RESUMEN
Cells infected by Toxoplasma gondii undergo up-regulation of proinflammatory cytokines, organelle redistribution, and protection from apoptosis. During infection in man, the parasite encysts within the retina, a process that results in retinochoroiditis which can lead to permanent loss of sight. The reasons for the parasite to infect retinal tissue and the mechanisms by which it encysts are not clearly understood. We studied the effect of infection with T. gondii of retinal vascular endothelial cells using the Clontech Atlastrade mark array system in order to elucidate changes in gene expression. We compared hybridization of RNA to the array from infected and uninfected cells at two time points; 2 and 24 h. Exposure to T. gondii after 2 h resulted in change of expression of approximately 6% of genes on the array, including those involved in cell structure, protein and vesicle trafficking, cell-cycle regulation, transcriptional and translational machinery, and apoptosis. Among the genes involved in the inflammatory response, chemokine genes such as GRO1 (Growth Regulated Oncogene 1), MCP-1 (Monocyte Chemotactic Protein-1), FKN (Fractalkine) and RANTES (Regulated upon Activation, Normal T Cell Expressed and Secreted) were found to be up-regulated and protein production was confirmed by ELISA. However after 24 h of infection, GRO1, MCP-1 and FKN were down-regulated, confirmed by RT-PCR. Thus, invasion of retinal vascular endothelium (RVE) cells by T. gondii leads to the production of chemokines important in directing the traffic of inflammatory cells to the infected area.
Asunto(s)
Quimiocinas/biosíntesis , Endotelio Vascular/inmunología , Endotelio Vascular/parasitología , Vasos Retinianos/inmunología , Vasos Retinianos/parasitología , Toxoplasma/inmunología , Animales , Línea Celular Transformada , Quimiocina CCL2/biosíntesis , Quimiocina CCL2/genética , Quimiocina CCL5/biosíntesis , Quimiocina CCL5/genética , Quimiocina CX3CL1 , Quimiocina CXCL1 , Quimiocinas/genética , Quimiocinas CX3C/biosíntesis , Quimiocinas CX3C/genética , Quimiocinas CXC/biosíntesis , Quimiocinas CXC/genética , Endotelio Vascular/metabolismo , Ensayo de Inmunoadsorción Enzimática , Perfilación de la Expresión Génica , Péptidos y Proteínas de Señalización Intercelular/biosíntesis , Péptidos y Proteínas de Señalización Intercelular/genética , Proteínas de la Membrana/biosíntesis , Proteínas de la Membrana/genética , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , ARN Mensajero/genética , Ratas , Vasos Retinianos/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Regulación hacia Arriba/inmunologíaRESUMEN
Toxoplasma gondii infection of the eye can result in a recurrent necrotising retinochoroiditis (TR) which may lead to a permanent loss of visual acuity. The mechanisms responsible for the control of TR within the retina are unknown. The aim of this study was to examine the effects of cytokines on the replication of T. gondii RH strain tachyzoites within rat retinal vascular endothelial (rRVE) cells. Pretreatment of rRVE with IFNgamma, TNF or IL-1beta resulted in a significant decrease in T. gondii replication from day 2 onwards. There was no significant difference in nitric oxide (NO) production by IFNgamma, TNF or IL-1beta treated rRVE as compared to controls at any time point. By comparison, the addition of L-tryptophan to IFNgamma treated cultures significantly restored T. gondii replication from 48 h post inoculation. Thus, IFNgamma, TNF and IL-1beta can significantly inhibit the replication of T. gondii within rRVE. However, this inhibition appears to be independent of NO production. L-tryptophan catabolism may have a role in IFNgamma mediated inhibition of T. gondii replication in rRVE cells.