Special Issue: Chronic inflammation in pregnant women with latent toxoplasmosis and explanation of discordant results of serological tests for toxoplasmosis

Toxoplasma gondii (Nicolle et Manceaux, 1908), an intracellular parasite that causes toxoplasmosis, infects a third of the human population. Latent toxoplasmosis has been linked to altered immune responses, including elevated proinflammatory cytokines. In early pregnancy, the immune system adapts to balance inflammation and foetal tolerance. This study assessed whether pregnant women in the first trimester infected with Toxoplasma gondii have different cytokine levels than uninfected women. This study also examined whether women with discordant test results for toxoplasmosis represent a distinct group or a mixed group composed of infected women with unusually low levels of anti-Toxoplasma antibodies and uninfected women with high levels of cross-reacting antibodies. We measured 18 cytokines (IL-1β, IL-1ra, IL-2, IL-4, IL-7, IL-9, IL-17A, Eotaxin, FGF basic, G-CSF, IFN-γ, IP-10, MCP-1, MIP-1α, MIP-1β, PDGF-BB, RANTES, TNF-α) in 78 pregnant women, classified as Toxoplasma-positive, Toxoplasma-negative or Toxoplasma-discordant (negative by IgG ELISA, positive by complement fixation test [CFT]). Using exploratory factor analysis, we identified two factors, the first explaining 29.6% and the second 24.9% of the total variability in cytokine concentrations. Toxoplasma-positive women scored significantly higher in the second factor, primarily associated with cytokines linked to Th1-driven inflammation and cellular immunity. Specifically, these women exhibited elevated levels of IL-1β, IL-1ra, IL-2, FGF basic and PDGF-BB compared to Toxoplasma-negative women. This finding suggests that pregnant women with latent toxoplasmosis experience some degree of chronic inflammation. Additionally, our results indicate that Toxoplasma-discordant women are likely Toxoplasma-negative individuals with detectable anti-Toxoplasma IgM antibodies. However, as this study focused on pregnant women, further research is necessary to validate these conclusions in broader populations.