@article {10504, title = {Multicentric Case-Control Study on Azathioprine Dose and Pharmacokinetics in Early-onset Pediatric Inflammatory Bowel Disease.}, journal = {Inflamm Bowel Dis}, volume = {23}, year = {2017}, month = {2017 04}, pages = {628-634}, abstract = {

BACKGROUND: Early-onset inflammatory bowel disease (IBD) is generally aggressive, with a high probability of complications and need of surgery. Despite the introduction of highly effective biological drugs, treatment with azathioprine continues to be important even for early-onset IBD; however, in these patients azathioprine response seems to be reduced. This study evaluated azathioprine doses, metabolite concentrations, and their associations with patients{\textquoteright} age in children with IBD treated at 6 tertiary pediatric referral centers.

METHODS: Azathioprine doses, metabolites, and clinical effects were assessed after at least 3 months of therapy in 17 early-onset (age < 6 yr, cases) and 51 nonearly-onset (aged > 12 and <18 yrs, controls) patients with IBD. Azathioprine dose was titrated on therapeutic efficacy (response and adverse effects). Azathioprine metabolites and thiopurine methyltransferase activity were determined by high-performance liquid chromatography with ultra violet-vis detection (HPLC-UV) methods.

RESULTS: Frequency of patients in remission was similar among early-onset and control groups, respectively (82\% and 84\%, P value = 0.72). Early-onset patients required higher doses of azathioprine (median 2.7 versus 2.0 mg{\textperiodcentered}kg{\textperiodcentered}d, P value = 1.1 {\texttimes} 10). Different doses resulted in comparable azathioprine active thioguanine nucleotide metabolite concentrations (median 263 versus 366 pmol/8 {\texttimes} 10 erythrocytes, P value = 0.41) and methylmercaptopurine nucleotide concentrations (median 1455 versus 1532 pmol/8 {\texttimes} 10 erythrocytes, P value = 0.60). Lower ratios between thioguanine nucleotide metabolites and azathioprine doses were found in early-onset patients (median 98 versus 184 pmol/8 {\texttimes} 10 erythrocytes{\textperiodcentered}mg{\textperiodcentered}kg{\textperiodcentered}d, P value = 0.017). Interestingly, early-onset patients presented also higher thiopurine methyltransferase activity (median 476 versus 350 nmol methylmercaptopurine/mg hemoglobin/h, P-value = 0.046).

CONCLUSIONS: This study demonstrated that patients with early-onset IBD present increased inactivating azathioprine metabolism, likely because of elevated activity of the enzyme thiopurine methyltransferase.

}, keywords = {Adolescent, Age of Onset, Antimetabolites, Azathioprine, Case-Control Studies, Child, Child, Preschool, Chromatography, High Pressure Liquid, Dose-Response Relationship, Drug, Erythrocytes, Female, Guanine Nucleotides, Humans, Inflammatory Bowel Diseases, Male, Mercaptopurine, Methyltransferases, Thioguanine}, issn = {1536-4844}, doi = {10.1097/MIB.0000000000001051}, author = {Stocco, Gabriele and Martelossi, Stefano and Arrigo, Serena and Barabino, Arrigo and Aloi, Marina and Martinelli, Massimo and Miele, Erasmo and Knafelz, Daniela and Romano, Claudio and Naviglio, Samuele and Favretto, Diego and Cuzzoni, Eva and Franca, Raffaella and Decorti, Giuliana and Ventura, Alessandro} } @article {1742, title = {Molecular mechanism of glucocorticoid resistance in inflammatory bowel disease.}, journal = {World J Gastroenterol}, volume = {17}, year = {2011}, month = {2011 Mar 7}, pages = {1095-108}, abstract = {

Natural and synthetic glucocorticoids (GCs) are widely employed in a number of inflammatory, autoimmune and neoplastic diseases, and, despite the introduction of novel therapies, remain the first-line treatment for inducing remission in moderate to severe active Crohn{\textquoteright}s disease and ulcerative colitis. Despite their extensive therapeutic use and the proven effectiveness, considerable clinical evidence of wide inter-individual differences in GC efficacy among patients has been reported, in particular when these agents are used in inflammatory diseases. In recent years, a detailed knowledge of the GC mechanism of action and of the genetic variants affecting GC activity at the molecular level has arisen from several studies. GCs interact with their cytoplasmic receptor, and are able to repress inflammatory gene expression through several distinct mechanisms. The glucocorticoid receptor (GR) is therefore crucial for the effects of these agents: mutations in the GR gene (NR3C1, nuclear receptor subfamily 3, group C, member 1) are the primary cause of a rare, inherited form of GC resistance; in addition, several polymorphisms of this gene have been described and associated with GC response and toxicity. However, the GR is not self-standing in the cell and the receptor-mediated functions are the result of a complex interplay of GR and many other cellular partners. The latter comprise several chaperonins of the large cooperative hetero-oligomeric complex that binds the hormone-free GR in the cytosol, and several factors involved in the transcriptional machinery and chromatin remodeling, that are critical for the hormonal control of target genes transcription in the nucleus. Furthermore, variants in the principal effectors of GCs (e.g. cytokines and their regulators) have also to be taken into account for a comprehensive evaluation of the variability in GC response. Polymorphisms in genes involved in the transport and/or metabolism of these hormones have also been suggested as other possible candidates of interest that could play a role in the observed inter-individual differences in efficacy and toxicity. The best-characterized example is the drug efflux pump P-glycoprotein, a membrane transporter that extrudes GCs from cells, thereby lowering their intracellular concentration. This protein is encoded by the ABCB1/MDR1 gene; this gene presents different known polymorphic sites that can influence its expression and function. This editorial reviews the current knowledge on this topic and underlines the role of genetics in predicting GC clinical response. The ambitious goal of pharmacogenomic studies is to adapt therapies to a patient{\textquoteright}s specific genetic background, thus improving on efficacy and safety rates.

}, keywords = {Drug Resistance, Glucocorticoids, Humans, Inflammatory Bowel Diseases, P-Glycoproteins, Polymorphism, Genetic, Receptors, Glucocorticoid, Signal Transduction, Transcription, Genetic}, issn = {2219-2840}, doi = {10.3748/wjg.v17.i9.1095}, author = {De Iudicibus, Sara and Franca, Raffaella and Martelossi, Stefano and Ventura, Alessandro and Decorti, Giuliana} }