Abstract
BackgroundInflammation plays a critical role in accelerating the progression of neurodegenerative diseases, such as Alzheimer’s disease (AD) and ataxia telangiectasia (A-T). In A-T mouse models, LPS-induced neuroinflammation advances the degenerative changes found in cerebellar Purkinje neurons both in vivo and in vitro. In the current study, we ask whether ibuprofen, a non-steroidal anti-inflammatory drug (NSAID), can have the opposite effect and delay the symptoms of the disease.MethodsWe tested the beneficial effects of ibuprofen in both in vitro and in vivo models. Conditioned medium from LPS stimulated primary microglia (LM) applied to cultures of dissociated cortical neurons leads to numerous degenerative changes. Pretreatment of the neurons with ibuprofen, however, blocked this damage. Systemic injection of LPS into either adult wild-type or adult Atm−/− mice produced an immune challenge that triggered profound behavioral, biochemical, and histological effects. We used a 2-week ibuprofen pretreatment regimen to investigate whether these LPS effects could be blocked. We also treated young presymptomatic Atm−/− mice to determine if ibuprofen could delay the appearance of symptoms.ResultsAdding ibuprofen directly to neuronal cultures significantly reduced LM-induced degeneration. Curiously, adding ibuprofen to the microglia cultures before the LPS challenge had little effect, thus implying a direct effect of the NSAID on the neuronal cultures. In vivo administration of ibuprofen to Atm−/− animals before a systemic LPS immune challenge suppressed cytological damage. The ibuprofen effects were widespread as microglial activation, p38 phosphorylation, DNA damage, and neuronal cell cycle reentry were all reduced. Unfortunately, ibuprofen only slightly improved the LPS-induced behavioral deficits. Yet, while the behavioral symptoms could not be reversed once they were established in adult Atm−/− animals, administration of ibuprofen to young mutant pups prevented their symptoms from appearing.ConclusionInflammatory processes impact the normal progression of A-T implying that modulation of the immune system can have therapeutic benefit for both the behavioral and cellular symptoms of this neurodegenerative disease.
Highlights
Inflammation plays a critical role in accelerating the progression of neurodegenerative diseases, such as Alzheimer’s disease (AD) and ataxia telangiectasia (A-T)
Microglia-mediated immune challenge contributes to the neuronal damage in vitro Previous studies in our lab have found that an LPS immune challenge significantly exaggerates neuronal damage in both the short and long-term [24, 25]
Neurotoxicity was significantly exaggerated when microglia were pretreated with LPS; this shows that under a specific immune challenge, more harmful substances were released into the medium [42]
Summary
Inflammation plays a critical role in accelerating the progression of neurodegenerative diseases, such as Alzheimer’s disease (AD) and ataxia telangiectasia (A-T). Ataxia telangiectasia (A-T) is a neurodegenerative disease of childhood with a prevalence between 1 in 40,000 and 1 in 100,000 people worldwide. It results from the mutation of a single gene, A-T mutated (ATM), whose gene product is a large kinase of the PI3K family. A-T symptoms include a progressive neuronal loss, ataxia, cancer susceptibility, hypersensitivity to ionizing radiation, immunodeficiency, and sterility [1,2,3]. In A-T patients, sustained immune challenges, including bacterial infections and chronic inflammation, greatly contribute to the development of disease pathology [18, 19]. The contribution of the immune system, in particular, the microglia of the brain’s innate immune system, to the neurological and neuropathological abnormalities of A-T remains less certain
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