The serum thioredoxin-1 levels are not associated with bronchopulmonary dysplasia and retinopathy of prematurity

Abstract

Background: We hypothesized that the serum TRX-1 in extremely preterm infants (EPIs) after birth was associated with the development of severe bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP).

Methods: This single-centered retrospective study enrolled EPIs treated at our institution. Serum TRX-1 concentrations of the residual samples taken on admission, day 10-20 of life, and 36-40 weeks of postmenstrual age (PMA) were measured with an enzyme-linked immunosorbent assay.

Results: The serum TRX-1 levels on admission were not different between the severe BPD (n = 46) and non-severe BPD groups (n = 67): [median (interquartile range) 147 (73.0-231) vs. 164 (80.5-248) ng/mL] (P = 0.57). These had no significant difference between the severe ROP (n = 47) and non-severe ROP groups (n = 66): [164 (71.3-237) vs. 150 (80.9-250) ng/mL] (P = 0.93). The TRX-1 levels at 10-20 days of life and 36-40 weeks of PMA also had no association with the development of severe BPD and ROP.

Conclusion: The serum TRX-1 levels after birth are not predictive of severe BPD and ROP.

Impact: Serum thioredoxin-1 levels in extremely preterm infants on the day of birth are lower than those in term or near-term infants hospitalized for transient tachypnea of the newborn. In extremely preterm infants, the serum thioredoxin-1 levels on the day of birth, at 10-20 days of life, and at postmenstrual age of 36-40 weeks were not associated with severe bronchopulmonary dysplasia and retinopathy of prematurity. The thioredoxin system is under development in extremely preterm infants; however, the serum thioredoxin-1 level is not predictive for severe bronchopulmonary dysplasia and retinopathy of prematurity.

Fig. 1. Flow diagram presenting the number of patients at each step in the study.

GA gestational age, NICU neonatal intensive care unit, PMA postmenstrual age, BPD bronchopulmonary dysplasia, ROP retinopathy of prematurity.

Fig. 2. Box-whisker plots of thioredoxin-1 (TRX-1) in the extremely preterm infants (EPIs) and control groups.

The median (interquartile range) of TRX levels on admission in the EPIs group was 153 (74.5–242) ng/mL, and that in the control group was 267 (150–428) ng/mL. The TRX-1 of the EPIs group was significantly lower than that of the control group (P < 0.001). EPIs extremely preterm infants, TRX-1 thioredoxin-1.

Fig. 3. Histograms of the serum thioredoxin-1 levels at the day of birth

Histograms of the serum thioredoxin-1 levels in extremely preterm infants (a) and controls (b). Both histograms show the distributions of TRX-1 skewed to the right. TRX-1 thioredoxin-1.

Fig. 4. Changes of the serum thioredoxin-1 levels after birth.

Thioredoxin-1 levels were measured in the residual serum samples taken on the day of birth, at 10–20 days of birth, and at 36–40 weeks of postmenstrual age. Square, round, triangle, and inverted triangle symbols indicate the patients without severe BPD or ROP, those with severe BPD only, those with severe ROP only, and those with severe BPD and ROP. Each patient’s value is connected with a black line. Median (interquartile range) of the serum TRX-1 levels on the day of birth, at 10–20 days of life, and 36–40 weeks of PMA was 153 (74.5–242), 111 (65.1–234), and 33.6 (18.2–87.2) ng/mL, respectively. The Wilcoxon signed-rank test showed a significant difference between on the day of birth and at 36–40 weeks of PMA (P < 0.001). No significant difference was shown between on the day of birth and at 10–20 days of life. TRX-1 thioredoxin-1.