cDNA arrays in degenerative arthritis research

Large-scale gene expression profiling reveals major pathogenetic pathways of cartilage degeneration in osteoarthritis

OBJECTIVE

Despite many research efforts in recent decades, the major pathogenetic mechanisms of osteoarthritis (OA), including gene alterations occurring during OA cartilage degeneration, are poorly understood, and there is no disease-modifying treatment approach. The present study was therefore initiated in order to identify differentially expressed disease-related genes and potential therapeutic targets.

METHODS

This investigation consisted of a large gene expression profiling study performed based on 78 normal and disease samples, using a custom-made complementary DNA array covering >4,000 genes.

RESULTS

Many differentially expressed genes were identified, including the expected up-regulation of anabolic and catabolic matrix genes. In particular, the down-regulation of important oxidative defense genes, i.e., the genes for superoxide dismutases 2 and 3 and glutathione peroxidase 3, was prominent. This indicates that continuous oxidative stress to the cells and the matrix is one major underlying pathogenetic mechanism in OA. Also, genes that are involved in the phenotypic stability of cells, a feature that is greatly reduced in OA cartilage, appeared to be suppressed.

CONCLUSION

Our findings provide a reference data set on gene alterations in OA cartilage and, importantly, indicate major mechanisms underlying central cell biologic alterations that occur during the OA disease process. These results identify molecular targets that can be further investigated in the search for therapeutic interventions.

Chondrocyte genomics: implications for disease modification in osteoarthritis

Advances in genomic technologies have made genome-wide-association and gene-expression studies a reality. Despite technical and analytical challenges, the application of genomic technologies to osteoarthritis research will lead to a better understanding of the disease at the molecular level. Functional genomics will identify genes involved in the chondrocyte response to cartilage injury and cartilage repair, and will help clarify the role of chondrocytes in arthritis onset, progression and outcome. Systems biology will enable researchers to develop a full portrait of osteoarthritis, a complex and multifactorial disease that involves not only articular cartilage but also synovium, synovial fluid, subchondral bone and peripheral blood. Ultimately such an approach will result in novel diagnostic and therapeutic targets and better disease management.