Selective gelatinase blockage ameliorates acute DSS colitis

Abstract

In the experimental models of intestinal inflammation and humans with inflammatory bowel diseases (IBD), increased levels of the matrix metalloproteinases (MMPs), MMP-2 and -9 (also referred to as gelatinase A and B, respectively), in inflamed tissue sites can be detected. In the presented study, we investigated potential beneficial effects exerted by doxycycline nonselectively blocking MMPs and the selective gelatinase inhibitor RO28-2653 in acute DSS colitis. Treatment with either compound for 8 days ameliorated clinical colitis pathology with a superior outcome in RO28-2653-treated animals. As compared to placebo controls, histopathological changes in the colon were less distinct following MMP blockage and IL-6 secretion in ex vivo biopsies was downregulated, paralleled by a diminished influx of pro-inflammatory immune cells and lack of overgrowth of the colonic lumen by potentially pro-inflammatory Escherichia coli of the commensal colon flora. We conclude that selective gelatinase inhibition not only exerts beneficial effects by disrupting the vicious cycle of positive feedback between immune cell stimulation and MMP induction but also prevents overgrowth of the colonic lumen by pro-inflammatory E. coli despite a lack of direct anti-bacterial properties, thus unaffecting the commensal gut microbiota. These findings put RO28-2653 into a center stage for development of intervention strategies in human IBD.

The distinct roles of MMP-2 and MMP-9 in acute DSS colitis

“…Mice were monitored daily for occult blood in stool (as determined by the guajak method using Haemoccult™, Beckman Coulter/PCD, Krefeld, Germany), stool consistence and body weight. Total clinical scores with a maximum of 12 were calculated by combined scores of weight loss, occurence of blood in stool, and stool consistence, as described previously [18][19][20].…”

“…In situ immunohistochemical analysis of colon paraffin sections was performed as described previously [18,21,22]. Primary antibodies against CD3 (#N1580, Dako, Denmark, dilution 1:10), FOXP-3 (FJK-16s, eBioscience, 1:100), B220 (eBioscience, San Diego, CA, USA, 1:200), myeloperoxidase-7 (MPO-7, # A0398, Dako, 1:10000), and F4/80 (#14-4801, clone BM8, eBioscience, 1:50) were used.…”

“…After 18 h at 37°C, culture supernatants were tested for IL-6 by enzyme-linked immunosorbent assay (ELISA) (BD Biosciences, Heidelberg, Germany) as described previously [18,20,23,24].…”

“…Given that synthetic selective gelatinase blockage was shown effective in preventing acute small intestinal as well as colonic inflammation [17,18], we were interested which gelatinase in particular (A, B, or both) was predominantly involved in mediating acute DSS colitis. In order to address this question, MMP-2-and MMP-9-deficient mice were subjected to acute colitis induced by DSS treatment for 7 days.…”

“…Furthermore, MMP-2-, but not MMP-9-deficient mice were protected from ileitis development [17]. In addition, acute dextrane sulfate sodium (DSS) colitis was ameliorated by preventive use of RO28-2653 [18]. Thus, we were interested whether gelatinase A, B, or both are essential in mediating acute colonic inflammation.…”