Bronchopulmonary dysplasia and neurodevelopmental outcome in extremely preterm neonates

We tested the hypothesis that the use of supplemental oxygen (sO(2)) at discharge from the NICU in extremely preterm neonates is associated with a greater risk of neurodevelopmental impairment (NDI) at 18 months corrected gestational age (CGA) than the risk of NDI of those neonates discharged in room air. Four hundred twenty-four charts were retrospectively reviewed from infants born at <27 weeks and transferred to Nationwide Children’s Hospital from December 1, 2004 to June 14, 2010. Use of sO(2) was evaluated on day of life (dol) 28, at 36 weeks post-menstrual age (PMA), and at discharge. Logistic regression was used to identify postnatal risk factors associated with sO(2) at discharge and NDI. At dol 28, 96 % of surviving patients received sO(2), and therefore had bronchopulmonary dysplasia (BPD) by definition from a National Institutes of Child Health and Human Development workshop. At 36 weeks PMA, 89 % continued on sO(2) (moderate/severe BPD), and at discharge, 74 % continued on sO(2). When factors associated with NDI were examined, the need for mechanical ventilation ≥28 days (adjOR = 3.21, p = 0.01), grade III–IV intraventricular hemorrhage (IVH) (adjOR = 4.61, p < 0.01), and discharge at >43 weeks PMA (adjOR = 2.12, p = 0.04) were the strongest predictors of NDI at 18 months CGA. There was no difference in Bayley Scales of Infant Development, third edition composite scores between patients with no/mild BPD and patients with moderate/severe BPD (cognitive p = 0.60, communication p = 0.53, motor p = 0.19) or those scores between patients on and off oxygen at discharge (cognitive p = 0.58, communication p = 0.70, motor p = 0.62). Conclusions: The need for sO(2) at discharge is not associated with an increased risk of NDI in these patients. The strongest predictors of poor neurodevelopmental outcome in this population were prolonged positive pressure support, grade III–IV IVH, and discharge at >43 weeks PMA

Inhaled nitric oxide alleviates hyperoxia suppressed phosphatidylcholine synthesis in endotoxin-induced injury in mature rat lungs

BACKGROUND: We investigated efficacy of inhaled nitric oxide (NO) in modulation of metabolism of phosphatidylcholine (PC) of pulmonary surfactant and in anti-inflammatory mechanism of mature lungs with inflammatory injury. METHODS: Healthy adult rats were divided into a group of lung inflammation induced by i.v. lipopolysaccharides (LPS) or a normal control (C) for 24 h, and then exposed to: room air (Air), 95% oxygen (O), NO (20 parts per million, NO), both O and NO (ONO) as subgroups, whereas [(3)H]-choline was injected i.v. for incorporation into PC of the lungs which were processed subsequently at 10 min, 4, 8, 12 and 24 h, respectively, for measurement of PC synthesis and proinflammatory cytokine production. RESULTS: LPS-NO subgroup had the lowest level of labeled PC in total phospholipids and disaturated PC in bronchoalveolar lavage fluid and lung tissue (decreased by 46–59%), along with the lowest activity of cytidine triphosphate: phosphocholine cytidylyltransferase (-14–18%) in the lungs, compared to all other subgroups at 4 h (p < 0.01), but not at 8 and 12 h. After 24-h, all LPS-subgroups had lower labeled PC than the corresponding C-subgroups (p < 0.05). LPS-ONO had higher labeled PC in total phospholipids and disaturated PC, activity of cytidylyltransferase, and lower activity of nuclear transcription factor-κB and expression of proinflammatory cytokine mRNA, than that in the LPS-O subgroup (p < 0.05). CONCLUSION: In LPS-induced lung inflammation in association with hyperoxia, depressed PC synthesis and enhanced proinflammatory cytokine production may be alleviated by iNO. NO alone only transiently suppressed the PC synthesis as a result of lower activity of cytidylyltransferase

Nitric Oxide Synthase Inhibition Enhances the Antitumor Effect of Radiation in the Treatment of Squamous Carcinoma Xenografts

This study tests whether the nitric oxide synthase (NOS) inhibitor, NG-nitro-L-arginine (L-NNA), combines favorably with ionizing radiation (IR) in controlling squamous carcinoma tumor growth. Animals bearing FaDu and A431 xenografts were treated with L-NNA in the drinking water. IR exposure was 10 Gy for tumor growth and survival studies and 4 Gy for ex vivo clonogenic assays. Cryosections were examined immunohistochemically for markers of apoptosis and hypoxia. Blood flow was assayed by fluorescent microscopy of tissue cryosections after i.v. injection of fluorospheres. Orally administered L-NNA for 24 hrs reduces tumor blood flow by 80% (p<0.01). Within 24 hrs L-NNA treatment stopped tumor growth for at least 10 days before tumor growth again ensued. The growth arrest was in part due to increased cell killing since a combination of L-NNA and a single 4 Gy IR caused 82% tumor cell killing measured by an ex vivo clonogenic assay compared to 49% by L-NNA or 29% by IR alone. A Kaplan-Meyer analysis of animal survival revealed a distinct survival advantage for the combined treatment. Combining L-NNA and IR was also found to be at least as effective as a single i.p. dose of cisplatin plus IR. In contrast to the in vivo studies, exposure of cells to L-NNA in vitro was without effect on clonogenicity with or without IR. Western and immunochemical analysis of expression of a number of proteins involved in NO signaling indicated that L-NNA treatment enhanced arginase-2 expression and that this may represent vasculature remodeling and escape from NOS inhibition. For tumors such as head and neck squamous carcinomas that show only modest responses to inhibitors of specific angiogenic pathways, targeting NO-dependent pro-survival and angiogenic mechanisms in both tumor and supporting stromal cells may present a potential new strategy for tumor control

MAP Kinase Phosphatase-2 Plays a Critical Role in Response to Infection by Leishmania mexicana

In this study we generated a novel dual specific phosphatase 4 (DUSP4) deletion mouse using a targeted deletion strategy in order to examine the role of MAP kinase phosphatase-2 (MKP-2) in immune responses. Lipopolysaccharide (LPS) induced a rapid, time and concentration-dependent increase in MKP-2 protein expression in bone marrow-derived macrophages from MKP-2+/+ but not from MKP-2−/− mice. LPS-induced JNK and p38 MAP kinase phosphorylation was significantly increased and prolonged in MKP-2−/− macrophages whilst ERK phosphorylation was unaffected. MKP-2 deletion also potentiated LPS-stimulated induction of the inflammatory cytokines, IL-6, IL-12p40, TNF-α, and also COX-2 derived PGE2 production. However surprisingly, in MKP-2−/− macrophages, there was a marked reduction in LPS or IFNγ-induced iNOS and nitric oxide release and enhanced basal expression of arginase-1, suggesting that MKP-2 may have an additional regulatory function significant in pathogen-mediated immunity. Indeed, following infection with the intracellular parasite Leishmania mexicana, MKP-2−/− mice displayed increased lesion size and parasite burden, and a significantly modified Th1/Th2 bias compared with wild-type counterparts. However, there was no intrinsic defect in MKP-2−/− T cell function as measured by anti-CD3 induced IFN-γ production. Rather, MKP-2−/− bone marrow-derived macrophages were found to be inherently more susceptible to infection with Leishmania mexicana, an effect reversed following treatment with the arginase inhibitor nor-NOHA. These findings show for the first time a role for MKP-2 in vivo and demonstrate that MKP-2 may be essential in orchestrating protection against intracellular infection at the level of the macrophage

Bronchopulmonary dysplasia: clinical aspects and preventive and therapeutic strategies

Abstract Background Bronchopulmonary dysplasia (BPD) is the result of a complex process in which several prenatal and/or postnatal factors interfere with lower respiratory tract development, leading to a severe, lifelong disease. In this review, what is presently known regarding BPD pathogenesis, its impact on long-term pulmonary morbidity and mortality and the available preventive and therapeutic strategies are discussed. Main body Bronchopulmonary dysplasia is associated with persistent lung impairment later in life, significantly impacting health services because subjects with BPD have, in most cases, frequent respiratory diseases and reductions in quality of life and life expectancy. Prematurity per se is associated with an increased risk of long-term lung problems. However, in children with BPD, impairment of pulmonary structures and function is even greater, although the characterization of long-term outcomes of BPD is difficult because the adults presently available to study have received outdated treatment. Prenatal and postnatal preventive measures are extremely important to reduce the risk of BPD. Conclusion Bronchopulmonary dysplasia is a respiratory condition that presently occurs in preterm neonates and can lead to chronic respiratory problems. Although knowledge about BPD pathogenesis has significantly increased in recent years, not all of the mechanisms that lead to lung damage are completely understood, which explains why therapeutic approaches that are theoretically effective have been only partly satisfactory or useless and, in some cases, potentially negative. However, prevention of prematurity, systematic use of nonaggressive ventilator measures, avoiding supraphysiologic oxygen exposure and administration of surfactant, caffeine and vitamin A can significantly reduce the risk of BPD development. Cell therapy is the most fascinating new measure to address the lung damage due to BPD. It is desirable that ongoing studies yield positive results to definitively solve a major clinical, social and economic problem

Characterisation of secreted exosomes from the intestinal nematode Heligmosomoides polygyrus

The parasite secretome has been shown to play a key role in both pathogenicity and the regulation of host defence, allowing pathogens, such as helminths, to establish a chronic infection within the host. The recently discovered presence of extracellular vesicles within parasite-derived excretory-secretory products introduces a new mechanism of potential cross-species communication. Extracellular vesicles (EVs), such as exosomes, facilitate cellular communication through the transfer of small RNAs, lipids and proteins between cells and organisms across all three kingdoms of life. In addition to their roles in normal physiology, EVs also transport molecules from pathogens to hosts, presenting parasite antigens and transferring infectious agents. Here, I examine secreted vesicles from the murine gastrointestinal nematode Heligmosomoides polygyrus, and their potential role in the host-helminth interactions. Transmission electron microscopy reveals vesicle-like structures of 50- 100 nM in the ultracentrifuged secretory product, and potential evidence of multi-vesicular bodies in the worm intestine. This, coupled with information from the exoproteome, helped support the hypothesis that exosomes originate from the parasite intestinal tract. I have completed a series of studies looking at the fundamental properties of exosome-cell interactions, providing comparative studies between mammalian and H. polygyrus-derived exosomes. I have determined some of the key factors influencing exosome uptake, including time of incubation, cell type and exosome origin. Through microarray analysis of H. polygyrus exosome-treated small intestinal epithelial cells, we see significant gene expression changes, including those involved in the regulation of signalling and the immune response, such as DUSP1 (dual-specificity phosphatase) and IL1RL1 (the receptor for IL-33). The modest reduction of inflammatory cytokine responses by exosomes in small intestinal cell lines was amplified in immune cells, such as macrophages. Exosomes can significantly reduce expression of classical activation markers, as well as inflammatory cytokine production in the macrophage cell line RAW 264.7, and this is further supported by similar responses in bone marrow-derived macrophages. Owing to their suppressive nature, I demonstrate that immunization of mice with an exosome/alum conjugate generates significant protection from a subsequent H. polygyrus larval challenge, as seen through a reduction in egg counts and worm burden. I have investigated the role of the IL33 receptor (IL-33R); a key molecule associated with parasitic resistance that is suppressed by exosomes in type-2 associated immune responses. Uptake of H. polygyrus-derived exosomes by alternatively activated macrophages caused the suppression of type 2 cytokine/protein release and the reduction of key genes associated with this phenotype. In addition, there was also significant repression of both transcript and surface T1/ST2, a subunit of the IL-33R). Using a model of lung inflammation, in vivo studies demonstrate that, in both prophylactic and co-administration experiments, exosomes modulate the innate cellular response. This is represented by changes in the number of innate lymphoid cells (ILCs), bronchoalveolar lavage eosinophils and type-2 cytokine output. In this system, the expression of T1/ST2 on type 2 ILCs was also significantly reduced. I have extended the investigation on exosome-IL-33R responses by using T1/ST2 knockout mice. Despite generating strong antibody responses, vaccination against exosomes could not protect T1/ST2 knockout mice against a subsequent infection. This work suggests that exosomes secreted by nematodes could mediate the transfer and uptake of parasite products into host cells, establishing cross-species communication to suppress the host ‘danger’ or inflammatory response

Inhaled nitric oxide for neonates with persistent pulmonary hypertension of the newborn in the CINRGI study: time to treatment response

Abstract Background Substantial numbers of neonates with hypoxic respiratory failure (HRF) do not immediately respond to inhaled nitric oxide (iNO) and are often labeled as non-responders. This retrospective data analysis assessed time to treatment response in the iNO key registration trial. Methods Treatment response was defined as a ≥10% increase in partial pressure of arterial oxygen (PaO2) or a ≥10% decrease in oxygenation index (OI) after initiation of study gas without the need for extracorporeal membrane oxygenation (ECMO). The proportion of patients showing a response at 30 min, 1 h, 24 h, and >24 h after iNO or placebo initiation was calculated and stratified by baseline PaO2 and OI. Results Data from 248 patients (iNO: n = 126; placebo: n = 122) were included; 66 patients receiving iNO showed improvement in oxygenation without needing ECMO versus 38 receiving placebo. Of the 66 iNO responders, 73% responded within ≤30 min, 9% within ≤1 h, 12% within ≤24 h, and 6% after 24 h. Of the 38 patients with improvement in oxygenation without needing ECMO while receiving placebo, 53% showed improvement within ≤30 min, 16% within ≤1 h, 29% within ≤24 h, and 3% after 24 h. Baseline disease severity was not predictive of time to response. Of the 48 patients in the iNO treatment group who were classified as non-responders due to eventual need for ECMO and not included in the analysis of responders, 40 (83%) had an initial improvement in oxygenation during iNO therapy. Conclusions Changes in PaO2 and OI after iNO initiation appear to be imprecise biomarkers of response to therapy in neonates with HRF. In some patients treated with iNO, it took up to 24 h to achieve improvement in oxygenation without need for ECMO, and a majority of those who eventually required ECMO did show an initial improvement in oxygenation during iNO treatment. Thus, reliable, objective, early criteria for iNO response still need to be established, and initial PaO2/OI responses should be interpreted with caution, particularly when considering discontinuing iNO therapy