Chest
Volume 120, Issue 2, August 2001, Pages 416-422
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Clinical Investigations
Asthma
Evaluation of Blood Vessels and Edema in the Airways of Asthma Patients: Regulation With Clarithromycin Treatment

https://doi.org/10.1378/chest.120.2.416Get rights and content

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.

Section snippets

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

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

Discussion

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

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    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.

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