Corticosteroids as adjuvant therapy for ocular toxoplasmosis

The Role of Corticosteroids and Immunomodulatory Therapy in the Management of Infectious Uveitis

PURPOSE

The index review aims to provide an update on the role of corticosteroids and steroid-sparing immunomodulatory therapy (IMT) in managing patients with infectious uveitis.

METHOD

Narrative literature review.

RESULTS

Corticosteroids and immunomodulatory therapy (IMT) focus on the host defense system instead of the pathogen, adjusting exaggerated inflammatory reactions to reduce potential harm to ocular tissues. Systemic or local corticosteroids are primarily selected as adjunctive medication for infectious uveitis. Concomitant corticosteroids have also been used in cases of paradoxical worsening in ocular tuberculosis and immune recovery uveitis in cytomegalovirus (CMV) retinitis. While there is no well-established evidence to support the use of IMT in infectious uveitis, it is occasionally used in clinical settings to treat persistent inflammation following resolution of infection such as cases of ocular tuberculosis and ocular syphilis where an insufficient response is observed with corticosteroids.

CONCLUSION

There is no consensus on the position of immunomodulatory therapy in the management of infectious uveitis with different etiologies. The index review provides an overview of available adjunctive corticosteroids and IMT options to assist clinicians in managing such disease entities more efficiently.

Ocular Toxoplasmosis

INTRODUCTION

Ocular toxoplasmosis is the leading cause of posterior uveitis worldwide, affecting individuals acrossdifferent age groups. The key to reducing vision loss includes prompt diagnosis and treatment. However, despite the prevalence of ocular toxoplasmosis, there has been little consensus regarding its pathophysiology,clinical features, diagnosis, and especially management.

METHODS

The data sources were literature reviews, including Pub Med and Medline databases. Search terms included toxoplasmosis, retinitis, vasculitis, vitritis, uveitis alone or in combination with, serum, aqueous, vitreous eye, ocular and review.

RESULTS

In this review paper, we have sought to provide an overview of the pathophysiology, epidemiology, and clinical features of the disease, both based on current literature and our own clinical experience. We have also discussed the use of serology, ocular fluid, and ophthalmic investigations that could further facilitate the diagnosis of ocular toxoplasmosis.Different management strategies have been reported worldwide, including newer approaches such as local therapy.

CONCLUSION

A better understanding of critical aspects of ocular toxoplasmosis will hopefully lead to reduced morbidity, including blindness associated with this condition.

Infections and glaucoma

Glaucoma is an intraocular pressure-related ophthalmic disease with multiple causes that results in an optic neuropathy and vision loss. Intraocular pressure elevation is among its strongest risk factors. While glaucoma is mostly primary in etiology, secondary glaucoma is not infrequent. Recognizing its cause is imperative, since treatment is often different depending on the pathophysiologic mechanism. Numerous clinically relevant ophthalmic infections can result in robust inflammatory responses that may result in pressure elevation or intraocular anatomic configurations that predispose to pressure elevation. Knowing the mechanisms by which these infections can lead to glaucoma is critical in treating, and we consolidate what is currently known in regards to how infectious diseases lead to glaucoma.

A Perspective on Thiazolidinone Scaffold Development as a New Therapeutic Strategy for Toxoplasmosis

Toxoplasma gondii is one of the most successful parasites due to its ability to infect a wide variety of warm-blooded animals. It is estimated that one-third of the world's population is latently infected. The generic therapy for toxoplasmosis has been a combination of antifolates such as pyrimethamine or trimethoprim with either sulfadiazine or antibiotics such as clindamycin with a combination with leucovorin to prevent hematologic toxicity. This therapy shows limitations such as drug intolerance, low bioavailability or drug resistance by the parasite. There is a need for the development of new molecules with the capacity to block any stage of the parasite's life cycle in humans or in a different type of hosts. Heterocyclic compounds are promissory drugs due to its reported biological activity; for this reason, thiazolidinone and its derivatives are presented as a new alternative not only for its inhibitory activity against the parasite but also for its high selectivity-level with high therapeutic index. Thiazolidinones are an important scaffold known to be associated with anticancer, antibacterial, antifungal, antiviral, antioxidant, and antidiabetic activities. The molecule possesses an imidazole ring that has been described as an antiprotozoal agent with antiparasitic properties and less toxicity. Thiazolidinone derivatives have been reportedly as building blocks in organic chemistry and as scaffolds for drug discovery. Here we present a perspective of how structural modifications of the thiazolidinone core could generate new compounds with high anti-parasitic effect and less toxic results.

Treatment of Toxoplasmosis: Historical Perspective, Animal Models, and Current Clinical Practice

Primary Toxoplasma gondii infection is usually subclinical, but cervical lymphadenopathy or ocular disease can be present in some patients. Active infection is characterized by tachyzoites, while tissue cysts characterize latent disease. Infection in the fetus and in immunocompromised patients can cause devastating disease. The combination of pyrimethamine and sulfadiazine (pyr-sulf), targeting the active stage of the infection, is the current gold standard for treating toxoplasmosis, but failure rates remain significant. Although other regimens are available, including pyrimethamine in combination with clindamycin, atovaquone, clarithromycin, or azithromycin or monotherapy with trimethoprim-sulfamethoxazole (TMP-SMX) or atovaquone, none have been found to be superior to pyr-sulf, and no regimen is active against the latent stage of the infection. Furthermore, the efficacy of these regimens against ocular disease remains uncertain. In multiple studies, systematic screening for Toxoplasma infection during gestation, followed by treatment with spiramycin for acute maternal infections and with pyr-sulf for those with established fetal infection, has been shown to be effective at preventing vertical transmission and minimizing the severity of congenital toxoplasmosis (CT). Despite significant progress in treating human disease, there is a strong impetus to develop novel therapeutics for both the acute and latent forms of the infection. Here we present an overview of toxoplasmosis treatment in humans and in animal models. Additional research is needed to identify novel drugs by use of innovative high-throughput screening technologies and to improve experimental models to reflect human disease. Such advances will pave the way for lead candidates to be tested in thoroughly designed clinical trials in defined patient populations.

Rapid resolution of toxoplasma chorioretinitis treatment using quadruple therapy

Purpose

To compare the effectiveness of quadruple-drug therapy consisting of cotrimoxazole (trimethopin and sulfamethoxazole), clindamycin antibiotics, and oral corticosteroid versus triple therapy consisting of pyrimetamine, sulphadiazine, and oral corticosteroid in the resolution of toxoplasmic chorioretinitis.

Methods

This was a double-blind randomized controlled trial with repeated measures using parallel design to compare the effectiveness of quadruple-drug therapy and triple-drug therapy in patients with toxoplasmic chorioretinitis. The measurement of lesion was done using automated computer software, calculating the average of lesion size from three fundus photographs taken from the baseline and at each follow-up visit. The analytical statistics were obtained using Mann-Whitney test, comparing percentage of lesion remission test in each examination.

Results

The percentage of lesion remission in quadruple-drug therapy was higher than in triple-drug therapy from the first visit until the first follow-up visit, with a p-value of 0.001. In addition, the mean percentage of lesion remission from first visit to last visit was 57.5% and the median was 70.9% in the quadruple therapy group, while in the triple-drug therapy group the mean was 52.5% and the median was 54.0% (p=0.720).

Conclusion

We conclude that the quadruple-drug therapy has a more rapid resolution effect on chorioretinitis lesion compared to triple therapy.

Infectious uveitis: An enigma

Infectious uveitis accounts for majority of the cases of uveitis in developing countries. It also encompasses an array of various microorganisms and their clinical presentations. Some of these infectious uveitic entities are familiar, while others are newly emerging in the global ophthalmic world. Many of these entities are also a major cause of morbidity and mortality, and appropriate, timely management is required to save not the eye, but life of the patient. This review highlights the ocular manifestations of various infectious uveitic entities, relevant to the ophthalmologist.

Corticosteroids as adjuvant therapy for ocular toxoplasmosis

BACKGROUND

Ocular infection caused by Toxoplasma gondii, a parasite, may result in inflammation in the retina, choroid, and uvea, and consequently lead to complications such as glaucoma, cataract, and posterior synechiae.

OBJECTIVES

The objective of this systematic review was to assess the effects of adjunctive use of corticosteroids to anti-parasitic therapy versus anti-parasitic therapy alone for ocular toxoplasmosis.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register (2016; Issue 11)), MEDLINE Ovid, Epub Ahead of Print, In-Process & Other Non-Indexed Citations, MEDLINE Ovid Daily (January 1946 to December 2016), Embase (January 1980 to December 2016), Latin American and Caribbean Literature on Health Sciences (LILACS (January 1982 to December 2016)), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP; www.who.int/ictrp/search/en). We used no date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 7 December 2016.

SELECTION CRITERIA

We had planned to include randomized and quasi-randomized controlled trials. Eligible trials would have enrolled participants of any age who were immunocompetent and were diagnosed with acute ocular toxoplasmosis. Included trials would have compared anti-parasitic therapy plus corticosteroids versus anti-parasitic therapy alone, different doses or times of initiation of corticosteroids.

DATA COLLECTION AND ANALYSIS

Two authors independently screened titles and abstracts retrieved through the electronic searches. We retrieved full-text reports of studies categorized as 'unsure' or 'include' after we reviewed the abstracts. Two authors independently reviewed each full-text report for eligibility. Discrepancies were resolved through discussion.

MAIN RESULTS

We identified no completed or ongoing trial that was eligible for this Cochrane review.

AUTHORS' CONCLUSIONS

Although research has identified a wide variation in practice regarding the use of corticosteroids, our review did not identify any evidence from randomized controlled trials for or against the role of corticosteroids in the management of ocular toxoplasmosis. Several questions remain unanswered by well-conducted randomized trials in this context, including whether the use of corticosteroids as an adjunctive agent is more effective than the use of anti-parasitic therapy alone; if so, when corticosteroids should be initiated in the treatment regimen (early versus late course of treatment), and what would be the best dose and duration of steroid use.

Host and Toxoplasma gondii genetic and non-genetic factors influencing the development of ocular toxoplasmosis: A systematic review

Toxoplasmosis is a cosmopolitan infection caused by the apicomplexan parasite Toxoplasma gondii. This infectious disease is widely distributed across the world where cats play an important role in its spread. The symptomatology caused by this parasite is diverse but the ocular affectation emerges as the most important clinical phenotype. Therefore, we conducted a systematic review of the current knowledge of ocular toxoplasmosis from the genetic diversity of the pathogen towards the treatment available for this infection. This review represents an update to the scientific community regarding the genetic diversity of the parasite, the genetic factors of the host, the molecular pathogenesis and its association with disease, the available diagnostic tools and the available treatment of patients undergoing ocular toxoplamosis. This review will be an update for the scientific community in order to encourage researchers to deploy cutting-edge investigation across this field.

Choroidoretinal granuloma in a young female patient

A 16-year-old Brazilian female patient presented with blurring of vision in the right eye. Corrected visual acuity was OD 2/20, OS 20/20. Afferent pupillary defect was absent and anterior segment examination revealed anterior uveitis. Fundus examination showed light vitritis and a raised grey-white granuloma located at posterior pole with focal serous retinal detachment on optical coherence. Indocyacnine green angiography disclosed a complete mask effect in granuloma's area. Differential diagnoses were infectious (bacterial, viral, fungal and parasites) diseases, systemic inflammatory diseases, tumours. Blood serologies (HIV, toxoplasma, Borrelia, cytomegalovirus (CMV), herpes simplex virus (HSV), varicella-zoster virus (VZV), rubeola) showed positive results for IgM and IgG for toxoplasma, and anterior chamber tap (PCR for toxoplasma, CMV, HSV, VZV) revealed toxoplasma DNA. Anti-toxoplasma therapy, pyrimethamine, sulfadiazine and calcium folinate, was administered immediately. On follow-up granuloma regression was observed, with complete visual restoration. This case demonstrates a clinically challenging posterior pole granuloma.

Clinical features and treatment of ocular toxoplasmosis

Ocular toxoplasmosis is a disease caused by the infection with Toxoplasma gondii through congenital or acquired routes. Once the parasite reaches the retina, it proliferates within host cells followed by rupture of the host cells and invasion into neighboring cells to make primary lesions. Sometimes the restricted parasite by the host immunity in the first scar is activated to infect another lesion nearby the scar. Blurred vision is the main complaint of ocular toxoplasmic patients and can be diagnosed by detection of antibodies or parasite DNA. Ocular toxoplasmosis needs therapy with several combinations of drugs to eliminate the parasite and accompanying inflammation; if not treated it sometimes leads to loss of vision. We describe here clinical features and currently available chemotherapy of ocular toxoplasmosis.