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Chronic psychosocial stress is increasingly being recognised as a risk factor for sporadic Alzheimer's disease (AD). The hypothalamic–pituitary–adrenal axis (HPA axis) is the major stress response pathway in the body and tightly regulates the production of cortisol, a glucocorticoid hormone. Dysregulation of the HPA axis and increased levels of cortisol are commonly found in AD patients and make a major contribution to the disease process. The underlying mechanisms remain poorly understood. In addition, within the general population there are interindividual differences in sensitivities to glucocorticoid and stress responses, which are thought to be due to a combination of genetic and environmental factors. These differences could ultimately impact an individuals' risk of AD. The purpose of this review is first to summarise the literature describing environmental and genetic factors that can impact an individual's HPA axis reactivity and function and ultimately AD risk. Secondly, we propose a mechanism by which genetic factors that influence HPA axis reactivity may also impact inflammation, a key driver of neurodegeneration. We hypothesize that these factors can mediate glucocorticoid priming of the immune cells of the brain, microglia, to become pro‐inflammatory and promote a neurotoxic environment resulting in neurodegeneration. Understanding the underlying molecular mechanisms and identifying these genetic factors has implications for evaluating stress‐related risk/progression to neurodegeneration, informing the success of interventions based on stress management and potential risks associated with the common use of glucocorticoids. [ABSTRACT FROM AUTHOR]

The innate immune response to LPS is highly dynamic yet tightly regulated. The majority of studies of gene expression have focussed on transcription. However, it is also important to understand how post‐transcriptional pathways are regulated in response to inflammatory stimuli as the rate of RNA degradation relative to new transcription is important for overall expression. RNA decay pathways include nonsense‐mediated decay, the RNA decay exosome, P‐body localized deadenylation, decapping and degradation, and AU‐rich element targeted decay mediated by tristetraprolin. Here, bone marrow‐derived Mϕs were treated with LPS over a time course of 0, 2, 6, and 24 h and the transcriptional profiles were analyzed by RNA sequencing. The data show that components of RNA degradation pathways are regulated during an LPS response. Processing body associated decapping enzyme DCP2 and regulatory subunit DCP1A, and 5′ exonuclease XRN1 and sequence specific RNA decay pathways were upregulated. Nonsense mediated decay was also increased in response to LPS induced signaling, initially by increased activation and at later timepoints at the mRNA and protein levels. This leads to increased nonsense mediated decay efficiency across the 24 h following LPS treatment. These findings suggest that LPS activation of Mϕs results in targeted regulation of RNA degradation pathways in order to change how subsets of mRNAs are degraded during an inflammatory response. [ABSTRACT FROM AUTHOR]

Background: Neuroinflammation and biometal dyshomeostasis are key pathological features of several neurodegenerative diseases, including Alzheimer's disease (AD). Inflammation and biometals are linked at the molecular level through regulation of metal buffering proteins such as the metallothioneins. Even though the molecular connections between metals and inflammation have been demonstrated, little information exists on the effect of copper modulation on brain inflammation. Methods: We demonstrate the immunomodulatory potential of the copper bis(thiosemicarbazone) complex CuII(atsm) in an neuroinflammatory model in vivo and describe its anti-inflammatory effects on microglia and astrocytes in vitro. Results: By using a sophisticated in vivo magnetic resonance imaging (MRI) approach, we report the efficacy of CuII(atsm) in reducing acute cerebrovascular inflammation caused by peripheral administration of bacterial lipopolysaccharide (LPS). CuII(atsm) also induced anti-inflammatory outcomes in primary microglia [significant reductions in nitric oxide (NO), monocyte chemoattractant protein 1 (MCP-1), and tumor necrosis factor (TNF)] and astrocytes [significantly reduced NO, MCP-1, and interleukin 6 (IL-6)] in vitro. These anti-inflammatory actions were associated with increased cellular copper levels and increased the neuroprotective protein metallothionein-1 (MT1) in microglia and astrocytes. Conclusion: The beneficial effects of CuII(atsm) on the neuroimmune system suggest copper complexes are potential therapeutics for the treatment of neuroinflammatory conditions. [ABSTRACT FROM AUTHOR]

Abstract: The phosphoinositide‐3‐kinase like kinases are a family of very large protein kinases. These PI3‐kinase like kinase (PIKK) proteins have well‐established roles in detection and repair of damage to the genome, regulation of the transcriptome and cellular metabolism. Recently there has emerged, evidence for links between these proteins and inflammation. While some of these links come from an increased understanding of the impacts of damage to the cell on inflammatory responses, others suggest that PIKK proteins also have direct roles in regulation of immune responses. Particularly evident is the link between DNA damage and innate immune response pathways. Here, we review recent findings on the PIKK family of proteins and how they impact on inflammation, particularly activation of the innate immune system. [ABSTRACT FROM AUTHOR]

Decreased ATM expression leads to accumulation of cytosolic DNA and neuroinflammation. Mutations in the ataxia‐telangiectasia (A‐T)‐mutated (ATM) gene give rise to the human genetic disorder A‐T, characterized by immunodeficiency, cancer predisposition, and neurodegeneration. Whereas a series of animal models recapitulate much of the A‐T phenotype, they fail to present with ataxia or neurodegeneration. We describe here the generation of an Atm missense mutant [amino acid change of leucine (L) to proline (P) at position 2262 (L2262P)] rat by intracytoplasmic injection (ICSI) of mutant sperm into oocytes. Atm‐mutant rats (AtmL2262P/L2262P) expressed low levels of ATM protein, suggesting a destabilizing effect of the mutation, and had a significantly reduced lifespan compared with Atm+/+. Whereas these rats did not show cerebellar atrophy, they succumbed to hind‐limb paralysis (45%), and the remainder developed tumors. Closer examination revealed the presence of both dsDNA and ssDNA in the cytoplasm of cells in the hippocampus, cerebellum, and spinal cord of AtmL2262P/L2262P rats. Significantly increased levels of IFN‐β and IL‐1β in all 3 tissues were indicative of DNA damage induction of the type 1 IFN response. This was further supported by NF‐κB activation, as evidenced by p65 phosphorylation (P65) and translocation to the nucleus in the spinal cord and parahippocampus. Other evidence of neuroinflammation in the brain and spinal cord was the loss of motor neurons and the presence of increased activation of microglia. These data provide support for a proinflammatory phenotype that is manifested in the Atm mutant rat as hind‐limb paralysis. This mutant represents a useful model to investigate the importance of neuroinflammation in A‐T. [ABSTRACT FROM AUTHOR]

Background: Despite significant endeavor having been applied to identify effective therapies to treat glioblastoma (GBM), survival outcomes remain intractable. The greatest nonsurgical benefit arises from radiotherapy, though tumors typically recur due to robust DNA repair. Patients could therefore benefit from therapies with the potential to prevent DNA repair and synergize with radiotherapy. In this work, we investigated the potential of salinomycin to enhance radiotherapy and further uncover novel dual functions of this ionophore to induce DNA damage and prevent repair., Methods: In vitro primary GBM models and ex vivo GBM patient explants were used to determine the mechanism of action of salinomycin by immunoblot, flow cytometry, immunofluorescence, immunohistochemistry, and mass spectrometry. In vivo efficacy studies were performed using orthotopic GBM animal xenograft models. Salinomycin derivatives were synthesized to increase drug efficacy and explore structure-activity relationships., Results: Here we report novel dual functions of salinomycin. Salinomycin induces toxic DNA lesions and prevents subsequent recovery by targeting homologous recombination (HR) repair. Salinomycin appears to target the more radioresistant GBM stem cell-like population and synergizes with radiotherapy to significantly delay tumor formation in vivo. We further developed salinomycin derivatives which display greater efficacy in vivo while retaining the same beneficial mechanisms of action., Conclusion: Our findings highlight the potential of salinomycin to induce DNA lesions and inhibit HR to greatly enhance the effect of radiotherapy. Importantly, first-generation salinomycin derivatives display greater efficacy and may pave the way for clinical testing of these agents., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Neuro-Oncology.)

Background: Neuroinflammation and biometal dyshomeostasis are key pathological features of several neurodegenerative diseases, including Alzheimer's disease (AD). Inflammation and biometals are linked at the molecular level through regulation of metal buffering proteins such as the metallothioneins. Even though the molecular connections between metals and inflammation have been demonstrated, little information exists on the effect of copper modulation on brain inflammation. Methods: We demonstrate the immunomodulatory potential of the copper bis(thiosemicarbazone) complex Cu II (atsm) in an neuroinflammatory model in vivo and describe its anti-inflammatory effects on microglia and astrocytes in vitro . Results: By using a sophisticated in vivo magnetic resonance imaging (MRI) approach, we report the efficacy of Cu II (atsm) in reducing acute cerebrovascular inflammation caused by peripheral administration of bacterial lipopolysaccharide (LPS). Cu II (atsm) also induced anti-inflammatory outcomes in primary microglia [significant reductions in nitric oxide (NO), monocyte chemoattractant protein 1 (MCP-1), and tumor necrosis factor (TNF)] and astrocytes [significantly reduced NO, MCP-1, and interleukin 6 (IL-6)] in vitro . These anti-inflammatory actions were associated with increased cellular copper levels and increased the neuroprotective protein metallothionein-1 (MT1) in microglia and astrocytes. Conclusion: The beneficial effects of Cu II (atsm) on the neuroimmune system suggest copper complexes are potential therapeutics for the treatment of neuroinflammatory conditions.

Ataxia-telangiectasia (A-T), an autosomal recessive disease caused by mutations in the ATM gene is characterised by cerebellar atrophy and progressive neurodegeneration which has been poorly recapitulated in Atm mutant mice. Consequently, pathways leading to neurodegeneration in A-T are poorly understood. We describe here the generation of an Atm knockout rat model that does not display cerebellar atrophy but instead paralysis and spinal cord atrophy, reminiscent of that seen in older patients and milder forms of the disorder. Loss of Atm in neurons and glia leads to accumulation of cytosolic DNA, increased cytokine production and constitutive activation of microglia consistent with a neuroinflammatory phenotype. Rats lacking ATM had significant loss of motor neurons and microgliosis in the spinal cord, consistent with onset of paralysis. Since short term treatment with steroids has been shown to improve the neurological signs in A-T patients we determined if that was also the case for Atm-deficient rats. Betamethasone treatment extended the lifespan of Atm knockout rats, prevented microglial activation and significantly decreased neuroinflammatory changes and motor neuron loss. These results point to unrepaired damage to DNA leading to significant levels of cytosolic DNA in Atm-deficient neurons and microglia and as a consequence activation of the cGAS-STING pathway and cytokine production. This in turn would increase the inflammatory microenvironment leading to dysfunction and death of neurons. Thus the rat model represents a suitable one for studying neurodegeneration in A-T and adds support for the use of anti-inflammatory drugs for the treatment of neurodegeneration in A-T patients., (© The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)