Neuroinflammation is an important component of Parkinson’s disease (PD) pathology, where astrocytes are exposed to inflammatory signals derived from resident and infiltrating immune cells. Interleukin-1β (IL-1β) can induce astrocyte reactivity, while interleukin-17A (IL-17A), a Th17-associated cytokine reported to be elevated in PD, has previously been shown to synergise with tumour necrosis factor-α (TNFα) in human astrocytes. We therefore investigated whether IL-17A similarly potentiates IL-1β-induced inflammatory responses in human induced pluripotent stem cell (iPSC)-derived ventral midbrain astrocytes.

NAS2 human iPSC-derived ventral midbrain astrocytes were exposed to cytokines for 24 h. An IL-1β dose-response study (0.01–3 ng/mL) was first performed to identify submaximal concentrations suitable for detecting cytokine interactions. IL-1β at 0.01 and 0.1 ng/mL was subsequently tested alone or in combination with IL-17A (10 ng/mL), a concentration previously selected to elicit minimal inflammatory responses when applied alone. Secreted IL-6, CCL5 and CXCL10 were quantified by ELISA, and expression of IL6, CCL5, CXCL10, ICAM1, C3 and GFAP was assessed by quantitative PCR. Astrocyte phenotype and morphology were evaluated by immunocytochemical analysis of GFAP, S100β, CX43 and EAAT1 and quantitative morphological measurements. Data were analysed using nested ANOVA.

IL-1β induced strong inflammatory responses, increasing IL-6, CCL5 and CXCL10 secretion and the expression of multiple inflammatory and reactivity-associated genes. Several responses were concentration-dependent. In contrast, IL-17A alone induced limited responses, and its addition to IL-1β did not consistently increase inflammatory mediator secretion or gene expression. Cytokine treatment for 24 h did not alter cellular morphology or GFAP, S100β, CX43 and EAAT1 protein immunoreactivity.

These findings demonstrate that IL-1β induces a strong acute inflammatory response in human iPSC-derived ventral midbrain astrocytes, but this response is not consistently potentiated by IL-17A. Despite changes in inflammatory mediator secretion and gene expression, no overt phenotypic or morphological alterations were detected following 24 h cytokine exposure. Overall, these findings provide no clear evidence of synergistic interaction between IL-1β and IL-17A under the conditions tested.