Statin Therapy and COVID-19 Infection (STACOV PROJECT)

Statins reduce intracellular cholesterol synthesis by interfering with the limiting enzyme HMGCoA reductase. A lower intracellular cholesterol concentration leads to activation of the transcription factor SREBP 2 upregulating LDL receptor synthesis. In general, intracellular cholesterol homeostasis achieves a new physiological equilibrium at lower cholesterol concentrations. Moreover, the effect of cholesterol pathway inhibition has also an effect on farnesyl and geranyl molecules formation influencing protein prenylation leading to changes on inflammation and immunomodulation in vitro.

Changes in intracellular cholesterol alter cell membrane composition, particularly the structures referred to cholesterol rafts that accommodate a huge number of cell surface proteins as receptors. Theoretically, alterations in cholesterol rafts could derange the function of some receptors Some preliminary studies on cell models have suggested that statins could interfere the activity of some membrane viral receptors blunting its entry to cell (Berraondo P et al CIMA nonpublished data). SARS-cov-2 goes into cells through the Angiotensin Converser Enzyme 2 (ACE2) which is located in the surface of several cells including lung cells. It has been suggested that simvastatin could have a role in SARS-cov-2 infection by blocking the virus entry to cell. However, atorvastatin has been shown to increase ACE2 expression in animal models. Moreover, intracellular cholesterol content seems to influence the virus uptake.

Severe SARS-cov-2 infection is mediated by an inflammatory storm resulting in a deep tissue injury, endothelial damage, prothrombotic state and multiorgan failure. As mentioned above, statins also have some potent anti-inflammatory effects as modulating TNF, the NFkB transcription factor or blocking some members of the Tool Like Receptor family as TLR4-9 and its downstream cofactor MYD88. This anti-inflammatory effect has been implicated in a better prognosis of some diseases as HBV or HCV chronic infection, limiting the progression of hepatic damage to chronic liver disease or hepatocarcinoma. The impact of statin use on influenza epidemics has been repetitively assessed but contradictory or non-conclusive results have been obtained. The combination of statins and angiotensin receptor blockers have shown an important protective effect on other epidemics as Ebola, probably to their action on endothelium protection. A protective effect of statins on pulmonary hypertension development in a primate HIV model has also been reported. Although, in general all these pleiotropic effects of statins have been shown in vitro and its clinical impact is not clear, a clinical assay to test the efficacy of simvastatin on SARS-cov-2 is going on. Recently an observational study including more than 8000 patients infected by Sars-Cov-2 showed the protective effect of being on statins or ACE inhibitors. Taken into account its widespread use and putative effects on viral entry, inflammation, immune mechanisms and endothelial function, the use of standard therapies as statins have been postulated to target the host response to new virus pandemics.