The major cockroach allergen Bla g 4 binds tyramine and octopamine.

Bla g 4 is a male cockroach specific protein and is one of the major allergens produced by Blattella germanica (German cockroach). This protein belongs to the lipocalin family that comprises a set of proteins that characteristically bind small hydrophobic molecules and play a role in a number of processes such as: retinoid and pheromone transport, prostaglandin synthesis and mammalian immune response. Using NMR and isothermal titration calorimetry we demonstrated that Bla g 4 binds tyramine and octopamine in solution. In addition, crystal structure analysis of the complex revealed details of tyramine binding. As tyramine and octopamine play important roles in invertebrates, and are counterparts to vertebrate adrenergic transmitters, we speculate that these molecules are physiological ligands for Bla g 4. The nature of binding these ligands to Bla g 4 sheds light on the possible biological function of the protein. In addition, we performed a large-scale analysis of Bla g 4 and Per a 4 (an allergen from American cockroach) homologs to get insights into the function of these proteins. This analysis together with a structural comparison of Blag 4 and Per a 4 suggests that these proteins may play different roles and most likely bind different ligands. Accession numbers: The atomic coordinates and the structure factors have been deposited to the Protein Data Band under accession codes: 4N7C for native Bla g 4 and 4N7D for the Se-Met Bla g 4 structure.

A mysterious case of gastroparesis: could the secret be found in a drink?

BACKGROUND: Gastroparesis is a disorder characterized by delayed gastric emptying of a meal in the absence of a mechanical gastric outlet obstruction. Idiopathic gastroparesis is at least as common as diabetic gastroparesis in most case series, and the true prevalence of gastroparesis is unknown. RESULTS: We report here an interesting case of idiopathic gastroparesis characterized by sudden onset in a female patient. The diagnosis was confirmed by ultrasonographic study of gastric emptying and electrogastrography, by gastric endoscopy/histology, and finally by allergy tests. The disorder was found to be due to a rare cause, namely an allergic predisposition. In fact, our patient, who demonstrated an allergy to gold salts, had drunk a glass of a liqueur containing gold flakes and developed an eosinophilic aggregation in the gastric mucosa observed at gastric endoscopy/histology. The symptoms disappeared after steroid administration. CONCLUSION: Our experience suggests that gastric histology and close enquiry into any history of allergy may be useful diagnostic tools in cases of idiopathic gastroparesis.

Streamer discharge reduces pollen-induced inflammatory responses and injury in human airway epithelial cells.

Although epidemiological studies have demonstrated that cedar pollen influences respiratory health, effective method for inactivating cedar pollen has not been established. Streamer discharge is a type of plasma discharge in which high-speed electrons collide with oxygen and nitrogen molecules. It reportedly has the ability to eliminate bacteria, mould, chemical substances and allergens. The present study investigated the influence of pollen on BEAS-2B cell line, derived from human airway epithelial cells, as well as the efficiency of streamer discharge on pollen-induced health effects. Airway epithelial cells were exposed to non-treated pollen and streamer-discharged pollen at doses of 100 and 1000 µg/mL for 6 or 24 h. Non-treated pollen at a dose of 1000 µg/mL significantly decreased cell viability and induced both mRNA and protein expression of interleukin-6, whereas streamer-discharged pollen showed the attenuated changes as compared with non-treated pollen. Further, scanning electron micrographs showed that streamer discharge caused the fine structural changes of pollen. These results provide the first experimental evidence that pollen at a high dose affects cell viability and inflammatory responses, and streamer discharge technology attenuates their influences by decomposing pollen.

Three-dimensional structure and IgE-binding properties of mature fully active Der p 1, a clinically relevant major allergen.

BACKGROUND: Der p 1 is a 25-kd allergen with cysteine protease activity. Sensitization to Der p 1 affects a large proportion of individuals with allergy, resulting in rhinitis, asthma, and/or atopic dermatitis. OBJECTIVE: We determined the Der p 1 crystallographic structure to understand the relationships among structure, function, and allergenicity. METHODS: Recombinant pro-Der p 1 was produced in Pichia pastoris and allowed to mature spontaneously before purification by a 2-step procedure. Protease activity was checked by using a fluorogenic peptide substrate. Allergenicity was analysed by IgE binding assays and basophil activation test. The determination of the 3-dimensional structure was obtained by X-ray crystallography at 1.9 A resolution. RESULTS: The recombinant protein is fully active and expresses an allergenicity equivalent to its natural counterpart. Der p 1 exhibits a cysteine protease fold typical of the papain family, has a magnesium binding site, and forms dimers with a large interface. The crystal lattice shows that the dimers are tightly packed in a compact double layer of proteins. Such an assembly likely exists in dry fecal pellets, the natural form of allergen exposure, and appears ideal to interact with cell surface and trigger allergic inflammation. CONCLUSION: We present here the 3-dimensional structural features of mature fully active Der p 1, one of the main allergens involved in human allergic diseases. This opens the possibility to evaluate the importance of enzymatic activity in pathology and possible new therapeutic interventions.

Measurement and characterization of cockroach allergens detected during normal domestic activity.

BACKGROUND: Cockroach allergen is recognized as a causal factor for asthma. However, airborne cockroach allergen has not been detected in undisturbed conditions, and therefore the behavior and properties of airborne cockroach allergen have been poorly characterized. A new aeroallergen sampling method and sensitive system of immunoassay have been used to examine cockroach allergen exposure. OBJECTIVE: Our purpose was to measure and characterize airborne cockroach allergens during normal domestic exposure in the homes of Sydney, Australia. METHODS: Air sampling with Institute of Occupational Medicine, Edinburgh (IOM) samplers was performed in the living rooms of 10 houses during low- and no-disturbance environments. In addition, inhaled particles were collected by each home occupant during low domestic exposure with use of intra-nasal samplers that impact particles onto an adhesive surface. The particles collected on the IOMs and the intra-nasal samplers were immunostained with Bla g 1 monoclonal antibodies. Particle size, morphologic characteristics, and the relative Bla g 1 content of particles were estimated. Reservoir dust samples from the kitchen, living room, and bedroom were assayed by an ELISA. Two forms of repeatability of IOM air sampling were examined. The first measure tested the repeatability of 2 IOM samples collected simultaneously in the same room during low- and no-disturbance activities. The second measure examined the repeatability of IOM sampling over time on 10 consecutive days. RESULTS: Bla g 1 was detected in reservoir dust samples taken from all homes (geometric mean 1.5 U/g, range 0.2-9.4 U/g). Inhaled particles containing Bla g 1 were detected during 1 hour of intra-nasal sampling in 8 of 10 homes during low disturbance. Cockroach particles were detected on all of the IOM samples collected for both 4-hour low-disturbance and overnight no-disturbance sampling environments. Particles containing Bla g 1 collected with the IOM samplers during low disturbance ranged in size from 3 to 350 microm. These particles are amorphous and irregular in shape, and a majority of the large particles were described as flakes (flat, transparent particles) and fibers (threadlike). A relationship was demonstrated between the allergen content of cockroach particles and their particle size. The larger particles elute more Bla g 1. The coefficient of repeatability for measurements made during low and no disturbance was 3.62 and 2.09, respectively. For measurements repeated over time at the same site, the coefficient of repeatability was 2.61. This represents the fold range within which 95% of pairs of measurements made at an interval of 1 day would be expected to lie. CONCLUSIONS: Airborne cockroach allergen is present in both undisturbed and low-disturbance environments in homes with relatively low reservoir levels of Bla g 1. In agreement with previous reports, airborne particles containing cockroach allergen (Bla g 1) are mainly associated with particles >10 microm. These particles are amorphous and irregular in shape and can be described as flakes and fibers.

Asma alérgica: aspectos genéticos y ambientales

El asma es una enfermedad multifactorial y clínicamente heterogénea. La variedad alérgica es inducida principalmente por los ácaros del polvo casero, en personas genéticamente susceptibles. Las condiciones genéticas apropiadas para desarrollar este tipo de alergia, parecen estar determinadas por el Complejo Mayor de Histocompatibilidad del Humano (CMH), mediante el control de la respuesta Inmunoglobulina E (IgE) contra alergenos de ácaros. El control ambiental se considera como esencial en el manejo de los problemas alérgicos, incluyendo el asma. En los últimos años se han registrado importantes adelantos respectoa los componentes ambientales y genéticos del Asma Alérgica (AA). En esta revisión se analizan los avancesen este campo de la investigación clínica y básica, que posiblemente ayudarán a obtener un manejo más apropiado de estas enfermedades