1. Evidence of a Myenteric Plexus Barrier and Its Macrophage-Dependent Degradation During Murine Colitis: Implications in Enteric Neuroinflammation
- Author
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Tamas Kovacs, Nandor Nagy, Ryo Hotta, Ildikó Bódi, Zoltán Varga, Allan M. Goldstein, Viktória E. Tóth, Rhian Stavely, David Dora, Szilamér Ferenczi, and Krisztina J. Kovács
- Subjects
Macrophage ,Fluorescent Antibody Technique ,RC799-869 ,BMB, blood-myenteric barrier ,STED, stimulated emission depletion ,Inflammatory bowel disease ,Enteric Nervous System ,Mice ,0302 clinical medicine ,MyMs, myenteric plexus macrophages ,Barrier function ,Myenteric plexus ,Original Research ,GFP, green fluorescent protein ,0303 health sciences ,education.field_of_study ,TNF, tumor necrosis factor ,PGS, periganglionic space ,IBD, inflammatory bowel disease ,Chemistry ,Gastroenterology ,Diseases of the digestive system. Gastroenterology ,MCP-1, monocyte chemoattractant protein-1 ,Colitis ,GI, gastrointestinal ,Immunohistochemistry ,Cell biology ,ECM, extracellular matrix ,Extracellular Matrix ,MMP, matrix metalloproteinase ,Neutrophil Infiltration ,iNOS, inducible nitric oxide synthase ,LPS, lipopolysaccharide ,qPCR, quantitative polymerase chain reaction ,FITC, fluorescein isothiocyanate ,Disease Susceptibility ,Iba1, ionized calcium-binding adapter molecule 1 ,Neuroglia ,PAMP, pathogen-associated molecular pattern ,Barrier ,BBB, blood-brain barrier ,Population ,PBS, phosphate-buffered saline ,Myenteric Plexus ,Intraganglionic Macrophage ,CNS, central nervous system ,Immunophenotyping ,03 medical and health sciences ,DSS, dextran sulfate sodium ,medicine ,Animals ,education ,Neuroinflammation ,030304 developmental biology ,ECM ,ENS, enteric nervous system ,Hepatology ,Macrophages ,Enteric Ganglion ,MM, muscularis macrophage ,medicine.disease ,IL, interleukin ,Disease Models, Animal ,Neuroinflammatory Diseases ,Enteric nervous system ,IGM, intraganglionic macrophage ,030217 neurology & neurosurgery ,Biomarkers - Abstract
Background & Aims Neuroinflammation in the gut is associated with many gastrointestinal (GI) diseases, including inflammatory bowel disease. In the brain, neuroinflammatory conditions are associated with blood-brain barrier (BBB) disruption and subsequent neuronal injury. We sought to determine whether the enteric nervous system is similarly protected by a physical barrier and whether that barrier is disrupted in colitis. Methods Confocal and electron microscopy were used to characterize myenteric plexus structure, and FITC-dextran assays were used to assess for presence of a barrier. Colitis was induced with dextran sulfate sodium, with co-administration of liposome-encapsulated clodronate to deplete macrophages. Results We identified a blood-myenteric barrier (BMB) consisting of extracellular matrix proteins (agrin and collagen-4) and glial end-feet, reminiscent of the BBB, surrounded by a collagen-rich periganglionic space. The BMB is impermeable to the passive movement of 4 kDa FITC-dextran particles. A population of macrophages is present within enteric ganglia (intraganglionic macrophages [IGMs]) and exhibits a distinct morphology from muscularis macrophages, with extensive cytoplasmic vacuolization and mitochondrial swelling but without signs of apoptosis. IGMs can penetrate the BMB in physiological conditions and establish direct contact with neurons and glia. Dextran sulfate sodium-induced colitis leads to BMB disruption, loss of its barrier integrity, and increased numbers of IGMs in a macrophage-dependent process. Conclusions In intestinal inflammation, macrophage-mediated degradation of the BMB disrupts its physiological barrier function, eliminates the separation of the intra- and extra-ganglionic compartments, and allows inflammatory stimuli to access the myenteric plexus. This suggests a potential mechanism for the onset of neuroinflammation in colitis and other GI pathologies with acquired enteric neuronal dysfunction., Graphical abstract
- Published
- 2021