Role of epithelial integrin-linked kinase in promoting intestinal inflammation: effects on CCL2, fibronectin and the T cell repertoire.

Abstract

BACKGROUND:

The role of integrin signaling in mucosal inflammation is presently unknown. Hence, we aimed to investigate the role of epithelial-derived integrin-linked kinase (ILK), a critical integrin signaling intermediary molecule, in colonic inflammation.

METHODS:

Conditional intestinal epithelial cell ILK knockout mice were used for assessment of acute and chronic dextran sodium sulfate (DSS)-induced colitis. Disease activity was scored using standard histological scoring, mucosal cytokines were measured using ELISA, chemokines were determined using reverse-transcription polymerase chain reaction, as well as Q-PCR, and intracellular cytokine staining performed using FACS analysis.

RESULTS:

In both acute and chronic DSS-induced colitis, compared to wild-type mice, ILK-ko mice exhibit less weight loss, and have reduced inflammatory scores. In an in vitro model system using HCT116 cells, we demonstrate that si-RNA mediated down-regulation of ILK results in a reduction in monocyte chemoattractant protein 1 (MCP1, CCL2) chemokine expression. A reduction in CCL2 levels is also observed in the tissue lysates of chronically inflamed colons from ILK-ko mice. Examination of mesenteric lymph node lymphocytes from ILK-ko mice reveals that there is a reduction in the levels of IFN gamma using intracellular staining, together with an increase in Foxp3+ T regulatory cells. Immunohistochemistry demonstrates that reduced fibronectin expression characterizes the inflammatory lesions within the colons of ILK-ko mice. Intriguingly, we demonstrate that fibronectin is directly capable of downregulating T regulatory cell development.

CONCLUSIONS:

Collectively, the data indicate for the first time that ILK plays a pro-inflammatory role in intestinal inflammation, through effects on chemokine expression, the extracellular matrix and immune tolerance.

• Authors: Kiran Assi, Scott Patterson, Shoukat Dedhar, David Owen, Megan Levings, Baljinder Salh
• Journal: BMC immunology (BMC Immunol) Vol. 12 Pg. 42 (Aug 01 2011) ISSN: 1471-2172 [Electronic] England
• PMID: 21806815 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Chemokine CCL2
• Fibronectins
• Immunologic Factors
• Lipopolysaccharides
• integrin-linked kinase
• Protein Serine-Threonine Kinases

Topics

• Animals
• Cell Line, Tumor
• Chemokine CCL2 (biosynthesis, metabolism)
• Colitis (chemically induced, enzymology, immunology)
• Epithelial Cells (enzymology)
• Female
• Fibronectins (immunology, metabolism)
• Gene Expression Regulation (drug effects)
• HCT116 Cells
• Humans
• Immunologic Factors (pharmacology)
• Lipopolysaccharides (pharmacology)
• Male
• Mice
• Mice, Knockout
• Phosphatidylinositol 3-Kinases (metabolism)
• Protein Serine-Threonine Kinases (genetics, metabolism)
• T-Lymphocytes (immunology, metabolism)
• T-Lymphocytes, Regulatory (immunology, metabolism)
• Weight Loss (genetics)