Cinética da Migração Celular Intradérmica em Hamsters Sensibilizadoscom Diferentes Constituintes Antigênicos de duas Vacinas ContraLeishmaniose Visceral Canina

by Dores Moreira, Nádia das

Abstract (Summary)
Dogs represent the most important domestic reservoirs of L. chagasi, and a vaccine against caninevisceral leishmaniasis (CVL) would be an important tool in the control of human VL by decreasingdramatically the infection pressure of L. chagasi/L. infantum. Although, an effective vaccineagainst human and CVL is not yet available, much effort has been expended in this area in recentyears and several candidate vaccine antigens have been studied in dogs. In this context, hamstershave been used as a model for understanding the mechanisms of immunogenicity for vaccinesagainst CVL. In order to gain a better understanding of how the antigens and vaccine adjuvantsinteract with the innate immune response, we test two vaccines schedules: a commercialLEISHMUNE® vaccine and a killed Leishmania braziliensis antigen plus saponin (LBSap). Themain objective of the present study was to assess the kinetics of cell migration in the skin ofhamsters and the levels of nitric oxide after inoculation with distinct antigenic components of theLBSap and LEISHMUNE® vaccines. Dermal inflammatory infiltrate profiles, circulatingleukocytes and the role of NO/iNOS during intradermal injections in abdominal area were assessedat different times (1, 12, 24, 48, 96 and 168 hours) were assessed. In the current study, 120hamsters were inoculated in the abdominal region by intradermal via and were subdivided withinfive experimental groups, with 24 hamsters each: (i) SALINA group (S), which received inoculumwith sterile saline 0.85%; (ii) SAPONINA group (Sap), inoculated with 100 ?g of saponinadjuvant; (iii) L. braziliensis group (LB), inoculated with 60 mg/protein of L. braziliensis, (iv)LBSap group that received 60 ?g of L. braziliensis antigen plus 100 ?g of saponin; and (v)LEISHMUNE® group, which received 150 ?g of FML lyophilized antigen associated with 100 ?gof saponin. After 1, 12, 24, 48, 96 and 168 hours; skin biopsies were performed. The resultsobtained in this study highlighted the hamster (Mesocricetus auratus) as a good model to assess theinnate immune response enabling a better understanding of the in situ cellular events triggered afterinoculation. The study of kinetics of cell migration contributes in the selection of vaccine antigensand adjuvants even before the test in dogs, especially with regard to issues related to the safety andimmunogenicity. Therefore, it supports the search of the new potential vaccines candidates againstCVL. The discrete local reactions recorded after inoculation with SAPONIN allow us torecommend its use for dogs. The SAPONIN was able to promote an increase in the circulations ofneutrophils and an early reduction of lymphocytes, while LB, LBSap and LEISHMUNE® promotedan increase in neutrophils in the later period indicating a mobilization of these cells in systemiclevels soon after the saponin inoculations and the regulation of this phenomenon due to theassociation with the Leishmania sp antigens. Furthermore, the SAPONIN reduced the number ofcirculating lymphocytes in the early period, while LBSap caused a late reduction; LEISHMUNE®induced a persistent reduction of these cell populations throughout all points of the kinetics. Thisdata showed that the SAPONIN facilitate in the mobilization of lymphocytes that has beenrecruited along with neutrophils to migrate into the inoculum site. We also observed a latereduction of neutrophils in the inflammatory focus in animals inoculated with SAPONIN, LBSap,and LB whereas the LEISHIMUNE® group showed a inclination to the maintenance of thispopulation, indicating the participation of neutrophils in innate immune responses after inoculationwith antigens plus vaccine adjuvants. The L. braziliensis antigen was able to cause an earlyreduction of lymphocytes in the dermis while SAPONIN and LBSap triggered a late recruitment,suggesting the role of SAPONIN in the traffic of antigen presenting cells and also induction of thelymphocyte migration even in the late period. The SAPONIN carried out an early and persistentrecruitment of macrophages while LBSap and LEISHMUNE® vaccines showed a tendency tomaintain the levels of this population in the dermis, suggesting that the association of adjuvant andantigens may influence the decrease of the monocytes migration. The increase of seric NO levels inLEISHMUNE® and LBSap groups indicates the involvement of the type 1 cytokines such as IFN-?,which can be essential in the polarization of the protective acquired immune response during thevaccination process.
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Claúdia Martins Carneiro; Wanderson Geraldo de Lima; Elenice Moreira Lemos; Alexandre Barbosa Reis

School:Universidade Federal de Ouro Prêto

School Location:Brazil

Source Type:Master's Thesis

Keywords:1 hamster teses 2 leishmaniose 3 vacinação de animais 4 cães doenças i universidade federal ouropreto ii título imunologia


Date of Publication:01/29/2008

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