Expression of the protein serum amyloid A in response to Aspergillus fumigatus in murine models of allergic airway inflammation

Background: Serum amyloid A (SAA) is an acute phase protein that is elevated in blood during inflammation. The role of this protein in allergic diseases of airways remains unclear. Aims: The objective of this study was to evaluate the SAA in blood, lung and bronchial cells in a murine model of bronchial hypersensitivity to Aspergillus fumigatus. Methods: To achieve this purpose, different groups of 5-month-old mice were housed in cages containing hay bedding that was contaminated with A. fumigatus and were kept in an isolation room for 16 days to allow for the induction of allergic airway inflammation. Subsequently, the mice were then exposed once again to Aspergillus spores at 0, 2, 8, 24 and 72 h, and they were bled to acquire serum and sacrificed to obtain bronchoalveolar lavage fluid (BALF) or lung tissues for analysis. SAA levels were measured in lung, serum and BALF by dot blot assay and RT-PCR (reverse transcription polymerase chain reaction). Results: The results indicated that SAA protein levels increased in both serum and lung within 2-24 h after mice were exposed to Aspergillus spores. Moreover, the SAA mRNA expression levels in the lungs and BALF cells demonstrated the same trend that was observed for the protein levels through the dot blot assay; in particular, SAA mRNA levels increased within the first hour after mice were exposed to A. fumigatus. Conclusions: In this allergic airway model, we conclude that A. fumigatus can induce an acute inflammatory response in the airways through the stimulation of the SAA protein, increasing its levels in serum, lung tissue and BALF samples during the early hours of exposure of mice that have been sensitised for this fungus. Resumen Antecedentes La proteina amiloide A serica (AAS) es un reactante de fase aguda cuyos valores sanguineos aumentan durante los procesos inflamatorios agudos. Todavia no se ha dilucidado el papel que desempena en las enfermedades alergicas de las vias respiratorias. Objetivos El objetivo del presente estudio fue examinar los valores de AAS en sangre, tejido pulmonar y celulas bronquiales en un modelo murino de hipersensibilidad bronquial frente a Aspergillus fumigatus. Metodos Diferentes grupos de ratones de 5 meses de vida fueron alojados en jaulas cuyos lechos de paja estaban contaminados por A. fumigatus y se mantuvieron en una sala de aislamiento durante 16 dias para permitir la induccion de inflamacion alergica de las vias respiratorias. Tras este periodo de induccion, a la