Chronic inflammation induced by type I collagen in rats.

In this study we attempt to investigate if collagen type 1 from bovine Achilles tendon is capable of causing an inflammatory response. Thus, we immunized rats with a collagen emulsion injected in the right hind paw, via subplantar, and intradermally on the back. Seven days later, the rats were reimmunized by intradermal injection on the base of the tail with an identical emulsion. The inflammatory response was assessed by measuring the hind paw swelling of the rats every seven days for two months. We also analysed the levels of anticollagen antibodies in each rat during the experimental period. An indirect microELISA method was developed to determine collagen-specific-antibodies in rat serum. We observed a chronic inflammation in 41% of immunized rats. This pathology results in local swelling in the hind paw that remained for at least two months. This model was accompanied with the production of antibodies against collagen that appeared on day 14 after induction and remained during the study period (56 days). A positive correlation between swelling and antibody titre was observed.