Variations in CRHR1 are associated with persistent pulmonary hypertension of the newborn

Early Pulmonary Hypertension in Preterm Infants

Pulmonary hypertension (PH) in preterm neonates has multifactorial pathogenesis with unique characteristics. Premature surfactant-deficient lungs are injured following exposure to positive pressure ventilation and high oxygen concentrations resulting in variable phenotypes of PH. The prevalence of early PH is variable and reported to be between 8% and 55% of extremely preterm infants. Disruption of the lung development and vascular signaling pathway could lead to abnormal pulmonary vascular transition. The management of early PH and the off-label use of selective pulmonary vasodilators continue to be controversial.

Evidence-Based Guidelines for Acute Stabilization and Management of Neonates with Persistent Pulmonary Hypertension of the Newborn

Persistent pulmonary hypertension of the newborn, or PPHN, represents a challenging condition associated with high morbidity and mortality. Management is complicated by complex pathophysiology and limited neonatal specific evidence-based literature, leading to a lack of universal contemporary clinical guidelines for the care of these patients. To address this need and to provide consistent high-quality clinical care for this challenging population in our neonatal intensive care unit, we sought to develop a comprehensive clinical guideline for the acute stabilization and management of neonates with PPHN. Utilizing cross-disciplinary expertise and incorporating an extensive literature search to guide best practice, we present an approachable, pragmatic, and clinically relevant guide for the bedside management of acute PPHN. KEY POINTS: · PPHN is associated with several unique diagnoses; the associated pathophysiology is different for each unique diagnosis.. · PPHN is a challenging, dynamic, and labile process for which optimal care requires frequent reassessment.. · Key management goals are adequate tissue oxygen delivery, avoiding harm..

Genome-wide association study identifies WWC2 as a possible locus associated with persistent pulmonary hypertension of the newborn in the Thai population

BACKGROUND

There is known to be significant genetic involvement in persistent pulmonary hypertension of the newborn (PPHN), but to date there is not a clear understanding of this situation, and clarifying that involvement would be of considerable assistance in devising effective treatments for the disease. This case-control study was undertaken to search for genetic variants associated with PPHN in the Thai population using a genome-wide association study (GWAS).

METHODS

A 659,184 single nucleotide polymorphisms from 387 participants (54 PPHN cases and 333 healthy participants) were genotyped across the human genome using an Illumina Asian Screening Array-24 v1.0 BeadChip Array. After quality control, we obtained 443,063 autosomal SNPs for the GWAS analysis. The FaST-LMM and R packages were used for all statistical analyses.

RESULTS

For the case-control analysis, the genomic inflation factor (λ) was 1.016, rs149768622 T>C in the first intron of WWC2 gene showed the strongest association with a P value of 3.76E-08 and odds ratio (OR) of 13.24 (95% CI: 3.91-44.78). The variants at the LOC102723906/LOC105377599, CADM4, GPM6A, CIT, RIMBP2, LOC105374510, LOC105375193, PTPRN2, CDK14, and LCORL loci showed suggestive evidence of associations with PPHN (P<1E-05).

CONCLUSIONS

This GWAS found that rs149768622 T>C in the WWC2 gene was possibly associated with PPHN. However, replication and functional studies are needed to validate this association and further explore the role(s) of the WWC2 gene in PPHN.

Correlating SFTPC gene variants to interstitial lung disease in Egyptian children

Background

Interstitial lung disease (ILD) is a broad heterogeneous group of lung disorders that is characterized by inflammation of the lungs. Surfactant dysfunction disorders are a rare form of ILD diseases that result from mutations in surfactant protein C gene (SFTPC) with prevalence of approximately 1/1.7 million births. SFTPC patients are presented with clinical manifestations of ILD ranging from fatal respiratory failure of newborn to chronic respiratory problems in children. In the current study, we aimed to investigate the spectrum of SFTPC genetic variants as well as the correlation of the SFTPC gene mutations with ILD disease in twenty unrelated Egyptian children with diffuse lung disease and suspected surfactant dysfunction using Sanger sequencing.

Results

Sequencing of SFTPC gene revealed five variants: c.42+35G>A (IVS1+35G>A) (rs8192340) and c.43-21T>C (IVS1-21T>C) (rs13248346) in intron 1, c.436-8C>G (IVS4-8C>G) (rs2070687) in intron 4, c.413C>A p.T138N (rs4715) in exon 4, and c.557G>Ap.S186N (rs1124) in exon 5.

Conclusion

The present study confirms the association of detecting variants of SFTPC with surfactant dysfunction disorders.

Pulmonary hypertension in the newborn- etiology and pathogenesis

A disruption in the well-orchestrated fetal-to-neonatal cardiopulmonary transition at birth results in the clinical conundrum of severe hypoxemic respiratory failure associated with elevated pulmonary vascular resistance (PVR), referred to as persistent pulmonary hypertension of the newborn (PPHN). In the past three decades, the advent of surfactant, newer modalities of ventilation, inhaled nitric oxide, other pulmonary vasodilators, and finally extracorporeal membrane oxygenation (ECMO) have made giant strides in improving the outcomes of infants with PPHN. However, death or the need for ECMO occurs in 10-20% of term infants with PPHN. Better understanding of the etiopathogenesis of PPHN can lead to physiology-driven management strategies. This manuscript reviews the fetal circulation, cardiopulmonary transition at birth, etiology, and pathophysiology of PPHN.

Possible association between a polymorphism of EPAS1 gene and persistent pulmonary hypertension of the newborn: a case-control study

OBJECTIVE

To explore possible genes related to the development of persistent pulmonary hypertension of the newborn (PPHN).

METHODS

The authors identified 285 single nucleotide polymorphisms (SNPs) of 11 candidate genes (BMPR2, EPAS1, PDE3A, VEGFA, ENG, NOTCH3, SOD3, CPS1, ABCA3, ACVRL1, and SMAD9), using an Illumina Asian Screening Array-24 v1.0 BeadChip Array. The FastLmmC and R package was used for statistical analyses. The chi-square test and Cochrane-Armitage trend test were used to compare the allele and genotype frequencies between the groups and to test the genetic models, respectively.

RESULTS

A total of 45 PPHN infants and 294 control subjects were analyzed. The most common cause of PPHN was meconium aspiration syndrome. Among the 285 SNPs, 17 SNPs from 6 candidate genes (BMPR2, EPAS1, PDE3A, VEGFA, ENG, and NOTCH3) were significantly associated with PPHN (P < 0.05). After using the Bonferroni correction (P < 0.00018), only the rs17034984 SNP located in intron 1 of the EPAS1 gene remained significantly different between the PPHN and control subjects (P = 0.00014). The frequency of the TC/TT genotype of rs17034984 in the gene with the dominant model was significant in the patients with PPHN (OR = 5.38, 95% CI: 2.15-13.49). The T allele frequency of rs17034984 in the gene showed a significant difference compared with the control subjects (OR = 4.89, 95% CI: 2.03-11.82).

CONCLUSIONS

The present study suggests that the rs17034984 variant of EPAS1 gene is associated with PPHN.

Association between genetic variations in carbamoyl-phosphate synthetase gene and persistent neonatal pulmonary hypertension

Persistent pulmonary hypertension of the new-borns (PPHN) is one of the main etiologies of morbidity as well as mortality in neonates. Previous studies found that genetic polymorphisms in urea cycle enzymes are associated with PPHN. Few of the genetic polymorphisms in neonates have been recognized with PPHN. We aimed to find out the prevalence of the CPS-I gene polymorphism and to correlate the genotype with the serum nitric oxide (NO) levels in Egyptian neonates with idiopathic PPHN. We included neonates diagnosed with PPH (n = 150) while the control group included healthy neonates with matched age and sex (n = 100). The CPS-I gene polymorphism: A/C, trans-version substitution, rs4399666 genotype was identified using TaqMan-based quantitative PCR. The results revealed that the CPS-I A/C rs4399666 gene polymorphism and lower serum NO levels were significantly associated with idiopathic PPHN in neonates. In addition, serum NO level was significantly associated with an rs4366999 A/C variant gene in idiopathic PPHN (p = 0.001). Univariable regression analysis demonstrated that there was a significant association between CPS-I A/C rs4399666 CC and increased risk of PPHN (odd ratio, 95% CI of 1.8 (0.78 to 1.75), p-value = 0.04).Conclusion: We concluded that mutant CPS-I A/C rs4399666 minor variant especially the homozygous CC genotype is frequently distributed among the PPHN group. This demonstrates that the presence of mutant CPS-I rs4399666 does not necessarily predispose to the development of PPHN in neonates, but nonetheless, if the C allele is inherited in the homozygous CC genotype, it is associated with a higher risk of PPHN. What is Known: • Prior studies found that polymorphisms in urea cycle enzyme genes are associated with PPHN. • Association between CPS-1 gene polymorphisms is significantly associated with PPHN. What is New: • The prevalence of CPS-1, A/C trans-version substitution, rs4399666 gene polymorphism in Egyptian neonates presented with idiopathic PPHN. • Mutant CPS-I A/C rs4399666 especially the homozygous CC genotype is more frequently distributed among PPHN, and it is significantly associated with low serum nitric oxide level.

Nitric oxide activates AMPK by modulating PDE3A in human pulmonary artery smooth muscle cells

Phosphodiesterase 3 (PDE3), of which there are two isoforms, PDE3A and PDE3B, hydrolyzes cAMP and cGMP—cyclic nucleotides important in the regulation of pulmonary vascular tone. PDE3 has been implicated in pulmonary hypertension unresponsive to nitric oxide (NO); however, contributions of the two isoforms are not known. Furthermore, adenosine monophosphate‐activated protein kinase (AMPK), a critical regulator of cellular energy homeostasis, has been shown to be modulated by PDE3 in varying cell types. While AMPK has recently been implicated in pulmonary hypertension pathogenesis, its role and regulation in the pulmonary vasculature remain to be elucidated. Therefore, we utilized human pulmonary artery smooth muscle cells (hPASMC) to test the hypothesis that NO increases PDE3 expression in an isoform‐specific manner, thereby activating AMPK and inhibiting hPASMC proliferation. We found that in hPASMC, NO treatment increased PDE3A protein expression and PDE3 activity with a concomitant decrease in cAMP concentrations and increase in AMPK phosphorylation. Knockdown of PDE3A using siRNA transfection blunted the NO‐induced AMPK activation, indicating that PDE3A plays an important role in AMPK regulation in hPASMC. Treatment with a soluble guanylate cyclase (sGC) stimulator increased PDE3A expression and AMPK activation similar to that seen with NO treatment, whereas treatment with a sGC inhibitor blunted the NO‐induced increase in PDE3A and AMPK activation. These results suggest that NO increases PDE3A expression, decreases cAMP, and activates AMPK via the sGC‐cGMP pathway. We speculate that NO‐induced increases in PDE3A and AMPK may have implications in the pathogenesis and the response to therapies in pulmonary hypertensive disorders.

The use of supplemental hydrocortisone in the management of persistent pulmonary hypertension of the newborn

OBJECTIVE

Characterize association between hydrocortisone receipt and hospital outcomes of infants with persistent pulmonary hypertension of the newborn (PPHN).

STUDY DESIGN

Cohort study of infants ≥34 weeks with PPHN who received inhaled nitric oxide at <7 days of age (2010-2016). We generated propensity scores, and performed inverse probability-weighted regression to estimate hydrocortisone effect on outcomes: death, chronic lung disease (CLD), oxygen at discharge.

RESULTS

Of 2743 infants, 30% received hydrocortisone, which was associated with exposure to mechanical ventilation, sedatives, paralytics, or vasopressors (p < 0.001). There was no difference in death, CLD, or oxygen at discharge. In infants with meconium aspiration syndrome, hydrocortisone was associated with decreased oxygen at discharge (odds ratio 0.56; 95% confidence interval 0.21, 0.91).

CONCLUSIONS

There was no association between hydrocortisone receipt and death, CLD, or oxygen at discharge in our cohort. Prospective studies are needed to evaluate the effectiveness of hydrocortisone in infants with PPHN.

Persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension of the newborn (PPHN) is a significant clinical problem characterized by refractory and severe hypoxemia secondary to elevated pulmonary vascular resistance resulting in right-to-left extrapulmonary shunting of deoxygenated blood. PPHN is associated with diverse cardiopulmonary disorders and a high early mortality rate for infants with severe PPHN. Surviving infants with PPHN have an increased risk of long-term morbidities. PPHN physiology can be categorized by (1) maladaptation: pulmonary vessels have normal structure and number but have abnormal vasoreactivity; (2) excessive muscularization: increased smooth muscle cell thickness and increased distal extension of muscle to vessels that are usually not muscularized; and (3) underdevelopment: lung hypoplasia associated with decreased pulmonary artery number. Treatment involves adequate lung recruitment, optimization of cardiac output and left ventricular function, and pulmonary vasodilators such as inhaled nitric oxide. Infants who fail to respond to conventional therapy should be evaluated for lethal lung disorders including alveolar-capillary dysplasia, T-box transcription factor 4 gene, thyroid transcription factor-1, ATP-binding cassette A3 gene, and surfactant protein diseases.

Genes that drive the pathobiology of pediatric pulmonary arterial hypertension

Emerging data from studies of pediatric-onset pulmonary arterial hypertension (PAH) indicate that the genomics of pediatric PAH is different than that of adults. There is a greater genetic burden in children, with rare genetic factors contributing to at least 35% of pediatric-onset idiopathic PAH (IPAH) compared with ~11% of adult-onset IPAH. De novo variants are the most frequent genetic cause of PAH in children, likely contributing to ~15% of all cases. Rare deleterious variants in bone morphogenetic protein receptor 2 (BMPR2) contribute to pediatric-onset familial PAH and IPAH with similar frequency as adult-onset. While likely gene-disrupting (LGD) variants in BMPR2 contribute across the lifespan, damaging missense variants are more frequent in early-onset PAH. Rare deleterious variants in T-box 4-containing protein (TBX4) are more common in pediatric-compared with adult-onset PAH, explaining ~8% of pediatric IPAH. PAH associated with congenital heart disease (APAH-CHD) and other developmental disorders account for a large proportion of pediatric PAH. SRY-related HMG box transcription factor (SOX17) was recently identified as an APAH-CHD risk gene, contributing less frequently to IPAH, with a greater prevalence of rare deleterious variants in children compared with adults. The differences in genetic burden and genes underlying pediatric- vs adult-onset PAH indicate that genetic information relevant to pediatric PAH cannot be extrapolated from adult studies. Large cohorts of pediatric-onset PAH are necessary to identify the unique etiological differences of PAH in children, as well as the natural history and response to therapy.

Genetics and Genomics of Pediatric Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare disease with high mortality despite recent therapeutic advances. The disease is caused by both genetic and environmental factors and likely gene-environment interactions. While PAH can manifest across the lifespan, pediatric-onset disease is particularly challenging because it is frequently associated with a more severe clinical course and comorbidities including lung/heart developmental anomalies. In light of these differences, it is perhaps not surprising that emerging data from genetic studies of pediatric-onset PAH indicate that the genetic basis is different than that of adults. There is a greater genetic burden in children, with rare genetic factors contributing to ~42% of pediatric-onset PAH compared to ~12.5% of adult-onset PAH. De novo variants are frequently associated with PAH in children and contribute to at least 15% of all pediatric cases. The standard of medical care for pediatric PAH patients is based on extrapolations from adult data. However, increased etiologic heterogeneity, poorer prognosis, and increased genetic burden for pediatric-onset PAH calls for a dedicated pediatric research agenda to improve molecular diagnosis and clinical management. A genomics-first approach will improve the understanding of pediatric PAH and how it is related to other rare pediatric genetic disorders.

Pharmacologic Management of Severe Bronchopulmonary Dysplasia

Few medications are available and well tested to treat infants who already have developed or inevitably will develop severe bronchopulmonary dysplasia (sBPD). Infants who develop sBPD clearly have not benefited from decades of research efforts to identify clinically meaningful preventive therapies for very preterm infants in the first days and weeks of their postnatal lives. This review addresses challenges to individualized approaches to medication use for sBPD. Specific challenges include understanding the combination of an individual infant's postmenstrual and postnatal age and the developmental status of drug-metabolizing enzymes and receptor expression. This review will also explore the reasons for the variable responsiveness of infants to specific therapies, based on current understanding of developmental pharmacology and pharmacogenetics. Data demonstrating the remarkable variability in the use of commonly prescribed drugs for sBPD are presented, and a discussion about the current use of some of these medications is provided. Finally, the potential use of antifibrotic medications in late-stage sBPD, which is characterized by a profibrotic state, is addressed.

Genetics and Other Omics in Pediatric Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare disease with high mortality despite therapeutic advances. Clinical management of children with PAH is particularly challenging because of increased complexity of disease etiology and clinical presentation, and the lack of data from pediatric-specific clinical trials. In children, PAH often develops in association with congenital heart disease and other developmental disorders. Emerging data from genetic studies of pediatric-onset PAH indicate that the genetic basis is different than that of adults. There is a greater genetic burden in children, with rare genetic factors contributing to at least 35% of pediatric-onset idiopathic PAH (IPAH) compared with approximately 11% of adult-onset IPAH. De novo variants are the most frequent monogenetic cause of PAH in children, likely contributing to approximately 15% of all cases. Rare deleterious variants in BMPR2 contribute to pediatric-onset IPAH and familial PAH with similar frequency as adult-onset disease but rarely explain cases of PAH associated with other diseases. Rare deleterious variants in developmental genes-including TBX4, SOX17, and other genes requiring confirmation in larger cohorts-are emerging as important contributors to pediatric-onset disease. Because each causal gene contributes to only a small number of cases, large cohorts of pediatric-onset PAH are needed to further identify the unique etiologic differences of PAH in children. We propose a genetics-first approach followed by focused phenotyping of pediatric patients grouped by genetic diagnosis to define endophenotypes that can be used to improve risk stratification and treatment.

Persistent Pulmonary Hypertension of the Newborn: Pathophysiological Mechanisms and Novel Therapeutic Approaches

Persistent pulmonary hypertension of the newborn (PPHN) is one of the main causes of neonatal morbidity and mortality. It is characterized by sustained elevation of pulmonary vascular resistance (PVR), preventing an increase in pulmonary blood flow after birth. The affected neonates fail to establish blood oxygenation, precipitating severe respiratory distress, hypoxemia, and eventually death. Inhaled nitric oxide (iNO), the only approved pulmonary vasodilator for PPHN, constitutes, alongside supportive therapy, the basis of its treatment. However, nearly 40% of infants are iNO resistant. The cornerstones of increased PVR in PPHN are pulmonary vasoconstriction and vascular remodeling. A better understanding of PPHN pathophysiology may enlighten targeted and more effective therapies. Sildenafil, prostaglandins, milrinone, and bosentan, acting as vasodilators, besides glucocorticoids, playing a role on reducing inflammation, have all shown potential beneficial effects on newborns with PPHN. Furthermore, experimental evidence in PPHN animal models supports prospective use of emergent therapies, such as soluble guanylyl cyclase (sGC) activators/stimulators, l-citrulline, Rho-kinase inhibitors, peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists, recombinant superoxide dismutase (rhSOD), tetrahydrobiopterin (BH4) analogs, ω-3 long-chain polyunsaturated fatty acids (LC-PUFAs), 5-HT2A receptor antagonists, and recombinant human vascular endothelial growth factor (rhVEGF). This review focuses on current knowledge on alternative and novel pathways involved in PPHN pathogenesis, as well as recent progress regarding experimental and clinical evidence on potential therapeutic approaches for PPHN.

Identification of genetic factors underlying persistent pulmonary hypertension of newborns in a cohort of Chinese neonates

Background

Persistent pulmonary hypertension of the newborn (PPHN) is a severe clinical problem among neonatal intensive care unit (NICU) patients. The genetic pathogenesis of PPHN is unclear. Only a few genetic polymorphisms have been identified in infants with PPHN. Our study aimed to investigate the potential genetic etiology of PPHN.

Methods

This study recruited PPHN patients admitted to the NICU of the Children’s Hospital of Fudan University from Jan 2016 to Dec 2017. Exome sequencing was performed for all patients. Variants in reported PPHN/pulmonary arterial hypertension (PAH)-related genes were assessed. Single nucleotide polymorphism (SNP) association and gene-level analyses were carried out in 74 PPHN cases and 115 non-PPHN controls with matched baseline characteristics.

Results

Among the patient cohort, 74 (64.3%) patients were late preterm and term infants (≥ 34 weeks gestation) and 41 (35.7%) were preterm infants (< 34 weeks gestation). Preterm infants with PPHN exhibited low birth weight and a high frequency of bronchopulmonary dysplasia, respiratory distress syndrome (RDS) and mortality. Nine patients (only one preterm infant) were identified as harboring genetic variants, including three with pathogenic/likely pathogenic variants in TBX4 and BMPR2 and six with variants of unknown significance in BMPR2, SMAD9, TGFB1, KCNA5 and TRPC6. Three SNPs (rs192759073, rs1047883 and rs2229589) in CPS1 and one SNP (rs1044008) in NOTCH3 were significantly associated with PPHN (p < 0.05). CPS1 and SMAD9 were identified as risk genes for PPHN (p < 0.05).

Conclusions

In this study, we identified genetic variants in PPHN patients, and we reported CPS1, NOTCH3 and SMAD9 as risk genes for late preterm and term PPHN in a single-center Chinese cohort. Our findings provide additional genetic evidence of the pathogenesis of PPHN and new insight into potential strategies for disease treatment.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1148-1) contains supplementary material, which is available to authorized users.

Genetic variation in CRHR1 is associated with short-term respiratory response to corticosteroids in preterm infants at risk for bronchopulmonary dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) is an orphan disease and advances in prevention and treatment are lacking. The clinical efficacy of systemic corticosteroid therapy to reduce the severity of lung disease and BPD is highly variable. Our objective was to assess whether candidate SNPs in corticosteroid metabolism and response genes are associated with short-term phenotypic response to systemic corticosteroids in infants at high risk for BPD.

METHODS

Pharmacogenetic analysis of data from a large randomized controlled trial (TOLSURF) in infants treated with dexamethasone or hydrocortisone using multivariate linear regression. The primary outcome was a change in respiratory severity score (RSS, mean airway pressure x FiO2) at day 7 of corticosteroid treatment.

RESULTS

rs7225082 in the intron of CRHR1 is significantly associated with the magnitude of decrease in RSS 7 days after starting treatment with systemic corticosteroid (meta-analysis P = 2.8 × 10^-4). Each T allele at rs7225082 is associated with a smaller absolute change in RSS at day 7, i.e., less response to systemic corticosteroids.

CONCLUSIONS

Genetic variability is associated with corticosteroid responsiveness with regard to respiratory status in preterm infants. Identification of genetic markers of corticosteroid responsiveness may allow for therapeutic individualization, with the goal of optimizing the risk-to-benefit ratio for an individual child.

Genetic Association of Pulmonary Surfactant Protein Genes, SFTPA1, SFTPA2, SFTPB, SFTPC, and SFTPD With Cystic Fibrosis

Surfactant proteins (SP) are involved in surfactant function and innate immunity in the human lung. Both lung function and innate immunity are altered in CF, and altered SP levels and genetic association are observed in Cystic Fibrosis (CF). We hypothesized that single nucleotide polymorphisms (SNPs) within the SP genes associate with CF or severity subgroups, either through single SNP or via SNP-SNP interactions between two SNPs of a given gene (intragenic) and/or between two genes (intergenic). We genotyped a total of 17 SP SNPs from 72 case-trio pedigree (SFTPA1 (5), SFTPA2 (4), SFTPB (4), SFTPC (2), and SFTPD (2)), and identified SP SNP associations by applying quantitative genetic principles. The results showed (a) Two SNPs, SFTPB rs7316 (p = 0.0083) and SFTPC rs1124 (p = 0.0154), each associated with CF. (b) Three intragenic SNP-SNP interactions, SFTPB (rs2077079, rs3024798), and SFTPA1 (rs1136451, rs1059057 and rs4253527), associated with CF. (c) A total of 34 intergenic SNP-SNP interactions among the 4 SP genes to be associated with CF. (d) No SNP-SNP interaction was observed between SFTPA1 or SFTPA2 and SFTPD. (e) Equal number of SNP-SNP interactions were observed between SFTPB and SFTPA1/SFTPA2 (n = 7) and SP-B and SFTPD (n = 7). (f) SFTPC exhibited significant SNP-SNP interactions with SFTPA1/SFTPA2 (n = 11), SFTPB (n = 4) and SFTPD (n = 3). (g) A single SFTPB SNP was associated with mild CF after Bonferroni correction, and several intergenic interactions that are associated (p < 0.01) with either mild or moderate/severe CF were observed. These collectively indicate that complex SNP-SNP interactions of the SP genes may contribute to the pulmonary disease in CF patients. We speculate that SPs may serve as modifiers for the varied progression of pulmonary disease in CF and/or its severity.

Beyond the inhaled nitric oxide in persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension (PPHN) is a consequence of failed pulmonary vascular transition at birth and leads to pulmonary hypertension with shunting of deoxygenated blood across the ductus arteriosus (DA) and foramen ovale (FO) resulting in severe hypoxemia, and it may eventually lead to life-threatening circulatory failure. PPHN is a serious event affecting both term and preterm infants in the neonatal intensive care unit. It is often associated with diseases such as congenital diaphragmatic hernia, meconium aspiration, sepsis, congenital pneumonia, birth asphyxia and respiratory distress syndrome. The diagnosis of PPHN should include echocardiographic evidence of increased pulmonary pressure, with demonstrable right-to-left shunt across the DA or FO, and the absence of cyanotic heart diseases. The mainstay therapy of PPHN includes treatment of underlying causes, maintenance of adequate systemic blood pressure, optimized ventilator support for lung recruitment and alveolar ventilation, and pharmacologic measures to increase pulmonary vasodilation and decrease pulmonary vascular resistance. Inhaled nitric oxide has been proved to treat PPHN successfully with improved oxygenation in 60-70% of patients and to significantly reduce the need for extracorporeal membrane oxygenation (ECMO). About 14%-46% of the survivors develop long-term impairments such as hearing deficits, chronic lung disease, cerebral palsy and other neurodevelopmental disabilities.

Polymorphisms in urea cycle enzyme genes are associated with persistent pulmonary hypertension of the newborn

BackgroundPersistent pulmonary hypertension of the newborn (PPHN) is characterized by elevated pulmonary vascular resistance. Endogenous nitric oxide is critical for regulation of pulmonary vascular resistance. Nitric oxide is generated from L-arginine, supplied by the urea cycle (UC). We hypothesized that polymorphisms in UC enzyme genes and low concentrations of UC intermediates are associated with PPHN.MethodsWe performed a family-based candidate gene analysis to study 48 single-nucleotide polymorphisms (SNPs) in six UC enzyme genes. Genotyping was carried out in 94 infants with PPHN and their parents. We also performed a case-control analysis of 32 cases with PPHN and 64 controls to identify an association between amino-acid levels on initial newborn screening and PPHN.ResultsThree SNPs (rs41272673, rs4399666, and rs2287599) in carbamoyl phosphate synthase 1 gene (CPS1) showed a significant association with PPHN (P=0.02). Tyrosine levels were significantly lower (P=0.003) and phenylalanine levels were significantly higher (P=0.01) in cases with PPHN. There was no difference in the arginine or citrulline levels between the two groups.ConclusionsThis study suggests an association (P<0.05) between SNPs in CPS1 and PPHN. These findings warrant further replication in larger cohorts of patients.

Persistent pulmonary hypertension of the newborn

Failure of the normal circulatory adaptation to extrauterine life results in persistent pulmonary hypertension of the newborn (PPHN). Although this condition is most often secondary to parenchymal lung disease or lung hypoplasia, it may also be idiopathic. PPHN is characterized by elevated pulmonary vascular resistance with resultant right-to-left shunting of blood and hypoxemia. Although the preliminary diagnosis of PPHN is often based on differential cyanosis and labile hypoxemia, the diagnosis is confirmed by echocardiography. Management strategies include optimal lung recruitment and use of surfactant in patients with parenchymal lung disease, maintaining optimal oxygenation and stable blood pressures, avoidance of respiratory and metabolic acidosis and alkalosis, and pulmonary vasodilator therapy. Extracorporeal membrane oxygenation is considered when medical management fails. Although mortality associated with PPHN has decreased significantly with improvements in medical care, there remains the potential risk for neurodevelopmental disability which warrants close follow-up of affected infants after discharge.

Keratin mediated attachment of stem cells to augment cardiomyogenic lineage commitment

The objective of this work was to develop a simple surface modification technique using keratin derived from human hair for efficient cardiomyogenic lineage commitment of human mesenchymal stem cells (hMSCs). Keratin was extracted from discarded human hair containing both the acidic and basic components along with the heterodimers. The extracted keratin was adsorbed to conventional tissue culture polystyrene surfaces at different concentration. Keratin solution of 500μg/ml yielded a well coated layer of 12±1nm thickness with minimal agglomeration. The keratin coated surfaces promoted cell attachment and proliferation. Large increases in the mRNA expression of known cardiomyocyte genes such as cardiac actinin, cardiac troponin and β-myosin heavy chain were observed. Immunostaining revealed increased expression of sarcomeric α-actinin and tropomyosin whereas Western blots confirmed higher expression of tropomyosin and myocyte enhancer factor 2C in cells on the keratin coated surface than on the non-coated surface. Keratin promoted DNA demethylation of the Atp2a2 and Nkx2.5 genes thereby elucidating the importance of epigenetic changes as a possible molecular mechanism underlying the increased differentiation. A global gene expression analysis revealed a significant alteration in the expression of genes involved in pathways associated in cardiomyogenic commitment including cytokine and chemokine signaling, cell-cell and cell-matrix interactions, Wnt signaling, MAPK signaling, TGF-β signaling and FGF signaling pathways among others. Thus, adsorption of keratin offers a facile and affordable yet potent route for inducing cardiomyogenic lineage commitment of stem cells with important implications in developing xeno-free strategies in cardiovascular regenerative medicine.

EDN1 Gene Variant is Associated with Neonatal Persistent Pulmonary Hypertension

Recent studies have suggested associations between certain genetic variants and susceptibility to persistent pulmonary hypertension of the newborn (PPHN). The aim of the study was to evaluate the association of EDN1, NOS3, ACE and VEGFA genes with PPHN. Neonates with respiratory distress were enrolled in the study, whose gestational age ≥34 weeks, age ≤3 days. They were divided into PPHN and non-PPHN group. The EDN1, NOS3, ACE and VEGFA genes were detected by next-generation sequencing, and the results were validated by Sanger sequencing. Serum endothelin-1 (ET-1) levels were quantified by ELISA. A total of 112 neonates were enrolled (n = 55 in PPHN group; n = 57 in non-PPHN group). There is a significantly difference in the genotype distribution of EDN1 rs2070699 between the PPHN and non-PPHN group (P = 0). A higher frequency of the rs2070699 T allele was observed in the PPHN group (54.5% vs 27.2%; OR = 3.89; 95%CI 1.96-7.72). The rs2070699 T allele was associated with higher ET-1 levels (3.333 ± 2.517 pg/mL vs 1.223 ± 0.856 pg/mL; P = 0.002) and a longer ventilation period (5.8 ± 2.6 days vs 3.6 ± 3.3 days; P = 0). The results suggest there is an association between EDN1 and PPHN. The presence of the rs2070699 T allele increased the risk of PPHN in neonates with respiratory distress.

Advances in Neonatal Pulmonary Hypertension

Persistent pulmonary hypertension of the newborn (PPHN) is a surprisingly common event in the neonatal intensive care unit, and affects both term and preterm infants. Recent studies have begun to elucidate the maternal, fetal and genetic risk factors that trigger PPHN. There have been numerous therapeutic advances over the last decade. It is now appreciated that oxygen supplementation, particularly for the goal of pulmonary vasodilation, needs to be approached as a therapy that has risks and benefits. Administration of surfactant or inhaled nitric oxide (iNO) therapy at a lower acuity of illness can decrease the risk of extracorporeal membrane oxygenation/death, progression of disease and duration of hospital stay. Milrinone may have specific benefits as an 'inodilator', as prolonged exposure to iNO plus oxygen may activate phosphodiesterase (PDE) 3A. Additionally, sildenafil and hydrocortisone may benefit infants exposed to hyperoxia and oxidative stress. Continued investigation is likely to reveal new therapies such as citrulline and cinaciguat that will enhance NO synthase and soluble guanylate cyclase function. Continued laboratory and clinical investigation will be needed to optimize treatment and improve outcomes.

Neonatal Genetic Variation in Steroid Metabolism and Key Respiratory Function Genes and Perinatal Outcomes in Single and Multiple Courses of Corticosteroids

OBJECTIVE

The aim of the study is to evaluate the association of steroid metabolism and respiratory gene polymorphisms in neonates exposed to antenatal corticosteroids (ACS) with respiratory outcomes, small for gestational age (SGA), and response to repeat ACS.

STUDY DESIGN

This candidate gene study is a secondary analysis of women enrolled in a randomized controlled trial of single versus weekly courses of ACS. Nineteen single nucleotide polymorphisms (SNPs) in 13 steroid metabolism and respiratory function genes were evaluated. DNA was extracted from placenta or fetal cord serum and analyzed with TaqMan genotyping. Each SNP was evaluated for association via logistic regression with respiratory distress syndrome (RDS), continuous positive airway pressure (CPAP)/ventilator use (CPV), and SGA.

RESULTS

CRHBP, CRH, and CRHR1 minor alleles were associated with an increased risk of SGA. HSD11B1 and SCNN1B minor alleles were associated with an increased likelihood of RDS. Carriage of minor alleles in SerpinA6 was associated with an increased risk of CPV. CRH and CRHR1 minor alleles were associated with a decreased likelihood of CPV.

CONCLUSION

Steroid metabolism and respiratory gene SNPs are associated with respiratory outcomes and SGA in patients exposed to ACS. Risks for respiratory outcomes are affected by minor allele carriage as well as by treatment with multiple ACS.

A Rare Cause of Persistent Pulmonary Hypertension Resistant to Therapy in The Newborn: Short-Rib Polydactyly Syndrome

Short-rib polydactyly syndrome is an autosomal recessively inherited lethal skeletal dysplasia. The syndrome is characterized by marked narrow fetal thorax, short extremities, micromelia, cleft palate/lip, polydactyly, cardiac and renal abnormalities, and genital malformations. In cases with pulmonary hypoplasia, persistent pulmonary hypertension of the newborn can develop. In this paper, we present a term newborn with persistent pulmonary hypertension of the newborn, which has developed secondary to short-rib polydactyly syndrome and was resistant to therapy with inhaled nitric oxide and oral sildenafil.

Molecular physiopathogenetic mechanisms and development of new potential therapeutic strategies in persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension of the newborn (PPHN) is a cyanogenic plurifactorial disorder characterized by failed postnatal drop of pulmonary vascular resistance and maintenance of right-to-left shunt across ductus arteriosus and foramen ovale typical of intrauterine life. The pathogenesis of PPHN is very complex and can result from functional (vasoconstriction) or structural (arteriolar remodeling, reduced pulmonary vessels density) anomalies of pulmonary circulation. Etiopathogenetic factors heterogeneity can strongly condition therapeutical results and prognosis of PPHN that is particularly severe in organic forms that are usually refractory to selective pulmonary vasodilator therapy with inhaled nitric oxide. This paper reports the more recent acquisitions on molecular physiopathogenetic mechanisms underlying functional and structural forms of PPHN and illustrates the bases for adoption of new potential treatment strategies for organic PPHN. These strategies aim to reverse pulmonary vascular remodeling in PPHN with arteriolar smooth muscle hypertrophy and stimulate pulmonary vascular and alveolar growth in PPHN associated with lung hypoplasia.In order to restore lung growth in this severe form of PPHN, attention is focused on the results of studies of mesenchymal stem cells and their therapeutical paracrine effects on bronchopulmonry dysplasia, a chronic neonatal lung disease characterized by arrested vascular and alveolar growth and development of pulmonary hypertension.

Update on PPHN: mechanisms and treatment

Persistent pulmonary hypertension of the newborn (PPHN) is a syndrome of failed circulatory adaptation at birth, seen in about 2/1000 live born infants. While it is mostly seen in term and near-term infants, it can be recognized in some premature infants with respiratory distress or bronchopulmonary dysplasia. Most commonly, PPHN is secondary to delayed or impaired relaxation of the pulmonary vasculature associated with diverse neonatal pulmonary pathologies, such as meconium aspiration syndrome, congenital diaphragmatic hernia, and respiratory distress syndrome. Gentle ventilation strategies, lung recruitment, inhaled nitric oxide, and surfactant therapy have improved outcome and reduced the need for extracorporeal membrane oxygenation (ECMO) in PPHN. Newer modalities of treatment discussed in this article include systemic and inhaled vasodilators like sildenafil, prostaglandin E1, prostacyclin, and endothelin antagonists. With prompt recognition/treatment and early referral to ECMO centers, the mortality rate for PPHN has significantly decreased. However, the risk of potential neurodevelopmental impairment warrants close follow-up after discharge for infants with PPHN.

Diagnosis and treatment of pulmonary hypertension in infancy

Normal pulmonary vascular development in infancy requires maintenance of low pulmonary vascular resistance after birth, and is necessary for normal lung function and growth. The developing lung is subject to multiple genetic, pathological and/or environmental influences that can adversely affect lung adaptation, development, and growth, leading to pulmonary hypertension. New classifications of pulmonary hypertension are beginning to account for these diverse phenotypes, and or pulmonary hypertension in infants due to PPHN, congenital diaphragmatic hernia, and bronchopulmonary dysplasia (BPD). The most effective pharmacotherapeutic strategies for infants with PPHN are directed at selective reduction of PVR, and take advantage of a rapidly advancing understanding of the altered signaling pathways in the remodeled vasculature.

The pulmonary circulation in neonatal respiratory failure

The pulmonary circulation rapidly adapts at birth to establish lungs as the site of gas exchange. Abnormal transition at birth and/or parenchymal lung disease can result in neonatal hypoxemic respiratory failure. This article reviews the functional changes in pulmonary hemodynamics and structural changes in pulmonary vasculature secondary to (1) normal and abnormal transition at birth, and (2) diseases associated with neonatal hypoxemic respiratory failure. Various management strategies to correct respiratory failure are also discussed.