Tissue protection and endothelial cell signaling by 20-HETE analogs in intact ex vivo lung slices.

The capacity to follow cell type-specific signaling in intact lung remains limited. 20-hydroxyeicosatetraenoic acid (20-HETE) is an endogenous fatty acid that mediates signaling for a number of key physiologic endpoints in the pulmonary vasculature, including cell survival and altered vascular tone. We used confocal microscopy to identify enhanced reactive oxygen species (ROS) production in endothelial cell (EC)s in intact lung evoked by two stable analogs of 20-HETE, 20-5,14-HEDE (20-hydroxyeicosa-5(Z),14(Z)-dienoic acid) and 20-5,14-HEDGE (N-[20-hydroxyeicosa-5(Z),14(Z)-dienoyl]glycine). These analogs generated increased ROS in cultured pulmonary artery endothelial cells as well. 20-HETE analog treatment decreased apoptosis of pulmonary tissue exposed to hypoxia-reoxygenation (HR) ex vivo. Enhanced ROS production and apoptosis were confirmed by biochemical assays. Our studies identify physiologically critical, graded ROS from ECs in live lung tissue ex vivo treated with 20-HETE analogs and protection from HR-induced apoptosis. These methodologies create exciting possibilities for studying signaling by stable 20-HETE analogs and other factors in pulmonary endothelial and other lung cell types in their native milieu.

Skeletal Muscle Mitochondrial Dysfunction Is Present in Patients with CKD before Initiation of Maintenance Hemodialysis.

BACKGROUND AND OBJECTIVES: Patients with CKD suffer from frailty and sarcopenia, which is associated with higher morbidity and mortality. Skeletal muscle mitochondria are important for physical function and could be a target to prevent frailty and sarcopenia. In this study, we tested the hypothesis that mitochondrial dysfunction is associated with the severity of CKD. We also evaluated the interaction between mitochondrial function and coexisting comorbidities, such as impaired physical performance, intermuscular adipose tissue infiltration, inflammation, and oxidative stress. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Sixty-three participants were studied, including controls (n=21), patients with CKD not on maintenance hemodialysis (CKD 3-5; n=20), and patients on maintenance hemodialysis (n=22). We evaluated in vivo knee extensors mitochondrial function using 31P magnetic resonance spectroscopy to obtain the phosphocreatine recovery time constant, a measure of mitochondrial function. We measured physical performance using the 6-minute walk test, intermuscular adipose tissue infiltration with magnetic resonance imaging, and markers of inflammation and oxidative stress in plasma. In skeletal muscle biopsies from a select number of patients on maintenance hemodialysis, we also measured markers of mitochondrial dynamics (fusion and fission). RESULTS: We found a prolonged phosphocreatine recovery constant in patients on maintenance hemodialysis (53.3 [43.4-70.1] seconds, median [interquartile range]) and patients with CKD not on maintenance hemodialysis (41.5 [35.4-49.1] seconds) compared with controls (38.9 [32.5-46.0] seconds; P=0.001 among groups). Mitochondrial dysfunction was associated with poor physical performance (r=0.62; P=0.001), greater intermuscular adipose tissue (r=0.44; P=0.001), and increased markers of inflammation and oxidative stress (r=0.60; P=0.001). We found mitochondrial fragmentation and increased content of dynamin-related protein 1, a marker of mitochondrial fission, in skeletal muscles from patients on maintenance hemodialysis (0.86 [0.48-1.35] arbitrary units (A.U.), median [interquartile range]) compared with controls (0.60 [0.24-0.75] A.U.). CONCLUSIONS: Mitochondrial dysfunction is due to multifactorial etiologies and presents prior to the initiation of maintenance hemodialysis, including in patients with CKD stages 3-5.