Soluble interleukin-2 receptor levels in infants with bronchopulmonary dysplasia

Hemophagocytic lymphohistiocytosis associated with necrotizing enterocolitis in premature newborns

Hemophagocytic lymphohistiocytosis (HLH) is a systemic disease resulting from the excessive release of inflammatory cytokines by macrophages under prolonged antigenic stimulation. If untreated, it leads to multiorgan failure and death. Necrotizing enterocolitis (NEC) has not previously been associated with HLH. Here we report four preterm infants who were diagnosed with HLH associated with NEC. Two patients received chemotherapy and one survived. The other two infants succumbed to multiorgan failure. These results suggest that NEC may be a common clinical manifestation of HLH in premature neonates.

Inflammatory mediators in the immunobiology of bronchopulmonary dysplasia

Inflammation is important in the development of bronchopulmonary dysplasia (BPD). Polymorphonuclear cells and macrophages and proinflammatory cytokines/chemokines denote early inflammation in clinical scenarios such as in utero inflammation with chorioamnionitis or initial lung injury associated with respiratory distress syndrome or ventilator-induced lung injury. The persistence and non-resolution of lung inflammation contributes greatly to BPD, including altering the lung's ability to repair, contributing to fibrosis, and inhibiting secondary septation, alveolarization, and normal vascular development. Further understanding of the role of inflammation in the pathogenesis of BPD, in particular, during the chronic inflammatory period, offers us the opportunity to develop inflammation-related prevention and treatment strategies of this disease that has long-standing consequences for very premature infants.

Surfactant modulates intracellular signaling of the adhesion receptor L-selectin

Intraalveolar leukocyte accumulation is one of the hallmarks during respiratory distress. In the intraalveolar space, leukocyte activation is mediated by pathogens, cytokines, and different ligands binding to adhesion molecules. Leukocyte stimulation via the adhesion molecule L-selectin is specifically induced by ligands expressed on leukocytes, platelets, endothelial cells, or lipopolysaccharide. Recently, we have demonstrated that leukocyte activation by L-selectin transmits several intracellular signaling cascades resulting in capping and cytoskeletal changes, the activation of kinases and neutral sphingomyelinase, the recruitment of adaptor proteins to the cell membrane, the activation of the small G-proteins Ras and Rac, and the release of oxygen. In the present study, we examined the effects of surfactant on L-selectin-induced signal transduction in leukocytes. Using fluorescence microscopy, we provide evidence that preincubation of leukocytes with surfactant significantly inhibits receptor capping; 28+/-7% of cells show capping after L-selectin stimulation versus 8+/-5% and 3+/-1% of cells after preincubation with Exosurf and Curosurf, respectively (p < 0.05). The activity of the neutral sphingomyelinase in cell lysates is also modulated by surfactant. In addition, we show that the activation of the tyrosine kinase p56lck is diminished by approximately 50% after surfactant treatment. This results in inhibition in tyrosine phosphorylation of certain intracellular proteins. The interaction of the L-selectin molecule with its antibody was not influenced by surfactant as shown by flow cytometry. Surfactant inhibits intracellular signaling events of the L-selectin receptor in leukocytes and might therefore contribute to the modulatory effects of surfactant on immune function.

Bronchopulmonary dysplasia and oxidative stress: are we closer to an understanding of the pathogenesis of BPD?

In recent years a body of data has accumulated, linking the development of bronchopulmonary dysplasia (BPD) to increased oxidative stress in the first few days after birth, since high concentrations of metabolites reflecting increased peroxidation products such as pentane, ethane, protein carbonyl, o-tyrosine, allantoin and F2-isoprostanes, as well as low levels of glutathione and sulfhydryl/total protein ratio, also reflecting increased oxidative load, have been found in the premature infants at risk of or developing BPD. Oxidative stress seems to increase lung antioxidants in some experimental models of BPD and hyperoxia affects foetal lung growth. There are similarities between inflammation and hypoxia/reoxygenation, since both activate a number of inflammatory mediators such as cytokines and adhesion molecules, some of which are found in high concentrations in tracheal aspirate fluid of infants developing BPD. Surfactant production and function are also altered by both hyperoxia and reactive oxygen species per se, making the lungs more vulnerable to injury. This new knowledge may result in new and more efficient therapeutic approaches, hopefully leading to the eradication of BPD in the near future.

Lymphocyte subsets, sIL2-R and sICAM-1 in blood during allergen challenge tests in asthmatic children

In order to study cell activation in peripheral blood on bronchial allergen provocation up to 24 h, we investigated 32 asthmatic children, sensitive to house-dust mites. Six healthy young adult volunteers served as controls. Lymphocyte subsets (CD3, CD19, CD4, CD8) and activation markers (CD25-T, HLADR-T, CD23) in peripheral blood as well as soluble IL2-R and soluble ICAM-1 in serum were evaluated. In terms of clinical reaction, 23 children exhibited a DAR, 6 an EAR, 6 a LAR and 3 children did not show a bronchoconstrictor response to allergen challenge with house-dust mite extract (NAR). In comparison to controls, asthmatic children showed a significantly higher expression of CD23 on B-lymphocytes (p < 0.05). Other subsets were in the same range in both groups. After provocation there was a significant increase of CD4/CD8-ratio only in asthmatic children. Serum levels of sIL2-R were significantly higher in asthmatic children compared to controls at baseline as well as at 12 and 24 h after provocation, without variation during observation period. No differences were noted for sICAM-1. Our results confirm the hypothesis that lymphocytes, as important cells in regulation of allergic immune response, are recruited into peripheral blood under allergen challenge conditions in sensitized asthmatic children.