INHIBITION OF MATRIX METALLOPROTEINASE 9 WITH DOXYCYCLINE REDUCES NEUTROPHIL MIGRATION IN PANCREATITIS-ASSOCIATED LUNG INJURY

Abstract

Background: In pancreatitis-associated lung injury (PALI), matrix metalloproteinase 9 (MMP-9) promotes neutrophil (PMN) migration through endothelial basement membrane into the lung. We hypothesize that inhibition of MMP-9 with doxycycline, a potent MMP-9 inhibitor, may reduce lung injury following experimental acute pancreatitis (AP). Methods: In vivo: 18 rats were randomized into three groups: (1) AP without treatment, (2) AP with doxycycline (30mg/kg s.c.) and (3) control. AP was induced by retrograde infusion of glycodeoxycholic acid (GDOC) into the pancreatic duct. Subcutaneous administration of doxycycline followed directly after AP induction and after 3 and 6 hours serum was evaluated for doxycycline level with HPLC (2μg/ml). After 9 hours rats were killed and lungs were investigated histologically. Staining was performed with NACE for pulmonary PMN and histological lung injury. In vitro: We tested the inhibitory effect of doxycycline on PMN transmigration across matrigel invasion chambers. In group (1) no doxcycline was added to the PMN suspension, group (2) contained doxycycline (2μg/ml). Transmigrated PMN on the lower surface of the mebrane were stained and counted. Results: Average doxycycline serum level after subcutaneous application was 2μg/ml after 3 hours and did not change after 6 hours. Doxycycline in the evaluated concentration significantly reduced TNF-α induced PMN transmigration across matrigel membrane in vitro (12.6+/−2.6 vs. 20.1+/−3.9; p<0.05). After induction of severe acute pancreatitis doxycycline decreased the number of pulmonary PMN compared to the group without treatment (21.2+/−5.1 vs. 32.5+/−6.8; P < 0,05), control group (14.2+/−4.0). Conclusion: Inhibition of MMP-9 with doxycycline reduces inflammation induced PMN transmigration across matrigel membrane in vitro and also PMN migration into the lung following experimental acute pancreatitis in vivo and might prove an effective treatment or prophylaxis against PALI.