Macrophages and microglia can be polarized along a continuum toward a detrimental (M1) or a beneficial (M2) state in the injured CNS. Although phagocytosis of myelin in vitro promotes M2 polarization, macrophage/microglia in the injured spinal cord retain a predominantly M1 state that is detrimental to recovery. We have identified two factors that underlie this skewing toward M1 polarization in the injured CNS. We show that TNF prevents phagocytosis-mediated conversion from M1 to M2 cells in vitro and in vivo in spinal cord injury (SCI). Additionally, iron that accumulates in macrophages in SCI increases TNF expression and the appearance of a macrophage population with a proinflammatory mixed M1/M2 phenotype. In addition, transplantation experiments show that increased loading of M2 macrophages with iron induces a rapid switch from M2 to M1 phenotype. The combined effect of this favors predominant and prolonged M1 macrophage polarization that is detrimental to recovery after SCI.

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This retrospective study was aimed to identify dogs with neoplasms affecting the central nervous system (CNS) and compile information on the affected breeds, sex, age group, anatomical site of the tumor, type of clinical signs and clinical course, and laboratory results. The study included the cases submitted to the Veterinary Teaching Hospital (HVU) of the Federal University of Santa Maria (UFSM), Brazil, from January 2003 to June 2011. The 26 neoplasms affecting the CNS included in this study occurred mainly in Boxers (35%) and the predominantly affected age-group was 5-year-old or older (92.3%). The course of clinical signs in dogs with brain neoplasms was 7-115 days and that of spinal cord tumors was 7-420 days. The most frequently observed neurological signs in dogs with brain and spinal cord neoplasms were respectively changes in the conscience levels (58%), which were characterized by somnolence, and spinal hyperesthesia (57%). The cortico-thalamic region and the T3-L3 spinal cord segment were the most frequently anatomical sites involved (58% and 43%, respectively). Ten out 12 neoplasms affecting the brain were primary (83.3%) whereas only four of those 14 neoplasms affecting the spinal cord were primary (28.6%). Meningioma was the most frequent m primary neoplasms affecting the brain and spinal cord of dogs, consisting respectively of 40% e 75% of the cases.