Pharmacological Investigations in Glia Culture Model of Inflammation

Abstract

Astrocytes and microglia are the main cell population besides neurons in the central nervous system (CNS). Astrocytes support the neuronal network via maintenance of transmitter and ion homeostasis. They are part of the tripartite synapse, composed of pre- and postsynaptic neurons and perisynaptic astrocytic processes as a functional unit. There is an increasing evidence that astroglia are involved in the pathophysiology of CNS disorders such as epilepsy, autoimmune CNS diseases or neuropsychiatric disorders, especially with regard to glia-mediated inflammation. In addition to astrocytes, investigations on microglial cells, the main immune cells of the CNS, offer a whole network approach leading to better understanding of non-neuronal cells and their pathological role in CNS diseases and treatment. An in vitro astrocyte-microglia co-culture model of inflammation was developed by Faustmann et al. (2003), which allows to study the endogenous inflammatory reaction and the cytokine expression under drugs in a differentiated manner. Commonly used antiepileptic drugs (e.g., levetiracetam, valproic acid, carbamazepine, phenytoin, and gabapentin), immunomodulatory drugs (e.g., dexamethasone and interferon-beta), hormones and psychotropic drugs (e.g., venlafaxine) were already investigated, contributing to better understanding mechanisms of actions of CNS drugs and their pro- or anti-inflammatory properties concerning glial cells. Furthermore, the effects of drugs on glial cell viability, proliferation and astrocytic network were demonstrated. The in vitro astrocyte-microglia co-culture model of inflammation proved to be suitable as unique in vitro model for pharmacological investigations on astrocytes and microglia with future potential (e.g., cancer drugs, antidementia drugs, and toxicologic studies).

Keywords: M5/M30 conditions; antiepileptic drugs (AEDs); astrocyte-microglia co-culture model; immunomodulatory drugs; inflammation; pharmacology; psychotropic drugs.

FIGURE 1

Immunocytochemistry of microglia morphology in M5 und M30 astrocyte-microglia co-cultures. Physiological M5 co-cultures containing 5% microglia (red) (A). Pathological, inflammatory M30 co-cultures containing 30% microglia (B) (published by Dambach et al., 2014). Staining with the monoclonal antibody ED-1 allowed the classification of microglia (white arrows) as resting ramified (C), intermediate (D) and activated rounded phagocytic (E) phenotype (published by Ismail et al., 2021). Nuclei (blue) were counterstained with DAPI to visualize the total glial cell number.