Evidence for mast cells activation in the lung of propionic acid-induced autism-like rat model (histological and immunohistochemical study)

Abstract

Introduction: Autism spectrum disorder (ASD) is a global health problem. Growing evidence suggests that high prevalence rates of different allergic conditions are associated with autism.Aim of the Work: As mast cells are the main cells included in the pathophysiology of allergic reactions and anaphylaxis, therefore, this study aimed to find scientific evidence for the association between propionic acid-induced ASD and mast cell activation in the lung.Materials and Methods: Twenty rats (Two weeks-old) were randomly divided into two equal groups ten rats each; control group: rats were given SC injection of phosphate buffer saline (1ml) for five successive days and Propionic acid (PPA) treated group: rats were given (500 mg/kg/ day) SC for five successive days. By the end of two-months-old lungs were dissected and examined by histological and immunohistochemical methods.Results: A significant increase in mast cell density, intact mast cells and degranulated cells were observed in PPA treated group compared with the control group. Thickened interalveolar septum with inflammatory cellular infiltration and congested blood vessels were observed. Most of mast cells were degranulated. Mast cells were found within the smooth muscle layers of respiratory bronchioles. A statistically significant increase in area percent of collagen was detected in PPA treated group in comparison to the control group. A significant increase in area percentage of IL-6 was also detected in PPA treated group in comparison to the control group.Conclusion: The results are indicative that an increase in mast cell density was detected in PPA treated group. It was associated with lung fibrosis and increased area percentage of IL-6.