Does Extremely Low Birth Weight Predispose to Low-Renin Hypertension?

Update on Low-Renin Hypertension: Current Understanding and Future Direction

Low-renin hypertension is common and affects 1 in 4 people with hypertension. Understanding the different causes and management of low-renin hypertension is becoming increasingly relevant as renin measurements are more widely ordered in clinical practice. Importantly, many people with low-renin hypertension do not fit traditional definitions of known causes, and the approach to management of these people is not unclear. This review provides an overview of our evolving understanding of the causes of low-renin hypertension, the expanding spectrums of pathophysiology, key differentiating characteristics, distinct management strategies, and highlights our knowledge gaps. It is important to distinguish the underlying pathophysiology of an individual with low-renin hypertension to individualize treatment.

Cardiovascular Health Starts in the Womb

Hypertension has largely been viewed as a disorder of adulthood. Historically, blood pressure (BP) was not routinely measured in children because hypertension was considered uncommon in childhood. It was not until the 1970s that it was apparent that in childhood BP levels were normally lower compared with those in adults, were related to age and growth, and that abnormal BP in children needed different definitions. Based on the distribution of BP levels in available child cohorts, the 95th percentile of BP levels became the definition of hypertension in children and adolescents-an epidemiological definition. Subsequent clinical and epidemiological research identified associated risk factors in childhood that linked abnormal BP in youth with hypertension in adulthood. In the 1980s, the Barker hypothesis, based on observations that low birth weight could be linked to cardiovascular disease in adulthood, promoted further research spanning epidemiological, clinical, and basic science on the childhood origins of hypertension. This review focuses on recent findings from both longitudinal maternal-child cohorts and experimental models that examine both maternal and offspring conditions associated with risks of subsequent cardiovascular disease.

Serum neutrophil gelatinase-associated lipocalin and cystatin C is associated with blood pressure in ex-preterm children and adolescents

BACKGROUND

As preterm birth is a risk factor for hypertension (HTN), biomarkers for early prediction of HTN in childhood is an emerging need. The aims of the study were to evaluate serum biomarkers in ex-preterm children and examine for associations with office peripheral and central SBP (cSBP), ambulatory BP parameters and pulse wave velocity (PWV).

METHODS

This case-control study included children and adolescents born prematurely (ex-preterms) and at full term (controls). All participants underwent office and ambulatory BP monitoring, assessment of cSBP, PWV and serum biomarkers at the same visit. Neutrophil gelatinase-associated lipocalin (NGAL), matrix metalloproteinase-2, metalloproteinase-9 (MMP-2, MMP-9) and Cystatin C (CysC) were measured using ELISA.

RESULTS

The study population included 52 ex-preterm individuals and 26 controls. Mean age was 10.7 ± 3.6 years. NGAL, MMP-2, MMP-9, and CysC levels were similar between the ex-preterm and the control group. In the ex-preterm group, NGAL is associated with office SBP z score (β = 1.007, 95% CI 1.001-0.014, P = 0.049), CysC with office DBP z score (β = 1.003, 95% CI 1.001-0.005, P = 0.018) and cSBP z score (β = 1.003, 95% CI 1.001-0.005, P = 0.006) independently of age, sex and BMI z score. Among ex-preterm children and adolescents 17% had ambulatory HTN and 31% had white-coat HTN. NGAL levels were higher in ex-preterm children with WCH compared with children with normal BP [57.9 (IQR 50.8) versus 34.6 (IQR 46.2)], P = 0.018].

CONCLUSION

WCH is common in ex-preterm children and adolescents and is associated with higher NGAL levels and CysC presents positive association with cSBP. The findings in this study provides preliminary evidence that NGAL and CysC may have a role in predicting the risk of developing hypertension later in life. Further studies are warranted.

Perinatal risk factors of renal outcome in former extremely low birth weight neonates

Former Extremely Low Birthweight (ELBW) neonates suffer from adverse renal and cardiovascular outcomes later in life. Less is known about additional perinatal risk factors for these adverse outcomes which we have investigated in this study. We compared renal outcome between ELBW children and controls, to find perinatal risk factors for poorer renal outcome and to unveil associations between kidney function and blood pressure. This study included 93 former ELBW children and 87 healthy controls with a mean age of 11 years at assessment. We measured cystatin C-based estimated glomerular filtration rate (eGFR) and blood pressure. Blood pressure and eGFR levels were compared between cases and controls. We subsequently investigated perinatal risk factors for adverse outcome amongst ELBW children. ELBW children have significantly higher blood pressure (mean SBP percentile 75th vs. 47th, p <0.001) and lower mean eGFR (94 vs. 107 ml/min/1.73 m2, p = 0.005) compared to the control group. Elevated blood pressure did not correlate with perinatal characteristics and none of them had microalbuminuria. ELBW children with eGFR <90 ml/min/1.73 m2 were ventilated longer (17 vs. 9 days, p = 0.006), more frequently male (OR = 3.33, p = 0.055) and tended to suffer more from intraventricular hemorrhage (40% vs. 15.8%, p = 0.056). There was no association between blood pressure and kidney dysfunction.

CONCLUSIONS

Understanding risk profiles for unfavorable outcomes may help to identify children at increased risk for kidney dysfunction. Poorer eGFR was associated with longer ventilation, male sex, and intra-ventricular hemorrhage but not with blood pressure. This knowledge can lead to safer neonatal therapeutic regimens for ELBW infants, a more intensive follow-up and earlier treatment initiation for children at highest risk.

WHAT IS KNOWN

• Extremely Low Birthweight (ELBW) neonates suffer later in life from adverse renal and cardiovascular outcomes. • Perinatal risk factors that further predict the individual risk for adverse outcomes are not well known.

WHAT IS NEW

• Poorer eGFR in adolescence was associated with male sex, longer ventilation and intra-ventricular hemorrhage at birth but not with blood pressure. • Former ELBW infants had higher blood pressures compared to controls, but no microalbuminuria. • This knowledge can lead to potential precision medicine, safer neonatal therapeutic regimens for ELBW infants, a more intensive follow-up and earlier treatment initiation for children at highest risk.

Advocating for the inclusion of kidney health outcomes in neonatal research: best practice recommendations by the Neonatal Kidney Collaborative

Acute kidney injury (AKI) occurs in nearly 30% of sick neonates. Chronic kidney disease (CKD) can be detected in certain populations of sick neonates as early as 2 years. AKI is often part of a multisystem syndrome that negatively impacts developing organs resulting in short- and long-term pulmonary, neurodevelopmental, and cardiovascular morbidities. It is critical to incorporate kidney-related data into neonatal clinical trials in a uniform manner to better understand how neonatal AKI or CKD could affect an outcome of interest. Here, we provide expert opinion recommendations and rationales to support the inclusion of short- and long-term neonatal kidney outcomes using a tiered approach based on study design: (1) observational studies (prospective or retrospective) limited to data available within a center's standard practice, (2) observational studies involving prospective data collection where prespecified kidney outcomes are included in the design, (3) interventional studies with non-nephrotoxic agents, and (4) interventional studies with known nephrotoxic agents. We also provide recommendations for biospecimen collection to facilitate ancillary kidney specific research initiatives. This approach balances the costs of AKI and CKD ascertainment with knowledge gained. We advocate that kidney outcomes be included routinely in neonatal clinical study design. Consistent incorporation of kidney outcomes across studies will increase our knowledge of neonatal morbidity.

Pathophysiology of primary hypertension in children and adolescents

The progress in research on the physiology of the cardiovascular system made in the last 100 years allowed for the development of the pathogenesis not only of secondary forms of hypertension but also of primary hypertension. The main determinants of blood pressure are described by the relationship between stroke volume, heart rate, peripheral resistance, and arterial stiffness. The theories developed by Guyton and Folkow describe the importance of the volume factor and total peripheral resistance. However, none of them fully presents the pathogenesis of essential hypertension. The multifactorial model of primary hypertension pathogenesis developed by Irving Page in the 1940s, called Page's mosaic, covers most of the pathophysiological phenomena observed in essential hypertension. The most important pathophysiological phenomena included in Page's mosaic form a network of interconnected "nodes". New discoveries both from experimental and clinical studies made in recent decades have allowed the original Page mosaic to be modified and the addition of new pathophysiological nodes. Most of the clinical studies confirming the validity of the multifactorial pathogenesis of primary hypertension concern adults. However, hypertension develops in childhood and is even perinatally programmed. Therefore, the next nodes in Page's mosaic should be age and perinatal factors. This article presents data from pediatric clinical trials describing the most important pathophysiological processes associated with the development of essential hypertension in children and adolescents.

When will the Glomerular Filtration Rate in Former Preterm Neonates Catch up with Their Term Peers?

AIMS

Whether and when glomerular filtration rate (GFR) in preterms catches up with term peers is unknown. This study aims to develop a GFR maturation model for (pre)term-born individuals from birth to 18 years of age. Secondarily, the function is applied to data of different renally excreted drugs.

METHODS

We combined published inulin clearance values and serum creatinine (Scr) concentrations in (pre)term born individuals throughout childhood. Inulin clearance was assumed to be equal to GFR, and Scr to reflect creatinine synthesis rate/GFR. We developed a GFR function consisting of GFRbirth (GFR at birth), and an Emax model dependent on PNA (with GFRmax, PNA50 (PNA at which half ofGFR max is reached) and Hill coefficient). The final GFR model was applied to predict gentamicin, tobramycin and vancomycin concentrations.

RESULT

In the GFR model, GFRbirth varied with birthweight linearly while in the PNA-based Emax equation, GA was the best covariate for PNA50, and current weight for GFRmax. The final model showed that for a child born at 26 weeks GA, absolute GFR is 18%, 63%, 80%, 92% and 96% of the GFR of a child born at 40 weeks GA at 1 month, 6 months, 1 year, 3 years and 12 years, respectively. PopPK models with the GFR maturation equations predicted concentrations of renally cleared antibiotics across (pre)term-born neonates until 18 years well.

CONCLUSIONS

GFR of preterm individuals catches up with term peers at around three years of age, implying reduced dosages of renally cleared drugs should be considered below this age.

Impact of preterm birth on kidney health and development

Preterm birth, defined as birth before the gestational age of 37 weeks, affects 11% of the newborns worldwide. While extensive research has focused on the immediate complications associated with prematurity, emerging evidence suggests a link between prematurity and the development of kidney disease later in life. It has been demonstrated that the normal course of kidney development is interrupted in infants born prematurely, causing an overall decrease in functional nephrons. Yet, the pathogenesis leading to the alterations in kidney development and the subsequent pathophysiological consequences causing kidney disease on the long-term are incompletely understood. In the present review, we discuss the current knowledge on nephrogenesis and how this process is affected in prematurity. We further discuss the epidemiological evidence and experimental data demonstrating the increased risk of kidney disease in these individuals and highlight important knowledge gaps. Importantly, understanding the intricate interplay between prematurity, abnormal kidney development, and the long-term risk of kidney disease is crucial for implementing effective preventive and therapeutic strategies.

Blood pressure and cardiovascular risk in relation to birth weight and urinary sodium: an individual-participant meta-analysis of European family-based population studies

BACKGROUND

Although the relation of salt intake with blood pressure (BP) is linear, it is U-shaped for mortality and cardiovascular disease (CVD). This individual-participant meta-analysis explored whether the relation of hypertension, death or CVD with 24-h urinary sodium excretion (UVNA) or sodium-to-potassium (UNAK) ratio was modified by birth weight.

METHODS

Families were randomly enrolled in the Flemish Study on Genes, Environment and Health Outcomes (1985-2004) and the European Project on Genes in Hypertension (1999-2001). Categories of birth weight, UVNA and UNAK (≤2500, >2500-4000, >4000 g; <2.3, 2.3-4.6 and >4.6 g; and <1, 1-2, >2, respectively) were coded using deviation-from-mean coding and analyzed by Kaplan-Meier survival functions and linear and Cox regression.

RESULTS

The study population was subdivided into the Outcome ( n  = 1945), Hypertension ( n  = 1460) and Blood Pressure cohorts ( n  = 1039) to analyze the incidence of mortality and cardiovascular endpoints, hypertension and BP changes as function of UVNA changes. The prevalence of low/medium/high birth weight in the Outcome cohort was 5.8/84.5/9.7%. Over 16.7 years (median), rates were 4.9, 8 and 27.1% for mortality, CVD and hypertension, respectively, but were not associated with birth weight. Multivariable-adjusted hazard ratios were not significant for any endpoint in any of the birth weight, UVNA and UNAK strata. Adult body weight tracked with birth weight ( P  < 0.0001). The partial r in the low-birth-weight group associating changes from baseline to follow-up in UVNA and SBP was 0.68 ( P  = 0.023) but not significant in other birth weight groups.

CONCLUSION

This study did not substantiate its prior hypothesis but showed tracking of adult with birth weight and suggest that low birth weight increases salt sensitivity.

Initiatives to Reduce the Content of Sodium in Food Products and Meals and Improve the Population's Health

Table salt is the main source of sodium (Na) in the human diet. Excessive supply of Na in a diet is strongly linked to many non-communicable human diseases, such as hypertension, obesity and stomach cancer. The World Health Organization recommends that daily intake of salt in adult diets should be kept below 5 g/person/day, which corresponds to 2 g Na/person/day. However, on average, adults consume about 9-10 g/person/day, and children and young people about 7-8 g/person/day. Initiatives to reduce salt intake include modifications of food composition in collaboration with the food industry, education of consumers, salt marking on foodstuff labels and taxation of salt. A need also exists to educate society so that they choose low-sodium products. In view of the food technology and amount of salt intake, the most important and the easiest change to make is to reduce the content of salt in baked goods. This paper analyses the results of surveys regarding strategies to reduce salt content in food products and considers multifaceted initiatives to reduce salt intake as a possible efficient method of improving the population's health status.

The joint associations of high birth weight and not having siblings with metabolic obesity phenotype among school-aged children and adolescents: A National Survey in China

OBJECTIVE

Birth weight (BW) and sibling's status are two important indicators of early intrauterine environment and subsequent living environment, but no evidence has emerged on their joint associations on metabolic obesity phenotype. To determine the joint associations between BW and single-child status with childhood metabolic obesity phenotype was our purpose.

METHODS

A cross-sectional assessment of children and adolescents aged 7-18 years was performed in Chinese seven provinces in 2013. We obtained anthropometric, blood pressure and biochemical measurements, and distributed questionnaires covering demographic, neonatal and lifestyle characteristics. The metabolic obesity phenotype was defined by 2018 consensus-based criteria. Logistic regression and restricted cubic spline models were applied to evaluate the associations of BW and metabolic obesity phenotype, and estimate the multiplicative interactions and the combined associations of BW and single-child status with metabolic obesity phenotype.

RESULTS

Of enrolled 12 346 children and adolescents, the prevalence of metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO) was 1.96% and 3.03%. There were 8.95% and 4.03% children with high BW or low BW, and 67.55% did not have siblings. High BW was positively associated with MHO (OR = 1.94, 95%CI = 1.28-2.94). Single-child also had increased odds of MHO and MUO (p < 0.05), and it had joint associations with high BW showing 0.85- to 2.58-fold higher odds of MUO and MHO.

CONCLUSIONS

High BW and single-child status have joint positive associations with the subsequent odds of MHO and MUO, which should be jointly prevented through earlier screening and subsequent preventive strategies.

Perfused boundary region as biomarker for endothelial integrity in former preterms in adolescence

INTRODUCTION

Extremely low birth weight (ELBW) survivors have microvascular structural differences already described in kidney and retina, suggesting changes in endothelial integrity. A biomarker of endothelial integrity is perfused boundary region (PBR), which measures glycocalycal thickness. The endothelial glycocalyx is a complex, highly versatile structure with essential roles in vascular integrity and function. We explored PBR patterns together with other microvascular markers in healthy controls and former ELBW children.

METHODS

In the PREMATCH cohort (87 healthy controls, 93 ELBW survivors), we assessed endothelial integrity by calculating PBR (sidestream dark-field imaging), several microvascular markers (blood pressure, estimated glomerular filtration rate (eGFR_cysC)), and retinal imaging in early adolescence. We explored differences between both groups, and searched for perinatal determinants of PBR and correlations between different microvascular markers.

RESULTS

We provided reference values for PBR (average 1.90 µm, SD 0.30) in children. PBR was not different from ELBW survivors during early adolescence, despite their higher blood pressure, lower eGFR_cysC, and different retinal vessel width and tortuosity.

CONCLUSIONS

We generated reference values for PBR in early adolescence. Despite some correlations between microvascular parameters, there seem to be numerous confounders to propose PBR as a marker for endothelial integrity in ELBW survivors.

IMPACT

The endothelial glycocalyx is a complex and versatile structure. Changes in blood pressure and retinal and renal vascularization suggest a disturbance of its integrity in extremely low birth weight (ELBW) survivors. Its thickness can be measured by calculating perfused boundary region (PBR) using sidestream dark-field imaging, with a higher PBR indicating a thinner glycocalyx. We generated reference values for PBR in healthy adolescents. These values were not different in former ELBW children. Despite some correlations of PBR with other microvascular biomarkers, these are not strong enough to describe endothelial integrity and its covariates in former ELBW children.

QTc intervals are not prolonged in former ELBW infants at pre-adolescent age

BACKGROUND

Whether preterm birth is associated with cardiac conduction or repolarization abnormalities in later life is still poorly explored, with conflicting data on QTc prolongation in former extreme low birth weight (ELBW, &lt;1000 g) infants.

METHODS

Twelve lead electrocardiograms (ECG) at rest, collected in the PREMATurity as predictor of children's Cardiovascular-renal Health (PREMATCH) study in former ELBW cases and term controls during pre-adolescence (8-14 years) were analyzed on corrected QT time (QTc, Bazett) and QT dispersion (QTd). ECG findings were compared between groups (Mann-Whitney), and associations with clinical and biochemical findings were explored (Spearman). In ELBW cases, associations between QTc and perinatal characteristics (at birth, neonatal stay) were explored (Mann-Whitney, Spearman).

RESULTS

QTc and QTd were similar between 93 ELBW cases and 87 controls [409 (range 360-465) versus 409 (337-460); 40 (0-100) versus 39 (0-110)] ms. Age, height, weight, or body mass index were not associated with the QTc interval, while female sex (median difference 11.4 ms) and lower potassium (r = -0.26) were associated with longer QTc interval. We could not observe any significant association between QTc interval and perinatal characteristics.

CONCLUSIONS

There were no differences in QTc or QTd between ELBW and term controls in ECGs at rest in pre-adolescents.

IMPACT

This study aimed to assess the differences in QTc and QTd intervals between extreme low birth weight infants (ELBW) and term controls in electrocardiographic measurements at rest during pre-adolescence. This analysis confirmed the absence of significant differences in QTc or QTd findings between ELBW cases and term controls, while female sex and lower potassium were associated with a prolonged QTc interval. These data suggest that QTc screening strategies-including for pharmacovigilance-should not differentiate between former ELBW cases and term controls.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT02147457.

The Combined Effect of Birth Weight and Lifestyle on Clustered Cardio-Metabolic Risk Factors in Children and Adolescents: A National School-Based Cross-Sectional Survey

Background: Due to the adverse effects of cardio-metabolic risk factors (CMRFs) in children and adolescents on their current and later life health, and the growing evidence that birth weight and lifestyle have on CMRFs, we aimed to estimate the combined effect of birth weight and lifestyle on clustered CMRFs in children and adolescents. Methods: We enrolled 11,509 participants aged 7–18 years old in a national school-based cross-sectional study in seven provinces in China in 2013. Information on CMRFs was collected through anthropometric measurements and blood sample testing. Information on birth weight, lifestyle and other basic information were investigated through children and adolescents’ as well as parents’ questionnaires. The generalized linear mixed model was applied to estimate the odd ratio (OR) and 95% confidence interval (95% CI) for the associations between CMRFs, clustered CMRFs and birth weight, lifestyle, and the combinations of birth weight and lifestyle. Results: Overall, the prevalence of clustered CMRFs was 3.6% in children and adolescents aged 7–18 years, higher in boys (4.4%) than girls (2.9%). The combination of LBW/ideal lifestyle (OR = 2.00, 95% CI: 1.07–3.72) was associated with higher risk of clustered CMRFs, as well as in adolescents aged 13–18 years and in boys. The combination of HBW/poor lifestyle (OR = 1.74, 95% CI: 1.13–2.68) was related to elevated risk of clustered CMRFs, especially in children aged 7–12 years. Conclusions: CMRFs in Chinese children and adolescents is concerning, ideal lifestyle could weaken the association of birth weight with clustered CMRFs, especially in younger age, indicating that programs to prevent abnormal birth weight or poor lifestyle or both among children and adolescents may reduce CMRFs in China.

Trans- and Multigenerational Maternal Social Isolation Stress Programs the Blood Plasma Metabolome in the F3 Generation

Metabolic risk factors are among the most common causes of noncommunicable diseases, and stress critically contributes to metabolic risk. In particular, social isolation during pregnancy may represent a salient stressor that affects offspring metabolic health, with potentially adverse consequences for future generations. Here, we used proton nuclear magnetic resonance (¹H NMR) spectroscopy to analyze the blood plasma metabolomes of the third filial (F3) generation of rats born to lineages that experienced either transgenerational or multigenerational maternal social isolation stress. We show that maternal social isolation induces distinct and robust metabolic profiles in the blood plasma of adult F3 offspring, which are characterized by critical switches in energy metabolism, such as upregulated formate and creatine phosphate metabolisms and downregulated glucose metabolism. Both trans- and multigenerational stress altered plasma metabolomic profiles in adult offspring when compared to controls. Social isolation stress increasingly affected pathways involved in energy metabolism and protein biosynthesis, particularly in branched-chain amino acid synthesis, the tricarboxylic acid cycle (lactate, citrate), muscle performance (alanine, creatine phosphate), and immunoregulation (serine, threonine). Levels of creatine phosphate, leucine, and isoleucine were associated with changes in anxiety-like behaviours in open field exploration. The findings reveal the metabolic underpinnings of epigenetically heritable diseases and suggest that even remote maternal social stress may become a risk factor for metabolic diseases, such as diabetes, and adverse mental health outcomes. Metabolomic signatures of transgenerational stress may aid in the risk prediction and early diagnosis of non-communicable diseases in precision medicine approaches.

Salt sensitivity of blood pressure in childhood and adolescence

Although moderation of sodium intake is recommended population-wide, it remains uncertain who benefits from salt restriction. Salt sensitivity refers to changes in blood pressure in response to sodium intake and may occur with or without hypertension. Unfortunately, there is no practical way to assess salt sensitivity in daily practice. Assessment of salt sensitivity even in research studies is challenging with varying protocols utilized which may contribute to differing results. Building on studies in animals and adults, risk factors and conditions associated with salt sensitivity have been identified in the pediatric and young adult populations. This review presents the limited evidence linking obesity, low birth weight, diabetes, chronic kidney disease, and race/ethnicity with salt sensitivity in children, adolescents, and young adults. The impact of stress on sodium handling is also reviewed. The influence of age on the timing of introduction of dietary salt restriction and the long-term influence of salt sensitivity on risk for hypertension are considered. Lastly, interventions other than salt restriction that may improve salt sensitivity and may inform recommendations to families are reviewed.

Preterm birth and cardiac function in adulthood

Preterm birth affects 1 in 10 pregnancies worldwide, with increasing survival rates over the last 30 years. However, as this new generation of long-term survivors approaches middle age, recent studies have revealed increased cardiovascular risk factors and higher rates of ischaemic heart disease and heart failure. Cardiovascular imaging has identified smaller cardiac chamber size, changes in myocardial mass and impaired ventricular function, particularly under physiological stress. Accordingly, this population should be recognised as having a higher risk of heart failure as they age. In this review, we present current evidence for increased rates of heart failure and evidence of alterations in cardiac structure and function in those born preterm. We discuss potential mechanisms to explain this risk including greater frequency of co-morbidities known to be associated with heart failure. We also explore potential mechanistic links specific to the preterm-born population, including the impact of premature birth on myocardial and vascular development and the effects of perinatal haemodynamic changes and chronic lung disease on the developing heart. We highlight gaps in our knowledge and consider implications for patient management relevant to the adult physician.

Gut Microbiome over a Lifetime and the Association with Hypertension

PURPOSE OF REVIEW

Microorganisms living within an ecosystem create microbial communities and play key roles in ecosystem functioning. During their lifespan, humans share their bodies with a variety of microorganisms. More than 10-100 trillion symbiotic microorganisms live on and within human beings, and the majority of these microorganisms populate the distal ileum and colon (referred to as the gut microbiota). Interactions between the gut microbiota and the host involve signaling via chemical neurotransmitters and metabolites, neuronal pathways, and the immune system. Hypertension is a complex and heterogeneous pathophenotype. A reductionist approach that assumes that all patients who have the same signs of a disease share a common disease mechanism and thus should be treated similarly is insufficient for optimal blood pressure management. Herein, we have highlighted the contribution of the gut microbiome to blood pressure regulation in humans.

RECENT FINDINGS

Gut dysbiosis-an imbalance in the composition and function of the gut microbiota-has been shown to be associated with hypertension. Gut dysbiosis occurs via environmental pressures, including caesarean section, antibiotic use, dietary changes, and lifestyle changes over a lifetime. This review highlights how gut dysbiosis may affect a host's blood pressure over a lifetime. The review also clarifies future challenges in studies of associations between the gut microbiome and hypertension.

Maternal and gestational influences on childhood blood pressure

Exposures that contribute to a sub-optimal intrauterine environment can have an effect on the developing fetus. Impaired fetal growth that results in low birth weight is an established risk factor for cardio-metabolic disorders later in life. Recent epidemiologic and prospective cohort studies that include the maternal and gestational period have identified maternal and gestational conditions that confer increased risk for subsequent cardio-metabolic disorders in the absence of low birth weight. Maternal pre-conception health status, including chronic obesity and type 2 diabetes, increase risk for childhood obesity and obesity-related higher blood pressure (BP) in child offspring. Maternal gestational exposures, including gestational diabetes, gestational hypertension, and preeclampsia, are associated with higher BP in offspring. Other maternal exposures such as cigarette smoke and air pollution also increase risk for higher BP in child offspring. Recent, but limited, data indicate that assisted reproductive technologies can be associated with hypertension in childhood, despite otherwise normal gestation and healthy newborn. Gestational exposures associated with higher BP in childhood can be related to familial lifestyle factors, genetics, or epigenetic modification of fetal deoxyribonucleic acid (DNA). These factors, or combination of factors, as well as other adverse intrauterine conditions, could induce fetal programing leading to health consequences in later life. Current and developing research will provide additional insights on gestational exposures and fetal adjustments that increase risk for higher BP levels in childhood.

Retinal and Renal Microvasculature in Relation to Central Hemodynamics in 11-Year-Old Children Born Preterm or At Term

Background Prematurity disrupts the perinatal maturation of the microvasculature and macrovasculature and confers high risk of vascular dysfunction later in life. No previous studies have investigated the crosstalk between the microvasculature and macrovasculature in childhood. Methods and Results In a case-control study, we enrolled 55 children aged 11 years weighing <1000 g at birth and 71 matched controls (October 2014-November 2015). We derived central blood pressure (BP) wave by applanation tonometry and calculated the forward/backward pulse waves by an automated pressure-based wave separation algorithm. We measured the renal resistive index by pulsed wave Doppler and the central retinal arteriolar equivalent by computer-assisted program software. Compared with controls, patients had higher central systolic BP (101.5 versus 95.2 mm Hg, P<0.001) and backward wave amplitude (15.5 versus 14.2 mm Hg, P=0.029), and smaller central retinal arteriolar equivalent (163.2 versus 175.4 µm, P<0.001). In multivariable analyses, central retinal arteriolar equivalent was smaller with higher values (+1 SD) of central systolic BP (-2.94 µm; 95% CI, -5.18 to -0.70 µm [P=0.011]) and forward (-2.57 µm; CI, -4.81 to -0.32 µm [P=0.026]) and backward (-3.20 µm; CI, -5.47 to -0.94 µm [P=0.006]) wave amplitudes. Greater renal resistive index was associated with higher backward wave amplitude (0.92 mm Hg, P=0.036). Conclusions In childhood, prematurity compared with term birth is associated with higher central systolic BP and forward/backward wave amplitudes. Higher renal resistive index likely moves reflection points closer to the heart, thereby explaining the inverse association of central retinal arteriolar equivalent with central systolic BP and backward wave amplitude. These observations highlight the crosstalk between the microcirculation and macrocirculation in children. Registration URL: http://www.clinicaltrials.gov. Unique Identifier: NCT02147457.

Glomerular Filtration Rate in Former Extreme Low Birth Weight Infants over the Full Pediatric Age Range: A Pooled Analysis

Various cohort studies document a lower glomerular filtration rate (GFR) in former extremely low birth weight (ELBW, <1000 g) neonates throughout childhood when compared to term controls. The current aim is to pool these studies to describe the GFR pattern over the pediatric age range. To do so, we conducted a systematic review on studies reporting on GFR measurements in former ELBW cases while GFR data of healthy age-matched controls included in these studies were co-collected. Based on 248 hits, 6 case-control and 3 cohort studies were identified, with 444 GFR measurements in 380 former ELBW cases (median age 5.3–20.7 years). The majority were small (17–78 cases) single center studies, with heterogeneity in GFR measurement (inulin, cystatin C or creatinine estimated GFR formulae) tools. Despite this, the median GFR (mL/min/1.73 m²) within case-control studies was consistently lower (−13%, range −8% to −25%) in cases, so that a relevant minority (15–30%) has a eGFR<90 mL/min/1.73 m²). Consequently, this pooled analysis describes a consistent pattern of reduced eGFR in former ELBW cases throughout childhood. Research should focus on perinatal risk factors for impaired GFR and long-term outcome, but is hampered by single center cohorts, study size and heterogeneity of GFR assessment tools.

Cardiovascular effects of prenatal stress-Are there implications for cerebrovascular, cognitive and mental health outcome?

Prenatal stress programs offspring cognitive and mental health outcome. We reviewed whether prenatal stress also programs cardiovascular dysfunction which potentially modulates cerebrovascular, cognitive and mental health disorders. We focused on maternal stress and prenatal glucocorticoid (GC) exposure which have different programming effects. While maternal stress induced cortisol is mostly inactivated by the placenta, synthetic GCs freely cross the placenta and have different receptor-binding characteristics. Maternal stress, particularly anxiety, but not GC exposure, has adverse effects on maternal-fetal circulation throughout pregnancy, probably by co-activation of the maternal sympathetic nervous system, and by raising fetal catecholamines. Both effects may impair neurodevelopment. Experimental data also suggest that severe maternal stress and GC exposure during early and mid-gestation may increase the risk for cardiovascular disorders. Human data are scarce and especially lacking for older age. Programming mechanisms include aberrations in cardiac and kidney development, and functional changes in the renin-angiotensin-aldosterone-system, stress axis and peripheral and coronary vasculature. Adequate experimental or human studies examining the consequences for cerebrovascular, cognitive and mental disorders are unavailable.

Extremely Low Birth Weight Predisposes to Impaired Renal Health: A Pooled Analysis

BACKGROUND

A number of studies examined the association between preterm delivery and kidney size and function later in life. However, the number of cases in published cohort studies is low. This study was aimed at performing a multicenter collaboration to pool data to obtain more accurate results to quantify the extent of renal impairment in former extremely low birth weight (ELBW; <1,000 g) children.

METHODOLOGY

We performed a subject-level meta-analysis to pool data from Cracow (64 cases/34 controls) and Leuven (93 cases/87 controls). We assessed and analyzed cystatin C, estimated glomerular filtration rate (eGFR), ultrasound kidney length, and blood pressure (BP) in 11-year-old ELBW children compared with controls born at term. The prevalence of hypertension (HT) and prehypertension (preHT) in both groups was also analyzed.

RESULTS

The study group comprised 157 former ELBW children (gestational age 23-33 weeks and birth weight 430-1,000 g) and 123 children born at term. Former ELBW children had lower mean eGFR (100.62 ± 16.53 vs. 111.89 ± 15.26 mL/min/1.73 m2; p < 0.001), smaller absolute kidney length (8.56 ± 0.78 vs. 9.008 ± 0.73 cm; <0.001), and higher systolic (111.8 ± 9.8 vs. 107.2 ± 9.07 mm Hg; p = 0.01) and diastolic (68.6 ± 6.8 vs. 66.3 ± 7.7 mm Hg; p = 0.03) BP. Smaller renal size in former ELBW children was positively associated with lower birth weight, shorter gestational age, and severity of perinatal complications (intraventricular hemorrhage, length of stay, mechanical ventilation, and oxygen therapy).

CONCLUSION

ELBW is associated with lower eGFR and a high frequency of preHT and HT.

Kidney Size, Renal Function, Ang (Angiotensin) Peptides, and Blood Pressure in Young Adults Born Preterm

Preterm birth incurs a higher risk for adult cardiovascular diseases, including hypertension. Because preterm birth may impact nephrogenesis, study objectives were to assess renal size and function of adults born preterm versus full term and to examine their relationship with blood pressure (BP; 24-hour ambulatory BP monitoring) and circulating renin-Ang (angiotensin) system peptides. The study included 92 young adults born (1987-1997) preterm (≤29 weeks of gestation) and term (n=92) matched for age, sex, and race. Young adults born preterm had smaller kidneys (80±17 versus 90±18 cm³/m²; P<0.001), higher urine albumin-to-creatinine ratio (0.70; interquartile range, 0.47-1.14 versus 0.58, interquartile range 0.42 to 0.78 mg/mmol, P=0.007), higher 24-hour systolic (121±9 versus 116±8 mm Hg; P=0.001) and diastolic (69±5 versus 66±6 mm Hg; P=0.004) BP, but similar estimated glomerular filtration rate. BP was inversely correlated with kidney size in preterm participants. Plasma Ang I was higher in preterm versus term participants (36.3; interquartile range, 13.2-62.3 versus 19.4; interquartile range, 9.9-28.1 pg/mL; P<0.001). There was no group difference in renin, Ang II, Ang (1-7), and alamandine. In the preterm, but not in the term group, higher BP was significantly associated with higher renin and alamandine and lower birth weight and gestational age with smaller adult kidney size. Young adults born preterm have smaller kidneys, higher urine albumin-to-creatinine ratio, higher BP, and higher circulating Ang I levels compared with term controls. Preterm young adults with smaller kidneys have higher BP. Clinical Trial Registration- URL: http://www.clinicaltrials.gov . Unique identifier: NCT03261609.

Physiologically based pharmacokinetic (PBPK) modeling and simulation in neonatal drug development: how clinicians can contribute

Introduction: Legal initiatives to stimulate neonatal drug development should be accompanied by development of valid research tools. Physiologically based (PB)-pharmacokinetic (PK) modeling and simulation are established tools, accepted by regulatory authorities. Consequently, PBPK holds promise to be a strong research tool to support neonatal drug development. Area covered: The currently available PBPK models still have poor predictive performance in neonates. Using an illustrative approach on distinct PK processes of absorption, distribution, metabolism, excretion, and real-world data in neonates, we provide evidence on the need to further refine available PBPK system parameters through generation and integration of new knowledge. This necessitates cross talk between clinicians and modelers to integrate knowledge (PK datasets, system knowledge, maturational physiology) or test and refine PBPK models. Expert opinion: Besides refining these models for 'small molecules', PBPK model development should also be more widely applied for therapeutic proteins and to determine exposure through breastfeeding. Researchers should also be aware that PBPK modeling in combination with clinical observations can also be used to elucidate age-related changes that are almost impossible to study based on in vivo or in vitro data. This approach has been explored for hepatic biliary excretion, renal tubular activity, and central nervous system exposure.

Endothelial Colony-Forming Cells in Young Adults Born Preterm: A Novel Link Between Neonatal Complications and Adult Risks for Cardiovascular Disease

BACKGROUND

Preterm birth is linked to cardiovascular risks and diseases. Endothelial progenitor cells play a critical role in vascular development and repair. Cord blood endothelial progenitor cells of preterm-born infants, especially endothelial colony-forming cells (ECFC), show enhanced susceptibility to prematurity-related pro-oxidant stress. Whether ECFC dysfunction is present in adulthood following preterm birth is unknown.

METHODS AND RESULTS

This cross-sectional observational study includes 55 preterm-born (≤29 gestational weeks) young adults (18-29 years old, 38% male) and 55 sex- and age-matched full-term controls. ECFC were isolated from peripheral blood; cell proliferative and vascular cord formation capacities were assessed in vitro. Daytime systolic blood pressure was higher, whereas glucose tolerance and body mass index were lower in preterm-born subjects. ECFC colonies grew in culture for 62% of full-term- and 58% of preterm-born participants. Preterm-born participants have formed ECFC colonies later in culture and have reduced proliferation compared with controls. Only in preterm-born individuals, we observed that the later the ECFC colony grows in culture, the worse was overall ECFC function. In addition, in preterms, elevated systolic blood pressure significantly correlated with reduced ECFC proliferation (r_S=-0.463; P=0.030) and numbers of branches formed on matrigel (r_S=-0.443; P=0.039). In preterm-born subjects, bronchopulmonary dysplasia was associated with impaired ECFC function, whereas exposure to antenatal steroids related to better ECFC function.

CONCLUSIONS

This study is the first to examine ECFC in preterm-born adults and to demonstrate ECFC dysfunction compared with full-term controls. In the preterm-born group, ECFC dysfunction was associated with bronchopulmonary dysplasia, the major prematurity-related neonatal morbidity, and with increased systolic blood pressure into adulthood.

Reproducibility of Retinal Microvascular Traits Decoded by the Singapore I Vessel Assessment Software Across the Human Age Range

BACKGROUND

Retinal microvascular traits predict adverse health outcomes. The Singapore I Vessel Assessment (SIVA) software improved automated postprocessing of retinal photographs. In addition to microvessel caliber, it generates measures of arteriolar and venular geometry. Few studies addressed the reproducibility of SIVA measurements across a wide age range.

METHODS

In the current study, 2 blinded graders read images obtained by nonmydriatic retinal photography twice in 20 11-year-old children, born prematurely (n = 10) or at term (n = 10) and in 60 adults (age range, 18.9–86.1 years).

RESULTS

Former preterm compared with term children had lower microvessel diameter and disorganized vessel geometry with no differences in intraobserver and interobserver variability. Among adults, microvessel caliber decreased with age and blood pressure and arteriolar geometry was inversely correlated with female sex and age. Intraobserver differences estimated by the Bland–Altman method did not reach significance for any measurement. Across measurements, median reproducibility (RM) expressed as percent of the average trait value was 8.8% in children (median intraclass correlation coefficient [ICC], 0.94) and 8.0% (0.97) in adults. Likewise, interobserver differences did not reach significance with RM (ICC) of 10.6% (0.85) in children and 10.4% (0.93) in adults. Reproducibility was best for microvessel caliber (intraobserver/interobserver RM, 4.7%/6.0%; ICC, 0.98/0.96), worst for venular geometry (17.0%/18.8%; 0.93/0.84), and intermediate for arteriolar geometry (10.9%/14.9%; 0.95/0.86).

CONCLUSIONS

SIVA produces repeatable measures of the retinal microvasculature in former preterm and term children and in adults, thereby proving its usability from childhood to old age.

Association between cognition and the retinal microvasculature in 11-year old children born preterm or at term

BACKGROUND

Retinal microvessels can be visualized non-invasively and mirror the status of the cerebral microvasculature.

AIMS

To investigate whether in young children born prematurely or at term cognitive performance is related to retinal microvascular traits.

STUDY DESIGN, SUBJECTS

In 93 prematurely born infants (birth weight < 1000 g) and 87 controls born at term, we measured head circumference (HC) and determined intelligence quotient (IQ) by combining matrix reasoning and spatial span (Wechsler Non-Verbal test, Dutch version) and post-processed retinal photographs using Singapore I Vessel Assessment software (version 3.6).

OUTCOME MEASURES, RESULTS

Compared with controls, cases had smaller HC (51.7 vs 53.4 cm; p < 0.001), lower IQ (93.9 vs 109.2; p < 0.001), smaller retinal arteriolar (CRAE; 162.7 vs 174.0 μm; p < 0.001) and venular (CRVE; 234.9 vs 242.8 μm; p = 0.003) diameters and CRAE/CRVE ratio (0.69 vs 0.72; p = 0.001). A 1-SD decrease in CRAE was associated with smaller HC (-0.53 cm; p < 0.001) and lower total IQ (-3.74; p < 0.001), matrix reasoning (-1.77; p = 0.004) and spatial span (-2.03; p = 0.002). These associations persisted after adjustment for sex and age and risk factors for cognitive impairment, including blood pressure, body mass index and parental educational attainment.

CONCLUSIONS

HC, total IQ, matrix reasoning and spatial span decrease with smaller retinal arteriolar diameter. Our findings suggest that maldevelopment of the cerebral microcirculation, as mirrored by the retinal microvasculature, has lasting effects on the growth of the brain and cognitive performance of prematurely born children.

Ibuprofen exposure in early neonatal life does not affect renal function in young adolescence

INTRODUCTION

Ibuprofen exposure results in acute transient renal dysfunction in preterm neonates, but we are unaware of data on long-term renal safety.

METHODS

In a previously studied cohort of extreme low birth weight (ELBW, <1000 g) cases, the PREMATurity as predictor of children's Cardiovascular-renal Health study generated data on renal function (renal length, estimated glomerular filtration rate based on cystatin C (eGFR_cysC) at the age of 11 years. This data set in 93 ELBW cases may also generate data on long-term drug safety on ibuprofen. In this post hoc analysis, we linked markers of renal function in young adolescence in ELBW cases with their perinatal (prenatal maternal, setting at birth, treatment modalities including drug prescription during neonatal stay, neonatal creatinine values, postdischarge growth) characteristics, including but not limited to ibuprofen exposure during neonatal stay.

RESULTS

Ibuprofen exposure was not associated with significant differences in renal length or eGFR_cysC. Moreover, we were unable to identify any other risk factor (perinatal characteristics, postnatal creatinine trends, postdischarge growth) on renal outcome in this cohort.

CONCLUSIONS

Neonatal exposure to ibuprofen did not affect renal function. Larger studies are needed to explore the confounders of variability in renal function in former ELBW cases. This matters since ELBW relates to risk for hypertension, cardiovascular events and renal disease in later life and identification of risk factors holds the promise of secondary prevention.

TRIAL REGISTRATION NUMBER

NCT02147457.

Association between exposure to particulate matter during pregnancy and birthweight: a systematic review and a meta-analysis of birth cohort studies

Studies of the associations between maternal exposure to particulate matter (PM) and risk of adverse effects on fetal growth are inconsistent and inconclusive. This question can be well answered by carefully designed birth cohort studies; however, so far the evidence from such studies has not come to the same conclusion. We sought to evaluate the association between maternal exposures to PM and low birthweight (LBW) enrolling 14 studies from 11 centers, and to explore the influence of trimester and exposure assessment methods on between-center heterogeneity in this association. Data were derived from PubMed, Embase, Google Scholar, CNKI, and WanFang database, references from relevant articles, and results from published studies until March 2017. Using a random-effects meta-analysis, we combined the coefficient and odds ratios (OR) of individual studies conducted among 14 birth cohort studies. Random-effect meta-analysis results suggested that a 17% and 6% increase in risk of LBW was relevant to a 10 mg/m3 rise in PM2.5 and PM10 exposure concentrations at the 3rd trimester (pooled odds ratios (OR), 1.17 and 1.06; 95% confidence interval (CI), 0.94-1.46 and 0.97-1.15, respectively), but the null value was included in our 95% CI. Our results showed that exposure to PM2.5 and PM10 during pregnancy has a positive relevance to LBW based on birth cohort studies. However, neither reached formal statistical significance. Negative impacts on outcomes of birth is implied by maternal exposure to PM. Further mechanistic researches are needed to explain the connection between PM pollution and LBW.