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Background: Macrophage migration to the vessels is important for vascular inflammation and induces vascular degenerative diseases. Macrophages secrete matrix metalloprotainases (MMPs), which activate many cytokines and digest extracellular matrix of aorta. MMPs play an important role in the progression of aortic aneurysm. We previously reported that non-specific prolyl hydroxylase domain protein (PHD) inhibitor, Cobalt chloride (CoCl2), suppressed MMP-2 and -9 expression and attenuated experimental abdominal aortic aneurysm (AAA) formation in mice. In this report we investigated the myeloid specific PHD2 knockout effect on MMPs expression and aneurysm formation. Methods: Myeloid specific PHD2 conditional knockout (MyPHD2KO) mice were generated. Experimental AAA was induced by periaortic application of Calcium chloride (CaCl2) for 6 weeks. In vitro Lipopolysaccharide (LPS, 100ng/ml) was used to induce MMP-2 and MMP-9 expression with peritoneal macrophages. MMPs mRNA, protein expression and protein activity were analyzed by qRT-PCR, Western blot analysis and Zymography, respectively. ELISA-based NF-κB p65 Transcription Factor Assay was used to examine NF-κB p65 binding activity with consensus DNA binding site. Results: CaCl2-induced AAA was suppressed with MyPHD2KO mice (max diameter of aneurysm: 1.03mm±0.14mm in MyPHD2KO group, 1.63mm±0.34mm in Control AAA group, p Conclusion: Deletion of PHD2 in myeloid lineage attenuated MMPs expression by NF-κB inactivation and suppressed AAA formation. PHD2 in macrophage may be a novel target for cardiovascular disease treatment.

Background: Hypoxia-inducible factor-1α (Hif1α) is a transcriptional factor that regulates various genes reacting hypoxic conditions. In atherosclerotic legion, Hif1α is thought to be regulating inflammatory responses. We previously reported that myeloid specific Proryl hydroxylase domain protein2 deletion had protective effect on cardiovascular disease in animal model. The roll of Hif1α of myeloid lineage in inflammatory response is not determined. Methods and Results: Myeloid specific Hif1α knock out mice (MyHif KO) were created using Cre-lox recombination. MyHif KO mice were crossed with Apolipoprotein E knockout (ApoEKO) mice to create double knock out mice (MyHif/ApoE DKO group, n=18). ApoEKO with Hif1α flox/flox (without Cre recombinase) mice were used as control group (n=11). Two groups were fed with high fat diet (HFD) and infused with Angiotensin II (AII, 1800ng/kg/min) by osmotic mini pump for 4 weeks to promote abdominal aortic aneurysm (AAA) formation. The genotype of mice was blinded during experiment. There was no significant difference in survival rate between two groups. MyHif/ApoE DKO increased AAA formation rate (94.4% vs 81.8% in control) and aortic diameter (2.42mm±0.21mm vs 1.89±0.27mm in control). AAA classification reported by Daugherty et al was significantly exaggerated in MyHif/ApoE DKO group (2.75±0.35 vs 1.63±0.46 in control, P=0.03). Elastin degradation grade was checked by Elastica van Gieson staining. MyHif/ApoE DKO also deteriorated the elastin degradation grade (3.91±0.08 vs 3.25±0.31, P=0.01). The number of macrophages which migrated to abdominal aorta was increased in MyHif/ApoE DKO group (565±110.3/section vs 260.5±136.5/section in control, P=0.0507), whereas MyHif/ApoE DKO did not change the glucose level, blood pressure and body weight. Peritoneal macrophages from MyHif/ApoE DKO were significantly activated the migration induced by monocyte chemotactic protein-1 in dose dependent manner. Conclusion: Hif1α of myeloid lineage might have vascular protective effect via suppressing the macrophage activation in the model of AII-induced AAA in mice.