Ocular toxoplasmosis: an update and review of the literature

Ocular toxoplasmosis is the most common cause of posterior uveitis worldwide. The infection can be acquired congenitally or postnatally and ocular lesions may present during or years after the acute infection occur. Current treatment controls ocular infection and inflammation, but does not prevent recurrences. We present a review and update on ocular toxoplasmosis and address misconceptions still found in the current medical literature.Universidade Federal de São Paulo (UNIFESP) Instituto da VisãoMcGill University Henry C Witelson Ocular Pathology LaboratoryAlbert Einstein Jewish Institute for Education and ResearchClínica SilveiraUNIFESP, Instituto da VisãoSciEL

Direct fluorescent antibody assay and polymerase chain reaction for the detection of Chlamydia trachomatis in patients with vernal keratoconjunctivitis

OBJECTIVES: To identify Chlamydia trachomatis via polymerase chain reaction and a direct fluorescent antibodyassay in patients with vernal keratoconjunctivitis while comparing the efficacies of both tests for detectingChlamydia trachomatis in these conditions. METHODS: Conjunctival scraping samples were obtained from 177 patients who were divided into two groups: avernal keratoconjunctivitis group (group A) and a control group (group B). The polymerase chain reaction and adirect fluorescent antibody assay were performed. Sensitivity, specificity, receiver operating characteristic curves,and areas under the curve were calculated for both tests in groups A and B. Receiver operating characteristic curveswere plotted using a categorical variable with only two possible outcomes (positive and negative). RESULTS: Statistical analysis revealed a significant association between vernal keratoconjunctivitis and Chlamydia trachomatis infection detected by a direct fluorescent antibody assay with high sensitivity and specificity. Allpatients in group A with positive polymerase chain reactions also presented with positive direct fluorescentantibody assays. CONCLUSION: The association between vernal keratoconjunctivitis and Chlamydia trachomatis infection wasconfirmed by positive direct fluorescent antibody assays in 49.4% of vernal keratoconjunctivitis patients and bypositive polymerase chain reactions in 20% of these patients. The direct fluorescent antibody assay detectedChlamydia trachomatis in a higher number of patients than did the polymerase chain reaction. Although thediagnosis of trachoma is essentially clinical, the disease may not be detected in vernal keratoconjunctivitis patients.Due to the high frequency of chlamydial infection detected in patients with vernal keratoconjunctivitis, we suggestconsidering routine laboratory tests to detect Chlamydia trachomatis in patients with severe and refractory allergicdisease

Imatinib mesylate alters the expression of genes related to disease progression in an animal model of uveal melanoma

Imatinib mesylate (IM) is a compound that inhibits both BCR-ABL tyrosine kinase and c-kit receptors. Tyrosine kinases are important in cellular signaling and mediate major cellular processes such as proliferation, differentiation, apoptosis, attachment, and migration. Twenty-six albino rabbits were injected with 1 x 10(6) human uveal melanoma (UM) cells (92.1) into the suprachoroidal space. Animals were immunosuppressed (cyclosporin A) over the course of the 12-week experiment and divided into two groups (n = 13). the experimental group received IM once daily by gavage while the control group received a placebo. One animal per group was sacrificed every week after the 2nd week. Upon necropsy, organs were harvested for histopathological examination. Cells from the primary tumors were recultured and tested in proliferation and invasion assays. A PCR array was used to investigate the differences in expression of 84 genes related to tumor metastasis. in the treated group, 4 rabbits developed intraocular tumors, with an average largest tumor dimension (LTD) of 2.5 mm and 5 animals reported metastatic disease. Whereas 6 rabbits in the control group developed intraocular tumors, with an average LTD of 5.8 mm and 6 animals reported metastatic disease. the recultured cells from the treated group demonstrated lower proliferation rates and were less invasive (p < 0.001). the PCR array showed differences in expression of genes related to metastasis. Notably, there was 290-fold increase in SERPINB5, a tumor suppressor gene, and a 10-fold higher expression of KISS I, a metastasis suppressor gene, in the treated group. Proangiogenic genes such as VEGFA, PDGFA and PDGFB were downregulated in the treated group. To the best of our knowledge, this is the first report detailing the altered expression of specific genes in UM cells after treatment with IM.McGill Univ, Ctr Hlth, Dept Ophthalmol & Pathol, Montreal, PQ, CanadaHenry C Witelson Ocular Pathol Lab, Montreal, PQ, CanadaUniversidade Federal de São Paulo UNIFESP EPM, Dept Ophthalmol, São Paulo, BrazilUniversidade Federal de São Paulo UNIFESP EPM, Dept Ophthalmol, São Paulo, BrazilWeb of Scienc

Discrimination between patients with acquired toxoplasmosis and congenital toxoplasmosis on the basis of the immune response to parasite antigens

Many persons infected with Toxoplasma gondii develop ocular lesions, Immunologic parameters in the response to I gondii were evaluated in infected persons with and without ocular lesions and in noninfected controls. Subjects were divided into groups on the basis of presence of serum antibodies to I: gondii, presence of ocular lesions, and clinical history. Production of interleukin-2 and interferon-gamma by peripheral blood mononuclear cells from patients with probable congenital toxoplasmosis was decreased, compared with that in persons with presumed acquired infection. Cell proliferation and delayed-type skin reaction induced by soluble toxoplasma tachyzoite antigen followed the same pattern. Asymptomatic persons showed high levels of interleukin-12 and interferon-gamma, whereas persons with ocular lesions had high interleukin-1 and tumor necrosis factor-alpha responses toward soluble toxoplasma tachyzoite antigen. These data suggest that patients with ocular disease due to congenital infection show tolerance toward the parasite. Furthermore, susceptibility to ocular lesions after acquired toxoplasmosis is associated with high levels of interleukin-1 and tumor necrosis factor-alpha, whereas resistance is associated with high levels of interleukin-12 and interferon-gamma.Univ São Paulo, ICB, Dept Immunol, BR-05509890 São Paulo, BrazilUniv São Paulo, Inst Heart, Lab Transplant Immunol, São Paulo, BrazilUniv São Paulo, Fac Med, Dept Ophthalmol, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Ophthalmol, São Paulo, BrazilUniv São Paulo, Sch Med, Div Clin Immunol & Allergy, Lab Med Invest, São Paulo, BrazilFundacao EJ Zerbini, São Paulo, BrazilUniv Fed Minas Gerais, Dept Biochem & Immunol, Belo Horizonte, MG, BrazilFundacao Osvaldo Cruz, Ctr Pesquisas Rene Rachou, Belo Horizonte, MG, BrazilNEI, Immunol Lab, NIH, Bethesda, MD 20892 USAUniversidade Federal de São Paulo, Dept Ophthalmol, São Paulo, BrazilWeb of Scienc

Toxoplasma gondii detection in peripheral blood of patients with ocular toxoplasmosis using and comparing immunohistochemistry and PCR

Os mecanismos envolvidos na gravidade e recorrencia da toxoplasmose ocular ainda nao sao bem entendidos. Novos metodos diagnosticos, como a identificacao de parasitas eventualmente circulantes, sao necessarios para diagnosticar casos atipicos e entender melhor os mecanismos de recorrencia. Objetivo: Deteccao do Toxoplasma gondii no sangue periferico de pacientes com diferentes tipos de uveites utilizando as tecnicas de imunohistoquimica e reacao em cadeia da polimerase. Material e metodo: Pacientes com diferentes tipos de uveites e voluntarios saudaveis tiveram 20ml de sangue periferico retirado e seu DNA extraido em ate seis horas da venoclise e armazenado em papel FTA ou congelado. Cepa YFP RH de T. gondii foi cultivado em camada de fibroblastos por 5 semanas. Microscopio de fluorescencia foi usado para determinar a concentracao dos parasitas em suspensao e diluicoes seriadas foram realizadas: de 106 a 100 parasitas por mililitro. Cytospins e esfregaco de sangue total receberam solucao contendo parasitas em diferentes concentracoes e foram submetidos a imunohistoquimica automatizada. Amostras de sangue com diferentes concentracoes de parasitas tiveram seu DNA extraido e foram submetidas a reacao em cadeia da polimerase utilizando dois alvos: um fragmento de 62bp do gene B1 e o fragmento 529bp. Os primers utilizados foram: B1 Forward 5Æ- CTA GTA TCG GTG CGG CAA TGT -3Æe Reverse 5Æ- GGC AGC GTC TCT TCC TCT TTT -3Æ e 529 CGC TGC AGG GAG GAA GAC GAA AGT TG- 3Æ e reverse 5´- CGC TGC AGA CAC AGT GCA TCT GAA TT- 3Æ. Apos a determinacao da tecnica de melhor sensibilidade foram analisadas as amostras de pacientes com diferentes tipos de uveites. Os testes foram realizados em triplicata. Resultados: A reacao de PCR em tempo real foi mais sensivel do que a tecnica de imunohistoquimica para identificar parasitas em sangue periferico. Ao utilizar o fragmento 529bp como alvo obteve-se maior sensibilidade do que ao utilizar o gene B1 como alvo, identificando concentracao de 1 toxo/ml. Foram analisados 32 pacientes, sendo que em duas amostras foi observado resultado positivo da reacao em cadeia da polimerase T. gondii. Estes dois pacientes apresentavam uveites autoimunes, sorologia positiva para toxoplasmose e recebiam medicacao imunossupressora. Conclusoes: A tecnica de imunohistoquimica foi capaz de identificar a presenca de T. gondii no sangue periferico, mas a tecnica de PCR em tempo real apresentou sensibilidade maior. O PCR utilizando o fragmento 529bp como alvo foi mais sensivel do que o PCR utilizando o gene B1 como alvo, provavelmente pelo maior numero de copias no DNA do parasita do fragmento 529 em relacao ao gene B1. Dentre os pacientes estudados, apenas aqueles que recebiam medicacao imunossupressora apresentaram parasitas circulando no sangue perifericoBV UNIFESP: Teses e dissertaçõe

Use of CD25 as an immunohistochemical marker for acquired ocular toxoplasmosis

PURPOSE: Toxoplasmosis is the most common cause of posterior infectious uveitis worldwide. It is often impossible to determine its congenital or acquired nature. Interleukin-2 (IL-2) in peripheral blood has been described as a possible marker for acquired toxoplasmosis. The purpose of this study is to evaluate the histopathological characteristics of ocular toxoplasmosis cases using CD25 as a marker for the expression of interleukin-2. METHODS: Ten formalin-fixed, paraffin-embedded enucleated globes from ten immunocompetent patients with clinical diagnosis of toxoplasmosis were evaluated. Four patients had the acquired form of ocular toxoplasmosis (positive IgM) while six were IgM negative and IgG positive for toxoplasmosis. Histopathological slides were reviewed for the extension of the retinal necrosis, number of toxo cysts, the granulomatous inflammatory reaction, the presence of T and B cells within the choroid and the IL-2 expression. Immunohistochemistry using monoclonal antibodies was performed to observe the expression of CD4, CD8, CD20, CD25, and CD68. RESULTS: The histopathological evaluation disclosed no differences between acquired and the other ocular toxoplasmosis cases regarding the characteristics studied. However, CD25 showed a higher expression of IL-2 on the 4 acquired cases of ocular toxoplasmosis compared to the remainders. CONCLUSIONS: To the best of our knowledge, this is the first report showing that the use of CD25 as a marker for interleukin-2 could differentiate acquired ocular toxoplasmosis