Primary glia expressing the G93A-SOD1 mutation present a neuroinflammatory phenotype and provide a cellular system for studies of glial inflammation

Abstract

Detailed study of glial inflammation has been hindered by lack of cell culture systems that spontaneously demonstrate the "neuroinflammatory phenotype". Mice expressing a glycine → alanine substitution in cytosolic Cu, Zn-superoxide dismutase (G93A-SODI) associated with familial amyotrophic lateral sclerosis (ALS) demonstrate age-dependent neuroinflammation associated with broad-spectrum cytokine, eicosanoid and oxidant production. In order to more precisely study the cellular mechanisms underlying glial activation in the G93A-SODI mouse, primary astrocytes were cultured from 7 day mouse neonates. At this age, G93A-SODI mice demonstrated no in vivo hallmarks of neuroinflammation. Nonetheless astrocytes cultured from G93A-SODI (but not wild-type human SODI-expressing) transgenic mouse pups demonstrated a significant elevation in either the basal or the tumor necrosis alpha (TNFα)-stimulated levels of proinflammatory eicosanoids prostaglandin E2 (PGE2) and leukotriene B4 (LTB4); inducible nitric oxide synthase (iNOS) and •NO (indexed by nitrite release into the culture medium); and protein carbonyl products. Specific cytokine- and TNFα death-receptor-associated components were similarly upregulated in cultured G93A-SODI cells as assessed by multiprobe ribonuclease protection assays (RPAs) for their mRNA transcripts. Thus, endogenous glial expression of G93A-SODI produces a metastable condition in which glia are more prone to enter an activated neuroinflammatory state associated with broad-spectrum increased production of paracrine-acting substances. These findings support a role for active glial involvement in ALS and may provide a useful cell culture tool for the study of glial inflammation. © 2006 Hensley et al; licensee BioMed Central Ltd.