Clarithromycin in preventing bronchopulmonary dysplasia in Ureaplasma urealyticum-positive preterm infants

Appropriate antibiotic therapy improves Ureaplasma sepsis outcome in the neonatal mouse

BACKGROUND

Ureaplasma causes sepsis in human neonates. Although erythromycin has been the standard treatment, it is not always effective. No published reports have evaluated Ureaplasma sepsis in a neonatal model. We hypothesized that appropriate antibiotic treatment improves Ureaplasma sepsis in a neonatal mouse model.

METHODS

Two ATCC strains and two clinical strains of Ureaplasma were evaluated in vitro for antibiotic minimum inhibitory concentration (MIC). In addition, FVB albino mice pups infected with Ureaplasma were randomly assigned to saline, erythromycin, or azithromycin therapy and survival, quantitative blood culture, and growth were evaluated.

RESULTS

MICs ranged from 0.125 to 62.5 µg/ml and 0.25 to 1.0 µg/ml for erythromycin and azithromycin, respectively. The infecting strain and antibiotic selected for treatment appeared to affect survival and bacteremia, but only the infecting strain affected growth. Azithromycin improved survival and bacteremia against each strain, whereas erythromycin was effective against only one of four strains.

CONCLUSION

We have established a neonatal model of Ureaplasma sepsis and observed that treatment outcome is related to infecting strain and antibiotic treatment. We speculate that appropriate antibiotic selection and dosing are required for effective treatment of Ureaplasma sepsis in neonates, and this model could be used to further evaluate these relationships.

Mesenchymal stem cell-mediated reversal of bronchopulmonary dysplasia and associated pulmonary hypertension

Clinical trials have failed to demonstrate an effective preventative or therapeutic strategy for bronchopulmonary dysplasia (BPD), a multifactorial chronic lung disease in preterm infants frequently complicated by pulmonary hypertension (PH). Mesenchymal stem cells (MSCs) and their secreted components have been shown to prevent BPD and pulmonary fibrosis in rodent models. We hypothesized that treatment with conditioned media (CM) from cultured mouse bone marrow-derived MSCs could reverse hyperoxia-induced BPD and PH. Newborn mice were exposed to hyperoxia (FiO₂=0.75) for two weeks, were then treated with one intravenous dose of CM from either MSCs or primary mouse lung fibroblasts (MLFs), and placed in room air for two to four weeks. Histological analysis of lungs harvested at four weeks of age was performed to determine the degree of alveolar injury, blood vessel number, and vascular remodeling. At age six weeks, pulmonary artery pressure (PA acceleration time) and right ventricular hypertrophy (RVH; RV wall thickness) were assessed by echocardiography, and pulmonary function tests were conducted. When compared to MLF-CM, a single dose of MSC-CM-treatment (1) reversed the hyperoxia-induced parenchymal fibrosis and peripheral PA devascularization (pruning), (2) partially reversed alveolar injury, (3) normalized lung function (airway resistance, dynamic lung compliance), (4) fully reversed the moderate PH and RVH, and (5) attenuated peripheral PA muscularization associated with hyperoxia-induced BPD. Reversal of key features of hyperoxia-induced BPD and its long-term adverse effects on lung function can be achieved by a single intravenous dose of MSC-CM, thereby pointing toward a new therapeutic intervention for chronic lung diseases.

Colchicine protects against hyperoxic lung injury in neonatal rats

BACKGROUND

Bronchopulmonary dysplasia (BPD) is characterized by inflammation, fibrosis and mucosal necrosis, which leads to emphysematous coalescence of alveoli.

OBJECTIVE

We tested whether prophylaxis with colchicine , an anti-inflammatory, antioxidant and antifibrotic drug, would decrease the severity of lung injury in an animal model of BPD.

METHODS

Twenty-five rat pups were divided into three groups: control (n = 8), hyperoxia (n = 7), and hyperoxia + colchicine (n = 10). The hyperoxia groups were exposed to >95% oxygen from day 1 to 10 of life. On day 10, the animals were sacrificed and the lungs were processed for histology and biochemical analysis. Lung morphology was assessed by the mean linear intercept (MLI), a measure of alveolar size. The degree of lung inflammation and antioxidant capacity were assessed by quantifying lung homogenate tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels.

RESULTS

Colchicine significantly decreased lung damage as determined by the MLI in the hyperoxia groups (p < 0.01). The median level of lung MDA was significantly higher in the hyperoxia group compared with the control group (p < 0.05) and the colchicine-treated group (p < 0.05). Lung homogenate SOD and GSH-Px activities in the colchicine-treated group were significantly higher than in the hyperoxia group (p < 0.05). Furthermore, colchicine-treated pups had lower lung homogenate TNF-α and IL-1β levels compared with the hyperoxia group (p < 0.05).

CONCLUSIONS

Colchicine has favorable effects on alveolarization as well as inflammation and oxidative stress markers in an animal model of BPD.