Amy T. Nathan

Innate immune responses of airway epithelium to house dust mite are mediated through β-glucan–dependent pathways

BACKGROUND House dust mite (HDM) induces allergic asthma in sensitized individuals, although the mechanisms by which HDM is sensed and recognized by the airway mucosa, leading to dendritic cell (DC) recruitment, activation, and subsequent T(H)2-mediated responses, are unknown. OBJECTIVE We sought to define the pathways by which HDM activates respiratory epithelium to induce allergic airway responses. METHODS Using a human airway epithelial cell line (16HBE14o-), we studied secretion of the DC chemokine CCL20 after exposure to HDM or other allergens, investigated components of the HDM responsible for the induction of chemokine release, and examined activation of signaling pathways. Central findings were also confirmed in primary human bronchial cells. RESULTS We demonstrate that exposure of airway epithelium to HDM results in specific and rapid secretion of CCL20, a chemokine attractant for immature DCs. The induction of CCL20 secretion is dose and time dependent and quite specific to HDM because other allergens, such as ragweed pollen and cockroach antigen, fail to significantly induce CCL20 secretion. Induction of CCL20 secretion is not protease or Toll-like receptor 2/4 dependent but, interestingly, relies on beta-glucan moieties within the HDM extract, as evidenced by the ability of other beta-glucans to competitively inhibit its secretion and by the fact that disruption of these structures by treatment of HDM with beta-glucanase significantly reduces subsequent chemokine secretion. CONCLUSION Taken together, our results describe a novel mechanism for specific pattern recognition of HDM-derived beta-glucan moieties, which initiates allergic airway inflammation and, through recruitment of DCs, might link innate pattern recognition at the airway surface with adaptive immune responses.

New Insights Into Innate Immune Mechanisms Underlying Allergenicity

Allergic diseases, which have reached epidemic proportions, are caused by inappropriate immune responses to a relatively small number of environmental proteins. The molecular basis for the propensity of specific proteins to promote maladaptive, allergic responses has been difficult to define. Recent data suggest that the ability of such proteins to promote allergic responses in susceptible hosts is a function of their ability to interact with diverse pathways of innate immune recognition and activation at mucosal surfaces. This review highlights recent insights into innate immune activation by allergens—through proteolytic activity, engagement of pattern recognition receptors, molecular mimicry of TLR signaling complex molecules, lipid-binding activity, and oxidant potential—and the role of such activation in inducing allergic disease. A greater understanding of the fundamental origins of allergenicity should help define new preventive and therapeutic targets in allergic disease.

Caffeine Modulates TNF-α Production by Cord Blood Monocytes: The Role of Adenosine Receptors

Caffeine, a nonspecific adenosine receptor (AR) antagonist is widely used to treat apnea of prematurity. Because adenosine modulates multiple biologic processes including inflammation, we hypothesized that AR blockade by caffeine would increase cytokine release from neonatal monocytes. Using cord blood monocytes (CBM), we investigated 1) the changes in AR mRNA profile by real time quantitative reverse-transcription polymerase-chain-reaction (qRT-PCR) and protein expression (western blot) after in vitro culture, caffeine or lipopolysaccharide (LPS) exposure, and 2) the modulation of cytokine release and cyclic adenosine monophosphate (cAMP) production by enzyme-linked immunosorbent assay (ELISA) induced by caffeine and specific AR antagonists: DPCPX(A1R), ZM241385(A2aR), MRS1754(A2bR), and MRS1220(A3R). After 48 h in culture, A2aR and A2bR gene expression increased 1.9 (p = 0.04) and 2.5-fold (p = 0.003), respectively. A1R protein expression directly correlated with increasing LPS concentrations (p = 0.01), with minimal expression preexposure. Only caffeine (50 μM) and DPCPX (10 nM) decreased tumor necrosis factor-alpha (TNF-α) release from LPS activated-CBM by 20 and 25% (p = 0.01) and TNF-α gene expression by 30 and 50%, respectively, in conjunction with a ≥2-fold increase in cAMP (p < 0.05). AR blockade did not modulate other measured cytokines. The induction of A1R after LPS exposure suggests an important role of this receptor in the control of inflammation in neonates. Our findings also suggest that caffeine, via A1R blockade, increases cAMP production and inhibits pretranscriptional TNF-α production by CBM.

Correlation between Serum Caffeine Levels and Changes in Cytokine Profile in a Cohort of Preterm Infants

OBJECTIVE To determine changes in cytokine levels associated with caffeine treatment in a cohort of preterm infants. STUDY DESIGN For this observational prospective study, we collected clinical data from 26 preterm infants (≤ 30 weeks gestational age). In addition to caffeine levels, cytokine profiles in peripheral blood (PB) and tracheal aspirates (TA) were determined with enzyme-linked immunosorbent assay at birth, before and after (at 24 hours and 1 week) initiation of caffeine. Non-parametric statistics were applied. RESULTS Included infants were 26.9 ± 1.7 weeks gestational age and weighed 985 ± 202 g. At birth, all cytokine concentrations were significantly greater in TA than PB. Serum caffeine levels were 11.1 μg/mL (interquartile range, 1.85) at approximately 24 hours post-load and 16.4 (8.7) μg/mL at 1 week on treatment. At approximately 24 hours post-load, interleukin (IL)-10 levels decreased by 47.5% (P = .01) in PB and 38.5% (P = .03) in TA, whereas other cytokine levels remained unchanged. At 1 week, caffeine levels were correlated (U-shaped) with changes in proinflammatory tumor necrosis factor-α (R(2) = 0.65; P = .0008), interleukin (IL)-1β (R(2) = 0.73; P = .0007), and IL-6 (R(2) = 0.59; P = .003), whereas inversely correlated (linear) with the anti-inflammatory IL-10 (R(2) = 0.64; P = .0008). Altogether, caffeine, at serum levels ≥ 20 μg/mL, was associated with a proinflammatory profile after 1 week of treatment. CONCLUSIONS Caffeine treatment for apnea of prematurity correlates with changes in cytokine profile. Caffeine levels ≥ 20 μg/mL are associated with a proinflammatory profile in our cohort of preterm infants.

Tools and methods for quality improvement and patient safety in perinatal care

The quality of health care is now recognized to vary widely in all medical specialties, including perinatal medicine. A national focus on quality improvement (QI) and patient safety is prompting providers to change and improve the care given to patients. All QI and safety efforts require the use of an improvement model to manage the complex process of improving care. This article reviews the most common frameworks in use today, including the Model for Improvement, Six Sigma, and Lean. Specific tools such as affinity, key driver and fishbone diagrams, process maps and statistical process control, as well as checklists are reviewed, with examples from the perinatal literature to illustrate their use in perinatal QI efforts.

Opioid Neonatal Abstinence Syndrome: An Overview

Opioid neonatal abstinence syndrome (NAS) refers to signs of withdrawal observed in infants experiencing intrauterine opioid exposures. Early identification of at-risk infants allows for the prompt initiation of nonpharmacologic supportive care. When withdrawal symptoms are severe despite these interventions, pharmacologic therapy including opioid weaning is initiated. Consistency with standardized nonpharmacologic approaches as well as stringent weaning protocols are important in minimizing the length of stay and length of pharmacologic treatment for these vulnerable patients.

The impact of fluid balance on outcomes in critically ill near-term/term neonates: a report from the AWAKEN study group

BackgroundIn sick neonates admitted to the NICU, improper fluid balance can lead to fluid overload. We report the impact of fluid balance in the first postnatal week on outcomes in critically ill near-term/term neonates.MethodsThis analysis includes infants ≥36 weeks gestational age from the Assessment of Worldwide Acute Kidney injury Epidemiology in Neonates (AWAKEN) study (N = 645). Fluid balance: percent weight change from birthweight. Primary outcome: mechanical ventilation (MV) on postnatal day 7.ResultsThe median peak fluid balance was 1.0% (IQR: −0.5, 4.6) and occurred on postnatal day 3 (IQR: 1, 5). Nine percent required MV at postnatal day 7. Multivariable models showed the peak fluid balance (aOR 1.12, 95%CI 1.08–1.17), lowest fluid balance in 1st postnatal week (aOR 1.14, 95%CI 1.07–1.22), fluid balance on postnatal day 7 (aOR 1.12, 95%CI 1.07–1.17), and negative fluid balance at postnatal day 7 (aOR 0.3, 95%CI 0.16–0.67) were independently associated with MV on postnatal day 7.ConclusionsWe describe the impact of fluid balance in critically ill near-term/term neonates over the first postnatal week. Higher peak fluid balance during the first postnatal week and higher fluid balance on postnatal day 7 were independently associated with MV at postnatal day 7.

A quality improvement initiative to reduce necrotizing enterocolitis across hospital systems

ObjectiveNecrotizing enterocolitis (NEC) is a devastating intestinal disease in premature infants. Local rates of NEC were unacceptably high. We hypothesized that utilizing quality improvement methodology to standardize care and apply evidence-based practices would reduce our rate of NEC.Study designA multidisciplinary team used the model for improvement to prioritize interventions. Three neonatal intensive care units (NICUs) developed a standardized feeding protocol for very low birth weight (VLBW) infants, and employed strategies to increase the use of human milk, maximize intestinal perfusion, and promote a healthy microbiome.ResultsThe primary outcome measure, NEC in VLBW infants, decreased from 0.17 cases/100 VLBW patient days to 0.029, an 83% reduction, while the compliance with a standardized feeding protocol improved.ConclusionThrough reliable implementation of evidence-based practices, this project reduced the regional rate of NEC by 83%. A key outcome and primary driver of success was standardization across multiple NICUs, resulting in consistent application of best practices and reduction in variation.