Norma Jung

Impact of P-glycoprotein on clopidogrel absorption.

The antiplatelet activity of clopidogrel is characterized by considerable interindividual differences. Variable intestinal absorption is suggested to contribute to the inconsistencies in response. We tested the hypothesis that the intestinal efflux transporter P‐glycoprotein (P‐gp) limits the oral bioavailability of clopidogrel and that variance in the MDR1 gene encoding P‐gp predicts absorption variability.

Relevance of the Organic Cation Transporters 1 and 2 for Antiretroviral Drug Therapy in Human Immunodeficiency Virus Infection

Carrier-mediated transport across cell membranes is an important determinant of activity, resistance, and toxicity of chemotherapeutic agents including antiretroviral (ARV) drugs (ARDs). The organic cation transporters (OCTs) 1 and 2 have been implicated in the translocation of different cationic drugs but so far were insufficiently tested for interactions with ARDs. Here, we assessed among cationic drugs commonly used in human immunodeficiency virus (HIV) therapy inhibitors and substrates of OCTs, and analyzed the tissue distribution of OCTs and their expression in lymph nodes (LNs), the primary intracellular target of HIV and ARDs. Inhibitors were identified by measuring the attenuated uptake of the radiolabeled model substrate 1-methyl-4-phenylpyridinium into OCT-transfected human embryonic kidney-293 cells in the presence of ARDs. Substrates were identified by measuring OCT-specific intracellular accumulation using liquid chromatography/tandem mass spectrometry. Inhibitory drugs were (in order of increasing potency): nelfinavir < ritonavir < saquinavir < indinavir < trimethoprim < pentamidine, with consistently lower IC50 values determined for OCT1. Substrates with highest transport efficacy (Vmax/Km) were lamivudine (OCT1, 8 μl/mg protein/min; OCT2, 4.4 μl/mg protein/min) and zalcitabine (OCT1, 4.1 μl/mg protein/min; OCT2, 2.6 μl/mg protein/min). Using quantitative real-time polymerase chain reaction, a marked expression level of OCT1 was detected in human samples of liver, ovary, prostate, and testis, and of OCT2 in kidney, colon, heart, skeletal muscle, and testis. Expression of OCTs in LNs was low in HIV-negative control individuals but dramatically increased in HIV-infected persons. These data suggest that drug interactions about the OCTs may be relevant for the ARV therapy, in particular by influencing drug accession to infected tissues and hepatic or renal elimination.

Plasmacytoid dendritic cells accumulate and secrete interferon alpha in lymph nodes of HIV-1 patients.

Circulating plasmacytoid dendritic cells (pDC) decline during HIV-1 infection, but at the same time they express markedly higher levels of interferon alpha (IFNα), which is associated with HIV-1 disease progression. Here we show an accumulation of pDC in lymph nodes (LN) of treatment-naïve HIV-1 patients. This phenomenon was associated with elevated expression of the LN homing marker, CCR7, on pDC in peripheral blood of HIV-1 patients, which conferred increased migratory capacity in response to CCR7 ligands in ex vivo functional assays. LN-homed pDC of HIV-1 patients presented higher CD40 and lower BDCA2 levels, but unchanged CD83 and CD86 expression. In addition, these cells expressed markedly higher amounts of IFNα compared to uninfected individuals, and were undergoing faster rates of cell death. These results demonstrate for the first time that in asymptomatic, untreated HIV-1 patients circulating pDC up-regulate CCR7 expression, accumulate in lymph nodes, and express high amounts of IFNα before undergoing cell death. Since IFNα inhibits cell proliferation and modulates immune responses, chronically high levels of this cytokine in LN of HIV-1 patients may impair differentiation and immune function of bystander CD4+ T cells, thus playing into the mechanisms of AIDS immunopathogenesis.

Increased Interferon Alpha Expression in Circulating Plasmacytoid Dendritic Cells of HIV-1-Infected Patients

Background:The role of plasmacytoid dendritic cells (pDC) and interferon alpha (IFNα) in HIV-1 infection is still unclear. On one hand, HIV-1 disease is associated with a progressive decline of pDC, which displays reduced ability to produce IFNα after in vitro challenge. On the other hand, high IFNα serum levels in HIV-1-infected individuals have been proposed to promote immune hyper-activation and disease progression. Methods:We sought to determine whether disappearance of pDC in HIV-1 disease is due to homing in lymphoid tissues. We also studied IFNα and myxovirus resistance protein A (MxA) expression in unstimulated pDC and correlated these results with selected clinical and laboratory parameters. Results:We found that pDC decline markedly in peripheral blood of patients progressing to disease but at the same time express much higher levels of IFNα and MxA compared to control individuals. On the other hand, we observed steady pDC counts in lymph nodes of HIV-1 patients. The frequency of circulating pDC correlated directly with CD4 cell counts and inversely with viral load. However, we found no correlation between IFNα and MxA expression levels, CD4 counts, and viral load. Conclusions:Circulating pDC decline sharply in the course of HIV-1 disease, but express high levels of IFNα, which may represent a hallmark of systemic immune dysfunction.

Functional role of the 503F variant of the organic cation transporter OCTN1 in Crohn’s disease

Several susceptible gene loci were identified as being involved in the aetiology of Crohn’s disease (CD).1 Recently, a non-synonymous single nucleotide polymorphism in the SLC22A4 gene encoding the organic cation transporter OCTN1 has been linked with CD in Caucasian populations (a 1672CT transversion, resulting in the amino acid substitution L503F).2,3 However, the functional consequences of this alteration are unclear as yet. We have now discovered that L-ergothioneine (ET, 2-mercaptohistidine trimethylbetaine), a naturally occurring water soluble thiol compound of dietary origin, is the physiological substrate of OCTN1.4 Analysis of the concentration dependence of ET transport in OCTN1 transfected HEK293 fibroblasts by liquid chromatography tandem mass spectrometry revealed that the 503F variant was associated with a threefold higher substrate affinity (1/Km) and a twofold lower maximal transport velocity (Vmax), which resulted in a 50% higher initial transport capacity (Vmax/Km (503F) ≈ 1.5 × Vmax/Km (503L)) at low ET levels (⩽10 µmol/l) (fig 1A). Analysis of the time course of ET transport showed a higher clearance for …

Longitudinal Analysis of Distribution and Function of Plasmacytoid Dendritic Cells in Peripheral Blood and Gut Mucosa of HIV infected patients

Aberrant activation of plasmacytoid dendritic cells (pDCs) with excessive production of interferon alpha (IFNα) represents one of the hallmarks of immune activation during chronic phase of human immunodeficiency virus (HIV) infection. A number of studies have shown that disruption of mucosal integrity in the gut is a cause of persistent immune activation. However, little is known about the role that pDCs play in this process, and our current understanding comes from the simian immunodeficiency virus macaque model. Thus, in the present study we sought to investigate the frequency and function of pDCs in peripheral blood and gut samples from HIV-infected individuals before and 6 months after initiation of antiretroviral therapy (ART). We show that circulating pDCs were depleted in ART-naive HIV+ patients, and upregulated the gut-homing receptor CD103 compared with uninfected controls. By converse, pDCs accumulated in the terminal ileum of ART-naive HIV individuals compared with controls. Baseline levels of IFNα production and markers of immune activation in gut samples of ART-naive HIV subjects were elevated. All these parameters declined after 6 months of ART. Our results suggest that in chronic HIV infection, pDCs migrate from peripheral blood to the gut-associated lymphatic tissue, where they may contribute to immune activation.

Increased ergothioneine tissue concentrations in carriers of the Crohn’s disease risk-associated 503F variant of the organic cation transporter OCTN1

Accumulating evidence suggests that genetic susceptibility to Crohn’s disease (CD) is driven by loss-of-function mutations in established risk genes such as IBD5 , NOD2/CARD15 , ATG16L1 or IL23R conferring defects in the innate immune response.1 2 Within the IBD5 locus, a coding variant of the organic cation transporter OCTN1 ( SLC22A4 ) has been associated with the risk of CD in Caucasian populations.3 4 However, the causal involvement of OCTN1 in CD pathogenesis is unclear, because the OCTN1 variant is in linkage disequilibrium with other IBD5 alleles, in particular with a promoter variant of the carnitine transporter OCTN2 ( SLC22A5 ).3 We have previously demonstrated that the food ingredient ergothioneine (ET), not arising from mammalian metabolism or intestinal flora, represents the key substrate of OCTN15 and that the CD risk-associated variant 503F (1672T) exhibits a …

Preferential Upregulation of Interferon-α Subtype 2 Expression in HIV-1 Patients

Humans tailor virus-specific immune responses through modulated expression of 12 different interferon (IFN)-alpha subtypes. However, exacerbated expression of certain IFN-alpha subtypes causes immunopathology in the context of autoimmune conditions and chronic viral infections. We showed that progression to AIDS is associated with elevated expression of IFN-alpha in unstimulated peripheral blood mononuclear cells. Here, we sought to determine whether distinct IFN-alpha subtypes are involved in this phenomenon. We used quantitative RT-PCR to assess expression levels of 12 IFN-alpha subtypes in peripheral blood mononuclear cells from normal donors and HIV-1 patients at CDC stage A and stage C of the disease. Three patterns of IFN-alpha subtype expression emerged. First, IFN-alpha2 and IFN-alpha6 mRNA levels were elevated in both patient groups. Second, IFN-alpha1/13, IFN-alpha8, IFN-alpha14, IFN-alpha16, IFN-alpha17, and IFN-alpha21 were upregulated in stage C but not stage A patients. Third, expression levels of IFN-alpha4, IFN-alpha5, IFN-alpha7, and IFN-alpha10 did not change among the three groups of volunteers. Among all other subtypes, IFN-alpha2 was preferentially upregulated, showing >60-fold higher levels in stage A and >400-fold in stage C patients compared with controls, which correlated with declining CD4 counts. Our results demonstrate that distinct IFN-alpha subtypes are sequentially activated during HIV-1 infection, which may be predictive of disease progression.

Successful treatment of rheumatoid vasculitis-associated cutaneous ulcers using rituximab in two patients with rheumatoid arthritis

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Sex differences in immune responses to infectious diseases.

PurposeThe influence of sex hormones is recognized to account for the susceptibility and distinct outcomes of diverse infectious diseases.MethodsThis review discusses several variables including differences in behavior and exposure to pathogens, genetic, and immunological factors.ConclusionUnderstanding sex-based differences in immunity during different infectious diseases is crucial in order to provide optimal disease management for both sexes.