Association between gene variants and response to buprenorphine maintenance treatment

A variety of studies were addressed to differentiate responders and non-responders to substitution treatment among heroin dependent patients, without conclusive findings. In particular, preliminary pharmacogenetic findings have been reported to predict treatment effectiveness in mental health and substance use disorders. Aim of the present study was to investigate the possible association of buprenorphine (BUP) treatment outcome with gene variants that may affect kappa-opioid receptors and dopamine system function. One hundred and seven heroin addicts (West European, Caucasians) who underwent buprenorphine maintenance treatment were genotyped and classified into two groups (A and B) on the basis of treatment outcome. Non-responders to buprenorphine (group B) have been identified taking into account early drop out, continuous use of heroin, severe behavioral or psychiatric problems, misbehavior and diversion during the 6 months treatment period. No difference was evidenced between responders and non-responders to BUP in the frequency of kappa opioid receptor (OPRK1) 36G>T SNP. The frequency of dopamine transporter (DAT) gene polymorphism (SLC6A3/DAT1), allele 10, was evidently much higher in “non-responder” than in “responder” individuals (64.9% vs. 55.93%) whereas the frequency of the category of other alleles (6, 7 and 11) was higher in responder than in non-responder individuals (11.02% vs. 2.13% respectively). On one hand, the hypothesis that possible gene-related changes in kappa-opioid receptor could consistently affect buprenorphine pharmacological action and clinical effectiveness was not confirmed in our study, at least in relation to the single nucleotide polymorphism 36G>T. On the other hand, the possibility that gene-related dopamine changes could have reduced BUP effectiveness and impaired maintenance treatment outcome was cautiously supported by our findings. DAT1 gene variants such as allele 10, previously reported in association with personality and behavioral problems, would have influenced the effects of BUP-induced dopamine release, modulated through mu and kappa opioid receptors, and probably the related reinforcing capacity of the drug.     

Alcohol-induced endothelial changes are associated with oxidative stress and are rapidly reversed after withdrawal

BACKGROUND: Although heavy alcohol drinkers are at an increased risk of developing cardiovascular events, moderate alcohol intake is associated with reduced incidence of cardiovascular death. This paradox might reflect a dose-related effect of different alcohol intakes on endothelial function and this, in turn, might depend on changes in oxidative stress. METHODS: We tested the effects of alcohol withdrawal in heavy alcohol consumers and compared the plasma levels of endothelin-1, nitric oxide, plasminogen activator inhibitor-1, von Willebrand factor, malondialdehyde, and intracellular glutathione with those of alcoholics that did not modify their alcohol intake and teetotalers. In human endothelial cells that had been cultured for 2 weeks in the presence of different concentrations of ethanol, we assessed the same parameters after withdrawal of ethanol exposure. RESULTS: Alcohol increased the levels of endothelin-1, nitric oxide, and plasminogen activator inhibitor-1 and decreased the levels of von Willebrand factor both in vivo and in vitro. These changes were dose dependent, rapidly reversed after withdrawal of exposure, and associated with the presence of increased oxidative stress as indicated by increased levels of both malondialdehyde and intracellular glutathione. Blockade of oxidative stress by incubation of endothelial cells in the presence of oxidants' scavengers prevented the alcohol-induced functional modifications of the endothelium. CONCLUSIONS: Alcohol affects endothelial function with an effect that is mediated by an activated oxidative stress and is rapidly reversed after withdrawal. Dose-related endothelial responses to different alcohol intakes might translate in either vascular protection or vascular damage.     

Fibroblast growth factor-2 mediates Angiotensin-converting enzyme inhibitor-induced angiogenesis in coronary endothelium

The beneficial effect exerted by angiotensin-converting enzyme inhibitors (ACEI) on vascular endothelium has been attributed to restoration of endothelial cell survival properties and improvement of angiogenesis. Fibroblast growth factor (FGF)-2 is an angiogenic factor for the microvascular endothelium, which tonically promotes endothelial cell growth and survival through an autocrine/paracrine mechanism. Here, we formulate the hypothesis that FGF-2 might contribute to the prosurvival/proangiogenic effect of ACEI. We investigated zofenoprilat and, in selected experiments, lisinopril, as representatives of ACEI. These compounds induced formation of pseudocapillaries in vessel fragments isolated from porcine coronary and human umbilical arteries by increasing endothelial cell growth up to 5-fold. Angiogenesis was abolished by inhibitors of nitric-oxide synthase (NOS) pathway and by anti-FGF-2 antibodies. Consistently, in cultured coronary endothelial cells (CVECs), ACEI up-regulated endothelial NOS (eNOS) and FGF-2 and induced mitogen-activated protein kinase extracellular signal-regulated kinase 1/2 activation. The overexpression of eNOS/FGF-2 produced, at the functional level, enhanced cell proliferation and migration, the latter effect being dose-dependent and maximal at 0.1 microM zofenoprilat. The importance of FGF-2 for the acquisition of the angiogenic phenotype elicited by ACEI was clearly demonstrated by the impairment of endothelial functions following transfection of CVECs with small interference RNA for FGF-2. Moreover, FGF-2 silencing greatly affected the nuclear translocation of the FGF receptor (FGFR)-1, highlighting the autocrine mode of action of FGF-2. At the endothelial membrane level, zofenoprilat appeared to activate the bradykinin B1 receptor, a known stimulant of FGF-2 expression. In conclusion, we show that ACEI exert protective/proangiogenic effects in microvascular coronary endothelial cells by activating the endogenous FGF-2/FGFR-1 system.     

Homovanillic acid (HVA) plasma levels inversely correlate with attention deficit-hyperactivity and childhood neglect measures in addicted patients

Summary Background. Attention deficit hyperactivity disorder (ADHD) seems to be a risk condition for substance use disorders, possibly in relationship to common neurobiological changes, underlying both addictive and externalising behaviour susceptibility. Although this vulnerability has been primarily attributed to gene variants, previous studies suggest that also adverse childhood experiences may influence neurotransmission, affecting in particular brain dopamine (DA) system and possibly concurring to the development of behavioural disorders. Therefore, we decided to investigate ADHD symptoms and plasma concentrations of the DA metabolite homovanillic acid (HVA) in abstinent addicted patients, in comparison with healthy control subjects, evaluating whether ADHD scores were related with HVA levels, as expression of DA turnover, and whether HVA values, in turn, were associated with childhood emotional neglect. Methods. Eighty-two abstinent drug dependent patients, and 44 normal controls, matched for age and sex, completed the Wender Utah Rating Scale (WURS), measuring ADHD symptoms, and the Childhood Experience of Care and Abuse Questionnaire (CECA-Q). Blood samples were collected to determine HVA plasma levels. Results. Addicted individuals showed significantly higher ADHD scores and lower HVA levels respect to control subjects. ADHD scores at WURS in addicted patients negatively correlated with plasma HVA values. In turn, plasma HVA levels were inversely associated with childhood neglect measures, reaching statistical significance with “mother-antipathy” and “mother neglect” scores. Conclusions. These findings suggest the possibility that childhood experience of neglect and poor mother–child attachment may have an effect on central dopamine function as an adult, in turn contributing to both ADHD and substance abuse neurobiological vulnerability.     

Age-related susceptibility of naive and memory CD4 T cells to apoptosis induced by IL−2 deprivation or PHA addition

The increased age-associated incidence of infectious and cancer diseases has been related to the alteration of immune functioning found in the elderly (immunosenescence). The reduction of naive T cells, which determine an impaired ability to mount immune responses to new antigens, represents a hallmark of the aging process. The aim of this study was to evaluate the susceptibility to apoptosis of purified naive and memory CD4⁺ T cells from peripheral blood of healthy people ranging in age from 20 to 98 years. Two mechanisms of T cell elimination by apoptosis have been evaluated: cytokine deprivation and activation-induced cell death. After Interleukin−2 deprivation, the percentage of naive and memory CD4⁺ apoptotic cells significantly increased with donor age concomitantly with a reduction of Bcl-2 expression and an increase of intracellular content of reactive oxygen species. After phytohemagglutinin addition, the percentage of apoptotic cells, the expression of CD95, and the intracellular reactive oxygen species, were not significantly correlated with age both in naive and memory CD4⁺ T cells. Our data demonstrate the existence of functional alterations of naive and memory T cell populations during ageing. These alterations are mainly related to the mechanism of the apoptotic event rather than to the type of cell population involved (naive or memory). The alterations of naive and memory T cells may have implications in the age-related susceptibility to diseases.