COX2 expression increases in skin biopsies from dogs affected by nodular cutaneous leishmaniosis

Introduction: Cyclooxygenase 2 (COX-2) and vascular endothelial growth factor (VEGF) expression in dogs affected by nodular cutaneous leishmaniosis was evaluated. Dogs with this disease are less resistant to the infection due to failure of Langerhans cells and MHC class II-expressing keratinocytes to prime T lymphocytes. Materials and Methods: Skin punch biopsies (8 mmP) were taken from eight dogs affected by nodular cutaneous leishmaniosis, three dogs affected by ‘sterile’ chronic active dermatitis and five healthy dogs. Serial tissue sections were incubated with a set of antibodies in order to assess COX2 (goat pAb anti-COX2; ab23672; ABCAM) and VEGF (mouse anti-canine VEGF mAb; clone 247109; R & D Systems) expression. Results: COX2 and VEGF expression was significantly higher in Leishmania-positive (L+) samples than in those without infection (L-) and was almost absent in healthy skin. L+ samples showed strong COX2 and VEGF expression by the endothelial cells of dermal and hypodermal capillaries as well as nerve endings, while L- samples displayed COX2 only in macrophages, small groups of dermal fibroblasts and rare neutrophils. COX2 and VEGF expression was seen occasionally in a few fibroblasts and endothelial cells in control samples. Conclusions: Strong local COX2 and VEGF expression in dermatitis induced by Leishmania spp. was correlated with weaker macrophage reactivity as well as to the inability of these cells to kill organisms, probably due to higher local synthesis of PGE2.