MMP activity and PGP generation mediate the effects of DDR2 on neutrophil chemotaxis. (A) MMP and DDR2 inhibition affect neutrophil directionality in 3D collagen matrix. Human primary neutrophils were embedded in collagen I (pretreated with or without rDDR). Migration of neutrophils to 50nM IL-8 was recorded as described in Figure 3A. Results are representative of 5 independent experiments. *P < .05, Friedman test; Dunn posthoc test. (B) Neutrophil directionality in a collagen matrix is reduced upon DDR2 or MMP inhibition. The images show paths of individual cells migrating in a 3D collagen I matrix to IL-8 in the presence of the different inhibitors. Data are representative of 5 independent experiments. Also see supplemental Videos 2-4. (C) DDR2- and MMP-dependent migration is dependent on PGP production. Human primary neutrophils were pretreated for 30 minutes with 350 μg/mL RTR, 25μM GM6001, or 100μM Z-PP-CHO. The number of neutrophils migrating to 1μM LTB4 (in the presence of the inhibitors) through collagen I–coated Transwells was determined after 6 hours. Results represent the relative percentage of migrating cells after treatment (average ± SEM) of 4 independent experiments. *P < .05, Friedman test; Dunn posthoc test.
