Beatrice E. Lechner

Biglycan regulates the expression and sarcolemmal localization of dystrobrevin, syntrophin, and nNOS

The dystrophin‐associated protein complex (DAPC) provides a linkage between the cytoskeleton and the extracellular matrix (ECM) and is also a scaffold for a host of signaling molecules. The constituents of the DAPC must be targeted to the sarcolemma in order to properly function. Biglycan is an ECM molecule that associates with the DAPC. Here, we show that biglycan null mice exhibit a mild dystrophic phenotype and display a selective reduction in the localization of α‐dystrobrevin‐1 and ‐2, α‐ and βl‐syntrophin, and nNOS at the sarcolemma. Purified biglycan induces nNOS redistribution to the plasma membrane in cultured muscle cells. Biglycan protein injected into muscle becomes stably associated with the sarcolemma and ECM for at least 2 wk. This injected biglycan restores the sarcolemmal expression of α‐dystrobrevin‐1 and ‐2, and β1‐ and β2‐syntrophin in biglycan null mice. We conclude that biglycan is important for the maintenance of muscle cell integrity and plays a direct role in regulating the expression and sarcolemmal localization of the intracellular signaling proteins dystrobrevin‐1 and ‐2, α‐ and β1‐syntrophin and nNOS.—Mercado, M. L., Amenta, A. R., Hagiwara, H., Rafii, M. S., Lechner, B., Owens, R. T., McQuillan, D. J., Froehner, S. C., Fallon, J. R. Biglycan regulates the expression and sarcolemmal localization of dystrobrevin, syntrophin, and nNOS. FASEB J. 20, E1075–E1085 (2006)

Biglycan Is an Extracellular MuSK Binding Protein Important for Synapse Stability

The receptor tyrosine kinase MuSK is indispensable for nerve-muscle synapse formation and maintenance. MuSK is necessary for prepatterning of the endplate zone anlage and as a signaling receptor for agrin-mediated postsynaptic differentiation. MuSK-associated proteins such as Dok7, LRP4, and Wnt11r are involved in these early events in neuromuscular junction formation. However, the mechanisms regulating synapse stability are poorly understood. Here we examine a novel role for the extracellular matrix protein biglycan in synapse stability. Synaptic development in fetal and early postnatal biglycan null (bgn−/o) muscle is indistinguishable from wild-type controls. However, by 5 weeks after birth, nerve-muscle synapses in bgn−/o mice are abnormal as judged by the presence of perijunctional folds, increased segmentation, and focal misalignment of acetylcholinesterase and AChRs. These observations indicate that previously occupied presynaptic and postsynaptic territory has been vacated. Biglycan binds MuSK and the levels of this receptor tyrosine kinase are selectively reduced at bgn−/o synapses. In bgn−/o myotubes, the initial stages of agrin-induced MuSK phosphorylation and AChR clustering are normal, but the AChR clusters are unstable. This stability defect can be substantially rescued by the addition of purified biglycan. Together, these results indicate that biglycan is an extracellular ligand for MuSK that is important for synapse stability.

Neurodevelopmental Outcomes of Preterm Infants Fed Human Milk: : A Systematic Review

The neurodevelopmental benefits of breast milk feedings for preterm infants have been controversial. However, the effect on preterm infant neurodevelopment is sustained into childhood. The effects of breast milk feeding during the neonatal period and the duration of breastfeeding display effects on cognition into adolescence. The volume of breast milk received is a key factor in these effects. Additionally, emerging studies support the effects of human milk on structural brain development, such as increased white matter development and increased cortical thickness. The components of breast milk thought to mediate improved cognitive outcomes include long-chain polyunsaturated fatty acids and human milk oligosaccharides.

Biglycan and decorin differentially regulate signaling in the fetal membranes

Preterm birth is the leading cause of newborn mortality in the United States and about one third of cases are caused by preterm premature rupture of fetal membranes, a complication that is frequently observed in patients with Ehlers-Danlos Syndrome. Notably, a subtype of Ehlers-Danlos Syndrome is caused by expression of abnormal biglycan and decorin proteoglycans. As compound deficiency of these two small leucine-rich proteoglycans is a model of preterm birth, we investigated the fetal membranes of Bgn(-/-); Dcn(-/-) double-null and single-null mice. Our results showed that biglycan signaling supported fetal membrane remodeling during early gestation in the absence of concomitant changes in TGFβ levels. In late gestation, biglycan signaling acted in a TGFβ-dependent manner to aid in membrane stabilization. In contrast, decorin signaling supported fetal membrane remodeling at early stages of gestation in a TGFβ-dependent manner, and fetal membrane stabilization at later stages of gestation without changes in TGFβ levels. Furthermore, exogenous soluble decorin was capable of rescuing the TGFβ signaling pathway in fetal membrane mesenchymal cells. Collectively, these findings provide novel targets for manipulation of fetal membrane extracellular matrix stability and could represent novel targets for research on preventive strategies for preterm premature rupture of fetal membranes.

A mouse model of spontaneous preterm birth based on the genetic ablation of biglycan and decorin

Preterm premature rupture of membranes is responsible for one-third of preterm births. Ehlers-Danlos syndrome (EDS) is associated with preterm premature rupture of membranes in humans. In particular, an EDS variant is caused by a genetic mutation resulting in abnormal secretion of biglycan and decorin, two small leucine-rich proteoglycans highly expressed in reproductive tissues. Because biglycan/decorin null mutant (Bgn(-/-)Dcn(-/-)) mice demonstrate phenotypic changes similar to EDS, we used this model to test whether either biglycan or decorin or both play a role in the attainment of successful term gestation. Wild-type biglycan null mutant, decorin null mutant, and biglycan/decorin null mutant pregnancies were assessed for the length of gestation, pup and placenta weight, and litter size. Quantitative real-time PCR was performed to measure biglycan and decorin gene expression, and immunohistochemistry was performed to assess protein expression in placenta and fetal membranes at embryonic days E12, E15, and E18. Bgn(-/-)Dcn(-/-) dams displayed preterm birth, whereas the possession of at least two biglycan or decorin wild-type alleles was protective of preterm birth. The number of Bgn(-/-)Dcn(-/-) pups was decreased at postnatal day P1 but not at E18. Biglycan and decorin were upregulated in the placenta in the absence of each other and were developmentally regulated in fetal membranes, suggesting that these two proteoglycans demonstrate genetic complementation and contribute to gestational success in a dose-dependent manner. Thus, the biglycan/decorin null mutant mouse is a model of genetically induced preterm birth and perinatal loss. This model presents novel targets for preventive or therapeutic manipulation of preterm birth.

End-of-life care in a regional level IV neonatal intensive care unit after implementation of a palliative care initiative

Objective:We hypothesized that the implementation of a neonatal palliative care initiative will result in improved markers of end-of-life care.Study design:A retrospective and prospective chart review of neonatal intensive care unit deaths was performed for 24 months before, 16 months during and 24 months after the implementation of palliative care provider education and practice guidelines (n=106). Ancillary care, redirection of care, palliative medication usage and outcome meetings in the last 48 h of life and basic demographic data were compared between epochs. Parametric and nonparametric analysis was performed.Result:There was an increase in redirection of care and palliative medication usage and a decrease in variability of use of end-of-life interventions (P=0.012, 0.022 and <0.001).Conclusion:The implementation of a neonatal palliative care initiative was associated with increases in palliative interventions for neonates in their final 48 h of life, suggesting that such an initiative may enhance end-of-life care.

Uterine Dysfunction in Biglycan and Decorin Deficient Mice Leads to Dystocia during Parturition

Cesarean birth rates are rising. Uterine dysfunction, the exact mechanism of which is unknown, is a common indication for Cesarean delivery. Biglycan and decorin are two small leucine-rich proteoglycans expressed in the extracellular matrix of reproductive tissues and muscle. Mice deficient in biglycan display a mild muscular dystrophy, and, along with mice deficient in decorin, are models of Ehlers-Danlos Syndrome, a connective tissue anomaly associated with uterine rupture. As a variant of Ehlers-Danlos Syndrome is caused by a genetic mutation resulting in abnormal biglycan and decorin secretion, we hypothesized that biglycan and decorin play a role in uterine function. Thus, we assessed wild-type, biglycan, decorin and double knockout pregnancies for timing of birth and uterine function. Uteri were harvested at embryonic days 12, 15 and 18. Nonpregnant uterine samples of the same genotypes were assessed for tissue failure rate and spontaneous and oxytocin-induced contractility. We discovered that biglycan/decorin mixed double-knockout dams displayed dystocia, were at increased risk of delayed labor onset, and showed increased tissue failure in a predominantly decorin-dependent manner. In vitro spontaneous uterine contractile amplitude and oxytocin-induced contractile force were decreased in all biglycan and decorin knockout genotypes compared to wild-type. Notably, we found no significant compensation between biglycan and decorin using quantitative real time PCR or immunohistochemistry. We conclude that the biglycan/decorin mixed double knockout mouse is a model of dystocia and delayed labor onset. Moreover, decorin is necessary for uterine function in a dose-dependent manner, while biglycan exhibits partial compensatory mechanisms in vivo. Thus, this model is poised for use as a model for testing novel targets for preventive or therapeutic manipulation of uterine dysfunction.

Altered Decorin and Smad Expression in Human Fetal Membranes in PPROM

ABSTRACT Humans with Ehlers-Danlos syndrome, a subtype of which is caused by abnormal decorin expression, are at increased risk of preterm birth due to preterm premature rupture of fetal membranes (PPROM). In the mouse model, the absence of decorin leads to fetal membrane abnormalities, preterm birth, and dysregulation of decorins downstream pathway components, including the transcription factor p-Smad-2. However, the role of decorin and p-Smad-2 in idiopathic human PPROM is unknown. Fetal membranes from 20–25 pregnancies per group were obtained as a cross-sectional sample of births at one institution between January 2010 and December 2012. The groups were term, preterm without PPROM, and preterm with PPROM. Immunohistochemical analysis of fetal membranes was performed for decorin and p-Smad-2 using localization and quantification assessment. Decorin expression is developmentally regulated in fetal membranes and is decreased in preterm birth with PPROM compared to preterm birth without PPROM. In preterm with PPROM samples, the presence of infection is associated with significant decorin downregulation compared to preterm with PPROM samples without infection. The preterm with PPROM group exhibited decreased p-Smad-2 staining compared to both the term controls and the preterm-without-PPROM group. Our findings suggest that dysregulation of decorin and its downstream pathway component p-Smad-2 occurs in fetal membranes during the second trimester in pathological pregnancies, thus supporting a role for decorin and p-Smad-2 in the pathophysiology of fetal membranes and adverse pregnancy outcomes. These findings may lead to the discovery of new targets for the diagnosis and treatment of PPROM.

Seeking the best training model for difficult conversations in neonatology.

Abstract Objectives: We hypothesize that a formal simulation curriculum prepares neonatology fellows for difficult conversations better than traditional didactics. Methods: Single-center neonatology fellowship graduates from 1999 to 2013 were sent a retrospective web-based survey. Some had been exposed to a Difficult Conversations curriculum (simulation group), others had not (no simulation group). The simulation group participated in one workshop annually, consisting of lecture, simulation, and debriefing. Scenarios were customized to year of training. Epoch comparisons were made between the simulation and no simulation groups. Results: Self-rated baseline effectiveness at discussing difficult topics was not different. The simulation group reported more supervised family meetings and feedback after fellow-led meetings. Simulations were rated very positively. The simulation group reported increased comfort levels. Strategic pause and body positioning were specific communication skills more frequently acquired in the simulation group. In both groups, the highest ranked contributors to learning were mentor observation and clinical practice. In the simulation group, simulation and debriefing outranked didactics or other experiences. Conclusions: Simulation-based workshops improve communication skills in high stakes conversations. However, they do not substitute for mentor observation and experience. Establishing a structured simulation-based difficult conversations curriculum refines vital communication skills necessary for the high stakes conversations neonatologists direct in clinical practice.

Compensatory fetal membrane mechanisms between biglycan and decorin in inflammation

Preterm premature rupture of fetal membranes (PPROM) is associated with infection, and is one of the most common causes of preterm birth. Abnormal expression of biglycan and decorin, two extracellular matrix proteoglycans, leads to preterm birth and aberrant fetal membrane morphology and signaling in the mouse. In humans and mice, decorin dysregulation is associated with inflammation in PPROM. We therefore investigated the link between biglycan and decorin and inflammation in fetal membranes using mouse models of intraperitoneal Escherichia coli injections superimposed on genetic biglycan and decorin deficiencies. We assessed outcomes in vivo as well as in vitro using quantitative PCR, Western blotting, and enzyme‐linked immunosorbent assays. Our results suggest that biglycan and decorin compensate for each other in the fetal membranes, but lose the ability to do so under inflammation, leading to decreased latency to preterm birth. Furthermore, our findings suggest that biglycan and decorin play discrete roles in fetal membrane signaling pathways during inflammation, leading to changes in the abundance of MMP8 and collagen α1VI, two components of the fetal membrane extracellular matrix that influence the pathophysiology of PPROM. In summary, these findings underline the importance of biglycan and decorin as targets for the manipulation of fetal membrane extracellular matrix stability in the context of inflammation. Mol. Reprod. Dev. 82: 387–396, 2015.