Functional variants of OCTN cation transporter genes are associated with Crohn disease

Drug Transporters and Na+/H+ Exchange Regulatory Factor PSD-95/Drosophila Discs Large/ZO-1 Proteins

Drug transporters govern the absorption, distribution, and elimination of pharmacologically active compounds. Members of the solute carrier and ATP binding-cassette drug transporter family mediate cellular drug uptake and efflux processes, thereby coordinating the vectorial movement of drugs across epithelial barriers. To exert their physiologic and pharmacological function in polarized epithelia, drug transporters must be targeted and stabilized to appropriate regions of the cell membrane (i.e., apical versus basolateral). Despite the critical importance of drug transporter membrane targeting, the mechanisms that underlie these processes are largely unknown. Several clinically significant drug transporters possess a recognition sequence that binds to PSD-95/Drosophila discs large/ZO-1 (PDZ) proteins. PDZ proteins, such as the Na(+)/H(+) exchanger regulatory factor (NHERF) family, act to stabilize and organize membrane targeting of multiple transmembrane proteins, including many clinically relevant drug transporters. These PDZ proteins are normally abundant at apical membranes, where they tether membrane-delimited transporters. NHERF expression is particularly high at the apical membrane in polarized tissue such as intestinal, hepatic, and renal epithelia, tissues important to drug disposition. Several recent studies have highlighted NHERF proteins as determinants of drug transporter function secondary to their role in controlling membrane abundance and localization. Mounting evidence strongly suggests that NHERF proteins may have clinically significant roles in pharmacokinetics and pharmacodynamics of several pharmacologically active compounds and may affect drug action in cancer and chronic kidney disease. For these reasons, NHERF proteins represent a novel class of post-translational mediators of drug transport and novel targets for new drug development.

PROBIOTIC APPROACHES FOR TARGETING INFLAMMATORY BOWEL DISEASE: AN UPDATE ON ADVANCES AND OPPORTUNITIES IN MANAGING THE DISEASE

Various commensal enteric and pathogenic bacteria may be involved in the pathogenesis of inflammatory bowel diseases (IBDs), a chronic condition with a pathogenic background that involves both immunogenetic and environmental factors. IBDs comprising of Crohn's disease, and ulcerative colitis, and pauchitis are chronic inflammatory conditions, and known for causing disturbed homeostatic balance among the intestinal immune compartment, gut epithelium and microbiome. An increasing trend of IBDs in incidence, prevalence, and severity has been reported during recent years. Probiotic strains have been reported to manage the IBDs and related pathologies, and hence are current hot topics of research for their potential to manage metabolic diseases as well as various immunopathologies. However, the probiotics industry will need to undergo a transformation, with increased focus on stringent manufacturing guidelines and high-quality clinical trials. This article reviews the present state of art of role of probiotic bacteria in reducing inflammation and strengthening the host immune system with reference to the management of IBDs. We infer that t healthcare will move beyond its prevailing focus on human physiology, and embrace the superorganism as a paradigm to understand and ameliorate IBDs.

Acetylcholine and acetylcarnitine transport in peritoneum: Role of the SLC22A4 (OCTN1) transporter

A suitable experimental tool based on proteoliposomes for assaying Organic Cation Transporter Novel member 1 (OCTN1) of peritoneum was pointed out. OCTN1, recently acknowledged as acetylcholine transporter, was immunodetected in rat peritoneum. Transport was assayed following flux of radiolabelled TEA, acetylcholine or acetylcarnitine in proteoliposomes reconstituted with peritoneum extract. OCTN1 mediated, besides TEA, also acetylcholine and a slower acetylcarnitine transport. External sodium inhibited acetylcholine uptake but not its release from proteoliposomes. Differently, sodium did not affect acetylcarnitine uptake. These results suggested that physiologically, acetylcholine should be released while acetylcarnitine was taken up by peritoneum cells. Transport was impaired by OCTN1 inhibitors, butyrobetaine, spermine, and choline. Biotin was also found as acetylcholine transport inhibitor. Anti-OCTN1 antibody specifically inhibited acetylcholine transport confirming the involvement of OCTN1. The transporter was also immunodetected in human mesothelial primary cells. Extract from these cells was reconstituted in proteoliposomes. Transport features very similar to those found with rat peritoneum were observed. Validation of the proteoliposome model for peritoneal transport study was then achieved assaying transport in intact mesothelial cells. TEA, butyrobetaine and Na(+) inhibited acetylcholine transport in intact cells while efflux was Na(+) insensitive. Therefore transport features in intact cells overlapped those found in proteoliposomes.

Association of single nucleotide polymorphism rs3792876 in SLC22A4 gene with autoimmune thyroid disease in a Chinese Han population

Background

The autoimmune thyroid diseases (AITD), including Graves’ disease (GD) and Hashimoto’s thyroiditis (HT), are caused by interactions between susceptibility genes and environmental triggers. Single nucleotide polymorphisms (SNPs) of Solute carrier family 22, member 4 (SLC22A4) have been shown to be associated with several autoimmune diseases, including Crohn’s disease (CD) and rheumatoid arthritis (RA). The aim of this study is to investigate whether SNP rs3792876 in the SLC22A4 gene is associated with GD, HT and AITD in a Chinese Han population.

Methods

In this study, we collected specimens from 553 Chinese Han individuals of 92 AITD pedigrees in 10 cities in Liaoning province, China (80 GD pedigrees, 478 members; 12 HT pedigrees, 75 members). SNP rs3792876 was genotyped using the TaqMan allelic discrimination assay. Hardy-Weinberg Equilibrium tests were performed among founders of the pedigrees using Haploview software. Family-based association tests performed using FBAT software.

Results

No deviation from Hardy-Weinberg equilibrium was observed (p > 0.05). There were not significant association between the SLC22A4 gene polymorphism (rs3792876) and GD, HT and AITD was found.

Conclusions

These results suggest a lack of association between the SLC22A4 gene polymorphism rs3792876 and susceptibility to GD, HT and AITD in a Chinese Han population.

OCT1 and imatinib transport in CML: is it clinically relevant?

Imatinib is a highly effective therapy for chronic phase-chronic myeloid leukaemia (CP-CML) patients; however, responses to frontline imatinib are variable. The human organic cation transporter 1 (OCT1; SLC22A1) has been reported to be the main influx transporter involved in imatinib uptake into CML cells. Furthermore, variation in the efficiency of imatinib influx via OCT1 has been demonstrated to result in the inter-patient variation observed in primary response to imatinib. Although studies have questioned the role of OCT1 in imatinib influx, these have been largely performed in non-clinical settings. Measuring both OCT1 mRNA levels and the functional activity of OCT1 in primary leukaemic cells has been demonstrated to predict molecular response and outcome in imatinib-treated CP-CML patients in several independent studies. Here, the role of OCT1 and OCT1 genetic variants in imatinib uptake and response prediction is summarised and data generated from model systems assessing the role of OCT1 in imatinib transport is discussed.

Association of TOMM40 and SLC22A4 polymorphisms with ischemic stroke

Recent genome-wide association studies (GWASs) and their meta-analyses have identified various genes and loci underlying the predisposition to ischemic stroke or coronary artery disease in Caucasian populations. Given that ischemic stroke and coronary artery disease may have a shared genetic architecture, certain polymorphisms may confer genetic susceptibility to these two diseases. The aim of the present study was to examine the possible association of ischemic stroke with 29 single-nucleotide polymorphisms (SNPs) previously identified by the meta-analyses of GWASs as susceptibility loci for coronary artery disease. The study population comprised 3,187 Japanese individuals, including 894 subjects with ischemic stroke and 2,293 controls. The genotypes for the 29 SNPs of the 28 genes were determined by a method that combines the polymerase chain reaction and sequence-specific oligonucleotide probes with suspension array technology. Comparisons of the allele frequencies by the χ² test between subjects with ischemic stroke and controls revealed that rs9319428 (G→A) of the fms-related tyrosine kinase 1 gene (P=0.0471), rs2075650 (G→A) of the translocase of outer mitochondrial membrane 40 homolog gene (TOMM40, P=0.0102) and rs273909 (T→C) of the solute carrier family 22, member 4 gene (SLC22A4, P=0.0097) were significantly (P<0.05) associated with the prevalence of ischemic stroke. Multivariable logistic regression analysis with adjustment for age, gender, body mass index, smoking status and the prevalence of hypertension, diabetes mellitus and dyslipidemia revealed that rs2075650 of TOMM40 (P=0.0443; recessive model; odds ratio=0.50) and rs273909 of SLC22A4 (P=0.0123; dominant model; odds ratio=0.45) were significantly associated with ischemic stroke with the minor G and C allele, respectively, being protective against this condition. TOMM40 and SLC22A4 may thus be susceptibility loci for ischemic stroke in Japanese individuals.

Organic cation transporter Octn1-mediated uptake of food-derived antioxidant ergothioneine into infiltrating macrophages during intestinal inflammation in mice

OCTN1/SLC22A4 is expressed on apical membranes of small intestine, and is involved in gastrointestinal absorption of its substrates, including the food-derived antioxidant ergothioneine (ERGO). ERGO concentration in circulating blood of patients with inflammatory bowel disease (Crohn's disease) is lower than that in healthy volunteers; thus, circulating ERGO is a potential diagnostic marker, although the mechanisms underlying low ERGO concentration in patients are unknown. Here, we focused on intestinal macrophages, which infiltrate sites of inflammation, and examined possible first-pass uptake of ERGO by macrophages. ERGO concentration in blood was lower in mice with dextran sodium sulfate (DSS)-induced colitis than in controls. On the other hand, expression of octn1 gene product and ERGO concentration in intestinal tissues of DSS-treated mice were higher than in controls. Interestingly, lamina propria mononuclear cells (LPMCs) isolated from DSS-treated mice contained ERGO and showed [(3)H]ERGO uptake and Octn1 expression, whereas ERGO was undetectable in LPMCs of control mice. Functional expression of OCTN1 was also confirmed in LPS-stimulated human macrophage-like cell line, THP-1. In conclusion, OCTN1 is functionally expressed on activated intestinal macrophages, and ERGO uptake into these immune cells could contribute at least in part to the altered disposition of ERGO in intestinal inflammation.

Analysis of gene-environment interactions in postnatal development of the mammalian intestine

Unlike mammalian embryogenesis, which takes place in the relatively predictable and stable environment of the uterus, postnatal development can be affected by a multitude of highly variable environmental factors, including diet, exposure to noxious substances, and microorganisms. Microbial colonization of the intestine is thought to play a particularly important role in postnatal development of the gastrointestinal, metabolic, and immune systems. Major changes in environmental exposure occur right after birth, upon weaning, and during pubertal maturation into adulthood. These transitions include dramatic changes in intestinal contents and require appropriate adaptations to meet changes in functional demands. Here, we attempt to both characterize and provide mechanistic insights into postnatal intestinal ontogeny. We investigated changes in global intestinal gene expression through postnatal developmental transitions. We report profound alterations in small and large intestinal transcriptional programs that accompany both weaning and puberty in WT mice. Using myeloid differentiation factor 88 (MyD88)/TIR-domain-containing adapter-inducing interferon-β (TRIF) double knockout littermates, we define the role of toll-like receptors (TLRs) and interleukin (IL)-1 receptor family member signaling in postnatal gene expression programs and select ontogeny-specific phenotypes, such as vascular and smooth muscle development and neonatal epithelial and mast cell homeostasis. Metaanalysis of the effect of the microbiota on intestinal gene expression allowed for mechanistic classification of developmentally regulated genes by TLR/IL-1R (TIR) signaling and/or indigenous microbes. We find that practically every aspect of intestinal physiology is affected by postnatal transitions. Developmental timing, microbial colonization, and TIR signaling seem to play distinct and specific roles in regulation of gene-expression programs throughout postnatal development.

Pharmacogenetics of drug-induced birth defects: the role of polymorphisms of placental transporter proteins

One of the ongoing issues in perinatal medicine is the risk of birth defects associated with maternal drug use. The teratogenic effect of a drug depends, apart from other factors, on the exposition of the fetus to the drug. Transporter proteins are known to be involved in the pharmacokinetics of drugs and have an effect on drug level and fetal drug exposure. This condition may subsequently alter the risk of teratogenicity, which occurs in a dose-dependent manner. This review focuses on the clinically important polymorphisms of transporter proteins and their effects on the mRNA and protein expression in placental tissue. We also propose a novel approach on how the different genotypes of the polymorphism can be translated into phenotypes to facilitate genetic association studies. The last section looks into the recent studies exploring the association between P-glycoprotein polymorphisms and the risk of fetal birth defects associated with medication use during pregnancy.

Increasing small intestinal permeability worsens colitis in the IL-10-/- mouse and prevents the induction of oral tolerance to ovalbumin

BACKGROUND

Increased intestinal permeability is found in noninflamed portions of the gut of inflammatory bowel disease patients and in their first-degree relatives, suggesting that it is not a consequence of inflammation. Additionally, increased small intestinal permeability precedes colonic disease in animal models of inflammatory bowel disease. However, it is not known how small intestinal permeability modulates disease in the colon. The aim of this study was to determine if increasing small intestinal permeability modulates colonic inflammation in interleukin (IL)-10 mice and if an increase in permeability is sufficient to prevent oral tolerance to a dietary antigen.

METHODS

IL-10 mice were treated with the zonula occludens toxin pathway agonist AT-1002 for 8 weeks, and colitis severity was measured at 12 weeks of age. Wild-type mice were also treated with AT-1002 and fed ovalbumin (OVA) to determine the local and systemic immune response to this antigen under increased small intestinal permeability conditions.

RESULTS

IL-10 mice treated with AT-1002 showed exacerbated colitis at 12 weeks of age. AT-1002 also induced a significant OVA-specific humoral response compared with mice that received OVA alone. In addition, the intestinal production of IL-10 and TGF-β in response to oral OVA was prevented when OVA was given with AT-1002.

CONCLUSIONS

Increasing small intestinal permeability worsens colitis in IL-10 mice, and it prevents the development of oral tolerance to OVA in wild-type mice. This study suggests that small intestinal permeability is not merely a consequence of inflammation but a condition that leads to two of the main pathological features of inflammatory bowel disease.

Host-microbe interactions via membrane transport systems

Living organisms take in essential molecules and get rid of wastes effectively through the selective transport of materials. Especially in the digestive tract, advanced transport systems are indispensable for the absorption of nutrients and elimination of waste products. These transport pathways control physiological functions by modulating the ionic environment inside and outside the cells. Moreover, recent studies have shown the importance of the expression of trafficking-related molecules and the population of gut microbiota. We found that the molecules secreted from microorganisms are imported into the cells via transporters or endocytosis and that they activate cell survival pathways of intestinal epithelial cells. These findings indicate that the interactions between the gut microbiota and host cells are mediated, at least partly, by the membrane transport systems. In addition, it is well known that the breakdown of transport systems induces various diseases. This review highlights the significance of the transport systems as the pathogenic molecules and therapeutic targets in gastrointestinal disorders. For example, abnormal expression of the genes encoding membrane transport-related molecules is frequently involved in digestive diseases, such as colorectal cancer and inflammatory bowel disease. We herein review the significance of these molecules as pathogenic and therapeutic targets for digestive diseases.

Functional and molecular effects of mercury compounds on the human OCTN1 cation transporter: C50 and C136 are the targets for potent inhibition

The effect of mercury compounds has been tested on the organic cation transporter, hOCTN1. MeHg(+), Hg(2+), or Cd(2+) caused strong inhibition of transport. 1,4-Dithioerythritol (DTE), cysteine (Cys), and N-acetyl-l-cysteine reversed (NAC) the inhibition at different extents. 2-Aminoethyl methanethiosulfonate hydrobromide (MTSEA), a prototype SH reagent, exerted inhibition of transport similar to that observed for the mercurial agents. To investigate the mechanism of action of mercurials, mutants of hOCTN1 in which each of the Cys residues was substituted by Ala have been constructed, over-expressed in Escherichia coli, and purified. Tetraethylammonium chloride (TEA) uptake mediated by each mutant in proteoliposomes was comparable to that of wild type (WT). IC50 values of the WT and mutants for the mercury compounds were derived from dose-response analyses. The mutants C50A and C136A showed significant increase of IC50 indicating that the 2 Cys residues were involved in the interaction with the mercury compounds and inhibition of the transporter. The double mutant C50A/C136A was constructed; the lack of inhibition confirmed that the 2 Cys residues are the targets of mercury compounds. MTSEA showed similar behavior with respect to the mercurial reagents with the difference that increased IC50 was observed also in the C81A mutant. Similar results were obtained when transport was measured as acetylcholine uptake. Ethyl mercury (Thimerosal) inhibited hOCTN1 as well. C50A, C50A/C136A and, at very lower extent, C136A showed increased IC50 indicating that C50 was the major target of this mercury compound. The homology model of hOCTN1 was built using as template PiPT and validated by the experimental data on mutant proteins.

What do drug transporters really do?

Potential drug-drug interactions mediated by the ATP-binding cassette (ABC) transporter and solute carrier (SLC) transporter families are of clinical and regulatory concern. However, the endogenous functions of these drug transporters are not well understood. Discussed here is evidence for the roles of ABC and SLC transporters in the handling of diverse substrates, including metabolites, antioxidants, signalling molecules, hormones, nutrients and neurotransmitters. It is suggested that these transporters may be part of a larger system of remote communication ('remote sensing and signalling') between cells, organs, body fluid compartments and perhaps even separate organisms. This broader view may help to clarify disease mechanisms, drug-metabolite interactions and drug effects relevant to diabetes, chronic kidney disease, metabolic syndrome, hypertension, gout, liver disease, neuropsychiatric disorders, inflammatory syndromes and organ injury, as well as prenatal and postnatal development.

The effect of turmeric (Curcuma longa) extract on the functionality of the solute carrier protein 22 A4 (SLC22A4) and interleukin-10 (IL-10) variants associated with inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic relapsing disease. Genetic predisposition to the disease reduces an individual's capacity to respond appropriately to environmental challenges in the intestine leading to inappropriate inflammation. IBD patients often modify their diet to mitigate or reduce the severity of inflammation. Turmeric (Curcuma longa L., Zingiberaceae) has historically been used in Chinese, Hindu, and Ayurvedic medicine over several centuries to treat inflammatory disorders. To understand how turmeric may influence the consequences of a genetic predisposition to inappropriate inflammation, we used HEK293 cells to examine the in vitro capacity of turmeric extract and fractions to affect the functionality of two gene variants, solute carrier protein 22 A4 (SLC22A4, rs1050152) and interleukin-10 (IL-10, rs1800896) associated with IBD. We found that a turmeric extract and several chromatographically separated fractions beneficially affected the variants of SLC22A4 and IL-10 associated with IBD, by reducing inappropriate epithelial cell transport (SLC22A4, 503F) and increasing anti-inflammatory cytokine gene promoter activity (IL-10, -1082A). The effect of turmeric on the IL-10 variant was strongly associated with the curcumin content of the extract and its fractions.

Role of genetics in pediatric inflammatory bowel disease

Inflammatory bowel disease (IBD), encompassing Crohn's disease (CD), ulcerative colitis (UC), and unclassified IBD, is characterized by chronic intestinal inflammation and has a multifactorial etiology with complex interactions between genetic and environmental factors. The genetics of IBD are believed to be common and complex with over 163 associated genetic loci. However, the genetic contribution of the majority of these common loci is small, and the effect sizes are low. Although childhood onset IBD represents only 10% to 25% of all IBD cases, in depth research into the genetic networks of pediatric IBD has revealed exciting new developments and unsuspected pathways. Recent pediatric studies have revealed an increasing spectrum of human monogenic diseases with high effect sizes or penetrance that can present with IBD or IBD-like intestinal inflammation. A substantial proportion of patients with these genetic defects present with very early onset of intestinal inflammation, with onset of IBD at less than 10 years of age. There is also considerable overlap with primary immunodeficiencies and very early onset IBD. This review summarizes the current understanding of the genetics of pediatric IBD with a focus on the very early onset population and discusses the promising results from the effort of finding missing heritability of IBD from studying pediatric population.

Ultra-performance liquid chromatographic determination of L-ergothioneine in commercially available classes of cow milk

A new efficient and sensitive precolumn hydrophilic interaction ultra-performance liquid chromatography (HILIC-UPLC) method was established for the quantitative determination of L-ergothioneine (ERT) in milk. After derivatization of ERT with 7-diethylamino-3-[4-(iodoacetamido)phenyl]-4-methylcoumarin, chromatographic separation was achieved in a fairly short time, less than 5 min, on a 100 × 2.1 mm Waters Cortecs UPLC HILIC 1.6-μm column, by using a mixture of 30 mmol/L ammonium acetate/acetonitrile (10:90, v/v) as a mobile phase flowing isocratically at 0.9 mL/min. Limit of detection and the limit of quantification were 0.03 and 0.10 μmol/L, respectively. The method exhibited linearity in a concentration range of 0.16 and 5.08 μmol/L. Mean recovery was 106.66%, whereas intra- and interassay precisions were determined to be within 6 RSD%. On average, ERT concentration in different commercially available classes of cow milk was found to be 0.442 ± 0.191 μmol/L, with the highest levels in the ultra-high temperature milks and low values in the unprocessed and HTST whole milks. In this light, our experiments suggest that ERT could be used as a marker for the heat treatment of milk.

Genetic update on inflammatory factors in ulcerative colitis: Review of the current literature

Ulcerative colitis (UC) is one of the main types of inflammatory bowel disease, which is caused by dysregulated immune responses in genetically predisposed individuals. Several genetic factors, including interleukin and interleukin receptor gene polymorphisms and other inflammation-related genes play central role in mediating and modulating the inflammation in the human body, thereby these can be the main cause of development of the disease. It is clear these data are very important for understanding the base of the disease, especially in terms of clinical utility and validity, but summarized literature is exiguous for challenge health specialist that can used in the clinical practice nowadays. This review summarizes the current literature on inflammation-related genetic polymorphisms which are associated with UC. We performed an electronic search of Pubmed Database among publications of the last 10 years, using the following medical subject heading terms: UC, ulcerative colitis, inflammation, genes, polymorphisms, and susceptibility.

Escherichia coli-host macrophage interactions in the pathogenesis of inflammatory bowel disease

Multiple studies have demonstrated alterations in the intestinal microbial community (termed the microbiome) in Crohn’s disease (CD) and several lines of evidence suggest these changes may have a significant role in disease pathogenesis. In active and quiescent disease, both the faecal and mucosa-associated microbiome are discordant with matched controls with reduced biodiversity, changes in dominant organisms and increased temporal variation described. Mucosa-associated adherent, invasive Escherichia coli (E. coli) (AIEC), pro-inflammatory and resistant to killing by mucosal macrophages, appear to be particularly important. AIEC possess several virulence factors which may confer pathogenic potential in CD. Type-1 pili (FimH) allow adherence to intestinal cells via cell-surface carcinoembryonic antigen-related cell adhesion molecules and possession of long polar fimbrae promotes translocation across the intestinal mucosa via microfold (M)-cells of the follicle-associated epithelium. Resistance to stress genes (htrA, dsbA and hfq) and tolerance of an acidic pH may contribute to survival within the phagolysosomal environment. Here we review the current understanding of the role of mucosa-associated E. coli in Crohn’s pathogenesis, the role of the innate immune system, factors which may contribute to prolonged bacterial survival and therapeutic strategies to target intracellular E. coli.

Single-nucleotide polymorphisms in SLC22A23 are associated with ulcerative colitis in a Canadian white cohort

BACKGROUND

SLC22A23 is an orphan gene in the SLC22 family of organic membrane transporters, and its single-nucleotide polymorphism rs17309827-T was recently nominally associated with intestinal inflammation in a genome-wide association study. Other polymorphisms in the SLC22A23 gene have been associated with diseases with an inflammatory component, and polymorphisms in related genes in the SLC22 family have been repeatedly associated with inflammatory bowel disease (IBD).

OBJECTIVE

In a candidate-gene study using a well-phenotyped, highly monitored, Manitoban white cohort, we investigated whether variations in SLC22A23 were associated with intestinal inflammation.

DESIGN

Selected genetic variations were genotyped by using fluorescent-based assays or a polymerase chain reaction-restriction fragment length polymorphism analysis in 160 individuals with Crohn disease, 149 individuals with ulcerative colitis, and 142 healthy control subjects to determine genetic associations.

RESULTS

Homozygocity for single-nucleotide polymorphisms rs4959235-TT and rs950318-GG was associated with IBD, whereby 6% of patients (18 of 311 cases) carried these genotypes, but they were not seen in healthy controls.

CONCLUSION

Associations reported in this article add to the emerging evidence that SLC22A23 variants could modify IBD risk. However, the biology of the gene and impact of variations on the gene's functions need to be tested to validate a causative role.

Interleukin-23 receptor single nucleotide polymorphisms in ulcerative colitis. A study in Iranian populations

BACKGROUND/OBJECTIVE

Genetic factors seem to play an important role in the pathogenesis of ulcerative colitis (UC). Genome wide association studies showed a highly significant association between interleukin 23 receptor (IL23R) single nucleotide polymorphisms (SNPs) and Crohn's disease; however, there are contrary results regarding the disease-modifying effects of IL23R variants in UC. This study was performed in a group of patients with UC to test the possible role of IL23R SNPs in conferring susceptibility or protection against the disease.

METHODS

The study was performed on 67 Iranian adult patients with UC and 78 healthy controls. Eight IL23R SNPs were genotyped, using real-time polymerase chain reaction (RT-PCR). The frequencies of alleles and genotype at each position were determined and compared between two groups of patients and controls.

RESULTS

The frequency of the T allele at position rs1343151 was significantly higher in the patient group, compared to the controls (P=0.018). The TT genotype at the same position was also significantly overrepresented in the patient group (P=0.02). There was no significant difference in alleles and genotype frequencies of other SNPs between patients and controls.

CONCLUSIONS

This study identified a new susceptibility locus associated with UC. Our findings provide further insight into the genetics of UC, which might be amenable to future therapeutic intervention.

Crystallization and preliminary X-ray analysis of the ergothioneine-biosynthetic methyltransferase EgtD

Ergothioneine is an amino-acid betaine derivative of histidine that was discovered more than one century ago. Despite significant research pointing to a function in oxidative stress defence, the exact mechanisms of action of ergothioneine remain elusive. Although both humans and bacterial pathogens such as Mycobacterium tuberculosis seem to depend on ergothioneine, humans are devoid of the corresponding biosynthetic enzymes. Therefore, its biosynthesis may emerge as potential drug target in the development of novel therapeutics against tuberculosis. The recent identification of ergothioneine-biosynthetic genes in M. smegmatis enables a more systematic study of its biology. The pathway is initiated by EgtD, a SAM-dependent methyltransferase that catalyzes a trimethylation reaction of histidine to give N(α),N(α),N(α)-trimethylhistidine. Here, the recombinant production, purification and crystallization of EgtD are reported. Crystals of native EgtD diffracted to 2.35 Å resolution at a synchrotron beamline, whereas crystals of seleno-L-methionine-labelled protein diffracted to 1.75 Å resolution and produced a significant anomalous signal to 2.77 Å resolution at the K edge. All of the crystals belonged to space group P212121, with two EgtD monomers in the asymmetric unit.

Identification and Functional Characterization of Novel Genetic Variations in the OCTN1 Promoter

Human organic cation/carnitine transporter 1 (OCTN1) plays an important role in the transport of drugs and endogenous substances. It is known that a missense variant of OCTN1 is significantly associated with Crohn's disease susceptibility. This study was performed to identify genetic variants of the OCTN1 promoter in Korean individuals and to determine their functional effects. First, the promoter region of OCTN1 was directly sequenced using genomic DNA samples from 48 healthy Koreans. OCTN1 promoter activity was then measured using a luciferase reporter assay in HCT-116 cells. Seven variants of the OCTN1 promoter were identified, two of which were novel. There were also four major OCTN1 promoter haplotypes. Three haplotypes (H1, H3, and H4) showed decreased transcriptional activity, which was reduced by 22.9%, 23.0%, and 44.6%, respectively (p<0.001), compared with the reference haplotype (H2). Transcription factor binding site analyses and gel shift assays revealed that NF-Y could bind to the region containing g.-1875T>A, a variant present in H3, and that the binding affinity of NF-Y was higher for the g.-1875T allele than for the g.-1875A allele. NF-Y could also repress OCTN1 transcription. These data suggest that three OCTN1 promoter haplotypes could regulate OCTN1 transcription. To our knowledge, this is the first study to identify functional variants of the OCTN1 promoter.

Role of genes, the environment and their interactions in the etiology of inflammatory bowel diseases

Few of the studied genes demonstrate association with inflammatory bowel disease (IBD). Three mutations in the nucleotide-binding oligomerization domain 2 gene have consistently shown to be independent risk factors for Crohn's disease, but none of the alleles exhibited high sensitivity or specificity for IBD. Linkage analysis implicated several loci on various chromosomes, and epistasis has been demonstrated. The etiopathogenesis of IBD remains unknown, and environmental contribution to their pathogenesis is evident from genetic studies that demonstrated incomplete monozygotic twins concordandance rate for both Crohn's and ulcerative colitis. Smoking has shown an opposite effect on disease phenotype, with an adverse effect on disease course for Crohn's disease, but a slight beneficial effect in ulcerative colitis. The contribution of infectious agents to susceptibility to IBD appears to be strong. However, the role of nutrition on the etiology and therapy of IBD is not clear. Inconsistencies in environmental risk factors could be due to gene-environment interactions, making it essential to study the role of genetics and environmental contribution to the etiopathology of IBD. Transgenic or knockout mice, such as interleukin-10(-/-), T-cell receptor alpha(-/-), Galphai(2) (-/-) and N-cadherin(-/-), develop colitis-like inflammation similar to humans. Therefore, animal models must be further studied to explore mechanistic interactions.

Modeling inflammatory bowel disease: the zebrafish as a way forward

The zebrafish has proved to be an informative model of vertebrate development and, more recently, an emerging model of human disease. The realization of the full potential of the zebrafish as a disease model lies in two interdependent areas. The first is an appreciation that the often overlooked strength of this species lies in allowing the design of experiments that address the interplay of genetics and the environment in a manipulable manner. The second is in the application and further development of gene targeting approaches. These twin features will be addressed in this review in the context of modeling inflammatory bowel disease.

Immunopathology of inflammatory bowel disease

Inflammatory bowel disease (IBD) results from a complex series of interactions between susceptibility genes, the environment, and the immune system. The host microbiome, as well as viruses and fungi, play important roles in the development of IBD either by causing inflammation directly or indirectly through an altered immune system. New technologies have allowed researchers to be able to quantify the various components of the microbiome, which will allow for future developments in the etiology of IBD. Various components of the mucosal immune system are implicated in the pathogenesis of IBD and include intestinal epithelial cells, innate lymphoid cells, cells of the innate (macrophages/monocytes, neutrophils, and dendritic cells) and adaptive (T-cells and B-cells) immune system, and their secreted mediators (cytokines and chemokines). Either a mucosal susceptibility or defect in sampling of gut luminal antigen, possibly through the process of autophagy, leads to activation of innate immune response that may be mediated by enhanced toll-like receptor activity. The antigen presenting cells then mediate the differentiation of naïve T-cells into effector T helper (Th) cells, including Th1, Th2, and Th17, which alter gut homeostasis and lead to IBD. In this review, the effects of these components in the immunopathogenesis of IBD will be discussed.

Susceptibility to ulcerative colitis in Hungarian patients determined by gene-gene interactions

AIM: To study the inflammatory bowel disease-5 locus (IBD5) and interleukin-23 receptor (IL23R) gene variants in UC patients and test for gene-gene interaction.

METHODS: The study population (n = 625) was comprised of 320 unrelated ulcerative colitis (UC) patients with Caucasian origin and 316 age- and gender-matched, healthy controls. Five variants in the IBD5 locus (IGR2198a_1 rs11739135, IGR2096a_1 rs12521868, IGR2230a_1 rs17622208, SLC22A4 rs1050152 and SLC22A5 rs2631367) and two of the IL23R gene (rs1004819, rs2201841) were analysed. PCR and restriction fragment length polymorphism methods were used for genotyping, the SLC22A4 rs1050152 genotypes were determined by direct sequencing. Interactions and specific genotype combinations of the seven variants were tested by binary logistic regression analysis. The IL23R genotypes were stratified by IBD5 genotypes for further interaction analyses.

RESULTS: For the IL23R rs1004819 A allele we found significantly higher allele frequency (P = 0.032) in UC patients compared to control subjects. The SNP rs1004819 showed significant association with UC risk for carriers (P = 0.004, OR = 1.606; 95%CI: 1.160-2.223) and the SNP rs2201841 for homozygotes (P = 0.030, OR = 1.983; 95%CI: 1.069-3.678). Individually none of the IBD5 markers conferred risk to UC development. There was no evidence for statistical interaction either between IBD5 loci and IL23R genes using logistic regression analysis. After genotype stratification, we could detect a positive association on the background of rs1004819 A allele for SLC22A4 T, SLC22A5 C, IGR2198a_1 C or IGR2096a_1 T allele, the highest OR was calculated in the presence of SLC22A4 T allele (P = 0.005, OR = 2.015; 95%CI: 1.230-3.300). There was no association with UC for any combinations of rs1004819 and IGR2230a_1. The IL23R rs2201841 homozygous genotype and IBD5 carrier status together did not confer susceptibility for UC.

CONCLUSION: The present study has shown that UC susceptibility genes are likely to act in a complex interactive manner similar to CD.

Clinical and biochemical correlates of serum L-ergothioneine concentrations in community-dwelling middle-aged and older adults

Background

Despite the increasing interest towards the biological role of L-ergothioneine, little is known about the serum concentrations of this unusual aminothiol in older adults. We addressed this issue in a representative sample of community-dwelling middle-aged and older adults.

Methods

Body mass index, estimated glomerular filtration rate, serum concentrations of L-ergothioneine, taurine, homocysteine, cysteine, glutathione, cysteinylglycine, and glutamylcysteine were evaluated in 439 subjects (age 55–85 years) randomly selected from the Hunter Community Study.

Results

Median L-ergothioneine concentration in the entire cohort was 1.01 IQR 0.78–1.33 µmol/L. Concentrations were not affected by gender (P = 0.41) or by presence of chronic medical conditions (P = 0.15). By considering only healthy subjects, we defined a reference interval for L-ergothioneine serum concentrations from 0.36 (90% CI 0.31–0.44) to 3.08 (90% CI 2.45–3.76) µmol/L. Using stepwise multiple linear regression analysis L-ergothioneine was negatively correlated with age (rpartial = −0.15; P = 0.0018) and with glutamylcysteine concentrations (rpartial = −0.13; P = 0.0063).

Conclusions

A thorough analysis of serum L-ergothioneine concentrations was performed in a large group of community-dwelling middle-aged and older adults. Reference intervals were established. Age and glutamylcysteine were independently negatively associated with L-ergothioneine serum concentration.

Betaine reduces serum uric acid levels and improves kidney function in hyperuricemic mice

Betaine as a dietary alkaloid has attracted the attention of patients with kidney diseases. This study aimed to investigate the effects of betaine on serum uric acid levels and kidney function, and explore their underlying mechanisms in potassium oxonate-induced hyperuricemic mice. Betaine at 5, 10, 20, and 40 mg/kg was orally administered to hyperuricemic mice for 7 days and found to significantly reduce serum uric acid levels and increase fractional excretion of uric acid in hyperuricemic mice in a dose-dependent manner. It effectively restored renal protein level alterations of urate transport-related molecular proteins urate transporter 1, glucose transporter 9, organic anion transporter 1, and ATP-binding cassette subfamily G member 2 in this model, possibly resulting in the enhancement of kidney urate excretion. Moreover, betaine reduced serum creatinine and blood urea nitrogen levels and affected urinary levels of beta-2-microglobulin and N-acetyl-beta-D-glucosaminidase as well as upregulated renal protein levels of organic cation/carnitine transporters OCT1, OCTN1, and OCTN2, resulting in kidney function improvement in hyperuricemic mice. The findings from this study provide evidence that betaine has anti-hyperuricemic and nephroprotective actions by regulating protein levels of these renal organic ion transporters in hyperuricemic mice.

Renal transport of organic anions and cations

Organic anions and cations (OAs and OCs, respectively) comprise an extraordinarily diverse array of compounds of physiological, pharmacological, and toxicological importance. The kidney, primarily the renal proximal tubule, plays a critical role in regulating the plasma concentrations of these organic electrolytes and in clearing the body of potentially toxic xenobiotics agents, a process that involves active, transepithelial secretion. This transepithelial transport involves separate entry and exit steps at the basolateral and luminal aspects of renal tubular cells. Basolateral and luminal OA and OC transport reflects the concerted activity of a suite of separate proteins arranged in parallel in each pole of proximal tubule cells. The cloning of multiple members of several distinct transport families, the subsequent characterization of their activity, and their subcellular localization within distinct regions of the kidney, now allows the development of models describing the molecular basis of the renal secretion of OAs and OCs. New information on naturally occurring genetic variation of many of these processes provides insight into the basis of observed variability of drug efficacy and unwanted drug-drug interactions in human populations. The present review examines recent work on these issues.

Strategies of bacterial over expression of membrane transporters relevant in human health: the successful case of the three members of OCTN subfamily

The OCTN subfamily includes OCTN1, 2, and 3 which are structurally and functionally related. These transporters are involved in maintenance of the carnitine homeostasis, which is essential in mammals for fatty acid β-oxidation, VLDL assembly, post-translational modifications, and other essential functions. Indeed, defects of these transporters lead to severe pathologies. OCTN1 and OCTN2 are expressed in many human tissues, while OCTN3 gene has been identified only in mouse and rat. The transporters mediate transport of carnitine and other substrates with different efficiencies and mechanisms. In order to over express the three proteins, a screening of many combinations of E. coli strains with plasmid constructs has been conducted. Only Rosetta(DE3) or Rosettagami2(DE3) gave significant expression. Higher protein amounts were firstly obtained with pET-41a(+) or pGEX-4T1 carrying fusion protein tags which required additional purification passages. Vectors carrying only a 6His tag, suitable for single passage purification, were preferred even though they lead to lower initial expression levels. Expressions were then increased optimizing several critical parameters. hOCTN1 was obtained with pH6EX3 in RosettaGami2(DE3)pLysS. hOCTN2 and mOCTN3 were obtained using pET-21a(+) in Rosetta(DE3). In particular, hOCTN2 was expressed only after codon bias, substituting the second triplet CGG with AAA (R2K mutant). The best growth conditions for hOCTN1 and mOCTN3 were 28 °C and 6 h of induction, while 4 h of induction for hOCTN2R2K. The proteins collected in the insoluble fraction of cell lysates, solubilized with sarkosyl, were purified by Ni-chelating chromatography. Final yield was 2.0, 3.0, or 3.5 mg/l of cell culture for mOCTN3, hOCTN1, or hOCTN2R2K. The data indicated that, in spite of the close evolutionary relations, several factors play different critical roles in bacterial expression of the three proteins, thus general criteria cannot be underlined. However, the strategy of dealing with related proteins revealed to be finally successful for over expressing all the three subfamily members.

Gene genealogies for genetic association mapping, with application to Crohn's disease

A gene genealogy describes relationships among haplotypes sampled from a population. Knowledge of the gene genealogy for a set of haplotypes is useful for estimation of population genetic parameters and it also has potential application in finding disease-predisposing genetic variants. As the true gene genealogy is unknown, Markov chain Monte Carlo (MCMC) approaches have been used to sample genealogies conditional on data at multiple genetic markers. We previously implemented an MCMC algorithm to sample from an approximation to the distribution of the gene genealogy conditional on haplotype data. Our approach samples ancestral trees, recombination and mutation rates at a genomic focal point. In this work, we describe how our sampler can be used to find disease-predisposing genetic variants in samples of cases and controls. We use a tree-based association statistic that quantifies the degree to which case haplotypes are more closely related to each other around the focal point than control haplotypes, without relying on a disease model. As the ancestral tree is a latent variable, so is the tree-based association statistic. We show how the sampler can be used to estimate the posterior distribution of the latent test statistic and corresponding latent p-values, which together comprise a fuzzy p-value. We illustrate the approach on a publicly-available dataset from a study of Crohn's disease that consists of genotypes at multiple SNP markers in a small genomic region. We estimate the posterior distribution of the tree-based association statistic and the recombination rate at multiple focal points in the region. Reassuringly, the posterior mean recombination rates estimated at the different focal points are consistent with previously published estimates. The tree-based association approach finds multiple sub-regions where the case haplotypes are more genetically related than the control haplotypes, and that there may be one or multiple disease-predisposing loci.

Reduced fat oxidation rates during submaximal exercise in adolescents with Crohn's disease

BACKGROUND

Children with Crohn's disease (CD) suffer from malnutrition. Understanding substrate utilization during exercise may help patients with CD sustain a healthy active lifestyle without compromising nutrition. The aim of this study was to determine whether substrate utilization and bioavailability during exercise are altered in children with CD compared with controls.

METHODS

Seven children with CD (mean age ± SD: 15.2 ± 2.3 yr) and 7 controls (14.4 ± 2.3 yr) were matched by sex and biological age. Participants completed 60 minutes of cycling at an intensity equivalent to 50% of their peak mechanical power. Rates of total fat and carbohydrate (CHO) oxidation, the amount of fat and CHO oxidized, and the contribution of fat and CHO to total energy expenditure were calculated from expired gases collected during exercise. Blood was collected before, during, and at the end of exercise and analyzed for insulin, free fatty acids, and glucose.

RESULTS

Whole-body fat oxidation rate (expressed in mg · kg(-1) of body weight per min) during exercise was lower in children with CD (5.8 ± 1.0) compared with controls (8.0 ± 2.2, P < 0.05). Children with CD relied significantly more on CHO, with approximately 10% greater contribution toward total energy expenditure (P < 0.05) than controls. There were no differences in plasma insulin, free fatty acids, or glucose between the groups.

CONCLUSIONS

Fat metabolism during exercise seems to be impaired in children with CD. A greater reliance on CHO is required to meet the energy demands of submaximal exercise.

Impact of exome sequencing in inflammatory bowel disease

Approaches to understanding the genetic contribution to inflammatory bowel disease (IBD) have continuously evolved from family- and population-based epidemiology, to linkage analysis, and most recently, to genome-wide association studies (GWAS). The next stage in this evolution seems to be the sequencing of the exome, that is, the regions of the human genome which encode proteins. The GWAS approach has been very fruitful in identifying at least 163 loci as being associated with IBD, and now, exome sequencing promises to take our genetic understanding to the next level. In this review we will discuss the possible contributions that can be made by an exome sequencing approach both at the individual patient level to aid with disease diagnosis and future therapies, as well as in advancing knowledge of the pathogenesis of IBD.

Vitamin D and Crohn's disease in the adult patient: a review

Crohn's disease (CD) is characterized as a chronic immune-mediated inflammatory disorder of the gastrointestinal tract. Current consensus surrounding the cause of the disease suggests a complex interplay between genetic susceptibility, the intestinal microbiome and environmental factors, leading to the aberrant Th1 and Th17 immune cell mediated response. Vitamin D deficiency is common in CD patients, and long-standing deficiency has been associated with reduced bone mineral density (BMD). Accumulating evidence now suggests that in addition to maintaining skeletal integrity, vitamin D also plays an integral role in regulating the general immune response, a function employed via its genomic actions on the vitamin D receptor (VDR). The VDR is expressed in all immune cells and both directly and indirectly targeted by the bioactive form of vitamin D, 1,25-Dihydroxyvitamin D (1,25[OH]2D). Impaired regulation or deficiency of the vitamin has been linked to the promotion of self-reactive T cell development, loss of immune tolerance to self-structures, and experimental colitis in animal models, whereas the subsequent administration of the vitamin in these models resulted in the improvement of immune-mediated symptoms. In addition, low vitamin D has been associated with disease activity in CD patients, and supplementation appears to be beneficial in improving clinical scores and reducing inflammation. Therefore, the primary aims of this article were to review the molecular evidence supporting the immunoregulatory roles of vitamin D and its supplementation in the CD patient, based on existing literature. The physiological processes, accepted serum concentration values, and its well-recognized role in bone health were also summarized.

The association between three promoter polymorphisms of IL-10 and inflammatory bowel diseases (IBD): a meta-analysis

AIM

To assess the relationship of the Interleukin-10 (IL-10) -1082G/A (rs1800896), -819C/T (rs1800871) and -592C/A (rs1800872) polymorphism with inflammatory bowel disease (IBD) by means of meta-analysis.

METHODS

Published data addressing the association between polymorphism of the IL-10 with Crohn's disease (CD) and Ulcerative colitis (UC) were selected from electronic databases. A total of 17 studies including 4132 cases and 5109 controls were included in this meta-analysis which detected whether -1082G/A, -819C/T and -592C/A polymorphism were associated with CD or UC susceptibility.

RESULT

The IL-10 -819C/T and -519C/A variant allele observed a significant association with UC (OR 1.16, 95%CI 1.03-1.31 and OR 1.19, 95%CI 1.03-1.38) not CD while there is no significant association between -1082G/A and UC or CD.

CONCLUSION

The IL-10 -819C/T and -592C/A polymorphisms contribute to susceptibility to UC, but IL-10 -1082G/A polymorphism neither associated with CD nor UC.

Replication study of ulcerative colitis risk loci in a Lithuanian-Latvian case-control sample

BACKGROUND

Differences between populations might be reflected in their different genetic risk maps to complex diseases, for example, inflammatory bowel disease. We here investigated the role of known inflammatory bowel disease-associated single nucleotide polymorphisms (SNPs) in a subset of patients with ulcerative colitis (UC) from the Northeastern European countries Lithuania and Latvia and evaluated possible epistatic interactions between these genetic variants.

METHODS

We investigated 77 SNPs derived from 5 previously published genome-wide association studies for Crohn's disease and UC. Our study panel comprised 444 Lithuanian and Latvian patients with UC and 1154 healthy controls. Single marker case-control association and SNP-SNP epistasis analyses were performed.

RESULTS

We found 14 SNPs tagging 9 loci, including 21q21.1, NKX2-3, MST1, the HLA region, 1p36.13, IL10, JAK2, ORMDL3, and IL23R, to be associated with UC. Interestingly, the association of UC with previously identified variants in the HLA region was not the strongest association in our study (P = 4.34 × 10, odds ratio [OR] = 1.25), which is in contrast to all previously published studies. No association with any disease subphenotype was found. SNP-SNP interaction analysis showed significant epistasis between SNPs in the PTPN22 (rs2476601) and C13orf31 (rs3764147) genes and increased risk for UC (P = 1.64 × 10, OR = 2.44). The association has been confirmed in the Danish study group (P = 0.04, OR = 3.25).

CONCLUSIONS

We confirmed the association of the 9 loci (21q21.1, 1p36.13, NKX2-3, MST1, the HLA region, IL10, JAK2, ORMDL3, and IL23R) with UC in the Lithuanian-Latvian population. SNP-SNP interaction analyses showed that the combination of SNPs in the PTPN22 (rs2476601) and C13orf31 (rs3764147) genes increase the risk for UC.

Central role of the gut epithelial barrier in the pathogenesis of chronic intestinal inflammation: lessons learned from animal models and human genetics

The gut mucosa is constantly challenged by a bombardment of foreign antigens and environmental microorganisms. As such, the precise regulation of the intestinal barrier allows the maintenance of mucosal immune homeostasis and prevents the onset of uncontrolled inflammation. In support of this concept, emerging evidence points to defects in components of the epithelial barrier as etiologic factors in the pathogenesis of inflammatory bowel diseases (IBDs). In fact, the integrity of the intestinal barrier relies on different elements, including robust innate immune responses, epithelial paracellular permeability, epithelial cell integrity, as well as the production of mucus. The purpose of this review is to systematically evaluate how alterations in the aforementioned epithelial components can lead to the disruption of intestinal immune homeostasis, and subsequent inflammation. In this regard, the wealth of data from mouse models of intestinal inflammation and human genetics are pivotal in understanding pathogenic pathways, for example, that are initiated from the specific loss of function of a single protein leading to the onset of intestinal disease. On the other hand, several recently proposed therapeutic approaches to treat human IBD are targeted at enhancing different elements of gut barrier function, further supporting a primary role of the epithelium in the pathogenesis of chronic intestinal inflammation and emphasizing the importance of maintaining a healthy and effective intestinal barrier.

The SLC22 family with transporters of organic cations, anions and zwitterions

The SLC22 family contains 13 functionally characterized human plasma membrane proteins each with 12 predicted α-helical transmembrane domains. The family comprises organic cation transporters (OCTs), organic zwitterion/cation transporters (OCTNs), and organic anion transporters (OATs). The transporters operate as (1) uniporters which mediate facilitated diffusion (OCTs, OCTNs), (2) anion exchangers (OATs), and (3) Na(+)/zwitterion cotransporters (OCTNs). They participate in small intestinal absorption and hepatic and renal excretion of drugs, xenobiotics and endogenous compounds and perform homeostatic functions in brain and heart. Important endogeneous substrates include monoamine neurotransmitters, l-carnitine, α-ketoglutarate, cAMP, cGMP, prostaglandins, and urate. It has been shown that mutations of the SLC22 genes encoding these transporters cause specific diseases like primary systemic carnitine deficiency and idiopathic renal hypouricemia and are correlated with diseases such as Crohn's disease and gout. Drug-drug interactions at individual transporters may change pharmacokinetics and toxicities of drugs.

Plasma L-ergothioneine measurement by high-performance liquid chromatography and capillary electrophoresis after a pre-column derivatization with 5-iodoacetamidofluorescein (5-IAF) and fluorescence detection

Two sensitive and reproducible capillary electrophoresis and high-performance liquid chromatography-fluorescence procedures were established for quantitative determination of L-egothioneine in plasma. After derivatization of L-ergothioneine with 5-iodoacetamidofluorescein, the separation was carried out by HPLC on an ODS-2 C-18 sperisorb column by using a linear gradient elution and by HPCE on an uncoated fused silica capillary, 50 µm id, and 60 cm length. The methods were validated and found to be linear in the range of 0.3 to 10 µmol/l. The limit of quantification was 0.27 µmol/l for HPCE and 0.15 µmol/l for HPLC. The variations for intra- and inter-assay precision were around 6 RSD%, and the mean recovery accuracy close to 100% (96.11%).

IL-16 induces intestinal inflammation via PepT1 upregulation in a pufferfish model: new insights into the molecular mechanism of inflammatory bowel disease

Inflammatory bowel disease (IBD) has long been a worldwide health care problem with a persistently increasing incidence. Although its clinical features have been well described, its etiology and pathogenesis remain unclear. IL-16 is a chemoattractant cytokine with various effects on cellular activities and diseases. However, the involvement of IL-16 in IBD remains poorly understood. In this study, to our knowledge we report for the first time the mechanism by which IL-16 induces intestinal inflammation by upregulating the expression of oligopeptide transporter member 1 (PepT1) in a Tetraodon nigroviridis fish model. The dextran sodium sulfate-induced colitis model in this species revealed that IL-16 levels significantly increase accompanied by elevations in PepT1 in the colon. Moreover, the signs of colitis were dramatically attenuated by IL-16 depletion using anti-IL-16 Abs. In vivo IL-16 administration induced remarkable intestinal inflammation with typical ulcerative colitis-like features, including histologic damage, inflammatory cell infiltration, increased myeloperoxidase activity, and proinflammatory cytokines expression, which corresponded with significant PepT1 upregulation in the colon. The IL-16-induced PepT1 expression and its upregulated fMLF transport were also demonstrated in vitro. To our knowledge, our study provides the first evidence of the connection between IL-16 and PepT1, which provides new insights into the molecular mechanism underlying IBD development. Additionally, this study suggests that fish species are an attractive model for studying IBD. By providing a better understanding of IL-16 biology from fish to mammals, this study should aid the development of IL-16-based therapies for IBD.

Enzymes involved in L-carnitine biosynthesis are expressed by small intestinal enterocytes in mice: implications for gut health

BACKGROUND

Carnitine is essential for mitochondrial β-oxidation of long-chain fatty acids. Deficiency of carnitine leads to severe gut atrophy, ulceration and inflammation in animal models of carnitine deficiency. Genetic studies in large populations have linked mutations in the carnitine transporters OCTN1 and OCTN2 with Crohn's disease (CD), while other studies at the same time have failed to show a similar association and report normal serum carnitine levels in CD patients.

METHODS

In this report, we have studied the expression of carnitine-synthesizing enzymes in intestinal epithelial cells to determine the capability of these cells to synthesize carnitine de novo. We studied expression of five enzymes involved in carnitine biosynthesis, namely 6-N-trimethyllysine dioxygenase (TMLD), 4-trimethylaminobutyraldehyde dehydrogenase (TMABADH), serine hydroxymethyltransferase 1 and 2 (SHMT1 and 2) and γ-butyrobetaine hydroxylase (BBH) by real-time PCR in mice (C3H strain). We also measured activity of γ-BBH in the intestine using an ex vivo assay and localized its expression by in situ hybridization.

RESULTS

Our investigations show that mouse intestinal epithelium expresses all five enzymes required for de novo carnitine biosynthesis; the expression is localized mainly in villous surface epithelial cells throughout the intestine. The final rate-limiting enzyme γ-BBH is highly active in the small intestine; its activity was 9.7 ± 3.5 pmol/mg/min, compared to 22.7 ± 7.3 pmol/mg/min in the liver.

CONCLUSIONS

We conclude that mouse gut epithelium is able to synthesize carnitine de novo. This capacity to synthesize carnitine in the intestine may play an important role in gut health and can help explain lack of clinical carnitine deficiency signs in subjects with mutations with OCTN transporters.