1
|
Pade LR, Stepler KE, Portero EP, DeLaney K, Nemes P. Biological mass spectrometry enables spatiotemporal 'omics: From tissues to cells to organelles. MASS SPECTROMETRY REVIEWS 2024; 43:106-138. [PMID: 36647247 PMCID: PMC10668589 DOI: 10.1002/mas.21824] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/14/2022] [Accepted: 09/17/2022] [Indexed: 06/17/2023]
Abstract
Biological processes unfold across broad spatial and temporal dimensions, and measurement of the underlying molecular world is essential to their understanding. Interdisciplinary efforts advanced mass spectrometry (MS) into a tour de force for assessing virtually all levels of the molecular architecture, some in exquisite detection sensitivity and scalability in space-time. In this review, we offer vignettes of milestones in technology innovations that ushered sample collection and processing, chemical separation, ionization, and 'omics analyses to progressively finer resolutions in the realms of tissue biopsies and limited cell populations, single cells, and subcellular organelles. Also highlighted are methodologies that empowered the acquisition and analysis of multidimensional MS data sets to reveal proteomes, peptidomes, and metabolomes in ever-deepening coverage in these limited and dynamic specimens. In pursuit of richer knowledge of biological processes, we discuss efforts pioneering the integration of orthogonal approaches from molecular and functional studies, both within and beyond MS. With established and emerging community-wide efforts ensuring scientific rigor and reproducibility, spatiotemporal MS emerged as an exciting and powerful resource to study biological systems in space-time.
Collapse
Affiliation(s)
- Leena R. Pade
- Department of Chemistry & Biochemistry, University of Maryland, 8051 Regents Drive, College Park, MD 20742
| | - Kaitlyn E. Stepler
- Department of Chemistry & Biochemistry, University of Maryland, 8051 Regents Drive, College Park, MD 20742
| | - Erika P. Portero
- Department of Chemistry & Biochemistry, University of Maryland, 8051 Regents Drive, College Park, MD 20742
| | - Kellen DeLaney
- Department of Chemistry & Biochemistry, University of Maryland, 8051 Regents Drive, College Park, MD 20742
| | - Peter Nemes
- Department of Chemistry & Biochemistry, University of Maryland, 8051 Regents Drive, College Park, MD 20742
| |
Collapse
|
2
|
Phetsanthad A, Vu NQ, Yu Q, Buchberger AR, Chen Z, Keller C, Li L. Recent advances in mass spectrometry analysis of neuropeptides. MASS SPECTROMETRY REVIEWS 2023; 42:706-750. [PMID: 34558119 PMCID: PMC9067165 DOI: 10.1002/mas.21734] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 08/22/2021] [Accepted: 08/28/2021] [Indexed: 05/08/2023]
Abstract
Due to their involvement in numerous biochemical pathways, neuropeptides have been the focus of many recent research studies. Unfortunately, classic analytical methods, such as western blots and enzyme-linked immunosorbent assays, are extremely limited in terms of global investigations, leading researchers to search for more advanced techniques capable of probing the entire neuropeptidome of an organism. With recent technological advances, mass spectrometry (MS) has provided methodology to gain global knowledge of a neuropeptidome on a spatial, temporal, and quantitative level. This review will cover key considerations for the analysis of neuropeptides by MS, including sample preparation strategies, instrumental advances for identification, structural characterization, and imaging; insightful functional studies; and newly developed absolute and relative quantitation strategies. While many discoveries have been made with MS, the methodology is still in its infancy. Many of the current challenges and areas that need development will also be highlighted in this review.
Collapse
Affiliation(s)
- Ashley Phetsanthad
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
| | - Nhu Q. Vu
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
| | - Qing Yu
- School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, WI 53705, USA
| | - Amanda R. Buchberger
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
| | - Zhengwei Chen
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
| | - Caitlin Keller
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
| | - Lingjun Li
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
- School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, WI 53705, USA
| |
Collapse
|
3
|
Narita N, Yamada R, Kakehi M, Kimura H. Diurnal Fluctuations of Orexin-A and -B in Cynomolgus Monkey Cerebrospinal Fluid Determined by a Novel Analytical Method Using Antiadsorptive Additive Treatment Followed by Nanoflow Liquid Chromatography-High-Resolution Mass Spectrometry. ACS Chem Neurosci 2023; 14:609-618. [PMID: 36719857 PMCID: PMC9936545 DOI: 10.1021/acschemneuro.2c00370] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Orexin-A (OXA) and -B (OXB) are involved in the regulation of multiple physiological functions including the sleep-wake states; therefore, it is critical to monitor their levels under various conditions. Unfortunately, the widely used radioimmunoassay has insufficient specificity for OXA. Although liquid chromatography-tandem mass spectrometry (LC-MS/MS) has higher specificity for OXA, previously reported OXA levels in human cerebrospinal fluid (CSF) measured using this technique are still inconsistent. Moreover, to the best of our knowledge, OXB has not been detected in the CSF. In this study, we established a novel method for OXA and OXB measurement. We noticed that OXA and OXB in the CSF was sticky; thus, citric acid and Tween 80 were used to prevent their nonspecific binding. Then, highly specific and sensitive nanoflow liquid chromatography-high-resolution mass spectrometry (nanoLC-HRMS) was used to measure OXA and OXB levels. Evaluation of the diurnal fluctuations of OXA and OXB in cisternal and lumbar CSF samples from cynomolgus monkeys revealed a sharp increase in the early light period, followed by a gradual increase to the maximum levels at the end of the light period, and then a sharp drop to the minimum levels during the early dark period. OXB levels were lower than OXA levels in cisternal CSF. Although basal OXA levels in individual monkeys showed substantial variations, the ratios between the maximum and minimum OXA levels of each monkey were similar. Our method for accurate OXA and OXB measurement should help improve our knowledge of orexin biology.
Collapse
Affiliation(s)
- Naohiro Narita
- Drug
Metabolism and Pharmacokinetics Laboratory, Research, Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Ryuji Yamada
- Neuroscience
Drug Discovery Unit, Research, Takeda Pharmaceutical
Company Limited, 26-1 Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Masaaki Kakehi
- Drug
Metabolism and Pharmacokinetics Laboratory, Research, Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Haruhide Kimura
- Neuroscience
Drug Discovery Unit, Research, Takeda Pharmaceutical
Company Limited, 26-1 Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan,
| |
Collapse
|
4
|
van der Hoeven AE, van Waaij K, Bijlenga D, Roelandse FWC, Overeem S, Bakker JA, Fronczek R, Lammers GJ. Hypocretin-1 measurements in cerebrospinal fluid using radioimmunoassay: within and between assay reliability and limit of quantification. Sleep 2022; 45:6581446. [PMID: 35512685 PMCID: PMC9272241 DOI: 10.1093/sleep/zsac103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 03/30/2022] [Indexed: 11/23/2022] Open
Abstract
Study Objectives The most sensitive and specific investigative method for the diagnosis of narcolepsy type 1 (NT1) is the determination of hypocretin-1 (orexin-A) deficiency (≤110 pg/mL) in cerebrospinal fluid using a radioimmunoassay (RIA). We aimed to assess the reliability of the Phoenix Pharmaceuticals hypocretin-1 RIA, by determining the lower limit of quantification (LLOQ), the variability around the cutoff of 110 pg/mL, and the inter- and intra-assay variability. Methods Raw data of 80 consecutive hypocretin-1 RIAs were used to estimate the intra- and inter-assay coefficient of variation (CV). The LLOQ was established and defined as the lowest converted concentration with a CV <25%; the conversion is performed using a harmonization sample which is internationally used to minimize variation between RIAs. Results The mean intra-assay CV was 4.7%, while the unconverted inter-assay CV was 28.3% (18.5% excluding 2 outliers) and 7.5% when converted to international values. The LLOQ was determined as 27.9 pg/mL. The intra-assay CV of RIAs with lower specific radioactive activity showed a median of 5.6% (n = 41, range 1.6%–17.0%), which was significantly higher than in RIAs with higher specific activity (n = 36; median 3.2%, range 0.4%–11.6%, p = .013). The CV around the 110 pg/mL cutoff was <7%. Conclusions Hypocretin-1 RIAs should always be harmonized using standard reference material. The specific activity of an RIA has a significant impact on its reliability, because of the decay of 125I radioactivity. Values around the hypocretin-1 cut-off can reliably be measured. Hypocretin-1 concentrations below 28 pg/mL should be reported as “undetectable” when measured with the Phoenix Pharmaceuticals RIA. Clinical Trial Information This study is not registered in a clinical trial register, as it has a retrospective database design
Collapse
Affiliation(s)
- Adrienne Elisabeth van der Hoeven
- Department of Neurology, Leiden University Medical Center , Leiden , the Netherlands
- Sleep-Wake Center, Stichting Epilepsie Instellingen Nederland (SEIN) , Heemstede , the Netherlands
| | - Kevin van Waaij
- Department of Neurology, Leiden University Medical Center , Leiden , the Netherlands
| | - Denise Bijlenga
- Department of Neurology, Leiden University Medical Center , Leiden , the Netherlands
- Sleep-Wake Center, Stichting Epilepsie Instellingen Nederland (SEIN) , Heemstede , the Netherlands
| | | | | | - Jaap Adriaan Bakker
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center , Leiden , the Netherlands
| | - Rolf Fronczek
- Department of Neurology, Leiden University Medical Center , Leiden , the Netherlands
- Sleep-Wake Center, Stichting Epilepsie Instellingen Nederland (SEIN) , Heemstede , the Netherlands
| | - Gert Jan Lammers
- Department of Neurology, Leiden University Medical Center , Leiden , the Netherlands
- Sleep-Wake Center, Stichting Epilepsie Instellingen Nederland (SEIN) , Heemstede , the Netherlands
| |
Collapse
|
5
|
Orexin 2 receptor (OX2R) protein distribution measured by autoradiography using radiolabeled OX2R-selective antagonist EMPA in rodent brain and peripheral tissues. Sci Rep 2022; 12:8473. [PMID: 35589803 PMCID: PMC9120030 DOI: 10.1038/s41598-022-12601-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 05/13/2022] [Indexed: 11/18/2022] Open
Abstract
Orexin, a neuropeptide, performs various physiological functions, including the regulation of emotion, feeding, metabolism, respiration, and sleep/wakefulness, by activating the orexin 1 receptor and orexin 2 receptor (OX2R). Owing to the pivotal role of OX2R in wakefulness and other biological functions, OX2R agonists are being developed. A detailed understanding of OX2R protein distribution is essential for determining the mechanisms of action of OX2R agonists; however, this has been hindered by the lack of selective antibodies. In this study, we first confirmed the OX2R-selective binding of [3H]-EMPA in in vitro autoradiography studies, using brain slices from OX2R knockout mice and their wild-type littermates. Subsequently, OX2R protein distribution in rats was comprehensively assessed in 51 brain regions and 10 peripheral tissues using in vitro autoradiography with [3H]-EMPA. The widespread distribution of OX2R protein, including that in previously unrecognized regions of the retrosplenial cortex, was identified. In contrast, OX2R protein expression was negligible/very low in peripheral tissues, suggesting that orexin exerts OX2R-dependent physiological functions primarily through activation of the central nervous system. These findings will be useful for understanding the wide range of biological functions of OX2R and the application of OX2R agonists in various disorders.
Collapse
|
6
|
Sarkanen T, Sved G, Juujärvi M, Alakuijala A, Partinen M. Misdiagnosis of narcolepsy caused by a false positive orexin-A/hypocretin-1 enzyme immune assay. J Clin Sleep Med 2022; 18:2075-2078. [PMID: 35481446 PMCID: PMC9340599 DOI: 10.5664/jcsm.10014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The diagnosis of narcolepsy is based on clinical history, sleep studies, and, in some cases, cerebrospinal fluid orexin-A/hypocretin-1 measurement. The gold standard for orexin measurement is the radioimmune assay (RIA), but other commercial kits are also available, such as the enzyme immune assay (EIA). The specificity of orexin EIA in humans is unknown. We report four cases where orexin levels were measured by EIA and resulted in false positives and the misdiagnosis of narcolepsy. Therefore, orexin EIA measurement should be strongly discouraged in a clinical setting.
Collapse
Affiliation(s)
- Tomi Sarkanen
- Department of Neurology, Tampere University Hospital, Tampere, Finland.,Department of Neurology, Tampere University, Faculty of Medicine and Health Technology, Tampere, Finland
| | - Gabriele Sved
- Helsinki Sleep Clinic, Terveystalo Biobank and Clinical Research, Helsinki, Finland
| | - Maria Juujärvi
- Department of Clinical Chemistry, Fimlab Laboratories Ltd, Tampere, Finland
| | - Anniina Alakuijala
- Department of Clinical Neurophysiology, HUS Medical Imaging Center, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
| | - Markku Partinen
- Helsinki Sleep Clinic, Terveystalo Biobank and Clinical Research, Helsinki, Finland.,Department of Clinical Neurosciences, Clinicum, University of Helsinki, Helsinki, Finland
| |
Collapse
|
7
|
Li S, Zhang R, Hu S, Lai J. Plasma Orexin-A Levels in Patients With Schizophrenia: A Systematic Review and Meta-Analysis. Front Psychiatry 2022; 13:879414. [PMID: 35693955 PMCID: PMC9174516 DOI: 10.3389/fpsyt.2022.879414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 04/29/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Orexins are polypeptides regulating appetite, sleep-wake cycle, and cognition functions, which are commonly disrupted in patients with schizophrenia. Patients with schizophrenia show a decreased connectivity between the prefrontal cortex and midline-anterior thalamus, and orexin can directly activate the axon terminal of cells within the prefrontal cortex and selectively depolarize neurons in the midline intralaminar nuclei of the thalamus. To address the relationship between orexin and schizophrenia, this study performed a meta-analysis on the alteration of plasma orexin-A levels in patients with schizophrenia. METHOD We searched eligible studies in PubMed, Embase, Cochrane, and China National Knowledge Infrastructure (CNKI) from 1998 to September 3, 2021. A total of 8 case-control studies were included in the meta-analyses, providing data on 597 patients with schizophrenia and 370 healthy controls. The Stata version 16.0 software was used to calculate the Hedges's adjusted g with 95% confidence intervals (CI). RESULTS The plasma orexin-A levels were not altered in subjects with schizophrenia (n = 597) when compared to healthy controls (n = 370). Subgroup analyses of gender (male and female vs. only male), country (China vs. other countries), medication (medication vs. non-medication), and the measurement of plasma orexin-A (Enzyme-linked immunosorbent assay vs. radioimmunoassay) revealed heterogeneity ranging from 30.15 to 98.15%, but none showed a significant alteration of plasma orexin-A levels in patients with schizophrenia. Heterogeneity was lower in the other countries and radioimmunoassay subgroup, while other subgroups remained to be highly heterogeneous. No significant evidence of publication bias was found either in Begg's test or the Egger's test. CONCLUSION The present meta-analysis indicated that patients with schizophrenia did not show abnormal plasma levels of orexin-A. SYSTEMATIC REVIEW REGISTRATION https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021283455, identifier: CRD42021283455.
Collapse
Affiliation(s)
- Shaoli Li
- Department of Psychiatry, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Department of Medical Oncology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Ruili Zhang
- Department of Psychiatry, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Shaohua Hu
- Department of Psychiatry, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorders' Management in Zhejiang Province, Hangzhou, China.,Brain Research Institute of Zhejiang University, Hangzhou, China.,Zhejiang Engineering Center for Mathematical Mental Health, Hangzhou, China.,Department of Neurobiology, NHC and CAMS Key Laboratory of Medical Neurobiology, School of Brain Science and Brian Medicine, and MOE Frontier Science Center for Brain Science and Brain-Machine Integration, Zhejiang University School of Medicine, Hangzhou, China
| | - Jianbo Lai
- Department of Psychiatry, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorders' Management in Zhejiang Province, Hangzhou, China.,Brain Research Institute of Zhejiang University, Hangzhou, China.,Zhejiang Engineering Center for Mathematical Mental Health, Hangzhou, China.,Department of Neurobiology, NHC and CAMS Key Laboratory of Medical Neurobiology, School of Brain Science and Brian Medicine, and MOE Frontier Science Center for Brain Science and Brain-Machine Integration, Zhejiang University School of Medicine, Hangzhou, China
| |
Collapse
|
8
|
What do I talk about when I talk about measuring CNS orexin-A? Considerations of orexin-A measurements in clinical and preclinical setting. MEDICINE IN DRUG DISCOVERY 2021. [DOI: 10.1016/j.medidd.2021.100101] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
|
9
|
Chrobok L, Bajkacz S, Klich JD, Lewandowski MH. LC-MS/MS Analysis Elucidates a Daily Rhythm in Orexin A Concentration in the Rat Vitreous Body. Molecules 2021; 26:5036. [PMID: 34443622 PMCID: PMC8401233 DOI: 10.3390/molecules26165036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/11/2021] [Accepted: 08/16/2021] [Indexed: 11/29/2022] Open
Abstract
Orexins are two neuropeptides synthesised mainly in the brain lateral hypothalamic area. The orexinergic system provides arousal-dependent cues for a plethora of brain centres, playing a vital role in feeding behaviour, regulation of the sleep-wake cycle and circadian rhythms. Recently, orexins were found to be produced in the retina of an eye; however, their content in the vitreous body and possible daily pattern of expression have not yet been explored. In this manuscript, we describe the development and validation of a liquid chromatography with tandem mass spectrometry (LC-MS/MS) method designed for quantitative bioanalysis of orexin in the rat vitreous body. Orexin was extracted from vitreous body samples with a water:acetonitrile:formic acid (80:20:0.1; v/v/v) mixture followed by vortexing and centrifuging. Separation was performed on a reverse-phase HPLC column under gradient conditions. Orexin was analysed via multiple-reaction monitoring (MRM) in the positive electrospray mode. The total analysis time for each sample was less than 5.0 min. Once the method was fully optimised, it was then validated, following the 2018 FDA guidance on bioanalytical method validations. The calibration curves for orexin (1-500 ng/mL) were constructed using a linear regression with a 1/x2 weighting. The lower limit of quantitation for orexin was 1.0 pg/mL for the vitreous body. Intra-day and inter-day estimates of accuracy and precision were within 10% of their nominal values, indicating that the method is reliable for quantitation of orexin in the rat vitreous body. From the physiological perspective, our results are the first to show daily rhythm of orexin synthesis by the retina with possible implications on the circadian regulation of vision.
Collapse
Affiliation(s)
- Lukasz Chrobok
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Gronostajowa 9 Street, 30-387 Krakow, Poland; (J.D.K.); (M.H.L.)
| | - Sylwia Bajkacz
- Department of Inorganic Chemistry, Analytical Chemistry and Electrochemistry, Faculty of Chemistry, Silesian University of Technology, Krzywoustego 6 Street, 44-100 Gliwice, Poland
- The Biotechnology Centre, Silesian University of Technology, Krzywoustego 8 Street, 44-100 Gliwice, Poland
| | - Jasmin Daniela Klich
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Gronostajowa 9 Street, 30-387 Krakow, Poland; (J.D.K.); (M.H.L.)
| | - Marian Henryk Lewandowski
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Gronostajowa 9 Street, 30-387 Krakow, Poland; (J.D.K.); (M.H.L.)
| |
Collapse
|
10
|
Cerebrospinal fluid orexin in Alzheimer's disease: a systematic review and meta-analysis. Sleep Med 2021; 85:230-238. [PMID: 34364094 DOI: 10.1016/j.sleep.2021.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 06/13/2021] [Accepted: 07/06/2021] [Indexed: 12/29/2022]
Abstract
OBJECTIVE/BACKGROUND A growing body of evidence suggests that sleep and Alzheimer's disease (AD) have a bi-directional relationship. Emerging research also suggests that orexin, a key neurotransmitter involved in sleep-wake regulation, may be altered in persons with AD, however results have not been consistent across prior studies. This investigation was conducted to both evaluate the aggregate literature to minimize the risk of bias and identify potential factors associated with heterogeneity across studies. METHODS Systematic review identified relevant investigations that compared cerebrospinal fluid orexin in persons with AD and controls. Meta-analysis (random effects model) compared effect size (Hedge's g) for orexin between AD and controls. Meta-regression was additionally performed for key variables of interest to evaluate potential causes of heterogeneity among studies. RESULTS 17 studies were identified that met inclusion/exclusion criteria. Evidence of publication bias was not identified. Non-significant increases in orexin were observed in AD relative to controls, with moderate to large heterogeneity among studies (Hedge's g = 0.20, p = 0.136, I2 = 72.6%). Meta-regression demonstrated both year of publication (β = 0.055, p = 0.020) and effect size for phosphorylated tau in AD versus controls (β = 0.417, p = 0.031) were associated with differences in orexin. CONCLUSIONS Results do not support broad differences in orexin in AD compared to controls, however, evolving diagnostic criteria may have affected findings across studies. Future research that examines orexin in AD over the longitudinal course of the disorder and explores potential links between phosphorylated tau and orexin are indicated.
Collapse
|
11
|
Lindström M, Schinkelshoek M, Tienari PJ, Kukkonen JP, Renkonen R, Fronczek R, Lammers GJ, Itkonen O. Orexin-A measurement in narcolepsy: A stability study and a comparison of LC-MS/MS and immunoassays. Clin Biochem 2021; 90:34-39. [PMID: 33539807 DOI: 10.1016/j.clinbiochem.2021.01.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Orexin-A and -B are neuropeptides involved in sleep-wake regulation. In human narcolepsy type 1, this cycle is disrupted due to loss of orexin-producing neurons in the hypothalamus. Cerebrospinal fluid (CSF) orexin-A measurement is used in the diagnosis of narcolepsy type 1. Currently available immunoassays may lack specificity for accurate orexin quantification. We developed and validated a liquid chromatography mass spectrometry assay (LC-MS/MS) for CSF orexin-A and B. METHODS We used CSF samples from narcolepsy type 1 (n = 22) and type 2 (n = 6) and non-narcoleptic controls (n = 44). Stable isotope-labeled orexin-A and -B internal standards were added to samples before solid-phase extraction and quantification by LC-MS/MS. The samples were also assayed by commercial radioimmunoassay (RIA, n = 42) and enzymatic immunoassay (EIA, n = 72) kits. Stability of orexins in CSF was studied for 12 months. RESULTS Our assay has a good sensitivity (10 pmol/L = 35 pg/mL) and a wide linear range (35-3500 pg/mL). Added orexin-A and -B were stable in CSF for 12 and 3 months, respectively, when frozen. The median orexin-A concentration in CSF from narcolepsy type 1 patients was <35 pg/mL (range < 35-131 pg/mL), which was lower than that in CSF from control individuals (98 pg/mL, range < 35-424 pg/mL). Orexin-A concentrations determined using our LC-MS/MS assay were five times lower than those measured with a commercial RIA. Orexin-B concentrations were undetectable. CONCLUSIONS Orexin-A concentrations measured by our LC-MS/MS assay were lower in narcolepsy type 1 patients as compared to controls. RIA yielded on average higher concentrations than LC-MS/MS.
Collapse
Affiliation(s)
- Mikael Lindström
- HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
| | - Mink Schinkelshoek
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands; Sleep-Wake Centre, Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands
| | - Pentti J Tienari
- HUS Neurocenter, Helsinki University Hospital, Helsinki, Finland; Translational Immunology Research Program, Faculty of Medicine, University of Helsinki, Finland
| | - Jyrki P Kukkonen
- Department of Pharmacology, Institute of Biomedicine, University of Helsinki, Helsinki, Finland
| | - Risto Renkonen
- HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland; Transplantation Laboratory, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Rolf Fronczek
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands; Sleep-Wake Centre, Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands
| | - Gert Jan Lammers
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands; Sleep-Wake Centre, Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands
| | - Outi Itkonen
- HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| |
Collapse
|
12
|
Ravel JM, Mignot EJM. [Narcolepsy: From the discovery of a wake promoting peptide to autoimmune T cell biology and molecular mimicry with flu epitopes]. Biol Aujourdhui 2019; 213:87-108. [PMID: 31829930 DOI: 10.1051/jbio/2019026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Indexed: 11/14/2022]
Abstract
Narcolepsy-cataplexy was first described in the late 19th century in Germany and France. Prevalence was established to be 0.05 % and a canine model was discovered in the 1970s. In 1983, a Japanese study found that all patients carried HLA-DR2, suggesting autoimmunity as the cause of the disease. Studies in the canine model established that dopaminergic stimulation underlies anti-narcoleptic action of psychostimulants, while antidepressants were found to suppress cataplexy through adrenergic reuptake inhibition. No HLA association was found in canines. A linkage study initiated in 1988 revealed in hypocretin (orexin) receptor two mutations as the cause of canine narcolepsy in 1999. In 1992, studies on African Americans showed that DQ0602 was a better marker than DR2 across all ethnic groups. In 2000, hypocretin-1/orexin A levels were measured in the cerebrospinal fluid (CSF) and found to be undetectable in most patients, establishing hypocretin deficiency as the cause of narcolepsy. Decreased CSF hypocretin-1 was then found to be secondary to the loss of the 70,000 neurons producing hypocretin in the hypothalamus, suggesting immune destruction of these cells as the cause of the disease. Additional genetic studies, notably genome wide associations (GWAS), found multiple genetic predisposing factors for narcolepsy. These were almost all involved in other autoimmune diseases, although a strong and unique association with T cell receptor (TCR) alpha and beta loci were observed. Nonetheless, all attempts to demonstrate presence of autoantibodies against hypocretin cells in narcolepsy failed, and the presumed autoimmune cause remained unproven. In 2009, association with strep throat infections were found, and narcolepsy onsets were found to occur more frequently in spring and summer, suggesting upper away infections as triggers. Following reports that narcolepsy cases were triggered by vaccinations and infections against influenza A 2009 pH1N1, a new pandemic strain that erupted in 2009, molecular mimicry with influenza A virus was suggested in 2010. This hypothesis was later confirmed by peptide screening showing higher activity of CD4+ T cell reactivity to a specific post-translationally amidated segment of hypocretin (HCRT-NH2) and cross-reactivity of specific TCRs with a pH1N1-specific segment of hemagglutinin that shares homology with HCRT-NH2. Strikingly, the most frequent TCR recognizing these antigens was found to carry sequences containing TRAJ24 or TRVB4-2, segments modulated by narcolepsy-associated genetic polymorphisms. Cross-reactive CD4+ T cells with these cross-reactive TCRs likely subsequently recruit CD8+ T cells that are then involved in hypocretin cell destruction. Additional flu mimics are also likely to be discovered since narcolepsy existed prior to 2009. The work that has been conducted over the years on narcolepsy offers a unique perspective on the conduct of research on the etiopathogeny of a specific disease.
Collapse
Affiliation(s)
- Jean-Marie Ravel
- Stanford Center for Sleep Sciences and Medicine, Department of Psychiatry and Behavioral Medicine, Stanford University, 3615 Porter Drive, Palo Alto, CA, USA
| | - Emmanuel J M Mignot
- Stanford Center for Sleep Sciences and Medicine, Department of Psychiatry and Behavioral Medicine, Stanford University, 3615 Porter Drive, Palo Alto, CA, USA
| |
Collapse
|