Ocular toxoplasmosis in Iran: 40 cases analysis

The role of age in ocular toxoplasmosis: clinical signs of immunosenescence and inflammaging

Purpose

This study aimed to investigate the association between age, immune response, and clinical presentation of ocular toxoplasmosis (OT).

Design

This was a monocentric, retrospective, observational cohort study.

Methods

A review of the medical records of patients with active OT at the Uveitis Center, Charité Universitätsmedizin, was conducted. Baseline parameters included age at presentation, visual acuity, intraocular pressure (IOP), size and location of active lesions, inflammatory activity, antibody index (AI), and complications of intraocular inflammation. The data were presented as the mean ± standard deviation (SD). The level of significance was set at a p-value of <0.05.

Results

Between 1998 and 2019, 290 patients with active OT were diagnosed at our tertiary reference center. The mean age of the participants was 37.7 ± 17.1 years, 53.8% of them were female individuals, and 195 patients (70.9%) showed recurrent disease. Older age was associated with lower baseline visual acuity (p = 0.043), poor visual outcome (p = 0.019), increased inflammatory activity (p < 0.005), and larger retinal lesions (p < 0.005). Older patients presented a lower AI (<35 years: 45.1 ± 82.7, median: 12.1; ≥35 years: 18.6 ± 50.5, median: 5.8; p = 0.046), confirmed by a decrease in AI with increasing age (R2 = 0.045; p = 0.024). Finally, AI was correlated with lesion size (multiple linear regression analysis: p = 0.043). Macular involvement (24.3% of patients) was positively correlated with complications (macular/peripapillary edema and retinal detachment, p < 0.005) and poor visual outcome (p < 0.005) and was negatively correlated with inflammatory activity (p < 0.005).

Conclusion

We found a strong and clinically relevant impact of age on the clinical presentation and course of OT. While an unspecific inflammatory response increased with age, the specific, local humoral immune response declined. These findings are well in line with the concept of immunosenescence and inflammaging in uveitis.

The Decreased Treg Cells Number Associated with Retinal Lesion Size in Ocular Toxoplasmosis

Introduction

The imbalance of the immune response is an important factor contributing to the incidence of ocular toxoplasmosis (OT). Regulatory T cells (Treg) play a key role in maintaining the balance between Th1 and Th17 immune responses, while interleukin-27 (IL-27) levels are related to the differentiation of Th17 cells. This study analyzes the differences in the number of Treg cells and the level of IL-27 between OT patients and seropositive individuals without ocular lesions and its correlation with retinal lesion size.

Methods

This analytic observational study, conducted for 8 months, involved 11 OT patients and 10 seropositive individuals without ocular lesions. All subjects underwent a comprehensive ophthalmological examination. Retinal lesions were documented by fundus photographs and the size was measured using Digimizer 4.2.2.0 software. Isolation of peripheral blood mononuclear cells (PBMC) was performed to measure the number of Treg cells using flow cytometry and interleukin-27 levels were assessed using the Sandwich enzyme-linked immunosorbent assay (ELISA) technique. Data were analyzed with SPSS.

Result

The number of Treg cells in the OT group (47.16 ± 15.66%) was lower than in the seropositive group without the ocular lesions (62.86 ± 17.08%) (p = 0.029). The serum IL-27 levels in the OT group were not significantly different from the seropositive group without the ocular lesions (p = 0.360). The number of Treg cells was significantly related to retinal lesion size (p = 0.043), with a correlation coefficient of -0.648, indicating a strong and inverse correlation. There was no significant correlation between serum IL-27 levels and retinal lesion size (p = 0.556).

Conclusion

Ocular toxoplasmosis patients have a low number of Treg cells that are inversely related to the retinal lesion size. The size of the retinal lesion increases as the number of Treg cells decreases.

Assessment of ocular toxoplasmosis patients reported at a tertiary center in the northeast of Iran

PURPOSE

Ocular toxoplasmosis, which is caused by the single-cell parasite Toxoplasma gondii, is currently the most significant cause of posterior uveitis in the world. No previous studies have described the prevalence and clinical features of ocular toxoplasmosis in the northeast of Iran. The purpose of the current study was to address this gap.

METHODS

In this retrospective study, the medical records of 488 uveitis patients who presented to the Khatam-al-Anbia Eye Hospital of Mashhad University of Medical Sciences, a tertiary ophthalmology center in the northeast of Iran, between January 2013 and December 2015 were evaluated. The clinical features and risk factors of 99 (20%) consecutive patients with ocular toxoplasmosis were extracted.

RESULTS

Ninety-nine including 53 (53.5%) female and 46 (46.5%) male patients with ocular toxoplasmosis were included in the analysis. Reduced vision (77%) and floaters (15.2%) were the most common presenting symptoms. The age category that was most affected by ocular toxoplasmosis was 20-40 years (range: 11-65 years) with a mean age of 27.2. All patients had retinochoroiditis, but just two had anterior uveitis. All of the extracted patients, with the exception of three patients, had unilateral involvement. None of the patients had any other medical disorders with the exception of one woman, who had diabetes. Only four recurring ocular toxoplasmosis patients were referred to the education hospital during the study. Serology data were available for just 32 patients, of which 31 (96.8%) were IgG positive, and 1 (3.2%) was IgM positive.

CONCLUSION

Toxoplasma gondii was responsible for 20% of the patients of uveitis that presented to the largest ophthalmology center in the northeast of Iran. There is a high incidence of patients of ocular toxoplasmosis in the northeast of Iran, and it is a significant cause of uveitis and visual impairment in this area.

PCR-based Diagnosis of Toxoplasma Parasite in Ocular Infections Having Clinical Indications of Toxoplasmosis

BACKGROUND

The diagnosis of ocular toxoplasmosis is mainly based on clinical features. However, ocular fluid testing by PCR may be very helpful for approval or rejection of this etiology. In this study, we utilized a nested-PCR technique, targeting the B1 partial sequence to analyze the aqueous and vitreous samples for evaluating the presence of the Toxoplasma DNA.

METHODS

Fifty aqueous or vitreous humor samples were obtained from patients with clinical features of ocular toxoplasmosis admitted to ophthalmology hospitals and clinics in Iran, within 2014. The samples were subsequently subjected to DNA extraction and purification. For nested amplification of the Toxoplasma B1 gene, two primer pairs were used. The outer and inner primers are expected to produce a 193 bp and a 96 bp fragments, respectively.

RESULTS

The first-round PCR resulted in the detection of T. gondii in 58% of samples by amplification of the expected 193bp DNA fragment. The nested-PCR using the inner primers, detected 15 additional samples from those with negative amplicons in the first round PCR (overall positivity of 88%). In addition, vitreous samples showed relatively more positive cases than aqueous humor in detection of the infection.

CONCLUSION

The nested-PCR protocol using the B1 gene, with the high detection power, could be a useful complimentary method to clinical diagnose of ocular toxoplasmosis.