Low-Magnitude Mechanical Signals Combined with Zoledronic Acid Reduce Musculoskeletal Weakness and Adiposity in Estrogen-Deprived Mice

AUTHORS

Gabriel M. Pagnotti, Trupti Trivedi, Laura E. Wright, Sutha K. John, Sreemala Murthy, Ryan R. Pattyn, Monte S. Willis, Yun She, Sukanya Suresh, William R. Thompson, Clinton T. Rubin, Khalid S. Mohammad, Theresa A. Guise

ABSTRACT

Combination treatment of Low-Intensity Vibration (LIV) with zoledronic acid (ZA) was hypothesized to preserve bone mass and muscle strength while reducing adipose tissue accrual associated with complete estrogen (E2)-deprivation in young and skeletally mature mice. Complete E2-deprivation (surgical-ovariectomy (OVX) and daily injection of aromatase inhibitor (AI) letrozole) were performed on 8-week-old C57BL/6 female mice for 4 weeks following commencement of LIV administration or control (no LIV), for 28 weeks. Additionally, 16-week-old C57BL/6 female E2-deprived mice were administered ±LIV twice daily and supplemented with ±ZA (2.5 ng/kg/week). By week 28, lean tissue mass quantified by dual-energy X-ray absorptiometry was increased in younger OVX/AI+LIV(y) mice, with increased myofiber cross-sectional area of quadratus femorii. Grip strength was greater in OVX/AI+LIV(y) mice than OVX/AI(y) mice. Fat mass remained lower in OVX/AI+LIV(y) mice throughout the experiment compared with OVX/AI(y) mice. OVX/AI+LIV(y) mice exhibited increased glucose tolerance and reduced leptin and free fatty acids than OVX/AI(y) mice. Trabecular bone volume fraction and connectivity density increased in the vertebrae of OVX/AI+LIV(y) mice compared to OVX/AI(y) mice; however, this effect was attenuated in the older cohort of E2-deprived mice, specifically in OVX/AI+ZA mice, requiring combined LIV with ZA to increase trabecular bone volume and strength. Similar improvements in cortical bone thickness and cross-sectional area of the femoral mid-diaphysis were observed in OVX/AI+LIV+ZA mice, resulting in greater fracture resistance. Our findings demonstrate that the combination of mechanical signals in the form of LIV and anti-resorptive therapy via ZA improve vertebral trabecular bone and femoral cortical bone, increase lean mass, and reduce adiposity in mice undergoing complete E2-deprivation.

One Sentence Summary: Low-magnitude mechanical signals with zoledronic acid suppressed bone and muscle loss and adiposity in mice undergoing complete estrogen deprivation.

Translational Relevance Postmenopausal patients with estrogen receptor-positive breast cancer treated with aromatase inhibitors to reduce tumor progression experience deleterious effects to bone and muscle subsequently develop muscle weakness, bone fragility, and adipose tissue accrual. Bisphosphonates (i.e., zoledronic acid) prescribed to inhibit osteoclast-mediated bone resorption are effective in preventing bone loss but may not address the non-skeletal effects of muscle weakness and fat accumulation that contribute to patient morbidity. Mechanical signals, typically delivered to the musculoskeletal system during exercise/physical activity, are integral for maintaining bone and muscle health; however, patients undergoing treatments for breast cancer often experience decreased physical activity which further accelerates musculoskeletal degeneration. Low-magnitude mechanical signals, in the form of low-intensity vibrations, generate dynamic loading forces similar to those derived from skeletal muscle contractility. As an adjuvant to existing treatment strategies, low-intensity vibrations may preserve or rescue diminished bone and muscle degraded by breast cancer treatment.

HMGB1 neuroimmune signaling and REST-G9a gene repression contribute to ethanol-induced reversible suppression of the cholinergic neuron phenotype

AUTHORS

Fulton T. Crews, Rachael P. Fisher, Liya Qin & Ryan P. Vetreno

ABSTRACT

Adolescent binge drinking increases Toll-like receptor 4 (TLR4), receptor for advanced glycation end products (RAGE), the endogenous TLR4/RAGE agonist high-mobility group box 1 (HMGB1), and proinflammatory neuroimmune signaling in the adult basal forebrain in association with persistent reductions of basal forebrain cholinergic neurons (BFCNs). In vivo preclinical adolescent intermittent ethanol (AIE) studies find anti-inflammatory interventions post-AIE reverse HMGB1-TLR4/RAGE neuroimmune signaling and loss of BFCNs in adulthood, suggesting proinflammatory signaling causes epigenetic repression of the cholinergic neuron phenotype. Reversible loss of BFCN phenotype in vivo is linked to increased repressive histone 3 lysine 9 dimethylation (H3K9me2) occupancy at cholinergic gene promoters, and HMGB1-TLR4/RAGE proinflammatory signaling is linked to epigenetic repression of the cholinergic phenotype. Using an ex vivo basal forebrain slice culture (FSC) model, we report EtOH recapitulates the in vivo AIE-induced loss of ChAT+IR BFCNs, somal shrinkage of the remaining ChAT+ neurons, and reduction of BFCN phenotype genes. Targeted inhibition of EtOH-induced proinflammatory HMGB1 blocked ChAT+IR loss while disulfide HMBG1-TLR4 and fully reduced HMGB1-RAGE signaling decreased ChAT+IR BFCNs. EtOH increased expression of the transcriptional repressor RE1-silencing transcription factor (REST) and the H3K9 methyltransferase G9a that was accompanied by increased repressive H3K9me2 and REST occupancy at promoter regions of the BFCN phenotype genes Chat and Trka as well as the lineage transcription factor Lhx8. REST expression was similarly increased in the post-mortem human basal forebrain of individuals with alcohol use disorder, which is negatively correlated with ChAT expression. Administration of REST siRNA and the G9a inhibitor UNC0642 blocked and reversed the EtOH-induced loss of ChAT+IR BFCNs, directly linking REST-G9a transcriptional repression to suppression of the cholinergic neuron phenotype. These data suggest that EtOH induces a novel neuroplastic process involving neuroimmune signaling and transcriptional epigenetic gene repression resulting in the reversible suppression of the cholinergic neuron phenotype.

Report From the 6th International Meeting on Bone Marrow Adiposity (BMA2020)

AUTHORS

Erica L. Scheller, Meghan E. McGee-Lawrence, and Beata Lecka-Czernik

ABSTRACT

The 6th International Meeting on Bone Marrow Adiposity (BMA) entitled “Marrow Adiposity: Bone, Aging, and Beyond” (BMA2020) was held virtually on September 9th and 10th, 2020. The mission of this meeting was to facilitate communication and collaboration among scientists from around the world who are interested in different aspects of bone marrow adiposity in health and disease. The BMA2020 meeting brought together 198 attendees from diverse research and clinical backgrounds spanning fields including bone biology, endocrinology, stem cell biology, metabolism, oncology, aging, and hematopoiesis. The congress featured an invited keynote address by Ormond MacDougald and ten invited speakers, in addition to 20 short talks, 35 posters, and several training and networking sessions. This report summarizes and highlights the scientific content of the meeting and the progress of the working groups of the BMA society (http://bma-society.org/).

A glucuronated flavone TMMG spatially targets chondrocytes to alleviate cartilage degeneration through negative regulation of IL-1β

AUTHORS

Priyanka Kothari, Geeta Dhaniya, Anirban Sardar, Shradha Sinha, Aboli Girme, Divya Rai, Kunal Chutani, Lal Hingorani, Ritu Trivedi

ABSTRACT

Chondrocytes are the only resident cell types that form the extracellular matrix of cartilage. Inflammation alters the anabolic and catabolic regulation of chondrocytes, resulting in the progression of osteoarthritis (OA). The potential of TMMG, a glucuronated flavone, was explored against the pathophysiology of OA in both in vitro and in vivo models. The effects of TMMG were evaluated on chondrocytes and the ATDC5 cell line treated with IL-1β in an established in vitro inflammatory OA model. An anterior cruciate ligament transection (ACLT) model was used to simulate post-traumatic injury in vivo. Micro-CT and histological examination were employed to examine the micro-architectural status and cartilage alteration. Further, serum biomarkers were measured using ELISA to assess OA progression. In-vitro, TMMG reduced excessive ROS generation and inhibited pro-inflammatory IL-1β secretion by mouse chondrocytes and macrophages, which contributes to OA progression. This expression pattern closely mirrored osteoclastogenesis prevention. In-vivo results show that TMMG prevented chondrocyte apoptosis and degradation of articular cartilage thickness, subchondral parameters, and elevated serum COMP, CTX-II, and IL-1β which were significantly restored in 5 and 10 mg.kg−1day−1 treated animals and comparable to the positive control Indomethacin. In addition, TMMG also improved cartilage integrity and decreased the OARSI score by maintaining chondrocyte numbers and delaying ECM degradation. These findings suggest that TMMG may be a prospective disease-modifying agent that can mitigate OA progression.

Aging and the carotid body: A scoping review

AUTHORS

Camillo Di Giulio, Susi Zara, Andrea Mazzatenta, Vittore Verratti, Andrea Porzionato, Amelia Cataldi, Mieczyslaw Pokorski

ABSTRACT

The carotid body (CB) is a neuroepithelial tissue consisting of O2-sensitive glomus cells that constantly scan the arterial blood for O2 and generate a discharge as an inverse function of O2 content. Aging is a cumulative result of decreased O2 supply paralleled by a decreased O2 tissue demand and oxidative damage to cells derived from aerobic metabolism. Here we studied how CB affects the aging process. This is a study of CB ultrastructural morphometry and immunohistochemical expression of proteins underlying CB responsiveness. The study was based on human CBs obtained from cadavers of people who died due to traumatic events in young and old age. The study was supplemented by investigations of CBs obtained from young and old rats subjected to chronic normoxic and hypoxic conditions. We found changes in the old normoxic CBs akin to the effects of chronic hypoxia such as enhanced extracellular matrix, reduced synaptic contacts between glomus cells, fewer glomus cells, secretory vesicles, and mitochondria. These changes were accompanied by enhanced expressions of hypoxia-inducible factor one-alpha (HIF-1α), vascular endothelial growth factor (VEGF), and nitric oxide synthase (NOS2). We conclude that hypoxia and aging share a common background consisting of deficient O2 tissue supply, mitochondrial dysfunction, and a limited ability to deal with increased cellular oxidative stress. Aging leads to adaptative reductions in CB responsiveness to hypoxia shifting the chemosensory setpoint upward. We submit that the attenuated CB sensitivity at old age may be tantamount to “physiological denervation” leading to a gradual loss of the chemosensing role in the prevention of tissue hypoxia by increasing lung ventilation.

A prognostic model of clear cell renal cell carcinoma based on telomere-related lncRNAs

AUTHORS

Hao Chen, Li Li, Longkun Mao, Jianfeng Zeng

ABSTRACT

Background

Telomeres have been demonstrated to be critical in the development of multiple tumors. However, the association of telomere-related lncRNAs with clear cell renal cell carcinoma (ccRCC) and their prognostic roles in ccRCC patients remain unknown.

METHODS

Expression matrix and clinicopathological data of ccRCC patients were extracted from The Cancer Genome Altas and UCSC Xena browser. The differentially expressed genes were identified and intersected with the telomere-related genes downloaded from the Telnet database. Telomere-related lncRNAs were screened by the univariate Cox regression analysis. Each patient's risk score was calculated to establish a nomogram based on eight telomere-related lncRNAs screened by the least absolute shrinkage and selection operator (LASSO) algorithm and multivariate Cox regression analysis. The correlation between telomere-related lncRNAs and immune cells was assessed by the CIBEERSORT algorithm. The immune and stromal infiltrations were quantified by the ESTIMATE algorithm. Gene set enrichment analysis (GSEA) was performed to explore the selected lncRNA functions.

Result

We screened eight telomere-related lncRNAs and established a risk score model for predicting survival in ccRCC patients. A nomogram was developed to predict the survival outcomes of postoperative patients by integrating several clinical factors, and a well-predictive effect was observed. The correlation between selected lncRNAs and immune function was explored by the CIBEERSORT and ESTIMATE algorithms. Besides, GSEA showed that telomere-related lncRNAs could affect ccRCC prognosis through multiple pathways.