Abstract
The development of senomorphic drugs to attenuate the senescent phenotype and senolytics to clear pro-inflammatory senescent cells to treat aging-associated disorders is being hotly pursued. The effort is complicated by the fact that senescent cells play a constructive role in some cellular processes such as tissue repair and wound healing. However, concerns about efficacy, which senescent cells to target, and unwanted side effects have created potential roadblocks. Chimeric Antigen Receptor (CAR) T cells directed against urokinase-type plasminogen activator receptor (uPAR), which is expressed on at least a subset of senescent cells (SC) in atherosclerotic plaques and fibrotic livers, removed SC and improved glucose metabolism. A conventional vaccine targeting CD153-expressing senescent T-cells, also improved glucose metabolism in obese mice. Recent work to selectively target senescent cells associated with several pathologies has resulted in the creation of a peptide vaccine that primarily targets endothelial cells expressing high levels of GPNMB, recently identified as a biomarker of senescence. The vaccine reduces atherosclerotic plaque burden and metabolic dysfunction such as glucose intolerance in mouse models of obesity and atherosclerosis. For translation to humans the activity of the vaccine will need to be tightly controlled, as the target, GPNMB has multiple roles in normal physiology including acting to inhibit and possibly resolve inflammation. A promising alternative approach would be to use passive immunization with a monoclonal antibody directed against GPNMB.
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