Fig. 7

Comparative effects of SLIGRL-amide and ATP on promoting mucin release and inhibiting IAV infectivity in mouse isolated tracheal segments. a Effect of SLIGRL-amide and the purinoceptor agonist ATP on levels of AB-PAS (left-hand panels) and IAV (right-hand panels) staining in sections of mouse trachea. In AB-PAS experiments, mouse isolated tracheal segments were mounted onto the explant perfusion system and pre-perfused for 24 h, and then incubated for 15 min with saline, SLIGRL-amide or ATP. Segments were fixed, paraffin-embedded, sectioned and stained with AB-PAS. In IAV immunohistochemical staining experiments, tracheal segments were mounted onto the explant perfusion system and incubated for 15 min with IAV in the presence of absence of saline, SLIGRL-amide or ATP. After two days of perfusion with media, segments were fixed, paraffin-embedded, sectioned and immunostained for IAV. Shown are representative images from at least 3 experiments. Bar = 50 μm. b Residual levels of AB-PAS staining, expressed as %SPP (strong positive pixels), within the epithelium of mouse isolated tracheal segments following a 15 min exposure to saline (control, white fill) or selected compounds (black fill) (n = 4-8 tracheal segments per group). Luminal exposure to SLIGRL-amide, BAM8-22 and ATP, but not CGRP or substance P (SubP), stimulated a reduction in epithelial AB-PAS staining, consistent with mucin secretion. *, P <0.05, compared to vehicle (one-way ANOVA, Dunnett’s posthoc test)