The following is a summary of “Chronic rhinosinusitis patients display an aberrant immune cell localization with enhanced S aureus biofilm metabolic activity and biomass,” published in the MARCH 2023 issue of Allergy & Immunology by Shaghayegh, et al.

Chronic rhinosinusitis (CRS) is characterized by persistent sinus mucosa inflammation and impairment of the sinuses’ natural defense mechanism. Severe recalcitrant CRS is a condition that is unresponsive to medical and surgical treatments and often features Staphylococcus aureus-dominant mucosal biofilms. For a study, researchers sought to examine the properties of S aureus biofilms grown in vitro regarding inflammation and CRS severity and the spatial pattern of inflammatory cells in patients’ sinonasal tissue. In addition, they sought to investigate the characteristics of in vitro-grown S aureus biofilms about inflammation and CRS severity. They also examined the spatial distribution of inflammatory cells in the sinonasal tissue of patients with CRS.

S aureus isolated from nasal swabs of CRS with nasal polyps (CRSwNP), CRS without nasal polyps (CRSnP), and controls (n = 72) were grown into biofilm in vitro, and their metabolic activity, biomass, colony-forming units, and exoprotein synthesis were measured. Using whole-genome sequencing, the virulence genes of S. aureus were assessed. The Lund-Mackay computed tomography score was used to assess the severity of the patient’s disease by analyzing their matched sinonasal tissue blocks (n = 57). Investigations were made on the relationships between the characteristics of S. aureus biofilm, the number and distribution of specific immune cells in the corresponding sinonasal mucosa, and the severity of the illness.

Increased infiltration of CD3+, CD68+, CD20+, and CD138+ cells was observed in patients with CRSwNP compared to tissue from controls. CD3+, CD138+, and MBP+ cells diffused deeper into the tissue in CRSwNP but clustered close to the epithelium in controls. The study also found that S aureus biofilms derived from CRSwNP showed thicker biomass, higher colony-forming units, and higher exoprotein production than controls (P < .05). In addition, S aureus biofilm properties, inflammatory cell numbers, and CRS severity scores were positively correlated.

The study concluded that S aureus biofilms played a crucial role in CRS etiopathogenesis and that the aberrant immunolocalization of key immune cells in CRSwNP may contribute to disease severity.