Systemic paracrine milieu

The systemic paracrine milieu refers to the collective environment of circulating and locally acting signaling factors, including cytokines, chemokines, growth factors, and extracellular vesicles, that regulate cellular function and tissue homeostasis (Conboy et al., 2005, Nature). It is not a single molecular target but a physiological state representing the sum of intercellular communication signals throughout the body (Villeda et al., 2014, Nature Medicine). In aging and chronic disease, this milieu undergoes significant shifts, such as the accumulation of pro-inflammatory factors known as the Senescence-Associated Secretory Phenotype (SASP), which can impair stem cell function and promote tissue degeneration (Acosta et al., 2013, Nature Cell Biology). Therapeutic interventions like heterochronic parabiosis, therapeutic plasma exchange, or senolytic drugs aim to 'rejuvenate' or 'normalize' this milieu to restore regenerative capacity and improve healthspan (Lehallier et al., 2019, Nature Medicine). Because it involves a vast array of heterogeneous components rather than a discrete receptor or enzyme, it is categorized as a systemic physiological environment rather than a traditional drug target (Katsimpardi et al., 2014, Science).

Other names

Systemic environmentCirculating milieuHumoral environmentParacrine signaling environmentSystemic signaling milieu

Modulation of the collective signaling environment by removing deleterious pro-inflammatory or pro-senescent factors (e.g., via senolytics or plasma exchange) or by replenishing beneficial regenerative factors to restore youthful tissue function.