Murine models of inflammatory pain and clinical evaluation
The carrageenan model was induced by an intraplantar subcutaneous injection of 20 µL of 3% λ-carrageenan (Dalmann et al., 2015). The monoarthritic model was induced by injection of 5 µl of Complete Freund’s Adjuvant (CFA) on either side of the left ankle joint of mice under brief anesthesia (2.5% isoflurane inhalation) (Kerckhove et al., 2014).
To test mechanical allodynia and hyperalgesia, two calibrated von Frey filaments producing a force of 0.04 g and 1.4 g (Bioseb, France) were used, respectively, as described previously (Dalmann et al., 2015). The number of paw withdrawal responses to five stimulations for a given filament force was counted and used as a “pain” parameter (VF score).
The size of the paw edema was measured with a caliper. For the assessment of interleukine-6 (IL-6) content, the paw edema was removed and incubated in RPMI (Roswell Park Memorial Institute medium, Sigma Aldrich, Saint Louis, USA) supplemented with 10% antibiotic cocktail (penicillin, streptomycin, #P11-010, PAA, Austria) at 37°C under a 5% CO2 atmosphere. After overnight incubation, IL-6 was quantified in the supernatant by ELISA.