The Association of TSLP and IL-4 with Patient-Reported Outcome Measures in Chronic Rhinosinusitis with Nasal Polyps

BACKGROUND: Thymic stromal lymphopoietin (TSLP) plays an important role in mediating the type-2-inflammatory response. This study examined how TSLP and interleukin (IL)-4 levels in patients with chronic rhinosinusitis with nasal polyps (CRSwNP) correlated with clinical and postoperative outcomes. METHODS: Solid-phase sandwich ELISA was used to analyze TSLP and IL-4 levels in mucus (n = 47), plasma (n = 17), polyp (n = 30), inferior (n = 25), and middle (n = 26) turbinate tissue collected during functional endoscopic sinus surgery (FESS) in CRSwNP patients (n = 76) and controls (n = 11). Inclusion criteria includes patients with medical treatment refractory CRSwNP confirmed by endoscopy or maxillofacial CT. Exclusion criteria include history of immunodeficiency, coagulation disorders, fungal sinusitis, or cystic fibrosis. Levels of TSLP and IL-4 were correlated with SNOT-22, UPSIT, and fractional exhaled nitric oxide (FeNO) using MannWhitney U two-tailed test and linear regression with Spearman correlation coefficient test. RESULTS: TSLP is elevated in the inferior turbinates (effect size = 2.695, p = 0.0007) of CRSwNP patients compared to controls. IL-4 is expressed at elevated levels in the inferior (effect size = 3.092, p < 0.0001) and middle turbinates (effect size = 2.041, p = 0.019) compared to controls. Mucus TSLP (r = 0.4013, p = 0.0153) and IL-4 (r = 0.6138, p < 0.0001) positively correlate with preoperative FeNO levels. Lower TSLP in the inferior (r = -0.5179, p = 0.0231) and middle turbinates (r = -0.5075, p = 0.0224) and lower IL-4 in the inferior turbinates (r = -0.5205, p = 0.0223) correlate with a greater improvement in SNOT-22 post-FESS. CONCLUSION: TSLP and IL-4 are elevated in patients with CRSwNP and correlated with increased preoperative FeNO levels and decreased sinonasal quality of life benefit after FESS. Expression of TSLP and IL-4 may play a role in guiding postoperative expectations in patients with treatment refractory CRSwNP.