Pleiotropic effects of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors: candidate mechanisms for anti-lipid deposition in blood vessels

Association of high LDL concentrations with erectile dysfunction from a Mendelian randomization study

Lipid metabolism plays a key role in erectile dysfunction. Our purpose was to evaluate the influence of lipid-lowering drugs on erectile dysfunction employing a two-sample Mendelian randomization (MR) study. Genetic instruments were employed to represent the exposure of lipid-lowering drugs. Inverse variance-weighted MR (IVWMR) was employed to calculate the estimation of effects. IVW-MR analysis showed that the positive relationship between the expression of HMGCR and the risk of erectile dysfunction (odds ratio [OR] = 1.27, 95% confidence interval [CI] 1.03-1.57; p = 0.028). No significant relationship was detected between NPC1L1, PSK9 expression and erectile dysfunction. This MR study suggested that HMGCR inhibitors are a more desirable treatment modality for patients with ED.

Statin therapy inhibits fatty acid synthase via dynamic protein modifications

Statins are a class of drug widely prescribed for the prevention of cardiovascular disease, with pleiotropic cellular effects. Statins inhibit HMG-CoA reductase (HMGCR), which converts the metabolite HMG-CoA into mevalonate. Recent discoveries have shown HMG-CoA is a reactive metabolite that can non-enzymatically modify proteins and impact their activity. Therefore, we predicted that inhibition of HMGCR by statins might increase HMG-CoA levels and protein modifications. Upon statin treatment, we observe a strong increase in HMG-CoA levels and modification of only a single protein. Mass spectrometry identifies this protein as fatty acid synthase (FAS), which is modified on active site residues and, importantly, on non-lysine side-chains. The dynamic modifications occur only on a sub-pool of FAS that is located near HMGCR and alters cellular signaling around the ER and Golgi. These results uncover communication between cholesterol and lipid biosynthesis by the substrate of one pathway inhibiting another in a rapid and reversible manner.

Rosuvastatin Alleviates Intestinal Injury by Down-Regulating the CD40 Pathway in the Intestines of Rats Following Traumatic Brain Injury

Statins have been reported to suppress CD40 expression and nuclear factor (NF)-κB activation, which are both up-regulated in the intestines following traumatic brain injury (TBI)-induced intestinal injury. In this study, we aimed to investigate the effects of the statin rosuvastatin on post-TBI jejunal injury in rats, focusing on potential mechanisms involving the CD40/NF-κB signaling pathway. The jejunal CD40 expression was determined by western blotting. The DNA-binding activity of NF-κB was assessed by electrophoretic mobility shift assays (EMSAs). The tumor necrosis factor (TNF)-α and interleukin (IL)-1β levels were assessed by enzyme-linked immunosorbent assays (ELISAs). The severity of the jejunal mucosal injury was assessed by hematoxylin and eosin (HE) staining and histopathological evaluation. We found that the post-TBI upregulation of both CD40 expression and NF-κB activity in the jejunal tissues were significantly inhibited by rosuvastatin, while the post-TBI expression of TNF-α and IL-1β was significantly suppressed by rosuvastatin. In addition, rosuvastatin significantly ameliorated TBI-induced effects on the villus height, crypt depth, and villous surface area. Rosuvastatin suppressed TBI-induced intestinal injury in rats, which may be associated with the blockade of the CD40/NF-κB pathway.

Eleven-year temporal trends of clinical characteristics and long-term outcomes in patients undergoing percutaneous coronary intervention for acute coronary syndrome in the Shinken database

Despite the increasing incidence of acute coronary syndrome (ACS) in Japan, its prognosis has improved. However, there is a paucity of longitudinal registry data providing trends of in-hospital care and prognosis of ACS in Japan. ACS patients undergoing percutaneous coronary intervention (PCI) included in the Shinken Database 2004-2014 were divided into two groups according to admission year (2004-2009, n = 390; 2010-2014, n = 328). Patient characteristics, lesion/procedure characteristics, medications at discharge, all-cause mortality, cardiovascular death, acute myocardial infarction (AMI), target lesion revascularization (TLR), re-PCI to new lesion, and coronary artery bypass graft (CABG) within 2 years after discharge were compared between the groups. Prevalence of hypertension, dyslipidemia, and dual antiplatelet/statin prescription increased significantly between periods. Usage of second-generation drug-eluting stents (DES) increased markedly between the two periods (2.6, 66.8%), while those of bare metal stents (64.4, 26.5%) and first-generation DES (25.6, 1.5%) decreased (all, p < 0.01). Two-year event-free survival rate increased for all-cause mortality (94.6-98.3%, p = 0.01), TLR (79.4-96.1%, p < 0.01), and re-PCI to new lesion (87.3-95.1%, p < 0.01). There were no significant differences in cardiovascular death, AMI, or CABG between the two periods. The event-free rates for TLR and re-PCI to new lesion in ACS patients have increased over the last decade in Japan. These observations should be confirmed in larger, longitudinal, multicenter registries.

Perioperative Statin Treatment: Can it Decrease Postsurgical Cardiac Event Risk in Noncardiac Surgery?

Cardiac events are an important cause of postsurgical morbidity and mortality. Statin drugs have been studied as potentially risk-modifying agents in perioperative medicine. They have been shown to confer a protective benefit in cardiac surgery, but the evidence available in noncardiac surgery patient populations remains less conclusive. We hypothesized that perioperative statin treatment would be associated with lower incidence of postsurgical cardiac events (PSCEs) after major noncardiac surgery. A retrospective cohort study included 21,637 major noncardiac surgeries. Statin treatment was the exposure of interest and PSCE was the primary outcome measure. Data collection included patient age, body mass index, smoking status, diabetic status, cardiac event history, statin treatment history, and PSCE diagnoses. Perioperative statin treatment occurred in 4176 cases (19.3%). PSCEs occurred in 50 cases (0.23%), 29 in the untreated control group (0.17%) and 21 in the statin treatment group (0.50%). Relative risk in the untreated group was 0.3303 (95% confidence interval = 0.1886, 0.5786). This implied that statin-treated patients had higher risk than the untreated group. However, a logistic regression model that accounted for observed cardiac disease risk factors showed statin treatment not to be a significant predictor of PSCE in this sample. Analysis repeated in high-risk subsets of the cohort yielded similar results. A propensity score matching method that minimized differences between study groups also failed to demonstrate a significant association between statin treatment and PSCE risk. Our study did not demonstrate a significant association between perioperative statin treatment and PSCEs after major noncardiac surgery.

Lovastatin exerts protective effects on endothelial cells via upregulation of PTK2B

Statins are HMG-CoA reductase inhibitors that are used to decrease the blood levels of low-density lipoprotein (LDL). In addition, they have been shown to exert pleiotropic protective effects in the absence of LDL-lowering activity. The present study investigated the effects of lovastatin on global gene expression in human umbilical vein endothelial cells (HUVECs), in order to further explore its ability to protect against oxidized (ox)-LDL-induced cytotoxicity. HUVECs were treated with lovastatin for 2–24 h, and gene expression patterns were analyzed using cDNA microarrays. The results suggested that numerous genes were regulated by lovastatin, including certain genes associated with cell survival, such as PTK2B, BCL2 and MAP3K3. In particular, PTK2B, which has been shown to exert anti-apoptotic effects against ox-LDL-induced cell injury, was upregulated by lovastatin. Knockdown of PTK2B was able to attenuate ox-LDL-induced cell injury, and this was associated with decreased levels of phosphorylated-AKT and eNOS, and inhibition of mitochondrial-dependent apoptosis. In conclusion, the results of the present study suggested that lovastatin protects against ox-LDL-induced cell injury, potentially via the upregulation of PTK2B, which regulates the anti-apoptosis signaling pathway.

Targeting GGTase-I activates RHOA, increases macrophage reverse cholesterol transport, and reduces atherosclerosis in mice

BACKGROUND

Statins have antiinflammatory and antiatherogenic effects that have been attributed to inhibition of RHO protein geranylgeranylation in inflammatory cells. The activity of protein geranylgeranyltransferase type I (GGTase-I) is widely believed to promote membrane association and activation of RHO family proteins. However, we recently showed that knockout of GGTase-I in macrophages activates RHO proteins and proinflammatory signaling pathways, leading to increased cytokine production and rheumatoid arthritis. In this study, we asked whether the increased inflammatory signaling of GGTase-I-deficient macrophages would influence the development of atherosclerosis in low-density lipoprotein receptor-deficient mice.

METHODS AND RESULTS

Aortic lesions in mice lacking GGTase-I in macrophages (Pggt1b▵/▵) contained significantly more T lymphocytes than the lesions in controls. Surprisingly, however, mean atherosclerotic lesion area in Pggt1b▵/▵ mice was reduced by ≈60%. GGTase-I deficiency reduced the accumulation of cholesterol esters and phospholipids in macrophages incubated with minimally modified and acetylated low-density lipoprotein. Analyses of GGTase-I-deficient macrophages revealed upregulation of the cyclooxygenase 2-peroxisome proliferator-activated-γ pathway and increased scavenger receptor class B type I- and CD36-mediated basal and high-density lipoprotein-stimulated cholesterol efflux. Lentivirus-mediated knockdown of RHOA, but not RAC1 or CDC42, normalized cholesterol efflux. The increased cholesterol efflux in cultured cells was accompanied by high levels of macrophage reverse cholesterol transport and slightly reduced plasma lipid levels in vivo.

CONCLUSIONS

Targeting GGTase-I activates RHOA and leads to increased macrophage reverse cholesterol transport and reduced atherosclerosis development despite a significant increase in inflammation.

The effect of simvastatin on glucose homeostasis in streptozotocin induced type 2 diabetic rats

Objective. To investigate the effect of simvastatin on glucose homeostasis in streptozotocin induced type 2 diabetic rats. Methods. Forty male Wistar rats were randomly divided into four groups. Normal control rats were fed with standard diet, others were fed with high-fat diet. Diabetic rats were induced by a single intraperitoneal injection of STZ. The simvastatin intervention rats were fed with simvastatin during the experiment process, and the simvastatin treatment rats were fed with simvastatin after diabetes rats were induced. We measured body weight, fasting plasma glucose, cholesterol, high-density lipoprotein cholesterol, and triglyceride after an overnight fast. Results. The FPG was higher in diabetic rats when compared to normal control ones; the simvastatin intervention rats had a higher FPG compared to the diabetic rats and were more easily be induced to diabetes at the end of 4 weeks, FPG level of simvastatin treatment rats was increased compared with diabetic model rats after 12 weeks. Conclusion. These data indicate that simvastatin intervention rats may cause hyperglycemia by impairing the function of islet β cells and have an adverse effect on glucose homeostasis, especially on FPG level.

Association between statins and infections after coronary artery bypass grafting

BACKGROUND

We determined whether pre-operative statin therapy is associated with a decrease in the incidence of infections after coronary artery bypass grafting (CABG).

METHODS

A retrospective cohort study of 6253 patients undergoing isolated CABG, from the Texas Heart Institute Database from January 1, 2000 to December 31, 2010 (3869 receiving statins and 2384 not receiving statins) was conducted. Primary outcome was the development of any postoperative infection (composite of deep-sternal wound infection, leg harvest-site infection, pneumonia, or sepsis) after CABG. Secondary outcome was the association between pre-operative statin use and individual incidence of each aforementioned infection. Logistic regression analyses were performed.

RESULTS

Incidence of any postoperative infection in patients who received statins pre-operatively was 6.5% compared to 8.3% in patients who did not receive statins. Pre-operative statin therapy was associated with a significant reduction in the primary outcome (odds ratio (OR) 0.74, 95% confidence interval (CI) 0.60-0.90) in adjusted models. Among individual secondary outcomes, pre-operative statin therapy was associated with a reduced incidence of sternal wound infections (2.5% vs. 3.2%, OR 0.6, 95% CI 0.5-0.8) and leg harvest site infections (0.6% vs. 1.3%, OR 0.46, 95% CI 0.2-0.8). Pre-operative statin therapy was not associated with a reduced incidence of pneumonia or sepsis.

CONCLUSION

Pre-operative statin use is associated with a decrease in overall incidence of post-operative infections after CABG. We propose immunomodulatory effects of statins leading to a dampening of inflammatory cascade as the cause of our findings.

Do statins have a role in reduction/prevention of post-PCI restenosis?

The pathophysiology of post-PCI restenosis involves neointimal formation that consists of three phases: thrombosis (within 24 h), recruitment (3-8 days), and proliferation, which starts on day 8 of PCI. Various factors suggested to be predictors/risks for restenosis include C-reactive protein (CRP), inflammatory mediators (cytokines and adhesion molecules), oxygen radicals, advanced glycation end products (AGEs) and their receptors (RAGE), and soluble RAGE (sRAGE). The earlier noted factors produce thrombogenesis, vascular smooth muscle cell proliferation, and extracellular matrix formation. Statins have pleiotropic effects. Besides lowering serum cholesterol, they have various other biological effects including antiinflammatory, antithrombotic, CRP-lowering, antioxidant, antimitotic, and inhibition of smooth muscle cell proliferation. They inhibit matrix metalloproteinase and cyclooxygenase-2, lower AGEs, decrease expression of RAGE and increase levels of serum sRAGE. They also increase the synthesis of nitric oxide (NO) by increasing endothelial NO synthase expression and activity. Preprocedural statin therapy is known to reduce peri- and post-PCI myonecrosis and reduce the need for repeat revascularization. There is evidence that statin-eluting stents inhibit in-stent restenosis in animal models. It is concluded that because of the above attributes of statins, they are suitable candidates for reduction of post-PCI restenosis and post-PCI myonecrosis. The future directions for the use of statins in reduction of post-PCI restenosis and myonecrosis have been discussed.

Statins inhibit protein lipidation and induce the unfolded protein response in the non-sterol producing nematode Caenorhabditis elegans

Statins are compounds prescribed to lower blood cholesterol in millions of patients worldwide. They act by inhibiting HMG-CoA reductase, the rate-limiting enzyme in the mevalonate pathway that leads to the synthesis of farnesyl pyrophosphate, a precursor for cholesterol synthesis and the source of lipid moieties for protein prenylation. The nematode Caenorhabditis elegans possesses a mevalonate pathway that lacks the branch leading to cholesterol synthesis, and thus represents an ideal organism to specifically study the noncholesterol roles of the pathway. Inhibiting HMG-CoA reductase in C. elegans using statins or RNAi leads to developmental arrest and loss of membrane association of a GFP-based prenylation reporter. The unfolded protein response (UPR) is also strongly activated, suggesting that impaired prenylation of small GTPases leads to the accumulation of unfolded proteins and ER stress. UPR induction was also observed upon pharmacological inhibition of farnesyl transferases or RNAi inhibition of a specific isoprenoid transferase (M57.2) and found to be dependent on both ire-1 and xbp-1 but not on pek-1 or atf-6, which are all known regulators of the UPR. The lipid stores and fatty acid composition were unaffected in statin-treated worms, even though they showed reduced staining with Nile red. We conclude that inhibitors of HMG-CoA reductase or of farnesyl transferases induce the UPR by inhibiting the prenylation of M57.2 substrates, resulting in developmental arrest in C. elegans. These results provide a mechanism for the pleiotropic effects of statins and suggest that statins could be used clinically where UPR activation may be of therapeutic benefit.