All Trans Retinoic Acid (ATRA) progresses alveolar epithelium regeneration by involving diverse signalling pathways in emphysematous rat

Early postnatal high-dose fat-soluble enteral vitamin A supplementation for moderate or severe bronchopulmonary dysplasia or death in extremely low birthweight infants (NeoVitaA): a multicentre, randomised, parallel-group, double-blind, placebo-controlled, investigator-initiated phase 3 trial

BACKGROUND

Vitamin A plays a key role in lung development, but there is no consensus regarding the optimal vitamin A dose and administration route in extremely low birthweight (ELBW) infants. We aimed to assess whether early postnatal additional high-dose fat-soluble enteral vitamin A supplementation versus placebo would lower the rate of moderate or severe bronchopulmonary dysplasia or death in ELBW infants receiving recommended basic enteral vitamin A supplementation.

METHODS

This prospective, multicentre, randomised, parallel-group, double-blind, placebo-controlled, investigator-initiated phase 3 trial conducted at 29 neonatal intensive care units in Austria and Germany assessed early high-dose enteral vitamin A supplementation (5000 international units [IU]/kg per day) or placebo (peanut oil) for 28 days in ELBW infants. Eligible infants had a birthweight of more than 400 g and less than 1000 g; gestational age at birth of 32+0 weeks postmenstrual age or younger; and the need for mechanical ventilation, non-invasive respiratory support, or supplemental oxygen within the first 72 h of postnatal age after admission to the neonatal intensive care unit. Participants were randomly assigned by block randomisation with variable block sizes (two and four). All participants received basic vitamin A supplementation (1000 IU/kg per day). The composite primary endpoint was moderate or severe bronchopulmonary dysplasia or death at 36 weeks postmenstrual age, analysed in the intention-to-treat population. This trial was registered with EudraCT, 2013-001998-24.

FINDINGS

Between March 2, 2015, and Feb 27, 2022, 3066 infants were screened for eligibility at the participating centres. 915 infants were included and randomly assigned to the high-dose vitamin A group (n=449) or the control group (n=466). Mean gestational age was 26·5 weeks (SD 2·0) and mean birthweight was 765 g (162). Moderate or severe bronchopulmonary dysplasia or death occurred in 171 (38%) of 449 infants in the high-dose vitamin A group versus 178 (38%) of 466 infants in the control group (adjusted odds ratio 0·99, 95% CI 0·73-1·55). The number of participants with at least one adverse event was similar between groups (256 [57%] of 449 in the high-dose vitamin A group and 281 [60%] of 466 in the control group). Serum retinol concentrations at baseline, at the end of intervention, and at 36 weeks postmenstrual age were similar in the two groups.

INTERPRETATION

Early postnatal high-dose fat-soluble enteral vitamin A supplementation in ELBW infants was safe, but did not change the rate of moderate or severe bronchopulmonary dysplasia or death and did not substantially increase serum retinol concentrations.

FUNDING

Deutsche Forschungsgemeinschaft and European Clinical Research Infrastructures Network (ECRIN).

The early and late intervention effects of collagen-binding FGF2 on elastase-induced lung injury

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) has high morbidity and mortality, with no effective treatment at present. Emphysema, a major component of COPD, is a leading cause of human death worldwide. Fibroblast growth factor 2 (FGF2) is implicated in the pathogenesis of pulmonary emphysema and may play an important role in the lung repair process after injury, but concerns remain with respect to its effectiveness.

OBJECTIVE

In the present work, we sought to determine how the timing (early and late intervention) of sustained-release FGF2 system administration impacted its effectiveness on a porcine pancreatic elastase (PPE)-induced lung injury mouse model.

METHODS

To examine the early intervention efficiency of collagen-binding FGF2 (CBD-FGF2), mice received intratracheally nebulized CBD-FGF2 with concurrent intratracheal injection of PPE. To explore the late intervention effect, CBD-FGF2 was intratracheally aerosolized after PPE administration, and lungs were collected after CBD-FGF2 treatment for subsequent analysis.

RESULT

In response to PPE, mice had significantly increased alveolar diameter, collagen deposition and expression of inflammatory factors and decreased lung function indices and expression of alveolar epithelium markers. Our results indicate that CBD-FGF2 administration was able to prevent and repair elastase-induced lung injury partly through the suppression of the inflammatory response and recovery of the alveolar epithelium. The early use of CBD-FGF2 for the prevention of PPE-induced emphysema showed better results than late therapeutic administration against established emphysema.

CONCLUSION

These data provide insight regarding the prospective role of a drug-based option (CBD-FGF2) for preventing and curing emphysema.

Am80-Encapsulated Lipid Nanoparticles, Developed with the Aim of Achieving Alveolar Regeneration, Have an Improvement Effect on Pulmonary Emphysema

Chronic obstructive pulmonary disease (COPD) is characterized by chronic bronchitis and emphysema, and current drug treatments target its symptoms. Thus, the development of a therapeutic drug to repair alveolar destruction is urgently needed. Our previous research revealed that the synthetic retinoic acid Am80 (1.0 mg/kg) showed a repairing effect on collapsed alveoli in a mouse model of elastase-induced emphysema. However, a further reduction in the dose is desirable to facilitate the development of a powder inhalation formulation for clinical application. We, therefore, focused on SS-OP to deliver Am80 efficiently. As a result, 0.01 mg/kg of Am80-encapsulated SS-OP nanoparticles repaired collapsed alveoli and improved the respiratory function in the mouse model of elastase induced emphysema. The results suggested that, with the use of SS-OP, the Am80 dose could be reduced. This could contribute to the development of a powder inhalation system as a curative medicine for COPD.

All‑trans retinoic acid promotes macrophage phagocytosis and decreases inflammation via inhibiting CD14/TLR4 in acute lung injury

Acute lung injury (ALI) is a common clinical emergency and all-trans retinoic acid (ATRA) can alleviate organ injury. Therefore, the present study investigated the role of ATRA in ALI. Lipopolysaccharide (LPS)-induced ALI rats were treated with ATRA and the arterial partial pressure of oxygen (PaO₂), lung wet/dry weight (W/D) ratio and protein content in the bronchial alveolar lavage fluid (BALF) were measured to evaluate the effect of ATRA on ALI rats. Alveolar macrophages were isolated from the BALF. The phagocytic function of macrophages was detected using the chicken erythrocyte phagocytosis method and flow cytometry. The viability of macrophages was measured using a Cell Counting Kit-8 assay, and apoptosis was analyzed using a TUNEL assay and flow cytometry. The expression levels of Toll-like receptor 4 (TLR4) and cluster of differentiation (CD)14 on the macrophage membrane were detected by immunofluorescence staining. The protein levels of TLR4, CD14, phosphorylated (p)-65, p65, p-IκBα and IκBα were analyzed using western blotting. The concentrations of IL-6, IL-1β and macrophage inflammatory protein-2 in the plasma of rats were detected by ELISA. Macrophages were treated with IAXO-102 (TLR4 inhibitor) to verify the involvement of CD14/TLR4 in the effect of ATRA on ALI. ATRA provided protection against LPS-induced ALI, as evidenced by the increased PaO₂ and reduced lung W/D ratio and protein content in the BALF. ATRA enhanced macrophage phagocytosis and viability and reduced apoptosis and inflammation in ALI rats. Mechanically, ATRA inhibited CD14 and TLR4 expression and NF-κB pathway activation. ATRA enhanced macrophage phagocytosis and reduced inflammation by inhibiting the CD14/TLR4-NF-κB pathway in LPS-induced ALI. In summary, ATRA inactivated the NF-κB pathway by inhibiting the expression of CD14/TLR4 receptor in the alveolar macrophages of rats, thus enhancing the phagocytic function of macrophages in ALI rats, improving the activity of macrophages, inhibiting apoptosis, reducing the levels of inflammatory factors, and consequently playing a protective role in ALI model rats. This study may offer novel insights for the clinical management of ALI.