Background & aims: Crohn's disease (CD) and ulcerative colitis (UC) are associated with chronic tissue damage and continuous tissue repair. A central, but not well-characterized, event during this process is the migration of activated fibroblasts to the wound.
Methods: Human colonic lamina propria fibroblasts (CLPF) were isolated from patients with CD and UC and from healthy controls and were characterized by immunocytochemistry. Migration assays of CLPF were performed in the modified 48-well Boyden chamber. Focal adhesion kinase (FAK) and FAK autophosphorylation in migrating CLPF were determined by Western blotting. FAK mRNA expression was investigated by Northern blotting.
Results: The migration of CD-CLPF and UC-CLPF was significantly reduced when compared with control-CLPF. This was correlated with a decrease in FAK phosphorylation, whereas, in migrating control-CLPF, an increase was found. Similarly, the presence of the inflammatory mediators interferon (IFN)-gamma (50 ng/mL) or tumor necrosis factor (TNF) (30 ng/mL) in conditioned medium significantly reduced the migration of control-CLPF to 41% +/- 4% or 30% +/- 7%, respectively. Preincubation of control-CLPF with TNF (20 ng/mL) and IFN-gamma (10 ng/mL) for 3 days reduced their migratory response to 10% of control (P < 0.001), which also was correlated with a decrease in FAK phosphorylation. Culture of IFN-gamma/TNF-treated CLPF for a further 7 days without cytokines did not restore the migratory potential and FAK phosphorylation, indicating a persistent functional change.
Conclusions: CD- and UC-CLPF have a reduced migratory potential compared with normal CLPF. That may be caused by contact with IFN-gamma and TNF. This loss of migratory potential was correlated with diminished FAK phosphorylation.