Unraveling the metabolomic architecture of autism in a large Danish population-based cohort.

BACKGROUND: The prevalence of autism in Denmark has been increasing, reaching 1.65% among 10-year-old children, and similar trends are seen elsewhere. Although there are several factors associated with autism, including genetic, environmental, and prenatal factors, the molecular etiology of autism is largely unknown. Here, we use untargeted metabolomics to characterize the neonatal metabolome from dried blood spots collected shortly after birth. METHODS: We analyze the metabolomic profiles of a subset of a large Danish population-based cohort (iPSYCH2015) consisting of over 1400 newborns, who later are diagnosed with autism and matching controls and in two Swedish population-based cohorts comprising over 7000 adult participants. Mass spectrometry analysis was performed by a timsTOF Pro operated in QTOF mode, using data-dependent acquisition. By applying an untargeted metabolomics approach, we could reproducibly measure over 800 metabolite features. RESULTS: We detected underlying molecular perturbations across several metabolite classes that precede autism. In particular, the cyclic dipeptide cyclo-leucine-proline (FDR-adjusted p = 0.003) and the carnitine-related 5-aminovaleric acid betaine (5-AVAB) (FDR-adjusted p = 0.03), were associated with an increased probability for autism, independently of known prenatal and genetic risk factors. Analysis of genetic and dietary data in adults revealed that 5-AVAB was associated with increased habitual dietary intake of dairy (FDR-adjusted p < 0.05) and with variants near SLC22A4 and SLC22A5 (p < 5.0e - 8), coding for a transmembrane carnitine transporter protein involved in controlling intracellular carnitine levels. CONCLUSIONS: Cyclo-leucine-proline and 5-AVAB are associated with future diagnosis of autism in Danish neonates, both representing novel early biomarkers for autism. 5-AVAB is potentially modifiable and may influence carnitine homeostasis.

Low-no-calorie sweeteners exert marked compound-specific impact on the human gut microbiota ex vivo.

Low-no-calorie sweeteners (LNCS) are used as sugar substitutes as part of strategies to reduce the risk of chronic diseases related to high sugar intake (e.g. type 2 diabetes (T2D)). This study investigated how a range of sweeteners [tagatose (TA)/maltitol (MA)/sorbitol (SO)/stevia (ST)/sucralose (SU)/acesulfame K (ACK)] impact the gut microbiota of T2D subjects and healthy human adults using the ex vivo SIFR® technology (n = 12). The cohort covered clinically relevant interpersonal and T2D-related differences. ACK/SU remained intact while not impacting microbial composition and metabolite production. In contrast, TA/SO and ST/MA were respectively readily and gradually fermented. ST and particularly TA/SO/MA increased bacterial density and SCFA production product-specifically: SO increased acetate (∼Bifidobacterium adolescentis), whilst MA/ST increased propionate (∼Parabacteroides distasonis). TA exerted low specificity as it increased butyrate for healthy subjects, yet propionate for T2D subjects. Overall, LNCS exerted highly compound-specific effects stressing that results obtained for one LNCS cannot be generalised to other LNCS.

Effects of Long-Term Storage on the Biobanked Neonatal Dried Blood Spot Metabolome.

Over 2.5 million neonatal dried blood spots (DBS) are stored at the Danish National Biobank. These samples offer extraordinary possibilities for metabolomics research, including prediction of disease and understanding of underlying molecular mechanisms of disease development. Nevertheless, Danish neonatal DBS have been little explored in metabolomics studies. One question that remains underinvestigated is the long-term stability of the large number of metabolites typically assessed in untargeted metabolomics over long time periods of storage. Here, we investigate temporal trends of metabolites measured in 200 neonatal DBS collected over a time course of 10 years, using an untargeted liquid chromatography tandem mass spectrometry (LC-MS/MS) based metabolomics protocol. We found that a majority (71%) of the metabolome was stable during 10 years of storage at -20 °C. However, we found decreasing trends for lipid-related metabolites, such as glycerophosphocholines and acylcarnitines. A few metabolites, including glutathione and methionine, may be strongly influenced by storage, with changes in metabolite levels up to 0.1-0.2 standard deviation units per year. Our findings indicate that untargeted metabolomics of DBS samples, with long-term storage in biobanks, is suitable for retrospective epidemiological studies. We identify metabolites whose stability in DBS should be closely monitored in future studies of DBS samples with long-term storage.

Rethinking Drug Analysis in Health Care: High-Throughput Analysis of 71 Drugs of Abuse in Oral Fluid Using Ion Mobility--High-Resolution Mass Spectrometry.

We have identified a clinical need for a sensitive, specific, flexible, comprehensive and affordable analytical technology to efficiently detect polydrug use. In addition, the current standard practice of surveilled urine sampling is uncomfortable for the patient; hence, more patient-friendly sample collection methods are requested. To fill these needs, we have developed and validated a high-throughput liquid chromatography-high-resolution mass spectrometry (LC--HRMS) method for the analysis of drugs of abuse (DoA) in oral fluid (OF). The method covers a panel of 71 substances including traditional DoA, prescription narcotics and new psychoactive substances (NPS), with a guaranteed limit of identification of <3 µg/L for 87% of the analytes. Method validation showed high accuracy (>99.7%), sensitivity (>99.7%) and specificity (100%). Most analytes had a high process efficiency during the salting-out liquid-liquid extraction sample preparation and no or only a minor matrix effect during the analysis. We have implemented this method in clinical routine and present data from 18,579 OF samples collected during routine patient treatment in mainly psychiatric and addiction clinics in West Sweden between September 2020 and June 2021. Seventy-one percent of the samples were positive and a total of 41,472 DoA findings were detected. Amphetamine (27%), buprenorphine (25%), nordiazepam (18%) and alprazolam (16%) were most prevalent. New psychoactive substances were detected in 189 samples (1.0%). The occurrence of polydrug use was common; 34% of the positive samples contained three analytes or more and 12% six or more. To the best of our knowledge, this is the first method for comprehensive analysis of DoA in OF using LC--HRMS and the largest dataset published on the detection of DoA in OF. With the current complex and variable drug use pattern, this broad, cost-effective and reliable method has largely replaced immunoassay screening in urine in our laboratory.

Pulmonary Metabolism of Substrates for Key Drug-Metabolizing Enzymes by Human Alveolar Type II Cells, Human and Rat Lung Microsomes, and the Isolated Perfused Rat Lung Model.

Significant pulmonary metabolism of inhaled drugs could have drug safety implications or influence pharmacological effectiveness. To study this in vitro, lung microsomes or S9 are often employed. Here, we have determined if rat and human lung microsomes are fit for purpose or whether it is better to use specific cells where drug-metabolizing enzymes are concentrated, such as alveolar type II (ATII) cells. Activities for major hepatic and pulmonary human drug-metabolizing enzymes are assessed and the data contextualized towards an in vivo setting using an ex vivo isolated perfused rat lung model. Very low rates of metabolism are observed in incubations with human ATII cells when compared to isolated hepatocytes and fewer of the substrates are found to be metabolized when compared to human lung microsomal incubations. Reactions selective for flavin-containing monooxygenases (FMOs), CYP1B1, CYP2C9, CYP2J2, and CYP3A4 all show significant rates in human lung microsomal incubations, but all activities are higher when rat lung microsomes are used. The work also demonstrates that a lung microsomal intrinsic clearance value towards the lower limit of detection for this parameter (3 µL/min/mg protein) results in a very low level of pulmonary metabolic clearance during the absorption period, for a drug dosed into the lung in vivo.

Improvement of bone-erosive temporomandibular joint (TMJ) abnormalities in adolescents undergoing non-surgical treatment: a longitudinal study.

OBJECTIVES: To investigate the longitudinal changes of the imaging temporomandibular joint (TMJ) characteristics in young patients with TMJ-related symptoms and treated with non-surgical methods. The severity of self-reported symptoms at follow-up was also investigated. METHODS: A cone beam CT (CBCT)/CT follow-up examination [median follow-up 4.1 (1.3-6.4) years] was performed in 22 patients with erosive TMJ abnormalities [baseline median age 16 (12-18) years]. Imaging characteristics were analyzed and the changes between the examinations were categorized as (A) improvement, (B) no change, or (C) worsening. Severity of follow-up symptoms was evaluated using Jaw Functional Limitation Scale (JFLS-8) and Graded Chronic Pain Scale (Grade 0-IV). Analyses were performed separately for left and right TMJ. Findings at baseline and follow-up were compared using McNemar test to account for dependencies. Changes in proportions of hard tissue findings between examinations were assessed using Wilcoxon signed ranks test. RESULTS: A significant reduction in the proportion of patients with erosive abnormalities was found [59.1%, 95% CI (36.4-79.3) %]. Baseline erosions improved in 9/12 (75%) right and 14/15 (93%) left TMJs. About half repaired; developed an intact cortical outline. Number of joints with osteophytes increased (right: p < 0.04, left: p < 0.003). New osteophytes were mostly found in joints with erosive findings. Low or no limitation of jaw function (Jaw Functional Limitation Scale) was found in 12/22 (55%) and no or low intensity of pain (Graded Chronic Pain Scale Grade 0 or I) in 19/22 (86%) at follow-up. CONCLUSION: We found a high potential for repair of erosive TMJ abnormalities. However, the patient series was small. The majority of patients assessed their symptom severity at follow-up as low.

CBCT characteristics and interpretation challenges of temporomandibular joint osteoarthritis in a hand osteoarthritis cohort.

OBJECTIVES: To characterise osteoarthritis (OA) in the temporomandibular joints (TMJs) by means of cone beam CT in a hand OA population, and identify interpretation challenges. METHODS: The TMJs of 54 individuals (mean age 71.3) recruited from the "The Oslo hand OA cohort", independently of TMJ-related symptoms, were examined with cone beam CT (ProMax MidCBCT). Images were analysed for bone change characteristics and each joint was diagnosed with either OA, no OA or as indeterminate for OA. The image analysis criteria developed for the Research Diagnostic Criteria for Temporomandibular Disorders were used. Frequencies of bone changes, joint diagnoses and severity grades (1-2) were calculated, as well as κ values for observer agreement. RESULTS: In the OA joints, the most frequent bone changes occurred in the condyle: flattening (79%), osteophyte (72%) and subcortical sclerosis (70%). The most frequent changes in the fossa/eminence were flattening (57%), erosion (49%) and subcortical sclerosis (47%). 53 (49%) of the 108 joints were diagnosed with TMJ OA (68 % Grade 2), 29 joints (27%) with no OA, and 26 joints (24%) were indeterminate for OA. Inter- and intraobserver agreement showed mean κ values of 0.67 and 0.62, respectively. CONCLUSIONS: TMJ changes were common in elderly with hand OA and characterised by bone productive changes. The radiologic features indicated a late stage TMJ OA. Interpretation challenges related to subtle changes were identified and are reflected by the rather low observer agreement. The diagnosis of TMJ OA should be based on evident and clear abnormalities only.

Accuracy of the HumaSensplus point-of-care uric acid meter using capillary blood obtained by fingertip puncture.

BACKGROUND: The uric acid (UA) level in patients with gout is a key factor in disease management and is typically measured in the laboratory using plasma samples obtained after venous puncture. This study aimed to assess the reliability of immediate UA measurement with capillary blood samples obtained by fingertip puncture with the HumaSensplus point-of-care meter. METHODS: UA levels were measured using both the HumaSensplus meter in the clinic and the routine plasma UA method in the biochemistry laboratory of 238 consenting diabetic patients. HumaSensplus capillary and routine plasma UA measurements were compared by linear regression, Bland-Altman plots, intraclass correlation coefficient (ICC), and Lin's concordance coefficient. Values outside the dynamic range of the meter, low (LO) or high (HI), were analyzed separately. The best capillary UA thresholds for detecting hyperuricemia were determined by receiver operating characteristic (ROC) curves. The impact of potential confounding factors (demographic and biological parameters/treatments) was assessed. Capillary and routine plasma UA levels were compared to reference plasma UA measurements by liquid chromatography-mass spectrometry (LC-MS) for a subgroup of 67 patients. RESULTS: In total, 205 patients had capillary and routine plasma UA measurements available. ICC was 0.90 (95% confidence interval (CI) 0.87-0.92), Lin's coefficient was 0.91 (0.88-0.93), and the Bland-Altman plot showed good agreement over all tested values. Overall, 17 patients showed values outside the dynamic range. LO values were concordant with plasma values, but HI values were considered uninterpretable. Capillary UA thresholds of 299 and 340 µmol/l gave the best results for detecting hyperuricemia (corresponding to routine plasma UA thresholds of 300 and 360 µmol/l, respectively). No significant confounding factor was found among those tested, except for hematocrit; however, this had a negligible influence on the assay reliability. When capillary and routine plasma results were discordant, comparison with LC-MS measurements showed that plasma measurements had better concordance: capillary UA, ICC 0.84 (95% CI 0.75-0.90), Lin's coefficient 0.84 (0.77-0.91); plasma UA, ICC 0.96 (0.94-0.98), Lin's coefficient 0.96 (0.94-0.98). CONCLUSIONS: UA measurements with the HumaSensplus meter were reasonably comparable with those of the laboratory assay. The meter is easy to use and may be useful in the clinic and in epidemiologic studies.

Selective Nonsteroidal Glucocorticoid Receptor Modulators for the Inhaled Treatment of Pulmonary Diseases.

A class of potent, nonsteroidal, selective indazole ether-based glucocorticoid receptor modulators (SGRMs) was developed for the inhaled treatment of respiratory diseases. Starting from an orally available compound with demonstrated anti-inflammatory activity in rat, a soft-drug strategy was implemented to ensure rapid elimination of drug candidates to minimize systemic GR activation. The first clinical candidate 1b (AZD5423) displayed a potent inhibition of lung edema in a rat model of allergic airway inflammation following dry powder inhalation combined with a moderate systemic GR-effect, assessed as thymic involution. Further optimization of inhaled drug properties provided a second, equally potent, candidate, 15m (AZD7594), that demonstrated an improved therapeutic ratio over the benchmark inhaled corticosteroid 3 (fluticasone propionate) and prolonged the inhibition of lung edema, indicating potential for once-daily treatment.

Use of HµREL Human Coculture System for Prediction of Intrinsic Clearance and Metabolite Formation for Slowly Metabolized Compounds.

Design of slowly metabolized compounds is an important goal in many drug discovery projects. Standard hepatocyte suspension intrinsic clearance (CLint) methods can only provide reliable CLint values above 2.5 µL/min/million cells. A method that permits extended incubation time with maintained performance and metabolic activity of the in vitro system is warranted to allow in vivo clearance predictions and metabolite identification of slowly metabolized drugs. The aim of this study was to evaluate the static HµREL coculture of human hepatocytes with stromal cells to be set up in-house as a standard method for in vivo clearance prediction and metabolite identification of slowly metabolized drugs. Fourteen low CLint compounds were incubated for 3 days, and seven intermediate to high CLint compounds and a cocktail of cytochrome P450 (P450) marker substrates were incubated for 3 h. In vivo clearance was predicted for 20 compounds applying the regression line approach, and HµREL coculture predicted the human intrinsic clearance for 45% of the drugs within 2-fold and 70% of the drugs within 3-fold of the clinical values. CLint values as low as 0.3 µL/min/million hepatocytes were robustly produced, giving 8-fold improved sensitivity of robust low CLint determination, over the cutoff in hepatocyte suspension CLint methods. The CLint values of intermediate to high CLint compounds were at similar levels both in HµREL coculture and in freshly thawed hepatocytes. In the HµREL coculture formation rates for five P450-isoform marker reactions, paracetamol (CYP1A2), 1-OH-bupropion (CYP2B6), 4-OH-diclofenac (CYP2C9), and 1-OH-midazolam (3A4) were within the range of literature values for freshly thawed hepatocytes, whereas 1-OH-bufuralol (CYP2D6) formation rate was lower. Further, both phase I and phase II metabolites were detected and an increased number of metabolites were observed in the HµREL coculture compared to hepatocyte suspension. In conclusion, HµREL coculture can be applied to accurately estimate intrinsic clearance of slowly metabolized drugs and is now utilized as a standard method for in vivo clearance prediction of such compounds in-house.

Real world data on primary treatment for mantle cell lymphoma: a Nordic Lymphoma Group observational study.

There is consensus that young patients with mantle cell lymphoma (MCL) should receive intensive immunochemotherapy regimens, but optimal treatment of elderly patients as well for as patients with limited or indolent disease is not defined. Our aim was to evaluate and compare outcome in relation to prognostic factors and first-line treatment in patients with MCL in a population-based data set. Data were collected from the Swedish and Danish Lymphoma Registries from the period of 2000 to 2011. A total of 1389 patients were diagnosed with MCL. During this period, age-standardized incidence MCL increased, most prominently among males. Furthermore, male gender was associated with inferior overall survival (OS) in multivariate analysis (hazard ratio [HR] = 1.36; P = .002). Forty-three (3.6%) patients with stage I-II disease received radiotherapy with curative intent, showing a 3-year OS of 93%. Twenty-nine (2.4%) patients followed a watch-and-wait approach and showed a 3-year OS of 79.8%. Among patients receiving systemic treatment, rituximab (n = 766; HR = 0.66; P = .001) and autologous stem cell transplant (n = 273; HR = 0.55; P = .004) were independently associated with improved OS in multivariate analysis. Hence, by a population-based approach, we were able to provide novel data on prognostic factors and primary treatment of MCL, applicable to routine clinical practice.

Troglitazone metabolism and transporter effects in chimeric mice: a comparison between chimeric humanized and chimeric murinized FRG mice.

1. The biotransformation, hepatic transporter and blood chemistry effects of troglitazone were investigated following 7 days of dosing at 600 mg/kg/day to chimeric murinized or humanized FRG mice, Mo-FRG and Hu-FRG mice, respectively. 2. Clinical chemistry and histopathology analysis revealed a significant drop in humanization over the time course of the study for the Hu-FRG mice but no significant changes associated with troglitazone treatment in either the Mo-FRG or the Hu-FRG models. No changes in transporter expression in livers of these mice were observed. Oxidative and conjugative metabolic pathways were identified with a 15- to 18-fold increase in formation of troglitazone sulfate in the Hu-FRG mice compared with the Mo-FRG mice in blood and bile, respectively. This resembles the troglitazone metabolism in human and these data are comparable with the formation of this metabolite in the chimeric uPA(+/+)/SCID mice. 3. However, larger amounts of troglitazone glucuronide were also observed in the Hu-FRG mouse compared with the Mo-FRG mouse which may be an effect of the drop in humanization of the Hu-FRG mouse during the study. 4. Highly humanized mice have a considerable potential in providing a useful first insight into circulating human metabolites of candidate drugs metabolized in the liver.

Randomized crossover study in patients with neuroendocrine tumors to assess patient preference for lanreotide Autogel(®) given by either self/partner or a health care professional.

BACKGROUND: Lanreotide Autogel(®) is supplied in prefilled syringes. Therefore, it is possible for patients with neuroendocrine tumors to use self-/partner-administered injections. The primary objective of this study was to assess the proportion of patients preferring self/partner injections over injections administered by health care professionals, and to describe the impact of self/partner administration on efficacy, safety, and costs. METHODS: Of 62 eligible patients, 26 (42%) patients with neuroendocrine tumors treated with a stable dose of lanreotide Autogel 90 mg or 120 mg every 4 weeks agreed to participate in this Phase IV, international, open-label, crossover study, conducted at hospitals in Sweden, Norway, and Denmark. Patients were randomized to two blocks, starting with administration of lanreotide Autogel by either self/partner or a health care professional. Preference for injections administered by self/partner or health care professionals was measured, as well as efficacy, safety, and health care resource utilization (both direct and indirect costs). RESULTS: Of 25 evaluable patients, 22 (88%) preferred self/partner injections, mainly because they experienced increased independence. Based on all patients asked to participate (n = 62), 35% preferred self/partner injections on a regular basis. There was no difference in efficacy or safety between the two administration blocks. CONCLUSION: Many patients with neuroendocrine tumors prefer self/partner injection of lanreotide Autogel, and are able to self/partner inject without any impact on efficacy or safety. This administration method seems to provide a good alternative for suitable patients to increase patient independence and reduce the number of clinic visits.

Marked improvement of overall survival in mantle cell lymphoma: a population based study from the Swedish Lymphoma Registry.

Abstract In recent years, more intensive chemotherapy regimens for mantle cell lymphoma (MCL) have been associated with prolongation of survival. In this study, our aim was to investigate prognostic factors and evaluate improvement in survival in MCL on a population level. The cohort included all patients diagnosed with MCL from 1 January 2000 to 31 March 2010 in the Swedish Lymphoma Registry. At total of 785 patients with MCL were identified. Age, performance status, and B-symptoms were significant prognostic factors for overall survival (OS) in multivariate analysis. In addition, OS was markedly improved (hazard ratio 0.8, 95% confidence interval 0.7-0.9) for patients diagnosed during the latest time period, 2006-2010, also when corrected for prognostic factors as above. Estimated OS at 3 years was 62%, compared to 47% for patients diagnosed earlier (p < 0.01). The reasons for this dramatic improvement in OS are not yet clear, but may be due to the introduction of specific and more potent therapeutic regimens.

Three-dimensional echocardiography using single-heartbeat modality decreases variability in measuring left ventricular volumes and function in comparison to four-beat technique in atrial fibrillation.

BACKGROUND: Three dimensional echocardiography (3DE) approaches the accuracy of cardiac magnetic resonance in measuring left ventricular (LV) volumes and ejection fraction (EF). The multibeat modality in comparison to single-beat (SB) requires breath-hold technique and regular heart rhythm which could limit the use of this technique in patients with atrial fibrillation (AF) due to stitching artifact. The study aimed to investigate whether SB full volume 3DE acquisition reduces inter- and intraobserver variability in assessment of LV volumes and EF in comparison to four-beat (4B) ECG-gated full volume 3DE recording in patients with AF. METHODS: A total of 78 patients were included in this study. Fifty-five with sinus rhythm (group A) and 23 having AF (group B). 4B and SB 3DE was performed in all patients. LV volumes and EF was determined by these two modalities and inter- and intraobserver variability was analyzed. RESULTS: SB modality showed significantly lower inter- and intraobserver variability in group B in comparison to 4B when measuring LV volumes and EF, except for end-systolic volume (ESV) in intraobserver analysis. There were significant differences when calculating the LV volumes (p < 0.001) and EF (p < 0.05) with SB in comparison to 4B in group B. CONCLUSION: Single-beat three-dimensional full volume acquisition seems to be superior to four-beat ECG-gated acquisition in measuring left ventricular volumes and ejection fraction in patients having atrial fibrillation. The variability is significantly lower both for ejection fraction and left ventricular volumes.

Comparison of a new commercial test, Dermatophyte-PCR kit, with conventional methods for rapid detection and identification of Trichophyton rubrum in nail specimens.

The performance of a new commercially available duplex PCR, which combines pan-dermatophyte PCR with a Trichophyton rubrum-specific PCR, was evaluated. This Dermatophyte PCR kit, which requires one day for laboratory diagnosis, was compared with the conventional methods of microscopy and culture that necessitate up to 4 weeks for final diagnosis of dermatophytosis. We studied 177 nail samples from patients with suspected onychomycosis by fluorescence microscopy (blankophore), cultures and the Dermatophyte PCR kit. More samples were positive by PCR (78/177, 44%) than by culture (59/177, 34%). T. rubrum was present in 95% of all culture-positive nail specimens, which was confirmed by PCR in 55/56 specimens. The positive predictive value, negative predictive value, specificity and sensitivity of the duplex PCR was 93%, 87%, 94% and 85%, respectively, when confirmed by positive culture, microscopy or both. Due to its sensitivity, specificity and rapidity, we conclude that this PCR is an attractive method for routine investigation of nail dermatophytosis in a clinical setting.

Long-term efficacy of the tension-free vaginal tape procedure for the treatment of urinary incontinence: a retrospective follow-up 11.5 years post-operatively.

INTRODUCTION AND HYPOTHESIS: The aim was to evaluate the long-term cure rates and the late complications of the tension-free vaginal tape (TVT). METHODS: One hundred and forty-seven women with stress incontinence underwent surgery at our clinic between 1994 and 1997. At the time of follow-up, 128 were alive, 104 attended an objective evaluation at the clinic, while 20 women were contacted by telephone for an extensive interview. Eighty-four percent were assessed in a retrospective study 10-13 (11.5) years post-operatively. The evaluation included a stress test and, if this test was positive, also a 24-h pad-weighing test, the same questionnaire about urinary symptoms as that used pre-operatively and a visual analogue scale. RESULTS: The objective cure rate was 84%. The subjective cure rate was 77%, while 18% had improved. Ninety-four percent of the patients were satisfied with the surgical result. No late adverse effects of the operation were found. CONCLUSIONS: The TVT procedure is effective and safe for more than 10 years.

Analysis of ileal sodium/bile acid cotransporter and related nuclear receptor genes in a family with multiple cases of idiopathic bile acid malabsorption.

The etiology of most cases of idiopathic bile acid malabsorption (IBAM) is unknown. In this study, a Swedish family with bile acid malabsorption in three consecutive generations was screened for mutations in the ileal apical sodium-bile acid cotransporter gene (ASBT; gene symbol, SLC10A2) and in the genes for several of the nuclear receptors known to be important for ASBT expression: the farnesoid X receptor (FXR) and peroxisome proliferator activated receptor alpha (PPARalpha). The patients presented with a clinical history of idiopathic chronic watery diarrhea, which was responsive to cholestyramine treatment and consistent with IBAM. Bile acid absorption was determined using (75)Se-homocholic acid taurine (SeHCAT); bile acid synthesis was estimated by measuring the plasma levels of 7alpha-hydroxy-4-cholesten-3-one (C4). The ASBT, FXR, and PPARalpha genes in the affected and unaffected family members were analyzed using single stranded conformation polymorphism (SSCP), denaturing HPLC, and direct sequencing. No ASBT mutations were identified and the ASBT gene did not segregate with the bile acid malabsorption phenotype. Similarly, no mutations or polymorphisms were identified in the FXR or PPARalpha genes associated with the bile acid malabsorption phenotype. These studies indicate that the intestinal bile acid malabsorption in these patients cannot be attributed to defects in ASBT. In the absence of apparent ileal disease, alternative explanations such as accelerated transit through the small intestine may be responsible for the IBAM.

Common polymorphisms in the CYP7A1 gene do not contribute to variation in rates of bile acid synthesis and plasma LDL cholesterol concentration.

Transcriptional regulation of the cholesterol 7alpha-hydroxylase (CYP7AI) gene is of critical importance for bile acid and cholesterol metabolism. We evaluated the physiological significance of two common polymorphisms (-203C/A and -469T/C) in the promoter region of the CYP7AI gene. No evidence was found for physiological differences between either the -203C and -203A alleles or the -469T and -469C alleles in transient transfection studies using native 834bp promoter constructs. Moreover, no association was observed between the CYP7AI promoter polymorphisms and the hepatic cholesterol 7alpha-hydroxylase activity and parameters of bile acid synthesis rates, as analyzed in subjects with gallstone disease. In addition, no relationships were found between the promoter polymorphisms and plasma LDL cholesterol concentration in association studies conducted in three different groups of middle-aged Swedish men. Finally, near complete allelic association was found between the two promoter polymorphisms and the IVS6+363G/A polymorphism at the 3' end of the CYP7AI gene (|D'|=0.98), indicating strong linkage disequilibrium across the whole CYP7AI gene. It is concluded that common polymorphisms of the CYP7A1 gene do not contribute to variation in cholesterol 7alpha-hydroxylase activity, rates of bile acid synthesis and plasma LDL cholesterol concentration in humans.

Feedback regulation of bile acid synthesis in human liver: importance of HNF-4alpha for regulation of CYP7A1.

A great number of nuclear factors are involved in the negative feedback mechanism regulating bile acid synthesis. There are two major ways for the negative feedback to effect the synthesis; the SHP-dependent, involving FXR, and the SHP-independent way, affecting HNF-4alpha. We studied 23 patients with gallstone disease. Eight patients were treated with chenodeoxycholic acid, 7 with cholestyramine prior to operation, and 8 served as controls. Liver biopsies were analyzed with Real-time-PCR. In the cholestyramine-treated group mRNA levels of CYP7A1 were increased about 10-fold. Treatment with CDCA decreased the mRNA levels of CYP7A1 by about 70%. The mRNA levels of CYP8B1, CYP27A1, and CYP7B1 were not significantly altered in the treated groups. The analysis of mRNA levels for HNF-4alpha showed 64% higher levels in the cholestyramine-treated group compared to the controls. These levels showed positive and highly significant correlation to the levels of mRNA of CYP7A1 when studied in all three groups together. FXR, SHP, and LRH-1/FTF were not significantly affected by the different treatments. Our results indicate that when bile acid synthesis is upregulated by cholestyramine treatment the SHP-independent pathway for controlling CYP7A1 transcription dominates over the SHP-dependent pathway.