Protein-enriched extracts from housefly (Musca domestica) maggots alleviates atherosclerosis in apolipoprotein E-deficient mice by promoting bile acid production and consequent cholesterol consumption

Currently, atherosclerosis control is important to prevent future heart attacks or strokes. Protein-enriched extract (PE) from housefly maggots (Musca domestica) can inhibit the development of atherosclerosis partially through its antioxidant effects. Whether PE exerts other anti-atherosclerosis functions remains unclear. Here, PE was found to simultaneously promote cholesterol metabolism effects in apolipoprotein E knockout (ApoE^-/- ) mice. Bile acid synthesis plays a key role in regulating cholesterol homeostasis in atherosclerosis. Whether PE alleviates atherosclerosis by promoting bile acid production and consequent cholesterol consumption was further explored. First, 8-week-old male ApoE^-/- mice were recruited and fed on a cholesterol-enriched diet. After 8 weeks, these mice were divided into three groups and received gavage administration of PE, simvastatin, and saline for another 8 weeks. Atherosclerosis severity was then assessed. Real-time quantitative polymerase chain reaction and western blot were employed to determine the expression of hepatic ATP-binding cassette transporter A1 (ABCA1), liver X receptor α (LXRα), and peroxisome proliferator-activated receptor-γ (PPAR-γ). Serum levels of high-density lipoprotein-cholesterol (HDL), low-density lipoprotein-cholesterol (LDL), and total cholesterol (TC) were determined by enzyme-linked immunoassay. Results revealed that PE reversed the formation of atherosclerotic lesion; increased the expression of PPAR-γ, LXRα, and ABCA1; increased the amount of bile flow and total bile acid; reduced the serum level of LDL and TC; and increased the level of HDL. In conclusion, enhancement on bile acid production and consequent cholesterol consumption may partially contribute to the anti-atherosclerotic effects of PE. The reversal of PPARγ-LXRα-ABCA1 signaling pathway may be involved in this process.

Anti-atherosclerotic effect of housefly (Musca domestica) maggot-derived protein-enriched extracts by dampened oxidative stress in apolipoprotein E-deficient mice

Despitemany therapeutic advances, atherosclerosis remains the leading cause of morbidity and mortality in developed countries.

Habitual aerobic exercise increases plasma pentraxin 3 levels in middle-aged and elderly women

Chronic inflammation that occurs with aging is one of the risk factors for cardiovascular disease. Regular exercise may prevent cardiovascular morbidity by decreasing chronic systematic inflammation. Additionally, excess inflammation can be reduced by the anti-inflammatory protein pentraxin 3 (PTX3). Thus, both habitual exercise and PTX3 have an anti-inflammatory effect. However, it is unclear whether regular exercise leads to increased plasma PTX3 concentration. In the present study, we investigated the effects of regular aerobic exercise on plasma PTX3 concentration in middle-aged and elderly women. Twenty-two postmenopausal women (60 ± 6 years) were randomly divided evenly into 2 groups (i.e., exercise intervention and control). Subjects in the exercise group completed 2 months of regular aerobic exercise training (walking and cycling, 30-45 min, 3-5 days·week⁻¹). Before and after the intervention, we evaluated plasma PTX3 concentration, peak oxygen uptake, blood chemistry, and arterial distensibility (carotid arterial compliance and β-stiffness) in all participants. There were no significant differences in baseline parameters between the 2 groups. Plasma PTX3 concentration was significantly increased in the exercise group after the intervention (p < 0.05). High-density lipoprotein cholesterol, peak oxygen uptake, and arterial compliance were also significantly increased (p < 0.05), while β-stiffness was markedly decreased (p < 0.01) after the intervention. On the other hand, there was no change in the parameters tested in the control group. This study demonstrates that regular aerobic exercise increases plasma PTX3 concentration with improvement of high-density lipoprotein cholesterol, peak oxygen uptake, and arterial distensibility in postmenopausal women.

Association between the severity of obstructive sleep apnea and the ratio of low-density lipoprotein cholesterol to high-density lipoprotein cholesterol

The positive association between the ratio of serum low-density lipoprotein cholesterol (LDL-C) to serum high-density lipoprotein cholesterol (HDL-C) and cardiovascular events has recently been receiving much attention. However, the association between the severity of obstructive sleep apnea (OSA) and this ratio has not yet been investigated. Accordingly, we sought to clarify this association and the effect of continuous positive airway pressure (CPAP) therapy on the ratio. We performed polysomnography and LDL-C/HDL-C measurements in 215 patients who were suspected of having OSA. Furthermore, LDL-C/HDL-C was again evaluated 6 months after polysomnography in 30 OSA patients for whom CPAP therapy was initiated and continued, and in 11 age- and sex-matched OSA patients for whom the therapy could not be initiated. The LDL-C/HDL-C correlated positively with apnea-hypopnea index (ρ = 0.28, P < .001) and negatively with the lowest arterial oxyhemoglobin saturation (ρ = -0.30, P < .001). Multivariate regression analysis revealed that ln apnea-hypopnea index (or ln lowest arterial oxyhemoglobin saturation) was independently associated with LDL-C/HDL-C. The LDL-C/HDL-C decreased after 6 months in the CPAP group (2.29 ± 0.67 to 2.11 ± 0.74, P = .02), whereas it did not change in the non-CPAP group (2.65 ± 0.82 to 2.62 ± 0.66, P = .81). The severity of OSA was independently associated with LDL-C/HDL-C, and LDL-C/HDL-C was significantly reduced at 6 months after CPAP therapy. These findings suggest that LDL-C/HDL-C increases in proportion to the severity of OSA, which may contribute partly to an increased risk for cardiovascular events in OSA patients.

Vasculoprotective effects of rosiglitazone through modulating renin-angiotensin system in vivo and vitro

Background

The peroxisome proliferator-activated receptor-γ (PPARγ) agonist rosiglitazone has been suggested to exert cardiovascular protection through the improvement of lipid metabolism, anti-inflammation, anti-proliferation etc. However, whether renin-angiotensin system (RAS) is involved in the vascular protective effects of PPARγ agonists is not fully understood. The present study aimed to investigate the effects of the renin-angiotensin system in vascular protection mediated by PPARγ agonists.

Objective

To investigate the actions of the renin-angiotensin system in vascular protection mediated by activation of PPARγ in vivo and in vitro.

Methods

Rats were fed a regular diet (n = 8), a cholesterol-rich diet plus methylthiouracil (80 mg/Kg/day, n = 10), a cholesterol-rich diet plus methylthiouracil and rosiglitazone (4 mg/kg/day, n = 10). The rosiglitazone treatment was started from one month after the start of cholesterol-rich diet plus methylthiouracil, and lasted five months. Cultured vascular smooth muscle cells (VSMCs) were pretreated with 1 μmol/L angiotensin II (ANG II) for 6 h and randomly divided into the control group; the ANG II group (1 μmol/L ANG II); the groups respectively treated with different concentration rosiglitazone (20, 30, 50) μmol/L for 12 h; the groups treated with 30 μmol/L rosiglitazone for (6, 12, 24) h. Morphology changes of the aortic tissues were observed by hematoxylin and eosin stain. The VSMC growth was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. Angiotensin II and expression of angiotensin receptors were determined by radioimmunoassay, reverse transcription polymerase chain reaction (RT-PCR), western blot, and immunohistochemistry.

Results

After 6 months, lipid deposition, VSMC proliferation and migration toward intima were observed in aortic tissues in the rats on a cholesterol-rich diet plus methylthiouracil, while these pathological changes induced by the cholesterol-rich diet were significantly suppressed by rosiglitazone. In addition, VSMC proliferation induced by ANG II was markedly inhibited by rosiglitazone. Rosiglitazone markedly down-regulated expression of angiotensin type 1 receptor (AT₁R) and up-regulated expression of angiotensin type 2 receptor (AT₂R) in the aortic tissues and ANG II-treated VSMCs.

Conclusions

The present study demonstrated that PPARγ agonist rosiglitazone suppressed ANG II-induced VSMC proliferation in vitro and early atherosclerotic formation evoked by cholesterol-rich diet in vivo. These vasculoprotective effects of rosiglitazone were mediated at least partially by reduction in local tissue ANG II concentration, down-regulation of AT₁R expression and up-regulation of AT₂R expression both at the mRNA and protein levels.

Ten-year evaluation of homogeneous low-density lipoprotein cholesterol methods developed by Japanese manufacturers. Application of the Centers for Disease Control and Prevention/Cholesterol Reference Method Laboratory Network lipid standardization protocol

AIM

The risk index for atherosclerotic cardiovascular diseases in the Japanese metabolic syndrome-focused health checkup program was changed from total cholesterol (TC) to low-density lipoprotein cholesterol (LDL-C). We discuss the validity of this change with respect to standardization.

METHODS

The beta-quantification procedure of the Centers for Disease Control and Prevention (CDC) uses the LDL-C reference value as a target. Clinical laboratories and commercial manufacturers use homogeneous LDL-C methods for standardization. (A) For clinical laboratories, LDL-C in 648 samples requested from 108 hospitals was analyzed. (B) Manufacturers participated in the CDC/Cholesterol Reference Method Laboratory Network LDL-C standardization protocol. The standardization was conducted with a performance follow-up for the 10-year period from 1998 to 2008 at 2-year intervals, 6 times.

RESULTS

(A) In clinical laboratories, acceptable LDL-C levels within ±4% of the CDC's criteria remained 70.4%, 456 of 648 subjects. Negative maximum bias deviating from the LDL-C target value was -35.8%, -52.5 mg/dL, and positive maximum bias was +24.5%, +32.3 mg/dL. (B) For manufacturers, the standardization achievement rate of the analytical reagent/instrument/calibrator system in the last four standardizations from 2002 to 2008 remained on average 66.6%, far lower than the level required.

CONCLUSIONS

The standardization achievement rate of homogeneous LDL-C methods was much low-er than that of TC. TC should still be used as a risk index for atherosclerotic cardiovascular diseases. The standardization achievement rate of homogeneous LDL-C should be maintained at 100%, at least using samples with normal lipoprotein profiles. The accuracy and specificity of LDL-C should be further improved before practical and clinical use.

The inhibitory effects of rosiglitazone on cardiac hypertrophy through modulating the renin-angiotensin system in diet-induced hypercholesterolemic rats

Cardiac hypertrophy is not only an adaptational state before heart failure but also is an independent risk factor for ischemia, arrhythmia, and sudden death. However, the direct effects of hypercholesterolemia on the myocardium and mechanisms are not completely understood. It has been demonstrated that peroxisome proliferator-activated receptor-gamma (PPARgamma) ligand agonists attenuate cardiac hypertrophy through anti-inflammatory effects. The present study investigated the effects of PPARgamma agonists on hypercholesterolemia-dependent, renin-angiotensin-system-related cardiac hypertrophy. The findings showed that left ventricular hypertrophy, eminent cardiomyocyte hypertrophy, and lipid deposits in myocardium were observed in the rats fed a cholesterol-rich diet for 6 months, while these characteristic pathological alterations and the increase in angiotensin II (ANG II) level and over-expression of angiotensin II type 1 receptor (AT(1)R) in the left ventricular tissues induced by the cholesterol-rich diet were significantly suppressed to equal extents by rosiglitazone and irbesartan. In contrast, expression of angiotensin II type 2 receptor (AT(2)R) was upregulated by these two drugs. In addition, lipid metabolism was markedly improved. The above findings suggest that the cardioprotection of the PPARgamma agonist against cardiac hypertrophy evoked by hypercholesterolemia in rats is mediated partially by the improvement of lipid profile, the reduction of ANG II level in the local tissue along with the downregulation of AT(1)R expression, and upregulation of AT(2)R expression.