Proteomic Interrogation of the Acute Response to Muscle Damage in Untrained Middle Aged and Older Females

Blunted regenerative responses to muscle damage with aging are linked to inflammatory signaling and satellite cell dynamics; however, most evidence is derived from males and is limited to targeted assays of bulk muscle tissue and/or circulating biomarkers. Here, we focused on middle-aged and older females and leveraged multi-compartment proteomics to identify responses to modest muscle damage across myofibrillar (MYOF), sarcoplasmic (SARCO), and serum compartments. Sixteen females (mean age = 61±8 years) had vastus lateralis biopsies and serum collected before (PRE) and 24 h after (POST) a resistance loading protocol that induced modest muscle damage (72.9% increase in serum creatine kinase activity). SARCO and MYOF fractions were separated using differential centrifugation, and proteomics was performed on three compartments using a nanoparticle capture approach followed by mass spectrometry, yielding 9,059 proteins in SARCO, 4,334 in MYOF, and 3,964 in serum. The protocol produced 90 differentially abundant (DA) proteins in SARCO (61 up, 29 down), 39 in MYOF (27 up, 12 down), and 124 in serum (34 up (9 muscle-specific), 90 down). DA proteins minimally overlapped across compartments. Enrichment analyses pointed primarily to translation-related processes in MYOF and contractile processes in serum. Pathway Level Information ExtractoR performed on all DA proteins identified multi-compartment biocircuits linked to membrane trafficking, vesicle mediated transport, neutrophil degranulation, and viral infection. Viral infection-related proteins correlated with body weight and body fat, while vesicle mediated transport-related proteins correlated with serum creatine kinase activity. This analysis reveals novel biocircuitry of modest muscle damage in middle-aged and older females.