Objectives The objective of this study was to investigate how in vitro astrocyte cultures respond to cytokine pro- and anti-inflammatory cytokine concentrations, corresponding to those seen in the aftermath of human TBI, by analysing downstream cytokine generation.

Design In vitro study.

Subjects Human induced pluripotent stem cells (iPSC)-derived astrocytes.

Methods The astrocytes were exposed to levels of TNF (1–10,000 pg/ml), IL-6 (100–1,000,000 pg/ml), Interleukin-1β (IL-1β, 1–10,000 pg/ml), Interleukin-4 (IL-4, 1–10,000 pg/ml) and Interleukin-10 (IL-10, 1–10,000 pg/ml). Following 24, 48 and 72 hours, culture supernatant was extracted and analysed using a human cytokine/chemokine 39-plex luminex assay (ThermoFisher).

Results The astrocyte secretome revealed concentration-, time- or concentration*time-dependent production of downstream cytokines (12, 8 and 2 cytokines, respectively p<0.05). IL-1β and TNF exposure generated the most downstream cytokine production, while IL-6, IL-4 and IL-10 did not generally induce a robust response.

Conclusions iPSC-derived astrocytes exposed to cytokine concentrations reflecting those in TBI generate an increased downstream cytokine production, especially when exposed to IL-1β and TNF. This is in contrast to our previous work on neuronal cultures where IL-1β only produced a few down-stream cytokines.¹ More work is needed to better understand how different cells in the CNS respond to the neuroinflammatory milieu after TBI alone and in combination.