Disruption of p21-activated kinase 1 gene diminishes atherosclerosis in apolipoprotein E-deficient mice.
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ABSTRACT:
SUBMITTER: Singh NK
PROVIDER: S-EPMC4480433 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundAtherosclerosis is a chronic disease that is closely related to inflammation and macrophage apoptosis, which leads to secondary necrosis and proinflammatory responses in advanced lesions. Caspase-activated DNase (CAD) is a double-strand specific endonuclease that leads to the subsequent degradation of chromosome DNA during apoptosis. However, whether CAD is involved in the progression of atherosclerosis remains elusive.Methods and resultsCAD-/-ApoE-/- and ApoE-/- littermates were fed a high-fat diet for 28 weeks to develop atherosclerosis. Human specimens were collected from coronary heart disease (CHD) patients who were not suitable for transplantation. CAD expression was increased in the atheromatous lesions of CHD patients and high-fat diet-treated ApoE-deficient mice. Further investigation demonstrated that CAD deficiency inhibited high-fat diet-induced atherosclerosis, as evidenced by decreased atherosclerotic plaques, inhibited inflammatory response, and macrophage apoptosis, as well as enhanced stability of plaques in CAD-/-ApoE-/- mice compared to the ApoE-/- controls. Bone marrow transplantation verified the effect of CAD on atherosclerosis from macrophages. Mechanically, the decrease in the phosphorylated levels of mitogen-activated protein kinase (MAPK) kinase/extracellular signal-regulated kinase 1 and 2 (MEK-ERK1/2) that resulted from CAD knockout and the activation of nuclear factor kappa B signaling mediated by CAD stimulation that was suppressed by inhibiting ERK1/2 phosphorylation revealed the potential association between the role of CAD in atherosclerosis and the MAPK signaling pathway.ConclusionsIn conclusion, CAD deficiency protects against atherosclerosis through inhibiting inflammation and macrophage apoptosis, which is partially through inactivation of the MEK-ERK1/2 signaling pathway. This finding provides a promising therapeutic target for treating atherosclerosis.
| S-EPMC5210397 | biostudies-literature
Project description:Increasing evidence suggests that adenosine monophosphate-activated protein kinase (AMPK) exerts protective effects for cardiovascular diseases apart from the regulation of energy homeostasis. However, the role of AMPK and its underlying mechanism on macrophage foam cell formation are poorly understood. In this study, we sought to investigate the potential effects of AMPK in modulating cholesterol deposition by using murine macrophage-derived foam cells. Incubation with 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR) markedly attenuated the cholesterol ester accumulation in oxidized low density lipoprotein-loaded macrophages. Notably, AICAR treatment significantly increased ATP-binding cassette transporters G1 (Abcg1) mRNA and protein levels without affecting mRNA and protein expression of ABCA1, scavenger receptors, including scavenger receptor-A, CD36, and scavenger receptor-BI (SR-BI), and cholesterol synthesis-related genes. The up-regulation of Abcg1 by AICAR was independent of the liver X receptor/retinoid X receptor pathway but dependent on ERK activation. AICAR elevates Abcg1 expression through a post-transcriptional mechanism that stabilizes the mRNA. Using a heterologous system with luciferase as a reporter, we further identify the Abcg1 mRNA 3'-UTR responsible for the regulatory effect of AICAR. Prevention of ABCG1 expression by small interfering RNA abolished the AICAR-mediated attenuation on foam cell formation. Furthermore, increased ABCG1 expression and reduced lipid accumulation were demonstrated in AICAR-treated macrophages isolated from apolipoprotein E-deficient mice (apoE(-/-) mice). AICAR treatment also inhibited atherosclerotic plaque formation in apoE(-/-) mice. Our findings elucidate a precise mechanism involved in the prevention of atherogenesis by AMPK.
| S-EPMC2963409 | biostudies-literature
Project description:Background and purposeNumerous in vitro studies have suggested that digoxin suppresses inflammation and alters lipid metabolism. However, the effect of dioxin on atherosclerosis is poorly understood. The present study was conducted to determine whether digoxin affects the development of atherosclerosis in a murine model of atherosclerotic disease.Experimental approachApolipoprotein E-deficient mice maintained on a Western-type diet were administered PBS (control), low-dose digoxin (1 mg · kg(-1) · day(-1)) or high-dose digoxin (2 mg · kg(-1) · day(-1)) via i.p. injection for 12 weeks.Key resultsDigoxin dose-dependently reduced atherosclerotic lesion formation and plasma lipid levels (reductions of 41% in total cholesterol, 54% in triglycerides and 20% in low-density lipoprotein cholesterol in the high-dose digoxin-treated group). Moreover, treatment with digoxin markedly attenuated IL-17A expression and IL-17A-related inflammatory responses and increased the abundance of regulatory T cells (Tregs).Conclusions and implicationsOur data demonstrate that digoxin acts as a specific antagonist of retinoid-related orphan receptor-γ to decrease atherosclerosis by suppressing lipid levels and IL-17A-related inflammatory responses.
| S-EPMC4831306 | biostudies-literature
Project description:Objective- Monocyte-derived foam cells are one of the key players in the formation of atherosclerotic plaques. Adenosine receptors and extracellular adenosine have been demonstrated to modulate foam cell formation. ADK (adenosine kinase) is a major enzyme regulating intracellular adenosine levels, but its functional role in myeloid cells remains poorly understood. To enhance intracellular adenosine levels in myeloid cells, ADK was selectively deleted in novel transgenic mice using Cre-LoxP technology, and foam cell formation and the development of atherosclerotic lesions were determined. Approach and Results- ADK was upregulated in macrophages on ox-LDL (oxidized low-density lipoprotein) treatment in vitro and was highly expressed in foam cells in atherosclerotic plaques. Atherosclerotic mice deficient in ADK in myeloid cells were generated by breeding floxed ADK (ADKF/F) mice with LysM-Cre (myeloid-specific Cre recombinase expressing) mice and ApoE-/- (apolipoprotein E deficient) mice. Mice absent ADK in myeloid cells exhibited much smaller atherosclerotic plaques compared with controls. In vitro assays showed that ADK deletion or inhibition resulted in increased intracellular adenosine and reduced DNA methylation of the ABCG1 (ATP-binding cassette transporter G1) gene. Loss of methylation was associated with ABCG1 upregulation, enhanced cholesterol efflux, and eventually decreased foam cell formation. Conclusions- Augmentation of intracellular adenosine levels through ADK knockout in myeloid cells protects ApoE-/- mice against atherosclerosis by reducing foam cell formation via the epigenetic regulation of cholesterol trafficking. ADK inhibition is a promising approach for the treatment of atherosclerotic diseases.
| S-EPMC6309817 | biostudies-literature
Project description:RATIONALE:Peroxiredoxin 2 (Prdx2), a thiol-specific peroxidase, has been reported to regulate proinflammatory responses, vascular remodeling, and global oxidative stress. OBJECTIVE:Although Prdx2 has been proposed to retard atherosclerosis development, no direct evidence and mechanisms have been reported. METHODS AND RESULTS:We show that Prdx2 is highly expressed in endothelial and immune cells in atherosclerotic lesions and blocked the increase of endogenous H(2)O(2) by atherogenic stimulation. Deficiency of Prdx2 in apolipoprotein E-deficient (ApoE(-/-)) mice accelerated plaque formation with enhanced activation of p65, c-Jun, JNKs, and p38 mitogen-activated protein kinase; and these proatherogenic effects of Prdx2 deficiency were rescued by administration of the antioxidant ebselen. In bone marrow transplantation experiments, we found that Prdx2 has a major role in inhibiting atherogenic responses in both vascular and immune cells. Prdx2 deficiency resulted in increased expression of vascular adhesion molecule-1, intercellular adhesion molecule-1, and monocyte chemotactic protein-1, which led to increased immune cell adhesion and infiltration into the aortic intima. Compared with deficiency of glutathione peroxidase 1 or catalase, Prdx2 deficiency showed a severe predisposition to develop atherosclerosis. CONCLUSIONS:Prdx2 is a specific peroxidase that inhibits atherogenic responses in vascular and inflammatory cells, and specific activation of Prdx2 may be an effective means of antiatherogenic therapy.
| S-EPMC5474748 | biostudies-literature
Project description:The transcription factor Stat3 is an activator of systemic inflammatory genes. Two isoforms of Stat3 are generated by alternative splicing, Stat3? and Stat3?. The ? isoform lacks the transactivation domain but retains other functions, including dimerization and DNA binding. Stat3?-deficient mice exhibit elevated expression of systemic inflammatory genes and are hyperresponsive to lipopolysaccharide, suggesting that Stat3? functions predominantly as a suppressor of systemic inflammation. To test whether Stat3? deficiency would provoke pathologic effects associated with chronic inflammation, we asked whether selective removal of Stat3? would exacerbate the development of atherosclerosis in apolipoprotein E-deficient mice. In apoE(-/-)Stat3?(-/-) mice atherosclerotic plaque formation was significantly enhanced relative to apoE(-/-)Stat3?(+/+) controls. The ability of Stat3? deficiency to promote atherosclerosis was more pronounced in female mice, but could be unmasked in males by feeding a high fat diet. Infiltrating macrophages were not increased in aortas of apoE(-/-)Stat3?(-/-) mice. In contrast, the proportion of pro-inflammatory TH17 cells was significantly elevated in aortic infiltrates from apoE(-/-)Stat3?(-/-) mice, relative to paired apoE(-/-)Stat3?(+/+) littermates. These observations indicate that Stat3? can suppress pathologic sequelae associated with chronic inflammation. Our findings further suggest that in Stat3?-deficient mice the unopposed action of Stat3? may enhance atherogenesis in part by promoting differentiation of TH17 cells.
| S-EPMC3739303 | biostudies-literature
Project description:ObjectiveIL-25 has been implicated in the initiation of type 2 immunity and in the protection against autoimmune inflammatory diseases. Recent studies have identified the novel innate lymphoid type 2 cells (ILC2s) as an IL-25 target cell population. The purpose of this study was to evaluate if IL-25 has any influence on atherosclerosis development in mice.Methods and resultsAdministration of 1 ?g IL-25 per day for one week to atherosclerosis-prone apolipoprotein (apo)E deficient mice, had limited effect on the frequency of T cell populations, but resulted in a large expansion of ILC2s in the spleen. The expansion was accompanied by increased levels of anti-phosphorylcholine (PC) natural IgM antibodies in plasma and elevated levels of IL-5 in plasma and spleen. Transfer of ILC2s to apoE deficient mice elevated the natural antibody-producing B1a cell population in the spleen. Treatment of apoE/Rag-1 deficient mice with IL-25 was also associated with extensive expansion of splenic ILC2s and increased plasma IL-5, suggesting ILC2s to be the source of IL-5. Administration of IL-25 in IL-5 deficient mice resulted in an expanded ILC2 population, but did not stimulate generation of anti-PC IgM, indicating that IL-5 is not required for ILC2 expansion but for the downstream production of natural antibodies. Additionally, administration of 1 ?g IL-25 per day for 4 weeks in apoE deficient mice reduced atherosclerosis in the aorta both during initiation and progression of the disease.ConclusionsThe present findings demonstrate that IL-25 has a protective role in atherosclerosis mediated by innate responses, including ILC2 expansion, increased IL-5 secretion, B1a expansion and natural anti-PC IgM generation, rather than adaptive Th2 responses.
| S-EPMC4309452 | biostudies-literature
Project description:Background and purposeThe liver X receptor (LXR) agonist T317 reduces atherosclerosis but induces fatty liver. Metformin activates energy metabolism by activating AMPKα. In this study, we determined if interactions between metformin and T317 could inhibit atherosclerosis without activation of hepatic lipogenesis.Experimental approachApolipoprotein E-deficient mice were treated with T317, metformin or both agents, in a high-fat diet for 16 weeks. Then, samples of aorta, liver, macrophage and serum were collected to determine atherosclerotic lesions, fatty liver, lipid profiles and expression of related proteins. Techniques used included immunohistochemistry, histology, qRT-PCR and Western blot.Key resultsT317 inhibited en face and aortic root sinus lesions, and the inhibition was further enhanced by addition of metformin. Co-treatment with metformin and T317 increased lesion stability, by increasing collagen content, and reducing necrotic cores and calcification. Formation of macrophages/foam cells and their accumulation in arterial wall were inhibited by the co-treatment, which was accompanied by increased ABCA1/ABCG1 expression, reduced monocyte adhesion and apparent local proliferation of macrophages. Metformin blocked T317-induced fatty liver by inhibiting T317-induced hepatic LXRα nuclear translocation and expression of lipogenic genes and by activating AMPKα. Moreover, co-treatment with T317 and metformin improved triglyceride metabolism by inducing expression of adipose triglyceride lipase, hormone-sensitive lipase, PPARα and carnitine acetyltransferase and by inhibiting acyl-CoA:diacylglycerol acyltransferase 1 expression.Conclusions and implicationsCo-treatment with T317 and metformin inhibited the development of atherosclerosis without activation of lipogenesis, suggesting that combined treatment with T317 and metformin may be a novel approach to inhibition of atherosclerosis.
| S-EPMC5901167 | biostudies-literature
Project description:Atherosclerosis is a serious public health concern. Excessive inflammatory responses of vascular cells are considered a pivotal pathogenesis mechanism underlying atherosclerosis development. It is known that Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signalling plays an important role in atherosclerosis progression. Protein inhibitor of activated STAT3 (PIAS3) is the key negative regulator of JAK/STAT3 signalling. However, its effect on atherogenesis is unknown. Here, we observed that PIAS3 levels are reduced in atherosclerotic lesions and that PIAS3 expression decreases in conjunction with increases in interleukin-6 expression and atherosclerosis severity. Oxidized low-density lipoprotein (ox-LDL), an atherogenic stimulus, reduced PIAS3 expression, an effect that may be attributed to nitric oxide synthesis upregulation. In turn, PIAS3 overexpression effectively suppressed ox-LDL-induced inflammation, lipid accumulation and vascular smooth muscle cell proliferation. These results indicate that PIAS3 is a critical repressor of atherosclerosis progression. The findings of this study have contributed to our understanding on the pathogenesis of atherosclerosis and have provided us with a potential target through which we can inhibit atherosclerosis-related cellular responses.
| S-EPMC5109228 | biostudies-literature
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.
| S-EPMC4007137 | biostudies-literature