Revisiting the nature and pharmacodynamics of tacrolimus metabolites.

The toxicity of tacrolimus metabolites and their potential pharmacodynamic (PD) interactions with tacrolimus might respectively explain the surprising combination of higher toxicity and lower efficacy of tacrolimus despite normal blood concentrations, described in extensive metabolizers. To evaluate such interactions, we produced tacrolimus metabolites in vitro and characterized them by high resolution mass spectrometry (HRMS, for all) and nuclear magnetic resonance (NMR, for the most abundant, M-I). We quantified tacrolimus metabolites and checked their structure in patient whole blood and peripheral blood mononuclear cells (PBMC).

Gut microbiota biotransformation of drug glucuronides leading to gastrointestinal toxicity: Therapeutic potential of bacterial β-glucuronidase inhibition in mycophenolate-induced enteropathy.

Aims: Drug-induced enteropathy is often associated with the therapeutic use of certain glucuronidated drugs. One such drug is mycophenolic acid (MPA), a well-established immunosuppressant of which gastrointestinal adverse effects are a major concern. The role of bacterial β-glucuronidase (β-G) from the gut microbiota in MPA-induced enteropathy has recently been discovered.

A multi-omics investigation of tacrolimus off-target effects on a proximal tubule cell-line.

Introduction: Tacrolimus, an immunosuppressive drug prescribed to a majority of organ transplant recipients is nephrotoxic, through still unclear mechanisms. This study on a lineage of proximal tubular cells using a multi-omics approach aims to detect off-target pathways modulated by tacrolimus that can explain its nephrotoxicity.

Methods: LLC-PK1 cells were exposed to 5 µM of tacrolimus for 24 h in order to saturate its therapeutic target FKBP12 and other high-affine FKBPs and favour its binding to less affine targets.

Substrate binding and lipid-mediated allostery in the human organic anion transporter 1 at the atomic-scale.

The Organic Anion Transporter 1 is a membrane transporter known for its central role in drug elimination by the kidney. hOAT1 is an antiporter translocating substrate in exchange for a-ketoglutarate. The understanding of hOAT1 structure and function remains limited due to the absence of resolved structure of hOAT1.

Perfusate Metabolomics Content and Expression of Tubular Transporters During Human Kidney Graft Preservation by Hypothermic Machine Perfusion.

Background: Ischemia-related injury during the preimplantation period impacts kidney graft outcome. Evaluating these lesions by a noninvasive approach before transplantation could help us to understand graft injury mechanisms and identify potential biomarkers predictive of graft outcomes. This study aims to determine the metabolomic content of graft perfusion fluids and its dependence on preservation time and to explore whether tubular transporters are possibly involved in metabolomics variations.

MRP4 is responsible for the efflux transport of mycophenolic acid β-d glucuronide (MPAG) from hepatocytes to blood.

Mycophenolic acid (MPA) has become a cornerstone of immunosuppressive therapy, in particular for transplant patients. In the gastrointestinal tract, the liver and the kidney, MPA is mainly metabolized into phenyl-β-d glucuronide (MPAG). Knowledge about the interactions between MPA/MPAG and membrane transporters is still fragmented.

Cyclosporine A inhibits MRTF-SRF signaling through Na/K ATPase inhibition and actin remodeling.

Calcineurin inhibitors (CNI) are the pillars of immunosuppression in transplantation. However, they display a potent nephrotoxicity whose mechanisms remained widely unsolved. We used an untargeted quantitative proteomic approach (iTRAQ technology) to highlight new targets of CNI in renal proximal tubular cells (RPTCs).

Effect of genetic polymorphisms in CYP3A4, CYP3A5, and m-TOR on everolimus blood exposure and clinical outcomes in cancer patients.

Genetic variations in CYP3A4, CYP3A5, and m-TOR could contribute to interpatient variability regarding m-TOR inhibitors pharmacokinetics or cellular effects. The purpose of this study was to evaluate the influence of selected candidate variations in these genes on everolimus pharmacokinetics, efficacy, and toxicity in cancer patients. Thirty-four patients receiving everolimus for breast (n = 22) or renal (n = 10) cancers, or neuroendocrine tumors of pancreatic origin (n = 2) were included in the study.

Multidrug resistance-associated protein 4 in pharmacology: Overview of its contribution to pharmacokinetics, pharmacodynamics and pharmacogenetics.

MRP4 is an ABC membrane transporter involved in clinical outcomes as it is located in many tissues that manages the transport and the elimination of many drugs. This review explores the implication of MRP4 in clinical pharmacology and the importance of its genetic variability. Although there is no specific recommendation regarding the study of MRP4 in drug development, it should be considered when drugs are eliminated by the kidney or liver or when drug-drug interactions are expected.

Sum of peak intensities outperforms peak area integration in iTRAQ protein expression measurement by LC-MS/MS using a TripleTOF 5600+ platform.

In the field of quantitative proteomics, the Isobaric Tags for Relative and Absolute Quantitation (iTRAQ) technology has demonstrated efficacy for proteome monitoring despite its lack of a consensus for data handling. In the present study, after peptide and protein identification, we compared the widespread quantitation method based on the calculation of MS/MS reporter ion peaks areas ratios (ProteinPilot) to the alternative method based on the calculation of ratios of the sum of peak intensities (jTRAQx [Quant]) and we processed output data with the in-house Customizable iTRAQ Ratios Calculator (CiR-C) algorithm. Quantitation based on peak area ratios displayed no significant linear correlation with Western blot quantitation.

A donor and recipient candidate gene association study of allograft loss in renal transplant recipients receiving a tacrolimus-based regimen.

This work investigated, in two large cohorts of French renal transplants treated with tacrolimus, the influence of donor and recipient ABCB1, CYP3A4, and CYP3A5 genotypes on the risk of allograft loss. A discovery and a replication population of 330 and 369 adult renal transplant patients, each from a different transplantation center and all receiving a tacrolimus-based immunosuppressive regimen, were retrospectively genotyped. The influence of genetic factors and other known risk factors on allograft loss was investigated using multivariate Cox proportional hazard analyses.

Recruitment of 7SL RNA to assembling HIV-1 virus-like particles.

Retroviruses incorporate specific host cell RNAs into virions. In particular, the host noncoding 7SL RNA is highly abundant in all examined retroviruses compared with its cellular levels or relative to common mRNAs such as actin. Using live cell imaging techniques, we have determined that the 7SL RNA does not arrive with the HIV-1 RNA genome.

Mechanistic insights into type I toxin antitoxin systems in Helicobacter pylori: the importance of mRNA folding in controlling toxin expression.

Type I toxin-antitoxin (TA) systems have been identified in a wide range of bacterial genomes. Here, we report the characterization of a new type I TA system present on the chromosome of the major human gastric pathogen, Helicobacter pylori. We show that the aapA1 gene encodes a 30 amino acid peptide whose artificial expression in H.

Analysis of the human immunodeficiency virus-1 RNA packageome.

All retroviruses package cellular RNAs into virions. Studies of murine leukemia virus (MLV) revealed that the major host cell RNAs encapsidated by this simple retrovirus were LTR retrotransposons and noncoding RNAs (ncRNAs). Several classes of ncRNAs appeared to be packaged by MLV shortly after synthesis, as precursors to tRNAs, small nuclear RNAs, and small nucleolar RNAs were all enriched in virions.

RNase J depletion leads to massive changes in mRNA abundance in Helicobacter pylori.

Degradation of RNA as an intermediate message between genes and corresponding proteins is important for rapid attenuation of gene expression and maintenance of cellular homeostasis. This process is controlled by ribonucleases that have different target specificities. In the bacterial pathogen Helicobacter pylori, an exo- and endoribonuclease RNase J is essential for growth.