Detection of microparticles in nasal lavage fluid that express both integrin β6 and a marker of epithelial-mesenchymal transition (either alpha-smooth muscle actin or Snail) is useful for the identification of severe chronic rhinosinusitis

Abstract

Microparticles (MPs) are one type of extracellular vesicle shed from cell membranes. Integrin β6 (ITGB6) is an epithelial marker that is up-regulated during epithelial repair. Snail is a transcription factor that induces epithelial-mesenchymal transition (EMT) during epithelial repair. Alpha-smooth muscle actin (αSMA) is a mesenchymal marker which is also up-regulated during EMT. We hypothesized that abnormal EMT status is associated with polyp recurrence in chronic rhinosinusitis (CRS) and endeavored to establish MP assays that can detect EMT in nasal lavage fluids (NLFs). Snail, αSMA and ITGB6(+)MPs were measured by flow-cytometry in NLFs collected from 196 CRS with nasal polyp patients (CRSwNP) and 47 control subjects whose age, sex and smoking status were matched to the CRSwNP group. Levels of Snail(+)ITGB6(+)MPs (1.6-fold, p<0.0001) and αSMA(+)ITGB6(+)MPs (2.0-fold, p<0.0001) were increased in CRSwNP compared with control. Among CRSwNP subjects, levels of Snail(+)ITGB6(+)MPs (1.7-fold, p<0.0001) and αSMA(+)ITGB6(+)MPs (2.0-fold, p<0.0001) were higher in those with a history of previous polypectomy than in those without, independent of age, atopy, asthma or steroid use. Area under the curve (AUC) analyses showed that levels of αSMA(+)ITGB6(+)MPs (AUC:0.78 [95%CI:0.71-0.84], sensitivity 81%, specificity 61%) and Snail(+)ITGB6(+)MPs (AUC:0.77 [0.69-0.84], sensitivity 58%, specificity 66%) have potential utility to detect EMT and assess the degree of disease severity in CRS patients. Elevated EMT, with up-regulation of ITGB6 on MPs along with EMT markers Snail or αSMA, is associated with severe polyp recurrences which necessitated revision polypectomy. Snail or αSMA(+)ITGB6(+)MPs are potential biomarkers to detect severe CRS patients at high risk for revision polypectomy.