Fig. 5: AZ3451 and AZ8838 are anti-inflammatory in a PAR2 agonist-induced rat paw oedema model.
a PAR2 agonist 2f-LIGRLO-NH2 (2 f, 350 µg/paw, i.pl.) caused peak paw swelling at 30 min. AZ3451 (10 mg kg−1 s.c.) 30 min before, or AZ8838 (10 mg kg−1 p.o.) 2 h before, agonist 2f-LIGRLO-NH2 significantly reduced paw swelling. All subsequent measurements are at 30 min after i. pl. saline (sham) or 2f-LIGRLO-NH2 ( ± antagonist) groups. b Percentage activated/degranulated mast cells in paw induced by 2f-LIGRLO-NH2 was inhibited by AZ3451 or AZ8838 pre-treatment. c Tryptase-positive (AA1+ve) intact mast cells in paw (% cells in sham) were decreased by 2f-LIGRLO-NH2, which was inhibited by AZ3451 or AZ8838 pre-treatment. d Intact mast cells stained dark purple by toluidine blue (black arrowheads) and activated/degranulated mast cells stained light purple (black arrow). e Tryptase-positive mast cells (green) were significantly reduced by 2f-LIGRLO-NH2 vs sham; this was partly blocked by AZ3451 or AZ8838 pre-treatment. Extracellular tryptase undetectable by IHC. f Histamine release (green) was blocked by AZ3451 or AZ8838 pre-treatment. Sham showed intact/inactive histamine-containing mast cells, whereas 2f-LIGRLO-NH2 showed extracellular histamine indicating mast cell degranulation. AZ3451- and AZ8838-treated paws contained inactive mast cells with minimal histamine. g Neutrophil elastase-positive (NE+ve) intact neutrophils (green) in paw. 2f-LIGRLO-NH2 decreased NE+ve cells, which was partially inhibited by AZ3451 or AZ8848 pre-treatment. h % NE+ve cells vs sham in paw at 30 min after 2f-LIGRLO-NH2 or saline. i Myeloperoxidase (MPO) activity, indicating neutrophil activation, was increased by 2f-LIGRLO-NH2 but reduced almost to baseline by pre-treatment with AZ3451 or AZ8838. IHC images: nuclei stained blue with DAPI. Data from two independent experiments shown as mean ± s.e.m., n = 10 for sham and 2f-LIGRLO-NH2 control, n = 5 for AZ8838 and AZ3451 groups. Analysis: Student’s t-test or one-way ANOVA; +p < 0.05, ++p < 0.01, +++p < 0.001, ++++p < 0.0001 compared to sham; *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 compared to 2f-LIGRLO-NH2 control.
