Tomás Zambrano

Identification of pharmacogenetic predictors of lipid-lowering response to atorvastatin in Chilean subjects with hypercholesterolemia.

BACKGROUND Statins are normally the first-line therapy for hypercholesterolemia (HC); however, the lipid-lowering response shows high interindividual variation. We investigated the effect of four polymorphisms in CYP3A4, CYP3A5 and ABCB1 genes on response to atorvastatin and CYP3A4 activity in Chilean subjects with HC. METHODS A total of 142 hypercholesterolemic individuals underwent atorvastatin therapy (10mg/day/1month). Serum lipid levels before and after treatment were measured. Genetic variants in CYP3A4 (-290A>G, rs2740574), CYP3A5 (6986A>G, rs776746) and ABCB1 (2677G>A/T, rs2032582 and 3435C>T, rs1045642) were analyzed by PCR-RFLP. CYP3A4 enzyme activity in urine samples was assessed through determination of 6β-hydroxycortisol/cortisol free ratio (6βOHC/FC). RESULTS After 4weeks of therapy, a significant reduction in total cholesterol (TC) and LDL-c was observed (P<0.001). The G allele for -290A>G polymorphism was related to higher percentage of variation in TC and LDL-c (P<0.001). Moreover, same allele was associated with higher HDL-c variation (P=0.017). In addition, CYP3A4 enzyme activity was lower in subjects carrying this polymorphism (P=0.009). No differences were observed for CYP3A5 and ABCB1 variants. CONCLUSION Our results suggest that presence of G allele for -290A>G polymorphism determines a better response to atorvastatin, being also associated with lower CYP3A4 activity in vivo, causing an increased atorvastatin activity.

Epigenetic Modifications of Major Depressive Disorder

Major depressive disorder (MDD) is a chronic disease whose neurological basis and pathophysiology remain poorly understood. Initially, it was proposed that genetic variations were responsible for the development of this disease. Nevertheless, several studies within the last decade have provided evidence suggesting that environmental factors play an important role in MDD pathophysiology. Alterations in epigenetics mechanism, such as DNA methylation, histone modification and microRNA expression could favor MDD advance in response to stressful experiences and environmental factors. The aim of this review is to describe genetic alterations, and particularly altered epigenetic mechanisms, that could be determinants for MDD progress, and how these alterations may arise as useful screening, diagnosis and treatment monitoring biomarkers of depressive disorders.

SLCO1B1 c.388A>G Polymorphism Is Associated with HDL-C Levels in Response to Atorvastatin in Chilean Individuals.

The use of statins as the preferred lipid-lowering therapy has clearly demonstrated its efficacy in the treatment of hypercholesterolemia, reducing also the risk of coronary events and cardiovascular disease mortality. In this study, we assessed single nucleotide polymorphisms (SNPs) in the SLCO1B1 gene and their effect on atorvastatin response. We included 129 Chilean hypercholesterolemic patients undergoing 10 mg/day of atorvastatin therapy during 4 weeks. Lipid profile was determined before and after drug administration. Genotyping of SLCO1B1 rs4149056 (c.521T>C) SNP was performed with allele-specific polymerase chain reaction, whilst polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used for genotyping the SLCO1B1 rs2306283 (c.388A>G) variant. After statin therapy, concentrations of TC, LDL-C and TG had a decrease from baseline (p < 0.05). Also, HDL-C levels increased (p < 0.05). Minor allele frequencies for the rs2306283 and rs4149056 variants were 0.547 and 0.136, respectively. LDL-C response to atorvastatin was not associated with the SLCO1B1 rs4149056 nor the rs2306283 polymorphisms (p > 0.05). However, the latter SNP was associated with HDL-C variability after atorvastatin medication (p = 0.02). This study indicates that LDL-C reduction following atorvastatin therapy is not influenced by the SNPs evaluated. In addition, the polymorphism rs2306283 at the SLCO1B1 gene determines greater HDL-C concentrations in response to atorvastatin medication in Chilean hypercholesterolemic subjects.

Involvement of cytochrome P450 in cisplatin treatment: implications for toxicity

PurposeThe aim of this study is to evaluate the relationship between the CYP450 enzyme family and cisplatin toxicity.MethodsThis article examined a collection of studies suggesting that CYP450 enzymes may influence cisplatin toxicity. We performed a narrative mini-review.ResultsThe studies review showed that CYP450 enzymes have an important role in drug-induced hepatotoxicity and nephrotoxicity, mainly CYP2E1 and CYP4A11. The studies also suggested that the cisplatin and CYP2E1 interaction leads to the generation of reactive oxygen species (ROS) and other oxidants resulting in renal injury; and that ROS generated by both the use of cisplatin and by the CYP2E1 increases tissue damage, induces apoptosis, and causes liver failure.ConclusionsWe observed that there is an important relationship between CYP450 and cisplatin, involving increased toxicity. However, the possible mechanisms described for the involvement of CYP450 enzymes in nephrotoxicity and hepatotoxicity induced by cisplatin need to be confirmed by further studies. Therefore, there is a need for a deeper investigation focusing on cisplatin toxicity mediated by CYP450 enzymes, which would undoubtedly contribute to a better understanding of the mechanisms that have been implicated so far.

APOE Polymorphisms Contribute to Reduced Atorvastatin Response in Chilean Amerindian Subjects

Genetic factors can determine the high variability observed in response to lipid-lowering therapy with statins. Nonetheless, the frequency of single nucleotide polymorphisms (SNPs) and their impact can vary due to ethnicity. Because the Chilean population carries a strong Amerindian background, the objective of this study was to evaluate the influence of apolipoprotein E (APOE) variants (rs429358, rs7412) and the 1959C>T SNP (rs5925) in the low-density lipoprotein receptor (LDLR) in response to atorvastatin treatment in hypercholesterolemic individuals. A hundred and thirty nine subjects undergoing statin therapy were included. Identification of Amerindian mtDNA haplogroups was determined by polymerase chain reaction (PCR) and PCR followed by restriction fragment length polymorphism (RFLP), respectively. SNPs were determined by PCR-RFLP. Out of the 139 individuals studied, 84.4% had an Amerindian background, according to mtDNA analysis. In relation to APOE variants, carriers of the E3/4 genotype presented lower cholesterol reduction compared to genotype E3/3 (LDL-C: −18% vs. −29%, p ˂ 0.001). On the other hand, the LDLR rs5925 SNP was not related to atorvastatin response (p = 0.5760). Our results suggest that APOE SNPs are potential predictors to atorvastatin therapy in Amerindian Chilean subjects.

Polyphenol-Related Epigenetic Modifications in Osteoarthritis: Current Therapeutic Perspectives.

The hyaline cartilage is an avascular, aneural and alymphatic tissue with a limited ability to repair itself. When the cartilage is exposed to some kind of injury, it usually triggers osteoarthritis (OA), a prevalent and degenerative joint disease closely related to aging. OA is both complex and multifactorial, and is the most common form of arthritis, being positioned as a major cause of pain and dysfunction in the world. In addition, high OA prevalence can greatly affect work capacity, making this disease a significant social problem, therefore, its prevention and treatment becomes a priority. At this time, there are numerous therapeutic strategies available to improve hyaline cartilage repair by using chondrocytes or mesenchymal cells, but neither is effective enough to generate functional and durable tissue reparation over time. In OA, chondrocytes have an aberrant gene expression and phenotype, resulting in a loss of balance between anabolic and catabolic processes. Environmental influences such as radiation, infection, smoking, nutrients, toxins and stress can affect gene expression patterns, which may constitute risk factors for various chronic and degenerative diseases, such as OA. In addition, considerable evidence shows that epigenetic mechanisms play an important role in OA chondrogenesis and pathogenesis. Natural plant-derived products such as polyphenols, which are secondary metabolites considered to have potential activity to block inflammation in several degenerative diseases, can stimulate epigenetic modifications, and may provide new therapeutic targets and cost-effective treatments. This review aims to present various polyphenolbased therapies currently used for the treatment of several progressive diseases, including OA.

Polyphenols from Chilean Propolis and Pinocembrin Reduce MMP-9 Gene Expression and Activity in Activated Macrophages

Polyphenols from diverse sources have shown anti-inflammatory activity. In the context of atherosclerosis, macrophages play important roles including matrix metalloproteinases synthesis involved in degradation of matrix extracellular components affecting the atherosclerotic plaque stability. We prepared a propolis extract and pinocembrin in ethanol solution. Propolis extract was chemically characterized using LC-MS. The effect of treatments on gene expression and proteolytic activity was measured in vitro using murine macrophages activated with LPS. Cellular toxicity associated with both treatments and the vehicle was determined using MTT and apoptosis/necrosis detection assays. MMP-9 gene expression and proteolytic activity were measured using qPCR and zymography, respectively. Thirty-two compounds were identified in the propolis extract, including pinocembrin among its major components. Treatment with either ethanolic extract of propolis or pinocembrin inhibits MMP-9 gene expression in a dose-dependent manner. Similarly, an inhibitory effect was observed in proteolytic activity. However, the effect showed by ethanolic extract of propolis was higher than the effect of pinocembrin, suggesting that MMP-9 inhibition results from a joint contribution between the components of the extract. These data suggest a potential role of polyphenols from Chilean propolis in the control of extracellular matrix degradation in atherosclerotic plaques.

Frequency of Common Variants in Genes Involved in Lipid-Lowering Response to Statins in Chilean Subjects with Hypercholesterolemia

Polimorfismos de los genes CYP3A4, CYP3A5 y ABCB1 se han asociado a variaciones en la respuesta a farmacos hipolipemiantes, como las estatinas; principales medicamentos utilizados para disminuir los niveles plasmaticos de colesterol (CT). Sin embargo, la frecuencia de estas variantes geneticas puede variar entre las poblaciones. Asi, el objetivo de este trabajo fue evaluar la frecuencia de tres polimorfismos de los genes CYP3A4, CYP3A5 y ABCB1, relacionados previamente a la respuesta a estatinas, en individuos chilenos hipercolesterolemicos (HC) y controles. Se analizaron 135 sujetos con diagnostico de hipercolesterolemia primaria (CT 240 mg/dL) y 120 controles (CT 200 mg/dL) pertenecientes a la Region de La Araucania (Chile). La genotipificacion de las variantes geneticas se efectuo mediante la tecnica de reaccion en cadena de la polimerasa seguido de restriccion enzimatica (PCR-RFLP). La distribucion de genotipos para la variante 3435C>T del gen ABCB1 en los individuos HC (CC: 49%, CT: 37%, TT: 14%) y controles (CC: 41%, CT: 48%, TT: 11%) fue semejante (P = 0,186). De forma similar, la distribucion de genotipos para el polimorfismo -290A>G del gen CYP3A4 en los pacientes HC (AA: 73%, AG: 27%, GG: 0%) y controles (AA: 71%, AG: 29%, GG: 0%) fue equivalente (P = 0,863). Del mismo modo, la distribucion de genotipos para la variante 6986A>G del gen CYP3A5 en el grupo HC (AA: 4%, AG: 41%, GG: 55%) y grupo control (AA: 4%, AG: 47%, GG: 49%) fue similar (P = 0,594). En resumen, nuestro estudio demuestra que las frecuencias de los polimorfismos 3435C>T (ABCB1), -290A>G (CYP3A4) y 6986A>G (CYP3A5) no difieren entre individuos HC y controles, y son comparables a las frecuencias encontradas en poblaciones asiaticas. Su efecto sobre el tratamiento con estatinas en la poblacion chilena debe ser investigado.

Gender-Specific Association Between ABCC2 -24C>T SNP and Reduction in Triglycerides in Chilean Patients Treated With Atorvastatin

Statins are the first‐line therapy prescribed to lower plasma cholesterol levels. Although being safe and showing several beneficial cholesterol‐independent pleiotropic effects, a significant variability regarding statins therapeutic goals has been abundantly documented, but less understood. We aimed to investigate the influence of the ABCC2 ‐24C>T single nucleotide polymorphism on Chilean hypercholesterolaemic individuals treated for 4 weeks with 10 mg/day atorvastatin. A total of 127 individuals medicated with atorvastatin 10 mg/day/4 weeks were included. Lipid profiles were determined before and after drug administration by conventional assays. Genotyping of the ABCC2 rs717620 SNP (‐24C>T) was performed with TaqMan® Drug Metabolism Genotyping Assays. As expected, atorvastatin reduced TC, LDL‐C and TG concentrations (p < 0.05). Also, HDL‐C levels were increased (p < 0.05). Minor allele frequency for the rs717620 was 0.232. Overall, atorvastatin response was not associated with the ABCC2 rs717620 SNP (p > 0.05). Nonetheless, in male individuals carrying the ‐24T allele, we observed an attenuated reduction in both TG values and the TG/HDL‐C ratio after 10 mg/day atorvastatin. This study indicates that TG levels and the TG/HDL‐C ratio are affected by the rs717620 SNP in Chilean males but not female individuals after atorvastatin treatment.

Bacterial Community Profile of the Gut Microbiota Differs between Hypercholesterolemic Subjects and Controls

The role of gut microbiota in the development of metabolic illnesses has been abundantly demonstrated. Recent studies suggest that gut microbiota alterations may also be related to the development of hypercholesterolemia. Therefore, we aimed to assess differences in the gut bacterial community profiles between hypercholesterolemic subjects and controls. Thirty cases diagnosed with hypercholesterolemia and 27 normocholesterolemic controls were included. A fasting whole blood sample was obtained to determine the lipid profile. In parallel, stool samples were collected and total DNA was isolated to assess the bacterial community profiles by denaturing gradient gel electrophoresis (DGGE). In addition, the Richness, Shannon-Weaver, and Simpson indexes were used to evaluate the richness and diversity of bacterial communities. As expected, serum concentrations of total cholesterol, triglycerides, and LDL-cholesterol were significantly higher in the cases compared with controls. Moreover, DGGE analysis showed a lower richness and diversity of bacterial communities in hypercholesterolemic subjects. In conclusion, our results showed differences in the profiles of bacterial communities between hypercholesterolemic subjects and controls, suggesting a possible role of the gut microbiota in the development of hypercholesterolemia.