RESUMO
Multidimensional single-cell analyses of T cells have fueled the debate about whether there is extensive plasticity or 'mixed' priming of helper T cell subsets in vivo. Here, we developed an experimental framework to probe the idea that the site of priming in the systemic immune compartment is a determinant of helper T cell-induced immunopathology in remote organs. By site-specific in vivo labeling of antigen-specific T cells in inguinal (i) or gut draining mesenteric (m) lymph nodes, we show that i-T cells and m-T cells isolated from the inflamed central nervous system (CNS) in a model of multiple sclerosis (MS) are distinct. i-T cells were Cxcr6+, and m-T cells expressed P2rx7. Notably, m-T cells infiltrated white matter, while i-T cells were also recruited to gray matter. Therefore, we propose that the definition of helper T cell subsets by their site of priming may guide an advanced understanding of helper T cell biology in health and disease.
Assuntos
Autoimunidade , Encéfalo/imunologia , Linhagem da Célula , Encefalomielite Autoimune Experimental/imunologia , Intestinos/imunologia , Pele/imunologia , Linfócitos T Auxiliares-Indutores/imunologia , Transferência Adotiva , Animais , Autoimunidade/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Sinalização do Cálcio , Líquido Cefalorraquidiano/imunologia , Líquido Cefalorraquidiano/metabolismo , Encefalomielite Autoimune Experimental/tratamento farmacológico , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/metabolismo , Cloridrato de Fingolimode/farmacologia , Perfilação da Expressão Gênica , Genes Codificadores dos Receptores de Linfócitos T , Células HEK293 , Humanos , Imunossupressores/farmacologia , Intestinos/efeitos dos fármacos , Microscopia Intravital , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia de Fluorescência , Esclerose Múltipla Recidivante-Remitente/genética , Esclerose Múltipla Recidivante-Remitente/imunologia , Esclerose Múltipla Recidivante-Remitente/metabolismo , Fenótipo , Estudos Prospectivos , RNA-Seq , Receptores CXCR6/genética , Receptores CXCR6/metabolismo , Receptores Purinérgicos P2X7/genética , Receptores Purinérgicos P2X7/metabolismo , Análise de Célula Única , Pele/efeitos dos fármacos , Pele/metabolismo , Linfócitos T Auxiliares-Indutores/efeitos dos fármacos , Linfócitos T Auxiliares-Indutores/metabolismo , Linfócitos T Auxiliares-Indutores/transplante , TranscriptomaRESUMO
Microglia and central nervous system (CNS)-associated macrophages (CAMs), such as perivascular and meningeal macrophages, are implicated in virtually all diseases of the CNS. However, little is known about their cell-type-specific roles in the absence of suitable tools that would allow for functional discrimination between the ontogenetically closely related microglia and CAMs. To develop a new microglia gene targeting model, we first applied massively parallel single-cell analyses to compare microglia and CAM signatures during homeostasis and disease and identified hexosaminidase subunit beta (Hexb) as a stably expressed microglia core gene, whereas other microglia core genes were substantially downregulated during pathologies. Next, we generated HexbtdTomato mice to stably monitor microglia behavior in vivo. Finally, the Hexb locus was employed for tamoxifen-inducible Cre-mediated gene manipulation in microglia and for fate mapping of microglia but not CAMs. In sum, we provide valuable new genetic tools to specifically study microglia functions in the CNS.
Assuntos
Encéfalo/patologia , Encefalomielite Autoimune Experimental/patologia , Traumatismos do Nervo Facial/patologia , Microglia/metabolismo , Cadeia beta da beta-Hexosaminidase/metabolismo , Animais , Encéfalo/citologia , Encéfalo/imunologia , Sistemas CRISPR-Cas/genética , Encefalomielite Autoimune Experimental/imunologia , Traumatismos do Nervo Facial/imunologia , Técnicas de Introdução de Genes , Genes Reporter/genética , Loci Gênicos/genética , Humanos , Microscopia Intravital , Substâncias Luminescentes/química , Proteínas Luminescentes/química , Proteínas Luminescentes/genética , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos , Microglia/imunologia , Células NIH 3T3 , RNA-Seq , Análise de Célula Única , Transfecção , Cadeia beta da beta-Hexosaminidase/genética , Proteína Vermelha FluorescenteRESUMO
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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Regulatory myeloid immune cells, such as myeloid-derived suppressor cells (MDSCs), populate inflamed or cancerous tissue and block immune cell effector functions. The lack of mechanistic insight into MDSC suppressive activity and a marker for their identification has hampered attempts to overcome T cell inhibition and unleash anti-cancer immunity. Here, we report that human MDSCs were characterized by strongly reduced metabolism and conferred this compromised metabolic state to CD8+ T cells, thereby paralyzing their effector functions. We identified accumulation of the dicarbonyl radical methylglyoxal, generated by semicarbazide-sensitive amine oxidase, to cause the metabolic phenotype of MDSCs and MDSC-mediated paralysis of CD8+ T cells. In a murine cancer model, neutralization of dicarbonyl activity overcame MDSC-mediated T cell suppression and, together with checkpoint inhibition, improved the efficacy of cancer immune therapy. Our results identify the dicarbonyl methylglyoxal as a marker metabolite for MDSCs that mediates T cell paralysis and can serve as a target to improve cancer immune therapy.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Imunoterapia/métodos , Melanoma/imunologia , Células Supressoras Mieloides/imunologia , Aldeído Pirúvico/metabolismo , Amina Oxidase (contendo Cobre)/metabolismo , Animais , Linfócitos T CD8-Positivos/transplante , Comunicação Celular , Proliferação de Células , Humanos , Tolerância Imunológica , Ativação Linfocitária , Melanoma Experimental , Camundongos , Camundongos Transgênicos , Neoplasias Experimentais , Receptor de Morte Celular Programada 1/metabolismoRESUMO
The cellular sources of interleukin 6 (IL-6) that are relevant for differentiation of the TH17 subset of helper T cells remain unclear. Here we used a novel strategy for the conditional deletion of distinct IL-6-producing cell types to show that dendritic cells (DCs) positive for the signaling regulator Sirpα were essential for the generation of pathogenic TH17 cells. Using their IL-6 receptor α-chain (IL-6Rα), Sirpα+ DCs trans-presented IL-6 to T cells during the process of cognate interaction. While ambient IL-6 was sufficient to suppress the induction of expression of the transcription factor Foxp3 in T cells, trans-presentation of IL-6 by DC-bound IL-6Rα (called 'IL-6 cluster signaling' here) was needed to prevent premature induction of interferon-γ (IFN-γ) expression in T cells and to generate pathogenic TH17 cells in vivo. Our findings should guide therapeutic approaches for the treatment of TH17-cell-mediated autoimmune diseases.
Assuntos
Sistema Nervoso Central/imunologia , Células Dendríticas/imunologia , Encefalomielite Autoimune Experimental/imunologia , Subunidade alfa de Receptor de Interleucina-6/genética , Interleucina-6/metabolismo , Células Th17/imunologia , Animais , Autoimunidade , Diferenciação Celular , Células Cultivadas , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Humanos , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Glicoproteína Mielina-Oligodendrócito/imunologia , Fragmentos de Peptídeos/imunologia , Receptores Imunológicos/genética , Receptores Imunológicos/metabolismoRESUMO
Selectively labeling cells with damaged membranes is needed not only for identifying dead cells in culture, but also for imaging membrane barrier dysfunction in pathologies in vivo. Most membrane permeability stains are permanently colored or fluorescent dyes that need washing to remove their non-uptaken extracellular background and reach good image contrast. Others are DNA-binding environment-dependent fluorophores, which lack design modularity, have potential toxicity, and can only detect permeabilization of cell volumes containing a nucleus (i.e., cannot delineate damaged volumes in vivo nor image non-nucleated cell types or compartments). Here, we develop modular fluorogenic probes that reveal the whole cytosolic volume of damaged cells, with near-zero background fluorescence so that no washing is needed. We identify a specific disulfonated fluorogenic probe type that only enters cells with damaged membranes, then is enzymatically activated and marks them. The esterase probe MDG1 is a reliable tool to reveal live cells that have been permeabilized by biological, biochemical, or physical membrane damage, and it can be used in multicolor microscopy. We confirm the modularity of this approach by also adapting it for improved hydrolytic stability, as the redox probe MDG2. We conclude by showing the unique performance of MDG probes in revealing axonal membrane damage (which DNA fluorogens cannot achieve) and in discriminating damage on a cell-by-cell basis in embryos in vivo. The MDG design thus provides powerful modular tools for wash-free in vivo imaging of membrane damage, and indicates how designs may be adapted for selective delivery of drug cargoes to these damaged cells: offering an outlook from selective diagnosis toward therapy of membrane-compromised cells in disease.
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Neuromyelitis optica is a chronic neuroinflammatory disease, which primarily targets astrocytes and often results in severe axon injury of unknown mechanism. Neuromyelitis optica patients harbour autoantibodies against the astrocytic water channel protein, aquaporin-4 (AQP4-IgG), which induce complement-mediated astrocyte lysis and subsequent axon damage. Using spinal in vivo imaging in a mouse model of such astrocytopathic lesions, we explored the mechanism underlying neuromyelitis optica-related axon injury. Many axons showed a swift and morphologically distinct 'pearls-on-string' transformation also readily detectable in human neuromyelitis optica lesions, which especially affected small calibre axons independently of myelination. Functional imaging revealed that calcium homeostasis was initially preserved in this 'acute axonal beading' state, ruling out disruption of the axonal membrane, which sets this form of axon injury apart from previously described forms of traumatic and inflammatory axon damage. Morphological, pharmacological and genetic analyses showed that AQP4-IgG-induced axon injury involved osmotic stress and ionic overload, but does not appear to use canonical pathways of Wallerian-like degeneration. Subcellular analysis demonstrated remodelling of the axonal cytoskeleton in beaded axons, especially local loss of microtubules. Treatment with the microtubule stabilizer epothilone, a putative therapy approach for traumatic and degenerative axonopathies, prevented axonal beading, while destabilizing microtubules sensitized axons for beading. Our results reveal a distinct form of immune-mediated axon pathology in neuromyelitis optica that mechanistically differs from known cascades of post-traumatic and inflammatory axon loss, and suggest a new strategy for neuroprotection in neuromyelitis optica and related diseases.
Assuntos
Neuromielite Óptica , Animais , Aquaporina 4 , Astrócitos/metabolismo , Autoanticorpos/metabolismo , Axônios/patologia , Humanos , Imunoglobulina G/metabolismo , Camundongos , Neuromielite Óptica/metabolismoRESUMO
Death receptor 6 (DR6) is an orphan member of the TNF receptor superfamily and controls cell death and differentiation in a cell-autonomous manner in different cell types. Here, we report an additional non-cell-autonomous function for DR6 in the peripheral nervous system (PNS). DR6-knockout (DR6 KO) mice showed precocious myelination in the PNS Using an in vitro myelination assay, we demonstrate that neuronal DR6 acts in trans on Schwann cells (SCs) and reduces SC proliferation and myelination independently of its cytoplasmic death domain. Mechanistically, DR6 was found to be cleaved in neurons by "a disintegrin and metalloprotease 10" (ADAM10), releasing the soluble DR6 ectodomain (sDR6). Notably, in the in vitro myelination assay, sDR6 was sufficient to rescue the DR6 KO phenotype. Thus, in addition to the cell-autonomous receptor function of full-length DR6, the proteolytically released sDR6 can unexpectedly also act as a paracrine signaling factor in the PNS in a non-cell-autonomous manner during SC proliferation and myelination. This new mode of DR6 signaling will be relevant in future attempts to target DR6 in disease settings.
Assuntos
Proteína ADAM10/metabolismo , Secretases da Proteína Precursora do Amiloide/metabolismo , Proliferação de Células , Proteínas de Membrana/metabolismo , Neurônios/metabolismo , Receptores do Fator de Necrose Tumoral/metabolismo , Células de Schwann/metabolismo , Animais , Morte Celular , Linhagem Celular , Citoplasma/metabolismo , Domínio de Morte , Desintegrinas/metabolismo , Feminino , Células HEK293 , Humanos , Hibridomas , Masculino , Metaloproteases/metabolismo , Camundongos , Camundongos Knockout , Bainha de Mielina/metabolismo , Comunicação Parácrina , Fenótipo , Receptores do Fator de Necrose Tumoral/genética , Células de Schwann/ultraestrutura , Especificidade por SubstratoRESUMO
The current lack of understanding about how nanocarriers cross the blood-brain barrier (BBB) in the healthy and injured brain is hindering the clinical translation of nanoscale brain-targeted drug-delivery systems. Here, the bio-distribution of lipid nano-emulsion droplets (LNDs) of two sizes (30 and 80 nm) in the mouse brain after traumatic brain injury (TBI) is investigated. The highly fluorescent LNDs are prepared by loading them with octadecyl rhodamine B and a bulky hydrophobic counter-ion, tetraphenylborate. Using in vivo two-photon and confocal imaging, the circulation kinetics and bio-distribution of LNDs in the healthy and injured mouse brain are studied. It is found that after TBI, LNDs of both sizes accumulate at vascular occlusions, where specifically 30 nm LNDs extravasate into the brain parenchyma and reach neurons. The vascular occlusions are not associated with bleedings, but instead are surrounded by processes of activated microglia, suggesting a specific opening of the BBB. Finally, correlative light-electron microscopy reveals 30 nm LNDs in endothelial vesicles, while 80 nm particles remain in the vessel lumen, indicating size-selective vesicular transport across the BBB via vascular occlusions. The data suggest that microvascular occlusions serve as "gates" for the transport of nanocarriers across the BBB.
Assuntos
Lesões Encefálicas Traumáticas , Nanopartículas , Animais , Barreira Hematoencefálica , Encéfalo , Portadores de Fármacos/química , Lipossomos , Camundongos , Nanopartículas/químicaRESUMO
Regulation of axon guidance and pruning of inappropriate synapses by class 3 semaphorins are key to the development of neural circuits. Collapsin response mediator protein 2 (CRMP2) has been shown to regulate axon guidance by mediating semaphorin 3A (Sema3A) signaling; however, nothing is known about its role in synapse pruning. Here, using newly generated crmp2-/- mice we demonstrate that CRMP2 has a moderate effect on Sema3A-dependent axon guidance in vivo, and its deficiency leads to a mild defect in axon guidance in peripheral nerves and the corpus callosum. Surprisingly, crmp2-/- mice display prominent defects in stereotyped axon pruning in hippocampus and visual cortex and altered dendritic spine remodeling, which is consistent with impaired Sema3F signaling and with models of autism spectrum disorder (ASD). We demonstrate that CRMP2 mediates Sema3F signaling in primary neurons and that crmp2-/- mice display ASD-related social behavior changes in the early postnatal period as well as in adults. Together, we demonstrate that CRMP2 mediates Sema3F-dependent synapse pruning and its dysfunction shares histological and behavioral features of ASD.
Assuntos
Transtorno do Espectro Autista , Peptídeos e Proteínas de Sinalização Intercelular/genética , Proteínas de Membrana/fisiologia , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/fisiologia , Semaforinas , Animais , Espinhas Dendríticas , Camundongos , Camundongos Knockout , Plasticidade Neuronal , Neurônios , Transdução de SinaisRESUMO
Conventionally, neuronal development is regarded to follow a stereotypic sequence of neurogenesis, migration, and differentiation. We demonstrate that this notion is not a general principle of neuronal development by documenting the timing of mitosis in relation to multiple differentiation events for bipolar cells (BCs) in the zebrafish retina using in vivo imaging. We found that BC progenitors undergo terminal neurogenic divisions while in markedly disparate stages of neuronal differentiation. Remarkably, the differentiation state of individual BC progenitors at mitosis is not arbitrary but matches the differentiation state of post-mitotic BCs in their surround. By experimentally shifting the relative timing of progenitor division and differentiation, we provide evidence that neurogenesis and differentiation can occur independently of each other. We propose that the uncoupling of neurogenesis and differentiation could provide neurogenic programs with flexibility, while allowing for synchronous neuronal development within a continuously expanding cell pool.
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Diferenciação Celular , Divisão Celular , Neurogênese , Retina/embriologia , Células Bipolares da Retina/fisiologia , Peixe-Zebra/embriologia , AnimaisRESUMO
Expansion of a (G4C2)n repeat in C9orf72 causes amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), but the link of the five repeat-encoded dipeptide repeat (DPR) proteins to neuroinflammation, TDP-43 pathology, and neurodegeneration is unclear. Poly-PR is most toxic in vitro, but poly-GA is far more abundant in patients. To directly compare these in vivo, we created congenic poly-GA and poly-PR mice. 40% of poly-PR mice were affected with ataxia and seizures, requiring euthanasia by 6 weeks of age. The remaining poly-PR mice were asymptomatic at 14 months of age, likely due to an 80% reduction of the transgene mRNA in this subgroup. In contrast, all poly-GA mice showed selective neuron loss, inflammation, as well as muscle denervation and wasting requiring euthanasia before 7 weeks of age. In-depth analysis of peripheral organs and blood samples suggests that peripheral organ failure does not drive these phenotypes. Although transgene mRNA levels were similar between poly-GA and affected poly-PR mice, poly-GA aggregated far more abundantly than poly-PR in the CNS and was also found in skeletal muscle. In addition, TDP-43 and other disease-linked RNA-binding proteins co-aggregated in rare nuclear inclusions in the hippocampus and frontal cortex only in poly-GA mice. Transcriptome analysis revealed activation of an interferon-responsive pro-inflammatory microglial signature in end-stage poly-GA but not poly-PR mice. This signature was also found in all ALS patients and enriched in C9orf72 cases. In summary, our rigorous comparison of poly-GA and poly-PR toxicity in vivo indicates that poly-GA, but not poly-PR at the same mRNA expression level, promotes interferon responses in C9orf72 disease and contributes to TDP-43 abnormalities and neuron loss selectively in disease-relevant regions.
Assuntos
Esclerose Lateral Amiotrófica/genética , Proteína C9orf72/genética , Interferons/biossíntese , Degeneração Neural/patologia , Esclerose Lateral Amiotrófica/imunologia , Esclerose Lateral Amiotrófica/patologia , Animais , Expansão das Repetições de DNA/genética , Modelos Animais de Doenças , Camundongos , Camundongos Transgênicos , Degeneração Neural/genética , Degeneração Neural/imunologia , Neurônios/patologiaRESUMO
Sequence variations in the triggering receptor expressed on myeloid cells 2 (TREM2) have been linked to an increased risk for neurodegenerative disorders such as Alzheimer's disease and frontotemporal lobar degeneration. In the brain, TREM2 is predominantly expressed in microglia. Several disease-associated TREM2 variants result in a loss of function by reducing microglial phagocytosis, impairing lipid sensing, preventing binding of lipoproteins and affecting shielding of amyloid plaques. We here investigate the consequences of TREM2 loss of function on the microglia transcriptome. Among the differentially expressed messenger RNAs in wild-type and Trem2-/- microglia, gene clusters are identified which represent gene functions in chemotaxis, migration and mobility. Functional analyses confirm that loss of TREM2 impairs appropriate microglial responses to injury and signals that normally evoke chemotaxis on multiple levels. In an ex vivo organotypic brain slice assay, absence of TREM2 reduces the distance migrated by microglia. Moreover, migration towards defined chemo-attractants is reduced upon ablation of TREM2 and can be rescued by TREM2 re-expression. In vivo, microglia lacking TREM2 migrate less towards injected apoptotic neurons, and outgrowth of microglial processes towards sites of laser-induced focal CNS damage in the somatosensory cortex is slowed. The apparent lack of chemotactic stimulation upon depletion of TREM2 is consistent with a stable expression profile of genes characterizing the homoeostatic signature of microglia.
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Quimiotaxia , Glicoproteínas de Membrana/deficiência , Glicoproteínas de Membrana/genética , Microglia/fisiologia , Neurônios/patologia , Receptores Imunológicos/deficiência , Receptores Imunológicos/genética , Doença de Alzheimer/genética , Doença de Alzheimer/fisiopatologia , Células Cultivadas , Demência Frontotemporal , Perfilação da Expressão Gênica , Humanos , Mutação com Perda de Função , Células Mieloides , Doenças Neurodegenerativas/genética , Doenças Neurodegenerativas/fisiopatologia , FagocitoseRESUMO
In vivo optical imaging has emerged as a powerful tool with which to study cellular responses to injury and disease in the mammalian CNS. Important new insights have emerged regarding axonal degeneration and regeneration, glial responses and neuroinflammation, changes in the neurovascular unit, and, more recently, neural transplantations. Accompanying a 2017 SfN Mini-Symposium, here, we discuss selected recent advances in understanding the neuronal, glial, and other cellular responses to CNS injury and disease with in vivo imaging of the rodent brain or spinal cord. We anticipate that in vivo optical imaging will continue to be at the forefront of breakthrough discoveries of fundamental mechanisms and therapies for CNS injury and disease.
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Doenças do Sistema Nervoso Central/diagnóstico por imagem , Sistema Nervoso Central/diagnóstico por imagem , Sistema Nervoso Central/lesões , Neuroimagem/métodos , Animais , Humanos , Camundongos , Neuroimagem/instrumentação , RatosRESUMO
Using a descanned, laser-induced guide star and direct wavefront sensing, we demonstrate adaptive correction of complex optical aberrations at high numerical aperture (NA) and a 14-ms update rate. This correction permits us to compensate for the rapid spatial variation in aberration often encountered in biological specimens and to recover diffraction-limited imaging over large volumes (>240 mm per side). We applied this to image fine neuronal processes and subcellular dynamics within the zebrafish brain.
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Microscopia Confocal/instrumentação , Microscopia Confocal/estatística & dados numéricos , Óptica e Fotônica/instrumentação , Animais , Linhagem Celular , Óptica e Fotônica/normas , Fatores de Tempo , Peixe-ZebraRESUMO
OBJECTIVE: Neuromyelitis optica (NMO) is an autoimmune disease of the central nervous system, which resembles multiple sclerosis (MS). NMO differs from MS, however, in the distribution and histology of neuroinflammatory lesions and shows a more aggressive clinical course. Moreover, the majority of NMO patients carry immunoglobulin G autoantibodies against aquaporin-4 (AQP4), an astrocytic water channel. Antibodies against AQP4 can damage astrocytes by complement, but NMO histopathology also shows demyelination, and - importantly-axon injury, which may determine permanent deficits following NMO relapses. The dynamics of astrocyte injury in NMO and the mechanisms by which toxicity spreads to axons are not understood. METHODS: Here, we establish in vivo imaging of the spinal cord, one of the main sites of NMO pathology, as a powerful tool to study the formation of experimental NMO-related lesions caused by human AQP4 antibodies in mice. RESULTS: We found that human AQP4 antibodies caused acute astrocyte depletion with initial oligodendrocyte survival. Within 2 hours of antibody application, we observed secondary axon injury in the form of progressive swellings. Astrocyte toxicity and axon damage were dependent on AQP4 antibody titer and complement, specifically C1q. INTERPRETATION: In vivo imaging of the spinal cord reveals the swift development of NMO-related acute axon injury after AQP4 antibody-mediated astrocyte depletion. This approach will be useful in studying the mechanisms underlying the spread of NMO pathology beyond astrocytes, as well as in evaluating potential neuroprotective interventions. Ann Neurol 2016;79:794-805.
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Despite the inability of CNS axons to regenerate, an increased regenerative capacity can be elicited following conditioning lesion to the peripheral branch of dorsal root ganglia neurons (DRGs). By in vivo radiolabeling of rat DRGs, coupled to mass spectrometry and kinesin immunoprecipitation of spinal cord extracts, we determined that the anterograde transport of cytoskeleton components, metabolic enzymes and axonal regeneration enhancers, was increased in the central branch of DRGs following a peripheral conditioning lesion. Axonal transport of mitochondria was also increased in the central branch of Thy1-MitoCFP mice following a peripheral injury. This effect was generalized and included augmented transport of lysosomes and synaptophysin- and APP-carrying vesicles. Changes in axonal transport were only elicited by a peripheral lesion and not by spinal cord injury. In mice, elevated levels of motors and of polyglutamylated and tyrosinated tubulin were present following a peripheral lesion and can explain the increase in axonal transport induced by conditioning. In summary, our work shows that a peripheral injury induces a global increase in axonal transport that is not restricted to the peripheral branch, and that, by extending to the central branch, allows a rapid and sustained support of regenerating central axons.