Alteration of synoviocytes by inflammation--the source of a persistent non-immunologic drive in synovitis: analysis of levels of mRNA expression by a simple multi-gene assay.

A solid phase hybridization assay was developed to assess simultaneously the level of transcription of multiple genes in inflammatory tissues and in derivative cell lines. It involves binding of a labelled cDNA probe to plasmids containing cDNAs of the genes of interest in excess concentration applied to a nylon membrane in a dot blot format. After hybridization under stringent conditions, the blot is washed and counts enumerated. Levels of mRNA are compared between different samples by normalization to GAPDH. The results indicate that mesenchymal cells isolated from inflammatory synovia exhibit alterations in the pattern of gene expression which distinguish them from similarly isolated and cultured cells from non-inflammatory synovia. These patterns are sustained through multiple passages in tissue culture, suggesting that this may reflect a persistently altered state of fibroblast differentiation induced by exposure to an inflammatory milieu.