The effect of macrolides on allergic rhinitis versus chronic rhinosinusitis- an in-vitro study

Abstract

Background The mechanisms of the rhinitic process are complex. Previous studies upon nasal epithelial cells have begun to investigate rhinitis. HNECs from turbinate explant tissue were taken from three patient groups (Normals, Chronic Rhinosinusitics and Rhinitics). Aims The study, firstly, aims to establish fundamental differences in cytokine activity between allergic rhinitis and chronic rhinosinusitis by analysing baseline levels of cytokines IL-6 and IL-8 and subsequent impact of bacterial endotoxin. Secondly the study analyses the affect of macrolides on activity in each subgroup. Methods HNECs were grown from the biopsy specimens as explant culture. Standardised exposures to LPS bacterial endotoxin and macrolide were carried out. The concentration of each mediator present in the medium at the end of incubation was assessed by ELISA). A final quantity of total cellular protein was obtained. 3 Results Baseline levels of IL-6 in unstimulated Allergic Rhinitics are significantly higher than in Normal patients. Baseline levels of IL-8, however, are lowest in Allergics. LPS significantly stimulates Allergics to increase production of both IL-6 and IL-8. Macrolides lower IL-6 and IL-8 in both stimulated and unstimulated AR cells. Baseline levels of IL-6 and IL-8 are higher in CRS than AR and Normals. LPS significantly raises IL-6 and IL-8 in CRS. Macrolides increase IL-6 and IL-8 in stimulated CRS cells however reduce levels of both in un-stimulated cells. Discussion Pre-existing neutrophilic and eosinophilic activity in CRS subjects may explain the increased baseline levels of both cytokines upon macrolide exposure. Whilst some studies have suggested macrolides act as antimicrobial, others have suggested that it is their anti-inflammatory effects that are more relevant. Treatment for Allergic Rhinitis needs to be effective long-term. The results here are novel and encourage further research to improve understanding of the effects of macrolides in a potentially pivotal role.