51
|
Mizuno H, Kihara Y. Druggable Lipid GPCRs: Past, Present, and Prospects. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1274:223-258. [PMID: 32894513 DOI: 10.1007/978-3-030-50621-6_10] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
G protein-coupled receptors (GPCRs) have seven transmembrane spanning domains and comprise the largest superfamily with ~800 receptors in humans. GPCRs are attractive targets for drug discovery because they transduce intracellular signaling in response to endogenous ligands via heterotrimeric G proteins or arrestins, resulting in a wide variety of physiological and pathophysiological responses. The endogenous ligands for GPCRs are highly chemically diverse and include ions, biogenic amines, nucleotides, peptides, and lipids. In this review, we follow the KonMari method to better understand druggable lipid GPCRs. First, we have a comprehensive tidying up of lipid GPCRs including receptors for prostanoids, leukotrienes, specialized pro-resolving mediators (SPMs), lysophospholipids, sphingosine 1-phosphate (S1P), cannabinoids, platelet-activating factor (PAF), free fatty acids (FFAs), and sterols. This tidying up consolidates 46 lipid GPCRs and declutters several perplexing lipid GPCRs. Then, we further tidy up the lipid GPCR-directed drugs from the literature and databases, which identified 24 clinical drugs targeting 16 unique lipid GPCRs available in the market and 44 drugs under evaluation in more than 100 clinical trials as of 2019. Finally, we introduce drug designs for GPCRs that spark joy, such as positive or negative allosteric modulators (PAM or NAM), biased agonism, functional antagonism like fingolimod, and monoclonal antibodies (MAbs). These strategic drug designs may increase the efficacy and specificity of drugs and reduce side effects. Technological advances will help to discover more endogenous lipid ligands from the vast number of remaining orphan GPCRs and will also lead to the development novel lipid GPCR drugs to treat various diseases.
Collapse
Affiliation(s)
| | - Yasuyuki Kihara
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
| |
Collapse
|
52
|
Sanjel B, Shim WS. Recent advances in understanding the molecular mechanisms of cholestatic pruritus: A review. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165958. [PMID: 32896605 DOI: 10.1016/j.bbadis.2020.165958] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 08/21/2020] [Accepted: 09/01/2020] [Indexed: 02/06/2023]
Abstract
Cholestasis, a condition characterized by an abnormal decrease in bile flow, is accompanied by various symptoms such as pruritus. Although cholestatic pruritus is a prominent condition, its precise mechanisms have largely been elusive. Recently, advancements have been made for understanding the etiology and pathogenesis of cholestatic pruritus. The current review therefore focuses on summarizing the overall progress made in the elucidation of its molecular mechanisms. We have reviewed the available animal models on cholestasis to compare the differences between them, characterized potential pruritogens involved in cholestatic pruritus, and have summarized the receptor and ion channels implicated in the condition. Finally, we have discussed the available treatment options for alleviation of cholestatic pruritus. As our understanding of the mechanisms of cholestatic pruritus deepens, novel strategies to cure this condition are awaited.
Collapse
Affiliation(s)
- Babina Sanjel
- College of Pharmacy, Gachon University, Hambakmoero 191, Yeonsu-gu, Incheon 21936, Republic of Korea; Gachon Institute of Pharmaceutical Sciences, Hambakmoero 191, Yeonsu-gu, Incheon 21936, Republic of Korea
| | - Won-Sik Shim
- College of Pharmacy, Gachon University, Hambakmoero 191, Yeonsu-gu, Incheon 21936, Republic of Korea; Gachon Institute of Pharmaceutical Sciences, Hambakmoero 191, Yeonsu-gu, Incheon 21936, Republic of Korea.
| |
Collapse
|
53
|
Chen YL, He ZG, Wang Q, Xiang HB, Fan L, Xiong J. Specific Patterns of Spinal Metabolite Ratio Underlying α-Me-5-HT-evoked Pruritus Compared with Compound 48/80 Based on Proton Nuclear Magnetic Resonance Spectroscopy. Curr Med Sci 2020; 40:761-766. [PMID: 32862388 DOI: 10.1007/s11596-020-2233-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 06/12/2020] [Indexed: 01/03/2023]
Abstract
Mechanisms of pruritus are implicated in the dysregulation of the metabolites in the spinal cord. We investigated pruritus behavioral testing in three groups of young adult male C57Bl/6 mice, including one group treated with normal saline, while the other groups intradermally injected with α-Me-5-HT (histamine-independent pruritogen), compound 48/80 (histamine-dependent pruritogen) at the nape skin of the neck, respectively. Proton nuclear magnetic resonance spectroscopy (MRS) was used to compare spinal metabolites from the vertebral cervical among three groups, and to study the association of spinal metabolite ratio and pruritus intensity. The MRS-measured N-acetylaspartate-to-myoinositol ratio (NAA/Ins) was significantly correlated with the number of scratches between normal saline group and 48/80 group or α-Me-5-HT group (both P<0.0001), indicating that NAA/Ins may be a robust surrogate marker of histamine-independent/dependent pruritogen. There was significant difference in Glu/Ins between normal saline group and 48/80 group (P=0.017), indicating that Glu/Ins may be a surrogate marker of histamine-dependent pruritogen, while GABA/Ins was highly significantly different between normal saline group and α-Me-5-HT group (P=0.008), suggesting that GABA/Ins may be a surrogate marker of histamine-independent pruritogen. MRS may reflect the extent of pruritus intensity elicited by α-Me-5-HT and compound 48/80 with sensitivity similar to the number of scratches, and above potential markers need to be further validated in pre-clinical and clinical treatment trials.
Collapse
Affiliation(s)
- Ying-le Chen
- Department of Anesthesiology, the First Affiliated Quanzhou Hospital of Fujian Medical University, Quanzhou, 362000, China
| | - Zhi-Gang He
- Emergency Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Qian Wang
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Hong-Bing Xiang
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Li Fan
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| | - Jun Xiong
- Hepatobiliary Surgery Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| |
Collapse
|
54
|
Zaccor NW, Sumner CJ, Snyder SH. The nonselective cation channel TRPV4 inhibits angiotensin II receptors. J Biol Chem 2020; 295:9986-9997. [PMID: 32493776 PMCID: PMC7380189 DOI: 10.1074/jbc.ra120.014325] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 06/01/2020] [Indexed: 12/14/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) are a ubiquitously expressed family of receptor proteins that regulate many physiological functions and other proteins. They act through two dissociable signaling pathways: the exchange of GDP to GTP by linked G-proteins and the recruitment of β-arrestins. GPCRs modulate several members of the transient receptor potential (TRP) channel family of nonselective cation channels. How TRP channels reciprocally regulate GPCR signaling is less well-explored. Here, using an array of biochemical approaches, including immunoprecipitation and fluorescence, calcium imaging, phosphate radiolabeling, and a β-arrestin-dependent luciferase assay, we characterize a GPCR-TRP channel pair, angiotensin II receptor type 1 (AT1R), and transient receptor potential vanilloid 4 (TRPV4), in primary murine choroid plexus epithelial cells and immortalized cell lines. We found that AT1R and TRPV4 are binding partners and that activation of AT1R by angiotensin II (ANGII) elicits β-arrestin-dependent inhibition and internalization of TRPV4. Activating TRPV4 with endogenous and synthetic agonists inhibited angiotensin II-mediated G-protein-associated second messenger accumulation, AT1R receptor phosphorylation, and β-arrestin recruitment. We also noted that TRPV4 inhibits AT1R phosphorylation by activating the calcium-activated phosphatase calcineurin in a Ca2+/calmodulin-dependent manner, preventing β-arrestin recruitment and receptor internalization. These findings suggest that when TRP channels and GPCRs are co-expressed in the same tissues, many of these channels can inhibit GPCR desensitization.
Collapse
Affiliation(s)
- Nicholas W Zaccor
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Charlotte J Sumner
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Solomon H Snyder
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| |
Collapse
|
55
|
Abstract
Itch is a unique sensation that helps organisms scratch away external threats; scratching itself induces an immune response that can contribute to more itchiness. Itch is induced chemically in the peripheral nervous system via a wide array of receptors. Given the superficial localization of itch neuron terminals, cells that dwell close to the skin contribute significantly to itch. Certain mechanical stimuli mediated by recently discovered circuits also contribute to the itch sensation. Ultimately, in the spinal cord, and likely in the brain, circuits that mediate touch, pain, and itch engage in cross modulation. Much of itch perception is still a mystery, but we present in this review the known ligands and receptors associated with itch. We also describe experiments and findings from investigations into the spinal and supraspinal circuitry responsible for the sensation of itch.
Collapse
Affiliation(s)
- Mark Lay
- The Solomon H. Snyder Department of Neuroscience and the Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA;,
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience and the Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA;,
- Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| |
Collapse
|
56
|
Zhu Y, Xu S, Lu Y, Wei Y, Yao B, Guo F, Zheng X, Wang Y, He Y, Jin L, Li Y. Repositioning an Immunomodulatory Drug Vidofludimus as a Farnesoid X Receptor Modulator With Therapeutic Effects on NAFLD. Front Pharmacol 2020; 11:590. [PMID: 32477115 PMCID: PMC7240069 DOI: 10.3389/fphar.2020.00590] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 04/16/2020] [Indexed: 12/12/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disorder, and yet with no pharmacological treatment approved worldwide. The repositioning of old drugs provides a safe approach for drug development. Vidofludimus, an inhibitor for dihydroorotate dehydrogenase (DHODH) for the treatment of autoimmune disorders, is herein uncovered as a novel modulator for farnesoid X receptor (FXR) by biochemical and crystallographic analysis. We further revealed that vidofludimus exerts in vivo therapeutic effects on dextran sodium sulfate (DSS)-induced colitis in an FXR-dependent manner. Notably, vidofludimus also possesses remarkable beneficial effects in reducing NAFLD by targeting FXR, which may represent a unique approach in developing the treatment for NAFLD. Our findings not only reveal a promising template for the design of novel FXR ligands in treating autoimmune disorders, but also uncover a novel therapeutic effect for vidofludimus on NAFLD based on the newly established relationships among drugs, targets, and diseases.
Collapse
Affiliation(s)
- Yanlin Zhu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen, China
| | - Shuangshuang Xu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen, China
| | - Yi Lu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen, China.,Xiamen Key Laboratory of Neonatal Diseases, Xiamen Children's Hospital, Xiamen, China
| | - Yijuan Wei
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen, China
| | - Benqiang Yao
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen, China
| | - Fusheng Guo
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen, China
| | - Xing Zheng
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen, China
| | - Yumeng Wang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen, China
| | - Ying He
- Laboratory Animal Center, Xiamen University, Xiamen, China
| | - Lihua Jin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen, China.,Department of Diabetes Complications and Metabolism, Diabetes and Metabolism Research Institute, Beckman Research Institute, City of Hope National Medical Center, Duarte, USA
| | - Yong Li
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen, China
| |
Collapse
|
57
|
Gordon DM, Neifer KL, Hamoud ARA, Hawk CF, Nestor-Kalinoski AL, Miruzzi SA, Morran MP, Adeosun SO, Sarver JG, Erhardt PW, McCullumsmith RE, Stec DE, Hinds TD. Bilirubin remodels murine white adipose tissue by reshaping mitochondrial activity and the coregulator profile of peroxisome proliferator-activated receptor α. J Biol Chem 2020; 295:9804-9822. [PMID: 32404366 DOI: 10.1074/jbc.ra120.013700] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/11/2020] [Indexed: 12/18/2022] Open
Abstract
Activation of lipid-burning pathways in the fat-storing white adipose tissue (WAT) is a promising strategy to improve metabolic health and reduce obesity, insulin resistance, and type II diabetes. For unknown reasons, bilirubin levels are negatively associated with obesity and diabetes. Here, using mice and an array of approaches, including MRI to assess body composition, biochemical assays to measure bilirubin and fatty acids, MitoTracker-based mitochondrial analysis, immunofluorescence, and high-throughput coregulator analysis, we show that bilirubin functions as a molecular switch for the nuclear receptor transcription factor peroxisome proliferator-activated receptor α (PPARα). Bilirubin exerted its effects by recruiting and dissociating specific coregulators in WAT, driving the expression of PPARα target genes such as uncoupling protein 1 (Ucp1) and adrenoreceptor β 3 (Adrb3). We also found that bilirubin is a selective ligand for PPARα and does not affect the activities of the related proteins PPARγ and PPARδ. We further found that diet-induced obese mice with mild hyperbilirubinemia have reduced WAT size and an increased number of mitochondria, associated with a restructuring of PPARα-binding coregulators. We conclude that bilirubin strongly affects organismal body weight by reshaping the PPARα coregulator profile, remodeling WAT to improve metabolic function, and reducing fat accumulation.
Collapse
Affiliation(s)
- Darren M Gordon
- Department of Neurosciences, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA.,Center for Diabetes and Endocrine Research (CeDER), University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Kari L Neifer
- Department of Neurosciences, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Abdul-Rizaq Ali Hamoud
- Department of Neurosciences, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Charles F Hawk
- Department of Neurosciences, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Andrea L Nestor-Kalinoski
- Advanced Microscopy and Imaging Center, Department of Surgery, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Scott A Miruzzi
- Department of Neurosciences, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Michael P Morran
- Advanced Microscopy and Imaging Center, Department of Surgery, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Samuel O Adeosun
- Department of Physiology and Biophysics, Cardiorenal and Metabolic Diseases Research Center, University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - Jeffrey G Sarver
- Center for Drug Design and Development (CD3), Department of Pharmacology and Experimental Therapeutics, University of Toledo College of Pharmacy and Pharmaceutical Sciences, Toledo, Ohio, USA
| | - Paul W Erhardt
- Center for Drug Design and Development (CD3), Department of Medicinal and Biological Chemistry, University of Toledo College of Pharmacy and Pharmaceutical Sciences, Toledo, Ohio, USA
| | - Robert E McCullumsmith
- Department of Neurosciences, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA.,ProMedica, Toledo, Ohio, USA
| | - David E Stec
- Department of Physiology and Biophysics, Cardiorenal and Metabolic Diseases Research Center, University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - Terry D Hinds
- Department of Neurosciences, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA .,Center for Diabetes and Endocrine Research (CeDER), University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| |
Collapse
|
58
|
Abstract
Abstract
Purpose of Review
Chronic pruritus represents a burdensome symptom in cholestatic liver disease. This review recommends a stepwise therapeutic approach, alongside with providing information on epidemiology, pathophysiology, and novel drug targets.
Recent Findings
Current epidemiological data emphasize chronic itch as a major symptom in immune-mediated liver diseases such as primary biliary cholangitis affecting up to 70% of patients with a significant number suffering from long-lasting and severe pruritus. κ-opioid receptor (KOR) agonists, PPAR agonists, and ileal bile acid transporter (IBAT) inhibitors are currently investigated for their anti-pruritic efficacy in clinical trials. Future therapies may target the autotaxin-lysophosphatidic acid-axis or the Mas-related GPCR MRGPRX4.
Summary
Cholestatic pruritus still remains a challenging symptom for patients and physicians. Using a stepwise approach including cholestyramine, rifampicin, bezafibrate, naltrexone, and sertraline, pruritus is often adequately manageable. KOR agonists and IBAT inhibitors are currently the most promising anti-pruritic drugs for cholestatic pruritus in development.
Collapse
|
59
|
Xing Y, Chen J, Hilley H, Steele H, Yang J, Han L. Molecular Signature of Pruriceptive MrgprA3 + Neurons. J Invest Dermatol 2020; 140:2041-2050. [PMID: 32234460 DOI: 10.1016/j.jid.2020.03.935] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 03/12/2020] [Accepted: 03/13/2020] [Indexed: 02/07/2023]
Abstract
Itch, initiated by the activation of sensory neurons, is associated frequently with dermatological diseases. MrgprA3+ sensory neurons have been identified as one of the major itch-sensing neuronal populations. Mounting evidence has demonstrated that peripheral pathological conditions induce physiological regulation of sensory neurons, which is critical for the maintenance of chronic itch sensation. However, the underlying molecular mechanisms are not clear. Here, we performed RNA sequencing of genetically labeled MrgprA3+ neurons under both naïve and allergic contact dermatitis conditions. Our results revealed the unique molecular signature of itch-sensing neurons and the distinct transcriptional profile changes that result in response to dermatitis. We found enrichment of nine Mrgpr family members and two histamine receptors in MrgprA3+ neurons, suggesting that MrgprA3+ neurons are a direct neuronal target for histamine and Mrgpr agonists. In addition, PTPN6 and PCDH12 were identified as highly selective markers of MrgprA3+ neurons. We also discovered that MrgprA3+ neurons respond to skin dermatitis in a way that is unique from other sensory neurons by regulating a combination of transcriptional factors, ion channels, and key molecules involved in synaptic transmission. These results significantly increase our knowledge of itch transmission and uncover potential targets for combating itch.
Collapse
Affiliation(s)
- Yanyan Xing
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Junyu Chen
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Henry Hilley
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Haley Steele
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Jingjing Yang
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Liang Han
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA.
| |
Collapse
|
60
|
Vítek L. Bilirubin as a signaling molecule. Med Res Rev 2020; 40:1335-1351. [PMID: 32017160 DOI: 10.1002/med.21660] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/12/2019] [Accepted: 01/24/2020] [Indexed: 12/24/2022]
Abstract
For long time bilirubin was only considered as a potentially dangerous sign of liver diseases, but it now appears clear that it is also a powerful signaling molecule. Together with potent antioxidant activities that were only reported in the last few decades, many other biological effects have now been clearly described. These include especially profound inhibitory effects on almost all effectors of the immune system, with their clinical consequences in the bilirubin-mediated protection against autoimmune and inflammatory diseases. Separate from these, bilirubin activates various nuclear and cytoplasmic receptors, resembling the endocrine activities of actual hormonal substances. This is true for the "classical" hepatic nuclear receptors, including the aryl hydrocarbon receptor, or the constitutive androstane receptor; and also for some lesser-explored receptors such as peroxisome proliferator-activated receptors α and γ; Mas-related G protein-coupled receptor; or other signaling molecules including fatty acid binding protein 1, apolipoprotein D, or reactive oxygen species. All of these targets have broad metabolic effects, which in turn may offer protection against obesity, diabetes mellitus, and other metabolic diseases. The (mostly experimental) data are also supported by clinical evidence. In fact, data from the last three decades have convincingly demonstrated the protective effects of mildly elevated serum bilirubin concentrations against various "diseases of civilization." Additionally, even tiny, micromolar changes of serum bilirubin concentrations have been associated with substantial alteration in the risks of these diseases. It is highly likely that all of the biological activities of bilirubin have yet to be exhaustively explored, and thus we can expect further clinical discoveries about this evolutionarily old molecule into the future.
Collapse
Affiliation(s)
- Libor Vítek
- 4th Department of Internal Medicine and Institute of Medical Biochemistry and Laboratory Diagnostics, General Faculty Hospital and 1st Faculty of Medicine, Charles University, Prague, Czech Republic
| |
Collapse
|
61
|
Abstract
Itch is a topic to which everyone can relate. The physiological roles of itch are increasingly understood and appreciated. The pathophysiological consequences of itch impact quality of life as much as pain. These dynamics have led to increasingly deep dives into the mechanisms that underlie and contribute to the sensation of itch. When the prior review on the physiology of itching was published in this journal in 1941, itch was a black box of interest to a small number of neuroscientists and dermatologists. Itch is now appreciated as a complex and colorful Rubik's cube. Acute and chronic itch are being carefully scratched apart and reassembled by puzzle solvers across the biomedical spectrum. New mediators are being identified. Mechanisms blur boundaries of the circuitry that blend neuroscience and immunology. Measures involve psychophysics and behavioral psychology. The efforts associated with these approaches are positively impacting the care of itchy patients. There is now the potential to markedly alleviate chronic itch, a condition that does not end life, but often ruins it. We review the itch field and provide a current understanding of the pathophysiology of itch. Itch is a disease, not only a symptom of disease.
Collapse
Affiliation(s)
- Ferda Cevikbas
- Dermira, Inc., Menlo Park, California; and Harvard Medical School and the Cutaneous Biology Research Center at Massachusetts General Hospital, Charlestown, Massachusetts
| | - Ethan A Lerner
- Dermira, Inc., Menlo Park, California; and Harvard Medical School and the Cutaneous Biology Research Center at Massachusetts General Hospital, Charlestown, Massachusetts
| |
Collapse
|
62
|
Hinds TD, Stec DE. Bilirubin Safeguards Cardiorenal and Metabolic Diseases: a Protective Role in Health. Curr Hypertens Rep 2019; 21:87. [PMID: 31599366 DOI: 10.1007/s11906-019-0994-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE OF REVIEW To discuss recent advances indicating that bilirubin safeguards against cardiorenal and metabolic diseases. RECENT FINDINGS Several investigations from human patient populations and experimental animal models have shown that bilirubin improves cardiorenal and metabolic dysfunction. The latest studies found an entirely new function of bilirubin suggesting that it acts as a hormone signaling molecule capable of activating nuclear receptors for burning fat, which may explain several of its protective actions. This review highlights the current findings (within the last 3 years) regarding cardiorenal and metabolic protective effects of bilirubin and the latest mechanism(s) that may be mediating these effects.
Collapse
Affiliation(s)
- Terry D Hinds
- Department of Physiology and Pharmacology, University of Toledo College of Medicine, Toledo, OH, 43614, USA
| | - David E Stec
- Department of Physiology & Biophysics, Mississippi Center for Obesity Research, University of Mississippi Medical Center, 2500 North State St, Jackson, MS, 39216, USA.
| |
Collapse
|
63
|
Yu H, Zhao T, Liu S, Wu Q, Johnson O, Wu Z, Zhuang Z, Shi Y, Peng L, He R, Yang Y, Sun J, Wang X, Xu H, Zeng Z, Zou P, Lei X, Luo W, Li Y. MRGPRX4 is a bile acid receptor for human cholestatic itch. eLife 2019; 8:48431. [PMID: 31500698 PMCID: PMC6773440 DOI: 10.7554/elife.48431] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 09/02/2019] [Indexed: 02/06/2023] Open
Abstract
Patients with liver diseases often suffer from chronic itch, yet the pruritogen(s) and receptor(s) remain largely elusive. Here, we identify bile acids as natural ligands for MRGPRX4. MRGPRX4 is expressed in human dorsal root ganglion (hDRG) neurons and co-expresses with itch receptor HRH1. Bile acids elicited Ca2+ responses in cultured hDRG neurons, and bile acids or a MRGPRX4 specific agonist induced itch in human subjects. However, a specific agonist for another bile acid receptor TGR5 failed to induce itch in human subjects and we find that human TGR5 is not expressed in hDRG neurons. Finally, we show positive correlation between cholestatic itch and plasma bile acids level in itchy patients and the elevated bile acids is sufficient to activate MRGPRX4. Taken together, our data strongly suggest that MRGPRX4 is a novel bile acid receptor that likely underlies cholestatic itch in human, providing a promising new drug target for anti-itch therapies.
Collapse
Affiliation(s)
- Huasheng Yu
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Beijing, China
| | - Tianjun Zhao
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Beijing, China
| | - Simin Liu
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
| | - Qinxue Wu
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Omar Johnson
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Zhaofa Wu
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Zihao Zhuang
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
| | - Yaocheng Shi
- Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Luxin Peng
- Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Renxi He
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Yong Yang
- Department of Dermatology, Beijing Key Laboratory of Molecular Diagnosis on Dermatoses, Peking University First Hospital, Peking University, Beijing, China
| | - Jianjun Sun
- Department of Neurosurgery, Peking University Third Hospital, Peking University, Beijing, China
| | - Xiaoqun Wang
- State Key Laboratory of Brain and Cognitive Science, CAS Center for Excellence in Brain Science and Intelligence Technology (Shanghai), Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Haifeng Xu
- Department of Liver Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - Zheng Zeng
- Department of Infectious Diseases, Peking University First Hospital, Beijing, China
| | - Peng Zou
- Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Xiaoguang Lei
- Peking-Tsinghua Center for Life Sciences, Beijing, China.,Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Wenqin Luo
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Beijing, China.,Chinese Institute for Brain Research, Beijing, China
| |
Collapse
|
64
|
Kremer AE. What are new treatment concepts in systemic itch? Exp Dermatol 2019; 28:1485-1492. [DOI: 10.1111/exd.14024] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 08/02/2019] [Accepted: 08/23/2019] [Indexed: 12/20/2022]
Affiliation(s)
- Andreas E. Kremer
- Department of Medicine 1 & Translational Research Center Friedrich‐Alexander‐University Erlangen‐Nürnberg Erlangen Germany
| |
Collapse
|
65
|
Hashimoto T, Yosipovitch G. Itching as a systemic disease. J Allergy Clin Immunol 2019; 144:375-380. [DOI: 10.1016/j.jaci.2019.04.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 04/03/2019] [Accepted: 04/09/2019] [Indexed: 12/12/2022]
|
66
|
Abstract
PURPOSE OF REVIEW Pruritus is a common extrahepatic symptom in various liver disorders, in particularly those with cholestatic features. This review summarizes epidemiology, pathophysiology, evidence-based therapeutic recommendations and currently investigated drugs for pruritus in hepatobiliary disorders. RECENT FINDINGS Recent epidemiological data suggest pruritus as a common and relevant symptom in immune-mediated liver diseases, i.e., primary biliary cholangitis (PBC) with over 70% affected patients, up to 56% suffering from chronic pruritus. The better pathophysiological understanding of hepatic pruritus has led to the identification of novel therapeutic targets, addressed in drug trials using KOR agonists, PPAR agonists, and ileal bile acid transporter inhibitors. Hepatic itch remains among the most agonizing symptoms for affected patients and a clinical challenge for physicians. Therapeutic recommendations include a guideline-based stepwise approach starting with cholestyramine, followed by rifampicin, naltrexone, and sertraline. Bezafibrate and ileal bile acid transporter inhibitors represent promising future anti-pruritic treatment options.
Collapse
Affiliation(s)
- Miriam M Düll
- Department of Medicine 1, Gastroenterology, Hepatology, Pneumology and Endocrinology, Friedrich-Alexander-University Erlangen-Nürnberg, Ulmenweg 18, D-91054, Erlangen, Germany
| | - Andreas E Kremer
- Department of Medicine 1, Gastroenterology, Hepatology, Pneumology and Endocrinology, Friedrich-Alexander-University Erlangen-Nürnberg, Ulmenweg 18, D-91054, Erlangen, Germany.
| |
Collapse
|
67
|
BAM8-22 and its receptor MRGPRX1 may attribute to cholestatic pruritus. Sci Rep 2019; 9:10888. [PMID: 31350433 PMCID: PMC6659683 DOI: 10.1038/s41598-019-47267-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 07/11/2019] [Indexed: 12/16/2022] Open
Abstract
Pruritus is an unexpected symptom observed in cholestasis and its mechanism is still unclear. Here, we show that bovine adrenal medulla (BAM) 8-22, an endogenous itch-inducing peptide, could be involved in cholestatic pruritus. It was found that bile duct ligation (BDL) mice, an obstructive cholestasis model, showed increased spontaneous scratching behaviour. Importantly, the mRNA level of proenkephalin, a precursor polypeptide of BAM8-22, was significantly increased in the skin of BDL mice. Furthermore, the mRNA level of Mrgprx1, which encodes a receptor for BAM8-22, was significantly increased in the dorsal root ganglia (DRG) of BDL mice. This was further confirmed by elevation of intracellular calcium levels upon BAM8-22 treatment in primarily-cultured DRG neurons. In addition, BDL mice showed augmented scratching behaviour by BAM8-22, indicating enhanced activity of MRGPRX1. Moreover, the skin homogenate of BDL mice induced elevation of intracellular calcium levels through MRGPRX1. Finally, among the various bile acids, chenodeoxycholic acid significantly increased proenkephalin transcription in a human keratinocyte cell line (HaCaT). In conclusion, cholestatic pruritus could be attributed in part to enhanced action of both BAM8-22 in the skin and its receptor MRGPRX1 in sensory neurons.
Collapse
|
68
|
Molecular pharmacology of metabotropic receptors targeted by neuropsychiatric drugs. Nat Struct Mol Biol 2019; 26:535-544. [PMID: 31270468 DOI: 10.1038/s41594-019-0252-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 05/15/2019] [Indexed: 12/30/2022]
Abstract
Metabotropic receptors are responsible for so-called 'slow synaptic transmission' and mediate the effects of hundreds of peptide and non-peptide neurotransmitters and neuromodulators. Over the past decade or so, a revolution in membrane-protein structural determination has clarified the molecular determinants responsible for the actions of these receptors. This Review focuses on the G protein-coupled receptors (GPCRs) that are targets of neuropsychiatric drugs and shows how insights into the structure and function of these important synaptic proteins are accelerating understanding of their actions. Notably, elucidating the structure and function of GPCRs should enhance the structure-guided discovery of novel chemical tools with which to manipulate and understand these synaptic proteins.
Collapse
|
69
|
Meixiong J, Vasavda C, Snyder SH, Dong X. MRGPRX4 is a G protein-coupled receptor activated by bile acids that may contribute to cholestatic pruritus. Proc Natl Acad Sci U S A 2019; 116:10525-10530. [PMID: 31068464 PMCID: PMC6535009 DOI: 10.1073/pnas.1903316116] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Patients suffering from cholestasis, the slowing or stoppage of bile flow, commonly report experiencing an intense, chronic itch. Numerous pruritogens are up-regulated in cholestatic patient sera, including bile acids (BAs). Acute injection of BAs results in itch in both mice and humans, and BA-modulating therapy is effective in controlling patient itch. Here, we present evidence that human sensory neuron-expressed Mas-related G protein-coupled receptor X4 (MRGPRX4), an orphan member of the Mrgpr family of GPCRs, is a BA receptor. Using Ca2+ imaging, we determined that pathophysiologically relevant levels of numerous BAs activated MRGPRX4. No mouse Mrgpr orthologs were activated by BAs. To assess the in vivo relevance of BA activation of MRGPRX4, we generated a humanized mouse with targeted expression of MRGPRX4 in itch-encoding sensory neurons. BAs activated MRGPRX4+ sensory neurons at higher levels compared with WT neurons. Compared with control animals, MRGPRX4+ mice scratched more upon acute injection of BAs and in a model of cholestatic itch. Overall, these data suggest that targeting MRGPRX4 is a promising strategy for alleviating cholestatic itch.
Collapse
Affiliation(s)
- James Meixiong
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Chirag Vasavda
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Solomon H Snyder
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205;
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Department of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Xinzhong Dong
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205;
- Department of Dermatology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| |
Collapse
|
70
|
Patel SP, Vasavda C, Ho B, Meixiong J, Dong X, Kwatra SG. Cholestatic pruritus: Emerging mechanisms and therapeutics. J Am Acad Dermatol 2019; 81:1371-1378. [PMID: 31009666 DOI: 10.1016/j.jaad.2019.04.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 04/08/2019] [Accepted: 04/13/2019] [Indexed: 01/01/2023]
Abstract
Patients suffering from cholestasis often report experiencing a debilitating, unrelenting itch. In contrast to conditions, such as urticaria, in which histamine primarily drives itch (pruritus), cholestatic pruritus is multifactorial and more difficult to treat. Existing therapies are not always effective and have undesirable adverse effect profiles. Here, we conducted a systematic literature review to evaluate conventional treatment strategy, current pathophysiologic understanding, and the role of new therapies in the context of cholestatic pruritus. We discuss novel findings implicating bile acids, lysophosphatidic acid, and bilirubin as potential important mediators of cholestatic itch. New therapies that aim to remove or modulate pruritogens have been supported in observational cohort studies and randomized controlled trials. Although these new therapies show promise, further research is needed to confirm the pathophysiology of cholestatic pruritus so that targeted therapy can be developed.
Collapse
Affiliation(s)
- Sagar P Patel
- Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Chirag Vasavda
- The Solomon H Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Byron Ho
- Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - James Meixiong
- The Solomon H Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Xinzhong Dong
- Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland; The Solomon H Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland; Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Shawn G Kwatra
- Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
| |
Collapse
|