Sympathetic and parasympathetic interaction in vascular and secretory control of the nasal mucosa in anaesthetized dogs

Further Understanding of Neuro-Immune Interactions in Allergy: Implications in Pathophysiology and Role in Disease Progression

The complicated interaction between the central and the autonomic (sympathetic, parasympathetic, and enteric) nervous systems on the one hand and the immune system and its components, on the other hand, seems to substantially contribute to allergy pathophysiology, uncovering an under-recognized association that could have diagnostic and therapeutic potentials. Neurons connect directly with and regulate the function of many immune cells, including mast cells, the cells that have a leading role in allergic disorders. Proinflammatory mediators such as cytokines, neurotrophins, chemokines, and neuropeptides are released by immune cells, which stimulate sensory neurons. The release of neurotransmitters and neuropeptides caused by the activation of these neurons directly impacts the functional activity of immune cells and vice versa, playing a decisive role in this communication. Successful application of Pavlovian conditioning in allergic disorders supports the existence of a psychoneuroimmunological interplay in classical allergic hypersensitivity reactions. Activation of neuronal homeostatic reflexes, like sneezing in allergic rhinitis, coughing in allergic asthma, and vomiting in food allergy, offers additional evidence of a neuroimmunological interaction that aims to maintain homeostasis. Dysregulation of this interaction may cause overstimulation of the immune system that will produce profound symptoms and exaggerated hemodynamic responses that will lead to severe allergic pathophysiological events, including anaphylaxis. In this article, we have systematically reviewed and discussed the evidence regarding the role of the neuro-immune interactions in common allergic clinical modalities like allergic rhinitis, chronic rhinosinusitis, allergic asthma, food allergy, atopic dermatitis, and urticaria. It is essential to understand unknown – to most of the immunology and allergy experts – neurological networks that not only physiologically cooperate with the immune system to regulate homeostasis but also pathogenetically interact with more or less known immunological pathways, contribute to what is known as neuroimmunological inflammation, and shift homeostasis to instability and disease clinical expression. This understanding will provide recognition of new allergic phenotypes/endotypes and directions to focus on specialized treatments, as the era of personalized patient-centered medicine, is hastening apace.

Changes of T-helper type 1/2 cell balance by anticholinergic treatment in allergic mice

BACKGROUND

Anticholinergic drugs or vidian neurectomy can alleviate the symptoms of allergic rhinitis.

OBJECTIVE

To show that inhibition of the cholinergic nerve influences the balance of T-helper type 1 and 2 cells in allergic rhinitis mice.

METHODS

Twenty-four mice were randomly allocated to 1 of 4 groups: control, model, model with ipratropium bromide treatment, and model with 6-hydroxydopamine treatment. Allergic model-treated mice were sensitized with ovalbumin. Evaluation of allergic symptoms was recorded according to a symptom score. Ovalbumin serum IgE was measured by enzyme-linked immunosorbent assay. Expression of interleukin-4, interferon-γ, forkhead box P3, substance P, and vasoactive intestinal peptides was detected by immunohistochemistry and imaging analysis.

RESULTS

Symptoms in allergic mice were significantly alleviated by ipratropium bromide. Ovalbumin serum IgE and eosinophils of nasal mucosa were significantly decreased. Interleukin-4 expression level was significantly higher in the allergic model group than in the control group and significantly decreased by ipratropium bromide (P < .05). In contrast, the expression of forkhead box P3 was lower in the allergic model group than in the control group and increased with treatment by ipratropium bromide (P < .05). Conversely, interferon-γ expression was not changed by anticholinergic treatment in the nasal mucosa of allergic mice. Expression of substance P and vasoactive intestinal peptide was significantly increased in allergic mice and decreased by ipratropium bromide. Sympathetic denervation did not change the expression of interleukin-4, interferon-γ, forkhead box P3, substance P, and vasoactive intestinal peptide.

CONCLUSION

inhibition of the cholinergic nerve not only alleviated symptoms of allergic rhinitis by inhibiting the impulse of the parasympathetic nerve but also modulated the T-helper type 2-predominant immune reaction, expression of neuropeptides, and related inflammation factors.

Neurochemical classification and projection targets of CART peptide immunoreactive neurons in sensory and parasympathetic ganglia of the head

The aims of the present study were to determine if there is neuronal Cocaine and amphetamine regulated transcripts (CART) peptide expression (CART+) in parasympathetic (sphenopalatine (SPG); otic (OG)) and sensory (trigeminal (TG)) ganglia of the head and to examine the neurochemical phenotype (calcitonin gene-related peptide (CGRP), neurofilament 200 (NF200), isolectin B4 (IB4) binding, vasoactive intestinal peptide (VIP), neuropeptide Y (NPY) and enkephalin (ENK) immunoreactivity) and projection targets (lacrimal gland (LG), parotid gland (PG), nasal mucosa (NM), temporomandibular joint (TMJ), middle cerebral artery (MCA) and middle meningeal artery (MMA)) of CART expressing neurons in these ganglia. We found CART+ neurons in both the SPG (5.25±0.07%) and OG (4.32±0.66). A significant proportion of these CART+ neurons contained VIP, NPY or ENK (34%, 26% and 11%, respectively). SPG neurons retrogradely labelled from the lacrimal gland (29%) were CART+, but we were unable to demonstrate CART+ labelling in any of the SPG or OG neurons labelled from other targets. This supports a role for CART peptides in lacrimation or regulation of vascular tone in the lacrimal gland, but not in salivation or nasal congestion. CART+ neurons were also present in the trigeminal ganglion (1.26±0.38%), where their size distribution was confined almost completely to neurons smaller than 800 μm2 (mean=410 μm2; 98%<800 μm2), and were almost always CGRP+, but did not bind IB4. This is consistent with a role for CART peptides in trigeminal pain. However, there were few CART+ neurons amongst any of the trigeminal neurons retrogradely labelled from the targets we investigated and thus we cannot comment on the tissue type where such pain may have originated. Our study shows that some specialization of CART peptide expression (based on neurochemical phenotype and target projection) is evident in sensory and parasympathetic ganglia of the head.

Unilateral rhinorrhea after translabyrinthine surgery due to parasympathetic hypersensitive syndrome: differentiation from cerebrospinal fluid leakage

INTRODUCTION

Unilateral rhinorrhea after translabyrinthine surgery for vestibular or facial schwannoma usually suggests cerebrospinal fluid (CSF) leakage and requires specific measures, including revision surgery.

OBJECTIVE

To draw attention to the possibility of postoperative unilateral rhinorrhea with concomitant hyperlacrimation and hypersialorrhea without a CSF origin and reflecting more a neuroplastic phenomenon.

STUDY DESIGN

Retrospective study in a tertiary care center university clinic.

PATIENTS AND INTERVENTION

For 1 case of intratemporal facial schwannoma and 2 cases of vestibular schwannoma, surgery was by a translabyrinthine approach with sacrifice of the facial nerve and hypoglossofacial anastomosis in the first case. Postoperative unilateral hydrorhinorrhea associated with various degrees of lacrimation and/or salivary hypersecretion occurred mainly during exercise or under stressful situations.

CONCLUSION

With unilateral rhinorrhea after translabyrinthine surgery for vestibular or facial schwannoma, concomitant symptoms such as lacrimation or hypersialorrhea may not be explained by CSF leakage through the eustachian tube. Misinterpretation may lead to detrimental revision surgery. The pathophysiogenetic mechanism suggests a neuroplastic phenomenon involving a denervation hypersensitivity reaction of the autonomous system. A simple diagnostic test with a nasal anticholinergic agent may be beneficial.

Age determines vascular reactivity as measured by optical rhinometry

BACKGROUND

Endonasal blood volume depends on autonomous nervous system activation and ultimately vascular reactivity. It can be measured by optical rhinometry, a simple- to-use, subject-compliance independent method. We investigated endonasal perfusion following postural change to determine predictors of vascular response.

MATERIALS AND METHODS

Optical rhinometry was performed in 52 healthy subjects (25 women) with an age range of 21-80 years. Subjects were placed in supine position after 5 min of standing. Optical density (OD) as marker of endonasal blood volume was continuously measured for 30 min after postural change. In addition to age, data on other risk factors for impaired vascular reactivity, such as gender, smoking, level of physical activity, resting heart rate and blood pressure were obtained. To evaluate raw-data curves, integrals over defined time-periods were calculated.

RESULTS

The OD initially increased following the intervention (t(max) at 207 +/- 12 s, mean +/- SEM). Thereafter, a gradual return to baseline levels was observed in young but not in elderly subjects. In multivariate models, age was the most influential parameter for vascular response followed by body mass index. The defined integrals as indicators of curve structure were all significantly influenced by age (P < 0.01 for each interval). Other measured risk factors had no effect on curve characteristics.

CONCLUSIONS

Age is an important predictor of endonasal perfusion. Evaluation of optical rhinometry needs to take age-dependency of results into account. Studies in patients with cardiovascular disease are needed to show if optical rhinometry can provide information about vascular responsiveness as a predictor of cardiovascular morbidity.

Inhibitory effects of excess sympathetic activity on parasympathetic vasodilation in the rat masseter muscle

The present study was designed to examine the effect of sympathetic tonic activity on parasympathetic vasodilation evoked by the trigeminal-mediated reflex in the masseter muscle in urethane-anesthetized rats. Sectioning of the superior cervical sympathetic trunk (CST) ipsilaterally increased the basal level of blood flow in the masseter muscle (MBF). Electrical stimulation of the peripheral cut end of the CST for 2 min using 2-ms pulses ipsilaterally decreased in a dependent manner the intensity (0.5-10 V) and frequency (0.1-5 Hz) of the MBF. The CST stimulation for 2 min at <0.5 Hz with 5 V using 2-ms pulses seems to be comparable with the spontaneous activity in the CST fibers innervating the masseter vasculature, because this stimulation restored the basal level of the MBF to the presectioned values. Parasympathetic vasodilation evoked by electrical stimulation of the central cut end of the lingual nerve in the masseter muscle was markedly reduced by CST stimulation for 2 min with 5 V using 2-ms pulses in a frequency-dependent manner (0.5-5 Hz). Intravenous administration of phentolamine significantly reduced the vasoconstriction induced by CST stimulation in a dose-dependent manner (0.1-1 mg/kg), but pretreatment with either phentolamine or propranolol failed to affect the sympathetic inhibition of the parasympathetic vasodilation. Our results suggest that 1) excess sympathetic activity inhibits parasympathetic vasodilation in the masseter muscle, and 2) alpha- and beta-adrenoceptors do not contribute to sympathetic inhibition of parasympathetic vasodilation, and thus some other types of receptors must be involved in this response.

A comprehensive model of allergic rhinitis in guinea pigs

INTRODUCTION

The economic and social impact of allergic rhinitis is substantial. The effectiveness of currently available medications is limited and therefore investigations for more effective drugs is essential. This study was intended to establish a model of allergic rhinitis in guinea pigs that can be utilized for further investigation of new drugs.

METHODS

Male Dunkin Hartley guinea pigs were sensitized intranasally to, and challenged with, ovalbumin. Sneezing (SN) and nose rubbing (NR) response to allergen challenge were observed on day 21 post-initiation of sensitization in conscious guinea pigs. Nasal blockade (NB), leukocyte infiltration, and lung inflation pressure (LIP) were assessed in the same guinea pigs 23-28 days post-initiation of sensitization. A ventilator/flow method was used to measure NB and LIP. Leukocyte infiltration into nasal lavage fluid 60 min after challenge in the same animals was recorded as total and differential cell counts.

RESULTS

Sensitized guinea pigs produced acute allergic responses after allergen challenge. This was characterized by increases in SN, NR, NB, and eosinophil infiltration. In addition, intranasal allergen challenge did not change lung inflation pressure.

DISCUSSION

Allergen-induced rhinitis in guinea pigs resembles that in humans. The model reported in this study can be used to reflect the effectiveness of drugs currently used to treat allergic rhinitis and to investigate new potential drugs for the treatment of allergic rhinitis.

Permeability issues in nasal drug delivery

The nasal route is one of the most permeable and highly vascularized site for drug administration ensuring rapid absorption and onset of therapeutic action. It has been potentially explored as an alternative route for drugs with poor bioavailability and for the delivery of biosensitive and high molecular weight (MW) compounds such as proteins, peptides, steroids, vaccines, and so on. This review discusses the major factors affecting the permeability of drugs or biomolecules through the nasal mucosa, including biological, formulation and device-related factors. This information could potentially help to achieve desired plasma concentrations of drugs without compromising or altering the normal physiology of the nasal cavity.

Neurology of allergic inflammation and rhinitis

Afferent nerves, derived from the trigeminal ganglion, and postganglionic autonomic nerves, derived from sympathetic and parasympathetic ganglia expressing many different neurotransmitters, innervate the nose. Reflexes that serve to optimize the air-conditioning function of the nose by altering sinus blood flow, or serve to protect the nasal mucosal surface by mucus secretion, vasodilatation, and sneezing, can be initiated by a variety of stimuli, including allergen, cold air, and chemical irritation. Activation of nasal afferent nerves can also have profound effects on respiration, heart rate, blood pressure, and airway caliber (the diving response). Dysregulation of the nerves in the nose plays an integral role in the pathogenesis of allergic rhinitis. Axon reflexes can precipitate inflammatory responses in the nose, resulting in plasma extravasation and inflammatory cell recruitment, while allergic inflammation can produce neuronal hyper-responsiveness. Targeting the neuronal dysregulation in the nose may be beneficial in treating upper airway disease.

Sympathetic and parasympathetic interaction in vascular and secretory control of salivary glands in anaesthetised dogs

The present study was undertaken to examine sympathetic-parasympathetic interactions in the regulation of salivary gland function, with special reference to the possible role of the sympathetic cotransmitter neuropeptide Y (NPY). In dogs anaesthetised with pentobarbitone, electrical stimulation of the parasympathetic nerve to the submandibular gland evoked an increase in glandular blood flow and salivary secretion. Sympathetic nerve stimulation evoked a significant prolonged attenuation of vasodilator and secretory responses to subsequent parasympathetic stimulation. This attenuation was not significantly altered by alpha- and beta-adrenoceptor blockade. Systemic administration of the sympathetic cotransmitter, NPY, mimicked the effect of the sympathetic stimulation by significantly attenuating vasodilatation and salivary secretion. The NPY Y1 receptor agonist, [Leu31, Pro34]NPY and the specific NPY Y2 receptor agonist N-acetyl[Leu28, Leu31]NPY 24-36 both significantly attenuated the vasodilatation and salivary secretion evoked by stimulation of the parasympathetic nerve. The NPY Y1 receptor antagonist, GR231118 significantly antagonised the attenuation of vasodilatation caused by both sympathetic stimulation and the NPY Y1 receptor agonist. GR231118 also inhibited the pressor response of NPY. Intra-arterial injection of methacholine and stimulation of the parasympathetic nerve both caused local vasodilatation in the gland which was significantly attenuated by pretreatment with sympathetic stimulation or the NPY Y1 agonist. The NPY Y2-specific agonist did not attenuate methacholine-induced vasodilatation but did attenuate vasodilatation evoked by parasympathetic stimulation. The results indicate that NPY as a sympathetic cotransmitter may have a role in the regulation of vascular secretory function of salivary glands.

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

1. 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. 2. 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. 3. 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 microg 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 microg kg(-1), respectively. 4. In healthy volunteers, objective increase in NAR and reduction in nasal minimal cross section area (MCSA) induced by intranasal spray of histamine dihydrochloride (15 microg kg(-1) in 200 microl of saline) were significantly attenuated by 50% following local pretreatment with 1.275 microg kg(-1) of TASP-V when compared with saline. 5. 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.