In vitro studies have demonstrated possible neuroprotective effects of the following pro-inflammatory cytokines: IL-6, IL-1β and TNF-α against glutaminergic excitotoxicity in brain through different pathways.

In the current study, we aim to correlate level of the above pro-inflammatory cytokines in serum with glutamate levels in head of caudate nucleus measured using Proton Magnetic Resonance Spectroscopy (1H-MRS) in patients with obsessive-compulsive disorder (OCD), a neuropsychiatric illness with possible multifactorial aetiology including immunological and excitotoxic factors.

Thirty psychotropic-naïve patients with OCD and an equal number of gender and age-matched normal controls were recruited in the study. A detailed psychiatric assessment was carried out including sociodemographic and clinical variables. A 3T MR imaging and spectroscopy session was carried out in head of caudate nucleus. Further, absolute quantification of glutamate level was obtained using LC model. Simultaneously, 5 mL of blood sample was collected and assayed for the above pro-inflammatory cytokines (Siemens, Immulite™). The level of glutamate was correlated with the cytokine levels in patients with OCD.

The level of Glx was significantly higher in patients with OCD as compared to controls (P < 0.05). The Glx level negatively correlated with two of the three pro-inflammatory cytokines: IL-6 and TNF-α (r = −0.807; r = −0.838; P < 0.05) while no significant correlation was demonstrated with IL-1β.

The findings provide preliminary evidence regarding possible neuroprotective effects of pro-inflammatory cytokines against glutaminergic excitotoxicity in patients with OCD. Further studies including patients with other psychiatric illnesses as controls are required for confirmation of the above findings.

The authors have not supplied their declaration of competing interest.