Increased expression of surface activation markers on neutrophils following migration into the nasal lumen.

BACKGROUND: The sequence of events following the recruitment of a free-flowing neutrophil in the peripheral circulation, via adhesion, migration and release of mediators, to a neutrophil on the surface of the nasal epithelium is a co-ordinated process. Little is known about the state of neutrophil activation following this course of events. OBJECTIVES: To investigate the expression of surface activation markers on neutrophils, reflecting activation during their recruitment to the nose, and to see whether the inflammatory process during allergic rhinitis influences this process. METHOD: Nine healthy controls and 12 patients with grass pollen-induced intermittent allergic rhinitis were investigated during the peak of the pollen season. The expression of CD11b, CD66b and CD63 on the neutrophil cell surface, as a reflection of activation, was analysed using flow cytometry. Neutrophils were derived from peripheral blood and nasal lavage fluid. In addition, eosinophil cationic protein (ECP) and myeloperoxidase (MPO) as well as L-, P- and E-selectins in the nasal lavage fluid were analysed using RIA and ELISA, respectively. RESULTS: A marked increase in the expression of all three CD markers on the neutrophil cell surface was noticed following migration from the bloodstream to the surface of the nasal mucosa. At the peak of the grass pollen season, the MPO levels increased, reflecting an increase in the total number of nasal fluid neutrophils. In parallel, the expression of CD11b was further augmented. The expression of the CDb11b was reduced on neutrophils remaining in the circulation. In addition, the level of L-selectin was reduced on neutrophils derived from the blood during allergic inflammation. CONCLUSION: Neutrophils might become activated during their transfer from the blood to the surface of the nasal mucosa, but these changes may also be due to depletion of activated neutrophils in the blood via activated endothelial/epithelial adhesion and chemoattractant measures. The increased expression of surface activation markers during allergic rhinitis suggests roles for neutrophils in the inflammatory process.

Pituitary adenylate cyclase-activating polypeptide, effects in the human nose.

BACKGROUND: Pituitary adenylate cyclase-activating peptide (PACAP) is a neuropeptide with strong vaso- and bronchodilator capacity. There is recent evidence that PACAP decreases the release of proinflammatory cytokines and we have previously shown that PACAP inhibits neutrophil chemotaxis in vitro, but little is known about the effects of PACAP in human upper and lower airways. OBJECTIVE: To investigate the effects of PACAP in the human upper respiratory tract focusing on vasodilatation/nasal airway resistance (NAR), neutrophil recruitment, plasma extravasation and endogenous production of IL-1-related mediators. METHODS: Surgical specimens from five patients (aged 19-55 years), obtained in conjunction with nasal surgery, were used for immunohistochemical localization of PACAP in the nasal mucosa. In seven, healthy, non-allergic, non-smoking subjects (aged 19-45 years), NAR was measured with rhinomanometry. Nasal lavage was performed, before and after intranasal application of PACAP (200 microL of a 1 microm PACAP solution in each nasal cavity), with and without the addition of histamine. Cells, albumin and IL-1-related mediators were analysed in nasal lavage. In addition, the effects on pulse, blood pressure, ECG and pulmonary function were evaluated. RESULTS: In the nasal mucosa, PACAP-like immunoreactive nerve fibres were seen close to blood vessels and seromucous glands. Application of PACAP in the nasal cavity increased NAR and augmented the increase in NAR induced by histamine. In addition, PACAP inhibited histamine-induced recruitment of neutrophils, increased plasma leakage and reduced the level of IL-1RA (an endogenously produced IL-1 receptor antagonist) in nasal lavage. Cardiovascular and pulmonary parameters were not affected. CONCLUSION: These results imply that PACAP is an important endogenous mediator in human upper airways, with a potential role as a regulator of vascular smooth muscle, secretion, plasma extravasation, neutrophil recruitment and cytokine activity.

The induction of carbon monoxide-mediated airway relaxation by PACAP 38 in isolated guinea pig airways.

Pituitary adenylate cyclase--activating peptide 38 (PACAP 38) displays several biologic activities relevant to obstructive airway disease. Carbon monoxide (CO) has recently emerged as a potent, endogenously produced mediator of bronchodilation. In this study, we have analyzed the occurrence of PACAP 38 and the corresponding occurrence of heme oxygenase (HO), the rate-limiting enzyme for CO production, in guinea pig trachea, using immunocytochemistry. We have also investigated whether the dilatory effects of PACAP 38 are dependent on CO, using an in vitro setup for tracheal studies. A moderate supply of PACAP-like immunoreactive nerve fibers was seen in association with tracheal smooth muscle. HO-like immunoreactivity was observed in the respiratory epithelium and in association with smooth muscle bundles. PACAP 38 induced a concentration-dependent relaxation of precontracted tracheal segments. This dilation was nearly abolished after pretreatment with zincprotoporphyrine, an inhibitor of heme oxygenase. The same effect was accomplished with Rp-8Br-cyclicGMPS, an inhibitor of cyclicGMP, whereas the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine had no effect on the PACAP 38--induced dilation. The presented data suggest that PACAP 38 can induce bronchodilation by means of a CO-dependent, cyclicGMP-related mechanism, thereby providing a link between neurotransmission and local CO release in the airway smooth muscle.

Pituitary adenylate cyclase-activating peptide inhibits neutrophil chemotaxis.

Pituitary adenylate cyclase-activating peptide 38 (PACAP 38) is a neuropeptide that displays several biological effects of interest in the context of airway diseases such as asthma and chronic obstructive pulmonary disease. These effects include inhibition of airway and vascular smooth muscle tone as well as modulation of inflammatory cell activity. However, little is known about the effect of PACAP on granulocytes. The present study was designed to investigate if PACAP and the closely related peptide vasoactive intestinal peptide (VIP) could affect neutrophil migration. A standard 48 well chemotaxis chamber was used to assess the effects of PACAP on N-Formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP)-induced neutrophil chemotaxis and spontaneous random migration. PACAP 38 and VIP inhibited fMLP-induced human neutrophil chemotaxis. Furthermore, both peptides also exhibited a dose-related trend toward inhibiting the spontaneous, unstimulated migration of neutrophils. Since enhanced cell migration in cell chamber systems is reported to correlate with increased invasive properties in vivo, the presented inhibitory effects of PACAP 38 on neutrophil chemotaxis, supports the idea of an anti-inflammatory role for PACAP. This together with the well documented bronchodilatory capacity of PACAP might indicate a role for PACAP-agonists in future treatment of asthma and other inflammatory airway diseases.

Pituitary adenylate cyclase-activating peptide 38 a potent endogenously produced dilator of human airways.

Pituitary adenylate cyclase-activating peptide (PACAP) 38 displays several biological activities relevant to obstructive airway disease. In this study, the occurrence of PACAP 38 in human small bronchi and corresponding pulmonary arteries was analysed immunocytochemically. The dilatory effects of this peptide on the same structures were also studied in vitro. A moderate number of PACAP-like immunoreactive nerve fibres was seen in association with bronchial and vascular smooth muscle and around seromucous glands. PACAP 38 caused a concentration-dependent relaxation of precontracted bronchial and pulmonary arterial segments. The maximal relaxation was more pronounced in the airways than in the arteries, whereas the potency in both was identical. PACAP 38 caused relaxation of all segments tested (nine patients), whereas vasoactive intestinal polypeptide (VIP) failed to cause relaxation of bronchial segments from six of nine patients. Both PACAP and VIP dilated all pulmonary arterial segments tested. In conclusion, pituitary adenylate cyclase-activating peptide 38 is a potent dilator of human bronchi and is present in the human lung. Pituitary adenylate cyclase-activating peptide 38 may, therefore, play a role in the endogenous regulation of airway tone. The inhibitory effects of pituitary adenylate cyclase-activating peptide 38 are more consistent than those of the related neuropeptide vasoactive intestinal polypeptide, perhaps reflecting a difference in susceptibility to degrading enzymes.