Secretion of multi-protein migratory complex induced by Toxoplasma gondii infection in macrophages involves the uPA/uPAR activation system.

Toxoplasmosis is a world wide spread zoonosis caused by Toxoplasma gondii, an obligate intracellular parasite that is able to disseminate into deep tissues and cross biological barriers, reaching immunoprivileged sites such as the brain and retina. The parasite is able to infect macrophages and dendritic cells for dispersal throughout the body. However, the molecular mechanisms or outcomes of the subversion of the host cell are largely unknown. Recently our group established that metalloproteinases are involved in migration of infected macrophages. Herein, we evaluated the recruitment of host invasive machinery components in T. gondii infected murine macrophages. We showed by immunoprecipitation assays that MMP-9, CD44 TIMP-1 and uPAR were secreted as a multi-protein complex by infected macrophages. Zymographic analysis revealed that MMP-9 was present in its pro- and active form. Moreover, inhibition of uPA/uPAR pathway by PAI-1 decreased secretion of MMP-9 active forms, as well those associated to uPAR and TIMP-1, but not to CD44. Data presented here suggest that MMP-9 is secreted as a multiprotein complex by T. gondii infected macrophages, similar to that observed in metastatic cells. We further speculate that uPA/uPAR system is involved in the expression/secretion of complexes containing active MMP-9 forms.

Toxoplasma gondii infection positively modulates the macrophages migratory molecular complex by increasing matrix metalloproteinases, CD44 and alpha v beta 3 integrin.

Toxoplasmosis is a world wide spread zoonosis caused by Toxoplasma gondii, an obligate intracellular parasite that is able to disseminate into deep tissues and cross biological barriers, reaching immunoprivileged sites such as the brain and retina. The parasite is able to infect macrophages and dendritic cells for dispersal throughout the body. However, the molecular principals or outcomes of the subversion of the host cell are largely unknown. We evaluated the involvement of host invasive machinery in the migration of T. gondii infected murine cells from a monocytic/macrophage lineage. Migration in Matrigel of infected macrophages was augmented after 48 h of infection, and inhibition of metalloproteinases abolished migration. We also demonstrated that T. gondii infection induces a decreasing of CD44 at cell surface independent of the ERK signaling pathway, and that secretion of active MMP9 is augmented upon infection. Infected macrophages showed increased expression of MT1-MMP and ADAM10 membrane matrix metalloproteinases. Furthermore, processing of pro-alpha v and pro-beta 3 in T. gondii infected cells seems to depend on metalloproteinases to generate functional mature integrin alpha v beta 3 molecules, with no evidence of the involvement of proprotein convertase pathway.

Monocytes/macrophages infected with Toxoplasma gondii do not increase co-stimulatory molecules while maintaining their migratory ability.

Toxoplasma gondii is an obligate intracellular parasite that is able to disseminate into deep tissues and cross biological barriers, reaching immunoprivileged sites such as the brain and retina. The parasite is able to infect macrophages and dendritic cells and use them for dispersal throughout the body, but the activation state of those cells is unknown. We investigated the ability of human and murine cells from monocytic/macrophage lineages that had not previously been exposed to inflammatory cytokines to up-regulate co-stimulatory and adhesion molecules upon infection. Toxoplasma gondii-infected human monocytes (freshly isolated and THP1 lineage) were unable to up-regulate CD86, CD83, CD40 or CD1a. CD80 expression increased in infected cells but expression of l-selectin and beta2 integrin was unaltered. We evaluated the ability of infected macrophages from wild type C57/BL/6 or CD14(-/-) mice to migrate in 8 mum transwells. Infected cells from CD14(-/-) mice were more likely to de-adhere than infected cells from wild type mice but they did not show any increase in migratory ability. The non-stimulatory profile of these infected cells may contribute to parasite spread throughout the lymphatic circulation in the initial phases of infection.