Immunological response and markers of cell damage in seropositive horses for Toxoplasma gondii.

The study analysed the immune response and cell damage markers in horses found to carry the parasite Toxoplasma gondii, noting a heightened immune response and signs of cell damage in horses with higher levels of antibodies to the parasite.

Research Objective

• The researchers aimed to study the immunological variables and cellular damage markers in the blood serum of horses that tested positive for T. gondii, a disease-causing parasite. The goal was to better understand how this parasite affects the equine population, since little is known about this disease in horses.

Methodology

• The team sourced serum samples from adult horses in Santa Catarina State, Brazil, which had been used in a previous study. These samples were grouped according to the level of antibodies for T. gondii present, which was determined by an immunofluorescence assay.
• The groups consisted of 20 samples from horses with no antibodies (Group A – control), 20 samples with antibody titers of 1:64 (Group B), 20 samples with titers of 1:256 (Group C), and five samples with titers of 1:1024 (Group D).

Findings

• Horses in Groups B, C, and D (those with antibodies for T. gondii) were found to have elevated levels of immunoglobulins (IgM and IgG), pro-inflammatory cytokines (TNF-α, IFN-γ, IL-1, IL-4, and IL-6) and protein C-reactive protein, along with reduced levels of IL-10, an anti-inflammatory cytokine. This was compared to Group A, which had no antibodies.
• Increased levels of nitric oxide were also observed in the antibody-positive horses. This indicated an active humoral and cellular immune response in these animals.
• Interestingly, the research noted a correlation between high levels of antibodies and inflammatory mediators, suggesting that the presence of T. gondii in horses provokes a significant immune response.
• The researchers also found elevated markers of cell injury caused by lipid peroxidation (TBARS) and protein oxidation (AOPP) in horses testing positive for T. gondii, when compared to the seronegative animals.

Conclusion

• Based on these findings, the study suggests that horses which are seropositive for T. gondii maintain active immune responses against the parasite. As a result of the chronicity of the disease, they display cellular damage that could potentially lead to tissue destruction and the emergence of clinical disease symptoms.