Co-stimulation with IL-1β and TNF-α induces an inflammatory reactive astrocyte phenotype with neurosupportive characteristics in a human pluripotent stem cell model system

Abstract

Astrocyte reactivation has been discovered to be an important contributor to several neurological diseases. In vitro models involving human astrocytes have the potential to reveal disease-specific mechanisms of these cells and to advance research on neuropathological conditions. Here, we induced a reactive phenotype in human induced pluripotent stem cell (hiPSC)-derived astrocytes and studied the inflammatory natures and effects of these cells on human neurons. Astrocytes responded to interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) treatment with a typical transition to polygonal morphology and a shift to an inflammatory phenotype characterized by altered gene and protein expression profiles. Astrocyte-secreted factors did not exert neurotoxic effects, whereas they transiently promoted the functional activity of neurons. Importantly, we engineered a novel microfluidic platform designed for investigating interactions between neuronal axons and reactive astrocytes that also enables the implementation of a controlled inflammatory environment. In this platform, selective stimulation of astrocytes resulted in an inflammatory niche that sustained axonal growth, further suggesting that treatment induces a reactive astrocyte phenotype with neurosupportive characteristics. Our findings show that hiPSC-derived astrocytes are suitable for modeling astrogliosis, and the developed in vitro platform provides promising novel tools for studying neuron-astrocyte crosstalk and human brain disease in a dish.

Short and long TNF‐alpha exposure recapitulates canonical astrogliosis events in human‐induced pluripotent stem cells‐derived astrocytes

“…Once released by microglia, this cytokine participates in the induction of neurotoxic dysfunctional phenotype A1 (Liddelow et al, ). According to these recent reports, long‐term exposure to TNF‐α impaired glutamate uptake by iPSC‐derived astrocytes (Hyvarinen et al, ; Zhou et al, ), Here, we show that this impairment can occur just after short‐term exposure to TNF‐α as well. Of note, as astrogliosis progresses due to long‐term TNF‐α exposure, impairment of aspartate uptake confirmed their dysfunctionality indeed.…”

“…Recent evidences have shown that extracellular glutamate stimulates glutamate release from astrocytes in order to coordinate neuronal activity, pointing to an emerging role for astrocytes in modulating both glutamate uptake and release and extending their therapeutic potential (Mahmoud, Gharagozloo, Simard, & Gris, ). Recent advances in the characterization of A1/A2 astrocytes have contributed to understand the dual effects of reactive astrocytes (Liddelow et al, ), even though the reproducibility of these phenotypes has been challenged in vitro (Hyvarinen et al, ; Zhou et al, ). However, TNF‐alpha is one of main factors involved in the signaling of both phenotypes.…”

In Vitro Oxygen-Glucose Deprivation-Induced Stroke Models with Human Neuroblastoma Cell- and Induced Pluripotent Stem Cell-Derived Neurons

“…For all staining experiments, four images per well were taken and used for image analysis. CellProfiler [ 34 ] software was used to perform image analysis as previously described [ 39 ], where the areas of calcein-AM- and EthD-1-positive cells in the images were determined from.…”

Astrocytes as Guardians of Neuronal Excitability: Mechanisms Underlying Epileptogenesis

“…In this paragraph, we will focus on cytokines that exacerbate epilepsy progression and may therefore be interesting for therapeutic intervention. The most studied cytokines regarding astrogliosis and epilepsy are interleukin-1 beta (IL-1β), IL-6, and tumor necrosis factor-alpha (TNF-α); pro-inflammatory cytokines that can be released by reactive astrocytes (49,50) and activated microglia (51). In a complex pathology such as epilepsy, more cytokines are playing roles in the alleviation and exacerbation of the disease.…”

“…Numerous studies have shown upregulation of IL-1β, IL-6, and TNF-α in animals with (recurrent) seizures (53)(54)(55)(56)(57)(58)(59) and patients with epilepsy (60)(61)(62)(63). IL-1β can affect neurotransmitter receptors (64,65), induce calcium influx by N-methyl-D-aspartate (NMDA) and 3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-mediated mechanisms in neurons (66,67), lead to alterations in expression of microRNAs in astrocytes (68)(69)(70), as well as potassium channels (71), metalloproteinases (72), altered astrocytic glutamate uptake (73,74) and calcium uptake (75), and induces astrocytic release of other pro-inflammatory cytokines (50). IL-6 activates the Grp130/JAK/STAT pathway and thereby induces the release of additional pro-inflammatory cytokines, further endorsing inflammation (76).…”