title: The disruption of mitochondrial axonal transport is an early event in neuroinflammation.
abstract: BACKGROUND
  In brain inflammatory diseases, axonal damage is one of the most critical steps in the cascade that leads to permanent disability. Thus, identifying the initial events triggered by inflammation or oxidative stress that provoke axonal damage is critical for the development of neuroprotective therapies. Energy depletion due to mitochondrial dysfunction has been postulated as an important step in the damage of axons. This prompted us to study the effects of acute inflammation and oxidative stress on the morphology, transport, and function of mitochondria in axons.
  
  
  METHODS
  Mouse cerebellar slice cultures were challenged with either lipopolysaccharide (LPS) or hydrogen peroxide (H2O2) ex vivo for 24 h. Axonal mitochondrial morphology was evaluated by transmission electron microscopy (TEM) and mitochondrial transportation by time-lapse imaging. In addition, mitochondrial function in the cerebellar slice cultures was analyzed through high-resolution respirometry assays and quantification of adenosine triphosphate (ATP) production.
  
  
  RESULTS
  Both conditions promoted an increase in the size and complexity of axonal mitochondria evident in electron microscopy images, suggesting a compensatory response. Such compensation was reflected at the tissue level as increased respiratory activity of complexes I and IV and as a transient increase in ATP production in response to acute inflammation. Notably, time-lapse microscopy indicated that mitochondrial transport (mean velocity) was severely impaired in axons, increasing the proportion of stationary mitochondria in axons after LPS challenge. Indeed, the two challenges used produced different effects: inflammation mostly reducing retrograde transport and oxidative stress slightly enhancing retrograde transportation.
  
  
  CONCLUSIONS
  Neuroinflammation acutely impairs axonal mitochondrial transportation, which would promote an inappropriate delivery of energy throughout axons and, by this way, contribute to axonal damage. Thus, preserving axonal mitochondrial transport might represent a promising avenue to exploit as a therapeutic target for neuroprotection in brain inflammatory diseases like multiple sclerosis.
authors: Center of Neuroimmunology, Institut d'Investigacions Biomèdiques August Pi Sunyer (IDIBAPS), Cellex Building, Laboratory 3A, Casanova 145, 08036, Barcelona, Spain.
authors: Oihana
authors: O
authors: Errea
authors: Center of Neuroimmunology, Institut d'Investigacions Biomèdiques August Pi Sunyer (IDIBAPS), Cellex Building, Laboratory 3A, Casanova 145, 08036, Barcelona, Spain.
authors: Beatriz
authors: B
authors: Moreno
authors: Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi Sunyer (IDIBAPS), 08036, Barcelona, Spain.
authors: Alba
authors: A
authors: Gonzalez-Franquesa
authors: Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi Sunyer (IDIBAPS), 08036, Barcelona, Spain.|Spanish Biomedical Research Center in Diabetes and associated disorders (CIBERDEM), University of Barcelona, 08907, Barcelona, Spain.|Department of Physiological Sciences II, University of Barcelona, 08907, Barcelona, Spain.
authors: Pablo M
authors: PM
authors: Garcia-Roves
authors: Center of Neuroimmunology, Institut d'Investigacions Biomèdiques August Pi Sunyer (IDIBAPS), Cellex Building, Laboratory 3A, Casanova 145, 08036, Barcelona, Spain. pvilloslada@clinic.ub.es.|University of California, San Francisco, USA. pvilloslada@clinic.ub.es.
authors: Pablo
authors: http://orcid.org/0000-0002-8735-6119
authors: P
authors: Villoslada
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D001370:Axonal Transport / Q000187:drug effects / Q000502:physiology*; D001369:Axons / Q000187:drug effects / Q000648:ultrastructure*; D002531:Cerebellum / Q000187:drug effects / Q000648:ultrastructure*; D005786:Gene Expression Regulation / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000633:toxicity; D066298:In Vitro Techniques; D008070:Lipopolysaccharides / Q000633:toxicity; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D009097:Multienzyme Complexes / Q000378:metabolism; D009924:Organ Culture Techniques; D016877:Oxidants / Q000633:toxicity; D013997:Time Factors; D014162:Transfection
chemical_list: D008070:Lipopolysaccharides; D008164:Luminescent Proteins; D009097:Multienzyme Complexes; D016877:Oxidants; C413663:fluorescent protein 583; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide