Postnatal Sepsis and Bronchopulmonary Dysplasia in Premature Infants: Mechanistic Insights into "New BPD"

Association between viral infection and bronchopulmonary dysplasia in preterm infants: a systematic review and meta-analysis

Bronchopulmonary dysplasia (BPD) is the most common serious complication of very preterm infants (VPI) or very low birth weight (VLBW) infants. Studies implicate viral infections in etiopathogenesis. The aim of this study was to summarize the relationship between viral infections and BPD through a systematic review and meta-analysis. We searched PubMed, Embase, the Web of Science Core Collection, and the Cochrane Database on December 19, 2023. We included observational studies that examined the association between viral infections and BPD in preterm infants. We extracted data on study methods, participant characteristics, exposure assessment, and outcome measures. We assessed study risk of bias using the Newcastle-Ottawa Scale (NOS). We included 17 and 15 studies in the qualitative review and meta-analysis, respectively. The meta-analysis showed a significant association between viral infection and BPD diagnosed at 36 weeks postmenstrual age (odds ratio (OR): 2.42, 95% confidence interval: 1.89-3.09, 13 studies, very low certainty of evidence). In a subgroup analysis of specific viruses, cytomegalovirus (CMV) proved to be significantly associated with BPD diagnosed at 36 weeks postmenstrual age (OR: 2.34, 95% confidence interval: 1.80-3.05, 11 studies). We did not find an association between viral infection and BPD diagnosed on the 28th day of life, probably due to the small sample size of the included prospective studies.  Conclusion: Viral infections, especially CMV, are associated with an increased risk of BPD in preterm infants. Methodologically reliable prospective studies with large samples are needed to validate our conclusions, and high-quality randomized controlled studies are needed to explore the effect of prevention or treatment of viral infections on the incidence of BPD. What is Known: • Studies have attempted to identify viral infections and bronchopulmonary dysplasia in preterm infants; however, results have been inconsistent. What is New: • Systematic demonstration that viral infections, particularly cytomegalovirus, are positively associated with bronchopulmonary dysplasia diagnosed in preterm infants at the 36th week of postmenstrual age. • The importance of screening for viral infections in preterm infants, especially cytomegalovirus. More high-quality studies should be produced in the future to investigate the causal relationship between viral infections and bronchopulmonary dysplasia.

[Impact of different angles of pulmonary surfactant administration on bronchopulmonaryplasia and intracranial hemorrhage in preterm infants: a prospective randomized controlled study]

OBJECTIVES

To investigate the effects of different angles of pulmonary surfactant (PS) administration on the incidence of bronchopulmonary dysplasia and intracranial hemorrhage in preterm infants.

METHODS

A prospective study was conducted on 146 preterm infants (gestational age <32 weeks) admitted to the Department of Neonatology, Provincial Hospital Affiliated to Anhui Medical University from January 2019 to May 2023. The infants were randomly assigned to different angles for injection of pulmonary surfactant groups: 0° group (34 cases), 30° group (36 cases), 45° group (38 cases), and 60° group (38 cases). Clinical indicators and outcomes were compared among the groups.

RESULTS

The oxygenation index was lower in the 60° group compared with the other three groups, with shorter invasive ventilation time and oxygen use time, and a lower incidence of bronchopulmonary dysplasia than the other three groups (P<0.05). The incidence of intracranial hemorrhage was lower in the 60° group compared to the 0° group (P<0.05). The cure rate in the 60° group was higher than that in the 0° group and the 30° group (P<0.05).

CONCLUSIONS

The clinical efficacy of injection of pulmonary surfactant at a 60° angle is higher than other angles, reducing the incidence of intracranial hemorrhage and bronchopulmonary dysplasia in preterm infants.

Epigenetic modifications in the development of bronchopulmonary dysplasia: a review

While perinatal medicine advancements have bolstered survival outcomes for premature infants, bronchopulmonary dysplasia (BPD) continues to threaten their long-term health. Gene-environment interactions, mediated by epigenetic modifications such as DNA methylation, histone modification, and non-coding RNA regulation, take center stage in BPD pathogenesis. Recent discoveries link methylation variations across biological pathways with BPD. Also, the potential reversibility of histone modifications fuels new treatment avenues. The review also highlights the promise of utilizing mesenchymal stem cells and their exosomes as BPD therapies, given their ability to modulate non-coding RNA, opening novel research and intervention possibilities. IMPACT: The complexity and universality of epigenetic modifications in the occurrence and development of bronchopulmonary dysplasia were thoroughly discussed. Both molecular and cellular mechanisms contribute to the diverse nature of epigenetic changes, suggesting the need for deeper biochemical techniques to explore these molecular alterations. The utilization of innovative cell-specific drug delivery methods like exosomes and extracellular vesicles holds promise in achieving precise epigenetic regulation.

TGF-α/EGFR signaling promotes lipopolysaccharide-induced abnormal elastin deposition and alveolar simplification

Bronchopulmonary dysplasia (BPD) is characterized by shortened secondary septa and fewer, larger alveoli. Elastin deposition to the distal tips of the secondary septa is critical for elongation of the secondary septa. Alveolar myofibroblasts, which are thought to migrate to the septal tips during alveolarization, are mainly responsible for elastin production and deposition. Antenatal exposure to inflammation induces abnormal elastin deposition, thereby increasing the risk of developing BPD. Here, we found that lipopolysaccharide (LPS) significantly increased the expression of transforming growth factor-α (TGF-α) in an LPS-induced rat model of BPD and in LPS-treated human pulmonary epithelial cells (BEAS-2B). In addition, in vitro experiments suggested that LPS upregulated TGF-α expression via toll-like receptor 4 (TLR4)/tumor necrosis factor α-converting enzyme (TACE) signaling. Increased TGF-α levels via its receptor epidermal growth factor receptor (EGFR)-induced lysyl oxidase (LOX) overactivation and cell division cycle 42 (Cdc42) activity inhibition of myofibroblasts. Similarly, in vivo LOX overactivation and inhibition of Cdc42 activity were observed in the lungs of LPS-exposed pups. LOX overactivation led to abnormal elastin deposition, and inhibition of Cdc42 activity disturbed the directional migration of myofibroblasts and disrupted elastin localization. Most importantly, the EGFR inhibitor erlotinib partially rescued LOX overactivation and Cdc42 activity inhibition, and improved elastin deposition and alveolar development in antenatal LPS-treated rats. Taken together, our data suggest that TGF-α/EGFR signaling is critically involved in the regulation of elastin deposition and represents a novel therapeutic target.

Risk factors for severe bronchopulmonary dysplasia in a Chinese cohort of very preterm infants

OBJECTIVES

To examine the risk factors for severe bronchopulmonary dysplasia (BPD) in a cohort of very preterm infants (VPIs) in China, as BPD is common among VPIs and associated with a high mortality rate.

METHODS

In this multicenter retrospective study, medical records from infants with BPD born at gestation age (GA) of <32 weeks with birth weight (BW) of <1,500 grams (g) in 7 regions of China were included. The cohort was stratified into different BPD severity groups based on their fraction of inspired oxygen requirement at a modified GA of 36 weeks or post discharge. Risk factors were identified using logistic regression analysis.

RESULTS

A significant inverse correlation was revealed between BPD severity and both GA and BW (p<0.001). Independent risk factors for severe BPD (sBPD) were identified as invasive mechanical ventilation (≥7d), multiple blood transfusion (≥3), nosocomial infection (NI), hemodynamically significant patent ductus arteriosus (hsPDA), delayed initiation of enteral nutrition, and longer time to achieve total caloric intake of 110 kcal/kg. Conversely, administration of antenatal steroids was associated with reduced risk of sBPD.

CONCLUSION

Our study not only reaffirmed the established risk factors of low GA and BW for sBPD in VPIs, but also identified additional, potentially modifiable risk factors. Further research is warranted to explore whether intervention in these modifiable factors might reduce the risk of sBPD.Clinical Trial Reg. No.: ChiCTR1900023418.

Investigation of the miRNA-mRNA Regulatory Circuits and Immune Signatures Associated with Bronchopulmonary Dysplasia

Background

Bronchopulmonary dysplasia (BPD) has become a major cause of morbidity and mortality in preterm infants worldwide, yet its pathogenesis and underlying mechanisms remain poorly understood. The present study sought to explore microRNA-mRNA regulatory networks and immune cells involvement in BPD through a combination of bioinformatic analysis and experimental validation.

Methods

MicroRNA and mRNA microarray datasets were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed microRNAs (DEMs) were identified in BPD patients compared to control subjects, and their target genes were predicted using miRWalk, miRNet, miRDB, and TargetScan databases. Subsequently, protein-protein interaction (PPI) and functional enrichment analyses were conducted on the target genes. 30 hub genes were screened using the Cytohubba plugin of the Cytoscape software. Additionally, mRNA microarray data was utilized to validate the expression of hub genes and to perform immune infiltration analysis. Finally, real-time PCR (RT-PCR), immunohistochemistry (IHC), and flow cytometry were conducted using a mouse model of BPD to confirm the bioinformatics findings.

Results

Two DEMs (miR-15b-5p and miR-20a-5p) targeting genes primarily involved in the regulation of cell cycle phase transition, ubiquitin ligase complex, protein serine/threonine kinase activity, and MAPK signaling pathway were identified. APP and four autophagy-related genes (DLC1, PARP1, NLRC4, and NRG1) were differentially expressed in the mRNA microarray dataset. Analysis of immune infiltration revealed significant differences in levels of neutrophils and naive B cells between BPD patients and control subjects. RT-PCR and IHC confirmed reduced expression of APP in a mouse model of BPD. Although the proportion of total neutrophils did not change appreciably, the activation of neutrophils, marked by loss of CD62L, was significantly increased in BPD mice.

Conclusion

Downregulation of APP mediated by miR-15b-5p and miR-20a-5p may be associated with the development of BPD. Additionally, increased CD62L- neutrophil subset might be important for the immune-mediated injury in BPD.

Factors associated with the response to postnatal dexamethasone use in very low birthweight infants: a nationwide cohort study

BACKGROUND

Dexamethasone is widely used as a systemic corticosteroid to treat and prevent bronchopulmonary dysplasia (BPD) in preterm infants. We evaluated the current epidemiology of dexamethasone use to prevent BPD and analyse the factors associated with the response to dexamethasone in very low birthweight infants using a nationwide database.

METHODS

We included very low birthweight infants born between January 2013 and December 2020 with a gestational age of 23-31 weeks using data from the Korean Neonatal Network registry. Patients were grouped based on their dexamethasone use into 'Dex' or 'No Dex' groups. Clinical variables and data were collected, and the annual trends of dexamethasone use and the proportion of patients who received dexamethasone according to gestational age were analysed. Respiratory outcomes were compared between the groups. Univariate and multivariate analyses were performed to analyse factors associated with the response to dexamethasone in BPD.

RESULTS

Of 11 261 eligible infants, 2313 (20.5%) received dexamethasone, and 1714 (74.1%) of them were diagnosed with moderate-to-severe BPD. The 8-year annual prevalence of dexamethasone use was 17.7-22.3%. The 'Dex' group had more moderate-to-severe BPD, more frequent invasive ventilation use at a postmenstrual age of 36 weeks and longer ventilator duration. Birth weight, 5-minute APGAR score, pulmonary hypertension within the first 28 days, surgical treatment of patent ductus arteriosus, medical treatment of patent ductus arteriosus, pathological chorioamnionitis, hydrocortisone or budesonide use, surgical management of necrotising enterocolitis and fungal sepsis were associated with BPD after dexamethasone use.

CONCLUSIONS

Approximately 20.5% of preterm infants received dexamethasone, and the frequency increased as gestational age decreased. Poor response to dexamethasone was associated with antenatal and postnatal inflammation, low birth weight and early pulmonary hypertension.

A two-center retrospective study: association of early caffeine administration and oxygen radical diseases in neonatology in Chinese preterm neonates

Introduction

Since December 2012, the prophylactic use of caffeine to treat AOP in preterm infants has been approved in China. This study aimed to investigate the relationship between early caffeine treatment initiation and the incidence of oxygen radical diseases in neonatology (ORDIN) in Chinese preterm infants.

Methods

A retrospective study was conducted at two hospitals in South China, involving 452 preterm infants with gestational ages less than 37 weeks. The infants were divided into early (227 cases, initiating within 48 h after birth) and late (225 cases, initiating over 48 h after birth) caffeine treatment group. Logistic regression analysis and Receiver Operating Characteristic (ROC) curves were used to evaluate the association between early caffeine treatment and the incidence of ORDIN.

Results

The results showed that extremely preterm infants in early treatment group had a lower incidence of PIVH and ROP compared to those in the late treatment group (PIVH, 20.1% versus 47.8%, P = 0.02; ROP, 70.8% versus 89.9%, P = 0.025). Very preterm infants in the early treatment group had a lower incidence of BPD and PIVH compared to those in the late treatment group (BPD, 43.8% versus 63.1%, P = 0.002; PIVH, 9.0% versus 22.3%, P = 0.001). Moreover, VLBW infants who received early caffeine treatment exhibited a decreased incidence of BPD (55.9% versus 80.9%, P = 0.000), PIVH (11.8% versus 33.1%, P = 0.000), and ROP (69.9% versus 79.8%, P = 0.043) compared to those in the late treatment group. Infants in the early caffeine treatment showed a reduced likelihood of PIVH (adjusted odds ratio, 0.407; 95%CI, 0.188-0.846) but did not exhibit a significant association with other terms of ORDIN. ROC analysis revealed that early initiation of caffeine treatment was associated with lower risk of BPD, PIVH, and ROP in preterm infants.

Discussion

In conclusion, this study demonstrates that early initiation of caffeine treatment is associated with a decreased incidence of PIVH in Chinese preterm infants. Further prospective investigations are necessary to verify and elucidate the precise effects of early caffeine treatment on complications in preterm Chinese infants.

A prediction nomogram for moderate-to-severe bronchopulmonary dysplasia in preterm infants < 32 weeks of gestation: A multicenter retrospective study

Background

Moderate-to-severe bronchopulmonary dysplasia (msBPD) is a serious complication in preterm infants. We aimed to develop a dynamic nomogram for early prediction of msBPD using perinatal factors in preterm infants born at <32 weeks' gestation.

Methods

This multicenter retrospective study conducted at three hospitals in China between January 2017 and December 2021 included data on preterm infants with gestational age (GA) < 32 weeks. All infants were randomly divided into training and validation cohorts (3:1 ratio). Variables were selected by Lasso regression. Multivariate logistic regression was used to build a dynamic nomogram to predict msBPD. The discrimination was verified by receiver operating characteristic curves. Hosmer-Lemeshow test and decision curve analysis (DCA) were used for evaluating calibration and clinical applicability.

Results

A total of 2,067 preterm infants. GA, Apgar 5-min score, small for gestational age (SGA), early onset sepsis, and duration of invasive ventilation were predictors for msBPD by Lasso regression. The area under the curve was 0.894 (95% CI 0.869-0.919) and 0.893 (95% CI 0.855-0.931) in training and validation cohorts. The Hosmer-Lemeshow test calculated P value of 0.059 showing a good fit of the nomogram. The DCA demonstrated significantly clinical benefit of the model in both cohorts. A dynamic nomogram predicting msBPD by perinatal days within postnatal day 7 is available at https://sdxxbxzz.shinyapps.io/BPDpredict/.

Conclusion

We assessed the perinatal predictors of msBPD in preterm infants with GA < 32 weeks and built a dynamic nomogram for early risk prediction, providing clinicians a visual tool for early identification of msBPD.

Preterm sepsis is associated with acute lung injury as measured by pulmonary severity score

BACKGROUND

Sepsis related acute lung injury (ALI) is established in adults but has not been investigated in premature infants. Herein, we used pulmonary severity score (PSS) trajectories and C-reactive protein (CRP) to examine the relation between sepsis and ALI in premature infants.

METHODS

This retrospective study identified 211 sepsis and 123 rule out (RO) events in 443 infants born <31 weeks and <1500 grams. The PSS was calculated prior to, at the time of, and up to 1 week after each event. Initial and peak CRP values were collected for each event.

RESULTS

PSS significantly increased at 0 h from baseline (-72h) and remained increased at all subsequent time points (all p < 0.002) in sepsis events. Mean PSS in sepsis episodes were also higher compared to RO events at +24 h, +48 h, +72 h, and +168 h (all p < 0.004). A positive correlation was noted between peak CRP values in sepsis events and PSS at 0 h, +24 h, +48 h, and +72 h.

CONCLUSIONS

The temporal PSS trends and correlation with CRP levels observed in sepsis but not in RO events supports the hypothesis that neonatal sepsis is associated with ALI and contributes to the accumulating evidence that neonatal ARDS occurs.

IMPACT

To evaluate pulmonary severity scores and c-reactive protein values over time to establish an association between preterm neonatal sepsis and acute lung injury (ALI). Though sepsis is well established as the most common indirect cause of ALI leading to acute respiratory distress syndrome (ARDS) in adults and pediatrics, this phenomenon remains undefined in neonates. This study validates the proposal by the Neonatal ARDS Project that ARDS also occurs in neonates by demonstrating acute and sustained changes in markers of pulmonary injury temporally related to a diagnosis of neonatal sepsis in preterm infants.

Prospecting of exosomal-miRNA signatures as prognostic marker for gestational diabetes mellitus and other adverse pregnancy outcomes

Exosomal microRNA (ExomiRs) serves as potential cargo molecules responsible for post-translation of gene expression and intracellular communication playing a vital role in acting as clinically relevant prognostic biomarkers for identifying pregnancy-associated complications in patients. ExomiRs are associated with Gestational Diabetes Mellitus (GDM) as potential targets for understanding the pathophysiology of beta-cell dysfunction. ExomiRs (ExomiR 122, ExomiR 16-5p, ExomiR 215-5p, ExomiR 450b-3p, ExomiR 122-5p) aid to act as biomarkers and regulate the progression of diabetes and its related complication. These ExomiRshave been reported to interfere with the regulation of various genes such as ZEB2, IRS1, IRS2, GLUT1, GLUT4, etc. and inhibition of several pathways like PI3K/AKT, Wnt, and mTOR signaling pathways leading to the modulation in the development of GDM affecting the clinical and pathological features of women. These ExomiRs have also been associated with other pregnancy-associated complications, including preeclampsia, hypothyroidism, pregnancy loss, and ectopic pregnancies. On the other hand, overexpression of certain ExomiRs such as Exomir-515-5p, ExomiR-221, and ExomiR-96 serve a regulatory role in overcoming insulin resistance. Taken together, the current review focuses on the prospective capabilities of ExomiRs for diagnosis and clinical prognosis of GDM women with respect to pregnancy outcomes.

[Influencing factors for the development and severity of bronchopulmonary dysplasia in preterm infants with a gestational age of <32 weeks and a birth weight of <1 500 g]

OBJECTIVES

To study the influencing factors for the development and severity of bronchopulmonary dysplasia (BPD) in preterm infants with a gestational age of <32 weeks and a birth weight of <1 500 g.

METHODS

A retrospective analysis was performed on the medical data of preterm infants with a gestational age of <32 weeks and a birth weight of <1 500 g who were admitted to Women and Children's Hospital Affiliated to Xiamen University from January 1, 2017 to December 31, 2021. According to oxygen dependence on day 28 after birth, they were divided into two groups: BPD (n=218) and non-BPD (n=142). According to disease severity based on oxygen concentration required at the corrected age of 36 weeks or at discharge, the infants with BPD were divided into two groups: mild BPD (n=154) and moderate/severe BPD (n=64). Indices such as perinatal data and nutritional status were compared between groups. The multivariate logistic regression analysis was used to determine the influencing factors for BPD and its severity.

RESULTS

The incidence rate and severity of BPD increased with the reduction in gestational age and birth weight (P<0.05). The multivariate logistic regression analysis showed that a long duration of invasive mechanical ventilation (OR=1.320, P<0.05), hemodynamically significant patent ductus arteriosus (OR=2.032, P<0.05), and a prolonged time to reach oral calorie goal of 110 kcal/(kg·d) (OR=1.041, P<0.05) were risk factors for BPD, while an older gestational age was a protective factor against BPD (OR=0.535, P<0.05). Early-onset sepsis (OR=2.524, P<0.05) and a prolonged time to reach oral calorie goal of 110 kcal/(kg·d) (OR=1.029, P<0.05) were risk factors for moderate/severe BPD, while a high mean weight growth velocity was a protective factor against moderate/severe BPD (OR=0.906, P<0.05).

CONCLUSIONS

The incidence rate and severity of BPD in preterm infants with a gestational age of <32 weeks and a birth weight of <1 500 g can be reduced by shortening the duration of invasive mechanical ventilation, giving early treatment of early-onset sepsis and hemodynamically significant patent ductus arteriosus, adopting active enteral nutritional strategies, and increasing mean weight growth velocity.

Pulmonary hypertension with bronchopulmonary dysplasia: Aichi cohort study

BACKGROUND

The incidence of pulmonary hypertension (PH) associated with bronchopulmonary dysplasia (BPD) has not been investigated in regional cohorts. The aim of this study was to clarify the incidence of PH associated with BPD in all very low birthweight infants (VLBWIs) born during the study period in Aichi Prefecture, Japan.

METHODS

We conducted a retrospective observational cohort study of all VLBWIs born in Aichi Prefecture. The inclusion criteria were VLB, birth between 1 January 2015 and 31 December 2015, and admission to any neonatal intensive care unit in Aichi Prefecture. BPD28d and BPD36w were defined as the need for supplemental oxygen or any respiratory support at 28 days of age or 36 weeks of postmenstrual age (PMA). The primary outcome was the incidence of PH after 36 weeks' PMA (PH36w) in VLBWIs with BPD28d and BPD36w. The secondary outcomes were the clinical factors related to PH36w in BPD36w patients. Mann-Whitney U-test and Fisher's exact test were used for univariate analysis. Differences were considered statistically significant at P < 0.05. Risk ratio (RR) and 95% confidence interval (CI) were also evaluated.

RESULTS

A total of 441 patients were analyzed. A total of 217 and 131 patients met the definition of BPD28d and BPD36w, respectively. Nine patients were diagnosed with PH36w (4.2% and 6.9% of the BPD28d and BPD36w patients, respectively). The presence of oligohydramnios (RR, 2.71; 95% CI: 1.55-4.73, P = 0.014) and sepsis (RR, 3.62; 95% CI: 1.51-8.63, P = 0.025) was significant in the PH36w patients.

CONCLUSIONS

The incidence of PH36w was 4.2% and 6.9% in the BPD28d and BPD36w patients, respectively. Oligohydramnios and sepsis were significantly associated with PH36w in VLBWIs.