Ageing and the lymphatic system: Implications for immunity, brain health, and possible therapeutic interventions.

The lymphatic system is essential for maintaining interstitial fluid balance, supporting immune surveillance, and clearing metabolic waste, yet its role in ageing has only recently come into focus. With age, lymphatic vessels and lymphoid organs undergo structural and functional decline, leading to impaired transport, disrupted immune cell trafficking, and chronic low-grade inflammation. These changes contribute to systemic inflammaging and are increasingly implicated in cardiovascular disease, metabolic dysfunction, and neurodegenerative disorders. In the central nervous system, deterioration of the glymphatic and meningeal lymphatic systems compromises cerebrospinal fluid circulation and the clearance of amyloid-β, tau, and other metabolites, thereby accelerating cognitive decline. In this review, we examine the molecular and cellular mechanisms that underline lymphatic ageing, including junctional remodeling, extracellular matrix stiffening, altered lymphangiogenic signaling, and endothelial senescence. We critically assess the consequences of lymphatic dysfunction for systemic and brain health, highlighting unresolved controversies such as the extent to which lymphatic changes are primary drivers of pathology, the limitations of rodent models and indirect imaging readouts, and the lack of ageing-resolved single-cell maps in human tissues. Finally, we discuss therapeutic avenues ranging from antioxidant and pro-lymphangiogenic strategies to lifestyle interventions and reconstructive microsurgery. Together these insights position the lymphatic system as a central, yet underexplored, determinant of resilience in ageing and a promising target for future gerotherapeutic interventions.