IL-6 in depressive disorder

Major depressive disorder (MDD) is a prevalent mental health condition that ranks among the top psychiatric illnesses worldwide. Approximately 30-60% of patients diagnosed with depression do not show positive responses to currently available antidepressant treatments. There is consistent evidence suggesting that elevated blood levels of the cytokine interleukin-6 (IL-6) in individuals with MDD have a significant impact on stress responses and correlate with depression severity scores (1, 2).

IL-6 in depressive disorder

Given the association between IL-6 and MDD, inhibiting IL-6 has gained attention as a potential therapeutic approach for depression. By targeting IL-6 pathways it is hypothesized that the aberrant inflammatory response associated with MDD can be modulated, leading to improved treatment outcomes. Exploring IL-6 inhibition, as a novel strategy holds promise for the development of more effective therapies for individuals who are non-responsive to current antidepressant treatments.

IL-6 can reliably be measured in various sample types by ELISA assay:

BIOMEDICA IL-6 ELISA (cat. no. BI-IL6)

• Sensitive – Measurable values in serum and plasma samples
• Reliable – Full validation package
• Specific-  Characterized epitope-mapped antibodies
• Easy – Color-coded reagents and controls included

 

Related ELISA products

VEGF (cat. no. BI-VEGF), Angiopoietin-2 (BI-ANG2), Big-Endothelin (cat. no. BI-20082H), NT-proCNP (cat. no. BI-20812)

Publications

1. How does IL-6 change after combined treatment in MDD patients? A systematic review. Lombardi AL, Manfredi L, Conversi D. Brain Behav Immun Health. 2022 Dec 24;27:100579. doi: 10.1016/j.bbih.2022.100579. PMID: 36624849; PMCID: PMC9822965.
2. Role of Interleukin-6 in Depressive Disorder. Ting EY et al., Int J Mol Sci. 2020 Mar 22;21(6):2194. doi: 10.3390/ijms21062194. PMID: 32235786; PMCID: PMC7139933.

 

Related literature

Interleukin 6 as a marker of depression in women with sleep apnea. Campos-Rodriguez F et al., J Sleep Res. 2021 Feb;30(1):e13035. doi: 10.1111/jsr.13035. Epub 2020 Mar 25. PMID: 32212220.

 

Abstract

Depression is common in women with obstructive sleep apnea (OSA), but objective markers of depression have not yet been explored in such patients. We hypothesized that inflammation and antioxidant biomarkers may be associated with depression in a cohort of OSA women. We conducted a multicentre, cross-sectional study in 247 women diagnosed with moderate-to-severe OSA. Depression was assessed by the depression subscale of the Hospital Anxiety and Depression Questionnaire (HAD-D) and defined as a score ≥11. Associations between tumour necrosis factor α (TNFα), interleukin 6 (IL-6), C-reactive protein (CRP), intercellular adhesion molecule 1 (ICAM-1), catalase (CAT), superoxide dismutase (SOD) and brain-derived neurotrophic factor (BDNF) plasma levels and depression were assessed. The women had a median (25th-75th percentiles) age of 58 (51-65) years, body mass index (BMI) of 33.5 (29.0-38.3) Kg/m² , Epworth Sleepiness Scale (ESS) score of 10 (6-13) and apnea-hypopnea index (AHI) of 33.3 (22.8-49.3). Logistic regression analyses revealed that only IL6 levels were associated with the presence of depression (adjusted odds ratio [OR], 1.20; 95% confidence interval [CI], 1.08-1.34), whereas linear regression further confirmed that IL6 levels were significantly associated with HAD-D scores (β = .154; 95% CI, 0.03-0.30). Multivariate regression analysis showed that IL6 (OR, 1.22; 95% CI, 1.09-1.36), ESS (OR, 1.10; 95% CI 1.02-1.19) and physical activity <30 min/day (OR, 2.51; 95% CI, 1.25-5.05) were independent predictors of depression. Thus, we conclude that in a cohort of women with moderate-to-severe OSA, IL6 levels are independently associated with the presence of depression and correlate with depression scores. Low physical activity and higher ESS scores are also independent indicators of risk of depression in this population.