Atorvastatin, Aspirin, Oxidative Stress, Coagulation and Platelet Activation Indexes

Primary and secondary prevention trials with statins, as well as with antiplatelet, clearly demonstrated that these drugs are able to reduce cardiovascular events. Even if the principal mechanism of action of statins is to lower cholesterol, other effects, the so-called pleiotropic effects, have been considered as adjunctive properties potentially accounting for the antiatherosclerotic effect of statins.

Inhibition of oxidative stress may be considered an intriguing pleiotropic effect in view of the fact that oxidative stress is thought to be a key event in the initiation and progression of atherosclerotic disease. Reduction of several markers of oxidative stress including isoprostanes, 8-hydroxydeoxyguanosine (8-OHdG), and nitrotyrosine have been observed after statin treatment. NADPH oxidase is among the most important sources of reactive oxygen species involved in atherosclerotic disease. The investigators developed an ELISA to evaluate serum levels of soluble-gp91phox, the catalytic core of phagocyte NADPH oxidase. Recently the investigators showed that statins (30 days treatment) exert an antioxidant effect via inhibition of soluble gp91phox expression.

The exact mechanism by which atorvastatin reduces NADPH oxidase, however, is unclear. Recent study showed that statin treatment inhibits leukocyte ROCK activity, a protein kinase implicated in the activation of NADPH oxidase, with a mechanism that seems to be independent from lowering cholesterol.

Accelerated atherosclerosis is a typical feature of type 2 diabetes mellitus (T2DM). Thus, patients with T2DM have a 2- to 4-fold increased risk of cardiovascular diseases (CAD) and 2- to 6-fold increased risk of stroke.

Platelets play a major role in the etiology of atherosclerotic disease, as shown by the significant decrease of cardiovascular events in patients treated with aspirin, an inhibitor of COX1 that prevents platelet thromboxane (Tx) A2 formation. Despite this, interventional trials with aspirin in diabetic patients failed to show a beneficial effect. It has been previously demonstrated that COX1 inhibition determines a shift in arachidonic acid metabolism towards other pathways, such as the lipooxygenase system. The investigators speculate that COX1 inhibition could also be associated with increased conversion of arachidonic acid to platelet isoprostane formation; the increase of platelet isoprostanes would balance the inhibition of TxA2, thus hampering the antiplatelet effect of aspirin. As reported above, statins have been reported to down-regulate systemic isoprostanes with a mechanism that may involve inhibition of NADPH oxidase,therefore it could be interesting to examine if statins improve the antiplatelet effect of aspirin via inhibition of platelet isoprostanes.

To further study the mechanism(s) implicate in gp91phox downregulation by statin the investigators planned the present study in patients with hypercholesterolemia.

Furthermore, the second part of the study will be addressed to evaluate the synergistic role of atorvastatin with aspirin treatment in Type 2 Diabetes mellitus patients.