Transfer colitis in Rag1-/-- mice enhances hepatic MMP–9 expression

Introduction: Naive T-cell reconstitution into Rag 1-/- mice induces transfer colitis1. Earlier studies showed that 5% of patients with ulcerative colitis are prone to develop primary sclerosing cholangitis resulting in hepatic fibrosis and vice versa2. Based on these studies we characterized the effect of transfer colitis on liver fibrosis and sclerosing cholangitis in Rag 1-/- mice.

Methods: In order to evaluate the hepatic damage of T-cell reconstituted Rag 1-/- mice we assessed hydroxyproline in liver tissue and serum GPT level. Markers of liver fibrogenesis such as collagen–1, GFAP, α-SMA, MMP–9, and MMP–13 gene expression were tested / assessed by quantitative RT-PCR. Subsequently MMP–9 expression was analyzed at histological level by co-immunostaining and enzymatic activity by zymography methods.

Results: In Rag 1-/- mice liver integrity and fibrosis status were not altered in comparison to controls. Fibrosis related hepatic gene expression of type I collagen, GFAP, and alpha-SMA was decreased. We observed increased hepatic MMP–9 expression in the Rag1-/- mouse model of transfer colitis and could identify CD45+ cells as cellular sources of MMP–9. Other parameters of liver fibrosis were not altered but increased myeloperoxidase expression indicates neutrophil granulocyte infiltration.

Conclusion: Our results demonstrate that significant enhancement of MMP–9 expression at gene transcription, enzymatic and histological level provides an indication of a pro-inflammatory hepatic reaction. Increased myeloperoxidase expression might represent infiltration of MMP–9 expressing neutrophil granulocytes into the liver. Our results reveal a preliminary stage for sclerosing cholangitis in a murine T-cell reconstituted Rag 1-/- model. Subsequent studies analyzing bile duct integrity to characterize the role of MMP–9 in early bile duct damage/changes are under investigation.

Literatur: 1. T cell transfer model of chronic colitis: concepts, considerations, and tricks of the trade Dmitry V. Ostanin, Jianxiong Bao, Iurii Koboziev, Laura Gray, Sherry A. Robinson-Jackson, Melissa Kosloski-Davidson, V. Hugh Price, Matthew B. Grisham. Am J Physiol Gastrointest Liver Physiol. 2009 February; 296(2): G135–G146. 2. Clinical features and management of primary sclerosing cholangitis Marina G Silveira, Keith D Lindor. World J Gastroenterol. 2008 June 7; 14(21): 3338–3349.