Neuroimmune and Inflammatory Signals in Complex Disorders of the Central Nervous System (original) (raw)
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The brain, traditionally regarded as immune-privileged due to the blood-brain barrier, harbors a sophisticated immune system crucial for maintaining neural health and resilience against various challenges. Microglia, the resident immune cells of the central nervous system, actively monitor their environment, participating in immune surveillance, synaptic pruning, and neuroprotection. Astrocytes also play vital roles by regulating neurotransmitter levels, supporting metabolism, and maintaining the blood-brain barrier integrity. Recent research underscores the involvement of T cells and monocytes in modulating neuroinflammation and immune responses within the brain. Neurological disorders such as Alzheimer's and Parkinson's disease highlight the brain's vulnerability to immune dysregulation. This review aimed to elucidate the role of neuroimmune cells in brain health and the progression of neurological diseases. It aimed to identify critical mechanisms to enhance therapeutic strategies and improve outcomes. Understanding these interactions is essential for developing targeted therapies to mitigate neuroinflammation and preserve cognitive functions. This review critically examines neuroinflammation related to aging and disease, with a focus on neuroimmune cells and their underlying mechanisms. It highlights how chronic inflammation, driven by activated microglia and astrocytes, exacerbates neuronal damage, synaptic dysfunction, and cognitive decline. The disruption of immune privilege in these conditions involves complex pathways that trigger inflammatory responses, impairing essential neural functions. Despite its immune-privileged status, the brain's immune system, primarily involving microglia and astrocytes, is crucial for maintaining homeostasis and managing illness. Our review strongly suggests that neurological diseases, influenced by genetic, environmental, and aging factors, often involve heightened neuroinflammation. Targeted therapies are needed to address infections, chronic inflammation, and environmental impacts. Additionally, research into mental health disorders and advancements in imaging techniques are critical for understanding immune dysfunction and enhancing treatment strategies.
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Neuroinflammation is instigated by the misfiring of immune cells in the central nervous system (CNS) involving microglia and astrocytes as key cell-types. Neuroinflammation is a consequence of CNS injury, infection, toxicity, or autoimmunity. It is favorable as well as a detrimental process for neurodevelopment and associated processes. Transient activation of inflammatory response involving release of cytokines and growth factors positively affects the development and post-injury tissue. However, chronic or uncontrolled inflammatory responses may lead to various neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis, and multiple sclerosis. These diseases have variable clinical and pathological features, but are underlaid by the aggregation of misfolded proteins with a cytotoxic effect. Notably, abnormal activation of glial cells could mediate neuroinflammation, leading to the neurodegenerative condition. Micr...
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Microglia has emerged not only as an essential inflammatory cell but also as a major player in the development of the adult brain. Microglia phagocytize extra-numerical synapses during postnatal development, maintain and strengthen the remaining subset of synapses, remodel synaptic circuits and clearing apoptotic newborn neurons. Thereby, microglia plays a crucial role for the establishment, plasticity and function of adult neural circuits. In addition to the key role in normal brain function, any imbalance in microglia activity has been associated with neurodegenerative diseases. Microglial cells respond rapidly to smallest pathological changes, this being a vital aspect in many tissue scaring and the local confinement of focal lesions. It is assumed that the high motility of microglial cells represents an important requirement to fulfill the numerous functions. In this review will highlight the role of microglial motility in the healthy and the injured brain, and discuss how impai...
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Neuroinflammation is now recognised as an important contributory factor in the progression of Alzheimer’s disease and probably also in the early stages of the disease. It is likely that this derives largely from aberrant activation of microglia, the resident mononuclear phagocytes of the brain. These cells are responsible for physiological immune surveillance and clearance of pathogens in the central nervous system, but evidence indicates that in Alzheimer’s disease, microglial function is compromised, and this contributes to the pathology. It is unclear what factors cause the inappropriate activation of the microglia in Alzheimer’s disease, but one contributor may be infiltrating peripheral immune cells and these include macrophages and T cells. It has been suggested that both cell types modulate the phenotype of microglia, highlighting the importance of crosstalk between the innate and adaptive immune system in Alzheimer’s disease. This review outlines our current knowledge of how...