Modification of fibroblast gamma-interferon responses by extracellular matrix

Fibroblasts from scaffold-based three-dimensional human cultures have been demonstrated to colonize ulcer wound beds and persist for at least 6 mo without rejection. This study examines the expression in these cultures of molecules associated with activation of the immune system in acute rejection. Studies in monolayer cultures showed that fibroblasts expressed CD40 at about 10% of the surface density seen in umbilical vein endothelial cells, whereas HLA-DR was undetectable. In these cultures, both molecules were induced by gamma-interferon. In scaffold-based three-dimensional cultures, however, a majority of the fibroblasts showed little induction of CD40 and HLA-DR in response to gamma-interferon, although HLA class I expression was increased. Fibroblasts re- isolated from the three-dimensional cultures and cultured in monolayers recovered HLA-DR induction in response to gamma-interferon. Fibroblasts cultured in an alternative three-dimensional system using collagen gels showed CD40 and HLA-DR induction by gamma-interferon in the same manner as monolayer cultures. Comparison of phosphorylation of signal transducer and activator of transcription 1 on tyrosine-701 showed it to be similar in monolayer and three-dimensional culture, and phospho-signal transducer and activator of transcription 1 moved into the nucleus. Induction of the class II transcription activator was greatly reduced, however. We propose that interaction of fibroblasts with the fibroblast-derived extracellular matrix is an important modulator of gamma-interferon responsiveness and that this interaction may play a role in the low immunogenicity of allogeneic fibroblasts grown on scaffolds.