TIMP1 and chronic obstructive pulmonary disease: Proteins included in the derivation of DNAmGrimAge such as tissue inhibitor metalloproteinases 1 (TIMP-1) have previously demonstrated significant increases in both the sputum43 and blood44 of individuals with COPD compared to control individuals, perhaps one reason why DNAmGrimAge performs well in both airway and blood compartments in relation to COPD.