Toxoplasma gondii is the most common cause of retinochoroiditis in the world. Ocular toxoplasmosis relapses despite the use of antibiotics and remains an important cause of loss of visual acuity especially in children with congenital infection as well as the elderly and the immunosuppressed. Unfortunately, our understanding of the mechanisms of protection against ocular toxoplasmosis is fragmentary. Macrophages, microglia and T cells are the major components of the cell infiltrates in ocular toxoplasmosis. An important event in the interaction between these cells is the stimulation of CD40 expressed on macrophages/microglia. We identified a new paradigm by which the immune system through CD40 kills T. gondii. CD40 induces toxoplasmacidal activity in macrophages and retinal microglia. This is dependent on autophagy, a process that targets the parasite to lysosomal degradation. This finding is likely key to ocular toxoplasmosis because in vivo control of this disease requires CD40. Thus, studying the regulation of CD40-induced autophagy will likely identify new molecular targets for eradication of T. gondii and for therapy of ocular toxoplasmosis that will hopefully prevent relapse of this disease. The objective of this application is to understand how CD40 signaling in macrophages and retinal microglia controls ocular toxoplasmosis and how T. gondii subverts these signals. The central hypothesis for the proposed research is that, CD40 mediates resistance against toxoplasmosis in the eye through protein kinase activation and induction of autophagy. In contrast, T. gondii and cytokines triggered by the parasite use a strategy to impair the signaling needed for optimal activation of autophagy allowing the parasite to evade eradication. This hypothesis will be tested using immunochemical studies as well as genetic approaches that block specific vesicular trafficking molecules. In the first specific aim we will determine if autophagy and protein kinase activation induced by CD40 mediate resistance to ocular toxoplasmosis. In the second aim, we will identify the intracellular events by which cytokines prevent optimal induction of autophagy and test whether inhibition of these events improves control of ocular toxoplasmosis. The proposed work may lead to new strategies to eradicate T. gondii and treat ocular toxoplasmosis based on modulation autophagy and/or CD40 signaling.
Toxoplasmosis of the eye is a relapsing disease and a major cause of visual loss. Currently available therapeutic regimens do not prevent relapse of this disease. We plan studies that will hopefully identify molecules that can be used to boost the ability of the immune system to control ocular toxoplasmosis.
| Liu, Elizabeth; Van Grol, Jennifer; Subauste, Carlos S (2015) Atg5 but not Atg7 in dendritic cells enhances IL-2 and IFN-? production by Toxoplasma gondii-reactive CD4+ T cells. Microbes Infect 17:275-84 |
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| Chen, Yu; Sawada, Osamu; Kohno, Hideo et al. (2013) Autophagy protects the retina from light-induced degeneration. J Biol Chem 288:7506-18 |
| Muniz-Feliciano, Luis; Van Grol, Jennifer; Portillo, Jose-Andres C et al. (2013) Toxoplasma gondii-induced activation of EGFR prevents autophagy protein-mediated killing of the parasite. PLoS Pathog 9:e1003809 |
| Van Grol, Jennifer; Muniz-Feliciano, Luis; Portillo, Jose-Andres C et al. (2013) CD40 induces anti-Toxoplasma gondii activity in nonhematopoietic cells dependent on autophagy proteins. Infect Immun 81:2002-11 |
| Portillo, Jose-Andres C; Feliciano, Luis Muniz; Okenka, Genevieve et al. (2012) CD40 and tumour necrosis factor-? co-operate to up-regulate inducuble nitric oxide synthase expression in macrophages. Immunology 135:140-50 |
| Subauste, Carlos (2012) Animal models for Toxoplasma gondii infection. Curr Protoc Immunol Chapter 19:Unit 19.3.1-23 |
| Subauste, Carlos S; Ajzenberg, Daniel; Kijlstra, Aize (2011) Review of the series ""Disease of the year 2011: toxoplasmosis"" pathophysiology of toxoplasmosis. Ocul Immunol Inflamm 19:297-306 |
| Tu, Zhidan; Portillo, Jose-Andres C; Howell, Scott et al. (2011) Photoreceptor cells constitutively express functional TLR4. J Neuroimmunol 230:183-7 |
| Van Grol, Jennifer; Subauste, Cecilia; Andrade, Rosa M et al. (2010) HIV-1 inhibits autophagy in bystander macrophage/monocytic cells through Src-Akt and STAT3. PLoS One 5:e11733 |
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