RESUMEN
Anti-ganglioside antibodies (anti-Gg Abs) have been linked to delayed/poor clinical recovery in both axonal and demyelinating forms of Guillain-Barrè Syndrome (GBS). In many instances, the incomplete recovery is attributed to the peripheral nervous system's failure to regenerate. The cross-linking of cell surface gangliosides by anti-Gg Abs triggers inhibition of nerve repair in both in vitro and in vivo axon regeneration paradigms. This mechanism involves the activation of the small GTPase RhoA, which negatively modulates the growth cone cytoskeleton. At present, the identity/es of the receptor/s responsible for transducing the signal that ultimately leads to RhoA activation remains poorly understood. The aim of this work was to identify the transducer molecule responsible for the inhibitory effect of anti-Gg Abs on nerve repair. Putative candidate molecules were identified through proteomic mass spectrometry of ganglioside affinity-captured proteins from rat cerebellar granule neurons (Prendergast et al., 2014). These candidates were evaluated using an in vitro model of neurite outgrowth with primary cultured dorsal root ganglion neurons (DRGn) and an in vivo model of axon regeneration. Using an shRNA-strategy to silence putative candidates on DRGn, we identified tumor necrosis factor receptor 1A protein (TNFR1A) as a transducer molecule for the inhibitory effect on neurite outgrowth from rat/mouse DRGn cultures of a well characterized mAb targeting the related gangliosides GD1a and GT1b. Interestingly, lack of TNFr1A expression on DRGn abolished the inhibitory effect on neurite outgrowth caused by anti-GD1a but not anti-GT1b specific mAbs, suggesting specificity of GD1a/transducer signaling. Similar results were obtained using primary DRGn cultures from TNFR1a-null mice, which did not activate RhoA after exposure to anti-GD1a mAbs. Generation of single point mutants at the stalk region of TNFR1A identified a critical amino acid for transducing GD1a signaling, suggesting a direct interaction. Finally, passive immunization with an anti-GD1a/GT1b mAb in an in vivo model of axon regeneration exhibited reduced inhibitory activity in TNFR1a-null mice compared to wild type mice. In conclusion, these findings identify TNFR1A as a novel transducer receptor for the inhibitory effect exerted by anti-GD1a Abs on nerve repair, representing a significant step forward toward understanding the factors contributing to poor clinical recovery in GBS associated with anti-Gg Abs.
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Axones , Gangliósidos , Inmunoglobulina G , Regeneración Nerviosa , Receptores Tipo I de Factores de Necrosis Tumoral , Proteína de Unión al GTP rhoA , Animales , Gangliósidos/metabolismo , Gangliósidos/inmunología , Axones/metabolismo , Axones/inmunología , Ratas , Ratones , Proteína de Unión al GTP rhoA/metabolismo , Proteína de Unión al GTP rhoA/inmunología , Receptores Tipo I de Factores de Necrosis Tumoral/metabolismo , Receptores Tipo I de Factores de Necrosis Tumoral/inmunología , Inmunoglobulina G/inmunología , Inmunoglobulina G/metabolismo , Inmunoglobulina G/farmacología , Síndrome de Guillain-Barré/inmunología , Síndrome de Guillain-Barré/metabolismo , Síndrome de Guillain-Barré/patología , Ratones Noqueados , Transducción de Señal , Células CultivadasRESUMEN
BACKGROUND: Peripheral nerve injuries stimulate the regenerative capacity of injured neurons through a neuroimmune phenomenon termed the conditioning lesion (CL) response. This response depends on macrophage accumulation in affected dorsal root ganglia (DRGs) and peripheral nerves. The macrophage chemokine CCL2 is upregulated after injury and is allegedly required for stimulating macrophage recruitment and pro-regenerative signaling through its receptor, CCR2. In these tissues, CCL2 is putatively produced by neurons in the DRG and Schwann cells in the distal nerve. METHODS: Ccl2fl/fl mice were crossed with Advillin-Cre, P0-Cre, or both to create conditional Ccl2 knockouts (CKOs) in sensory neurons, Schwann cells, or both to hypothetically remove CCL2 and macrophages from DRGs, nerves or both. CCL2 was localized using Ccl2-RFPfl/fl mice. CCL2-CCR2 signaling was further examined using global Ccl2 KOs and Ccr2gfp knock-in/knock-outs. Unilateral sciatic nerve transection was used as the injury model, and at various timepoints, chemokine expression, macrophage accumulation and function, and in vivo regeneration were examined using qPCR, immunohistochemistry, and luxol fast blue staining. RESULTS: Surprisingly, in all CKOs, DRG Ccl2 gene expression was decreased, while nerve Ccl2 was not. CCL2-RFP reporter mice revealed CCL2 expression in several cell types beyond the expected neurons and Schwann cells. Furthermore, macrophage accumulation, myelin clearance, and in vivo regeneration were unaffected in all CKOs, suggesting CCL2 may not be necessary for the CL response. Indeed, Ccl2 global knockout mice showed normal macrophage accumulation, myelin clearance, and in vivo regeneration, indicating these responses do not require CCL2. CCR2 ligands, Ccl7 and Ccl12, were upregulated after nerve injury and perhaps could compensate for the absence of Ccl2. Finally, Ccr2gfp knock-in/knock-out animals were used to differentiate resident and recruited macrophages in the injured tissues. Ccr2gfp/gfp KOs showed a 50% decrease in macrophages in the distal nerve compared to controls with a relative increase in resident macrophages. In the DRG there was a small but insignificant decrease in macrophages. CONCLUSIONS: CCL2 is not necessary for macrophage accumulation, myelin clearance, and axon regeneration in the peripheral nervous system. Without CCL2, other CCR2 chemokines, resident macrophage proliferation, and CCR2-independent monocyte recruitment can compensate and allow for normal macrophage accumulation.
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Quimiocina CCL2 , Macrófagos , Traumatismos de los Nervios Periféricos , Animales , Axones/inmunología , Axones/patología , Quimiocina CCL2/inmunología , Quimiocina CCL2/metabolismo , Quimiocinas/inmunología , Quimiocinas/metabolismo , Macrófagos/inmunología , Macrófagos/metabolismo , Ratones , Regeneración Nerviosa/fisiología , Traumatismos de los Nervios Periféricos/inmunología , Traumatismos de los Nervios Periféricos/metabolismo , Traumatismos de los Nervios Periféricos/patologíaRESUMEN
Leukocyte infiltration and blood-brain barrier breakdown contribute to secondary brain damage after traumatic brain injury (TBI). TBI induces neuroimmune responses triggering pathogenic complement activation through different pathways, including the lectin pathway. We investigated mechanisms underlying mannose-binding lectin (MBL)-mediated brain damage focusing on neutrophil infiltration and blood-brain barrier breakdown in a TBI mouse model. Wild type mice and MBL-/- null mice were subjected to controlled cortical impact. We studied neutrophil infiltration and regional localization by confocal microscopy 1, 4 and 15 days post-trauma, and investigated neutrophil extracellular trap (NET) formation. By immunofluorescence and/or Western blotting in various brain regions we studied the presence of fibrin(ogen), pentraxin-3, albumin and immunoglobulin G. Finally, we studied neurofilament proteins, synaptophysin, and αII-spectrin, and assessed white matter content in the injured tissue. TBI triggered an acute wave of neutrophil infiltration at day 1 followed by a more discrete persistence of neutrophils in the injured tissue at least until day 15. We detected the presence of NETs and pentraxin-3 in the injured tissue, as well as accumulation of fibrin(ogen), increased blood-brain barrier permeability, and neurofilament, synaptophysin and white matter loss, and calpain-mediated αII spectrin breakdown. MBL-/- mice showed reduced number of Ly6G+ neutrophils 4 days after TBI, lower accumulation of pentraxin-3 and fibrin(ogen) in the injured tissue, reduced global plasma protein extravasation, and better preservation of axonal and white matter integrity. These results show that MBL participates in secondary neutrophil accumulation and blood-brain barrier breakdown, and promotes axonal and white matter damage after TBI in mice.
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Axones/metabolismo , Barrera Hematoencefálica/metabolismo , Lesiones Traumáticas del Encéfalo/metabolismo , Encéfalo/metabolismo , Lectina de Unión a Manosa/deficiencia , Animales , Axones/inmunología , Axones/patología , Barrera Hematoencefálica/inmunología , Barrera Hematoencefálica/patología , Encéfalo/inmunología , Encéfalo/patología , Lesiones Traumáticas del Encéfalo/inmunología , Lesiones Traumáticas del Encéfalo/patología , Masculino , Lectina de Unión a Manosa/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones NoqueadosRESUMEN
Axon regenerative failure in the mature CNS contributes to functional deficits following many traumatic injuries, ischemic injuries, and neurodegenerative diseases. The complement cascade of the innate immune system responds to pathogen threat through inflammatory cell activation, pathogen opsonization, and pathogen lysis, and complement is also involved in CNS development, neuroplasticity, injury, and disease. Here, we investigated the involvement of the classical complement cascade and microglia/monocytes in CNS repair using the mouse optic nerve injury (ONI) model, in which axons arising from retinal ganglion cells (RGCs) are disrupted. We report that central complement C3 protein and mRNA, classical complement C1q protein and mRNA, and microglia/monocyte phagocytic complement receptor CR3 all increase in response to ONI, especially within the optic nerve itself. Importantly, genetic deletion of C1q, C3, or CR3 attenuates RGC axon regeneration induced by several distinct methods, with minimal effects on RGC survival. Local injections of C1q function-blocking antibody revealed that complement acts primarily within the optic nerve, not retina, to support regeneration. Moreover, C1q opsonizes and CR3+ microglia/monocytes phagocytose growth-inhibitory myelin debris after ONI, a likely mechanism through which complement and myeloid cells support axon regeneration. Collectively, these results indicate that local optic nerve complement-myeloid phagocytic signaling is required for CNS axon regrowth, emphasizing the axonal compartment and highlighting a beneficial neuroimmune role for complement and microglia/monocytes in CNS repair.SIGNIFICANCE STATEMENT Despite the importance of achieving axon regeneration after CNS injury and the inevitability of inflammation after such injury, the contributions of complement and microglia to CNS axon regeneration are largely unknown. Whereas inflammation is commonly thought to exacerbate the effects of CNS injury, we find that complement proteins C1q and C3 and microglia/monocyte phagocytic complement receptor CR3 are each required for retinal ganglion cell axon regeneration through the injured mouse optic nerve. Also, whereas studies of optic nerve regeneration generally focus on the retina, we show that the regeneration-relevant role of complement and microglia/monocytes likely involves myelin phagocytosis within the optic nerve. Thus, our results point to the importance of the innate immune response for CNS repair.
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Axones/metabolismo , Complemento C1q/metabolismo , Complemento C3/metabolismo , Células Mieloides/metabolismo , Traumatismos del Nervio Óptico/metabolismo , Células Ganglionares de la Retina/metabolismo , Animales , Axones/inmunología , Complemento C1q/inmunología , Complemento C3/inmunología , Femenino , Masculino , Ratones , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Noqueados , Células Mieloides/inmunología , Regeneración Nerviosa/fisiología , Traumatismos del Nervio Óptico/inmunología , Traumatismos del Nervio Óptico/patología , Células Ganglionares de la Retina/inmunologíaRESUMEN
Although aggravated multiple sclerosis (MS) disability has been reported in aged patients, the aging impact on immune cells remodeling within the CNS is not well understood. Here, we investigated the influence of aging on immune cells and the neuroinflammatory and neurodegenerative processes that occur in a well-established viral model of progressive MS. We found an anomalous presence of CD4+ T, CD8+ T, B cells, and cells of myeloid lineage in the CNS of old sham mice whereas a blunted cellular innate and adaptive immune response was observed in Theiler's murine encephalomyelitis virus (TMEV) infected old mice. Microglia and macrophages show opposite CNS viral responses regarding cell counts in the old mice. Furthermore, enhanced expression of Programmed Death-ligand 1 (PD-L1) was found in microglia isolated from old TMEV-infected mice and not in isolated CNS macrophages. Immunocytochemical staining of microglial cells confirms the above differences between young and old mice. Age-related axonal loss integrity in the mouse spinal cord was found in TMEV mice, but a less marked neurodegenerative process was present in old sham mice compared with young sham mice. TMEV and sham old mice also display alterations in innate and adaptive immunity in the spleen compared to the young mice. Our study supports the need of new or adapted pharmacological strategies for MS elderly patients.
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Axones/inmunología , Senescencia Celular/inmunología , Modelos Animales de Enfermedad , Esclerosis Múltiple/inmunología , Enfermedades Neuroinflamatorias/inmunología , Animales , Femenino , Ratones , Esclerosis Múltiple/patología , Enfermedades Neuroinflamatorias/patología , Theilovirus/inmunologíaRESUMEN
Neuroinflammation has been put forward as a mechanism triggering axonal regrowth in the mammalian central nervous system (CNS), yet little is known about the underlying cellular and molecular players connecting these two processes. In this study, we provide evidence that MMP2 is an essential factor linking inflammation to axonal regeneration by using an in vivo mouse model of inflammation-induced axonal regeneration in the optic nerve. We show that infiltrating myeloid cells abundantly express MMP2 and that MMP2 deficiency results in reduced long-distance axonal regeneration. However, this phenotype can be rescued by restoring MMP2 expression in myeloid cells via a heterologous bone marrow transplantation. Furthermore, while MMP2 deficiency does not affect the number of infiltrating myeloid cells, it does determine the coordinated expression of pro- and anti-inflammatory molecules. Altogether, in addition to its role in axonal regeneration via resolution of the glial scar, here, we reveal a new mechanism via which MMP2 facilitates axonal regeneration, namely orchestrating the expression of pro- and anti-inflammatory molecules by infiltrating innate immune cells.
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Axones/inmunología , Trasplante de Médula Ósea , Metaloproteinasa 2 de la Matriz/genética , Regeneración Nerviosa/inmunología , Traumatismos del Nervio Óptico/inmunología , Nervio Óptico/inmunología , Animales , Antígenos Ly/genética , Antígenos Ly/inmunología , Axones/ultraestructura , Receptor 1 de Quimiocinas CX3C/genética , Receptor 1 de Quimiocinas CX3C/inmunología , Movimiento Celular , Proteína GAP-43/genética , Proteína GAP-43/inmunología , Regulación de la Expresión Génica , Inmunidad Innata , Inflamación , Antígenos Comunes de Leucocito/genética , Antígenos Comunes de Leucocito/inmunología , Metaloproteinasa 2 de la Matriz/deficiencia , Metaloproteinasa 2 de la Matriz/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Células Mieloides/citología , Células Mieloides/inmunología , Regeneración Nerviosa/genética , Nervio Óptico/metabolismo , Traumatismos del Nervio Óptico/genética , Traumatismos del Nervio Óptico/patología , Retina/inmunología , Retina/lesiones , Retina/metabolismo , Trasplante Heterólogo , Irradiación Corporal TotalRESUMEN
Alphaherpesviruses (α-HV) are a large family of double-stranded DNA viruses which cause many human and animal diseases. There are three human α-HVs: Herpes Simplex Viruses (HSV-1 and HSV-2) and Varicella Zoster Virus (VZV). All α-HV have evolved multiple strategies to suppress or exploit host cell innate immune signaling pathways to aid in their infections. All α-HVs initially infect epithelial cells (primary site of infection), and later spread to infect innervating sensory neurons. As with all herpesviruses, α-HVs have both a lytic (productive) and latent (dormant) stage of infection. During the lytic stage, the virus rapidly replicates in epithelial cells before it is cleared by the immune system. In contrast, latent infection in host neurons is a life-long infection. Upon infection of mucosal epithelial cells, herpesviruses immediately employ a variety of cellular mechanisms to evade host detection during active replication. Next, infectious viral progeny bud from infected cells and fuse to neuronal axonal terminals. Here, the nucleocapsid is transported via sensory neuron axons to the ganglion cell body, where latency is established until viral reactivation. This review will primarily focus on how HSV-1 induces various innate immune responses, including host cell recognition of viral constituents by pattern-recognition receptors (PRRs), induction of IFN-mediated immune responses involving toll-like receptor (TLR) signaling pathways, and cyclic GMP-AMP synthase stimulator of interferon genes (cGAS-STING). This review focuses on these pathways along with other mechanisms including autophagy and the complement system. We will summarize and discuss recent evidence which has revealed how HSV-1 is able to manipulate and evade host antiviral innate immune responses both in neuronal (sensory neurons of the trigeminal ganglia) and non-neuronal (epithelial) cells. Understanding the innate immune response mechanisms triggered by HSV-1 infection, and the mechanisms of innate immune evasion, will impact the development of future therapeutic treatments.
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Axones/inmunología , Herpes Simple/inmunología , Herpesvirus Humano 1/inmunología , Evasión Inmune , Inmunidad Innata , Células Receptoras Sensoriales/inmunología , Animales , Herpes Simple/terapia , Humanos , Transducción de Señal/inmunologíaRESUMEN
Partial phagocytosis-called trogocytosis-of axons by microglia has been documented in ex vivo preparations but has not been directly observed in vivo. The mechanisms that modulate microglial trogocytosis of axons and its function in neural circuit development remain poorly understood. Here, we directly observe axon trogocytosis by microglia in vivo in the developing Xenopus laevis retinotectal circuit. We show that microglia regulate pruning of retinal ganglion cell axons and are important for proper behavioral response to dark and bright looming stimuli. Using bioinformatics, we identify amphibian regulator of complement activation 3, a homolog of human CD46, as a neuronally expressed synapse-associated complement inhibitory molecule that inhibits trogocytosis and axonal pruning. Using a membrane-bound complement C3 fusion protein, we demonstrate that enhancing complement activity enhances axonal pruning. Our results support the model that microglia remodel axons via trogocytosis and that neurons can control this process through expression of complement inhibitory proteins.
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Axones/metabolismo , Activación de Complemento , Microglía/metabolismo , Plasticidad Neuronal , Fagocitosis , Animales , Axones/inmunología , Comunicación Celular , Humanos , Proteína Cofactora de Membrana/metabolismo , Microglía/inmunología , Células Ganglionares de la Retina/metabolismo , Sinapsis/metabolismo , Proteínas de Xenopus/metabolismo , Xenopus laevisRESUMEN
The inflammatory environment of demyelinated lesions in multiple sclerosis (MS) patients contributes to remyelination failure. Inflammation activates a cytoprotective pathway, the integrated stress response (ISR), but it remains unclear whether enhancing the ISR can improve remyelination in an inflammatory environment. To examine this possibility, the remyelination stage of experimental autoimmune encephalomyelitis (EAE), as well as a mouse model that incorporates cuprizone-induced demyelination along with CNS delivery of the proinflammatory cytokine IFN-γ were used here. We demonstrate that either genetic or pharmacological ISR enhancement significantly increased the number of remyelinating oligodendrocytes and remyelinated axons in the inflammatory lesions. Moreover, the combined treatment of the ISR modulator Sephin1 with the oligodendrocyte differentiation enhancing reagent bazedoxifene increased myelin thickness of remyelinated axons to pre-lesion levels. Taken together, our findings indicate that prolonging the ISR protects remyelinating oligodendrocytes and promotes remyelination in the presence of inflammation, suggesting that ISR enhancement may provide reparative benefit to MS patients.
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Sistema Nervioso Central/inmunología , Cuprizona/efectos adversos , Enfermedades Desmielinizantes/inmunología , Encefalomielitis Autoinmune Experimental/inmunología , Remielinización/fisiología , Animales , Axones/inmunología , Enfermedades Desmielinizantes/inducido químicamente , Modelos Animales de Enfermedad , Femenino , Inflamación/genética , Inflamación/inmunología , Interferón gamma/genética , Interferón gamma/metabolismo , Masculino , Ratones , Oligodendroglía/inmunología , Remielinización/genéticaRESUMEN
Unraveling the pathology of stroke is a prerequisite for designing therapeutic strategies. It was reported that myelin injury exceeded axonal loss in the peri-infarct region of rodent white matter stroke. An in-depth investigation of the post-stroke white matter damage in higher-order species might innovate stroke intervention. In this study, adult male cynomolgus monkeys received surgical middle cerebral artery occlusion (MCAO), and serial magnetic resonance scans to non-invasively assess brain damage. Spontaneous movements were recorded to evaluate post-stroke behavior. The axon and myelin loss, as well as immune cell infiltration were examined using immunohistochemistry. Magnetic resonance imaging revealed cerebral infarcts and white matter injury after MCAO in monkeys, which were confirmed by neurological deficits. Immunostaining of white matter fibers showed substantial demyelination whilst retention of axons in the infarcts 8 days post MCAO, while a progressive loss of myelin and axons was observed after one month. Gliosis, microglia activation, and leukocyte infiltration were identified in the lesions. These results demonstrate that demyelination predates axonal injury in non-human primate ischemic stroke, which provides a time window for stroke intervention focusing on prevention of progressive axonal loss through myelin regeneration.
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Axones/patología , Isquemia Encefálica/patología , Enfermedades Desmielinizantes/patología , Accidente Cerebrovascular Isquémico/patología , Sustancia Blanca/patología , Animales , Axones/química , Axones/inmunología , Isquemia Encefálica/inmunología , Enfermedades Desmielinizantes/inmunología , Gliosis/inmunología , Gliosis/patología , Accidente Cerebrovascular Isquémico/inmunología , Macaca fascicularis , Masculino , Sustancia Blanca/química , Sustancia Blanca/inmunologíaRESUMEN
OBJECTIVES: To describe CSF-defined neuronal intermediate filament (NIF) autoimmunity. METHODS: NIF-IgG CSF-positive patients (41, 0.03% of 118599 tested, 1996-2019) were included (serum was neither sensitive nor specific). Criteria-based patient NIF-IgG staining of brain and myenteric NIFs was detected by indirect immunofluorescence assay (IFA); NIF-specificity was confirmed by cell-based assays (CBAs, alpha internexin, neurofilament light [NF-L]), heavy-[NF-H] chain). RESULTS: Sixty-one percent of 41 patients were men, median age, 61 years (range, 21-88). Syndromes were encephalopathy predominant (23), cerebellar ataxia predominant (11), or myeloradiculoneuropathies (7). MRI abnormalities (T2 hyperintensities of brain, spinal cord white matter tracts. and peripheral nerve axons) and neurophysiologic testing (EEG, EMG, evoked potentials) co-localized with clinical neurological phenotypes (multifocal in 29%). Thirty patients (73%) had ≥ 1 immunological perturbation: cancer (paraneoplastic), 22; systemic infection (parainfectious [including ehrlichosis, 3] or HIV), 7; checkpoint-inhibitor cancer immunotherapy, 4; other, 5. Cancers were as follows: neuroendocrine-lineage carcinomas, 12 (small cell, 6; Merkel cell, 5; pancreatic, 1 [11/12 had NF-L-IgG detected, versus 8/29 others, P = 0.0005]) and other, 11. Onset was predominantly subacute (92%) and accompanied by inflammatory CSF (75%), and immunotherapy response (77%). In contrast, CSF controls (15684 total) demonstrated NIF-IgG negativity (100% of test validation controls), and low frequencies of autoimmune diagnoses (20% of consecutively referred clinical specimens) and neuroendocrine-lineage carcinoma diagnosis (3.1% vs. 30% of NIF cases), P < 0.0001. Median NF-L protein concentration was higher in 8 NF-L-IgG-positive patients (median, 6718 ng/L) than 16 controls. INTERPRETATION: Neurological autoimmunity, defined by CSF-detected NIF-IgGs, represents a continuum of treatable axonopathies, sometimes paraneoplastic or parainfectious.
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Axones/inmunología , Axones/patología , Biomarcadores/líquido cefalorraquídeo , Enfermedades del Sistema Nervioso , Proteínas de Neurofilamentos/inmunología , Adulto , Anciano , Anciano de 80 o más Años , Animales , Autoanticuerpos/sangre , Autoanticuerpos/líquido cefalorraquídeo , Autoantígenos/inmunología , Autoinmunidad/inmunología , Biomarcadores/sangre , Sistema Nervioso Central/diagnóstico por imagen , Estudios de Cohortes , Progresión de la Enfermedad , Ehrlichiosis/inmunología , Femenino , Humanos , Inmunoglobulina G/sangre , Inmunoglobulina G/líquido cefalorraquídeo , Filamentos Intermedios/inmunología , Masculino , Ratones , Persona de Mediana Edad , Enfermedades del Sistema Nervioso/líquido cefalorraquídeo , Enfermedades del Sistema Nervioso/etiología , Enfermedades del Sistema Nervioso/inmunología , Enfermedades del Sistema Nervioso/fisiopatología , Adulto JovenRESUMEN
CNS autoantigens conjugated to oxidized mannan (OM) induce antigen-specific T cell tolerance and protect mice against autoimmune encephalomyelitis (EAE). To investigate whether OM-peptides treat EAE initiated by human MHC class II molecules, we administered OM-conjugated murine myelin oligodendrocyte glycoprotein peptide 35-55 (OM-MOG) to humanized HLA-DR2b transgenic mice (DR2b.Ab°), which are susceptible to MOG-EAE. OM-MOG protected DR2b.Ab° mice against MOG-EAE by both prophylactic and therapeutic applications. OM-MOG reversed clinical symptoms, reduced spinal cord inflammation, demyelination, and neuronal damage in DR2b.Ab° mice, while preserving axons within lesions and inducing the expression of genes associated with myelin (Mbp) and neuron (Snap25) recovery in B6 mice. OM-MOG-induced tolerance was peptide-specific, not affecting PLP178-191-induced EAE or polyclonal T cell proliferation responses. OM-MOG-induced immune tolerance involved rapid induction of PD-L1- and IL-10-producing myeloid cells, increased expression of Chi3l3 (Ym1) in secondary lymphoid organs and characteristics of anergy in MOG-specific CD4+ T cells. The results show that OM-MOG treats MOG-EAE in a peptide-specific manner, across mouse/human MHC class II barriers, through induction of a peripheral type 2 myeloid cell response and T cell anergy, and suggest that OM-peptides might be useful for suppressing antigen-specific CD4+ T cell responses in the context of human autoimmune CNS demyelination.
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Axones/efectos de los fármacos , Encefalomielitis Autoinmune Experimental/tratamiento farmacológico , Inmunosupresores/farmacología , Células Mieloides/efectos de los fármacos , Médula Espinal/efectos de los fármacos , Linfocitos T/efectos de los fármacos , Adulto , Animales , Axones/inmunología , Axones/metabolismo , Axones/patología , Estudios de Casos y Controles , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Encefalomielitis Autoinmune Experimental/genética , Encefalomielitis Autoinmune Experimental/inmunología , Encefalomielitis Autoinmune Experimental/metabolismo , Femenino , Regulación de la Expresión Génica , Grecia , Antígenos HLA-DR/genética , Antígenos HLA-DR/metabolismo , Humanos , Interleucina-2/metabolismo , Subunidad alfa del Receptor de Interleucina-2/metabolismo , Activación de Linfocitos/efectos de los fármacos , Masculino , Ratones Endogámicos C57BL , Ratones Transgénicos , Persona de Mediana Edad , Proteína Básica de Mielina/genética , Proteína Básica de Mielina/metabolismo , Células Mieloides/inmunología , Células Mieloides/metabolismo , Médula Espinal/inmunología , Médula Espinal/metabolismo , Médula Espinal/patología , Proteína 25 Asociada a Sinaptosomas/genética , Proteína 25 Asociada a Sinaptosomas/metabolismo , Linfocitos T/inmunología , Linfocitos T/metabolismo , Adulto JovenRESUMEN
Microglia and peripheral macrophages have both been implicated in amyotrophic lateral sclerosis (ALS), although their respective roles have yet to be determined. We now show that macrophages along peripheral motor neuron axons in mouse models and patients with ALS react to neurodegeneration. In ALS mice, peripheral myeloid cell infiltration into the spinal cord was limited and depended on disease duration. Targeted gene modulation of the reactive oxygen species pathway in peripheral myeloid cells of ALS mice, using cell replacement, reduced both peripheral macrophage and microglial activation, delayed symptoms and increased survival. Transcriptomics revealed that sciatic nerve macrophages and microglia reacted differently to neurodegeneration, with abrupt temporal changes in macrophages and progressive, unidirectional activation in microglia. Modifying peripheral macrophages suppressed proinflammatory microglial responses, with a shift toward neuronal support. Thus, modifying macrophages at the periphery has the capacity to influence disease progression and may be of therapeutic value for ALS.
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Esclerosis Amiotrófica Lateral/inmunología , Axones/inmunología , Macrófagos/inmunología , Microglía/inmunología , Neuronas Motoras/inmunología , Nervio Ciático/inmunología , Adulto , Anciano , Esclerosis Amiotrófica Lateral/metabolismo , Animales , Femenino , Humanos , Macrófagos/metabolismo , Masculino , Ratones Endogámicos C57BL , Ratones Transgénicos , Microglía/metabolismo , Persona de Mediana Edad , Neuronas Motoras/metabolismo , Nervio Ciático/metabolismo , Médula Espinal/inmunología , Médula Espinal/metabolismoRESUMEN
B cell-depleting therapies have recently proven to be clinically highly successful in the treatment of multiple sclerosis (MS). This study aimed to determine the effects of the novel type II anti-human CD20 (huCD20) monoclonal antibody (mAb) obinutuzumab (OBZ) on spinal cord degeneration in a B cell-dependent mouse model of MS. Double transgenic huCD20xHIGR3 (CD20dbtg) mice, which express human CD20, were immunised with the myelin fusion protein MP4 to induce experimental autoimmune encephalomyelitis (EAE). Both light and electron microscopy were used to assess myelination and axonal pathology in mice treated with OBZ during chronic EAE. Furthermore, the effects of the already established murine anti-CD20 antibody 18B12 were assessed in C57BL/6 wild-type (wt) mice. In both models (18B12/wt and OBZ/CD20dbtg) anti-CD20 treatment significantly diminished the extent of spinal cord pathology. While 18B12 treatment mainly reduced the extent of axonal pathology, a significant decrease in demyelination and increase in remyelination were additionally observed in OBZ-treated mice. Hence, the data suggest that OBZ could have neuroprotective effects on the CNS, setting the drug apart from the currently available type I anti-CD20 antibodies.
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Anticuerpos Monoclonales Humanizados/administración & dosificación , Antígenos CD20/inmunología , Antineoplásicos Inmunológicos/administración & dosificación , Linfocitos B/inmunología , Encefalomielitis Autoinmune Experimental/tratamiento farmacológico , Esclerosis Múltiple Crónica Progresiva/tratamiento farmacológico , Médula Espinal/efectos de los fármacos , Animales , Anticuerpos Monoclonales/administración & dosificación , Antígenos CD20/metabolismo , Axones/efectos de los fármacos , Axones/inmunología , Axones/patología , Linfocitos B/patología , Enfermedad Crónica/tratamiento farmacológico , Modelos Animales de Enfermedad , Encefalomielitis Autoinmune Experimental/inmunología , Encefalomielitis Autoinmune Experimental/patología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Microscopía Electrónica , Esclerosis Múltiple/tratamiento farmacológico , Esclerosis Múltiple/inmunología , Esclerosis Múltiple/patología , Esclerosis Múltiple Crónica Progresiva/inmunología , Esclerosis Múltiple Crónica Progresiva/patología , Proteína Básica de Mielina/inmunología , Proteína Proteolipídica de la Mielina/inmunología , Proteínas de Neurofilamentos/sangre , Proteínas Recombinantes de Fusión/inmunología , Médula Espinal/inmunología , Médula Espinal/patología , Médula Espinal/ultraestructuraRESUMEN
Numerous experimental and postmortem studies have increasingly reported dystrophic axons and dendrites, and alterations of dendritic spine morphology and density in the hippocampus as prominent changes in the early stages of Alzheimer's disease (AD). Furthermore, these alterations tend to correlate well with the progressive cognitive decline observed in AD. For these reasons, and because these neurite structures have a capacity to re-grow, re-establish lost connections, and are critical for learning and memory, there is compelling evidence to suggest that therapeutic interventions aimed at preventing their degradation or promoting their regrowth may hold tremendous promise in preventing the progression of AD. In this regard, collapsin response mediator proteins (CRMPs), a family of phosphoproteins playing a major role in axon guidance and dendritic growth, are especially interesting. The roles these proteins play in neurons and immune cells are reviewed here.
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Enfermedad de Alzheimer/inmunología , Enfermedad de Alzheimer/metabolismo , Sistemas de Liberación de Medicamentos/métodos , Proteínas del Tejido Nervioso/inmunología , Proteínas del Tejido Nervioso/metabolismo , Enfermedad de Alzheimer/tratamiento farmacológico , Animales , Axones/efectos de los fármacos , Axones/inmunología , Axones/metabolismo , Dendritas/efectos de los fármacos , Dendritas/inmunología , Dendritas/metabolismo , Sistemas de Liberación de Medicamentos/tendencias , Hipocampo/efectos de los fármacos , Hipocampo/inmunología , Hipocampo/metabolismo , Humanos , Factores Inmunológicos/administración & dosificación , Factores Inmunológicos/inmunología , Factores Inmunológicos/metabolismo , Neuritas/efectos de los fármacos , Neuritas/inmunología , Neuritas/metabolismo , Neuronas/efectos de los fármacos , Neuronas/inmunología , Neuronas/metabolismo , Isoformas de Proteínas/inmunología , Isoformas de Proteínas/metabolismoRESUMEN
Cytokine storm in COVID-19 is characterized by an excessive inflammatory response to SARS-CoV-2 that is caused by a dysregulated immune system of the host. We are proposing a new hypothesis that SARS-CoV-2 mediated inflammation of nucleus tractus solitarius (NTS) may be responsible for the cytokine storm in COVID 19. The inflamed NTS may result in a dysregulated cholinergic anti-inflammatory pathway and hypothalamic-pituitary-adrenal axis.
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Betacoronavirus/metabolismo , Infecciones por Coronavirus/metabolismo , Citocinas/metabolismo , Neumonía Viral/metabolismo , Núcleo Solitario/metabolismo , Axones/inmunología , Axones/metabolismo , Axones/virología , Betacoronavirus/inmunología , COVID-19 , Infecciones por Coronavirus/inmunología , Nervios Craneales/inmunología , Nervios Craneales/metabolismo , Nervios Craneales/virología , Citocinas/inmunología , Humanos , Sistema Hipotálamo-Hipofisario/inmunología , Sistema Hipotálamo-Hipofisario/metabolismo , Sistema Hipotálamo-Hipofisario/virología , Mediadores de Inflamación/inmunología , Mediadores de Inflamación/metabolismo , Pandemias , Sistema Hipófiso-Suprarrenal/inmunología , Sistema Hipófiso-Suprarrenal/metabolismo , Sistema Hipófiso-Suprarrenal/virología , Neumonía Viral/inmunología , SARS-CoV-2 , Núcleo Solitario/inmunología , Núcleo Solitario/virologíaRESUMEN
Mouse hepatitis virus (MHV) is a murine betacoronavirus (m-CoV) that causes a wide range of diseases in mice and rats, including hepatitis, enteritis, respiratory diseases, and encephalomyelitis in the central nervous system (CNS). MHV infection in mice provides an efficient cause-effect experimental model to understand the mechanisms of direct virus-induced neural-cell damage leading to demyelination and axonal loss, which are pathological features of multiple sclerosis (MS), the most common disabling neurological disease in young adults. Infiltration of T lymphocytes, activation of microglia, and their interplay are the primary pathophysiological events leading to disruption of the myelin sheath in MS. However, there is emerging evidence supporting gray matter involvement and degeneration in MS. The investigation of T cell function in the pathogenesis of deep gray matter damage is necessary. Here, we employed RSA59 (an isogenic recombinant strain of MHV-A59)-induced experimental neuroinflammation model to compare the disease in CD4-/- mice with that in CD4+/+ mice at days 5, 10, 15, and 30 postinfection (p.i.). Viral titer estimation, nucleocapsid gene amplification, and viral antinucleocapsid staining confirmed enhanced replication of the virions in the absence of functional CD4+ T cells in the brain. Histopathological analyses showed elevated susceptibility of CD4-/- mice to axonal degeneration in the CNS, with augmented progression of acute poliomyelitis and dorsal root ganglionic inflammation rarely observed in CD4+/+ mice. Depletion of CD4+ T cells showed unique pathological bulbar vacuolation in the brain parenchyma of infected mice with persistent CD11b+ microglia/macrophages in the inflamed regions on day 30 p.i. In summary, the current study suggests that CD4+ T cells are critical for controlling acute-stage poliomyelitis (gray matter inflammation), chronic axonal degeneration, and inflammatory demyelination due to loss of protective antiviral host immunity.IMPORTANCE The current trend in CNS disease biology is to attempt to understand the neural-cell-immune interaction to investigate the underlying mechanism of neuroinflammation, rather than focusing on peripheral immune activation. Most studies in MS are targeted toward understanding the involvement of CNS white matter. However, the importance of gray matter damage has become critical in understanding the long-term progressive neurological disorder. Our study highlights the importance of CD4+ T cells in safeguarding neurons against axonal blebbing and poliomyelitis from murine betacoronavirus-induced neuroinflammation. Current knowledge of the mechanisms that lead to gray matter damage in MS is limited, because the most widely used animal model, experimental autoimmune encephalomyelitis (EAE), does not present this aspect of the disease. Our results, therefore, add to the existing limited knowledge in the field. We also show that the microglia, though important for the initiation of neuroinflammation, cannot establish a protective host immune response without the help of CD4+ T cells.
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Axones/inmunología , Axones/metabolismo , Antígenos CD4/deficiencia , Infecciones por Coronavirus/inmunología , Infecciones por Coronavirus/virología , Virus de la Hepatitis Murina/fisiología , Poliomielitis/etiología , Animales , Axones/patología , Encéfalo/inmunología , Encéfalo/metabolismo , Encéfalo/patología , Recuento de Linfocito CD4 , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Infecciones por Coronavirus/patología , Citocinas/metabolismo , Modelos Animales de Enfermedad , Susceptibilidad a Enfermedades/inmunología , Ganglios Espinales/inmunología , Ganglios Espinales/metabolismo , Ganglios Espinales/patología , Inmunohistoquímica , Mediadores de Inflamación/metabolismo , RatonesRESUMEN
BACKGROUND AND PURPOSE: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a heterogeneous autoimmune disorder critically lacking diagnostic biomarkers. Autoantibodies to nodal and paranodal components have recently been described in a small subset of patients. Here, the diagnostic value of immune reactivity toward the myelin compartment was investigated. METHODS: Ninety-four French CIDP patients were retrospectively studied. The reactivity toward the peripheral nerve was investigated. Sural nerve biopsies were examined by electron microscopy and immunofluorescence. RESULTS: Twenty-one patients (22%) and three patients (3%) presented with a strong immunoglobulin G or immunoglobulin M reactivity respectively against the myelin compartment. The clinical, electrophysiological and morphological features were examined in nine of these patients for whom sural nerve biopsies were available. Seven patients were electrodiagnosed with definite CIDP, one with possible CIDP and one was unclassifiable but sural nerve biopsy argued for CIDP diagnosis. Electron microscopy of sural nerve biopsies demonstrated the presence of macrophage-mediated demyelination restricted to the internode in all nine patients. Immunolabelling for voltage-gated sodium channels, myelin and axonal markers confirmed the presence of segmental demyelination and of remyelination. The nodal and paranodal regions, however, were unaffected in these patients. Nerve conduction studies corroborated the multifocal and segmental profile, and seven patients showed increased duration of proximal (1.5-5.1 times) and/or distal (1.2-3.4 times) compound muscle action potential in at least two nerves. CONCLUSION: Antibody- and macrophage-mediated demyelination appears responsible for conduction alterations in CIDP patients and nerve immunostaining assays may serve as a supportive diagnostic biomarker.
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Autoanticuerpos , Axones/patología , Macrófagos/patología , Vaina de Mielina/patología , Polirradiculoneuropatía Crónica Inflamatoria Desmielinizante/diagnóstico , Adulto , Anciano , Axones/inmunología , Electrodiagnóstico , Femenino , Humanos , Inmunoglobulina G/inmunología , Macrófagos/inmunología , Masculino , Persona de Mediana Edad , Vaina de Mielina/inmunología , Conducción Nerviosa , Nervios Periféricos/inmunología , Nervios Periféricos/patología , Polirradiculoneuropatía Crónica Inflamatoria Desmielinizante/inmunología , Polirradiculoneuropatía Crónica Inflamatoria Desmielinizante/patología , Estudios RetrospectivosRESUMEN
Guillain-Barré syndrome (GBS) is an acute immune-mediated polyradiculoneuropathy, and pathophysiologically classified into acute inflammatory demyelinating polyneuropathy (AIDP), acute motor axonal neuropathy (AMAN), and acute motor and sensory axonal neuropathy (AMSAN). The main pathophysiological mechanism is complement-mediated nerve injury caused by antibody-antigen interaction in the peripheral nerves. Antiglycolipid antibodies are most pathogenic factors in the development of GBS, but not found in 40% of patients with GBS. One of the principal target regions in GBS is the node of Ranvier where functional molecules including glycolipids are assembled. Nodal dysfunction induced by the immune response in nodal axolemma, termed "nodopathy," can electrophysiologically show reversible conduction failure, axonal degeneration, or segmental demyelination. To detect new target molecules in antiglycolipid antibody-negative GBS and to elucidate the pathophysiology in the subacute and the subsequent phases of the disorder are the next problems.