Clinical and Experimental Allergy

Ở những bệnh nhân hen phế quản dị ứng, viêm đường thở được khởi phát bởi các tác nhân cụ thể (hít phải các tác nhân gây dị ứng như tác nhân gây dị ứng từ bụi nhà và bào tử phấn hoa) hoặc các tác nhân không cụ thể (như ô nhiễm không khí và nhiễm virus). Hầu hết những hạt hít vào này đều không có hoạt tính miễn dịch. Các tế bào đuôi gai (DCs) là rất quan trọng cho việc chuẩn bị và phân biệt T helper-2 của các tế bào T chưa trưởng thành hướng tới các tác nhân gây dị ứng qua đường hô hấp. Sự ô nhiễm của các kháng nguyên với các kiểu mẫu phân tử liên kết (PAMPs), chẳng hạn như lipopolysaccharide (LPS), là cần thiết để kích hoạt DCs tạo ra một phản ứng miễn dịch. Các kiểu mẫu phân tử liên quan đến tổn thương (DAMPs), chẳng hạn như axit uric và adenosine triphosphate (ATP), cũng góp phần vào việc khởi phát viêm bằng cách kích hoạt và chiêu mộ nhiều tế bào viêm khác nhau. Bằng chứng thuyết phục cho thấy cần có sự hợp tác chặt chẽ giữa PAMPs và DAMPs để bắt đầu một phản ứng miễn dịch đối với các tác nhân gây dị ứng. Một số nghiên cứu gần đây đã chứng minh vai trò quan trọng của các tín hiệu nguy hiểm nội sinh trong giai đoạn khởi đầu và duy trì bệnh dị ứng. Nghiên cứu thêm trong lĩnh vực này nên tập trung vào vai trò có thể có của những yếu tố này trong việc duy trì các bệnh mãn tính và khởi phát quá trình tái cấu trúc đường thở.

Background  Atopic dermatitis (AD) is an inflammatory skin disease whose lesions can have two stages: acute and chronic. In skin biopsies a biphasic pattern of cytokine expression has been shown, Th2 in acute lesions and Th1 in chronic AD lesions.

Objective  We investigated the expression of an activation marker and a homing receptor, as well as cytokine production, in different peripheral blood T cell subpopulations from AD patients with chronic (Group A) and acute lesions (Group B) and controls.

Methods  We evaluated 26 adult AD patients (12 Group A, 14 Group B) and 14 non‐atopic controls. IgE was measured by immunoassay. CD4, CD8, cutaneous‐lymphocyte‐associated antigen (CLA) and human leucocyte antigen (HLA)‐DR expression, and cytokine production (IL‐2, IL‐13, IFN‐γ, TNF‐α, IL‐10, IL‐4) were analysed in mononuclear cells by flow cytometry.

Results  In Group B there was a significant increase in eosinophil levels and a non‐significant increase in IgE. In Group A we found an increase in CLA⁺CD4⁺ cells (8.19±1.84) compared with controls (4.83±0.53) (P<0.05) and CD4⁺HLA‐DR⁺ cells in the CLA⁺ subpopulation (45.54±15.40) compared with controls (30.49±6.07) (P<0.05). In the CLA⁺CD4⁺ subpopulation, there was a significant increase in IL‐4, IL‐13 and TNF‐α production in Group B (12.46±7.7, 11.26±5.97, 43.92±15.55) compared with controls (5.34±3.50, 4.54±1.78, 19.29±9.97) with no differences in Group A.

Conclusion  Greater immunological differences were detected in peripheral blood from patients with acute compared with chronic lesions, especially in the circulating T cell‐subset with skin tropism that preferentially responded to cutaneous allergens. This is the first demonstration of phenotypic changes in circulating CLA⁺ T cells between AD patients with acute and chronic lesions.

Background Interleukin‐9 is a T cell‐derived Th2‐type cytokine that has been linked to airway hyper‐responsiveness, mucus hypersecretion and mast cell infiltration in animal models. We recently demonstrated the potential for IL‐9 to act in human eosinophil development and survival.

Objectives The aims of this study were: (i) to compare IL‐9 mRNA expression in bronchial biopsies between atopic asthmatics and normal controls, (ii) to investigate kinetic expression of IL‐9 mRNA in skin biopsies after allergen challenge; and (iii) to relate IL‐9 expression to infiltration of eosinophils, mast cell and T lymphocytes in local tissue.

Methods Bronchial biopsies were obtained from atopic asthmatics (n = 12) and normal non‐asthmatics (n = 12) at baseline. Skin biopsies were obtained from atopic subjects (n = 11) at 1, 3, 6, 24, 48 and 72 h after allergen challenge. Diluent challenge sites at 24 h were used as controls. IL‐9 mRNA was identified using the technique of in situ hybridization. The numbers of eosinophils, mast cells and T cells were evaluated by immunohistochemistry.

Results The numbers of IL‐9 mRNA⁺ cells present in the bronchial mucosa were significantly greater in atopic asthmatics than those in normal controls (P = 0.003). The numbers of eosinophils, but not mast cells, were also significantly higher in asthmatics (P < 0.005). The numbers of IL‐9 mRNA⁺ cells present in the airway of asthmatics significantly correlated with the numbers of eosinophils (r = 0.623, P = 0.03), but not mast cells or T cells. Compared with diluent challenge, the numbers of IL‐9 mRNA⁺ cells were significantly elevated at all allergen‐challenged sites in the skin, with maximal signals at 48 h (P < 0.005). At 72 h, the numbers of IL‐9 mRNA⁺ cells significantly correlated with the numbers of eosinophils (r = 0.707, P = 0.015).

Conclusion Elevated expression of IL‐9 in allergic inflammation may contribute to local eosinophil infiltration and survival in asthma and other allergic atopic diseases.

BackgroundNeutrophil apoptosis and phagocytic clearance have been proposed as key determinants affecting the resolution of airway inflammation.

ObjectiveTo determine the kinetics of neutrophil priming, recruitment, activation and subsequent clearance in a naturally occurring equine disease model of neutrophilic pulmonary inflammation.

Methods and ResultsA 5 h mouldy hay/straw challenge in hypersensitive horses induced transient pulmonary dysfunction lasting 4 days. At 24 h circulating neutrophils were primed and displayed delayed rates of spontaneous apoptosisin vitro. Neutrophil numbers in the airspaces peaked at 5 h and then fell abruptly, returning to pre‐challenge levels by 4 days. Airspace neutrophils demonstrated increased respiratory burst activity compared with circulating cells and equine neutrophil elastase 2A concentrations increased in parallel with neutrophil numbers indicatingin vivopriming and degranulation. The number of apoptotic neutrophils and proportion of alveolar macrophages containing phagocytosed apoptotic neutrophils increased significantly at 24 h and 4 days post‐challenge corresponding to the period of most rapid neutrophil clearance.

ConclusionThis is the first demonstration of spontaneous neutrophil apoptosis and phagocytic removal in a natural disease model of airway inflammation and provides critical kinetic data to support the hypothesis that this clearance pathway plays a central role in the resolution of neutrophilic inflammation.

Previous studies have shown that bronchoalveolar lavage fluid from horses with allergic respiratory disease and showing clinical symptoms contains increased numbers of neutrophils. In some cases, the eosinophil count is also increased. In this study the time course of changes in lung function and the accumulation of radiolabelled leucocytes and platelets in the lungs of allergic and normal horses has been examined during a 7 hr allergen exposure. Antigen challenge had no effect on pleural pressure or the distribution of radiolabelled neutrophils, eosinophils or platelets in normal horses. In contrast, in 6/8 allergic horses, there was an increase in pleural pressure and neutrophil accumulation in the lungs, both of which were evident after 4–5 hr. However, during the 7 hr challenge period radiolabelled eosinophils were detected in the lungs of only 1/6 horses exhibiting an increase in pleural pressure and in 1/7 horses that failed to show a change in airway function despite a clinical history of allergic respiratory disease. Antigen challenge did not alter the distribution of radiolabelled platelets in the five allergic horses tested. These results demonstrate that increased pleural pressure is not accompanied by eosinophil or platelet accumulation in the lungs of horses with allergic respiratory disease following exposure to antigen. However, changes in airway function can be associated with neutrophil accumulation but can also take place in the absence of this cell recruitment. This raises the possibility that the presence of neutrophils in the lung is not a prerequisite for changes in lung function.

Background The underlying relationship between viral infections and allergic diseases of the upper respiratory tract has not been well clarified.

Methods In order to clarify the relationship between viral infection and nasal hypersensitivity, mice were sensitized with ovalbumin (OVA) and then infected intranasally with respiratory syncytial virus (RSV), after which their nasal sensitivity to histamine or antigen was examined.

Results Non‐sensitized mice showed transient mild nasal hypersensitivity following nasal administration of histamine after intranasal RSV inoculation. In mice sensitized with OVA, RSV infection significantly exaggerated their nasal hypersensitivity to histamine and OVA. Treatment of these mice with a neurokinin (NK)‐1/NK‐2 receptor antagonist, but not with anti‐IL‐5 antibodies, reduced their hypersensitivity. The infiltration of nasal mucosa with eosinophils was temporarily associated with accelerated rate of RSV elimination in these animals.

Conclusion RSV infection induced transient nasal hypersensitivity. Several mechanisms, including impairment of nasal epithelial cells are thought to mediate this effect. In allergen‐sensitized mice, RSV inoculation strongly enhanced nasal hypersensitivity.

Background: The pollen of canary grass, which was introduced as a pasture grass from Europe, is a major allergen source in the external environment of southern Australia. This study was performed to characterize the major recombinant allergens of canary grass pollen. It is anticipated that recombinant allergens may be useful in diagnosis and immunotherapy of grass pollen induced allergies.

Objective: To clone major canary grass pollen allergens and assess their nucleotide and amino acid sequence homologies with other grass pollen allergens. This sequence information may then be useful in T and B cell epitope mapping studies.

Methods: A canary grass pollen λgtl 1 cDNA expression library was constructed and screened with sera of grass‐pollen‐sensitive patients. IgE‐reactive clones were isolated, sub‐cloned into Escherichia coli, sequenced and, along with the deduced amino acid sequences, compared with other sequences in nucleotide and amino acid databases.

Results: One of the clones encoded the group 1 allergen of canary grass pollen, Pha a 1, with a deduced amino acid sequence identity of 88.8% with Lol p 1, from rye‐grass pollen, 88.1% with Hol 1 1, from velvet grass pollen and 86.6% with Phi p 1, from timothy grass pollen. The other clones (e.g. clones, 5, 14, 28, 29) encoded polymorphic forms of Pha a 5. These polymorphic forms showed between 60.6–95.5% nucleotide and 40.1–81.7% deduced amino acid sequence identities with each other. Moreover, they shared significant sequence identity with other group 5 allergens from rye‐grass, timothy and Kentucky bluegrass pollens.

Conclusions: Group 1 and four isoforms of group 5 allergens of canary grass pollen have been cloned and upon sequencing demonstrated strong nucleotide and amino acid sequence identities with other group 1 and 5 grass pollen allergens.

Pollen from 10 agricultural plant species was surveyed for the presence of proteins crossreactive with group I, group IV and group IX allergens. Barley (Hordeum vulgare), maize (Zea mays), rye (Secale cerale), triticale (xTriticosecale cereale), oats (Avena saliva), Canola (Brassica napus) and sunflower (Helianthus annux) pollens contained numerous allergen cognate proteins. Northern blot analysis of barley pollen RNA revealed the presence of group I and group IX allergen transcripts. The barley pollen cDNA hvp9742, and three other cloned allergens: phlenum protense (Phip) V, Phl p Va and Lolium perenne (Lol p) 1b, were demonstrated to have extensive nucleotide and amino acid sequence similarity to the Poa p IX isoallergens. It was concluded that hvp9742 represents a Poa p IX isoallergen homologue expressed by barley pollen, and was therefore designated Hor v IX. It is further shown that the most highly conserved domains of all seven proteins, including Hor v IX, map to previously defined Poa p IX antibody binding epitopes.