The Use of Animal Models for Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a description of classical symptoms that can be grouped together to be recognized as a common entity. However, the disease is more heterogeneous and is likely composed of many different, distinct diseases (1) . This heterogeneity is of two types. First, the disease can be classified into several subtypes, and second, the underlying cause of each disease group may be attributable to different genetic and environmental factors, each contributing to a distinct disease phenotype. This is an important starting point when discussing animal models for RA. Thus, there is not one model for RA. There are, and must be, several different models with different symptoms and different pathogenic mechanisms, controlled by different genes.