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Absence of myeloid COX-2 attenuates acute inflammation but does not influence development of atherosclerosis in apolipoprotein E null mice.

ABSTRACT: The role of myeloid cell cyclooxygenase-2 (COX-2) in the progression of atherosclerosis has not been clearly defined.We investigated the role of COX-2 expressed in the myeloid lineage in the development of atherosclerosis using a myeloid-specific COX-2(-/-) (COX-2(-M/-M)) mouse on a hyperlipidemic apolipoprotein (apo) E(-/-) background (COX-2(-M/-M)/apoE(-/-)). Myeloid COX-2 depletion resulted in significant attenuation of acute inflammation corresponding with decreased PGE(2) levels in an air pouch model. COX-2 depletion in myeloid cells did not influence development of atherosclerosis in COX-2(-M/-M)/apoE(-/-) when compared to apoE(-/-) littermates fed either chow or western diets. The unanticipated lack of contribution of myeloid COX-2 to the development atherosclerosis is not attributable to altered maintenance, differentiation, or mobilization of myeloid and lymphoid populations. Moreover, myeloid COX-2 depletion resulted in unaltered serum prostanoid levels and cellular composition of atherosclerotic lesions of COX-2(-M/-M)/apoE(-/-) mice.Our results suggest that COX-2 expression in myeloid cells, including macrophages, does not influence the development of atherosclerosis in mice.

SUBMITTER: Narasimha AJ

PROVIDER: S-EPMC2859183 | biostudies-other | 2010 Feb

REPOSITORIES: biostudies-other

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Absence of myeloid COX-2 attenuates acute inflammation but does not influence development of atherosclerosis in apolipoprotein E null mice.

Narasimha Ajay J AJ Watanabe Junji J Ishikawa Tomo-o TO Priceman Saul J SJ Wu Lily L Herschman Harvey R HR Reddy Srinivasa T ST

Arteriosclerosis, thrombosis, and vascular biology 20091119 2

<h4>Objective</h4>The role of myeloid cell cyclooxygenase-2 (COX-2) in the progression of atherosclerosis has not been clearly defined.<h4>Methods and results</h4>We investigated the role of COX-2 expressed in the myeloid lineage in the development of atherosclerosis using a myeloid-specific COX-2(-/-) (COX-2(-M/-M)) mouse on a hyperlipidemic apolipoprotein (apo) E(-/-) background (COX-2(-M/-M)/apoE(-/-)). Myeloid COX-2 depletion resulted in significant attenuation of acute inflammation correspo ...[more]

PMID: 19926832

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Project description:Macrophages play a pivotal role in atherosclerotic plaque development. Recent evidence has suggested the glucagon-like peptide-1 receptor (GLP-1R) agonist, liraglutide, can attenuate pro-inflammatory responses in macrophages. We hypothesized that liraglutide could limit atherosclerosis progression in vivo via modulation of the inflammatory response.Human THP-1 macrophages and bone marrow-derived macrophages, from both wild-type C57BL/6 (WT) and apolipoprotein E null mice (ApoE-/-) were used to investigate the effect of liraglutide on the inflammatory response in vitro. In parallel, ApoE-/- mice were fed a high-fat (60% calories from fat) high-cholesterol (1%) diet for 8 weeks to induce atherosclerotic disease progression with/without daily 300 ?g/kg liraglutide administration for the final 6 weeks. Macrophages were analysed for M?1 and M?2 macrophage markers by Western blotting, RT-qPCR, ELISA and flow cytometry. Atherosclerotic lesions in aortae from ApoE-/- mice were analysed by en face staining and monocyte and macrophage populations from bone marrow derived cells analysed by flow cytometry.Liraglutide decreased atherosclerotic lesion formation in ApoE-/- mice coincident with a reduction in pro-inflammatory and increased anti-inflammatory monocyte/macrophage populations in vivo. Liraglutide decreased IL-1beta in M?0 THP-1 macrophages and bone marrow-derived macrophages from WT mice and induced a significant increase in the M?2 surface marker mannose receptor in both M?0 and M?2 macrophages. Significant reduction in total lesion development was found with once daily 300 ?g/kg liraglutide treatment in ApoE-/- mice. Interestingly, liraglutide inhibited disease progression at the iliac bifurcation suggesting that it retards the initiation and development of disease. These results corresponded to attenuated M?1 markers (CCR7, IL-6 and TNF-alpha), augmented M?2 cell markers (Arg-1, IL-10 and CD163) and finally decreased M?1-like monocytes and macrophages from bone marrow-derived cells.This data supports a therapeutic role for liraglutide as an atheroprotective agent via modulating macrophage cell fate towards M?2 pro-resolving macrophages.

Project description:Fat inflammation may play an important role in comorbidities associated with obesity such as atherosclerosis.To first establish feasibility of fat transplantation, epididymal fat pads were harvested from wild-type C57BL/6J mice and transplanted into leptin-deficient (Lep(ob/ob)) mice. Fat transplantation produced physiological leptin levels and prevented obesity and infertility in Lep(ob/ob) mice. However, the transplanted fat depots were associated with chronically increased macrophage infiltration with characteristics identical to those observed in fat harvested from obese animals. The inflammation in transplanted adipose depots was regulated by the same factors that have been implicated in endogenous fat inflammation such as monocyte chemoattractant protein-1. To determine whether this inflamed adipose depot could affect vascular disease in mice, epididymal fat depots were transplanted into atherosclerosis-prone apolipoprotein E-deficient ApoE(-/-) mice. Plasma from ApoE(-/-) mice receiving fat transplants contained increased leptin, resistin, and monocyte chemoattractant protein-1 compared with plasma from sham-operated ApoE(-/-) mice. Furthermore, mice transplanted with visceral fat developed significantly more atherosclerosis compared with sham-operated animals, whereas transplants with subcutaneous fat did not affect atherosclerosis despite a similar degree of fat inflammation. Treatment of transplanted ApoE(-/-) mice with pioglitazone decreased macrophage content of the transplanted visceral fat pad and reduced plasma monocyte chemoattractant protein-1. Importantly, pioglitazone also reduced atherosclerosis triggered by inflammatory visceral fat but had no protective effect on atherosclerosis in the absence of the visceral fat transplantation.Our results indicate that visceral adipose-related inflammation accelerates atherosclerosis in mice. Drugs such as thiazolidinediones might be a useful strategy to specifically attenuate the vascular disease induced by visceral inflammatory fat.

Dataset Information

Absence of myeloid COX-2 attenuates acute inflammation but does not influence development of atherosclerosis in apolipoprotein E null mice.

Publications

Absence of myeloid COX-2 attenuates acute inflammation but does not influence development of atherosclerosis in apolipoprotein E null mice.

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