Thiopurine Drugs in the Treatment of Ulcerative Colitis: Identification of a Novel Deleterious Mutation in TPMT

Influence of TPMT and NUDT15 Genetic Polymorphisms on Mercaptopurine Pharmacokinetics in Healthy Volunteers

Aims: This study aimed to investigate the impact of genetic polymorphisms of thiopurine methyltransferase (TPMT) and NUDT15 on pharmacokinetics profile of mercaptopurine in healthy adults in China. Methods: Blood samples were obtained from 45 healthy adult volunteers who were administered azathioprine. Genomic DNA was extracted and sequenced for TPMT and NUDT15. The plasma concentrations of 6-mercaptopurine (6-MP) were determined by ultra-performance liquid chromatography-tandem mass spectrometry. Finally, pharmacokinetic parameters were calculated based on the time-concentration curve. Results: Among the 45 healthy adult volunteers enrolled in the study, two TPMT allelic variants and three NUDT15 allelic variants were detected. In total, six genotypes were identified, including TPMT*1/*1&NUDT15*1/*1, TPMT*1/*1&NUDT15*1/*2, TPMT*1/*1&NUDT15*1/*9, TPMT*1/*1&NUDT15*2/*5, TPMT*1/*6&NUDT15*1/*2, and TPMT*1/*3&NUDT15*1/*2. The results indicated that Area Under Curve (AUC) of 6-MP in volunteers with TPMT*1/*3&NUDT15*1/*2 and TPMT*1/*6&NUDT15*1/*2 were 1.57-1.62-fold higher than in individuals carrying the wild type (TPMT*1/*1&NUDT15*1/*1). Compared with wild type, the half-life (T1/2) of TPMT*1/*6&NUDT15*1/*2 was extended by 1.98 times, whereas T1/2 of TPMT*1/*3&NUDT15*1/*2 decreased by 67%. The maximum concentration (Cmax) of TPMT*1/*3&NUDT15*1/*2 increased significantly by 2.15-fold, whereas the corresponding clearance (CL/F) decreased significantly by 58.75%. Conclusion: The findings of this study corroborate the notion that various genotypes of TPMT and NUDT15 can impact the pharmacokinetics of mercaptopurine, potentially offering foundational insights for personalized mercaptopurine therapy.

The Lactobacillus plantarum P-8 Probiotic Microcapsule Prevents DSS-Induced Colitis through Improving Intestinal Integrity and Reducing Colonic Inflammation in Mice

Probiotics, recognized as beneficial and active microorganisms, often face challenges in maintaining their functionality under harsh conditions such as exposure to stomach acid and bile salts. In this investigation, we developed probiotic microcapsules and assessed their protective effects and underlying mechanisms in a murine model of dextran sulfate sodium (DSS)-induced colitis using male C57BL/6J mice. The administration of the probiotic microcapsules significantly mitigated body weight loss, prevented colon length shortening, decreased the disease activity index scores, and reduced histopathological scores in mice with DSS-induced colitis. Concurrently, the microencapsulated probiotics preserved intestinal barrier integrity by upregulating the expressions of tight junction proteins ZO-1 and occludin, as well as the mucus layer component MUC-2. Moreover, the treatment with probiotic microcapsules suppressed the activation of the NLRP3 inflammasome signaling pathway in the context of DSS-induced colitis. In conclusion, these findings support the utilization of probiotic microcapsules as a potential functional food ingredient to maintain the permeability of the intestinal barrier and alleviate colonic inflammation in UC.

SERS spectroscopy as a tool for the study of thiopurine drug pharmacokinetics in a model of human B leukemia cells

Thiopurine drugs are immunomodulatory antimetabolites relevant for pediatric patients characterized by dose-dependent adverse effects such as myelosuppression and hepatotoxicity, often related to inter-individual differences, involving the activity of important enzymes at the basis of their biotransformation, such as thiopurine S-methyltransferase (TPMT). Surface Enhanced Raman Scattering (SERS) spectroscopy is emerging as a bioanalytical tool and represents a valid alternative in terms of affordable costs, shorter analysis time and easier sample preparation in comparison to the most employed methods for pharmacokinetic analysis of drugs. The aim of this study is to investigate mercaptopurine and thioguanine pharmacokinetics by SERS in cell lysates of a B-lymphoblastoid cell line (NALM-6), that did (TPMT*1) or did not (MOCK) overexpress the wild-type form of TPMT as an in vitro cellular lymphocyte model to discriminate between cells with different levels of TPMT activity on the base of the amount of thioguanosine nucleotides (TGN) metabolites formed. SERS analysis of the cell lysates was carried out using SERS substrates constituted by Ag nanoparticles deposited on paper and parallel samples were used for quantification of thiopurine nucleotides with liquid chromatography-tandem mass spectrometry (LC-MS/MS). A direct SERS detection method has been set up that could be a tool to study thiopurine drug pharmacokinetics in in vitro cellular models to qualitatively discriminate between cells that do and do not overexpress the TPMT enzyme, as an alternative to other more laborious techniques. Results underlined decreased levels of TGN and increased levels of methylated metabolites when TPMT was overexpressed, both after mercaptopurine and thioguanine treatments. A strong positive correlation (Spearman's rank correlation coefficient rho = 0.96) exists between absolute quantification of TGMP (pmol/1 x 106 cells), obtained by LC-MS/MS, and SERS signal (intensity of TGN at 915 cm-1). In future studies, we aim to apply this method to investigate TPMT activity in pediatric patients' leukocytes.

3D Printed Personalized Colon-targeted Tablets: A Novel Approach in Ulcerative Colitis Management

Ulcerative colitis (UC) and Crohn's disease (CD) are two types of idiopathic inflammatory bowel disease (IBD) that are increasing in frequency and incidence worldwide, particularly in highly industrialized countries. Conventional tablets struggle to effectively deliver anti-inflammatory drugs since the inflammation is localized in different areas of the colon in each patient. The goal of 3D printing technology in pharmaceutics is to create personalized drug delivery systems (DDS) that are tailored to each individual's specific needs. This review provides an overview of existing 3D printing processes, with a focus on extrusion-based technologies, which have received the most attention. Personalized pharmaceutical products offer numerous benefits to patients worldwide, and 3D printing technology is becoming more affordable every day. Custom manufacturing of 3D printed tablets provides innovative ideas for developing a tailored colon DDS. In the future, 3D printing could be used to manufacture personalized tablets for UC patients based on the location of inflammation in the colon, resulting in improved therapeutic outcomes and a better quality of life.

Concomitant 5-aminosalicylic acid treatment does not affect 6-thioguanine nucleotide levels in patients with inflammatory bowel disease on thiopurines

Background

There are conflicting data as to whether co-treatment with 5-aminosalicylic acid (5-ASA) in patients with inflammatory bowel disease (IBD) under azathioprine (AZA) or 6-mercaptopurine (6-MP) therapy may influence 6-thioguanine nucleotide (6-TGN) concentrations, and whether this combination puts patients at risk of side-effects. The aim of the study was to determine 6-TGN levels in patients treated with AZA/6-MP, either alone or in combination with 5-ASA.

Methods

Available blood samples from patients treated with AZA or 6-MP were retrieved from the Swiss IBD Cohort Study (SIBDCS). The eligible individuals were divided into 2 groups: those with vs. without 5-ASA co-medication. Levels of 6-TGN and 6-methylmercaptopurine ribonucleotides (6-MMPR) were determined and compared. Potential confounders were compared between the groups, and also evaluated as potential predictors for a multivariate regression model.

Results

Of the 110 patients enrolled in this analysis, 40 received concomitant 5-ASA at the time of blood sampling. The median 6-TGN levels in patients with vs. those without 5-ASA co-treatment were 261 and 257 pmol/8×108 erythrocytes, respectively (P=0.97). Likewise, there were no significant differences in 6-MMPR levels (P=0.79). Through multivariate analysis, 6-TGN levels were found to be significantly higher in non-smokers, patients without prior surgery, and those without signs of stress-hyperarousal.

Conclusions

Blood concentrations of 6-TGN and 6-MMPR did not differ between patients with vs. those without 5-ASA co-treatment. Our data warrant neither more frequent lab monitoring nor dose adaptation of AZA in patients receiving concomitant 5-ASA treatment.

Pharmacogenetic Effect of Thiopurine Methyl Transferase (TPMT) Gene Expression and Serum TNF on the Imuran Response in Ulcerative Colitis (UC) Iraqi Patients

Background

Ulcerative colitis (UC), a chronic inflammatory bowel disease (IBD), exerts its impact on both rectal and colonic mucosa, with a growing incidence. This study aims to explore the pharmacogenetic influence of thiopurine methyl transferase (TPMT) gene expression and serum tumor necrosis factor (TNF) levels on the response to Imuran in Iraqi patients with UC.

Methods

Seventy individuals with chronic UC and 30 healthy controls were enrolled in this investigation. RNA extraction using the triazole method and enzyme-linked immunosorbent assay (ELISA) for TNF measurement were employed. Patients, aged 15-50 years, underwent Imuran treatment.

Results

Diverse responses to Imuran were observed among patients, with TPMT gene expression levels below 1 in 35 patients leading to side effects, while the remaining 35 patients exhibited positive responses with TPMT gene expression exceeding 1. Patients with varying degrees of severe, moderate, and mild UC associated with TNF showed a significant correlation with Imuran non-response.

Conclusions

A distinct correlation was identified between TPMT gene expression and Imuran therapy outcomes in UC patients. Further investigation is warranted to elucidate the underlying mechanism, positioning the TPMT gene as a potential therapeutic target for mitigating the impact of UC.

Investigating the Metabolic Mechanisms of Butaselen, An Ebselen Analog

BACKGROUND

Butaselen is an ebselen analog that is under clinical trials for treating hepatic and pulmonary fibrosis. Our previous studies showed that butaselen is mainly present in human plasma in the form of M2, a free Se-methylated metabolite.

OBJECTIVE

This study aimed to investigate the metabolic mechanisms of butaselen.

METHODS AND RESULTS

Butaselen was incubated with human plasma. Butaselen immediately disappeared, and the butaselen-HSA (human serum albumin) adduct was detected by HPLC-HRMS, showing that butaselen covalently binds to HSA. The butaselen-HSA adduct was precipitated using acetonitrile and then incubated with PBS, Cys, and GSH for 1 hour. The product was M1, a reduced form of butaselen. The results indicated that HSA, Cys, and GSH can reduce the butaselen-HSA covalent bond. The binding site for butaselen could be the cysteine-34 residue of HSA through pronase and trypsin hydrolysis. Incubating butaselen with cysteine, butaselen-Cys, butaselen-2Cys, and M1 were generated, indicating the covalent binding and reduction of butaselen by cysteine. We incubated liver microsomes and cytosol with butaselen, 6.22 and 246 nM M2 were generated, respectively. The results demonstrated that cytosolic enzymes are mainly involved in M2 production. The amount of M2 in the liver cytosol decreased from 246 nM to 2.21 nM when 10 mM m-anisic acid (a specific TPMT enzyme inhibitor) was added, showing that TPMT is responsible for M2 formation.

CONCLUSION

Butaselen was covalently bound to HSA, and the binding site was the cysteine-34 residue of HSA. The butaselen-HSA adduct was reduced by free thiol compounds to generate M1. M1 was further metabolized to M2 by cytosolic TPMT. This study provides a basis for studying the pharmacokinetics of selenium-containing drugs.

Cytotoxicity of Thiopurine Drugs in Patients with Inflammatory Bowel Disease

The effectiveness of thiopurine drugs in inflammatory bowel disease (IBD) was confirmed more than a half-century ago. It was proven that these can be essential immunomodulatory medications. Since then, they have been used routinely to maintain remission of Crohn’s disease (CD) and ulcerative colitis (UC). The cytotoxic properties of thiopurines and the numerous adverse effects of the treatment are controversial. However, the research subject of their pharmacology, therapy monitoring, and the search for predictive markers are still very relevant. In this article, we provide an overview of the current knowledge and findings in the field of thiopurines in IBD, focusing on the aspect of their cytotoxicity. Due to thiopurines’ benefits in IBD therapy, it is expected that they will still constitute an essential part of the CD and UC treatment algorithm. More studies are still required on the modulation of the action of thiopurines in combination therapy and their interaction with the gut microbiota.

Probiotic Bacillus cereus Alleviates Dextran Sulfate Sodium-Induced Colitis in Mice through Improvement of the Intestinal Barrier Function, Anti-Inflammation, and Gut Microbiota Modulation

Dysbiosis leads to continuous progress of inflammatory bowel disease (IBD). However, current therapeutic approaches for IBD have limited efficacy and are associated with various side effects. This study focused on exploring the positive effect of a new Bacillus cereus (B. cereus) strain (HMPM18123) in a colitis mouse model and elucidate the underlying molecular mechanisms. The colitis symptoms were alleviated by the B. cereus administration as evidenced by decreased body weight loss, colon length shortening, disease activity index score, and histopathological score. The B. cereus mitigated intestinal epithelial barrier damage by upregulating tight junction protein expression. Moreover, B. cereus exerted anti-inflammatory effects by regulating macrophage polarization and suppressing the TLR4-NF-κB-NLRP3 inflammasome signaling pathways. B. cereus also rebalanced the damaged gut microbiota. Thus, the molecular mechanism of alleviating colitis by B. cereus treatment involved the regulation of the TLR4-NF-κB-NLRP3 inflammasome signaling pathways in intestinal mucosal barriers by modulating gut microbiota composition.