Eosinophilic oesophagitis: relevance of mast cell infiltration

Aims

Eosinophilic oesophagitis (EoE) is a chronic inflammatory disease characterised clinically by symptoms of oesophageal dysfunction and histopathologically by a prominent eosinophilic inflammation. Despite eosinophils having a histologically predominant position, their role in the immunopathogenesis of the disease is still questionable. Several other inflammatory cells are involved and may also play a critical role. The purpose of this study was to characterise the mast cell infiltration, and to correlate it with the clinical state of EoE.

Methods and results

Using immunohistochemistry and quantitative morphometry, we investigated eosinophils and mast cells extensively in oesophageal biopsies from patients with active EoE and from patients with EoE in remission, and compared the findings with healthy individuals. In EoE, epithelium and lamina propria were similarly infiltrated with eosinophils. In contrast, mast cells infiltration was limited to the epithelium, displaying a localised immune response. Interestingly, whereas epithelial mast cells and eosinophils were high in active EoE, some patients in remission, e.g. normalised epithelial eosinophils, showed remaining high numbers of mast cells. Patient clustering supported two groups of patients in clinical remission, differentiating based on presence or absence of epithelial mast cells.

Conclusions

Active EoE is characterised in addition to the well‐known tissue eosinophilia by a marked epithelium‐restricted mast cell infiltration. Of interest, in a subgroup of patients, mast cell infiltration persisted despite clinical remission. To elucidate the clinical consequence of persistent epithelial mast cells infiltration further studies are required following patients in clinical remission longitudinally.     

IL‐33 activates eosinophils of visceral adipose tissue both directly and via innate lymphoid cells

Eosinophils are multifunctional leukocytes involved in allergic reactions as well as adipose tissue regulation. IL‐5 is required for eosinophil survival; however, the in vivo mechanisms of eosinophil regulation are not fully understood. A tg mouse model with il5 promoter‐driven EGFP expression was established for detecting the IL‐5‐producing cells in vivo. Il5‐egfp tg mice expressed high levels of EGFP in gonadal adipose tissue (GAT) cells. EGFP⁺ cells in GAT were mainly group 2 innate lymphoid cells (ILCs). IL‐33 preferentially expanded EGFP⁺ cells and eosinophils in GAT in vivo. EGFP⁺ ILCs were found to upregulate prg2 mRNA expression in GAT eosinophils. These results demonstrate that ILCs activate eosinophils in GAT. The blockage of IL‐33Rα, on the other hand, did not impair EGFP⁺ ILC numbers but did impair eosinophil numbers in vivo. GAT eosinophils expressed IL‐33Rα and IL‐33 expanded eosinophil numbers in CD90⁺ cell‐depleted mice. IL‐33 was further observed to induce the expression of retnla and epx mRNA in eosinophils. These findings demonstrate that IL‐33 directly activates eosinophils in GAT, and together with our other findings described above, our findings show that IL‐33 has dual pathways via which it activates eosinophils in vivo: a direct activation pathway and a group 2 ILC‐mediated pathway.     

Comparison of histological parameters for the diagnosis of eosinophilic oesophagitis versus gastro‐oesophageal reflux disease on oesophageal biopsy material

Aims: Eosinophil infiltration of the oesophageal epithelium is the cardinal pathomorphological finding in eosinophilic oesophagitis (EO), but gastro‐oesophageal reflux disease (GORD) is also associated with increased eosinophils. The aim was to compare histological parameters for the diagnosis of EO versus GORD on routinely taken biopsy specimens. Methods and results: One hundred and five routine biopsy specimens with EO (n = 62), GORD (n = 24) and probable EO (n = 19) from 74 patients (52 men, 22 women; mean age 43.7 years) were analysed for numbers of eosinophils, mast cells, degranulation and qualitative changes of oesophageal epithelium using immunohistochemistry with monoclonal antibodies against eosinophil peroxidase and eosinophil major basic protein and mast cell tryptase. Eosinophil infiltration was significantly higher in EO than in GORD both on haematoxylin and eosin staining (54.8 versus 9.1; P < 0.05) and immunohistochemistry (77.5 versus 24.7; P < 0.05). Eosinophil degranulation was significantly more intense in EO than in GORD (1.16 versus 0.41; P < 0.05). Furthermore, eosinophilia‐codependent secondary qualitative changes of squamous epithelium in EO were generally more extensive than those in GORD. Conclusions: Histological differential diagnosis of EO and GORD should be based on eosinophil counts, secondary morphological changes of eosinophils and oesophageal squamous epithelium, especially in cases suspicious of EO.     

Children with atopic histories exhibit impaired lipopolysaccharide‐induced Toll‐like receptor‐4 signalling in peripheral monocytes

Background The hygiene hypothesis states that early exposure to bacterial products such as lipopolysaccharide (LPS) may be protective against the development of allergic diseases. Whether atopic disease affects the ability of immune cells to respond to LPS is unclear. Our laboratory has demonstrated previously that children express high levels of Toll‐like receptor (TLR)‐4 on CD4⁺ cells in nasal mucosa. Objective To determine if children with a history of allergic disease have impaired responses to LPS on circulating CD4⁺ leucocytes. Methods Peripheral blood mononuclear cells from children (aged 2–18) and adults with or without a history of atopic conditions were cultured with/without IL‐4 or LPS for up to 24 h. Expression of surface TLR‐4, CD14, CD4, CD3, as well as of intracellular phosphorylated ^p42/p44ERK and p38 mitogen‐activated protein kinase (MAPK) were assessed by flow cytometry. Results A history of atopy in children was associated with impaired LPS‐induced TLR‐4‐dependent phosphorylation of ^p42/44ERK and p38 MAPK by CD4⁺ monocytes. Decreased LPS signalling was reproduced by pre‐incubation of control cells with recombinant IL‐4. LPS stimulation also decreased TLR‐4 expression on monocytes from children without atopic histories but not from atopic subjects. CD4⁺ T lymphocytes showed limited LPS responsiveness, regardless of atopic status. In contrast with non‐atopic children, TLR‐4 expression on monocytes of children with atopic histories decreased as a function of age. Conclusions This study provides evidence for defective LPS recognition on circulating CD4⁺ leucocytes of subjects with atopic histories compared with those from non‐atopic children. CD4⁺TLR4⁺ monocytes from children with atopic histories failed to phosphorylate MAPKs. Our results suggest that a history of atopic disease is associated with impaired TLR‐4‐mediated innate immune function compared with non‐atopic children. Cite this as: D. Préfontaine, A.‐A. Banville‐Langelier, P.‐O. Fiset, J. Guay, J. An, M. Mazer, Q. Hamid and B. D. Mazer, Clinical & Experimental Allergy, 2010 (40) 1648–1657.     

TNF α is localized to nasal mucosal mast cells and is released in acute allergic rhinitis

Allergic mucosal inflammation is characterized by tissue infiltration with eosinophils, and associated activation of mast cells and T lymphocytes. Tumour necrosis factor (TNF) alpha/cachectin is a candidate cytokine relevant to the pathogenesis of these events through its capacity to upregulate the expression of endothelial cell adhesion molecules, mediate granulocyte chemoattraction, and activate eosinophils, mast cells and T cells. To investigate the presence and localization of TNF α in the nasal mucosa in allergic rhinitis, nasal biopsies from perennial rhinitic (n=13) and non-rhinitic volunteers (n=11) were embedded in glycol methacrylate and immunostained with a monoclonal antibody directed against TNF α, and adjacent 2μm sections stained for tryptase, CD3 and eosinophil cationic protein. This identified positive immunostaining for TNF α in the submucosa of both the rhinitic and normal subjects (median cell counts 13 and 23 cells/mm² respectively, P=0.24) with cellular localization to mast cells but not to T-lymphocytes or eosinophils. In a subsequent study of seven atopic subjects, nasal allergen challenge produced increases in lavage levels of histamine and albumin, which was associated with significant release of TNF α as early as 2 min post-allergen when compared with the saline control day (P=0.5). This difference was also apparent when studying the area under the curve both at 30 and 60 min post-challenge t-test (P=0.015 and 0.02 respectively). These findings which both locate immunoreactive TNF α to nasal mast cells and identify its release following in vivo exposure to allergen, provide evidence for mast cells as an important source of this cytokine in patients with allergic rhinitis.     

Interleukin-5 mRNA expressed by eosinophils and γ/δ T cells in parasite-immune sheep

Interleukin (IL)-5 is produced by a variety of cell types and contributes to both lymphocyte development and eosinophil terminal differentiation in vitro. The coincidence of worm expulsion and eosinophilia in sheep infected with the gastrointestinal nematode Trichostrongylus colubriformis suggests that eosinophils may be involved as effector cells in host immunity against parasite infection. The role of IL-5 in this process was investigated by observing the distribution of IL-5 mRNA⁺ cells in the small intestine, mesenteric lymph nodes (MLN) and Peyer's patches (PP) by an in situ hybridization technique using a murine IL-5 riboprobe. IL-5 mRNA⁺ cells were distributed throughout the lamina propria (LP) of the small intestine from the tips of the villi to the muscularis mucosae and in the parafollicular areas of MLN and PP in both naive and immune sheep. The phenotypes of IL-5 mRNA⁺ cells was explored by simultaneous eosin and immunohistochemical staining using a monoclonal antibody recognizing the T19 marker, which identifies a major subset of γ/α TCR⁺ cells in sheep. In immune sheep, there was about a five-fold increase in the number of eosinophils and IL-5 mRNA⁺ cells in the LP, but there was no significant change in numbers of T19⁺ cells. Most of the IL-5 mRNA⁺ cells in the LP were eosinophils, but many of the T19⁺ cells also expressed IL-5 mRNA. In contrast, there were fewer eosinophils than T19⁺ cells in MLN of immune sheep and, compared to controls, a threefold increase in T19⁺ cells and a five-fold increase in T19⁺/IL-5 mRNA⁺ double-positive cells was observed in immune sheep. In PP, there were very few eosinophils but substantial numbers of T19⁺ cells; however, no significant differences in numbers of eosinophils, T19⁺ or IL-5 mRNA⁺ cells were observed between control and immune sheep. These results indicate that in sheep, both eosinophils and γ/δ T cells are capable of IL-5 expression and suggest that IL-5 is an important regulatory factor in autocrine and paracrine activation of effector cells involved in parasite immune expulsion.     

IL‐33‐activated murine mast cells control the dichotomy between RORγt+ and Helios+ Tregs via the MK2/3‐mediated IL‐6 production in vitro

In mast cells, IL‐33 typically induces the activation of NF‐κB, which results in the production of cytokines such as IL‐6 and IL‐2. Here, we demonstrate that the IL‐33‐induced IL‐6 production in murine mast cells and the formation of RORγt⁺ T_regs essentially depends on the MAPKAPs, MK2, and MK3 (MK2/3) downstream of MyD88. In contrast to this, the IL‐33‐induced and MyD88‐dependent IL‐2 production in mast cells contributes to the maintenance of Helios⁺ T_regs. Thereby, the IL‐33‐induced IL‐2 response and, thus, the maintenance of Helios⁺ T_regs are limited by an IL‐6‐mediated autocrine negative feedback stimulation acting on mast cells. Collectively, we present MK2/3 in IL‐33‐activated mast cells as a signaling node, which controls the dichotomy between RORγt⁺ T_reg and Helios⁺ T_reg in vitro.     

Pulmonary periarterial inflammation in fatal asthma

Background To date, little information has been available about pulmonary artery pathology in asthma. The pulmonary artery supplies the distal parts of the lungs and likely represents a site of immunological reaction in allergic inflammation. The objective of this study was to describe the inflammatory cell phenotype of pulmonary artery adventitial inflammation in lung tissue from patients who died of asthma. Methods We quantified the different inflammatory cell types in the periarterial region of small pulmonary arteries in lung tissue from 22 patients who died of asthma [fatal asthma (FA)] and 10 control subjects. Using immunohistochemistry and image analysis, we quantified the cell density for T lymphocytes (CD3, CD4, CD8), B lymphocytes (CD20), eosinophils, mast cells (chymase and tryptase), and neutrophils in the adventitial layer of pulmonary arteries with a diameter smaller than 500 μm. Results Our data (median/interquartile range) demonstrated increased cell density of mast cells [FA=271.8 (148.7) cells/mm²; controls=177.0 (130.3) cells/mm², P=0.026], eosinophils [FA=23.1 (58.6) cells/mm²; controls=0.0 (2.3) cells/mm², P=0.012], and neutrophils [FA=50.4 (85.5) cells/mm²; controls=2.9 (30.5) cells/mm², P=0.009] in the periarterial space in FA. No significant differences were found for B and T lymphocytes or CD4⁺ or CD8⁺ subsets. Chymase/tryptase positive (MC_CT) mast cells predominated over tryptase (MC_T) mast cells in the perivascular arterial space in both asthma patients and controls [MC_CT/(MC_CT+MC_T)=0.91 (0–1) in FA and 0.75 (0–1) in controls, P=0.86]. Conclusions Our results show that the adventitial layer of the pulmonary artery participates in the inflammatory process in FA, demonstrating increased infiltration of mast cells, eosinophils, and neutrophils, but not of T and B lymphocytes.     

Allergen-induced recruitment of FcσRI+ eosinophils in human atopic skin

We have attempted to identify FcσRI⁺ eosinophils in cutaneous late-phase reaction in atopic subjects biopsied at 6, 24 and 48 h after the injection of either allergen or a diluent control. Compared to the diluent sites, allergen-injected sites had significantly increased numbers of eosinophils, peaking between 6 and 24 h, of which approximately 20–30% expressed mRNA for the α, β, and γ chains of FcσRI, as shown by in situ hybridization. Using either a monoclonal or a polyclonal anti-α chain antibody, the FcσRIα protein also co-localized to approximately 50–80% of eosinophils at all time points studied. We also observed a significant correlation (r = 0.89; p = 0.02) between the numbers of FcσRI⁺ (997⁺)/EG2⁺ eosinophils and the magnitude of the late-phase reaction. Thus, a significant proportion of eosinophils infiltrating the site of allergen-induced allergic tissue reactions in atopic subjects express FcσRI. The findings show that high-affinity IgE receptors may play a role in eosinophil secretory processes in vivo.     

Immunoglobulin E antibodies enhance pulmonary inflammation induced by inhalation of a chemical hapten

Background Occupational exposure to chemicals is an important cause of asthma. Recent studies indicate that IgE antibodies enhance sensitization to chemicals in the skin. Objective We investigated whether IgE might similarly promote the development of airway inflammation following inhalation of a contact sensitizer. Methods A model of chemical‐induced asthma is described in which introduction of the low‐molecular‐weight compound, trinitrobenzene sulphonic acid (TNBS), via the respiratory tract was used for both sensitization and challenge. The role of IgE antibodies in the immune response to inhaled TNBS in this model was assessed by comparing the responses of wild‐type (WT) and IgE‐deficient (IgE^?/?) mice on the BALB/c background. Reconstitution of circulating IgE levels by intravenous injection of IgE antibodies into IgE^?/? mice before sensitization was performed to confirm the role of IgE in any differences observed between the responses of WT and IgE^?/? mice. Results Intranasal challenge of TNBS‐sensitized (but not sham‐sensitized control mice) induced intense pulmonary inflammation. Macrophages, eosinophils and lymphocytes, including T, B, natural killer and natural killer T cells, were recruited to the airway and the animals displayed bronchial hyperresponsiveness (BHR) to methacholine. Serum levels of murine mast cell protease‐1 (mMCP‐1) were elevated suggesting mast cell activation. In contrast, the development of airway inflammation, recruitment of lymphocytes, induction of BHR and production of mMCP‐1 were all significantly attenuated in IgE‐deficient mice. Reconstitution of IgE^?/? mice with IgE (of unrelated antigen specificity) before sensitization partially restored these features of asthma. Conclusion Our data indicate that IgE antibodies non‐specifically enhance the development of airway inflammation induced by exposure to chemical antigens.     

Bone marrow type 2 innate lymphoid cells: a local source of interleukin‐5 in interleukin‐33‐driven eosinophilia

T helper type 2 (Th2) cells, type 2 innate lymphoid cells (ILC2s) and eosinophil progenitors have previously been described to produce interleukin‐5 (IL‐5) in the airways upon allergen provocation or by direct administration of IL‐33. Eosinophilic airway inflammation is known to be associated with IL‐5‐dependent eosinophil development in the bone marrow, however, the source of IL‐5 remains unclear. T helper cells, ILC2s and CD34⁺ progenitors have been proposed to be involved in this process, therefore, we investigated whether these cells are taking part in eosinophilopoiesis by producing IL‐5 locally in the bone marrow in IL‐33‐driven inflammation. Airway exposure with IL‐33 led to eosinophil infiltration in airways and elevated eotaxin‐2/CCL24. Importantly, IL‐5 production as well as expression of the IL‐33 receptor increased in ILC2s in the bone marrow under this treatment. A small but significant induction of IL‐5 was also found in CD34⁺ progenitors but not in T helper cells. Similar results were obtained by in vitro stimulation with IL‐33 where ILC2s rapidly produced large amounts of IL‐5, which coincided with the induction of eosinophil hematopoiesis. IL‐33‐mediated eosinophil production was indeed dependent on IL‐5 as both airway and bone marrow eosinophils decreased in mice treated with anti‐IL‐5 in combination with IL‐33. Interestingly, the responsiveness of ILC2s to IL‐33 as well as IL‐33‐induced eotaxin‐2/CCL24 were independent of the levels of IL‐5. In summary, we demonstrate for the first time that IL‐33 acts directly on bone marrow ILC2s, making them an early source of IL‐5 and part of a process that is central in IL‐33‐driven eosinophilia.     

EGF receptor activation during allergic sensitization affects IL‐6‐induced T‐cell influx to airways in a rat model of asthma

EGF receptor (EGFR) is involved in cell differentiation and proliferation in airways and may trigger cytokine production by T cells. We hypothesized that EGFR inhibition at the time of allergic sensitization may affect subsequent immune reactions. Brown Norway rats were sensitized with OVA, received the EGFR tyrosine kinase inhibitor, AG1478 from days 0 to 7 and OVA challenge on day 14. OVA‐specific IgE in serum and cytokines and chemokines in BAL were measured 24 h after challenge. To evaluate effects on airway hyperresponsiveness (AHR), rats were sensitized, treated with AG1478, intranasally challenged, and then AHR was assessed. Furthermore chemotactic activity of BALF for CD4⁺ T cells was examined. The eosinophils, neutrophils and lymphocytes in BAL were increased by OVA and only the lymphocytes were reduced by AG1478. OVA significantly enhanced IL‐6 concentration in BAL, which was inhibited by AG1478. However AHR, OVA‐specific IgE and IL‐4 mRNA expression in CD4⁺ T cells were not affected by AG1478. BALF from OVA‐sensitized/challenged rats induced CD4⁺ T‐cell migration, which was inhibited by both AG1478 treatment in vivo and neutralization of IL‐6 in vitro. EGFR activation during sensitization may affect the subsequent influx of CD4⁺ T cells to airways, mainly mediated through IL‐6.     

The prognostic value of intraepithelial and stromal CD3‐, CD117‐ and CD138‐positive cells in non‐small cell lung carcinoma

Al‐Shibli K, Al‐Saad S, Andersen S, Donnem T, Bremnes RM, Busund L‐T. The prognostic value of intraepithelial and stromal CD3‐, CD117‐ and CD138‐positive cells in non‐small cell lung carcinoma. APMIS 2010; 118: 371–82. The major value of prognostic markers in potentially curable non‐small cell lung carcinoma (NSCLC) should be to guide therapy after surgical treatment. Although tumor‐infiltrating T lymphocytes and plasma cells have been documented in NSCLC, a clear association with clinical outcome, especially for the stromal component, has not been well established. The aim of this study was to elucidate the prognostic significance of these cells/markers in the epithelial and stromal compartments of NSCLC. Tissue microarrays from 335 resected, stage I‐IIIA, NSCLC were constructed by duplicate cores from viable neoplastic epithelial and stromal areas. Immunohistochemistry was used to evaluate the infiltration of CD3⁺, CD117⁺ as well as CD138⁺ cells in epithelial and stromal areas. In univariate analyses, increasing numbers of stromal CD3⁺ (p = 0.001) and epithelial CD3⁺ cells (p = 0.004) correlated significantly with an improved disease‐specific survival. No such relation was noted with CD3⁺ or CD117⁺ cells. In the multivariate analysis, stromal CD3⁺ cells was an independent prognostic factor for disease‐specific survival (HR 1.925, CI 1.21–3.04, p = 0.005). Increased presence of the pan T‐cell marker, CD3, which is an independent factor, correlates with improved clinical outcome in NSCLC. This prognostic impact of T cells is clearer in the tumor stroma. Neither plasma cells nor mast cells were prognostic indicators in our cohort.     

Secretion of the eosinophil-active cytokines interleukin-5, granulocyte/macrophage colonystimulating factor and interleukin-3 by bronchoalveolar lavage CD4+ and CD8+ T cell lines in atopics asthmatics,and atopic and nonatopic controls

Specific eosinophil accumulation and activation within the asthmatic bronchial mucosa are thought to occur at least partly through the actions of cytokines, including interleukin (IL)-5, IL-3 and granulocyte/macrophage colonystimulating factor (GM-CSF). Although mRNA encoding some of these cytokines has been demonstrated in bronchoalveolar lavage (BAL) fluid cells and bronchial biopsies from asthmatics, it has yet to be established whether these cells produce the translated products and whether expression is associated with CD4⁺ T helper or CD8⁺ cytotoxic T cells. We addressed this problem by raising polyclonal CD4⁺ and CD8⁺ T cell lines from the BAL fluid of six atopic asthmatics, five atopic non-asthmatics and seven non-atopic non-asthmatic controls. BAL fluid cells obtained at fiberoptic bronchoscopy were depleted of adherent cells, and then T lymphocytes expanded by stimulation with monoclonal anti-CD3 antibody and recombinant human IL-2. When lymphocytes had expanded to sufficient numbers, CD4⁺ and CD8⁺ cells were separated by positive selection with magnetic beads coated with anti-CD4 or anti-CD8 monoclonal antibodies and further expanded. Cytokine secretion by standardized cell numbers was measured by enzyme-linked immunosorbent assays. BAL CD4⁺ T cell lines from the asthmatics secreted significantly elevated quantities of both IL-5 and GM-CSF as compared with lines from the atopic and non-atopic controls (p = 0.023–0.003). In contrast, IL-3 secretion did not significantly differ between the groups. In some subjects, CD8⁺ T cell lines also secreted significant quantities of these cytokines and there was a trend for IL-5 secretion by these cells to be higher in asthmatics than non-atopic controls (p = 0.035). These data are consistent with the hypothesis that activated T lymphocytes from asthmatics, particularly of the CD4⁺ subset, are predisposed to release elevated quantities of cytokines relevant to the accumulation and activation of eosinophils.     

The role of mast cells and eosinophils in chronic gastritis

Abstract The role of mast cells and eosinophils in influencing the pathology of chronic gastritis remains unclear. We attempted to study the relationship between endoscopy and the mast cell and eosinophil infiltrate. We also studied the role of gene polymorphisms, Helicobacter pylori density and the CagA antibody status in influencing the mast cell and eosinophil infiltrate. One hundred and twenty consecutive patients were studied. Endoscopic evaluation was done and 3 antral biopsies were taken from each patient and were assessed for eosinophilic and mast cell infiltration, H. pylori density and the density of the other inflammatory cells as per the revised Sydney system. Cytokine gene polymorphisms (IL-1β, IL-1RA and TNF-α) were done on the DNA extracted from the peripheral blood by PCR-RFLP. ELISA was done on the patients’ serum for the anti-CagA antibody titres. Nodularity is strongly associated with the presence and density of eosinophils on biopsy (P< 0.05). Eosinophil density is strongly associated with the density of H. pylori, neutrophils, lymphocytes, plasma cells, atrophy, ulceration, foveolitis and lymphoid follicles. The mast cell density is not associated with any of the other histopathological variables. Gene polymorphisms and the CagA antibody titres have no relationship to the mast cell and eosinophil density. Eighty-one patients showed positive anti-CagA antibody titres but there was no association with the eosinophilic or the mast cell infiltrate. It is likely that eosinophilic infiltration is influenced by the H. pylori density but the CagA protein has no role to play in influencing the grade of the eosinophilic infiltrate in the Indian context. Cytokine gene proinflammatory polymorphisms have no role to play in influencing the eosinophilic or the mast cell response. It is likely that other mediators are involved in the inflammatory cell responses.     

Immune Response Against 2,4‐Dinitrofluorobenzene‐Induced Atopic Dermatitis‐Like Clinical Manifestation is Suppressed by Spermidine in NC⁄Nga Mice

Of the biogenic polyamines, spermidine is a natural constituent of living cells and organisms. Spermidine is associated with regulation of cell growth, proliferation and differentiation, and with the suppression of oxidation and inflammation. Atopic dermatitis (AD) is a chronic inflammatory skin disease that has a complex and multiple pathogenesis, which includes genetic abnormality, modified or abnormal immune response and the production of nitric oxide and reactive oxygen species. We investigated whether spermidine can relieve AD‐like clinical manifestation induced by the continual application of 2,4‐dinitrofluorobenzene (DNFB) in NC?Nga mice. Spermidine at concentrations of 1 or 10 mg/kg reduced increasing ear swelling and attenuated oedema, haemorrhage and hyperkeratosis in AD‐like skin lesions. Repetitive application of DNFB induced inflammatory cell infiltration to skin lesions, whereas intraperitoneal injection of spermidine inhibited DNFB‐evoked infiltration of eosinophils, mast cells and T lymphocytes. Furthermore, spermidine suppressed mast cell degranulation and production of interferon‐gamma by activated CD4⁺ T cells in AD‐like skin lesions. Spermidine may be a potential therapeutic agent for treatment of AD.     

Ingestion of heat-treated Lactobacillus rhamnosus GG prevents development of atopic dermatitis in NC/Nga mice

Background Continuous oral administration of live Lactobacillus rhamnosus GG (L. GG) to pregnant subjects with atopic dermatitis and their children, suppressed the frequency of atopic dermatitis. The details of mechanisms and immune systems involved in this suppressive effect, however, remain speculative. Objective We sought to clarify suppressive mechanisms of L. GG on atopic dermatitis by using NC/Nga mice, a model of human atopic dermatitis. Methods Maternal mice and infant mice were fed with food containing or not containing heat‐treated L. GG during pregnancy and breastfeeding, and after weaning. Results Control NC/Nga mice raised under an air‐uncontrolled condition spontaneously manifested typical skin lesions very similar to those in patients with atopic dermatitis. On the other hand, administration of food containing heat‐treated L. GG inhibited the onset and development of atopic skin lesions, accompanied by smaller numbers of mast cells and eosinophils in the affected skin sites. Mice fed with L. GG showed a significant increase in plasma IL‐10 levels compared with control mice, while there was no significant difference in the proportion of splenic CD4⁺CD25⁺ regulatory T cells between mice fed with L. GG and control mice. The IL‐10 mRNA expression was enhanced in both Peyer's patches and mesenteric lymph nodes in mice fed with L. GG. Conclusion These findings suggest that some components of heat‐treated L. GG may have an ability to delay the onset and suppress the development of atopic dermatitis, probably through a strong induction of IL‐10 in intestinal lymphoid organs and systemic levels.     

Evaluation of peroxisome proliferator‐activated receptor agonists on interleukin‐5‐induced eosinophil differentiation

Peroxisome proliferator‐activated receptor (PPAR) agonists have been suggested as novel therapeutics for the treatment of inflammatory lung disease, such as allergic asthma. Treatment with PPAR agonists has been shown to inhibit airway eosinophilia in murine models of allergic asthma, which can occur through several mechanisms including attenuated generation of chemoattractants (e.g. eotaxin) and decreased eosinophil migrational responses. In addition, studies report that PPAR agonists can inhibit the differentiation of several cell types. To date, no studies have examined the effects of PPAR agonists on interleukin‐5 (IL‐5) ‐induced eosinophil differentiation from haemopoietic progenitor cells. Non‐adherent mononuclear cells or CD34⁺ cells isolated from the peripheral blood of allergic subjects were grown for 2 weeks in Methocult^® cultures with IL‐5 (10 ng/ml) and IL‐3 (25 ng/ml) in the presence of 1–1000 nm PPARα agonist (GW9578), PPARβ/δ agonist (GW501516), PPARγ agonist (rosiglitazone) or diluent. The number of eosinophil/basophil colony‐forming units (Eo/B CFU) was quantified by light microscopy. The signalling mechanism involved was assessed by phosphoflow. Blood‐extracted CD34⁺ cells cultured with IL‐5 or IL‐5 + IL‐3 formed Eo/B CFU, which were significantly inhibited by rosiglitazone (100 nm , P < 0·01) but not GW9578 or GW501516. In addition, rosglitazone significantly inhibited IL‐5‐induced phosphorylation of extracellular signal‐regulated kinase 1/2. We observed an inhibitory effect of rosiglitazone on eosinophil differentiation in vitro, mediated by attenuation of the extracellular signal‐regulated kinase 1/2 signalling pathway. These findings indicate that the PPARγ agonist can attenuate tissue eosinophilia by interfering with local differentiative responses.     

Attenuation of allergic airway inflammation in IL-4 deficient mice

To investigate the role of IL-4 in vivo in allergic asthma, we developed a murine model of allergen-induced airway inflammation. Repealed daily exposures of actively immunised C57BL/6 mice to aerosolized ovalbumin (OVA) induced a peribronchial inflammation and an increase in eosinophils and lymphocytes in bronchoalveolar-lavage(BAL) fluid. In IL-4 deficient (IL4^?/?) mice, treated in the same way, there were substantially fewer eosinophils in BAL and much less peribronchial inflammation compared with wild type mice. In this model, mast cell deficient (W/W^v) mice developed a similar degree of BAL eosinophilia and peribronchial inflammation as wild type mice, demonstrating that the mast cell is not required for the induction of chronic airway inflammation. In contrast, BAL eosinophilia and airway inflammation were absent in OVA-treated MHC ClassII deficient (B6.Aa^?/?) mice which lack mature CD4⁺ T lymphocytes. In conclusion, these results indicate that IL-4 is a central mediator of allergic airway inflammation, regulating antigen-induced eosinophil recruitment into the airways by a T cell dependent mechanism.