TREM2 deficiency eliminates TREM2+ inflammatory macrophages and ameliorates pathology in Alzheimer’s disease mouse models

Jay, Taylor R.; Miller, Crystal; Cheng, Paul J.; Graham, Leah C.; Bemiller, Shane M.; Broihier, Margaret L.; Xu, Guixiang; Margevicius, Daniel; Karlo, J. Colleen; Sousa, Gregory L.; Cotleur, Anne C.; Butovsky, Oleg; Bekris, Lynn M.; Staugaitis, Susan M.; Leverenz, James B.; Pimplikar, Sanjay W.; Landreth, Gary E.; Howell, Gareth R.; Ransohoff, Richard M.; Lamb, Bruce T.

doi:10.1084/jem.20142322

Cited by 544 publications

(603 citation statements)

References 32 publications

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“…Variants in these genes, especially in TREM2 and CD33, are associated with compromised phagocytic function of peripheral monocytes or macrophages and altered Aβ accumulation in AD brains 24,51 . Interestingly, CR1 (encoding complement receptor-1, also known as CD35) is expressed primarily in peripheral leukocytes and erythrocytes, but not in any brain cells.…”

Section: Disorders Of Systemic Immunitymentioning

confidence: 99%

A systemic view of Alzheimer disease — insights from amyloid-β metabolism beyond the brain

et al. 2017

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The global burden of Alzheimer disease (AD), already the most common type of dementia, is expected to increase still further owing to population ageing. AD not only causes severe distress for patients and caregivers, but also results in a large economic burden on society. Current major challenges in AD include the lack of reliable biomarkers for its early diagnosis, as well as the lack of effective preventive strategies and treatments 1,2 . Thus, increased understanding of the molecular patho genesis of AD could lead to the development of improved diagnostic and therapeutic strategies.AD is conventionally regarded as a CNS disorder. However, increasing experimental, epidemiological and clinical evidence has suggested that manifestations of AD extend beyond the brain. These systemic alterations might not be simply secondary effects of the cerebral degeneration seen in AD, but could reflect under lying processes linked to progression of the disease. AD pathogenesis is complex, involving abnormal amyloid-β (Aβ) metabolism, tau hyperphosphorylation, oxidative stress, reactive glial and microglial changes, and other pathological events. Given that Aβ is a major hallmark of AD and a fertile area of research in this disease, this Review focuses on the systemic role of Aβ in AD. We discuss the communication between peripheral and central pools of Aβ, and describe interactions between systemic abnormalities and AD pathogenesis in the brain. We review emerging findings of associations between systemic abnormalities and Aβ metabolism, and describe how these associations might interact with or reflect on the central pathways of Aβ production and clearance. On the basis of these findings, we suggest that interactions between the brain and the periphery might have a crucial role in the development and progression of AD. Aβ biogenesis and catabolismA steady accrual of data from laboratories and clinics is providing increasing support for the concept that an imbalance between the production and clearance of Aβ is a very early (and often initiating) factor in AD 3 . Normal metabolism of Aβ and maintenance of the homeostatic balance between Aβ production and clearance is, therefore, essential to maintain brain health. In fact, physiological metabolism of Aβ occurs not only in the brain but also in the periphery, and communication between these regions is possible (FIG. 1). Central and peripheral production of AβAβ is derived from the proteolytic cleavage of amyloid precursor protein (APP), which is expressed not only in brain cells, including neurons, astrocytes and microglia, but also in peripheral organs and tissues, such as the Abstract | Alzheimer disease (AD) is the most common type of dementia, and is currently incurable; existing treatments for AD produce only a modest amelioration of symptoms. Research into this disease has conventionally focused on the CNS. However, several peripheral and systemic abnormalities are now understood to be linked to AD, and our understanding of how these alterations contribute to AD is becom...

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Section: Disorders Of Systemic Immunitymentioning

confidence: 99%

A systemic view of Alzheimer disease — insights from amyloid-β metabolism beyond the brain

et al. 2017

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“…However, recent work demonstrated that loss of Trem2 leads either to microglial degeneration in different diseases of the central nervous system [55,66,11], or conversely to protection [34]. Thus, the exact mechanisms underlying 5-HT 2B R-mediated regulation of microglial survival and the role of scavenger receptors in this response will have to be investigated in further studies.…”

Section: Discussionmentioning

confidence: 99%

Serotonin 2B receptor slows disease progression and prevents degeneration of spinal cord mononuclear phagocytes in amyotrophic lateral sclerosis

et al. 2016

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Abstract:Microglia are the resident phagocytes of the central nervous system and have been implicated in the pathogenesis of neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS). During neurodegeneration, microglial activation is accompanied by infiltration of circulating monocytes, leading to overall increased phagocytic activity and production of multiple inflammatory mediators in the spinal cord. Degenerative alterations in monocytes and microglia are commonly observed during neurodegenerative diseases, yet little is known concerning the mechanisms leading to their degeneration, or the consequences on disease progression. Here we observed that the serotonin 2B receptor (5-HT 2B ), a serotonin receptor expressed in microglia, is upregulated in the spinal cord of three different transgenic mouse models of ALS. In mutant SOD1 mice, this upregulation was restricted to cells positive for CD11b, a marker of mononuclear phagocytes. Ablation of 5-HT 2B receptor in transgenic ALS mice expressing mutant SOD1 resulted in increased degeneration of mononuclear phagocytes, as evidenced by fragmentation of Iba1-positive cellular processes. This was accompanied by decreased expression of key neuroinflammatory genes but also loss of expression of homeostatic microglial genes. Importantly, the dramatic effect of 5-HT 2B receptor ablation on mononuclear phagocytes was associated with acceleration of disease progression. To determine the translational relevance of these results, we studied polymorphisms in the human HTR2B gene, which encodes the 5-HT 2B receptor, in a large cohort of ALS patients. In this cohort, the C allele of SNP rs10199752 in HTR2B was associated with longer survival. Moreover, patients carrying one copy of the C allele of SNP rs10199752 showed increased 5-HT 2B mRNA in spinal cord and displayed less pronounced degeneration of mononuclear phagocytes than patients carrying two copies of the more common A allele. Thus functional 5-HT 2B receptors limit degeneration of spinal cord macrophages (most likely microglia), and slow disease progression in ALS. Targeting this receptor might be therapeutically useful.

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“…However, chronic activation of these cells shift microglia to a more proinflammatory and less phagocytic state (9, 10). Although much of the data implicating microglia in AD has come from neuropathological investigation, recent genome-wide association studies have provided the first genetic evidence (to our knowledge) linking microglia dysfunction to AD, with the discovery of risk polymorphisms in several immune system genes: CR1, TREM2, CD33, HLA-DRB5, MS4A6A, and ABCA7 (8,(11)(12)(13)(14)(15).In contrast to the field's increasing understanding of the role of innate immunity in AD, comparatively little is known about whether the adaptive immune system might also influence AD. Those studies that have examined these peripheral populations have largely focused on questions about their potential as biomarkers or their role in active Aβ immunization (3, 16).…”

mentioning

confidence: 99%

mentioning

confidence: 99%

The adaptive immune system restrains Alzheimer’s disease pathogenesis by modulating microglial function

Marsh

Abud

Lakatos

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

321

264

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The innate immune system is strongly implicated in the pathogenesis of Alzheimer's disease (AD). In contrast, the role of adaptive immunity in AD remains largely unknown. However, numerous clinical trials are testing vaccination strategies for AD, suggesting that T and B cells play a pivotal role in this disease. To test the hypothesis that adaptive immunity influences AD pathogenesis, we generated an immune-deficient AD mouse model that lacks T, B, and natural killer (NK) cells. The resulting "Rag-5xfAD" mice exhibit a greater than twofold increase in β-amyloid (Aβ) pathology. Gene expression analysis of the brain implicates altered innate and adaptive immune pathways, including changes in cytokine/chemokine signaling and decreased Ig-mediated processes. Neuroinflammation is also greatly exacerbated in Rag-5xfAD mice as indicated by a shift in microglial phenotype, increased cytokine production, and reduced phagocytic capacity. In contrast, immune-intact 5xfAD mice exhibit elevated levels of nonamyloid reactive IgGs in association with microglia, and treatment of Rag-5xfAD mice or microglial cells with preimmune IgG enhances Aβ clearance. Last, we performed bone marrow transplantation studies in Rag-5xfAD mice, revealing that replacement of these missing adaptive immune populations can dramatically reduce AD pathology. Taken together, these data strongly suggest that adaptive immune cell populations play an important role in restraining AD pathology. In contrast, depletion of B cells and their appropriate activation by T cells leads to a loss of adaptiveinnate immunity cross talk and accelerated disease progression.is the leading cause of age-related neurodegeneration, affecting over 5.2 million people in the United States alone (1). Pathologically, AD is characterized by two hallmark protein aggregates, amyloid-β (Aβ) plaques and neurofibrillary tangles, that are accompanied by neuroinflammation, including microgliosis, elevated cytokine production, and activation of complement pathways (2-5). Initially, microglia respond to and surround plaques, degrading Aβ by phagocytosis (for review, see refs. 6-8). However, chronic activation of these cells shift microglia to a more proinflammatory and less phagocytic state (9, 10). Although much of the data implicating microglia in AD has come from neuropathological investigation, recent genome-wide association studies have provided the first genetic evidence (to our knowledge) linking microglia dysfunction to AD, with the discovery of risk polymorphisms in several immune system genes: CR1, TREM2, CD33, HLA-DRB5, MS4A6A, and ABCA7 (8,(11)(12)(13)(14)(15).In contrast to the field's increasing understanding of the role of innate immunity in AD, comparatively little is known about whether the adaptive immune system might also influence AD. Those studies that have examined these peripheral populations have largely focused on questions about their potential as biomarkers or their role in active Aβ immunization (3, 16). However, the adaptive and innate immune systems rarely fu...

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TREM2 deficiency eliminates TREM2+ inflammatory macrophages and ameliorates pathology in Alzheimer’s disease mouse models

Abstract: Jay and colleagues show that TREM2 deficiency reduces the number of macrophages infiltrating the brain and is protective against disease pathogenesis in mouse models of Alzheimer’s disease.

Cited by 544 publications

References 32 publications

A systemic view of Alzheimer disease — insights from amyloid-β metabolism beyond the brain

A systemic view of Alzheimer disease — insights from amyloid-β metabolism beyond the brain

Serotonin 2B receptor slows disease progression and prevents degeneration of spinal cord mononuclear phagocytes in amyotrophic lateral sclerosis

The adaptive immune system restrains Alzheimer’s disease pathogenesis by modulating microglial function

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