Effects of Nebulized Diethylenetetraamine-NONOate in a Mouse Model of Acute Pseudomonas aeruginosa Pneumonia: Pulmonary Neutrophil Infiltration

However, the nebulization of 2.5 ^mol DETA-NO had no significant effect on pulmonary bacterial load (data not shown). In contrast to DETA-NO exposure, iNO exposure was associated with an increased pulmonary bacterial load at 40 ppm (241 ± 55% of the bacterial load in mice in the untreated pneumonia group; p < 0.05) but not at 10 ppm (Fig 1).
Effects Of DETA-NO and iNO on Pulmonary Neutrophil Infiltration
Pulmonary MPO activity, a marker of leukocyte infiltration, was significantly increased in pneumonia vs sham mice (Fig 2). Pulmonary MPO levels in mice with pneumonia were unaffected either by nebulized DETA-NO or iNO. In sham mice, pulmonary MPO activity was slightly increased by nebulization of 125 ^mol DETA-NO, but not 12.5 ^mol DETA-NO. In contrast, the low level of pulmonary MPO measured in sham mice was further reduced following exposure to iNO at both 10 and 40 ppm, although only the 40-ppm dose achieved statistical significance.
The morphologic appearance of lungs from sham mice, mice with untreated pneumonia, and mice with pneumonia that were treated (with DETA-NO and iNO) are shown in Figure 3. The lungs of sham mice showed normal morphology except for mild peripheral atelectasis and vascular congestion (grade 0) More info asthma medications inhalers. Compared to sham mice, the lungs of mice with pneumonia were characterized by mild-to-moderate bronchopneumonia with vascular congestion, edema, and bronchiolar/airspace inflammatory infiltrates that were composed of neutrophils (grade 1 to 2). The lungs of mice nebulized with DETA-NO and iNO showed similar histology in terms of neutrophilic infiltration and vascular congestion, with the degree of bronchopneumonia ranging from mild to severe (grades 1 to 3). In severely affected animals, there was extensive vascular congestion, hemorrhage, and neutrophilic infiltration. However, compared to mice with pneumonia that were treated with DETA-NO and untreated mice with pneumonia, iNO exposure was associated with the presence of more abundant bacteria and less alveolar edema.
Figure 2. Effect of nebulized DETA-NO or iNO on pulmonary tissue MPO activity in sham mice and mice with P aeruginosa pneumonia (untreated sham group, 19 mice; untreated mice with pneumonia, 28 mice; other treatment groups, 6 to 12 mice per group). * = p < 0.01 for pneumonia vs sham; # = p < 0.05 for DETA-NO-treated or iNO-treated groups vs respective untreated control animals.
Figure 3. Hematoxylin and eosin-stained light micrographs of histologic sections from mice lungs. Top left, a: lung from a sham mouse showing normal airspaces, interstitium, and bronchioles (original X90). Middle left, b: lung from untreated mouse with pneumonia showing moderate bronchopneumonia with vascular congestion, alveolar edema, and moderate neutrophil infiltration (original X90). Bottom left, c: DETA-NO-treated lung from a mouse with pneumonia showing severe bronchopneumonia with edema and extensive neutrophilic infiltration (original X90). Lung from a mouse with pneumonia that has been treated with INO showing moderate bronchopneumonia (top right, d) [original X220] and abundant bacteria (middle right, e) [original X350]. The large arrows indicate neutrophils; the small arrows indicate bacteria.