Gram-negative
sepsis,
bacterial meningitis and
endotoxin shock are life-threatening disorders, associated with the rapid release of neutrophil
enzymes.
Neutrophil collagenase/
matrix metalloproteinase-8 (MMP-8) and
gelatinase B/
matrix metalloproteinase-9 (MMP-9) are contained in granules, are quickly exocytosed upon granulocyte activation and efficiently cleave intact and denatured
collagens, respectively. Genetic ablation of
gelatinase B protects against
endotoxin-induced mortality. Therefore, we designed and synthesized a
peptidomimetic gelatinase B inhibitor
Regasepin1, and compared the selectivity for the
collagenases MMP-1, MMP-8 and MMP-13.
Regasepin1 was found to inhibit, almost to the same degree, the neutrophil
enzymes MMP-8 and MMP-9 and the monocytic
tumor necrosis factor-alpha (
TNF-alpha) converting enzyme (TACE/ADAM-17) in vitro. With the use of mass spectrometry analysis, the plasma half-life of inhibitor levels was determined after an intraperitoneal bolus injection in mice. Plasma peak levels of the inhibitor were reached at 50 min after
intraperitoneal injection and the subsequent half-life in the circulation exceeded 40 min.
Regasepin1 protected mice against lethal endotoxinemia by intraperitoneal and
intravenous injection routes. This proves the principle that early neutrophil
MMP inhibition followed by TACE blockade may become a treatment strategy of gram-negative
sepsis, endotoxinemia and other life-threatening inflammatory reactions.