Expression patterns of heat shock proteins in lungs of neonates with congenital diaphragmatic hernia

Background: Congenital diaphragmatic hernia (CDH) is associated in many cas es with pulmonary hypertension. Currently, extracorporeal membrane oxygenat ion (ECMO) is one of the possible modalities of treatment of pulmonary hype rtension and prevention of parenchymal lung injury in neonates with CDH. Hypothesis: Molecular stress is present in the lungs of neonates with CDH. To test this hypothesis, we investigate the expression pattern of stress ge nes (heat shock proteins [HSPs] 27 and 70) in lungs of patients with CDH wh o have pulmonary hypertension, and evaluate the influence of ECMO on the ex pression levels of these genes to understand the underlying molecular mecha nisms. Design: Paraffin-embedded lung autopsy specimens from patients with CDH and lung hypoplasia who either did or did not receive ECMO treatment and age-m atched controls were immunostained by means of monoclonal antihuman antibod ies against HSP 70 and HSP 27, with the streptavidin-biotin complex method. Setting: Level Ill academic children's hospital. Main Outcome Measures: Expression levels of both HSP 27 and HSP 70 were sem iquantitatively evaluated in bronchial epithelium, as well as in medial smo oth muscle cells (SMCs) and endothelium of large and small pulmonary arteri es, by means of a score ranging from 0 to 4. Statistical analysis of the da ta was performed with the nonparametric Mann-Whitney test, with significant probability value at P less than or equal to.05, Results: For HSP 70, the most pronounced immunoreactivity was observed in t he bronchial epithelium, followed by the medial SMCs of small arteries (of external diameter <200 mu m). The overall expression was significantly high er in patients with CDH than controls in bronchi as well as in pulmonary ar teries. For HSP 27, intense expression was found in medial SMCs, followed b y the bronchial epithelium in controls, with significantly increased expres sion in medial SMCs of large and small; arteries in patients with CDH. Trea tment with ECMO was associated with significantly reduced expression levels of HSP 70 in medial SMCs of both large and small arteries, whereas HSP 27 expression levels were decreased only in small arteries. In addition, the e xpression levels of both HSPs were significantly lower in endothelium of sm all arteries. Conclusions: Increased expression of HSPs in CDH paints to a condition of p ulmonary stress. This pulmonary stress appears to be partially ameliorated by ECMO treatment. This may point to one of the mechanisms by which ECMO al leviates pulmonary hypertension associated with CDH.