Interleukin 1 beta, tumor necrosis factor alpha, and interleukin 8 in bronchoalveolar lavage fluid of patients with diffuse panbronchiolitis: a potential mechanism of macrolide therapy

Treatment of severe small airways disease in children with cystic fibrosis: alternatives to corticosteroids

A group of patients with cystic fibrosis (CF) have severe small airways disease characterized by wheeze, chest tightness and limited sputum production, often with deteriorating lung function. Suggested mechanisms include mucosal edema secondary to infection and inflammation, smooth muscle contraction caused by inflammatory mediators, and collapse of bronchiectatic airways. While treatment with long-term oral corticosteroids may result in symptomatic improvement, adverse effects often make them intolerable. Inhaled corticosteroids are used in many centers despite the lack of conclusive evidence of their efficacy. Therapeutic alternatives to corticosteroids are aimed at reversing bronchoconstriction and reducing inflammation. Many patients with CF are treated with short- and long-term inhaled bronchodilators, but data to support their use are inconclusive. Other attempted routes of administration for short-acting bronchodilators include the subcutaneous and intravenous routes, but clinical data are again lacking. Sodium cromoglycate (cromolyn sodium) has been studied, with little evidence of benefit. Theophyllines have also been studied, both intravenously and orally, with some effect, but are not often used in clinical practice. Nonsteroidal anti-inflammatory therapies include ibuprofen, macrolide antibiotics, intravenous immunoglobulin, cyclosporine, and leukotriene antagonists. Ibuprofen has been shown to be useful in patients with mild CF disease, but concerns about potential adverse effects have limited its use. The results of various macrolide studies are awaited, but to date there are no long-term studies published. While there is great interest in the potential of intravenous immunoglobulin, cyclosporine and leukotriene antagonists, the evidence for their effectiveness comes from anecdotal reports, thus there is currently insufficient data to support their use. Since this is a small group of patients, it is unlikely that sufficient numbers will ever be recruited for these studies; thus it is probable that drugs will be tried on an individual patient basis. The order in which they are attempted is unclear, but it would be sensible to try the least invasive medication with the least adverse effects first, moving on to more potent, but more toxic drugs if that treatment fails.

[Attenuated mRNA induction of molecules associated with neutrophil migration by 14-membered ring macrolides inhibits bleomycin induced acute lung injury in mice]

BACKGROUND

Although the pathogeneses of interstitial pneumonia are not well understood, it has been reported that inflammatory cells, especially neutrophils, and their injurious substances play important roles in the progression of interstitial pneumonia. Erythromycin and other 14-membered ring macrolides (14-MRMLs) have been reported to inhibit chronic airway inflammation by mechanisms of anti-neutrophil and several other anti-inflammatory activities. The present study was undertaken to investigate the effects and mechanisms of 14-MRMLs (erythromycin: EM; clarithromycin: CAM; roxithromycin: RXM) on an experimental model of bleomycin (BLM) -induced acute lung injury in mice.

METHODS

BLM was administered intravenously to ICR mice. For the evaluation of early-phase inflammation, cell populations in broncho-alveolar lavage fluid (BALF) and induction of mRNA of adhesion molecules (E-selectin, P-selectin, ICAM-1, VCAM-1) and TNF-alpha tested by RT-PCR in lung tissues were examined at 0 to 13 days after BLM. These parameters were also compared with those of the control (NS alone), 14-MRMLs-untreated (BLM alone) and-pre-treated (BLM+pre 14-MRMLs) groups.

RESULTS

The number of neutrophils, macrophages, and lymphocytes significantly increased in BAL. Neutrophils especially increased with two peaks after BLM administration. 14-MRMLs significantly inhibited both peaks of neutrophil. The increase in number of macrophages in BALF was significantly attenuated by EM and RXM, and slightly attenuated by CAM. Number of lymphocytes in BALF was significantly attenuated by EM and CAM, and slightly attenuated by RXM. Changes in mRNA expression of E-selectin, P-selectin, ICAM-1, VCAM-1, and TNF-alpha were associated with the number of neutrophils migrating into the airspace. 14-MRMLs clearly inhibited the induction of VCAM-1 mRNA, and tended to attenuate the induction of ICAM-1 and TNF-alpha mRNA, but did not inhibit the induction of E-selectin and P-selectin mRNA.

DISCUSSION

These findings show that 14-MRMLs clearly attenuated the expression of VCAM-1mRNA, and tended to attenuate the induction of ICAM-1 and TNF-alpha mRNA, and subsequently inhibited leucocyte, especially neutrophil migration into the airspace during the early phase of BLM-induced lung injury and finally inhibited lung fibrosis. This might be one potent mechanism of the anti-inflammatory effects of 14-MRMLs in BLM-induced acute lung injury. The findings suggest that prophylactic administration of 14-MRMLs may be clinically efficacious in preventing acute exacerbation of interstitial pneumonia and acute lung injury.

Diffuse panbronchiolitis--pathophysiology and treatment mechanisms

Diffuse panbronchiolitis (DPB) is a chronic, potentially life-threatening lower respiratory tract disease that is particularly common in Japanese people. It is characterized by chronic infiltration of inflammatory cells, and Pseudomonas aeruginosa is isolated from sputum in some cases. Bronchoalveolar lavage fluid from DPB patients contains high concentrations of neutrophils, lymphocytes and inflammatory cytokines compared with levels found in other chronic lung diseases. If left untreated, DPB progresses rapidly and is usually fatal, but long-term, low-dose macrolide therapy improves the prognosis. Macrolides are effective against DPB even in the absence of a P. aeruginosa infection. There is evidence that these antibiotic agents may have an anti-inflammatory mode of action in DPB.

Clinical relevance of macrolide-resistant Streptococcus pneumoniae for community-acquired pneumonia

Macrolides are often the first choice for empirical treatment of community-acquired pneumonia. However, macrolide resistance among Streptococcus pneumoniae has escalated at alarming rates in North America and worldwide. Macrolide resistance among pneumococci is primarily due to genetic mutations affecting the ribosomal target site (ermAM) or active drug efflux (mefE). Prior antibiotic exposure is the major risk factor for amplification and perpetuation of resistance. Clonal spread facilitates dissemination of drug-resistant strains. Data assessing the impact of macrolide resistance on clinical outcomes are spare. Many experts believe that the clinical impact is limited. Ribosomal mutations confer high-grade resistance, whereas efflux mutations can likely be overridden in vivo. Favorable pharmacokinetics and pharmacodynamics, high concentrations at sites of infections, and additional properties of macrolides may enhance their efficacy. In this article, we discuss the prevalence of macrolide resistance among S. pneumoniae, risk factors and mechanisms responsible for resistance, therapeutic strategies, and implications for the future.

Therapy with macrolides in patients with cystic fibrosis

Cystic fibrosis affects 1/2500 individuals and is the most common lethal autosomal recessive disease in people of northern European descent. It is characterized by chronic infections with mucoid Pseudomonas aeruginosa and progressive deterioration of respiratory function. Much research has focused on the inflammatory component of the disease. Macrolide antibiotics are postulated to suppress inflammatory mediators and interfere with biofilm formation produced by P. aeruginosa. In vitro studies show promising results, and a limited number of human studies reported improvements in respiratory function with the drugs. Macrolide antibiotics are generally safe and well tolerated and may prove to be effective in patients with cystic fibrosis.

Characterization of CD44 expressed on alveolar macrophages in patients with diffuse panbronchiolitis

Interleukin (IL)-8 may play an important role in neutrophil infiltration in the airways of patients with diffuse panbronchiolitis (DPB). Furthermore, alveolar macrophages could produce IL-8 subsequent to CD44-hyaluronic acid (HA) interaction. The purpose of this study was to evaluate the contribution of CD44 expressed on alveolar macrophages to the pathogenesis of DPB. We examined the concentration of soluble CD44 (sCD44) in bronchoalveolar lavage fluid (BALF) and CD44 expression on macrophages in BALF from patients with DPB before and after low-dose, long-term macrolide therapy. We also assessed the HA-binding ability of alveolar macrophages as a functional analysis of the CD44 molecule. The sCD44 concentration in BALF was significantly lower in patients with DPB than in healthy volunteers. Percentages of alveolar macrophages expressing low CD44 (CD44 low(+)) and HA-nonbinding alveolar macrophages were higher in patients with DPB compared with healthy volunteers. Furthermore, macrolide therapy normalized CD44 expression and HA-binding ability of macrophages in BALF from DPB patients. Our findings suggest that alveolar macrophage dysfunction could result from abnormalities of CD44 expression in patients with DPB and that these events could contribute to the pathogenesis of DPB.

Anti-inflammatory effects of macrolide antibiotics

Macrolides are widely used as antibacterial drugs. Clinical and experimental data, however, indicate that they also modulate inflammatory responses, both contributing to the treatment of infective diseases and opening new opportunities for the therapy of other inflammatory conditions. Considerable evidence, mainly from in vitro studies, suggests that leukocytes and neutrophils in particular, are important targets for modulatory effects of macrolides on host defense responses. This underlies the use of the 14-membered macrolide erythromycin for the therapy of diffuse panbronchiolitis. A variety of other inflammatory mediators and processes are also modulated by macrolides, suggesting that the therapeutic indications for these drugs may be extended significantly in future.

Effect of roxithromycin on T lymphocyte proliferation and cytokine production elicited by mite antigen

Clinical evidence suggests that roxithromycin (RXM) may be an effective additional therapy for bronchial asthma. However, how it interferes with allergic responses is unclear. To investigate the mechanisms of action of RXM, lymphocyte transformation and interferon (IFN)-gamma, interleukin (IL)-4 and IL-5 synthesis associated with Dermatophagoides farinae (Df), mite antigen in patients with bronchial asthma were evaluated in vitro in the presence of RXM. T cell proliferation in Df antigen-stimulated patients' lymphocytes was suppressed by 50-100 microg/ml of RXM. Production of IL-4 and IL-5 was similarly decreased by 1-10 microg/ml RXM, whereas, IFN-gamma production, which was reduced by Df-stimulation alone, was increased by 50 microg/ml RXM. Our results suggest that skewed cytokine profiles of patients with mite antigen-induced bronchial asthma may be corrected with RXM, which may mimic those of patients in remission, who are tolerant of Df antigen.

High concentrations of beta-chemokines in BAL fluid of patients with diffuse panbronchiolitis

BACKGROUND

T cells are important cellular components of bronchial inflammation in diffuse panbronchiolitis (DPB). beta-Chemokines such as RANTES (regulated on activation, normal T-cell expressed and secreted) and macrophage inflammatory peptide (MIP)-1alpha are closely related to the migration of inflammatory cells into the lung. In this study, we investigate the contribution of beta-chemokines to the accumulation of T cells in the lungs of patients with DPB.

PATIENTS AND METHODS

We determined the levels of beta-chemokines in BAL fluid (BALF) and the correlation between these levels and T-cell subsets in BALF of 23 patients with DPB and 16 healthy subjects by sandwich enzyme-linked immunosorbent assay and flow cytometry.

RESULTS

Percentages of CD3+ human leukocyte antigen (HLA)-DR+, CD8+, and CD8+HLA-DR+ cells in BALF of patients were significantly higher than in the control BALF. The absolute number of CD8+HLA-DR+ cells was also higher in BALF of patients than in the control BALF (p < 0.0001). Phenotypic analysis of CD4+ cells in BALF showed a similar percentage of CD4+CD45RA+ cells and CD4+CD29+ cells in patients and normal subjects. The concentrations of RANTES and MIP-1alpha in BALF of patients with DPB were significantly higher than in BALF of normal subjects (p < 0.05). In addition, there was a significant correlation between the absolute number or percentage of CD8+HLA-DR+ cells and MIP-1alpha concentration in BALF.

CONCLUSIONS

Our results suggest that the interaction between activated CD8+ T cells and MIP-1alpha may contribute to the pathogenesis of DPB.

Neutrophils, unopposed neutrophil elastase, and alpha1-antiprotease defenses following human lung transplantation

Neutrophils are sequestered in the newly transplanted lung after reperfusion or with infection, rejection, and chronic graft dysfunction. Because unopposed (free) neutrophil elastase (NE) released into bronchoalveolar secretions may injure the lung allograft and impair bacterial clearance, we assessed total neutrophil numbers, myeloperoxidase activity as an index of neutrophil influx and degranulation, alpha1-antiprotease (alpha1-AP) concentrations, and unopposed NE activity in bronchoalveolar secretions from lung transplant recipients. Unopposed NE activity was present in bronchoalveolar lavage fluid (BALF) from recipients transplanted for emphysema associated with alpha1-AP deficiency as well as recipients without such deficiency (171 of 2,137 BALF; 8%). Ten of 17 (59%) recipients with alpha1-AP deficiency who were followed for at least 1 yr after transplant with multiple surveillance and diagnostic bronchoscopies had at least one BALF containing unopposed NE, usually associated with the presence of > or = 10(5) colony forming units/ml BALF of aerobic bacteria. In contrast, 19 of 58 (33%) with emphysema not associated with alpha1-AP deficiency, 8 of 32 (25%) recipients with cystic fibrosis (CF), 6 of 16 (38%) with idiopathic pulmonary fibrosis (IPF), and 11 of 36 (31%) with other indications for transplant had unopposed NE in BALF. alpha1-AP levels were significantly elevated in the early posttransplant time period and could be augmented considerably in alpha1-AP-deficient recipients with episodes of infection or rejection. Our findings indicate that unopposed NE activity can be found in both alpha1-AP-deficient and alpha1-AP-sufficient recipients after transplantation, usually in association with endobronchial bacterial infection.

Erythromycin attenuates an experimental model of chronic bronchiolitis via augmenting monocyte chemoattractant protein-1

The mechanisms underlying the therapeutic efficacy of erythromycin (EM) in diffuse panbronchiolitis (DPB) was investigated. For this purpose, an experimental rabbit model of DPB induced by Pseudomonas aeruginosa inoculation was employed. Daily administration of EM (3 mg x kg x day(-1)) led to an increase in the number of macrophages in bronchoalveolar lavage fluid (BALF) at an early phase, while reducing the size of granulomatous lesions at the late phase without affecting the number of viable bacteria recovered from the infected lung. Reverse transcriptase polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA) and immunohistochemical studies showed that monocyte chemoattractant protein (MCP)-1 was produced in both BALF and infected lung. EM treatment resulted in a significant increase in the level of MCP-1 in BALF, while reducing that of tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-8. EM also increased MCP-1 messenger ribonucleic acid (mRNA) and protein expression in the infected lung. MCP-1 blockade abolished the protective effect of EM, as neutralization of MCP-1 with anti-MCP-1 antibodies reduced the EM-induced increase in the number of macrophages in BALF, and augmented size of the granulomatous lesions, as compared to control. The results of the present study suggest that erythromycin attenuates the pulmonary granuloma formation, at least in part, by increasing the production of monocyte chemoattractant protein-1.

Intrapulmonary concentrations of inflammatory cytokines in a mouse model of chronic respiratory infection caused by Pseudomonas aeruginosa

We investigated the role of inflammatory cytokines in a mouse model of chronic Pseudomonas aeruginosa infection mimicking diffuse panbronchiolitis (DPB), and determined the effects of clarithromycin therapy on the production of these cytokines. The concentrations of IL-1beta, IL-2, IL-4, IL-5, interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) were measured serially in the lungs of mice with experimentally induced chronic respiratory P. aeruginosa infection until 60 days after inoculation. The concentrations of these cytokines during the course of the disease were significantly higher than baseline (before inoculation, P<0.01 for all cytokines). Clarithromycin significantly inhibited the production of IL-1beta and TNF-alpha in the lung (P<0.01). The same treatment also reduced the levels of other cytokines, albeit insignificantly. Treatment with anti-TNF-alpha antibody significantly reduced the number of pulmonary lymphocytes and concentration of IL-1beta in the lung (P<0.01), but did not change the number of viable bacteria. Our findings resemble those detected in bronchoalveolar lavage fluid of patients with DPB and indicate that inflammatory cytokines play an important role in chronic P. aeruginosa lung infection. Our results also show that macrolides modulated the production of these cytokines, ultimately reducing lymphocyte accumulation in the lung. Our data suggest that anti-TNF-alpha antibody might be a useful new strategy for the treatment of chronic respiratory P. aeruginosa infection.

Erythromycin inhibits beta2-integrins (CD11b/CD18) expression, interleukin-8 release and intracellular oxidative metabolism in neutrophils

Macrolides have therapeutic benefits on chronic inflammatory airway diseases. Thus, macrolides are supposed to have variable biological effects apart from antimicrobial activity. Neutrophil adherence and influx with oxidants and cytokines production implicates involvement in airway inflammation. To investigate whether erythromycin (EM) affects neutrophil activity in vitro, lipopolysaccharide (LPS)-treated neutrophils were continuously incubated for 4 h in the absence or presence of increasing doses of EM from 1 microg ml(-1) to 100 microg ml(-1) in the last 2 h. Leukocyte adhesion molecules Mac-1 and intracellular H2O2(DCFH) were determined by flowcytometric assay. IL-8 and TNFalpha in supernatant was measured by ELISA method. The expression of Mac-1 and mean intracellular DCF fluorescence intensity (DCFH) of neutrophils significantly increased after stimulation with LPS. Pretreatment with EM significantly decreased LPS induced Mac-1 expression on neutrophils compared with LPS stimulation only. EM alone (100 microg ml(-1)) also decreased Mac-1 expression on neutrophils. EM significantly reduced the LPS-increased DCFH. EM alone (100 microg ml(-1)) also caused a decrease in DCFH. Increasing doses of EM also significantly decreased the IL-8 released by LPS-stimulated neutrophils. In conclusion, EM exerts a direct effect on the neutrophils by downregulating the expression of beta2-integrin on neutrophils, thus leading to a decrease in the intracellular H2O2, as well as the production of IL-8. Our conclusion provides an explanation for the clinical efficacy of erythromycin in neutrophil-mediated airway inflammation.

[Macrolides and Pseudomonas aeruginosa infection]

Several unique effects of subinhibitory concentrations of C14 and C15 macrolides on Pseudomonas aeruginosa infection are described in vitro: P. aeruginosa virulence factors inhibition, bacterial biofilm disruption, P. glycoprotein expression upregulation, anti-inflammatory and immunoregulatory effects. Clinical trials in vivo are warranted to assess the potential usefulness of macrolides for treatment of chronic infections caused by P. aeruginosa.

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.

Grepafloxacin inhibits tumor necrosis factor-alpha-induced interleukin-8 expression in human airway epithelial cells

We examined the effect of grepafloxacin (GPFX), a new fluoroquinolone antimicrobial agent, on interleukin-8 (IL-8) expression in tumor necrosis factor-alpha (TNF-alpha)-stimulated human airway epithelial cells (AEC). GPFX inhibited IL-8 protein production as well as mRNA expression in a concentration-dependent manner (2.5 - 25 micro g/ml), but the inhibition of IL-8 expression by corresponding concentrations of GPFX to serum and airway lining fluids was not complete. We discuss the modulatory effect of GPFX on IL-8 production in the context of its efficacy on controlling chronic airway inflammatory diseases.

Interleukin-8 gene repression by clarithromycin is mediated by the activator protein-1 binding site in human bronchial epithelial cells

Macrolide antibiotics are known to be effective for the treatment of chronic inflammatory airway diseases including diffuse panbronchiolitis, chronic bronchitis, and bronchial asthma. Other than having antimicrobial activities, macrolides have antiinflammatory effects, such as the inhibition of cytokine production. In the present study we investigated the effects of clarithromycin (CAM) on interleukin (IL)-8 gene expression and protein levels, using the human bronchial epithelial cell line BET-1A. Northern blot analyses showed that CAM inhibited tumor necrosis factor (TNF)-alpha-induced IL-8 gene expression in a dose- and incubation time-dependent manner. The half-life of IL-8 messenger RNA transcripts in TNF-alpha-treated BET-1A cells did not change with CAM. Transfection studies with BET-1A cells, using fusion genes composed of the 5'-flanking sequences of the IL-8 gene and a luciferase reporter gene, demonstrated potent promoter activity in a 174-bp segment (-130 to +44 bp relative to the transcription start site). This segment includes activator protein (AP)-1 and nuclear factor (NF)-kappaB-like sites, and exhibited its strongest response to TNF-alpha. TNF-alpha-induced promoter activity in this segment showed a significant repression by CAM. However, a 156-bp segment (-112 to +44 bp) that does not include an AP-1 site but includes an NF-kappaB-like site did not show a significant repression of TNF-alpha-induced promoter activity by CAM. Mutation of the AP-1 binding site abrogated the suppression by CAM of TNF-alpha-induced enhancement of luciferase activity. In accord with promoter analyses, an electrophoretic mobility shift assay showed that CAM repressed AP-1 binding in TNF-alpha-treated BET-1A cells; however, TNF-alpha induced both AP-1 and NF-kappaB binding activities in BET-1A cells. These data suggest that macrolides such as CAM repress IL-8 gene transcription mainly via the AP-1 binding site in human bronchial epithelial cells. Our findings provide a novel mechanism for the antiinflammatory function of macrolides, implicating a target for the development of new drugs for treating chronic airway inflammation.

Cholinomimetic action of macrolide antibiotics on airway gland electrolyte secretion

We investigated the acute effects of erythromycin (EM) and its derivatives on ionic currents in airway glands from feline tracheae. Therapeutic concentrations of EM or clarithromycin (CAM) attenuated the whole cell currents evoked by ACh in a competitive manner. The maximally stimulated inward Cl- currents were reduced to 54 and 83% and the outward K+ currents to 55 and 84% of control values by EM and CAM, respectively, whereas the responses induced by phenylephrine, norepinephrine, caffeine, or ionomycin were unaffected by EM, CAM, or EM523, a synthetic derivative of EM. K+ channels in excised outside-out patches were not influenced by macrolides. Although therapeutic concentrations of macrolides showed no effect on the baseline currents, high concentrations of macrolides alone evoked currents mimicking the ACh response, which were abolished completely by atropine. We concluded that macrolides act as a partial agonist on cholinergic receptors, resulting in a reduction of Cl- secretion at pharmacological doses of the agents, which may exhibit a pronounced effectiveness on hypertrophied and/or cholinergically sensitized submucosal glands in pathological airways.

Fourteen-member macrolides inhibit interleukin-8 release by human eosinophils from atopic donors

Macrolide antibiotics such as erythromycin have been reported to be effective for asthma. However, the precise mechanisms of this effect remain unclear. We studied the effect of erythromycin, clarithromycin, josamycin, and other antibiotics on the release by eosinophils of interleukin-8 (IL-8), a potent chemokine for inflammatory cells, including eosinophils themselves. Human eosinophils were isolated from atopic patients, and the effects of the drugs on IL-8 release were evaluated. Only 14-member macrolides (erythromycin and clarithromycin) showed a concentration-dependent suppressive effect on IL-8 release (control, 100%; erythromycin at 1 microgram/ml, 67.82% +/- 3.45% [P < 0.01]; clarithromycin at 5 micrograms/ml, 56.81% +/- 9.61% [P < 0.01]). The effect was found at therapeutic concentrations and appeared to occur at the posttranscriprtional level. In contrast, a 16-member macrolide (josamycin) had no significant effect. We suggest that 14-member macrolides inhibit IL-8 release by eosinophils and may thereby prevent the autocrine cycle necessary for the recruitment of these cells into the airways.

Roxithromycin inhibits cytokine production by and neutrophil attachment to human bronchial epithelial cells in vitro

We evaluated the effect of roxithromycin on cytokine production and neutrophil attachment to human airway epithelial cells. Roxithromycin suppressed production of interleukin 8 (IL-8), IL-6, and granulocyte-macrophage colony-stimulating factor. It inhibited neutrophil adhesion to epithelial cells. Roxithromycin modulates local recruitment and activation of inflammatory cells, which may have relevance to its efficacy in airway diseases.

Interleukin-8 and markers of neutrophil degranulation in pleural effusions

In order to know the degree of interleukin-8 (IL-8) production in the pleural space and its relationship to neutrophil activation, IL-8, neutrophil elastase (NE), and myeloperoxidase (MPO) were assessed in blood and pleural fluid (PF) of 219 patients with pleural effusions. Correlations between blood and PF IL-8, NE, and MPO were either absent or weak, except for IL-8 in transudates (r = 0.6745, p < 0.001). PF IL-8, NE, and MPO concentrations in cases of empyema were higher than in cases of effusion of other causes (p < 0.001). No significant differences in inflammatory markers were observed between parapneumonic and tuberculous fluids. IL-8, NE, and MPO levels in malignant, nonspecific, and transudative effusions were lower than in those due to infection, the lowest levels corresponding to transudates. No significant correlation was observed between PF IL-8 and neutrophil count in any group; in contrast, IL-8 was associated with NE and MPO in empyema (r = 0.7545, and r = 0.7283; p < 0.001), tuberculosis (r = 0.4016, p = 0.008 and r = 0.6545, p < 0.001), and nonspecific effusions (r = 0.3748, p = 0.007 and r = 0.3085, p = 0.028). Our results indicate that local production of markers of the nonspecific inflammatory response is high in both chronic and acute pleural infection, and suggest a role for IL-8 in the release of NE and MPO.

Elevated levels of soluble adhesion molecules in serum of patients with diffuse panbronchiolitis

STUDY OBJECTIVE

Adhesion molecules have been implicated in the pathogenesis of inflammatory diseases. This study was designed to determine whether soluble adhesion molecules in serum reflect the disease activity in diffuse panbronchiolitis (DPB).

PATIENTS AND METHODS

Using an enzyme-linked immunosorbent assay, we measured the serum levels of soluble L-, E-, and P-selectin (sL-, sE-, and sP-selectin), intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 in 27 patients with DPB, 13 with bronchiectasis, and 15 normal adults. BAL was also performed, and the levels of interleukin (IL)-8 and IL-1 beta in BAL fluid (BALF) were measured.

RESULTS

The serum levels of these molecules were significantly elevated in DPB patients compared with the control subjects. DPB patients also had significant high levels of circulating sE- and sP-selectin compared with patients with bronchiectasis. There was a significant correlation between serum sE-selectin and the percentage of neutrophils in BALF in all patients. There was a significant inverse correlation between serum sE-selectin and percent vital capacity in DPB patients. In the same patients, the relationships between serum sE-selectin and BALF concentrations of IL-1 beta as well as between serum sL-selectin and BALF IL-8 were also significant. Treatment of DPB patients with macrolides significantly reduced the serum levels of these soluble adhesion molecules and BALF concentrations of IL-1 beta and IL-8.

CONCLUSIONS

Our results suggest that these soluble adhesion molecules, particularly selectins, may reflect the disease activity of DPB, and that their levels may be regulated by cytokines produced in the lungs.

Inhibitory effect of erythromycin on interleukin 8 production by 1 alpha,25-dihydroxyvitamin D3-stimulated THP-1 cells

We have recently reported that long-term administration of erythromycin at a low dose reduced the number of neutrophils and concentrations of interleukin 8 (IL-8) in bronchoalveolar lavage fluid in patients with chronic lower respiratory tract disease. To investigate the mechanism of action of erythromycin, we evaluated its effect on IL-8 production in the 1 alpha,25-dihydroxyvitamin D3-stimulated human monocytic cell line THP-1. Erythromycin at a concentration of 10 micrograms/ml significantly reduced IL-8 production by THP-1 cells stimulated with lipopolysaccharide (10 ng/ml) and 1% normal human serum compared with the amount produced by untreated cells (untreated cells, 2,448 pg/ml; erythromycin-treated cells, 872 pg/ml). Our results suggest that erythromycin may impair IL-8 production by alveolar macrophages, ultimately reducing neutrophil accumulation in the airspace.

Significance of IL-1beta and IL-1 receptor antagonist (IL-1Ra) in bronchoalveolar lavage fluid (BALF) in patients with diffuse panbronchiolitis (DPB)

We evaluated the effect of erythromycin therapy on pulmonary function tests and the airway inflammatory response of patients with DPB. The number of neutrophils in BALF obtained from DPB patients was significantly higher than that of healthy volunteers. Treatment with erythromycin (600 mg/day for 12.9+/-9.5 months (mean +/- s.d.)) significantly reduced the total number of cells and neutrophils in the airway, and significantly improved pulmonary function tests. The levels of IL-1beta and IL-8 were significantly higher in DPB compared with healthy volunteers (P<0.05, P<0.05, respectively). IL-1Ra in patients is considered to have a weak inhibitory activity for IL-1beta, with approximately five-fold concentration of IL-1beta compared with that in healthy volunteers (approx. nine-fold concentration of IL-1beta). Erythromycin therapy significantly reduced these cytokines to levels comparable to those of healthy volunteers, and produced a trend toward reduction in the level of IL-1Ra in BALF. The level of IL-1beta correlated significantly with the concentration of neutrophils in BALF (r=0.72, P<0.01), as well as with the level of IL-1Ra (r=0.688, P<0.05) and IL-8 (r=0.653, P<0.05). A nearly significant or significant correlation was observed between the concentration of neutrophils and levels of IL-1Ra or IL-8 in BALF (r=0.526, P=0.053 or r=0.776, P<0.01, respectively). There was also a significant relationship between FEV(1) and the concentration of neutrophils in BALF (r=0.524, P<0.05). Our results suggest that the relative amounts of IL-1beta and IL-1Ra or IL-8 may contribute, at least in part, to the neutrophil-mediated chronic airway inflammation in patients with chronic airway disease, and long-term erythromycin therapy may down-regulate the vigorous cycle between the cytokine network and neutrophil accumulation, with resultant reduction of neutrophil-mediated inflammatory response.