Chemokine levels in the murine brain from early postnatal development to aging.

Cytokines and chemokines are key mediators of immune-brain communication and play important roles in central nervous system development, homeostasis, and aging. While individual cytokines and chemokines have been implicated in neurodevelopmental and age-related processes, a systematic characterization of their expression in the brain across the lifespan is lacking. Here, we performed a multiplex analysis of cytokine and chemokine levels in whole-brain homogenates from C57BL/6 mice spanning early postnatal life to advanced aging (postnatal day 3 to 24 months). Using a multiplex immunoassay, we quantified 21 chemokines and 9 cytokines and identified distinct age-associated expression patterns. Several chemokines exhibited elevated levels during early postnatal development, whereas others were selectively increased in the aged brain. Notably, a subset of chemokines displayed biphasic expression, with higher levels during both early life and aging. Cytokine analysis revealed increased levels of IL-1β and IL-2 during early postnatal development, while aging was associated with elevated TNF-α, IL-2, and IL-4. Together, these data provide a descriptive resource of cytokine and chemokine expression in the mouse brain across the lifespan, highlighting life stage-specific immune signatures that may differentially influence immune cell trafficking, neuron-glia interactions, and brain function during neural development and aging.