Modified skin-window technique in cynomolgus macaques (Macaca fasicularis) for assessing neutrophil extravasation

Alterations in neutrophil extravasation are seen in disease states and in response to therapeutics. To investigate neutrophil extravasation during the acute inflammatory response, a skin-window technique used in humans was adapted for use in cynomolgus macaques (Macaca fasicularis). Modulation of neutrophil extravasation was attempted with systemic methotrexate and local application of the anaphylatoxin recombinant C5a (rC5a). On day 1, skin windows were created in 4 ketamine-anesthetized monkeys on both forearms by mildly abrading the skin and then overlaying the abrasions with filter paper either saturated in saline or rC5a for 6 h. At 2.5 h prior to generation of new skin windows on day 2, the monkeys received 4.5 mg methotrexate IM, and skin windows and treatment with saline or rC5a were repeated on new forearm sites on each monkey. All papers were analyzed for albumin, neutrophil number, and the neutrophil chemoattractant IL8. Day 1 albumin levels did not differ between groups, indicating consistent abrasion. Methotrexate given prior to the day 2 abrasions reduced neutrophil extravasation and IL8 levels compared with those on day 1. rC5a partially abrogated the methotrexate-induced reduction in neutrophil extravasation and IL8 production. The skin-window technique was well tolerated by the monkeys and successfully accommodated measurement of changes in neutrophil extravasation in response to inflammatory modulators.