In vivo inhibition of miR-155 significantly alters post-stroke inflammatory response.
MicroRNA miR-155 is implicated in modulation of the inflammatory processes in various pathological conditions. In our previous studies, we demonstrated that in vivo inhibition of miR-155 promotes functional recovery after mouse experimental stroke. In the present study, we explored if this beneficial effect is associated with miR-155 inhibition-induced alterations in post-stroke inflammatory response.



Intravenous injections of a specific miR-155 inhibitor were initiated at 48 h after mouse distal middle cerebral artery occlusion (dMCAO). Temporal changes in the expression of cytokines and key molecules associated with cytokine signaling were assessed at 7, 14, and 21 days after dMCAO, using mouse cytokine gene and protein arrays and Western blot analyses. Electron and immunofluorescence confocal microscopy techniques were used to evaluate the ultrastructural changes, as well as altered expression of specific phenotypic markers, at different time points after dMCAO.



In the inhibitor-injected mice (inhibitor group), there was a significant decrease in CCL12 and CXCL3 cytokine expression at 7 days and significantly increased levels of major cytokines IL-10, IL-4, IL-6, MIP-1α, IL-5, and IL-17 at 14 days after dMCAO. These temporal changes correlated with altered expression of miR-155 target proteins SOCS-1, SHIP-1, and C/EBP-β and phosphorylation levels of cytokine signaling regulator STAT-3. Electron microscopy showed decreased number of phagocytically active peri-vascular microglia/macrophages in the inhibitor samples. Immunofluorescence and Western blot of these samples demonstrated that expression of leukocyte/ macrophage marker CD45 and phagocytosis marker CD68 was reduced at 7 days, and in contrast, significantly increased at 14 days after dMCAO, as compared to controls.



Based on our findings, we propose that in vivo miR-155 inhibition following mouse stroke significantly alters the time course of the expression of major cytokines and inflammation-associated molecules, which could influence inflammation process and tissue repair after experimental cerebral ischemia.
Department of Neurosurgery, University of New Mexico Health Sciences Center, 1101 Yale Blvd, Albuquerque, NM, 87106-3834, USA.
Juan Carlos
JC
Pena-Philippides
Department of Neurosurgery, University of New Mexico Health Sciences Center, 1101 Yale Blvd, Albuquerque, NM, 87106-3834, USA.
Ernesto
E
Caballero-Garrido
Ilia State University, Tbilisi, Georgia.
Tamar
T
Lordkipanidze
Department of Neurosurgery, University of New Mexico Health Sciences Center, 1101 Yale Blvd, Albuquerque, NM, 87106-3834, USA. troitbak@salud.unm.edu.
Tamara
0000-0003-1599-6819
T
Roitbak
D000818:Animals; D000070416:Antagomirs / Q000494:pharmacology / Q000627:therapeutic use*; D050882:CREB-Binding Protein / Q000235:genetics / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D004660:Encephalitis / Q000209:etiology* / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D020244:Infarction, Middle Cerebral Artery / Q000150:complications*; D008264:Macrophages / Q000473:pathology / Q000648:ultrastructure; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000378:metabolism*; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D017628:Microglia / Q000473:pathology / Q000648:ultrastructure; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D000071222:Suppressor of Cytokine Signaling 1 Protein / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
C491049:Aif1 protein, mouse; D000070416:Antagomirs; D002135:Calcium-Binding Proteins; D016207:Cytokines; D035683:MicroRNAs; D008840:Microfilament Proteins; C532623:Mirn155 microRNA, mouse; C491590:Socs1 protein, mouse; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050882:CREB-Binding Protein; C494364:Crebbp protein, mouse; C000606433:Inpp5d protein, mouse; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases
MicroRNA; Microglia/macrophages; Post-stroke inflammation; dMCAO; miR-155