Early resection of a rare congenital pulmonary airway malformation causing severe progressive respiratory distress in a preterm neonate: a case report and review of the literature.

BACKGROUND: Congenital pulmonary airway malformations (CPAMs) are a heterogenous collection of congenital lung malformations, often diagnosed prenatally. The Stocker Type III CPAM is a rare CPAM sub-type, and, when large, may be associated with hydrops. Furthermore, reports of CPAM management which may include surgical resection in extreme preterm infants are limited. CASE PRESENTATION: We report a case of a female neonate born at 28 weeks of gestation with severe respiratory distress and diffuse pulmonary opacification on the right concerning for a large congenital lung lesion. This lesion was not detected on routine antenatal imaging, and she did not have clinical findings of associated hydrops. Her respiratory status improved dramatically after surgical resection of a mass at 12 day of age. The mass was consistent pathologically with a Stocker Type III CPAM. Lung expansion showed subsequent improvement at 16 months of age. CONCLUSIONS: Our case describes a preterm neonate with severe respiratory distress that was found postnatally to have a large, unilateral congenital lung lesion despite a normal prenatal ultrasound. Additionally, this lesion required excision early in life due to severity of respiratory compromise. This case highlights that rare congenital lung lesions, like this rare sub-type of CPAM, should remain a diagnostic consideration in neonates with severe respiratory distress. Early lung resection for CPAM in preterm infants is not well described and the favorable outcomes of this case help expand perspectives on potential management strategies.

Challenges in developing a consensus definition of neonatal sepsis.

Sepsis remains a leading cause of morbidity and mortality in the neonatal population, and at present, there is no unified definition of neonatal sepsis. Existing consensus sepsis definitions within paediatrics are not suited for use in the NICU and do not address sepsis in the premature population. Many neonatal research and surveillance networks have criteria for the definition of sepsis within their publications though these vary greatly and there is typically a heavy emphasis on microbiological culture. The concept of organ dysfunction as a diagnostic criterion for sepsis is rarely considered in neonatal literature, and it remains unclear how to most accurately screen neonates for organ dysfunction. Accurately defining and screening for sepsis is important for clinical management, health service design and future research. The progress made by the Sepsis-3 group provides a roadmap of how definitions and screening criteria may be developed. Similar initiatives in neonatology are likely to be more challenging and would need to account for the unique presentation of sepsis in term and premature neonates. The outputs of similar consensus work within neonatology should be twofold: a validated definition of neonatal sepsis and screening criteria to identify at-risk patients earlier in their clinical course. IMPACT: There is currently no consensus definition of neonatal sepsis and the definitions that are currently in use are varied.A consensus definition of neonatal sepsis would benefit clinicians, patients and researchers.Recent progress in adults with publication of Sepsis-3 provides guidance on how a consensus definition and screening criteria for sepsis could be produced in neonatology.We discuss common themes and potential shortcomings in sepsis definitions within neonatology.We highlight the need for a consensus definition of neonatal sepsis and the challenges that this task poses.

Stem Cells: Potential Therapy for Neonatal Injury?

Stem cell transplantation (SCT) is an established first-line or adjunctive therapy for a variety of neonatal and adult diseases. New evidence in preclinical models as well as a few human studies show the potential utility of SCT in neuroprotection and in the modulation of inflammatory injury in at risk-neonates. This review briefly summarizes current understanding of human stem cell biology during ontogeny and present recent evidence supporting SCT as a viable approach for postinsult neonatal injury.

Maternal inflammation modulates infant immune response patterns to viral lung challenge in a murine model.

BACKGROUND: Chorioamnionitis, an inflammatory gestational disorder, commonly precedes preterm delivery. Preterm infants may be at particular risk for inflammation-related morbidity related to infection, although the pathogenic mechanisms are unclear. We hypothesized that maternal inflammation modulates immune programming to drive postnatal inflammatory processes. METHODS: We used a novel combined murine model to treat late gestation dams with low-dose lipopolysaccharide (LPS) and to secondarily challenge exposed neonates or weanlings with Sendai virus (SeV) lung infection. Multiple organs were analyzed to characterize age-specific postnatal immune and inflammatory responses. RESULTS: Maternal LPS treatment enhanced innate immune populations in the lungs, livers, and/or spleens of exposed neonates or weanlings. Secondary lung SeV infection variably affected neutrophil, macrophage, and dendritic cell proportions in multiple organs of exposed pups. Neonatal lung infection induced brain interleukin (IL)-4 expression, although this response was muted in LPS-exposed pups. Adaptive immune cells, including lung, lymph node, and thymic lymphocytes and lung CD4 cells expressing FoxP3, interferon (IFN)-γ, or IL-17, were variably prominent in LPS-exposed pups. CONCLUSION: Maternal inflammation modifies postnatal immunity and augments systemic inflammatory responses to viral lung infection in an age-specific manner. We speculate that inflammatory modulation of the developing immune system contributes to chronic morbidity and mortality in preterm infants.

Enhanced phagocytosis in neonatal monocyte-derived macrophages is associated with impaired SHP-1 signaling.

Resident macrophages represent a first line of defense through the ingestion of microbial pathogens. Phagocytosis mediated by immunoglobulin-binding Fc receptors is a complex series of events involving tyrosine phosphorylation and dephosphorylation. In the present study we determined that the phagocytic capacity of neonatal monocyte-derived macrophage (MDM) was enhanced in comparison to adult MDM. Cross-linking of surface FcγRIIa receptors enhanced tyrosine phosphorylation of several proteins in both groups, followed by a reduction in tyrosine phosphorylation in adult but not neonatal MDM. Expression of the tyrosine phosphatase SHP-1 was similar in neonatal and adult MDM; however, baseline SHP-1 activity levels were diminished in neonatal MDM. Cross-linking of FcγRIIa receptors induced a greater increase in SHP-1 activity in adult MDM vs. neonatal MDM. The cytoplasmic adapter protein Cbl is a SHP-1 ligand and negatively affects phagocytosis. As determined by co-immunoprecipitation assays, SHP-1 and Cbl did not associate to the same extent in neonatal as compared to adult MDM. Our data suggest that the enhanced phagocytic capacity of neonatal MDM is associated with decreased SHP-1 activity and alteration of downstream signaling pathways.

Flice inhibitory protein is associated with the survival of neonatal neutrophils.

Neonatal polymorphonuclear leukocytes (PMN) exhibit delayed apoptosis both constitutively and under inflammatory conditions, and evidence has linked PMN longevity to the presence of antiapoptotic proteins. Activation of the survival-associated transcription factor, nuclear factor kappa B (NF-κB), promotes the synthesis of several antiapoptotic proteins including Flice inhibitory protein (FLIP). Neonatal and adult PMN were compared in this study to test the hypothesis that FLIP modulates age-related apoptosis. Expression of the short isoform, FLIP-S, was prominent at baseline and persisted during spontaneous apoptosis in neonatal PMN, whereas basal expression was lower and decreased under the same conditions in adult PMN. Stable FLIP-S expression in neonatal PMN was associated with a relative resistance to apoptosis in response to the protein synthesis inhibitor, cycloheximide (CHX), or the NF-κB inhibitor, gliotoxin. In contrast, similar treatment of adult PMN promoted greater overall apoptosis accompanied by FLIP degradation. Nuclear levels of phosphorylated p65, a critical NF-κB dimer, were relatively robust in neonatal PMN under basal conditions or after stimulation with TNF-α, a cytokine that induces FLIP. In conclusion, persistent FLIP-S expression is involved in the longevity of neonatal PMN, and our data suggest a contribution of NF-κB signaling and related survival mechanisms.

Human tumor-infiltrating Th17 cells have the capacity to differentiate into IFN-γ+ and FOXP3+ T cells with potent suppressive function.

Accumulating evidence suggests that Th17 cells and Tregs may exhibit development plasticity and that CD4(+) Tregs can differentiate into IL-17-producing T cells; however, whether Th17 cells can reciprocally convert into Tregs has not been described. In this study, we generated Th17 clones from tumor-infiltrating T lymphocytes (TILs). We showed that Th17 clones generated from TILs can differentiate into IFN-γ-producing and FOXP3(+) cells after in vitro stimulation with OKT3 and allogeneic peripheral blood mononuclear cells. We further demonstrated that T-cell receptor (TCR) engagement was responsible for this conversion, and that this differentiation was due to the epigenetic modification and reprogramming of gene expression profiles, including lineage-specific transcriptional factor and cytokine genes. In addition to expressing IFN-γ and FOXP3, we showed that these differentiated Th17 clones mediated potent suppressive function after repetitive stimulation with OKT3, suggesting that these Th17 clones had differentiated into functional Tregs. We further demonstrated that the Th17-derived Tregs, unlike naturally occurring CD4(+) CD25(+) Tregs, did not reconvert back into Th17 cells even under Th17-biasing cytokine conditions. These results provide the critical evidence that human tumor-infiltrating Th17 cells can differentiate into Tregs and indicate a substantial developmental plasticity of Th17 cells.

Decreased CD47 expression during spontaneous apoptosis targets neutrophils for phagocytosis by monocyte-derived macrophages.

BACKGROUND: Neutrophils (PMN) are the primary leukocyte responders during acute inflammation. After migrating into the tissues, PMN undergo programmed cell death (apoptosis) and are subsequently removed via phagocytosis by resident macrophages during the resolution phase. Efficient phagocytosis of apoptotic neutrophils is necessary for successful resolution. CD47 plays a critical role in mediating the phagocytic response, although its role in the phagocytosis of apoptotic PMN is incompletely understood. AIMS: In the present study we tested the hypotheses that CD47 modulates the targeting of apoptotic PMN for phagocytosis, and that this process is altered in neonatal PMN. STUDY DESIGN: Adult and neonatal PMN were examined for their expression of CD47. To investigate CD47-mediated functions, apoptotic adult and neonatal PMN were co-cultured with monocyte-derived macrophages (MDM) and the phagocytic index was determined using a flow cytometry-based assay. RESULTS: We observed lower basal surface CD47 levels on neonatal vs. adult PMN. In both groups, spontaneous apoptosis led to decreased surface and total cellular CD47 expression. Adult and neonatal MDM ingested apoptotic neonatal target PMN more avidly than apoptotic adult target PMN. Masking of surface CD47 on PMN with a monoclonal antibody enhanced MDM phagocytic activity. CONCLUSIONS: Our results suggest that age-dependent expression of CD47 on PMN may account for differences in their ingestion by macrophages and in the resolution of inflammation.

Siglec-9 and SHP-1 are differentially expressed in neonatal and adult neutrophils.

Neonatal PMN (polymorphonuclear neutrophils) exhibit altered inflammatory responsiveness and greater longevity compared with adult PMN; however, the involved mechanisms are incompletely defined. Receptors containing immunoreceptor tyrosine-based inhibitory motif (ITIM) domains promote apoptosis by activating inhibitory phosphatases, such as Src homology domain 2-containing tyrosine phosphatase-1 (SHP-1), that block survival signals. Sialic acid-binding immunoglobulin-like lectin (Siglec)-9, an immune inhibitory receptor with an ITIM domain, has been shown to induce cell death in adult PMN in association with SHP-1. To test our hypothesis that neonatal PMN inflammatory function may be modulated by unique Siglec-9 and SHP-1 interactions, we compared expression of these proteins in adult and neonatal PMN. Neonatal PMN exhibited diminished cellular expression of Siglec-9, which was phosphorylated in the basal state. Granulocyte-macrophage colony-stimulating factor (GM-CSF) treatment decreased Siglec-9 phosphorylation levels in neonatal PMN but promoted its phosphorylation in adult PMN, observations associated with altered survival signaling. Although SHP-1 expression was also diminished in neonatal PMN, GM-CSF treatment had minimal effect on phosphorylation status. Further analysis revealed that Siglec-9 and SHP-1 physically interact, as has been observed in other immune cells. Our data suggest that age-specific interactions between Siglec-9 and SHP-1 may influence the altered inflammatory responsiveness and longevity of neonatal PMN.

Effects of anoxia on megakaryocyte progenitors derived from cord blood CD34pos cells.

BACKGROUND: Severe hypoxic insults to the fetus and neonate are associated with the development of thrombocytopenia. The thrombocytopenia in some cases is the result of disseminated intravascular coagulation, but that mechanism fails to account for all, perhaps the majority, of cases. OBJECTIVE: We hypothesized that human fetal megakaryocyte (Mk) progenitors are directly adversely affected by transient anoxia. DESIGN AND METHODS: To test this, we isolated CD34pos cells from the umbilical cord blood of 10 healthy term neonates, and exposed these to 0% or 20% O2 for 24 h, with or without recombinant thrombopoietin (rTpo, 50 ng/mL). After 24 h, a portion of the CD34pos cells were harvested for flow cytometric evaluation of apoptosis. The remaining cells were cultured for an additional 10-12 days, under normoxic conditions, in a collagen-based serum-free system containing rTpo, IL-3, and IL-6. In this way, we sought to determine the effect of transient anoxia on clonogenic capacity of Mk progenitors. RESULTS: Contrary to our hypothesis, anoxia did not increase either apoptosis or cell death of the CD34pos cells. The addition of rTpo was protective, with a significant decrease in apoptosis and cell death (P < 0.0001), and an increase in the number of Mk colonies cultured (P = 0.04). There was no difference between the normoxic and anoxic groups in proliferative potential of the Mk progenitor cells. CONCLUSIONS: The thrombocytopenia observed in neonates following an acute hypoxic event is not likely due to a direct deleterious effect of hypoxia on Mk progenitors.

Vascular cell adhesion molecule-1 expression and hematopoietic supportive capacity of immortalized murine stromal cell lines derived from fetal liver and adult bone marrow.

Ontogeny-specific differences in hematopoietic behavior may be influenced by unique adhesive interactions between hematopoietic cells and the microenvironment, such as that mediated by vascular cell adhesion molecule-1 (VCAM-1, CD 106). Although VCAM-1 is variably expressed during vertebrate development, we hypothesized that VCAM-1 expression might be linked to the enhanced capacity of the fetal liver microenvironment to support hematopoiesis. To test this we used immortalized murine stromal cell lines derived from midgestation fetal liver and adult bone marrow to compare the functional expression of VCAM-1. Molecular analysis of VCAM-1 expression was performed on stromal cell lines using Northern blot analysis, immunoprecipitation studies, and solid-phase enzyme-linked immunosorbent assay. Hematopoietic studies were performed by coculturing fetal liver cells with stromal cell lines, and the functional readout was determined by high-proliferative potential colony-forming cell (HPP-CFC) adherence assays. In contrast to our initial hypothesis, we observed greater expression of VCAM-1 messenger ribonucleic acid and protein on an adult marrow stromal cell line. In functional studies, anti-VCAM-1 antibody inhibited the binding of nearly half of the HPP-CFCs to adult marrow stroma but had a minimal effect on their binding to fetal liver stroma, despite the greater adherence of HPP-CFCs to fetal stroma. We conclude that VCAM-1 influences the hematopoietic supportive capacity of immortalized murine stroma derived from adult bone marrow. Our studies suggest that cellular interactions other than those mediated by VCAM-1 are involved in the increased adhesive capacity of immortalized murine stroma derived from fetal liver.