Arnaud Sauer

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.

In Vitro Efficacy of Antifungal Treatment Using Riboflavin/UV-A (365 nm) Combination and Amphotericin B

PURPOSE To demonstrate the antimicrobial properties of riboflavin/UV-A (365 nm) against fungal pathogens. METHODS The antimicrobial properties of riboflavin/UV-A (365 nm), with or without previous treatment with amphotericin B, were tested on three groups of fungi selected from severe cases of keratomycosis: Candida albicans, Fusarium sp, and Aspergillus fumigatus. They were tested by using Kirby-Bauer discs with empty disc (control), riboflavin 0.1% alone (R), UV-A alone (UV-A), riboflavin 0.1% and additional UV-A exposure (R+UV-A), amphotericin B alone (A), amphotericin B and riboflavin 0.1% (A+R), amphotericin B and UV-A (A+UV-A), amphotericin B and riboflavin 0.1%, and additional UV-A exposure (A+R+UV-A). The mean growth inhibition zone (GIZ) was measured around the discs. RESULTS C. albicans, Fusarium sp, and A. fumigatus did not show any increased GIZ after treatment without previous amphotericin B medication. However, GIZ was significantly greater after pretreatment with amphotericin B and riboflavin/UV-A (A+R+UV-A) for C. albicans (P = 0.0005), Fusarium sp (P = 0.0023) and A. fumigatus (P = 0.0008) compared with A, A+R, and A+UV-A. CONCLUSIONS Amphotericin B is believed to interact with fungi membrane sterols to produce aggregates that form transmembrane channels. Given that collagen is one of the principal components of the cornea, it is also probable that amphotericin B may diffuse easily after cross-linking. Previous treatment with amphotericin B allowed riboflavin/UV-A effectiveness against C. albicans, Fusarium sp, and A. fumigatus. This schema might be used in the future for the treatment of keratomycosis.

Severe South American ocular toxoplasmosis is associated with decreased Ifn-γ/Il-17a and increased Il-6/Il-13 intraocular levels.

In a cross sectional study, 19 French and 23 Colombian cases of confirmed active ocular toxoplasmosis (OT) were evaluated. The objective was to compare clinical, parasitological and immunological responses and relate them to the infecting strains. A complete ocular examination was performed in each patient. The infecting strain was characterized by genotyping when intraocular Toxoplasma DNA was detectable, as well as by peptide-specific serotyping for each patient. To characterize the immune response, we assessed Toxoplasma protein recognition patterns by intraocular antibodies and the intraocular profile of cytokines, chemokines and growth factors. Significant differences were found for size of active lesions, unilateral macular involvement, unilateral visual impairment, vitreous inflammation, synechiae, and vasculitis, with higher values observed throughout for Colombian patients. Multilocus PCR-DNA sequence genotyping was only successful in three Colombian patients revealing one type I and two atypical strains. The Colombian OT patients possessed heterogeneous atypical serotypes whereas the French were uniformly reactive to type II strain peptides. The protein patterns recognized by intraocular antibodies and the cytokine patterns were strikingly different between the two populations. Intraocular IFN-γ and IL-17 expression was lower, while higher levels of IL-13 and IL-6 were detected in aqueous humor of Colombian patients. Our results are consistent with the hypothesis that South American strains may cause more severe OT due to an inhibition of the protective effect of IFN-γ.

Microbial keratitis as a foreseeable complication of cosmetic contact lenses: a prospective study

Purpose:  A recent study shows that the relative risk of contact lenses (CL)‐related microbial keratitis (MK) is highly increased with cosmetic contact lenses (CosCL). The aim of our study is to illustrate the implications of the CosCL on the occurence of MK and to describe the subpopulation of CosCL wearers.

New clinical and experimental insights into Old World and neotropical ocular toxoplasmosis

Retinal lesions or other ocular manifestations are serious consequences of infection with the protozoan parasite Toxoplasma gondii. Whilst classically considered a consequence of congenital transmission, recent screening studies estimated that 2% of T. gondii seropositive persons in Europe and North America have retinal lesions, most of them persisting unnoticed. The situation is more dramatic in South America, probably due to the predominance of virulent strains. Some of these strains seem to exhibit ocular or neuronal tropism and are responsible for severe ocular lesions. Despite the medical importance, the physiopathological mechanisms have only recently begun to be elucidated. The particular immune-privileged situation in the eye has to be considered. Studies on French patients showed low or undetectable ocular parasite loads, but a clear Th1/Th17 type immune reaction. Suitable mouse models have appeared in the last few years. Using such a model, IL-17A proved to impair parasite control and induce pathology. In contrast, in South American patients, the parasite seems to be much less efficiently controlled through a Th2 type or suppressive immune response that favors parasite replication. Finally, several host genetic markers controlling immune response factors have been associated with ocular involvement of T. gondii infection, mainly in South America.

The local immune response to intraocular Toxoplasma re-challenge: Less pathology and better parasite control through Treg/Th1/Th2 induction

Ocular toxoplasmosis is a major cause of blindness world-wide. Ocular involvement is frequently seen following congenital infection. Many of these infections are quiescent but pose a life-time risk of reactivation. However, the physiopathology of ocular toxoplasmosis reactivation is largely unexplored. We previously developed a Swiss-Webster outbred mouse model for congenital toxoplasmosis by neonatal injection of Toxoplasma gondii cysts. We also used a mouse model of direct intraocular infection to show a deleterious local T helper 17 type response upon primary infection. In the present study, our two models were combined to study intravitreal re-challenge of neonatally infected mice, as an approximate model of reactivation, in comparison with a primary ocular infection. Using BioPlex proteomic assays in aqueous humour and reverse transcription-PCR for T helper cell transcription factors, we observed diminished T helper 17 type reaction in reinfection, compared with primary infection. In contrast, T helper 2 and T regulatory responses were enhanced. Interestingly, this was also true for T helper 1 markers such as IFN-γ, which was paralleled by better parasite control. Secretion of IL-27, a central cytokine for shifting the immune response from T helper 17 to T helper 1, was also greatly enhanced. We observed a similar protective immune reaction pattern in the eye upon reinfection with the virulent RH strain, with the notable exception of IFN-γ. In summary, our results show that the balance is shifted from T helper 17 to a less pathogenic but more effective anti-parasite Treg/T helper 1/T helper 2 pattern in a reactivation setting.

Prevention of retinochoroiditis in congenital toxoplasmosis: Europe versus South America.

Congenital toxoplasmosis is suspected when seroconversion occurs in a pregnant woman, and it is confirmed by one or more biologic tests (polymerase chain reaction on amniotic fluid or neonatal serodiagnosis). The methods used are diagnostic in more than 95% of cases at birth and in 100% of cases by the age of 9 months. Ocular lesions represent the most frequent complication of congenital toxoplasmosis, independent of any treatment. The risk of toxoplasmic retinochoroiditis is highly unpredictable, however, mainly because the pathophysiology is poorly understood. By school age, 10% to 20% of children with congenital toxoplasmosis have one or more retinochoroidal lesions, but more than 90% of them have normal vision in both eyes; bilateral blindness is very rare. This article focuses on the controversy surrounding the effectiveness of screening and treatment for children with congenital toxoplasmosis.

Murine neonatal infection provides an efficient model for congenital ocular toxoplasmosis.

Congenital infection is one of the most serious settings of infection with the apicomplexan parasite Toxoplasma gondii. Ocular diseases, such as retinochoroiditis, are the most common sequels of such infection in utero. However, while numerous studies have investigated the physiopathology of acquired toxoplasmosis, congenital infection has been largely neglected so far. Here, we establish a mouse model of congenital ocular toxoplasmosis. Parasite load and ocular pathology have been followed for the first 4 weeks of life. Ocular infection developed slowly compared to cerebral infection. Even after 4 weeks, not all eyes were infected and ocular parasite load was low. Therefore, we evaluated a scheme of neonatal infection to overcome problems associated with congenital infection. Development of infection and physiopathology was similar, but at a higher, more reliable rate. In summary, we have established a valuable model of neonatal ocular toxoplasmosis, which facilitates the research of the underlying physiopathological mechanisms and new diagnostic approaches of this pathology.

Impairment of Lacrimal Secretion in the Unaffected Fellow Eye of Patients with Recurrent Unilateral Herpetic Keratitis

PURPOSE To assess the impact of recurrent unilateral herpetic keratitis (HK) on the tear secretion of the unaffected fellow eye. DESIGN Prospective, noninterventional study. PARTICIPANTS AND CONTROLS Thirty-five patients with a history of recurrent unilateral HK (clinically quiescent for at least 3 months) (HK group) and 35 patients who were age- and sex-matched with no history of corneal disease (control group). METHODS Tear osmolarity, tear instability (tear break-up time [TBUT]), tear reflex (Schirmers I test), and central corneal sensitivity with the Cochet-Bonnet esthesiometer (Luneau, France) were measured in the HK and control groups. MAIN OUTCOME MEASURES Tear osmolarity, TBUT, Schirmers I, and central corneal sensitivity were compared between the affected and unaffected eyes of the HK and control groups. RESULTS Tear osmolarity and tear secretion reflex were similar between the affected and unaffected eyes of the HK group. Corneal sensitivity and TBUT were statistically lower in the affected eyes compared with the unaffected eyes in the HK group (P = 0.001 and P<0.001, respectively). The central corneal sensitivity of unaffected eyes in the HK group was not significantly different from that in the control group (P>0.05). The tear stability and tear secretion reflex were decreased and tear osmolarity was increased in the unaffected eyes of the HK group compared with the control group (P<0.05, all cases). The difference between unaffected and control eyes varied according to the type of HK. All 4 tests were modified in patients with neurotrophic keratitis (KN). In the keratouveitis subgroup, only corneal sensitivity was normal, whereas Schirmers I results were also normal in patients with archipelago keratitis. Tear osmolarity was consistently affected in both eyes of herpetic patients. CONCLUSIONS Tear function is impaired in the unaffected eyes of patients with unilateral recurrent HK, even when the disease is apparently quiescent. The higher severity of results in the unaffected fellow eye of patients with KN in comparison with other herpes subgroups suggests that recurrent HK induces a reduction in the afferent pathways of the tear secretion reflex from the affected eye, leading to tear dysfunction in the unaffected eye. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Ocular penetration of topically applied linezolid in a rabbit model.

PURPOSE: To evaluate ocular penetration of topically applied linezolid, a new antibiotic agent targeted against gram‐positive organisms. SETTING: Laboratory of Pharmacology, University Hospital of Strasbourg, Strasbourg, France. METHODS: New Zealand White rabbits were divided into 3 equal groups. One drop of 50 μL (2 mg/mL) linezolid was administrated in Group 1. In Group 2, eyes were dosed in accordance with a keratitis protocol (1 drop of 2 mg/mL every 15 minutes for 1 hour). Aqueous humor was sampled 6 times from immediately after to 3 hours after drop delivery. In Group 3, a keratitis protocol was implemented before the animals were humanely killed. Conjunctiva, cornea, vitreous, and blood samples were collected 1 hour and 2 hours after the last drop. Linezolid concentrations were measured by high‐performance liquid chromatography. RESULTS: Each group comprised 8 rabbits. In Group 1 and Group 2, the peak linezolid concentration in the aqueous humor (mean 0.87 mg/L ± 0.16 [SD] and 2.17 ± 0.4 mg/L, respectively) was 45 minutes after the last drop delivery. In Group 3, the concentrations 1 hour and 2 hours after the last drop were higher than 3 μg/g in the conjunctiva samples and higher than 4 μg/g in the cornea samples. The linezolid concentration in the vitreous and serum was negligible. CONCLUSIONS: Linezolid levels in the aqueous humor, conjunctiva, and cornea exceeded the minimum inhibitory concentration of most gram‐positive organisms that cause bacterial keratitis and endophthalmitis. Linezolid could be a valuable alternative in cases of increased resistance to vancomycin. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.