Beneficial actions of statins in the reduction of atrial fibrillation and stabilization and regression of coronary plaques: but how and why?

The Impact of Simvastatin on Lipidomic Markers of Cardiovascular Risk in Human Liver Cells Is Secondary to the Modulation of Intracellular Cholesterol

Statins are the first-line lipid-lowering therapy for reducing cardiovascular disease (CVD) risk. A plasma lipid ratio of two phospholipids, PI(36:2) and PC(18:0_20:4), was previously identified to explain 58% of the relative CVD risk reduction associated with pravastatin, independent of a change in low-density lipoprotein-cholesterol. This ratio may be a potential biomarker for the treatment effect of statins; however, the underlying mechanisms linking this ratio to CVD risk remain unclear. In this study, we investigated the effect of altered cholesterol conditions on the lipidome of cultured human liver cells (Hep3B). Hep3B cells were treated with simvastatin (5 μM), cyclodextrin (20 mg/mL) or cholesterol-loaded cyclodextrin (20 mg/mL) for 48 h and their lipidomes were examined. Induction of a low-cholesterol environment via simvastatin or cyclodextrin was associated with elevated levels of lipids containing arachidonic acid and decreases in phosphatidylinositol species and the PI(36:2)/PC(18:0_20:4) ratio. Conversely, increasing cholesterol levels via cholesterol-loaded cyclodextrin resulted in reciprocal regulation of these lipid parameters. Expression of genes involved in cholesterol and fatty acid synthesis supported the lipidomics data. These findings demonstrate that the PI(36:2)/PC(18:0_20:4) ratio responds to changes in intracellular cholesterol abundance per se, likely through a flux of the n-6 fatty acid pathway and altered phosphatidylinositol synthesis. These findings support this ratio as a potential marker for CVD risk reduction and may be useful in monitoring treatment response.

Statin treatment alters serum n-3 to n-6 polyunsaturated fatty acids ratio in patients with dyslipidemia

Background

The effects of statins on serum n-3 to n-6 polyunsaturated fatty acids (PUFAs) levels have not been fully evaluated. We examined the effects of two types of statins (rosuvastatin and pitavastatin) on serum PUFAs levels and their ratios in patients with dyslipidemia.

Findings

A total of 46 patients who were not receiving lipid-lowering therapy were randomly assigned to receive either 2.5 mg/day of rosuvastatin or 2 mg/day of pitavastatin. Serum PUFAs levels were measured at baseline, at 4 weeks, and at 12 weeks. Rosuvastatin was used to treat 23 patients, and the remaining 23 patients were treated using pitavastatin. Serum docosahexaenoic acid (DHA) levels decreased significantly at 12 weeks in both groups (rosuvastatin: from 169.6 to 136.3 μg/mL, p = 0.006; pitavastatin: from 188.6 to 153.9 μg/mL, p = 0.03). However, serum levels of eicosapentaenoic acid (EPA) and arachidonic acid (AA) did not change. In addition, the EPA/AA ratio did not change, whereas the DHA/AA ratio decreased significantly at 12 weeks in both groups (rosuvastatin: from 0.99 to 0.80, p = 0.01; pitavastatin: from 1.14 to 0.91, p = 0.003). No adverse events were observed during the study period.

Conclusions

In this small, open-label, pilot study, rosuvastatin and pitavastatin decreased serum DHA levels and the DHA/AA ratio in patients with dyslipidemia.

Effects of Statins on Serum n-3 to n-6 Polyunsaturated Fatty Acid Ratios in Patients With Coronary Artery Disease

Background:

A low n-3 to n-6 polyunsaturated fatty acids (PUFAs) ratio is reported to be associated with cardiovascular events. However, the effects of statins on this ratio have not been fully examined.

Methods:

A total of 101 patients with coronary artery disease, who were not receiving lipid-lowering therapy were randomly assigned to receive either 4 mg/day of pitavastatin or 20 mg/day of pravastatin. Serum PUFA levels were measured at baseline and 8 months after treatment with statins.

Results:

Pitavastatin was used to treat 51 patients and the remaining 50 patients were treated using pravastatin. A significant positive correlation was observed between the percent change in low-density lipoprotein cholesterol and that in dihomogamma-linolenic acid ( r = .376, P = .007), arachidonic acid (AA; r = .316, P = .02), eicosapentaenoic acid (EPA; r = .408, P = .003), or docosahexaenoic acid (DHA; r = .270, P = .056) in the pitavastatin group. However, these correlations were not observed in the pravastatin group. The DHA/AA ratio decreased significantly in the pitavastatin group only (from 0.96 to 0.83, P = .0002) and the DHA/AA ratio was significantly lower in the pitavastatin group at 8 months (0.83 vs 0.96, P = .03). The EPA/AA ratio did not show significant changes in either group.

Conclusions:

Pitavastatin decreased the serum DHA/AA ratio, whereas pravastatin had no effect on this ratio. Neither pitavastatin nor pravastatin had an effect on the serum EPA/AA ratio in patients with coronary artery disease.

Effects of lipid-lowering therapy with strong statin on serum polyunsaturated fatty acid levels in patients with coronary artery disease

Residual risk of cardiovascular events after treatment with stain might be explained in part because patients have low levels of n-3 polyunsaturated fatty acids (PUFA). We examined how lipid-lowering therapy with strong statin affected serum PUFA levels in patients with coronary artery disease. The study population consisted of 46 patients with coronary artery disease whose low-density lipoprotein (LDL) cholesterol was more than 100 mg/dl. Lipid-lowering therapy was performed with a strong statin including atorvastatin (n = 22), rosuvastatin (n = 9) or pitavastatin (n = 15). Serum PUFA levels were determined by gas chromatography. The treatment with strong statin decreased the sum of dihomo-γ-linolenic acid (DGLA) and arachidonic acid (AA) levels (195 ± 41 to 184 ± 44 μg/ml, P < 0.05) as well as the sum of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels (233 ± 71 to 200 ± 72 μg/ml, P < 0.001). These effects of strong statin resulted in a significant decrease in ratio of the sum of EPA and DHA levels to the sum of DGLA and AA levels (1.20 ± 0.27 to 1.10 ± 0.35, P < 0.05). The percent decrease in the LDL cholesterol level correlated significantly with that in the sum of EPA and DHA levels (r = 0.38, P < 0.01). In conclusion, our results showed that lipid-lowering therapy with strong statin mainly reduced n-3 PUFAs in proportion to the decrease in the LDL cholesterol level in patients with coronary artery disease.

Can vagus nerve stimulation halt or ameliorate rheumatoid arthritis and lupus?

Acetylcholine, the principal vagus neurotransmitter, inhibits inflammation by suppressing the production of pro-inflammatory cytokines through a mechanism dependent on the α7 nicotinic acetylcholine receptor subunit (alpha7nAChR) that explains why vagus nerve stimulation is anti-inflammatory in nature. Strong expression of alpha7nAChR in the synovium of rheumatoid arthritis and psoriatic arthritis patients was detected. Peripheral macrophages and synovial fibroblasts respond in vitro to specific alpha7nAChR cholinergic stimulation with potent inhibition of proinflammatory cytokines. Fibroblasts balance inflammatory mechanisms and arthritis development through feedback cholinergic stimulation by nearby immune cells. Collagen induced arthritis in alpha7nAChR^(-/-) mice was significantly severe and showed increased synovial inflammation and joint destruction compared to the wild-type mice. Similar to vagal nerve stimulation and alpha7nAChR agonists, polyunsaturated fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) also suppress inflammation. In view of their similar anti-inflammatory actions, it is proposed that vagal nerve stimulation, alpha7nAChR agonists and EPA and DHA may augment the formation of anti-inflammatory lipid molecules: lipoxins, resolvins, protectins and maresins. This implies that therapies directed at regulation of the cholinergic and alpha7nAChR mediated mechanisms and enhancing the formation of lipoxins, resolvins, protectins and maresins may halt and/or ameliorate rheumatoid arthritis, lupus and other rheumatological conditions.