Matrix metalloproteinases and atherogenesis in dependence of age

Association among VKORC1 rs9923231, CYP4F2 rs2108622, GGCX rs11676382 polymorphisms and acute ischemic stroke

Acute ischemic stroke is a major cause of morbidity and mortality worldwide, and genetic factors play a role in the risk of stroke. Single nucleotide polymorphisms (SNPs) in the VKORC1, CYP4F2, and GGCX genes have been linked to clinical outcomes, such as bleeding and cardiovascular diseases. This study aimed to investigate the association between specific polymorphisms in these genes and the risk of developing the first episode of acute ischemic stroke in patients without a known embolic source. This retrospective, cross-sectional, observational, analytical, case-control study included adult patients diagnosed with acute ischemic stroke. The SNPs in VKORC1 rs9923231, CYP4F2 rs2108622, GGCX rs11676382 genes were genotyped and analyzed together with the demographic and clinical factors of the 2 groups of patients. The presence of SNPs in VKORC1 or CYP4F2 genes significantly increased the risk of ischemic stroke in the context of smoking, arterial hypertension, and carotid plaque burden. The multivariate logistic model revealed that smoking (odds ratio [OR] = 3.920; P < .001), the presence of carotid plaques (OR = 2.661; P < .001) and low-density lipoprotein cholesterol values >77 mg/dL (OR = 2.574; P < .001) were independently associated with stroke. Polymorphisms in the VKORC1 and CYP4F2 genes may increase the risk of ischemic stroke in patients without a determined embolic source. Smoking, the presence of carotid plaques, and high low-density lipoprotein cholesterol levels were reconfirmed as important factors associated with ischemic stroke.

Effect of microRNA-133a-3p/matrix metalloproteinase-9 axis on the growth of atherosclerotic vascular smooth muscle cells

Atherosclerosis (AS) is the leading cause of cardiovascular disease and poses a threat to human health. MicroRNAs (miRNAs/miRs) are a group of endogenous small non-coding RNAs that have been identified to serve important roles in AS. However, the expression and role of miR-133a-3p in AS remains unclear. The aim of the present study was to investigate miR-133a-3p in AS and to determine its underlying mechanism. The level of miR-133a-3p expression in the blood and vascular plaque tissue of patients with AS was detected via reverse transcription-quantitative PCR (RT-qPCR). The role of miR-133a-3p in human vascular smooth muscle cells (hVSMCs) was investigated, following upregulation and downregulation of this miR in hVSMCs. Cell proliferation and apoptosis were determined using a Cell Counting kit-8 assay and flow cytometry, respectively. The results demonstrated the downregulation of miR-133a-3p in the blood and vascular plaque tissue of patients with AS. Matrix metallopeptidase-9 (MMP-9) was revealed to be a direct target gene of miR-133a-3p, which was upregulated in the blood and vascular plaque tissue of patients with AS. Furthermore, MMP-9 was determined to be negatively regulated by miR-133a-3p in hVSMCs. In addition, significant inhibition of hVSMC proliferation and induction of cell apoptosis were observed following MMP-9 downregulation and following transfection with the miR-133a-3p mimic. The effects of the miR-133a-3p mimic on hVSMC proliferation and apoptosis were reversed by MMP-9 over-expression. Overall, the results indicated that miR-133a-3p was downregulated in AS, which results in the inhibition of hVSMC proliferation and the induction of cell apoptosis via MMP-9. miR-133a-3p may therefore be a promising therapeutic target for the treatment of AS.

MicroRNA-133b regulates the growth and migration of vascular smooth muscle cells by targeting matrix metallopeptidase 9

Atherosclerosis is a systemic disease affecting the whole arterial tree of the human body, and it is the leading cause of cardiovascular diseases.Vascular smooth muscle cells (VSMCs) have been identified to play a key role in the development of atherosclerosis. MicroRNAs (miRNAs) are a group of endogenous small non-coding RNAs, and they play a critical role in many biological processes including regulating cell proliferation, migration and apoptosis. However, till now, the expression and role of miR-133b in atherosclerosis remain largely unknown. Therefore, our purpose was to investigate the expression and role of miR-133b in atherosclerosis and to explore the underlying mechanism. The results showed that miR-133b was down-regulated in the blood and vascular plaque tissues of rabbits with atherosclerosis. Matrix metallopeptidase 9 (MMP-9) was a direct target of miR-133b. In addition, our data indicated that miR-133b mimic could significantly inhibit rVSMC cell proliferation activity, migration ability and induce cell apoptosis compared with the control group, and all these effects were reversed by MMP-9-plasmid. Taken together, these findings highlight an important role for miR-133b/MMP-9 axis in atherosclerosis. And miR-133b might be a valuable clinical marker and therapeutic target for atherosclerosis.

Exposure to endosulfan increases endothelial permeability by transcellular and paracellular pathways in relation to cardiovascular diseases

Exposure to environmental pollutants results in out-of-balance of vascular homeostasis. Endothelial dysfunction leads to a disruption of the endothelial permeability characteristics, associated with cardiovascular diseases. We previously reported that endosulfan could cause endothelial dysfunction, but the role of endosulfan in permeability of endothelial cells has been unexplored. To elucidate molecular mechanism of endosulfan-induced changes in endothelial permeability, human umbilical vein endothelial cells (HUVECs) were exposed to endosulfan, followed by endothelial permeability analysis. The results showed that permeability of HUVECs was enhanced at 48 h after exposure to endosulfan in a dose-dependent manner. Immunofluorescence analysis demonstrated the disruptions of actin cytoskeleton and focal adhesion in endosulfan-exposed cells. Endosulfan activated MMP3/LAMC1/FAK signaling pathway, and downregulated ROCK and PXN in transcellular pathway. Endosulfan affected adherens junctions via E-cadherin and β-catenin, and impaired gap junctions through downregulation of Cx43 in paracellular pathway. We predicted four closely related human cardiovascular diseases in Nextbio, including shock, coronary arteriosclerosis, disorder of cardiac function and hypertensive disorder in relation to endosulfan exposure. Some genes such as ROCK2 and PXN were predicted to be key genes in these diseases. These findings suggest that endosulfan increased endothelial permeability by paracellular and transcellular pathways, implicating the potential correlation between endosulfan and cardiovascular diseases.

TLR4 antagonist attenuates atherogenesis in LDL receptor-deficient mice with diet-induced type 2 diabetes

Although a large number of studies have well documented a key role of toll-like receptor (TLR)4 in atherosclerosis, it remains undetermined if TLR4 antagonist attenuates atherogenesis in mouse model for type 2 diabetes. In this study, we induced type 2 diabetes in low-density lipoprotein receptor-deficient (LDLR(-/-)) mice by high-fat diet (HFD). At 8 weeks old, 20 mice were fed HFD and 20 mice fed regular chow (RC) for 24 weeks. In the last 10 weeks, half HFD-fed mice and half RC-fed mice were treated with Rhodobacter sphaeroides lipopolysaccharide (Rs-LPS), an established TLR4 antagonist. After the treatment, atherosclerotic lesions in aortas were analyzed. Results showed that the HFD significantly increased bodyweight, glucose, lipids including total cholesterol, triglycerides and free fatty acids, and insulin resistance, indicating that the HFD induced type 2 diabetes in LDLR(-/-) mice. Results also showed that Rs-LPS had no effect on HFD-increased metabolic parameters in both nondiabetic and diabetic mice. Lipid staining of aortas and histological analysis of cross-sections of aortic roots showed that diabetes increased atherosclerotic lesions, but Rs-LPS attenuated atherogenesis in diabetic mice. Furthermore, immunohistochemical studies showed that Rs-LPS reduced infiltration of monocytes/macrophages and expression of interleukin (IL)-6 and matrix metalloproteinase-9 in atherosclerotic lesions of diabetic mice. Finally, the antagonistic effect of Rs-LPS on TLR4 was demonstrated by our in vitro studies showing that Rs-LPS inhibited IL-6 secretion from macrophages and endothelial cells stimulated by LPS or LPS plus saturated fatty acid palmitate. Taken together, our study demonstrated that TLR4 antagonist was capable of attenuating vascular inflammation and atherogenesis in mice with HFD-induced type 2 diabetes.

Vascular smooth muscle cell in atherosclerosis

Vascular smooth muscle cells (VSMCs) exhibit phenotypic and functional plasticity in order to respond to vascular injury. In case of the vessel damage, VSMCs are able to switch from the quiescent 'contractile' phenotype to the 'proinflammatory' phenotype. This change is accompanied by decrease in expression of smooth muscle (SM)-specific markers responsible for SM contraction and production of proinflammatory mediators that modulate induction of proliferation and chemotaxis. Indeed, activated VSMCs could efficiently proliferate and migrate contributing to the vascular wall repair. However, in chronic inflammation that occurs in atherosclerosis, arterial VSMCs become aberrantly regulated and this leads to increased VSMC dedifferentiation and extracellular matrix formation in plaque areas. Proatherosclerotic switch in VSMC phenotype is a complex and multistep mechanism that may be induced by a variety of proinflammatory stimuli and hemodynamic alterations. Disturbances in hemodynamic forces could initiate the proinflammatory switch in VSMC phenotype even in pre-clinical stages of atherosclerosis. Proinflammatory signals play a crucial role in further dedifferentiation of VSMCs in affected vessels and propagation of pathological vascular remodelling.

Menopausal hormone treatment cardiovascular disease: another look at an unresolved conundrum

Cardiovascular disease (CVD) is the most common cause of death in women. Before the Women's Health Initiative (WHI) hormone trials, evidence favored the concept that menopausal hormone treatment (MHT) protects against CVD. WHI studies failed to demonstrate CVD benefit, with worse net outcomes for MHT versus placebo in the population studied. We review evidence regarding the relationship between MHT and CVD with consideration of mechanisms and risk factors for atherogenesis and cardiac events, results of observational case-control and cohort studies, and outcomes of randomized trials. Estrogen effects on CVD risk factors favor delay or amelioration of atherosclerotic plaque development but may increase risk of acute events when at-risk plaque is present. Long-term observational studies have shown ∼40% reductions in risk of myocardial infarction and all-cause mortality. Analyses of data from randomized control trials other than the WHI show a ∼30% cardioprotective effect in recently menopausal women. Review of the literature as well as WHI data suggests that younger and/or more recently menopausal women may have a better risk-benefit ratio than older or remotely menopausal women and that CVD protection may only occur after >5 years; WHI women averaged 63 years of age (12 years postmenopausal) and few were studied for >6 years. Thus, a beneficial effect of long-term MHT on CVD and mortality is still an open question and is likely to remain controversial for the foreseeable future.

A functional polymorphism at miR-491-5p binding site in the 3'-UTR of MMP-9 gene confers increased risk for atherosclerotic cerebral infarction in a Chinese population

BACKGROUND

and purpose: Matrix metalloproteinases 9 (MMP-9) has been reported to play a critical role in the pathophysiology of atherosclerotic cerebral infarction (ACI). Here we assessed association of MMP-9 polymorphisms with ACI susceptibility and the function of SNPs through microRNA mediated regulation.

METHODS

Genotyping was performed using MALDI-TOF mass spectrometry. Reporter gene plasmids with the MMP-9 3'UTR carrying either the mutant or the wild-type MMP-9 allele were constructed. Also, we constructed pcDNA-3.1-miR-491-5p recombinant plasmid, which transiently co-transfected human umbilical vein endothelial cells (HUVEC) with the reporter plasmids. Reporter plasmids, miR-491-5p mimics and inhibitor were transfected into HUVE cells line by lipofectamine. MMP-9 mRNA expression in HUVEC was detected by RT-PCR and protein level by ELISA.

RESULTS

The rs1802908 and rs2664517 polymorphisms were not observed in all subjects from Hunan Han Chinese. No significant difference in genotype distribution of rs20544 and rs9509 between cases and controls were observed (p＞0.05). The rs1056628CC genotype had a significantly increased risk for ACI as compared with carries of the rs1056628 A allele (total χ(2) = 12.041, P = 0.002). Reporter gene assay revealed that the rs1056628 A allele showed lower reporter activity than the rs1056628C allele. Hsa-miR-491-5p had effect on modulation of MMP-9 gene in vitro. The rs1056628 A→C variant in the 3'-UTR of the MMP-9 increased MMP-9 protein expression in cultured HUVECs.

CONCLUSIONS

Our data suggested that the rs1056629A→C variation contributes to an increased risk of ACI by increasing MMP-9 expression through affecting binding of miR-491 to the polymorphic site in the 3'-UTR of MMP-9.

[Update on diabetic macroangiopathy]

Current findings from the literature on the multifactorial genesis of macroangiopathy of diabetes mellitus (DM) were compiled using the PubMed database. The primary aim was to find an explanation for the morphological, immunohistochemical and molecular characteristics of this form of atherosclerosis. The roles of advanced glycation end products (AGE), defective signal transduction and imbalance of matrix metalloproteinases in the increased progression of atherosclerosis in coronary and cerebral arteries as well as peripheral vascular disease are discussed. The restricted formation of collateral arteries (arteriogenesis) in diabetic patients with postischemic lesions is also a focus of attention. The increased level of prothrombotic factors and the role of diabetic neuropathy in DM are also taken into account. Therapeutic influences of AGE-RAGE (receptor of AGE) interactions on the vascular wall and the effects of endothelial progenitor cells in the repair of diabetic vascular lesions are additionally highlighted.

Low-dose ultraviolet radiation selectively degrades chromophore-rich extracellular matrix components

Photoageing of human skin due to chronic exposure to ultraviolet radiation (UVR) is characterized histologically by extensive remodelling of the dermal elastic fibre system. Whilst enzymatic pathways are thought to play a major role in mediating extracellular matrix (ECM) degeneration in UV-exposed skin, the substrate specificity of UVR-up-regulated and activated matrix metalloproteinases (MMPs) is low. It is unclear, therefore, how such cell-mediated mechanisms alone could be responsible for the reported selective degradation of elastic fibre components such as fibrillin-1 and fibulin-5 during the early stages of photoageing. Here we use atomic force microscopy (AFM) and scanning transmission electron microscopy (STEM) to demonstrate that physiologically attainable doses (20-100 mJ/cm(2)) of direct UV-B radiation can induce profound, dose-dependent, changes in the structure of, and mass distribution within, isolated fibrillin microfibrils. Furthermore, using reducing and native PAGE in combination with AFM, we show that, whilst exposure to low-dose UV-B radiation significantly alters the macromolecular and quaternary structures of both UV chromophore (Cys, His, Phe, Trp and Tyr)-rich fibrillin microfibrils (fibrillin-1, 21.0%) and fibronectin dimers (fibronectin, 12.9%), similar doses have no detectable effect on UV chromophore-poor type I collagen monomers (2.2%). Analysis of the published primary amino acid sequences of 49 dermal ECM components demonstrates that most elastic fibre-associated proteins, but crucially neither elastin nor members of the collagen family, are rich in UV chromophores. We suggest, therefore, that the amino acid composition of elastic fibre-associated proteins [including the fibrillins, fibulins, latent TGFbeta binding proteins (LTBPs) and the lysyl oxidase family of enzymes (LOK/LOXLs)] may predispose them to direct degradation by UVR. As a consequence, this selective acellular photochemical pathway may play an important role in initiating and/or exacerbating cell-mediated ECM remodelling in UVR-exposed skin.

Hyperbaric oxygen effect on MMP-9 after a vascular insult

Matrix metalloproteinease-9 (MMP-9) is involved in a host of processes. Many of its processes are physiologically beneficial as well as detrimental. The over-expression of this enzyme has been implicated as a contributory factor to some of the sequalae associated with cerebral ischemia, cell death, non-healing wounds, traumatic brain injury, aneurysms, and plaque instability in atherosclerosis. Several studies have examined the effect of hyperbaric oxygen (HBO) on MMP-9 expression. Because this proteinase is involved in both chronic and acute pathology, we wanted to investigate an acute expression model and see if, and how quickly, its expression would respond to HBO therapy. Our patient was scheduled to have elective surgery with an overnight stay followed by a series of HBO exposures. The patient served as her own control. An MMP-9 and urine pH was obtained prior to surgery to establish a baseline. On days 1, 3, and 4 post-op, samples were obtained before and after hyperbaric exposure. The patient was exposed to 100% O2 at 2.5 ATA for 60 min during each treatment for 5 days. The patient's MMP-9 values were dramatically elevated after surgery as compared to the baseline readings. The percentage increase from baseline was 400%. Our patient showed a significant reduction in MMP-9 expression after each hyperbaric exposure with the greatest decrease seen on post-op day 1 and subsequent exposures showing slightly less expression. Reduction in MMP-9 expression ranged from 46% on day 1 to 30% on post-op day 4. This case study suggests that if done relatively soon after a vascular or tissue insult, HBO can reduce MMP-9 expression. Chronic vascular pathologies, such as atherosclerotic plaque and aneurysms where over-expression of MMP-9 may result in acute coronary syndrome (ACS) or cerebral vascular accidents (CVAs), may be mitigated by a series of HBO treatments that reduce MMP-9 expression. Causality and/or contributory effects of MMP-9 expression in both pathologic and physiologic processes needs to be further elucidated. The understanding of how HBO therapy modulates these may provide an additional insight into mechanisms and future potential therapies for pathologic conditions such as those described above.

Ovariectomy in aged versus young rats augments matrix metalloproteinase-mediated vasoconstriction in mesenteric arteries

OBJECTIVE

Ovarian deficiency is known to undermine vasoprotective mechanisms and accelerate cardiovascular disease in postmenopausal women. In a rat model of menopause (aged ovariectomized [Ovx] rats), we recently revealed a vasoconstrictor pathway mediated by matrix metalloproteinases (MMPs) via cleavage of big endothelin-1 (ET-1). However, the specific impact of aging and/or Ovx on this pathway remains unknown. We hypothesized that aging exacerbates MMP-mediated vasoconstriction in an ovary-deficient state.

METHODS

Young and aged female Sprague-Dawley rats, either intact or Ovx, were assessed for MMP-dependent vasoreactivity. Dose responses to big ET-1 in the absence or presence of an MMP inhibitor (GM6001) were tested on small mesenteric arteries using a pressure myograph system. MMP levels in the vascular tissue were measured by gelatin zymography.

RESULTS

Both young Ovx and aged Ovx animals demonstrated a similar increase in the vasoconstriction to big ET-1 compared with the age-matched intact groups. MMP inhibition attenuated big ET-1 response in both Ovx groups and aged controls, but this effect was more pronounced in aged Ovx arteries (area under the curve reduction, 3.8 +/- 0.6 units in aged Ovx rats vs 1.5 +/- 0.5 units in young Ovx rats or 1.8 +/- 0.6 units in aged intact rats; P < 0.05). MMP-2 activity in the vascular tissue increased with age and was further augmented by Ovx.

CONCLUSIONS

Regardless of age, ovarian loss increases vascular reactivity to big ET-1, which is mediated, in part, by MMP. Superimposed with advancing age, ovarian deficiency further increases the proconstrictor role of MMP, which corresponds with higher MMP-2 levels in the aging vessel wall. MMP-mediated vasoconstriction may be a mechanism contributing to vascular dysfunction in postmenopausal women.

Inflammation-induced atherosclerosis as a target for prevention of cardiovascular diseases from early life

Atherogenesis starts from the fetal life, and its natural course consists of interrelations between traditional risk factors and inflammatory, immune, and endothelial biomarkers. Even the early-stages of atherosclerotic lesions, i.e. fatty streaks present the features of chronic inflammation. Markers of inflammation are associated with insulin resistance and major atherosclerosis risk factors. Several studies have confirmed a relationship between surrogate markers of future cardiovascular disease with childhood obesity, notably abdominal obesity, as well as with the degree of obesity. Moreover, functional and structural changes are documented in arteries of children with a familial predisposition to atherosclerotic diseases; these changes are associated with clusters of inflammatory factors and markers of oxidation. In addition to the development of atheromatous plaques, inflammation also plays an essential role in the destabilization of artery plaques, and in turn in the occurrence of acute thrombo-embolic disorders. Markers of inflammation can provide predictive clinical information about outcomes of patients with acute coronary syndromes, independent of the extent of myocardial damage. Moreover, serum levels of the inflammatory markers might add prognostic information provided by traditional risk factors. Platelets have an important role in vascular inflammation and atherosclerosis and in the formation of mural thrombi. As lifestyle modification trials have been successful in decreasing endothelial dysfunction and the level of markers of inflammation among children and adolescents, it is suggested that in addition to expanding pharmacological therapies considered for secondary prevention of atherosclerotic diseases aiming to control the inflammatory process, the importance of primordial/primary prevention of atherosclerosis should be underscored.

Evaluation of serum matrix metalloproteinases as biomarkers for detection of neurological symptoms in carotid artery disease

OBJECTIVE

Relevant soluble matrix metalloproteinases (MMPs), their inhibitors, tissue inhibitor of metalloproteinases (TIMPs), and serological factors were analyzed as possible biomarkers for neurological symptoms in patients with carotid artery stenosis.

METHODS AND RESULTS

Asymptomatic (n = 76) and symptomatic (n = 69) patients were evaluated. Serum levels of collagenases (MMP-1, -8), gelatinases (MMP-2, -9), stromelysin (MMP-3), matrilysin (MMP-7), and TIMP-1, -2 were determined by enzyme-linked immunosorbant assay (ELISA). Furthermore, fibrinogen, C-reactive protein (CRP), leukocytes, and further serological parameters were measured. Circulating MMP-7, -8, -9, and TIMP-1 were significantly enhanced in symptomatic individuals with P < .001 for MMP-7 and P < .05 for MMP-8, -9, and TIMP-1. Significant correlations were found between various MMPs with highest correlation coefficient of r = .749 between MMP-8 and -9. In addition, MMP-1, -3, -7, -9 correlated significantly with leukocytes, MMP-1, and TIMP-1 with thrombocytes, MMP-8 with fibrinogen, and MMP-7 with creatinine. Combination of more than one biomarker led to significantly enhanced positive predictive value (PPV) for neurological symptom compared to single MMP (MMP-7 + MMP-9: PPV = 73.1%, MMP-7 + MMP-8 + MMP-9: PPV = 73.8% vs. PPV = 62.5%; P < .001).

CONCLUSIONS

Thus, using appropriate analytical approaches, we showed for the first time the possibility to use set of relevant biomarkers as predictors of neurological symptoms. Such biomarkers together with current diagnostic techniques may further contribute to recognize vulnerable lesions to define patients at risk.

Smooth muscle apoptosis and vascular remodeling

PURPOSE OF REVIEW

The present review is to summarize recent advances in molecular mechanisms that regulate vascular smooth muscle cell apoptosis during vascular remodeling. In normal blood vessels apoptosis counteracts cell division, whereas apoptosis is especially crucial for regulating vascular remodeling during cardiovascular diseases.

RECENT FINDINGS

Recent results have expanded our knowledge regarding the signaling pathways and molecules that regulate vascular smooth muscle cell death in postnatal vascular remodeling. Compelling data from genetic disorders associated with vascular smooth muscle cell loss (e.g., Hutchinson-Gilford progeria syndrome) and experimental studies suggest that changes in hemodynamic and mechanical forces are major modulators for vascular smooth muscle cell apoptosis. Furthermore, understanding the therapeutic effects of antihypertensive drugs related to apoptosis may identify pathways that can improve outcomes independent of the blood pressure fall.

SUMMARY

Regulation of vascular smooth muscle cell apoptosis is a potential target to modify pathological vascular remodeling and new drugs development.

LOX-1 deletion decreases collagen accumulation in atherosclerotic plaque in low-density lipoprotein receptor knockout mice fed a high-cholesterol diet

AIMS

Collagen, as a component of the extracellular matrix, has been linked to atherosclerotic plaque formation and stability. Activation of LOX-1, a lectin-like oxidized low-density lipoprotein (LDL) receptor-1, exerts a significant role in collagen formation. We examine the hypothesis that LOX-1 deletion may inhibit collagen accumulation in atherosclerotic arteries in LDL receptor (LDLR) knockout (KO) mice.

METHODS AND RESULTS

We generated LOX-1 KO and LOX-1/LDLR double KO mice on a C57BL/6 (wild-type mice) background and fed a 4% cholesterol/10% cocoa butter diet for 18 weeks. Vessel wall collagen accumulation was increased in association with atherogenesis in the LDLR KO mice (P < 0.01 vs. wild-type mice), but much less so in the double KO mice (P < 0.01 vs. LDLR KO mice). Collagen accumulation data were corroborated with pro-collagen I measurements. Expression/activity of osteopontin, fibronectin, and matrix metalloproteinases (MMP-2 and MMP-9) was also increased in the LDLR KO mice (P < 0.01 vs. wild-type mice), but not in the mice with LOX-1 deletion (P < 0.01 vs. LDLR KO mice). The expression of NADPH oxidase (p47(phox), p22(phox), gp91(phox), and Nox-4 subunits) and nitrotyrosine was increased in the LDLR KO mice (P < 0.01 vs. wild-type mice) and not in mice with LOX-1 deletion (P < 0.01 vs. LDLR KO mice). Phosphorylation of Akt-1 and endothelial nitric oxide synthase and expression of haem-oxygenase-1 were found to be reduced in the LDLR KO mice (P < 0.01 vs. wild-type mice), but not in the mice with LOX-1 deletion (P < 0.01 vs. LDLR KO mice).

CONCLUSION

LOX-1 deletion reduces enhanced collagen deposition and MMP expression in atherosclerotic regions via inhibition of pro-oxidant signals.

Over-expression of angiotensin II type 2 receptor (agtr2) decreases collagen accumulation in atherosclerotic plaque

Angiotensin (Ang) II, via type 1 receptor activation, exerts a significant role in atherogenesis and collagen synthesis. To test the hypothesis that Ang II type 2 receptor (AT2R) upregulation delivered with adeno-associated virus type 2 (AAV/AT2R) would inhibit collagen synthesis in atherosclerotic arteries, LDLR knockout mice were injected with AAV/AT2R and fed 4% cholesterol diet for 18 weeks. LDLR knockout mice treated with saline or AAV/Neo exhibited extensive vessel wall collagen accumulation, which was reduced by about 50% with AT2R over-expression. AT2R upregulation completely blocked the alterations in the expression of procollagen-I, osteopontin, fibronectin, CD68, and matrix metalloproteinases (MMP-2 and MMP-9), as well as phosphorylation of p38 and p44/42 MAPKs. Activity of superoxide dismutase was reduced in the LDLR KO mice and it increased with AT2R upregulation. This study demonstrates that AT2R over-expression reduces enhanced collagen accumulation, MMP expression and activity in atherosclerotic regions via inhibition of pro-oxidant signals.