The identification and validation of biomarkers to support the assessment of novel therapeutics for COPD continues to be an important area of research. The aim of the current study was to identify ...systemic protein biomarkers correlated with measures of COPD severity, as well as specific protein signatures associated with comorbidities such as metabolic syndrome. 142 protein analytes were measured in serum of 140 patients with stable COPD, 15 smokers without COPD and 30 non-smoking controls. Seven analytes (sRAGE, EN-RAGE, NGAL, Fibrinogen, MPO, TGF-α and HB-EGF) showed significant differences between severe/very severe COPD, mild/moderate COPD, smoking and non-smoking control groups. Within the COPD subjects, univariate and multivariate analyses identified analytes significantly associated with FEV(1), FEV(1)/FVC and DLCO. Most notably, a set of 5 analytes (HB-EGF, Fibrinogen, MCP-4, sRAGE and Sortilin) predicted 21% of the variability in DLCO values. To determine common functions/pathways, analytes were clustered in a correlation network by similarity of expression profile. While analytes related to neutrophil function (EN-RAGE, NGAL, MPO) grouped together to form a cluster associated with FEV(1) related parameters, analytes related to the EGFR pathway (HB-EGF, TGF-α) formed another cluster associated with both DLCO and FEV(1) related parameters. Associations of Fibrinogen with DLCO and MPO with FEV(1)/FVC were stronger in patients without metabolic syndrome (r = -0.52, p = 0.005 and r = -0.61, p = 0.023, respectively) compared to patients with coexisting metabolic syndrome (r = -0.25, p = 0.47 and r = -0.15, p = 0.96, respectively), and may be driving overall associations in the general cohort. In summary, our study has identified known and novel serum protein biomarkers and has demonstrated specific associations with COPD disease severity, FEV(1), FEV(1)/FVC and DLCO. These data highlight systemic inflammatory pathways, neutrophil activation and epithelial tissue injury/repair processes as key pathways associated with COPD.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The sense of hearing is remarkable for its auditory dynamic range, which spans more than 10 ¹² in acoustic intensity. The mechanisms that enable the cochlea to transduce high sound levels without ...damage are of key interest, particularly with regard to the broad impact of industrial, military, and recreational auditory overstimulation on hearing disability. We show that ATP-gated ion channels assembled from P2X ₂ receptor subunits in the cochlea are necessary for the development of temporary threshold shift (TTS), evident in auditory brainstem response recordings as sound levels rise. In mice null for the P2RX2 gene (encoding the P2X ₂ receptor subunit), sustained 85-dB noise failed to elicit the TTS that wild-type (WT) mice developed. ATP released from the tissues of the cochlear partition with elevation of sound levels likely activates the broadly distributed P2X ₂ receptors on epithelial cells lining the endolymphatic compartment. This purinergic signaling is supported by significantly greater noise-induced suppression of distortion product otoacoustic emissions derived from outer hair cell transduction and decreased suprathreshold auditory brainstem response input/output gain in WT mice compared with P2RX2- null mice. At higher sound levels (≥95 dB), additional processes dominated TTS, and P2RX2- null mice were more vulnerable than WT mice to permanent hearing loss due to hair cell synapse disruption. P2RX2- null mice lacked ATP-gated conductance across the cochlear partition, including loss of ATP-gated inward current in hair cells. These data indicate that a significant component of TTS represents P2X ₂ receptor-dependent purinergic hearing adaptation that underpins the upper physiological range of hearing.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
We designed AM1241, a selective CB 2 cannabinoid receptor agonist, and used it to test the hypothesis that CB 2 receptor activation would reverse the sensory hypersensitivity observed in neuropathic ...pain states. AM1241 exhibits high affinity and selectivity for CB 2 receptors. It also exhibits high potency in vivo . AM1241 dose-dependently reversed tactile and thermal hypersensitivity produced by ligation of the L5 and L6 spinal nerves in rats. These effects were selectively antagonized by a CB 2 but not by a CB 1 receptor antagonist, suggesting that they were produced by actions of AM1241 at CB 2 receptors. AM1241 was also active in blocking spinal nerve ligation-induced tactile and thermal hypersensitivity in mice lacking CB 1 receptors (CB 1 -/- mice), confirming that AM1241 reverses sensory hypersensitivity independent of actions at CB 1 receptors. These findings demonstrate a mechanism leading to the inhibition of pain, one that targets receptors localized exclusively outside the CNS. Further, they suggest the potential use of CB 2 receptor-selective agonists for treatment of human neuropathic pain, a condition currently without consistently effective therapies. CB 2 receptor-selective agonist medications are predicted to be without the CNS side effects that limit the effectiveness of currently available medications.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
NGF has been suggested to play a role in urinary bladder dysfunction by mediating inflammation, as well as morphological and functional changes, in sensory and sympathetic neurons innervating the ...urinary bladder. To further explore the role of NGF in bladder sensory function, we generated a transgenic mouse model of chronic NGF overexpression in the bladder using the urothelium-specific uroplakin II (UPII) promoter. NGF mRNA and protein were expressed at higher levels in the bladders of NGF-overexpressing (NGF-OE) transgenic mice compared with wild-type littermate controls from postnatal day 7 through 12-16 wk of age. Overexpression of NGF led to urinary bladder enlargement characterized by marked nerve fiber hyperplasia in the submucosa and detrusor smooth muscle and elevated numbers of tissue mast cells. There was a marked increase in the density of CGRP- and substance P-positive C-fiber sensory afferents, neurofilament 200-positive myelinated sensory afferents, and tyrosine hydroxylase-positive sympathetic nerve fibers in the suburothelial nerve plexus. CGRP-positive ganglia were also present in the urinary bladders of transgenic mice. Transgenic mice had reduced urinary bladder capacity and an increase in the number and amplitude of nonvoiding bladder contractions under baseline conditions in conscious open-voiding cystometry. These changes in urinary bladder function were further associated with an increased referred somatic pelvic hypersensitivity. Thus, chronic urothelial NGF overexpression in transgenic mice leads to neuronal proliferation, focal increases in urinary bladder mast cells, increased urinary bladder reflex activity, and pelvic hypersensitivity. NGF-overexpressing mice may, therefore, provide a useful transgenic model for exploring the role of NGF in urinary bladder dysfunction.
Extracellular ATP plays a role in nociceptive signalling and sensory regulation of visceral function through ionotropic receptors
variably composed of P2X 2 and P2X 3 subunits. P2X 2 and P2X 3 ...subunits can form homomultimeric P2X 2 , homomultimeric P2X 3 , or heteromultimeric P2X 2/3 receptors. However, the relative contribution of these receptor subtypes to afferent functions of ATP in vivo is poorly understood. Here we describe null mutant mice lacking the P2X 2 receptor subunit (P2X 2 â/â ) and double mutant mice lacking both P2X 2 and P2X 3 subunits (P2X 2 /P2X 3 Dblâ/â ), and compare these with previously characterized P2X 3 â/â mice. In patch-clamp studies, nodose, coeliac and superior cervical ganglia (SCG) neurones from wild-type mice responded
to ATP with sustained inward currents, while dorsal root ganglia (DRG) neurones gave predominantly transient currents. Sensory
neurones from P2X 2 â/â mice responded to ATP with only transient inward currents, while sympathetic neurones had barely detectable responses. Neurones
from P2X 2 /P2X 3 Dblâ/â mice had minimal to no response to ATP. These data indicate that P2X receptors on sensory and sympathetic ganglion neurones
involve almost exclusively P2X 2 and P2X 3 subunits. P2X 2 â/â and P2X 2 /P2X 3 Dblâ/â mice had reduced pain-related behaviours in response to intraplantar injection of formalin. Significantly, P2X 3 â/â , P2X 2 â/â , and P2X 2 /P2X 3 Dblâ/â mice had reduced urinary bladder reflexes and decreased pelvic afferent nerve activity in response to bladder distension.
No deficits in a wide variety of CNS behavioural tests were observed in P2X 2 â/â mice. Taken together, these data extend our findings for P2X 3 â/â mice, and reveal an important contribution of heteromeric P2X 2/3 receptors to nociceptive responses and mechanosensory transduction within the urinary bladder.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The molecular basis of mechanosensory transduction by primary sensory neurones remains poorly understood. Amongst candidate
transducer molecules are members of the acid-sensing ion channel (ASIC) ...family; nerve fibre recordings have shown ASIC2 and
ASIC3 null mutants have aberrant responses to suprathreshold mechanical stimuli. Using the neuronal cell body as a model of
the sensory terminal we investigated if ASIC2 or 3 contributed to mechanically activated currents in dorsal root ganglion
(DRG) neurones. We cultured neurones from ASIC2 and ASIC3 null mutants and compared response properties with those of wild-type
controls. Neuronal subpopulations categorized by cell size, action potential duration and isolectin B4 (IB4) binding generated
distinct responses to mechanical stimulation consistent with their predicted in vivo phenotypes. In particular, there was a striking relationship between action potential duration and mechanosensitivity as
has been observed in vivo . Putative low threshold mechanoreceptors exhibited rapidly adapting mechanically activated currents. Conversely, when nociceptors
responded they displayed slowly or intermediately adapting currents that were smaller in amplitude than responses of low threshold
mechanoreceptor neurones. No differences in current amplitude or kinetics were found between ASIC2 and/or ASIC3 null mutants
and controls. Ruthenium red (5 μ m ) blocked mechanically activated currents in a voltage-dependent manner, with equal efficacy in wild-type and knockout animals.
Analysis of proton-gated currents revealed that in wild-type and ASIC2/3 double knockout mice the majority of putative low
threshold mechanoreceptors did not exhibit ASIC-like currents but exhibited a persistent current in response to low pH. Our
findings are consistent with another ion channel type being important in DRG mechanotransduction.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Emphysema in chronic obstructive pulmonary disease (COPD) can be characterized by high-resolution chest computed tomography (HRCT); however, the repeated use of HRCT is limited because of concerns ...regarding radiation exposure and cost.
To evaluate biomarkers associated with emphysema and COPD-related clinical characteristics, and to assess the relationships of soluble receptor for advanced glycation endproducts (sRAGE), a candidate systemic biomarker identified in this study, with single-nucleotide polymorphisms (SNPs) in the gene coding for RAGE (AGER locus) and with clinical characteristics.
Circulating levels of 111 biomarkers were analyzed for association with clinical characteristics in 410 patients with COPD enrolled in the TESRA study. sRAGE was also measured in the ECLIPSE cohort in 1,847 patients with COPD, 298 smokers and 204 nonsmokers. The association between 21 SNPs in the AGER locus with sRAGE levels and clinical characteristics was also investigated.
sRAGE was identified as a biomarker of diffusing capacity of carbon monoxide and lung density in the TESRA cohort. In the ECLIPSE cohort, lower sRAGE levels were associated with increased emphysema, increased Global Initiative for Chronic Obstructive Lung Disease stage, and COPD disease status. The associations with emphysema in both cohorts remained significant after covariate adjustment (P < 0.0001). One SNP in the AGER locus, rs2070600, was associated with circulating sRAGE levels both in TESRA (P = 0.0014) and ECLIPSE (7.07 × 10(-16)), which exceeded genome-wide significance threshold. Another SNP (rs2071288) was also associated with sRAGE levels (P = 0.01) and diffusing capacity of carbon monoxide (P = 0.01) in the TESRA study.
Lower circulating sRAGE levels are associated with emphysema severity and genetic polymorphisms in the AGER locus are associated with systemic sRAGE levels. Clinical trial registered with www.clinicaltrials.gov (NCT 00413205 and NCT 00292552).
The umbrella cells that line the bladder are mechanosensitive, and bladder filling increases the apical surface area of these cells; however, the upstream signals that regulate this process are ...unknown. Increased pressure stimulated ATP release from the isolated uroepithelium of rabbit bladders, which was blocked by inhibitors of vesicular transport, connexin hemichannels, ABC protein family members, and nucleoside transporters. Pressure-induced increases in membrane capacitance (a measure of apical plasma membrane surface area where 1 microF approximately equals 1 cm2) were inhibited by the serosal, but not mucosal, addition of apyrase or the purinergic receptor antagonist PPADS. Upon addition of purinergic receptor agonists, increased capacitance was observed even in the absence of pressure. Moreover, knockout mice lacking expression of P2X2 and/or P2X3 receptors failed to show increases in apical surface area when exposed to hydrostatic pressure. Treatments that prevented release of Ca2+ from intracellular stores or activation of PKA blocked ATPgammaS-stimulated changes in capacitance. These results indicate that increased hydrostatic pressure stimulates release of ATP from the uroepithelium and that upon binding to P2X and possibly P2Y receptors on the umbrella cell, downstream Ca2+ and PKA second messenger cascades may act to stimulate membrane insertion at the apical pole of these cells.
Pharmacology of P2X channels Gever, Joel R; Cockayne, Debra A; Dillon, Michael P ...
Pflügers Archiv,
08/2006, Volume:
452, Issue:
5
Journal Article
Peer reviewed
Significant progress in understanding the pharmacological characteristics and physiological importance of homomeric and heteromeric P2X channels has been achieved in recent years. P2X channels, gated ...by ATP and most likely trimerically assembled from seven known P2X subunits, are present in a broad distribution of tissues and are thought to play an important role in a variety of physiological functions, including peripheral and central neuronal transmission, smooth muscle contraction, and inflammation. The known homomeric and heteromeric P2X channels can be distinguished from each other on the basis of pharmacological differences when expressed recombinantly in cell lines, but whether this pharmacological classification holds true in native cells and in vivo is less well-established. Nevertheless, several potent and selective P2X antagonists have been discovered in recent years and shown to be efficacious in various animal models including those for visceral organ function, chronic inflammatory and neuropathic pain, and inflammation. The recent advancement of drug candidates targeting P2X channels into human trials, confirms the medicinal exploitability of this novel target family and provides hope that safe and effective medicines for the treatment of disorders involving P2X channels may be identified in the near future.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Pain remains an area of considerable unmet clinical need, and this is particularly true of pain associated with bone metastases, in part because existing analgesic drugs show only limited efficacy in ...many patients and in part because of the adverse side effects associated with these agents. An important issue is that the nature and roles of the algogens produced in bone that drive pain-signalling systems remain unknown. Here, we tested the hypothesis that adenosine triphosphate is one such key mediator through actions on P2X3 and P2X2/3 receptors, which are expressed selectively on primary afferent nocioceptors, including those innervating the bone. Using a well-established rat model of bone cancer pain, AF-353, a recently described potent and selective P2X3 and P2X2/3 receptor antagonist, was administered orally to rats and found to produce highly significant prevention and reversal of bone cancer pain behaviour. This attenuation occurred without apparent modification of the disease, since bone destruction induced by rat MRMT-1 carcinoma cells was not significantly altered by AF-353. Using in vivo electrophysiology, evidence for a central site of action was provided by dose-dependent reductions in electrical, mechanical and thermal stimuli-evoked dorsal horn neuronal hyperexcitability following direct AF-353 administration onto the spinal cord of bone cancer animals. A peripheral site of action was also suggested by studies on the extracellular release of adenosine triphosphate from MRMT-1 carcinoma cells. Moreover, elevated phosphorylated-extracellular signal-regulated kinase expression in dorsal root ganglion neurons, induced by co-cultured MRMT-1 carcinoma cells, was significantly reduced in the presence of AF-353. These data suggest that blockade of P2X3 and P2X2/3 receptors on both the peripheral and central terminals of nocioceptors contributes to analgesic efficacy in a model of bone cancer pain. Thus, systemic P2X3 and P2X2/3 receptor antagonists with central nervous system penetration may offer a promising therapeutic tool in treating bone cancer pain.
PDF
