Cytokine networks in neuroinflammation
TL;DR: Recent observations on the impact of dysregulated cytokine networks in neuroinflammation are summarized.
Abstract: Cytokines provide cells with the ability to communicate with one another and orchestrate complex multicellular behaviour. There is an emerging understanding of the role that cytokines play in normal homeostatic tissue function and how dysregulation of these cytokine networks is associated with pathological conditions. The central nervous system (CNS), where few blood-borne immune cells circulate, seems to be particularly vulnerable to dysregulated cytokine networks. In degenerative diseases, such as proteopathies, CNS-resident cells are the predominant producers of pro-inflammatory cytokines. By contrast, in classical neuroinflammatory diseases, such as multiple sclerosis and encephalitides, pro-inflammatory cytokines are mainly produced by tissue-invading leukocytes. Whereas the effect of dysregulated cytokine networks in proteopathies is controversial, cytokines delivered to the CNS by invading immune cells are in general detrimental to the tissue. Here, we summarize recent observations on the impact of dysregulated cytokine networks in neuroinflammation.
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TL;DR: High‐dimensional cytometry reveals that microglia, several subsets of border‐associated macrophages and dendritic cells coexist in the CNS at steady state and exhibit disease‐specific transformations in the immune microenvironment during aging and in models of Alzheimer’s disease and multiple sclerosis.
635 citations
Cites background from "Cytokine networks in neuroinflammat..."
...CNS infiltration into the parenchyma is a hallmark of neuro-inflammation (Becher et al., 2017)....
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...…parenchyma became homogeneously reactive during EAE, compared to a small subpopulation of responsive microglia during aging and AD, is likely due to the great amount of cytokines and other inflammatory mediators delivered to the CNS by invading leukocytes during EAE (Becher et al., 2016, 2017)....
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TL;DR: This review will describe the current state of knowledge concerning the biology of neuroinflammation, emphasizing mast cell-glia and glia- glia interactions, then conclude with a consideration of how a cell's endogenous mechanisms might be leveraged to provide a therapeutic strategy to target neuro inflammation.
Abstract: Inflammation is a complex biological response fundamental to how the body deals with injury and infection to eliminate the initial cause of cell injury and effect repair. Unlike a normally beneficial acute inflammatory response, chronic inflammation can lead to tissue damage and ultimately its destruction, and often results from an inappropriate immune response. Inflammation in the nervous system ("neuroinflammation"), especially when prolonged, can be particularly injurious. While inflammation per se may not cause disease, it contributes importantly to disease pathogenesis across both the peripheral (neuropathic pain, fibromyalgia) and central [e.g., Alzheimer disease, Parkinson disease, multiple sclerosis, motor neuron disease, ischemia and traumatic brain injury, depression, and autism spectrum disorder] nervous systems. The existence of extensive lines of communication between the nervous system and immune system represents a fundamental principle underlying neuroinflammation. Immune cell-derived inflammatory molecules are critical for regulation of host responses to inflammation. Although these mediators can originate from various non-neuronal cells, important sources in the above neuropathologies appear to be microglia and mast cells, together with astrocytes and possibly also oligodendrocytes. Understanding neuroinflammation also requires an appreciation that non-neuronal cell-cell interactions, between both glia and mast cells and glia themselves, are an integral part of the inflammation process. Within this context the mast cell occupies a key niche in orchestrating the inflammatory process, from initiation to prolongation. This review will describe the current state of knowledge concerning the biology of neuroinflammation, emphasizing mast cell-glia and glia-glia interactions, then conclude with a consideration of how a cell's endogenous mechanisms might be leveraged to provide a therapeutic strategy to target neuroinflammation.
293 citations
Cites background from "Cytokine networks in neuroinflammat..."
...When activated, they phagocytose cellular debris, present antigens to T cells and release cytokines/chemokines, the latter providing cells with the ability to communicate with one another and orchestrate complex multicellular behavior (Becher et al., 2017)....
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TL;DR: The meningeal lymphatic system can be viewed as a novel player in neurophysiology by altering the accessibility of CSF-borne immune neuromodulators to the brain parenchyma, thereby altering their effects on the brain.
265 citations
TL;DR: It is suggested that mast cell-associated inflammatory mediators from systemic inflammation and brain could augment neuroinflammation and neurodegeneration in the brain.
Abstract: Neuroinflammatory response is primarily a protective mechanism in the brain. However, excessive and chronic inflammatory responses can lead to deleterious effects involving immune cells, brain cells and signaling molecules. Neuroinflammation induces and accelerates pathogenesis of Parkinson’s disease (PD), Alzheimer’s disease (AD) and Multiple Sclerosis. Neuroinflammatory pathways are indicated as novel therapeutic targets for these diseases. Mast cells are immune cells of hematopoietic origin that regulate inflammation and upon activation release many proinflammatory mediators in systemic and central nervous system inflammatory conditions. In addition, inflammatory mediators released from activated glial cells induce neurodegeneration in the brain. Systemic inflammation-derived proinflammatory cytokines/chemokines and other factors cause a breach in the blood brain-barrier (BBB) thereby allowing for the entry of immune/inflammatory cells including mast cell progenitors, mast cells and proinflammatory cytokines and chemokines into the brain. These peripheral-derived factors and intrinsically generated cytokines/chemokines, α-synuclein, corticotropin-releasing hormone, substance P, beta amyloid 1-42 (Aβ1-42) peptide and amyloid precursor proteins can activate glial cells, T-cells and mast cells in the brain can induce additional release of inflammatory and neurotoxic molecules contributing to chronic neuroinflammation and neuronal death. The glia maturation factor, a proinflammatory protein discovered in our laboratory released from glia, activates mast cells to release inflammatory cytokines and chemokines. Chronic increase in the proinflammatory mediators induces neurotoxic Aβ and plaque formation in AD brains and neurodegeneration in PD brains. Glial cells, mast cells and T-cells can reactivate each other in neuroinflammatory conditions in the brain and augment neuroinflammation. Further, inflammatory mediators from the brain can also enter into the peripheral system through defective BBB, recruit immune cells into the brain, and exacerbate neuroinflammation. We suggest that mast cell-associated inflammatory mediators from systemic inflammation and brain could augment neuroinflammation and neurodegeneration in the brain. This review addresses the role of some atypical inflammatory mediators that are associated with mast cell inflammation and their activation of glial cells to induce neurodegeneration.
224 citations
Cites background from "Cytokine networks in neuroinflammat..."
...…and hormones released by the activated glial cells and injured neurons are involved in neuroinflammation in AD and PD pathogenesis (Tufekci et al., 2012; Pennisi et al., 2016; Becher et al., 2017; Gualtierotti et al., 2017; Rustenhoven et al., 2017; Sawikr et al., 2017; Song et al., 2017)....
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...Inflammatory mediators, neurotoxic mediators, inflammasomes and hormones released by the activated glial cells and injured neurons are involved in neuroinflammation in AD and PD pathogenesis (Tufekci et al., 2012; Pennisi et al., 2016; Becher et al., 2017; Gualtierotti et al., 2017; Rustenhoven et al., 2017; Sawikr et al., 2017; Song et al., 2017)....
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TL;DR: A single-cell characterization of cerebrospinal fluid and blood of newly diagnosed multiple sclerosis patients is provided, revealing altered composition of lymphocyte and monocyte subsets, validated by other methods including the interrogation of the TFH subset in mouse models of MS.
Abstract: Cerebrospinal fluid (CSF) protects the central nervous system (CNS) and analyzing CSF aids the diagnosis of CNS diseases, but our understanding of CSF leukocytes remains superficial. Here, using single cell transcriptomics, we identify a specific location-associated composition and transcriptome of CSF leukocytes. Multiple sclerosis (MS) - an autoimmune disease of the CNS - increases transcriptional diversity in blood, but increases cell type diversity in CSF including a higher abundance of cytotoxic phenotype T helper cells. An analytical approach, named cell set enrichment analysis (CSEA) identifies a cluster-independent increase of follicular (TFH) cells potentially driving the known expansion of B lineage cells in the CSF in MS. In mice, TFH cells accordingly promote B cell infiltration into the CNS and the severity of MS animal models. Immune mechanisms in MS are thus highly compartmentalized and indicate ongoing local T/B cell interaction.
220 citations
References
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TL;DR: This study’s findings can provide practical guidelines to steer partnership programs within the academic and clinical bodies, with the aim of providing a collaborative partnership approach to clinical education.
Abstract: The aim of our systematic review was to retrieve and integrate relevant evidence related to the process of formation and implementation of the academic–service partnership, with the aim of reformin...
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TL;DR: It has been more than 10 years since it was first proposed that the neurodegeneration in Alzheimer's disease (AD) may be caused by deposition of amyloid β-peptide in plaques in brain tissue and the rest of the disease process is proposed to result from an imbalance between Aβ production and Aβ clearance.
Abstract: It has been more than 10 years since it was first proposed that the neurodegeneration in Alzheimer9s disease (AD) may be caused by deposition of amyloid β-peptide (Aβ) in plaques in brain tissue. According to the amyloid hypothesis, accumulation of Aβ in the brain is the primary influence driving AD pathogenesis. The rest of the disease process, including formation of neurofibrillary tangles containing tau protein, is proposed to result from an imbalance between Aβ production and Aβ clearance.
12,652 citations
TL;DR: Findings provide a basis for understanding how inhibition of IFN-γ signaling enhances development of pathogenic TH-17 effector cells that can exacerbate autoimmunity.
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4,616 citations
TL;DR: In vivo, antibody to IL- 17 inhibited chemokine expression in the brain during experimental autoimmune encephalomyelitis, whereas overexpression of IL-17 in lung epithelium caused Chemokine production and leukocyte infiltration, indicating a unique T helper lineage that regulates tissue inflammation.
Abstract: Interleukin 17 (IL-17) has been linked to autoimmune diseases, although its regulation and function have remained unclear. Here we have evaluated in vitro and in vivo the requirements for the differentiation of naive CD4 T cells into effector T helper cells that produce IL-17. This process required the costimulatory molecules CD28 and ICOS but was independent of the cytokines and transcription factors required for T helper type 1 or type 2 differentiation. Furthermore, both IL-4 and interferon-γ negatively regulated T helper cell production of IL-17 in the effector phase. In vivo, antibody to IL-17 inhibited chemokine expression in the brain during experimental autoimmune encephalomyelitis, whereas overexpression of IL-17 in lung epithelium caused chemokine production and leukocyte infiltration. Thus, IL-17 expression characterizes a unique T helper lineage that regulates tissue inflammation.
4,196 citations
TL;DR: Using passive transfer studies, it is confirmed that these IL-23–dependent CD4+ T cells are highly pathogenic and essential for the establishment of organ-specific inflammation associated with central nervous system autoimmunity.
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4,027 citations