title: Immunohistochemical study of arginase-1 in the spinal cords of Lewis rats with experimental autoimmune encephalomyelitis.
abstract: Arginase-1, a marker for M2 phenotype alternatively activated macrophages, inhibits inflammation and is associated with phagocytosis of cell debris and apoptotic cells. We analyzed the expression of arginase-1, a competitive enzyme of inducible nitric oxide synthase (iNOS), in the spinal cords of Lewis rats with experimental autoimmune encephalomyelitis (EAE). Western blot analysis showed that both arginase-1 and iNOS significantly increased in the spinal cords of rats at the peak stage of EAE compared with the expression level in control animals (p<0.05) and declined thereafter. Immunofluorescent staining demonstrated that increased expression of arginase-1 in EAE spinal cords was confirmed in macrophages as well as in some neurons and astrocytes that were constitutively positive for arginase-1 in normal spinal cords. A semiquantitative analysis by immunofluorescence showed that in EAE lesions, an increased level of arginase-1 immunoreactivity was matched with ED1-positive macrophages, which were also positive for activin A, a marker for the M2 phenotype. Taking all of these findings into consideration, we postulate that the increased level of arginase-1, which is partly from M2 macrophages, contributes to the modulation of neuroinflammation in EAE lesions, possibly through the reduction of nitric oxide in the lesion via competition with iNOS for the use of L-arginine.
authors.affiliation: Department of Anatomy, School of Medicine, Jeju National University, Jeju 690-756, South Korea.
authors.forename: Meejung
authors.initials: M
authors.lastname: Ahn
authors.forename: Wonjun
authors.initials: W
authors.lastname: Yang
authors.forename: Heechul
authors.initials: H
authors.lastname: Kim
authors.forename: Jae-kwang
authors.initials: JK
authors.lastname: Jin
authors.forename: Changjong
authors.initials: C
authors.lastname: Moon
authors.forename: Taekyun
authors.initials: T
authors.lastname: Shin
mesh_terms: D000818:Animals; D001119:Arginase / Q000378:metabolism*; D001253:Astrocytes / Q000201:enzymology; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000201:enzymology*; D005260:Female; D007150:Immunohistochemistry; D008264:Macrophages / Q000201:enzymology; D008297:Male; D009474:Neurons / Q000201:enzymology*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D013116:Spinal Cord / Q000201:enzymology*
chemical_list: D052247:Nitric Oxide Synthase Type II; D001119:Arginase; C542908:arginase I, rat