Astroglia acquires a toxic neuroinflammatory role in response to the cerebrospinal fluid from amyotrophic lateral sclerosis patients

Abstract

BackgroundNon-cell autonomous toxicity is one of the potential mechanisms implicated in the etiopathogenesis of amyotrophic lateral sclerosis (ALS). However, the exact role of glial cells in ALS pathology is yet to be fully understood. In a cellular model recapitulating the pathology of sporadic ALS, we have studied the inflammatory response of astroglia following exposure to the cerebrospinal fluid from ALS patients (ALS-CSF).MethodsVarious inflammatory markers including pro-inflammatory and anti-inflammatory cytokines, COX-2, PGE-2, trophic factors, glutamate, nitric oxide (NO), and reactive oxygen species (ROS) were analyzed in the rat astroglial cultures exposed to ALS-CSF and compared with the disease control or normal controls. We used immunofluorescence, ELISA, and immunoblotting techniques to investigate the protein expression and real-time PCR to study the messenger RNA (mRNA) expression. Glutamate, NO, and ROS were estimated using appropriate biochemical assays. Further, the effect of conditioned medium from the astroglial cultures exposed to ALS-CSF on NSC-34 motor neuronal cell line was detected using the MTT assay. Statistical analysis was carried out using one-way ANOVA followed by Tukey’s post hoc test, or Student’s t test, as applicable.ResultsHere, we report that the ALS-CSF enhanced the production and release of inflammatory cytokines IL-6 and TNF-α, as well as COX-2 and PGE-2. Concomitantly, anti-inflammatory cytokine IL-10 and the beneficial trophic factors, namely VEGF and GDNF, were down-regulated. We also found impaired regulation of glutamate, NO, and ROS in the astroglial cultures treated with ALS-CSF. The conditioned medium from the ALS-CSF exposed astroglial cultures induced degeneration in NSC-34 cells.ConclusionsOur study demonstrates that the astroglial cells contribute to the neuroinflammation-mediated neurodegeneration in the in vitro model of sporadic ALS.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-016-0698-0) contains supplementary material, which is available to authorized users.

Astrocytes in Pathogenesis of ALS Disease and Potential Translation into Clinic

“…VEGF delays MN degeneration and increases survival in animal models of ALS [73,74]. In line with these results, low levels of VEGF and GDNF were reported in the CSF of ALS patients [75]. VEGF exerts its antiexcitotoxic effects on MNs through mechanisms involving VEGF receptor-2 and activation of the PI3-K/Akt signaling pathway [72].…”

Chitotriosidase, a biomarker of Amyotrophic Lateral Sclerosis accentuates neurodegeneration in spinal motor neurons through neuroinflammation.

“…We have earlier reported that ALS-CSF induced apoptosis and reduced ChAT expression in NSC-34 cells [46] with altered neuronal activity and motor de cits in adult rats [47,48]. Conditioned medium from glial cells exposed to ALS-CSF also resulted in reduced viability of NSC-34 cells [31,41]. The reduction in the white matter area observed with staining by phospohorylated neuro laments can be correlated to white matter atrophy observed in ALS patient spinal cord [49].…”

“…Microglial proliferation was observed from the pre-clinical stage of disease in mSOD1 rats while hypertrophic GFAP labelled astrocytes were seen only during the late clinical stage [40]. Microglial cells responded prior to astrocytes when exposed to ALS-CSF as microglia showed increased release of pro-in ammatory molecules like interleukin 6, TNF-α and glutamate as early as 12 hours while astrocytes showed a similar response only after 24 or 48 hours [31,41].…”

Pathogenic commonalities between spinal muscular atrophy and amyotrophic lateral sclerosis: Converging roads to therapeutic development

“…Elevated levels of the inflammasome component IL-1 and phosphorylated ERK is also observed in spinal cord astrocytes of ALS mice and patients (Chung et al, 2005;Johann et al, 2015). The secretion of IL-6 by ALS astrocytes can be elicited by the pathogenic pro-inflammatory effector TWEAK (Bowerman et al, 2015), or by the cerebrospinal fluid (CSF) obtained from ALS patients, which in addition to promote TNF production, leads to decreased astrocytic expression of GDNF by astrocytes (Mishra et al, 2016). The decreased ability of SOD1 mutant astrocytes to support motoneuron survival can be ameliorated by GDNF (Das and Svendsen, 2015).…”