Selectin polymorphisms and perinatal morbidity in low-birthweight infants

Phenotype wide association study links bronchopulmonary dysplasia with eosinophilia in children

Bronchopulmonary dysplasia (BPD) is a common complication of preterm birth. Despite this, genetic drivers of BPD are poorly understood. The objective of this study is to better understand the impact of single nucleotide polymorphisms (SNPs) previously associated with BPD by examining associations with other phenotypes. We drew pediatric subjects from the biorepository at the Center for Applied Genomics to identify associations between these SNPs and 2,146 imputed phenotypes. Methylation data, external cohorts, and in silico validation methods were used to corroborate significant associations. We identified 60 SNPs that were previously associated with BPD. We found a significant association between rs3771150 and rs3771171 and mean eosinophil percentage in a European cohort of 6,999 patients and replicated this in external cohorts. Both SNPs were also associated with asthma, COPD and FEV1/FVC ratio. These SNPs displayed associations with methylation probes and were functionally linked to ST2 (IL1RL1) levels in blood and lung tissue. Our findings support a genetic justification for the epidemiological link between BPD and asthma. Given the well-established link between ST2 and type 2 inflammation in asthma, these findings provide a rationale for future studies exploring the role of type 2 inflammation in the pathogenesis of BPD.

Genetics of bronchopulmonary dysplasia: An update

Bronchopulmonary dysplasia (BPD) is a multi-factorial disease that results from multiple clinical factors, including lung immaturity, mechanical ventilation, oxidative stress, pulmonary congestion due to increasing cardiac blood shunting, nutritional and immunological factors. Twin studies have indicated that susceptibility to BPD can be strongly inherited in some settings. Studies have reported associations between common genetic variants and BPD in preterm infants. Recent genomic studies have highlighted a potential role for molecular pathways involved in inflammation and lung development in affected infants. Rare mutations in genes encoding the lipid transporter ATP-binding cassette, sub-family A, member 3 (ABCA3 gene) which is involved in surfactant synthesis in alveolar type II cells, as well as surfactant protein B (SFTPB) and C (SFTPC) can also result in severe form of neonatal-onset interstitial lung diseases and may also potentially affect the course of BPD. This chapter summarizes the current state of knowledge on the genetics of BPD.

SELL and GUCY1A1 Gene Polymorphisms in Patients with Unstable Angina

Acute ischaemia is mostly caused by the rupture of an unstable atherosclerotic plaque in a coronary artery, resulting in platelet accumulation and thrombus formation, which closes the lumen of the coronary vessel. Many different factors can cause atherosclerotic plaques to occlude the lumen of a coronary artery, including factors that increase vascular inflammation and blood platelet aggregation, as well as genetic factors. L-selectin is an adhesion molecule encoded by the human SELL gene, playing an important role in leukocyte adhesion to the endothelium and the development of inflammation. Guanylate cyclase 1 soluble subunit alpha 1 (GUCY1A1) is a gene that affects vasoreactivity and platelet function, thereby influencing thrombotic processes and the risk of developing thrombotic lesions in the coronary vessels. In SELL and GUCY1A1 genes, several polymorphisms have been detected, which may affect gene expression. The aim of our study was to assess the association between the SELL rs2205849 and rs2229569 and GUCY1A1 rs7692387 polymorphisms with the risk of acute coronary syndromes in the form of unstable angina pectoris, and the association between these polymorphisms and selected clinical parameters affecting the risk of developing ischemic heart disease. The study included 232 patients with unstable angina. The diagnosis of unstable angina was achieved by a typical clinical presentation and confirmation of significant coronary artery lumen stenosis (>70%) during coronary angiography. There were no statistically significant differences in GUCY1A1 rs7692387 and SELL rs2205849 and rs2229569 polymorphism distribution between the total study and the control groups. However, when only analysing patients over 55 years of age, we found a decreased frequency of the GUCY1A1 rs7692387AA genotype (AA vs. GA + GG, OR: 0.07; 95% CI: 0.01−0.78) and an increased frequency of the SELL rs2205849 CC genotype (CC vs. TC + TT p = 0.022) and SELL rs2229569 AA genotype (AA vs. GA + GG p = 0.022) in patients with unstable angina. Our results suggest that the SELL rs2205849 and rs2229569 and GUCY1A1 rs7692387 polymorphisms are not risk factors for unstable angina in the Polish population. The GUCY1A1 rs7692387 polymorphism may increase the risk of unstable angina in patients younger than 55 years, while the SELL polymorphisms rs2205849 and rs2229569 may increase the risk of unstable angina in patients older than 55 years in the Polish population.

Verification of immunology-related genetic associations in BPD supports ABCA3 and five other genes

BACKGROUND

Inflammatory processes are key drivers of bronchopulmonary dysplasia (BPD), a chronic lung disease in preterm infants. In a large sample, we verify previously reported associations of genetic variants of immunology-related genes with BPD.

METHODS

Preterm infants with a gestational age ≤32 weeks from PROGRESS and the German Neonatal Network (GNN) were included. Through a consensus case/control definition, 278 BPD cases and 670 controls were identified. We identified 49 immunity-related genes and 55 single-nucleotide polymorphisms (SNPs) previously associated with BPD through a comprehensive literature survey. Additionally, a quantitative genetic association analysis regarding oxygen supplements, mechanical ventilation, and continuous positive air pressure (CPAP) was performed.

RESULTS

Five candidate SNPs were nominally associated with BPD-related phenotypes with effect directions not conflicting the original studies: rs11265269-CRP, rs1427793-NUAK1, rs2229569-SELL, rs1883617-VNN2, and rs4148913-CHST3. Four of these genes are involved in cell adhesion. Extending our analysis to all well-imputed SNPs of all candidate genes, the strongest association was rs45538638-ABCA3 with CPAP (p = 4.9 × 10^-7, FDR = 0.004), an ABC transporter involved in surfactant formation.

CONCLUSIONS

Most of the previously reported associations could not be replicated. We found additional support for SNPs in CRP, NUAK1, SELL, VNN2, and ABCA3. Larger studies and meta-analyses are required to corroborate these findings.

IMPACT

Larger cohort for improved statistical power to detect genetic associations with bronchopulmonary dysplasia (BPD). Most of the previously reported genetic associations with BPD could not be replicated in this larger study. Among investigated immunological relevant candidate genes, additional support was found for variants in genes CRP, NUAK1, SELL, VNN2, and CHST3, four of them related to cell adhesion. rs45538638 is a novel candidate SNP in reported candidate gene ABC-transporter ABCA3. Results help to prioritize molecular candidate pathomechanisms in follow-up studies.

Role of oxidative stress in neonatal respiratory distress syndrome

Respiratory distress syndrome is the commonest respiratory disorder in preterm infants. Although it is well known that preterm birth has a key role, the mechanisms of lung injury have not been fully elucidated. The pathogenesis of this neonatal condition is based on the rapid formation of the oxygen reactive species, which surpasses the detoxification capacity of anti-oxidative defense system. The high reactivity of free radical leads to damage to a variety of molecules and may induce respiratory cell death. There is evidence that the oxidative stress involved in the physiopathology of this disease, is particularly related to oxygen supplementation, mechanical ventilation, inflammation/infection and diabetes. This narrative review summarizes what is known regarding the connection between oxidative stress and respiratory distress syndrome.

Influence of haplotypes, gene expression and soluble levels of L-selectin on the risk of acute coronary syndrome

BACKGROUND

L-selectin gene (SELL) is a candidate gene for the development of acute coronary syndrome (ACS) that contributes to endothelial dysfunction. The -642C>T (rs2205849) and 725C>T (rs2229569) polymorphisms have been associated with changes in gene expression, ligand affinity and increased risk of cardiovascular disease. The aim of this study was to investigate the association between the haplotypes constructed with the -642C>T and 725C>T polymorphisms of the SELL gene, the expression levels of its mRNA and the serum levels of soluble L-selectin with ACS.

METHODS

We recruited 615 individuals of Mexican origin matched by age, including 342 patients with ACS and 273 individuals without personal history of ischemic cardiopathy as control group (CG). Genotyping was performed by PCR-RFLP. The qPCR technique was used to analyze the expression of mRNA using TaqMan® UPL probes. The levels of soluble L-selectin were measured with ELISA.

RESULTS

The allele variants in both polymorphisms were over-represented in the CG compared to the ACS (OR range: 0.371-0.716, p<0.006). The CT and TT haplotypes had a protective effect against the development of ACS (OR=0.401, p<0.0001; OR=0.628, p<0.0001, respectively). SELL expression was 3.076 times higher in the ACS group compared to CG (p<0.001). The levels of soluble L-selectin were similar between ACS and CG.

CONCLUSIONS

Both polymorphisms had no effect on mRNA expression and soluble protein levels. The polymorphisms -642C>T and 725C>T of the SELL gene are protective factors against the development of ACS. There is an increased gene expression of L-selectin in ACS compared to CG in the population of Western Mexico.

Expression of lymphocyte activation markers of preterm neonates is associated with perinatal complications

Background

Inappropriate activation of T lymphocytes plays an important role in perinatal complications. However, data on T lymphocyte activation markers of preterm infants is scarce. We investigated the association between gender, gestational and postnatal age, preeclampsia (PE), premature rupture of membranes (PROM) as well as prenatal steroid treatment (PS) and the frequency of activated T lymphocyte subsets (HLA-DR+, CD69+, CD25+, CD62L+) and major T lymphocyte subpopulations (CD4, CD8, Th1, Th2, naïve, memory) in peripheral blood during the first postnatal week in preterm infants.

Results

Cord blood and peripheral blood samples were collected from 43 preterm infants on the 1st, 3rd, and 7th days of life. We assessed the frequency of the above T lymphocyte subsets using flow cytometry. The ‘mixed effect model’ was used to analyze the effects of clinical parameters on T lymphocyte markers. The frequency of CD25+ T lymphocytes was higher in PROM. The frequency of CD4+ and CD8+ cells and the CD4+/CD8+ cell ratio was decreased in PE. The frequency of CD62L+ T lymphocytes was higher in male compared with female infants. PS did not affect the frequency of the investigated markers. CD4+ CD25+ cells had a lower frequency at birth than on day 7. Th2 lymphocytes had a lower frequency on postnatal days 1 and 3 when compared to day 7.

Conclusions

Our observations indicate that alterations affecting the expression of T lymphocyte activation markers are associated with the above factors and may play a role in the development of perinatal complications.

Ventilation strategies for preventing oxidative stress-induced injury in preterm infants with respiratory disease: an update

Reactive oxygen and nitrogen species are produced by several inflammatory and structural cells of the airways. The lungs of preterm newborns are susceptible to oxidative injury induced by both reactive oxygen and nitrogen species. Increased oxidative stress and imbalance in antioxidant enzymes may play a role in the pathogenesis of inflammatory pulmonary diseases. Preterm infants are frequently exposed to high oxygen concentrations, infections or inflammation; they have reduced antioxidant defense and high free iron levels which enhance toxic radical generation. Multiple ventilation strategies have been studied to reduce injury and improve outcomes in preterm infants. Using lung protective strategies, there is the need to reach a compromise between satisfaction of gas exchange and potential toxicities related to over-distension, derecruitment of lung units and high oxygen concentrations. In this review, the authors summarize scientific evidence concerning oxidative stress as it relates to resuscitation in the delivery room and to the strategies of ventilation.

Elucidating the role of genomics in neonatal sepsis

Sepsis is a major cause of neonatal morbidity and mortality, especially in vulnerable preterm populations. Immature immune defenses, and environmental and maternal factors contribute to this risk, with as many as a third of very preterm infants experiencing sepsis during their stay in the neonatal intensive care unit (NICU). Epidemiologic and twin studies have suggested that there is a genetic contribution to sepsis predilection. Several investigators have conducted candidate gene association studies on variants of specific interest and potential functional significance in neonatal sepsis. In this review, we describe details of studies that have evaluated genetic susceptibility in neonatal sepsis, and summarize findings from a review of candidate gene association studies.

The role of genetic polymorphisms in antioxidant enzymes and potential antioxidant therapies in neonatal lung disease

SIGNIFICANCE

Oxidative stress is involved in the development of newborn lung diseases, such as bronchopulmonary dysplasia and persistent pulmonary hypertension of the newborn. The activity of antioxidant enzymes (AOEs), which is impaired as a result of prematurity and oxidative injury, may be further affected by specific genetic polymorphisms or an unfavorable combination of more of them.

RECENT ADVANCES

Genetic polymorphisms of superoxide dismutase and catalase were recently demonstrated to be protective or risk factors for the main complications of prematurity. A lot of research focused on the potential of different antioxidant strategies in the prevention and treatment of lung diseases of the newborn, providing promising results in experimental models.

CRITICAL ISSUES

The effect of different genetic polymorphisms on protein synthesis and activity has been poorly detailed in the newborn, hindering to derive conclusive results from the observed associations with adverse outcomes. Therapeutic strategies that aimed at enhancing the activity of AOEs were poorly studied in clinical settings and partially failed to produce clinical benefits.

FUTURE DIRECTIONS

The clarification of the effects of genetic polymorphisms on the proteomics of the newborn is mandatory, as well as the assessment of a larger number of polymorphisms with a possible correlation with adverse outcome. Moreover, antioxidant treatments should be carefully translated to clinical settings, after further details on optimal doses, administration techniques, and adverse effects are provided. Finally, the study of genetic polymorphisms could help select a specific high-risk population, who may particularly benefit from targeted antioxidant strategies.

Antioxidant strategies and respiratory disease of the preterm newborn: an update

Preterm newborns are challenged by an excessive oxidative burden, as a result of several perinatal stimuli, as intrauterine infections, resuscitation, mechanical ventilation, and postnatal complications, in the presence of immature antioxidant capacities. "Oxygen radical disease of neonatology" comprises a wide range of conditions sharing a common pathway of pathogenesis and includes bronchopulmonary dysplasia (BPD) and other main complications of prematurity. Antioxidant strategies may be beneficial in the prevention and treatment of oxidative stress- (OS-) related lung disease of the preterm newborn. Endotracheal supplementation or lung-targeted overexpression of superoxide dismutase was proved to reduce lung damage in several models; however, the supplementation in preterm newborn failed to reduce the risk of BPD, although long-term respiratory outcomes were improved. Also melatonin administration to small cohorts of preterm newborns suggested beneficial effects on lung OS. The possibility to identify single nucleotide polymorphism affecting the risk of BPD may help to identify specific populations with particularly high risk of OS-related diseases and may pose the basis for individually targeted treatments. Finally, surfactant replacement may lead to local anti-inflammatory and antioxidant effects, thanks to specific enzymatic and nonenzymatic antioxidants naturally present in animal surfactants.

Progress in understanding the genetics of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease in infants. Its treatment imposes considerable healthcare burden and costs in the perinatal and early childhood period and patients are usually left with lifelong deficits in lung function. Evidence exists for different pathophysiologic pathways that can promote the structural changes that characterize BPD, including the impairment in alveolarization; however, there is increasing interest regarding heritable factors that may predispose very low birth weight infants to BPD. Our review focuses on recent publications that have investigated genetic factors that may potentially contribute to such reported heritability. These publications point us toward some possible genomic candidates for further study, but certainly do not identify any particular gene or gene pathway that would be inferred to be contributing substantially to the underlying etiology of BPD.

Prediction of sepsis-related outcomes in neonates through systematic genotyping of polymorphisms in genes for innate immunity and inflammation: a narrative review and critical perspective

CONTEXT AND OBJECTIVE

Neonatal sepsis is associated with premature birth and maternal infection. Large-scale studies seek to define markers that identify neonates at risk of developing sepsis. Here, we examine whether the scientific evidence supports systematic use of polymorphism genotyping in cytokine and innate immunity genes, to identify neonates at increased risk of sepsis.

DESIGN AND SETTING

Narrative literature review conducted at Fernandes Figueira Institute, Brazil.

METHODS

The literature was searched in PubMed, Embase (Excerpta Medica Database), Lilacs (Literatura Latino-Americana e do Caribe em Ciências da Saúde), SciELO (Scientific Electronic Library Online) and Cochrane Library. From > 400,000 references, 548 were retrieved based on inclusion/exclusion criteria; 22 were selected for detailed analysis after quality assessment.

RESULTS

The studies retrieved addressed the impact of gene polymorphisms relating to immune mechanisms (most often TNF-a, LT-a, IL-6, IL-1β, IL-1ra, L-selectin, CD14 and MBL) or inflammatory mechanisms (ACE and angiotensin II receptors; secretory PLA2; and hemostatic factors). Despite initial reports suggesting positive associations between specific polymorphisms and increased risk of sepsis, the accumulated evidence has not confirmed that any of them have predictive power to justify systematic genotyping.

CONCLUSIONS

Sepsis prediction through systematic genotyping needs to be reevaluated, based on studies that demonstrate the functional impact of gene polymorphisms and epidemiological differences among ethnically distinct populations.

Targeting inflammation to prevent bronchopulmonary dysplasia: can new insights be translated into therapies?

Bronchopulmonary dysplasia (BPD) frequently complicates preterm birth and leads to significant long-term morbidity. Unfortunately, few therapies are known to effectively prevent or treat BPD. Ongoing research has been focusing on potential therapies to limit inflammation in the preterm lung. In this review we highlight recent bench and clinical research aimed at understanding the role of inflammation in the pathogenesis of BPD. We also critically assess currently used therapies and promising developments in the field.

Association between birth weight in preterm neonates and the BclI polymorphism of the glucocorticoid receptor gene

Endogenous and exogenous glucocorticoids influence fetal growth and development, and maternal administration of synthetic glucocorticoids may decrease the risk of perinatal morbidity including lung disease in preterm neonates. Because polymorphisms of the glucocorticoid receptor gene are known to influence the sensitivity to glucocorticoids, in the present study we examined whether any associations could exist among the BclI, N363S and ER22/23EK polymorphisms of the glucocorticoid receptor gene and gestational age, birth weight and/or perinatal morbidity of 125 preterm neonates born at 28-35 weeks' gestation with (n=57) or without maternal dexamethasone treatment (n=68). The prevalence of the three polymorphisms in the whole group of preterm infants was similar to that reported in healthy adult Hungarian population. However, we found that the BclI polymorphism significantly associated with higher birth weight adjusted for the gestational age (p=0.004, ANOVA analysis). None of the three polymorphisms showed an association with perinatal morbidities, including necrotizing enterocolitis, intraventricular hemorrhagia, patent ductus arteriosus, respiratory distress syndrome, bronchopulmonary dysplasia and sepsis in the two groups of preterm neonates with and without maternal dexamethasone treatment. These results suggest that the BclI polymorphism of the glucocorticoid receptor gene may have an impact on gestational age-adjusted birth weight, but it does not influence perinatal morbidities of preterm neonates.

Dysplasia: a review

Bronchopulmonary dysplasia (BPD) is a common perinatal complication of very low birth weight preterm infants with a significant risk of long-term disability and morbidity. While clinical conditions such as prematurity and mechanical ventilation are its major risk factors, studies suggest that there is an individual susceptibility to BPD. This comprehensive review summarizes data collected about the implication of genetic polymorphisms in BPD and in its risk factors. Some studies have directly related the risk of BPD to genotype. Indeed, carrier states of genetic variants of cytokines (IFNgamma T+874A), adhesion molecules (L-selectin-Pro213Ser), elements of renin-angiotensin system (ACE-I/D), antioxidant enzymes (GST-P1 Val105Ile), and surfactant proteins (SPA1, SPB intron 4) has been identified as risk factors to BPD. Other studies investigated the role of genotype in BPD risk factors. Premature birth has been linked to carrier states of genetic variants with an impact on immune status (such as IL-6 G(-174)C, MBL2 54G/A, VEGF G+405C, HSP72 A+1267G genes) and matrix metalloproteases. Fetal inflammatory response syndrome, a major determinant of BPD is also affected by genotype (including LTalpha A+250G). Disturbed intrauterine lung development and vascularization may also contribute to BPD; these processes may be impaired in the presence of some rare genetic mutations. Furthermore, there is also a genetic component in the susceptibility to other perinatal adaptational disturbances such as respiratory distress syndrome that are associated with an increased need for mechanical ventilation, and, hence, with lung damage. The genetic variants presented in this article may help to identify infants at risk for BPD.