Cynthia Azeredo Cordeiro

Transcriptional Analysis of Murine Macrophages Infected with Different Toxoplasma Strains Identifies Novel Regulation of Host Signaling Pathways

Most isolates of Toxoplasma from Europe and North America fall into one of three genetically distinct clonal lineages, the type I, II and III lineages. However, in South America these strains are rarely isolated and instead a great variety of other strains are found. T. gondii strains differ widely in a number of phenotypes in mice, such as virulence, persistence, oral infectivity, migratory capacity, induction of cytokine expression and modulation of host gene expression. The outcome of toxoplasmosis in patients is also variable and we hypothesize that, besides host and environmental factors, the genotype of the parasite strain plays a major role. The molecular basis for these differences in pathogenesis, especially in strains other than the clonal lineages, remains largely unexplored. Macrophages play an essential role in the early immune response against T. gondii and are also the cell type preferentially infected in vivo. To determine if non-canonical Toxoplasma strains have unique interactions with the host cell, we infected murine macrophages with 29 different Toxoplasma strains, representing global diversity, and used RNA-sequencing to determine host and parasite transcriptomes. We identified large differences between strains in the expression level of known parasite effectors and large chromosomal structural variation in some strains. We also identified novel strain-specifically regulated host pathways, including the regulation of the type I interferon response by some atypical strains. IFNβ production by infected cells was associated with parasite killing, independent of interferon gamma activation, and dependent on endosomal Toll-like receptors in macrophages and the cytoplasmic receptor retinoic acid-inducible gene 1 (RIG-I) in fibroblasts.

Interleukin-10 Gene Polymorphism (-1082G/A) is Associated with Toxoplasmic Retinochoroiditis

PURPOSE Experimental data have demonstrated a relevant role for IL-10, an anti-inflammatory cytokine, in the modulation of acute ocular toxoplasmosis. Therefore, this study was conducted to investigate the possible association between an IL10 gene polymorphism at position -1082 and toxoplasmic retinochoroiditis (TR) in humans. METHODS One hundred patients with diagnosed TR were recruited from the Uveitis Section, Federal University of Minas Gerais. For comparison, one hundred healthy blood donors with positive serology for toxoplasmosis and without retinal signs of previous TR were included in the study. Genomic DNA was obtained from oral swabs of individuals and amplified using polymerase chain reaction (PCR) with specific primers flanking the locus -1082 of IL10 (-1082G/A). PCR products were subjected to restriction endonuclease digestion and analyzed by polyacrylamide gel electrophoresis, to distinguish allele G and A of the IL-10 gene, allowing the detection of the polymorphism and determination of genotypes. RESULTS There was a significant difference in the genotype distribution between TR patients and control subjects (chi(2) = 6.33, P = 0.04). Carriers of the IL10 -1082 A allele (AA+AG genotypes) were more often patients with TR than control subjects (chi(2) = 5.97, P = 0.01, OR, 2.55; 95% CI, 1.11 < OR < 5.55). In a subgroup analysis, there was no significant difference in genotypes and allele carriage regarding visual acuity, involvement of both eyes and TR recurrence. CONCLUSIONS This study suggests that the genotypes related with a low production of IL-10 may be associated with the occurrence of TR.

Toxoplasma gondii Superinfection and Virulence during Secondary Infection Correlate with the Exact ROP5/ROP18 Allelic Combination

ABSTRACT The intracellular parasite Toxoplasma gondii infects a wide variety of vertebrate species globally. Infection in most hosts causes a lifelong chronic infection and generates immunological memory responses that protect the host against new infections. In regions where the organism is endemic, multiple exposures to T. gondii likely occur with great frequency, yet little is known about the interaction between a chronically infected host and the parasite strains from these areas. A widely used model to explore secondary infection entails challenge of chronically infected or vaccinated mice with the highly virulent type I RH strain. Here, we show that although vaccinated or chronically infected C57BL/6 mice are protected against the type I RH strain, they are not protected against challenge with most strains prevalent in South America or another type I strain, GT1. Genetic and genomic analyses implicated the parasite-secreted rhoptry effectors ROP5 and ROP18, which antagonize the hosts gamma interferon-induced immunity-regulated GTPases (IRGs), as primary requirements for virulence during secondary infection. ROP5 and ROP18 promoted parasite superinfection in the brains of challenged survivors. We hypothesize that superinfection may be an important mechanism to generate T. gondii strain diversity, simply because two parasite strains would be present in a single meal consumed by the feline definitive host. Superinfection may drive the genetic diversity of Toxoplasma strains in South America, where most isolates are IRG resistant, compared to North America, where most strains are IRG susceptible and are derived from a few clonal lineages. In summary, ROP5 and ROP18 promote Toxoplasma virulence during reinfection. IMPORTANCE Toxoplasma gondii is a widespread parasite of warm-blooded animals and currently infects one-third of the human population. A long-standing assumption in the field is that prior exposure to this parasite protects the host from subsequent reexposure, due to the generation of protective immunological memory. However, this assumption is based on clinical data and mouse models that analyze infections with strains common to Europe infections with strains common to Europe and North America. In contrast, we found that the majority of strains sampled from around the world, in particular those from South America, were able to kill or reinfect the brains of hosts previously exposed to T. gondii. The T. gondii virulence factors ROP5 and ROP18, which inhibit key host effectors that mediate parasite killing, were required for these phenotypes. We speculate that these results underpin clinical observations that pregnant women previously exposed to Toxoplasma can develop congenital infection upon reexposure to South American strains. Toxoplasma gondii is a widespread parasite of warm-blooded animals and currently infects one-third of the human population. A long-standing assumption in the field is that prior exposure to this parasite protects the host from subsequent reexposure, due to the generation of protective immunological memory. However, this assumption is based on clinical data and mouse models that analyze infections with strains common to Europe and North America. In contrast, we found that the majority of strains sampled from around the world, in particular those from South America, were able to kill or reinfect the brains of hosts previously exposed to T. gondii. The T. gondii virulence factors ROP5 and ROP18, which inhibit key host effectors that mediate parasite killing, were required for these phenotypes. We speculate that these results underpin clinical observations that pregnant women previously exposed to Toxoplasma can develop congenital infection upon reexposure to South American strains.

Interleukin-6 gene polymorphism (-174 G/C) is associated with toxoplasmic retinochoroiditis.

Purpose:  Experimental data have demonstrated a relevant role for IL‐6 in the modulation of acute ocular toxoplasmosis. Therefore, we aim to investigate the possible association between the IL‐6 gene polymorphism at position ‐174 and toxoplasmic retinochoroiditis (TR) in humans.

Córnea verticilata - marcador clínico da doença de Fabry: relato de caso

Fabrys disease is a rare X-linked lisosomal storage disorder of glycosphingolipid (GL) metabolism, caused by a deficiency of a-galactosidase A activity. The progressive accumulation of GL in tissues results in the clinical manifestations of the disease, that are more evident in hemizygous males, and include angiokeratomas, acroparesthesia, cornea verticillata, cardiac and kidney involvement, cerebrovascular manifestations. A family with Fabrys disease including 2 female patients and 3 male patients is reported. The patients were submitted to complete medical history, ophthalmological examination and alpha-galactosidase activity test. Cornea verticillata was a constant finding in all patients. This demonstrates the important role of the ophtalmological examination for the diagnosis of Fabrys disease since the eye findings are so characteristic of the disease.

Increased serum levels of soluble tumor necrosis factor receptor-2 (sTNFR2) in patients with active toxoplasmic retinochoroiditis

This study aimed to investigate the serum levels of the cytokine TNF-α and its soluble receptors (sTNFR1 and sTNFR2) in patients with toxoplasmosis retinochoroiditis (TR) and controls. 37 patients with TR and 30 subjects with positive serology for toxoplasmosis but without history and signs of uveitis were included in this study. Serum concentrations of TNF-α, sTNFR1, and sTNFR2 were determined by ELISA. Serum concentrations of TNF-α and sTNFR1 were similar in controls (mean ± SD median values; 56.57±141.96 and 504.37±163.87, respectively) and TR patients (mean ± SD values, 121.62±217.56 and 511.15±189.30, respectively). Serum concentrations of sTNFR2 were higher in the uveitis group when compared to the control group (respectively, mean ± SD values, 1734.84±379.32 and 1442.75±309.47; p=0.002). There was no association between the serum levels of the molecules and the time of first symptoms, severity of vitreous haze, size or localization of active lesions, levels of visual acuity, and presence of vasculitis. These results suggest that TR is associated with changes in the circulating levels of inflammatory biomarkers, but they are not correlated with local/ocular signs.

Imunogenética das uveítes

Cytokines are molecules involved in intercellular communication in immune and inflammatory responses, playing an important role in uveitis. Genetic polymorphisms responsible for the production of certain cytokines have been associated with the occurrence and the severity of uveitis. Therefore, the present study has the purpose of describing these possible associations, pointing out the individual genetic background in the prognosis of uveitis.

Serum levels of neurotrophic factors in active toxoplasmic retinochoroiditis

Toxoplasmic retinochoroiditis (TR) is the most common identifiable cause of posterior uveitis in Brazil. Response to treatment and clinical presentation may vary significantly. We assessed serum levels of brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), nerve growth factor (NGF), neurotrophin (NT)-3, and NT-4/5 in patients with active TR, before and after TR treatment. METHODS Twenty patients with active lesion and 15 healthy controls were enrolled in the study. Serum concentration of neurotrophic factors was determined by enzyme-linked immunosorbent assay. RESULTS BDNF levels were significantly higher in patients before treatment when compared with controls (p=0.0015). There was no significant difference in pro-BDNF, NGF, GDNF, NT-3, and NT-4/5 levels between TR patients and controls. Treatment did not affect the levels of these factors. CONCLUSION BDNF may be released in the context of the active TR inflammatory response.