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Oxidation-reduction (redox) controls fetal hypoplastic lung growth
Jason C Fisher1, David E Kling, T Bernard Kinane
1Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA.
Insights
N-acetylcysteine significantly enhanced fetal lung growth in organ culture by increasing reduced glutathione levels. This supports the role of redox mechanisms in regulating fetal lung development, offering potential therapeutic insights.
Area of Science:
- Developmental biology
- Pulmonary medicine
- Biochemistry
Background:
- Congenital diaphragmatic hernia (CDH) leads to persistent pulmonary hypoplasia, a major cause of mortality.
- Previous studies indicated antioxidants accelerate fetal lung growth in culture.
- A reductant mechanism was hypothesized to underlie antioxidant effects on lung growth.
Purpose of the Study:
- To investigate the effect of N-acetylcysteine (NAC) on nitrofen-induced fetal lung hypoplasia in organ culture.
- To determine if NAC influences the redox state of fetal lung tissue.
Main Methods:
- Nitrofen-induced hypoplastic rat fetal lungs were cultured for 4 days.
- Organ cultures were treated with N-acetylcysteine (100 microM) or a control medium.
- Lung airway growth (bud count, perimeter, area) was measured daily.
- Reduced and oxidized glutathione levels were assayed to estimate tissue redox potential.
Main Results:
- NAC treatment significantly increased fetal lung area, perimeter, and bud count.
- N-acetylcysteine administration led to a significant increase in reduced glutathione levels.
- The ratio of reduced to oxidized glutathione was elevated in NAC-treated lungs.
Conclusions:
- N-acetylcysteine promotes the growth of hypoplastic fetal lungs in an organ culture model.
- NAC treatment enhances the reduced glutathione status, indicating a shift in redox potential.
- These findings suggest that oxidation-reduction (redox) mechanisms are critical regulators of fetal lung development.
Introduction:
The persistent morbidity and mortality of congenital diaphragmatic hernia are largely due to associated pulmonary hypoplasia. We have shown previously that three antioxidants (vitamin C, glutathione, and vitamin E) could accelerate the growth of fetal hypoplastic lungs grown in culture. We hypothesize that this occurs via a reductant mechanism.
Methods:
Timed-pregnant rats were gavage-fed nitrofen (100 mg) on day 9.5 of gestation (term = day 22). Fetal lungs were harvested on day 13.5 and placed in organ culture containing serum-free BGJb medium with antibiotics. After randomization, the lung organ cultures were divided into a control group (n = 31) and an experimental group that received the antioxidant N-acetylcysteine (NAC, 100 microM, n = 31). The fetal lung organ cultures were grown for 4 days at 37 degrees C with 5% CO(2). Computer-assisted digital tracings of the airways were performed daily on live, unstained specimens, and lung bud count, perimeter, and area were measured. After 4 days, lungs were pooled, homogenized, and assayed for reduced and oxidized glutathione, normalized to protein, as an estimate of the tissue redox potential. Data were expressed as means +/- SEM, and statistical comparisons were performed using Student's unpaired t test, with P < 0.05 considered significant.
Results:
Area, perimeter, lung bud count, and complexity (as measured by the perimeter/square root of area) were all significantly increased with NAC treatment from day 2 onward. Reduced glutathione levels were significantly increased following NAC administration (67.1 +/- 5.8 versus 37.5 +/- 4.2 micromol/mg, P = 0.0004). The ratio of reduced to oxidized glutathione was 2.23.
Conclusions:
N-Acetylcysteine stimulates nitrofen-induced hypoplastic fetal lung growth in organ culture and increases the ratio of reduced to oxidized glutathione. These data support the concept that oxidation-reduction (redox) may be an important control mechanism for fetal lung growth.