Table 3.

Frailty biomarker studies in rodents

Biomarker	Animal model	Frailty assessment/model	Findings	Type of biomarker	Reference
MCP-1	Wild-type and Ercc1−/Δ and Bubr1H/H mouse models	Frailty not assessed	Increased with age and accelerated in progeria models	Serum	(Yousefzadeh et al. 2018)
ALT, ALP	Male C57BL/6 mice 24 months	Mouse Clinical Frailty Index	Lower levels associated with increasing FI Score	Serum	(Kane et al. 2016, 2017)
HR, HR variability	Male C57BL/6 mice 24 months	Mouse Clinical Frailty Index	Lower HR and lower variability associated with increasing FI Score	Non-invasive cuff assessment	(Kane et al. 2017)
Total protein, albumin	Male C57BL/6 mice 19–23 months	Mouse Clinical Frailty Index	Lower levels with increased FI score	Serum	(Kane et al. 2016)
IL-6, IL-12p40, IL-9, IFN-γ	Male and female C57BL/6 mice 17–23 months	Mouse Clinical Frailty Index	Sex differences: IL-6, IL-9 and IFN-γ increased with FI score in females and IL-12p40 increased with FI score in males.	Serum	(Kane et al. 2018)
IL-6, IL-lβ, TNF-α, IFN-γ, KC	IL-10 knock-out mice	Frailty not assessed	Higher in knock-out than in wild-type mice.	Serum	(Walston et al. 2008; Ko et al. 2012)
G-CSF, Eotaxin	Sodi knock-out mice	Frailty not assessed	Higher in knock-out than in wild-type mice.	Serum	(Deepa et al. 2017)

CML, ; BDNF, ; MCP-1, monocyte chemoattractant protein 1; ALT, alanine aminotransferase; ALP, alkaline phosphatase; HR, heart rate; IL, interleukin; IFN, interferon; TNF, tumor necrosis factor; KC, keratinocyte chemoattractant; G-CSF, granulocyte colony-stimulating factor; sod1, superoxide dismutase 1; FI, frailty index.