66034T/C polymorphism of the human pregnane X receptor (hPXR) as potential risk factor for drug resistance in epilepsy - Preliminary study.

INTRODUCTION AND OBJECTIVES: Recent research has suggested that genetic factors may play an important role in the development of drug resistance in epilepsy. It is not clear which gene loci are responsible for the drug-resistant phenotype. Studying certain nuclear receptors may be helpful in predicting drug response, as they regulate drug transporting proteins and enzymes involved in their metabolism. This study focuses on one of these receptors, the human pregnane X receptor (hPXR). The objective was to examine the link between selected single nucleotide polymorphisms (SNPs) 69789A/G rs 7643645 and 66034T/C rs 13059232 hPXR and the lack of response to epilepsy treatment. MATERIALS AND METHODS: 73 patients diagnosed with drug-resistant epilepsy were included in the study. The diagnoses were made according to the criteria published by The International League Against Epilepsy (ILAE) in 2010. The control group was comprised of a group of 122 healthy volunteers. Genetic material isolated from the peripheral blood of the participants was analyzed with TagMan Genotyping Assays in search of the selected hPXR polymorphisms. RESULTS: The distribution of genotypes of the 66034T/C rs 13059232 hPXR polymorphism was significantly different in the group with drug-resistant epilepsy and the control group. In the drug-resistant group the CC genotype was significantly more common compared to the control group (50.7% vs 35.2%) p=0.0339. The distribution of 69789 A/G rs 7643645 hPXR genotypes was comparable in both groups. CONCLUSIONS: There is potential association between hPXR and drug resistance but its relevance for the development of drug-resistant phenotype remains to be studied.

Plasmatic microRNA as Potential Biomarkers of Multiple Sclerosis: Literature Review.

There is ongoing research with the goal of finding precise and sensitive biomarkers of multiple sclerosis (MS). Recently, researchers have paid particular attention to small, non-encoding, single stranded endogenous microRNA molecules (miR, miRNA). At first these molecules were thought to be found only within the cell. Today it is known, however, that they can also be found in the extracellular spaces (plasma, serum, saliva, urine, tears, sweat, milk, sperm and amniotic fluid, among others). It has been established that extracellular miRNA perform a wide spectrum of functions, such as transmitting signals between cells, modulating processes involved in angiogenesis, neurogenesis, proliferation or apoptosis. Given the high stability of these small molecules in the extracellular compartment (plasma), their tissue specificity and strong ties with pathological processes underlying multiple sclerosis, miRNA seem to be a good target for researchers trying to discover diseases' new markers. Determining an accurate miRNA expression profile in MS and correlating it with the gene profile may lead to the discovery of new pathophysiological processes. Demonstrating that changes in the composition and concentration of extracellular miRNA may in some cases correlate with certain aspects of the underlying disease (such as its severity) could lead to their use as biomarkers of MS. Further research is needed.

Selected extracellular microRNA as potential biomarkers of multiple sclerosis activity--preliminary study.

Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system (CNS). Four distinct disease courses are known, although approximately 90% of patients are diagnosed with the relapsing-remitting form (RRMS). The name "multiple sclerosis" pertains to the underlying pathology: the presence of demyelinating plaques in the CNS, in particular in the periventricular region, corpus callosum, cervical spine, and the cerebellum. There are ongoing efforts to discover biomarkers that would allow for an unequivocal diagnosis, assess the activity of inflammatory and neurodegenerative processes, or warn of disease progression. At present, small noncoding RNA particles-microRNA (miRNA, miR) seem to be particularly noteworthy, as they take part in posttranscriptional regulation of expression of various genes. Changes in composition as well as function of miRNA found in body fluids of MS patients are subjects of research, in the hope they prove accurate markers of MS activity. This preliminary study aims to evaluate the expression of selected extracellular microRNA particles (miRNA-let-7a, miRNA-92a, miRNA-684a) in patients experiencing MS relapse and remission, with healthy volunteers serving as a control group and to evaluate the correlation between miRNA expression and selected clinical parameters of those patients. Thirty-seven patients suffering from MS formed two examined groups: 20 patients undergoing relapse and 17 in remission. Thirty healthy volunteers formed the control group. All patients who were subjects to peripheral blood sampling had been hospitalized in the Department of Neurology and Stroke(1). Four milliliters of venous whole blood had been collected into EDTA tubes. The basis for the selection of the three particular miRNA investigated in this study (miRNA-let-7a, miRNA-92a, miRNA-684a) was a preliminary bioinformatic analysis of data compiled from several medical databases, including Ovid MEDLINE®, Embase, Cochrane Database of Systematic Reviews (CDSR), miRWalk, and miRBase. The isolation of extracellular microRNA from plasma was carried out using miRNeasy Mini Kit (Qiagen) reagents. The reverse transcription was carried out with TaqMan® MicroRNA Reverse Transcription Kit (Applied Biosystems), as per manufacturers' instructions. Standard microRNA TaqMan® tests (Applied Biosystems) were used for miRNA quantification. The qPCR were performed on a 7900 HT Fast Real-Time PCR System (Applied Biosystems) and analyzed using Sequence Detection System 2.3 software. In addition, all patients at the Department of Neurology and Stroke undergo a routine complete blood count with differential. The main objective of this study was to evaluate the expression of selected microRNA (has-miR-let-7a, miR-92a, and miR-648a) in the plasma of patients with MS during a relapse as well as in remission and attempt to correlate the acquired data with clinically relevant parameters of the disease. Finding such correlations may potentially lead to the use of miRNA as a biomarker of MS, which could help diagnose the disease and assess its severity and the efficacy of treatment. The difference in the expression of has-miR-let-7a in the remission group and the control group was statistically significant (p = 0.002). Similarly, the expression of miRNA-648a in patients in remission was significantly different from the expression in the control group (p = 0.02). Analysis of the correlation between the expression of miRNA-92a and the severity of the disease as measured by the EDSS scale in patients undergoing relapse showed significant negative linear correlation (r = -0.54, p = 0.01). Higher miR-648a expression correlated with more frequent flare-ups in the joint group of patients in remission and relapse (p = 0.03). This study is one of the few that demonstrate significantly changed expression of selected extracellular miRNA in plasma of MS patients and correlate those findings with clinical parameters. These observations may suggest that some miRNA subsets may be potential biomarkers for MS activity.