The proinflammatory action of microglial P2 receptors is enhanced in SOD1 models for amyotrophic lateral sclerosis.
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by the selective loss of lower and upper motoneurons. The pathology is imputable in approximately 2% of cases to mutations in the ubiquitous enzyme Cu, Zn superoxide dismutase (SOD1). Common theories to explain the pathogenic mechanisms of ALS include activation of microglia, responsible for the release of proinflammatory factors. However, how mutant SOD1 affects microglial activation and subsequently injures neurons is still unclear. Considering that extracellular ATP, through purinergic P2 receptors, constitutes a well recognized neuron-to-microglia alarm signal, the aim of this study was to investigate how the expression of mutant SOD1 affects P2 receptor-mediated proinflammatory microglial properties. We used primary and immortalized microglial cells from mutant SOD1 mice to explore several aspects of activation by purinergic ligands and to analyze the overall effect of such stimulation on the viability of NSC-34 and SH-SY5Y neuronal cell lines. We observed up-regulation of P2X(4), P2X(7), and P2Y(6) receptors and down-regulation of ATP-hydrolyzing activities in mutant SOD1 microglia. This potentiation of the purinergic machinery reflected into enhanced sensitivity mainly to 2'-3'-O-(benzoyl-benzoyl) ATP, a P2X(7) receptor preferential agonist, and translated into deeper morphological changes, enhancement of TNF-alpha and cyclooxygenase-2 content, and finally into toxic effects exerted on neuronal cell lines by microglia expressing mutant SOD1. All these parameters were prevented by the antagonist Brilliant Blue G. The purinergic activation of microglia may thus constitute a new route involved in the progression of ALS to be exploited to potentially halt the disease.
D'Ambrosi
Nadia
N
Santa Lucia Foundation, Rome, Italy. n.dambrosi@hsantalucia.it
Finocchi
Pamela
P
Apolloni
Savina
S
Cozzolino
Mauro
M
Ferri
Alberto
A
Padovano
Valeria
V
Pietrini
Grazia
G
Carrì
Maria Teresa
MT
Volonté
Cinzia
C
D000409:Alanine / Q000235:genetics; D019943:Amino Acid Substitution / Q000235:genetics; D000690:Amyotrophic Lateral Sclerosis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D000818:Animals; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D018920:Coculture Techniques; D004195:Disease Models, Animal; D018450:Disease Progression; D015971:Gene Expression Regulation, Enzymologic; D005998:Glycine / Q000235:genetics; D006801:Humans; D018836:Inflammation Mediators / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D017628:Microglia / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology*; D010641:Phenotype; D018048:Receptors, Purinergic P2 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D000072105:Superoxide Dismutase-1; D015854:Up-Regulation / Q000235:genetics
D018836:Inflammation Mediators; D018048:Receptors, Purinergic P2; C000606290:SOD1 protein, human; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D000409:Alanine; D005998:Glycine