Table 2.

List of biomarkers and analytical methods.

Type	Biomarker	Test	Supplier (Cat. #)	Matrix	Biological function	General health implications
Metabolic	α-amylase	Kinetic	Salimetrics (1-1902)	saliva	Major salivary enzyme that hydrolyzes polysaccharides to glucose and maltose.	Biomarker of sympathetic nervous system; elevated levels linked to stress (Nater and Rohleder 2009).
Metabolic	Uric acid	Kinetic	Salimetrics (1-3802)	serum	Product of metabolic breakdown of purine nucleotides.	Elevated levels linked to gout, kidney stones and diabetes (Dehghan et al. 2008); low levels may be linked to depression (Jimenez-Fernandez et al. 2015).
Metabolic	Low density lipoprotein (LDL)	Enzyme-linked immunosorbent assay (ELISA)	Cell Biolabs (STA-391)	serum	“Bad cholesterol”; lipoprotein synthesized in the liver; transports cholesterol to tissues; can be deposited in the walls of blood vessels and contribute to atherosclerosis.	Elevated serum LDL contributes to the pathogenesis of atherosclerosis (Hansson and Hermansson 2011).
Metabolic	High density lipoprotein (HDL)	ELISA	Cell Biolabs (STA-391)	serum	“Good cholesterol”; transports cholesterol from tissues to the liver.	HDL has vascular protective effects; reduces the risk of atherosclerosis (Luscher et al. 2014). High HDL in combination with low SAA is predictive of reduced mortality risk (Zewinger et al. 2015).
Metabolic	Serum amyloid A (SAA)	MSD V-plex vascular injury panel	MSD (K15198G-1)	serum	Family of apolipoproteins associated with HDL and secreted during acute phase of inflammation; involved in recruitment of immune cells to inflammatory sites.	High levels linked to inflammatory diseases, diabetes (Marzi et al. 2013), CVD and death (Johnson et al. 2004; Zamani et al. 2013).
Immune	C-reactive protein (CRP)	MSD V-plex vascular injury panel	MSD (K15198G- 1)	serum	Protein synthesized in the liver; enhances phagocytosis during acute phase reactions that promote inflammation.	Elevated in chronic inflammatory diseases; risk factor for CVD and death (Barron et al. 2015; Koenig et al. 1999; Zengin et al. 2015).
Immune	Vascular cell adhesion molecule 1 (VCAM-1)	MSD V-plex vascular injury panel	MSD (K15198G- 1)	serum	Protein consisting of immunoglobulin domains; expressed in blood vessels upon cytokine stimulation; promotes adhesion of lymphocytes to vascular endothelium.	Elevated levels linked to CVD and risk of death (Zamani et al. 2013).
Immune	Intercellular adhesion molecule 1 (ICAM-1)	MSD V-plex vascular injury panel	MSD (K15198G- 1)	serum	Immunoglobulin glycoprotein produced by vascular endothelium and leukocytes; induced by IL-1 and TNF; produces pro-inflammatory effects through cell signaling.	Elevated levels linked with chronic inflammation, diabetes (Gu et al. 2012), stroke and risk of death (Schnabel et al. 2013).
Immune	Interleukin (IL)-1β	MSD U-plex pro-inflammatory cytokines panel	MSD (K15053K- 1)	serum	Cytokine protein produced by activated macrophages; mediator of inflammatory responses; involved in cell proliferation, differentiation, and apoptosis.	Central regulator of stress response affecting levels of other stress biomarkers (Goshen and Yirmiya 2009); involved in pathogenesis of atherosclerosis (Hansson and Hermansson 2011).
Immune	IL-6	MSD U-plex pro-inflammatory cytokines panel	MSD (K15053K- 1)	serum	Cytokine produced by macrophages and T-cells; stimulates B cell and T cell differentiation in acute phase response to tissue damage; produces fever.	Drive production of reactant proteins, including CRP; elevated levels linked to major depressive disorder (Haapakoski et al. 2015) and higher risk of death in CVD patients (Zamani et al. 2013).
Immune	IL-8	MSD U-plex pro-inflammatory cytokines panel	MSD (K15053K- 1)	serum	Cytokine produced by macrophages; mediator of pro-inflammatory response; induces chemotaxis and phagocytosis by immune cells at infection sites.	Elevated levels linked with inflammation, obesity and increased risk of death (Cavusoglu et al. 2015).
Immune	TNF-α	MSD U-plex pro-inflammatory cytokines panel	MSD (K15053K- 1)	serum	Cytokine produced by macrophages; functions in systemic inflammation by evoking mediators of acute phase reactions as well as in tumor apoptosis.	Produces fever; used pharmacologically; elevated levels linked to autoimmune disorders and major depressive disorder (Haapakoski et al. 2015).
Immune	Fibrinogen	ELISA	Abcam (ab108842)	serum	Protein that synthesizes into fibrin in the liver; functions as a blood clotting factor that promotes coagulation.	Elevated levels linked to thrombosis, CVD, and increased risk of death (Barron et al. 2015; Kunutsor et al. 2016).
Immune	Myeloperoxidase (MPO)	ELISA	Abcam (ab119605)	serum	Peroxidase enzyme produced by activated neutrophils, monocytes and macrophages. Catalyzes the modification of LDL.	Elevated levels linked to coronary artery disease (Zakynthinos and Pappa 2009).
Neuroendocrine	Dehydroepiandrosterone (DHEA)	ELISA	Salimetrics (11202)	serum	Steroid hormone; precursor of sex hormones; suppresses inflammation; improves lipid metabolism; decreases insulin resistance; reduces oxidative brain damage.	Low levels linked to coronary heart disease (Tivesten et al. 2014), immune disorder and increased risk of death (Ohlsson et al. 2015).
Neuroendocrine	Epinephrine	ELISA	Eagle Biosciences (AND31-K03)	serum	Catecholamine produced by adrenal glands and brain; increases heart rate and glucose levels, decreases digestive and immune functions during “fight- or-flight” response.	Increased in acute stress and exercise; used to treat cardiac arrest and allergic reactions. Inconsistent reports on associations with burnout and depression; high levels indicative of AL in previous studies (Juster et al. 2010; Juster et al. 2011).
Neuroendocrine	Norepinephrine	ELISA	Eagle Biosciences (AND31-K03)	serum	Catecholamine produced by the brain; increases blood pressure, constricts blood vessels, and modulates brain activities during “fight-or-flight” response.	Increases alertness, heart rate and blood pressure; increased in stress (Gu et al. 2016); high level can be predictive of CVD (Yufu et al. 2014); low levels linked with depression (Moret and Briley 2011).
Neuroendocrine	Dopamine	ELISA	Eagle Biosciences (AND31-K03)	serum	Catecholamine produced in the brain and adrenal glands; involved in motivation, voluntary movement, and cognition; increases blood pressure and heart rate.	Major role in reward pathways in brain; used to treat cardiac arrest; low levels linked to depression (Dunlop and Nemeroff 2007; Kapur and Mann 1992).