iNKT cells are enriched in inflammatory infiltrates of chronic rhinosinusitis with nasal polyposis

iNKT cells, a subset of T cells, are potent effectors of Th2-inflammation that have been associated with a range of allergic diseases, but their involvement in chronic rhinosinusitis with nasal polyposis (CRSwNP) has not been well studied. We investigated their presence and expression of prostaglandin D2 and lipoxin-A4 receptors, Chemoattractant receptor-homologue-Th2 (CRTH2) and formyl-peptide Receptor-2 respectively, in nasal polyp tissue of patients with CRSwNP, as inflammatory regulator, in the presence of commensal bacteria, Staphylococcus aureus. Twenty patients with CRSwNP were recruited for the study. Samples from 8-healthy volunteers were collected as controls. Single-cell suspensions of the nasal polyp tissue and PBMC were stimulated with lipoxin-A4, S. aureus and/or PGD2 and were studied by flow-cytometry. In nasal polyp tissues, iNKT cells represented 16.5±4.5% of lymphocytes, compared to 3.48±2% in circulation (p=0.006) of CRSwNP patients. The proportion of CRTH2+iNKT cells were increased in PBMCs (5.95±2.11%) and nasal polyp tissues (6.16%±1.9) of patients with CRSwNP compared to PBMCs of controls (1.3±1%, p=0.34 & 0.35 respectively). This was accompanied by increased IL-4+iNKT cells (from 7.14±2.26% at basal level to 28.3±4.8%, p=0.005), post-PGD2+S. aureus stimulation. The expression of FPR2+iNKT cells were diminished in the nasal polyp tissues (1.29±0.3%) compared to blood (8.29±3.4%, p=0.05). However, stimulation with lipoxin-A4 significantly recovered FPR2 receptor expression on iNKT cells in PBMC and in the polyp tissue (p=0.002). iNKT cells are a prominent component of the inflammatory cellular infiltrate in nasal polyps in CRSwNP which may get activated by S. aureus+PGD2 and may be refractory to anti-inflammatory effects of lipoxins