Investigation of the effects of Simvastatin and other statin drugs on gut Microbiome with regards to clinical obesity

Investigation of the effects of Simvastatin and other statin drugs on gut Microbiome with regards to clinical obesity

Rhonda Garza Biochemistry Department

Supervisors Dr. Robert Akins, PhD Dr. Jack Sobel, MD (ID DMC)

OutlineOutline

Introduction Hypothesis Methods Results Conclusion

Serum cholesterol-lowering statins act by competitive inhibition of the rate-limiting enzyme in cholesterol biosynthesis, hydroxymethylglutaryl-CoA (HMG-CoA) reductase.

Hydroxymethylglutaryl-CoA (HMG-CoA) reductase is essential in prokaryotes for biosynthesis of isoprenes, not sterols.

Central questions. Central questions. The main issue to be addressed by this The main issue to be addressed by this project is to what extent statins inhibit growth of bacteria in project is to what extent statins inhibit growth of bacteria in vitro.vitro.

Investigation of the effects of Simvastatin and other statin drugs on gut Microbiome with regards to clinical obesityInvestigation of the effects of Simvastatin and other statin drugs on gut Microbiome with regards to clinical obesity

Investigation of the effects of Simvastatin and other statin drugs on gut Microbiome with regards to clinical obesityInvestigation of the effects of Simvastatin and other statin drugs on gut Microbiome with regards to clinical obesity

The human gut is dominated by species in the Fimicutes and Bacteroides phyla.

Several studies indicate that the balance of these two groups is surprisingly important in obesity. Obese individuals who enroll in diets and successfully reduce body fat progress from Fimicute dominant to Bacteroides dominate gut species.

Obese mice that have disruptions in the obesity gene (ob/ob) show Fimicutes-dominant gut microbiota compared to Bacteroides rich

populations in lean mice

HypothesisHypothesis

My hypothesis is that a subset of six commercially used statins will selectively inhibit gut-associated bacteria in the Fimicutes phylum, predominantly Clostridium species.

In order to maintain this balance, obese individuals may benefit from specific statins in assisting or maintaining weight loss.

The study will have an impact on the choice of statins, if

some prove to be superior in bacterial management but equally effective in lowering serum cholesterol.

MethodsMethods• Enterobacteria associated with sepsis, were obtained from a variety of

sources and their species was verified by sequencing of their 16S rDNA genes.

• Statins: Lovastatin, Zocor, Fluvastatin, were dissolved from tablets at 10 mg active ingredient per ml of 15% ethanol, 0.25% NaOH and activated by heating at 60°C for 2 hours. Lipitor and Crestor were dissolved at 10 mg/ml in DMSO, Lovastatin l at 10 mg/ml in ethanol.

ResultsResults

Individual statins varied in the range of species affected

Lovastatin, Lipitor, and Zocor all inhibited B. subtilis, none inhibited E. coli, Lipitor and Zocor inhibited P. mirabilis, and only Zocor inhibited S. epidermidis.

Effective statins inhibited B. subtilis at 10 g/ml. Fluvastatin inhibited MRSA and MSSA strains of S. aureus, but was not effective against E. coli, K. pneumoniae, E. aerogenes, or S. marcescens

Table 1. Variable susceptibilities of bacterial species to individual statins by agar-based assay

SpeciesTaxonomic

groupZocor Fluvastatin Lipitor Lovastatin Crestor

B. subtilis Fimicute S S S S R

P. mirabilis Enterobacteria S S S S s

S. aureus (MRSA&MSSA)

Fimicute S S S R R

E. coli Enterobacteria S S S R R

S. epidemidis Fimicute s s s R R

K. pneumoniae Enterobacteria R R s R R

S. marcescens Enterobacteria R R R R R

E. aerogenes Enterobacteria R R R R R

Clostridium sordellii Fimicute S S R R R

Candida albicans Fungi S S S S S

See Fig. 3 and comments. R: Resistant, little or no zone of inhibition; S: susceptible, clear zone of inhibition; s: slightly susceptible, hazy zone of inhibtion

Bacillus subtilisBacillus subtilis

6633-1Bacillus subtilis

Zocor

LovastatinLovastatin

(1:10)

Zocor (1:10)

Fluvastatin Fluvastatin(1:10)

Clostridium sordellii

Clostridium sordellii

9714-1Clostridium sordellii

Zocor

LovastatinLovastatin

(1:10)

Zocor (1:10)

Fluvastatin Fluvastatin(1:10)

C. albicans S. aureus MRSA B. subtilis

S. marcescens S. epidermidisE. coli S. aureus MSSA K. pneumoniae

E. aerogenes P. mirabilis

S. aureus MSSA

Zocor Crestor

Lovastatin Fluvastatin

Lipitor Solvent

StatinsC. albicans S. aureus MRSA B. subtilis

S. marcescens S. epidermidisE. coli S. aureus MSSA K. pneumoniae

E. aerogenes P. mirabilis

E. coli S. aureus MSSA K. pneumoniae

E. aerogenes P. mirabilis

S. aureus MSSA

Zocor Crestor

Lovastatin Fluvastatin

Lipitor Solvent

Zocor Crestor

Lovastatin Fluvastatin

Lipitor Solvent

Statins

Future ExperimentsFuture Experiments

• An in vivo approach was started that will investigate fecal DNA from a donor who was treated with Simvastatin. Samples were taken pre-treatment, during treatment and post-treatment respectively. The GI flora was expected to shift from Fimicutes and Bacteroides flora to Bacteroides-dominant gut microbiota. This is being determined with successful Q-PCR testing. The effectiveness of Simvastain relative to other anti-obesity drugs is currently unclear and will be pursued in future experiments.

ConclusionConclusion

The subset of six commercially used statins did selectively inhibit gut-associated bacteria in the Fimicutes phylum, predominantly Clostridium species.

The in vivo approach is suggesting that there is a shift in gut microbiota with the treatment of Simvastatin.

• A epidemiological study will further enhance the expectation of statins as a drug that targets the Fimicute population in obese patients.