Kappa‐carrageenan sinus rinses reduce inflammation and intracellular Staphylococcus aureus infection in airway epithelial cells

BACKGROUND: Chronic rhinosinusitis (CRS) is a common disease, often refractory to conventional antimicrobial treatment. In this study we investigate the antimicrobial and anti-inflammatory effects of adding kappa-carrageenan to a commercially available sinus rinse. METHODS: Kappa-carrageenan was added to Flo CRS and Flo Sinus Care sinus rinses and applied directly to air-liquid interface cultured primary human nasal epithelial cells (HNECs) from 10 CRS patients. Inflammatory markers were measured using enzyme-linked immunosorbent assay. Kappa-carrageenan-supplemented sinus rinses were applied to human bronchial epithelial cells (HBEs) in the presence of different Staphylococcus aureus strains to observe the effect on intracellular infection rates. RESULTS: Flo Sinus Care with kappa-carrageenan rinse solutions resulted in a marked reduction of interleukin-6 (IL-6) production by HNECs from CRS patients (p = 0.007). Both Flo CRS and Flo Sinus Care rinses significantly reduced the S aureus intracellular infection of HBEs (p < 0.0001). The addition of kappa-carrageenan to both Flo CRS and Flo Sinus Care rinses further reduced the intracellular infection rate by an average of 2%. CONCLUSIONS: The commonly used sinus irrigation product Flo Sinus Care with added kappa-carrageenan reduces IL-6 production by HNECs in vitro. Flo CRS and Flo Sinus Care rinses significantly reduced S aureus intracellular infection rates of HBE cells. Our findings may have clinical relevance for CRS patient management.