Khosla, Sundeep

Senescent cells have detrimental effects across tissues with aging but may have beneficial effects on tissue repair, specifically on skin wound healing. However, the potential role of senescent cells in fracture healing has not been defined. Here, we performed an in silico analysis of public mRNAseq data and found that senescence and senescence-associated secretory phenotype (SASP) markers increased during fracture healing. We next directly established that the expression of senescence biomarkers increased markedly during murine fracture healing. We also identified cells in the fracture callus that displayed hallmarks of senescence, including distension of satellite heterochromatin and telomeric DNA damage; the specific identity of these cells, however, requires further characterization. Then, using a genetic mouse model ( Cdkn2a LUC ) containing a Cdkn2a Ink4a -driven luciferase reporter, we demonstrated transient in vivo senescent cell accumulation during callus formation. Finally, we intermittently treated young adult mice following fracture with drugs that selectively eliminate senescent cells (‘senolytics’, Dasatinib plus Quercetin), and showed that this regimen both decreased senescence and SASP markers in the fracture callus and significantly accelerated the time course of fracture healing. Our findings thus demonstrate that senescent cells accumulate transiently in the murine fracture callus and, in contrast to the skin, their clearance does not impair but rather improves fracture healing.

ABSTRACT The surrogate threshold effect (STE) is defined as the minimum treatment effect on a surrogate that is reliably predictive of a treatment effect on the clinical outcome. It provides a framework for implementing a clinical trial with a surrogate endpoint. The aim of this study was to update our previous analysis by validating the STE for change in total hip (TH) BMD as a surrogate for fracture risk reduction; the novelty of this study was this validation. To do so, we used individual patient data from 61,415 participants in 16 RCTs that evaluated bisphosphonates (nine trials), selective estrogen receptor modulators (four trials), denosumab (one trial), odanacatib (one trial), and teriparatide (one trial) to estimate trial-specific treatment effects on TH BMD and all, vertebral, hip, and nonvertebral fractures. We then conducted a random effects meta-regression of the log relative fracture risk reduction against 24-month change in TH BMD, and computed the STE as the intersection of the upper 95% prediction limit of this regression with the line of no fracture reduction. We validated the STE by checking whether the number of fractures in each trial provided 80% power and determining what proportion of trials with BMD changes ≥ STE reported significant reductions in fracture risk. We applied this analysis to (i) the trials on which we estimated the STE; and (ii) trials on which we did not estimate the STE. We found that the STEs for all, vertebral, hip, and nonvertebral fractures were 1.83%, 1.42%, 3.18%, and 2.13%, respectively. Among trials used to estimate STE, 27 of 28 were adequately powered, showed BMD effects exceeding the STE, and showed significant reductions in fracture risk. Among the validation set of 11 trials, 10 met these criteria. Thus STE differs by fracture type and has been validated in trials not used to develop the approach. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Abstract The burden of senescent cells (SnCs), which do not divide but are metabolically active and resistant to death by apoptosis, is increased in older adults and those with chronic diseases. These individuals are also at the greatest risk for morbidity and mortality from SARS‐CoV‐2 infection. SARS‐CoV‐2 complications include cytokine storm and multiorgan failure mediated by the same factors as often produced by SnCs through their senescence‐associated secretory phenotype (SASP). The SASP can be amplified by infection‐related pathogen‐associated molecular profile factors. Senolytic agents, such as Fisetin, selectively eliminate SnCs and delay, prevent, or alleviate multiple disorders in aged experimental animals and animal models of human chronic diseases, including obesity, diabetes, and respiratory diseases. Senolytics are now in clinical trials for multiple conditions linked to SnCs, including frailty; obesity/diabetes; osteoporosis; and cardiovascular, kidney, and lung diseases, which are also risk factors for SARS‐CoV‐2 morbidity and mortality. A clinical trial is underway to test if senolytics decrease SARS‐CoV‐2 progression and morbidity in hospitalized older adults. We describe here a National Institutes of Health‐funded, multicenter, placebo‐controlled clinical trial of Fisetin for older adult skilled nursing facility (SNF) residents who have been, or become, SARS‐CoV‐2 rtPCR‐positive, including the rationale for targeting fundamental aging mechanisms in such patients. We consider logistic challenges of conducting trials in long‐term care settings in the SARS‐CoV‐2 era, including restricted access, consent procedures, methods for obtaining biospecimens and clinical data, staffing, investigational product administration issues, and potential solutions for these challenges. We propose developing a national network of SNFs engaged in interventional clinical trials.

Wnt signaling plays a central role in the development of bone forming osteoblasts and bone remodeling. This study analyzed Wnt‐10b control of gene expression throughout osteoblast differentiation. Genes regulated by Wnt‐10b were identified by analyzing five mouse osteoblast lines (C3H10T1/2, ST‐2, bone marrow stromal cells, MC‐3T3, and calvarial osteoblasts). These cell lines were exposed to media from a Wnt‐10b producing cell line via a transwell system. mRNA levels of 32 osteoblastic, Wnt and BMP responsive genes were quantified by qPCR. Several genes were consistently up/down regulated, representing different stages of osteoblast commitment and differentiation. In the second part of the study, C3H10T1/2 cells were treated with BMP2 osteoblast differentiation media to stimulate the growth of osteoblastic cells. The control and Wnt‐10b treated cells were harvested at 0, 6, 9, 12, or 15 days to observe the effect of Wnt‐10b during differentiation. Analysis of 64 genes showed two known Wnt‐3a targets, complement component 3 (C3) and chemokine ligand 16 (Cxcl16), were highly regulated by Wnt‐10b. This study indentifies a number of important genes that are regulated by Wnt‐10b during osteoblast differentiation. This project was funded by the Mayo Graduate School and the Summer Undergraduate Research Fellowship.

Senescent cells exacerbate COVID-19 Cellular senescence is a state elicited in response to stress signals and is associated with a damaging secretory phenotype. The number of senescent cells increases with advanced age and this in turn drives age-related diseases. Camell et al. show that senescent cells have an amplified inflammatory response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (see the Perspective by Cox and Lord). This response is communicated to nonsenescent cells, suppressing viral defense mechanisms and increasing the expression of viral entry proteins. In old mice infected with a SARS-CoV-2–related virus, treatment with senolytics to reduce the senolytic cell burden reduced mortality and increased antiviral antibodies. Science , abe4832, this issue p. eabe4832 ; see also abi4474, p. 281

Abstract Background: Glucocorticoid-induced myopathy is well-recognized in overt Cushing syndrome (CS), but the impact of mild cortisol secretion on muscle is unclear. Recent data suggest that patients with mild autonomous cortisol secretion (MACS) are frailer and report more weakness than patients with non-functioning adrenal adenomas. We hypothesized that MACS is associated with 1) objective measures of impaired muscle strength and performance and 2) increased tissue accumulation of advanced glycation end products (AGEs), a measure of accelerated aging. Aim: To determine the effect of MACS on muscle mass, strength, performance, and tissue accumulation of AGEs. Methods: We conducted a cross-sectional analysis as part of an ongoing cohort study in patients with MACS compared to age and sex-matched referent subjects without cortisol excess. MACS was defined as serum cortisol >1.8 mcg/dL after the 1 mg overnight dexamethasone suppression test (DST), in the absence of overt signs and symptoms of CS. We measured hand grip strength with hand grip dynamometer and evaluated functional performance on the timed up and go test, 6 minute walk test, and gait speed assessment. Tissue accumulation of AGEs was measured with point-of-care AGE reader. Appendicular lean mass was calculated and adjusted for height in participants who underwent body composition scan. Results: A total of 23 patients with MACS and 23 age and sex-matched referent subjects without cortisol excess were enrolled. The median age of diagnosis was 63 years (range, 51–81), and 26 (56%) were women. In the MACS cohort, median cortisol following 1 mg DST was 2.6 µg/dL (range, 1.9–13.0), median DHEA-S 37 µg/dL (range, 5.0- 141.0), and median ACTH 8.5 pg/mL (range, 5.0–38.0). Patients with MACS had lower hand grip strength (median 29.3 vs. 32.5 kg, p=0.052), slower gait speed (median 1.1 vs. 1.4 m/s, p=0.001), covered less distance during the 6 minute walk test (median 453 vs. 510 m, p=0.001), and took longer to complete the timed up and go test (median 10.1 vs. 8.6 s, p=0.04) than referent subjects without cortisol excess. Accumulation of AGEs was higher in patients with MACS (median 2.9 vs. 2.4, p=0.01). No significant difference was observed in appendicular lean mass (n=19 pairs, 7.8 vs. 7.5 kg/m2, p=0.57). Conclusions: MACS is associated with decreased muscle strength and performance without a significant change in muscle mass, suggesting poor muscle quality. We also observed increased tissue accumulation of AGEs in MACS patients, consistent with our hypothesis of MACS-induced accelerated aging. These findings may help explain the increased frailty observed in MACS, and suggest muscle assessment be considered in all patients with autonomous cortisol secretion. Further studies should examine the impact of muscle and functional impairments on morbidity in MACS, and its possible reversal with either a structured exercise intervention or adrenalectomy.

Abstract Background: Frailty is characterized by an increased vulnerability and a decline in physiological reserve. Frailty has been previously linked to cortisol concentrations and blunted diurnal cortisol secretion. Our objective was to determine the association of urine steroid metabolome and its diurnal variation with frailty and prefrailty in older adults. Methods: Cross-sectional study of community-dwelling adults ≥ 50 years. Participants with adrenal disorders, end-stage renal or liver disease, on exogenous steroids or drugs affecting steroid metabolism were excluded. All participants completed day and night separate urine collection. Frailty was assessed using a phenotype model (weight loss, exhaustion, grip strength, low physical activity, and slow walking pace). Participants were characterized as frail if they met at least three criteria, pre-frail if they fulfilled one or two criteria, and robust if no criteria were met. Urine samples were analyzed with the liquid-chromatography, high-resolution, accurate-mass mass spectrometry for 25 urine steroid metabolites. Results: Of 119 participants, 60 (50.4%) were women, without sex differences in age or education status. On frailty assessment, 5 (4.2%) participants were frail and 33 (27.7%) were prefrail, with equal sex distribution. Urine steroid metabolome analysis demonstrated 21/25 steroids were higher in men vs women. In an age adjusted model, presence of prefrailty or frailty was associated with a higher ratio of total cortisol metabolites/total androgen metabolites (TCM/TAM) in men (estimate 0.64, P-value= 0.0004), but not in women. In men, after adjusting for age, among cortisol metabolites, lower day to night ratio of 5α-Tetrahydrocortisol (estimate -0.36, P-value= 0.0419) and β-Cortol (estimate -0.35, P-value= 0.0238) were associated with frail or prefrail phenotype. After adjusting for age, higher ratio of TCM/TAM was associated lower gait speed in men (estimate -1.2, P-value= 0.046) and women (estimate -3.9, P-value= 0.012); and lower hand grip strength in men (estimate -0.04, P-value= 0.046) but not in women. Conclusion: We showed that a higher glucocorticoid to androgen ratio and a flattened circadian steroid variation were associated with presence of frail or prefrail phenotype in men. Further studies should examine the role of steroid metabolism and HPA axis impairment, and the associated sex differences, in the functional decline in aging population.

Abstract Background: Elevated urine cortisol (<1% of urinary steroid metabolome) was reported to predict future development of dementia. Our objective was to determine the association of urine steroid metabolome and its diurnal variation with cognitive function in men and women. Methods: Cross-sectional study of community-dwelling adults ≥ 50 years. Participants with adrenal disorders, end-stage renal or liver disease, on exogenous steroids or drugs affecting steroid metabolism were excluded. All participants completed day and night separate urine collection. A series of seven IPad-based tests using the National Institute of Health Toolbox Cognition Battery were administered to evaluate five key domains; performance was reported using fully corrected T-scores for age, sex, education, and race with a national normative mean of 50. T-scores were generated for the two summary measures: 1) fluid cognition (includes executive function, episodic memory, working memory, and processing speed), and 2) total composite (composite of fluid and language score). Urine samples were analyzed with the liquid-chromatography, high-resolution, accurate-mass mass spectrometry for 25 urine steroid metabolites. Results: Of 109 participants, 56 (51%) were women, and age and educational status were similar in men and women. On cognitive assessment, men and women had similar median composite cognition (T-score of 53 vs 54, p=0.74) and fluid cognition (T-score of 53 vs 51, p-value 0.96). Urine steroid metabolome analysis demonstrated 21/25 steroids were higher in men vs women. In both women and men, the ratio of total cortisol metabolites/total androgen metabolites (TCM/TAM) was associated with lower fluid cognition (women: ρ= -0.34, p=0.01, men: ρ= -0.43, p=0.001) and composite cognition (women: ρ= -0.27, p=0.04, men: ρ= -0.39, p=0.004). Higher ratio of day to night TCM were associated with a better fluid cognition in men (ρ= 0.35, p=0.01), but not in women (ρ= -0.11, p=0.41). Steroid ratios suggesting a relative enzymatic deficiency of 5α-Reductase type 2 was associated with lower fluid cognition in women (ρ= -0.29, p=0.03). In men, the fluid composite score was associated with a relative deficiency in 21-Hydroxylase (ρ= 0.42, p=0.002), 3β-Hydroxysteroid dehydrogenase (ρ= 0.43, p=0.001), and P450oxidoreductase (ρ= -0.35, p=0.01). Conclusion: We showed that a higher glucocorticoid to androgen ratio and a flattened circadian steroid variation were associated with lower global and fluid cognition score. Steroid ratios reflecting steroidogenesis enzymatic activity demonstrated sex differences in relation to cognition. Additional studies should examine whether the steroid fingerprint associated with lower cognition is predictive of a future dementia onset.

Abstract Background: Cognitive deficits in memory, language, and executive function have been described in Cushing’s syndrome, but the impact of mild cortisol secretion on cognition is unclear. Rather than overt hypercortisolism, mild autonomous cortisol secretion (MACS) is typically associated with abnormal circadian cortisol production. Aim: To characterize the effect of MACS on cognitive performance. Methods: We conducted a cross-sectional analysis as part of an ongoing cohort study in patients with MACS compared to age and sex-matched referent subjects without cortisol excess. MACS was defined as serum cortisol concentration >1.8 mcg/dL after the 1 mg overnight dexamethasone suppression test (DST), in the absence of signs and symptoms of overt Cushing syndrome. We used the National Institute of Health Toolbox Cognition Battery to assess cognitive performance. A series of seven IPad-based tests were administered to evaluate five key domains: 1) executive function, 2) episodic memory, 3) working memory, 4) language, and 5) processing speed. Performance was reported using fully corrected T-scores for age, sex, education, and race with a normative mean of 50 and a standard deviation of 10. T-scores were generated for the individual components as well as three summary measures: 1) fluid cognition (includes executive function, episodic memory, working memory, and processing speed), 2) crystallized cognition (includes language), and 3) total cognition (composite of fluid and crystalized cognition). Results: A total of 23 patients with MACS and 23 age and sex-matched referent subjects without cortisol excess were enrolled. The median age of diagnosis was 63 years (range, 51–81), and 26 (56%) were women. In the MACS cohort, median cortisol following 1 mg DST was 2.6 ug/dL (range, 1.9–13.0) with median ACTH of 8.5 pg/mL (range, 5.0–38.0) and median DHEA-S of 37 mcg/dL (range, 5.0- 141.0). On cognitive assessment, patients with MACS had lower total cognition (T-scores 50 vs. 54, p=0.05) and fluid cognition (T-scores 48 vs. 53, p=0.01) composite scores compared to referent subjects without cortisol excess. In particular, patients with MACS performed worse on tests of executive function (Dimensional Change Card Sort: T-scores 55 vs. 63, p= 0.02 and Flanker Inhibitory Control and Attention: T-scores 45 vs. 52, p=0.01). There were no significant differences observed in the remaining individual domains of language, processing speed, working memory, and episodic memory, or crystallized cognition. Conclusions: MACS is associated with impaired total cognition, and in particular, executive function and fluid cognition. These findings suggest that patients with MACS are susceptible to cortisol-mediated changes in the brain. Additional studies should examine the contribution of neuropsychiatric symptoms on cognition in MACS, and possible improvement following treatment for cortisol excess.

Objective Several small studies reported increased prevalence and incidence of asymptomatic vertebral fractures in patients with non-functioning adrenal adenomas and adenomas with mild autonomous cortisol secretion. However, the risk of symptomatic fractures at vertebrae, and at other sites remains unknown. Our objective was to determine the prevalence and incidence of symptomatic site-specific fractures in patients with adrenal adenomas. Design Population-based cohort study, Olmsted County, Minnesota, USA, 1995–2017. Methods Participants were the patients with adrenal adenoma and age/sex-matched referent subjects. Patients with overt hormone excess were excluded. Main outcomes measures were prevalence and incidence of bone fractures. Results Of 1004 patients with adrenal adenomas, 582 (58%) were women, and median age at diagnosis was 63 years (20–96). At the time of diagnosis, patients had a higher prevalence of previous fractures than referent subjects (any fracture: 47.9% vs 41.3%, P = 0.003, vertebral fracture: 6.4% vs 3.6%, P = 0.004, combined osteoporotic sites: 16.6% vs 13.3%, P = 0.04). Median duration of follow-up was 6.8 years (range: 0–21.9 years). After adjusting for age, sex, BMI, tobacco use, prior history of fracture, and common causes of secondary osteoporosis, patients with adenoma had hazard ratio of 1.27 (95% CI: 1.07–1.52) for developing a new fracture during follow up when compared to referent subjects. Conclusions Patients with adrenal adenomas have higher prevalence of fractures at the time of diagnosis and increased risk to develop new fractures when compared to referent subjects.