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Rats and mice exhibit distinct inflammatory reactions after spinal cord injury
Author(s) -
Sroga Julie M.,
Jones T. Bucky,
Kigerl Kristina A.,
McGaughy Violeta M.,
Popovich Phillip G.
Publication year - 2003
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.10736
Subject(s) - microglia , biology , pathology , spinal cord injury , infiltration (hvac) , mhc class ii , neuroinflammation , spinal cord , fibronectin , t cell , inflammation , immunology , immune system , extracellular matrix , medicine , microbiology and biotechnology , neuroscience , physics , thermodynamics
Spinal contusion pathology in rats and mice is distinct. Cystic cavities form at the impact site in rats while a dense connective tissue matrix occupies the injury site in mice. Because inflammatory cells coordinate mechanisms of tissue injury and repair, we evaluated whether the unique anatomical presentation in spinally injured rats and mice is associated with a species‐specific inflammatory response. Immunohistochemistry was used to compare the leukocytic infiltrate between rats and mice. Microglia/macrophage reactions were similar between species; however, the onset and magnitude of lymphocyte and dendritic cell (DC) infiltration were markedly different. In rats, T‐cell numbers were highest between 3 and 7 days postinjury and declined by 50% over the next 3 weeks. In mice, significant T‐cell entry was not evident until 14 days postinjury, with T‐cell numbers doubling between 2 and 6 weeks. Dendritic cell influx paralleled T‐cell infiltration in rats but was absent in mouse spinal cord. De novo expression of major histocompatability class II molecules was increased in both species but to a greater extent in mice. Unique to mice were cells that resembled lymphocytes but did not express lymphocyte‐specific markers. These cells extended from blood vessels within the fibrotic tissue matrix and expressed fibronectin, collagen I, CD11b, CD34, CD13, and CD45. This phenotype is characteristic of fibrocytes, specialized blood‐borne cells involved in wound healing and immunity. Thus, species‐specific neuroinflammation may contribute to the formation of distinct tissue environments at the site of spinal cord injury in mice and rats. J. Comp. Neurol. 462:223–240, 2003. © 2003 Wiley‐Liss, Inc.