Contribution to the regulation of intestinal matrix metalloProteinase expression by tumor necrosis factor alpha in inflammatory bowel disease

Abstract

Activated immuno-cumpetent cells in the intestinal mueosa of patients with Inflammatory Bowel Disease (IBD) secrete mediators which might evoke the expression of tissue degrading Matrix MetalloProteinases (MMP). We studied the contribution of TNF-a to expression of housekeeping MMP-2 and inflammation related MMP-9 in cultured ileum/colon from Crohn's disease (CD) and ulcerative colitis (UC) patients versus macroscopically normal colon from colorectal carcinoma (CRC) controls. From surgically resected intestine, mucusa/submucosa were cut into 0.1 cm 2 explants. Series of 10 explants were cultured in 3.5 ml modified CMRL-1066, with or without PokeWeedMitogen (PWM) immunnstimulation and anti-TNFor-antibody infliximab, in 95% 02/5% CO 2 atmosphere at 37 ~ for 72 hours. Conditioned media were analysed for protein by ELISA and mRNA in tissue homogenates was quantitated by RT-PCR. Explants from 1BD patients cultured in CMRL expressed significantly more MMP-2 protein than CRC controls (mean 21.8 vs 13.5 ng/mg tissue weight, P<~0.05) and much more MMP-9 (3.2 vs 1.0 ng/mg, P<0.01), while median MMP-2 and MMP-9 transcript levels were 2and 5-fold increased, respectively. Remarkably, only in CD explants part of MMP-9 expression was TNF-a dependent (1.7 vs 2.7 ng/mg, with and without infliximab, respectively, P~0.08), while expression of MMP-2 was independent from TNF--a in all tissues. Whereas TNF-a protein and mRNA levels were increased dramatically (18-fold nae in mean and 36-fold median induction, respectively), stimulation with PWM decreased MMP-2 protein (P<0.01) and only margmafly increased MMP-9 protein in IBD and controls, independent from TNF-a neutralization by infliximab. In contrast, MMP-2 and MMP-9 mRNA levels showed 1.4and 6-fold median induction, regardless of tissue type. These results indicate a major involvement of MMP-2 and -9 in [BD pathogenesis, TNF-a mediated constitutive regulation of MMP-9 only in CD, and the existence of intestinal PWM-sensitive MMP regulatory mechanisms largely independent from TNF-ct.