Richard D. Dey

Climate change and respiratory disease: European Respiratory Society position statement

Climate change will affect individuals with pre-existing respiratory disease, but the extent of the effect remains unclear. The present position statement was developed on behalf of the European Respiratory Society in order to identify areas of concern arising from climate change for individuals with respiratory disease, healthcare workers in the respiratory sector and policy makers. The statement was developed following a 2-day workshop held in Leuven (Belgium) in March 2008. Key areas of concern for the respiratory community arising from climate change are discussed and recommendations made to address gaps in knowledge. The most important recommendation was the development of more accurate predictive models for predicting the impact of climate change on respiratory health. Respiratory healthcare workers also have an advocatory role in persuading governments and the European Union to maintain awareness and appropriate actions with respect to climate change, and these areas are also discussed in the position statement.

COMPARISON OF INDUCIBLE NITRIC OXIDE SYNTHASE GENE EXPRESSION AND LUNG INFLAMMATION FOLLOWING INTRATRACHEAL INSTILLATION OF SILICA, COAL, CARBONYL IRON, OR TITANIUM DIOXIDE IN RATS

The pulmonary toxicity of the respirable dusts silica, coal, carbonyl iron, and titanium dioxide on alveolar macrophage (AM) and neutrophil (PMN) inducible nitric oxide synthase (iNOS) gene expression and nitric oxide (NO) production was investigated. Rats were intratracheally instilled with 5 mg/100 g body weight of silica, coal, carbonyl iron, or titanium dioxide. The dust particles averaged less than 5 microns in diameter. Bronchoalveolar lavage was performed 24 h later. Bronchoalveolar lavage cell (BALC) differentials, iNOS gene expression and NO production by BALC (measured indirectly as NO-dependent chemiluminescence), and lavageable lung protein levels were measured. Analyzed on an equal mass basis, silica, coal, and titanium dioxide dusts increased the production of iNOS-dependent NO by AM. Silica and titanium dioxide both increased the levels of iNOS mRNA while carbonyl iron and coal did not. Each dust caused an increase in PMN, indicating an inflammatory response. Carbonyl iron and titanium dioxide decreased the numbers of AM. Levels of acellular lavageable lung protein were increased by silica, carbonyl iron, and titanium dioxide. When exposure was normalized for an equal number of particles, the pneumotoxic dusts, silica and coal, caused more inflammation and NO production than the nuisance dusts, carbonyl iron and titanium dioxide. Therefore, it appears that particle number is a more appropriate metric of exposure than mass when comparing the relative pathogenicity of dusts of different sizes. Furthermore, since the potency of these dusts (on a particle number basis) to increase iNOS gene expression reflects their inflammatory and pathogenic potential, it is proposed that NO may contribute to the early inflammatory damage observed in the lung following dust exposure.

Identification and neuropeptide content of trigeminal neurons innervating the rat nasal epithelium

Trigeminal ganglia provides sensory innervation to the rat nasal cavity. The purpose of this study was to identify the location and characterize the neuropeptide content of trigeminal neurons that project specifically to the rat nasal epithelium. The right nasal cavity was instilled with 4 microliters of rhodamine-labelled latex microspheres. Seven, 10 or 14 days after tracer instillation, both trigeminal ganglia were removed and prepared for substance P and calcitonin gene-related peptide immunocyto-chemistry. neurons labelled with microspheres were located in the trigeminal ganglia at the division of the ophthalmic and maxillary nerves and were only found on the side ipsilateral to the instillation. The percentage of labelled cell body profiles in the right trigeminal ganglia averaged 1.61 +/- .04% at seven days. 1.54 +/- .01% at 10 days, and 1.65 +/- .02% at 14 days after instillation. These values were not statistically different, but the fluorescence intensity in labelled neurons was increased after 14 days. The right trigeminal ganglia contained a mean of 166 +/- 13.81 labelled cell body profiles representing 1.60 +/- .09% of the total. Of the labelled profiles, 81.6 +/- 3.27% were immunoreactive for substance P and 35.2 +/- 4.00% for calcitonin gene-related peptide. Sections of nasal mucosa showed that the microspheres were localized only in the epithelial layer and did not enter the lamina propria indicating that the microsphere transport was confined to nerve fibres present in the epithelial layer. These studies have identified specific neurons in the trigeminal ganglia that project to the nasal epithelium. Most of the neurons retrogradely labelled from the nasal cavity contained substance P but some contained calcitonin gene-related peptide, suggesting that the nasal epithelium is predominantly targeted by substance P-containing neurons.

Colocalization of vasoactive intestinal peptide and nitric oxide synthase in neurons of the ferret trachea

Neurally-mediated relaxation of smooth muscle in human, guinea-pig, cat, and pig airways is largely attributed to a nonadrenergic, noncholinergic mechanism. While the specific transmitter(s) of this relaxant system have not been conclusively identified, vasoactive intestinal peptide and nitric oxide have emerged as likely mediators in airway smooth muscle. Both vasoactive intestinal peptide and nitric oxide relax guinea-pig, pig and human smooth muscle. Vasoactive intestinal peptide is present in nerve fibers associated with airway smooth muscle in humans and several animal species. In guinea-pigs, vasoactive intestinal peptide is released during electrical field stimulation of airway strips and the release correlates with the nonadrenergic relaxation. This relaxation is markedly reduced after incubation of tracheal tissue with a specific VIP antibody and by immunization to vasoactive intestinal peptide. Similarly, nonadrenergic relaxations induced by electrical field stimulation are reduced in human, pig, guinea-pig and bovine airways by nitric oxide synthesis inhibitors. Vasoactive intestinal peptide is present in nerve cell bodies of airway ganglia, suggesting that these nerves in airway smooth muscle originate from intrinsic neurons. It is stored in dense-core vesicles of nerve terminals near airway smooth muscle, suggesting that preformed vasoactive intestinal peptide is released by fusion of the vesicles with the cell membrane of the nerve terminal. Nitric oxide is probably generated by a novel mechanism involving de novo synthesis at the nerve terminal during neural activation by the action of the enzyme nitric oxide synthase.(ABSTRACT TRUNCATED AT 250 WORDS)

Co-localization of vasoactive intestinal peptide- and substance P-containing nerves in cat bronchi

The occurrence of vasoactive intestinal peptide (VIP) and substance P in nerve fibers within the lung is well established, and both VIP- and substance P-containing nerve fibers are known to supply pulmonary vascular and bronchial smooth muscle and submucosal glands. In the present study, we have investigated the co-localization of these two peptides in cat lung. The co-localization procedure follows a standard immunocytochemical protocol except that the primary and labeled secondary antisera each contain a combination of two antisera allowing the simultaneous detection of two antigens in a single tissue section. Using fluorescence microscopy, VIP- and substance P-containing nerve fibers were co-localized in bronchial smooth muscle, in the walls of pulmonary and bronchial arteries, and around submucosal glands. VIP and substance P were also co-localized in nerve cell bodies that comprised the intrinsic airway ganglia. Substance P-containing nerve fibers were observed within the bronchial epithelium, but VIP was not present at this location. The co-localization of VIP and substance P in the same nerve fibers suggests that airway and pulmonary vascular function may be partially regulated by the simultaneous or sequential release of VIP and substance P from the same nerve fibers. The results also suggest that, in addition to extrinsic nerve fibers that contain substance P, the airways of cats are supplied by substance P-containing nerve fibers that originate from intrinsic nerve cell bodies.

Rat alveolar macrophages express preprotachykinin gene-I mRNA-encoding tachykinins

Although the tachykinins substance P (SP) and neurokinin A have been largely localized to neurons, eosinophils have also been shown to express these peptides. Our aim was to determine whether rat alveolar macrophages (AM) express preprotachykinin gene-I (PPT-I) mRNA that encodes these tachykinins and to examine expression during inflammation. PPT-I mRNA was detected by reverse transcription (RT)-polymerase chain reaction (PCR) in AM and brain (control) but not in peritoneal macrophages. Northern analysis showed that PPT-I mRNA was induced two- to fourfold by in vivo treatment of rats with intratracheal lipopolysaccharide (LPS) and in vitro after 4 h of exposure to LPS. This increase was inhibited by dexamethasone. In situ RT-PCR and immunocytochemistry further confirmed that AM express PPT-I mRNA and SP-like immunoreactivity, respectively, which was enhanced by LPS treatment. A 1.3-kb transcript consistent with PPT-I mRNA was detected by Northern analysis of bronchoalveolar lavage neutrophils. Therefore, rat AM express PPT-I mRNA that is upregulated in AM by LPS and is attenuated by dexamethasone. PPT-I mRNA was also detected in lung neutrophils.

Prenatal and Early, but Not Late, Postnatal Exposure of Mice to Sidestream Tobacco Smoke Increases Airway Hyperresponsiveness Later in Life

Background Cigarette smoke exposure in utero and during early postnatal development increases the incidence of asthma and airway hyperresponsiveness (AHR) later in life, suggesting that a possible critical period of developmental sensitivity exists in the prenatal and early postnatal periods. Objective We investigated mechanisms of susceptibility during critical developmental periods to sidestream smoke (SS) exposure and evaluated the possible effects of SS on neural responses. Methods We exposed three different age groups of mice to either SS or filtered air (FA) for 10 consecutive days beginning on gestation day (GD) 7 by maternal exposure or beginning on postnatal day (PND) 2 or PND21 by direct inhalation. Lung function, airway substance P (SP) innervation, and nerve growth factor (NGF) levels in broncho alveolar lavage fluid were measured after a single SS exposure on PND59. Results Methacholine (MCh) dose response for lung resistance (RL) was significantly elevated, and dynamic pulmonary compliance (Cdyn) was significantly decreased, in the GD7 and PND2 SS exposure groups compared with the FA groups after SS exposure on PND59. At the same time points, the percent area of SP nerve fibers in tracheal smooth muscle and the levels of NGF were significantly elevated. MCh dose–response curves for RL and Cdyn, SP nerve fiber density, and the level of NGF were not significantly changed in the PND21 exposure group after SS exposure on PND59. Conclusions These results suggest that a critical period of susceptibility to SS exposure exists in the prenatal and early postnatal period of development in mice that results in increased SP innervation, increased NGF levels in the airway, and enhanced MCh AHR later in life.

Glutamate toxicity in the lung and neuronal cells: prevention or attenuation by VIP and PACAP.

Abstract: VIP, which has been demonstrated to reduce or prevent oxidant injury in the lungs and other organs, is shown here to protect against excitotoxic injury of the lung and excitotoxic death of cortical neuronal cells in primary culture. Glutamate killing of neuron‐like PC‐12 cells, attributable to oxidant stress rather that to excitotoxicity, is also reduced or prevented by VIP and by the closely related peptide PACAP. The exact mechanisms of this protection remain to be determined, but appear to include antioxidant and anti‐apoptotic actions, and suppression of glutamate‐induced upregulation of its own receptor. Both VIP and PACAP offer the promise of novel and nontoxic means of defending against NMDA and glutamate toxicity.

Enhanced Pulmonary Response to the Inhalation of Freshly Fractured Silica as Compared with Aged Dust Exposure

Abstract We have reported previously that grinding crystalline silica generates radicals on its cleavage planes and that this fresh dust is more cytotoxic in vitro than aged silica. The objective of the present study was to determine if freshly fractured silica was also more toxic and inflammatory in vivo than aged silica of the same composition and particle size. Fresh α-quartz was generated using a jet mill, while aged dust was milled and then stored for 2 months before use. Analysis of surface radicals by electron spin resonance spectroscopy verified the enhanced surface activity of this fresh silica compared with aged dust. Male Fischer 344 rats were exposed to fresh or aged α-quartz by inhalation (20 mg/m3, 5 hours per day, 5 days per week for 2 weeks) and pulmonary responses were determined 1 to 3 days after exposure. Exposure to aged silica resulted in an increase in total cells, red blood cells, lymphocytes, and granulocytes harvested by bronchoalveolar lavage, and in elevated acellular lavage pro...

Innervation of tracheal epithelium and smooth muscle by neurons in airway ganglia

The neurochemical profiles of neurons in ferret tracheal ganglia has been characterized, but their projections to smooth muscle and epithelium in ferret trachea has not been examined. The purpose of this study is to determine the location of cell bodies that project VIP‐, SP‐, and NPY‐containing fibers to the ferret tracheal smooth muscle and epithelium. Segments of ferret trachea were cultured for 0, 1, 3, or 7 days, some in the presence of 3 μm capsaicin. VIP, SP, or NPY nerve fiber density was measured using morphometric procedures. A retrograde tracer, rhodamine‐labeled microspheres, identified neurons projecting to the epithelium. The density of SP fibers in the epithelium was reduced after culture, but VIP innervation was not different. In tracheal smooth muscle, the density of VIP‐ and SP‐IR fibers was not different during the culture period, but NPY fiber density was reduced at all culture times. Capsaicin treatment did not affect nerve fiber density in the tracheal smooth muscle but produced a significant reduction in the density of epithelial VIP‐ and SP‐IR nerve fibers after 1 day. Rhodamine‐labeled microspheres were identified in VIP‐containing nerve cell bodies of the ferret tracheal plexus. VIP innervation to the airway epithelium in ferret originates both from cell bodies in airway ganglia and cell bodies in sensory ganglia. The pathway from airway ganglia suggest the existence of a local reflex mechanisms initiated by epithelial irritation. Anat Rec 254:166–172, 1999.