RESUMO
BACKGROUND: Macrophages play a key role in peripheral nerve repair and demonstrate complex phenotypes that are highly dependent on microenvironmental cues. METHODS: We determined temporal changes in macrophage gene expression over time using RNA sequencing after fluorescence-activated cell sorting (FACS) macrophage populations from injured peripheral nerve. We identified key upstream regulators and dominant pathways using ingenuity pathway analysis and confirmed these changes with NanoString technology. We then investigate the effects of extreme polarizers of macrophage phenotype (IL4 and IFNγ) on nerve regeneration. We determined macrophage gene expression in vivo at the site of peripheral nerve injury with NanoString technology, and assessed recovery from sciatic nerve injury by cranial tibial muscle weights and retrograde labeling motor neurons in mice with deletion of IL4 or IFNγ receptors. RESULTS: We demonstrate that IL4R and IFNγR deletions provide complementary responses to polarization, and alter expression of genes associated with angiogenesis and axonal extension, but do not influence recovery from peripheral nerve transection at 8 weeks after repair. CONCLUSIONS: Overall, this study provides a framework to evaluate the phenotype of macrophages over time, and provides a broader and more precise assessment of gene expression changes than has previously been commonly used. This data suggests ways in which polarization may be modulated to improve repair.
Assuntos
Regulação da Expressão Gênica/fisiologia , Macrófagos/patologia , Traumatismos dos Nervos Periféricos/patologia , Animais , Células Cultivadas , Citocinas/metabolismo , Modelos Animais de Doenças , Citometria de Fluxo , Regulação da Expressão Gênica/efeitos dos fármacos , Peptídeos e Proteínas de Sinalização Intercelular , Interleucina-1/genética , Interleucina-1/metabolismo , Lipopolissacarídeos/toxicidade , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Regeneração Nervosa/fisiologia , Traumatismos dos Nervos Periféricos/induzido quimicamente , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Receptores de Interferon/genética , Receptores de Interferon/metabolismo , Estatísticas não Paramétricas , Fatores de Tempo , Transfecção , Receptor de Interferon gamaRESUMO
Equine herpesvirus type 1 (EHV-1) is a ubiquitous and highly contagious pathogen that causes a range of disease severities with outbreaks of notable economic impact. Given the limitations in immune protection of current vaccines and the limited effectiveness of antiviral drugs on EHV-1 infections in vivo, improved treatment measures are needed to control disease. The use of drugs that alter the epigenetic state of herpes simplex virus genome has been shown to limit viral primary infection and reactivation both in vitro and in vivo. Therefore, we tested the hypothesis that maintaining a repressive epigenetic state on the EHV-1 genome in the host equine cell would decrease viral load during lytic infection. Equine fetal kidney cells (EFKCs) or isolated peripheral blood leukocytes were treated in vitro with (a) the nucleoside analog ganciclovir; (b) the histone demethylase inhibitor OG-L002; (c) both ganciclovir and OG-L002; or (d) dimethyl sulfoxide (DMSO, vehicle control); and then infected with a clinical EHV-1 isolate. Treatment of EFKCs with ganciclovir (mean 22.3 DNA copies per cell, p = 0.0005), OG-L002 (mean 25.6, p = 0.005) or both ganciclovir and OG-L002 (mean 7.1, p = 0.0001) resulted in decreased EHV-1 viral load at 24 h post-infection (hpi) in comparison with DMSO (mean 42.0), with greater impact using the combined treatment. Further, EHV-1 gene expression at 3 hpi decreased when EFKCs were infected in the presence of ganciclovir (p = 0.04) and combined treatment of ganciclovir and OG-L002 (p = 0.0003). In contrast, under similar conditions, neither ganciclovir nor OG-L002 suppressed EHV-1 infection in leukocytes. Differences between cell types, drug penetrance, or drug turnover, may have contributed to the distinct effects observed in this study.
RESUMO
Peripheral nerve possesses the inherent ability to regrow and recover following injury. However, nerve regeneration is often slow and incomplete due to limitations associated with the local microenvironment during the repair process. Manipulation of the local microenvironment at the site of nerve repair, therefore, represents a significant opportunity for improvement in downstream outcomes. Macrophages and Schwann cells play a key role in the orchestration of early events after peripheral nerve injury. We describe the production, characterization, and use of an injectable, peripheral nerve-specific extracellular matrix-based hydrogel (PNSECM) for promoting modulation of the local macrophage and Schwann cell responses at the site of nerve repair in a rodent model of sciatic nerve injury. We show that PNSECM hydrogels largely maintain the matrix structure associated with normal native peripheral nerve tissue. PNSECM hydrogels were also found to promote increased macrophage invasion, higher percentages of M2 macrophages and enhanced Schwann cell migration when used as a lumen filler in a rodent model of nerve gap repair using an inert nerve guidance conduit. These results suggest that an injectable PNSECM hydrogel can provide a supportive, bioactive scaffold which promotes repair of peripheral nerve in vivo. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 450-459, 2018.
Assuntos
Matriz Extracelular/metabolismo , Hidrogéis/farmacologia , Regeneração Nervosa/efeitos dos fármacos , Traumatismos dos Nervos Periféricos/fisiopatologia , Recuperação de Função Fisiológica , Nervo Isquiático/metabolismo , Animais , Movimento Celular/efeitos dos fármacos , Cães , Matriz Extracelular/ultraestrutura , Feminino , Membro Posterior/fisiopatologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Especificidade de Órgãos , Traumatismos dos Nervos Periféricos/patologia , Ratos Sprague-Dawley , Recuperação de Função Fisiológica/efeitos dos fármacos , Células de Schwann/efeitos dos fármacos , Células de Schwann/patologia , Nervo Isquiático/efeitos dos fármacosRESUMO
BACKGROUND: Quantification of the number of axons reinnervating a target organ is often used to assess regeneration after peripheral nerve repair, but because of axonal branching, this method can overestimate the number of motor neurons regenerating across an injury. Current methods to count the number of regenerated motor neurons include retrograde labeling followed by cryosectioning and counting labeled motor neuron cell bodies, however, the process of sectioning introduces error from potential double counting of cells in adjacent sections. NEW METHOD: We describe a method, retroDISCO, that optically clears whole mouse spinal cord without loss of fluorescent signal to allow imaging of retrograde labeled motor neurons using confocal microscopy. RESULTS: Complete optical clearing of spinal cords takes four hours and confocal microscopy can obtain z-stacks of labeled motor neuron pools within 3-5min. The technique is able to detect anticipated differences in motor neuron number after cross-suture and conduit repair compared to intact mice and is highly repeatable. COMPARISON WITH EXISTING METHOD: RetroDISCO is inexpensive, simple, robust and uses commonly available microscopy techniques to determine the number of motor neurons extending axons across an injury site, avoiding the need for labor-intensive cryosectioning and potential double counting of motor neuron cell bodies in adjacent sections. CONCLUSIONS: RetroDISCO allows rapid quantification of the degree of reinnervation without the confounding produced by axonal sprouting.