Polyclonal IgE induces mast cell survival and cytokine production.

BACKGROUND: Ag-dependent activation of IgE-bearing mast cells is a critical first step in immediate hypersensitivity and other allergic responses. Recent studies have revealed Ag-independent effects of monoclonal mouse IgE molecules on mast cell survival and activation. However, no studies have been performed on the effects of polyclonal IgE molecules. Here, we tested whether polyclonal mouse and human IgE molecules affect survival and cytokine production in mast cells. METHODS: Mast cells were cultured in the presence of polyclonal mouse and human IgE molecules, and cell survival and cytokine production were analyzed. RESULTS: Polyclonal mouse IgE molecules in sera from mice with atopic dermatitis-like allergic skin inflammation, enhanced survival and cytokine production in mast cell cultures. Similar to the effects of monoclonal IgE, the polyclonal IgE effects were mediated by the high-affinity IgE receptor, FcepsilonRI. Human polyclonal IgE molecules present in sera from atopic dermatitis patients were also capable of activating mast cells, and inducing IL-8 production in human cord blood-derived mast cells. CONCLUSIONS: These results imply that polyclonal IgE in atopic dermatitis and other atopic conditions might modulate mast cell number and function, thus amplifying the allergic response.

Hyperexpression of NOD2 in intestinal mast cells of Crohn's disease patients: preferential expression of inflammatory cell-recruiting molecules via NOD2 in mast cells.

NOD2, an intracellular sensor of bacteria-derived muramyl dipeptide (MDP) has been implicated as a key player in intestinal immune health and disease. Mast cells (MCs) have been reported to be increased in the gut of patients with inflammatory bowel disease. However, NOD2 expression and its role in human primary MCs are unknown. The number of NOD2(+) intestinal MCs was significantly increased in the Crohn's disease (CD) specimens compared to Ulcerative colitis (UC) specimens and controls. IFN-gamma upregulated NOD2 expression in MCs. CXCL10 and urokinase-type plasminogen activator (uPA) upregulation was specific to MCs activated by MDP compared to MCs activated by LPS and IgE/anti-IgE. MDP-induced upregulation of ICAM-1, VCAM-1, and uPA was specific to MCs compared to mononuclear cells. The number of CXCL10(+)NOD2(+) intestinal MCs was significantly increased in the CD patients. Our results suggest that NOD2(+) MCs have specific pathogenic roles that involve the recruitment of inflammatory cells in CD.

Increased leukotriene E4 in the exhaled breath condensate of children with mild asthma.

BACKGROUND: Chronic airway inflammation is a feature of asthma. Increased levels of cysteinyl leukotrienes (cys-LTs; leukotriene [LT]C(4), LTD(4), LTE(4)) have been shown in the exhaled breath condensate (EBC) of children with moderate-to-severe asthma. The aim of this study was to examine the relationship between EBC cys-LTs (LTE(4)) levels and bronchial hyperreactivity in children with mild asthma in order to evaluate the clinical utility of measuring EBC cys-LTs levels. METHODS: We measured LTE(4) levels in the EBC of children aged 8 to 18 years, including healthy nonasthmatic children (n = 6) and children with mild asthma (n = 37). Patients with mild asthma were classified into the following three groups: group 1, participants who had been asymptomatic (no wheezing/symptoms of asthma) for > 6 months prior to examination (n = 12); group 2, participants who were asymptomatic but had had wheezing/symptoms of asthma within 6 months before examination (n = 18); and group 3, patients with current wheeze and/or mild symptoms of asthma exacerbation at the time of examination. RESULTS: Exhaled LTE(4) levels were increased in all children with mild asthma compared with nonasthmatic control subjects (5.69 +/- 9.62 pg/20 min vs 0.74 +/- 0.79 pg/20 min, p < 0.05) [mean +/- SD]. In particular, the EBC LTE(4) levels in group 2 (4.99 +/- 6.70 pg/20 min) and group 3 (14.66 +/- 17.11 pg/20 min) were increased compared with control subjects and group 1 (1.50 +/- 1.69 pg/20 min). The EBC LTE(4) levels negatively correlated with the provocative concentration of methacholine causing a 15% fall in FEV(1) (r = - 0.454, p = 0.012). CONCLUSION: EBC cys-LTs may be useful as a noninvasive marker assessing airway inflammation and hyperreactivity in children with asthma.

Impaired interferon-gamma production in a subset population of severe atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by pruritic chronic eczema. The immunopathogenesis of this condition is still not well understood. We assessed the transcription and production of IFN-gamma, the Th1 cytokine, and the Th2 cytokine IL-5 in peripheral blood mononuclear cells (PBMCs) from patients with severe AD. METHODS: The subjects included 17 severe (serum IgE: 5,000-92,000 U/ml, median: 20,000 U/ml), 4 mild AD (IgE: 2-520 U/ml) and 8 nonatopic controls (IgE: <100 U/ml). The severe AD patients were classified into two groups according to the response to standard treatment with topical glucocorticoids. Individuals were classified as poorly responsive (AD-P) if the clinical score decreased less than one third after 2 weeks of hospital treatment and as responsive (AD-R) if the score decreased more than one third. PBMCs isolated from the subjects were stimulated with PHA and PMA. RESULTS: The expression of IFN-gamma in PBMCs in the AD-P group was much lower than that observed in the other groups at both mRNA and protein levels. There were no significant differences in the levels of IL-5 both in mRNA and protein levels between the groups. There were no significant differences in STAT4 DNA-binding activity following PHA/IL-2/IL-12 stimulation between AD-P and controls. CONCLUSIONS: These results suggest that the decreased INF-gamma production may account for the abnormal immunopathogenesis of severe, intractable AD.

High-density oligonucleotide array analysis of mRNA transcripts in peripheral blood cells of severe atopic dermatitis patients.

BACKGROUND: There are few laboratory tests for evaluating atopic dermatitis (AD) with the exception of IgE levels or the eosinophil count. We attempted to identify new diagnostic markers by screening the genome-wide expression of transcripts in peripheral blood mononuclear cells (PBMC). METHODS: For this study, we enrolled 7 nonatopic healthy volunteers, 5 AD patients who responded well to treatment and 6 who responded poorly. We compared genome-wide transcript levels in PBMC derived from patients with severe AD and healthy volunteers using high-density oligonucleotide arrays (GeneChip, Affymetrix). After the first screening with GeneChip, we employed real-time quantitative PCR to confirm differential expression levels. RESULTS: Screening with GeneChip showed that the levels of a total of 92 transcripts increased at least 3-fold in one population compared to another. After further evaluation of these genes with real-time quantitative PCR, the levels of 4 transcripts were confirmed to be significantly different in PBMC from AD patients compared to controls, namely IFN-gamma, TRAIL (TNF-related apoptosis-inducing ligand), ISGF-3 (STAT1) and defensin-1. With the exception of IFN-gamma, none of these genes has previously been implicated in AD pathology. CONCLUSION: These 4 transcripts in PBMC are expected to be useful markers for evaluating AD.