Accumulation of protein aggregates is an inherent part of normal ageing in numerous organisms. Protein aggregation with age affects the proteome of different tissues, cellular compartments as well as in the extracellular space. Age-dependent protein aggregates contribute to functional decline and thus are prime targets in the search of strategies to promote healthy ageing (Huang et al.,eLife,2019). We discovered mechanisms to prevent age-dependent protein aggregation outside cells inC. elegans. Specifically, we identified over 50 components of the extracellular proteostasis network inC. elegansthat protect against extracellular protein aggregation. Promoting extracellular proteostasis can prolong lifespan and, during a pathogenic attack, can enhance survival (Gallotta et al.,Nature,2020). Switching on a longevity program in mid-life helps to clear extracellular aggregates, concomitant with the rejuvenation of acute stress responses (Molière et al.,Geroscience,2024). Follow-up work reveals conserved anti-aggregation activity in a secreted human protein with homologies toC. elegansextracellular proteostasis components. Notably, its overexpression promotes healthy ageing inC. elegans. Together our work exposes proteostasis mechanisms used by the organism to protect its extracellular proteome against aggregation during ageing, with potentially conserved activities in corresponding human proteins.