Immunologic Indicators of Clinical Progression during CanineLeishmania infantumInfection

Abstract

In both dogs and humans Leishmania infantum infection is more prevalent than disease, as infection often does not equate with clinical disease. Previous studies additively indicate that advanced clinical visceral leishmaniasis is characterized by increased production of anti-Leishmania antibodies, Leishmania-specific lymphoproliferative unresponsiveness, and decreased production of gamma interferon (IFN-␥) with a concomitant increase of interleukin-10 (IL-10). In order to differentiate infection versus progressive disease for better disease prognostication, we temporally evaluated humoral and cellular immunologic parameters of naturally infected dogs. The work presented here describes for the first time the temporal immune response to natural autochthonous L. infantum infection in foxhounds within the United States. Several key changes in immunological parameters should be considered when differentiating infection versus clinical disease, including a dramatic rise in IgG production, progressive increases in antigen-specific peripheral blood mononuclear cell proliferation, and IFN-␥ production. Polysymptomatic disease is precluded by increased IL-10 production and consistent detection of parasite kinetoplast DNA in whole blood. This clinical presentation and the immuno-dysregulation mirror those observed in human patients, indicating that this animal model will be very useful for testing immunomodulatory anti-IL-10 and other therapies.

Leishmania-Derived Trimannose Modulates the Inflammatory Response To Significantly Reduce Leishmania major-Induced Lesions

“…Leishmania major (MHOM/IL/80/Friedlin) cultures were maintained in complete Grace's insect medium (Sigma) with 10% heat-inactivated fetal bovine serum, 2 mM glutamine, 100 U/ml penicillin, and 100 l/ml of streptomycin at 28°C and harvested for parasite freeze-thaw antigen or live parasites for inoculation as described previously (43,44). One of the following was injected into the left hind footpad: 5 ϫ 10 6 L. major promastigotes in 50 l of sterile PBS, 5 ϫ 10 7 beads (carrier [uncoated] or trimannose-coated beads) in 50 l of PBS, or a single injection of 5 ϫ 10 6 L. major promastigotes and 5 ϫ 10 7 beads (carrier or trimannose-coated beads) in 50 l of PBS.…”

“…Parasite DNA isolation and qPCR were performed as previously described (43)(44)(45). DNA was isolated from homogenized footpads with a QIAamp DNA blood minikit per the manufacturer's instruction (Qiagen, Valencia, CA).…”

Canine Visceral Leishmaniasis in Brazil

“…In whole blood, the increase of IL-10 has been associated with detection of parasite DNA [97]. Do Nascimento et al, in accordance, state that in CVL there is increase in expression of pro-inflammatory cytokines IFN-γ and TNF-α in dogs with low splenic parasitism, while dogs with higher parasitic load show an increase in IL-10 [98].…”

Activation of Autophagy and Nucleotide-Binding Domain Leucine-Rich Repeat–Containing-Like Receptor Family, Pyrin Domain–Containing 3 Inflammasome during Leishmania infantum–Associated Glomerulonephritis

“…Dogs with symptomatic VL typically have hypergammaglobulinemia and abundant circulating parasite antigen. 22 Previous studies evaluating proteins associated with VL glomerular deposits had conflicting results. 7,29 One study found granular deposits of IgG, IgM, and C3 within 31 of 34 dogs examined.…”

“…The 10 dogs from Brazil, evaluated via full physical examination, were more likely to be symptomatic at the time of presentation (7 of 10 dogs), and also had a higher probability of comorbidities, including malnutrition, helminth infection, or rickettsial infections, and had positive anti-Leishmania antibodies. Study animals were enrolled for this study on the basis of IFAT Q19 serology, as previously described, 22 …”