Jean-Silvain Lacroix

Loss of dipeptidylpeptidase IV activity in chronic rhinosinusitis contributes to the neurogenic inflammation induced by substance P in the nasal mucosa

In this study, we have found that dipeptidylpeptidase IV (DPPIV) plays in vivo an active role in the modulation of the inflammatory response of chronic rhinosinusitis. Human nasal mucosa expresses DPPIV‐like immunoreactivity in submucosal seromucus glands, leukocytes, and endothelial cells of blood vessels. DPPIV enzymatic activity in nasal tissue biopsies taken from patients suffering from chronic rhinosinusitis was correlated inversely with the density of inflammatory cells in the nasal mucosa, and the DPPIV activity rose when chronic rhinosinusitis was treated. By using a pig animal model, we have shown that the intranasal administration of recombinant DPPIV decreased the vasodilatation induced by exogenous substance P (SP), a proinflammatory peptide released by sensory nerves. In contrast, an inhibitor of DPPIV enhanced the vasodilatatory effect at low doses of SP. SP5–11 was 100‐ to 1000‐fold less potent than SP as a vasodilator of the nasal mucosa. The vasodilatatory effect of SP was abolished by a NK1 receptor antagonist. In conclusion, these results suggest a new pathophysiological pathway for rhinitis based on clinical observations in humans, indicating the involvement of an enzyme to modulate non‐adrenergic and non‐cholinergicnon‐cholinergic substrate that occurred during nasal dysfunctions.

N-acetylcysteine inhibits Na+ absorption across human nasal epithelial cells

N‐acetylcysteine (NAC) is a widely used mucolytic drug in patients with a variety of respiratory disorders. The mechanism of action is based on rupture of the disulfide bridges of the high molecular glycoproteins present in the mucus, resulting in smaller subunits of the glycoproteins and reduced viscosity of the mucus. Because Na+ absorption regulates airway surface liquid volume and thus the efficiency of mucociliary clearance, we asked whether NAC affects the bioelectric properties of human nasal epithelial cells. A 24‐h basolateral treatment with 10 mM of NAC decreased the transepithelial potential difference and short‐circuit current (ISC) by 40%, and reduced the amiloride‐sensitive current by 50%, without affecting the transepithelial resistance. After permeabilization of the basolateral membranes of cells with amphotericin B in the presence of a mucosal‐to‐serosal Na+ gradient (135:25 mM), NAC inhibited 45% of the amiloride‐sensitive current. The Na+‐K+‐ATPase pump activity and the basolateral K+ conductance were not affected by NAC treatment. NAC did not alter total cell mRNA and protein levels of α‐epithelial Na+ channel (EnaC) subunit, but reduced abundance of α‐ENaC subunits in the apical cell membrane as quantified by biotinylation. This effect can be ascribed to the sulphydryl (SH) group of NAC, since N‐acetylserine and S‐carboxymethyl‐l‐cysteine were ineffective. Given the importance of epithelial Na+ channels in controlling the thin layer of fluid that covers the surface of the airways, the increase in the fluidity of the airway mucus following NAC treatment in vivo might be in part related to downregulation of Na+ absorption and consequently water transport. J. Cell. Physiol. 201: 106–116, 2004.

Chronic panrhinosinusitis without nasal polyps: long-term outcome after functional endoscopic sinus surgery

OBJECTIVE: The goal of this study was to evaluate the long-term outcome after functional endoscopic sinus surgery (FESS) for chronic panrhinosinusitis without nasal polyps by using symptom scoring and an endoscopic outcome evaluation. STUDY DESIGN: Seventy-seven patients with chronic panrhinosinusitis without nasal polyps (Kennedy computed tomography (CT) scan stages I to III) were followed up for at least 3 years after FESS. Preoperative evaluation included a CT scan and an immunoallergologic evaluation. Three years after FESS, all patients were interviewed and scored endoscopically. RESULTS: Ninety-two percent of the patients showed a marked global improvement after FESS. The endoscopic control showed normal findings in 54% of all ethmoidal cavities. The postoperative endoscopic score correlated significantly with the subjective satisfaction ratings (P < 0.001). The preoperative CT staging proposed by Kennedy was predictive for necessity of revision surgery in 15% of the patients. CONCLUSIONS: Our data suggest that FESS for chronic panrhinosinusitis without nasal polyps has a good long-term outcome on subjective symptoms and endoscopic findings. SIGNIFICANCE: According to this study, subjective improvement correlates significantly with the post-operative endoscopic findings in the ethmoidal cavities of patients with chronic panrhinosinusitis without polyps at a long-term follow-up.

Intranasal administration of neuropeptide Y in man: systemic absorption and functional effects.

1 Exogenous neuropeptide Y (NPY, 10 nmol, 50 nmol and 100 nmol) and its vehicle (NaCl 0.9%) were administered in a double blind, randomized and controlled manner by intranasal spray in 7 healthy volunteers. Variations of plasma NPY concentration over time were measured during 120 min. Forty min after the administration of 50 nmol and 100 nmol of exogenous NPY, plasma NPY increased from 5.5 ± 1.1 pM to 9.8 ± 2.3 pM (P < 0.05) and from 9.06 ± 5.1 pM to 20.8 ± 6.16 pM (P < 0.001), respectively. There was no significant modification of the mean arterial blood pressure and no subjective discomfort was reported. 2 Nasal airway resistance (NAR) was measured by anterior rhinomanometry and was reduced by 25 ± 3% and 32 ± 5% after the spray of 50 nmol and 100 nmol, respectively, for about 90 min. 3 Double‐blind, randomized, placebo‐controlled and 3‐way crossover design experiments were performed in 8 healthy volunteers to evaluate the influence of intranasal pretreatment with NPY (20 nmol) and the mixed α1/α2‐adrenoceptor agonist oxymetazoline (20 nmol) on the functional effects of subsequent local irritation evoked by capsaicin (3.3 × 10−4 mol). Subjective evaluation of NAR and local intensity of discomfort were evaluated by means of a visual analogue scale. Nasal secretions were collected and objective NAR was recorded by rhinomanometry. 4 Subjective NAR, nasal secretions and rhinomanometry recordings were not modified by intranasal application of saline, NPY or oxymetazoline. Subjective nasal obstruction, local discomfort, nasal secretions and NAR increase evoked by capsaicin were markedly reduced by NPY pretreatment (P < 0.05) when compared to saline or oxymetazoline. 5 It is concluded that intranasal application of exogenous NPY has very low systemic absorption but induced long lasting nasal vasoconstriction without cardiovascular effects. Pretreatment of the nasal mucosa with exogenous NPY reduces both secretagogue and vasodilator responses to subsequent application of capsaicin.

CGRP 27-37 analogues with high affinity to the CGRP1 receptor show antagonistic properties in a rat blood flow assay

CGRP Y0-28-37 is known as a selective CGRP1 receptor antagonist. We succeeded in optimising the CGRP1 receptor affinity of this fragment by multiple amino acid replacement. The analogues [p34, F35]CGRP 27-37 and [D31, p34, F35]CGRP 27-37 exhibit a 100-fold increased affinity compared to the unmodified segment. Receptor binding studies were performed with human neuroblastoma cells SK-N-MC, which selectively express the hCGRP1 receptor. Blood flow, which is increased by exogenous CGRP, was measured in the right femoral artery. Preincubation of the rats with [p34, F35]CGRP 27-37 and [D31, p34, F35]CGRP 27-37 led to a significant decrease in CGRP induced increase in vascular conductance indicating the antagonistic properties of these compounds. Interestingly, an exchange of the amino acid Asn31 to Asp31 in [p34, F35]CGRP 27-37 shortened the period of the antagonistic effect significantly, suggestive of a different rate of metabolism for the two ligands. Secondary structure investigations obtained by circular dichroism measurements revealed that an increase in ordered structure correlates with high binding affinity.

Src Signaling Links Mediators of Inflammation to Cx43 Gap Junction Channels in Primary and Transformed CFTR-Expressing Airway Cells

Dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) is associated with recurrent pulmonary infections and inflammation. We previously reported that tumor necrosis factor (TNF)-α decreases gap junction connectivity in cell lines derived from the airway epithelium of non-cystic fibrosis (non-CF) subjects, a mechanism that was defective in cells derived from CF patients, and identified the tyrosine kinase c-Src as a possible bridge between TNF-α and Cx43. To examine whether this modulation also takes place in primary epithelial cells, the functional expression of Cx43 was studied in non-CF and CF airway cells, obtained from surgical polypectomies and turbinectomies, which were grown either on culture dishes or permeable filters. Expression of Cx43 was detected by immunofluorescence on cells grown under both culture conditions. Non-CF and CF airway cells also showed intercellular diffusion of Lucifer Yellow. Dye coupling was rapidly abolished in non-CF cells in the presence of TNF-α, lipopolysaccharide and lysophosphatidic acid, and could be prevented by tyrphostin47, an inhibitor of Src tyrosine kinases. This down-regulation, however, was not detected in CF airway cells. These data indicate that CFTR dysfunction is associated with altered Src signaling, resulting in the persistence of gap junction connectivity in primary and transformed CF airway cells.

Vascular control of the pig nasal mucosa : distribution and effect of somatostatin in relation to noradrenaline and neuropeptide Y

By means of immunohistochemistry and radioimmunoassay (RIA), we have investigated the possible occurrence of somatostatin (SOM)-like immunoreactivity (-LI) in the autonomic innervation of the pig nasal mucosa. SOM-immunoreactive (-IR) fibres were present around nasal arteries, arterioles and venous sinusoids. Double-labelling experiments revealed that SOM-LI was co-localized with the noradrenaline (NA) markers tyrosine hydroxylase and dopamine-beta-hydroxylase as well as with neuropeptide Y (NPY) in a subpopulation of neurons in the superior cervical sympathetic ganglion and in perivascular nerve terminals. Furthermore, SOM-LI was also present in perivascular fibres containing vasoactive intestinal polypeptide (VIP) and NPY of presumably parasympathetic origin. The parasympathetic fibres that were associated with glands contained peptide histidine isoleucine (PHI), VIP and NPY but not SOM, suggesting that in the nasal mucosa SOM-IR is restricted to perivascular nerves. As revealed by RIA, the content of SOM-LI in biopsies of both nasal mucosa and superior cervical sympathetic ganglion was about 12 pmol/g and the reverse phase HPLC characterisation of SOM-LI shown two separate peaks for SOM-28 and SOM-14. In thiopentone anaesthetized pigs (n = 10), local intra-arterial (i.a.) infusion of SOM (1-14) induced dose-dependent, long lasting and parallel reduction of the nasal arterial blood flow, the volume of the nasal mucosa (reflecting capacitance vessel function) and decrease of the laser Doppler flowmeter signal (reflecting superficial nasal mucosal blood flow). These functional responses were not modified after pretreatment with the alpha-adrenoceptor antagonist phenoxybenzamine (1 mg kg-1 i.a.) whereas the effects of NA were almost abolished. SOM (6.10(-6) mol, i.a.) did not influence the nasal vascular responses to single impulse stimulation of the nasal sympathetic nerve supply providing no evidence for prejunctional activity in spite of clear-cut vascular effects. It is concluded that SOM-LI is co-localized with NA and NPY in sympathetic nerves and with VIP/NPY in parasympathetic perivascular nerves of the pig nasal mucosa. Since SOM evokes vasoconstriction via non-adrenergic mechanisms, this peptide should also be considered when discussing mediator candidates for the neural regulation of the nasal vascular bed.

Postoperative/Posttraumatic Gustatory Dysfunction

Clinical taste testing in humans is far from being routinely performed in ear, nose and throat (ENT) clinics. Consequently, most reports on posttraumatic and postoperative taste disorders are case reports and mainly consist of qualitative (e.g. dysgeusia, metallic taste) taste changes after either head injury or ENT surgery. Since quantitative taste deficiencies (ageusia, hypogeusia) often go unnoticed by the patients, the real incidence of ageusia and hypogeusia after head trauma and various surgical procedures remains largely unknown. This lack of reliable clinical data is partly due to the lack of easy, reproducible and rapid clinical taste testing devices. The present chapter tries to resume the current knowledge on postoperative and posttraumatic taste disorders. Despite the sparse literature, the chapter focuses on those ENT surgical procedures where at least some prospective and systematic studies on gustatory dysfunction exist. Accordingly, taste disorders after middle ear surgery, tonsillectomy and dental interventions are largely discussed.

Effects of amphotericin B on ion transport proteins in airway epithelial cells

Topical intranasal application of the antifungal Amphotericin B (AmphoB) has been shown as an effective medical treatment of chronic rhinosinusitis. Because this antibiotic forms channels in lipid membranes, we considered the possibility that it affects the properties and/or cell surface expression of ion channels/pumps, and consequently transepithelial ion transport. Human nasal epithelial cells were exposed apically to AmphoB (50 μM) for 4 h, 5 days (4 h daily), and 4 weeks (4 h daily, 5 days weekly) and allowed to recover for 18–48 h. AmphoB significantly reduced transepithelial potential difference, short‐circuit current, and the amiloride‐sensitive current. This was not due to generalized cellular toxicity as judged from normal transepithelial resistance and mitochondrial activity, but was related to inhibitory effects of AmphoB on ion transport proteins. Thus, cells exposed to AmphoB for 4 h showed decreased apical epithelial sodium channels (ENaC) activity with no change in basolateral Na+K+‐ATPase activity and K+ conductance, and reduced amount of αENaC, α1‐Na+K+‐ATPase, and NKCC1 proteins at the cell membrane, but no change in mRNA levels. After a 5‐day treatment, there was a significant decrease in Na+K+‐ATPase activity. After a 4‐week treatment, a decrease in basolateral K+ conductance and in αENaC and α1‐Na+K+‐ATPase mRNA levels was also observed. These findings may reflect a feedback mechanism aimed to limit cellular Na+ overload and K+ depletion subsequently to formation of AmphoB pores in the cell membrane. Thus, the decreased Na+ absorption induced by AmphoB resulted from reduced cell surface expression of the ENaC, Na+K+‐ATPase pump and NKCC1 and not from direct inhibition of their activities.

Influence of TASP-V, a novel neuropeptide Y (NPY) Y2 agonist, on nasal and bronchial responses evoked by histamine in anaesthetized pigs and in humans.

In nine anaesthetized pigs we have studied the influence of intranasal or intrabronchial pretreatment with TASP‐V, a neuropeptide Y (NPY) Y2 agonist formed by the attachment of NPY 21–36 to a template‐assembled synthetic peptide (TASP), on the functional responses to subsequent intranasal or intrabronchial histamine challenge. In a parallel study, subjective and objective nasal airway resistance (NAR) increase following intranasal histamine challenge was evaluated in 11 healthy volunteers after TASP‐V or placebo pretreatment. In pigs, increase in sphenopalatine blood flow induced by histamine dihydrochloride nasal spray (0.25 mg kg−1 in 3 ml of saline) was significantly reduced by 65% (P<0.05) following intranasal pretreatment with 10 μg kg−1 of TASP‐V. Bronchoconstriction induced by histamine dihydrochloride nebulization (0.5 mg kg−1 in 3 ml of saline) was significantly attenuated by 25 and 55% following aerosolized pretreatment with TASP‐V analogue at 10 and 20 μg kg−1, respectively. In healthy volunteers, objective increase in NAR and reduction in nasal minimal cross section area (MCSA) induced by intranasal spray of histamine dihydrochloride (15 μg kg−1 in 200 μl of saline) were significantly attenuated by 50% following local pretreatment with 1.275 μg kg−1 of TASP‐V when compared with saline. It is concluded that intranasal or intrabronchial pretreatment with TASP‐V reduced nasal obstruction and bronchoconstriction evoked by histamine challenge in the pig. In healthy human volunteers, this agent attenuated NAR increase and MCSA reduction induced by intranasal application of histamine.