Dogs immunized with LBSap vaccine displayed high levels of IL-12and IL-10 cytokines and CCL4, CCL5 and CXCL8 chemokinesin the dermis.

Abstract

The complex interplay between cytokines and chemokines regulates innate and adaptive immuneresponses against pathogens; specifically, cytokine and chemokine expression drives activation ofimmune effector cells and their recruitment to tissue infection sites. Herein, we inoculated dogs withLeishmania braziliensis antigens plus saponin (the LBSap vaccine), as well as with the vaccine components,and then used real-time PCR to evaluate the kinetics of dermal expression of mRNAs of cytokines (IL-12,IFN- _, TNF- _, IL-4, IL-13, TGF- _ and IL-10) and chemokines (CCL2, CCL4, CCL5, CCL21 and CXCL8) 1, 12, 24and 48 h after inoculation. We also evaluated the correlation between cytokine and chemokine expres-sion and dermal cellularity. The LBSap vaccine induced high levels of IL-12 and IL-10 expression at 12 and24 h, respectively. Furthermore, we observed positive correlations between IL-12 and IL-13 expression,IFN- _ and IL-13 expression, and IL-13 and TGF- _ expression, suggesting that a mixed cytokine microen-vironment developed after immunization with the vaccine. Inoculation with the saponin adjuvant aloneinduced a chemokine and cytokine expression profile similar to that observed in the LBSap group. CCL4and CXCL8 chemokine expression was up regulated by the LBSap vaccine. CCL5 expression was initiallyhighest in the LBSap group, but at 48 h, expression was highest in the LB group. Information about thekinetics of the immune response to this vaccine gained using this dog model will help to elucidate themechanisms of and factors involved in a protective response against Leishmania infection and will aid inestablishing rational approaches for the development of vaccines against canine visceral leishmaniasis.