Selected Biomarkers of Depression: What Are the Effects of Cytokines and Inflammation?

Abstract

Depression is one of the leading mental illnesses worldwide and lowers the quality of life of many. According to WHO, about 5% of the worldwide population suffers from depression. Newer studies report a staggering global prevalence of 27.6%, and it is rising. Professionally, depression belonging to affective disorders is a psychiatric illness, and the category of major depressive disorder (MDD) comprises various diagnoses related to persistent and disruptive mood disorders. Due to this fact, it is imperative to find a way to assess depression quantitatively using a specific biomarker or a panel of biomarkers that would be able to reflect the patients’ state and the effects of therapy. Cytokines, hormones, oxidative stress markers, and neuropeptides are studied in association with depression. The latest research into inflammatory cytokines shows that their relationship with the etiology of depression is causative. There are stronger cytokine reactions to pathogens and stressors in depression. If combined with other predisposing factors, responses lead to prolonged inflammatory processes, prolonged dysregulation of various axes, stress, pain, mood changes, anxiety, and depression. This review focuses on the most recent data on cytokines as markers of depression concerning their roles in its pathogenesis, their possible use in diagnosis and management, their different levels in bodily fluids, and their similarities in animal studies. However, cytokines are not isolated from the pathophysiologic mechanisms of depression or other psychiatric disorders. Their effects are only a part of the whole pathway.

Inflammatory Blood Signature Related to Common Psychological Comorbidity in Chronic Pain

“…This line of research suggests that the immune system is involved in both central and peripheral sensitization of pain neurons [ 2 ], in the development and priming of the pain system [ 1 ], in sex differences in prevalence [ 12 , 13 ], and in the bidirectional interplay between pain and psychological wellbeing [ 3 , 4 ]. Systemic low-grade inflammation has been indicated in several pain diagnoses [ 14 , 15 , 16 , 17 , 18 ], similar to the findings for inflammation and depression [ 19 , 20 , 21 , 22 ]. Pain diagnoses are generally symptom-based due to a lack of clear pathophysiological factors and reliable and relevant biomarkers.…”

Mechanism of Chaihu Longgu oyster adjusted decoction for the treatment of depression based on network pharmacology and molecular docking technology

“…It is mainly produced by activated macrophages and plays a role in regulating immune cells. Abnormal TNF expression is linked with various human diseases, including Alzheimer's disease, cancer, and major depression (40)(41)(42). Many major neuropathologic features of TNF or IL-6 in the central nervous system are similar to those found in cytokine-related immune inflammatory neurological diseases in humans (42).…”

Pioneering Changes in Psychiatry: Biomarkers, Psychedelics, and AI

“…Cytokines, small peptides with a significant role in inflammation and cellular processes, have been strongly linked to stress and depression. Specific cytokines, such as interleukin-1 beta (IL-1β), show increased presence in individuals under acute or chronic stress, pointing toward a potential link to depressive disorders . Research suggests that individuals experiencing depression or stress display increased cytokine concentrations, which often correspond to the severity of their condition.…”

“…Additionally, specific genetic variations, such as those found in the IL1B gene, may increase susceptibility to depression under certain conditions, such as multiple sclerosis. Figure shows that this complex interplay of various biomarkers underscores the intricate biology of psychiatric disorders and their potential therapeutic targets …”

“…Role of cytokines groups in stress and depression response Adapted with permission from ref . Copyright 2023 by MPDI under the terms of a Creative Commons CC-BY license.…”