Rheumatoid factor, anti-heat shock protein (65 kDa) antibodies and anti-nuclear antibodies in equine joint diseases.

This research paper investigated the potential role of autoimmune responses in causing equine joint diseases. It tested three different autoantibodies in both blood serum and joint fluid, and briefly found that certain antibodies could be elevated in horses with specific joint conditions. However, these changes were not significantly correlated with a pattern of disease development.

Investigating Autoimmune Mechanisms in Equine Joint Diseases

• The study was designed to test the hypothesis that autoimmune responses could be contributing to the development of equine joint diseases. Autoimmune responses refer to instances where the immune system mistakenly attacks the body’s own cells, considering them as foreign invaders.
• The researchers were specifically interested in three types of autoantibodies: IgM-rheumatoid factor (IgM-RF), antibodies against a protein known as heat shock protein 65 kDa (HSP65), and anti-nuclear antibodies (ANA). These antibodies were selected because they are commonly elevated in certain autoimmune diseases in humans.

Evaluation of Autoantibodies

• The team tested for these antibodies in both the blood serum and synovial fluid (fluid in the joints) of horses with different types of joint disorders.
• The IgM-RF and HSP65 antibodies were tested with an ELISA assay, while the ANA was tested with indirect immunofluorescence to whole cell nuclear components.
• The findings were that, overall, the presence of these antibodies was only marginally higher in horses with joint diseases, which did not clearly indicate a pattern related to disease.

Notable Findings

• When examining the results of the groups, they did notice that the levels of IgM-RF in the synovial fluid were significantly elevated in horses with osteoarthritis, traumatised joints, and articular fractured bones.
• However, the serum levels of IgM-RF in the samples of horses with joint conditions did not significantly differ from those of healthy horses.
• Significant increases in HSP65 antibodies were only detected in the synovial fluid of horses with traumatised joints.

Correlations and Conclusion

• No correlations were found between the levels of these antibodies in the synovial fluid and blood serum, which means the bodily presence of these antibodies is inconsistent.
• Even though antibody levels to HSP65 correlated with concentrations of another immune protein called IgG, the authors caution that it is not clear what role, if any, that the HSP65 protein plays in the development of joint diseases.
• Finally, the researchers were unable to detect any ANA antibodies in the blood samples.