51
|
O'Mullane LM, Cook DI, Dinudom A. Purinergic regulation of the epithelial Na+ channel. Clin Exp Pharmacol Physiol 2009; 36:1016-22. [PMID: 19566815 DOI: 10.1111/j.1440-1681.2009.05256.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
1. The epithelial Na(+) channel (ENaC) is a major conductive pathway that transports Na(+) across the apical membrane of the distal nephron, the respiratory tract, the distal colon and the ducts of exocrine glands. The ENaC is regulated by hormonal and humoral factors, including extracellular nucleotides that are available from the epithelial cells themselves. 2. Extracellular nucleotides, via the P2Y2 receptors (P2Y2Rs) at the basolateral and apical membrane of the epithelia, trigger signalling systems that inhibit the activity of the ENaC and activate Ca(2+) -dependent Cl(-) secretion. 3. Recent data from our laboratory suggest that stimulation of the P2Y2Rs at the basolateral membrane inhibits ENaC activity by a signalling mechanism that involves G beta gamma subunits freed from a pertussis toxin (PTX)-sensitive G-protein and phospholipase C (PLC) beta 4. A similar signalling mechanism is also partially responsible for inhibition of the ENaC during activation of apical P2Y2Rs. 4. Stimulation of apical P2Y2Rs also activates an additional signalling mechanism that inhibits the ENaC and involves the activated Galpha subunit of a PTX-insensitive G-protein and activation of an unidentified PLC. The effect of this PTX-insensitive system requires the activity of the basolateral Na(+)/K(+)/2Cl(-) cotransporter.
Collapse
Affiliation(s)
- Lauren M O'Mullane
- Discipline of Physiology, The Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, New South Wales, Australia
| | | | | |
Collapse
|
52
|
Borrmann T, Hinz S, Bertarelli DCG, Li W, Florin NC, Scheiff AB, Müller CE. 1-Alkyl-8-(piperazine-1-sulfonyl)phenylxanthines: Development and Characterization of Adenosine A2B Receptor Antagonists and a New Radioligand with Subnanomolar Affinity and Subtype Specificity. J Med Chem 2009; 52:3994-4006. [DOI: 10.1021/jm900413e] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Thomas Borrmann
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, An der Immenburg 4, D-53121 Bonn, Germany
| | - Sonja Hinz
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, An der Immenburg 4, D-53121 Bonn, Germany
| | - Daniela C. G. Bertarelli
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, An der Immenburg 4, D-53121 Bonn, Germany
| | - Wenjin Li
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, An der Immenburg 4, D-53121 Bonn, Germany
| | - Nicole C. Florin
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, An der Immenburg 4, D-53121 Bonn, Germany
| | - Anja B. Scheiff
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, An der Immenburg 4, D-53121 Bonn, Germany
| | - Christa E. Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, An der Immenburg 4, D-53121 Bonn, Germany
| |
Collapse
|
53
|
Haskó G, Csóka B, Németh ZH, Vizi ES, Pacher P. A(2B) adenosine receptors in immunity and inflammation. Trends Immunol 2009; 30:263-70. [PMID: 19427267 DOI: 10.1016/j.it.2009.04.001] [Citation(s) in RCA: 184] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 04/02/2009] [Accepted: 04/06/2009] [Indexed: 01/08/2023]
Abstract
A(2B) adenosine receptors are increasingly recognized as important orchestrators of inflammation. A(2B) receptor activation promotes the inflammatory response of mast cells, epithelial cells, smooth muscle cells and fibroblasts, thereby contributing to the pathophysiology of asthma and colitis. A(2B) receptor stimulation limits endothelial cell inflammatory responses and permeability and suppresses macrophage activation thereby preventing tissue injury after episodes of hypoxia and ischemia. A(2B) receptor stimulation also promotes the production of angiogenic cytokines by endothelial cells, mast cells and dendritic cells, aiding granuloma tissue formation and inflammatory resolution, but can also contribute to tumor growth. A(2B) receptors are, thus, potentially important pharmacological targets in treating immune system dysfunction and inflammation.
Collapse
Affiliation(s)
- György Haskó
- Department of Surgery, University of Medicine and Dentistry of New Jersey, Newark, 07103, USA.
| | | | | | | | | |
Collapse
|
54
|
Frick JS, MacManus CF, Scully M, Glover LE, Eltzschig HK, Colgan SP. Contribution of adenosine A2B receptors to inflammatory parameters of experimental colitis. THE JOURNAL OF IMMUNOLOGY 2009; 182:4957-64. [PMID: 19342675 DOI: 10.4049/jimmunol.0801324] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Inflammatory diseases influence tissue metabolism, significantly altering the profile of extracellular adenine nucleotides. A number of studies have suggested that adenosine (Ado) may function as an endogenously generated anti-inflammatory molecule. Given the central role of intestinal epithelial cells to the development of colitis, we hypothesized that specific Ado receptors would contribute to disease resolution in mucosal inflammation as modeled by dextran sodium sulfate (DSS) colitis. Initial profiling studies revealed that murine intestinal epithelial cells express predominantly the Ado A2B receptor (AA2BR) and to a lesser extent AA2AR. Guided by these results, we examined the contribution of AA2BR to colitis. Initial studies indicated that the severity of colitis was increased in Aa2br(-/-) mice relative to Aa2br(+/+) controls, as reflected by increased weight loss, colonic shortening, and disease activity indices. Likewise, enteral administration of the selective AA2BR inhibitor PSB1115 to Aa2br(+/+) mice resulted in a similar increase in severity of DSS colitis. Cytokine profiling of colonic tissue revealed specific deficiencies in IL-10 in Aa2br(-/-) mice relative to controls. Extensions of these findings in cultured human intestinal epithelial cells revealed that stable Ado analogs induce IL-10 mRNA and protein and that such increases can be blocked with PSB1115. Taken together, these studies indicate a central regulatory role for AA2BR-modulated IL-10 in the acute inflammatory phase of DSS colitis, thereby implicating AA2BR as an endogenously protective molecule expressed on intestinal epithelial cells.
Collapse
Affiliation(s)
- Julia-Stefanie Frick
- Institute for Medical Microbiology and Hygiene, University Hospital, Tübingen, Germany
| | | | | | | | | | | |
Collapse
|
55
|
Haskó G, Linden J, Cronstein B, Pacher P. Adenosine receptors: therapeutic aspects for inflammatory and immune diseases. Nat Rev Drug Discov 2009; 7:759-70. [PMID: 18758473 DOI: 10.1038/nrd2638] [Citation(s) in RCA: 880] [Impact Index Per Article: 58.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Adenosine is a key endogenous molecule that regulates tissue function by activating four G-protein-coupled adenosine receptors: A1, A2A, A2B and A3. Cells of the immune system express these receptors and are responsive to the modulatory effects of adenosine in an inflammatory environment. Animal models of asthma, ischaemia, arthritis, sepsis, inflammatory bowel disease and wound healing have helped to elucidate the regulatory roles of the various adenosine receptors in dictating the development and progression of disease. This recent heightened awareness of the role of adenosine in the control of immune and inflammatory systems has generated excitement regarding the potential use of adenosine-receptor-based therapies in the treatment of infection, autoimmunity, ischaemia and degenerative diseases.
Collapse
Affiliation(s)
- György Haskó
- Department of Surgery, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, 185 South Orange Avenue, Newark, New Jersey 07103, USA.
| | | | | | | |
Collapse
|
56
|
Neshat S, deVries M, Barajas-Espinosa AR, Skeith L, Chisholm SP, Lomax AE. Loss of purinergic vascular regulation in the colon during colitis is associated with upregulation of CD39. Am J Physiol Gastrointest Liver Physiol 2009; 296:G399-405. [PMID: 19074640 DOI: 10.1152/ajpgi.90450.2008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Evidence from patients with inflammatory bowel disease (IBD) and animal models suggests that inflammation alters blood flow to the mucosa, which precipitates mucosal barrier dysfunction. Impaired purinergic sympathetic regulation of submucosal arterioles, the resistance vessels of the splanchnic vasculature, is one of the defects identified during IBD and in mouse models of IBD. We hypothesized that this may be a consequence of upregulated catabolism of ATP during colitis. In vivo and in vitro video microscopy techniques were employed to measure the effects of purinergic agonists and inhibitors of CD39, an enzyme responsible for extracellular ATP catabolism, on the diameter of colonic submucosal arterioles from control mice and mice with dextran sodium sulfate [DSS, 5% (wt/vol)] colitis. Using a luciferase-based ATP assay, we examined the degradation of ATP and utilized real-time PCR, Western blotting, and immunohistochemistry to examine the expression and localization of CD39 during colitis. Arterioles from mice with DSS colitis did not constrict in response to ATP (10 microM) but did constrict in the presence of its nonhydrolyzable analog alpha,beta-methylene ATP (1 microM). alpha,beta-Methylene ADP (100 microM), an inhibitor of CD39, restored ATP-induced vasoconstriction in arterioles from mice with DSS-induced colitis. CD39 protein and mRNA expression was markedly increased during colitis. Immunohistochemical analysis demonstrated that, in addition to vascular CD39, F4/80-immunoreactive macrophages accounted for a large proportion of submucosal CD39 staining during colitis. These data implicate upregulation of CD39 in impaired sympathetic regulation of gastrointestinal blood flow during colitis.
Collapse
Affiliation(s)
- S Neshat
- Department of Physiology, Queen's University, Kingston, Ontario, Canada
| | | | | | | | | | | |
Collapse
|
57
|
McCloskey KD, Anderson UA, Davidson RA, Bayguinov YR, Sanders KM, Ward SM. Comparison of mechanical and electrical activity and interstitial cells of Cajal in urinary bladders from wild-type and W/Wv mice. Br J Pharmacol 2009; 156:273-83. [PMID: 19154433 DOI: 10.1111/j.1476-5381.2008.00006.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE W/W(v) and wild-type murine bladders were studied to determine whether the W/W(v) phenotype, which causes a reduction in, but not abolition of, tyrosine kinase activity, is a useful tool to study the function of bladder interstitial cells of Cajal (ICC). EXPERIMENTAL APPROACH Immunohistochemistry, tension recordings and microelectrode recordings of membrane potential were performed on wild-type and mutant bladders. KEY RESULTS Wild-type and W/W(v) detrusors contained c-Kit- and vimentin-immunopositive cells in comparable quantities, distribution and morphology. Electrical field stimulation evoked tetrodotoxin-sensitive contractions in wild-type and W/W(v) detrusor strips. Atropine reduced wild-type responses by 50% whereas a 25% reduction occurred in W/W(v) strips. The atropine-insensitive component was blocked by pyridoxal-5-phosphate-6-azophenyl-2',4'-disulphonic acid in both tissue types. Wild-type and W/W(v) detrusors had similar resting membrane potentials of -48 mV. Spontaneous electrical activity in both tissue types comprised action potentials and unitary potentials. Action potentials were nifedipine-sensitive whereas unitary potentials were not. Excitatory junction potentials were evoked by single pulses in both tissues. These were reduced by atropine in wild-type tissues but not in W/W(v) preparations. The atropine-insensitive component was abolished by pyridoxal-5-phosphate-6-azophenyl-2',4'-disulphonic acid in both preparations. CONCLUSIONS AND IMPLICATIONS Bladders from W/W(v) mice contain c-Kit- and vimentin-immunopositive ICC. There are similarities in the electrical and contractile properties of W/W(v) and wild-type detrusors. However, significant differences were found in the pharmacology of the responses to neurogenic stimulation with an apparent up-regulation of the purinergic component. These findings indicate that the W/W(v) strain may not be the best model to study ICC function in the bladder.
Collapse
Affiliation(s)
- K D McCloskey
- Physiology, Division of Basic Medical Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast, Northern Ireland, UK.
| | | | | | | | | | | |
Collapse
|
58
|
Abstract
Extracellular adenosine is produced in a coordinated manner from cells following cellular challenge or tissue injury. Once produced, it serves as an autocrine- and paracrine-signaling molecule through its interactions with seven-membrane-spanning G-protein-coupled adenosine receptors. These signaling pathways have widespread physiological and pathophysiological functions. Immune cells express adenosine receptors and respond to adenosine or adenosine agonists in diverse manners. Extensive in vitro and in vivo studies have identified potent anti-inflammatory functions for all of the adenosine receptors on many different inflammatory cells and in various inflammatory disease processes. In addition, specific proinflammatory functions have also been ascribed to adenosine receptor activation. The potent effects of adenosine signaling on the regulation of inflammation suggest that targeting specific adenosine receptor activation or inactivation using selective agonists and antagonists could have important therapeutic implications in numerous diseases. This review is designed to summarize the current status of adenosine receptor signaling in various inflammatory cells and in models of inflammation, with an emphasis on the advancement of adenosine-based therapeutics to treat inflammatory disorders.
Collapse
Affiliation(s)
- Michael R Blackburn
- Department of Biochemistry and Molecular Biology, The University of Texas-Houston Medical School, Houston, TX 77030, USA.
| | | | | | | |
Collapse
|
59
|
Abstract
Adenosine acts as a cytoprotective modulator in response to stress to an organ or tissue. Although short-lived in the circulation, it can activate four subtypes of G protein-coupled adenosine receptors (ARs): A(1), A(2A), A(2B), and A(3). The alkylxanthines caffeine and theophylline are the prototypical antagonists of ARs, and their stimulant actions occur primarily through this mechanism. For each of the four AR subtypes, selective agonists and antagonists have been introduced and used to develop new therapeutic drug concepts. ARs are notable among the GPCR family in the number and variety of agonist therapeutic candidates that have been proposed. The selective and potent synthetic AR agonists, which are typically much longer lasting in the body than adenosine, have potential therapeutic applications based on their anti-inflammatory (A(2A) and A(3)), cardioprotective (preconditioning by A(1) and A(3) and postconditioning by A(2B)), cerebroprotective (A(1) and A(3)), and antinociceptive (A(1)) properties. Potent and selective AR antagonists display therapeutic potential as kidney protective (A(1)), antifibrotic (A(2A)), neuroprotective (A(2A)), and antiglaucoma (A(3)) agents. AR agonists for cardiac imaging and positron-emitting AR antagonists are in development for diagnostic applications. Allosteric modulators of A(1) and A(3) ARs have been described. In addition to the use of selective agonists/antagonists as pharmacological tools, mouse strains in which an AR has been genetically deleted have aided in developing novel drug concepts based on the modulation of ARs.
Collapse
Affiliation(s)
- Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Biooorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0810, USA.
| |
Collapse
|
60
|
Viswanathan VK, Hodges K, Hecht G. Enteric infection meets intestinal function: how bacterial pathogens cause diarrhoea. Nat Rev Microbiol 2008; 7:110-9. [PMID: 19116615 DOI: 10.1038/nrmicro2053] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Infectious diarrhoea is a significant contributor to morbidity and mortality worldwide. In bacterium-induced diarrhoea, rapid loss of fluids and electrolytes results from inhibition of the normal absorptive function of the intestine as well as the activation of secretory processes. Advances in the past 10 years in the fields of gastrointestinal physiology, innate immunity and enteric bacterial virulence mechanisms highlight the multifactorial nature of infectious diarrhoea. This review explores the various mechanisms that contribute to loss of fluids and electrolytes following bacterial infections, and attempts to link these events to specific virulence factors and toxins.
Collapse
Affiliation(s)
- V K Viswanathan
- Department of Veterinary Science & Microbiology, University of Arizona, Tucson, Arizona 85721, USA
| | | | | |
Collapse
|
61
|
Kolachala VL, Vijay-Kumar M, Dalmasso G, Yang D, Linden J, Wang L, Gewirtz A, Ravid K, Merlin D, Sitaraman SV. A2B adenosine receptor gene deletion attenuates murine colitis. Gastroenterology 2008; 135:861-70. [PMID: 18601927 PMCID: PMC2632861 DOI: 10.1053/j.gastro.2008.05.049] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2008] [Revised: 05/08/2008] [Accepted: 05/15/2008] [Indexed: 01/17/2023]
Abstract
BACKGROUND & AIMS The A(2B) adenosine receptor (A(2B)AR) is the predominant adenosine receptor expressed in the colonic epithelia. We have previously shown that A(2B)AR mRNA and protein levels are up-regulated during colitis. In this study, we addressed the role of the A(2B)AR in the development of murine colitis and the potential mechanism underlying its effects. METHODS Dextran sodium sulfate (DSS), 2,4,6-trinitrobenzene sulfonic acid (TNBS), and Salmonella typhimurium were used to induce colitis in A(2B)AR-null mice (A(2B)AR(-/-)). Colitis was determined using established clinical and histologic scoring. Keratinocyte-derived chemokine (KC) measurements were performed using an enzyme-linked immunosorbent assay. RESULTS Colonic inflammation induced by DSS, TNBS, or S typhimurium was attenuated in A(2B)AR(-/-) compared with their wild-type counterparts. Clinical features, histologic score, and myeloperoxidase activity were significantly decreased in A(2B)AR(-/-) mice. However, A(2B)AR(-/-) showed increased susceptibility to systemic Salmonella infection. Tissue levels of the neutrophil chemokine, KC was decreased in colitic A(2B)AR(-/-) mice. In addition, flagellin-induced KC levels were attenuated in A(2B)AR(-/-) mice. Neutrophil chemotaxis in response to exogenous interleukin-8 was preserved in A(2B)AR(-/-) mice, suggesting intact neutrophil migration in response to appropriate stimuli. CONCLUSIONS These data demonstrate, for the first time, that the A(2B)AR plays a proinflammatory role in colitis. A(2B) receptor antagonism may be an effective treatment for acute inflammatory intestinal diseases such as acute flare of inflammatory bowel disease.
Collapse
Affiliation(s)
- Vasantha L Kolachala
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA
| | | | - Guilliume Dalmasso
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA
| | - Dan Yang
- Departments of Biochemistry and Medicine, Boston University School of Medicine, Boston, MA 02118
| | - Joel Linden
- Department of Medicine and Cardiovascular Research Center, University of Virginia, Charlottesville, VA
| | - Lixin Wang
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA
| | | | - Katya Ravid
- Departments of Biochemistry and Medicine, Boston University School of Medicine, Boston, MA 02118
| | - Didier Merlin
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA
| | - Shanthi V. Sitaraman
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA,Address correspondence to: Shanthi V. Sitaraman, Division of Digestive Diseases, Room 201-F, 615, Michael Street, Whitehead Research Building, Emory University, Atlanta, GA, 30322, Phone: 404-727-2430, Fax: 404-727-5767,
| |
Collapse
|
62
|
Purinergic receptors and gastrointestinal secretomotor function. Purinergic Signal 2008; 4:213-36. [PMID: 18604596 DOI: 10.1007/s11302-008-9104-4] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2007] [Accepted: 04/07/2008] [Indexed: 02/06/2023] Open
Abstract
Secretomotor reflexes in the gastrointestinal (GI) tract are important in the lubrication and movement of digested products, absorption of nutrients, or the diarrhea that occurs in diseases to flush out unwanted microbes. Mechanical or chemical stimulation of mucosal sensory enterochromaffin (EC) cells triggers release of serotonin (5-HT) (among other mediators) and initiates local reflexes by activating intrinsic primary afferent neurons of the submucous plexus. Signals are conveyed to interneurons or secretomotor neurons to stimulate chloride and fluid secretion. Inputs from myenteric neurons modulate secretory rates and reflexes, and special neural circuits exist to coordinate secretion with motility. Cellular components of secretomotor reflexes variably express purinergic receptors for adenosine (A1, A2a, A2b, or A3 receptors) or the nucleotides adenosine 5'-triphosphate (ATP), adenosine diphosphate (ADP), uridine 5'-triphosphate (UTP), or uridine diphosphate (UDP) (P2X(1-7), P2Y(2), P2Y(4), P2Y(6), P2Y(12) receptors). This review focuses on the emerging concepts in our understanding of purinergic regulation at these receptors, and in particular of mechanosensory reflexes. Purinergic inhibitory (A(1), A(3), P2Y(12)) or excitatory (A(2), P2Y(1)) receptors modulate mechanosensitive 5-HT release. Excitatory (P2Y(1), other P2Y, P2X) or inhibitory (A(1), A(3)) receptors are involved in mechanically evoked secretory reflexes or "neurogenic diarrhea." Distinct neural (pre- or postsynaptic) and non-neural distribution profiles of P2X(2), P2X(3), P2X(5), P2Y(1), P2Y(2), P2Y(4), P2Y(6), or P2Y(12) receptors, and for some their effects on neurotransmission, suggests their role in GI secretomotor function. Luminal A(2b), P2Y(2), P2Y(4), and P2Y(6) receptors are involved in fluid and Cl(-), HCO(3) (-), K(+), or mucin secretion. Abnormal receptor expression in GI diseases may be of clinical relevance. Adenosine A(2a) or A(3) receptors are emerging as therapeutic targets in inflammatory bowel diseases (IBD) and gastroprotection; they can also prevent purinergic receptor abnormalities and diarrhea. Purines are emerging as fundamental regulators of enteric secretomotor reflexes in health and disease.
Collapse
|