Abstract
Purpose:
To investigate the cytokine profiles of aqueous humor samples of patients with primary (p) or recurrent (r) ocular toxoplasmosis (OT) and potential correlations with clinical characteristics.
Methods:
We investigated aqueous humor samples of 62 individuals/patients (27 male, 35 female, mean age: 36 yrs). All patients included in this study were confirmed as OT by intraocular positive toxoplasma gondii antibodies (Goldman/Witmer coefficient>3). The Bioplex-Immunoassay was used to analyze for 27 chemokines/cytokines. Our study cohort consisted of 22 pts. with primary (p)OT infection and 29 pts. with recurrent (r)OT and 11 age matched individuals as controls. The Wilcoxon-Mann-Whitney-Test was applied to compare cytokine levels between groups, whereas the spearman correlation was used for a subgroup analysis of recurrent OT.
Results:
Significant differences of the intraocular cytokine profile could be related to clinical features. Firstly, we demonstrate that several cytokines are highly elevated in pOT as well as in rOT as compared to controls. IFNγ as an important primary indicator for intraocular immune response was higher in pOT (p=0.0002) and rOT (p=0.0017). We also observed that IL-17-levels were increased in pOT (p=0.05), but not in rOT (p=0.2996). IL-12-levels are not significantly elevated in pOT (p=0.75) and even slightly decreased in rOT (p=0.38). Moreover, we could correlate the number of recurrences with a reduction of IL-9 (p=0.01), TNFα (p=0.0326), IL-13 (p=0.0326) and IFNγ (p=0.0315).
Conclusions:
The role of the intraocular cytokinome is still under debate. Our results confirm the significant contribution of IFNγ in both pOT and rOT. In contrast, intraocular IL-12, as major inducer of IFNγ, remained low. This may imply that other pathways of OT activation are important. IL-17 as a potential target for specific therapy, was significantly upregulated in active pOT but not rOT. As an interesting feature we first demonstrate an impaired IL-9 production which highly correlated with rOT. Currently, the role of TH9 cells in OT is unknown and warrants further investigation.<br /> Strategies designed to identify certain cytokine clusters could potentially select patients at risk for recurrent retinitis.