title: In Leishmania major-induced inflammation, interleukin-13 reduces hyperalgesia, down-regulates IL-1β and up-regulates IL-6 in an IL-4 independent mechanism.
abstract: Infection with high dose Leishmania major induces a sustained hyperalgesia in BALB/c mice while low dose induces a short lived hyperalgesia both accompanied with the upregulation of IL-1β and IL-6. Although IL-13 was shown to reduce the high dose L. major hyperalgesia during the treatment period, this effect was accompanied by a significant decrease in the levels of IL-1β and a significant increase in the levels of IL-6 in the paws of mice even beyond this period. Those results suggest that IL-13 exerts those effects via the induction of another mediator, IL-4 being a potential candidate due to its known hypoalgesic effects in other models and to its close functional closeness to IL-13 especially at the level of receptors. In this study we correlated the pain thresholds and the levels of IL-1β, IL-6 and IL-4 with the period of IL-13 treatment and beyond it in mice infected with high and low dose of L. major. The results of both models show that IL-1β plays no direct role in provoking the observed hyperalgesia after stopping the treatment with IL-13 which is in contrary to IL-6 which might be a key player after the treatment period. Furthermore we demonstrate that there is no correlation between the levels of IL-4, hyperalgesia, the decreased IL-1β levels and the increased levels of IL-6 in the paws of IL-13 treated and L. major (high and low dose) infected BALB/c mice.
authors.affiliation: Faculty of Sciences, Biology Department, University of Balamand, Koura, Lebanon. marckaram@terra.net.lb
authors.forename: Marc C
authors.initials: MC
authors.lastname: Karam
authors.forename: Rana
authors.initials: R
authors.lastname: Merckbawi
authors.forename: Jane E
authors.initials: JE
authors.lastname: El-Kouba
authors.forename: Samer I
authors.initials: SI
authors.lastname: Bazzi
authors.forename: K B
authors.initials: KB
authors.lastname: Bodman-Smith
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D015536:Down-Regulation; D005260:Female; D006930:Hyperalgesia / Q000276:immunology* / Q000469:parasitology; D007249:Inflammation / Q000276:immunology / Q000469:parasitology; D018793:Interleukin-13 / Q000276:immunology*; D053583:Interleukin-1beta / Q000378:metabolism*; D015847:Interleukin-4 / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism*; D018320:Leishmania major / Q000276:immunology*; D016773:Leishmaniasis, Cutaneous / Q000276:immunology* / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D010147:Pain Measurement; D017288:Pain Threshold; D015854:Up-Regulation
chemical_list: D018793:Interleukin-13; D053583:Interleukin-1beta; D015850:Interleukin-6; D015847:Interleukin-4