Justus G. Garweg

Comparison of Enzyme-Linked Immunosorbent Assay, Immunoblotting, and PCR for Diagnosis of Toxoplasmic Chorioretinitis

ABSTRACT Ocular toxoplasmosis is the major cause of posterior uvetis in European populations. The clinical diagnosis of toxoplasmic chorioretinitis is based upon ophthalmoscopic findings, which are often but not always typical. Laboratory testing is therefore important to confirm the etiology of the disease. In the present 2-year prospective study, the relative diagnostic sensitivities of the three analytical techniques (enzyme-linked immunosorbent assay [ELISA], immunoblotting, and PCR) were compared by using a group of patients (n = 19) with suspected ocular toxoplasmosis. The relative specificities of the three techniques were assessed by including two control groups of patients: one with nontoxoplasmic and noninflammatory ocular disease (n = 48) and the other with nontoxoplasmic and inflammatory ocular disease (n = 20). All 19 of the clinically suspect patients had serological evidence of exposure to Toxoplasma gondii: 17 had been previously infected, and 2 had current infection. The analysis of paired aqueous humor and serum samples by ELISA and immunoblotting revealed the local production of specific antibodies of the immunoglobulin G type in 63% (12 of 19) and 53% (10 of 19) of patients, respectively. PCR analysis of aqueous humor samples confirmed the presence of T. gondii DNA in 28% (5 of 18) of cases. When combined, ELISA, immunoblotting, and PCR findings confirmed the toxoplasmic origin of retinal lesions in 83% (15 of 18) of patients. The relative specificities of the three techniques were 89% for ELISA and immunoblotting and 100% for PCR.

Cytokine Profiles in Toxoplasmic and Viral Uveitis

BACKGROUND Uveitis is a major cause of visual impairment throughout the world. Analysis of cytokine profiles in aqueous humor specimens may provide insight into the physiopathological processes that underly retinal damage in this context. METHODS Using a multiplex assay, we determined the concentrations of 17 cytokines and chemokines in aqueous humor specimens obtained from patients with ocular toxoplasmosis or viral uveitis and compared these concentrations with those in specimens obtained from patients with noninfectious intermediate uveitis or cataract. RESULTS Five mediators (interleukin [IL]-8, monocyte chemoattractant protein-1, tumor necrosis factor-alpha, IL-4, and IL-10) were detected in >50% of patients in all groups. In contrast, IL-5 and IL-12 were specific for ocular toxoplasmosis, and granulocyte monocyte colony-stimulating factor and IL-1 were specific for viral uveitis; these mediators could present specific markers for diagnostic purposes. Interferon-gamma, IL-6, and macrophage inflammatory protein-1beta were common markers of ocular toxoplasmosis and viral uveitis. IL-17 was a common marker of ocular toxoplasmosis and intermediate uveitis. CONCLUSIONS We found specific cytokine profiles for each type of uveitis, with large interindividual variations and no etiological or clinical correlations. Ocular cytokine mapping contributes to a better understanding of the physiopathology of specific forms of uveitis and provides guidance for new targeted treatment.

Reactivation of ocular toxoplasmosis during pregnancy

We wished to assess whether ocular toxoplasmosis can be reactivated during pregnancy in immunocompetent females, and whether such reactivation is confined to the eye or whether the fetus is exposed to the risk of vertical transmission. For this purpose, we retrospectively examined 18 females with ocular toxoplasmosis during the course of 35 pregnancies. Of these 18 patients, seven developed recurrences during seven pregnancies. Due to the potential risk of functional damage to the mother and the possibility of vertical disease transmission to the fetus, we suggest following such cases carefully during pregnancy until the dimensions of the problem are more fully appreciated.

Ocular manifestations in congenital toxoplasmosis

BackgroundRetinochoroiditis is the most common ocular manifestation of congenital toxoplasmosis, but other associated ophthalmological pathologies can also occur. The aim of this study was to determine the nature of the latter in treated cases of the disease and to assess their impact on visual function.MethodsFour hundred and thirty consecutive children with serologically confirmed congenital toxoplasmosis were included in this study. Data were prospectively collected using standardized ophthalmological assessment forms. The presence of retinochoroiditis and of associated pathologies was ascertained, and their impact on visual function was assessed.ResultsAfter a median follow-up of 12 years [range 0.6–26 years], 130 children manifested retinochoroiditis. We detected 22 foci of retinochoroiditis at birth and 264 additional ones during the follow-up period. Of these, 48 (17%) were active when first diagnosed. Twenty-five of the 130 children (19%) had other associated ocular pathologies. Of these, 21 (16%) had a strabismus, which was due to macular lesions in 86% of the cases; 7 (5.4%) presented with unilateral microphthalmia, and 4 (3%) with cataracts. Most of these events were detected after the onset of retinochoroiditis. None of the children presented with ocular involvement in the absence of chorioretinal lesions. Macular lesions occurred more frequently in children with associated pathologies (p<0.0001), and associated pathologies were likewise more common in individuals with macular lesions (p=0.0003). Visual impairment occurred in 31/130 cases, and in all but 3 of these eyes it was due not to an associated pathology but to macular retinochoroiditis.ConclusionsAt the end of the follow-up period, ocular involvement existed in 30% of the treated children with congenital toxoplasmosis. Associated eye pathologies were manifested less frequently than anticipated. They may occur later in life and are an indirect marker of the severity of congenital toxoplasmosis, but they do not have a direct impact on visual acuity. The overall functional prognosis of congenital toxoplasmosis is better than would be expected on the basis of literature findings, with only 2 of the 130 children suffering bilateral visual impairment.

Prognostic factors for the long-term development of ocular lesions in 327 children with congenital toxoplasmosis.

The aim of this study was to identify the high-risk factors associated with the development of ocular lesions in a large cohort of children with congenital toxoplasmosis (CT), irrespective of their gestational age at the time of maternal infection. Children were managed according to a standardized protocol and monitored for up to 14 years at the Croix-Rousse Hospital, Lyon, France. Cox model and a flexible regression, spline-based method were used for the analysis. During a median follow-up time of 6 years, 79 of the 327 children (24%) had at least one retinochoroidal lesion. No bilateral impairment of visual acuity was observed. The risk of a child developing ocular disease was higher not only when mothers were infected early during pregnancy, which was expected, but also when CT was diagnosed prior to or at the time of birth, when non-ocular manifestations were present at baseline and when birth was premature.

Serotyping of Toxoplasma gondii: striking homogeneous pattern between symptomatic and asymptomatic infections within Europe and South America

Field isolates of Toxoplasma gondii in Europe and North America have been grouped into three clonal lineages that display different virulence in mice. Whether the genetic structure of the parasite is related to clinical expression in humans has not yet been demonstrated. We developed an enzyme-linked immunosorbent assay which uses lineage-specific, polymorphic polypeptides derived from the dense granule antigens, GRA5 and GRA6. Our goal was to compare serotypical patterns observed in asymptomatic versus symptomatic (ocular disease and severe infection in human immunodeficiency virus (HIV)-positive patients) infections among patients from Europe and South America. Independent of the clinical presentation of the disease, serotypes differed according to geographical origin, with a homogeneous distribution of serotype II in Europe and of serotypes I and III in South America. We conclude that GRA5-GRA6 serotyping is an interesting tool to study serotype prevalence in populations but it is not an accurate marker of pathogenicity of Toxoplasma infection in humans.

Pathophysiology of Proliferative Vitreoretinopathy in Retinal Detachment

Because proliferative vitreoretinopathy cannot be effectively treated, its prevention is indispensable for the success of surgery for retinal detachment. The elaboration of preventive and therapeutic strategies depends upon the identification of patients who are genetically predisposed to develop the disease, as well as upon an understanding of the biological process involved and the role of local factors, such as the status of the uveovascular barrier. Detachment of the retina or vitreous activates glia to release cytokines and ATP, which not only protect the neuroretina but also promote inflammation, retinal ischemia, cell proliferation, and tissue remodeling. The vitreal microenvironment favors cellular de-differentiation and proliferation of cells with nonspecific nutritional requirements. This may render a pharmacological inhibition of their growth difficult without causing damage to the pharmacologically vulnerable neuroretina. Moreover, reattachment of the retina relies upon the local induction of a controlled wound-healing response involving macrophages and proliferating glia. Hence, the functional outcome of proliferative vitreoretinopathy will be determined by the equilibrium established between protective and destructive repair mechanisms, which will be influenced by the location and the degree of damage to the photoreceptor cells that is induced by peri-retinal gliosis.

Long-term impact of treated congenital toxoplasmosis on quality of life and visual performance.

Background: Long-term evolution of congenital toxoplasmosis is not documented. We assessed the outcome of treated congenital toxoplasmosis in a cohort of adult individuals who had undergone ante- and postnatal treatment to provide information for pediatricians and parents on the evolution of the disease. Methods: We conducted a questionnaire study on 126 adults with congenital toxoplasmosis (mean age: 22.2 years; age range: 18–31 years) monitored regularly until the time of inclusion. The main outcome measures were quality of life (Psychological General Well-Being Index) and visual function (VF14 questionnaire), and the outcomes were correlated with disease-specific factors. Results: Of the 102 patients (80.9%) who were finally included in the study, 12 (11.8%) presented neurologic effects and 60 (58.8%) manifested ocular lesions; in the latter category, 13 individuals (12.7%) had reduced visual function. The overall global quality-of-life score (74.7 ± 14.2) was close to the expected normal range for the general population (73.7 ± 15.3). Overall, visual function was only slightly impaired (M = 97.3; 95% confidence interval, 95.8–98.8). Although disease-independent critical life circumstances were associated with a reduced Psychological General Well-Being Index, this index was not influenced by any of the clinical characteristics of congenital toxoplasmosis. Neurologic pathologies, reduced visual acuity, foveal location of the retinal lesion, and squinting contributed to decreased visual function at follow-up. Conclusions: Our data reveal that treated congenital toxoplasmosis has little effect on the quality of life and visual function of the affected individuals. These encouraging findings may help to alleviate the anxiety of affected individuals and their parents.

Prognostic factors of liver metastases from uveal melanoma

ObjectivesThis study was designed to assess survival and identify prognostic factors for liver metastases diagnosed by systematic screening in uveal melanoma patients.MethodsAmong 602 consecutive patients treated over 10 years for uveal melanoma and followed by systematic semi-annual hepatic screening (abdominal ultrasonography), 63 (10.5%) developed liver metastases; these patients form the basis of this study. Factors including patient demographics, characteristics of the uveal tumor, metastasis-free interval, severity of liver metastatic involvement, and treatments of metastases were studied retrospectively regarding their prognostic value, using univariate (Kaplan-Meier method) and multivariate (Cox model) analyses.ResultsThirty-five patients (55.6% of the metastatic population) received systemic chemotherapy or best supportive care only; 14 patients (22.2% of the metastatic population) diagnosed with diffuse liver involvement had cytoreductive surgery and intra-arterial chemotherapy; 14 (22.2% of the metastatic population) had complete surgical removal of liver metastases followed by postoperative intra-arterial chemotherapy. No significant surgical complications were experienced. The median overall survival after diagnosis of liver metastases was 15 months. It reached 25 months for selected patients with complete resection (P=0.0002). In this cohort of 63 patients, ten or fewer preoperatively diagnosed metastases and primary uveal melanoma not involving the ciliary body were independently associated with better prognosis.ConclusionsThis study suggests that selected patients with screened liver metastases from uveal melanoma may benefit from aggressive treatment, including surgery. The two independent favorable prognostic factors are fewer than ten metastases at screening and the absence of ciliary body involvement.

Immunopathology in ocular toxoplasmosis: facts and clues

Although parasite-mediated host cell lysis is deemed to be an important cause of tissue destruction in ocular toxoplasmosis (OT), the severity of the disease is probably correlated with hypersensitivity and inflammation. Notwithstanding, the mechanisms that regulate the inflammatory process in recurrent OT are poorly understood. Recent evidence has identified interleukin (IL) 17 as a marker for disease severity. The ocular and cerebral presence of this cytokine is generally associated with the induction of autoimmune responses in the brain and the eye. Indeed, there are indications that autoimmunity may contribute to clinical variability in the activity of OT. IL-23, which induces the proliferation of IL-17-producing cells and IL-27, which is a counterplayer to IL-17, may regulate T(H)-1-cell-mediated responses in OT. The importance of these cytokines in experimental models of uveitis and encephalitis has been recently reported. CD25(+) regulatory T-cells may control the local inflammatory response and protect the host against collateral inflammatory tissue damage. The responses of these cells to OT may be suitably tailored to cope with either an acquired or a congenital aetiology. Knowledge relating to immunoreactivity in OT has grown impressively during the past few years. Its characteristic and variable features have been identified and the potential relevance of autoimmunity has been assessed. In light of this knowledge, potential future treatment options have been considered.