Mechanism of neutrophil recruitment induced by IL-8 in chronic sinusitis

Macrolide treatment decreased the size of nasal polyps and IL-8 levels in nasal lavage

Recently, epidemiologic and experimental studies have been reported that long-term macrolides are effective for the treatment of chronic airway inflammatory diseases including diffuse panbronchiolitis, chronic rhinosinusitis, and cystic fibrosis (Jaffe A, Francis J, Rosenthal M, et al. Long-term azithromycin may improve lung function in children with cystic fibrosis. Lancet 351:420, 1998), and that macrolides can directly reduce the production of IL-8 by nasal epithelial cells (Suzuki H, Shimomura A, Ikeda K, et al. Inhibitory effect of macrolides on interleukin-8 secretion from cultured human nasal epithelial cells. Laryngoscope 107:1661-1666, 1997). In this study we administered macrolides with 14-membered rings to patients with nasal polyps due to chronic rhinosinusitis for at least 3 months and measured the IL-8 level in nasal lavage from those patients. The IL-8 levels in nasal lavage from patients with nasal polyps were reduced during macrolide treatment. There was significant correlation between decreased IL-8 levels in nasal lavage and the clinical effect of macrolides on the size of the nasal polyps. In the group whose polyps were reduced in size, the IL-8 levels dramatically decreased from 231.2 pg/mL to 44.0 pg/mL (p < 0.05), and were significantly higher before macrolide treatment than those in the group whose polyps showed no change (p < 0.005). This reduction in IL-8 may be an important aspect of the effect of macrolide treatment on nasal polyps in chronic rhinosinusitis.

Evidence for neutrophil activation in occupational asthma

In order to evaluate the role of neutrophils in the pathogenesis of occupational asthma (OA), 15 toluene diisocyanate (TDI)-asthma and six grain dust-asthma patients were recruited. Controls were the same number of subjects showing negative bronchoprovocation test (BPT) and six house dust mite-sensitive asthma. Bronchoscopic biopsy specimens were stained with monoclonal antibodies to mast cell (AA1), eosinophil (EG2), pan T cell (CD3) and neutrophil (NE). Serum neutrophil chemotactic activity (NCA) was measured before and 10-420 min after BPT. Sputum interleukin-8 (IL-8) and myeloperoxidase (MPO) were also measured. There was a significant increase of NE+ cells as well as AA1+ and EG2+ cells in grain dust- and TDI-asthma compared with house dust-sensitive asthma (P < 0.05). Neutrophil+ cells and AA1+ cells showed a significant correlation in TDI-asthma (r = 0.73, P = 0.02). Serum NCA was significantly increased at 10 min after BPT and decreased at 60 min in subjects with TDI-asthma. In grain dust-asthma, serum NCA increased at 30 min and decreased at 240 min after BPT (P < 0.05). Sputum IL-8 and MPO were significantly increased after BPT in both TDI- and grain dust-asthma (P < 0.05). These findings suggested that neutrophils in the lungs might contribute to bronchoconstriction induced by either TDI or grain dust. The possible involvement of IL-8 in activation of neutrophils was also suggested.

Increased expression of IL-4, IL-5, IFN-gamma, IL-6, IL-8, and TGF-beta mRNAs in maxillary mucosa of patients with chronic sinusitis

This study aimed to investigate expression of various cytokine mRNAs, including IL-6, IL-8, TGF-beta, IL-4, IL-5, and IFN-gamma in maxillary sinus mucosa of patients with chronic sinusitis. Maxillary sinus mucosae of six patients with chronic sinusitis and turbinate mucosae of six healthy subjects were obtained. We performed RT-PCR and Southern blot to examine gene expression of the cytokines IL-6, IL-8, TGF-beta, IL-4, IL-5, and IFN-gamma in maxillary sinus mucosa and compared the results with cytokine gene expressions in normal turbinate mucosa. IL-6, IL-8, TGF-beta, IL-4, IL-5, and IFN-gamma mRNAs were expressed more frequently in maxillary sinus mucosa from patients with chronic sinusitis than in normal turbinate mucosa. All the maxillary sinus mucosa specimens revealed relatively higher mean density ratio for each cytokine investigated than did normal turbinate mucosa. IL-6, IL-8, TGF-beta, IL-4, IL-5, and IFN-gamma mRNAs were expressed simultaneously in maxillary sinus mucosa of chronic sinusitis. These cytokines may be responsible for recruitment of inflammatory cells and for mucosal thickening in chronic sinusitis, and thus chronicity of the disease.

Grain dust induces IL-8 production from bronchial epithelial cells: the effect of dexamethasone on IL-8 production

BACKGROUND

Recent publications have suggested an active participation of neutrophils to induce bronchoconstriction after inhalation of grain dust (GD).

OBJECTIVE

To further understand the role of neutrophils in the pathogenesis of GD-induced asthma, this investigation was designed to determine whether human bronchial epithelial cells could produce IL-8 production and to observe the effect of dexamethasone on IL-8 production.

MATERIALS AND METHODS

We cultured Beas-2B, a bronchial epithelial cell line. To observe GD-induced responses, four concentrations (1 to 200 microg/mL) of GD were incubated for 24 hours and compared with those without incubation of GD. To evaluate the effect of pro-inflammatory cytokines on IL-8 production, epithelial cells were incubated with peripheral blood mononuclear cell (PBMC) culture supernatant, which was derived from the culture of PBMC from a GD-induced asthmatic subject under the exposure to 10 microg/mL of GD, and compared with those cultured without addition of PBMC supernatant. The level of released IL-8 in the supernatant was measured by enzyme-linked immunosorbent assay. To evaluate the effect of dexamethasone on IL-8 production, four concentrations (5 to 5000 ng/mL) of dexamethasone were pre-incubated for 24 hours and the same experiments were repeated.

RESULTS

There was significant production of IL-8 from bronchial epithelial cells with additions of GD in a dose-dependent manner (P < .05), which was significantly augmented with additions of PBMC supernatant (P < .05) at each concentration. Compared with the untreated sample, pretreatment of dexamethasone could induced a remarkable inhibitions (15% to 55%) of IL-8 production from bronchial epithelial cells in a dose-dependent manner.

CONCLUSION

These results suggest that IL-8 production from bronchial epithelial cells may contribute to neutrophil recruitment occurring in GD-induced airway inflammation. The downregulation of IL-8 production by dexamethasone from bronchial epithelial cells may contribute to the efficacy of this compound in reducing cellular infiltration and ultimately to its anti-inflammatory property.

Inhibitory effect of erythromycin on interleukin-8 secretion from exudative cells in the nasal discharge of patients with chronic sinusitis

OBJECTIVES

The mechanism of the efficacy of long-term low-dose macrolide therapy for chronic sinusitis is not fully understood. The authors studied the inhibitory effect of erythromycin on interleukin-8 (IL-8) secretion from exudative cells in the nasal discharge of patients with chronic sinusitis.

STUDY DESIGN AND METHODS

Exudative cells in the nasal discharge were isolated from six patients with nonallergic chronic sinusitis. The cells, more than 90% of which were neutrophils, were incubated with or without erythromycin in the presence of 10 micrograms/mL of lipopolysaccharide. The IL-8 concentrations in the culture supernatants were measured by enzyme-linked immunoassay.

RESULTS

The amount of secreted IL-8 in the absence of erythromycin was 682 +/- 226 pg/10(6) cells/24 h. The IL-8 secretion was significantly reduced to 66 +/- 15% and 46 +/- 13% of the control in the presence of 10(-6) and 10(-5) M of erythromycin, respectively.

CONCLUSION

Erythromycin may act as a biologic modulator that inhibits IL-8 secretion from exudative cells and thereby blocks the vicious circle of neutrophil recruitment and IL-8 generation in the inflammatory site in chronic sinusitis.

Sinus mucosal IL-8 gene expression in chronic rhinosinusitis

BACKGROUND

Epithelial hyperplasia and mucosal infiltration of leukocytes are common features of chronic rhinosinusitis. The epithelium can produce chemoattractant cytokines that may contribute to leukocyte infiltration in rhinosinusitis.

OBJECTIVE

We sought to determine whether mucosal IL-8 gene expression is increased in chronic rhinosinusitis and to relate IL-8 gene expression to disease severity.

METHODS

We used both a noncompetitive and a quantitative, competitive reverse transcription-polymerase chain reaction to examine IL-8 gene expression in samples of sinus mucosal tissue obtained during surgery from 22 patients with chronic rhinosinusitis and 9 normal control subjects. IL-8 gene expression was related to disease severity assessed by sinus computed tomography (CT) scores and to symptom scores assessed by means of a questionnaire.

RESULTS

Sinus mucosal IL-8 gene expression was not detected in any of the control subjects but was present in 12 of 22 (55%) patients with rhinosinusitis. Sinus CT scores and symptom scores were both significantly higher in patients with positive mucosal IL-8 gene expression than in subjects with no detectable IL-8 gene expression. Positive IL-8 gene expression was not predicted by history of prior surgery nor by atopic or asthmatic status. In 9 subjects with positive IL-8 gene expression, levels of mRNA expression, assessed by competitive reverse transcription-polymerase chain reaction, correlated significantly (rho = 0.72, P <.05) with sinus CT scores.

CONCLUSION

Sinus mucosal expression of the gene for IL-8 is increased in patients with chronic rhinosinusitis, and the level of IL-8 gene expression correlates with disease severity.

Cytokines in nasal polyposis, acute and chronic sinusitis

Cytokines are potent biologic factors involved in the regulation of inflammation, immune defense, and wound healing. Recently, growing interest has developed in the role of cytokines in chronic sinusitis and nasal polyposis. In the present study, we investigated the cytokine profile of different types of rhinosinusitis in order to evaluate whether a specific form of rhinosinusitis is associated with the expression of a certain cytokine profile. Sinus mucosa from patients with acute sinusitis (n = 10), chronic sinusitis (n = 7), antrochoanal polyp (n = 10), nasal polyps (n = 8) and controls of turbinate mucosa (n = 7) were sampled. The cytokine protein content (IL-1 beta, IL-3, IL-4, IL-5, IL-6, IL-8, IL-13, GM-CSF, interferon-gamma) of tissue homogenates was measured using ELISA technique. In acute sinusitis, the synthesis of proinflammatory cytokines and of the neutrophil chemokine IL-8 and IL-3 appeared to be upregulated. Chronic sinusitis mucosa demonstrated no significantly increased concentrations of the measured cytokines. In bilateral nasal polyposis, but not in antrochoanal polyps, the eosinophil related cytokine IL-5 was strongly upregulated. From these findings, it appears that specific cytokine patterns are found in different forms of sinusitis, and that IL-5 may represent the most important cytokine responsible for tissue eosinophilia in nasal polyposis.

Neutrophil infiltration and release of IL-8 in airway mucosa from subjects with grain dust-induced occupational asthma

BACKGROUND

The immuno-pathological mechanism for occupational asthma induced by grain dust (GD) remains to be clarified. There have been few reports suggesting the involvement of neutrophils inducing bronchoconstriction after inhalation of GD.

OBJECTIVE

To further understand the role of neutrophil in the pathogenesis of GD-induced asthma.

MATERIALS AND METHODS

We studied the phenotype of leucocytes of the bronchial mucosa in patients with GD-induced asthma. Bronchial biopsy specimens were obtained by fibreoptic bronchoscopy from six subjects with GD-induced asthma. Six allergic asthma patients sensitive to house dust mite were enrolled as controls. Bronchial biopsy specimens were examined by immunohistochemistry with a panel of monoclonal antibodies to tryptase-containing mast cell (AA1), activated eosinophil (EG2), pan T-lymphocyte (CD3) and neutrophil elastase (NE). Induced sputum was collected before and after the GD-bronchoprovocation test. The IL-8 level in the sputum was measured using ELISA.

RESULTS

There was a significant increase in the number of AA1+ and NE+ cells in bronchial mucosa of GD-induced asthma, compared with those of allergic asthma (P=0.01, P=0.01, respectively). No significant differences were observed in the number of EG2+ and CD3+ cells (P = 0.13, P=0.15, respectively). IL-8 was abundant in the sputum of all GD-induced asthma patients and significantly increased after the bronchial challenges compared with the baseline value (P = 0.03).

CONCLUSION

These findings support the view that neutrophil recruitment together with mast cells may contribute to the bronchoconstriction induced by GD. A possible involvement of IL-8 was suggested.

Enhanced neutrophil chemotactic activity after bronchial challenge in subjects with grain dust-induced asthma

BACKGROUND

There have been few reports suggesting involvement of neutrophils in induction of bronchoconstriction after inhalation of grain dust.

OBJECTIVES

To understand the role of neutrophils in pathogenesis of grain dust-induced asthma.

MATERIALS AND METHODS

We observed serum neutrophil chemotactic activity during grain dust-bronchoprovocation tests in six asthmatic subjects with positive bronchial challenges (group I). They were compared with those of six symptomatic subjects from the same workplace with negative bronchial challenges (group II).

RESULTS

After grain dust inhalation, serum neutrophil chemotactic activity significantly increased at 30 minutes (P = .028), and then decreased to baseline level at 240 minutes (P = .028) in five subjects of group I having isolated early asthmatic responses. Enhanced neutrophil chemotactic activity was persistent for up to 240 minutes in one asthmatic subject having both early and late asthmatic responses. There was, however, no significant change in serum neutrophil chemotactic activity during bronchial challenges in subjects of group II. Pre-incubation of sera with anti-interleukin-8 (IL-8) antibody did not affect the neutrophil chemotactic activity results of group I subjects.

CONCLUSION

These results suggest that enhanced neutrophil chemotactic activity distinct from IL-8 may contribute to significant bronchoconstriction induced by grain dust.

Inhibitory effect of macrolides on interleukin-8 secretion from cultured human nasal epithelial cells

The mechanism of macrolide therapy in chronic sinusitis patients is unclear. The authors studied the effect of macrolides on interleukin (IL)-8 secretion from cultured human nasal epithelial cells. Epithelial cells harvested from the nasal polyps of patients with chronic sinusitis were primary-cultured, and secreted IL-8 in culture media was measured by enzyme immunoassay. The cells secreted considerable amounts of IL-8 constitutively and in response to lipopolysaccharide. The secretion was significantly inhibited by 10(-5) M of erythromycin, clarithromycin, roxithromycin, and josamycin. 10(-6) M erythromycin still showed the inhibitory effect, whereas the same concentration of josamycin did not. These results indicate that macrolide antibiotics may act as an immunomodulator to reduce IL-8 in inflammatory sites and, at least partially, account for the clinically discrepant effects between 14- and 16-membered ring macrolides in long-term low-dose therapy for chronic sinusitis.

Expression of adhesion molecules in nonallergic chronic sinusitis

Endothelial and epithelial adhesion molecules are important in the recruitment of leukocytes to inflammatory sites. To determine the relationship between recruited leukocytes and adhesion molecules in the paranasal sinus mucosa of nonallergic chronic sinusitis, we surgically obtained mucosa from 16 patients and identified the expression of intercellular adhesion molecules (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and P-selectin by immunohistochemistry. Neutrophils were significantly dominant in the nasal discharge as compared with eosinophils. The degree of neutrophil infiltration in the paranasal sinus mucosa was prominent in both intraepithelial and subepithelial areas as compared with the lamina propria. In each tissue site, the degree of infiltration of neutrophils was similar to that of eosinophils. These findings suggest that the tissue neutrophils actively and rapidly migrated into the lumen. All the adhesion molecules except VCAM-1 were expressed in the vascular endothelial cells. On the other hand, the surface epithelial cells showed the expression of only ICAM-1. The expression of ICAM-1 on the endothelial cells correlated with the degree of neutrophil infiltration in the mucosa The eosinophil infiltration was not dependent on any adhesion molecules examined here. It was concluded that ICAM-1 expression in the mucosa may be involved in neutrophil recruitment and may contribute to the establishment of the inflammatory cell distribution in the paranasal sinus of nonallergic chronic sinusitis.

Effects of long-term low-dose macrolide administration on neutrophil recruitment and IL-8 in the nasal discharge of chronic sinusitis patients

Effects of long-term low-dose macrolide administration were studied in patients with chronic sinusitis. Twelve patients with non-allergic chronic sinusitis were orally given 150 mg roxithromycin once a day without other treatments. The patients underwent computed tomography before and after the treatment, and paranasal sinus aeration was analyzed quantitatively. The number of neutrophils in the nasal smear was semiquantitatively assessed on a grading scale, and the IL-8 concentration in the nasal discharge was measured by enzyme immunoassay. The aeration of all four sinuses significantly improved, and recruited neutrophils and the IL-8 level in the nasal discharge were simultaneously reduced after the treatment. These findings suggest that long-term low-dose roxithromycin administration inhibits the positive feedback mechanism of neutrophil recruitment and IL-8 production by the recruited neutrophils, which is considered to be an essential cause of the prolongation of sinusitis.