Research

Demonstration of a novel technique to quantitatively assess inflammatory mediators and cells in rat knee joints

Nicola J Barton¹ , David A Stevens² , Jane P Hughes² , Adriano G Rossi³ , Iain P Chessell² , Alison J Reeve² and Daniel S McQueen¹

¹  Division of Neuroscience, University of Edinburgh, Medical College, 1 George Sq, Edinburgh, EH8 9JZ, UK

²  Neurology CEDD, GlaxoSmithKline R&D Ltd, Harlow, Essex CM19 5AW, UK

³  MRC Centre for Inflammation Research, The Queens Medical Research Institute, University of Edinburgh, EH16 4TJ, UK

author email corresponding author email

Journal of Inflammation 2007, 4:13doi:10.1186/1476-9255-4-13

Published:	13 June 2007

Abstract

Background

The inflammation that accompanies the pain and swelling associated with osteo- and rheumatoid arthritis is mediated by complex interactions of inflammatory mediators. Cytokines play a pivotal role in orchestrating many of these processes, including inflammatory cell recruitment, adhesion and activation. In addition, prostaglandins are secreted into the synovial cavity and are involved in perpetuation of local inflammation, vasodilatation and vasoconstriction, and also with bone resorption. Pre-clinical models have been developed in order to correlate to the human disease and principle among these is the adjuvant-induced arthritis model in the rat.

Methods

We have developed a technique to quantitatively assess the contents of synovial fluid samples from rat joints. Two needles joined together are inserted into the knee joint of anaesthetised rats and connected to a Watson-Marlow perfusion pump. Sterile saline is infused and withdrawn at 100 μl min^-1 until a 250 μl sample is collected.

Results

Our results demonstrate up to 125 fold increases in synovial IL1α and IL1β concentrations, approximately 30 fold increases in levels of IL6 and IL10 and a 200–300 fold elevation in synovial concentrations of TNFα during FCA-induced experimental arthritis. Finally, this novel technique has demonstrated a dose-response relationship between FCA and the total cell counts of synovial perfusates.

Conclusion

In summary, this new technique provides a robust method for quantifying inflammatory mediators and cells from the synovial cavity itself, thereby detailing the inflammatory processes from within the capsule and excluding those processes occurring in other tissues surrounding the entire articulation.