Inhibition of 3-Hydroxy-3-Methylglutaryl–Coenzyme A Reductase and Application of Statins as a Novel Effective Therapeutic Approach against Acanthamoeba Infections

Abstract

f Acanthamoeba is an opportunistic pathogen in humans, whose infections most commonly manifest as Acanthamoeba keratitis or, more rarely, granulomatous amoebic encephalitis. Although there are many therapeutic options for the treatment of Acanthamoeba, they are generally lengthy and/or have limited efficacy. Therefore, there is a requirement for the identification, validation, and development of novel therapeutic targets against these pathogens. Recently, RNA interference (RNAi) has been widely used for these validation purposes and has proven to be a powerful tool for Acanthamoeba therapeutics. Ergosterol is one of the major sterols in the membrane of Acanthamoeba. 3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase is an enzyme that catalyzes the conversion of HMG-CoA to mevalonate, one of the precursors for the production of cholesterol in humans and ergosterol in plants, fungi, and protozoa. Statins are compounds which inhibit this enzyme and so are promising as chemotherapeutics. In order to validate whether this enzyme could be an interesting therapeutic target in Acanthamoeba, small interfering RNAs (siRNAs) against HMG-CoA were developed and used to evaluate the effects induced by the inhibition of Acanthamoeba HMG-CoA. It was found that HMG-CoA is a potential drug target in these pathogenic free-living amoebae, and various statins were evaluated in vitro against three clinical strains of Acanthamoeba by using a colorimetric assay, showing important activities against the tested strains. We conclude that the targeting of HMG-CoA and Acanthamoeba treatment using statins is a novel powerful treatment option against Acanthamoeba species in human disease.

Statins and Voriconazole Induce Programmed Cell Death in Acanthamoeba castellanii

“…Their activity against Acanthamoeba strains has been demonstrated in previous studies from our laboratory (22,30). Briefly, the IC 50 Cellular DNA fragmentation.…”

“…Statins are a family of lipid-lowering drugs widely used to control cholesterol levels in humans. Their mechanism of action is the inhibition of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase by binding to the active site of this enzyme in Acanthamoeba (22). The enzyme converts HMG-CoA to mevalonate, a precursor of cholesterol in humans and ergosterol in plants, fungi, and protozoa (23,24).…”

Evaluation of Acanthamoeba Myosin-IC as a Potential Therapeutic Target

“…The transfection reagent was added at a ratio 2.5:1 (transfection reagent [l]/siRNA [g]) in accordance with the manufacturer's recommendations for adherent cell types and after initial optimization in previous studies with siRNA and Acanthamoeba (8,9). The experiment was performed with both Acanthamoeba strains, and it was carried out in triplicate starting with 10 4 cells/ml.…”

Statin-induced chronic cholesterol depletion inhibits Leishmania donovani infection: Relevance of optimum host membrane cholesterol

“…For example, they have been implicated in neuroprotection [48], cancer [49] and cell cycle arrest [36]. A common theme emerging from a number of studies is the role of statins in treating infections [50][51][52][53][54][55], although there appears to be a lack of consensus on a common mechanism. Our present results of optimal host membrane cholesterol requirement in leishmanial infection using statin treatment of host cells extend these observations, and could have potential implications in the control and therapy of leishmaniasis.…”