Fluoxetine reduces `Toxoplasma gondii` tachyzoite counts and inflammation, improving survival in acute murine toxoplasmosis
Background
Acute toxoplasmosis, caused by the obligate intracellular parasite Toxoplasma gondii, poses a life-threatening risk due to rapid tachyzoite replication and severe immunopathological sequelae from the robust immune response. Current treatments and vaccines are often unsatisfactory, leaving a critical gap in managing this global health concern. Fluoxetine, a selective serotonin reuptake inhibitor (SSRI), has recently garnered attention for its potential in repurposing to control cytokine storm in various clinical settings, suggesting a broader immunomodulatory capacity beyond its neurological effects.
Study Design
Researchers established an animal model of acute toxoplasmosis using the virulent RH strain in mice. To assess therapeutic effects, mice were administered either spiramycin or fluoxetine for 5 days starting from the day of infection. For prophylactic evaluation, fluoxetine administration began 2 weeks prior to infection induction. Primary endpoints included tachyzoite counts, histopathological changes, inflammatory cytokine levels (TNF-α, IL-4, MCP-1), redox status, apoptosis markers (p21), vascular dysfunction markers (endocan), and growth differentiation factor 15 (GDF-15) levels. Scanning electron microscopy was used to detect morphological effects on tachyzoites.
Results
Fluoxetine demonstrated antiparasitic activity comparable to spiramycin, achieving a comparable reduction of tachyzoite counts. Scanning electron microscopy revealed prominent deleterious morphological effects on tachyzoites by both drugs. Histopathological changes were improved by both drugs, with fluoxetine exhibiting superior effect, particularly in the brain. Fluoxetine substantially attenuated the inflammatory response through a reduction of TNF-α, IL-4, and MCP-1 levels. Prophylactic fluoxetine administration also induced improvement of the redox status. > Fluoxetine exhibited superior effect in reversing infection-induced modulation of apoptosis and vascular dysfunction in the brain by significantly reducing the levels of p21 and endocan, respectively. Additionally, fluoxetine upregulated the levels of growth differentiation factor 15 (GDF-15) in the spleen, which partly accounted for the limitation of immunopathology. These combined effects led to better survival in acute murine toxoplasmosis.
Key Findings
- Fluoxetine achieved comparable reduction of
Toxoplasma gondiitachyzoite counts to spiramycin. - Fluoxetine improved histopathological changes, with a superior effect in the brain compared to spiramycin.
- Fluoxetine substantially attenuated inflammatory response by reducing
TNF-α,IL-4, andMCP-1levels. - Fluoxetine significantly reduced
p21andendocanlevels, reversing apoptosis and vascular dysfunction in the brain. - Fluoxetine upregulated
GDF-15in the spleen, contributing to immunopathology limitation and better survival.
Why It Matters
This study highlights fluoxetine's potential as a repurposed therapeutic agent for acute toxoplasmosis, offering a novel strategy beyond existing unsatisfactory treatments. Its dual action—antiparasitic and superior anti-inflammatory/immunomodulatory effects—suggests it could serve as an effective adjunct therapy. The observed vascular protective and pro-apoptotic effects in the brain are particularly significant, addressing critical aspects of disease pathology that current interventions often miss. While this is a preclinical animal study, the findings open avenues for exploring fluoxetine in human clinical trials, potentially leading to a more comprehensive protocol for managing severe toxoplasmosis, especially in immunocompromised individuals. Further research is needed to translate these findings into a usable clinical protocol, including optimal dosing and timing in humans.
fluoxetine
toxoplasmosis
anti-inflammatory
immunomodulatory
antiparasitic
preclinical-animal