Secretoneurin is released into human airways by topical histamine but not capsaicin

The inferior turbinate: An autonomic organ

The inferior turbinate has well-recognized respiratory and immune functions to provide the airway with appropriate warmth, humidification, and filtration of the inspired air while sampling the environment for pathogens. Normal functioning of the inferior turbinate relies on an intact autonomic system to maintain homeostasis within the nasal cavity. The autonomic nervous system innervates the submucosal glands and the vasculature within the inferior turbinate, resulting in control of major turbinate functions: nasal secretions, nasal patency, warmth, and humidification. This review will summarize the autonomic innervations of the turbinates, both the normal and abnormal autonomic processes that contribute to the turbinate functions, and the clinical considerations regarding optimal functioning of the turbinate autonomic system.

Sensory neuropeptides are potent chemoattractants for human basophils in vitro

The sensory neuropeptides secretoneurin (SN) and substance P (SP) are involved in "neurogenic" inflammatory processes as they occur in bronchial asthma or allergic rhinitis. A possible interaction with basophils has not been reported to date. Basophils were isolated from healthy donors by magnetic cell sorting technique and migration was explored using Boyden microchemotaxis chambers. SN [10(-8)M] and SP [10(-6) to 10(-8)M] proved to be chemoattractants equally potent to FMLP [10(-8)M] or LPS [10 pg/ml]. Specific anti-SN antibodies and a trypsinization preparation of SN were used to determine the specificity of the SN effect on basophils. The preincubation of basophils with neurokinin-1 (NK-1) or -2 (NK-2) receptor antagonists revealed the SP effect to act via NK-1 receptors in basophils. In addition, we were able to show phosphodiesterases and phosphoinositide-3 kinases to be engaged in the downstream signalling pathway. Our observations reveal for the first time a link between basophils, which are engaged in allergic processes, and the neuropeptides SN and SP. Furthermore, our data might suggest phosphodiesterases or phosphoinositide-3 kinases to be new therapeutic targets for the treatment of allergic diseases such as asthma or allergic rhinitis.

[Hymenoptera venom anaphylaxis and cardiovascular disease]

Preexisting cardiovascular disease may worsen the course of anaphylaxis. This is illustrated based on the example of Hymenoptera venom allergy. Fatal sting anaphylaxis is most often observed in elderly patients. During autopsy preexisting cardiovascular disease is frequently found. Preexisting cardiovascular disease in patients with anaphylaxis may also cause lasting morbidity, e.g. cerebral or myocardial infarction. Heart medications, notably beta-blockers und ACE-inhibitors may worsen the course of anaphylactic reactions due to their pharmacologic effects. Since cardiovascular diseases are much more frequent than anaphylaxis and these medications are very effective, these drugs cannot be substituted in patients with both diseases without a careful risk analysis. Epinephrine is the drug of first choice for treatment of anaphylaxis. It may however, especially following rapid intravenous administration, cause severe arrhythmias or myocardial infarction. Adrenaline should therefore preferably be given intramuscularly, or by slow intravenous infusion.

Neural aspects of allergic rhinitis

PURPOSE OF REVIEW

Recent advances have helped to clarify the role of nerves in allergic rhinitis.

RECENT FINDINGS

Mast cell histamine release activates histamine H1 receptors on a subset of nonmyelinated Type C afferent trigeminal neurons to convey the sensation of itch. The itch nerves may be distinct from those responsible for burning pain and the dull ache of congestion. Activation of brain stem centers leads to cognition of nasal pruritus, generation of the systemic sneeze reflex and recruitment of local nasal parasympathetic reflexes. These cholinergic reflexes stimulate M3 muscarinic receptors on the submucosal glands to cause exocytosis and the thick mucous discharge of allergic rhinitis. The importance of these neural pathways is demonstrated by the benefits of antihistamines to block itch and sneeze, and anticholinergic drugs to block glandular secretion. One open question remains the role of mediators of allergic inflammation on the sensitivity and reactivity of afferent neurons and these secretory reflexes.

SUMMARY

The neurology of the nose helps to explain the sensations encountered in allergic rhinitis and opens new frontiers for drug discovery.