Abstract
Macrophages, a critical subset of innate immune cells, play a pivotal role in cytokine production during disease progression, tissue injury, and pathogen invasion. Their intricate involvement in the manifestation of chronic low-grade inflammation associated with the aging process is widely acknowledged. Notably, in aged tissues, macrophages exhibit an altered phenotype characterized by an augmented synthesis of pro-inflammatory cytokines and chemokines, a profile intimately associated with a phenomenon known as inflammaging. Macrophages possess the capacity to undergo cellular senescence, a state of permanent growth arrest, in response to diverse stressors, including aging. Senescent macrophages secrete an array of pro-inflammatory molecules, growth factors, and matrix metalloproteinases, collectively referred to as the Senescence-Associated Secretory Phenotype (SASP). The SASP exacerbates the state of chronic inflammation observed in aging tissues. Thus, disruptions in macrophage function and signaling pathways due to aging result in escalated production of inflammatory mediators, perpetuating inflammaging. Recent research has uncovered novel mechanisms centred around innate immune signaling and mitochondrial dysfunction in macrophages, highlighting their crucial role in the development of inflammaging and associated pathological conditions. This review delves into the latest scientific findings on these emerging mechanisms in macrophage senescence related to aging and explores the prospects of targeting macrophages to address age-associated conditions effectively.