title: Myocardial injury after ischemia-reperfusion in mice deficient in Akt2 is associated with increased cardiac macrophage density.
abstract: Akt2 protein kinase has been shown to promote cell migration and actin polymerization in several cell types, including macrophages. Because migrating macrophages constitute an important inflammatory response after myocardial ischemia, we determined cardiac macrophage expression after ischemia-reperfusion (I/R) injury and cryo-injury in mice lacking Akt2 (Akt2-KO). At 7 days post-I/R, Akt2-KO cardiac tissues showed an increase in immunohistochemical staining for macrophage markers (Galectin 3 and F4/80) compared with wild-type (WT) mice, indicating macrophage density was increased in the injured Akt2-KO myocardium. This change was time dependent because macrophage density was similar between WT and Akt2-KO myocardium at 3 days post-I/R, but by 7 and 14 days post-I/R, macrophage density was significantly increased in Akt2-KO myocardium. Concomitantly, infarct size was larger and cardiac function was reduced in Akt2-KO mice subjected to I/R. However, when cryo-infarction produced similar infarct sizes in the anterior wall in both WT and Akt2-KO mice, macrophage density remained higher in Akt2-KO mouse myocardium, suggesting Akt2 regulates myocardial macrophage density independent of infarct size. Consistently, bone marrow from Akt2-KO mice enhanced myocardial macrophage density in both C57/B6 WT and Akt2-KO recipient mice. Finally, reciprocal ex-vivo coculturing of macrophages and cardiac myocytes showed that activated Akt2-KO peritoneal macrophages had reduced mobility and adhesion when compared with WT littermate controls. Thus, although Akt-2 KO mice did not affect the initial inflammation response after injury and Akt2 deficiency has been shown to impair cell migration or motility in macrophages, our data suggested a novel mechanism in which increasing retention of Akt2-KO macrophages resulted in increasing cardiac Akt2-KO macrophage density in the myocardial space.
authors: Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors: Xue
authors: X
authors: Li
authors: Deana
authors: D
authors: Mikhalkova
authors: Erhe
authors: E
authors: Gao
authors: Jin
authors: J
authors: Zhang
authors: Valerie
authors: V
authors: Myers
authors: Carmen
authors: C
authors: Zincarelli
authors: Yonghong
authors: Y
authors: Lei
authors: Jianliang
authors: J
authors: Song
authors: Walter J
authors: WJ
authors: Koch
authors: Karsten
authors: K
authors: Peppel
authors: Joseph Y
authors: JY
authors: Cheung
authors: Arthur M
authors: AM
authors: Feldman
authors: Tung O
authors: TO
authors: Chan
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D017209:Apoptosis; D016026:Bone Marrow Transplantation; D002465:Cell Movement; D002478:Cells, Cultured; D018920:Coculture Techniques; D004195:Disease Models, Animal; D037502:Galectin 3 / Q000378:metabolism; D005786:Gene Expression Regulation; D006439:Hemodynamics; D007150:Immunohistochemistry; D008264:Macrophages / Q000201:enzymology* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009203:Myocardial Infarction / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D015428:Myocardial Reperfusion Injury / Q000201:enzymology* / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology; D051057:Proto-Oncogene Proteins c-akt / Q000172:deficiency* / Q000235:genetics; D013997:Time Factors; D016277:Ventricular Function, Left; D014945:Wound Healing
chemical_list: D000943:Antigens, Differentiation; D037502:Galectin 3; C485095:Lgals3 protein, mouse; C036763:monocyte-macrophage differentiation antigen; C494922:Akt2 protein, mouse; D051057:Proto-Oncogene Proteins c-akt