The role of the kidney in regulating arterial blood pressure

Placental epigenetic age and adolescent blood pressure: the Extremely Low Gestational Age Newborn cohort

BACKGROUND

We examined the association between placental epigenetic gestational age (eGA) acceleration and adolescent systolic blood pressure (SBP) in a cohort born extremely preterm.

METHODS

Study participants were a subset of the Extremely Low Gestational Age Newborn cohort (born <28 weeks' gestation) who had placental DNA methylation quantified and had SBP measured during adolescent follow-up. eGA acceleration was calculated as the residual from the regression of predicted placental eGA (using the Robust Placental Clock) onto chronological gestational age. Unadjusted and adjusted mixed effects models were used to test the association between eGA acceleration and adolescent SBP. We also tested the interaction of eGA acceleration and sex on SBP.

RESULTS

In the overall sample (N = 193), we found no association between placental eGA acceleration and adolescent SBP. When interaction between eGA acceleration and sex was tested, males had a 3.6 mmHg increase in SBP (95% CI 0.9, 6.4; p = 0.01) for every 1-week acceleration in eGA after adjusting for confounders.

CONCLUSION

Placental eGA acceleration is associated with SBP increase in adolescent males but not females born extremely preterm, supporting the hypothesis that placental eGA could be evaluated as a risk biomarker for childhood cardiovascular outcomes.

IMPACT

This study examines the association between placental epigenetic gestational age (eGA) and adolescent blood pressure. For every 1-week acceleration in placental eGA, adolescent males born extremely preterm had a 3.6 mmHg increase in systolic blood pressure (95% CI 0.9, 6.4; p = 0.01) after adjusting for confounders. The same association was not seen in females or the overall cohort. Our sex-specific finding supports the hypothesis that differences in placental eGA are associated with childhood health. Placental eGA estimation as a tool for identifying children who are at risk for developing elevated blood pressure should be further evaluated in other cohorts.

Chromatin State Maps of Blood Pressure-Relevant Renal Segments Reveal Potential Regulatory Role for SNPs

BACKGROUND

Hypertension or elevated blood pressure (BP) is a worldwide clinical challenge and the leading primary risk factor for kidney dysfunctions, heart failure, and cerebrovascular disease. The kidney is a central regulator of BP by maintaining sodium-water balance. Multiple genome-wide association studies revealed that BP is a heritable quantitative trait, modulated by several genetic, epigenetic, and environmental factors. The SNPs identified in genome-wide association studies predominantly (>95%) reside within noncoding genomic regions, making it difficult to understand how they regulate BP. Given the central role of the kidney in regulating BP, we hypothesized that chromatin-accessible regions in renal tissue would be enriched for BP-associated single nucleotide polymorphisms.

METHODS

We manually dissected 2 important kidney segments that maintain the sodium-water balance: proximal tubules and medullary thick ascending limbs from the human and rat kidneys. To delineate their chromatin and transcriptomic profiles, we performed the assay for transposase-accessible chromatin and RNA sequencing, respectively.

RESULTS

The chromatin accessibility maps revealed the shared and unique cis-regulatory elements that modulate the chromatin accessibility in proximal tubule and medullary thick ascending limbs of humans and rats. We developed a visualization tool to compare the cross-species epigenomic maps to identify potential regulatory targets for hypertension pathogenesis. We also identified a significant enrichment of BP-associated single nucleotide polymorphisms (1064 for human proximal tubule and 1172 for human medullary thick ascending limbs) within accessible chromatin regions of both segments, including rs1173771 and rs1421811 at the NPR3 locus and rs1800470 at the TGFb1 locus.

CONCLUSIONS

Collectively, this study lays a foundation for interrogating how intergenic single nucleotide polymorphisms may regulate polygenic traits such as BP.

Implantable Biosensors for Vascular Diseases: Directions for the Next Generation of Active Diagnostic and Therapeutic Medical Device Technologies

Cardiovascular disease remains the leading cause of morbidity and mortality worldwide. Key challenges such as atherosclerosis, in-stent restenosis, and maintaining arteriovenous access, pose urgent problems for effective treatments for both coronary artery disease and chronic kidney disease. The next generation of active implantables will offer innovative solutions and research opportunities to reduce the economic and human cost of disease. Current treatments rely on vascular stents or synthetic implantable grafts to treat vessels when they block such as through in-stent restenosis and haemodialysis graft failure. This is often driven by vascular cell overgrowth termed neointimal hyperplasia, often in response to inflammation and injury. The integration of biosensors into existing approved implants will bring a revolution in cardiovascular devices and into a promising new era. Biosensors that allow real-time vascular monitoring will provide early detection and warning of pathological cell growth. This will enable proactive wireless treatment outside of the traditional hospital settings. Ongoing research focuses on the development of self-reporting smart cardiovascular devices, which have shown promising results using a combination of virtual in silico modelling, bench testing, and preclinical in vivo testing. This innovative approach holds the key to a new generation of wireless data solutions and wireless powered implants to enhance patient outcomes and alleviate the burden on global healthcare budgets.

A Large-Scale Genome-wide Association Study of Blood Pressure Accounting for Gene-Depressive Symptomatology Interactions in 564,680 Individuals from Diverse Populations

Background

Gene-environment interactions may enhance our understanding of hypertension. Our previous study highlighted the importance of considering psychosocial factors in gene discovery for blood pressure (BP) but was limited in statistical power and population diversity. To address these challenges, we conducted a multi-population genome-wide association study (GWAS) of BP accounting for gene-depressive symptomatology (DEPR) interactions in a larger and more diverse sample.

Results

Our study included 564,680 adults aged 18 years or older from 67 cohorts and 4 population backgrounds (African (5%), Asian (7%), European (85%), and Hispanic (3%)). We discovered seven novel gene-DEPR interaction loci for BP traits. These loci mapped to genes implicated in neurogenesis (TGFA, CASP3), lipid metabolism (ACSL1), neuronal apoptosis (CASP3), and synaptic activity (CNTN6, DBI). We also identified evidence for gene-DEPR interaction at nine known BP loci, further suggesting links between mood disturbance and BP regulation. Of the 16 identified loci, 11 loci were derived from African, Asian, or Hispanic populations. Post-GWAS analyses prioritized 36 genes, including genes involved in synaptic functions (DOCK4, MAGI2) and neuronal signaling (CCK, UGDH, SLC01A2). Integrative druggability analyses identified 11 druggable candidate gene targets, including genes implicated in pathways linked to mood disorders as well as gene products targeted by known antihypertensive drugs.

Conclusions

Our findings emphasize the importance of considering gene-DEPR interactions on BP, particularly in non-European populations. Our prioritized genes and druggable targets highlight biological pathways connecting mood disorders and hypertension and suggest opportunities for BP drug repurposing and risk factor prevention, especially in individuals with DEPR.

Identification of Circulating Proteins Associated With Blood Pressure

BACKGROUND

Circulating proteins in blood are involved in various physiological processes, but their contributions to blood pressure regulation remain partially understood. In traditional observational studies, identifying circulating proteins causally associated with blood pressure is challenging because of potentially unmeasured confounding and possible reverse causality.

METHODS

Two-sample Mendelian randomization analyses were conducted to estimate the causal effects of 2270 circulating proteins (data sourced from 8 genome-wide association studies) on diastolic blood pressure, systolic blood pressure, and pulse pressure. Colocalization analyses were then used to investigate whether the circulating proteins and blood pressure traits shared causal genetic variants. To further verify the findings, we subsequently performed Steiger filtering analyses, annotation of protein-altering variants, assessment of overlap between protein quantitative trait loci and expression quantitative trait loci, protein-protein interaction and functional enrichment analyses, and drug target evaluation. To provide more potential biomarkers, we further evaluated the epidemiological associations of 2923 circulating proteins with blood pressure and hypertension by cross-sectional and longitudinal analyses using individual data in the UK Biobank.

RESULTS

Mendelian randomization and colocalization analyses identified 121 circulating proteins with putative causal effects on at least 1 blood pressure trait. Many of the identified proteins are enriched in the pathways relevant to blood pressure regulation, and a majority of these proteins are either known drug targets or druggable candidates.

CONCLUSIONS

This study has uncovered numerous circulating proteins potentially causally associated with blood pressure, providing insights into the regulatory mechanisms of blood pressure and potential therapeutic targets to facilitate blood pressure management.

Clinical implications of mineralocorticoid receptor overactivation

The mineralocorticoid receptor (MR) is a nuclear transcription factor that plays a critical role in regulating fluid, electrolytes, blood pressure, and hemodynamic stability. In conditions such as chronic kidney disease (CKD) and heart failure (HF), MR overactivation leads to increased salt and water retention, inflammatory and fibrotic gene expression, and organ injury. The MR is essential for transcriptional regulation and is implicated in metabolic, proinflammatory, and pro-fibrotic pathways. It is widely expressed in various cell types throughout the body, including the gastrointestinal tract, heart, brain, kidneys, immune cells, and vasculature. Animal studies suggest that MR activation induces oxidative stress in the kidneys and mediates renal inflammation and fibrosis. Immune cell-specific deletion of MR has shown protection against cardiac fibrosis, indicating the MR's role in pathological remodeling. In vascular smooth muscle cells, the MR regulates vascular tone and vasoconstriction. Mineralocorticoid receptor antagonists (MRAs) can be categorized based on their chemical structure as either steroidal or nonsteroidal. Steroidal MRAs (sMRA), such as spironolactone and eplerenone, have demonstrated cardiovascular benefits but are limited by hyperkalemia, gynecomastia, and sexual dysfunction. Nonsteroidal MRAs (nsMRA) have shown promise in preclinical studies and clinical trials. They offer a promising alternative by effectively blocking MR without hormone-like effects, potentially improving cardiovascular and renal disease management. Further education is necessary regarding the significance of MRA utilization in CKD and HF, balancing benefits with the risk of hyperkalemia. This risk could be mitigated by combining MRAs with potassium-binding agents. Studies are underway to explore the synergistic effects between nsMRAs and other agents, such as SGLT-2i inhibitors and Glucagon-like peptide-1 agonists, to optimize cardiorenal outcomes. Overall, MR overactivation remains a significant therapeutic target, with nsMRAs showing promise as pivotal therapies in CKD and HF management. This review highlights the evolving landscape of MR-targeted therapies, their molecular mechanisms, and clinical implications in cardiorenal diseases.

Pharmacological inhibition of the NLRP3 inflammasome attenuates kidney apoptosis, fibrosis, and injury in Dahl salt-sensitive rats

BACKGROUND

Salt-sensitive hypertension (SSH) is the most severe form of hypertension, and the presence of NLRP3 inflammasome plays a crucial role in its pathogenesis. Although MCC950 has shown therapeutic potential for hypertension and kidney injury, its mechanism of action remains unclear.

METHODS

Dahl salt-sensitive (SS) rats and their salt-tolerant aptamer control SS-13BN (BN) rats were randomly assigned to four groups: SS rats intraperitoneally administered physiological saline (SS + vehicle) or MCC950 (SS + MCC950), and BN rats intraperitoneally administered physiological saline (BN + vehicle) or MCC950 (BN + MCC950). All rats were given 2% saline for drinking and received intraperitoneal injections of physiological saline or MCC950 (5 mg/kg) every other day. Biomarkers such as serum creatinine, urinary protein, sodium retention, NLRP3 inflammasome, inflammation, apoptosis, fibrosis, sodium channels and histopathological changes in kidney injury were evaluated in blood, urine, and kidney tissues.

RESULTS

Compared with the SS + vehicle group, the SS + MCC950 group showed significantly lower blood pressure levels. Additionally, inhibition of NLRP3 inflammasome activation was observed along with reduced inflammation, apoptosis, fibrosis, and sodium retention in the kidneys.

CONCLUSIONS

The findings suggest that pharmacological inhibition of the NLRP3 inflammasome reduces blood pressure in SS rats and alleviates related kidney injury by suppressing inflammation, apoptosis, fibrosis, and sodium retention.

Tadalafil pretreatment attenuates doxorubicin-induced hepatorenal toxicity by modulating oxidative stress and inflammation in Wistar rats

Doxorubicin (DOX) is a widely used anticancer agent, but its clinical application is limited by significant off-target hepatorenal toxicity. Tadalafil (TAD), a selective phosphodiesterase-5 inhibitor used mainly for erectile dysfunction and pulmonary arterial hypertension, has shown potential in reducing oxidative stress. This study investigated TAD's chemoprotective effects and underlying mechanisms in DOX-induced hepatorenal toxicity in rats over 12 days. Eight groups of six rats each were orally pretreated with sterile water, silymarin (SIL), or TAD one hour before receiving intraperitoneal injections of 2.5 mg/kg DOX. On the 13th day, the rats were humanely sacrificed under inhaled halothane anesthesia, and serum was collected for hepatic and renal function tests, while liver and kidney tissues were analyzed for antioxidant enzyme activity, pro-inflammatory cytokines assay, and histopathological evaluation. DOX successfully induced hepatorenal toxicity, evidenced by significant increases (p<0.001, p<0.0001) in serum K+, urea, and creatinine levels, along with decreases in HCO3 -, TCa2+, and Cl-. Tissue analysis showed reduced SOD, CAT, GST, and GPx activities, with elevated MDA and GSH levels. TAD pretreatment significantly ameliorated these biochemical alterations (p<0.05, p<0.001, p<0.0001), suggesting its potential as an effective chemoprophylactic adjuvant in the development of DOX-induced hepatorenal toxicity.

Sodium Chloride Cotransporter in Hypertension

The sodium chloride cotransporter (NCC) is essential for electrolyte balance, blood pressure regulation, and pathophysiology of hypertension as it mediates the reabsorption of ultrafiltered sodium in the renal distal convoluted tubule. Given its pivotal role in the maintenance of extracellular fluid volume, the NCC is regulated by a complex network of cellular pathways, which eventually results in either its phosphorylation, enhancing sodium and chloride ion absorption from urines, or dephosphorylation and ubiquitination, which conversely decrease NCC activity. Several factors could influence NCC function, including genetic alterations, hormonal stimuli, and pharmacological treatments. The NCC's central role is also highlighted by several abnormalities resulting from genetic mutations in its gene and consequently in its structure, leading to dysregulation of blood pressure control. In the last decade, among other improvements, the acquisition of knowledge on the NCC and other renal ion channels has been favored by studies on extracellular vesicles (EVs). Dietary sodium and potassium intake are also implicated in the tuning of NCC activity. In this narrative review, we present the main cornerstones and recent evidence related to NCC control, focusing on the context of blood pressure pathophysiology, and promising new therapeutical approaches.

Characterization of hyperactive mutations in the renal potassium channel ROMK uncovers unique effects on channel biogenesis and ion conductance

Hypertension affects one billion people worldwide and is the most common risk factor for cardiovascular disease, yet a comprehensive picture of its underlying genetic factors is incomplete. Amongst regulators of blood pressure is the renal outer medullary potassium (ROMK) channel. While select ROMK mutants are prone to premature degradation and lead to disease, heterozygous carriers of some of these same alleles are protected from hypertension. Therefore, we hypothesized that gain-of-function (GoF) ROMK variants which increase potassium flux may predispose people to hypertension. To begin to test this hypothesis, we employed genetic screens and a candidate-based approach to identify six GoF variants in yeast. Subsequent functional assays in higher cells revealed two variant classes. The first group exhibited greater stability in the endoplasmic reticulum, enhanced channel assembly, and/or increased protein at the cell surface. The second group of variants resided in the PIP2-binding pocket, and computational modeling coupled with patch-clamp studies demonstrated lower free energy for channel opening and slowed current rundown, consistent with an acquired PIP2-activated state. Together, these findings advance our understanding of ROMK structure-function, suggest the existence of hyperactive ROMK alleles in humans, and establish a system to facilitate the development of ROMK-targeted antihypertensives.

Sex-Specific Differences in Kidney Function and Blood Pressure Regulation

Premenopausal women generally exhibit lower blood pressure and a lower prevalence of hypertension than men of the same age, but these differences reverse postmenopause due to estrogen withdrawal. Sexual dimorphism has been described in different components of kidney physiology and pathophysiology, including the renin-angiotensin-aldosterone system, endothelin system, and tubular transporters. This review explores the sex-specific differences in kidney function and blood pressure regulation. Understanding these differences provides insights into potential therapeutic targets for managing hypertension and kidney diseases, considering the patient's sex and hormonal status.

The role of protein prenylation inhibition through targeting FPPS by zoledronic acid in the prevention of renal fibrosis in rats

Renal fibrosis (RF) represents the most widespread pathological condition in chronic kidney disease (CKD). Recently, protein prenylation has been implicated in the fibrosis's progression. The research examined the renoprotective effect of zoledronic acid (ZA) (50 µg/kg/week) in a rat model of carbon tetrachloride (CCl4)-induced RF through targeting protein prenylation. Forty Wistar male rats were split up into the control group, vehicle-treated group, model-RF group, and RF-ZA group. Mean arterial blood pressure (MBP), BUN, serum creatinine, and urine albumin-creatinine ratio (uACR), protein levels of farnesyl pyrophosphate (FPP), tumour necrosis factor-alpha (TNF-α), transforming growth factor-β (TGF-β), and malondialdehyde (MDA), and catalase and gene expression of farnesyl pyrophosphate synthase (FPPS) and nuclear factor-kB (NF-κB) were measured. Immunohistochemical staining for renal interleukin-6 (IL-6), α-smooth muscle actin (α-SMA), and caspase-3, as well as histopathological alterations, were assessed. ZA considerably ceased the reduction in MBP, markedly reduced uACR, serum creatinine, BUN, and expression of FPPS, FPP, NF-κB, TGF-β, TNF-α, and MDA, and significantly increased catalase levels compared to the model-RF rats. ZA ameliorated the CCl4-induced histopathological alterations and suppressed the expression of caspase-3, α-SMA, and IL-6. In conclusion, ZA preserved renal function and prevented renal fibrosis in a rat model. These were achieved through targeting protein prenylation mainly by inhibiting FPPS.

Urotensin II system in chronic kidney disease

Chronic kidney disease (CKD) is a progressive and long-term condition marked by a gradual decline in kidney function. CKD is prevalent among those with conditions such as diabetes mellitus, hypertension, and glomerulonephritis. Affecting over 10% of the global population, CKD stands as a significant cause of morbidity and mortality. Despite substantial advances in understanding CKD pathophysiology and management, there is still a need to explore novel mechanisms and potential therapeutic targets. Urotensin II (UII), a potent vasoactive peptide, has garnered attention for its possible role in the development and progression of CKD. The UII system consists of endogenous ligands UII and UII-related peptide (URP) and their receptor, UT. URP pathophysiology is understudied, but alterations in tissue expression levels of UII and UT and blood or urinary UII concentrations have been linked to cardiovascular and kidney dysfunctions, including systemic hypertension, chronic heart failure, glomerulonephritis, and diabetes. UII gene polymorphisms are associated with increased risk of diabetes. Pharmacological inhibition or genetic ablation of UT mitigated kidney and cardiovascular disease in rodents, making the UII system a potential target for slowing CKD progression. However, a deeper understanding of the UII system's cellular mechanisms in renal and extrarenal organs is essential for comprehending its role in CKD pathophysiology. This review explores the evolving connections between the UII system and CKD, addressing potential mechanisms, therapeutic implications, controversies, and unexplored concepts.

Estimated glomerular filtration rate in observational and interventional studies in chronic kidney disease

Estimated glomerular filtration rate is considered the principal measure of kidney function and, together with albuminuria, is a relevant prognostic factor for the development of end-stage kidney disease. Due to the strong association between estimated glomerular filtration rate and clinical events, such as commencement of dialysis, cardiovascular outcomes and all-cause death, estimated glomerular filtration rate is crucial for clinical decision-making in terms of scheduling follow-up and pharmacological interventions, and planning renal replacement therapies in advanced chronic kidney disease. In this review we discuss the available methods for measuring glomerular filtration rate and for estimating it through mathematical equations developed over the last few decades. We summarize the prognostic association of different percentages of estimated glomerular filtration rate decline and the main clinical outcomes, and how treatments modify estimated glomerular filtration rate decline and the risk of future endpoints. We also examine the role of pre-clinical trial slope and that of estimated glomerular filtration rate as a useful biomarker when evaluating patients for inclusion into both observational and interventional studies.

Advances in 3D bioprinting for regenerative medicine applications

Biofabrication techniques allow for the construction of biocompatible and biofunctional structures composed from biomaterials, cells and biomolecules. Bioprinting is an emerging 3D printing method which utilizes biomaterial-based mixtures with cells and other biological constituents into printable suspensions known as bioinks. Coupled with automated design protocols and based on different modes for droplet deposition, 3D bioprinters are able to fabricate hydrogel-based objects with specific architecture and geometrical properties, providing the necessary environment that promotes cell growth and directs cell differentiation towards application-related lineages. For the preparation of such bioinks, various water-soluble biomaterials have been employed, including natural and synthetic biopolymers, and inorganic materials. Bioprinted constructs are considered to be one of the most promising avenues in regenerative medicine due to their native organ biomimicry. For a successful application, the bioprinted constructs should meet particular criteria such as optimal biological response, mechanical properties similar to the target tissue, high levels of reproducibility and printing fidelity, but also increased upscaling capability. In this review, we highlight the most recent advances in bioprinting, focusing on the regeneration of various tissues including bone, cartilage, cardiovascular, neural, skin and other organs such as liver, kidney, pancreas and lungs. We discuss the rapidly developing co-culture bioprinting systems used to resemble the complexity of tissues and organs and the crosstalk between various cell populations towards regeneration. Moreover, we report on the basic physical principles governing 3D bioprinting, and the ideal bioink properties based on the biomaterials' regenerative potential. We examine and critically discuss the present status of 3D bioprinting regarding its applicability and current limitations that need to be overcome to establish it at the forefront of artificial organ production and transplantation.

Downregulation of the kidney glucagon receptor, essential for renal function and systemic homeostasis, contributes to chronic kidney disease

The glucagon receptor (GCGR) in the kidney is expressed in nephron tubules. In humans and animal models with chronic kidney disease, renal GCGR expression is reduced. However, the role of kidney GCGR in normal renal function and in disease development has not been addressed. Here, we examined its role by analyzing mice with constitutive or conditional kidney-specific loss of the Gcgr. Adult renal Gcgr knockout mice exhibit metabolic dysregulation and a functional impairment of the kidneys. These mice exhibit hyperaminoacidemia associated with reduced kidney glucose output, oxidative stress, enhanced inflammasome activity, and excess lipid accumulation in the kidney. Upon a lipid challenge, they display maladaptive responses with acute hypertriglyceridemia and chronic proinflammatory and profibrotic activation. In aged mice, kidney Gcgr ablation elicits widespread renal deposition of collagen and fibronectin, indicative of fibrosis. Taken together, our findings demonstrate an essential role of the renal GCGR in normal kidney metabolic and homeostatic functions. Importantly, mice deficient for kidney Gcgr recapitulate some of the key pathophysiological features of chronic kidney disease.

Potential Role of the Skin in Hypertension Risk Through Water Conservation

Previous basic and clinical investigations have identified various pathogenic factors and determinants of risk that contribute to hypertension. Nevertheless, the pathogenesis of hypertension has not been fully elucidated. Moreover, despite the availability of antihypertensive medications for the management of blood pressure, treatments that address the full spectrum of the pathophysiological defects underpinning hypertension remain to be identified. To further investigate the mechanisms of primary hypertension, it is imperative to consider novel potential aspects, such as fluid management by the skin, in addition to the conventional risk factors. There is a close association between body fluid regulation and blood pressure, and the kidney, which, as the principal organ responsible for body fluid homeostasis, is the primary target for research in the field of hypertension. In addition, the skin functions as a biological barrier, potentially contributing to body fluid regulation. In this review, we propose the hypothesis that changes in skin water conservation are associated with hypertension risk based on recent findings. Further studies are required to clarify whether this novel hypothesis is limited to specific hypertension or applies to physiological blood pressure regulation.

Sleep and circadian rhythm disturbance in kidney stone disease: a narrative review

The circadian rhythm generated by circadian clock genes functions as an internal timing system. Since the circadian rhythm controls abundant physiological processes, the circadian rhythm evolved in organisms is salient for adaptation to environmental change. A disturbed circadian rhythm is a trigger for numerous pathological events. Recently, accumulated data have indicated that kidney stone disease (KSD) is related to circadian rhythm disturbance. However, the mechanism between them has not been fully elucidated. In this narrative review, we summarized existing evidence to illustrate the possible association between circadian rhythm disturbance and KSD based on the epidemiological studies and risk factors that are linked to circadian rhythm disturbance and discuss some chronotherapies for KSD. In summary, KSD is associated with systemic disorders. Metabolic syndrome, inflammatory bowel disease, and microbiome dysbiosis are the major risk factors supported by sufficient data to cause KSD in patients with circadian rhythm disturbance, while others including hypertension, vitamin D deficiency, parathyroid gland dysfunction, and renal tubular damage/dysfunction need further investigation. Then, some chronotherapies for KSD were confirmed to be effective, but the molecular mechanism is still unclear.

The Association of Toxoplasma gondii with the Combination of Cardiovascular Disease, Chronic Kidney Disease, or Chronic Liver Disease: A Preliminary Study

Toxoplasma gondii is a protozoan parasite widespread worldwide, with over 40 million individuals in the United States. It may infect vital organs such as the heart, kidneys, and liver, resulting in chronic infections. The main objective of this study is to investigate the association of Toxoplasma infection with the combination of cardiovascular disease, chronic kidney disease (CKD), or chronic liver disease (CLD). The National Health and Nutrition Examination Survey (NHANES 2009-2010) data were used, and the association of infection with chronic disease was assessed with biomarkers and indexes using statistical modeling. The percentage of participants with a combination of CLD and CKD was higher among Toxoplasma positive participants compared to the negative participants (2.76 vs. 1.26). Furthermore, exposure to T. gondii may increase the odds of cardiovascular disease, CKD, or CLD, or vice versa.

Calcium carbide-ripened plantain induced alterations in plasma electrolytes concentration and kidney function in rats

INTRODUCTION

Artificial fruit ripening agents such as ethanol, ethylene, ethephon, and calcium carbide (CaC2) is usually employed in stimulating the fruit ripening process. Currently, there is a paucity of information regarding the effects of various artificial fruits ripening methods on the health status of consumers. In this study, the physiological effects and possible health hazards associated with the consumption of plantain ripened by CaC2 and other non-chemical methods on the kidneys were investigated.

METHODS

Artificially ripened plantain was mixed with rat feed and fed to Wistar albino rats for four weeks, and the levels of plasma electrolytes (Na+, HCO3-, K+, and Cl-), urea, creatinine, as well as histological changes in the kidneys were determined.

RESULTS

Results indicated that rats fed with carbide-ripened plantain had a significantly high level of plasma bicarbonate (HCO3-) compared to control rats., but there was no difference in the level of plasma sodium (Na+). However, the levels of plasma potassium (K+) and chloride (Cl-) were significantly low in rats fed with CaC2-ripened plantain as compared to the control rats. Furthermore, the levels of urea and creatinine were significantly high in rats fed with CaC2-ripened plantain compared to the control animals. Histological analyses showed glomeruli atrophy and tubular necrosis in kidneys of rats fed with CaC2-ripened plantain, thereby further indicating toxicity to the kidneys.

CONCLUSIONS

Histological evidence and alterations in the level of the plasma electrolytes, urea, and creatinine suggest that consumption of fruits ripened with calcium carbide may be harmful to the kidneys.

Pediatric chronic kidney disease: blood cell count indexes as inflammation markers

INTRODUCTION

Chronic kidney disease (CKD) is defined as a progressive decline of kidney functions. In childhood, the main triggering factors are congenital anomalies of the kidneys and urinary tract (CAKUT) and glomerulopathies. Inflammatory responses present challenges for diagnosis and staging, which justifies studies on biomarkers/indexes.

AIM

To define blood cell count indexes and verify their association with pediatric CKD etiology and staging. The included indexes were: Neutrophil-Lymphocyte Ratio (NLR), Derived Neutrophil-Lymphocyte Ratio (dNLR), Lymphocyte-Monocyte Ratio (LMR), Systemic Inflammation Response Index (SIRI), Aggregate Index of Systemic Inflammation (AISI), and Systemic Immune-Inflammation Index (SII).

METHODS

We determined the indexes in 52 pediatric CKD patients and 33 healthy controls by mathematical calculation. CKD patients were separated in five groups based on the etiology and staging: Group IA: glomerulopathies at stage 1 or 2; IB: glomerulopathies at stage 3 or 4; IIA: CAKUT at stage 1 or 2; IIB: CAKUT at stage 3 or 4; and III: stages 3 or 4 of other etiologies. In addition, we combined all patients with CKD in one group (IV). Group V was a healthy control group.

RESULTS

Lower values of LMR were observed for groups IB and IIB compared to group V (p = 0.047, p = 0.031, respectively). Increased values of SIRI were found for group III versus group V (p = 0.030). There was no difference for other indexes when the groups were compared two by two.

CONCLUSION

The LMR and SIRI indexes showed promising results in the evaluation of inflammation, as they correlated with CKD etiologies and specially staging in these patients.

Dietary sodium enhances the expression of SLC4 family transporters, IRBIT, L-IRBIT, and PP1 in rat kidney: Insights into the molecular mechanism for renal sodium handling

The kidney plays a central role in maintaining the fluid and electrolyte homeostasis in the body. Bicarbonate transporters NBCn1, NBCn2, and AE2 are expressed at the basolateral membrane of the medullary thick ascending limb (mTAL). In a previous study, NBCn1, NBCn2, and AE2 are proposed to play as a regulatory pathway to decrease NaCl reabsorption in the mTAL under high salt condition. When heterologously expressed, the activity of these transporters could be stimulated by the InsP3R binding protein released with inositol 1,4,5-trisphosphate (IRBIT), L-IRBIT (collectively the IRBITs), or protein phosphatase PP1. In the present study, we characterized by immunofluorescence the expression and localization of the IRBITs, and PP1 in rat kidney. Our data showed that the IRBITs were predominantly expressed from the mTAL through the distal renal tubules. PP1 was predominantly expressed in the TAL, but is also present in high abundance from the distal convoluted tubule through the medullary collecting duct. Western blotting analyses showed that the abundances of NBCn1, NBCn2, and AE2 as well as the IRBITs and PP1 were greatly upregulated in rat kidney by dietary sodium. Co-immunoprecipitation study provided the evidence for protein interaction between NBCn1 and L-IRBIT in rat kidney. Taken together, our data suggest that the IRBITs and PP1 play an important role in sodium handling in the kidney. We propose that the IRBITs and PP1 stimulates NBCn1, NBCn2, and AE2 in the basolateral mTAL to inhibit sodium reabsorption under high sodium condition. Our study provides important insights into understanding the molecular mechanism for the regulation of sodium homeostasis in the body.

Renal CD81 interacts with sodium potassium 2 chloride cotransporter and sodium chloride cotransporter in rats with lipopolysaccharide-induced preeclampsia

The kidney regulates blood pressure through salt/water reabsorption affected by tubular sodium transporters. Expanding our prior research on placental cluster of differentiation 81 (CD81), this study explores the interaction of renal CD81 with sodium transporters in preeclampsia (PE). Effects of renal CD81 with sodium transporters were determined in lipopolysaccharide (LPS)-induced PE rats and immortalized mouse renal distal convoluted tubule cells. Urinary exosomal CD81, sodium potassium 2 chloride cotransporter (NKCC2), and sodium chloride cotransporter (NCC) were measured in PE patients. LPS-PE rats had hypertension from gestational days (GD) 6 to 18 and proteinuria from GD9 to GD18. Urinary CD81 in both groups tented to rise during pregnancy. Renal CD81, not sodium transporters, was higher in LPS-PE than controls on GD14. On GD18, LPS-PE rats exhibited higher CD81 in kidneys and urine exosomes, higher renal total and phosphorylated renal NKCC2 and NCC with elevated mRNAs, and lower ubiquitinated NCC than controls. CD81 was co-immunoprecipitated with NKCC2 or NCC in kidney homogenates and co-immunostained with NKCC2 or NCC in apical membranes of renal tubules. In plasma membrane fractions, LPS-PE rats had greater amounts of CD81, NKCC2, and NCC than controls with enhanced co-immunoprecipitations of CD81 with NKCC2 or NCC. In renal distal convoluted tubule cells, silencing CD81 with siRNA inhibited NCC and prevented LPS-induced NCC elevation. Further, PE patients had higher CD81 in original urines, urine exosomes and higher NKCC2 and NCC in urine exosomes than controls. Thus, the upregulation of renal CD81 on NKCC2 and NCC may contribute to the sustained hypertension observed in LPS-PE model. Urine CD81 with NKCC2 and NCC may be used as biomarkers for PE.

The link between immunity and hypertension in the kidney and heart

Hypertension is the primary cause of cardiovascular disease, which is a leading killer worldwide. Despite the prevalence of this non-communicable disease, still between 90% and 95% of cases are of unknown or multivariate cause ("essential hypertension"). Current therapeutic options focus primarily on lowering blood pressure through decreasing peripheral resistance or reducing fluid volume, but fewer than half of hypertensive patients can reach blood pressure control. Hence, identifying unknown mechanisms causing essential hypertension and designing new treatment accordingly are critically needed for improving public health. In recent years, the immune system has been increasingly implicated in contributing to a plethora of cardiovascular diseases. Many studies have demonstrated the critical role of the immune system in the pathogenesis of hypertension, particularly through pro-inflammatory mechanisms within the kidney and heart, which, eventually, drive a myriad of renal and cardiovascular diseases. However, the precise mechanisms and potential therapeutic targets remain largely unknown. Therefore, identifying which immune players are contributing to local inflammation and characterizing pro-inflammatory molecules and mechanisms involved will provide promising new therapeutic targets that could lower blood pressure and prevent progression from hypertension into renal or cardiac dysfunction.

FTIR Analysis of Renal Tissue for the Assessment of Hypertensive Organ Damage and proANP31–67 Treatment

The kidneys are one of the main end organs targeted by hypertensive disease. Although the central role of the kidneys in the regulation of high blood pressure has been long recognized, the detailed mechanisms behind the pathophysiology of renal damage in hypertension remain a matter of investigation. Early renal biochemical alterations due to salt-induced hypertension in Dahl/salt-sensitive rats were monitored by Fourier-Transform Infrared (FTIR) micro-imaging. Furthermore, FTIR was used to investigate the effects of proANP31–67, a linear fragment of pro-atrial natriuretic peptide, on the renal tissue of hypertensive rats. Different hypertension-induced alterations were detected in the renal parenchyma and blood vessels by the combination of FTIR imaging and principal component analysis on specific spectral regions. Changes in amino acids and protein contents observed in renal blood vessels were independent of altered lipid, carbohydrate, and glycoprotein contents in the renal parenchyma. FTIR micro-imaging was found to be a reliable tool for monitoring the remarkable heterogeneity of kidney tissue and its hypertension-induced alterations. In addition, FTIR detected a significant reduction in these hypertension-induced alterations in the kidneys of proANP31–67-treated rats, further indicating the high sensitivity of this cutting-edge imaging modality and the beneficial effects of this novel medication on the kidneys.

Challenges in the evaluation of endothelial cell dysfunction: a statement from the European Society of Hypertension Working Group on Endothelin and Endothelial Factors

Endothelial cell function is mediated by different mechanisms in different vascular beds. Moreover, in humans, endothelial cell dysfunction triggers and accelerates the progression of cardiovascular and chronic kidney diseases. Progression of such diseases can be in part mitigated by the control of cardiovascular risk factors and drugs targeting different systems, including endothelin receptor antagonists (ERAs), renin-angiotensin aldosterone antagonists and agents affecting glucose metabolism, all of which were shown to improve endothelial cell function. In recent years, the microRNAs, which are endogenous regulators of gene expression, have been identified as transmitters of information from endothelial cells to vascular smooth muscle cells, suggesting that they can entail tools to assess the endothelial cell dysfunction in arterial hypertension and target for pharmacologic intervention. This article critically reviews current challenges and limitations of available techniques for the invasive and noninvasive assessment of endothelial cell function, and also discusses therapeutic aspects as well as directions for future research in the areas of endothelial cell biology and pathophysiology in humans.

Hypertension in Chronic Kidney Disease: An Update on Diagnosis and Management

Hypertension (HTN) and chronic kidney disease (CKD) are pathophysiologic states that are intimately related, such that long-term HTN can lead to poor kidney function, and renal function decline can lead to worsening blood pressure (BP) control. HTN in CKD is caused by an interplay of factors, including salt and water retention, with extracellular volume expansion, sympathetic nervous system overactivity, renin-angiotensin-aldosterone system activation, and endothelial dysfunction. BP variability in the CKD population is significant, however, and thus requires close monitoring for appropriate management. With accumulating evidence, the diagnosis as well as management of HTN in CKD has been evolving in the last decade. In this comprehensive review based on current evidence and recommendations, we summarize the basics of pathophysiology, BP variability, diagnosis, and management of HTN in CKD with an emphasis on special populations with CKD.

Renal sympathetic activity: A key modulator of pressure natriuresis in hypertension

Hypertension is a complex disorder ensuing necessarily from alterations in the pressure-natriuresis relationship, the main determinant of long-term control of blood pressure. This mechanism sets natriuresis to the level of blood pressure, so that increasing pressure translates into higher osmotically driven diuresis to reduce volemia and control blood pressure. External factors affecting the renal handling of sodium regulate the pressure-natriuresis relationship so that more or less natriuresis is attained for each level of blood pressure. Hypertension can thus only develop following primary alterations in the pressure to natriuresis balance, or by abnormal activity of the regulation network. On the other hand, increased sympathetic tone is a very frequent finding in most forms of hypertension, long regarded as a key element in the pathophysiological scenario. In this article, we critically analyze the interplay of the renal component of the sympathetic nervous system and the pressure-natriuresis mechanism in the development of hypertension. A special focus is placed on discussing recent findings supporting a role of baroreceptors as a component, along with the afference of reno-renal reflex, of the input to the nucleus tractus solitarius, the central structure governing the long-term regulation of renal sympathetic efferent tone.

Structure and thiazide inhibition mechanism of the human Na-Cl cotransporter

The sodium-chloride cotransporter (NCC) is critical for kidney physiology1. The NCC has a major role in salt reabsorption in the distal convoluted tubule of the nephron2,3, and mutations in the NCC cause the salt-wasting disease Gitelman syndrome4. As a key player in salt handling, the NCC regulates blood pressure and is the target of thiazide diuretics, which have been widely prescribed as first-line medications to treat hypertension for more than 60 years5-7. Here we determined the structures of human NCC alone and in complex with a commonly used thiazide diuretic using cryo-electron microscopy. These structures, together with functional studies, reveal major conformational states of the NCC and an intriguing regulatory mechanism. They also illuminate how thiazide diuretics specifically interact with the NCC and inhibit its transport function. Our results provide critical insights for understanding the Na-Cl cotransport mechanism of the NCC, and they establish a framework for future drug design and for interpreting disease-related mutations.

Sodium Intake and Disease: Another Relationship to Consider

Sodium (Na+) is crucial for numerous homeostatic processes in the body and, consequentially, its levels are tightly regulated by multiple organ systems. Sodium is acquired from the diet, commonly in the form of NaCl (table salt), and substances that contain sodium taste salty and are innately palatable at concentrations that are advantageous to physiological homeostasis. The importance of sodium homeostasis is reflected by sodium appetite, an "all-hands-on-deck" response involving the brain, multiple peripheral organ systems, and endocrine factors, to increase sodium intake and replenish sodium levels in times of depletion. Visceral sensory information and endocrine signals are integrated by the brain to regulate sodium intake. Dysregulation of the systems involved can lead to sodium overconsumption, which numerous studies have considered causal for the development of diseases, such as hypertension. The purpose here is to consider the inverse-how disease impacts sodium intake, with a focus on stress-related and cardiometabolic diseases. Our proposition is that such diseases contribute to an increase in sodium intake, potentially eliciting a vicious cycle toward disease exacerbation. First, we describe the mechanism(s) that regulate each of these processes independently. Then, we highlight the points of overlap and integration of these processes. We propose that the analogous neural circuitry involved in regulating sodium intake and blood pressure, at least in part, underlies the reciprocal relationship between neural control of these functions. Finally, we conclude with a discussion on how stress-related and cardiometabolic diseases influence these circuitries to alter the consumption of sodium.

Alterações induzidas por plátano maturado com carbureto de cálcio na concentração plasmática de eletrólitos e na função renal em ratos

Resumo Introdução: Agentes de maturação artificial como etanol, etileno, etefon e carbureto de cálcio (CaC2) são comumente empregados para estimular o amadurecimento de frutas. Atualmente, há uma escassez de informações a respeito dos efeitos de diversos métodos artificiais de maturação de frutas no estado de saúde dos consumidores. Neste estudo, investigaram-se os efeitos fisiológicos e possíveis riscos à saúde associados ao consumo de plátano maturado por CaC2 e outros métodos não químicos nos rins. Métodos: O plátano artificialmente amadurecido foi misturado com ração de rato e fornecido a ratos albinos Wistar por quatro semanas, e determinaram-se os níveis de eletrólitos plasmáticos (Na+, HCO3−, K+, e Cl−), ureia, creatinina, bem como alterações histológicas nos rins. Resultados: Ratos alimentados com plátano amadurecido com carbureto apresentaram um nível significativamente maior de bicarbonato plasmático (HCO3−) em comparação com ratos controle, mas não houve diferença no nível plasmático de sódio (Na+). Entretanto, os níveis plasmáticos de potássio (K+) e cloreto (Cl−) foram significativamente baixos em ratos alimentados com plátano maturado com CaC2 comparados com ratos controle. Além disso, os níveis de ureia e creatinina foram significativamente mais elevados em ratos alimentados com plátano amadurecido com CaC2, em comparação com os animais controle. Análises histológicas mostraram atrofia glomerular e necrose tubular em rins de ratos alimentados com plátano amadurecido com CaC2, indicando assim ainda mais toxicidade aos rins. Conclusões: Evidências histológicas e alterações nos eletrólitos plasmáticos, ureia e creatinina sugerem que o consumo de frutas amadurecidas com carbureto de cálcio pode ser prejudicial aos rins.

Contributions of renal water loss and skin water conservation to blood pressure elevation in spontaneously hypertensive rats

We recently reported that skin vasoconstriction to suppress transepidermal water loss (TEWL) leads to hypertension in renal injury model rats with impaired urine concentration ability. In this study, we investigated the pathogenesis of hypertension in spontaneously hypertensive rats (SHRs) from the perspective of renal water loss and skin water conservation. We compared the urinary concentration ability, body sodium and water balance, blood pressure, and TEWL in SHRs and control normotensive Wistar-Kyoto rats (WKYs). SHRs showed significantly higher urine volume and lower urinary osmolality than those of WKYs, while there were no significant differences in water intake, urinary osmolyte excretion, and plasma osmolarity between the groups. SHRs exhibited significantly higher blood pressure, skin sodium content, and lower TEWL compared with those is WKYs. Skin vasodilation, induced by elevating body temperature, increased TEWL in both SHRs and WKYs, and significantly reduced blood pressure in SHRs but not WKYs. These findings suggest that physiological adaptation can reduce dermal water loss in SHRs to compensate for renal water loss. Vasoconstriction required for successful cutaneous water conservation explains SHR hypertension. Renal concentration ability and skin barrier function for water conservation may become a novel therapeutic target for essential hypertension.

Diverse functions of the inward-rectifying potassium channel Kir5.1 and its relationship with human diseases

The inward-rectifying potassium channel subunit Kir5.1, encoded by Kcnj16, can form functional heteromeric channels (Kir4.1/5.1 and Kir4.2/5.1) with Kir4.1 (encoded by Kcnj10) or Kir4.2 (encoded by Kcnj15). It is expressed in the kidneys, pancreas, thyroid, brain, and other organs. Although Kir5.1 cannot form functional homomeric channels in most cases, an increasing number of studies in recent years have found that the functions of this subunit should not be underestimated. Kir5.1 can confer intracellular pH sensitivity to Kir4.1/5.1 channels, which can act as extracellular potassium sensors in the renal distal convoluted tubule segment. This segment plays an important role in maintaining potassium and acid-base balances. This review summarizes the various pathophysiological processes involved in Kir5.1 and the expression changes of Kir5.1 as a differentially expressed gene in various cancers, as well as describing several other disease phenotypes caused by Kir5.1 dysfunction.

Extracellular matrix and vascular dynamics in the kidney of a murine model for Marfan syndrome

Fibrillin-1 is a pivotal structural component of the kidney's glomerulus and peritubular tissue. Mutations in the fibrillin-1 gene result in Marfan syndrome (MFS), an autosomal dominant disease of the connective tissue. Although the kidney is not considered a classically affected organ in MFS, several case reports describe glomerular disease in patients. Therefore, this study aimed to characterize the kidney in the mgΔlpn-mouse model of MFS. Affected animals presented a significant reduction of glomerulus, glomerulus-capillary, and urinary space, and a significant reduction of fibrillin-1 and fibronectin in the glomerulus. Transmission electron microscopy and 3D-ultrastructure analysis revealed decreased amounts of microfibrils which also appeared fragmented in the MFS mice. Increased collagen fibers types I and III, MMP-9, and α-actin were also observed in affected animals, suggesting a tissue-remodeling process in the kidney. Video microscopy analysis showed an increase of microvessel distribution coupled with reduction of blood-flow velocity, while ultrasound flow analysis revealed significantly lower blood flow in the kidney artery and vein of the MFS mice. The structural and hemodynamic changes of the kidney indicate the presence of kidney remodeling and vascular resistance in this MFS model. Both processes are associated with hypertension which is expected to worsen the cardiovascular phenotype in MFS.

Effect of age and sex in renal function by ultrasound and serum chemistry in two primate species (Alouatta caraya and Sapajus apella)

BACKGROUND

Comparative studies of kidney morphophysiology in nonhuman primates can help us investigate interspecies differences in growth and aging patterns.

METHODS

We tested the effect of age and sex in renal morphophysiology in 21 Alouatta caraya and 21 Sapajus apella (age range = 0.5-26 years) by ultrasound, red blood cell (RBC) count, and kidney function tests.

RESULTS

A. caraya had greater growth rate and absolute renal volume than S. apella, but the latter showed a greater relative renal volume and RBC count. There was a negative relationship between RBC and age, a positive relationship between creatinine and body mass, and an apparent negative relationship between creatinine and age only in S. apella.

CONCLUSIONS

Our results indicate that A. caraya has a faster aging mechanism than S. apella, and the higher relative kidney volume in S. apella is suggestive of high metabolic demands in this species.

Assessment of Stiffness of Large to Small Arteries in Multistage Renal Disease Model: A Numerical Study

Arterial stiffness (AS), as assessed via pulse wave velocity (PWV), is a major biomarker for cardiovascular risk assessment in patients with chronic kidney disease (CKD). However, the mechanisms responsible for the changes in PWV in the presence of kidney disease are not yet fully elucidated. In the present study, we aimed to investigate the direct effects attributable to biomechanical changes in the arterial tree caused by staged renal removal, independent of any biochemical or compensatory effects. Particularly, we simulated arterial pressure and flow using a previously validated one-dimensional (1-D) model of the cardiovascular system with different kidney configurations: two kidneys (2KDN), one single kidney (1KDN), no kidneys (0KDN), and a transplanted kidney (TX) attached to the external iliac artery. We evaluated the respective variations in blood pressure (BP), as well as AS of large-, medium-, and small-sized arteries via carotid-femoral PWV (cfPWV), carotid-radial PWV (crPWV), and radial-digital PWV (rdPWV), respectively. Our results showed that BP was increased in 1KDN and 0KDN, and that systolic BP values were restored in the TX configuration. Furthermore, a rise was reported in all PWVs for all tested configurations. The relative difference in stiffness from 2KDN to 0KDN was higher in the case of crPWV (15%) in comparison with the increase observed for cfPWV (11%). In TX, we observed a restoration of the PWVs to values close to 1KDN. Globally, it was demonstrated that alterations of the outflow boundaries to the renal arteries with staged kidney removal led to changes in BP and central and peripheral PWV in line with previously reported clinical data. Our findings suggest that the PWV variations observed in clinical practice with different stages of kidney disease may be partially attributed to biomechanical alterations of the arterial tree and their effect on BP.

Daytime Exposure to Blue Light Alters Cardiovascular Circadian Rhythms, Electrolyte Excretion and Melatonin Production

Artificial light is characterized by certain features of its impact on the body in terms of its spectral distribution of power, duration of exposure and intensity. Short waves, perceived as blue light, are the strongest synchronizing agent for the circadian system. In the present work, we investigated the features of the circadian rhythms of blood pressure (BP), heart rate (HR), the excretion of electrolytes and the secretion of melatonin in normotensive (Wistar–Kyoto) and hypertensive (SHR) rats under the action of monochromatic blue light in the daytime period. It was found that the exposure of Wistar–Kyoto rats to monochromatic blue light was accompanied by a significant decrease in nighttime and 24 h systolic BP. The most remarkable changes are characteristic of the HR in SHR rats under monochromatic light. A significant decrease in HR in each time period was found, but the predominance of nighttime over daytime values remained in SHR animals. There was also a significant increase in the mesor of the HR in SHR rats. Additionally, the amplitude of diastolic BP and HR, as well as the range of oscillations in HR, were significantly increased compared with the standard light pattern. In contrast to SHR rats, the regulation of the circadian rhythms in Wistar–Kyoto rats was more flexible and presented more changes, which may be aimed at the adaptation of the body to environmental conditions. For Wistar–Kyoto rats, an increase in the level of excreted electrolytes was observed under the action of monochromatic light, but no similar changes were found in SHR rats. For Wistar–Kyoto rats, a significant decrease in the urine concentration of aMT6s in the daytime and nighttime periods is characteristic, which results in the loss of the circadian rhythm. In SHR rats, there was a significant decrease in the nighttime content of aMT6s in the urine, while the daytime concentration, on the contrary, increased. The obtained data demonstrate that prolonged exposure to monochromatic blue light in the daytime period affects the circadian structure of the rhythms of the cardiovascular system, the rhythm of electrolyte excretion and the production of epiphyseal melatonin in wild-type and hypertensive animals. In SHR rats, the rhythms of BP and HR exhibit a more rigid pattern.

Diagnosis and management of hypernatraemia in children

Hypernatraemia is most commonly caused by excessive loss of solute-free water or decreased fluid intake; less often, the aetiology is salt intoxication. Especially infants, young children and individuals with a lack of access to water are at risk of developing hypernatraemia. Diagnosis is based on detailed history, physical examination and basic laboratory tests. Correction of hypernatraemia must be slow to prevent cerebral oedema and irreversible brain damage. This article reviews the aetiology, differential diagnosis and management of conditions associated with paediatric hypernatraemia. Distinguishing states with water deficiency from states with salt excess is important for proper management of hypernatraemic patients.

Association between orthostatic blood pressure dysregulation and geriatric syndromes: a cross-sectional study

Background

Orthostatic blood pressure dysregulation, including orthostatic hypotension (OH) and orthostatic hypertension (OHT), is common in the elderly. The association between OH and, to a lesser extent, OHT with geriatric syndromes is controversial and little investigated.

Our objective was to assess the association between orthostatic blood pressure dysregulation and geriatric syndromes in an ambulatory outpatient population.

Methods

This observational study included all outpatients for whom a one-visit comprehensive geriatric assessment was performed during a year. OH was defined as a decrease of at least 20 mmHg in systolic blood pressure (SBP) and/or 10 mmHg in diastolic blood pressure (DBP) after 1 or 3 min of standing. OHT was defined as an increase of more than 20 mmHg in SBP after 1 or 3 min of standing. Comorbidities, drugs regimen, a history of previous falls, nutritional, frailty, functional and cognitive status were compared between patients with OHT or OH and controls (NOR).

Results

Five hundred thirty patients (mean age: 82.9 ± 5.1 years) were included. 19.6% had an OH and 22.3% an OHT. OHT patients were more frequently female, had more diabetes and a lower resting SBP than patients with NOR. OH patients had a higher resting SBP than NOR. After adjusting for age, sex, resting SBP and diabetes, OHT was associated with a low walking speed (OR = 1.332[1.009–1.758]; p = 0.043) and severe cognitive impairment at MMSe score (OR = 1.629[1.070–1.956]; p = 0.016) compared to NOR. Conversely, OH was associated with a lower grip strength (p = 0.016) than NOR.

Conclusion

OHT and OH are common in elderly but associated with different geriatric phenotypes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-02844-8.

The role of nitric oxide in renovascular hypertension: from the pathophysiology to the treatment

Renovascular hypertension is one of the most relevant causes of secondary hypertension, mostly caused by atherosclerotic renovascular stenosis or fibromuscular dysplasia. The increase in angiotensin II production, oxidative stress, and formation of peroxynitrite promotes the decrease in nitric oxide (NO) availability and the development of hypertension, renal and endothelial dysfunction, and cardiac and vascular remodeling. The NO produced by nitric oxide synthases (NOS) acts as a vasodilator; however, endothelial NOS uncoupling (eNOS) also contributes to NO reduced availability in renovascular hypertension. NO donors and NO-derived metabolites have been investigated in experimental renovascular hypertension and have shown promissory effects in attenuating blood pressure and organ damage in this condition. Therefore, understanding the role of decreased NO in the pathophysiology of renovascular hypertension promotes the study and development of NO donors and molecules that can be converted into NO (such as nitrate and nitrite), contributing for the treatment of this condition in the future.

Association between pulse pressure, systolic blood pressure and the risk of rapid decline of kidney function among general population without hypertension: results from the China health and retirement longitudinal study (CHARLS)

BACKGROUND

Association between blood pressure (BP) and kidney function among the middle and old aged general population without hypertension remains unclear.

METHODS

Participants aged ≥ 45 years, with complete data in 2011 and 2015 interviews of the China Health and Retirement Longitudinal Study(CHARLS), and without pre-existing hypertension were included. Systolic BP (SBP) was categorized as low (< 120 mmHg), medium (120-129 mmHg), and high (120-139 mmHg). Diastolic BP (DBP) was categorized as low (< 60 mmHg), medium (60-74 mmHg), and high (75-89 mmHg). Pulse pressure (PP) was categorized as normal (< 60 mmHg) and high (≥ 60 mmHg). The outcome was defined as rapid decline of estimated glomerular filtration rate(eGFR, decline ≥ 4 ml/min/1.73 m2/year). BP combination was designed according to the category of SBP and PP. The association between BP components, types of BP combination, and the risk of rapid decline of eGFR was analyzed using multivariate logistic regression models, respectively. Age-stratified analyses were conducted.

RESULTS

Of 4,534 participants included, 695(15.3%) individuals were recognized as having rapid decline of eGFR. High PP[odds ratio(OR) = 1.34, 95%confidence interval(CI) 1.02-1.75], low SBP (OR = 1.28, 95%CI 1.03-1.59), and high SBP (OR = 1.32, 95% CI 1.02-1.71) were significantly associated with the risk of eGFR decline. Low SBP were associated with 65% increment of the risk of eGFR decline among participants aged < 55 years. The combination of high SBP and high PP (OR = 1.79, 95% CI 1.27-2.54) and the combination of low SBP and high PP (OR = 3.07, 95% CI 1.24-7.58) were associated with the increased risk of eGFR decline among the middle and old aged general population.

CONCLUSION

Single and combination of high PP and high SBP could be the risk indicators of eGFR decline among the middle and old aged general population.

Insights into the Mechanisms of Fetal Growth Restriction-Induced Programming of Hypertension

In recent decades, both clinical and animal studies have shown that fetal growth restriction (FGR), caused by exposure to adverse uterine environments, is a risk factor for hypertension as well as for a variety of adult diseases. This observation has shaped and informed the now widely accepted theory of developmental origins of health and disease (DOHaD). There is a plethora of evidence supporting the association of FGR with increased risk of adult hypertension; however, the underlying mechanisms responsible for this correlation remain unclear. This review aims to explain the current advances in the field of fetal programming of hypertension and a brief narration of the underlying mechanisms that may link FGR to increased risk of adult hypertension. We explain the theory of DOHaD and then provide evidence from both clinical and basic science research which support the theory of fetal programming of adult hypertension. In addition, we have explored the underlying mechanisms that may link FGR to an increased risk of adult hypertension. These mechanisms include epigenetic changes, metabolic disorders, vascular dysfunction, neurohormonal impairment, and alterations in renal physiology and function. We further describe sex differences seen in the developmental origins of hypertension and provide insights into the opportunities and challenges present in this field.

Use of in vitro metabolomics in NRK cells to help predicting nephrotoxicity and differentiating the MoA of nephrotoxicants

We describe a strategy using an in vitro metabolomics assay with tubular rat NRK-52E cells to investigate the Modes of Action (MoAs) of nephrotoxic compounds. Chemicals were selected according to their MoAs based on literature information: acetaminophen, 4-aminophenol and S-(trichlorovinyl-)L-cysteine (TCVC), (covalent protein binding); gentamycin, vancomycin, polymycin B and CdCl₂ (lysosomal overload) and tenofovir and cidofovir (mitochondrial DNA-interaction). After treatment and harvesting of the cells, intracellular endogenous metabolites were quantified relative to vehicle control. Metabolite patterns were evaluated in a purely data-driven pattern generation process excluding published information. This strategy confirmed the assignment of the chemicals to the respective MoA except for TCVC and CdCl₂. Finally, TCVC was defined as unidentified and CdCl₂ was reclassified to the MoA "covalent protein binding". Hierarchical cluster analysis of 58 distinct metabolites from the patterns enabled a clear visual separation of chemicals in each MoA. The assay reproducibility was very good and metabolic responses were consistent. These results support the use of metabolome analysis in NRK-52E cells as a suitable tool for understanding and investigating the MoA of nephrotoxicants. This assay could enable the early identification of nephrotoxic compounds and finally reduce animal testing.

Circumventricular Organ Apelin Receptor Knockdown Decreases Blood Pressure and Sympathetic Drive Responses in the Spontaneously Hypertensive Rat

The central site(s) mediating the cardiovascular actions of the apelin-apelin receptor (APJ) system remains a major question. We hypothesized that the sensory circumventricular organs (CVOs), interfacing between the circulation and deeper brain structures, are sites where circulating apelin acts as a signal in the central nervous system to decrease blood pressure (BP). We show that APJ gene (aplnr) expression was elevated in the CVOs of spontaneously hypertensive rats (SHRs) compared to normotensive Wistar Kyoto (WKY) controls, and that there was a greater mean arterial BP (MABP) decrease following microinjection of [Pyr¹]apelin-13 to the CVOs of SHRs compared to WKY rats. Lentiviral APJ-specific-shRNA (LV-APJ-shRNA) was used to knockdown aplnr expression, both collectively in three CVOs and discretely in individual CVOs, of rats implanted with radiotelemeters to measure arterial pressure. LV-APJ-shRNA-injection decreased aplnr expression in the CVOs and abolished MABP responses to microinjection of [Pyr¹]apelin-13. Chronic knockdown of aplnr in any of the CVOs, collectively or individually, did not affect basal MABP in SHR or WKY rats. Moreover, knockdown of aplnr in any of the CVOs individually did not affect the depressor response to systemic [Pyr¹]apelin-13. By contrast, multiple knockdown of aplnr in the three CVOs reduced acute cardiovascular responses to peripheral [Pyr¹]apelin-13 administration in SHR but not WKY rats. These results suggest that endogenous APJ activity in the CVOs has no effect on basal BP but that functional APJ in the CVOs is required for an intact cardiovascular response to peripherally administered apelin in the SHR.

Clinical Epidemiology of Systolic and Diastolic Orthostatic Hypotension in Patients on Peritoneal Dialysis

Blood pressure changes upon standing reflect a hemodynamic response, which depends on the baroreflex system and euvolemia. Dysautonomia and fluctuations in blood volume are hallmarks in kidney failure requiring replacement therapy. Orthostatic hypotension has been associated with mortality in hemodialysis patients, but neither this relationship nor the impact of changes in blood pressure has been tested in patients on peritoneal dialysis. We investigated both these relationships in a cohort of 137 PD patients. The response to orthostasis was assessed according to a standardized protocol. Twenty-five patients (18%) had systolic orthostatic hypotension, and 17 patients (12%) had diastolic hypotension. The magnitude of systolic and diastolic BP changes was inversely related to the value of the corresponding supine BP component (r = -0.16, p = 0.056 (systolic) and r = -0.25, p = 0.003 (diastolic), respectively). Orthostatic changes in diastolic, but not in systolic, BP were linearly related to the death risk (HR (1 mmHg reduction): 1.04, 95% CI 1.01-1.07, p = 0.006), and this was also true for CV death (HR: 1.08, 95% CI 1.03-1.12, p = 0.001). The strength of this association was not affected by further data adjustment (p ≤ 0.05). These findings suggest that independent of the formal diagnosis of orthostatic hypotension, even minor orthostatic reductions in diastolic BP bear an excess death risk in this population.

Centhaquine Restores Renal Blood Flow and Protects Tissue Damage After Hemorrhagic Shock and Renal Ischemia

Background: Centhaquine (CQ) (Lyfaquin®) is in late stage clinical development as a safe and effective first-in-class resuscitative agent for hemorrhagic shock patients (NCT02408731, NCT04056065, and NCT04045327). Acute kidney injury (AKI) is known to be associated with hemorrhagic shock. Hence, effect of CQ on protection of kidneys from damage due to hemorrhagic shock was investigated. Methods: To assess effect of CQ on AKI in shock, we created a rat model with hemorrhagic shock and AKI. Renal arteries were clamped and de-clamped to induce AKI like ischemia/reperfusion model and hemorrhage was carried out by withdrawing blood for 30 min. Rats were resuscitated with CQ (0.02 mg/kg) for 10 min. MAP, heart rate (HR), and renal blood flow (RBF) were monitored for 120 min. Results: CQ produced a significant improvement in RBF compared to vehicle (p< 0.003) even though MAP and HR was similar in CQ and vehicle groups. Blood lactate level was lower (p = 0.0064) in CQ than vehicle at 120 min post-resuscitation. Histopathological analysis of tissues indicated greater renal damage in vehicle than CQ. Western blots showed higher HIF-1α (p = 0.0152) and lower NGAL (p = 0.01626) levels in CQ vs vehicle. Immunofluorescence in the kidney cortex and medulla showed significantly higher (p< 0.045) expression of HIF-1α and lower expression of Bax (p< 0.044) in CQ. Expression of PHD 3 (p< 0.0001) was higher, while the expression of Cytochrome C (p = 0.01429) was lower in the cortex of CQ than vehicle. Conclusion: Results show CQ (Lyfaquin®) increased renal blood flow, augmented hypoxia response, decreased tissue damage and apoptosis following hemorrhagic shock induced AKI, and may be explored to prevent/treat AKI. Translational Statement: Centhaquine (CQ) is safe for human use and currently in late stage clinical development as a first-in-class resuscitative agent to treat hemorrhagic shock. In the current study, we have explored a novel role of CQ in protection from hemorrhagic shock induced AKI, indicating its potential to treat/prevent AKI.

Genetic variants of GRK4 influence circadian rhythm of blood pressure and response to candesartan in hypertensive patients

Background: Genetic variants of coding genes related to blood pressure regulation participate in the pathogenesis of hypertension and determines the response to specific antihypertensive drugs. G protein-coupled receptor kinase 4 (GRK4) and its variants are of great importance in pathogenesis of hypertension. However, little is known about role of GRK4 variants in determine circadian rhythm of blood pressure and response to candesartan in hypertension. The aim of this study was to analyze the correlation of GRK4 variants and circadian rhythm of blood pressure, and to explore their effect on antihypertensive efficiency of candestartan.Methods: In this study, a total of 1239 cases were eligible, completed ambulatory blood pressure monitoring (ABPm) observation and exon sequencing of G protein-coupled receptor kinase 4 (GRK4). ABPm was obtained before and after 4-week treatment of candesartan. Diurnal variation of systolic blood pressure and antihypertensive effect of candesartan were then assessed.Results: Compared to GRK4 wild type (GRK4-WT), patients with GRK4 variants were more likely to be non-dippers (odds ratio (OR) 6.672, 95% confidence interval (CI) 5.124-8.688, P < .001), with GRK4 A142V (OR 5.888, 95% CI 4.332-8.003, P < .001), A486V (OR 7.102, 95% CI 5.334-9.455, P < .001) and GRK4 R65L (OR 3.273, 95% CI 2.271-4.718, P < .001), respectively. Correlation analysis revealed that non-dippers rhythm of blood pressure were associated with GRK4 variants (r = .420, P < .001), with GRK4 A142V (r = .416, P < .001), A486V (r = .465, P < .001) and GRK4 R65L (r = .266, P < .001), respectively. When given 4-week candesartan, patients with GRK4 variants showed better antihypertensive effect as to drop in blood pressure (24 h mSBP, 21.21 ± 4.99 vs 12.34 ± 4.78 mmHg, P < .001) and morning peak (MP-SBP, 16.54 ± 4.37 vs 11.52 ± 4.14 mmHg, P < .001), as well as greater increase in trough to peak ratio (SBP-T/P, .71 ± .07 vs .58 ± .07, P < .001) and smoothness index (SBP-SI, 1.44 ± .16 vs 1.17 ± .11, P < .001) than those with GRK4 WT.Conclusion: This study indicates that hypertensive patients with GRK4 variants are more likely to be non-dippers. What's more, patients with GRK4 variants possess a significantly better antihypertensive response to candesartan than those with GRK4 WT.

Renal Natriuretic Peptide Receptor-C Deficiency Attenuates NaCl Cotransporter Activity in Angiotensin II-Induced Hypertension

Genome-wide association studies have identified that NPR-C (natriuretic peptide receptor-C) variants are associated with elevation of blood pressure. However, the mechanism underlying the relationship between NPR-C and blood pressure regulation remains elusive. Here, we investigate whether NPR-C regulates Ang II (angiotensin II)-induced hypertension through sodium transporters activity. Wild-type mice responded to continuous Ang II infusion with an increased renal NPR-C expression. Global NPR-C deficiency attenuated Ang II-induced increased blood pressure both in male and female mice associated with more diuretic and natriuretic responses to a saline challenge. Interestingly, Ang II increased both total and phosphorylation of NCC (NaCl cotransporter) abundance involving in activation of WNK4 (with-no-lysine kinase 4)/SPAK (Ste20-related proline/alanine-rich kinase) which was blunted by NPR-C deletion. NCC inhibitor, hydrochlorothiazide, failed to induce natriuresis in NPR-C knockout mice. Moreover, low-salt and high-salt diets-induced changes of total and phosphorylation of NCC expression were normalized by NPR-C deletion. Importantly, tubule-specific deletion of NPR-C also attenuated Ang II-induced elevated blood pressure, total and phosphorylation of NCC expression. Mechanistically, in distal convoluted tubule cells, Ang II dose and time-dependently upregulated WNK4/SPAK/NCC kinase pathway and NPR-C/Gi/PLC/PKC signaling pathway mediated NCC activation. These results demonstrate that NPR-C signaling regulates NCC function contributing to sodium retention-mediated elevated blood pressure, which suggests that NPR-C is a promising candidate for the treatment of sodium retention-related hypertension.

Linking the hemodynamic consequences of adverse childhood experiences to an altered HPA axis and acute stress response

Adverse childhood experiences (ACEs), such as maltreatment and severe household dysfunction, represent a significant threat to public health as ACEs are associated with increased prevalence of several chronic diseases. Biological embedding, believed to be rooted in dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis, is the prevailing theory by which chronic diseases become imprinted in individuals following childhood adversity. A shift towards HPA axis hypoactivity occurs in response to ACEs exposure and is proposed to contribute towards altered cortisol secretion, chronic low-grade inflammation, and dysregulated hemodynamic and autonomic function. This shift in HPA axis activity may be a long-term effect of glucocorticoid receptor methylation with downstream effects on hemodynamic and autonomic function. Emerging evidence suggests syncopal tendencies are increased among those with ACEs and coincides with altered neuroimmune function. Similarly, chronic low-grade inflammation may contribute towards arterial baroreceptor desensitization through increased arterial stiffness, negatively impacting autonomic regulation following posture change and increasing rates of syncope in later life, as has been previously highlighted in the literature. Although speculative, baroreceptor desensitization may be secondary to increased arterial stiffness and changes in expression of glucocorticoid receptors and arginine vasopressin, which are chronically altered by ACEs. Several research gaps and opportunities exist in this field and represent prospective areas for future investigation. Here, we synthesize current findings in the areas of acute psychosocial stress reactivity pertaining to HPA axis function, inflammation, and hemodynamic function while suggesting ideas for future research emphasizing systemic interactions and postural stress assessments among those with ACEs. This review aims to identify specific pathways which may contribute towards orthostatic intolerance in populations with history of childhood adversity.