Inflammatory immune response in rabbits with Staphylococcus aureus biofilm-associated sinusitis.

BACKGROUND: Staphylococcus aureus is the most commonly isolated bacterium from patients with surgically recalcitrant chronic rhinosinusitis (CRS). Understanding the immune responses to S aureus biofilms will provide insights into how the host response may be manipulated by therapeutic agents to improve the chances of successfully preventing and treating these infections. In this study, we investigated the inflammatory immune response in a rabbit model of S aureus biofilm-related sinusitis by analyzing the levels of some major inflammatory cytokines.

METHODS: Eighteen New Zealand white rabbits were randomly divided into 3 groups: a blank-control group; a negative-control group; and a model group. Four weeks after the biofilm-associated sinusitis models were established, the sinus mucosa was harvested and examined using hematoxylin-eosin (H&E) staining, scanning electron microscopy (SEM), reverse transcription polymerase chain reaction (RT-PCR), and western blotting. The expression levels of inflammatory cytokines were analyzed statistically.

RESULTS: Interleukin (IL)-1β, IL-8, and tumor necrosis factor (TNF)-α expression levels were significantly higher in the model group than in the blank-control group (p < 0.05); mRNA levels were increased by 1600%, 230%, and 130%, respectively, and the protein levels were increased by 180%, 100%, and 100%, respectively. In contrast, IL-4 and IL-5 mRNA levels were reduced by 44% and 70%, respectively, compared with the blank-control group (p < 0.05).

CONCLUSION: S aureus biofilms in the rabbit maxillary sinus mucosa were associated with increased IL-1β, IL-8, and TNF-α expression, and decreased IL-4 and IL-5 expression.