In vitroandin vivoeffects of zoledronate on senescence and senescence-associated secretory phenotype markers

Abstract

In addition to reducing fracture risk, zoledronate has been found in some studies to decrease mortality in humans and extend lifespan and healthspan in animals. Because senescent cells accumulate with aging and contribute to multiple co-morbidities, the non-skeletal actions of zoledronate could be due to senolytic (killing of senescent cells) or senomorphic (inhibition of the secretion of the senescence-associated secretory phenotype [SASP]) actions. To test this, we first performed in vitro senescence assays using human lung fibroblasts and DNA repair-deficient mouse embryonic fibroblasts, which demonstrated that zoledronate killed senescent cells with minimal effects on non-senescent cells. Next, in aged mice treated with zoledronate or vehicle for 8 weeks, zoledronate significantly reduced circulating SASP factors, including CCL7, IL-1β, TNFRSF1A, and TGFβ1 and improved grip strength. Analysis of publicly available RNAseq data from CD115+ (CSF1R/c-fms+) pre-osteoclastic cells isolated from mice treated with zoledronate demonstrated a significant downregulation of senescence/SASP genes (SenMayo). To establish that these cells are potential senolytic/senomorphic targets of zoledronate, we used single cell proteomic analysis (cytometry by time of flight [CyTOF]) and demonstrated that zoledronate significantly reduced the number of pre-osteoclastic (CD115+/CD3e-/Ly6G-/CD45R-) cells and decreased protein levels of p16, p21, and SASP markers in these cells without affecting other immune cell populations. Collectively, our findings demonstrate that zoledronate has senolytic effects in vitro and modulates senescence/SASP biomarkers in vivo. These data point to the need for additional studies testing zoledronate and/or other bisphosphonate derivatives for senotherapeutic efficacy.

Abstracts from the Bone Research Society Annual Meeting, April 13–15, 2023, Liverpool, UK

“…BPs can access non-mineralised tissues (7). The extensive range of currently reported non-skeletal effects include extending longevity in mouse models of progeria (8), enhancing human stem cell life span, DNA repair and tissue regeneration (9), effects on tumour growth, prevention of oxidative damage, promotion of autophagy (10), and modulation of cellular senescence (11).…”

Profiling microRNA expression during senescence and aging: mining for a diagnostic tool of senescent-cell burden

“…Significant progress in understanding diseases related to aging has been made over the last few years by identifying senescent cells as common substrate of a plethora of age-related diseases 1,2 termed senopathies 3 . Since the initial discovery of senolytics 4 , research on senescent cell targeting compounds progressed quickly [5][6][7][8][9][10][11][12][13][14] and clinical trials of this new class of drugs are ongoing 15 . This creates a necessity for companion diagnostics of senescence that allow early assessment of safety and efficacy of senolytic drug candidates and the detection of sensitive clinical endpoints 16 .…”

Cardiovascular benefits and risks associated with calcium, vitamin D, and antiresorptive therapy in the management of skeletal fragility

“…86 In addition to these observed changes in the CV system following bisphosphonate exposure, data have shown that zoledronate can have immunomodulatory effects including reduction in senescence-associated chemokines (such as CCL7, IL-1β, TNFRSF1A, and TGFβ1) and possible impact on immune cell subpopulations. [87][88][89] The role of these changes in the CV system and their impact on CV outcomes remain unclear. In figure 1, we have summarized the cardioprotective benefits of bisphosphonate therapy with a hypothesized mechanism based on the available pre-clinical and clinical data.…”