Bone Morphogenetic Protein 9 Protects against Neonatal Hyperoxia-Induced Impairment of Alveolarization and Pulmonary Inflammation.

Aim: Effective treatment of premature infants with bronchopulmonary dysplasia (BPD) is lacking. We hypothesize that bone morphogenetic protein 9 (BMP9), a ligand of the TGF-β family that binds to the activin receptor-like kinase 1 (ALK1)-BMP receptor type 2 (BMPR2) receptor complex, may be a novel therapeutic option for BPD. Therefore, we investigated the cardiopulmonary effects of BMP9 in neonatal Wistar rats with hyperoxia-induced BPD. Methods: Directly after birth Wistar rat pups were exposed to 100% oxygen for 10 days. From day 2 rat pups received BMP9 (2.5 μg/kg, twice a day) or 0.9% NaCl by subcutaneous injection. Beneficial effects of BMP9 on aberrant alveolar development, lung inflammation and fibrosis, and right ventricular hypertrophy (RVH) were investigated by morphometric analysis and cytokine production. In addition, differential mRNA expression of BMP9 and its receptor complex: ALK1, BMPR2, and Endoglin, and of the ALK1 downstream target transmembrane protein 100 (TMEM100) were studied during the development of experimental BPD. Expression of the BMP9 receptor complex and TMEM100 was studied in human endothelial and epithelial cell cultures and the effect of BMP9 on inflammatory cytokine production and TMEM100 expression was studied in endothelial cell cultures. Results:ALK1, ALK2, BMPRII, TMEM100, and Endoglin were differentially expressed in experimental BPD, suggesting a role for BMP9-dependent signaling in the development of (experimental) BPD. TMEM100 was expressed in the wall of blood vessels, showing an elastin-like expression pattern in arterioles. Expression of TMEM100 mRNA and protein was decreased after exposure to hyperoxia. BMP9 treatment of rat pups with hyperoxia-induced experimental BPD reduced alveolar enlargement, lung septal thickness and fibrosis, and prevented inflammation, but did not attenuate vascular remodeling and RVH. The anti-inflammatory effect of BMP9 was confirmed in vitro. Highest expression of ALK1, BMPR2, and TMEM100 was observed in human endothelial cell cultures. Stimulation of human endothelial cell cultures with BMP9 reduced their pro-inflammatory cytokine response and induced TMEM100 expression in pulmonary arterial endothelial cells. Conclusion: BMP9 protects against neonatal hyperoxia-induced BPD by improving aberrant alveolar development, inflammation and fibrosis, demonstrating its therapeutic potential for premature infants with severe BPD

Expression patterns of protein C inhibitor in mouse development

Proteolysis of extracellular matrix is an important requirement for embryonic development and is instrumental in processes such as morphogenesis, angiogenesis, and cell migration. Efficient remodeling requires controlled spatio-temporal expression of both the proteases and their inhibitors. Protein C inhibitor (PCI) effectively blocks a range of serine proteases, and recently has been suggested to play a role in cell differentiation and angiogenesis. In this study, we mapped the expression pattern of PCI throughout mouse development using in situ hybridization and immunohistochemistry. We detected a wide-spread, yet distinct expression pattern with prominent PCI levels in skin including vibrissae, and in fore- and hindgut. Further sites of PCI expression were choroid plexus of brain ventricles, heart, skeletal muscles, urogenital tract, and cartilages. A strong and stage-dependent PCI expression was observed in the developing lung. In the pseudoglandular stage, PCI expression was present in distal branching tubules whereas proximal tubules did not express PCI. Later in development, in the saccular stage, PCI expression was restricted to distal bronchioli whereas sacculi did not express PCI. PCI expression declined in postnatal stages and was not detected in adult lungs. In general, embryonic PCI expression indicates multifunctional roles of PCI during mouse development. The expression pattern of PCI during lung development suggests its possible involvement in lung morphogenesis and angiogenesis

Therapeutic potential of soluble guanylate cyclase modulators in neonatal chronic lung disease

Supplemental oxygen after premature birth results in aberrant airway, alveolar and pulmonary vascular development with an increased risk for bronchopulmonary dysplasia (BPD), and development of wheeze and asthma, pulmonary hypertension and COPD in survivors. Although stimulation of the nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic GMP (cGMP) signal transduction pathway has significant beneficial effects on disease development in animal models, so far this could not be translated to the clinic. Oxidative stress reduces the NO-sGC-cGMP pathway by oxidizing heme-bound sGC, resulting in inactivation or degradation of sGC. Reduced sGC activity and/or expression is associated with pathology due to premature birth, oxidative stress-induced lung injury, including impaired alveolar maturation, smooth muscle cell (SMC) proliferation and contraction, impaired airway relaxation and vasodilation, inflammation, pulmonary hypertension, right ventricular hypertrophy and an aggravated response towards hyperoxia-induced neonatal lung injury. Recently, Britt et al. (10) demonstrated that histamine-induced Ca2+ responses were significantly elevated in hyperoxia-exposed fetal human airway SMC's compared to normoxic controls, and that this hyperoxia-induced increase in the response was strongly reduced by NO-independent stimulation and activation of sGC. These recent studies highlight the therapeutic potential of sGC modulators in the treatment of preterm infants for respiratory distress with supplemental oxygen. Such treatment is aimed at improving aberrant alveolar and vascular development of the neonatal lung, and preventing the development of wheezing and asthma in survivors of premature birth. In addition, these studies highlight the suitability of fetal human airway SMC's as a translational model for pathological airway changes in the neonate

Cigarette smoke differentially modulates dendritic cell maturation and function in time

BACKGROUND: Dendritic cells (DCs) as professional antigen presenting cells (APCs) play a critical role in the regulation of host immune responses. DCs evolve from immature, antigen-capturing cells, to mature antigen-presenting cells. The relative contribution of DCs to cigarette smoke-induced inflammation is not well documented. In the current study, we investigated a modulatory effect of cigarette smoke extract (CSE) on differentiation, maturation and function of DCs. METHODS: Primary murine DCs were grown from bone marrow cells with GM-CSF. Development of DC was analyzed by expression of CD11c, MHCII, CD86, CD40 and CD83 using flow cytometry. Murine DC's and human L428 cells were co-cultured with CSE for various periods of time. Functional activity was analyzed by measuring FITC-dextran uptake, cytokine production and the ability to stimulate T cell activation in a mixed lymphocyte reaction. RESULTS: Our results show that short-term CSE stimulation (~24 h) influence the maturation status of newly differentiated and immature DCs towards more mature cells as revealed by upregulation of MHCII, CD83, CD86, CD40, reduction in antigen up-take capacity and enhanced secretion of pro-inflammatory (IL-12, IL-6 and TNF-α) cytokines. Interestingly, long-term CSE exposure, time- and concentration-dependently, suppressed the development of functional DCs. This suppression was demonstrated by a decline in CD11c/MHCII, CD83, CD86 and CD40 expression, the production of cytokines and ability to stimulate T lymphocytes. Moreover, CSE significantly suppressed the endocytosis function of mouse DCs which was not due to diminished DC viability. Similar to mouse DCs, long-term co-culturing of the human L428 DC cell line with CSE time-dependently suppressed the expression of CD54. CONCLUSIONS: The present study provides evidence that CSE modulates DC-mediated immune responses via affecting both the function and maturation of DCs. The suppressive effects of cigarette smoke on DC function might lead to impaired immune responses to various infections

Apelin Attenuates Hyperoxic Lung and Heart Injury in Neonatal Rats

Rationale: Apelin, a potent vasodilator and angiogenic factor, may be a novel therapeutic agent in neonatal chronic lung disease, including bronchopulmonary dysplasia

Inhaled nitric oxide attenuates pulmonary inflammation and fibrin deposition and prolongs survival in neonatal hyperoxic lung injury

Administration of inhaled nitric oxide (iNO) is a potential therapeutic strategy to prevent bronchopulmonary dysplasia (BPD) in premature newborns with respiratory distress syndrome. We evaluated this approach in a rat model, in which premature pups were exposed to room air, hyperoxia, or a combination of hyperoxia and NO (8.5 and 17 ppm). We investigated the anti-inflammatory effects of prolonged iNO therapy by studying survival, histopathology, fibrin deposition, and differential mRNA expression (real-time RT-PCR) of key genes involved in the development of BPD. iNO therapy prolonged median survival 1.5 days (P = 0.0003), reduced fibrin deposition in a dosage-dependent way up to 4.3-fold (P <0.001), improved alveolar development by reducing septal thickness, and reduced the influx of leukocytes. Analysis of mRNA expression revealed an iNO-induced downregulation of genes involved in inflammation (IL-6, cytokine-induced neutrophilic chemoattractant-1, and amphiregulin), coagulation, fibrinolysis (plasminogen activator inhibitor 1 and urokinase-type plasminogen activator receptor), cell cycle regulation (p21), and an upregulation of fibroblast growth factor receptor-4 (alveolar formation). We conclude that iNO therapy improves lung pathology and prolongs survival by reducing septum thickness, inhibiting inflammation, and reducing alveolar fibrin deposition in premature rat pups with neonatal hyperoxic lung injur

Pro- and anti-inflammatory effects of short chain fatty acids on immune and endothelial cells

In the gastro-intestinal tract, short chain fatty acids (SCFAs) have protective effects on epithelial cells. However, their effects on inflammatory cytokine production by endothelial and immune cells and the recruitment of immune cells and their trans-migration across the endothelial layer remain controversial. Both cell types are associated with the initiation and development of inflammatory diseases, such as atherosclerosis and sepsis. SCFAs modulate immune and inflammatory responses via activation of free fatty acid (FFA) receptors type 2 and 3 (FFA2 and FFA3 receptors), G protein-coupled receptor 109A (GPR109A) and inhibition of histone deacetylases (HDACs). This review will focus on the effects of SCFAs on lipopolysaccharide (LPS)- or tumor necrosis factor-alpha (TNFα)-induced inflammatory response on endothelial and immune cells function, and an overview is presented on the underlying mechanisms of the effects of SCFAs on both immune and endothelial cells, including HDACs, FFA2 and FFA3 receptors and GPR109A regulation of nuclear factor-kappa B (NF-κB) activation and mitogen-activated protein kinase (MAPK) signaling pathways

Pro- and anti-inflammatory effects of short chain fatty acids on immune and endothelial cells

In the gastro-intestinal tract, short chain fatty acids (SCFAs) have protective effects on epithelial cells. However, their effects on inflammatory cytokine production by endothelial and immune cells and the recruitment of immune cells and their trans-migration across the endothelial layer remain controversial. Both cell types are associated with the initiation and development of inflammatory diseases, such as atherosclerosis and sepsis. SCFAs modulate immune and inflammatory responses via activation of free fatty acid (FFA) receptors type 2 and 3 (FFA2 and FFA3 receptors), G protein-coupled receptor 109A (GPR109A) and inhibition of histone deacetylases (HDACs). This review will focus on the effects of SCFAs on lipopolysaccharide (LPS)- or tumor necrosis factor-alpha (TNFα)-induced inflammatory response on endothelial and immune cells function, and an overview is presented on the underlying mechanisms of the effects of SCFAs on both immune and endothelial cells, including HDACs, FFA2 and FFA3 receptors and GPR109A regulation of nuclear factor-kappa B (NF-κB) activation and mitogen-activated protein kinase (MAPK) signaling pathways