Table 2.

Shared mechanisms between COPD and mood disorders.

Mechanisms	References
Inflammation
Elevated levels of inflammatory mediators such as CRP, fibrinogen, IL-6, IL-8, IL-13, MCP-1, TNF-α, and TNF-α receptor-1 were detected in the plasma of COPD patients.	[64,65,66,67,68,69]
Inflammatory cytokines such as CRP, IL-1, IL-6, IFN-γ, TNF-α, and TNF-α receptor 1 were associated with depressive symptoms in COPD.	[65,70,71,72,73]
Oxidative stress
Decreased levels of reduced glutathione, as well as an increased amount of 8-isoprostane, were detected in COPD patients compared to controls.	[99]
Genetic polymorphisms associated with extracellular SOD as well as their expression in the sputum are frequently found in COPD patients.	[97,98]
Downregulation of Nrf2 and Nrf2-related, heme oxygenase-1, and glutamate-cysteine ligase catalytic subunit in the peripheral blood mononuclear cells were detected in COPD patients.	[99]
Reduced pulmonary expression of FOXO3a was reported in COPD patients.	[100]

COPD: Chronic obstructive pulmonary disease, CRP: C-reactive protein, FOXO: Fork-head box O, IL: Interleukin, IFN-γ: Interferon-γ, MCP: Monocyte chemoattractant protein, Nrf: Nuclear factor erythroid 2-related factor, TNF-α: Tumor necrosis factor-α, SOD: Superoxide dismutase.