One-year timeline kinetics of cytokine-mediated cellular immunity in dogs vaccinated against visceral leishmaniasis

BACKGROUND: The main control strategy for visceral leishmaniasis in Brazil has been based on the elimination of seropositive dogs, although this is not widely accepted. In this context, the use of a long-lasting protective vaccine against canine visceral leishmaniasis (CVL) has been highly expected. The aim of this work was to determine the timeline kinetics of the cytokine microenvironment derived from circulating leukocytes as supportive immunological biomarkers triggered by Leishmune® vaccine. Cross-sectional kinetic analysis of cellular immunity cytokines was carried out at three times (1, 6 and 12 months) after primovaccination with Leishmune®. In vitro short-term whole blood cultures were stimulated with Leishmania infantum soluble antigen (SLAg). The secreted cytokine signatures and their major sources were determined. RESULTS: At six months after vaccination, Leishmune® induced an increase in IL-8, IFN-γ, IL-17a and TNF-α levels and a decrease in IL-10. Cytokine signature analysis revealed a shift in the microenvironment towards a pro-inflammatory profile mediated by IL-8 and IFN-γ. Both, CD4(+) (↑TNF-α(+) and ↑IFN-γ (+)) and CD8(+) (↑IL-17a and ↓IL-4) T-cells contributed to the acquired immune responses observed after stimulation with SLAg. CONCLUSIONS: The changes observed in the cytokine profile suggested that Leishmune® was able to induce an effective response at six months after primovaccination. After one year, it returned to baseline suggesting the need of additional boosting

Higher Expression of CCL2, CCL4, CCL5, CCL21, and CXCL8 Chemokines in the Skin Associated with Parasite Density in Canine Visceral Leishmaniasis

Several previous studies correlated immunopathological aspects of canine visceral leishmaniasis (CVL) with tissue parasite load and/or the clinical status of the disease. Recently, different aspects of the immune response in Leishmania-infected dogs have been studied, particularly the profile of cytokines in distinct compartments. However, the role of chemokines in disease progression or parasite burdens of the visceralising species represents an important approach for understanding immunopathology in CVL. We found an increase in inflammatory infiltrate, which was mainly composed of mononuclear cells, in the skin of animals presenting severe forms of CVL and high parasite density. Our data also demonstrated that enhanced parasite density is positively correlated with the expression of CCL2, CCL4, CCL5, CCL21, and CXCL8. In contrast, there was a negative correlation between parasite density and CCL24 expression. These findings represent an advance in the knowledge of the involvement of skin inflammatory infiltrates in CVL and the systemic consequences and may contribute to developing a rational strategy for the design of new and more efficient prophylactic tools and immunological therapies against CVL

Safety evaluation of a vaccine: Effect in maternal reproductive outcome and fetal anomaly frequency in rats using a leishmanial vaccine as a model.

While the immunogenic potential of the vaccination against infectious diseases was extensively shown, data on the safety assessment of recombinant proteins in vaccine formulations administered during pregnancy are still scarce. In the current study, the antigenicity of a vaccine against leishmaniasis (based on Leishmania braziliensis recombinant protein peroxidoxin) during pregnancy and possible maternal reproductive outcomes and fetal anomalies after immunization with a leishmanial vaccine or adjuvant alone (Bordetella pertussis derived MPLA adjuvant) were assessed. Rats were mated and allocated in three groups: Control-rats received saline; Adjuvant-rats received the adjuvant MPLA, and Vaccine-rats received the combination of MPLA and peroxidoxin. The administration was subcutaneously at the dorsal region, three times (days 0, 7, 14 of pregnancy). On day 21 of pregnancy, all rats were bled for biochemical and immunological measurements. The gravid uterus was weighed with its contents, and the fetuses were analyzed. The immunization with peroxidoxin induced a significant production of circulating IgG levels compared to other groups but caused a significant in post-implantation loss (14.7%) when compared to Control (5.0%) and Adjuvant (4.4%) groups. Furthermore, a significantly high rate of fetal visceral anomalies, such as hydronephrosis and convoluted ureter, was also observed in animals that received vaccine when compared to Control or Adjuvant groups. These data indicate the importance of safety evaluation of vaccines during pregnancy and the limited use of peroxidoxin administration during pregnancy. More importantly, the safety monitoring of immunization with MPLA derived from Bordetella pertussis demonstrated no reproductive outcomes associated with adjuvant administration, suggesting its safe use during pregnancy

Reproductive outcome from rats treated with saline (Control), MPLA (Adjuvant) or MPLA + recombinant peroxidoxin of <i>Leishmania braziliensis</i> (Vaccine) during pregnancy.

<p>Reproductive outcome from rats treated with saline (Control), MPLA (Adjuvant) or MPLA + recombinant peroxidoxin of <i>Leishmania braziliensis</i> (Vaccine) during pregnancy.</p

Ossification sites of rats treated with saline (Control), MPLA (Adjuvant) or MPLA + recombinant peroxidoxin of <i>Leishmania braziliensis</i> (Vaccine) during pregnancy.

<p>Ossification sites of rats treated with saline (Control), MPLA (Adjuvant) or MPLA + recombinant peroxidoxin of <i>Leishmania braziliensis</i> (Vaccine) during pregnancy.</p

Biochemical parameters of rats treated with saline (Control), MPLA (Adjuvant) or MPLA + recombinant peroxidoxin of <i>Leishmania braziliensis</i> (Vaccine) during pregnancy.

<p>Biochemical parameters of rats treated with saline (Control), MPLA (Adjuvant) or MPLA + recombinant peroxidoxin of <i>Leishmania braziliensis</i> (Vaccine) during pregnancy.</p