Postnatal gene expression of airway epithelial sodium transporters associated with birth stress in humans

Does the use of antenatal corticosteroids reduce respiratory morbidity in babies born in late preterm period?

BACKGROUND

The aim of this study is to determine the effectiveness of antenatal corticosteroid in reducing respiratory morbidity in babies born in the late preterm period.

METHODS

Two hundred and eighty-six pregnant women at risk of having a late preterm delivery were studied. One hundred and forty-three (143) served as the cases and were given 2 doses of 12 mg intramuscular dexamethasone 12 h apart, while 143 served as the controls and were given a similar quantity of placebo. The women were followed up prospectively and data were collected on the pregnant women and their newborns on a standardized form. The neonates were assessed for acute respiratory distress syndrome and transient tachypnea of the newborn based on clinical signs, symptoms, and chest x-ray results (when indicated). The primary outcome was the occurrence of neonatal respiratory morbidity.

RESULTS

The primary outcome occurred in 5 out of 130 infants (3.8%) in the dexamethasone group and 31 out of 122 (25.4%) in the placebo group (P value = 0.000003). Birth asphyxia, neonatal intensive care admission and need for active resuscitation at birth also occurred significantly less frequently in the dexamethasone group (P value 0.004, 0.009, 0.014 respectively). There were no significant group differences in the incidence of neonatal sepsis, neonatal jaundice, hypoglycemia and feeding difficulties.

CONCLUSIONS

Administration of dexamethasone to women at risk for late preterm delivery significantly reduced the rate of neonatal respiratory complications, neonatal intensive care unit admission, and need for active resuscitation at birth.

TRIAL REGISTRATION

PACTR ( www.pactr.org ) Registration Number: PACTR202304579281358. The study was retrospectively registered on April 19, 2023.

Molecular insights using spatial transcriptomics of the distal lung in congenital diaphragmatic hernia

Abnormal pulmonary vascular development and function in congenital diaphragmatic hernia (CDH) is a significant factor leading to pulmonary hypertension. The lung is a very heterogenous organ and has marked cellular diversity that is differentially responsive to injury and therapeutic agents. Spatial transcriptomics provides the unmatched capability of discerning the differences in the transcriptional signature of these distinct cell subpopulations in the lung with regional specificity. We hypothesized that the distal lung parenchyma (selected as a region of interest) would show a distinct transcriptomic profile in the CDH lung compared with control (normal lung). We subjected lung sections obtained from male and female CDH and control neonates to spatial transcriptomics using the Nanostring GeoMx platform. Spatial transcriptomic analysis of the human CDH and control lung revealed key differences in the gene expression signature. Increased expression of alveolar epithelial-related genes (SFTPA1 and SFTPC) and angiogenesis-related genes (EPAS1 and FHL1) was seen in control lungs compared with CDH lungs. Response to vitamin A was enriched in the control lungs as opposed to abnormality of the coagulation cascade and TNF-alpha signaling via NF-kappa B in the CDH lung parenchyma. In male patients with CDH, higher expression of COL1A1 (ECM remodeling) and CD163 was seen. Increased type 2 alveolar epithelial cells (AT-2) and arterial and lung capillary endothelial cells were seen in control lung samples compared with CDH lung samples. To the best of our knowledge, this is the first use of spatial transcriptomics in patients with CDH that identifies the contribution of different lung cellular subpopulations in CDH pathophysiology and highlights sex-specific differences.NEW & NOTEWORTHY This is the first use of spatial transcriptomics in patients with congenital diaphragmatic hernia (CDH) that identifies the contribution of different lung cellular subpopulations in CDH pathophysiology and highlights sex-specific differences.

Influence of Alveolar Fluid on Aquaporins and Na+/K+-ATPase and Its Possible Theoretical or Clinical Significance

OBJECTIVE

Pulmonary edema is the most common pathophysiological change in pulmonary disease. Aquaporins (AQPs) and Na⁺/K⁺-ATPase play pivotal roles in alveolar fluid clearance. This study aimed to explore the influence of increased alveolar fluid on the absorption of lung fluid.

STUDY DESIGN

Eighty New Zealand rabbits were randomly divided into eight groups (n = 10 in each group), and models of different alveolar fluid contents were established by the infusion of different volumes of normal saline (NS) via the endotracheal tube. Five animals in each group were sacrificed immediately after infusion to determine the wet/dry ratio, while the remaining animals in each group were killed 4 hours later to determine the wet/dry ratio at 4 hours. Additionally, lung specimens were collected from each group, and quantitative real-time PCR (qRT-PCR), western blot, and immunohistochemical (IHC) analyses of AQPs and Na⁺/K⁺-ATPase were performed.

RESULTS

The qRT-PCR analysis and western blot studies showed markedly decreased mRNA and protein levels of AQP1 and Na⁺/K⁺-ATPase when the alveolar fluid volume was ≥6 mL/kg, and the mRNA level of AQP5 was significantly reduced when the alveolar fluid volume was ≥4 mL/kg. In addition, IHC analysis showed the same results. At 4 hours, the lung wet/dry ratio was significantly increased when the alveolar fluid volume was ≥6 mL/kg; however, compared with 0 hours after NS infusion, there was still a significant absorption of alveolar fluid for a period of 4 hours.

CONCLUSION

The results of this study suggest that increased alveolar fluid may induce the downregulation of the mRNA and protein expression of AQPs and Na⁺/K⁺-ATPase, which appear to affect alveolar fluid clearance in rabbit lungs. Early intervention is required to avoid excessive alveolar fluid accumulation.

KEY POINTS

· The expression levels of AQPs and Na+/K+--ATPase were significantly decreased as alveolar fluid increased.. · At 4 hours, wet/dry ratio was significantly increased when infusion volume was ≥ 6 mL/kg.. · Early intervention is required to avoid excessive alveolar fluid accumulation..

The Relationship between Antenatal Corticosteroid Administration-to-Delivery Intervals and Neonatal Respiratory Distress Syndrome and Respiratory Support

Background

Administration of antenatal corticosteroids (ACSs) is an effective strategy for managing preterm infants, which improves neonatal respiratory distress syndrome (NRDS) and attenuates the risk of neonatal mortality. However, many preterm infants are not exposed to a complete course of ACS administration, and the effects of different ACS-to-delivery intervals on NRDS and respiratory support remain unclear. Therefore, this study explored the relationship between ACS-to-birth intervals and NRDS and respiratory support in preterm infants.

Methods

In this retrospective cohort study, the preterm infants born between 240/7 and 316/7 wks of gestation were recruited from January 2015 to July 2021. All participants were categorised based on the time interval from the first ACS dose to delivery: <24 h, 1-2 d, 2–7 d, and >7 d. Multivariable logistic regression analysis examined the relationships between the ACS-to-birth interval and primary or secondary outcome while adjusting for potential confounders.

Results

Of the 706 eligible neonates, 264, 83, 292, and 67 received ACS-to-delivery intervals of <24 h, 1-2 d, 2–7 d, and >7 d, respectively. After adjusting these confounding factors, the multivariable logistic analysis showed a significantly increased risk of NRDS (aOR: 1.8, 95% CI: 1.2–2.7), neonatal mortality (aOR: 2.8, 95% CI: 1.1–6.8), the need for surfactant use (aOR: 2.7, 95% CI: 1.7–4.4), endotracheal intubation in the delivery room (aOR: 1.9, 95% CI: 1.0–3.7), and mechanical ventilation (aOR: 1.9, 95% CI: 1.1–3.4) in the ACS-to-delivery interval of <24 h group when compared with the ACS-to-birth interval of 2–7 d group.

Conclusions

Neonatal outcomes such as NRDS, neonatal mortality, the need for surfactant use, intubation in the delivery room, and the risk of mechanical ventilation are higher when the neonates are exposed to an ACS interval for less than 24 h before delivery.

Nasal expression of SARS-CoV-2 entry receptors in newborns

BACKGROUND

SARS-CoV-2 infection is typically mild in children. Lower expression of SARS-CoV-2 entry receptors in the nasal epithelia have been described in children compared with adults. However, data from newborns are lacking. We compared nasal expression of four SARS-CoV-2 entry receptors between term and preterm newborns and adults.

METHODS

Nasal scrape samples were obtained from 28 newborns (17 term and 11 preterm) and 10 adults. Reverse-transcription quantitative PCR was used to measure mRNA expression of ACE2, transmembrane serine protease 2 (TMPRSS2), neuropilin 1 (NRP1) and neuropilin 2 (NRP2) and insulin-like growth factor 1 receptor (IGF1R).

RESULTS

Expression levels of ACE2, TMPRSS2, NRP1 and NRP2 were lower in term and preterm newborns and IGF1R lower in term newborns compared with adults (p<0.05).

CONCLUSIONS

Both term and preterm newborns, compared with adults, have lower expression of SARS-CoV-2 entry receptors in nasal epithelium.

Aquaporins and (in)fertility: More than just water transport

Aquaporins (AQPs) are a family of channel proteins that facilitate the transport of water and small solutes across biological membranes. They are widely distributed throughout the organism, having a number of key functions, some of them unexpected, both in health and disease. Among the various diseases in which AQPs are involved, infertility has been overlooked. According to the World Health Organization (WHO) infertility is a global public health problem with one third of the couples suffering from subfertility or even infertility due to male or female factors alone or combined. Thus, there is an urgent need to unveil the molecular mechanisms that control gametes production, maturation and fertilization-related events, to more specifically determine infertility causes. In addition, as more couples seek for fertility treatment through assisted reproductive technologies (ART), it is pivotal to understand how these techniques can be improved. AQPs are heterogeneously expressed throughout the male and female reproductive tracts, highlighting a possible regulatory role for these proteins in conception. In fact, their function, far beyond water transport, highlights potential intervention points to enhance ART. In this review we discuss AQPs distribution and structural organization, functions, and modulation throughout the male and female reproductive tracts and their relevance to the reproductive success. We also highlight the most recent advances and research trends regarding how the different AQPs are involved and regulated in specific mechanisms underlying (in)fertility. Finally, we discuss the involvement of AQPs in ART-related processes and how their handling can lead to improvement of infertility treatment.