Neuroscience
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Extensive evidence implicates inflammation in multiple phases of stroke etiology and pathology. In particular, there is growing awareness that inflammatory events outside the brain have an important impact on stroke susceptibility and outcome. ⋯ Here, we provide an overview of the impact of systemic inflammation on stroke susceptibility and outcome. We discuss potential mechanisms underlying the impact on ischemic brain injury and highlight the implications for stroke prevention, therapy and modeling.
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Review
Imaging of inflammation in the peripheral and central nervous system by magnetic resonance imaging.
Inflammation plays a central role in the pathophysiology of numerous disorders of the nervous system, but is also pivotal for repair processes like peripheral nerve regeneration. In this review we summarize recent advances in cellular magnetic resonance imaging (MRI) while nuclear imaging methods to visualize neuroinflammation are covered by Wunder et al. [Wunder A, Klohs J, Dirnagl U (2009) Non-invasive imaging of central nervous system inflammation with nuclear and optical imaging. Neuroscience, in press]. ⋯ Iron oxide-contrast-enhanced MRI allowed in vivo visualization of cellular inflammation during wallerian degeneration, experimental autoimmune neuritis and encephalomyelitis, and stroke in rodents, but also in patients with multiple sclerosis and stroke. Importantly, cellular MRI provides additional information to gadolinium-DTPA-enhanced MRI since cellular infiltration and breakdown of the blood-brain barrier are not closely linked. Coupling of antibodies to iron oxide particles opens new avenues for molecular MRI and has been successfully used to visualize cell adhesion molecules guiding inflammation.
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Following injury to the nervous system, the activation of macrophages, microglia, and T-cells profoundly affects the ability of neurons to survive and to regenerate damaged axons. The primary visual pathway provides a well-defined model system for investigating the interactions between the immune system and the nervous system after neural injury. ⋯ T cells modulate this response, whereas microglia are thought to contribute to the loss of retinal ganglion cells in this model and in certain ocular diseases. This review discusses the complex and sometimes paradoxical actions of blood-borne macrophages, resident microglia, and T-cells in determining the outcome of injury in the primary visual pathway.
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Neurodegeneration and signs of immune activation, with T cell infiltration, major histocompatibility complex class II expression and glial activation, occur in many neurological diseases. Although particular qualities of the inflammatory response have been proposed to be of importance, still very little is known about the exact factors that determine susceptibility to neurodegeneration. Mechanistic studies have yielded conflicting results, where inflammation is suggested both to attenuate and aggravate loss of nerve cells depending on the circumstances. ⋯ We here review emerging evidence using this approach that indicates different pathways related both to adaptive and local innate immune responses, which determine strain-specific susceptibility to neuroimmune inflammation and neurodegeneration. Exact positioning of genes in these types of complex traits will be important for the understanding of pathogenetic mechanisms and to direct the focus of functional studies using classical experimental tools. Ultimately, a better knowledge about the interplay between the nervous system and the local and systemic immune system can define new ways of intervention in neurodegenerative processes.