© 2006 American Thoracic Society
Periarterial Leukocyte Accumulation in Allergic Airway InflammationTo the Editor:With great interest we read the recent article by Chiba and colleagues (1) on the suppressive effects on allergic airway reactions in mice by the uteroglobin-related protein 1 (UGRP1). This protein is highly expressed in epithelial cells of the respiratory tract. By intranasal administration of adeno-UGRP1, this protein was documented in the bronchial epithelial cells in the mouse ovalbumin (OVA) model. The suppressive effects on the leukocyte infiltration (mainly eosinophils) in the bronchial wall are likely to be induced by the diffusion of this protein from the epithelium. However, how will this signal reach the periarterial space and result in entry of leukocytes into this compartment? This leukocyte accumulation is often observed in a variety of animal models after the application of bacteria, viruses, or toxic agents into the airspace (reviewed in Reference 2), but it is a finding rarely discussed. In this compartment, a uniquely orientated capillary network runs in parallel to the branch of the pulmonary artery (3). Unfortunately, Chiba and coworkers (1) label the vessel next to the bronchus as "vein" in their Figures 1 and 2, and in Figure 5C the structure in the upper right corner seems also to be an artery and not a bronchus (labeled br). Not only in humans, but also in rodents, the bronchus and branches of the pulmonary artery run next to each other, and the veins are usually far away from the bronchi. The labeling of the figures should be corrected. These interesting findings on UGRP1 should stimulate further experiments on the role of this unique periarterial space in the lung.
Medical School of Hannover Hannover, Germany FOOTNOTES Conflict of Interest Statement: Neither author has a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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