LeBrasseur, Nathan K.

Abstract Supplemental O2 (hyperoxia; 30–90% O2) is a necessary intervention for premature infants, but it contributes to development of neonatal and pediatric asthma, necessitating better understanding of contributory mechanisms in hyperoxia-induced changes to airway structure and function. In adults, environmental stressors promote formation of senescent cells that secrete factors (senescence-associated secretory phenotype), which can be inflammatory and have paracrine effects that enhance chronic lung diseases. Hyperoxia-induced changes in airway structure and function are mediated in part by effects on airway smooth muscle (ASM). In the present study, using human fetal ASM cells as a model of prematurity, we ascertained the effects of clinically relevant moderate hyperoxia (40% O2) on cellular senescence. Fetal ASM exposed to 40% O2 for 7 days exhibited elevated concentrations of senescence-associated markers, including β-galactosidase; cell cycle checkpoint proteins p16, p21, and p-p53; and the DNA damage marker p-γH2A.X (phosphorylated γ-histone family member X). The combination of dasatinib and quercetin, compounds known to eliminate senescent cells (senolytics), reduced the number of hyperoxia-exposed β-galactosidase–, p21-, p16-, and p-γH2A.X–positive ASM cells. The senescence-associated secretory phenotype profile of hyperoxia-exposed cells included both profibrotic and proinflammatory mediators. Naive ASM exposed to media from hyperoxia-exposed senescent cells exhibited increased collagen and fibronectin and higher contractility. Our data show that induction of cellular senescence by hyperoxia leads to secretion of inflammatory factors and has a functional effect on naive ASM. Cellular senescence in the airway may thus contribute to pediatric airway disease in the context of sequelae of preterm birth.

Abstract Rationale Frailty represents an increased vulnerability to adverse health outcomes. The frailty phenotype conceptual model (three or more patient attributes of wasting, exhaustion, low activity, slowness, and weakness) is associated with increased morbidity and mortality in geriatric populations. Objectives Our objective was to describe the risks associated with frailty in patients with chronic obstructive pulmonary disease. Methods Data from the National Emphysema Treatment Trial (NETT) were retrospectively analyzed. The frailty phenotype conceptual model was operationalized as three or more frailty parameters (a body mass index decrease of ≥5% over 12 months, self-reported exhaustion, low 6-minute walk distance, or physical activity or respiratory muscle strength in the lowest quartile). Frail participants were compared with participants with two or fewer frailty parameters. Participants were followed starting 12 months after NETT randomization (to minimize surgical effect) for 24 months. Univariate, multivariate, Kaplan-Meier, and Cox proportional hazard analyses were performed, adjusting for treatment arm, age, modified Medical Research Council dyspnea scale, sex, and baseline forced expiratory volume in 1 second (FEV1). Multiple imputation was used for missing values. Results The participants (N = 902) were predominantly white (94.5%) males (59.5%), with a median age of 67 years (interquartile range, 63–70 yr) and a median FEV1% predicted of 26 (interquartile range, 20–33). Six percent of the participants (95% confidence interval [CI], 4.5 to 7.6) were frail. The incidence rate of frailty was 6.4 per 100 person-years. Frail participants reported significantly worse disease-specific and overall quality of life by St. George’s Respiratory Questionnaire total score (mean difference of 11.6; 95% CI, 7.6 to 15.6; P < 0.001), mental composite on Medical Outcomes Survey Short Form-36 (mean difference −6.8; 95% CI, −10.0 to −3.6; P < 0.001), and physical composite scores on Medical Outcomes Survey Short Form-36 (mean difference −16.7; 95% CI, −21.3 to −12.1; P = 0.001). Frail participants had an increased rate of hospitalization (adjusted hazard ratio, 1.6; 95% CI, 1.1 to 2.5; P = 0.02) and an adjusted increase in hospital use of 8.0 days (95% CI, 4.4 to 11.6; P < 0.001) compared with nonfrail participants. Frail participants had a higher mortality rate (adjusted hazard ratio, 1.4; 95% CI, 0.97 to 2.0; P = 0.07). Conclusions Among adults with chronic obstructive pulmonary disease, our measure of frailty (modified from the Fried frailty phenotype) was associated with incident and longer-duration hospitalization, and with poor quality of life.

Bilateral oophorectomy in premenopausal women is a unique condition causing the abrupt and premature loss of ovarian hormones, primarily estrogen. Bilateral oophorectomy causes an alteration of several fundamental aging processes at the cellular, tissue, organ, and system levels, leading to multimorbidity, frailty, and reduced survival. However, many questions remain unanswered.

Summary A serum biomarker of biological versus chronological age would have significant impact on clinical care. It could be used to identify individuals at risk of early‐onset frailty or the multimorbidities associated with old age. It may also serve as a surrogate endpoint in clinical trials targeting mechanisms of aging. Here, we identified MCP ‐1/ CCL 2, a chemokine responsible for recruiting monocytes, as a potential biomarker of biological age. Circulating monocyte chemoattractant protein‐1 ( MCP ‐1) levels increased in an age‐dependent manner in wild‐type ( WT ) mice. That age‐dependent increase was accelerated in Ercc1 −/Δ and Bubr1 H/H mouse models of progeria. Genetic and pharmacologic interventions that slow aging of Ercc1 −/Δ and WT mice lowered serum MCP ‐1 levels significantly. Finally, in elderly humans with aortic stenosis, MCP ‐1 levels were significantly higher in frail individuals compared to nonfrail. These data support the conclusion that MCP ‐1 can be used as a measure of mammalian biological age that is responsive to interventions that extend healthy aging.