Experimental Arthritis Mouse Models Driven by Adaptive and/or Innate Inflammation.

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease mainly affecting synovial joints. The clinical presentation of RA shows the heterogeneity of this disease with its underlying complex interactions between the innate and adaptive immune system and flare-ups of disease. Different disease models such as collagen induced arthritis, antigen induced arthritis, and Streptococcal cell wall induced arthritis can be exploited to investigate different aspects of the pathogenesis of arthritis. The disease can be monitored macroscopically over time via scoring systems. For histological examination, paraffin embedded knee sections can be used for hematoxylin and eosin staining to visualize cellular infiltration as well as for tartrate-resistant acid phosphatase (TRAP) staining to identify osteoclast-like cells. Cellular infiltration of the synovium by different myeloid cells such as tissue resident macrophages, dendritic cells and neutrophils can be monitored using flow cytometry. Here, we describe the methods for inducing the different mouse models for arthritis, including scoring systems per model, histological and flow cytometric analysis.