuals without milk allergy. PBMCs were cultured in the presence or absence of caseins or tetanus toxoid. T-cell proliferation was determined, and T-cell phenotyping was performed by means of flow cytometry with anti-CD4, anti-CD8, and anti-CLA mAbs.

RESULTS

After in vitro stimulation with caseins, PBMCs from patients with milk-induced urticaria and AD had a significantly greater percentage of CD4(+) T cells expressing CLA than patients with milk-induced gastrointestinal symptoms and atopic or nonatopic control subjects. After tetanus stimulation in vitro, no significant difference between the groups was observed. T cells from both patients with milk-induced urticaria and control subjects proliferated well in response to caseins and tetanus.

CONCLUSION

Lymphocytes expressing CLA are selectively activated in patients with milk-induced urticaria and may play an important role in the pathogenesis of this disease. Expression of CLA is not unique to milk-induced inflammation in the skin of patients with AD and milk allergy.