Modulation of host HIF-1α activity and the tryptophan pathway contributes to the anti-Toxoplasma gondii potential of nanoparticles

- L-tryptophan relieved parasite growth restriction by nanoparticles.
- Nanoparticles modulate host HIF-1α and IDO activity while mildly activating kynurenine pathway.

BackgroundToxoplasmosis constitutes a large global burden that is further exacerbated by the shortcomings of available therapeutic options, thus underscoring the urgent need for better anti-Toxoplasma gondii therapy or strategies. Recently, we showed that the anti-parasitic action of inorganic nanoparticles (NPs) could, in part, be due to changes in redox status as well as in the parasite mitochondrial membrane potential.MethodsIn the present study, we explored the in vitro mode of action of the anti-T. gondii effect of NPs by evaluating the contributions of host cellular processes, including the tryptophan pathway and hypoxia-inducing factor activity. NPs, at concentrations ranging from 0.01 to 200 µg/ml were screened for anti-parasitic activity. Sulfadiazine and/or pyrimethamine served as positive controls.ResultsWe found that interplay among multiple host cellular processes, including HIF-1α activity, indoleamine 2,3-dioxygenase activity, and to a larger extent the tryptophan pathway, contribute to the anti-parasitic action of NPs.ConclusionTo our knowledge, this is the first study to demonstrate an effect of NPs on the tryptophan and/or kynurenine pathway.General significanceOur findings deepen our understanding of the mechanism of action of NPs and suggest that modulation of the host nutrient pool may represent a viable approach to the development of new and effective anti-parasitic agents.

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