Influence of indigenous microbiota on experimental toxoplasmosis in conventional and germ-free mice

Toxoplasmosis represents one of the most common zoonoses worldwide. Its agent, Toxoplasma gondii, causes a severe innate pro-inflammatory response. The indigenous intestinal microbiota promotes host animal homoeostasis and may protect the host against pathogens. Germ-free (GF) animals provide an important tool for the study of interactions between host and microbiota. In this study, we assessed the role of indigenous microorganisms in disease development utilizing a murine toxoplasmosis model, which includes conventional (CV) and GF NIH Swiss mice. CV and GF mice orally inoculated with T. gondii had similar survival curves. However, disease developed differently in the two animal groups. In CV mice, intestinal permeability increased and levels of intestinal pro-inflammatory cytokines were altered. In GF animals, there were discrete epithelial degenerative changes and mucosal oedema, but the liver and lungs displayed significant lesions. We conclude that, despite similar survival curves, CV animals succumb to an exaggerated inflammatory response, whereas GF mice fail to produce an adequate systemic response.

Anti-Toxoplasma activity and impact evaluation of lyophilization, hot molding process, and gamma-irradiation techniques on CLH-PLGA intravitreal implants

Intraocular delivery systems have been developed to treat many eye diseases, especially those affecting the posterior segment of the eye. However, ocular toxoplasmosis, the leading cause of infectious posterior uveitis in the world, still lacks an effective treatment. Therefore, our group developed an intravitreal polymeric implant to release clindamycin, a potent anti-Toxoplasma antibiotic. In this work, we used different techniques such as differential scanning calorimetry, thermogravimetry, X-ray diffraction, scanning electron microscopy, and fourier-transform infrared spectroscopy to investigate drug/polymer properties while manufacturing the delivery system. We showed that the lyophilization, hot molding process, and sterilization by gamma irradiation did not change drug/polymer physical-chemistry properties. The drug was found to be homogeneously dispersed into the poly lactic-co-glycolic acid (PLGA) chains and the profile release was characterized by an initial burst followed by prolonged release. The drug profile release was not modified after gamma irradiation and non-covalent interaction was found between the drug and the PLGA. We also observed the preservation of the drug activity by showing the potent anti-Toxoplasma effect of the implant, after 24-72 h in contact with cells infected by the parasite, which highlights this system as an alternative to treat toxoplasmic retinochoroiditis.