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D B Jacoby

Publications and source records attributed to D B Jacoby.

At least 37 records · Page 2Linked to original sources
PubMed1998

Virus- and interferon-induced loss of inhibitory M2 muscarinic receptor function and gene expression in cultured airway parasympathetic neurons.

Viral infections increase vagally mediated reflex bronchoconstriction. Decreased function of inhibitory M2 muscarinic receptors on the parasympathetic nerve endings is likely to contribute to increased acetylcholine release. In this study, we used cultured airway parasympathetic neurons to determine the effects of parainfluenza virus and of interferon (IFN)-gamma on acetylcholine release, inhibitory M2 receptor function, and M2 receptor gene expression. In control cultures, electrically stimulated acetylcholine release increased when the inhibitory M2 receptors were blocked using atropine (10(-)5 M) and decreased when these receptors were stimulated using methacholine (10(-)5 M). Acetylcholine release was increased by viral infection and by treatment with IFN-gamma (300 U/ml). In these cells, atropine did not further potentiate, nor did methacholine inhibit, acetylcholine release, suggesting decreased inhibitory M2 receptor function and/or expression. Using a competitive reverse transcription-polymerase chain reaction method, we demonstrated that M2 receptor gene expression was decreased by more that an order of magnitude both by virus infection and by treatment with IFN. Thus, viral infections may increase vagally mediated bronchoconstriction both by directly inhibiting M2 receptor gene expression and by causing release of IFN-gamma which inhibits M2 receptor gene expression.

Acetylcholine↗
PubMed1998

Effects of tachykinin NK1 receptor antagonists on vagal hyperreactivity and neuronal M2 muscarinic receptor function in antigen challenged guinea-pigs.

1. The role of tachykinin NK1 receptors in the recruitment of eosinophils to airway nerves, loss of inhibitory neuronal M2 muscarinic receptor function and the development of vagal hyperreactivity was tested in antigen-challenged guinea-pigs. 2. In anaesthetized guinea-pigs, the muscarinic agonist, pilocarpine (1-100 microg kg(-1), i.v.), inhibited vagally induced bronchoconstriction, in control, but not in antigen-challenged guinea-pigs 24 h after antigen challenge. This indicates normal function of neuronal M2 muscarinic receptors in controls and loss of neuronal M2 receptor function in challenged guinea-pigs. Pretreatment of sensitized guinea-pigs with the NK1 receptor antagonists CP99994 (4 mg kg(-1), i.p.), SR140333 (1 mg kg(-1), s.c.) or CP96345 (15 mg kg(-1), i.p.) before antigen challenge, prevented M2 receptor dysfunction. 3. Neither administration of the NK1 antagonists after antigen challenge, nor pretreatment with an NK2 receptor antagonist, MEN10376 (5 micromol kg(-1), i.p.), before antigen challenge, prevented M2 receptor dysfunction. 4. Electrical stimulation of the vagus nerves caused a frequency-dependent (2-15 Hz, 10 V, 0.2 ms for 5 s) bronchoconstriction that was significantly increased following antigen challenge. Pretreatment with the NK1 receptor antagonists CP99994 or SR140333 before challenge prevented this increase. 5. Histamine (1-20 nmol kg(-1), i.v.) caused a dose-dependent bronchoconstriction, which was vagally mediated, and was significantly increased in antigen challenged guinea-pigs compared to controls. Pretreatment of sensitized animals with CP99994 before challenge prevented the increase in histamine-induced reactivity. 6. Bronchoalveolar lavage and histological studies showed that after antigen challenge significant numbers of eosinophils accumulated in the airways and around airway nerves. This eosinophilia was not altered by pretreatment with the NK1 receptor antagonist CP99994. 7. These data indicate that pretreatment of antigen-sensitized guinea-pigs with NK1, but not with NK2 receptor antagonists before antigen challenge prevented the development of hyperreactivity by protecting neuronal M2 receptor function. NK1 receptor antagonists do not inhibit eosinophil accumulation around airway nerves.

Animals↗
PubMed1998

Pulmonary neuronal M2 muscarinic receptor function in asthma and animal models of hyperreactivity.

In the lungs neuronal M2 muscarinic receptors limit acetylcholine release from postganglionic cholinergic nerves. These inhibitory M2 receptors are dysfunctional in antigen challenged guinea pigs and in humans with asthma which leads to an increase in vagally mediated hyperreactivity. In vitro, eosinophil products act as allosteric antagonists at neuronal M2 muscarinic receptors. In vivo, displacing or neutralising MBP preserves neuronal M2 muscarinic receptor function and prevents hyperreactivity. Thus, there is good evidence from animal studies that after antigen challenge pulmonary M2 muscarinic receptors become dysfunctional because MBP inhibits their function. Loss of function of pulmonary neuronal M2 muscarinic receptors has also been reported in patients with asthma, although the clinical significance of this dysfunction and the mechanisms underlying it are not yet established.

Acetylcholine↗
PubMed1998

Role of oxidants in influenza virus-induced gene expression.

Influenza virus-induced epithelial damage may be mediated, in part, by reactive oxygen intermediates (ROIs). In this study, we investigated the role of ROIs in the influenza virus-induced gene expression of antioxidant enzymes and in the activation of nuclear factor-kappa B (NF-kappa B), an oxidant-sensitive transcriptional factor. Influenza virus infection increased production of intracellular ROIs in A549 pulmonary epithelial cells. Induction of manganese superoxide dismutase (MnSOD) mRNA correlated with increased MnSOD protein and enzyme activity. Influenza virus infection also activated NF-kappa B binding as determined by an electrophoretic mobility shift assay. Pretreatment of A549 cells with N-acetyl-L-cysteine attenuated virus-induced NF-kappa B activation and interleukin (IL)-8 mRNA induction but did not block induction of MnSOD mRNA. In contrast, pyrrolidine dithiocarbamate blocked activation of NF-kappa B and induction of MnSOD and IL-8 mRNAs. Treatment with pyrrolidine dithiocarbamate also markedly decreased virus-induced cell death. Thus oxidants are involved in influenza virus-induced activation of NF-kappa B, in the expression of IL-8 and MnSOD, and in virus-induced cell death.

Acetylcysteine↗
PubMed1998

Muscarinic receptors and control of airway smooth muscle.

Contraction of airway smooth muscle is mediated by M3 muscarinic receptors on the airway smooth muscle. However, there is no evidence suggesting that hyperresponsiveness results from any alterations in function of these M3 muscarinic receptors. In contrast, there is clearly increased release of the neurotransmitter acetylcholine in animal models of hyperactivity and in asthma. Release of acetylcholine is controlled by inhibitory M2 muscarinic receptors, and it appears that it is these M2 receptors that are dysfunctional in animal models of hyperresponsiveness. Allergen-induced M2 receptor dysfunction is absolutely dependent upon an influx of eosinophils into the airways. Activated eosinophils release major basic protein, which binds to M2 receptors and prevents binding of acetylcholine. Thus, the normal negative feedback control of acetylcholine release is lost, and acetylcholine release is increased. In conclusion, loss of function of inhibitory M2 muscarinic receptors on the airway parasympathetic nerves causes vagally mediated bronchoconstriction and hyperresponsiveness following antigen challenge.

Animals↗
PubMed1997

Pretreatment with antibody to eosinophil major basic protein prevents hyperresponsiveness by protecting neuronal M2 muscarinic receptors in antigen-challenged guinea pigs.

In antigen-challenged guinea pigs there is recruitment of eosinophils into the lungs and to airway nerves, decreased function of inhibitory M2 muscarinic autoreceptors on parasympathetic nerves in the lungs, and airway hyperresponsiveness. A rabbit antibody to guinea pig eosinophil major basic protein was used to determine whether M2 muscarinic receptor dysfunction, and the subsequent hyperresponsiveness, are due to antagonism of the M2 receptor by eosinophil major basic protein. Guinea pigs were sensitized, challenged with ovalbumin and hyperresponsiveness, and M2 receptor function tested 24 h later with the muscarinic agonist pilocarpine. Antigen-challenged guinea pigs were hyperresponsive to electrical stimulation of the vagus nerves compared with controls. Likewise, loss of M2 receptor function was demonstrated since the agonist pilocarpine inhibited vagally-induced bronchoconstriction in control but not challenged animals. Pretreatment with rabbit antibody to guinea pig eosinophil major basic protein prevented hyperresponsiveness, and protected M2 receptor function in the antigen-challenged animals without inhibiting eosinophil accumulation in the lungs or around the nerves. Thus, hyperresponsiveness is a result of inhibition of neuronal M2 muscarinic receptor function by eosinophil major basic protein in antigen-challenged guinea pigs.

Acetylcholine↗
PubMed1997

Increased function of inhibitory neuronal M2 muscarinic receptors in diabetic rat lungs.

1. The function of inhibitory neuronal M2 muscarinic receptors in diabetic rat lungs was investigated. 2. Neuronal M2 muscarinic receptors inhibit acetylcholine release from parasympathetic nerves. Thus, stimulation of neuronal M2 muscarinic receptors with muscarinic agonists, such as pilocarpine, inhibits acetylcholine release and vagally induced bronchoconstriction. In contrast, blockade of neuronal M2 muscarinic receptors with selective M2 muscarinic antagonists, such as AF-DX 116, potentiates acetylcholine release and vagally induced bronchoconstriction. 3. Rats were made diabetic by streptozotocin (65 mg kg (-1), i.v.). After 7 14 days the rats were anaesthetized with urethane (1.5 g kg (-1), i.p.), tracheostomized, vagotomized, ventilated and paralysed with suxamethonium (30 mg kg (-1), i.v.). Some 7 day diabetic rats were treated with low doses of long acting (NPH) insulin (2 units day (-1), s.c.) for 7 days before experimentation. This dose of insulin was not sufficient to restore normoglycaemia in diabetic rats. Thus, insulin-treated diabetic rats remained hyperglycaemic. 4. Distal electrical stimulation (5 70 Hz, 6 s, 40 V, 0.4 ms) of the vagi caused bronchoconstriction, measured as an increase in inflation pressure and bradycardia. In diabetic rats, vagally induced bronchoconstriction was significantly depressed vs controls. In contrast, bronchoconstriction caused by i.v. acetylcholine was similar in diabetic and control animals. 5. The function of neuronal M2 muscarinic receptors was tested with the muscarinic agonist pilocarpine (0.001-100.0 microg kg (-1), i.v.) and the antagonist AF-DX 116 (0.01-3.0 mg kg (-1), i.v.). Pilocarpine inhibited vagally-induced bronchoconstriction (30 Hz, 20-40 V, 0.4 ms at 6 s) and AF-DX 116 potentiated vagally-induced bronchoconstriction (20 Hz, 20-40 V, 0.4 ms at 6 s) to a significantly greater degree in diabetic rats compared to controls. 6. Both frequency-dependent vagally-induced bronchoconstriction and M2 muscarinic receptor function could be restored to nearly control values in diabetic rats treated with low doses of insulin. 7. Displacement of [3H]QNB (1 nM) with the agonist carbachol (10.0 nM-10.0 mM) from diabetic cardiac M2 muscarinic receptors revealed a half log increase in agonist binding affinity at both the high and low affinity binding sites vs controls. In contrast, M2 receptors from insulin-treated diabetic rat hearts showed no significant difference in binding affinity vs controls. 8. These data show that neuronal M2 muscarinic receptors in the lungs have increased function in diabetic rats, suggesting that insulin modulates M2 muscarinic receptor function.

Acetylcholine↗
PubMed1997

Fetal pig neural cells as a restorative therapy for neurodegenerative disease.

With proper immunosuppression, interspecies transplantation of porcine as well as other species of neural cells survive, mature, and integrate into the host in a manner which reconstructs much of the appropriate neural circuitry. These transplants have been shown to alleviate many of the symptoms of various disorders of the central nervous system. In this study, we addressed immunological and maturation issues with regards to intracerebral transplantation of fetal porcine neural cells. First, we compared fetal neural xenograft survival in athymic nude rats versus rats immunosuppressed with cyclosporin A and found that there is little discernible difference between porcine grafts in the 2 recipients. We also found that ectopic transplantation of cells isolated from the porcine striatal primordium can survive and develop into grafts composed of both neuronal and glial phenotypes within the rat hippocampus. This fact raises the possibility that cells of a particular neurotransmitter type (e.g., GABAergic cells) developing from the striatal precursor cells can be transplanted outside the striatum of the adult brain and have physiological effects.

Animals↗
PubMed1997

Localization of eosinophils to airway nerves and effect on neuronal M2 muscarinic receptor function.

Neuronal M2 muscarinic receptors inhibit acetylcholine release from pulmonary parasympathetic nerves but are dysfunctional in antigen-challenged animals and asthmatics. Deletion of pulmonary eosinophils protects M2 receptor function in antigen-challenged guinea pigs. Therefore, the association of eosinophils with airway nerves was investigated. Nerve-associated eosinophils were significantly increased in challenged animals compared with controls (0.75 +/- 0.05 vs. 0.28 +/- 0.05 eosinophils/nerve). In antigen-challenged animals, eosinophil density was greatest around airway nerves, suggesting recruitment to the nerves. M2 receptor function was inversely correlated with the number of eosinophils per nerve, thus eosinophils are associated with airway nerves in antigen-challenged guinea pigs, where they impair M2 receptor function. In airways from three patients with fatal asthma, 196 of 637 eosinophils (30%) were associated with nerves, and release of eosinophil major basic protein was evident; conversely, in three control patients 1 of 11 (9%) eosinophils were in contact with nerves. Thus eosinophils and their granule proteins are also seen in association with airway nerves in patients with asthma.

Acetylcholinesterase↗
PubMed1996

Viral infection induces dependence of neuronal M2 muscarinic receptors on cyclooxygenase in guinea pig lung.

Inhibitory M2 muscarinic receptors on parasympathetic nerve endings in the lungs decrease release of acetylcholine, inhibiting vagally induced bronchoconstriction. Neuronal M2 receptor function can be studied using selective agonists and antagonists such as pilocarpine and gallamine. In pathogen-free guinea pigs indomethacin (1 mg/kg) did not alter the effect of either gallamine or pilocarpine, thus in pathogen free animals neuronal M2 muscarinic receptors function independently of cyclooxygenase products. However, in guinea pigs infected with virus, (which causes temporary loss of M2 receptor function), and then allowed to recover for 8 wk (to allow recovery of M2 receptors), indomethacin prevented both gallamine's potentiation and pilocarpine's inhibition of vagally induced bronchoconstriction. This new effect of indomethacin was not blocked by the addition of a 5-lipoxygenase inhibitor, AA861. However, the selective COX II inhibitor, L-745,337, had the same effect as indomethacin. Since exposure to ozone also caused neuronal M2 receptors to become dependent upon cyclooxygenase the effects of viral infection are likely to be due to inflammation. Thus, despite apparent recovery of normal M2 receptor function after viral infection or ozone, linkage of these receptors is chronically altered such that they become largely dependent on the activity of COX II.

Animals↗
PubMed1996

DNA binding specificities of YPF1, a Drosophila homolog to the DNA binding subunit of human DNA-dependent protein kinase, Ku.

YPF1, a heterodimeric protein from Drosophila melanogaster, is a homolog to Ku, the DNA binding subunit of human DNA-dependent protein kinase. This kinase is crucial in transcriptional activation, V(D)J recombination, double-strand break repair, and both topoisomerase and helicase activities. To investigate functional homology between YPF1 and Ku, we examined DNA binding properties of YPF1. Like Ku, at 100 mM KCl, YPF1 binding has no detectable DNA sequence specificity, requires a DNA terminus, and has a concentration-dependent stoichiometry consistent with subsequent translocation along DNA. YPF1 differs from Ku by having a 10(5)-fold higher affinity. At 400 mM KCl, YPF1 still prefers DNA termini but shows binding specificities not observed previously with Ku. In descending order of affinity, YPF1 binds to: specific DNA sequences with a specific polarity and spacing relative to DNA termini; nonspecific linear DNA; and circular DNA. At this higher ionic strength, binding stoichiometry is concentration independent, indicating that YPF1 remains bound to ends. These results demonstrate a strong functional homology between YPF1 and Ku at physiological ionic strength. The strong binding of YPF1 has also allowed us to detect underlying binding specificities that may be specific to YPF1 and its function.

Animals↗
PubMed1996

Oxidant stress responses in influenza virus pneumonia: gene expression and transcription factor activation.

The pathogenesis of influenza virus infections of the lungs is in part mediated by oxidative stress. Such infections might therefore be expected to induce expression of stress-response genes and genes encoding antioxidant enzymes and to activate transcriptional regulatory proteins. Mice (C57B1/6 and C3H/HeJ) were infected intranasally with influenza virus A/PR/8/34 (H1N1). Expression of the genes encoding the antioxidant enzymes manganese superoxide dismutase (Mn- SOD), indoleamine-2, 3-dioxygenase (IDO), heme oxygenase-1, and glutathione peroxidase were increased in the lungs of virus-infected animals. Cu/ZnSOD and catalase mRNA were not induced by viral infection. Activation of the transcriptional regulatory proteins AP-1, C/EBP, and NF-kappa B (which are known to be affected by oxidant stress) was demonstrated by electrophoretic mobility shift assay after viral infection. In the case of MnSOD, despite increased gene expression enzyme activity was not increased. In contrast, for heme oxygenase-1 both mRNA and activity were increased. C3H/ HeJ and C57B1/6 mice, which are known to have different responses to other types of oxidant stress, also differed in their responses to viral infection. Induction of heme oxygenase-1 expression was greater in C57B1/6 mice than in C3H/ HeJ mice, although inhibiting this enzyme did not alter virus-induced mortality. In contrast, IDO was more strongly induced in C3H/HeJ mice. Activation of NF-kappa B was much more marked in C57B1/6 mice than in C3H/HeJ mice. Although virus replication and inflammatory responses were equivalent in the two strains, lung injury (as measured by wet-to-dry wt ratios) and mortality were greater in C3H/HeJ mice than in C57B1/6 mice, a difference that may be related to differing oxidant stress responses. Thus influenza pneumonia causes an oxidant stress response in the lungs, the nature of which is determined in part by the genetic background of the host.

Animals↗
PubMed1996

Cultures of airway parasympathetic nerves express functional M2 muscarinic receptors.

To study the control of acetylcholine release from airway parasympathetic neurons, primary cultures of these cells were established. Guinea pig tracheas were disaggregated with collagenase and plated onto matrigel-coated plates in medium that contained cytosine arabinoside to inhibit growth of dividing cells. Over 7 to 10 days neurites grow from the cell bodies, reaching a length of 2 mm. The vast majority of the cells in these cultures were neurons, as identified by morphology and staining with Neurotag and with antibody to neuron-specific antigen protein gene product 9.5. Cultured neurons contained acetylcholine, which was released by electrical field stimulation. Thus these were parasympathetic neurons. Staining with antibodies to M1, M2, and M4 muscarinic receptors revealed the presence of only M2 receptors. Likewise, reverse transcription-polymerase chain reaction using primers for M1, M2, and M4 muscarinic receptors revealed mRNA only for M2 receptors. Blocking these M2 receptors using atropine potentiated the stimulated release of acetylcholine, demonstrating that the M2 receptors inhibit acetylcholine release, as they have been shown to do in vivo. Thus airway parasympathetic neurons can be grown in culture, they retain the ability to synthesize and release acetylcholine, and they express functional inhibitory M2 muscarinic receptors.

Acetylcholine↗
PubMed1995

NIH conference. Airway inflammation.

Diseases characterized by airway inflammation, excessive airway secretion, and airway obstruction affect a substantial proportion of the population. These diseases include asthma, chronic bronchitis, bronchiectasis, and cystic fibrosis. Asthma and chronic bronchitis may affect 25 million persons in the United States. Much progress has been made in the last decade toward an understanding of the mechanisms underlying chronic airway inflammation; recent work has resulted in several new concepts of the initiation and maintenance of airway inflammation. Airway production of chemokines, cytokines, and growth factors in response to irritants, infectious agents, and inflammatory mediators may play an important role in the modulation of acute and chronic airway inflammation. Lipid mediators may be produced by resident airway cells and by inflammatory cells; production of these mediators may also be altered by inflammatory cytokines. Increased airway obstruction may be related to intercurrent viral respiratory infection and to the induction of airway inflammation and airway hyperreactivity that results from such infection. Furthermore, several models exist to explain the processes by which airway inflammation is perpetuated in diseases such as asthma and chronic bronchitis. These include neurogenic inflammation, the perpetuation of the acute inflammatory response, and cycles of airway epithelial cell-mediated and inflammatory cell-mediated recruitment and activation of inflammatory cells. An understanding of these mechanisms of airway inflammation may provide the clinician with new therapeutic approaches to the treatment of these common and chronic diseases.

Bronchi↗
PubMed1995

Pretreatment with an antibody to interleukin-5 prevents loss of pulmonary M2 muscarinic receptor function in antigen-challenged guinea pigs.

Inhalational challenge with antigen decreases the function of inhibitory M2 muscarinic autoreceptors on parasympathetic nerves in the lung, increasing the release of acetylcholine from the vagus nerves and potentiating vagally induced bronchoconstriction. It is possible that eosinophils cause M2 receptor dysfunction, perhaps by releasing positively charged proteins that are M2 receptor antagonists. Because of the probable role of interleukin-5 in initiating and maintaining the eosinophil infiltration, we tested the function of neuronal M2 receptors in antigen-challenged guinea pigs after pretreatment with a monoclonal antibody to interleukin-5 (TRFK-5). Ovalbumin was given intraperitoneally to sensitize the animals. Three weeks later, the animals were injected intraperitoneally with either TRFK-5 (240 micrograms/kg i.p.) or saline. Beginning three days later, they were challenged with an ovalbumin aerosol for 5 min on each of four consecutive days. M2 receptor function was tested 24 h after the last antigen challenge. Electrical stimulation of both vagi caused bronchoconstriction and bradycardia. In control animals, pilocarpine attenuated, and gallamine potentiated, vagally induced bronchoconstriction by stimulating and blocking neuronal M2 muscarinic receptors, respectively. In challenged animals that did not receive TRFK-5, these effects were markedly reduced, confirming M2 receptor dysfunction. In TRFK-5-treated guinea pigs, the effects of both pilocarpine and gallamine were the same as those in control animals, demonstrating normal M2 receptor function. Pretreatment with TRFK-5 selectively inhibited the migration of eosinophils into the lungs as measured by lung lavage. Thus the function of M2 muscarinic receptors in antigen-challenged guinea pigs can be protected by inhibiting eosinophil influx into the lungs.

Animals↗
PubMed1995

Infection of a human respiratory epithelial cell line with rhinovirus. Induction of cytokine release and modulation of susceptibility to infection by cytokine exposure.

Rhinovirus infections cause over one third of all colds and are a contributing factor to exacerbations of asthma. To gain insights into the early biochemical events that occur in infected epithelial cells, we develop, for the first time, a model in which a pure respiratory epithelial cell population can be routinely infected by rhinovirus. Viral infection was confirmed by demonstrating that viral titers of supernatants and lysates from infected cell increased with time and by PCR. Infection by rhinovirus 14 was inhibited by homotypic antiserum and by antibodies to intercellular adhesion molecule-1 (ICAM-1), the receptor for this virus. Susceptibility of epithelial cells to infection by rhinovirus 14 (but not rhinovirus 2, an ICAM-1 independent strain) can be increased by preexposure of cells to TNF alpha, whereas IFN gamma reduces susceptibility to infection by both rhinovirus strains. Rhinovirus infection per se does not markedly alter ICAM-1 expression on epithelial cells. Finally, we demonstrate that rhinovirus infection induced increased production of IL-8, IL-6, and GM-CSF from epithelial cells. Production of IL-8 correlated with viral replication during the first 24 h after infection. This model should provide useful insights into the pathogenesis of rhinovirus infections.

Base Sequence↗