Maternal diabetes programs hypertension and kidney injury in offspring

Early-life exposures and long-term health: adverse gestational environments and the programming of offspring renal and vascular disease

According to the Developmental Origins of Health and Disease hypothesis, exposure to certain environmental influences during early life may be a key determinant of fetal development and short- and long-term offspring health. Indeed, adverse conditions encountered during the fetal, perinatal, and early childhood stages can alter normal development and growth, as well as put the offspring at elevated risk of developing long-term health conditions in adulthood, including chronic kidney disease and cardiovascular diseases. Of relevance in understanding the mechanistic basis of these long-term health conditions are previous findings showing low glomerular number in human intrauterine growth restriction and low birth weight-indicators of a suboptimal intrauterine environment. In different animal models, the main suboptimal intrauterine conditions studied relate to maternal dietary manipulations, poor micronutrient intake, prenatal ethanol exposure, maternal diabetes, glucocorticoid and chemical exposure, hypoxia, and placental insufficiency. These studies have demonstrated changes in kidney structure, glomerular endowment, and expression of key genes and signaling pathways controlling endocrine, excretion, and filtration function of the offspring. This review aims to summarize those studies to uncover the effects and mechanisms by which adverse gestational environments impact offspring renal and vascular health in adulthood. This is important for identifying agents and interventions that can prevent and mitigate the long-term consequences of an adverse intrauterine environment on the subsequent generation.NEW & NOTEWORTHY Human data and experimental animal data show that suboptimal environments during fetal development increase the risk of renal and vascular diseases in adult-life. This is related to permanent changes in kidney structure, function, and expression of genes and signaling pathways controlling filtration, excretion, and endocrine function. Uncovering the mechanisms by which offspring renal development and function is impacted is important for identifying ways to mitigate the development of diseases that strain health care services worldwide.

Sex differences in fetal kidney reprogramming: the case in the renin-angiotensin system

During the early stages of the development of the living multiorgan systems, genome modifications other than sequence variation occur that guide cell differentiation and organogenesis. These modifications are known to operate as a fetal programming code during this period, and recent research indicates that there are some tissue-specific codes in organogenesis whose effects may persist after birth until adulthood. Consequently, the events that disrupt the pre-established epigenetic pattern could induce shifts in organ physiology, with implications on health from birth or later in adult life. Chronic kidney disease (CKD) is one of the main causes of mortality worldwide; its etiology is multifactorial, but diabetes, obesity, and hypertension are the main causes of CKD in adults, although there are other risk factors that are mainly associated with an individual's lifestyle. Recent studies suggest that fetal reprogramming in the developing kidney could be implicated in the susceptibility to kidney disease in both childhood and adulthood. Some epigenetic modifications, such as genome methylation status, dysregulation of miRNA, and histone coding alterations in genes related to the regulation of the renin-angiotensin axis, a common denominator in CKD, may have originated during fetal development. This review focuses on epigenetic changes during nephrogenesis and their repercussions on kidney health and disease. In addition, the focus is on the influence of environmental factors during pregnancy, such as maternal metabolic diseases and dietary and metabolic conditions, as well as some sex differences in fetal kidney reprogramming during which dysregulation of the renin-angiotensin system is involved.

Association and pathways of baseline and longitudinal hemoglobin A1c with the risk of incident stroke: A nationwide prospective cohort study

AIMS

To investigate the association of baseline and long-term mean hemoglobin A1c (HbA1c) with the risk of stroke.

METHODS

A total of 11,220 participants aged over 45 years and without stroke at baseline were enrolled from the China Health and Retirement Longitudinal Study. Mean HbA1c was calculated as the mean of HbA1c at all previous visits before stroke occurred or the end of follow-up. Multivariable-adjusted Cox regressions and Bayesian network were used for the analysis.

RESULTS

During a median follow-up of 7.50 years, a total of 626 cases of stroke occurred. The risk of stroke increased with quintiles of baseline and mean HbA1c, the hazard ratio (HR) in Q5 versus Q1 was 1.30 (95 % confidence interval [CI],1.03-1.64) and 1.79 (95 % CI, 1.38-2.34), respectively. Per 1 unit increase in baseline and mean HbA1c was associated with 10 % (HR, 1.10; 95 % CI, 1.02-1.18) an 12 % (HR, 1.12; 95 % CI, 1.05-1.19) higher risk of stroke. Bayesian network analysis showed that the pathway from HbA1c to stroke was through hypertension, dyslipidemia, obesity, and inflammation.

CONCLUSIONS

Elevated levels of both baseline and long-term HbA1c were associated with increased risk of stroke, and hypertension and obesity played an important role in the pathway.

Long-term outcomes and potential mechanisms of offspring exposed to intrauterine hyperglycemia

Diabetes mellitus during pregnancy, which can be classified into pregestational diabetes and gestational diabetes, has become much more prevalent worldwide. Maternal diabetes fosters an intrauterine abnormal environment for fetus, which not only influences pregnancy outcomes, but also leads to fetal anomaly and development of diseases in later life, such as metabolic and cardiovascular diseases, neuropsychiatric outcomes, reproduction malformation, and immune dysfunction. The underlying mechanisms are comprehensive and ambiguous, which mainly focus on microbiota, inflammation, reactive oxygen species, cell viability, and epigenetics. This review concluded with the influence of intrauterine hyperglycemia on fetal structure development and organ function on later life and outlined potential mechanisms that underpin the development of diseases in adulthood. Maternal diabetes leaves an effect that continues generations after generations through gametes, thus more attention should be paid to the prevention and treatment of diabetes to rescue the pathological attacks of maternal diabetes from the offspring.

Maternal obesity and offspring health: Adapting metabolic changes through autophagy and mitophagy

Maternal obesity leads to obstetric complications and a high prevalence of metabolic anomalies in the offspring. Among various contributing factors for maternal obesity-evoked health sequelae, developmental programming is considered as one of the leading culprit factors for maternal obesity-associated chronic comorbidities. Although a unified theory is still lacking to systematically address multiple unfavorable postnatal health sequelae, a cadre of etiological machineries have been put forward, including lipotoxicity, inflammation, oxidative stress, autophagy/mitophagy defect, and cell death. Hereinto, autophagy and mitophagy play an essential housekeeping role in the clearance of long-lived, damaged, and unnecessary cell components to maintain and restore cellular homeostasis. Defective autophagy/mitophagy has been reported in maternal obesity and negatively impacts fetal development and postnatal health. This review will provide an update on metabolic disorders in fetal development and postnatal health issues evoked by maternal obesity and/or intrauterine overnutrition and discuss the possible contribution of autophagy/mitophagy in metabolic diseases. Moreover, relevant mechanisms and potential therapeutic strategies will be discussed in an effort to target autophagy/mitophagy and metabolic disturbances in maternal obesity.

Perinatal Obesity Sensitizes for Premature Kidney Aging Signaling

Chronic Kidney Disease (CKD), a global health burden, is strongly associated with age-related renal function decline, hypertension, and diabetes, which are all frequent consequences of obesity. Despite extensive studies, the mechanisms determining susceptibility to CKD remain insufficiently understood. Clinical evidence together with prior studies from our group showed that perinatal metabolic disorders after intrauterine growth restriction or maternal obesity adversely affect kidney structure and function throughout life. Since obesity and aging processes converge in similar pathways we tested if perinatal obesity caused by high-fat diet (HFD)-fed dams sensitizes aging-associated mechanisms in kidneys of newborn mice. The results showed a marked increase of γH2AX-positive cells with elevated 8-Oxo-dG (RNA/DNA damage), both indicative of DNA damage response and oxidative stress. Using unbiased comprehensive transcriptomics we identified compartment-specific differentially-regulated signaling pathways in kidneys after perinatal obesity. Comparison of these data to transcriptomic data of naturally aged kidneys and prematurely aged kidneys of genetic modified mice with a hypomorphic allele of Ercc1, revealed similar signatures, e.g., inflammatory signaling. In a biochemical approach we validated pathways of inflammaging in the kidneys after perinatal obesity. Collectively, our initial findings demonstrate premature aging-associated processes as a consequence of perinatal obesity that could determine the susceptibility for CKD early in life.

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.

Early-Life Origins of Metabolic Syndrome: Mechanisms and Preventive Aspects

One of the leading global public-health burdens is metabolic syndrome (MetS), despite the many advances in pharmacotherapies. MetS, now known as "developmental origins of health and disease" (DOHaD), can have its origins in early life. Offspring MetS can be programmed by various adverse early-life conditions, such as nutrition imbalance, maternal conditions or diseases, maternal chemical exposure, and medication use. Conversely, early interventions have shown potential to revoke programming processes to prevent MetS of developmental origins, namely reprogramming. In this review, we summarize what is currently known about adverse environmental insults implicated in MetS of developmental origins, including the fundamental underlying mechanisms. We also describe animal models that have been developed to study the developmental programming of MetS. This review extends previous research reviews by addressing implementation of reprogramming strategies to prevent the programming of MetS. These mechanism-targeted strategies include antioxidants, melatonin, resveratrol, probiotics/prebiotics, and amino acids. Much work remains to be accomplished to determine the insults that could induce MetS, to identify the mechanisms behind MetS programming, and to develop potential reprogramming strategies for clinical translation.

AT2R deficiency in mice accelerates podocyte dysfunction in diabetic progeny in a sex-dependent manner

AIMS/HYPOTHESIS

The angiotensin II receptor type 2 (AT₂R) may be a potential therapeutic target for the treatment of hypertension and chronic kidney disease (CKD). The expression and function of AT₂R in the vasculature and kidney appear sexually dimorphic. We hypothesised that Agtr2 knockout dams (AT₂RKO) with gestational diabetes would program their offspring for subsequent hypertension and CKD in a sex-dependent manner.

METHODS

Age- and sex-matched offspring of non-diabetic and diabetic dams of wild-type (WT) and AT₂RKO mice were followed from 4 to 20 weeks of age and were monitored for development of hypertension and nephropathy; a mouse podocyte cell line (mPOD) was also studied.

RESULTS

Body weight was progressively lower in female compared with male offspring throughout the lifespan. Female but not male offspring from diabetic AT₂RKO dams developed insulin resistance. Compared with the offspring of non-diabetic dams, the progeny of diabetic dams had developed more hypertension and nephropathy (apparent glomerulosclerosis with podocyte loss) at 20 weeks of age; this programming was more pronounced in the offspring of AT₂RKO diabetic dams, particularly female AT₂RKO progeny. Female AT₂RKO offspring had lower basal ACE2 glomerular expression, resulting in podocyte loss. The aberrant ACE2/ACE ratio was far more diminished in glomeruli of female progeny of diabetic AT₂RKO dams than in male progeny. Knock-down of Agtr2 in mPODs confirmed the in vivo data.

CONCLUSIONS/INTERPRETATION

AT₂R deficiency accelerated kidney programming in female progeny of diabetic dams, possibly due to loss of protective effects of ACE2 expression in the kidney.

Down-regulation of AMPK/PPARδ signalling promotes endoplasmic reticulum stress-induced endothelial dysfunction in adult rat offspring exposed to maternal diabetes

AIMS

Exposure to maternal diabetes is associated with increased prevalence of hypertension in the offspring. The mechanisms underlying the prenatal programming of hypertension remain unclear. Because endoplasmic reticulum (ER) stress plays a key role in vascular endothelial dysfunction in hypertension, we investigated whether aberrant ER stress causes endothelial dysfunction and high blood pressure in the offspring of dams with diabetes.

METHODS AND RESULTS

Pregnant Sprague-Dawley rats were intraperitoneally injected with streptozotocin (35 mg/kg) or citrate buffer at Day 0 of gestation. Compared with control mother offspring (CMO), the diabetic mother offspring (DMO) had higher blood pressure and impaired endothelium-dependent relaxation in mesenteric arteries, accompanied by decreased AMPK phosphorylation and PPARδ expression, increased ER stress markers, and reactive oxygen species (ROS) levels. The inhibition of ER stress reversed these aberrant changes in DMO. Ex vivo treatment of mesenteric arteries with an AMPK agonist (A769662) or a PPARδ agonist (GW1516) improved the impaired EDR in DMO and reversed the tunicamycin-induced ER stress, ROS production, and EDR impairment in mesenteric arteries from CMO. The effects of A769662 were abolished by co-treatment with GSK0660 (PPARδ antagonist), whereas the effects of GW1516 were unaffected by Compound C (AMPK inhibitor).

CONCLUSION

These results suggest an abnormal foetal programming of vascular endothelial function in offspring of rats with maternal diabetes that is associated with increased ER stress, which can be ascribed to down-regulation of AMPK/PPARδ signalling cascade.

Effects of Environmental Conditions on Nephron Number: Modeling Maternal Disease and Epigenetic Regulation in Renal Development

A growing body of evidence suggests that low nephron numbers at birth can increase the risk of chronic kidney disease or hypertension later in life. Environmental stressors, such as maternal malnutrition, medication and smoking, can influence renal size at birth. Using metanephric organ cultures to model single-variable environmental conditions, models of maternal disease were evaluated for patterns of developmental impairment. While hyperthermia had limited effects on renal development, fetal iron deficiency was associated with severe impairment of renal growth and nephrogenesis with an all-proximal phenotype. Culturing kidney explants under high glucose conditions led to cellular and transcriptomic changes resembling human diabetic nephropathy. Short-term high glucose culture conditions were sufficient for long-term alterations in DNA methylation-associated epigenetic memory. Finally, the role of epigenetic modifiers in renal development was tested using a small compound library. Among the selected epigenetic inhibitors, various compounds elicited an effect on renal growth, such as HDAC (entinostat, TH39), histone demethylase (deferasirox, deferoxamine) and histone methyltransferase (cyproheptadine) inhibitors. Thus, metanephric organ cultures provide a valuable system for studying metabolic conditions and a tool for screening for epigenetic modifiers in renal development.

Targeting the Renin-Angiotensin-Aldosterone System to Prevent Hypertension and Kidney Disease of Developmental Origins

The renin-angiotensin-aldosterone system (RAAS) is implicated in hypertension and kidney disease. The developing kidney can be programmed by various early-life insults by so-called renal programming, resulting in hypertension and kidney disease in adulthood. This theory is known as developmental origins of health and disease (DOHaD). Conversely, early RAAS-based interventions could reverse program processes to prevent a disease from occurring by so-called reprogramming. In the current review, we mainly summarize (1) the current knowledge on the RAAS implicated in renal programming; (2) current evidence supporting the connections between the aberrant RAAS and other mechanisms behind renal programming, such as oxidative stress, nitric oxide deficiency, epigenetic regulation, and gut microbiota dysbiosis; and (3) an overview of how RAAS-based reprogramming interventions may prevent hypertension and kidney disease of developmental origins. To accelerate the transition of RAAS-based interventions for prevention of hypertension and kidney disease, an extended comprehension of the RAAS implicated in renal programming is needed, as well as a greater focus on further clinical translation.

Exposure to maternal diabetes induces endothelial dysfunction and hypertension in adult male rat offspring

The adverse environment in early life can modulate adult phenotype, including blood pressure. Our previous study shows, in a rat streptozotocin (STZ)-induced maternal diabetes model, fetal exposure to maternal diabetes is characterized by established hypertension in the offspring. However, the exact mechanisms are not known. Our present study found, as compared with male control mother offspring (CMO), male diabetic mother offspring (DMO) had higher blood pressure with arterial dysfunction, i.e., decreased acetylcholine (Ach)-induced vasodilation. But there is no difference in blood pressure between female CMO and DMO. The decreased Ach-induced vasodilation was related to decreased nitric oxide (NO) production in the endothelium, not NO sensitivity in vascular smooth muscle because sodium nitroprusside (SNP)-mediated vasodilation was preserved; there was decreased NO production and lower eNOS phosphorylation in male DMO. The reactive oxygen species (ROS) level was increased in male DMO than CMO; normalized ROS levels with tempol increased NO production, normalized Ach-mediated vasodilation, and lowered blood pressure in male DMO rats. It indicates that diabetic programming hypertension is related to arterial dysfunction; normalizing ROS might be a potential strategy for the prevention of hypertension in the offspring.

Tubular Deficiency of Heterogeneous Nuclear Ribonucleoprotein F Elevates Systolic Blood Pressure and Induces Glycosuria in Mice

We reported previously that overexpression of heterogeneous nuclear ribonucleoprotein F (Hnrnpf) in renal proximal tubular cells (RPTCs) suppresses angiotensinogen (Agt) expression, and attenuates systemic hypertension and renal injury in diabetic Hnrnpf-transgenic (Tg) mice. We thus hypothesized that deletion of Hnrnpf in the renal proximal tubules (RPT) of mice would worsen systemic hypertension and kidney injury, perhaps revealing novel mechanism(s). Tubule-specific Hnrnpf knockout (KO) mice were generated by crossbreeding Pax8-Cre mice with floxed Hnrnpf mice on a C57BL/6 background. Both male and female KO mice exhibited elevated systolic blood pressure, increased urinary albumin/creatinine ratio, tubulo-interstitial fibrosis and glycosuria without changes in blood glucose or glomerular filtration rate compared with control littermates. However, glycosuria disappeared in male KO mice at the age of 12 weeks, while female KO mice had persistent glycosuria. Agt expression was elevated, whereas sodium-glucose co-transporter 2 (Sglt2) expression was down-regulated in RPTs of both male and female KO mice as compared to control littermates. In vitro, KO of HNRNPF in human RPTCs (HK-2) by CRISPR gRNA up-regulated AGT and down-regulated SGLT2 expression. The Sglt2 inhibitor canagliflozin treatment had no effect on Agt and Sglt2 expression in HK-2 and in RPTCs of wild-type mice but induced glycosuria. Our results demonstrate that Hnrnpf plays a role in the development of hypertension and glycosuria through modulation of renal Agt and Sglt2 expression in mice, respectively.

Normal foetal kidney volume in offspring of women treated for gestational diabetes

AIMS

The worldwide prevalence of gestational diabetes mellitus (GDM) is increasing. Studies in rodent models indicate that hyperglycaemia during pregnancy alters kidney development, yet few studies have examined if this is so in humans. The objective of this study was to evaluate the association of treated GDM with foetal kidney size.

MATERIALS AND METHODS

Participants were recruited from an Australian tertiary hospital, and clinical data were collected from women without GDM and women diagnosed and treated for GDM and their offspring. Participants underwent an obstetric ultrasound at 32-34 weeks gestation for foetal biometry and foetal kidney volume measurement.

RESULTS

Sixty-four non-GDM and 64 GDM women participated in the study. Thirty percent of GDM women were diagnosed with fasting hyperglycaemia, while 89% had an elevated 2-hour glucose level. Maternal age, weight and body mass index were similar in women with and without GDM. Estimated foetal weight, foetal kidney dimensions, total foetal kidney volume and birth weight were similar in offspring of women with and without GDM.

CONCLUSIONS

We conclude that a period of mild hyperglycaemia prior to diagnosis of GDM and treatment initiation, which coincides with a period of rapid nephron formation and kidney growth, does not alter kidney size at 32-34 weeks gestation.

Inhibition of Renin-Angiotensin System from Conception to Young Mature Life Induces Salt-Sensitive Hypertension via Angiotensin II-Induced Sympathetic Overactivity in Adult Male Rats

Previous studies indicate that perinatal compromise of taurine causes cardiovascular disorders in adults via the influence of taurine on renin-angiotensin system (RAS). This study tested whether perinatal inhibition of the RAS would itself alter the adult cardiovascular system in a similar way. Female Sprague-Dawley rats were fed normal rat chow and given water alone (Control) or water containing captopril (400 mg/l) from conception until weaning. Then, the male offspring drank water or water containing captopril until 5 weeks of age followed by normal rat chow and water alone until 7 weeks of age. Thereafter, they drank water alone (Control, Captopril) or 1% NaCl solution (Control+1%, Captopril+1%). At 9 weeks of age, all animals were implanted with femoral arterial and venous catheters. Forty-eight hours later, blood chemistry, glucose tolerance, and hemodynamic parameters were determined in freely moving conscious rats. Then, the same experiments were repeated 2 days after captopril treatment. Body weights, kidney and heart to body weight ratios, fasting and non-fasting blood sugar, glucose tolerance, and heart rates were not significantly different among groups. Further, plasma sodium, mean arterial pressure, and sympathetic activity significantly increased whereas baroreflex sensitivity decreased in Captopril+1% compared to other groups. These changes were normalized by acute captopril treatment and the arterial pressure differences also by acute ganglionic and central adrenergic blockade. The present study suggests that inhibition of the RAS in the early life induces RAS overactivity, leading to salt-sensitive hypertension via sympathetic nervous system overactivity and depressed baroreflex sensitivity in adult male rats.

The relationship between maternal obesity and diabetes during pregnancy on offspring kidney structure and function in humans: a systematic review

Evidence from animal models indicates that exposure to an obesogenic or hyperglycemic intrauterine environment adversely impacts offspring kidney development and renal function. However, evidence from human studies has not been evaluated systematically. Therefore, the aim of this systematic review was to synthesize current research in humans that has examined the relationship between gestational obesity and/or diabetes and offspring kidney structure and function. Systematic electronic database searches were conducted of five relevant databases (CINAHL, Cochrane, EMBASE, MEDLINE and Scopus). Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines were followed, and articles screened by two independent reviewers generated nine eligible papers for inclusion. Six studies were assessed as being of 'neutral' quality, two of 'negative' and one 'positive' quality. Observational studies suggest that offspring exposed to a hyperglycemic intrauterine environment are more likely to display markers of renal dysfunction and are at higher risk of end-stage renal disease. There was limited and inconsistent evidence for a link between exposure to an obesogenic intrauterine environment and offspring renal outcomes. Offspring renal outcome measures across studies were diverse, with a large variation in offspring age at follow-up, limiting comparability across studies. The collective current body of evidence suggests that intrauterine exposure to maternal obesity and/or diabetes adversely impacts renal programming in offspring, with an increased risk of kidney disease in adulthood. Further high-quality, longitudinal, prospective cohort studies that measure indicators of offspring renal development and function, including fetal kidney volume and albuminuria, at standardized follow-up time points, are warranted.

Exposure to Maternal Diabetes Mellitus Causes Renal Dopamine D1 Receptor Dysfunction and Hypertension in Adult Rat Offspring

Epidemiological and experimental studies suggest that maternal diabetes mellitus programs hypertension that is associated with impaired sodium excretion in the adult offspring. However, the underlying mechanisms are not clear. Because dopamine receptor function is involved in the pathogenesis of hypertension, we hypothesized that impaired renal dopamine D1 receptor function is also involved in the hypertension in offspring of maternal diabetes mellitus. Maternal diabetes mellitus was induced by a single intraperitoneal injection of streptozotocin (35 mg/kg) to pregnant Sprague-Dawley rats at day 0 of gestation. Compared with the offspring of mothers injected with citrate buffer (control mother offspring), the diabetic mother offspring (DMO) had increased systolic blood pressure and impaired D1 receptor-mediated diuresis and natriuresis, accompanied by increased renal PKC (protein kinase C) expression and activity, GRK-2 (G protein-coupled receptor kinase-2) expression, D1 receptor phosphorylation, D1 receptor/Gαs uncoupling, and loss of D1 receptor-mediated inhibition of Na+-K+-ATPase activity in renal proximal tubule cells from DMO. Inhibition of PKC reduced the increased GRK-2 expression and normalized D1 receptor function in primary cultures of renal proximal tubule cells from DMO. In addition, DMO, relative to control mother offspring, in vivo, had increased oxidative stress, indicated by decreased renal glutathione and increased renal malondialdehyde and urine 8-isoprostane. Normalization of oxidative stress with tempol also normalized the renal D1 receptor phosphorylation, D1 receptor-mediated diuresis and natriuresis, and blood pressure in DMO. Our present study indicates that maternal diabetes mellitus-programed hypertension in the offspring is caused by impaired renal D1 receptor function because of oxidative stress that is mediated by increased PKC-GRK-2 activity.

Transgenerational programming of nephron deficits and hypertension

Exposure to a sub-optimal environment in the womb can result in poor fetal growth and impair the normal development of organs. The kidney, specifically the process of nephrogenesis, has been shown to be impacted by many common pregnancy exposures including an inadequate diet, poor placental function, maternal stress as well as maternal smoking and alcohol consumption. This can result in offspring being born with a reduced nephron endowment, which places these individuals at increased risk of hypertension and chronic kidney disease (CKD). Of recent interest is whether this disease risk can be passed on to subsequent generations and, if so, what are the mechanisms and pathways involved. In this review, we highlight the growing body of evidence that a low birth weight and hypertension, which are both major risk factors for cardiovascular and CKD, can be transmitted across generations. However, as yet there is little data as to whether a low nephron endowment contributes to this disease transmission. The emerging data suggests transmission can occur both through both the maternal and paternal lines, which likely involves epigenetic mechanisms such chromatin remodelling (DNA methylation and histone modification) and non-coding RNA modifications. In addition, females who were born small and/or have a low nephron endowment are at an increased risk for pregnancy complications, which can influence the growth and development of the next generation. Future animal studies in this area should include examining nephron endowment across multiple generations and determining adult renal function. Clinically, long term follow-up studies of large birth cohorts need to be undertaken to more clearly determine the impact a sub-optimal environment in one generation has on the health outcomes in the second, and subsequent, generation.

Developmental Programming of Renal Function and Re-Programming Approaches

Chronic kidney disease affects more than 10% of the population. Programming studies have examined the interrelationship between environmental factors in early life and differences in morbidity and mortality between individuals. A number of important principles has been identified, namely permanent structural modifications of organs and cells, long-lasting adjustments of endocrine regulatory circuits, as well as altered gene transcription. Risk factors include intrauterine deficiencies by disturbed placental function or maternal malnutrition, prematurity, intrauterine and postnatal stress, intrauterine and postnatal overnutrition, as well as dietary dysbalances in postnatal life. This mini-review discusses critical developmental periods and long-term sequelae of renal programming in humans and presents studies examining the underlying mechanisms as well as interventional approaches to "re-program" renal susceptibility toward disease. Clinical manifestations of programmed kidney disease include arterial hypertension, proteinuria, aggravation of inflammatory glomerular disease, and loss of kidney function. Nephron number, regulation of the renin-angiotensin-aldosterone system, renal sodium transport, vasomotor and endothelial function, myogenic response, and tubuloglomerular feedback have been identified as being vulnerable to environmental factors. Oxidative stress levels, metabolic pathways, including insulin, leptin, steroids, and arachidonic acid, DNA methylation, and histone configuration may be significantly altered by adverse environmental conditions. Studies on re-programming interventions focused on dietary or anti-oxidative approaches so far. Further studies that broaden our understanding of renal programming mechanisms are needed to ultimately develop preventive strategies. Targeted re-programming interventions in animal models focusing on known mechanisms will contribute to new concepts which finally will have to be translated to human application. Early nutritional concepts with specific modifications in macro- or micronutrients are among the most promising approaches to improve future renal health.

Effects of bisphenol A treatment during pregnancy on kidney development in mice: a stereological and histopathological study

Bisphenol A (BPA) is a chemical found in plastics that resembles oestrogen in organisms. Developmental exposure to endocrine-disrupting chemicals, such as BPA, increases the susceptibility to type 2 diabetes (T2DM) and cardiovascular diseases. Animal studies have reported a nephron deficit in offspring exposed to maternal diabetes. The aim of this study was to investigate the prenatal BPA exposure effects on nephrogenesis in a mouse model that was predisposed to T2DM. This study quantitatively evaluated the renal structural changes using stereology and histomorphometry methods. The OF1 pregnant mice were treated with a vehicle or BPA (10 or 100 μg/kg/day) during days 9-16 of gestation (early nephrogenesis). The 30-day-old offspring were sacrificed, and tissue samples were collected and prepared for histopathological and stereology studies. Glomerular abnormalities and reduced glomerular formation were observed in the BPA offspring. The kidneys of the BPA10 and BPA100 female offspring had a significantly lower glomerular number and density than those of the CONTROL female offspring. The glomerular histomorphometry revealed a significant difference between the female and male CONTROL offspring for the analysed glomerular parameters that disappeared in the BPA10 and BPA100 offspring. In addition, the kidney histopathological examination showed typical male cuboidal epithelial cells of the Bowman capsule in the female BPA offspring. Exposure to environmentally relevant doses of BPA during embryonic development altered nephrogenesis. These structural changes could be associated with an increased risk of developing cardiometabolic diseases later in life.

Maternal glucose intolerance reduces offspring nephron endowment and increases glomerular volume in adult offspring

BACKGROUND

Animal studies report a nephron deficit in offspring exposed to maternal diabetes, yet are limited to models of severe hyperglycaemia which do not reflect the typical clinical condition and which are associated with foetal growth restriction that may confound nephron endowment. We aimed to assess renal morphology and function in offspring of leptin receptor deficient mice (Lepr^db /+) and hypothesized that exposure to impaired maternal glucose tolerance (IGT) would be detrimental to the developing kidney.

METHODS

Nephron endowment was assessed in offspring of C57BKS/J Lepr^db /+ and +/+ mice at embryonic day (E)18 and postnatal day (PN)21 using design-based stereology. Transcutaneous measurement of renal function and total glomerular volume were assessed in 6-month-old offspring. Only +/+ offspring of Lepr^db /+ dams were analysed.

RESULTS

Compared with +/+ dams, Lepr^db /+ dams had a 20% and 35% decrease in glucose tolerance prior to pregnancy and at E17.5 respectively. Offspring of IGT Lepr^db /+ dams had approximately 15% fewer nephrons at E18.5 and PN21 than offspring of +/+ dams. There was no difference in offspring bodyweight. Despite normal renal function, total glomerular volume was 13% greater in 6-month-old offspring of IGT Lepr^db /+ dams than in +/+ offspring.

CONCLUSIONS

IGT throughout gestation resulted in a nephron deficit that was established early in renal development. Maternal IGT was associated with glomerular hypertrophy in adult offspring, likely a compensatory response to maintain normal renal function. Given the increasing prevalence of IGT, monitoring glucose from early in gestation may be important to prevent altered kidney morphology. Copyright © 2016 John Wiley & Sons, Ltd.

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.

Morphofunctional renal alterations in rats induced by intrauterine hyperglycemic environment

INTRODUCTION

The renal development of rats begins in intrauterine life, finishing by 15 days after birth. Diabetes and other diseases during pregnancy can cause systemic changes in the offspring. We evaluated the structural and functional renal alterations of the offspring from diabetic mothers.

MATERIAL AND METHODS

Pregnant rats were separated and 1, 7, 30 and 90 days-old (DO) pups were divided into groups according to the treatment that the mothers received: G1: control, G2: untreated diabetic and G3: insulin-treated diabetic. The kidneys from offspring at 1, 7 and 30 DO were removed for immunohistochemical and histological studies. Furthermore, blood and urine samples were collected from animals at 30 DO to determine the glomerular filtration rate (GFR) by creatinine clearance, and the animals at 90 DO were subjected to blood pressure measurement by plethysmography.

RESULTS

Our results show an increase of PCNA(+) glomerular cells at 7 DO and a reduction in 30 DO animals as well as increased α-smooth muscle actin (α-SMA) tubulointerstitial expression at 1 and 7 DO in animals from G2, when compared with controls. The adult offspring from G2 showed reduced GFR and increased blood pressure.

CONCLUSIONS

Maternal diabetes may have induced programming of renal damage in offspring of hyperglycemic mothers, which may have contributed to the impairment of renal function.

Post-weaning high-fat diet accelerates kidney injury, but not hypertension programmed by maternal diabetes

BACKGROUND

The aim of this study was to establish the underlying mechanisms by which a post-weaning high-fat diet (HFD) accelerates the perinatal programming of kidney injury occurring in the offspring of diabetic mothers.

METHODS

Male mice, offspring of nondiabetic and diabetic dams were fed with normal diet (ND) or HFD from 4 to 20 wk of age. Rat renal proximal tubular cells were used in vitro.

RESULTS

On ND, the offspring of dams with severe maternal diabetes had an intrauterine growth restriction (IUGR) phenotype and developed mild hypertension and evidence of kidney injury in adulthood. Exposing the IUGR offspring to HFD resulted in rapid weight gain, catch-up growth, and later to profound kidney injury with activation of renal TGFβ1 and collagen type IV expression, increased oxidative stress, and enhanced renal lipid deposition, but not systemic hypertension. Given our data, we speculate that HFD or free fatty acids may accelerate the process of perinatal programming of kidney injury, via increased CD36 and fatty acid-binding protein 4 expression, which may target reactive oxygen species, nuclear factor-kappa B, and TGFβ1 signaling in vivo and in vitro.

CONCLUSION

Early postnatal exposure to overnutrition with a HFD increases the risk of development of kidney injury, but not hypertension, in IUGR offspring of dams with maternal diabetes.

Proteomic analyses of Urine Exosomes reveal New Biomarkers of Diabetes in Pregnancy

Objective

To evaluate 24 hour urine exosome protein content changes among pregnant US subjects with diabetes and obesity during early pregnancy.

Methods

The exosome proteome content from 24 hour urine samples of pregnant subjects with gestational diabetes mellitus (GDM, N=8) and pre-gestational Type 2 diabetes (PGD, N = 10) were compared with control samples (CTRL, N = 10) obtained at week 20 of pregnancy. Differences in exosome protein load between groups was identified by liquid chromatography/mass spectrometry, analyzed by linear regression in negative binomial distribution, visualized in MetaboAnalyst (version 3.0), and validated by western immunoblotting.

Results

At the 20^th week of pregnancy, we identified 646, 734 and 856 proteins in exosomes from 24 hour urine samples of patients from the CTRL, GDM and PGD groups, respectively. S100 calcium binding protein A9, damage associated molecular pattern (DAMP) signal, was found to be significantly increased in both GDM and PGD subjects. In GDM subjects the peptide counts for S100A9 protein independently correlated with maternal obesity and macrosomia of the newborn infants. Early to late pregnancy developmental changes in the GDM group were shown to utilize pathways and protein expression levels differently from those in PGD or CTRL groups.

Conclusions

Urinary exosome proteomic analysis non-invasively provides insights into maternal changes during diabetic pregnancy. Exosome biomarkers early in pregnancy can be potentially used to better understand pathophysiologic mechanisms of diabetes at a cellular level, and to distinguish between gestational and pre-gestational diabetes at the pathway level. This information can aid intervention efforts to improve pregnancy outcomes in women with diabetes.

Heart rate variability in neonates of type 1 diabetic pregnancy

BACKGROUND

Cardiomyopathy is a common finding in offspring of pre-gestational type 1 diabetic pregnancy. Echocardiographic and biochemical evidence of fetal cardiac dysfunction have also been reported. Studies suggest that offspring of diabetic mothers (ODM) undergo a fetal programming effect due to the hyperglycaemic intrauterine milieu which increases their risk of cardiovascular morbidity in adult life. Decreased neonatal heart rate variability (HRV) has been described in association with in-utero growth restriction, prematurity, sudden infant death syndrome and congenital heart disease. The effect of in-utero exposure to hyperglycaemia in diabetic pregnancy on neonatal HRV is unknown.

AIMS

Our aim was to determine if neonatal HRV differs between normal and diabetic pregnancy.

STUDY DESIGN AND SUBJECTS

This was a prospective observational study of 38 patients with pregestational type 1 diabetes and 26 controls. HRV assessment was performed using Powerlab (ADI Instruments Ltd).

OUTCOME MEASURES

Heart rate variability assessment and cord blood sampling for pH and glucose were performed for all neonates. Maternal glycaemic control was assessed via measurement of glycosylated haemoglobin in each trimester in the diabetic cohort.

RESULTS

Neonates of diabetic mothers had evidence of altered heart rate variability, with increased low frequency to high frequency ratio (LF: HF), suggestive of a shift towards sympathetic predominance (p<0.05). This altered HRV was significantly related to fetal acidaemia, cord blood glucose values and maternal glycaemic control during pregnancy (p<0.05).

CONCLUSION

Neonates of pregestational diabetic pregnancy have altered HRV which is related to maternal hyperglycaemia, fetal acidaemia and fetal glycaemia. Exposure of the developing heart to fluctuations in maternal glycaemia with subsequent alterations in HRV may explain why infants of diabetic mothers are at greater risk of cardiovascular disease in later life.

Alterations in perivascular innervation function in mesenteric arteries from offspring of diabetic rats

BACKGROUND AND PURPOSE

We have reported that exposure to a diabetic intrauterine environment during pregnancy increases blood pressure in adult offspring, but the mechanisms involved are not completely understood. This study was designed to analyse a possible role of perivascular sympathetic and nitrergic innervation in the superior mesenteric artery (SMA) in this effect.

EXPERIMENTAL APPROACH

Diabetes was induced in pregnant Wistar rats by a single injection of streptozotocin. Endothelium-denuded vascular rings from the offspring of control (O-CR) and diabetic rats (O-DR) were used. Vasomotor responses to electrical field stimulation (EFS), NA and the NO donor DEA-NO were studied. The expressions of neuronal NOS (nNOS) and phospho-nNOS (P-nNOS) and release of NA, ATP and NO were determined. Sympathetic and nitrergic nerve densities were analysed by immunofluorescence.

KEY RESULTS

Blood pressure was higher in O-DR animals. EFS-induced vasoconstriction was greater in O-DR animals. This response was decreased by phentolamine more in O-DR animals than their controls. L-NAME increased EFS-induced vasoconstriction more strongly in O-DR than in O-CR segments. Vasomotor responses to NA or DEA-NO were not modified. NA, ATP and NO release was increased in segments from O-DR. nNOS expression was not modified, whereas P-nNOS expression was increased in O-DR. Sympathetic and nitrergic nerve densities were similar in both experimental groups.

CONCLUSIONS AND IMPLICATIONS

The activity of sympathetic and nitrergic innervation is increased in SMA from O-DR animals. The net effect is an increase in EFS-induced contractions in these animals. These effects may contribute to the increased blood pressure observed in the offspring of diabetic rats.

Long-term renal consequences of preterm birth

The normal development of the kidney may be affected by several factors, including abnormalities in placental function, resulting in fetal growth restriction, exposure to maternal disease states, including hypertension and diabetes, antenatal steroids, chorioamnionitis, and preterm delivery. After preterm birth, several further insults may occur that may influence nephrogenesis and renal health, including exposure to nephrotoxic medications, postnatal growth failure, and obesity after growth restriction. In this review article, common clinical neonatal scenarios are used to highlight these renal risk factors, and the animal and human evidence on which these risk factors are based are discussed.

Renal echo-3D and microalbuminuria in children of diabetic mothers: a preliminary study

Maternal diabetes has assumed epidemic relevance in recent years and animal studies have provided some evidence that it may cause abnormalities in renal development and a reduction in nephron endowment in the offspring; however, human data are lacking. The renal cortex contains ∼95% of the glomeruli and its volume could be taken as a surrogate measure of glomerular number; based on this assumption, we measured renal cortex volume and in addition, microalbuminuria in a homogeneous sample of 42 children of diabetic (pregestational, n = 13, and gestational, n = 29) mothers, compared with 21 healthy children born of non-diabetic mothers. The offspring of diabetic mothers showed a significant reduction of renal cortex volume and higher albumin excretion compared with controls, possibly attributable to a reduction in the number of nephrons and the difference was statistically significant (P < 0.001). Although further studies on a larger sample are necessary, our preliminary findings suggest that maternal diabetes may affect renal development with sequelae later in life, requiring closer monitoring and follow-up. Furthermore, the importance of strict maternal diabetes management and control must be emphasized.

Developmental programming: variations in early growth and adult disease

Suboptimal conditions in utero are associated with the development of adult-onset diseases in offspring. Uteroplacental insufficiency in rats is a well-established animal model used to mimic and study the effects of developmental insults relevant to countries of abundant nutrient supply. However, wide-ranging outcomes for the offspring are apparent between the different investigators that use this model and also between cohorts generated in our laboratory. We aimed to explore the reasons for variability in rat models of uteroplacental insufficiency between different investigators and also between our own animal cohorts. We suggest differences in growth and disease development reflect uniqueness in susceptibility and highlight the complexity of interactions between genetic potential and environmental exposures. The impact of adverse exposures in utero has been described as having far-reaching effects that extend well beyond the first, directly exposed generation. However, the resulting phenotypes are not consistent between generations. This suggests that programmed effects are established de novo in each generation and challenges the prediction of disease. Characterization of growth and disease in the numerous rat models has led to our understanding of the impact of early life experiences on adult health. In order to drive the development of preventative and/or treatment strategies, future studies should focus on identifying the initial cause(s) of uteroplacental insufficiency, including genetic origins and the influence of poor diets.

Prenatal risk factors for childhood CKD

Development of CKD may be programmed prenatally. We sought to determine the association of childhood CKD with prenatal risk factors, including birth weight, maternal diabetes mellitus (DM), and maternal overweight/obesity. We conducted a population-based, case-control study with 1994 patients with childhood CKD (<21 years of age at diagnosis) and 20,032 controls in Washington state. We linked maternal and infant characteristics in birth records from 1987 to 2008 to hospital discharge data and used logistic regression analysis to assess the association of prenatal risk factors with childhood CKD. The prevalence of CKD was 126.7 cases per 100,000 births. High birth weight and maternal pregestational DM associated nominally with CKD, with respective crude odds ratios (ORs) of 1.17 (95% confidence interval [95% CI], 1.03 to 1.34) and 1.97 (95% CI, 1.15 to 3.37); however, adjustment for maternal confounders attenuated these associations to 0.97 (95% CI, 0.79 to 1.21) and 1.19 (95% CI, 0.51 to 2.81), respectively. The adjusted ORs for CKD associated with other prenatal factors were 2.88 (95% CI, 2.28 to 3.63) for low birth weight, 1.54 (95% CI, 1.13 to 2.09) for maternal gestational DM, 1.24 (95% CI, 1.05 to 1.48) for maternal overweight, and 1.26 (95% CI, 1.05 to 1.52) for maternal obesity. In subgroup analysis by CKD subtype, low birth weight and maternal pregestational DM associated significantly with increased risk of renal dysplasia/aplasia. Low birth weight, maternal gestational DM, and maternal overweight/obesity associated significantly with obstructive uropathy. These data suggest that prenatal factors may impact the risk of CKD. Future studies should aim to determine if modification of these factors could reduce the risk of childhood CKD.

Influence of abnormally high leptin levels during pregnancy on metabolic phenotypes in progeny mice

Maternal obesity increases the risk of obesity in offspring, and obesity is accompanied by an increase in blood leptin levels. The "yellow" mutation at the mouse agouti locus (A(y)) increases blood leptin levels in C57BL preobese pregnant mice without affecting other metabolic characteristics. We investigated the influence of the A(y) mutation or leptin injection at the end of pregnancy in C57BL mice on metabolic phenotypes and the susceptibility to diet-induced obesity (DIO) in offspring. In both C57BL-A(y) and leptin-treated mice, the maternal effect was more pronounced in male offspring. Compared with males born to control mothers, males born to A(y) mothers displayed equal food intake (FI) but decreased body weight (BW) gain after weaning, equal glucose tolerance, and enhanced FI-to-BW ratios on the standard diet but the same FI and BW on the high-fat diet. Males born to A(y) mothers were less responsive to the anorectic effect of exogenous leptin and less resistant to fasting (were not hyperphagic and gained less weight during refeeding after food deprivation) compared with males born to control mothers. However, all progeny displayed equal hypothalamic expression of Agouti gene-related protein (AgRP), neuropeptide Y (NPY), and proopiomelanocortin (POMC) and equal plasma leptin and glucose levels after food deprivation. Leptin injections in C57BL mice on day 17 of pregnancy decreased BW in both male and female offspring but inhibited FI and DIO only in male offspring. Our results show that hyperleptinemia during pregnancy has sex-specific long-term effects on energy balance regulation in progeny and does not predispose offspring to developing obesity.

Transgenerational metabolic outcomes associated with uteroplacental insufficiency

Intrauterine growth restriction increases adult metabolic disease risk with evidence to suggest that suboptimal conditions in utero can have transgenerational effects. We determined whether impaired glucose tolerance, reduced insulin secretion, and pancreatic deficits are evident in second-generation (F2) male and female offspring from growth-restricted mothers, in a rat model of uteroplacental insufficiency. Late gestation uteroplacental insufficiency was induced by bilateral uterine vessel ligation (restricted) or sham surgery (control) in Wistar-Kyoto rats. First-generation (F1) control and restricted females were mated with normal males and F2 offspring studied at postnatal day 35 and at 6 and 12 months. F2 glucose tolerance, insulin secretion, and sensitivity were assessed at 6 and 12 months and pancreatic morphology was quantified at all study ages. At 6 months, F2 restricted male offspring exhibited blunted first-phase insulin response (-35%), which was associated with reduced pancreatic β-cell mass (-29%). By contrast, F2 restricted females had increased β-cell mass despite reduced first-phase insulin response (-38%). This was not associated with any changes in plasma estradiol concentrations. Regardless of maternal birth weight, F2 control and restricted males had reduced homeostatic model assessment of insulin resistance and elevated plasma triglyceride concentrations at 6 months and reduced whole-body insulin sensitivity at 6 and 12 months compared with females. We report that low maternal birth weight is associated with reduced first-phase insulin response and gender-specific differences in pancreatic morphology in the F2. Further studies will define the mode(s) of disease transmission, including direct insults to developing gametes, adverse maternal responses to pregnancy, or inherited mechanisms.

Altered ureteric branching morphogenesis and nephron endowment in offspring of diabetic and insulin-treated pregnancy

There is strong evidence from human and animal models that exposure to maternal hyperglycemia during in utero development can detrimentally affect fetal kidney development. Notwithstanding this knowledge, the precise effects of diabetic pregnancy on the key processes of kidney development are unclear due to a paucity of studies and limitations in previously used methodologies. The purpose of the present study was to elucidate the effects of hyperglycemia on ureteric branching morphogenesis and nephrogenesis using unbiased techniques. Diabetes was induced in pregnant C57Bl/6J mice using multiple doses of streptozotocin (STZ) on embryonic days (E) 6.5-8.5. Branching morphogenesis was quantified ex vivo using Optical Projection Tomography, and nephrons were counted using unbiased stereology. Maternal hyperglycemia was recognised from E12.5. At E14.5, offspring of diabetic mice demonstrated fetal growth restriction and a marked deficit in ureteric tip number (control 283.7±23.3 vs. STZ 153.2±24.6, mean±SEM, p<0.01) and ureteric tree length (control 33.1±2.6 mm vs. STZ 17.6±2.7 mm, p = 0.001) vs. controls. At E18.5, fetal growth restriction was still present in offspring of STZ dams and a deficit in nephron endowment was observed (control 1246.2±64.9 vs. STZ 822.4±74.0, p<0.001). Kidney malformations in the form of duplex ureter and hydroureter were a common observation (26%) in embryos of diabetic pregnancy compared with controls (0%). Maternal insulin treatment from E13.5 normalised maternal glycaemia but did not normalise fetal weight nor prevent the nephron deficit. The detrimental effect of hyperglycemia on ureteric branching morphogenesis and, in turn, nephron endowment in the growth-restricted fetus highlights the importance of glycemic control in early gestation and during the initial stages of renal development.

Increased renal sympathetic nerve activity leads to hypertension and renal dysfunction in offspring from diabetic mothers

The exposure of the fetus to a hyperglycemic environment promotes the development of hypertension and renal dysfunction in the offspring at adult age. We evaluated the role of renal nerves in the hypertension and renal changes seen in offspring of diabetic rats. Diabetes was induced in female Wistar rats (streptozotocin, 60 mg/kg ip) before mating. Male offspring from control and diabetic dams were studied at an age of 3 mo. Systolic blood pressure measured by tail cuff was increased in offspring of diabetic dams (146 ± 1.6 mmHg, n = 19, compared with 117 ± 1.4 mmHg, n = 18, in controls). Renal function, baseline renal sympathetic nerve activity (rSNA), and arterial baroreceptor control of rSNA were analyzed in anesthetized animals. Glomerular filtration rate, fractional sodium excretion, and urine flow were significantly reduced in offspring of diabetic dams. Two weeks after renal denervation, blood pressure and renal function in offspring from diabetic dams were similar to control, suggesting that renal nerves contribute to sodium retention in offspring from diabetic dams. Moreover, basal rSNA was increased in offspring from diabetic dams, and baroreceptor control of rSNA was impaired, with blunted responses to infusion of nitroprusside and phenylephrine. Thus, data from this study indicate that in offspring from diabetic mothers, renal nerves have a clear role in the etiology of hypertension; however, other factors may also contribute to this condition.

Effect of age and COX-2-derived prostanoids on the progression of adult vascular dysfunction in the offspring of diabetic rats

BACKGROUND AND PURPOSE

The present study was designed to determine how diabetes in pregnancy affects vascular function in their offspring, the influence of age and whether COX activation is involved in this effect.

EXPERIMENTAL APPROACH

Relaxation responses to ACh were analysed in mesenteric resistance arteries from the offspring of control rats (O-CR) and those of diabetic rats (O-DR) at 3, 6 and 12 months of age. TxB₂, PGE₂ and PGF(2α) release were determined by enzyme immunoassay. COX-1 and COX-2 expression were measured by Western blot analysis.

KEY RESULTS

O-DR developed hypertension from 6 months of age compared with O-CR. In O-DR, relaxation responses to ACh were impaired in all ages studied and were restored by COX-2 inhibition. TP receptor blockade (SQ29548) restored ACh relaxation in arteries from 3-month-old O-DR while TP and EP receptor blockade (SQ29548 + AH6809) was required to restore it in 6-month-old O-DR. In 12-month-old O-DR, ACh relaxation was restored when TP, EP and FP receptors were blocked (SQ29548 + AH6809 + AL8810). ACh-stimulated TxB₂ was higher in all O-DR. ACh-stimulated PGE₂ release was increased in arteries from 6- and 12-month-old O-DR, whereas PGF(2α) was increased only in 12-month-old O-DR. COX-2, but not COX-1, expression was higher in O-DR than O-CR.

CONCLUSIONS AND IMPLICATIONS

The results indicate an age-dependent up-regulation of COX-2 coupled to an enhanced formation of vasoconstrictor prostanoids in resistance arteries from O-DR. This effect plays a key role in the pathogenesis of endothelial dysfunction, which in turn could contribute to the progression of vascular dysfunction in these rats.

Increased cyclooxygenase-2-derived prostanoids contributes to the hyperreactivity to noradrenaline in mesenteric resistance arteries from offspring of diabetic rats

This study analyzed the effect of in utero exposure to maternal diabetes on contraction to noradrenaline in mesenteric resistance arteries (MRA) from adult offspring, focusing on the role of cyclooxygenase (COX)-derived prostanoids. Diabetes in the maternal rat was induced by a single injection of streptozotocin (50 mg/kg body weight) on day 7 of pregnancy. Contraction to noradrenaline was analyzed in isolated MRA from offspring of diabetic (O-DR) and non-diabetic (O-CR) rats at 3, 6 and 12 months of age. Release of thromboxane A₂ (TxA₂) and prostaglandins E₂ (PGE₂) and F_2α (PGF_2α), was measured by specific enzyme immunoassay kits. O-DR developed hypertension from 6 months of age compared with O-CR. Arteries from O-DR were hyperactive to noradrenaline only at 6 and 12 months of age. Endothelial removal abolished this hyperreactivity to noradrenaline between O-CR and O-DR. Preincubation with either the COX-1/2 (indomethacin) or COX-2 inhibitor (NS-398) decreased noradrenaline contraction only in 6- and 12-month-old O-DR, while it remained unmodified by COX-1 inhibitor SC-560. In vessels from 6-month-old O-DR, a similar reduction in the contraction to noradrenaline produced by NS-398 was observed when TP and EP receptors were blocked (SQ29548+AH6809). In 12-month-old O-DR, this effect was only achieved when TP, EP and FP were blocked (SQ29548+AH6809+AL8810). Noradrenaline-stimulated TxB₂ and PGE₂ release was higher in 6- and 12-month-old O-DR, whereas PGF_2α was increased only in 12-month-old O-DR. Our results demonstrated that in utero exposure to maternal hyperglycaemia in rats increases the participation of COX-2-derived prostanoids on contraction to noradrenaline, which might help to explain the greater response to this agonist in MRA from 6- and 12-month-old offspring. As increased contractile response in resistance vessels may contribute to hypertension, our results suggest a role for these COX-2-derived prostanoids in elevating vascular resistance and blood pressure in offspring of diabetic rats.

Catalase prevents maternal diabetes-induced perinatal programming via the Nrf2-HO-1 defense system

We investigated whether overexpression of catalase (CAT) in renal proximal tubular cells (RPTCs) could prevent the programming of hypertension and kidney disease in the offspring of dams with maternal diabetes. Male offspring of nondiabetic and diabetic dams from two transgenic (Tg) lines (Hoxb7-green fluorescent protein [GFP]-Tg [controls] and Hoxb7/CAT-GFP-Tg, which overexpress CAT in RPTCs) were studied from the prenatal period into adulthood. Nephrogenesis, systolic blood pressure, renal hyperfiltration, kidney injury, and reactive oxygen species (ROS) generation were assessed. Gene expression of transforming growth factor-β1 (TGF-β1), nuclear factor erythroid 2p45-related factor-2 (Nrf2), and heme oxygenase-1 (HO-1) was tested in both in vitro and in vivo studies. Renal dysmorphogenesis was observed in offspring of Hoxb7-GFP-Tg dams with severe maternal diabetes; the affected male offspring displayed higher renal ROS generation and developed hypertension and renal hyperfiltration as well as renal injury with heightened TGF-β1 expression in adulthood. These changes were ameliorated in male offspring of diabetic Hoxb7/CAT-GFP-Tg dams via the Nrf2-HO-1 defense system. CAT promoted Nrf2 nuclear translocation and HO-1 gene expression, seen in both in vitro and in vivo studies. In conclusion, CAT overexpression in the RPTCs ameliorated maternal diabetes-induced perinatal programming, mediated, at least in part, by triggering the Nrf2-HO-1 defense system.

Long-term health outcomes in children born to mothers with diabetes: a population-based cohort study

BACKGROUND

To examine whether prenatal exposure to parental type 1 diabetes, type 2 diabetes, or gestational diabetes is associated with an increased risk of malignant neoplasm or diseases of the circulatory system in the offspring.

METHODS/PRINCIPAL FINDINGS

We conducted a population-based cohort study of 1,781,576 singletons born in Denmark from 1977 to 2008. Children were followed for up to 30 years from the day of birth until the onset of the outcomes under study, death, emigration, or December 31, 2009, whichever came first. We used Cox proportional hazards model to estimate hazard ratios (HR) with 95% confidence intervals (95% CI) for the outcomes under study while adjusting for potential confounders. An increased risk of malignant neoplasm was found in children prenatally exposed to maternal type 2 diabetes (HR = 2.2, 95%CI: 1.5-3.2). An increased risk of diseases of the circulatory system was found in children exposed to maternal type 1 diabetes (HR = 2.2, 95%CI: 1.6-3.0), type 2 diabetes (HR = 1.4, 95%CI: 1.1-1.7), and gestational diabetes (HR = 1.3, 95%CI: 1.1-1.6), but results were attenuated after excluding children with congenital malformations. An increased risk of diseases of the circulatory system was also found in children exposed to paternal type 2 diabetes (HR = 1.5, 95%CI: 1.1-2.2) and the elevated risk remained after excluding children with congenital malformations.

CONCLUSIONS

This study suggests that susceptibility to malignant neoplasm is modified partly by fetal programming. Diseases of the circulatory system may be modified by genetic factors, other time-stable family factors, or fetal programming.

Maternal adaptations and inheritance in the transgenerational programming of adult disease

Adverse exposures in utero have long been linked with an increased susceptibility to adult cardio-renal and metabolic diseases. Clear gender differences exist, whereby growth-restricted females, although exhibiting some phenotypic modifications, are often protected from overt disease outcomes. One of the greatest physiological challenges facing the female gender, however, is that of pregnancy; yet little research has focused on the outcomes associated with this, as a potential 'second-hit' for those who were small at birth. We review the limited evidence suggesting that pregnancy may unmask cardio-renal and metabolic disease states and the consequences for long-term maternal health in females who were born small. Additionally, a growing area of research in this programming field is in the transgenerational transmission of low birth weight and disease susceptibility. Pathways for transmission might include an abnormal adaptation to pregnancy by the growth-restricted mother and/or inheritance via the parental germline. Strategies to optimise the pregnancy environment and/or prevent the consequences of inheritance of programmed deficits and dysfunction are of critical importance for future generations.

Fetal programming of renal function

Results from large epidemiological studies suggest a clear relation between low birth weight and adverse renal outcome evident as early as during childhood. Such adverse outcomes may include glomerular disease, hypertension, and renal failure and contribute to a phenomenon called fetal programming. Other factors potentially leading to an adverse renal outcome following fetal programming are maternal diabetes mellitus, smoking, salt overload, and use of glucocorticoids during pregnancy. However, clinical data on the latter are scarce. Here, we discuss potential underlying mechanisms of fetal programming, including reduced nephron number via diminished nephrogenesis and other renal (e.g., via the intrarenal renin-angiotensin-aldosterone system) and non-renal (e.g., changes in endothelial function) alterations. It appears likely that the outcomes of fetal programming may be influenced or modified postnatally, for example, by the amount of nutrients given at critical times.

Safety in glomerular numbers

A low nephron number is, according to Brenner's hyperfiltration hypothesis, associated with hypertension, glomerular damage and proteinuria, and starts a vicious cycle that ends in renal failure over the long term. Nephron endowment is set during foetal life, and there is no formation of nephrons after 34-36 weeks of gestation, indicating that many factors before that time-point may have an impact on kidney development and reduce nephron numbers. Such factors include maternal malnutrition, stress, diseases, such as diabetes, uteroplacental insufficiency, maternal and neonatal drugs and premature birth. However, other congenital anomalies, such as renal hypoplasia, unilateral renal agenesis or multicystic dysplastic kidney, may also lead to a reduced nephron endowment, with an increased risk for hypertension, renal dysfunction and the need for renal replacement therapy. This review focuses on the causes and consequences of a low nephron endowment and will illustrate why there is safety in glomerular numbers.

Prenatally programmed hypertension: role of maternal diabetes

Epidemiological and experimental studies have led to the hypothesis of the fetal origin of adult diseases, suggesting that some adult diseases might be determined before birth by altered fetal development. Maternal diabetes subjects the fetus to an adverse environment that has been demonstrated to result in metabolic, cardiovascular and renal impairment in the offspring. The growing amount of obesity in young females in developed and some developing countries should contribute to increasing the incidence of diabetes among pregnant women. In this review, we discuss how renal and extrarenal mechanisms participate in the genesis of hypertension induced by a diabetic status during fetal development.