Neonatal hyperoxia exposure leads to developmental programming of cardiovascular and renal disease in adult rats.

Premature infants are often exposed to hyperoxia. However, there is limited data regarding the mechanistic underpinnings linking neonatal hyperoxia exposure and its contribution to cardio-renal dysfunction in adults born preterm. Our objective was to determine whether neonatal hyperoxia induces systemic vascular stiffness and cardio-renal dysfunction in adulthood. Newborn rats were randomly assigned to room air (RA) or hyperoxia (85% O2) from postnatal day 1 to 14, then recovered in RA until 1 year of life. Arterial stiffness, cardio-renal histomorphometry, and fibrosis in the aorta, heart, and kidney were assessed. RNA-sequencing (RNA-seq) of the aorta and kidney was also done. Adult rats exposed to neonatal hyperoxia had increased aortic and mesenteric artery stiffness as demonstrated by wire and pressure myography. They also had cardiomyocyte hypertrophy, glomerulomegaly, and tubular injury. Hyperoxia exposure altered the transcriptome profile associated with fibrosis and matrix remodeling in the aorta and kidney. There was also increased TGF-ß1 levels and fibrosis in the aorta, left ventricle, and kidney. In conclusion, neonatal hyperoxia exposure was associated with systemic vascular and cardio-renal alterations in 1-year-old rats. Further studies to determine how targeted therapies could reprogram cardio-renal injury after neonatal hyperoxia exposure are indicated.

Association Between Hypertensive Disorders of Pregnancy and Interval Neurocognitive Decline: An Analysis of the Hispanic Community Health Study/Study of Latinos.

OBJECTIVE: To evaluate whether hypertensive disorders of pregnancy, including gestational hypertension, preeclampsia, and eclampsia, are associated with cognitive decline later in life among U.S. Hispanic/Latina individuals. METHODS: The HCHS/SOL (Hispanic Community Health Study/Study of Latinos) is a prospective population-based study of Hispanic/Latino individuals aged 18-74 years from four U.S. communities. This analysis included parous individuals aged 45 years or older who participated in the HCHS/SOL clinic study visit 1 (2008-2011) neurocognitive assessment and subsequently completed a repeat neurocognitive assessment as part of the Study of Latinos-Investigation of Neurocognitive Aging ancillary study visit 2 (2015-2018). Hypertensive disorders of pregnancy were assessed retrospectively by self-report of any gestational hypertension, preeclampsia, or eclampsia. Cognitive functioning was measured at both study visits with the Brief Spanish-English Verbal Learning Test, Digit Symbol Substitution, and Word Fluency. A regression-based approach was used to define cognitive decline at visit 2 as a function of cognition at visit 1 after adjustment for age, education, and follow-up time. Linear regression models were used to determine whether hypertensive disorders of pregnancy or their component diagnoses were associated with standardized cognitive decline after adjustment for sociodemographic characteristics, clinical and behavioral risk factors, and follow-up time. RESULTS: Among 3,554 individuals included in analysis, the mean age was 56.2 years, and 467 of individuals (13.4%) reported at least one hypertensive disorder of pregnancy. Individuals with hypertensive disorders of pregnancy compared with those without were more likely to have higher mean systolic blood pressure, fasting glucose, and body mass index. After an average of 7 years of follow-up, in fully adjusted models, gestational hypertension was associated with a 0.17-SD relative decline in Digit Symbol Substitution scores (95% CI, -0.31 to -0.04) but not other cognitive domains (Brief Spanish-English Verbal Learning Test or Word Fluency). Neither preeclampsia nor eclampsia was associated with neurocognitive differences. CONCLUSION: The presence of preeclampsia or eclampsia was not associated with interval neurocognitive decline. In this cohort of U.S. Hispanic/Latina individuals, gestational hypertension alone was associated with decreased processing speed and executive functioning later in life.

Cardiac Abnormalities in Hispanic/Latina Women With Prior De Novo Hypertensive Disorders of Pregnancy.

BACKGROUND: Hypertensive disorders of pregnancy (HDP) are associated with long-term maternal risks for cardiovascular disease for reasons that remain incompletely understood. METHODS: The HCHS/SOL (Hispanic Community Health Study/Study of Latinos), a multi-center community-based cohort of Hispanic/Latino adults recruited 2008 to 2011, was used to evaluate the associations of history of de novo HDP (gestational hypertension, preeclampsia, eclampsia) with echocardiographic measures of cardiac structure and function in Hispanic/Latina women with ≥1 prior pregnancy and the proportion of association mediated by current hypertension (>140/90 mm Hg or antihypertensive therapy). RESULTS.: The study cohort included 5168 Hispanic/Latina women with an average age (SD) of 58.7 (9.7) years at time of echocardiogram. Prior de novo HDP was reported by 724 (14%) of the women studied and was associated with lower left ventricle (LV) ejection fraction -0.66 (95% confidence interval [CI], -1.21 to -0.11), higher LV relative wall thickness 0.09 (95% CI, 0-0.18), and 1.39 (95% CI, 1.02-1.89) higher risk of abnormal LV geometry after adjusting for blood pressure and other confounders. The proportion of the association mediated by current hypertension between HDP and LV ejection fraction was 0.09 (95% CI, 0.03-0.45), LV relative wall thickness was 0.28 (95% CI, 0.16-0.51), abnormal LV geometry was 0.14 (95% CI, 0.12-0.48), concentric left ventricular hypertrophy was 0.31 (95% CI, 0.19-0.86), and abnormal LV diastolic dysfunction was 0.58 (95% CI, 0.26-0.79). CONCLUSIONS.: In a large cohort of Hispanic/Latina women those with history of de novo HDP had detectable and measurable subclinical alterations in cardiac structure and both systolic and diastolic dysfunction that were only partially mediated by current hypertension.

Protective role of CXCR7 activation in neonatal hyperoxia-induced systemic vascular remodeling and cardiovascular dysfunction in juvenile rats.

Neonatal hyperoxia induces long-term systemic vascular stiffness and cardiovascular remodeling, but the mechanisms are unclear. Chemokine receptor 7 (CXCR7) represents a key regulator of vascular homeostasis and repair by modulating TGF-ß1 signaling. This study investigated whether pharmacological CXCR7 agonism prevents neonatal hyperoxia-induced systemic vascular stiffness and cardiac dysfunction in juvenile rats. Newborn Sprague Dawley rat pups assigned to room air or hyperoxia (85% oxygen), received CXCR7 agonist, TC14012 or placebo for 3 weeks. These rat pups were maintained in room air until 6 weeks when aortic pulse wave velocity doppler, cardiac echocardiography, aortic and left ventricular (LV) fibrosis were assessed. Neonatal hyperoxia induced systemic vascular stiffness and cardiac dysfunction in 6-week-old rats. This was associated with decreased aortic and LV CXCR7 expression. Early treatment with TC14012, partially protected against neonatal hyperoxia-induced systemic vascular stiffness and improved LV dysfunction and fibrosis in juvenile rats by decreasing TGF-ß1 expression. In vitro, hyperoxia-exposed human umbilical arterial endothelial cells and coronary artery endothelial cells had increased TGF-ß1 levels. However, treatment with TC14012 significantly reduced the TGF-ß1 levels. These results suggest that dysregulation of endothelial CXCR7 signaling may contribute to neonatal hyperoxia-induced systemic vascular stiffness and cardiac dysfunction.

Age-dependent effect on contralateral testicular compensation after testicular loss.

OBJECTIVE: To study compensatory changes in testicular growth and the hormonal axis after unilateral orchiectomy in a neonatal, prepubertal, and pubertal/adult murine model. This is the first study to use a neonatal mouse survival surgery model. DESIGN: A laboratory-based study examining a control, neonatal, prepubertal, and pubertal/adult mouse model. SETTING: University-based basic science research laboratory. ANIMALS: Control, neonatal (2-4 days of life), prepubertal (12-21 days of life), and pubertal/adult (42-44 days of life) C57BL/6 mouse models. INTERVENTION: Unilateral orchiectomy in the neonatal, prepubertal, and pubertal/adult mouse models at their respective ages. MAIN OUTCOME MEASURES: Body and testis weight and testicular length in the long axis were measured in a blinded fashion. In a similar way, testosterone, luteinizing hormone (LH), and follicle-stimulating hormone were assessed. RESULTS: Testes from neonatal and prepubertal mice weighed more (110.5, 12.2 and 103.0, 7.2 mg, respectively) than the control mice (91, 11.9 mg). There was no difference between the postpubertal group and the control group. The degree of compensatory hypertrophy was greater in the neonatal group but not in the prepubertal group when compared with the postpubertal group. Differences in follicle-stimulating hormone and testosterone were not statistically significant between the experimental and control arms. LH was significantly elevated in all experimental groups compared with the control. CONCLUSIONS: This is the first study to assess testicular compensatory hypertrophy using a neonatal mouse survival surgery model. Testicular hypertrophy occurs when unilateral loss occurs before puberty, but not in adulthood in mice. Earlier testis loss may contribute to a greater degree of growth. Functionally, the unilateral testis can maintain eugonadal testosterone levels, but higher levels of LH are required after hemicastration to sustain eugonadal testosterone levels.

Synthetic growth hormone-releasing hormone agonist ameliorates the myocardial pathophysiology characteristic of heart failure with preserved ejection fraction.

AIMS: To test the hypothesis that the activation of the growth hormone-releasing hormone (GHRH) receptor signalling pathway within the myocardium both prevents and reverses diastolic dysfunction and pathophysiologic features consistent with heart failure with preserved ejection fraction (HFpEF). Impaired myocardial relaxation, fibrosis, and ventricular stiffness, among other multi-organ morbidities, characterize the phenotype underlying the HFpEF syndrome. Despite the rapidly increasing prevalence of HFpEF, few effective therapies have emerged. Synthetic agonists of the GHRH receptors reduce myocardial fibrosis, cardiomyocyte hypertrophy, and improve performance in animal models of ischaemic cardiomyopathy, independently of the growth hormone axis. METHODS AND RESULTS: CD1 mice received 4- or 8-week continuous infusion of angiotensin-II (Ang-II) to generate a phenotype with several features consistent with HFpEF. Mice were administered either vehicle or a potent synthetic agonist of GHRH, MR-356 for 4-weeks beginning concurrently or 4-weeks following the initiation of Ang-II infusion. Ang-II-treated animals exhibited diastolic dysfunction, ventricular hypertrophy, interstitial fibrosis, and normal ejection fraction. Cardiomyocytes isolated from these animals exhibited incomplete relaxation, depressed contractile responses, altered myofibrillar protein phosphorylation, and disturbed calcium handling mechanisms (ex vivo). MR-356 both prevented and reversed the development of the pathological phenotype in vivo and ex vivo. Activation of the GHRH receptors increased cAMP and cGMP in cardiomyocytes isolated from control animals but only cAMP in cardiac fibroblasts, suggesting that GHRH-A exert differential effects on cardiomyocytes and fibroblasts. CONCLUSION: These findings indicate that the GHRH receptor signalling pathway(s) represents a new molecular target to counteract dysfunctional cardiomyocyte relaxation by targeting myofilament phosphorylation and fibrosis. Accordingly, activation of GHRH receptors with potent, synthetic GHRH agonists may provide a novel therapeutic approach to management of the myocardial alterations associated with the HFpEF syndrome.

c-Myc Drives inflammation of the maternal-fetal interface, and neonatal lung remodeling induced by intra-amniotic inflammation.

Background: Intra-amniotic inflammation (IAI) is associated with increased risk of preterm birth and bronchopulmonary dysplasia (BPD), but the mechanisms by which IAI leads to preterm birth and BPD are poorly understood, and there are no effective therapies for preterm birth and BPD. The transcription factor c-Myc regulates various biological processes like cell growth, apoptosis, and inflammation. We hypothesized that c-Myc modulates inflammation at the maternal-fetal interface, and neonatal lung remodeling. The objectives of our study were 1) to determine the kinetics of c-Myc in the placenta, fetal membranes and neonatal lungs exposed to IAI, and 2) to determine the role of c-Myc in modulating inflammation at the maternal-fetal interface, and neonatal lung remodeling induced by IAI. Methods: Pregnant Sprague-Dawley rats were randomized into three groups: 1) Intra-amniotic saline injections only (control), 2) Intra-amniotic lipopolysaccharide (LPS) injections only, and 3) Intra-amniotic LPS injections with c-Myc inhibitor 10058-F4. c-Myc expression, markers of inflammation, angiogenesis, immunohistochemistry, and transcriptomic analyses were performed on placenta and fetal membranes, and neonatal lungs to determine kinetics of c-Myc expression in response to IAI, and effects of prenatal systemic c-Myc inhibition on lung remodeling at postnatal day 14. Results: c-Myc was upregulated in the placenta, fetal membranes, and neonatal lungs exposed to IAI. IAI caused neutrophil infiltration and neutrophil extracellular trap (NET) formation in the placenta and fetal membranes, and neonatal lung remodeling with pulmonary hypertension consistent with a BPD phenotype. Prenatal inhibition of c-Myc with 10058-F4 in IAI decreased neutrophil infiltration and NET formation, and improved neonatal lung remodeling induced by LPS, with improved alveolarization, increased angiogenesis, and decreased pulmonary vascular remodeling. Discussion: In a rat model of IAI, c-Myc regulates neutrophil recruitment and NET formation in the placenta and fetal membranes. c-Myc also participates in neonatal lung remodeling induced by IAI. Further studies are needed to investigate c-Myc as a potential therapeutic target for IAI and IAI-associated BPD.

Neonatal intermittent hypoxia persistently impairs lung vascular development and induces long-term lung mitochondrial DNA damage.

Adults born preterm have an increased risk of pulmonary vascular disease. Extreme preterm infants often require supplemental oxygen but they also exhibit frequent intermittent hypoxemic episodes (IH). Here, we test the hypothesis that neonatal IH induces lung endothelial cell mitochondrial DNA (mitDNA) damage and contributes to long-term pulmonary vascular disease and pulmonary hypertension (PH). Newborn C57BL/6J mice were assigned to the following groups: 1) normoxia, 2) hyperoxia (O2 65%), 3) normoxia cycling with IH (O2 21% + O2 10%), and 4) hyperoxia cycling with IH (O2 65% + O2 10%) for 3 wk. IH episodes were initiated on postnatal day 7. Lung angiogenesis, PH, and mitDNA lesions were assessed at 3 wk and 3 mo. In vitro, the effect of IH on tubule formation and mitDNA lesions was evaluated in human pulmonary microvascular endothelial cells (HPMECs). Data were analyzed by ANOVA. In vitro, IH exposure reduced tubule formation and increased mitDNA lesions in HPMECs. This was most marked in HPMECs exposed to hyperoxia cycling with IH. In vivo, neonatal IH increased lung mitDNA lesions, impaired angiogenesis, and induced PH in 3-wk-old mice. These findings were pronounced in mice exposed to hyperoxia cycling with IH. At 3 mo follow-up, mice exposed to neonatal IH had persistently increased lung mitDNA lesions and impaired lung angiogenesis, even without concomitant hyperoxia exposure. Neonatal IH induces lung endothelial cell mitDNA damage and causes persistent impairment in lung angiogenesis. These findings provide important mechanistic insight into the pathogenesis of pulmonary vascular disease in preterm survivors.NEW & NOTEWORTHY Our current study demonstrates that neonatal intermittent hypoxia (IH) alters lung endothelial cell function, induces mitochondrial DNA lesions, and impairs lung vascular growth into adulthood. Moreover, when superimposed on hyperoxia, neonatal IH induces a severe lung vascular phenotype that is seen in preterm infants with PH. These findings suggest that neonatal IH contributes to PH in adults born preterm and importantly, that mitochondrial protection strategies may mitigate these deleterious effects.

Educational Review: The Impact of Perinatal Oxidative Stress on the Developing Kidney.

Oxidative stress occurs when there is an imbalance between reactive oxygen species/reactive nitrogen species and antioxidant systems. The interplay between these complex processes is crucial for normal pregnancy and fetal development; however, when oxidative stress predominates, pregnancy related complications and adverse fetal programming such as preterm birth ensues. Understanding how oxidative stress negatively impacts outcomes for the maternal-fetal dyad has allowed for the exploration of antioxidant therapies to prevent and/or mitigate disease progression. In the developing kidney, the negative impact of oxidative stress has also been noted as it relates to the development of hypertension and kidney injury mostly in animal models. Clinical research addressing the implications of oxidative stress in the developing kidney is less developed than that of the neurodevelopmental and respiratory conditions of preterm infants and other vulnerable neonatal groups. Efforts to study the oxidative stress pathway along the continuum of the perinatal period using a team science approach can help to understand the multi-organ dysfunction that the maternal-fetal dyad sustains and guide the investigation of antioxidant therapies to ameliorate the global toxicity. This educational review will provide a comprehensive and multidisciplinary perspective on the impact of oxidative stress during the perinatal period in the development of maternal and fetal/neonatal complications, and implications on developmental programming of accelerated aging and cardiovascular and renal disease for a lifetime.

Mesenchymal Stem Cell-derived Extracellular Vesicles Prevent Experimental Bronchopulmonary Dysplasia Complicated By Pulmonary Hypertension.

Mesenchymal stem cell (MSC) extracellular vesicles (EVs) have beneficial effects in preclinical bronchopulmonary dysplasia and pulmonary hypertension (BPD-PH) models. The optimal source, dosing, route, and duration of effects are however unknown. The objectives of this study were to (a) compare the efficacy of GMP-grade EVs obtained from Wharton's Jelly MSCs (WJ-MSCs) and bone marrow (BM-MSCs), (b) determine the optimal dosing and route of administration, (c) evaluate its long-term effects, and (d) determine how MSC EVs alter the lung transcriptome. Newborn rats exposed to normoxia or hyperoxia (85% O2) from postnatal day (P)1-P14 were given (a) intra-tracheal (IT) BM or WJ-MSC EVs or placebo, (b) varying doses of IT WJ-MSC EVs, or (c) IT or intravenous (IV) WJ-MSC EVs on P3. Rats were evaluated at P14 or 3 months. Early administration of IT BM-MSC or WJ-MSC EVs had similar beneficial effects on lung structure and PH in hyperoxia-exposed rats. WJ-MSC EVs however had superior effects on cardiac remodeling. Low, medium, and high dose WJ-MSC EVs had similar cardiopulmonary regenerative effects. IT and IV WJ-MSC EVs similarly improved vascular density and reduced PH in hyperoxic rats. Gene-set enrichment analysis of transcripts differentially expressed in WJ-MSC EV-treated rats showed that induced transcripts were associated with angiogenesis. Long-term studies demonstrated that a single early MSC EV dose has pulmonary vascular protective effects 3 months after administration. Together, our findings have significant translational implications as it provides critical insight into the optimal source, dosing, route, mechanisms of action, and duration of effects of MSC-EVs for BPD-PH.

Systemic delivery of large-scale manufactured Wharton's Jelly mesenchymal stem cell-derived extracellular vesicles improves cardiac function after myocardial infarction.

INTRODUCTION: Cardiovascular disease and myocardial infarction are leading causes of morbidity and mortality in aged populations. Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) are under evaluation as a therapeutic option for the treatment of myocardial infarction. AIM: This study aimed to develop a large-scale manufacturing procedure to harvest clinical-grade EVs required for the translation of EVs to the clinic. METHODS AND RESULTS: We compared the efficiency of large scale MSC-derived EV production and characterized EV miRNA cargo using the Quantum bioreactor with either fetal bovine serum or human platelet lysate (PLT)-containing expansion media. We tested the potency of the EV products in a murine model of acute myocardial infarction. Our results demonstrate an advantage of the Quantum bioreactor as a large-scale platform for EV production using PLT media; however, both media produced EVs with similar effects in vivo. The systemic delivery of EV products improved cardiac function following myocardial infarctions as indicated by a significant improvement in ejection fraction as well as parameters of cardiac performance, afterload, contractility and lusitropy. CONCLUSION: These findings have important implications for scale-up strategies of EVs and will facilitate clinical trials for their clinical evaluation.

S-Nitrosoglutathione Reductase Deficiency Causes Aberrant Placental S-Nitrosylation and Preeclampsia.

Background Preeclampsia, a leading cause of maternal and fetal mortality and morbidity, is characterized by an increase in S-nitrosylated proteins and reactive oxygen species, suggesting a pathophysiologic role for dysregulation in nitrosylation and nitrosative stress. Methods and Results Here, we show that mice lacking S-nitrosoglutathione reductase (GSNOR-/-), a denitrosylase regulating protein S-nitrosylation, exhibit a preeclampsia phenotype, including hypertension, proteinuria, renal pathology, cardiac concentric hypertrophy, decreased placental vascularization, and fetal growth retardation. Reactive oxygen species, NO, and peroxynitrite levels are elevated. Importantly, mass spectrometry reveals elevated placental S-nitrosylated amino acid residues in GSNOR-/- mice. Ascorbate reverses the phenotype except for fetal weight, reduces the difference in the S-nitrosoproteome, and identifies a unique set of S-nitrosylated proteins in GSNOR-/- mice. Importantly, human preeclamptic placentas exhibit decreased GSNOR activity and increased nitrosative stress. Conclusions Therefore, deficiency of GSNOR creates dysregulation of placental S-nitrosylation and preeclampsia in mice, which can be rescued by ascorbate. Coupled with similar findings in human placentas, these findings offer valuable insights and therapeutic implications for preeclampsia.

Short-acting testosterone appears to have lesser effect on male reproductive potential compared to long-acting testosterone in mice.

OBJECTIVE: To compare the effect of exogenous short-acting and long-acting testosterone on male reproductive potential in mice. DESIGN: In vivo mouse model. SETTING: University-based basic science research laboratory. ANIMALS: A total of 30 wild-type C57BL/6 male and female mice were used for this experimentation. The male mice were used for control group and testosterone supplementation, while both male and female mice were used for the breeding portion of the study. INTERVENTIONS: Exogenous testosterone was administered either in short-acting formulation (Monday-Wednesday-Friday dosing schedule, testosterone propionate 0.2 mg/kg), or long-acting formulation (3-month dosing schedule - testosterone pellets 150 mg) to male mice. MAIN OUTCOME MEASURES: Time to pregnancy, Luteinizing hormone (LH) levels, and testicular weight. RESULTS: Mice treated with long-acting testosterone appear to have longer time to pregnancy when compared to wild-type (33 ± 11 vs 23 ± 2.6 days, p ≤ 0.05) and mice that received short-acting testosterone propionate (26 ± 5.9 days). Mice treated with long-acting testosterone had smaller testes weight when compared to control (0.08 ± 0.01 vs 0.11 ± 0.01g; p ≤ 0.01), while the short-acting testosterone treated mice had similar testis weight when compared to control (0.09 ± 0.02 vs 0.11 ± 0.01g; ns). The serum testosterone level was elevated in mice that received testosterone pellets (285.78 ng/dL) and testosterone propionate (122.16 ng/dL) versus control (68.4 ng/dL). In mice that received long-acting testosterone pellets, LH levels at 3 months were almost undetectable while those that received short-acting testosterone remained similar to control (0.017 ± 0.058 vs 0.348 ± 0.232 IU/L; p ≤ 0.01). Female reproductive potential parameters including litter size and pup weight were collected and observed to have no difference between groups. CONCLUSION: Through a mouse breeding study, mice that received short-acting testosterone were shown to have fertility potential similar to wild-type male mice. Long-acting exogenous testosterone appeared to impair male reproductive capacity and LH levels when compared to short-acting testosterone. Short-acting testosterone appeared to cause less LH suppression. Identifying strategies to increase testosterone while simultaneously preserving male fertility is important for treating young men with hypogonadism.

Soluble Klotho, a biomarker and therapeutic strategy to reduce bronchopulmonary dysplasia and pulmonary hypertension in preterm infants.

Preterm infants with bronchopulmonary dysplasia (BPD) and pulmonary hypertension (PH) have accelerated lung aging and poor long-term outcomes. Klotho is an antiaging protein that modulates oxidative stress, angiogenesis and fibrosis. Here we test the hypothesis that decreased cord Klotho levels in preterm infants predict increased BPD-PH risk and early Klotho supplementation prevents BPD-like phenotype and PH in rodents exposed to neonatal hyperoxia. In experiment 1, Klotho levels were measured in cord blood of preterm infants who were enrolled in a longitudinal cohort study. In experiment 2, using an experimental BPD-PH model, rat pups exposed to room air or hyperoxia (85% O2) were randomly assigned to receive every other day injections of recombinant Klotho or placebo. The effect of Klotho on lung structure, PH and cardiac function was assessed. As compared to controls, preterm infants with BPD or BPD-PH had decreased cord Klotho levels. Early Klotho supplementation in neonatal hyperoxia-exposed rodents preserved lung alveolar and vascular structure, attenuated PH, reduced pulmonary vascular remodeling and improved cardiac function. Together, these findings have important implications as they suggest that perinatal Klotho deficiency contributes to BPD-PH risk and strategies that preserve Klotho levels, may improve long-term cardiopulmonary outcomes in preterm infants.

Effects of Klotho supplementation on hyperoxia-induced renal injury in a rodent model of postnatal nephrogenesis.

BACKGROUND: Hyperoxia (HO) causes kidney injury in preterm infants; however, whether these effects are modifiable is unknown. We hypothesized that administration of exogenous soluble Klotho, a kidney-derived antioxidant, would attenuate HO-induced kidney injury during postnatal nephrogenesis in rats. METHODS: Sprague Dawley neonatal rats assigned to normoxia (21% O2) or HO (85% O2) groups from postnatal day (P) 1 to 21 were randomly assigned to receive alternate day intraperitoneal injections of recombinant Klotho or placebo for 3 weeks. They were recovered in normoxia for an additional 3 weeks and sacrificed at 6 weeks. Renal artery resistance and pulsatility indices, tubular injury scores, glomerular area, and renal antioxidant capacity were assessed. RESULTS: Rodents exposed to HO during postnatal nephrogenesis had reduced kidney Klotho expression, glomerulomegaly, and higher tubular injury scores. Exogenous Klotho administration improved renal perfusion as indicated by decreases in both resistance and pulsatility indices and increased antioxidant enzyme expression. CONCLUSIONS: HO exposure during postnatal nephrogenesis in rodents results in a decline in kidney Klotho expression, decreased renal perfusion, enlarged glomerular size, and tubular injury. The exogenous administration of Klotho attenuated HO-induced kidney injury and augmented antioxidant capacity.

Neonatal hyperoxia exposure induces aortic biomechanical alterations and cardiac dysfunction in juvenile rats.

Supplemental oxygen (O2 ) therapy in preterm infants impairs lung development, but the impact of O2 on long-term systemic vascular structure and function has not been well-explored. The present study tested the hypothesis that neonatal O2 therapy induces long-term structural and functional alterations in the systemic vasculature, resulting in vascular stiffness observed in children and young adults born preterm. Newborn Sprague-Dawley rats were exposed to normoxia (21% O2 ) or hyperoxia (85% O2 ) for 1 and 3 weeks. A subgroup exposed to 3 weeks hyperoxia was recovered in normoxia for an additional 3 weeks. Aortic stiffness was assessed by pulse wave velocity (PWV) using Doppler ultrasound and pressure myography. Aorta remodeling was assessed by collagen deposition and expression. Left ventricular (LV) function was assessed by echocardiography. We found that neonatal hyperoxia exposure increased vascular stiffness at 3 weeks, which persisted after normoxic recovery at 6 weeks of age. These findings were accompanied by increased PWV, aortic remodeling, and altered LV function as evidenced by decreased ejection fraction, cardiac output, and stroke volume. Importantly, these functional changes were associated with increased collagen deposition in the aorta. Together, these findings demonstrate that neonatal hyperoxia induces early and sustained biomechanical alterations in the systemic vasculature and impairs LV function. Early identification of preterm infants who are at risk of developing systemic vascular dysfunction will be crucial in developing targeted prevention strategies that may improve the long-term cardiovascular outcomes in this vulnerable population.

Age Induced Nitroso-Redox Imbalance Leads to Subclinical Hypogonadism in Male Mice.

Objective: The cause of age-related changes in testosterone remains unclear. We hypothesized that increased nitroso-redox imbalance with aging could affect testosterone production. Materials and Methods: We measured several markers of nitroso-redox imbalance (4-HNE, 3-NT, and NT) in serum of S-nitrosoglutathione reductase knock out (GSNOR KO) mice that have increased nitroso-redox imbalance and compared these to wild-type (WT) mice. We evaluated the impact of age-induced nitroso-redox imbalance on serum luteinizing hormone (LH) and testosterone (T) in WT young (<2 months), middle-aged (2-6 months), and aged (>12 months) mice. Finally, to elucidate the susceptibility of testes to nitroso-redox imbalance, we measured 4-HNE protein levels in the testes of WT and KO mice. Results: We identified 4-HNE as a reliable marker of nitroso-redox imbalance, as evidenced by increased protein levels in serum of GSNOR KO mice compared with WT mice. We demonstrated that 4-HNE serum protein levels increase in WT mice with age but do not accumulate in the testes. We also found that T levels were similar in all age groups. Interestingly, we found that serum LH levels in aged and middle-aged mice were increased when compared to young mice (n = 5) consistent with the phenotype of subclinical hypogonadism. Conclusions: Increased serum 4-HNE and LH levels without changes in T with age suggest that nitroso-redox imbalance is associated with subclinical hypogonadism in aged mice. Recognizing the relationship and etiology of a currently poorly understood classification of hypogonadism could be a paradigm shift in how age-related testosterone change is diagnosed and treated.

Effect of nitroso-redox imbalance on male reproduction.

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are byproducts of normal metabolic processes. They are necessary for normal cellular function and are kept in balance by antioxidant mechanisms. Alterations in levels of ROS and RNS can lead to nitroso-redox imbalance that in turn can negatively affect male reproduction. Strategies to decrease ROS/RNS involve evasion of exposures (smoking, meat intake, pollution, calorie-dense diet), managing lifestyle, and increasing the consumption of antioxidants (vitamin C, vitamin E, alpha-lipoic acid, taurine, quercetin). Targeted therapies focusing on nitroso-redox imbalance can be critical for treatment of male reproductive dysfunction. This review outlines endogenous and exogenous sources of ROS/RNS, adverse effect on male reproduction, and strategies to control nitroso-redox imbalance.

Alterations of tumor microenvironment by nitric oxide impedes castration-resistant prostate cancer growth.

Immune targeted therapy of nitric oxide (NO) synthases are being considered as a potential frontline therapeutic to treat patients diagnosed with locally advanced and metastatic prostate cancer. However, the role of NO in castration-resistant prostate cancer (CRPC) is controversial because NO can increase in nitrosative stress while simultaneously possessing antiinflammatory properties. Accordingly, we tested the hypothesis that increased NO will lead to tumor suppression of CRPC through tumor microenvironment. S-nitrosoglutathione (GSNO), an NO donor, decreased the tumor burden in murine model of CRPC by targeting tumors in a cell nonautonomous manner. GSNO inhibited both the abundance of antiinflammatory (M2) macrophages and expression of pERK, indicating that tumor-associated macrophages activity is influenced by NO. Additionally, GSNO decreased IL-34, indicating suppression of tumor-associated macrophage differentiation. Cytokine profiling of CRPC tumor grafts exposed to GSNO revealed a significant decrease in expression of G-CSF and M-CSF compared with grafts not exposed to GSNO. We verified the durability of NO on CRPC tumor suppression by using secondary xenograft murine models. This study validates the significance of NO on inhibition of CRPC tumors through tumor microenvironment (TME). These findings may facilitate the development of previously unidentified NO-based therapy for CRPC.