Effects of early postnatal hypernutrition on nephron number and long-term renal function and structure in rats

Early postnatal nutrition and renal consequences in preterm infants

Perinatal nutritional factors may lead to decreased nephron endowment, decreased kidney function, and long-term development of chronic kidney disease and non-communicable diseases. At the same time, optimal postnatal nutrition and catch-up growth are associated with better neurodevelopmental outcomes in preterm infants. Therefore, nutritional management of preterm infants is a major challenge for neonatologists. In this context, the Section of Nutrition, Gastroenterology and Metabolism reviewed the current knowledge on nutritional issues related to kidney function. This narrative review discusses the clinical impact of early postnatal nutrition on long-term kidney function. In preterm infants, data are largely lacking to determine the extent to which early nutrition contributes to nephrogenesis and nephron endowment. However, some nutritional principles may help clinicians better protect the developing kidney in preterm infants. IMPACT: Clinical data show that preterm infants are an emerging population at high risk for chronic kidney disease. Both undernutrition and overnutrition can alter long-term kidney function. In preterm infants, data are largely lacking to determine the extent to which early postnatal nutrition contributes to nephrogenesis, nephron endowment and increased risk for chronic kidney disease. Some nutritional principles may help clinicians better protect the developing kidney in preterm infants: avoiding extrauterine growth restriction; providing adequate protein and caloric intakes; limiting exposure to high and prolonged hyperglycaemia; avoiding micronutrient deficiencies and maintaining acid-base and electrolyte balance.

High Amino Acid Intake in Early Life Is Associated With Systolic but Not Diastolic Arterial Hypertension at 5 Years of Age in Children Born Very Preterm

BACKGROUND

The life course of individuals born very premature is a topic of increasing concern. The association between high early amino acid intake and later high blood pressure (HBP) in preterm neonates is debated.

METHODS AND RESULTS

In a national, prospective, population-based birth cohort, EPIPAGE-2 (Etude Epidémiologique sur Petits Ages Gestationnels), we assessed blood pressure at 5 years. Eligible infants were those born between 24 and 29 weeks of gestation. Infants were distributed in 2 groups of 717 infants matched on propensity score on whether or not they were exposed to high amino acid intake (>3.5 g/kg per day at day 7); 455 control term infants were also enrolled. A value ≥95th percentile of reference values for age and height defined systolic or diastolic HBP. Blood pressure at 5 years of age was assessed for 389 and 385 children in the exposed and nonexposed groups, respectively. Rates (in percent) of systolic and diastolic HBP were 18.0% (95% CI, 14.5%-22.2%), 13.3% (95% CI, 10.3%-17.0%), 8.5% (95% CI, 6.5%-11.1%), and 9.0% (95% CI, 6.6%-12.3%), 10.2% (95% CI, 7.5%-13.6%), and 5.4% (95% CI, 3.8%-7.6%) in exposed, nonexposed, and term-born groups, respectively. Exposure to high early amino acid intake and maximal serum creatinine (by 50 μmol/L) between day 3 and day 7 were 2 independent risk factors for systolic HBP (adjusted odds ratio [aOR], 1.60 [95% CI, 1.05-2.43] and aOR, 1.59 [95% CI, 1.12-2.26], respectively) but not for diastolic HBP (aOR, 0.84 [95% CI, 0.50-1.39] and aOR, 1.09 [95% CI, 0.71-1.67], respectively). After adjustment for 5-year weight Z score, the aOR between high early amino acid intake and systolic HBP was 1.50 [95% CI, 0.98-2.30].

CONCLUSIONS

These results suggest that mechanisms of childhood systolic HBP involve neonatal renal challenge by high amino acid intake or dysfunction.

Comparison of renal growth in breast fed and artificial fed infants: a cross-sectional study

INTRODUCTION

Renal growth in infancy determines renal function in adulthood and can easily be assessed via infant renal volume. Renal growth is influenced by many endogenous and exogenous factors among which nutrition is of prime importance. Worldwide, infants get their nutrition either from breast milk or formula, both of which have controversial roles in kidney growth and development.

METHODS

A cross-sectional study was done on healthy infants in the Pediatric Nephrology Department of Mayo Hospital, Lahore. These infants were either breastfed or artificially fed and their kidney volumes were noted to determine any significant difference in kidney size. Both informed and written consent was taken before data collection and the data was analyzed using SPSS version 26.

RESULTS

Out of 80 infants included in our study, 55% were male and 45% were female. The mean age was 8.9 months and the mean weight was 7.6 kg. The mean total kidney volume was 45.38 cm³ and the mean relative kidney volume was 6.12 cm³/kg. No statistical difference in relative renal volume was found between breastfed and artificially fed infants.

CONCLUSION

The present study aimed to compare the renal volume and thus renal growth in breastfed versus formula-fed infants. No statistical significance was found in relative renal volume between breastfed and artificially fed infants.

Antenatal Programming of Hypertension: Paradigms, Paradoxes, and How We Move Forward

PURPOSE OF REVIEW

Synthesize the clinical, epidemiological, and preclinical evidence for antenatal programming of hypertension and critically appraise paradigms and paradoxes to improve translation.

RECENT FINDINGS

Clinical and epidemiological studies persistently demonstrate that antenatal factors contribute to programmed hypertension under the developmental origins of health and disease framework, including lower birth weight, preterm birth, and fetal growth restriction. Preclinical mechanisms include preeclampsia, maternal diabetes, maternal undernutrition, and antenatal corticosteroid exposure. However, clinical and epidemiological studies to date have largely failed to adequately identify, discuss, and mitigate many sources and types of bias in part due to heterogeneous study designs and incomplete adherence to scientific rigor. These limitations have led to incomplete and biased paradigms as well as persistent paradoxes that have significantly limited translation into clinical and population health interventions. Improved understanding of these paradigms and paradoxes will allow us to substantially move the field forward.

Regulation of nephron progenitor cell lifespan and nephron endowment

Low nephron number - resulting, for example, from prematurity or developmental anomalies - is a risk factor for the development of hypertension, chronic kidney disease and kidney failure. Considerable interest therefore exists in the mechanisms that regulate nephron endowment and contribute to the premature cessation of nephrogenesis following preterm birth. The cessation of nephrogenesis in utero or shortly after birth is synchronized across multiple niches in all mammals, and is coupled with the exhaustion of nephron progenitor cells. Consequently, no nephrons are formed after the cessation of developmental nephrogenesis, and lifelong renal function therefore depends on the complement of nephrons generated during gestation. In humans, a tenfold variation in nephron endowment between individuals contributes to differences in susceptibility to kidney disease; however, the mechanisms underlying this variation are not yet clear. Salient advances in our understanding of environmental inputs, and of intrinsic molecular mechanisms that contribute to the regulation of cessation timing or nephron progenitor cell exhaustion, have the potential to inform interventions to enhance nephron endowment and improve lifelong kidney health for susceptible individuals.

Translational insights into mechanisms and preventive strategies after renal injury in neonates

Adverse perinatal circumstances can cause acute kidney injury (AKI) and contribute to chronic kidney disease (CKD). Accumulating evidence indicate that a wide spectrum of perinatal conditions interferes with normal kidney development and ultimately leads to aberrant kidney structure and function later in life. The present review addresses the lack of mechanistic knowledge with regard to perinatal origins of CKD and provides a comprehensive overview of pre- and peri-natal insults, including genetic predisposition, suboptimal nutritional supply, obesity and maternal metabolic disorders as well as placental insufficiency leading to intrauterine growth restriction (IUGR), prematurity, infections, inflammatory processes, and the need for life-saving treatments (e.g. oxygen supplementation, mechanical ventilation, medications) in neonates. Finally, we discuss future preventive, therapeutic, and regenerative directions. In summary, this review highlights the perinatal vulnerability of the kidney and the early origins of increased susceptibility toward AKI and CKD during postnatal life. Promotion of kidney health and prevention of disease require the understanding of perinatal injury in order to optimize perinatal micro- and macro-environments and enable normal kidney development.

Can breastfeeding affect the rest of our life?

The breastfeeding period is one of the most important critical windows in our development, since milk, our first food after birth, contains several compounds, such as macronutrients, micronutrients, antibodies, growth factors and hormones that benefit human health. Indeed, nutritional, and environmental alterations during lactation, change the composition of breast milk and induce alterations in the child's development, such as obesity, leading to the metabolic dysfunctions, cardiovascular diseases and neurobehavioral disorders. This review is based on experimental animal models, most of them in rodents, and summarizes the impact of an adequate breast milk supply in view of the developmental origins of health and disease (DOHaD) concept, which has been proposed by researchers in the areas of epidemiology and basic science from around the world. Here, experimental advances in understanding the programming during breastfeeding were compiled with the purpose of generating knowledge about the genesis of chronic noncommunicable diseases and to guide the development of public policies to deal with and prevent the problems arising from this phenomenon. This review article is part of the special issue on "Cross talk between periphery and brain".

Developmental Origins of Kidney Disease: Why Oxidative Stress Matters?

The "developmental origins of health and disease" theory indicates that many adult-onset diseases can originate in the earliest stages of life. The developing kidney has emerged as being particularly vulnerable to adverse in utero conditions leading to morphological and functional changes, namely renal programming. Emerging evidence indicates oxidative stress, an imbalance between reactive oxygen/nitrogen species (ROS/RNS) and antioxidant systems, plays a pathogenetic role in the developmental programming of kidney disease. Conversely, perinatal use of antioxidants has been implemented to reverse programming processes and prevent adult-onset diseases. We have termed this reprogramming. The focus of this review is twofold: (1) To summarize the current knowledge on oxidative stress implicated in renal programming and kidney disease of developmental origins; and (2) to provide an overview of reprogramming effects of perinatal antioxidant therapy on renal programming and how this may prevent adult-onset kidney disease. Although early-life oxidative stress is implicated in mediating renal programming and adverse offspring renal outcomes, and animal models provide promising results to allow perinatal antioxidants applied as potential reprogramming interventions, it is still awaiting clinical translation. This presents exciting new challenges and areas for future research.

Renal Programming by Transient Postnatal Overfeeding: The Role of Senescence Pathways

Background

Early nutrition influences the risk of chronic kidney diseases (CKDs) development in adulthood. Mechanisms underlying the early programming of altered renal function remain incompletely understood. This study aims at characterizing the role of cell senescence pathways in early programming of CKD after transient postnatal overfeeding.

Materials and Methods

Reduced litters of 3 mice pups and standard litters of 9 mice pups were obtained to induce overfed animals during lactation and control animals, respectively. Animals were sacrificed at 24 days (weaning) or at 7 months of life (adulthood). Body weight, blood pressure, kidney weight, and glomerular count were assessed in both groups. Senescence pathways were investigated using β-Galactosidase staining and Western blotting of P16, P21, P53, P-Rb/Rb, and Sirtuin 1 (Sirt1) proteins.

Results

Early overfed animals had a higher body weight, a higher blood pressure at adulthood, and a higher glomerular number endowment compared to the control group. A higher β-Galactosidase activity, a significant increase in P53 protein expression (p = 0.0045) and a significant decrease in P-Rb/Rb ratio (p = 0.02), were observed at weaning in animals who underwent early postnatal overfeeding. Protein expression of Sirt1, a protective factor against accelerated stress-induced senescence, was significantly decreased (p = 0.03) at weaning in early overfed animals.

Conclusion

Early postnatal overfeeding by litter size reduction is associated with increased expression of factors involved in cellular senescence pathways, and decreased expression of Sirt 1 in the mouse kidney at weaning. These alterations may contribute to CKD programming after early postnatal overfeeding.

Early-Life Programming and Reprogramming of Adult Kidney Disease and Hypertension: The Interplay between Maternal Nutrition and Oxidative Stress

Kidney disease and hypertension both have attained the status of a global pandemic. Altered renal programming resulting in kidney disease and hypertension can begin in utero. Maternal suboptimal nutrition and oxidative stress have important implications in renal programming, while specific antioxidant nutrient supplementations may serve as reprogramming strategies to prevent kidney disease and hypertension of developmental origins. This review aims to summarize current knowledge on the interplay of maternal nutrition and oxidative stress in response to early-life insults and its impact on developmental programming of kidney disease and hypertension, covering two aspects. Firstly, we present the evidence from animal models supporting the implication of oxidative stress on adult kidney disease and hypertension programmed by suboptimal maternal nutrition. In the second part, we document data on specific antioxidant nutrients as reprogramming strategies to protect adult offspring against kidney disease and hypertension from developmental origins. Research into the prevention of kidney disease and hypertension that begin early in life will have profound implications for future health.

The Effect of Preterm Birth on Renal Development and Renal Health Outcome

Preterm birth is associated with adverse renal health outcomes including hypertension, chronic kidney disease, and an increased rate of progression to end-stage renal failure. This review explores the antenatal, perinatal, and postnatal factors that affect the functional nephron mass of an individual and contribute to long-term kidney outcome. Health-care professionals have opportunities to increase their awareness of the risks to kidney health in this population. Optimizing maternal health around the time of conception and during pregnancy, providing kidney-focused supportive care in the NICU during postnatal nephrogenesis, and avoiding accelerating nephron loss throughout life may all contribute to improved long-term outcomes. There is a need for ongoing research into the long-term kidney outcomes of preterm survivors in mid-to-late adulthood as well as a need for further research into interventions that may improve ex utero nephrogenesis.

Resilience to acute kidney injury in offspring of maternal protein restriction

Protein restriction (PR) during pregnancy induces morphofunctional alterations related to deficient nephrogenesis. We studied the renal functional and morphological significance of PR during pregnancy and/or lactation in adult male rat offspring and the repercussions on acute kidney injury (AKI) severity. Female rats were randomly assigned to the following groups: control diet during pregnancy and lactation (CC), control diet during pregnancy and PR diet during lactation (CR), PR during pregnancy and control diet during lactation (RC), and PR during pregnancy and lactation (RR). Three months after birth, at least 12 male offspring of each group randomly underwent either bilateral renal ischemia for 45 min [ischemia-reperfusion (IR)] or sham surgery. Thus, eight groups were studied 24 h after reperfusion: CC, CC + IR, CR, CR + IR, RC, RC + IR, RR, and RR + IR. Under basal conditions, the CR, RC, and RR groups exhibited a significant reduction in nephron number that was associated with a reduction in renal blood flow. Glomerular hyperfiltration was present as a compensatory mechanism to maintain normal renal function. mRNA levels of several vasoactive, antioxidant, and anti-inflammatory molecules were decreased. After IR, renal function was similarly reduced in all of the studied groups. Although all of the offspring from maternal PR exhibited renal injury, the magnitude was lower in the RC and RR groups, which were associated with faster renal blood flow recovery, differential vasoactive factors, and hypoxia-inducible factor-1α signaling. Our results show that the offspring from maternal PR are resilient to AKI induced by IR that was associated with reduced tubular injury and a differential hemodynamic response.

Developmental milestones in neonatal and juvenile C57Bl/6 mouse - Indications for the design of juvenile toxicity studies

There is a growing demand for wild type mice and mouse models of disease that may be more representative of human conditions but there is little information on neonatal and juvenile mouse anatomy. This project produces sound and comprehensive histology background data on the developing neonatal mouse at different time points from Day 0 until Day 28. The work describes optimal methods for tissue harvesting, fixation and processing from the neonatal and juvenile mice which can be used in routine toxicology studies. A review of the available literature revealed inconsistencies in the developmental milestones reported in the mouse. Although it is true that the sequence of events during the development is virtually the same in mice and rats, important developmental milestones in the mouse often happen earlier than in the rat, and these species should not be used interchangeably.

A maternal low-protein diet and neonatal overnutrition result in similar changes to glomerular morphology and renal cortical oxidative stress measures in male Wistar rats

There is a strong correlation between inadequate gestational and postpartum nutrition and the occurrence of cardiovascular diseases. The present study investigated the effects of a maternal low-protein diet and neonatal overfeeding on the oxidative balance and morphology of the renal cortex of male Wistar rats. Two independent protocols were used. First, pregnant Wistar rats received diets containing either 17% (normal protein) or 8% (low protein) casein throughout pregnancy and lactation. Second, the litter size was reduced by one-third on the third postnatal day to induce overnourishment in offspring. At 30 days, the oxidative balance and morphology of the renal cortex were analyzed. There was a small but significant increase in renal corpuscle area in the low protein (LP, 5%) and overnutrition (ON, 8%) groups. Glomerular tuft area also increased in LP (6%) and ON (9%), as did glomerular cellularity (LP, +11%; ON, +12%). In the oxidative stress analyses, both nutritional insults significantly elevated lipid peroxidation (LP, +18%; ON, +135%) and protein oxidation (LP, +40%; ON, +65%) while significantly reducing nonenzymatic antioxidant defenses, measured as reduced glutathione (LP, –32%; ON, –45%) and total thiol content (LP, –28%; ON, –24%). We also observed a decrease in superoxide dismutase (LP, –78%; ON, –51%), catalase (LP, –18%; ON, –61%), and glutathione S-transferase (only in ON, –44%) activities. Our results demonstrate that nutritional insults, even those of a very different nature, during perinatal development can result in similar changes in oxidative parameters and glomerular morphology in the renal cortex.

Postnatal nutritional intakes and hyperglycemia as determinants of blood pressure at 6.5 years of age in children born extremely preterm

BACKGROUND

Adverse developmental programming by early-life exposures might account for higher blood pressure (BP) in children born extremely preterm. We assessed associations between nutrition, growth and hyperglycemia early in infancy, and BP at 6.5 years of age in children born extremely preterm.

METHODS

Data regarding perinatal exposures including nutrition, growth and glycemia status were collected from the Extremely Preterm Infants in Sweden Study (EXPRESS), a population-based cohort including infants born <27 gestational weeks during 2004-2007. BP measurements were performed at 6.5 years of age in a sub-cohort of 171 children (35% of the surviving children).

RESULTS

Higher mean daily protein intake (+1 g/kg/day) during postnatal weeks 1-8 was associated with 0.40 (±0.18) SD higher diastolic BP. Higher mean daily carbohydrate intake (+1 g/kg/day) during the same period was associated with 0.18 (±0.05) and 0.14 (±0.04) SD higher systolic and diastolic BP, respectively. No associations were found between infant growth (weight, length) and later BP. Hyperglycemia and its duration during postnatal weeks 1-4 were associated primarily with higher diastolic BP z-scores.

CONCLUSIONS

These findings emphasize the importance of modifiable early-life exposures, such as nutrition and hyperglycemia, in determining long-term outcomes in children born extremely preterm.

Effect of early postnatal nutrition on chronic kidney disease and arterial hypertension in adulthood: a narrative review

Intrauterine growth restriction (IUGR) has been identified as a risk factor for adult chronic kidney disease (CKD), including hypertension (HTN). Accelerated postnatal catch-up growth superimposed to IUGR has been shown to further increase the risk of CKD and HTN. Although the impact of excessive postnatal growth without previous IUGR is less clear, excessive postnatal overfeeding in experimental animals shows a strong impact on the risk of CKD and HTN in adulthood. On the other hand, food restriction in the postnatal period seems to have a protective effect on CKD programming. All these effects are mediated at least partially by the activation of the renin-angiotensin system, leptin and neuropeptide Y (NPY) signaling and profibrotic pathways. Early nutrition, especially in the postnatal period has a significant impact on the risk of CKD and HTN at adulthood and should receive specific attention in the prevention of CKD and HTN.

Hamartin regulates cessation of mouse nephrogenesis independently of Mtor

Nephrogenesis concludes by the 36th week of gestation in humans and by the third day of postnatal life in mice. Extending the nephrogenic period may reduce the onset of adult renal and cardiovascular disease associated with low nephron numbers. We conditionally deleted either Mtor or Tsc1 (coding for hamartin, an inhibitor of Mtor) in renal progenitor cells. Loss of one Mtor allele caused a reduction in nephron numbers; complete deletion led to severe paucity of glomeruli in the kidney resulting in early death after birth. By contrast, loss of one Tsc1 allele from renal progenitors resulted in a 25% increase in nephron endowment with no adverse effects. Increased progenitor engraftment rates ex vivo relative to controls correlated with prolonged nephrogenesis through the fourth postnatal day. Complete loss of both Tsc1 alleles in renal progenitors led to a lethal tubular lesion. The hamartin phenotypes are not dependent on the inhibitory effect of TSC on the Mtor complex but are dependent on Raptor.

Role of renal sympathetic nerve activity in prenatal programming of hypertension

Prenatal insults, such as maternal dietary protein deprivation and uteroplacental insufficiency, lead to small for gestational age (SGA) neonates. Epidemiological studies from many different parts of the world have shown that SGA neonates are at increased risk for hypertension and early death from cardiovascular disease as adults. Animal models, including prenatal administration of dexamethasone, uterine artery ligation and maternal dietary protein restriction, result in SGA neonates with fewer nephrons than controls. These models are discussed in this educational review, which provides evidence that prenatal insults lead to altered sodium transport in multiple nephron segments. The factors that could result in increased sodium transport are discussed, focusing on new information that there is increased renal sympathetic nerve activity that may be responsible for augmented renal tubular sodium transport. Renal denervation abrogates the hypertension in programmed rats but has no effect on control rats. Other potential factors that could cause hypertension in programmed rats, such as the renin-angiotensin system, are also discussed.

Biochemical basis for pharmacological intervention as a reprogramming strategy against hypertension and kidney disease of developmental origin

The concept of "developmental origins of health and disease" (DOHaD) stipulates that both hypertension and kidney disease may take origin from early-life insults. The DOHaD concept also offers reprogramming strategies aiming at shifting therapeutic interventions from adulthood to early life, even before clinical symptoms are evident. Based on those two concepts, this review will present the evidence for the existence of, and the programming mechanisms in, kidney developmental programming that may lead to hypertension and kidney disease. This will be followed by potential pharmacological interventions that may serve as a reprogramming strategy to counter the rising epidemic of hypertension and kidney disease. We point out that before patients could benefit from this strategy, the most pressing issue is for the growing body of evidence from animal studies in support of pharmacological intervention as a reprogramming strategy to long-term protect against hypertension and kidney disease of developmental origins to be validated clinically and the critical window, drug dose, dosing regimen, and therapeutic duration identified.

Kidneys in 5-year-old preterm-born children: a longitudinal cohort monitoring of renal function

BackgroundBeing aware of the impact of low birth weight on late-onset hypertension, our aim was to describe systolic blood pressure (sBP) and renal function in 3-5-year-old preterm-born children and to determine which perinatal factors or childhood factors were associated with an altered renal function at 5 years in these children.MethodsThis was a prospective longitudinal cohort study of children born at 27-31 weeks of gestation and included at birth and examined at 3, 4, and 5 years of age. The primary outcome was renal function at 5 years: BP, estimated glomerular filtration rate, and albuminuria.ResultsOne hundred and sixty five children were examined, of whom 93 (56.4%) were male. Gestational age was 29.2±1.4 weeks and birth weight was 1,217±331 g. Overall, 25% children had sBP ≥90th percentile at age 3 and 4 years and 11% at 5 years. In multivariate analysis, sBP ≥90th percentile at 5 years was associated with the use of antenatal steroids (OR=0.19(0.05;0.65)). There was a significant association between protein intake on day 28 and sBP at 5 years (β=2.1±1.0, P=0.03). Glomerular filtration rate at 5 years was significantly decreased in case of hyaline membrane disease or necrotizing enterocolitis. High urine albumin was not predictable from one year to another.ConclusionIn preterm-born children, sBP was often high and neonatal protein intake was associated with increased blood pressure during childhood.

Postnatal overnutrition affects metabolic and vascular function reflected by physiological and histological changes in the aorta of adult Wistar rats

Rigorous nutritional care during early life leads to healthy adulthood. Cardiovascular and metabolic disorders, the most prevalent clinical challenges worldwide, are epidemiologically linked to poor nutritional habits throughout life. We aimed to understand whether postnatal overnutrition (PO) initiated during lactation affects metabolic markers and vascular function later in life. To test this hypothetical effect, we studied a PO Wistar rat model based on adjusting litter size at the third day of age to three pups and eight for the control group (C). Systemic parameters such as body weight and food intake were significantly increased in adult rats, measured up to 36 weeks. Moreover, fat mass, triglycerides, insulin and systolic blood pressure were all significantly increased in the PO group. Furthermore, we assessed whether these alterations would affect morphological and functional parameters in isolated vessels. Consistent with systemic alterations of the vasculature, contraction of thoracic aortic rings, determined by dose-response curves to norepinephrine (NE), was significantly reduced in PO rats. Histological stains revealed that the relative area of collagen was higher and the elastic fiber density was lower in the distal rings of PO rats. Altogether, our results highlight the critical importance of having a healthy neonatal nutrition to prevent harmful metabolic and vascular alterations during adulthood.

Effects of early overnutrition on the renal response to Ang II and expression of RAAS components in rat renal tissue

BACKGROUND AND AIMS

The aim of this study was to analyze the effects of early overnutrition (EON) on the expression of the renin angiotensin aldosterone system (RAAS) components in renal cortex, renal arteries and renal perivascular adipose tissue (PVAT), as well as the vascular response of renal arteries to Angiotensin II (Ang II).

METHODS AND RESULTS

On birth day litters were adjusted to twelve (L12-control) or three (L3-overfed) pups per mother. Half of the animals were sacrificed at weaning (21 days old) and the other half at 5 months of age. Ang II-induced vasoconstriction of renal artery segments increased in young overfed rats and decreased in adult overfed rats. EON decreased the gene expression of angiotensinogen (Agt), Ang II receptors AT1 and AT2 and eNOS in renal arteries of young rats, while it increased the mRNA levels of AT-2 and ET-1 in adult rats. In renal PVAT EON up-regulated the gene expression of COX-2 and TNF-α in young rats and the mRNA levels of renin receptor both in young and in adult rats. On the contrary, Ang II receptors mRNA levels were downregulated at both ages. Renal cortex of overfed rats showed increased gene expression of Agt in adult rats and of AT1 in young rats. However the mRNA levels of AT1 were decreased in the renal cortex of overfed adult rats.

CONCLUSION

EON is associated with alterations in the vascular response of renal arteries to Ang II and changes in the gene expression of RAAS components in renal tissue.

Endothelial dysfunction in individuals born after fetal growth restriction: cardiovascular and renal consequences and preventive approaches

Individuals born after intrauterine growth restriction (IUGR) have an increased risk of perinatal morbidity/mortality, and those who survive face long-term consequences such as cardiovascular-related diseases, including systemic hypertension, atherosclerosis, coronary heart disease and chronic kidney disease. In addition to the demonstrated long-term effects of decreased nephron endowment and hyperactivity of the hypothalamic-pituitary-adrenal axis, individuals born after IUGR also exhibit early alterations in vascular structure and function, which have been identified as key factors of the development of cardiovascular-related diseases. The endothelium plays a major role in maintaining vascular function and homeostasis. Therefore, it is not surprising that impaired endothelial function can lead to the long-term development of vascular-related diseases. Endothelial dysfunction, particularly impaired endothelium-dependent vasodilation and vascular remodeling, involves decreased nitric oxide (NO) bioavailability, impaired endothelial NO synthase functionality, increased oxidative stress, endothelial progenitor cells dysfunction and accelerated vascular senescence. Preventive approaches such as breastfeeding, supplementation with folate, vitamins, antioxidants, L-citrulline, L-arginine and treatment with NO modulators represent promising strategies for improving endothelial function, mitigating long-term outcomes and possibly preventing IUGR of vascular origin. Moreover, the identification of early biomarkers of endothelial dysfunction, especially epigenetic biomarkers, could allow early screening and follow-up of individuals at risk of developing cardiovascular and renal diseases, thus contributing to the development of preventive and therapeutic strategies to avert the long-term effects of endothelial dysfunction in infants born after IUGR.

The Impact of Kidney Development on the Life Course: A Consensus Document for Action

Hypertension and chronic kidney disease (CKD) have a significant impact on global morbidity and mortality. The Low Birth Weight and Nephron Number Working Group has prepared a consensus document aimed to address the relatively neglected issue for the developmental programming of hypertension and CKD. It emerged from a workshop held on April 2, 2016, including eminent internationally recognized experts in the field of obstetrics, neonatology, and nephrology. Through multidisciplinary engagement, the goal of the workshop was to highlight the association between fetal and childhood development and an increased risk of adult diseases, focusing on hypertension and CKD, and to suggest possible practical solutions for the future. The recommendations for action of the consensus workshop are the results of combined clinical experience, shared research expertise, and a review of the literature. They highlight the need to act early to prevent CKD and other related noncommunicable diseases later in life by reducing low birth weight, small for gestational age, prematurity, and low nephron numbers at birth through coordinated interventions. Meeting the current unmet needs would help to define the most cost-effective strategies and to optimize interventions to limit or interrupt the developmental programming cycle of CKD later in life, especially in the poorest part of the world.

Developmental Origins of Chronic Kidney Disease: Should We Focus on Early Life?

Chronic kidney disease (CKD) is becoming a global burden, despite recent advances in management. CKD can begin in early life by so-called "developmental programming" or "developmental origins of health and disease" (DOHaD). Early-life insults cause structural and functional changes in the developing kidney, which is called renal programming. Epidemiological and experimental evidence supports the proposition that early-life adverse events lead to renal programming and make subjects vulnerable to developing CKD and its comorbidities in later life. In addition to low nephron endowment, several mechanisms have been proposed for renal programming. The DOHaD concept opens a new window to offset the programming process in early life to prevent the development of adult kidney disease, namely reprogramming. Here, we review the key themes on the developmental origins of CKD. We have particularly focused on the following areas: evidence from human studies support fetal programming of kidney disease; insight from animal models of renal programming; hypothetical mechanisms of renal programming; alterations of renal transcriptome in response to early-life insults; and the application of reprogramming interventions to prevent the programming of kidney disease.

The magnitude of nephron number reduction mediates intrauterine growth-restriction-induced long term chronic renal disease in the rat. A comparative study in two experimental models

BACKGROUND

Intrauterine growth restriction (IUGR) is a risk factor for hypertension (HT) and chronic renal disease (CRD). A reduction in the nephron number is proposed to be the underlying mechanism; however, the mechanism is debated. The aim of this study was to demonstrate that IUGR-induced HT and CRD are linked to the magnitude of nephron number reduction, independently on its cause.

METHODS

Systolic blood pressure (SBP), glomerular filtration rate (GFR), proteinuria, nephron number, and glomerular sclerosis were compared between IUGR offspring prenatally exposed to a maternal low-protein diet (9% casein; LPD offspring) or maternal administration of betamethasone (from E17 to E19; BET offspring) and offspring with a normal birth weight (NBW offspring).

RESULTS

Both prenatal interventions led to IUGR and a similar reduction in birth weight. In comparison to NBW offspring, BET offspring had a severe nephron deficit (-50% in males and -40% in females, p < 0.01), an impaired GFR (-33%, p < 0.05), and HT (SBP+ 17 mmHg, p < 0.05). Glomerular sclerosis was more than twofold higher in BET offspring than in NBW offspring (p < 0.05). Long-term SBP, GFR, and glomerular sclerosis were unchanged in LPD offspring while the nephron number was moderately reduced only in males (-28% vs. NBW offspring, p < 0.05).

CONCLUSION

In this study, the magnitude of nephron number reduction influences long term renal disease in IUGR offspring: a moderate nephron number is an insufficient factor. Extremely long-term follow-up of adults prenatally exposed to glucocorticoids are required.

The conundrums of chronic kidney disease and aging

Chronic kidney disease (CKD), as presently defined, is a common disorder. Aging is a nearly universal phenomenon that can affect renal anatomy and function, but at variable rates in individuals. Loss of nephrons and a decline in glomerular filtration rate (GFR) is a characteristic of normal aging, called renal senescence. Using fixed and absolute thresholds for defining CKD on the basis of GFR for all ages may lead to diagnostic uncertainty (a conundrum) in both young and older subjects. This brief review will consider the physiological and anatomical changes of the kidney occurring in the process of normal renal senescence focusing on GFR and will examine the relevance of these observation for the diagnosis of CKD using GFR as the distinguishing parameter. Once a better understanding of the pathobiology underlying renal senescence is obtained, specific interventions may become available to slow the process.

Maternal Fat Feeding Augments Offspring Nephron Endowment in Mice

Increasing consumption of a high fat 'Western' diet has led to a growing number of pregnancies complicated by maternal obesity. Maternal overnutrition and obesity have health implications for offspring, yet little is known about their effects on offspring kidney development and renal function. Female C57Bl6 mice were fed a high fat diet (HFD, 21% fat) or matched normal fat diet (NFD, 6% fat) for 6 weeks prior to pregnancy and throughout gestation and lactation. HFD dams were overweight and glucose intolerant prior to mating but not in late gestation. Offspring of NFD and HFD dams had similar body weights at embryonic day (E)15.5, E18.5 and at postnatal day (PN)21. HFD offspring had normal ureteric tree development and nephron number at E15.5. However, using unbiased stereology, kidneys of HFD offspring were found to have 20-25% more nephrons than offspring of NFD dams at E18.5 and PN21. Offspring of HFD dams with body weight and glucose profiles similar to NFD dams prior to pregnancy also had an elevated nephron endowment. At 9 months of age, adult offspring of HFD dams displayed mild fasting hyperglycaemia but similar body weights to NFD offspring. Renal function and morphology, measured by transcutaneous clearance of FITC-sinistrin and stereology respectively, were normal. This study demonstrates that maternal fat feeding augments offspring nephron endowment with no long-term consequences for offspring renal health. Future studies assessing the effects of a chronic stressor on adult mice with augmented nephron number are warranted, as are studies investigating the molecular mechanisms that result in high nephron endowment.

Perinatal programming of renal function

PURPOSE OF REVIEW

Perinatal programming of renal function reflects the epigenetic alteration of genetically determined development by environmental factors. These include intrauterine malnutrition, pre and postnatal overnutrition, glucocorticoids, and certain toxins such as smoking. This review aims to summarize the most important findings.

RECENT FINDINGS

Human studies may show an increased susceptibility toward the general prevalence of renal failure in already small for gestational age children and adolescents. In particular, glomerular diseases present with a more severe clinical course. Partially related, partially independently, arterial hypertension is found in this at-risk group. The findings can mostly be confirmed in animal models. Both intrauterine nutrient deprived and overfed rodents show a tendency toward developing glomerulosclerosis and other renal disorders. Animal studies attempt to imitate clinical conditions, however, there are difficulties in transferring the findings to the human setting. The reduction of nephron number, especially in intrauterine growth-restricted humans and animals, is one mechanism of perinatal programming in the kidneys. In addition, vascular and endocrine alterations are prevalent. The molecular changes behind these mechanisms include epigenetic changes such as DNA-methylation, microRNAs, and histone modifications.

SUMMARY

Future research will have to establish clinical studies with clear and well defined inclusion criteria which also reflect prenatal life. The use of transgenic animal models might help to obtain a deeper insight into the underlying mechanisms.

High protein intake in neonatal period induces glomerular hypertrophy and sclerosis in adulthood in rats born with IUGR

BACKGROUND

Intrauterine growth restriction (IUGR) and postnatal nutrition are risk factors for cardiovascular and renal diseases in both humans and animals. The long-term renal effects of protein intake early in life remain unknown. The objective was to evaluate the effects of a neonatal feeding with high protein (HP) milk on renal functions and structure in IUGR male rats.

METHODS

Maternal gestational low protein diet was used to produce IUGR. At day 5, IUGR pups were gastrostomized in the "pup-in-the cup" model and received either normal protein (NP) milk or HP (+50% protein content) milk until day 21. After weaning, the animals were fed the same standard diet. Renal functions and structure were assessed at postnatal day 18 (D18) and in adult offspring.

RESULTS

During the preweaning period, the postnatal weight gain between the two groups was unaffected. On D18, kidneys from HP offspring were heavier with significant glomerular hypertrophy (+40%, P < 0.05). HP diet was associated with significant proteinuria and glomerulosclerosis (+49%, P < 0.05). Glomerular number was unaltered.

CONCLUSION

Neonatal HP feeding following IUGR affects renal functions and structure at adulthood. These alterations may result from a single nephron glomerular hyperfiltration.

First-trimester maternal protein intake and childhood kidney outcomes: the Generation R Study

BACKGROUND

Nutritional exposures during in utero development may have long-lasting consequences for postnatal renal health. Animal studies suggest that specifically maternal dietary protein intake during pregnancy influences childhood kidney function.

OBJECTIVE

We examined the associations of total, animal, and vegetable maternal protein intake during pregnancy with kidney volume and function in school-aged children.

DESIGN

This study was conducted in 3650 pregnant women and their children who were participating in a population-based cohort study from early life onward. First-trimester energy-adjusted maternal protein intake was assessed with a food-frequency questionnaire. At the child's age of 6 y, we assessed kidney volume, estimated glomerular filtration rate (eGFR) using serum creatinine and cystatin C concentrations, and microalbuminuria using urine albumin:creatinine ratios.

RESULTS

First-trimester maternal total protein intake was associated with a higher childhood creatinine-based eGFR (difference: 0.06 mL × min(-1) × 1.73 m(-2); 95% CI: 0.01, 0.12 mL · min(-1) · 1.73 m(-2) per gram of protein intake). This association was mainly driven by vegetable protein intake (0.22 mL × min(-1) × 1.73 m(-2); 95% CI: 0.10, 0.35 mL · min(-1) · 1.73 m(-2) per gram of vegetable protein intake). These associations were not explained by protein intake in early childhood. First-trimester maternal protein intake was not significantly associated with childhood kidney volume, cystatin C-based eGFR, or the risk of microalbuminuria.

CONCLUSIONS

Our findings suggest that higher total and vegetable, but not animal, maternal protein intake during the first trimester of pregnancy is associated with a higher eGFR in childhood. Further follow-up studies are needed to investigate whether maternal protein intake in early pregnancy also affects the risk of kidney diseases in later life.

Infant Breastfeeding and Kidney Function in School-Aged Children

BACKGROUND

Early life factors may influence kidney growth and function throughout the life course. We examined the associations of breastfeeding duration and exclusivity and age at introduction of solid foods with kidney outcomes at school age.

STUDY DESIGN

Prospective cohort study from fetal life onward.

SETTING & PARTICIPANTS

5,043 children in the Netherlands.

PREDICTORS

Infant feeding was assessed prospectively using questionnaires.

OUTCOMES & MEASUREMENTS

In children at a median age of 6.0 years, we measured kidney volume with ultrasound, estimated glomerular filtration rate (eGFR) from serum creatinine level, and microalbuminuria from urinary albumin and creatinine levels.

RESULTS

92% of all children were ever breastfed, of whom 27% were breastfed for more than 6 months and 21% were breastfed exclusively for at least 4 months. Compared with ever-breastfed children, never-breastfed children had smaller combined kidney volumes (-2.69 [95% CI, -4.83 to -0.56] cm(3)) and lower eGFRs (-2.42 [95% CI, -4.56 to -0.28] mL/min/1.73 m(2)) at school age. Among breastfed children, shorter duration of breastfeeding was associated with smaller combined kidney volume and lower microalbuminuria risk (P<0.05). Compared to exclusive breastfeeding for 4 months, nonexclusive breastfeeding in the first 4 months was associated with smaller combined kidney volume and lower eGFR (both P<0.05). Associations with eGFR were explained largely by kidney volume. Age at introduction of solid foods was not associated with any kidney outcome.

LIMITATIONS

Observational study, so causality cannot be established. Follow-up measurements were available for 76% of children.

CONCLUSIONS

These results suggest that breastfeeding is associated with subclinical changes in kidney outcomes in childhood. Further studies are needed to explore whether early life nutrition also affects the risk of kidney disease in adulthood.

Environmental origins of hypertension: phylogeny, ontogeny and epigenetics

Hypertension and renal parenchymal disease are intricately linked. Primary renal parenchymal disease can impact on sodium and volume regulation and lead to hypertension, while arterial hypertension can induce renal parenchymal injury and precipitate renal dysfunction. The examination for clues to the environmental origins of renal disease and hypertension necessitates an approach that integrates epidemiology, clinical medicine, developmental biology, environmental science and epigenetics, such that the manner in which genes and the environment interact can be better understood to pave the way for innovative management paradigms with regards to prevention, diagnosis and treatment. This review summarizes the extant literature and provides cogent arguments for the need to evaluate chronic adult onset disease models such as hypertension and renal disease from the modern perspective that takes into account prenatal exposures, the intrauterine environment and development, postnatal growth and transgenerational epigenetic modifications with their attendant future disease risk from the individual to the population level.

Effect of repeated fasting/refeeding on obesity development and health complications in rats arising from reduced nest

BACKGROUND

Overnutrition during postnatal life represents a risk factor for later obesity and associated metabolic disorders.

AIM

We investigated the interaction between postnatal and later-life nutrition on body composition, blood pressure and the jejunal enzyme activities in male Sprague-Dawley rats.

METHODS

From birth, we adjusted the number of pups in the nest to 4 (small litters-SL; overfeeding) or to 10 pups (normal litters-NL; controls), and from day 50 until 70, the SL (SL-R) and NL (NL-R) rats were subjected to 1 day fasting and 1 day refeeding cycles (RFR). Their body composition was determined by magnetic resonance imaging, and enzyme activity was assayed histochemically.

RESULTS

At 50 and 70 days, SL rats were found to be overweight (p < 0.001), with higher adiposity (p < 0.001) and blood pressure (p < 0.01). Moreover, despite significantly decreased daily food intake during RFR (SL-R 39 %, NL-R 23 %), higher fat deposition (p < 0.001) and blood pressure (p < 0.05) was detected in SL-R rats. Activity of alkaline phosphatase (AP) functionally involved in lipid absorption was significantly higher in SL than NL rats (p < 0.001) but substantially decreased in RFR groups (SL-R p < 0.001, NL-R p < 0.01). However, despite these enzymatic adaptations to reduced food intake, the SL-R rats displayed significantly higher AP activity in comparison with NL-R rats (p < 0.01) on day 70.

CONCLUSIONS

Our results demonstrate that postnatal overfeeding predisposes the ontogeny of intestinal function, which may promote the probability of obesity risk. Accordingly, in these animals, efficient fat deposition and elevated blood pressure were not diminished in response to dietary restrictions in later life.

Birth weight, malnutrition and kidney-associated outcomes--a global concern

An adverse intrauterine environment is associated with an increased risk of elevated blood pressure and kidney disease in later life. Many studies have focused on low birth weight, prematurity and growth restriction as surrogate markers of an adverse intrauterine environment; however, high birth weight, exposure to maternal diabetes and rapid growth during early childhood are also emerging as developmental risk factors for chronic diseases. Altered programming of nephron number is an important link between exposure to developmental stressors and subsequent risk of hypertension and kidney disease. Maternal, fetal, and childhood nutrition are crucial contributors to these programming effects. Resource-poor countries experience the sequential burdens of fetal and childhood undernutrition and subsequent overnutrition, which synergistically act to augment the effects of developmental programming; this observation might explain in part the disproportionate burden of chronic disease in these regions. Numerous nutritional interventions have been effective in reducing the short-term risk of low birth weight and prematurity. Understanding the potential long-term benefits of such interventions is crucial to inform policy decisions to interrupt the developmental programming cycle and stem the growing epidemics of hypertension and kidney disease worldwide.

Epigenetics and neonatal nutrition

Epigenetic changes have long-lasting effects on gene expression and are related to, and often induced by, the environment in which early development takes place. In particular, the period of development that extends from pre-conception to early infancy is the period of life during which epigenetic DNA imprinting activity is the most active. Epigenetic changes have been associated with modification of the risk for developing a wide range of adulthood, non-communicable diseases (including cardiovascular diseases, metabolic diseases, diseases of the reproductive system, etc.). This paper reviews the molecular basis of epigenetics, and addresses the issues related to the process of developmental programming of the various areas of human health.

Fetal and infant growth patterns and kidney function at school age

Low birth weight is associated with ESRD. To identify specific growth patterns in early life that may be related to kidney function in later life, we examined the associations of longitudinally measured fetal and infant growth with kidney function in school-aged children. This study was embedded in a population-based prospective cohort study among 6482 children followed from fetal life onward. Fetal and childhood growth was measured during second and third trimesters of pregnancy, at birth, and at 6, 12, 24, 36, and 48 months postnatally. At the age of 6 years, we measured kidney volume by ultrasound. GFR was estimated using blood creatinine levels. Higher gestational age-adjusted birth weight was associated with higher combined kidney volume and higher eGFR (per 1 SD score increase in birth weight; 1.27 cm(3) [95% confidence interval, 0.61 to 1.93] and 0.78 ml/min per 1.73 m2 [95% CI, 0.16 to 1.39], respectively). Fetal weight, birth weight, and weight at 6 months were positively associated with childhood kidney volume, whereas higher second trimester fetal weight was positively associated with higher GFR (all P values<0.05). Fetal and childhood lengths were not consistently associated with kidney function. In this cohort, lower fetal and early infant weight growth is associated with smaller kidney volume in childhood, whereas only lower fetal weight growth is associated with lower kidney function in childhood, independent of childhood growth. Whether these associations lead to an increased risk of kidney disease needs to be studied further.

Adverse prenatal environment and kidney development: implications for programing of adult disease

The 'developmental origins of health and disease' hypothesis suggests that many adult-onset diseases can be attributed to altered growth and development during early life. Perturbations during gestation can be detrimental and lead to an increased risk of developing renal, cardiovascular, metabolic, and neurocognitive dysfunction in adulthood. The kidney has emerged as being especially vulnerable to insult at almost any stage of development resulting in a reduction in nephron endowment. In both humans and animal models, a reduction in nephron endowment is strongly associated with an increased risk of hypertension. The focus of this review is twofold: i) to determine the importance of specific periods during development on long-term programing and ii) to examine the effects of maternal perturbations on the developing kidney and how this may program adult-onset disease. Recent evidence has suggested that insults occurring around the time of conception also have the capacity to influence long-term health. Although epigenetic mechanisms are implicated in mediating these outcomes, it is unclear as to how these may impact on kidney development. This presents exciting new challenges and areas for research.

Testosterone changes bladder and kidney structure in juvenile male rats

PURPOSE

Testosterone affects male development, maturation and aging but limited data exist on testosterone effects on the juvenile genitourinary system. We hypothesized that testosterone has bladder and kidney developmental effects, and investigated this in juvenile male rats.

MATERIALS AND METHODS

To examine the testosterone effect 21-day-old prepubertal male Wistar rats were divided into 3 groups of 12 each, including sham orchiectomy as controls, and bilateral orchiectomy with vehicle and bilateral orchiectomy with testosterone. Starting at age 28 days (week 0) testosterone enanthate (5 mg/100 gm) or vehicle was injected weekly. Testosterone was measured at study week 0 before injection, and at weeks 1, 6 and 16. Whole bladders and kidneys were evaluated for androgen receptor, bladder collagen-to-smooth muscle ratio, and renal morphometry and immunohistochemistry.

RESULTS

Testosterone was not detectable at week 0 in all groups. It remained undetectable at weeks 1, 6 and 16 in the orchiectomy plus vehicle group. Testosterone levels were physiological in controls and rats with orchiectomy plus testosterone but levels were higher in the latter than in the former group. Rats with orchiectomy plus testosterone had increased bladder-to-body and kidney-to-body weight ratios (p<0.01 and <0.05, respectively), and decreased collagen-to-smooth muscle ratio than the orchiectomy plus vehicle and control groups. Rats with orchiectomy plus testosterone had a lower renal total glomerular count (p<0.01) but increased androgen receptor density.

CONCLUSIONS

In juvenile male rats testosterone was associated with increased bladder and renal mass, and increased bladder smooth muscle. Testosterone associated kidneys also appeared to have fewer but larger glomeruli. These data support an important role for sex hormones in structural and functional development of the bladder and kidney.

Postnatal early overnutrition causes long-term renal decline in aging male rats

BACKGROUND

We evaluated the influence of postnatal early overnutrition on renal pathophysiological changes in aging rats.

METHODS

Three or 10 male pups per mother were assigned to either the small litter (SL) or normal litter (control) groups, respectively, during the first 21 d of life. The effects of early postnatal overnutrition were determined at 12 mo.

RESULTS

SL rats weighed more than controls between 4 d and 6 mo of age (P < 0.05). However, between 6 and 12 mo, body weights in both groups were not different. In the SL group, at 12 mo, systolic blood pressure was higher and creatinine clearance was lower than the same in controls (P < 0.05). Numbers of CD68 (ED1)-positive macrophages and apoptotic cells in renal cortex were higher in SL rats (P < 0.05). Furthermore, index scores for glomerulosclerosis and tubulointerstitial fibrosis were higher in the SL group (P < 0.05). Significantly less glomeruli per section area were found in aging SL rats (P < 0.05). Immunoblotting and immunohistochemistry showed decreased intrarenal renin expression in SL rats (P < 0.05).

CONCLUSION

Early postnatal overnutrition can potentiate structural and functional abnormalities in the aging kidney and can lead to systolic hypertension with reduced intrarenal renin activity.

Developmental origins of chronic renal disease: an integrative hypothesis

Cardiovascular diseases are one of the leading causes of mortality. Hypertension (HT) is one of the principal risk factors associated with death. Chronic kidney disease (CKD), which is probably underestimated, increases the risk and the severity of adverse cardiovascular events. It is now recognized that low birth weight is a risk factor for these diseases, and this relationship is amplified by a rapid catch-up growth or overfeeding during infancy or childhood. The pathophysiological and molecular mechanisms involved in the “early programming” of CKD are multiple and partially understood. It has been proposed that the developmental programming of arterial hypertension and chronic kidney disease is related to a reduced nephron endowment. However, this mechanism is still discussed. This review discusses the complex relationship between birth weight and nephron endowment and how early growth and nutrition influence long term HT and CKD. We hypothesize that fetal environment reduces moderately the nephron number which appears insufficient by itself to induce long term diseases. Reduced nephron number constitutes a “factor of vulnerability” when additional factors, in particular a rapid postnatal growth or overfeeding, promote the early onset of diseases through a complex combination of various pathophysiological pathways.

Effect of fetal and child health on kidney development and long-term risk of hypertension and kidney disease

Developmental programming of non-communicable diseases is now an established paradigm. With respect to hypertension and chronic kidney disease, adverse events experienced in utero can affect development of the fetal kidney and reduce final nephron number. Low birthweight and prematurity are the most consistent clinical surrogates for a low nephron number and are associated with increased risk of hypertension, proteinuria, and kidney disease in later life. Rapid weight gain in childhood or adolescence further compounds these risks. Low birthweight, prematurity, and rapid childhood weight gain should alert clinicians to an individual's lifelong risk of hypertension and kidney disease, prompting education to minimise additional risk factors and ensuring follow-up. Birthweight and prematurity are affected substantially by maternal nutrition and health during pregnancy. Optimisation of maternal health and early childhood nutrition could, therefore, attenuate this programming cycle and reduce the global burden of hypertension and kidney disease in the future.

Postnatal overfeeding in rodents by litter size reduction induces major short- and long-term pathophysiological consequences

Numerous studies have demonstrated that the early postnatal environment can influence body weight and energy homeostasis into adulthood. Rodents raised in small litters have been shown to be a useful experimental model to study the short- and long-term consequences of early overnutrition, which can lead to modifications not only in body weight but also of several metabolic features. Postnatal overfeeding (PNOF) induces early malprogramming of the hypothalamic system, inducing acquired persisting central leptin and insulin resistance and an increase in orexigenic signals. Visceral white adipose tissue, lipogenic activity, and inflammatory status are increased in PNOF rodents, while brown adipose tissue shows reduced thermogenic activity. Pancreatic and hepatic glucose responsiveness is persistently reduced in PNOF rodents, which also frequently present disturbances in plasma lipids. PNOF rodents present increased circulating concentrations of leptin, elevated corticosterone secretion, and significant changes in glucocorticoid sensitivity. PNOF also influences nephrogenesis and renal maturation. Increased oxidative stress is also described in circulating blood and in some tissues, such as the heart or liver. At the cardiovascular level, a moderate increase in arterial blood pressure is sometimes observed and rapid cardiac hypertrophy is observed at weaning; however, during maturation, impaired contractility and fibrosis are observed. Myocardial genome expression is rapidly modified in overfed mice. Moreover, hearts of PNOF rodents are more sensitive to ischemia-reperfusion injury. Together, these results suggest that the nutritional state in the immediate postnatal period should be taken into account, because it may have an impact on cardiometabolic risk in adulthood.

Overweight, hypertension and renal dysfunction in adulthood of neonatally overfed rats

Accelerated growth in early infancy has been associated with later cardiovascular and metabolic diseases. We investigated the influence of overnutrition during neonatal periods on the development of renal pathophysiological changes in adult offspring rats. Three or 10 male pups per mother were assigned to either the small litter (SL) or normal litter (NL) control groups during the first 21 days of life. The effects of early postnatal overnutrition on body weight, blood pressure and renal changes were determined at 3 and 6 months. Pups in the SL group weighed more than controls between 7 days and 6 months of age (P<.05). In the SL group, serum creatinine levels were higher at 3 and 6 months (P<.05), and at 6 months, blood pressure levels were higher than those of the controls (P<.05). The number of ED-1 positive macrophages in renal cortex and glomerulosclerosis index increased in the SL group at 3 and 6 months (P<.05). Additionally, cortical apoptotic cells increased in the SL group at 6 months (P<.05). Immunoblotting and immunohistochemistry showed that matrix metalloproteinase (MMP)-9 protein expressions decreased and tissue inhibitor of MMP-1, tumor necrosis factor-α, osteopontin and adiponectin expressions increased in the SL group at 3 months (P<.05). However, at 6 months, MMP-9 expression was elevated, and osteopontin expression remained elevated in the SL group (P<.05). Early postnatal overfeeding can lead to lasting overweight, hypertension and renal dysfunction and place a greater burden on the kidney.

Fetal hypoxia results in programming of aberrant angiotensin ii receptor expression patterns and kidney development

AIMS

The present study tested the hypothesis that fetal hypoxia adversely affects kidney development in fetal and offspring rats and alter the expression patterns of angiotensin II type 1 (AT1R) and type 2 (AT2R) receptors.

METHODS

Time-dated pregnant rats were divided between normoxic and hypoxic (10.5% O2 last period of gestation) groups. Protein expression, in the offspring, was determined using western blot.

RESULTS

Hypoxic treatment significantly decreased body and kidney weight in 21-day fetuses (E21) and 7-day neonates (P7). In 3-month-old offspring there were no significant differences in body and kidney weight between hypoxic and control animals. Fetal hypoxia had no effect on kidney AT1R density in E21 or P7, but significantly decreased kidney AT1R protein and mRNA abundance in both male and female adults. In contrast, kidney AT2R density was not affected by fetal hypoxia throughout the developmental stages studied. The hypoxia-mediated reduction of nephron numbers was progressively from P7 worsened into the adulthood with females affected more than males.

CONCLUSION

The results suggest that fetal hypoxia causes programming of aberrant kidney development and accelerates the aging process of the kidney during the postnatal development, which may contribute to an increased risk of cardiovascular disease.

Blood pressure follows the kidney: Perinatal influences on hereditary hypertension

Epidemiological and experimental data strongly suggest that cardiovascular diseases can originate from an aberrant environment during fetal development, a phenomenon referred to as perinatal programming. This review will focus on the role of the kidneys in determining blood pressure, and how (re)programming the renal development can persistently ameliorate hereditary hypertension. By combining physiologic and genomic studies we have discovered some candidate pathways suited for (re)programming the development of hypertension. This sets the stage for mechanistic analysis in future studies.