The role of the tumor necrosis factor (TNF)-related weak inducer of apoptosis (TWEAK) in offspring exposed to prenatal hypoxia

Placenta-targeted treatment in hypoxic dams improves maturation and growth of fetal cardiomyocytes in vitro via the release of placental factors

NEW FINDINGS

What is the central question of this study? Does treatment of hypoxic dams with a placenta-targeted antioxidant prevent the release of placenta-derived factors that impair maturation or growth of fetal cardiomyocytes in vitro? What is the main finding and its importance? Factors released from hypoxic placentae impaired fetal cardiomyocyte maturation (induced terminal differentiation) and growth (increased cell size) in vitro, which was prevented by maternal treatment with a placenta-targeted antioxidant (nMitoQ). Moreover, there were no sex differences in the effects of placental factors on fetal cardiomyocyte maturation and growth. Overall, our data suggest that treatment targeted against placental oxidative stress could prevent fetal programming of cardiac diseases via the release of placental factors.

ABSTRACT

Pregnancy complications associated with placental oxidative stress may impair fetal organ development through the release of placenta-derived factors into the fetal circulation. We assessed the effect of factors secreted from placentae previously exposed to prenatal hypoxia on fetal cardiomyocyte development and developed a treatment strategy that targets placental oxidative stress by encapsulating the antioxidant MitoQ into nanoparticles (nMitoQ). We used a rat model of prenatal hypoxia (gestational day (GD) 15-21), which was treated with saline or nMitoQ on GD15. On GD21, placentae were harvested, placed in culture, and conditioned medium (containing placenta-derived factors) was collected after 24 h. This conditioned medium was then added to cultured cardiomyocytes from control dam fetuses. Conditioned medium from prenatally hypoxic placentae increased the percentage of binucleated cardiomyocytes (marker of terminal differentiation) and the size of mononucleated and binucleated cardiomyocytes (sign of hypertrophy), effects that were prevented by nMitoQ treatment. Our data suggest that factors derived from placentae previously exposed to prenatal hypoxia lead to abnormal fetal cardiomyocyte development, and show that treatment against placental oxidative stress may prevent fetal programming of cardiac disease.

Increased uterine artery blood flow in hypoxic murine pregnancy is not sufficient to prevent fetal growth restriction†

Incomplete maternal vascular responses to pregnancy contribute to pregnancy complications including intrauterine growth restriction (IUGR) and preeclampsia. We aimed to characterize maternal vascular dysfunction in a murine model of fetal growth restriction as an approach toward identifying targetable pathways for improving pregnancy outcomes. We utilized a murine model of late-gestation hypoxia-induced IUGR that reduced E18.5 fetal weight by 34%. Contrary to our hypothesis, uterine artery blood flow as measured in vivo by Doppler ultrasound was increased in mice housed under hypobaric hypoxia (385 mmHg; 5500 m) vs normoxia (760 mmHg; 0 m). Using wire myography, uterine arteries isolated from hypoxic mice had similar vasodilator responses to the two activators A769662 and acetylcholine as those from normoxic mice, although the contribution of an increase in nitric oxide production to uterine artery vasodilation was reduced in the hypoxic vs normoxic groups. Vasoconstrictor responses to phenylephrine and potassium chloride were unaltered by hypoxia. The levels of activated adenosine monophosphate-activated protein kinase (AMPK) were reduced with hypoxia in both the uterine artery and placenta as measured by western blot and immunohistochemistry. We concluded that the rise in uterine artery blood flow may be compensatory to hypoxia but was not sufficient to prevent fetal growth restriction. Although AMPK signaling was reduced by hypoxia, AMPK was still receptive to pharmacologic activation in the uterine arteries in which it was a potent vasodilator. Thus, AMPK activation may represent a new therapy for pregnancy complications involving reduced uteroplacental perfusion.

The influence of non-opiate analogue of leu-enkephalin to the cardiac consequences of intrauterine hypoxia of albino rats

Objective ― Our study aimed to evaluate the possibility of correcting cardiac consequences of intrauterine hypoxia (IUH) by injecting leu-enkephalin analog, lacking affinity for opiate receptors, in the early postnatal period. Material and Methods ― To model IUH, we placed pregnant Wistar rats in a hypobaric chamber with an oxygen partial pressure of 52 mmHg. The procedure was repeated for 4 h daily over the 15th-19th days of gestation. From the 2nd through the 6th days of their lives, the offspring were injected intraperitoneally with non-opiate leu-enkephalin analog at a dose of 100 μg/kg (NALE: Phe-D-Ala-Gly-Phe-Leu-Arg). This analog did not have affinity for opiate receptors. The 7- and 60-day old offspring of female rats subjected to IUH were investigated. The control group included the descendants of intact animals. We investigated gravimetric indicators, DNA-synthetic activity of cardiomyocytes (CMC) by tritium-labeled thymidine autoradiography method, the size of the CMC nuclei, as well as size and amount of nucleoli in the CMC nuclei. The activity of free radical oxidation was evaluated in cardiac homogenates by chemiluminescence. Results ― In 7-day old rats subjected to IUH vs. control animals, we observed decreases in body mass by 32.6%, in heart mass by 27.3%; in the proportion of 3Н-thymidine labeled CMC nuclei by 32.7% in the left ventricle and by 30.4% in the right ventricle; in the number of nucleoli in the CMC nuclei (in the left ventricle: control – 2.384±0.027, IUH – 2.282±0.027*, p<0.05; in the right ventricle: control – 2.409±0.038; IUH – 2.240±0.012*, p<0, 05). Increase in CML indices of cardiac homogenates was revealed, indicating the activation of free radical oxidation. In 7-day old rats subjected to IUH and administration of the NALE peptide from the 2nd through the 6th days of their lives, the proportion of 3H-thymidine labeled nuclei in the CMC did not differ from the control (in the left ventricle: control – 12.79±0.89%, IUH + NALE – 10.98±0.95%, p>0.05; in the right ventricle: control – 11.61±0.78%; IUH + NALE – 11.26±0.58%, p>0.05). The number of nucleoli in the CMC nuclei of the left and right ventricles in the heart of 7-day old animals in the IUH + NALE group did not differ from the control too. The CML indices of heart homogenates in the IUH + NALE group were significantly lower than those in the IUH group. In 60-day old male rats exposed to IUH, there was a decrease in heart mass by 18.5%, sizes of CMC nuclei by 7.5% and 16.1% in the left and right ventricles, respectively, and in the total nucleoli area in the CMC nuclei of the left ventricle (control – 3.953±0.085; IUH – 3.372±0.078*; p<0.05). In 60-day old male rats subjected to IUH and injections of the NALE peptide from the 2nd to the 6th days of their lives, heart mass (control – 692.73±26.81 mg; IUH + NALE – 631.0±29.79 mg; p>0.05) and the size of the CMC nuclei of the right ventricle (control – 54.25±0.84; IUH + NALE – 55.24±0.94; p>0.05) did not differ significantly from the control. The size of the nuclei, the number and size of the nucleoli in the CMC of the left ventricle, as well as the area of the nucleoli in the CMC of the right ventricle in 60-day old male rats of the IUH + NALE group significantly exceeded control group values. Conclusion ― Administration of the NALE peptide to albino rats subjected to IUH normalized DNA-synthetic activity and the number of nucleoli in the nuclei of CMC in 7-day old animals, and also reduced the severity of oxidative stress in the heart tissue. In 60-day old albino male rats exposed to IUH, injecting NALE from the 2nd to the 6th days of their lives eliminated declines in heart mass and sizes of the CMC nuclei and nucleoli, and also led to an increase in the values of the nucleus-and-nucleolus complex indices compared with the control.

Developmental origins of nonalcoholic fatty liver disease as a risk factor for exaggerated metabolic and cardiovascular-renal disease

Intrauterine growth restriction (IUGR) is linked to increased risk for chronic disease. Placental ischemia and insufficiency in the mother are implicated in predisposing IUGR offspring to metabolic dysfunction, including hypertension, insulin resistance, abnormalities in glucose homeostasis, and nonalcoholic fatty liver disease (NAFLD). It is unclear whether these metabolic disturbances contribute to the developmental origins of exaggerated cardiovascular-renal disease (CVRD) risk accompanying IUGR. IUGR impacts the pancreas, adipose tissue, and liver, which are hypothesized to program for hepatic insulin resistance and subsequent NAFLD. NAFLD is projected to become the major cause of chronic liver disease and contributor to uncontrolled type 2 diabetes mellitus, which is a leading cause of chronic kidney disease. While NAFLD is increased in experimental models of IUGR, lacking is a full comprehension of the mechanisms responsible for programming of NAFLD and whether this potentiates susceptibility to liver injury. The use of well-established and clinically relevant rodent models, which mimic the clinical characteristics of IUGR, metabolic disturbances, and increased blood pressure in the offspring, will permit investigation into mechanisms linking adverse influences during early life and later chronic health. The purpose of this review is to propose mechanisms, including those proinflammatory in nature, whereby IUGR exacerbates the pathogenesis of NAFLD and how these adverse programmed outcomes contribute to exaggerated CVRD risk. Understanding the etiology of the developmental origins of chronic disease will allow investigators to uncover treatment strategies to intervene in the mother and her offspring to halt the increasing prevalence of metabolic dysfunction and CVRD.