Modulation of the Primary Astrocyte-Enriched Cultures’ Oxylipin Profiles Reduces Neurotoxicity

Abstract

Recently, manipulations with reactive astrocytes have been viewed as a new therapeutic approach that will enable the development of treatments for acute brain injuries and neurodegenerative diseases. Astrocytes can release several substances, which may exert neurotoxic or neuroprotective effects, but the nature of these substances is still largely unknown. In the present work, we tested the hypothesis that these effects may be attributed to oxylipins, which are synthesized from n-3 or n-6 polyunsaturated fatty acids (PUFAs). We used astrocyte-enriched cultures and found that: (1) lipid fractions secreted by lipopolysaccharide (LPS)—stimulated rat primary astrocyte-enriched cultures—possessed neurotoxic activity in rat primary neuronal cultures; (2) both of the tested oxylipin synthesis inhibitors, ML355 and Zileuton, reduce the LPS-stimulated release of interleukin 6 (IL-6) by astrocyte cultures, but only ML355 can change lipid fractions from neurotoxic to non-toxic; and (3) oxylipin profiles, measured by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) from neurotoxic and non-toxic lipid fractions, reveal a group of n-3 docosahexaenoic acid derivatives, hydroxydocosahexaenoic acids (HdoHEs)-4-HdoHE, 8-HdoHE, and 17-HdoHE, which may reflect the neuroprotective features of lipid fractions. Regulating the composition of astrocyte oxylipin profiles may be suggested as an approach for regulation of neurotoxicity in inflammatory processes.

Upregulated NF-κB pathway proteins may underlieAPOE44associated astrocyte phenotypes in sporadic Alzheimer’s disease

“…Furthermore, although IL6 and IL8 are generally considered 'pro-inflammatory', at resting concentrations both have neuroprotective functions such as prevention of excitotoxicity, promoting axonal growth, synaptic plasticity and memory consolidation (49,50) which may suggest disruption of the resting APOE44 phenotype; our oxylipin data are consistent with this. Studies of oxylipin secretion in astrocytes are uncommon (27,51,52) but comparison of published data with our results (Table 1) suggests a clear perturbation in APOE44 astrocytes; oxylipins that are known to increase in response to lipopolysaccharide (LPS) stimulation (14,15-DiHETrE, 11-HETE, 13-HODE) all have lower basal levels in quiescent APOE44 astrocytes whereas oxylipins known to decrease in response to LPS stimulation (5-HETE) have significantly higher basal levels in quiescent APOE44 astrocytes. Interestingly, both 5-HETE and 5-HEPE which had significantly higher basal levels in APOE44 astrocytes (along with 4-HDOHE which just failed to reach significance after FDR testing) are all products of the enzyme 5-LOX.…”

Norepinephrine Inhibits Lipopolysaccharide-Stimulated TNF-α but Not Oxylipin Induction in n-3/n-6 PUFA-Enriched Cultures of Circumventricular Organs

“…Moreover, oxylipin profiles are novel biomarkers for detection of disease states [ 8 , 11 ] and cellular phenotype polarization such as in A1-like and A2-like astrocytes induced by lipopolysaccharide (LPS) or cytokine treatment [ 12 ]. Indeed, oxylipin production and their functional significance have been studied in vitro, for example, in macrophages [ 13 ], microglia [ 14 , 15 ], astrocytes [ 12 , 16 , 17 ], neurons [ 18 ], and primary human brain microvessel endothelial cells [ 19 ]. However, other than studies on hippocampal abundance [ 20 , 21 ], brain-region-specific production has rarely been investigated for oxylipins.…”