Effect of NAC treatment and physical activity on neuroinflammation in subchronic Parkinsonism; is physical activity essential?

BACKGROUND: Neuroprotective strategies are becoming relevant to slow down dopaminergic cell death and inflammatory processes related to the progressive neurodegeneration in Parkinson's disease (PD). Interestingly, among others, physical activity (PA) or anti-oxidant agents (such as N-acetyl-L-cysteine, NAC) are common therapeutic strategies. Therefore, this study aims to analyze if there is a synergistic effect of physical activity along with NAC treatment on dopaminergic degeneration and neuroinflammatory response in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinsonism model after subchronic intoxication. METHODS: To ascertain this possibility, 48 8-week-old male mice (C57BL/6 strain) were used. Twenty four of them were placed individually in cages where voluntary physical activity was automatically monitored during 30 days and were divided into groups: (i) control; (ii) NAC; (iii) MPTP, and (iv) MPTP+NAC. The other 24 mice were divided into the same four groups but without physical activity. RESULTS: The data collected during the treatment period showed that there was an overall increase in the total running distance in all groups under physical activity, including Parkinsonian animals. However, the monitoring data per day showed that the activity routine by MPTP and MPTP+NAC groups was disrupted by alterations in the circardian rhythm because of MPTP intoxication. Results from post-mortem studies in the substantia nigra pars compacta (SNpc) showed significant decrease in the number of TH+ cells in all MPTP groups. Moreover, TH+ expression in the striatum was significantly decreased in all MPTP groups. Thus, PA + NAC treatment do not protect dopaminergic neurons against a subchronic intoxication of MPTP. Regarding glial response, the results obtained from microglial analysis do not show significant increase in the number of Iba-1+ cell in MPTP+NAC and MPTP+PA + NAC. In the striatum, a significant decrease is observed only in the MPTP+NAC group compared with that of the MPTP group. The microglial results are reinforced by those obtained from the analysis of astroglial response, in which a decrease in the expression of GFAP+ cells are observed in MPTP+NAC and MPTP+PA + NAC compared with MPTP groups both in the SNpc and in the striatum. Finally, from the study of the astroglial response by the co-localization of GFAP/S100b, we described some expression patterns observed based on the severity of the damage produced by the MPTP intoxication in the different treated groups. CONCLUSIONS: These results suggest that the combination of physical activity with an anti-oxidant agent does not have a synergistic neuroprotective effect in the nigrostriatal pathway. Our results show a potential positive effect, only due to NAC treatment, on the neuroinflammatory response after subchronic MPTP intoxication. Thus, physical activity is not essential, under these conditions. However, we believe that physical activity, used for therapeutic purposes, has a beneficial long-term effect. In this line, these results open the door to design longer studies to demonstrate its promising effect as neuroprotective strategy.

Intrapatient and interpatient pharmacokinetic variability of raltegravir in the clinical setting.

INTRODUCTION: Raltegravir (RAL) is the first in class integrase inhibitor and is licensed for administration at 400 mg twice daily. RAL pharmacokinetics are characterized by high interpatient variability and recently RAL plasma exposure has been correlated with efficacy. RAL is primarily metabolized by glucuronidation via uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) and UGT1A1*28 considered to be the main genetic variant associated with decreased UGT1A1 expression. This study investigated variability in RAL trough plasma concentrations (Ctrough) in the clinical setting, the effect of UGT1A1*28 and concomitant antiretrovirals. METHODS: A total of 86 patients, from Turin, Italy, and Madrid, Spain, were included in the analysis. Blood samples were obtained 10-14 hours postdose. Genotyping for UGT1A1*28 was conducted by sequencing. RESULTS: High interpatient and intrapatient variabilities were observed; 13 patients had ≥3 samples available, and the median coefficient of variation was 128 (64-265). Coadministration of RAL with atazanavir (ATV, n = 9) resulted in higher raltegravir Ctrough, 517 (307-2706) ng/mL when compared with patients not receiving ATV (n = 77) 223 (95-552; P = 0.02). UGT1A1*28 did not influence RAL plasma exposure. DISCUSSION: We have documented large intersubject and intrasubject variabilities in RAL plasma concentrations and confirmed the interaction with ATV. Further studies are required to better understand the mechanisms that influence the pharmacokinetics of RAL.

Influence of a single nucleotide polymorphism at the main ribavirin transporter gene on the rapid virological response to pegylated interferon-ribavirin therapy in patients with chronic hepatitis C virus infection.

The equilibrative nucleoside transporter 1 (ENT1) is the main protein involved in ribavirin cellular uptake. Polymorphisms at the ENT1 gene may influence ribavirin activity as part of hepatitis C virus (HCV) therapy. A retrospective study was conducted in 109 human immunodeficiency virus (HIV)-infected patients who were infected with HCV genotypes 1 or 4 who had received pegylated interferon (pegIFN)-ribavirin. Single nucleotide polymorphisms (SNPs) at the ENT1 gene were examined using TaqMan 5'-nuclease assays. In the study population, allelic frequencies at rs760370 were as follows: A3 (43 [39%] of 109 patients), AG (50 [46%] of 109 patients), and GG (16 [15%] of 109 patients). Achievement of rapid virological response was more frequent in GG carriers than in AA/AG carriers (50% vs 17%, respectively; P = .007). In multivariate analysis, the GG genotype (odds ratio [OR], 15.9; 95% confidence interval [CI], 2.8-92.2; P < .002), a baseline serum HCV-RNA level <600,000 IU/mL (OR, 45.7; 95% CI, 8.7-240.5; P <.001) and a serum ribavirin trough concentration >2.5 µg/mL (OR, 4.8; 95% CI, 1.3-17.1; P < .016) were associated with rapid virological response. When 2 or more of these factors were present, positive and negative predictive values of rapid virological response were 65% and 91%, respectively. In summary, a SNP rs760370A→G at the ENT1 gene influences the chance of rapid virological response to pegIFN-ribavirin therapy in HIV-infected patients with chronic HCV infection due to HCV genotypes 1 or 4, most likely modulating intracellular ribavirin exposure within hepatocytes.

Population pharmacokinetic modeling of the association between 63396C->T pregnane X receptor polymorphism and unboosted atazanavir clearance.

Atazanavir (ATV) plasma concentrations are influenced by CYP3A4 and ABCB1, which are regulated by the pregnane X receptor (PXR; NR1I2). PXR expression is correlated with CYP3A4 in liver in the absence of enzyme inducers. The PXR single nucleotide polymorphism (SNP) 63396C→T (rs2472677) alters PXR expression and CYP3A4 activity in vitro, and we previously showed an association of this polymorphism with unboosted ATV plasma concentrations. The aim of this study was to develop a population pharmacokinetic analysis to quantify the impact of 63396C→T and diurnal variation on ATV clearance. A population analysis was performed with 323 plasma samples from 182 randomly selected patients receiving unboosted ATV. Two hundred fifty-nine of the blood samples were collected at random time points, and 11 patients had a full concentration-time profile at steady state. Nonlinear mixed effects modeling was applied to explore the effects of PXR 63396C→T, patient demographics, and diurnal variation. A one-compartment model with first-order absorption and lag time best described the data. Population clearance was 19.7 liters/h with interpatient variability or coefficient of variation (CV) of 21.5%. Homozygosity for the T allele for PXR 63396 was associated with a 17.0% higher clearance that was statistically significant. Evening dosing was associated with 34% higher bioavailability than morning dosing. Patient demographic factors had no effect on ATV clearance. These data show an association of PXR 63396C→T and diurnal variation on unboosted ATV clearance. The association is likely to be mediated through an effect on hepatic PXR expression and therefore expression of its target genes (e.g., CYP3A4, SLCO1B1, and ABCB1), which are known to be involved in ATV clearance.

Use of the HCP5 single nucleotide polymorphism to predict hypersensitivity reactions to abacavir: correlation with HLA-B*5701.

OBJECTIVES: To study the correlation between the HLA-B*5701 allele and the single nucleotide polymorphism in HCP5 (rs2395029). PATIENTS AND METHODS: All HIV patients naive for abacavir seen at our institution between September 2007 and December 2008 were prospectively screened for HLA-B*5701. HCP5 rs2395029 genotyping was carried out by allelic discrimination using the TaqMan 5'-nuclease assay. High-resolution HLA class I typing was undertaken using sequence-specific primers. RESULTS: A total of 245 HIV patients were included in the study. A good correlation between HLA-B*5701 and HCP5 was observed (negative and positive predictive values of 100% and 93%, respectively). CONCLUSIONS: The use of HCP5 rs2395029 testing could be as useful as HLA-B*5701 typing to prevent the abacavir hypersensitivity reaction. Given that HCP5 testing is cheaper, less time-consuming and easier to perform than HLA typing, it may confidently replace the latter in clinical settings.

Predictors of kidney tubular dysfunction in HIV-infected patients treated with tenofovir: a pharmacogenetic study.

BACKGROUND: Tenofovir is one of the most widely used antiretroviral drugs. Tenofovir undergoes renal clearance by a combination of glomerular filtration and active tubular secretion. Although rare, the mechanism by which tenofovir causes renal damage is not well characterized. We have explored the association between kidney tubular dysfunction (KTD) and polymorphisms in genes encoding drug transporters. METHODS: All consecutive, human immunodeficiency virus (HIV)-infected patients receiving tenofovir-containing antiretroviral regimens who were seen at a single institution during the first trimester of 2008 were enrolled in the study. KTD was defined by the presence of at least 2 of the following abnormalities: nondiabetic glucosuria, urine phosphate wasting, hyperaminoaciduria, beta2-microglobulinuria, and increased fractional excretion of uric acid. Twelve single-nucleotide polymorphisms in the ABCC2, ABCC4, SCL22A6, SLC22A11, and ABCB1 genes were analyzed using TaqMan 5'-nuclease assays. RESULTS: A total of 115 HIV-infected patients were examined, of whom 19 (16.5%) had KTD. The percentage of patients with KTD was higher among those with genotype CC at position -24 of ABCC2 than among those with genotypes CT and TT (24% [16 of 68 patients] vs. 6% [3 of 47 patients]; P = .020). In a multivariate analysis, older age (odds ratio [OR], 1.1; 95% confidence interval [CI], 1.0-1.2; P = .024), lower body weight (OR, 0.9; 95% CI, 0.8-0.9; P = .048), and genotype CC at ABCC2 position -24 (OR, 5; 95% CI, 1.2-21; P = .027) were independently associated with KTD. CONCLUSIONS: Approximately 17% of HIV-infected patients treated with tenofovir had KTD. Homozygosity for the C allele at position -24 of the ABCC2 gene was strongly associated with KTD in this population. This polymorphism may help to identify patients at greater risk for developing tenofovir-associated tubulopathy, and close monitoring of renal function is warranted for these patients.

Local Gastrointestinal Injury Exacerbates Inflammation and Dopaminergic Cell Death in Parkinsonian Mice.

The cause of progressive degeneration in Parkinson's disease is not clear, although, in the last years, different studies have suggested that both brain and peripheral inflammation could play a key role in the progression of this disorder. In our study, we aimed to analyze the effect of an acute inflammation confined to the colon on dopaminergic neuronal death and glial response in mice intoxicated with MPTP. The results obtained show a very significant decrease of dopaminergic neurons in the SNpc as well as a significant decrease of dopaminergic fibers in the striatum of the MPTP+DSS-treated group compared with the control animals. In addition, there was a significant exacerbation of microglial and astrocytes activation in MPTP+DSS animals compared with the control group. This data suggests that a specific gastrointestinal injury, which induces a systemic inflammatory response, is able to exacerbate cell death mechanisms of the remaining dopaminergic neurons and then contributes to the persistent progression of the disease. These results leave open new lines of research on the role of exclusive colonic inflammation and the progression of nigrostriatal dopaminergic degeneration.

Voluntary exercise reduces plasma cortisol levels and improves transitory memory impairment in young and aged Octodon degus.

Sleep deprivation (SD) has been reported to induce transient cognitive impairment in functional domains commonly affected in dementia, including memory. Indeed, sleep disturbance has been proposed as an early marker for Alzheimer's disease (AD). SD emulates many aging-related modifications, including important memory dysfunctions possibly caused by triggers of stress such as cortisol. Although exercise is widely assumed to be beneficial for overall health, only recently has the research community focused its attention on its possible effects on brain functions such as cognition. Octodon degus (O. degus) is a recent rodent model considered suitable for the study of neurodegenerative diseases, since it spontaneously develops several histopathological hallmarks observed in AD. We aimed to uncover the interaction between stress, exercise, age and transient memory impairments after SD insult. In this study, animals had free individual access to wheels to practice voluntary exercise. The Barnes Maze (BM) task was conducted with young and aged O. degus animals after combining voluntary exercise and either normal sleep or SD. Plasma cortisol levels were measured after each condition. SD impaired hippocampus-dependent memory in both young and old animals, while cortisol levels did not significantly differ between non-SD and SD animals. However, voluntary exercise for 45 days improved the cognitive impairment caused by SD compared with the control condition. Moreover, voluntary exercise decreased plasma cortisol levels in both conditions, independently of the age.

Unexpected Exacerbation of Neuroinflammatory Response After a Combined Therapy in Old Parkinsonian Mice.

The design of therapeutic strategies that focus on the repositioning of anti-inflammatory and antioxidant drugs are a great bet to slow down the progression of neurodegenerative disorders. Despite the fact that Parkinson's disease (PD) is an age-related pathology, almost all experimental studies are carried out in young animals. Here, we evaluated the possible neuroprotective effect of the combination of the antioxidant N-acetylcysteine (NAC) and the anti-inflammatory HA-1077 in aged 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice (C57BL/6 mice, 20 months old), whose individual treatment has been shown to have neuroprotective effects in this Parkinsonism model. Interestingly, NAC+HA-1077-based treatment produced a significant increase in dopaminergic neuronal death accompanied by an increase in microglial and astroglial activation in the Substantia Nigra pars compacta (SNpc) and striatum of old-Parkinsonian mice compared to their control group. The astroglial response was also explored by co-immunostaining for GFAP and S100b together with p-JNK and it was found to be particularly exacerbated in the MPTP+NAC+HA-1077 group. The unexpected toxic effects found in the combined use of NAC and HA-1077 in old-Parkinsonian mice highlight the importance of taking into account that in elderly Parkinsonian patients the combination of some drugs (most of them used for other different age-related alterations) can have side effects that may result in the exacerbation of the neurodegenerative process.

Short communication: use of serum bilirubin levels as surrogate marker of early virological response to atazanavir-based antiretroviral therapy.

Given that atazanavir (ATV) increases bilirubin in an exposure-dependent manner, we tested whether bilirubin levels could be used as a surrogate of virological response to ATV-based regimens in 182 patients. Bilirubin increases of ≥0.7 mg/dl were independently associated with early virological response with an odds ratio of 5.2 (95% confidence interval 2.2-11.9). Total bilirubin, a nonexpensive, simple, and widely available parameter, might be used as a surrogate of virological response to ATV-based regimens, especially in areas with limited resources where HIV-RNA testing is not available.