Acute induction of apoptosis impairs inflammatory responses without the requirement for engulfment by macrophages.

(a) Ventral projections of embryos containing hs-hid (w;CyO hs-hid/+) stained for active caspases (anti-cDCP-1) following heat-shock for 0, 15, or 30 minutes; embryos fixed and stained at indicated times. (b) Schematic showing experimental design to induce exogenous apoptosis ahead of clearance by phagocytes in the embryo. (c) Scatterplot showing vacuoles per macrophage, per embryo as a read out of phagocytosis at 60 minutes post heat shock (immediately before wounding) in control and hs-hid embryos (n = 12 and 14, respectively; P = 0.829, Mann–Whitney test). (d) Prewound and 60-minute postwound ventral views of control (w;srp-GAL4,UAS-GFP/CyO) and hs-hid embryos (w;srp-GAL4,UAS-GFP/CyO hs-hid) subjected to 15-minute heat-shock; experimental design was as per (b), with wounding taking place at 60 minutes post heat shock. Dotted lines show wound edges. (e) Scatterplot of wound responses (density of macrophages at wound sites normalised to wound area and to control average) at 60 minutes post wounding of control and hs-hid embryos (n = 9 and 11, respectively; P = 0.0005, Mann–Whitney test). Line and error bars show mean and standard deviation in all scatterplots; ns and *** denote not significant and P S1 Data. cDCP-1, cleaved death caspase 1; GFP, green fluorescent protein; UAS, upstream activating sequence.