Microglial replacement therapy: a potential therapeutic strategy for incurable CSF1R-related leukoencephalopathy (original) (raw)
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Loss of homeostatic microglial phenotype in CSF1R-related Leukoencephalopathy
Acta Neuropathologica Communications, 2020
Microglia are resident macrophages of the central nervous system, and their unique molecular signature is dependent upon CSF-1 signaling. Previous studies have demonstrated the importance of CSF-1R in survival and development of microglia in animal models, but the findings are of uncertain relevance to understanding the influence of CSF-1R on microglia in humans. Hereditary diffuse leukoencephalopathy with spheroids (HDLS) [also known as adult onset leukoencephalopathy with spheroids and pigmented glia (ALSP)] is a neurodegenerative disorder primarily affecting cerebral white matter, most often caused by mutations of CSF1R. Therefore, we hypothesized that the molecular profile of microglia may be affected in HDLS. Semi-quantitative immunohistochemistry and quantitative transcriptomic profiling revealed reduced expression of IBA-1 and P2RY12 in both white and gray matter microglia of HDLS. In contrast, there was increased expression of CD68 and CD163 in microglia in affected white ma...
Glia, 2020
Adult onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) is a dementia resulting from dominantly inherited CSF1R inactivating mutations. The Csf1r +/− mouse mimics ALSP symptoms and pathology. Csf1r is mainly expressed in microglia, but also in cortical layer V neurons that are gradually lost in Csf1r+/− mice with age. We therefore examined whether microglial or neuronal Csf1r loss caused neurodegeneration in Csf1r+/− mice. The behavioral deficits, pathologies and elevation of Csf2 expression contributing to disease, previously described in the Csf1r +/− ALSP mouse, were reproduced by microglial deletion (MCsf1r het mice), but not by neural deletion. Furthermore, increased Csf2 expression by callosal astrocytes, oligodendrocytes, and microglia was observed in Csf1r +/− mice and, in MCsf1r het mice, the densities of these three cell types were increased in supraventricular patches displaying activated microglia, an early site of disease pathology. These data confirm that ALSP is a primary microgliopathy and inform future therapeutic and experimental approaches.
Molecular neurodegeneration, 2024
Background Induced pluripotent stem cell-derived microglia (iMGL) represent an excellent tool in studying microglial function in health and disease. Yet, since differentiation and survival of iMGL are highly reliant on colony-stimulating factor 1 receptor (CSF1R) signaling, it is difficult to use iMGL to study microglial dysfunction associated with pathogenic defects in CSF1R. Methods Serial modifications to an existing iMGL protocol were made, including but not limited to changes in growth factor combination to drive microglial differentiation, until successful derivation of microglia-like cells from an adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) patient carrying a c.2350G > A (p.V784M) CSF1R variant. Using healthy control lines, the quality of the new iMGL protocol was validated through cell yield assessment, measurement of microglia marker expression, transcriptomic comparison to primary microglia, and evaluation of inflammatory and phagocytic activities. Similarly, molecular and functional characterization of the ALSP patient-derived iMGL was carried out in comparison to healthy control iMGL. Results The newly devised protocol allowed the generation of iMGL with enhanced transcriptomic similarity to cultured primary human microglia and with higher scavenging and inflammatory competence at ~ threefold greater yield compared to the original protocol. Using this protocol, decreased CSF1R autophosphorylation and cell surface expression was observed in iMGL derived from the ALSP patient compared to those derived from healthy controls. Additionally, ALSP patient-derived iMGL presented a migratory defect accompanying a temporal reduction in purinergic receptor P2Y12 (P2RY12) expression, a heightened capacity to internalize myelin, as well as heightened inflammatory response to Pam 3 CSK 4. Poor P2RY12 expression was confirmed to be a consequence of CSF1R haploinsufficiency, as this feature was also observed following CSF1R knockdown or inhibition in mature control iMGL, and in CSF1R WT/KO and CSF1R WT/E633K iMGL compared to their respective isogenic controls.
Microglial homeostasis requires balanced CSF-1/CSF-2 receptor signaling
2019
SummaryCSF-1R haploinsufficiency causes adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). Previous studies in the Csf1r+/- mouse model of ALSP hypothesized a central role of elevated cerebral Csf2 expression. Here we show that monoallelic deletion of Csf2 rescues most behavioral deficits and histopathological changes in Csf1r+/- mice by preventing microgliosis and eliminating most microglial transcriptomic alterations, including those indicative of oxidative stress and demyelination. We also show elevation of Csf2 transcripts and of several CSF-2 downstream targets in the brains of ALSP patients, demonstrating that the mechanisms identified in the mouse model are functional in man. Our data provide new insights into the mechanisms underlying ALSP. Since both increased CSF2 levels and decreased microglial Csf1r expression have also been reported in Alzheimer’s disease and multiple sclerosis, we suggest that the unbalanced CSF-1R/CSF-2 signaling we descr...
CSF1R Stimulation Promotes Increased Neuroprotection by CD11c+ Microglia in EAE
Frontiers in Cellular Neuroscience
Microglia are resident immune cells of the central nervous system. Their development and maintenance depend on stimulation of Colony Stimulating Factor-1 receptor (CSF1R). Microglia play an important role in neurodevelopment and a population of microglia that expresses the complement receptor CD11c is critical for primary myelination. This population is virtually absent in the healthy adult brain but increases dramatically upon neuroinflammatory conditions, and these microglia are suggested to play a protective role in central nervous system (CNS) diseases. To date, the molecular trigger for their expansion is unknown. Here we showed that stimulation of CSF1R by either of its ligands, CSF1 and interleukin (IL)-34, can induce expansion of CD11c+ microglia. In addition, such stimulation resulted in amelioration of EAE symptoms and decreased demyelination. Treatment with CSF1R ligands also induced expression of the chemokine CCL2, and we showed that experimental overexpression of CCL2 in the brain led to a dramatic increase of CD11c+ microglia, independent of CCR2. Moreover, this led to elevated CSF1 expression, suggesting a positive feedback loop between CSF1R and CCL2. These data provide new insights to microglia biology and open new perspectives for modulating microglial activity in neuroinflammatory diseases such as multiple sclerosis.
Neuron, 2014
The colony-stimulating factor 1 receptor (CSF1R) is a key regulator of myeloid lineage cells. Genetic loss of the CSF1R blocks the normal population of resident microglia in the brain that originates from the yolk sac during early development. However, the role of CSF1R signaling in microglial homeostasis in the adult brain is largely unknown. To this end, we tested the effects of selective CSF1R inhibitors on microglia in adult mice. Surprisingly, extensive treatment results in elimination of $99% of all microglia brainwide, showing that microglia in the adult brain are physiologically dependent upon CSF1R signaling. Mice depleted of microglia show no behavioral or cognitive abnormalities, revealing that microglia are not necessary for these tasks. Finally, we discovered that the microglia-depleted brain completely repopulates with new microglia within 1 week of inhibitor cessation. Microglial repopulation throughout the CNS occurs through proliferation of nestin-positive cells that then differentiate into microglia. Neuron CSF1R Regulates Resident Microglia Neuron 82, 380-397, April 16, 2014 ª2014 Elsevier Inc. 381
2021
Amino acid substitutions in the kinase domain of the human CSF1R gene are associated with autosomal dominant adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). To model the human disease, we created a disease-associated mutation (Glu631Lys; E631K) in the mouse Csf1r locus. Homozygous mutation (Csf1rE631K/E631K) phenocopied the Csf1r knockout; with prenatal mortality or severe postnatal growth retardation and hydrocephalus. Heterozygous mutation delayed the postnatal expansion of tissue macrophage populations in most organs. Bone marrow cells from Csf1rE631K/+ mice were resistant to CSF1 stimulation in vitro, and Csf1rE631K/+ mice were unresponsive to administration of a CSF1-Fc fusion protein which expands tissue macrophage populations in controls. In the brain, microglial cell numbers and dendritic arborization were reduced in the Csf1rE631K/+ mice as in ALSP patients. The microglial phenotype is the opposite of microgliosis observed in Csf1r+/- mice. ...
International journal of …, 1995
this study we used op/op mice, which are deficient in the hematopoietic cytokine, colony-stimulating factor 1 (CSF-1), to determine the effect of CSF-I on neuronal survival and microglial response in injury. In normal mice microglia express the CSF-1 receptor and are primarily regulated by CSF-1, produced mainly by astrocytes. The CSF-1 deficiency in op/op mice results in a depletion in the number of monocytes and macrophages but does not affect the number or morphology of microglia. We produced an ischemic lesion in the cerebral cortex of mice by disrupting the pia-arachnoid blood vessels in a defined area. Using Nissl stain and astrocyte-and microglia-specific antibodies, we determined the number of viable neurons in such injury and the intensity of glial reaction. The cellular response to injury on the operated side of op/op mice was compared to that on the non-operated contralateral side and to the cellular response in similar lesions in CSF-1 producing C3H/HeJ mice. We found that the systemic lack of CSF-1 in op/op mice results in a significant increase in neuron vulnerability to ischemic injury and considerably reduced microglial response to neuron injury. Remedying the CSF-1 deficiency, either by grafting CSF-1 secreting astroglia into the brain or by implanting encapsulated CSF-1 secreting fibroblast-like cells into the peritoneum, partially restores the microglial response to neuron injury and significantly potentiates neuronal survival in cerebral cortex ischemic lesions. Astroglial reaction was approximately the same in the lesions in op/op mice, grafted and implanted op/op mice and C3H/HeJ mice, indicating that CSF-1 modulates microglia, but not the response of astrocytes to injury. The degree of neuronal survival was not correlated to the degree of microglial proliferation and intensity of their reaction. We report some indications that CSF-1, in addition to modulation of microglia, may also act directly on neurons.
Journal of Neuroscience Research, 2009
It is still debated whether microglia play a beneficial or harmful role in myelin disorders such as multiple sclerosis and leukodystrophies as well as in other pathological conditions of the central nervous system. The osteopetrotic (op/op) mouse has reduced numbers of cells of monocyte lineage as a result of an inactivating mutation in the colony stimulating factor-1 gene. To determine whether this mutant mouse might be used to study the role of microglia in myelin disorders, we quantified the number of microglia in the central nervous system of op/op mice and explored their ability to respond to brain injury created by a stab wound. Microglial density in the 2-month-old op/op mice was significantly decreased in the white matter tracts compared with thege matched wild-type controls (by 63.6% in the corpus callosum and 86.4% in the spinal dorsal column), whereas the decrease was less in the gray matter, cerebral cortex (24.0%). A similar decrease was seen at 7 months of age. Morphometric studies of spinal cord myelination showed that development of myelin was not affected in op/op mice. In response to a stab wound, the increase in the number of microglia/macrophages in op/op mice was significantly less pronounced than that in wild-type control. These findings demonstrate that this mutant is a valuable model in which to study roles of microglia/macrophages in the pathophysiology of myelin disorders. Keywords osteopetrotic mice; op/op mice; myelin Microglia, the resident macrophages in the central nervous system (CNS), were originally described solely as phagocytes that clear cell debris in the CNS (reviewed in Rezaie and Male, 2002). However, as new functions of microglia and macrophages in the CNS have been discovered, the roles of these cells in various CNS pathophysiologies have become more complex and controversial (
Is Pre‐Symptomatic Immunosuppression Protective in CSF1R ‐ Related Leukoencephalopathy?
Movement Disorders, 2021
Adult-onset leukoencephalopathy with spheroids and pigmented glia (ALSP) is the collective disease referring to patients previously diagnosed with hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) or pigmented orthochromatic leukodystrophy (POLD). ALSP is a white matter disease with a complex neurological phenotype consisting of pyramidal tract dysfunction, parkinsonism, and frontal-predominant cognitive impairment. 1 This autosomal-dominant disease typically affects females earlier than males with symptom onset in the fourth decade of life and average disease duration of 7 years. 2 In 2011, a mutation in the colony-stimulating factor 1 receptor (CSF1R) gene was first identified in the initial collection of HDLS families. 3 Two separate POLD families were later found to carry CSF1R mutations, therefore confirming that HDLS and POLD were actually a single CSF1R-related leukoencephalopathy. 1 There are now more than 70 different pathogenic mutations, most of which occur in the tyrosine kinase domain resulting in disruption of protein function. 4 The disease is currently known as CSF1R-related leukoencephalopathy to distinguish it from a somewhat similar condition produced by mutations in the AARS2 gene 5 or other unknown genetic causes. For the