Impaired norepinephrine-mediated contraction of isolated nasal mucosa in guinea pigs with allergic rhinitis

Overexpression of the anaphylatoxin receptors, complement anaphylatoxin 3a receptor and complement anaphylatoxin 5a receptor, in the nasal mucosa of patients with mild and severe persistent allergic rhinitis

BACKGROUND

Although the complement anaphylatoxin peptides, complement anaphylatoxin 3a (C3a) and complement anaphylatoxin 5a (C5a), are implicated in the inflammatory process in allergic rhinitis, a direct interaction between allergic mucosa and complement receptors has not been demonstrated.

OBJECTIVE

We investigated the expressional levels and distributional patterns of the C3a receptor (C3aR) and C5a receptor (C5aR) in normal, mild, and severe persistent allergic nasal mucosa.

METHODS

Immunohistochemistry and Western blotting using C3aR and C5aR antibodies were applied to normal nasal, mild, and severe persistent allergic nasal mucosa.

RESULTS

Complement anaphylatoxin 5a receptor was detected in the inflammatory cells of normal and allergic nasal mucosa, and its expression level was significantly higher in allergic nasal mucosa than normal nasal mucosa. C3aR in normal and allergic nasal mucosa was commonly expressed in nonmyeloid cells such as epithelial cells, submucosal glands, and nerve fibers. In addition, C3aR was expressed in the endothelium of cavernous sinuses and the surrounding perivascular muscle layer in severe persistent allergic nasal mucosa, but not in normal and mild allergic nasal mucosa. Western blotting demonstrated that the expression level of C3aR was significantly increased in severe persistent allergic nasal mucosa compared with normal and mild nasal mucosa.

CONCLUSION

On the basis of the location of C3aR and C5aR, C5aR may play a role in activation of inflammatory cells, whereas C3aR may mediate mucus secretion and mucosal swelling in allergic nasal mucosa, especially severe persistent allergic nasal mucosa.

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.

Regional differences in vascular responsiveness of nasal mucosae isolated from naive guinea pigs

OBJECTIVE

In the present study, the contractile response to norepinephrine (NE) and relaxing response to histamine and leukotriene D(4) (LTD(4)) were compared among the nasal mucosae of septa (S) and lateral (L) and medial turbinates (M) isolated from naive male Hartley guinea pigs.

METHODS

The isometrical tension of the isolated nasal mucosae of the above regions was measured at a resting tension of 0.5 g by using a standard organ-bath technique.

RESULTS

In each mucosal strip, NE induced a contraction in a concentration-dependent manner. A significant difference in efficacy (maximal response) of NE was found (L>M>S). In mucosal strips precontracted with NE (3x10(-5)M), both histamine and LTD(4) induced relaxing responses. The efficacy of histamine in S was significantly greater than those in L and M. The potency order of LTD(4) was L>M>S; a significant difference was observed between L and S.

CONCLUSION

In conclusion, the present study demonstrated a distinct regional difference in the response to contractile and relaxant agonists of isolated nasal mucosae of guinea pigs.