Immunolocalization of NLRP3 Inflammasome in Normal Murine Airway Epithelium and Changes following Induction of Ovalbumin-Induced Airway Inflammation

Figure 4

Translocation and luminal shedding of the IL-1 cytokines and inflammasome proteins in inflamed airway epithelium. (a–f) Serial sections of a control mouse lung (a-b) and those of an OVA-treated mouse (c–f) were stained for the cytokines and total caspase-1 in red (Cy3), and counterstained for nuclei with DAPI (blue). In the control mouse lung epithelium, IL-1β (a), IL-18 (b), and total caspase-1 (not shown) typically gave an homogenous cytoplasmic fluorescence (insets). In staining of multiple sections from the lung of OVA-treated mice, punctate fluorescence of both cytokines was consistently detected near the apical surface (c-d, insets). Together with caspase-1, these cytokines were detected in the lumen (c, d, e, arrowheads). (f) Control section incubated with the secondary antibody alone. Fluorescence images are representative of similar results from 3 experiments on 8 control and 8 OVA-treated mice. The scale bars are in microns. (g–i) Fluorescently labelled sections of inflamed lungs (g, i, k) were restained with H&E (h, j, l) to identify luminal structures containing inflammasome components and cytokines. Although some fluorescence was localized to infiltrating eosinophils (arrowheads) or cell-free debris (short arrows), most of the luminal shed material appeared to be within well-preserved eosinophilic vesicles (~6–10 microns) near the airway epithelial apex (inset long arrows). H&E images are representative of results from experiments carried out on multiple sections of 4 OVA-treated mouse lung. The scale bars are in microns.