Role of IL-6/IL-10 ratio in the diagnosis and in the assessment of the severity of obsessive-compulsive disorder

Exploring the role of interleukin-1β and interleukin-6 in the pathophysiology of obsessive-compulsive disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is a highly prevalent neuropsychiatric disorder. Recently, there has been a growing interest in investigating the association between pro-inflammatory cytokines and the pathogenesis of OCD. However, studies targeting interleukin-1β (IL-1β) and interleukin-6 (IL-6) in OCD are limited. Therefore, the present study aimed to explore the potential role of pro-inflammatory cytokines IL-1β and IL-6 in the pathophysiology and development of OCD.

METHODS

This study recruited 58 OCD patients and 30 age-sex-matched healthy controls (HCs). A qualified psychiatrist diagnosed OCD patients and assessed HCs based on the Diagnostic and Statistical Manual for Mental Health Disorders, 5th edition (DSM-5) criteria. We measured the severity of OCD using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). Serum IL-1β and IL-6 levels were measured using ELISA kits following the appropriate methods.

RESULTS

The results showed that serum IL-1β levels were significantly elevated in OCD patients compared to HCs (23.68±1.65 pg/ml vs. 15.75±1.02 pg/ml; p = 0.002). Similarly, OCD patients exhibited significantly higher serum IL-6 levels than HCs (44.97±0.73 pg/ml vs. 37.04±0.35 pg/ml; p<0.001). We observed both cytokines were positively correlated with the Y-BOCS scores in OCD patients (IL-1β: r = 0.380, p = 0.015; IL-6: r = 0.324, p = 0.026) which indicates their role in disease pathophysiology.

CONCLUSION

These results suggest that serum IL-1β and IL-6 levels may be associated with the pathophysiology of OCD. Also, these cytokines levels in blood samples can serve as early risk assessment tools for the development of OCD. We recommend further studies in a large and homogeneous population to support these findings.

Differential effects of lipopolysaccharide on cognition, corticosterone and cytokines in socially-housed vs isolated male rats

Social isolation is an established risk factor for mental illness and impaired immune function. Evidence suggests that neuroinflammatory processes contribute to mental illness, possibly via cytokine-induced modulation of neural activity. We examined the effects of lipopolysaccharide (LPS) administration and social home cage environment on cognitive performance in the 5-Choice Serial Reaction Time Task (5CSRTT), and their effects on corticosterone and cytokines in serum and brain tissue. Male Long-Evans rats were reared in pairs or in isolation before training on the 5CSRTT. The effects of saline and LPS (150 µg/kg i.p.) administration on sickness behaviour and task performance were then assessed. LPS-induced sickness behaviour was augmented in socially-isolated rats, translating to increased omissions and slower response times in the 5CSRTT. Both social isolation and LPS administration reduced impulsive responding, while discriminative accuracy remained unaffected. With the exception of reduced impulsivity in isolated rats, these effects were not observed following a second administration of LPS, revealing behavioural tolerance to repeated LPS injections. In a separate cohort of animals, social isolation potentiated the ability of LPS to increase serum corticosterone and IL-6, which corresponded to increased IL-6 in the orbitofrontal and medial prefrontal cortices and the nucleus accumbens. Basal IL-4 levels in the nucleus accumbens were reduced in socially-isolated rats. These findings are consistent with the adaptive response of reduced motivational drive following immune challenge, and identify social isolation as an exacerbating factor. Enhanced IL-6 signalling may play a role in mediating the potentiated behavioural response to LPS administration in isolated animals.

Serum IL-6/IL-10 ratio as a biomarker for the diagnosis and severity assessment of primary-open angle glaucoma

OBJECTIVE

To assess the performance of serum cytokine IL-6 and IL-6/IL-10 ratio as biomarkers for the diagnosis of primary open-angle glaucoma (POAG) and for determining its progression.

METHODS

In this study, 20 POAG patients and 21 healthy individuals from the Indonesian population were enrolled. The serum concentration of IL-6 and IL-10 were quantified. Comparative analysis was performed in addition to assessment of the diagnostic performance of cytokines using receiver-operating-curve (ROC) analysis.

RESULTS

POAG patients had a higher IL-6 (p < 0.0001) and IL-6/IL-10 ratio (p < 0.0001) than controls. Among the POAG subjects, advanced-stage patients exhibited a higher IL-6/IL-10 ratio than those in the early-moderate stage (p = 0.001; p = 0.006). The ROC curve analysis showed that both IL-6 level and IL-6/IL-10 ratio exhibited an excellent capability of diagnosing POAG (cut-off of 20.5 pg/mL (100% sensitivity and 94% specificity) and 4.4 (88% sensitivity and 94% specificity), respectively). Serum IL-6/IL-10 ratio displayed a better performance than IL-6 in discriminating POAG severity with cut-off of at least 6.6 (sensitivity of 86% and specificity of 90%) and 9.1 (sensitivity of 89% and specificity of 78%) classified according to C/D ratio and MD of VF, respectively.

CONCLUSION

The balance between IL-6 and IL-10 serum levels is potentially useful in discriminating POAG severity.