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Liu J, He X, Deng S, Zhao S, Zhang S, Chen Z, Xue C, Zeng L, Zhao H, Zhou Y, Bai R, Xu Z, Liu S, Zhou Q, Li M, Zhang J, Huang X, Chen R, Wang L, Lin D, Zheng J. QDPR deficiency drives immune suppression in pancreatic cancer. Cell Metab 2024; 36:984-999.e8. [PMID: 38642552 DOI: 10.1016/j.cmet.2024.03.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 12/20/2023] [Accepted: 03/28/2024] [Indexed: 04/22/2024]
Abstract
The relevance of biopterin metabolism in resistance to immune checkpoint blockade (ICB) therapy remains unknown. We demonstrate that the deficiency of quinoid dihydropteridine reductase (QDPR), a critical enzyme regulating biopterin metabolism, causes metabolite dihydrobiopterin (BH2) accumulation and decreases the ratio of tetrahydrobiopterin (BH4) to BH2 in pancreatic ductal adenocarcinomas (PDACs). The reduced BH4/BH2 ratio leads to an increase in reactive oxygen species (ROS) generation and a decrease in the distribution of H3K27me3 at CXCL1 promoter. Consequently, myeloid-derived suppressor cells are recruited to tumor microenvironment via CXCR2 causing resistance to ICB therapy. We discovered that BH4 supplementation is capable to restore the BH4/BH2 ratio, enhance anti-tumor immunity, and overcome ICB resistance in QDPR-deficient PDACs. Tumors with lower QDPR expression show decreased responsiveness to ICB therapy. These findings offer a novel strategy for selecting patient and combining therapies to improve the effectiveness of ICB therapy in PDAC.
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Affiliation(s)
- Ji Liu
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Xiaowei He
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Shuang Deng
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Sihan Zhao
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Shaoping Zhang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Ziming Chen
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Chunling Xue
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Lingxing Zeng
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Hongzhe Zhao
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Yifan Zhou
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Ruihong Bai
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Zilan Xu
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Shaoqiu Liu
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Quanbo Zhou
- Department of Pancreaticobiliary Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Mei Li
- Department of Pathology, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Jialiang Zhang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Xudong Huang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China
| | - Rufu Chen
- Guangdong Provincial People's Hospital & Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Liqin Wang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China; Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China.
| | - Dongxin Lin
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China; Department of Etiology and Carcinogenesis, National Cancer Center/National Clinical Research Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China.
| | - Jian Zheng
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China and Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China; Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China; Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China.
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Kaushik D, Gao L, Yuan K, Tang B, Kong R. LC-MS/MS methods for direct measurement of sepiapterin and tetrahydrobiopterin in human plasma and clinical applications. Bioanalysis 2024; 16:75-89. [PMID: 38099558 DOI: 10.4155/bio-2023-0144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023] Open
Abstract
Aim: Tetrahydrobiopterin (BH4), a natural cofactor of aromatic amino acid hydroxylases, and sepiapterin, a natural precursor of BH4, are endogenously present in human plasma. This is the first report on methods for direct quantification of sepiapterin and BH4 in human plasma by LC-MS/MS for pharmacokinetic assessment. Materials & methods: The analytes in plasma were harvested from blood that were treated with 10% ascorbic acid (AA) to a final concentration of 1% AA. Results & conclusion: The quantification methods were validated for calibration ranges of 0.75-500 ng/ml and 0.5-500 ng/ml for sepiapterin and BH4, respectively. Quantification of analytes was challenging due to their susceptibility to redox reactions. The validated methods were utilized successfully to support clinical development of sepiapterin.
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Affiliation(s)
- Diksha Kaushik
- PTC Therapeutics, Inc, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Lan Gao
- PTC Therapeutics, Inc, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Kun Yuan
- PTC Therapeutics, Inc, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Bowen Tang
- PTC Therapeutics, Inc, 100 Corporate Court, South Plainfield, NJ 07080, USA
| | - Ronald Kong
- PTC Therapeutics, Inc, 100 Corporate Court, South Plainfield, NJ 07080, USA
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Autoxidation Kinetics of Tetrahydrobiopterin-Giving Quinonoid Dihydrobiopterin the Consideration It Deserves. Molecules 2023; 28:molecules28031267. [PMID: 36770933 PMCID: PMC9921404 DOI: 10.3390/molecules28031267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 01/20/2023] [Accepted: 01/22/2023] [Indexed: 01/31/2023] Open
Abstract
In humans, tetrahydrobiopterin (H4Bip) is the cofactor of several essential hydroxylation reactions which dysfunction cause very serious diseases at any age. Hence, the determination of pterins in biological media is of outmost importance in the diagnosis and monitoring of H4Bip deficiency. More than half a century after the discovery of the physiological role of H4Bip and the recent advent of gene therapy for dopamine and serotonin disorders linked to H4Bip deficiency, the quantification of quinonoid dihydrobiopterin (qH2Bip), the transient intermediate of H4Bip, has not been considered yet. This is mainly due to its short half-life, which goes from 0.9 to 5 min according to previous studies. Based on our recent disclosure of the specific MS/MS transition of qH2Bip, here, we developed an efficient HPLC-MS/MS method to achieve the separation of qH2Bip from H4Bip and other oxidation products in less than 3.5 min. The application of this method to the investigation of H4Bip autoxidation kinetics clearly shows that qH2Bip's half-life is much longer than previously reported, and mostly longer than that of H4Bip, irrespective of the considered experimental conditions. These findings definitely confirm that an accurate method of H4Bip analysis should include the quantification of qH2Bip.
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Alhajji E, Boulghobra A, Bonose M, Berthias F, Moussa F, Maître P. Multianalytical Approach for Deciphering the Specific MS/MS Transition and Overcoming the Challenge of the Separation of a Transient Intermediate, Quinonoid Dihydrobiopterin. Anal Chem 2022; 94:12578-12585. [PMID: 36074025 DOI: 10.1021/acs.analchem.2c00924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Despite recent technological developments in analytical chemistry, separation and direct characterization of transient intermediates remain an analytical challenge. Among these, separation and direct characterization of quinonoid dihydrobiopterin (qH2Bip), a transient intermediate of tetrahydrobiopterin (H4Bip)-dependent hydroxylation reactions, essential in living organisms, with important and varied human pathophysiological impacts, are a clear illustration. H4Bip regeneration may be impaired by competitive nonenzymatic autoxidation reactions, such as isomerization of qH2Bip into a more stable 7,8-H2Bip (H2Bip) isomer, and subsequent nonenzymatic oxidation reactions. The quinonoid qH2Bip intermediate thus plays a key role in H4Bip-dependent hydroxylation reactions. However, only a few experimental results have indirectly confirmed this finding while revealing the difficulty of isolating qH2Bip from H4Bip-containing solutions. As a result, no current H4Bip assay method allows this isomer to be quantified even by liquid chromatography-tandem mass spectrometry (MS/MS). Here, we report isolation, structural characterization, and abundance of qH2Bip formed upon H4Bip autoxidation using three methods integrated into MS/MS. First, we characterized the structure of the two observed H2B isomers using IR photodissociation spectroscopy in conjunction with quantum chemical calculations. Then, we used differential ion mobility spectrometry to fully separate all oxidized forms of H4Bip including qH2Bip. These data are consistent and show that qH2Bip can also be unambiguously identified thanks to its specific MS/MS transition. This finding paves the way for the quantification of qH2Bip with MS/MS methods. Most importantly, the half-life value of this intermediate is nearly equivalent to that of H4Bip (tens of minutes), suggesting that an accurate method of H4Bip analysis should include the quantification of qH2Bip.
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Affiliation(s)
- Eskander Alhajji
- Institut de Chimie Physique, CNRS UMR 8000, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Ayoub Boulghobra
- Institut de Chimie Physique, CNRS UMR 8000, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Myriam Bonose
- Institut de Chimie Physique, CNRS UMR 8000, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Francis Berthias
- Institut de Chimie Physique, CNRS UMR 8000, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Fathi Moussa
- Institut de Chimie Physique, CNRS UMR 8000, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Philippe Maître
- Institut de Chimie Physique, CNRS UMR 8000, Université Paris-Saclay, 91405 Orsay Cedex, France
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Measurement of Tetrahydrobiopterin in Animal Tissue Samples by HPLC with Electrochemical Detection-Protocol Optimization and Pitfalls. Antioxidants (Basel) 2022; 11:antiox11061182. [PMID: 35740082 PMCID: PMC9228106 DOI: 10.3390/antiox11061182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 06/10/2022] [Accepted: 06/14/2022] [Indexed: 11/17/2022] Open
Abstract
Tetrahydrobiopterin (BH4) is an essential cofactor of all nitric oxide synthase isoforms, thus determination of BH4 levels can provide important mechanistic insight into diseases. We established a protocol for high-performance liquid chromatography/electrochemical detection (HPLC/ECD)-based determination of BH4 in tissue samples. We first determined the optimal storage and work-up conditions for authentic BH4 and its oxidation product dihydrobiopterin (BH2) under various conditions (pH, temperature, presence of antioxidants, metal chelators, and storage time). We then applied optimized protocols for detection of BH4 in tissues of septic (induced by lipopolysaccharide [LPS]) rats. BH4 standards in HCl are stabilized by addition of 1,4-dithioerythritol (DTE) and diethylenetriaminepentaacetic acid (DTPA), while HCl was sufficient for BH2 standard stabilization. Overnight storage of BH4 standard solutions at room temperature in HCl without antioxidants caused complete loss of BH4 and the formation of BH2. We further optimized the protocol to separate ascorbate and the BH4 tissue sample and found a significant increase in BH4 in the heart and kidney as well as higher BH4 levels by trend in the brain of septic rats compared to control rats. These findings correspond to reports on augmented nitric oxide and BH4 levels in both animals and patients with septic shock.
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Deng C, Wang S, Niu Z, Ye Y, Gao L. Newly established LC-MS/MS method for measurement of plasma BH4 as a predictive biomarker for kidney injury in diabetes. Free Radic Biol Med 2022; 178:1-6. [PMID: 34808334 DOI: 10.1016/j.freeradbiomed.2021.11.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 11/15/2021] [Accepted: 11/17/2021] [Indexed: 01/25/2023]
Abstract
OBJECTIVE The clinical research on BH4 is limited because of the difficulties on its measurement. In this study, we used our own established LC-MS/MS method to examine the plasma BH4 levels in diabetes to determine whether it could be used as a biomarker for the prediction of kidney injury in those patients. METHODS Hospitalized diabetes patients in Renmin Hospital of Wuhan University from Jan to Aug 2021 were recruited. To assess the association between plasma BH4 with ACR or eGFR in diabetes, a total of 142 patients with type 2 diabetes (T2DM) were enrolled. They were divided into three groups by albuminuria levels: normoalbuminuria (n = 68), microalbuminuria (n = 48), and macroalbuminuria (n = 26) according to ACR; or into two groups by eGFR: eGFR≥90 or eGFR<90 ml/min for correlation and logistic regression analysis. Plasma BH4 level was measured by LC-MS/MS along with other biochemical indices. RESULTS Plasma BH4 concentrations were decreased as ACR progressed. BH4 (r = -0.55, P < 0.001) and 2h C-Peptide (CP-2h) (r = -0.248, P = 0.003) levels were negatively correlated with ACR. Moreover, multivariable logistic regression analysis showed BH4 concentrations (B = -0.468, P < 0.001) and CP-2h (B = -0.257, P = 0.028) were independently associated with ACR progression. ROC curve showed that BH4 level has a predictive value on ACR (95%CI 0.686-0.841, sensitivity 69.1%, specificity 73%). Moreover, in diabetes patients with eGFR≥90 ml/min, plasma BH4 level (P = 0.008) is higher than those in diabetes with eGFR<90 ml/min and BH4 was remained independently associated with eGFR after multivariable logistic regression analysis (B = -0.193, P = 0.048). CONCLUSION Our established LC-MS/MS method could be used on human plasma BH4 measurements and our data suggested that BH4 level can be used as a biomarker for kidney injury in diabetes indicated by its association with ACR progression and early renal function decline.
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Affiliation(s)
- Chunxia Deng
- Department of Endocrinology & Metabolism, Renmin Hospital of Wuhan University, China
| | - Shuo Wang
- Department of Endocrinology & Metabolism, Renmin Hospital of Wuhan University, China
| | - Zhili Niu
- Department of Clinic Laboratory, Renmin Hospital of Wuhan University, China
| | - Yahong Ye
- Department of Endocrinology & Metabolism, Renmin Hospital of Wuhan University, China
| | - Ling Gao
- Department of Endocrinology & Metabolism, Renmin Hospital of Wuhan University, China.
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Scudellaro E, Tartaglione L, Varriale F, Dell’Aversano C, Taglialatela-Scafati O. HPLC-Based Analysis of Impurities in Sapropterin Branded and Generic Tablets. Pharmaceutics 2020; 12:pharmaceutics12040323. [PMID: 32260076 PMCID: PMC7237990 DOI: 10.3390/pharmaceutics12040323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/31/2020] [Accepted: 03/31/2020] [Indexed: 11/20/2022] Open
Abstract
This work was aimed at the definition of a chromatographic method able to separate and quantify impurities present in sapropterin-containing drugs during an accelerated stability study. The chromatographic method was applied to the orphan drug Kuvan® and to its corresponding generic sapropterin Dipharma (Diterin®), both of which are approved for the treatment of hyperphenylalaninemia-induced symptoms. The two products tested had a similar manufacture date and both had an approved stability shelf-life of three years. Samples were analyzed by HPLC at T = 0 and after six months of storage at 40 °C and 75% relative humidity. Identification of the impurities was supported by a detailed mass spectrometry and MS/MS profile. The analysis demonstrated an overall higher stability for the Diterin® formulation, which was related to a lower increase of some impurities compared to Kuvan®.
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Meyer JT, Sparling BA, McCarty WJ, Zhang M, Soto M, Schneider S, Chen H, Roberts J, Tan H, Kornecook T, Andrews PS, Knutson CG. Pharmacological Assessment of Sepiapterin Reductase Inhibition on Tactile Response in the Rat. J Pharmacol Exp Ther 2019; 371:476-486. [PMID: 31110114 DOI: 10.1124/jpet.119.257105] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 05/15/2019] [Indexed: 12/17/2023] Open
Abstract
There is an unmet medical need for nonopioid pain therapies in human populations; several pathways are under investigation for possible therapeutic intervention. Tetrahydrobiopterin (BH4) has received attention recently as a mediator of neuropathic pain. Recent reports have implicated sepiapterin reductase (SPR) in this pain pathway as a regulator of BH4 production. To evaluate the role of SPR inhibition on BH4 reduction, we developed analytical methods to monitor the relationship between the plasma concentration of test article and endogenous pterins and applied these in the rat spinal nerve ligation pain model. Sepiapterin is an endogenous substrate, which accumulates upon inhibition of SPR. In response to a potent inhibitor of SPR, plasma concentrations of sepiapterin increased proportionally with exposure. An indirect-effect pharmacokinetic/pharmacodynamic model was developed to describe the relationship between the plasma pharmacokinetics of test article and plasma sepiapterin levels in the rat, which was used to determine an in vivo SPR IC50 value. SPR inhibition and mechanical allodynia were assessed coordinately with pterin biomarkers in plasma and at the site of neuronal injury (i.e., dorsal root ganglion). Upon daily oral administration for 3 consecutive days, unbound plasma concentrations of test article exceeded the unbound in vivo rat SPR IC90 throughout the dose intervals, leading to a 60% reduction in BH4 in the dorsal root ganglion. Despite evidence for pharmacological modulation of the BH4 pathway, there was no significant effect on the tactile paw withdrawal threshold relative to vehicle-treated controls.
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Affiliation(s)
- James T Meyer
- Amgen Research, Thousand Oaks, California (J.T.M., M.Z., M.S., H.T., T.K.) and Amgen Research, Cambridge, Massachusetts (B.A.S., W.J.M., S.S., H.C., J.R., P.A., C.G.K.)
| | - Brian A Sparling
- Amgen Research, Thousand Oaks, California (J.T.M., M.Z., M.S., H.T., T.K.) and Amgen Research, Cambridge, Massachusetts (B.A.S., W.J.M., S.S., H.C., J.R., P.A., C.G.K.)
| | - William J McCarty
- Amgen Research, Thousand Oaks, California (J.T.M., M.Z., M.S., H.T., T.K.) and Amgen Research, Cambridge, Massachusetts (B.A.S., W.J.M., S.S., H.C., J.R., P.A., C.G.K.)
| | - Maosheng Zhang
- Amgen Research, Thousand Oaks, California (J.T.M., M.Z., M.S., H.T., T.K.) and Amgen Research, Cambridge, Massachusetts (B.A.S., W.J.M., S.S., H.C., J.R., P.A., C.G.K.)
| | - Marcus Soto
- Amgen Research, Thousand Oaks, California (J.T.M., M.Z., M.S., H.T., T.K.) and Amgen Research, Cambridge, Massachusetts (B.A.S., W.J.M., S.S., H.C., J.R., P.A., C.G.K.)
| | - Stephen Schneider
- Amgen Research, Thousand Oaks, California (J.T.M., M.Z., M.S., H.T., T.K.) and Amgen Research, Cambridge, Massachusetts (B.A.S., W.J.M., S.S., H.C., J.R., P.A., C.G.K.)
| | - Hao Chen
- Amgen Research, Thousand Oaks, California (J.T.M., M.Z., M.S., H.T., T.K.) and Amgen Research, Cambridge, Massachusetts (B.A.S., W.J.M., S.S., H.C., J.R., P.A., C.G.K.)
| | - Jonathan Roberts
- Amgen Research, Thousand Oaks, California (J.T.M., M.Z., M.S., H.T., T.K.) and Amgen Research, Cambridge, Massachusetts (B.A.S., W.J.M., S.S., H.C., J.R., P.A., C.G.K.)
| | - Helming Tan
- Amgen Research, Thousand Oaks, California (J.T.M., M.Z., M.S., H.T., T.K.) and Amgen Research, Cambridge, Massachusetts (B.A.S., W.J.M., S.S., H.C., J.R., P.A., C.G.K.)
| | - Thomas Kornecook
- Amgen Research, Thousand Oaks, California (J.T.M., M.Z., M.S., H.T., T.K.) and Amgen Research, Cambridge, Massachusetts (B.A.S., W.J.M., S.S., H.C., J.R., P.A., C.G.K.)
| | - Paul S Andrews
- Amgen Research, Thousand Oaks, California (J.T.M., M.Z., M.S., H.T., T.K.) and Amgen Research, Cambridge, Massachusetts (B.A.S., W.J.M., S.S., H.C., J.R., P.A., C.G.K.)
| | - Charles G Knutson
- Amgen Research, Thousand Oaks, California (J.T.M., M.Z., M.S., H.T., T.K.) and Amgen Research, Cambridge, Massachusetts (B.A.S., W.J.M., S.S., H.C., J.R., P.A., C.G.K.)
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Jung-Klawitter S, Kuseyri Hübschmann O. Analysis of Catecholamines and Pterins in Inborn Errors of Monoamine Neurotransmitter Metabolism-From Past to Future. Cells 2019; 8:cells8080867. [PMID: 31405045 PMCID: PMC6721669 DOI: 10.3390/cells8080867] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 08/02/2019] [Accepted: 08/04/2019] [Indexed: 12/13/2022] Open
Abstract
Inborn errors of monoamine neurotransmitter biosynthesis and degradation belong to the rare inborn errors of metabolism. They are caused by monogenic variants in the genes encoding the proteins involved in (1) neurotransmitter biosynthesis (like tyrosine hydroxylase (TH) and aromatic amino acid decarboxylase (AADC)), (2) in tetrahydrobiopterin (BH4) cofactor biosynthesis (GTP cyclohydrolase 1 (GTPCH), 6-pyruvoyl-tetrahydropterin synthase (PTPS), sepiapterin reductase (SPR)) and recycling (pterin-4a-carbinolamine dehydratase (PCD), dihydropteridine reductase (DHPR)), or (3) in co-chaperones (DNAJC12). Clinically, they present early during childhood with a lack of monoamine neurotransmitters, especially dopamine and its products norepinephrine and epinephrine. Classical symptoms include autonomous dysregulations, hypotonia, movement disorders, and developmental delay. Therapy is predominantly based on supplementation of missing cofactors or neurotransmitter precursors. However, diagnosis is difficult and is predominantly based on quantitative detection of neurotransmitters, cofactors, and precursors in cerebrospinal fluid (CSF), urine, and blood. This review aims at summarizing the diverse analytical tools routinely used for diagnosis to determine quantitatively the amounts of neurotransmitters and cofactors in the different types of samples used to identify patients suffering from these rare diseases.
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Affiliation(s)
- Sabine Jung-Klawitter
- Department of General Pediatrics, Division of Neuropediatrics and Metabolic Medicine, University Hospital Heidelberg, 69120 Heidelberg, Germany.
| | - Oya Kuseyri Hübschmann
- Department of General Pediatrics, Division of Neuropediatrics and Metabolic Medicine, University Hospital Heidelberg, 69120 Heidelberg, Germany
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Aziz MY, Chik Z. Bioanalysis of tetrahydrobiopterin with liquid chromatographic-mass spectrometric and its application for pharmacokinetics in apolipoprotein E knockout mice. J LIQ CHROMATOGR R T 2019. [DOI: 10.1080/10826076.2019.1625376] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Mohd Yusmaidie Aziz
- Integrative Medicine Cluster, Institut Perubatan dan Pergigian Termaju, Universiti Sains Malaysia, Bertam, Penang, Malaysia
| | - Zamri Chik
- Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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Yuan TF, Huang HQ, Gao L, Wang ST, Li Y. A novel and reliable method for tetrahydrobiopterin quantification: Benzoyl chloride derivatization coupled with liquid chromatography-tandem mass spectrometry analysis. Free Radic Biol Med 2018; 118:119-125. [PMID: 29501564 DOI: 10.1016/j.freeradbiomed.2018.02.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 02/02/2018] [Accepted: 02/26/2018] [Indexed: 01/15/2023]
Abstract
Tetrahydrobiopterin (BH4) is a crucial cofactor for nitric oxide synthase, acylglycerol mono-oxygenase and aromatic amino acids hydroxylases. Its significant function for redox pathways in vivo attracted much attention for long. However, because of the oxidizable and substoichiometric nature, analysis of BH4 has never been truly achieved with adequate sensitivity and applicability. In the present work, we pioneeringly stabilized BH4 by derivatizing the active secondary amine on five-position with benzoyl chloride (BC). Benefiting from the favorable chemical stability and excellent mass spectrometric sensitivity of the product (BH4-BC), ultra-sensitive and reliable quantification of endogenous BH4 in plasma was achieved using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. In such methodology, BH4-BC-d5 was introduced as stable isotopic internal standard. And the limit of quantification (LOQ) could reach 0.02 ng mL-1. In the end, after investigation of plasma BH4 in healthy volunteers (n = 38), we found that the levels of BH4 were significantly and negatively correlated to age. Comparing with all the other existed strategies, the present method was obviously superior in sensitivity, specificity and practical applicability. It could be expected that this work could largely promote the future studies in BH4-related fields.
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Affiliation(s)
- Teng-Fei Yuan
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Han-Qi Huang
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Ling Gao
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Shao-Ting Wang
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan 430060, China.
| | - Yan Li
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan 430060, China.
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12
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Xiong X, Zhang Y, Zhang W. Simultaneous determination of twelve polar pteridines including dihydro- and tetrahydropteridine in human urine by hydrophilic interaction liquid chromatography with tandem mass spectrometry. Biomed Chromatogr 2018; 32:e4244. [PMID: 29575016 DOI: 10.1002/bmc.4244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 03/07/2018] [Accepted: 03/09/2018] [Indexed: 11/07/2022]
Abstract
Pteridines and their derivatives are important cofactors in the process of cell metabolism, and the level of urinary excretion of these compounds is considered as an important clinical criterion. In this work, a new separation method involving hydrophilic interaction chromatography (HILIC) with tandem mass spectrometric detection has been developed for the simultaneous analysis of 12 pteridines including oxidized, di- and tetrahydroforms, namely neopterin, 7,8-dihydroneopterin, biopterin, 7,8-dihydrobiopterin, 5,6,7,8-tetrahydrobiopterin, dimethylpterin, dimethyltetrahydropterin, pterin, isoxanthopterin, xanthopterin, sepiapterin and pterin-6-carboxylic acid, in human urine without oxidative pretreatments. The stabilizing agent (dithiothreitol) at various concentrations and the stability of oxidized, di- and tetrahydroforms during the sample's short-term storage and processing and of the extracts were tested. In the developed method, 12 pteridines were chromatographically separated on an ZIC-HILIC column by gradient elution, and the run time was 20 min. Matrix effect was evaluated and several dilutions of urine were tested in order to study the evolution of signal suppression. Spiked recovery studies demonstrated that the technique was both accurate (83.1-116.7%) and precise (RSD 1.4-15.6%). Finally, several clinical urine specimens without oxidative pretreatments were examined with the new technique and compared with previous reports.
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Affiliation(s)
- Xin Xiong
- Department of Pharmacy, Peking University Third Hospital, Beijing, China
| | - Yuanyuan Zhang
- Department of Pharmacy, Peking University Third Hospital, Beijing, China
| | - Wenjing Zhang
- Department of Laboratory Medicine, Peking University Third Hospital, Beijing, China
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13
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Dabrowska M, Uram L, Zielinski Z, Rode W, Sikora E. Oxidative stress and inhibition of nitric oxide generation underlie methotrexate-induced senescence in human colon cancer cells. Mech Ageing Dev 2018; 170:22-29. [DOI: 10.1016/j.mad.2017.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/10/2017] [Accepted: 07/19/2017] [Indexed: 10/19/2022]
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14
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15
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Guibal P, Lo A, Maitre P, Moussa F. Pterin determination in cerebrospinal fluid: state of the art. Pteridines 2017. [DOI: 10.1515/pterid-2017-0001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
The analysis of pterins in the cerebrospinal fluid (CSF) is mandatory for the etiologic diagnosis of inborn errors of dopamine and serotonin metabolism. The success of the available therapeutic strategies for preventing the ongoing brain dysfunction is tightly dependent of the early diagnosis of these neurotransmitter disorders. Previous methods of pterins determination in the CSF have in common at least one reversed phase HPLC step coupled to electrochemical or fluorescence detection (FD). They differ in the oxidation procedure of the reduced forms of pterins into their oxidized fluorescent counterparts. Most of the methods using the FD include at least one offline chemical oxidation procedure and cannot allow the direct quantification of tetrahydrobiopterin (BH4). A recent method proposed a single step simultaneous quantification of all forms of pterins including BH4 by HPLC coupled to FD after post-column coulometric oxidation. Nowadays, recent advances in mass spectrometry (MS), notably in term of sensitivity, allow the direct unambiguous determination of all forms of pterins in the CSF by LC-MS/MS.
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Affiliation(s)
- Pierre Guibal
- Letiam, Lip(Sys) , Université Paris-Sud , IUT d’Orsay, Plateau de Moulon , 91405 Orsay , France
| | - Aurélien Lo
- Letiam, Lip(Sys) , Université Paris-Sud , IUT d’Orsay, Plateau de Moulon , 91405 Orsay , France
| | - Philippe Maitre
- Laboratoire de Chimie Physique , UMR 8000 CNRS , Faculté des Sciences d’Orsay, Université Paris-Sud , 15, Rue G. Clemenceau , 91400 Orsay , France
| | - Fathi Moussa
- Letiam, Lip(Sys) , Université Paris-Sud , IUT d’Orsay, Plateau de Moulon , 91405 Orsay , France
- Service de Biochimie, Groupe Hospitalier Trousseau-La Roche Guyon , APHP, 26 Avenue du Dr A. Netter , 75012 Paris , France
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16
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Abstract
Abstract
Pteridines and their derivatives function as intermediates in the metabolism of several vitamins and cofactors, and their relevance to disease has inspired new efforts to study their roles as disease biomarkers. Recent analytical advances, such as the emergence of sensitive mass spectrometry techniques, new workflows for measuring pteridine derivatives in their native oxidation states and increased multiplexing capacities for the simultaneous determination of many pteridine derivatives, have enabled researchers to explore the roles of urinary pteridines as disease biomarkers at much lower levels with greater accuracy than with previous technologies or methods. As a result, urinary pteridines are being increasingly studied as putative cancer biomarkers with promising results being reported from exploratory studies. In addition, the role of urinary neopterin as a universal biomarker for immune system activation is being investigated in new diseases where it is anticipated to become a useful supplementary marker in clinical diagnostic settings. In summary, this review provides an overview of recent developments in the clinical study of urinary pteridines as disease biomarkers, covers the most promising aspects of advanced analytical techniques being developed for the determination of urinary pteridines and discusses the major challenges associated with implementing pteridine biomarkers in clinical laboratory settings.
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Affiliation(s)
- Casey Burton
- Department of Chemistry and Center for Single Nanoparticle, Single Cell, and Single Molecule Monitoring, Missouri University of Science and Technology, Rolla, MO, USA
| | - Yinfa Ma
- Department of Chemistry and Center for Single Nanoparticle, Single Cell, and Single Molecule Monitoring, Missouri University of Science and Technology, 400 West 11th Street, Rolla, MO 65409, USA
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17
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Burton C, Shi H, Ma Y. Development of a high-performance liquid chromatography – Tandem mass spectrometry urinary pterinomics workflow. Anal Chim Acta 2016; 927:72-81. [DOI: 10.1016/j.aca.2016.05.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 05/01/2016] [Accepted: 05/02/2016] [Indexed: 10/21/2022]
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18
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Xiong X, Liu Y. Chromatographic behavior of 12 polar pteridines in hydrophilic interaction chromatography using five different HILIC columns coupled with tandem mass spectrometry. Talanta 2016; 150:493-502. [DOI: 10.1016/j.talanta.2015.12.066] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 12/21/2015] [Accepted: 12/24/2015] [Indexed: 11/25/2022]
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19
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Trenchard IJ, Siddiqui MS, Thodey K, Smolke CD. De novo production of the key branch point benzylisoquinoline alkaloid reticuline in yeast. Metab Eng 2015; 31:74-83. [PMID: 26166409 DOI: 10.1016/j.ymben.2015.06.010] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 06/22/2015] [Accepted: 06/30/2015] [Indexed: 12/28/2022]
Abstract
Microbial biosynthesis for plant-based natural products, such as the benzylisoquinoline alkaloids (BIAs), has the potential to address limitations in plant-based supply of established drugs and make new molecules available for drug discovery. While yeast strains have been engineered to produce a variety of downstream BIAs including the opioids, these strains have relied on feeding an early BIA substrate. We describe the de novo synthesis of the major BIA branch point intermediate reticuline via norcoclaurine in Saccharomyces cerevisiae. Modifications were introduced into yeast central metabolism to increase supply of the BIA precursor tyrosine, allowing us to achieve a 60-fold increase in production of the early benzylisoquinoline scaffold from fed dopamine with no supply of exogenous tyrosine. Yeast strains further engineered to express a mammalian tyrosine hydroxylase, four mammalian tetrahydrobiopterin biosynthesis and recycling enzymes, and a bacterial DOPA decarboxylase produced norcoclaurine de novo. We further increased production of early benzylisoquinoline scaffolds by 160-fold through introducing mutant tyrosine hydroxylase enzymes, an optimized plant norcoclaurine synthase variant, and optimizing culture conditions. Finally, we incorporated five additional plant enzymes--three methyltransferases, a cytochrome P450, and its reductase partner--to achieve de novo production of the key branch point molecule reticuline with a titer of 19.2 μg/L. These strains and reconstructed pathways will serve as a platform for the biosynthesis of diverse natural and novel BIAs.
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Affiliation(s)
- Isis J Trenchard
- Department of Bioengineering, Stanford University, 443 Via Ortega, MC 4245, Stanford, CA 94305, United States
| | - Michael S Siddiqui
- Department of Chemical Engineering; Stanford University, Stanford, CA 94305, United States
| | - Kate Thodey
- Department of Bioengineering, Stanford University, 443 Via Ortega, MC 4245, Stanford, CA 94305, United States
| | - Christina D Smolke
- Department of Bioengineering, Stanford University, 443 Via Ortega, MC 4245, Stanford, CA 94305, United States.
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20
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High-throughput intracellular pteridinic profiling by liquid chromatography–quadrupole time-of-flight mass spectrometry. Anal Chim Acta 2015; 853:442-450. [DOI: 10.1016/j.aca.2014.10.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 10/28/2014] [Accepted: 10/30/2014] [Indexed: 02/08/2023]
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21
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A rebuttal to “A comment to ‘Normalization of urinary pteridines by urine specific gravity for early cancer detection’ [Clin. Chim. Acta 435 (2014) 42–47]”. Clin Chim Acta 2015; 438:415-7. [DOI: 10.1016/j.cca.2014.08.044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 08/25/2014] [Indexed: 11/20/2022]
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22
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Arning E, Bottiglieri T. LC-MS/MS Analysis of Cerebrospinal Fluid Metabolites in the Pterin Biosynthetic Pathway. JIMD Rep 2014; 29:1-9. [PMID: 25213568 PMCID: PMC5059177 DOI: 10.1007/8904_2014_336] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 06/18/2014] [Accepted: 07/01/2014] [Indexed: 12/12/2022] Open
Abstract
The analysis of (6R)-5,6,7,8-tetrahydrobiopterin (BH4) and neopterin in cerebrospinal fluid (CSF) is often used to identify defects in the pterin biosynthetic pathway affecting monoamine metabolism that can lead to pediatric neurotransmitter diseases. Low levels of BH4 and neopterin alone may not be sufficient to determine the defect, and further testing is often required. We have developed a sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method for determination of BH4, 7,8-dihydrobiopterin (BH2), neopterin, and sepiapterin in CSF, which provides a more comprehensive evaluation of the pterin pathway. The method utilizes labeled stable isotopes as internal standards and allows for a fast 10-minute analysis by LC/MS/MS over a linear working range of 3 to 200 nmol/L. Total analytical imprecision is less than 14.4% for all pterin metabolites. Accuracy for BH4 and neopterin was determined by comparing data obtained by an alternative method using HPLC with EC and fluorescence detection. Excellent correlation was demonstrated for BH4 (r = 0.9646, 1/slope = 0.9397; n = 28; concentration range 3 to 63 nmol/L) and neopterin (r = 0.9919, 1/slope = 0.9539; n = 13; concentration range 5 to 240 nmol/L). CSF specimens from patients diagnosed with inborn errors of sepiapterin reductase (SR), 6-pyruvoyl-tetrahydropterin synthase (PTPS), dihydropteridine reductase (DHPR), and guanosine triphosphate cyclohydrolase (GTPCH) have been analyzed, and distinct pterin metabolite patterns were consistent with the initial diagnosis. This method differentiates patients with DHPR and SR deficiency from other pterin defects (GTPCH and PTPS) and will be useful for the diagnosis of specific defects in the pterin biosynthetic pathway.
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Affiliation(s)
- Erland Arning
- Baylor Research Institute, Institute of Metabolic Disease, Dallas, TX, 75226, USA.
| | - Teodoro Bottiglieri
- Baylor Research Institute, Institute of Metabolic Disease, Dallas, TX, 75226, USA
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23
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Guibal P, Lévêque N, Doummar D, Giraud N, Roze E, Rodriguez D, Couderc R, Billette
De Villemeur T, Moussa F. Simultaneous determination of all forms of biopterin and neopterin in cerebrospinal fluid. ACS Chem Neurosci 2014; 5:533-41. [PMID: 24650440 PMCID: PMC4102970 DOI: 10.1021/cn4001928] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 03/16/2014] [Indexed: 11/29/2022] Open
Abstract
In humans, genetic defects of the synthesis or regeneration of tetrahydrobiopterin (BH4), an essential cofactor in hydroxylation reactions, are associated with severe neurological disorders. The diagnosis of these conditions relies on the determination of BH4, dihydrobiopterin (BH2), and dihydroneopterin (NH2) in cerebrospinal fluid (CSF). As MS/MS is less sensitive than fluorescence detection (FD) for this purpose, the most widely used method since 1980 involves two HPLC runs including two differential off-line chemical oxidation procedures aiming to transform the reduced pterins into their fully oxidized fluorescent counterparts, biopterin (B) and neopterin (N). However, this tedious and time-consuming two-step indirect method underestimates BH4, BH2, and NH2 concentrations. Direct quantification of BH4 is essential for studying its metabolism and for monitoring the efficacy of BH4 supplementation in patients with genetic defects. Here we describe a single step method to simultaneously measure BH4, BH2, B, NH2, and N in CSF by HPLC coupled to FD after postcolumn coulometric oxidation. All target pterins were quantified in CSF with a small volume (100 μL), and a single filtration step for sample preparation and analysis. As compared to the most widely used method in more than 100 CSF samples, this new assay is the easiest route for accurately determining in a single run BH4, BH2, and NH2 in CSF in deficit situations as well as for monitoring the efficacy of the treatment.
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Affiliation(s)
- Pierre Guibal
- LETIAM, GCAPS,
EA 4041, IUT d’Orsay, Université Paris Sud 11, Plateau de Moulon. 91400 Orsay, France
| | - Nathalie Lévêque
- LETIAM, GCAPS,
EA 4041, IUT d’Orsay, Université Paris Sud 11, Plateau de Moulon. 91400 Orsay, France
| | - Diane Doummar
- Services
de Neuropédiatrie
et de Biochimie, Groupe Hospitalier Trousseau − Laroche −
Guyon, 26 avenue du Dr Arnold Netter, 75012 Paris, France
| | - Nicolas Giraud
- UMR CNRS
8182. ICMMO:
RMN en milieu orienté. UFR des Sciences, Université
Paris Sud 11. Rue du Doyen Georges
Poitou. 91400 Orsay, France
| | - Emmanuel Roze
- Department
of Neurology, Pitié-Salpêtrière
Hospital, AP-HP, 75013 Paris, France
- UMR S 952, INSERM,
Paris 6 University, 75005 Paris, France
| | - Diana Rodriguez
- Services
de Neuropédiatrie
et de Biochimie, Groupe Hospitalier Trousseau − Laroche −
Guyon, 26 avenue du Dr Arnold Netter, 75012 Paris, France
| | - Rémy Couderc
- Services
de Neuropédiatrie
et de Biochimie, Groupe Hospitalier Trousseau − Laroche −
Guyon, 26 avenue du Dr Arnold Netter, 75012 Paris, France
| | - Thierry Billette
De Villemeur
- Services
de Neuropédiatrie
et de Biochimie, Groupe Hospitalier Trousseau − Laroche −
Guyon, 26 avenue du Dr Arnold Netter, 75012 Paris, France
| | - Fathi Moussa
- LETIAM, GCAPS,
EA 4041, IUT d’Orsay, Université Paris Sud 11, Plateau de Moulon. 91400 Orsay, France
- Services
de Neuropédiatrie
et de Biochimie, Groupe Hospitalier Trousseau − Laroche −
Guyon, 26 avenue du Dr Arnold Netter, 75012 Paris, France
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24
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Fismen L, Eide T, Hjelde A, Svardal AM, Djurhuus R. Hyperoxia but not ambient pressure decreases tetrahydrobiopterin level without affecting the enzymatic capability of nitric oxide synthase in human endothelial cells. Eur J Appl Physiol 2013; 113:1695-704. [PMID: 23385656 DOI: 10.1007/s00421-013-2595-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 01/19/2013] [Indexed: 11/26/2022]
Abstract
Nitric oxide (NO) seems to be related to bubble formation and endothelial dysfunction resulting in decompression sickness. Bubble formation can be affected by aerobic exercise or manipulating NO. A prior heat stress (HS) has been shown to confer protection against decompression sickness in rats. An important question was if the oxidative environment experienced during diving limits the availability of the nitric oxide synthase (NOS) cofactor tetrahydrobiopterin (BH4). Human endothelial cells were used to investigate how HS and simulated diving affected NO synthesis and defense systems such as heat shock protein 70 (HSP70) and glutathione (GSH). BH4 was measured using a novel LC-MS/MS method and NOS by monitoring the conversion of radiolabeled L-arginine to L-citrulline. Increased pO₂ reduced BH4 levels in cells in a dose-dependent manner independently of high pressure. This effect may result in decreased generation of NO by NOS. The BH4 decrease seemed to be abolished when cells were exposed to HS prior to hyperoxia. NOS enzyme was unaffected by increased pO₂ but substantially reduced after HS. The BH4 level seemed to a minor extent to be dependent upon GSH and probably to a higher degree dependent on other antioxidants such as ascorbic acid. A simulated dive at 60 kPa O₂ had a potentiating effect on the heat-induced HSP70 expression, whereas GSH levels were unaffected by hyperoxic exposure. HS, hyperoxia, and dive affected several biochemical parameters that may play important roles in the mechanisms protecting against the adverse effects of saturation diving.
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Affiliation(s)
- Lise Fismen
- Norwegian Underwater Intervention AS, 5848, Bergen, Norway.
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