We have previously shown that treating atherosclerosis with bone morphogenetic protein-7 (BMP-7) affects the presence of macrophage subtypes in vitro, however it remains unknown whether BMP-7 treatment affects development and progression of atherosclerosis in vivo at an early and mid-stage of the disease. We therefore performed a Day 5 (D5) and Day 28 (D28) study to examine BMP-7's potential to affect monocyte differentiation. Atherosclerotic plaque formation was developed using our standard method and ApoE-/- mice were sacrificed at D5 and D28 post-surgery. Treatment animals received intravenous injections of BMP-7 at 200µg/kg of bodyweight. Hematoxylin and Eosin morphological stain shows that BMP-7 is capable of significantly reducing plaque accumulation at D28 post-surgery vs. PLCA group, p < 0.05. At D5, plaque formation was reduced but not significant. Immunohistochemistry staining was performed to determine BMP-7's effect on monocytes (CD14), inflammatory M1 (iNOS) and anti-inflammatory M2 (CD206, Arginase-1) macrophages. Immunohistochemistry results show BMP-7 administration reduced pro-inflammatory monocytes and M1 macrophages at D5 and D28 compared to PLCA animals; however, monocytes were not statistically lower at D28. The anti-inflammatory M2 macrophage population was significantly less in PLCA animals compared to SHAM animals at D5 and D28. There was no significant difference in M2 macrophages between PLCA and PLCA + BMP7 animals at D5, however, by D28, PLCA + BMP7 animals showed a significant increase in M2 macrophages compared to PLCA animals. Western blot analysis confirms a significant increase in pro-survival kinase ERK and a significant reduction in pro-inflammatory kinases p38 and JNK in BMP-7 treated mice (D5 and D28, p < 0.05). ELISA showed a significant reduction in pro-inflammatory cytokines IL-6, MCP-1, and TNF-? (D5 and D28, p < 0.05) and a significant increase in anti-inflammatory cytokine IL-10 in BMP-7 treated mice (D5 and D28, p < 0.05). In summary, our data indicate BMP-7 treatment induces monocyte to M2 macrophage differentiation, increases anti-inflammatory cytokine levels (IL-1ra and IL-10), and improves blow flow velocity (D5 and D28, p < 0.05) compared to untreated animals. The mechanisms of monocyte to M2 macrophage differentiation appear to be mediated by the p38, JNK, and ERK pathways. This study suggests BMP-7 is capable of reducing inflammation and slowing progression of atherosclerosis at both an early and mid-stage of the disease.
| Identifer | oai:union.ndltd.org:ucf.edu/oai:stars.library.ucf.edu:etd-6232 |
| Date | 01 January 2016 |
| Creators | Shoulders, Heidi |
| Publisher | STARS |
| Source Sets | University of Central Florida |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Electronic Theses and Dissertations |
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