Disagreement between two common biomarkers of global DNA methylation.

BACKGROUND: The quantification of global DNA methylation has been established in epigenetic screening. As more practicable alternatives to the HPLC-based gold standard, the methylation analysis of CpG islands in repeatable elements (LINE-1) and the luminometric methylation assay (LUMA) of overall 5-methylcytosine content in "CCGG" recognition sites are most widely used. Both methods are applied as virtually equivalent, despite the hints that their results only partly agree. This triggered the present agreement assessments. RESULTS: Three different human cell types (cultured MCF7 and SHSY5Y cell lines treated with different chemical modulators of DNA methylation and whole blood drawn from pain patients and healthy volunteers) were submitted to the global DNA methylation assays employing LINE-1 or LUMA-based pyrosequencing measurements. The agreement between the two bioassays was assessed using generally accepted approaches to the statistics for laboratory method comparison studies. Although global DNA methylation levels measured by the two methods correlated, five different lines of statistical evidence consistently rejected the assumption of complete agreement. Specifically, a bias was observed between the two methods. In addition, both the magnitude and direction of bias were tissue-dependent. Interassay differences could be grouped based on Bayesian statistics, and these groups allowed in turn to re-identify the originating tissue. CONCLUSIONS: Although providing partly correlated measurements of DNA methylation, interchangeability of the quantitative results obtained with LINE-1 and LUMA was jeopardized by a consistent bias between the results. Moreover, the present analyses strongly indicate a tissue specificity of the differences between the two methods.

Methadone induces hypermethylation of human DNA.

BACKGROUND: Increased global DNA methylation in the blood of patients chronically exposed to opioids had been interpreted as an indication of an epigenetic action of this drug class. MATERIALS & METHODS: To strengthen the causality, human MCF7 cells were cultured in media with the addition of several known or potential modulators of DNA methylation including methadone. RESULTS: Following 3 days of incubation with several different known or potential epigenetic modulators, global DNA methylation, quantified at LINE-1 CpG islands, showed a large variability across all treatments ranging from 27.8 to 63%. Based on distribution analysis of the global methylation of human DNA exposed to various potential modulators, present in vitro experiments showed that treatment with the opioid methadone was associated with an increased probability of hypermethylation. CONCLUSION: This strengthens the evidence that opioids interfere with mechanisms of classical epigenetics.

Consequences of a human TRPA1 genetic variant on the perception of nociceptive and olfactory stimuli.

BACKGROUND: TRPA1 ion channels are involved in nociception and are also excited by pungent odorous substances. Based on reported associations of TRPA1 genetics with increased sensitivity to thermal pain stimuli, we therefore hypothesized that this association also exists for increased olfactory sensitivity. METHODS: Olfactory function and nociception was compared between carriers (n = 38) and non-carriers (n = 43) of TRPA1 variant rs11988795 G>A, a variant known to enhance cold pain perception. Olfactory function was quantified by assessing the odor threshold, odor discrimination and odor identification, and by applying 200-ms pulses of H2S intranasal. Nociception was assessed by measuring pain thresholds to experimental nociceptive stimuli (blunt pressure, electrical stimuli, cold and heat stimuli, and 200-ms intranasal pulses of CO2). RESULTS: Among the 11 subjects with moderate hyposmia, carriers of the minor A allele (n = 2) were underrepresented (34 carriers among the 70 normosmic subjects; p = 0.049). Moreover, carriers of the A allele discriminated odors significantly better than non-carriers (13.1±1.5 versus 12.3±1.6 correct discriminations) and indicated a higher intensity of the H2S stimuli (29.2±13.2 versus 21±12.8 mm VAS, p = 0.006), which, however, could not be excluded to have involved a trigeminal component during stimulation. Finally, the increased sensitivity to thermal pain could be reproduced. CONCLUSIONS: The findings are in line with a previous association of a human TRPA1 variant with nociceptive parameters and extend the association to the perception of odorants. However, this addresses mainly those stimulants that involve a trigeminal component whereas a pure olfactory effect may remain disputable. Nevertheless, findings suggest that future TRPA1 modulating drugs may modify the perception of odorants.

Functional genomics suggest neurogenesis in the adult human olfactory bulb.

The human olfactory bulb displays high morphologic dynamics changing its volume with olfactory function, which has been explained by active neurogenetic processes. Discussion continues whether the human olfactory bulb hosts a continuous turnover of neurons. We analyzed the transcriptome via RNA quantification of adult human olfactory bulbs and intersected the set of expressed transcriptomic genes with independently available proteomic expression data. To obtain a functional genomic perspective, this intersection was analyzed for higher-level organization of gene products into biological pathways established in the gene ontology database. We report that a fifth of genes expressed in adult human olfactory bulbs serve functions of nervous system or neuron development, half of them functionally converging to axonogenesis but no other non-neurogenetic biological processes. Other genes were expectedly involved in signal transmission and response to chemical stimuli. This provides a novel, functional genomics perspective supporting the existence of neurogenesis in the adult human olfactory bulb.

µ-opioid receptor gene variant OPRM1 118 A>G: a summary of its molecular and clinical consequences for pain.

The human µ-opioid receptor variant 118 A>G (rs1799971) has become one of the most analyzed genetic variants in the pain field. At the molecular level, the variant reduces opioid receptor signaling efficiency and expression, the latter probably via a genetic-epigenetic interaction. In experimental settings, the variant was reproducibly associated with decreased effects of exogenous opioids. However, this translates into very small clinical effects (meta-analysis of 14 studies: Cohen's d = 0.096; p = 0.008), consisting of slightly higher opioid dosing requirements in peri- and post-operative settings. An effect can neither be maintained for chronic analgesic therapy nor for opioid side effects. It seems unlikely that further studies will reveal larger effect sizes and, therefore, further analyses appear unwarranted. Thus, due to its small effect size, the SNP is without major clinical relevance as a solitary variant, but should be regarded as a part of complex genotypes underlying pain and analgesia.

Common non-epigenetic drugs as epigenetic modulators.

Epigenetic effects are exerted by a variety of factors and evidence increases that common drugs such as opioids, cannabinoids, valproic acid, or cytostatics may induce alterations in DNA methylation patterns or histone conformations. These effects occur via chemical structural interactions with epigenetic enzymes, through interactions with DNA repair mechanisms. Computational predictions indicate that one-twentieth of all drugs might potentially interact with human histone deacetylase, which was prospectively experimentally verified for the compound with the highest predicted interaction probability. These epigenetic effects add to wanted and unwanted drug effects, contributing to mechanisms of drug resistance or disease-related and unrelated phenotypes. Because epigenetic changes might be transmitted to offspring, the need for reliable and cost-effective epigenetic screening tools becomes acute.

Linkage between increased nociception and olfaction via a SCN9A haplotype.

BACKGROUND AND AIMS: Mutations reducing the function of Nav1.7 sodium channels entail diminished pain perception and olfactory acuity, suggesting a link between nociception and olfaction at ion channel level. We hypothesized that if such link exists, it should work in both directions and gain-of-function Nav1.7 mutations known to be associated with increased pain perception should also increase olfactory acuity. METHODS: SCN9A variants were assessed known to enhance pain perception and found more frequently in the average population. Specifically, carriers of SCN9A variants rs41268673C>A (P610T; n = 14) or rs6746030C>T (R1150W; n = 21) were compared with non-carriers (n = 40). Olfactory function was quantified by assessing odor threshold, odor discrimination and odor identification using an established olfactory test. Nociception was assessed by measuring pain thresholds to experimental nociceptive stimuli (punctate and blunt mechanical pressure, heat and electrical stimuli). RESULTS: The number of carried alleles of the non-mutated SCN9A haplotype rs41268673C/rs6746030C was significantly associated with the comparatively highest olfactory threshold (0 alleles: threshold at phenylethylethanol dilution step 12 of 16 (n = 1), 1 allele: 10.6±2.6 (n = 34), 2 alleles: 9.5±2.1 (n = 40)). The same SCN9A haplotype determined the pain threshold to blunt pressure stimuli (0 alleles: 21.1 N/m(2), 1 allele: 29.8±10.4 N/m(2), 2 alleles: 33.5±10.2 N/m(2)). CONCLUSIONS: The findings established a working link between nociception and olfaction via Nav1.7 in the gain-of-function direction. Hence, together with the known reduced olfaction and pain in loss-of-function mutations, a bidirectional genetic functional association between nociception and olfaction exists at Nav1.7 level.

Functional genomics of pain in analgesic drug development and therapy.

Advances in genomic research have led to the clarification of the detailed involvement of gene products in biological pathways and these are being increasingly exploited in strategies for drug discovery and repurposing. Concomitant developments in informatics have resulted in the acquisition of complex gene information through the application of computational analysis of molecular interaction networks. This approach enables the acquired knowledge on hundreds of genes to be used to view molecular disease mechanisms from a genetic point of view. By analyzing 410 genes which control the complex process of pain, we show by computational analysis, based on functional annotations to pain-related genes, that 12 clearly circumscribed functional areas are essential for pain perception and thus for analgesic drug development. The genetics perspective revealed that future development strategies should focus on substances modulating intracellular signal transduction, ion transport and anatomical structure development. These processes are involved in the genetic-based absence of pain and therefore, provide promising fields for curative or preventive treatments. In contrast, interactions with G-protein coupled receptor pathways seem merely to provide symptomatic, not preventative relief of pain. In addition, biological functions accessed either by analgesic drugs or microRNAs suggest that synergistic therapies may be a future direction for drug development. With modern computational functional genomics, it is possible to exploit genetic information from increasingly available data sets on complex diseases, such as pain, and offers a new insight into drug development and therapy which is complementary to pathway-centered approaches.

Chronic opioid use is associated with increased DNA methylation correlating with increased clinical pain.

Environmentally caused changes in chromosomes that do not alter the DNA sequence but cause phenotypic changes by altering gene transcription are summarized as epigenetics. A major epigenetic mechanism is methylation or demethylation at CpG-rich DNA islands. DNA methylation triggered by drugs has largely unexplored therapeutic consequences. Here we report increased methylation at a CpG rich island in the OPRM1 gene coding for µ-opioid receptors and at a global methylation site (LINE-1) in leukocytes of methadone-substituted former opiate addicts compared with matched healthy controls. Higher DNA methylation associated with chronic opioid exposure was reproduced in an independent cohort of opioid-treated as compared to non-opioid-treated pain patients. This suggests that opioids may stimulate DNA methylation. The OPRM1 methylation had no immediate effect on µ-opioid receptor transcription and was not associated with opioid dosing requirements. However, the global DNA methylation at LINE-1 was significantly correlated with increased chronic pain. This suggests inhibitory effects on the transcription of still unspecified nocifensive gene products. It further implies that opioids may be causally associated with increased genome-wide DNA methylation, although currently there is no direct evidence of this. This has phenotypic consequences for pain and may provide a new, epigenetics-associated mechanism of opioid-induced hyperalgesia. The results indicate a potential influence of opioid analgesics on the patients' epigenome. They emphasize the need for reliable and cost-effective screening tools and may imply that high-throughput screening for lead compounds in artificial expression systems may not provide the best tools for identifying new pain medications.

Necessity and risks of arterial blood sampling in healthy volunteer studies.

Arterial blood sampling is necessary when drugs such as the fast-acting opioid analgesic remifentanil exhibit relevant differences between arterial and venous blood concentrations. Arterial cannulation is generally considered to be clinically safe and has thus become a standard procedure in pharmacokinetic-pharmacodynamic assessments. However, rare cases of arterial occlusions have to be considered in risk-benefit assessments of arterial sampling in pharmacokinetic studies, especially when including healthy volunteers. In an actual case, arterial occlusion requiring surgical repair was caused by a factor V Leiden thrombophilia associated genetic variant F5 1691G>A (rs6025) and aggravated by a hypoplastic radial artery. Neither risk factor had been identified prior to enrolment by routine laboratory tests such as the prothrombin time (international normalized ratio), partial thromboplastin time and the clinical Allen's test of arterial function. Re-assessment of the necessity of arterial sampling showed that none of the potential alternatives, target concentrations of computerized infusions or venous concentrations during non-steady-state and steady-state conditions could provide the arterial concentrations. Relying on venous concentrations may result in erroneous pharmacodynamic parameters. Accurate pharmacokinetic-pharmacodynamic studies relying on precisely measured blood concentrations require serial sampling techniques during both steady-state and non-steady-state conditions. However, as illustrated by the presented case, incidents involving the generally safe procedure of arterial sampling are possible, although rare. To further minimize the risks, screening of subjects for prothrombotic risks and careful assessment of the suitability of the artery should be considered in pharmacokinetic studies requiring arterial cannulation.

Kinetics of serum brain-derived neurotrophic factor following low-intensity versus high-intensity exercise in men and women.

Physical activity has been shown to enhance circulating brain-derived neurotrophic factor (BDNF) in animals and humans. However, the exact time course and sex-specific modulation of peripheral BDNF in response to exercise are still poorly understood. We examined the kinetics of BDNF serum concentrations in response to perceived high-intensity and low-intensity exercise, and during a subsequent recovery period by taking several blood samples during each phase. Furthermore, we compared the BDNF concentration between young men and women taking oral contraceptives. We found transient BDNF elevations during physical activity only for the high-intensity condition. Here, BDNF reached its maximum serum concentration after 20 min of exercise, and returned to baseline after approximately 10 min of recovery. Although there were no sex differences during baseline or recovery, the increase in the BDNF concentration during the exercise phase was more pronounced in men than in women.

Genetic-epigenetic interaction modulates µ-opioid receptor regulation.

Genetic and epigenetic mechanisms play important roles in protein expression, although at different levels. Genetic variations can alter CpG sites and thus influence the epigenetic regulation of mRNA expression, providing an increasingly recognized mechanism of functional consequences of genetic polymorphisms. One of those genetic effects is the association of reduced µ-opioid receptor expression with the functional genetic variant N40D (OPRM1 118A>G, rs1799971) that causes an amino acid exchange in the extracellular terminal of the µ-opioid receptor. We report that the nucleotide exchange at gene position +118 introduces a new CpG-methylation site into the OPRM1 DNA at position +117. This leads to an enhanced methylation of the OPRM1 DNA at this site and downstream. This epigenetic mechanism impedes µ-opioid receptor upregulation in brain tissue of Caucasian chronic opiate addicts, assessed postmortem. While in wild-type subjects, a reduced signalling efficiency associated with chronic heroin exposure was compensated by an increased receptor density, this upregulation was absent in carriers of the 118G receptor variant due to a diminished OPRM1 mRNA transcription. Thus, the OPRM1 118A>G SNP variant not only reduces µ-opioid receptor signalling efficiency, but, by a genetic-epigenetic interaction, reduces opioid receptor expression and therefore, depletes the opioid system of a compensatory reaction to chronic exposure. This demonstrates that a change in the genotype can cause a change in the epigenotype with major functional consequences.

A common HLA-DPA1 variant is associated with hepatitis B virus infection but fails to distinguish active from inactive Caucasian carriers.

BACKGROUND AND AIMS: Chronic infection with the hepatitis B virus (HBV) is a major health issue worldwide. Recently, single nucleotide polymorphisms (SNPs) within the human leukocyte antigen (HLA)-DP locus were identified to be associated with HBV infection in Asian populations. Most significant associations were observed for the A alleles of HLA-DPA1 rs3077 and HLA-DPB1 rs9277535, which conferred a decreased risk for HBV infection. We assessed the implications of these variants for HBV infection in Caucasians. METHODS: Two HLA-DP gene variants (rs3077 and rs9277535) were analyzed for associations with persistent HBV infection and with different clinical outcomes, i.e., inactive HBsAg carrier status versus progressive chronic HBV (CHB) infection in Caucasian patients (n = 201) and HBsAg negative controls (n = 235). RESULTS: The HLA-DPA1 rs3077 C allele was significantly associated with HBV infection (odds ratio, OR = 5.1, 95% confidence interval, CI: 1.9-13.7; p = 0.00093). However, no significant association was seen for rs3077 with progressive CHB infection versus inactive HBsAg carrier status (OR = 2.7, 95% CI: 0.6-11.1; p = 0.31). In contrast, HLA-DPB1 rs9277535 was not associated with HBV infection in Caucasians (OR = 0.8, 95% CI: 0.4-1.9; p = 1). CONCLUSIONS: A highly significant association of HLA-DPA1 rs3077 with HBV infection was observed in Caucasians. However, as a differentiation between different clinical courses of HBV infection was not possible, knowledge of the HLA-DPA1 genotype cannot be translated into personalized anti-HBV therapy approaches.

Single and combined IL28B, ITPA and SLC28A3 host genetic markers modulating response to anti-hepatitis C therapy.

Advances in hepatitis C pharmacogenomics identified modulations of a sustained virologic response (SVR) by frequent IL28B gene variants and of ribavirin-induced hemolysis by frequent ITPA gene variants. These associations have been widely reproduced in various ethnicities, clinical settings and hepatitis C viral genotypes. The IL28B minor alleles rs8099917G, rs12979860T and rs12980275G have been associated with non-SVR whereas the ITPA minor alleles rs1127354A and rs7270101C were associated with less hemolytic side effects, an effect also attributed to a nucleoside transporter gene SLC28A3 rs10868138G/rs56350726T haplotype. The significance levels of these associations, especially in genome-wide studies, were very high. We nevertheless tested how good clinical outcomes of peginterferon α/ribavirin therapy, such as SVR or hemolytic side effects, were predicted by these variants. An analysis in an example dataset of 115 patients revealed that the prediction of non-SVR or hemolysis by single variants was often only slightly better than guessing. Using combinations of IL28B variants provided a higher accuracy (64.5%) of predicting non-SVR than with single IL28B variants (accuracy 60-63%). Similarly, a decline in blood hemoglobin by ≥3 g/dl could be better predicted at an accuracy of 70% (10% better than guessing) with a combination of an ITPA variant with a nucleoside transporter gene (SLC28A3) haplotype. Thus, genotyping information about single IL28B or ITPA variants is reproducibly and statistically significantly associated with hepatitis C therapy outcomes; however, the clinical predictive utility of single variants can be increased by combinations of genotypes.

Effect sizes in experimental pain produced by gender, genetic variants and sensitization procedures.

BACKGROUND: Various effects on pain have been reported with respect to their statistical significance, but a standardized measure of effect size has been rarely added. Such a measure would ease comparison of the magnitude of the effects across studies, for example the effect of gender on heat pain with the effect of a genetic variant on pressure pain. METHODOLOGY/PRINCIPAL FINDINGS: Effect sizes on pain thresholds to stimuli consisting of heat, cold, blunt pressure, punctuate pressure and electrical current, administered to 125 subjects, were analyzed for 29 common variants in eight human genes reportedly modulating pain, gender and sensitization procedures using capsaicin or menthol. The genotype explained 0-5.9% of the total interindividual variance in pain thresholds to various stimuli and produced mainly small effects (Cohen's d 0-1.8). The largest effect had the TRPA1 rs13255063T/rs11988795G haplotype explaining >5% of the variance in electrical pain thresholds and conferring lower pain sensitivity to homozygous carriers. Gender produced larger effect sizes than most variant alleles (1-14.8% explained variance, Cohen's d 0.2-0.8), with higher pain sensitivity in women than in men. Sensitization by capsaicin or menthol explained up to 63% of the total variance (4.7-62.8%) and produced largest effects according to Cohen's d (0.4-2.6), especially heat sensitization by capsaicin (Cohen's d = 2.6). CONCLUSIONS: Sensitization, gender and genetic variants produce effects on pain in the mentioned order of effect sizes. The present report may provide a basis for comparative discussions of factors influencing pain.

Role of nucleoside transporters SLC28A2/3 and SLC29A1/2 genetics in ribavirin therapy: protection against anemia in patients with chronic hepatitis C.

BACKGROUND AND AIM: The standard of hepatitis C antiviral therapy combines pegylated interferon-α with ribavirin. This polar guanosine analog improves the sustained virological response (SVR) rates, but may induce hemolytic anemia. As its pharmacokinetics depend on facilitated transmembrane transport, we assessed whether variants in genes that code for concentrative (concentrative nucleoside transporters 2 and 3 coded by SLC28A2 and SLC28A3, respectively) and equilibrative nucleoside transporters (equilibrative nucleoside transporters 1 and 2 coded by SLC29A1 and SLC29A2, respectively) are associated with the therapy response and side effects. METHODS: Patients (n=169) chronically infected with the hepatitis C virus genotype 1, treated with standard doses of pegylated interferon-α and weight-based doses of ribavirin for up to 48 weeks, were genotyped for 21 variants in nucleoside transporter genes SLC28A2, SLC28A3, SLC29A1, and SLC29A2, selected to include reported functional variants and to span the complete gene loci. The presence or absence of a SVR (n=169) and a relevant decrease (>3 g/dl, n=115) in blood hemoglobin were associated with the genotypes. RESULTS: The variant SLC28A3 haplotype rs10868138G/rs56350726T (allelic frequency 0.074) was associated with a lower incidence (35.5%) of relevant decreases (>3 g/dl) in blood hemoglobin than in noncarriers (64.3%; P=0.024, n=115). This protection against hemolytic anemia was not associated with decreased SVR rates (n=169). CONCLUSION: A genetic variant in SCL28A3 coding for the concentrative nucleoside transporter 3 protects patients with chronic hepatitis C against hemolytic anemia without affecting SVR in hepatitis C virus genotype 1.

Importance of IL28B gene polymorphisms in hepatitis C virus genotype 2 and 3 infected patients.

BACKGROUND & AIMS: Genetic variation in the interleukin 28B (IL28B) gene has been associated with the response to interferon-alfa/ribavirin therapy in hepatitis C virus (HCV) genotype 1-infected patients. The importance of three IL28B single nucleotide polymorphisms (rs8099917, rs12980275 and rs12979860) for HCV genotype 2/3-infected patients is unknown. METHODS: In patients with chronic hepatitis C genotype 2/3 (n=267), IL28B host genotypes (rs8099917, rs12980275 and rs12979860) were analyzed for associations with sustained virologic response (SVR) to antiviral therapy with (pegylated) interferon-alfa and ribavirin and with respect to epidemiological, biochemical, and virological parameters. For comparison, hepatitis C genotype 1 patients (n=378) and healthy controls (n=200) were included. RESULTS: The rs12979860 CC genotype, lower age, and genotype 2 were significantly associated with SVR in HCV genotype 2/3-infected patients (p=0.01, p=0.03 and p=0.03, respectively). No association was observed for rs8099917 and rs12980275. In addition, an SVR in patients with rapid virologic response (RVR) was associated with the rs12979860 CC genotype (p=0.05), while for non-RVR no association was found. Furthermore, a significant association with a higher baseline viral load was observed for all three IL28B genotypes in genotype 1/2/3-infected patients. Finally, increasing frequencies of the rs12979860 CC genotypes were observed in genotype 1- (33.9%), genotype 3- (38.9%), and genotype 2-infected (51.9%) patients in comparison with healthy controls (49.0%) (p<0.01). CONCLUSIONS: In genotype 2/3-infected patients, rs12979860 was significantly associated with SVR. The frequency of the rs12979860 CC genotype is lower in HCV genotype 1 vs. genotype 2/3 patients. All major IL28B genotypes are associated with HCV-RNA concentration.

Impact of donor and recipient IL28B rs12979860 genotypes on hepatitis C virus liver graft reinfection.

BACKGROUND & AIMS: Recent studies have described a major impact of genetic variations near the IL28B gene on the natural course and outcome of antiviral therapy in chronic hepatitis C. We therefore, aimed to explore the impact of donor and recipient genotypes of these polymorphisms on hepatitis C virus (HCV) liver graft reinfection. METHODS: Donor and recipient genotypes of IL28B rs12979860C>T single nucleotide polymorphism were determined in 91 patients with HCV liver graft reinfection, 47 of whom were treated with pegylated interferon-α (PEG-IFN-α) and ribavirin. IL28B genetic polymorphisms were correlated with the natural course and treatment outcome of recurrent hepatitis C. RESULTS: Patients requiring liver transplantation due to end-stage chronic hepatitis C appeared to be selected toward the adverse genotypes rs12979860 CT/TT compared to non-transplanted HCV-infected patients (p=0.046). Patients with the donor genotype rs12979860 CC had higher peak ALT and HCV RNA serum concentrations than those with CT/TT (p=0.04 and 0.06, respectively). No association was observed between ALT/HCV RNA serum concentrations and recipient genotypes (p>0.3). More important, donor IL28B rs12979860 CC vs. CT/TT genotypes were associated with rapid, complete early, and sustained virologic response (RVR, cEVR, SVR) to treatment with PEG-IFN-α and ribavirin (p=0.003, 0.0012, 0.008, respectively), but weaker associations of recipient genotypes with RVR, cEVR, and SVR were observed as well (p=0.0046, 0.115, 0.118, respectively). CONCLUSIONS: We provide evidence for a dominant, but not exclusive impact of the donor rather than the recipient IL28B genetic background on the natural course and treatment outcome of HCV liver graft reinfection.

Epigenetics in pain and analgesia: an imminent research field.

Heritable phenotypes resulting from environment-caused changes in a chromosome without alterations in the DNA sequence are increasingly recognized as a basis of personalized therapy. Epigenetic mechanisms include covalent modifications of the DNA (methylation) or of the DNA-packaging histones (e.g., deacetylation or phosphorylation). In addition, regulatory non-coding RNA molecules (micro-RNAs) exert epigenetic actions. This leads to disruption or otherwise modified expression of genes. Environmental influences such as nutritional factors, exposure to chemicals or drugs, but also social factors appear to exert epigenetic actions. Histone modifications and DNA methylation are associated with the subject's age. Epigenetic mechanisms can silence the expression of pro- or antinociceptive genes. To the epigenetic control of nociception adds its control of the pharmacodynamics or pharmacokinetics of analgesics by epigenetic control of drug targets and analgesics metabolizing enzymes. Although epigenetics-based strategies for pain therapy are not yet available, experiments in rodents suggest that RNA interference may become a new therapy approach for neuropathic and other pain. Another epigenetic approach to analgesic treatment employs inhibitors of histone deacetylase that act on the epigenome by indirectly remodeling the spatial conformation of the chromatin. Finally, epigenetic techniques such as RNA interference have been employed in pain research to proof the contribution of certain proteins to nociception. Thus, the new field of epigenetics becomes increasingly used in research and management of pain and will complement genetics. This article introduces epigenetics to pain and summarizes the current and future utility.

Screening for IL28B gene variants identifies predictors of hepatitis C therapy success.

BACKGROUND: Recent research has shown that genetic variation in the IL28B gene predicts both chronicity of HCV infection and sustained virological response (SVR) to antiviral standard therapy. Because HCV affects 170 million people worldwide and is a leading cause of cirrhosis and hepatocellular carcinoma, screening for prognostic factors in routine clinical practice requires rapid and reliable assays. METHODS: The frequencies of gene polymorphisms IL28B rs8099917, rs12979860 and rs12980275 were investigated in two cohorts of 89 and 187 unrelated HCV-infected Caucasian patients and 195 non-infected participants. This was carried out by means of newly developed sensitive Pyrosequencing™ screening assays. RESULTS: The minor alleles were more frequent in patients (n=276) than in controls (n=195), with odds ratios (recessive hereditary model) of 2.2-11.6, indicating a moderate to large genotype effect size. The positive predictive values of the minor alleles for chronicity of HCV infection were 68.3%, 64.8% and 65.8% for rs8099917, rs12979860 and rs12980275, respectively. The minor alleles were also more frequent in patients who had a non-SVR (n=49) than in SVR patients (n=40), with odds ratios of 1.1-3.5 showing a small to moderate genotype effect size. The positive predictive values for non-SVR were 56.9%, 79.2% and 74% for rs8099917, rs12979860 and rs12980275, respectively. CONCLUSIONS: With the screening for IL28B polymorphisms rs12980275, rs8099917 and rs12979860, which are associated with HCV chronicity and with reduced SVR rates, an important prognostic factor of the therapy of chronic hepatitis C can be easily diagnosed.