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Clinical Investigations: ASTHMA |

Evaluation of Blood Vessels and Edema in the Airways of Asthma Patients*: Regulation With Clarithromycin Treatment FREE TO VIEW

Hong Wei Chu, MD; Monica Kraft, MD, FCCP; Michael D. Rex, BS; Richard J. Martin, MD, FCCP
Author and Funding Information

*From the Department of Medicine, National Jewish Medical and Research Center, Denver, CO.

Correspondence to: Richard J. Martin, MD, FCCP, National Jewish Medical and Research Center, 1400 Jackson St, Room J116, Denver, CO 80206; e-mail: martinr@njc.org



Chest. 2001;120(2):416-422. doi:10.1378/chest.120.2.416
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Published online

Background: Although airway angiogenesis and edema have been proposed to contribute to the airway remodeling process in patients with asthma, there are few studies looking at these structural components in the airway tissue of asthma patients. Mycoplasma infection may be associated with chronic asthma and has been shown to induce angiogenesis and edema in a murine model.

Participants and measurements: We evaluated blood vessels and edema by immunohistochemistry in endobronchial biopsy samples from 10 normal control subjects and 15 patients with mild-to-moderate asthma before and after a 6-week treatment with clarithromycin (n = 8) or placebo (n = 7). Type IV collagen and α2-macroglobulin were used to identify blood vessels and edema in the tissue, respectively. Mycoplasma pneumoniae was evaluated by polymerase chain reaction.

Setting: National Jewish Medical and Research Center.

Results: At baseline, the vascularity, the number of blood vessels, and the edematous area in the airway tissue were not significantly different between asthmatic patients and normal control subjects. However, asthmatic patients demonstrated increased blood vessel size compared with normal control subjects (p = 0.03). After clarithromycin treatment in asthmatic patients, the number of blood vessels was increased (p = 0.02), while edema decreased (p = 0.049). Asthmatic patients who tested positive for M pneumoniae showed a significant increase in vascularity than asthmatic patients who tested negative for M pneumoniae (p = 0.02).

Conclusion: Our data suggest that angiogenesis and edema may not be significant features of airway remodeling in patients with chronic, mild-to-moderate asthma. Clarithromycin treatment in asthmatic patients could reduce the edematous area as identified by α2-macroglobulin staining, which may lead to airway tissue shrinkage and cause an artificial increase in the number of blood vessels.

Figures in this Article

Airway remodeling, an important aspect of asthma pathology, may contribute to the airflow limitation in asthma patients.12 Several structural changes have been identified in the airway remodeling process, which include subepithelial fibrosis, smooth-muscle hypertrophy/hyperplasia, and mucous gland hypertrophy/hyperplasia. These structural changes could eventually cause the airway wall thickening. It is still unclear whether abnormalities in bronchial vasculature, such as angiogenesis, exist in the airways of asthma patients. An early study showed that blood vascularity (vessels as the percentage of total submucosal area) but not the numbers of blood vessels was increased in the small airway mucosa of postmortem fatal asthmatic lung.3A 1997 study4also demonstrated an increase in both vascularity and the numbers of blood vessels in the large airways of asthma patients. However, Carroll and coworkers5 showed that the total number of blood vessels in the airway wall and the total area occupied by vessels were similar in either small or large airway tissues from patients with fatal asthma, nonfatal asthma, and control subjects.

Airway mucosal edema results from increased microvascular permeability during the inflammatory process, which may further increase the airway wall thickening and lead to more severe airway obstruction.6Although edema has been described in the airway mucosa of asthma patients for many years,7it is very difficult to directly evaluate and quantify edema in the airways of asthma patients. Several plasma proteins, such as albumin, fibrinogen, and α2-macroglobulin, have been used as indexes of microvascular leakage and plasma exudation in asthma.8 Although increased plasma leakage as evaluated by BAL was found in asthmatic patients after allergen challenge,910 it is uncertain whether patients with stable asthma have increased microvascular leakage.8,11 To our knowledge, no study has been performed to evaluate edema or microvascular leakage in endobronchial biopsy tissue from asthma patients.

Previous studies12–14 have suggested that Mycoplasma infection may contribute to airway inflammation and remodeling. Airway inflammation and remodeling such as angiogenesis and goblet-cell metaplasia were induced in a murine model of respiratory infection with Mycoplasma pulmonis.12 Treatment with an antibiotic oxytetracycline in this animal model significantly reduced the airway inflammation, edema, and the number of blood vessels.12We have reported that chronic asthma is associated with Mycoplasma pneumoniae in the airway.13 Additionally, improvement in lung function followed with macrolide antibiotic treatment.14

In the current study, we first asked whether patients with mild-to-moderate asthma demonstrate increased airway vascularity, number of blood vessels, vessel size, and edema as compared to normal control subjects. Then, we asked whether a macrolide antibiotic, such as clarithromycin, could reduce these parameters. Therefore, we evaluated blood vessels and edema by immunostaining endobronchial biopsy specimens from normal control subjects and asthmatic patients treated with clarithromycin or placebo.

Subjects

Twenty-five subjects were recruited via newspaper and radio advertisement from the general Denver, CO community. Nine of these subjects came from our previous report of M pneumoniae detection by polymerase chain reaction.13 Sixteen subjects were new to this study. The asthmatic patients (n = 15) fulfilled criteria for asthma exhibiting a provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) of < 8 mg/mL and reversibility of lung function by at least 15% with a bronchodilator.,15 Normal control subjects (n = 10) exhibited no evidence of atopy or bronchial hyperresponsiveness (PC20 > 18 mg/mL). Exclusion criteria included inpatient status; upper or lower respiratory tract infection within 3 months of study start; use of macrolides, tetracyclines, quinolones, and oral/IV steroids within 3 months of study start; smoking history of > 5 pack-years, or any cigarettes within the previous 2 years; significant nonasthma pulmonary disease; or other medical problems. No subject was a hospital worker, ensuring that contact with potential patients infected with M pneumoniae was minimized.

Bronchoscopy

Both asthmatic patients and normal control subjects underwent bronchoscopy as previously described.16 Endobronchial biopsy tissues were obtained for staining protocol and M pneumoniae polymerase chain reaction analysis.,13 The location of the biopsies was randomized to the right or left lower lobe. Two to four tissue specimens were obtained under direct visualization from the fourth-generation or fifth-generation airways. Asthmatic patients were then randomly divided into two subgroups with different treatments. One subgroup of asthmatic patients (n = 8) received oral clarithromycin, 500 mg bid, for 6 weeks. The remainder of the asthmatic patients (n = 7) received placebo for 6 weeks. Bronchoscopy and biopsy were then repeated in both asthma groups. The protocol was approved by the institutional review board, and all subjects gave informed consent.

Tissue Processing and Staining

Endobronchial biopsy specimens were processed as previously reported.17 Briefly, specimens were fixed in acetone at− 20°C overnight and then embedded in glycol methacrylate resin. Tissue blocks were stored at − 20°C. Serial 2-μm sections were cut from the tissue blocks with a Reichert Ultracut E ultramicrotome (Leica; Deerfield, IL) and placed on poly-L-lysine-coated slides for immunostaining.

A mouse monoclonal antibody against human collagen type IV (1:50 dilution; Dako; Carpinteria, CA) was used to identify the blood vessels.4 Since α2-macroglobulin was shown to be a better edema marker in BAL fluid from patients with allergic rhinitis,,1819 we decided to use a sheep antihuman α2-macroglobulin polyclonal antibody (1:1,000 dilution; Cortex Biochem; San Leandro, CA) to indirectly identify the tissue edematous area. To reduce the variation of immunostaining between different batches, the blood vessel orα 2-macroglobulin staining was performed in the same batch. Sections were treated with 0.3% hydrogen peroxide in 0.05 mol/L Tris buffered saline solution (TBS, pH 7.6) for 30 min to inhibit endogenous peroxidase, followed by incubation with 1% normal horse or rabbit serum for 30 min to block potential nonspecific binding sites. The slides were then incubated with primary antibodies mentioned above for 2 h at room temperature, followed by incubation with biotinylated horse antimouse IgG or rabbit antisheep IgG for 1 h at room temperature. Thereafter, avidin-biotin-peroxidase complex (Vector Lab; Burlingame, CA) was added to the slides for 45 min at room temperature. After rinsing the slides in TBS, 0.03% aminoethylcarbazole in 0.03% hydrogen peroxide was used as a substrate to develop a peroxide-dependent red color reaction. Slides were counterstained with Mayer’s hematoxylin and covered with Crystalmount. Negative control slides were similarly treated but with the primary antibodies replaced by mouse or sheep serum or TBS.

Analyses of Blood Vessels and Edematous Area

Blood vessels and edematous area were examined in the submucosa at × 400 magnification. A National Institutes of Health Scion image analysis program was used to evaluate the area of blood vessels, edematous area, and submucosal area.17

The area internal to the vessel endothelial basement membrane was considered as the blood vessel area. The number of blood vessels was counted in the submucosa excluding smooth muscle and glands. The results of blood vessel evaluation in each subject4 were expressed as follows: (1) vascularity (percentage) = ([total vascular area/submucosal area] × 100); (2) number of blood vessels per millimeters squared submucosa = (total number of blood vessels/submucosal area); and (3) mean vessel size (micrometers squared) = (total vascular area/total number of blood vessels). To evaluate the edematous area, the α2-macroglobulin staining area was measured in the submucosa excluding blood vessels, smooth muscle, and glands. The measurement was expressed as edematous area (percentage) = ([α2-macroglobulin staining area/submucosal area] × 100).

All the slides were read and evaluated by the same observer who was completely blinded to subject status and treatment with a < 10% coefficient of variation for blood vessel and edematous area measurement on repeated measurement. We also performed a pilot study to test the interobserver variability for some randomly selected slides. The agreement between the two observers was < 10% coefficient of variation for the measurements.

Statistical Analyses

Within-group comparisons were performed using the paired t test or Wilcoxon rank sum test, depending on the distribution of the data. Between group comparisons were performed using the unpaired t test or a nonparametric Kruskal-Wallis analysis of variance, depending on data distribution. All tests were two sided, and a p value of ≤ 0.05 was regarded as significant.

Subjects

The characteristics of asthmatic patients and normal control subjects are shown in Table 1 . The gender distribution and the age of subjects were similar between asthmatic patients and normal control subjects. The baseline FEV1 percent predicted and PC20 were significantly lower in asthmatic patients than in normal control subjects. Five of 15 asthmatic patients were receiving inhaled steroids. None of the asthmatic patients received oral steroids. At baseline, no significant differences were present between asthmatic patients treated with the macrolide or placebo in regard to age, gender, FEV1 percent predicted, and duration of asthma, PC20, and inhaled steroid usage. After treatment, improvement of FEV1 percent predicted was seen in six of eight antibiotic-treated asthmatic patients (75.0%) and in three of seven placebo-treated asthmatic patients (42.3%; p = 0.20). PC20 was increased in six of eight antibiotic-treated asthmatic patients (75.0%) and in two of seven placebo-treated asthmatic patients (28.6%), and this change trended toward significance (p = 0.067).

Blood Vessels in Airway Tissue of Asthma Patients and Normal Control Subjects

At baseline, asthmatic patients had similar airway vascularity (4.2% [2.9 to 5.4%] vs 4.3% [2.8 to 5.0%]; p = 0.70) and number of blood vessels (143.1/mm2 [111.6 to 216.2/mm2] vs 184.8/mm2[ 143.3 to 233.3/mm2]; p = 0.20) as compared to normal control subjects (median, interquartile range). However, the blood vessel size in asthmatic patients was significantly larger (p = 0.03) than that in normal control subjects (Fig 1 ).

Baseline blood vessel data were also compared between asthmatic patients receiving (n = 5) or not receiving (n = 10) inhaled corticosteroids. No significant differences were found between the two asthma groups for vascularity (p = 0.27), number of vessels (p = 0.14), and vessel size (p = 0.33).

Edematous Area in Airway Tissue of Asthma Patients and Normal Control Subjects

Edematous area was determined byα 2-macroglobulin immunostaining in the submucosa. At the baseline, the edematous area in asthmatic patients was not significantly different from the normal control subjects (3.1%[ 0.6 to 5.5%] vs 6.0% [2.1 to 16.7%]; p = 0.22). The edematous area also did not differ (p = 0.22) between asthmatic patients receiving (2.3% [0.4 to 3.7%]) or not receiving (5.0% [0.5 to 14.8%]) inhaled corticosteroids.

Effects of Clarithromycin Treatment on Airway Blood Vessels in Asthma Patients

At the baseline, the vascularity and the vessel size were similar between asthmatic patients treated with clarithromycin or placebo. However, asthmatic patients treated with placebo had higher numbers of blood vessels than those treated with clarithromycin (p = 0.02).

After clarithromycin treatment, as shown in Table 2 , the vascularity did not significantly change. However, the number of blood vessels in the submucosa was significantly increased (p = 0.02). However, the blood vessel size tended to be decreased (p = 0.09). Placebo treatment in asthmatic patients did not significantly alter the vascularity, number of blood vessels, and vessel size (Table 2).

We also compared the changes (treatment − baseline) of vascularity, blood vessel numbers, and vessel size between clarithromycin-treated and placebo-treated asthmatic patients. As compared with placebo, clarithromycin treatment significantly increased the number of blood vessels in the submucosa (Δ = + 48.9/mm2 [− 10.8 to 109.5/mm2] vsΔ = − 37.5/mm2 [− 112.6 to− 2.1/mm2]; p = 0.037; Fig 2 ). The changes in vascularity (p = 0.12) and blood vessel size (p = 0.16) were not significantly different between the two asthma groups.

Among clarithromycin-treated asthmatic patients, four were positive for M pneumoniae and four were negative. After treatment, M pneumoniae-positive asthmatic patients showed a significant increase in vascularity compared with M pneumoniae-negative asthmatic patients (Δ = 2.9% [1.1 to 4.2%] vs Δ = 0.2% [− 1.1 to 0.3%]; p = 0.02).

Effects of Clarithromycin Treatment on Airway Edema in Asthma Patients

At baseline, the edematous area was similar between asthmatic patients treated with clarithromycin or placebo. After clarithromycin treatment, as shown in Table 2, asthmatic patients tended to have decreased edematous area (p = 0.12). Asthmatic patients treated with placebo did not show a significant change in edematous area (p = 0.95). When the changes (treatment − baseline) of edematous area were compared, clarithromycin-treated asthmatic patients demonstrated a significant decrease in edematous area as compared to placebo-treated asthmatic patients (Δ = − 0.4% [− 4.2 to 0.0] vs Δ = 0.5% [− 0.2 to 2.6%]; p = 0.049)

In contrast to the vascularity, the changes in edematous area were not significantly different between M pneumoniae-positive and M pneumoniae-negative clarithromycin-treated asthmatics. Examples of airway tissue staining for blood vessels andα 2-macroglobulin are given in Figure 3 .

This study demonstrates that as compared to normal control subjects, asthmatic patients had increased size of blood vessels, but not vascularity and the number of blood vessels. Moreover, the edematous area in airway submucosa was similar between the two groups. Antibiotic therapy in asthmatic patients increased the number of blood vessels but reduced the edematous area. Interestingly, after antibiotic treatment, M pneumoniae-positive asthmatic patients had significantly increased vascularity compared with M pneumoniae-negative asthmatics. Our data suggest that angiogenesis and edema may not be significant features in patients with mild-to-moderate, stable asthma. Clarithromycin treatment in asthma patients could reduce airway tissue edema, which may explain the artificial increase of blood vessel numbers after the treatment.

The present study does not indicate that angiogenesis is one of many airway remodeling features in patients with mild-to-moderate asthma. Our data support an early study in which similar bronchial tissue vascularity and total number of blood vessels were found among patients with fatal asthma, nonfatal asthma, and control subjects.5 However, our results were contrary to those reported by Li and Wilson,4 who found increased vascularity and number of blood vessels (identified by collagen type IV staining) in patients with mild asthma. The methodology in these two studies was similar, except that we evaluated blood vessels in the whole submucosa while they only evaluated blood vessels 150 μm below the basement membrane where there are more blood vessels. This may explain that the number of blood vessels in both normal control subjects and patients with mild asthma in their study was higher than that in our study. However, we cannot explain why we failed to see a significant difference between asthmatic patients and normal control subjects as reported by Li and Wilson.4 Interestingly, a recent study by Vrugt et al20 also evaluated blood vessels (identified by another blood vessel marker, EN4) in the whole submucosa of endobronchial biopsy tissues from normal control subjects, patients with mild asthma, and patients with severe asthma. Similar to our study, they did not find any significant differences in the number of blood vessels between patients with mild asthma and normal control subjects. However, they demonstrated a significant increase in the number of blood vessels in patients with severe asthma compared with patients with mild asthma and normal control subjects, suggesting that angiogenesis might be a characteristic of airway remodeling in patients with severe asthma, but not in patients with mild asthma. Although angiogenesis was not found in the large airways of our patients with mild-to-moderate asthma, these patients showed an increase in blood vessel size. The significance and mechanisms of vasodilation in our asthmatic patients remain to be elucidated.

It has been difficult to quantify tissue edema in a small endobronchial biopsy specimen. In this study, we for the first time attempted to evaluate airway tissue edema usingα 2-macroglobulin as a marker and measured the edematous area by image analysis. In contrary to our expectation, we did not find increased edema in biopsy tissue from asthmatic patients, which suggests that edema may not exist in patients with mild-to-moderate, stable asthma. Airway edema usually results from acute inflammatory response to allergen exposure or challenge.910 Our patients with asthma were all in stable condition without any signs of acute exacerbation or recent respiratory tract infections. Therefore, it may not be surprising that there was no significant tissue edema in patients with mild-to-moderate, stable asthma.

Since M pneumoniae has been shown to be associated with chronic asthma,13 a macrolide antibiotic (clarithromycin) was tested in asthmatic patients to see whether it could reduce blood vessels and edema. We found that, as compared to placebo-treated asthmatic patients, those treated with clarithromycin demonstrated an increased number of blood vessels and reduced edema. We also subgrouped the clarithromycin-treated asthmatic patients into M pneumoniae-positive and M pneumoniae-negative asthmatic patients. Although reduction in edema area was not significantly different between the two groups, M pneumoniae-positive asthmatic patients had a significant increase in the vascularity after clarithromycin treatment compared with M pneumoniae-negative asthmatic patients. This suggests that M pneumoniae-positive asthmatic patients might be more responsive to clarithromycin treatment. The significance and mechanisms of increased blood vessel number, vascularity, and reduced edema after clarithromycin treatment remain unclear. We speculate that increased numbers of blood vessels or vascularity in asthmatic patients may be an artifact of reduced edema by clarithromycin treatment. This artificially increased number of blood vessels or vascularity did not worsen the pulmonary functions in asthma patients, since 75% of clarithromycin-treated asthmatic patients had an improvement in FEV1 percent predicted and airway responsiveness to methacholine. Airway wall thickening has been suggested to contribute to asthma pathophysiology.,21The thickened airway wall consists of a mixture of many tissue components, including smooth muscle, mucous glands, cartilage, extracellular matrix, inflammatory cells, mesenchymal cells, blood vessels, and fluid. A change in any of these airway wall components could alter the airway wall thickness and thus affect the airflow in patients with asthma. Although no difference of edema was found at baseline between asthmatic patients and normal control subjects, a significant decrease in edema was seen in clarithromycin-treated asthmatic patients. This decrease in edema may overall reduce the airway wall thickness and therefore potentially increase the airflow in patients with asthma. Future studies combining the biopsy tissue analysis and whole airway wall thickness measurement by CT could be helpful to better understand the effects of clarithromycin treatment on airway tissue edema and other structure components. As for the mechanisms of tissue edema reduction by clarithromycin treatment, both antimicrobial (eg, Mycoplasma) and direct anti-inflammatory effects of clarithromycin could be involved.26 To further elucidate the effects of clarithromycin treatment on airway edema and blood vessels, future studies in an animal model with M pneumoniae infection are needed.

In summary, our data suggest that angiogenesis and edema may not be significant characteristics of airway remodeling in patients with chronic, mild-to-moderate, stable asthma. Clarithromycin treatment in asthma patients could reduce airway tissue edematous area, which might lead to an artificial increase in the number of blood vessels.

Abbreviations: PC20 = provocative concentration of methacholine causing a 20% fall in FEV1; TBS = Tris buffered saline solution

Supported by the American Lung Association-ARC, and the National Heart, Lung, and Blood Institute, HL 36577.

Drs. Martin and Kraft have received grant funding from Abbott Laboratories.

Table Graphic Jump Location
Table 1. Subject Characteristics *
* 

Data are expressed as mean ± SEM unless otherwise indicated; ICS = inhaled corticosteroids.

 

p < 0.01, compared to asthmatic patients.

Figure Jump LinkFigure 1. Blood vessel size in endobronchial biopsy tissues from asthmatic patients at baseline and normal control subjects. Cross bars represent the medians.Grahic Jump Location
Table Graphic Jump Location
Table 2. Blood Vessel and Edema Data in Asthmatic Patients *
* 

Data are expressed as median (interquartile range).

Figure Jump LinkFigure 2. The number of blood vessels in endobronchial biopsy tissues from asthmatic patients before and after clarithromycin or placebo treatment. Asthmatic patients treated with clarithromycin demonstrated a significant increase in the number of blood vessels. Cross bars represent the medians.Grahic Jump Location
Figure Jump LinkFigure 3. Representative photomicrographs of blood vessel and edema staining in endobronchial biopsy samples: normal control subject, type IV collagen staining (top left, A) for blood vessels and α2-macroglobulin staining (top right, B) for edematous area; asthmatic subject, type IV collagen staining (bottom left, C) and α2-macroglobulin staining (bottom right, D; original magnification × 400 for all photomicrographs).Grahic Jump Location
Busse, W, Elias, J, Sheppard, D, et al (1999) Airway remodeling and repair.Am J Respir Crit Care Med160,1035-1042. [PubMed]
 
Bousquet, J, Jeffery, PK, Busse, WW, et al Asthma: from bronchoconstriction to airways inflammation and remodeling.Am J Respir Crit Care Med2000;161,1720-1745. [PubMed]
 
Kuwano, K, Bosken, CH, Pare, PD, et al Small airway dimensions in asthma and in chronic obstructive pulmonary disease.Am Rev Respir Dis1993;148,1220-1225. [PubMed]
 
Li, X, Wilson, JW Increased vascularity of the bronchial mucosa in mild asthma.Am J Respir Crit Care Med1997;156,229-233. [PubMed]
 
Carroll, NG, Cooke, C, James, AL Bronchial blood vessel dimensions in asthma.Am J Respir Crit Care Med1997;155,689-695. [PubMed]
 
Fahy, JV, Corry, DB, Boushey, HA Airway inflammation and remodeling in asthma.Curr Opin Pulm Med2000;6,15-20. [PubMed] [CrossRef]
 
Rogers, DF, Evans, TW Plasma exudation and oedema in asthma.Br Med Bull1992;48,120-134. [PubMed]
 
Van de Graaf, EA, Out, TA, Roos, CM, et al Respiratory membrane permeability and bronchial hyperreactivity in patients with stable asthma: effects of therapy with inhaled steroids.Am Rev Respir Dis1991;143,362-368. [PubMed]
 
Lam, S, LeRiche, J, Phillips, D, et al Cellular and protein changes in bronchial lavage fluid after late asthmatic reaction in patients with red cedar asthma.J Allergy Clin Immunol1987;80,44-50. [PubMed]
 
Fick, RB, Jr, Metzger, WJ, Richerson, HB, et al Increased bronchovascular permeability after allergen exposure in sensitive asthmatics.J Appl Physiol1987;63,1147-1155. [PubMed]
 
Demoly, P, Maly, FE, Mautino, G, et al VEGF levels in asthmatic airways do not correlate with plasma extravasation.Clin Exp Allergy1999;29,1390-1394. [PubMed]
 
Bowden, JJ, Schoeb, TR, Lindsey, JR, et al Dexamethasone and oxytetracycline reverse the potentiation of neurogenic inflammation in airways of rats withMycoplasma pulmonisinfection.Am J Respir Crit Care Med1994;150,1391-1401. [PubMed]
 
Kraft, M, Cassell, GH, Henson, JE, et al Detection ofMycoplasma pneumoniaein the airways of adults with chronic asthma.Am J Respir Crit Care Med1998;158,998-1001. [PubMed]
 
Kraft, M, Cassell, GH, Bettinger, CM, et al Mycoplasma pneumoniaeas a cofactor in chronic asthma [abstract].Am J Respir Crit Care Med1997;155,A65
 
American Thoracic Society.. Standards for diagnosis and care of patients with chronic obstructive pulmonary disease (COPD) and asthma.Am Rev Respir Dis1987;136,225-244. [PubMed]
 
Martin, RJ, Cicutto, LC, Smith, HR, et al Airway inflammation in nocturnal asthma.Am Rev Respir Dis1991;143,351-357. [PubMed]
 
Chu, HW, Halliday, JL, Martin, RJ, et al Collagen deposition in large airways may not differentiate severe asthma from milder forms of the disease.Am J Respir Crit Care Med1998;158,1936-1944. [PubMed]
 
Svensson, C, Gronneberg, R, Andersson, M, et al Allergen challenge-induced entry of α2-macroglobulin and tryptase into human nasal and bronchial airways.J Allergy Clin Immunol1995;96,239-246. [PubMed]
 
Meyer, P, Persson, CG, Andersson, M, et al α2-Macroglobulin and eosinophil cationic protein in the allergic airway mucosa in seasonal allergic rhinitis.Eur Respir J1999;13,633-637. [PubMed]
 
Vrugt, B, Wilson, S, Bron, A, et al Increased submucosal vascularity in endobronchial biopsies from severe glucocorticoid-dependent asthmatics.Eur Respir J2000;15,1014-1021. [PubMed]
 
Niimi, A, Matsumoto, H, Amitani, R, et al Airway wall thickness in asthma assessed by computed tomography: relation to clinical indices.Am J Respir Crit Care Med2000;162,1518-1523. [PubMed]
 
Abisheganaden, JA, Avila, PC, Kishiyama, JL, et al Effect of clarithromycin on experimental rhinovirus-16 colds: a randomized, double-blind, controlled trial.Am J Med2000;108,453-459. [PubMed]
 
Ohri, K, Tamaoki, J, Kondo, M, et al Macrolide antibiotics inhibit nitric oxide generation by rat pulmonary alveolar macrophages.Eur Respir J2000;15,62-67. [PubMed]
 
Ianaro, A, Ialenti, A, Maffia, P, et al Anti-inflammatory activity of macrolide antibiotics.J Pharmacol Exp Ther2000;292,156-163. [PubMed]
 
Scaglione, F, Rossoni, G Comparative anti-inflammatory effects of roxithromycin, azithromycin and clarithromycin.J Antimicrob Chemother1998;41(suppl B),47-50. [PubMed]
 
Takizawa, H, Desaki, M, Ohtoshi, T, et al Erythromycin suppresses interleukin 6 expression by human bronchial epithelial cells: a potential mechanism of its anti-inflammatory action.Biochem Biophys Res Commun1995;210,781-786. [PubMed]
 

Figures

Figure Jump LinkFigure 1. Blood vessel size in endobronchial biopsy tissues from asthmatic patients at baseline and normal control subjects. Cross bars represent the medians.Grahic Jump Location
Figure Jump LinkFigure 2. The number of blood vessels in endobronchial biopsy tissues from asthmatic patients before and after clarithromycin or placebo treatment. Asthmatic patients treated with clarithromycin demonstrated a significant increase in the number of blood vessels. Cross bars represent the medians.Grahic Jump Location
Figure Jump LinkFigure 3. Representative photomicrographs of blood vessel and edema staining in endobronchial biopsy samples: normal control subject, type IV collagen staining (top left, A) for blood vessels and α2-macroglobulin staining (top right, B) for edematous area; asthmatic subject, type IV collagen staining (bottom left, C) and α2-macroglobulin staining (bottom right, D; original magnification × 400 for all photomicrographs).Grahic Jump Location

Tables

Table Graphic Jump Location
Table 1. Subject Characteristics *
* 

Data are expressed as mean ± SEM unless otherwise indicated; ICS = inhaled corticosteroids.

 

p < 0.01, compared to asthmatic patients.

Table Graphic Jump Location
Table 2. Blood Vessel and Edema Data in Asthmatic Patients *
* 

Data are expressed as median (interquartile range).

References

Busse, W, Elias, J, Sheppard, D, et al (1999) Airway remodeling and repair.Am J Respir Crit Care Med160,1035-1042. [PubMed]
 
Bousquet, J, Jeffery, PK, Busse, WW, et al Asthma: from bronchoconstriction to airways inflammation and remodeling.Am J Respir Crit Care Med2000;161,1720-1745. [PubMed]
 
Kuwano, K, Bosken, CH, Pare, PD, et al Small airway dimensions in asthma and in chronic obstructive pulmonary disease.Am Rev Respir Dis1993;148,1220-1225. [PubMed]
 
Li, X, Wilson, JW Increased vascularity of the bronchial mucosa in mild asthma.Am J Respir Crit Care Med1997;156,229-233. [PubMed]
 
Carroll, NG, Cooke, C, James, AL Bronchial blood vessel dimensions in asthma.Am J Respir Crit Care Med1997;155,689-695. [PubMed]
 
Fahy, JV, Corry, DB, Boushey, HA Airway inflammation and remodeling in asthma.Curr Opin Pulm Med2000;6,15-20. [PubMed] [CrossRef]
 
Rogers, DF, Evans, TW Plasma exudation and oedema in asthma.Br Med Bull1992;48,120-134. [PubMed]
 
Van de Graaf, EA, Out, TA, Roos, CM, et al Respiratory membrane permeability and bronchial hyperreactivity in patients with stable asthma: effects of therapy with inhaled steroids.Am Rev Respir Dis1991;143,362-368. [PubMed]
 
Lam, S, LeRiche, J, Phillips, D, et al Cellular and protein changes in bronchial lavage fluid after late asthmatic reaction in patients with red cedar asthma.J Allergy Clin Immunol1987;80,44-50. [PubMed]
 
Fick, RB, Jr, Metzger, WJ, Richerson, HB, et al Increased bronchovascular permeability after allergen exposure in sensitive asthmatics.J Appl Physiol1987;63,1147-1155. [PubMed]
 
Demoly, P, Maly, FE, Mautino, G, et al VEGF levels in asthmatic airways do not correlate with plasma extravasation.Clin Exp Allergy1999;29,1390-1394. [PubMed]
 
Bowden, JJ, Schoeb, TR, Lindsey, JR, et al Dexamethasone and oxytetracycline reverse the potentiation of neurogenic inflammation in airways of rats withMycoplasma pulmonisinfection.Am J Respir Crit Care Med1994;150,1391-1401. [PubMed]
 
Kraft, M, Cassell, GH, Henson, JE, et al Detection ofMycoplasma pneumoniaein the airways of adults with chronic asthma.Am J Respir Crit Care Med1998;158,998-1001. [PubMed]
 
Kraft, M, Cassell, GH, Bettinger, CM, et al Mycoplasma pneumoniaeas a cofactor in chronic asthma [abstract].Am J Respir Crit Care Med1997;155,A65
 
American Thoracic Society.. Standards for diagnosis and care of patients with chronic obstructive pulmonary disease (COPD) and asthma.Am Rev Respir Dis1987;136,225-244. [PubMed]
 
Martin, RJ, Cicutto, LC, Smith, HR, et al Airway inflammation in nocturnal asthma.Am Rev Respir Dis1991;143,351-357. [PubMed]
 
Chu, HW, Halliday, JL, Martin, RJ, et al Collagen deposition in large airways may not differentiate severe asthma from milder forms of the disease.Am J Respir Crit Care Med1998;158,1936-1944. [PubMed]
 
Svensson, C, Gronneberg, R, Andersson, M, et al Allergen challenge-induced entry of α2-macroglobulin and tryptase into human nasal and bronchial airways.J Allergy Clin Immunol1995;96,239-246. [PubMed]
 
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