Neopterin Release and Tryptophan Degradation in Patients with Uveitis

Uveitis is an intraocular inflammation affecting the highly vascularized uveal tissue. Early recognition and appropriate therapeutic intervention of uveitis are important since the condition may be associated with systemic disease and untreated uveitis may lead to blindness. Neopterin, an unconjugated pteridine, is an important biomarker of cell-mediated immunity and has a potential function in the process of inflammation. In addition to neopterin release, cellular immune activation also induces indoleamine 2,3-dioxygenase (IDO). In this study, the aim was to investigate possible immune changes in uveitis by determination of neopterin concentrations and tryptophan (Trp) degradation.

The participants who attended to the ophthalmology clinic with uveitis were divided into two groups: active (n = 63) and remission (n = 41). Additionally 30 healthy subjects were recruited as a control group.

In total, in 104 uveitis patients, urinary and serum neopterin, kynurenine (Kyn), and Kyn/Trp were found to be statistically higher than the 30 controls (all, p < 0.05). It was observed that all of the measured parameters did not differ between active and remission uveitis groups (all, p > 0.05), except for the Kyn/Trp ratio (p < 0.05). Urinary and serum neopterin levels were positively correlated with Kyn/Trp in the uveitis patients (both p < 0.05).

From these results, it can be concluded that uveitis can cause alterations in neopterin levels and the Kyn pathway. It seems that the measured parameters can be useful markers of cellular immune response in uveitis, although they might not be used to differentiate active or remission uveitis.