The mitochondrial function of peripheral blood mononuclear cells in frail older patients.

BACKGROUND: Frailty increases the incidence of geriatric syndromes and even the risk of death in old adults. However, the diagnostic criteria for frailty are inconsistent because of complex pathological processes and diverse clinical manifestations. To determine the effective biomarker and recognize frail status early, we investigated the correlation of mitochondrial morphology and function of human peripheral blood mononuclear cells (PBMCs) with frailty status in older adults. METHODS: This Cross-sectional study followed 393 participants (aged 25-100 years, female 31.04 %) from the First Affiliated Hospital of Nanjing Medical University. The frailty status of subjects was assessed by the physical frailty phenotype (PFP) scale. We analyzed mitochondria functions including mitochondria copy number (mtDNAcn), the mRNA expressions of mitochondrial dynamics-related genes mitofusin 1(MFN1), mitofusin 2(MFN2), optic atrophy protein-1(OPA1), fission protein-1(FIS1) and dynamin-related protein 1(DRP1), mitochondrial oxidative respiration and reactive oxygen species(ROS) levels in PBMCs. Mitochondria morphology, size, and number were observed by transmission electron microscopy (TEM). RESULTS: After adjustment for sex and BMI, mtDNAcn, the mRNA expression of FIS1, mitochondrial respiratory function (proton leak, maximum oxygen consumption, and respiratory reserve) and ROS level were significantly correlated with age (P = 0.031, 0.030, 0.042, 0.003, 0.002, 0.022, respectively). After correcting for age, sex, and BMI, mtDNAcn and the mRNA expression of OPA1 were correlated with 4 m gait speed respectively (P = 0.003, 0.028, respectively). Compared with non-frail people, mtDNAcn, the mRNA expression of MFN1, mitochondrial basal respiration, proton leak, maximum oxygen consumption, ATP production and space capacity were significantly decreased in frail older adults (P = 0.013, 0.036, 0.026, 0.024, 0.012, 0.029, 0.032, 0.020, respectively). ROS levels were significantly increased in the frail group (P = 0.016). Compared with non-frail people, the number, length, and perimeter, area of mitochondria were reduced in frail group under TEM (all P < 0.001). CONCLUSION: Mitochondrial dysfunctions (decreased mtDNAcn, impaired mitochondrial morphology, imbalanced mitochondrial dynamic, impaired mitochondrial respiratory function, and increased ROS levels) were significantly correlated with frail status.

Metabolic syndrome and its association with components of sarcopenia in older community-dwelling Chinese.

Aging and obesity contribute to muscle dysfunction. This study aimed to determine the cross-sectional associations between components of metabolic syndrome (MetS) and sarcopenia in 251 older community-dwelling Chinese. The total fat-free mass was measured by dual-energy X-ray absorptiometry, muscle strength (handgrip strength) by a handheld dynamometer, physical performance by 4-meter walk, 5-time chair stand test, and the short physical performance battery (SPPB). MetS was defined using the International Diabetes Federation (IDF) criteria. The participants with MetS had a higher appendicular skeletal muscle mass (ASM) and relative ASM (RASM). The males with MetS had higher handgrip strength, and the females with MetS had higher SPPB scores. After adjusting for age and body mass index, the participants with an increased waist circumference had a higher ASM, and those with increased diastolic blood pressure (DBP) also had higher handgrip strength. The males with elevated fasting blood glucose (FBG) levels had a lower gait speed. Components of MetS, such as DPB and FBG, were associated with muscle strength and physical performance in older adults. These results suggest that muscle strength and function should be considered in treating older adults with MetS.