Figure 7.

SLPI as an element of the interconnected protease network, bridging MMPs and serine proteases in inflammation. Infiltrating neutrophils carry a battery of proteolytic or bactericidal proteins ready for release upon an inflammatory insult. Besides local mucosal SLPI production, SLPI is also found in the secondary granules of neutrophils (yellow). MMP-9 and MMP-8 are stored in tertiary or specific granules (green) and the serine proteases cathepsin G (CatG), proteinase 3 (P3), and NE in primary granules (blue). Depending on the magnitude of the inflammatory stimulus, tertiary granules are released first, followed by secondary granules and primary granules. This overview shows the interconnectivity between proteases and protease inhibitors released from these vesicles and present in the local tissues (orange). Arrows indicate a positive/stimulatory effect, while solid lines with blunt ends correspond to inhibitory reactions. Line thickness is relative to the efficiency of the inhibitory/stimulatory effect. Red arrows indicate newly described links within this manuscript.