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Intestine-specific DGAT1 deficiency improves atherosclerosis in apolipoprotein E knockout mice by reducing systemic cholesterol burden.

ABSTRACT: BACKGROUND AND AIMS:Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) is the rate-limiting enzyme catalyzing the final step of triglyceride synthesis by esterifying a diglyceride with a fatty acid. We have previously shown that apolipoprotein E-knockout (ApoE-/-) mice lacking Dgat1 have reduced intestinal cholesterol absorption and potentiated macrophage cholesterol efflux, and consequently, exhibit attenuated atherogenesis. However, hematopoietic Dgat1 deficiency lacked beneficial effects on atherosclerosis. Due to our recent results on the critical role of intestinal Dgat1 in murine cholesterol homeostasis, we delineated whether intestinal Dgat1 deficiency regulates atherogenesis in mice. METHODS:We generated intestine-specific Dgat1-/- mice on the ApoE-/- background (iDgat1-/-ApoE-/-) and determined cholesterol homeostasis and atherosclerosis development. RESULTS:When fed a Western-type diet, iDgat1-/-ApoE-/- mice exhibited a substantial decrease in fasting plasma cholesterol content in ApoB-containing lipoproteins. Although lipid absorption was delayed, iDgat1-/-ApoE-/- mice had reduced acute and fractional cholesterol absorption coupled with an elevated fecal caloric loss. In line, increased appearance of i.v. administered [³H]cholesterol in duodena and stool of iDgat1-/-ApoE-/- animals suggested potentiated cholesterol elimination. Atherosclerotic lesions were markedly smaller with beneficial alterations in plaque composition as evidenced by reduced macrophage infiltration and necrotic core size despite unaltered collagen content, indicating improved plaque stability. CONCLUSIONS:Disruption of Dgat1 activity solely in the small intestine of ApoE-/- mice strongly decreased plasma cholesterol levels by abrogating the assimilation of dietary cholesterol, partly by reduced absorption and increased excretion. Consequently, the reduced cholesterol burden significantly attenuated atherogenesis and improved the lesion phenotype in iDgat1-/-ApoE-/- mice.

SUBMITTER: Vujic N

PROVIDER: S-EPMC7116265 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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Intestine-specific DGAT1 deficiency improves atherosclerosis in apolipoprotein E knockout mice by reducing systemic cholesterol burden.

Vujić Nemanja N Korbelius Melanie M Sachdev Vinay V Rainer Silvia S Zimmer Andreas A Huber Anton A Radović Branislav B Kratky Dagmar D

Atherosclerosis 20200810

<h4>Background and aims</h4>Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) is the rate-limiting enzyme catalyzing the final step of triglyceride synthesis by esterifying a diglyceride with a fatty acid. We have previously shown that apolipoprotein E-knockout (ApoE<sup>-/-</sup>) mice lacking Dgat1 have reduced intestinal cholesterol absorption and potentiated macrophage cholesterol efflux, and consequently, exhibit attenuated atherogenesis. However, hematopoietic Dgat1 deficiency lacked benef ...[more]

PMID: 32882484

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Project description:Background and aimsApolipoprotein A-I (ApoA-I), the main component of high-density lipoprotein (HDL), not only promotes reverse cholesterol transport (RCT) in atherosclerosis but also increases insulin secretion in pancreatic β-cells, suggesting that interventions which raise HDL levels may be beneficial in diabetes-associated cardiovascular disease (CVD). Previously, we showed that TNF-related apoptosis-inducing ligand (TRAIL) deletion in Apolipoprotein Eknockout (Apoe-/- ) mice results in diabetes-accelerated atherosclerosis in response to a "Western" diet. Here, we sought to identify whether reconstituted HDL (rHDL) could improve features of diabetes-associated CVD in Trail-/-Apoe-/- mice.Methods and resultsTrail-/-Apoe-/- and Apoe-/- mice on a "Western" diet for 12 weeks received 3 weekly infusions of either PBS (vehicle) or rHDL (containing ApoA-I (20 mg/kg) and 1-palmitoyl-2-linoleoyl phosphatidylcholine). Administration of rHDL reduced total plasma cholesterol, triglyceride, and glucose levels in Trail-/-Apoe-/- but not in Apoe-/- mice, with no change in weight gain observed. rHDL treatment also improved glucose clearance in response to insulin and glucose tolerance tests. Immunohistological analysis of pancreata revealed increased insulin expression/production and a reduction in macrophage infiltration in mice with TRAIL deletion. Furthermore, atherosclerotic plaque size in Trail-/-Apoe-/- mice was significantly reduced associating with increased expression of the M2 macrophage marker CD206, suggesting HDL's involvement in the polarization of macrophages. rHDL also increased vascular mRNA expression of RCT transporters, ABCA1 and ABCG1, in Trail-/-Apoe-/- but not in Apoe-/- mice. Conclusions. rHDL improves features of diabetes-associated atherosclerosis in mice. These findings support the therapeutic potential of rHDL in the treatment of atherosclerosis and associated diabetic complications. More studies are warranted to understand rHDL's mechanism of action.

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Intestine-specific DGAT1 deficiency improves atherosclerosis in apolipoprotein E knockout mice by reducing systemic cholesterol burden.

Publications

Intestine-specific DGAT1 deficiency improves atherosclerosis in apolipoprotein E knockout mice by reducing systemic cholesterol burden.

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