Glomerular hyperfiltration

Correlation between remnant cholesterol and hyperuricemia in American adults

BACKGROUND

Remnant cholesterol (RC) is an important marker for assessing the risk of metabolic syndrome. However, the correlation between RC and hyperuricemia (HUA) remains unclear. This study aimed to explore the correlation between RC and HUA in American adults.

METHODS

A total of 9089 participants from the 2013-2020 National Health and Nutrition Examination Survey were investigated. The correlation between RC and the odds of HUA was evaluated using multivariate logistic regression analysis. The nonlinear correlation was described using fitted smoothed curves. The correlation in subgroups was analyzed based on race, gender, alcohol consumption, age, body mass index, waist circumference, diabetes and moderate physical activities.

RESULTS

RC was correlated with uric acid (Spearman's correlation coefficient = 0.208 in males and 0.215 in females; all P < 0.001). Multiple logistic regression analysis indicated a positive correlation between RC and the risk of HUA (odds ratio = 1.022 in males and 1.031 in females; all P < 0.001). Subgroup analysis revealed that the correlation was stronger in females, participants aged < 50 years, and those without diabetes. Furthermore, the generalized smooth curve fitting demonstrated a linear correlation between RC and HUA, without threshold or saturation effects.

CONCLUSION

Elevated RC significantly and positively correlated with HUA in American adults. This correlation was stronger among females, participants aged < 50 years, and those without diabetes.

Juxtaglomerular apparatus-mediated homeostatic mechanisms: therapeutic implication for chronic kidney disease

INTRODUCTION

Juxtaglomerular apparatus (JGA)-mediated homeostatic mechanism links to how sodium-glucose cotransporter 2 inhibitors (SGLT2is) slow progression of chronic kidney disease (CKD) and may link to how tolvaptan slows renal function decline in autosomal dominant polycystic kidney disease (ADPKD).

AREA COVERED

JGA-mediated homeostatic mechanism has been hypothesized based on investigations of tubuloglomerular feedback and renin-angiotensin system. We reviewed clinical trials of SGLT2is and tolvaptan to assess the relationship between this mechanism and these drugs.

EXPERT OPINION

When sodium load to macula densa (MD) increases, MD increases adenosine production, constricting afferent arteriole (Af-art) and protecting glomeruli. Concurrently, MD signaling suppresses renin secretion, increases urinary sodium excretion, and counterbalances reduced sodium filtration. However, when there is marked increase in sodium load per-nephron, as in advanced CKD, MD adenosine production increases, relaxing Af-art and maintaining sodium homeostasis at the expense of glomeruli. The beneficial effects of tolvaptan on renal function in ADPKD may also depend on the JGA-mediated homeostatic mechanisms since tolvaptan inhibits sodium reabsorption in the thick ascending limb.The JGA-mediated homeostatic mechanism regulates Af-arts, constricting to relaxing according to homeostatic needs. Understanding this mechanism may contribute to the development of pharmacotherapeutic compounds and better care for patients with CKD.

SGLT2 Inhibitors in Kidney Diseases-A Narrative Review

Some of the most common conditions affecting people are kidney diseases. Among them, we distinguish chronic kidney disease and acute kidney injury. Both entities pose serious health risks, so new drugs are still being sought to treat and prevent them. In recent years, such a role has begun to be assigned to sodium-glucose cotransporter-2 (SGLT2) inhibitors. They increase the amount of glucose excreted in the urine. For this reason, they are currently used as a first-line drug in type 2 diabetes mellitus. Due to their demonstrated cardioprotective effect, they are also used in heart failure treatment. As for the renal effects of SGLT2 inhibitors, they reduce intraglomerular pressure and decrease albuminuria. This results in a slower decline in glomelular filtration rate (GFR) in patients with kidney disease. In addition, these drugs have anti-inflammatory and antifibrotic effects. In the following article, we review the evidence for the effectiveness of this group of drugs in kidney disease and their nephroprotective effect. Further research is still needed, but meta-analyses indicate SGLT2 inhibitors' efficacy in kidney disease, especially the one caused by diabetes. Development of new drugs and clinical trials on specific patient subgroups will further refine their nephroprotective effects.

Sirtuins in kidney health and disease

Sirtuins (SIRTs) are putative regulators of lifespan in model organisms. Since the initial discovery that SIRTs could promote longevity in nematodes and flies, the identification of additional properties of these proteins has led to understanding of their roles as exquisite sensors that link metabolic activity to oxidative states. SIRTs have major roles in biological processes that are important in kidney development and physiological functions, including mitochondrial metabolism, oxidative stress, autophagy, DNA repair and inflammation. Furthermore, altered SIRT activity has been implicated in the pathophysiology and progression of acute and chronic kidney diseases, including acute kidney injury, diabetic kidney disease, chronic kidney disease, polycystic kidney disease, autoimmune diseases and renal ageing. The renoprotective roles of SIRTs in these diseases make them attractive therapeutic targets. A number of SIRT-activating compounds have shown beneficial effects in kidney disease models; however, further research is needed to identify novel SIRT-targeting strategies with the potential to treat and/or prevent the progression of kidney diseases and increase the average human healthspan.

Chronic Kidney Disease Diets for Kidney Failure Prevention: Insights from the IL-11 Paradigm

Nearly every fifth adult in the United States and many older adults worldwide are affected by chronic kidney disease (CKD), which can progress to kidney failure requiring invasive kidney replacement therapy. In this review, we briefly examine the pathophysiology of CKD and discuss emerging mechanisms involving the physiological resolution of kidney injury by transforming growth factor beta 1 (TGFβ1) and interleukin-11 (IL-11), as well as the pathological consequences of IL-11 overproduction, which misguides repair processes, ultimately culminating in CKD. Taking these mechanisms into account, we offer an overview of the efficacy of plant-dominant dietary patterns in preventing and managing CKD, while also addressing their limitations in terms of restoring kidney function or preventing kidney failure. In conclusion, this paper outlines novel regeneration strategies aimed at developing a reno-regenerative diet to inhibit IL-11 and promote repair mechanisms in kidneys affected by CKD.

Increased risk of chronic kidney disease and mortality in a cohort of people diagnosed with metabolic dysfunction associated steatotic liver disease with hepatic fibrosis

BACKGROUND AND AIMS

Metabolic dysfunction associated steatotic liver disease (MASLD) increases the risk of incident chronic kidney disease (CKD). However, the relative risk of CKD associated with increasing hepatic fibrosis, and consequent mortality risk, remains underexplored in real-world cohorts. In this study, we sought to establish whether hepatic fibrosis is associated with increased CKD risk and explore differences in mortality risk in a cohort of people living with MASLD, contingent on liver fibrosis and CKD status.

METHODS

This was an observational study of people who underwent routine liver function testing in Tayside, Scotland. MASLD was defined as: elevated ALT (>30 U/L) or GGT (>73 U/L); presence of diabetes, and/or hypertension, and/or obesity; weekly alcohol consumption <14 units (112g (+/-8g) alcohol); and negative screen for other aetiologies. Data was collected from digital health records. We used log-binomial models to quantify the risk of CKD among those with and without fibrosis, and Cox regression models to estimate differences in mortality risk dependent on fibrosis and CKD.

RESULTS

In our cohort (n = 2,046), 1,448 (70.8%) people had MASLD without fibrosis and 598 (29.2%) with fibrosis; 161 (11.1%) and 117 (19.6%) respectively also had CKD. After excluding individuals with structural, autoimmune, or malignant CKD (n = 22), liver fibrosis (n = 593; 18.9% with CKD) was associated with increased CKD risk (aRR = 1.31, 1.04-1.64, p = 0.021). Increased mortality risk was observed for those with liver fibrosis (aHR = 2.30, 1.49-3.56, p = <0.001) and was higher again among people with both fibrosis and CKD (aHR = 5.07, 3.07-8.39, p = <0.014).

CONCLUSIONS

Liver fibrosis was an independent risk factor for CKD in this cohort of people living with MASLD. Furthermore, those with MASLD with liver fibrosis had higher risk for mortality and this risk was further elevated among those with co-morbid CKD. Given the increased risk of CKD, and consequent mortality risk, among people living with MASLD fibrosis, renal function screening should be considered within liver health surveillance programmes and guidelines.

8-OHdG mediates the association of co-exposure to fifty-five typical endocrine-disrupting chemicals with renal function: a cross-section investigation in Southern Chinese adults

Individual typical endocrine-disrupting chemicals (EDCs), including organophosphate triesters (OPEs), parabens, triclosan (TCS), bisphenols, benzophenones (BPs), phthalates (PAEs), and synthetic phenolic antioxidants (SPAs), are associated with renal dysfunction. However, the combined effects and underlying mechanisms of mixed EDC exposure on renal function remain unclear. Two hundred ninety-nine adult participants were enrolled in the cross-sectional survey conducted in Guangzhou, China. Urinary levels of 7 OPEs, 6 parabens, TCS, 14 bisphenols, 8 BPs, 15 PAEs, 4 SPAs, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) were determined, and estimated glomerular filtration rate (eGFR) was served as the outcome index. We found elevated levels of diphenyl phosphate (DPP), bisphenol A (BPA), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), and mono-butyl phthalate (MBP) showed dose-responsive associations with eGFR decline, However, nonlinear associations were observed for bis(2-butoxyethyl) hydrogen phosphate (BBOEP), TCS, 4-hydroxybenzophenone (HBP), mono-n-pentyl phthalate (MnPP), and mono-benzyl phthalate (MBzP). The quantile-based g-computation model demonstrated that a quartile increase in the EDC mixture corresponded to a 0.383-SD decrease (95% CI - 0.658 ~  - 0.108, P = 0.007) in eGFR. Notably, BPA was identified as the primary contributor to this effect. Moreover, 8-OHdG mediated the eGFR decline associated with EDC mixtures with a mediation proportion of 25.49%. A sex-modified effect was also observed (P = 0.004), indicating that exposure to the mixture of EDC was linked to more pronounced renal dysfunction in females. Our novel findings suggest that exposure to a typical mixture of EDCs is associated with renal dysfunction in the general adult population of Southern China. Furthermore, 8-OHdG may play a role in the pathogenesis of EDC mixture-related renal dysfunction.

Assessment of Risk Factors for Acute Kidney Injury with Machine Learning Tools in Children Undergoing Hematopoietic Stem Cell Transplantation

Background: Although acute kidney injury (AKI) is a common complication in patients undergoing hematopoietic stem cell transplantation (HSCT), its prophylaxis remains a clinical challenge. Attempts at prevention or early diagnosis focus on various methods for the identification of factors influencing the incidence of AKI. Our aim was to test the artificial intelligence (AI) potential in the construction of a model defining parameters predicting AKI development. Methods: The analysis covered the clinical data of children followed up for 6 months after HSCT. Kidney function was assessed before conditioning therapy, 24 h after HSCT, 1, 2, 3, 4, and 8 weeks after transplantation, and, finally, 3 and 6 months post-transplant. The type of donor, conditioning protocol, and complications were incorporated into the model. Results: A random forest classifier (RFC) labeled the 93 patients according to presence or absence of AKI. The RFC model revealed that the values of the estimated glomerular filtration rate (eGFR) before and just after HSCT, as well as methotrexate use, acute graft versus host disease (GvHD), and viral infection occurrence, were the major determinants of AKI incidence within the 6-month post-transplant observation period. Conclusions: Artificial intelligence seems a promising tool in predicting the potential risk of developing AKI, even before HSCT or just after the procedure.

Pediatric kidney dimensions and risk of persistent albuminuria in Mexican adolescents

In Mexico, chronic kidney disease of unknown origin is highly prevalent. Screening studies in adolescents have shown persistent microalbuminuria (pACR), adaptive podocytopathy and decreased kidney volume (KV). Here, we sought to develop normality tables of kidney dimensions by ultrasound in the Mexican state of Aguascalientes pediatric population (0 to 18y) and evaluate the relationship between the KV and pACR among the region's adolescents in a cross-sectional study. Kidney length (KL) and KV were determined by ultrasound. Our findings were compared with those in international literature of different populations where tables and graphs of normal kidney dimensions by ultrasound were reported. We compared organ dimensions in individuals above the age of 11 without albuminuria with those in patients with pACR recruited through screening studies in adolescents in Aguascalientes. This included 1068 individuals to construct percentile tables and graphs of the KL. Kidney dimensions were significantly lower when compared with all international comparisons. From a total 14,805 screen individuals, we compared 218 adolescents with pACR and 377 individuals without significant albuminuria. The Total KV adjusted to body surface (TKVBS) was significantly associated with pACR (odds ratio 1.03, 95% confidence interval 1.02-1.03). The upper quartile of TKVBS was highly associated with pACR (7.57, 4.13-13.87), hypertension (2.53, 1.66-3.86), and hyperfiltration (26 vs 11.5%). Thus, TKVBS is directly associated with pACR while greater KV, arterial hypertension, and hyperfiltration in patients with pACR suggest that the increase in volume is secondary to kidney hypertrophy. Additionally, the adaptative podocytopathy with low fibrosis seen on kidney biopsy which was performed in a subset of patients, and the smaller kidney dimensions in our population point to prenatal oligonephronia as the primary cause of the detected kidney disease.

A Retrospective Cohort Study That Examined the Impact of Cannabis Consumption on Long-Term Kidney Outcomes

Background: Cannabis consumption for recreational and medical use is increasing worldwide. However, the long-term effects on kidney health and disease are largely unknown. Materials and Methods: Post hoc analysis of cannabis use as a risk factor for kidney disease was performed using data from the Assessment, Serial Evaluation, and Subsequent Sequelae of Acute Kidney Injury (ASSESS-AKI) study that enrolled hospitalized adults with and without acute kidney injury from four U.S. centers during 2009-2015. Associations between self-reported cannabis consumption and the categorical and continuous outcomes were determined using multivariable Cox regression and linear mixed models, respectively. Results: Over a mean follow-up of 4.5±1.8 years, 94 participants without chronic kidney disease (CKD) (estimated glomerular filtration rate [eGFR] >60 mL/min/1.73 m2) who consumed cannabis had similar rates of annual eGFR decline versus 889 nonconsumers (mean difference=-0.02 mL/min/1.73 m2/year, p=0.9) and incident CKD (≥25% reduction in eGFR compared with the 3-month post-hospitalization measured eGFR and achieving CKD stage 3 or higher) (adjusted hazard ratio [aHR]=1.2; 95% confidence interval [CI]=0.7-2.0). Nineteen participants with CKD (eGFR <60 mL/min/1.73 m2) who consumed cannabis had more rapid eGFR decline versus 597 nonconsumers (mean difference=-1.3 mL/min/1.73 m2/year; p=0.02) that was not independently associated with an increased risk of CKD progression (≥50% reduction in eGFR compared with the 3-month post-hospitalization eGFR, reaching CKD stage 5, or receiving kidney replacement therapy) (aHR=1.6; 95% CI=0.7-3.5). Cannabis consumption was not associated with the rate of change in urine albumin to creatinine ratio (UACR) over time among those with (p=0.7) or without CKD (p=0.4). Conclusions: Cannabis consumption did not adversely affect the kidney function of participants without CKD but was associated with a faster annual eGFR decline among participants with CKD. Cannabis consumption was not associated with changes in UACR over time, incident CKD, or progressive CKD regardless of baseline kidney function. Additional research is needed to investigate the kidney endocannabinoid system and the impact of cannabis use on kidney disease outcomes.

Co-exposure of petrochemical workers to noise and mixture of benzene, toluene, ethylbenzene, xylene, and styrene: Impact on mild renal impairment and interaction

Epidemiological evidence concerning effects of simultaneous exposure to noise and benzene, toluene, ethylbenzene, xylene, and styrene (BTEXS) on renal function remains uncertain. In 2020, a cross-sectional study was conducted among 1160 petrochemical workers in southern China to investigate effects of their co-exposure on estimated glomerular filtration rate (eGFR) and mild renal impairment (MRI). Noise levels were assessed using cumulative noise exposure (CNE). Urinary biomarkers for BTEXS were quantified. We found the majority of workers had exposure levels to noise and BTEXS below China's occupational exposure limits. CNE, trans, trans-muconic acid (tt-MA), and the sum of mandelic acid and phenylglyoxylic acid (PGMA) were linearly associated with decreased eGFR and increased MRI risk. We observed U-shaped associations for both N-acetyl-S-phenyl-L-cysteine (SPMA) and o-methylhippuric acid (2-MHA) with MRI. In further assessing the joint effect of BTEXS (β, -0.164 [95% CI, -0.296 to -0.033]) per quartile increase in all BTEXS metabolites on eGFR using quantile g-computation models, we found SPMA, tt-MA, 2-MHA, and PGMA played pivotal roles. Additionally, the risk of MRI associated with tt-MA was more pronounced in workers with lower CNE levels (P = 0.004). Multiplicative interaction analysis revealed antagonisms of CNE and PGMA on MRI risk (P = 0.034). Thus, our findings reveal negative dose-effect associations between noise and BTEXS mixture exposure and renal function in petrochemical workers. With the exception of toluene, benzene, xylene, ethylbenzene, and styrene are all concerning pollutants for renal dysfunction. Effects of benzene, ethylbenzene, and styrene exposure on renal dysfunction were more pronounced in workers with lower CNE.

Association between Glycosylated Hemoglobin and Serum Uric Acid: A US NHANES 2011-2020

Background

Serum uric acid (SUA) and glycosylated hemoglobin (HbA1c) were closely related to the body's metabolism. This study aimed to investigate the relationship between HbA1c and SUA in adults.

Methods

This study selected 7293 participants aged ≥20 from 2011 to 2020 in the National Health and Nutrition Examination Survey (NHANES). The multivariate linear regression model was used to test the association between HbA1c and SUA. Subgroup analysis was performed according to age, gender, race, and body mass index (BMI). This study solved the relationship between HbA1c and SUA by fitting a smooth curve. Finally, the inflection point in the nonlinear relationship was calculated by the recursive algorithm, and the relationship between HbA1c and SUA on both sides of the inflection point was analyzed by the two-segment piecewise linear regression model.

Results

All 7293 participants found a negative correlation between HbA1c and SUA by completely adjusting the model (β = -7.93 and 95% CI: -9.49--6.37). In addition, when this study was stratified by gender, age, race, and BMI status, this negative correlation was still statistically significant. In the subgroup analysis, we found that the relationship between the two had different results due to gender differences. In men, HbA1c had a significant negative correlation with SUA. However, in women, the HbA1c value was positively correlated with SUA before 6.8%, and the HbA1c value was negatively correlated with SUA after 6.8%, which indicates that the relationship between HbA1c and SUA in women has changed in prediabetes and diabetes.

Conclusion

This study shows that HbA1c is positively correlated with SUA in American adults before 7%. There is a negative correlation after the HbA1c value of 7%.

Cardiopulmonary bypass management and acute kidney injury in cardiac surgery patients

BACKGROUND

Cardiopulmonary bypass (CPB) ensures tissue oxygenation during cardiac surgery. New technology allows continuous registration of CPB variables during the operation. The aim of the present investigation was to study the association between CPB management and the risk of postoperative acute kidney injury (AKI).

METHODS

This observational study based on prospectively registered data included 2661 coronary artery bypass grafting and/or valve patients operated during 2016-2020. Individual patient characteristics and postoperative outcomes collected from the SWEDEHEART registry were merged with CPB variables automatically registered every 20 s during CPB. Associations between CPB variables and AKI were analyzed with multivariable logistic regression models adjusted for patient characteristics.

RESULTS

In total, 387 patients (14.5%) developed postoperative AKI. After adjustments, longer time on CPB and aortic cross-clamp, periods of compromised blood flow during aortic cross-clamp time, and lower nadir hematocrit were associated with the risk of AKI, while mean blood flow, bladder temperature, central venous pressure, and mixed venous oxygen saturation were not. Patient characteristics independently associated with AKI were advanced age, higher body mass index, hypertension, diabetes mellitus, atrial fibrillation, lower left ventricular ejection fraction, estimated glomerular filtration rate <60 or >90 mL/min/m2 , and preoperative hemoglobin concentration below or above the normal sex-specific range.

CONCLUSIONS

To reduce the risk of AKI after cardiac surgery, aortic clamp time and CPB time should be kept short, and low hematocrit and periods of compromised blood flow during aortic cross-clamp time should be avoided if possible.

Renal sinus fat is associated with intrarenal hemodynamic abnormalities independent of visceral fat in patients with chronic kidney disease

OBJECTIVE

Obesity is a risk factor of chronic kidney disease (CKD), contributing to the rising incidence of cardiometabolic diseases. Renal sinus fat (RSF) is an ectopic fat depot located at the renal cavity that could impair renal function and hemodynamic through compression of renal structures. The major purpose of this study was to explore the relationship between RSF accumulation and renal dysfunction in CKD patients.

METHODS

We evaluated the associations between computed tomography measured RSF volume and key clinical and histologic parameters involved in renal function and hemodynamics in 132 well-characterized CKD patients who underwent renal biopsy (median age: 62 years; 63.6% men).

RESULTS

RSF volume normalized by renal volume (RSF%) positively correlated with obesity-related traits such body mass index and visceral fat volume (VFV) (all P < 0.001) whereas it negatively correlated with estimated glomerular filtration rate (eGFR) (ρ = -0.42, P < 0.001) and 24-h urinary creatinine clearance (CCr) (ρ = -0.34, P < 0.001). Notably, we found robust positive correlations between RSF% and renal resistive index (RRI) measured by the Doppler ultrasound (ρ = 0.40, P < 0.001), and the histological severity of global glomerular sclerosis (ρ = 0.48, P < 0.001) and interstitial fibrosis and tubular atrophy (IFTA) (ρ = 0.35, P < 0.001). In the multivariate linear regression models, after accounting for potential confounders including VFV, RSF% remained significantly associated with CCr (β = -0.26, P < 0.001), RRI (β = 0.17, P = 0.022), global glomerular sclerosis (β = 0.21, P = 0.002), and IFTA (β = 0.17, P = 0.012).

CONCLUSION

RSF accumulation is associated with renal dysfunction and hemodynamic abnormalities independent of visceral adiposity. Our results suggest that RSF may have a potential unique role in the pathogenesis of CKD.

Renal dysfunction in AQP4 NMOSD and MS; a potential predictor of relapse and prognosis

OBJECTIVE

This study aimed to explore the association between kidney function and the risk of relapse as well as prognosis in patients with aquaporin-4 (AQP4)-immunoglobulin G (IgG)-seropositive neuromyelitis optica spectrum disorder (NMOSD).

METHODS

We focused on patients experiencing their first onset of AQP4-IgG-seropositive NMOSD. Data on demographics, disease characteristics, and kidney function were collected, with the primary assessment utilizing the estimated glomerular filtration rate (eGFR). Associations between eGFR and relapse risk were examined using multivariate Cox proportional hazards regression models. Additionally, logistic regression models were employed to evaluate the impact of eGFR on clinical prognosis.

RESULTS

Our analysis revealed glomerular hyperfiltration and impaired urine concentrating ability in patients with AQP4-IgG-seropositive NMOSD. Multivariate Cox proportional hazards regression demonstrated a positive correlation between eGFR and the risk of relapse. Logistic regression analysis further identified higher eGFR as an independent predictor of disease relapse and prognosis in AQP4-IgG-seropositive NMOSD patients.

CONCLUSIONS

The eGFR of patients with AQP4-IgG-seropositive NMOSD emerges as a potential diagnostic biomarker for this condition, indicating its significance in predicting both relapse risk and clinical prognosis.

Albuminuria, Forgotten No More: Underlining the Emerging Role in CardioRenal Crosstalk

Kidneys have an amazing ability to adapt to adverse situations, both acute and chronic. In the presence of injury, the kidney is able to activate mechanisms such as autoregulation or glomerular hyperfiltration to maintain the glomerular filtration rate (GFR). While these adaptive mechanisms can occur in physiological situations such as pregnancy or high protein intake, they can also occur as an early manifestation of diseases such as diabetes mellitus or as an adaptive response to nephron loss. Although over-activation of these mechanisms can lead to intraglomerular hypertension and albuminuria, other associated mechanisms related to the activation of inflammasome pathways, including endothelial and tubular damage, and the hemodynamic effects of increased activity of the renin-angiotensin-aldosterone system, among others, are recognized pathways for the development of albuminuria. While the role of albuminuria in the progression of chronic kidney disease (CKD) is well known, there is increasing evidence of its negative association with cardiovascular events. For example, the presence of albuminuria is associated with an increased likelihood of developing heart failure (HF), even in patients with normal GFR, and the role of albuminuria in atherosclerosis has recently been described. Albuminuria is associated with adverse outcomes such as mortality and HF hospitalization. On the other hand, it is increasingly known that the systemic effects of congestion are mainly preceded by increased central venous pressure and transmitted retrogradely to organs such as the liver or kidney. With regard to the latter, a new entity called congestive nephropathy is emerging, in which increased renal venous pressure can lead to albuminuria. Fortunately, the presence of albuminuria is modifiable and new treatments are now available to reverse this common risk factor in the cardiorenal interaction.

Application of nanotechnology in the treatment of glomerulonephritis: current status and future perspectives

Glomerulonephritis (GN) is the most common cause of end-stage renal failure worldwide; in most cases, it cannot be cured and can only delay the progression of the disease. At present, the main treatment methods include symptomatic therapy, immunosuppressive therapy, and renal replacement therapy. However, effective treatment of GN is hindered by issues such as steroid resistance, serious side effects, low bioavailability, and lack of precise targeting. With the widespread application of nanoparticles in medical treatment, novel methods have emerged for the treatment of kidney diseases. Targeted transportation of drugs, nucleic acids, and other substances to kidney tissues and even kidney cells through nanodrug delivery systems can reduce the systemic effects and adverse reactions of drugs and improve treatment effectiveness. The high specificity of nanoparticles enables them to bind to ion channels and block or enhance channel gating, thus improving inflammation. This review briefly introduces the characteristics of GN, describes the treatment status of GN, systematically summarizes the research achievements of nanoparticles in the treatment of primary GN, diabetic nephropathy and lupus nephritis, analyzes recent therapeutic developments, and outlines promising research directions, such as gas signaling molecule nanodrug delivery systems and ultrasmall nanoparticles. The current application of nanoparticles in GN is summarized to provide a reference for better treatment of GN in the future.

Intrauterine life to adulthood: a potential risk factor for chronic kidney disease

Multiple risk factors for chronic kidney disease (CKD), one of the major causes of morbidity and mortality in the adult population globally, have been identified, including older age, male gender, family history, smoking, diabetes mellitus, hypertension, ischaemic heart diseases and various medications. Preterm delivery, affecting >10% of the newborns in the USA, is a global concern with increasing incidence in recent decades. Preterm birth has been linked to multiple medical comorbidities such as diabetes mellitus, hypertension and cardiovascular diseases, while its association with CKD has recently been investigated. Prematurity and intrauterine growth restriction (IUGR) have been associated with an increased risk for CKD, specific histopathological examination findings and CKD-associated risk factors such as diabetes mellitus, hypertension and dyslipidaemia. In this narrative review, our aim is to evaluate and summarize the association between the risk for CKD and prematurity, low birthweight and IUGR along with potential underlying pathophysiological mechanisms.

Obesity, Hyperfiltration, and Early Kidney Damage: A New Formula for the Estimation of Creatinine Clearance

CONTEXT

Glomerular hyperfiltration may represent a direct pathogenetic link between obesity and kidney disease. The most widely used methods to estimate creatine clearance such as Cockroft-Gault (CG), Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) have not been validated in subjects with obesity.

OBJECTIVE

The performance of prediction formulas was compared with measured creatinine clearance (mCrCl) in subjects with obesity.

METHODS

The study population included 342 patients with obesity (mean BMI 47.6 kg/m2) without primary kidney disease. A urine collection was performed over 24 hours for measurement of CrCl.

RESULTS

mCrCl increased with body weight. The CG formula showed an overestimation at high CrCl, whereas an underestimation resulted from CKD-EPI and MDRD. To improve the accuracy of estimated CrCl (eCrCl), a new CG-based formula was developed:53+0.7×(140-Age)×Weight/(96xSCr)×(0.85iffemale)A cut-off point for BMI of 32 kg/m2 was identified, at which the new formula may be applied to improve eCrCl.

CONCLUSION

In patients with obesity the glomerular filtration rate increases with body weight, and it is associated with the presence of albuminuria, suggesting an early kidney injury. We propose a novel formula that improves the accuracy of eCrCl to avoid missed diagnoses of hyperfiltration in patients with obesity.

The five types of glomerulonephritis classified by pathogenesis, activity and chronicity (GN-AC)

Glomerulonephritis (GN) is a diverse group of immune-mediated disorders. Currently, GN is classified largely by histological patterns that are difficult to understand and teach, and most importantly, do not indicate treatment choices. Indeed, altered systemic immunity is the primary pathogenic process and the key therapeutic target in GN. Here, we apply a conceptual framework of immune-mediated disorders to GN guided by immunopathogenesis and hence immunophenotyping: (i) infection-related GN require pathogen identification and control; (ii) autoimmunity-related GN, defined by presence of autoantibodies and (iii) alloimmunity-related GN in transplant recipients both require the suppression of adaptive immunity in lymphoid organs and bone marrow; (iv) autoinflammation-related GN, e.g. inborn errors of immunity diagnosed by genetic testing, requires suppression of single cytokine or complement pathways; and (v) Monoclonal gammopathy-related GN requires B or plasma cell clone-directed therapy. A new GN classification should include disease category, immunological activity to tailor the use of the increasing number of immunomodulatory drugs, and chronicity to trigger standard chronic kidney disease care including the evolving spectrum of cardio-renoprotective drugs. Certain biomarkers allow diagnosis and the assessment of immunological activity and disease chronicity without kidney biopsy. The use of these five GN categories and a therapy-focused GN classification is likely to overcome some of the existing hurdles in GN research, management and teaching by reflecting disease pathogenesis and guiding the therapeutic approach.

CKD therapy to improve outcomes of immune-mediated glomerular diseases

The management of immunoglobulin A nephropathy, membranous nephropathy, lupus nephritis, anti-neutrophil cytoplasmic antibody-associated vasculitis, C3 glomerulonephritis, autoimmune podocytopathies and other immune-mediated glomerular disorders is focused on two major treatment goals, preventing overall mortality and the loss of kidney function. Since minimizing irreversible kidney damage best serves both goals, the management of immune-mediated kidney disorders must focus on the two central pathomechanisms of kidney function decline, i.e., controlling the underlying immune disease process (e.g. with immunotherapies) and controlling the non-immune mechanisms of chronic kidney disease (CKD) progression. Here we review the pathophysiology of these non-immune mechanisms of CKD progression and discuss non-drug and drug interventions to attenuate CKD progression in immune-mediated kidney disorders. Non-pharmacological interventions include reducing salt intake, normalizing body weight, avoiding superimposed kidney injuries, smoking cessation and regular physical activity. Approved drug interventions include inhibitors of the renin-angiotensin-aldosterone system and sodium-glucose cotransporter-2. Numerous additional drugs to improve CKD care are currently being tested in clinical trials. Here we discuss how and when to use these drugs in the different clinical scenarios of immune-mediated kidney diseases.

Nanomedicines for the management of diabetic nephropathy: present progress and prospects

Diabetic nephropathy (DN) is a serious microvascular consequence of diabetes mellitus (DM), posing an encumbrance to public health worldwide. Control over the onset and progress of DN depend heavily on early detection and effective treatment. DN is a major contributor to end-stage renal disease, and a complete cure is yet to be achieved with currently available options. Though some therapeutic molecules have exhibited promise in treating DN complications, their poor solubility profile, low bioavailability, poor permeation, high therapeutic dose and associated toxicity, and low patient compliance apprehend their clinical usefulness. Recent research has indicated nano-systems as potential theranostic platforms displaying futuristic promise in the diagnosis and treatment of DN. Early and accurate diagnosis, site-specific delivery and retention by virtue of ligand conjugation, and improved pharmacokinetic profile are amongst the major advantages of nano-platforms, defining their superiority. Thus, the emergence of nanoparticles has offered fresh approaches to the possible diagnostic and therapeutic strategies regarding DN. The present review corroborates an updated overview of different types of nanocarriers regarding potential approaches for the diagnosis and therapy of DN.

What is central to renal nutrition: protein or sodium intake?

Historically, nutrition intervention has been primarily focused on limiting kidney injury, reducing generation of uraemic metabolites, as well as maintaining nutrition status and preventing protein-energy wasting in patients with chronic kidney disease (CKD). This forms an important rationale for prescribing restricted protein diet and restricted salt diet in patients with CKD. However, evidence supporting a specific protein intake threshold or salt intake threshold remains far from compelling. Some international or national guidelines organizations have provided strong or 'level 1' recommendations for restricted protein diet and restricted salt diet in CKD. However, it is uncertain whether salt or protein restriction plays a more central role in renal nutrition management. A key challenge in successful implementation or wide acceptance of a restricted protein diet and a restricted salt diet is patients' long-term dietary adherence. These challenges also explain the practical difficulties in conducting randomized trials that evaluate the impact of dietary therapy on patients' outcomes. It is increasingly recognized that successful implementation of a restricted dietary prescription or nutrition intervention requires a highly personalized, holistic care approach with support and input from a dedicated multidisciplinary team that provides regular support, counselling and close monitoring of patients. With the advent of novel drug therapies for CKD management such as sodium-glucose cotransporter-2 inhibitors or non-steroidal mineralocorticoid receptor antagonist, it is uncertain whether restricted protein diet and restricted salt diet may still be necessary and have incremental benefits. Powered randomized controlled trials with novel design are clearly indicated to inform clinical practice on recommended dietary protein and salt intake threshold for CKD in this new era.

Glomerular Hyperfiltration: A Marker of Fibrosis Severity in Metabolic Associated Steatotic Liver Disease in an Adult Population

Glomerular hyperfiltration (GH) is an increase in the glomerular filtration rate, possibly progressing to chronic kidney disease (CKD). Metabolic-associated steatotic liver disease (MASLD) is linked to an increased risk of CKD, especially if fibrosis is present; however, the association between GH and MASLD has not been explored. To evaluate GH prevalence in MASLD and its possible correlation with liver fibrosis. 772 consecutive patients with ultrasound MASLD (mean age 47.3 ± 8.9 years, 67.1% males) were enrolled. GH was defined as estimated glomerular filtration rate (eGFR) greater than the upper quartile of values in the cohort. Liver stiffness measurement (LSM) by FibroScan ≥ 7.2 kPa suggested liver fibrosis. GH was present in 20% of patients, liver fibrosis in 30%. In total, 53.4% of the cohort was obese, 40.9% hypertensive, 36.3% diabetic and 70.8% dyslipidaemic. GH patients compared to non-GH were significantly younger (38.4 ± 8.3 vs. 49.5 ± 7.7, p < 0.001), with higher prevalence of LSM > 7.2 kPa (35.5% vs. 29%, p < 0.001), without any difference in metabolic comorbidities. In multivariate analysis, age (OR 0.85, CI 95% 0.82-0.87) and significant fibrosis (OR 1.83; CI 95%1.10-3.03) remained independently associated with GH, regardless of the presence of metabolic alterations and nephrotoxic drugs. GH, an early marker of renal damage, is highly prevalent in MASLD and is associated with hepatic fibrosis. GH may be considered an early marker of both liver and renal disease and its recognition could prompt the management of risk factors aimed at preventing the progression of both hepatic and renal disease.

KIM-1, IL-18, and NGAL, in the Machine Learning Prediction of Kidney Injury among Children Undergoing Hematopoietic Stem Cell Transplantation-A Pilot Study

Children undergoing allogeneic hematopoietic stem cell transplantation (HSCT) are prone to developing acute kidney injury (AKI). Markers of kidney damage: kidney injury molecule (KIM)-1, interleukin (IL)-18, and neutrophil gelatinase-associated lipocalin (NGAL) may ease early diagnosis of AKI. The aim of this study was to assess serum concentrations of KIM-1, IL-18, and NGAL in children undergoing HSCT in relation to classical markers of kidney function (creatinine, cystatin C, estimated glomerular filtration rate (eGFR)) and to analyze their usefulness as predictors of kidney damage with the use of artificial intelligence tools. Serum concentrations of KIM-1, IL-18, NGAL, and cystatin C were assessed by ELISA in 27 children undergoing HSCT before transplantation and up to 4 weeks after the procedure. The data was used to build a Random Forest Classifier (RFC) model of renal injury prediction. The RFC model established on the basis of 3 input variables, KIM-1, IL-18, and NGAL concentrations in the serum of children before HSCT, was able to effectively assess the rate of patients with hyperfiltration, a surrogate marker of kidney injury 4 weeks after the procedure. With the use of the RFC model, serum KIM-1, IL-18, and NGAL may serve as markers of incipient renal dysfunction in children after HSCT.

Reactive oxygen species, toxicity, oxidative stress, and antioxidants: chronic diseases and aging

A physiological level of oxygen/nitrogen free radicals and non-radical reactive species (collectively known as ROS/RNS) is termed oxidative eustress or "good stress" and is characterized by low to mild levels of oxidants involved in the regulation of various biochemical transformations such as carboxylation, hydroxylation, peroxidation, or modulation of signal transduction pathways such as Nuclear factor-κB (NF-κB), Mitogen-activated protein kinase (MAPK) cascade, phosphoinositide-3-kinase, nuclear factor erythroid 2-related factor 2 (Nrf2) and other processes. Increased levels of ROS/RNS, generated from both endogenous (mitochondria, NADPH oxidases) and/or exogenous sources (radiation, certain drugs, foods, cigarette smoking, pollution) result in a harmful condition termed oxidative stress ("bad stress"). Although it is widely accepted, that many chronic diseases are multifactorial in origin, they share oxidative stress as a common denominator. Here we review the importance of oxidative stress and the mechanisms through which oxidative stress contributes to the pathological states of an organism. Attention is focused on the chemistry of ROS and RNS (e.g. superoxide radical, hydrogen peroxide, hydroxyl radicals, peroxyl radicals, nitric oxide, peroxynitrite), and their role in oxidative damage of DNA, proteins, and membrane lipids. Quantitative and qualitative assessment of oxidative stress biomarkers is also discussed. Oxidative stress contributes to the pathology of cancer, cardiovascular diseases, diabetes, neurological disorders (Alzheimer's and Parkinson's diseases, Down syndrome), psychiatric diseases (depression, schizophrenia, bipolar disorder), renal disease, lung disease (chronic pulmonary obstruction, lung cancer), and aging. The concerted action of antioxidants to ameliorate the harmful effect of oxidative stress is achieved by antioxidant enzymes (Superoxide dismutases-SODs, catalase, glutathione peroxidase-GPx), and small molecular weight antioxidants (vitamins C and E, flavonoids, carotenoids, melatonin, ergothioneine, and others). Perhaps one of the most effective low molecular weight antioxidants is vitamin E, the first line of defense against the peroxidation of lipids. A promising approach appears to be the use of certain antioxidants (e.g. flavonoids), showing weak prooxidant properties that may boost cellular antioxidant systems and thus act as preventive anticancer agents. Redox metal-based enzyme mimetic compounds as potential pharmaceutical interventions and sirtuins as promising therapeutic targets for age-related diseases and anti-aging strategies are discussed.

Glomerular hyperfiltration is an independent predictor of postoperative outcomes: A NSQIP multi-specialty surgical cohort analysis

AIM

While high estimated glomerular filtration rate (eGFR) has been associated with increased overall mortality, its effect on postoperative outcomes is relatively understudied. We sought to investigate the association between high eGFR and 30-day postoperative outcomes using a multi-specialty surgical cohort.

METHODS

Using the National Surgical Quality Improvement Program database, we selected adult for whom eGFR could be calculated using the 2021 Chronic Kidney Disease Epidemiology Collaboration equation. Based on sex-specific distributions of eGFR stratified by age quintiles, we classified patients into low (<5th percentile), normal (5-95th percentile) and high eGFR (>95th percentile). The primary outcome was a composite of any 30-day major adverse outcomes, including: death, reoperation, cardiac arrest, myocardial infarction and stroke. Secondary outcomes included 30-day infectious complications, venous thromboembolism (VTE), bleeding requiring transfusion, prolonged length of stay and unplanned readmission. After matching for demographic differences, comorbidity burden and operative characteristics, logistic regression models were used to evaluate the association between extremes of eGFR and the outcomes of interest.

RESULTS

Of 1 668 447 patients, 84 115 (5.07%) had a high eGFR. High eGFR was not associated with major adverse outcomes (odds ratio [OR] 1.00 [95% confidence interval (CI): 0.97, 1.03]); however, it was associated with reoperation (OR 1.04 [95% CI: 1.00,1.08]), infectious complications (OR 1.14 [95% CI: 1.11, 1.16]), VTE (OR 1.15 [95% CI: 1.09, 1.22]) and prolonged length of stay (OR 1.19 [95% CI: 1.16, 1.21]).

CONCLUSION

Our findings support an association between high eGFR and adverse 30-day postoperative outcomes.

Predicting outcomes in children with congenital anomalies of the kidney and urinary tract

BACKGROUND

Congenital anomalies of the kidney and urinary tract (CAKUT) are the most frequent causes of childhood chronic kidney disease (CKD). Using a large CAKUT cohort, we sought to identify the predictors of CKD and to develop a prediction model that informs a risk-stratified clinical pathway.

METHODS

This was a retrospective cohort study including cases with multicystic dysplastic kidneys (MCDK), unilateral kidney agenesis (UKA), kidney hypoplasia (KH), and posterior urethral valves (PUV). We identified risk factors for CKD (estimated glomerular filtration rate [eGFR] <60 ml/min/1.73 m2) and tested their performance in an adjusted multivariate binary regression model. Prediction probability scores for CKD were used to separate cases likely to develop complications from those not needing specialist follow-up.

RESULTS

We identified 452 eligible cases of CAKUT with 22% developing CKD. Strongest associations with CKD included primary diagnosis (OR 3.5, 95% CI 2.6-4.6), preterm delivery (OR 2.3, 95% CI 1.2-4.4), non-kidney anomalies (OR 1.8, 95% CI 1.1-3), first eGFR<90 (OR 8.9, 95% CI 4.4-18.1), small kidney size (OR 9, 95% CI 4.9-16.6), and additional kidney anomalies (OR 1.6, 95% CI 1.2-2.8). PUV (OR 4.7, 95% CI 1.5-15.3), first eGFR <90 (OR 4.4, 95% CI 2-9.7), and kidney length to body length ratio <7.9 (OR 4.2, 95% CI 1.9-9.2) were independent predictors of CKD. The regression model had a prediction accuracy of 80% and a prediction probability c-statistic of 0.81.

CONCLUSION

Using a large combined CAKUT cohort we identified risk factors for CKD. Our prediction model provides the first steps towards a risk-stratified clinical pathway. A higher resolution version of the Graphical abstract is available as Supplementary information.

Pharmacokinetic relevance of glomerular hyperfiltration for drug dosing

In chronic kidney disease (CKD) patients, hypofiltration may lead to the accumulation of drugs that are cleared mainly by the kidney and, vice versa, hyperfiltration may cause augmented renal excretion of the same drugs. In this review we mainly focus on the issue of whether hyperfiltration significantly impacts the renal clearance of drugs and whether the same alteration may demand an up-titration of the doses applied in clinical practice. About half of severely ill, septic patients and patients with burns show glomerular hyperfiltration and this may lead to enhanced removal of drugs such as hydrophilic antibiotics and a higher risk of antibiotic treatment failure. In general, hyperfiltering obese individuals show higher absolute drug clearances than non-obese control subjects, but this depends on the body size descriptor adopted to adjust for fat excess. Several mechanisms influence pharmacokinetics in type 2 diabetes, including renal hyperfiltration, reduced tubular reabsorption and augmented tubular excretion. However, no consistent pharmacokinetic alteration has been identified in hyperfiltering obese subjects and type 2 diabetics. Non-vitamin K antagonist oral anticoagulants (NOACs) have exhibited lower plasma concentrations in hyperfiltering patients in some studies in patients with atrial fibrillation, but a recent systematic review failed to document any excess risk for stroke and systemic embolism in these patients. Hyperfiltration is common among severely ill patients in intensive care units and drug levels should be measured whenever possible in these high-risk patients to prevent underdosing and treatment failure. Hyperfiltration is also common in patients with obesity or type 2 diabetes, but no consistent pharmacokinetic alteration has been described in these patients. No NOAC dose adjustment is indicated in patients with atrial fibrillation being treated with these drugs.

Long-Term Renal Function in Adult Patients with Phenylketonuria

INTRODUCTION

In phenylketonuria (PKU), toxic phenylalanine (Phe) can harm other organs beyond the brain. Furthermore, the lifelong therapy of PKU consists of consumption of increased amounts of amino-acid mixture that provoke hyperfiltration in the glomeruli. Therefore, the adherence to therapy in PKU might influence the long-term kidney function in PKU patients.

METHODS

Data from 41 adult, early treated PKU patients were analyzed in this 10-year, retrospective, monocentric study. Two subgroups were created according to their therapy adherence: one with long-term blood Phe levels in the therapeutic range (<600 µmol/L), and one with suboptimal blood Phe levels. Renal function and metabolic parameters were collected over 10 years. Kidney function parameters were compared between the two groups and associations between blood Phe levels and kidney function were tested.

RESULTS

After 10 years, serum creatinine levels (p = 0.369) and estimated glomerular filtration rate (eGFR) (p = 0.723) did not change significantly from baseline in the good therapeutic group. The suboptimal therapeutic group's eGFR decreased in the same period (from 110.4 ± 14 mL/min/1.73 m2 to 94.2 ± 16 mL/min/1.73 m2, p = 0.017). At 10 years, the suboptimal therapeutic group had an increased serum creatinine level (81 ± 14.4 μmol/L vs. 71.5 ± 13 μmol/L, p = 0.038), and a decreased eGFR (94.2 ± 16 mL/min/1.73 m2 vs. 103.3 ± 13 mL/min/1.73 m2p = 0.031) compared to the good adhering group. Significant negative correlation between Phe levels and eGFR (r = -0.41, p = 0.008) was observed.

CONCLUSION

Long-term suboptimal therapy adherence in PKU patients with high blood Phe levels may lead to deterioration in kidney function.

Pregnancy in Living Kidney Donors: An Evidence-Based Review

Purpose of review

To review the current studies and guidelines on the risk of adverse pregnancy outcomes in female kidney donors.

Recent findings

Living kidney donors include a significant amount of young women of child-bearing age. Safety and possible risks of pregnancy after donation are a concern for female kidney donor candidates. Many current studies indicate a higher risk of preeclampsia in women after kidney donation. Considering the increasing number of living kidney donors, the maternal outcomes of living kidney donation is an active area of research.

Summary

Guidelines and consensus statements on the risk of pregnancy in living kidney donors recommend close monitoring of blood pressure, weight gain, and proteinuria during pregnancy. Current studies indicate an increased risk of hypertensive disorders of pregnancy in living kidney donors. Counseling and informing donor candidates about the possible risks is important.

Low agreement between various eGFR formulae in pediatric and young adult ADPKD patients

BACKGROUND

Young autosomal dominant polycystic kidney disease (ADPKD) patients are becoming the new target population for the development of new treatment options. Determination of a reliable equation for estimated glomerular filtration rate (eGFR) from early stages is needed with the promising potential interventional therapies.

METHODS

Prospective and longitudinal study on a cohort of 68 genotyped ADPKD patients (age range 0-23 years) with long-term follow-up. Commonly used equations for eGFR were compared for their relative performance.

RESULTS

The revised Schwartz formula (CKiD) showed a highly significant decline in eGFR with aging (- 3.31 mL/min/1.73 m2/year, P < 0.0001). The recently updated equation by the Schwartz group (CKiDU25) showed a smaller (- 0.90 mL/min/1.73 m2/year) but significant (P = 0.001) decline in eGFR with aging and also showed a significant sex difference (P < 0.0001), not observed by the other equations. In contrast, the full age spectrum (FAS) equations (FAS-SCr, FAS-CysC, and the combined) showed no age and sex dependency. The prevalence of hyperfiltration is highly dependent on the formula used, and the highest prevalence was observed with the CKiD Equation (35%).

CONCLUSIONS

The most widely used methods to calculate eGFR in ADPKD children (CKiD and CKiDU25 equations) were associated with unexpected age or sex differences. The FAS equations were age- and sex-independent in our cohort. Hence, the switch from the CKiD to CKD-EPI equation at the transition from pediatric to adult care causes implausible jumps in eGFR, which could be misinterpreted. Having reliable methods to calculate eGFR is indispensable for clinical follow-up and clinical trials. A higher resolution version of the Graphical abstract is available as Supplementary information.

Trends in renal function in Northern Sweden 1986-2014: data from the seven cross-sectional surveys within the Northern Sweden MONICA study

OBJECTIVE

The prevalence of chronic kidney disease (CKD) is increasing globally, and CKD is closely related to cardiovascular disease (CVD). CKD and CVD share several risk factors (RF), such as diabetes, hypertension, obesity and smoking, and the prevalence of these RF has changed during the last decades, and we aimed to study the effect on renal function over time.

DESIGN

Repeated cross-sectional population-based studies.

SETTING

The two Northern counties (Norr- and Västerbotten) in Sweden.

PARTICIPANTS

Within the MONitoring Trends and Determinants of CArdiovascular Disease (MONICA) study, seven surveys were performed between 1986 and 2014, including participants aged 25-64 years (n=10 185).

INTERVENTIONS

None.

MEASURES

Information on anthropometry, blood pressure and cardiovascular risk factors was collected. Creatinine and cystatin C were analysed in stored blood samples and the estimated glomerular filtration rate (eGFR) calculated using the creatinine-based Lund-Malmö revised and Chronic Kidney Disease Epidemiology Collaboration (eGFRcrea) equations as well as the cystatin C-based Caucasian, Asian, Paediatric and Adult cohort (CAPA) equation (eGFRcysC). Renal function over time was analysed using univariable and multivariable linear regression models.

RESULTS

Renal function, both eGFRcrea and eGFRcysC, decreased over time (both p<0.001) and differed between counties and sexes. In a multivariable analysis, study year remained inversely associated with both eGFRcrea and eGFRcysC (both p<0.001) after adjustment for classical cardiovascular RF.

CONCLUSION

Renal function has deteriorated in Northern Sweden between 1986 and 2014.

Glomerular hyperfiltration and hypertrophy: an evaluation of maximum values in pathological indicators to discriminate "diseased" from "normal"

The success of sodium-glucose cotransporter 2 inhibitors and bariatric surgery in patients with chronic kidney disease has highlighted the importance of glomerular hyperfiltration and hypertrophy in the progression of kidney disease. Sustained glomerular hyperfiltration and hypertrophy can lead to glomerular injury and progressive kidney damage. This article explores the relationship between obesity and chronic kidney disease, focusing on the roles of glomerular hyperfiltration and hypertrophy as hallmarks of obesity-related kidney disease. The pathological mechanisms underlying this association include adipose tissue inflammation, dyslipidemia, insulin resistance, chronic systemic inflammation, oxidative stress, and overactivation of the sympathetic nervous system, as well as the renin-angiotensin aldosterone system. This article explains how glomerular hyperfiltration results from increased renal blood flow and intraglomerular hypertension, inducing mechanical stress on the filtration barrier and post-filtration structures. Injured glomeruli increase in size before sclerosing and collapsing. Therefore, using extreme values, such as the maximal glomerular diameter, could improve the understanding of the data distribution and allow for better kidney failure predictions. This review provides important insights into the mechanisms underlying glomerular hyperfiltration and hypertrophy and highlights the need for further research using glomerular size, including maximum glomerular profile, calculated using needle biopsy specimens.

Magnetic Resonance Imaging in Clinical Trials of Diabetic Kidney Disease

Chronic kidney disease (CKD) associated with diabetes mellitus (DM) (known as diabetic kidney disease, DKD) is a serious and growing healthcare problem worldwide. In DM patients, DKD is generally diagnosed based on the presence of albuminuria and a reduced glomerular filtration rate. Diagnosis rarely includes an invasive kidney biopsy, although DKD has some characteristic histological features, and kidney fibrosis and nephron loss cause disease progression that eventually ends in kidney failure. Alternative sensitive and reliable non-invasive biomarkers are needed for DKD (and CKD in general) to improve timely diagnosis and aid disease monitoring without the need for a kidney biopsy. Such biomarkers may also serve as endpoints in clinical trials of new treatments. Non-invasive magnetic resonance imaging (MRI), particularly multiparametric MRI, may achieve these goals. In this article, we review emerging data on MRI techniques and their scientific, clinical, and economic value in DKD/CKD for diagnosis, assessment of disease pathogenesis and progression, and as potential biomarkers for clinical trial use that may also increase our understanding of the efficacy and mode(s) of action of potential DKD therapeutic interventions. We also consider how multi-site MRI studies are conducted and the challenges that should be addressed to increase wider application of MRI in DKD.

Chronic intermittent hypoxia promotes glomerular hyperfiltration and potentiates hypoxia-evoked decreases in renal perfusion and PO2

Introduction: Sleep apnea (SA) is highly prevalent in patients with chronic kidney disease and may contribute to the development and/or progression of this condition. Previous studies suggest that dysregulation of renal hemodynamics and oxygen flux may play a key role in this process. The present study sought to determine how chronic intermittent hypoxia (CIH) associated with SA affects regulation of renal artery blood flow (RBF), renal microcirculatory perfusion (RP), glomerular filtration rate (GFR), and cortical and medullary tissue PO2 as well as expression of genes that could contribute to renal injury. We hypothesized that normoxic RBF and tissue PO2 would be reduced after CIH, but that GFR would be increased relative to baseline, and that RBF, RP, and tissue PO2 would be decreased to a greater extent in CIH vs. sham during exposure to intermittent asphyxia (IA, FiO2 0.10/FiCO2 0.03). Additionally, we hypothesized that gene programs promoting oxidative stress and fibrosis would be activated by CIH in renal tissue. Methods: All physiological variables were measured at baseline (FiO2 0.21) and during exposure to 10 episodes of IA (excluding GFR). Results: GFR was higher in CIH-conditioned vs. sham (p < 0.05), whereas normoxic RBF and renal tissue PO2 were significantly lower in CIH vs. sham (p < 0.05). Reductions in RBF, RP, and renal tissue PO2 during IA occurred in both groups but to a greater extent in CIH (p < 0.05). Pro-oxidative and pro-fibrotic gene programs were activated in renal tissue from CIH but not sham. Conclusion: CIH adversely affects renal hemodynamic regulation and oxygen flux during both normoxia and IA and results in changes in renal tissue gene expression.

Glomerulonephritis: immunopathogenesis and immunotherapy

'Glomerulonephritis' (GN) is a term used to describe a group of heterogeneous immune-mediated disorders characterized by inflammation of the filtration units of the kidney (the glomeruli). These disorders are currently classified largely on the basis of histopathological lesion patterns, but these patterns do not align well with their diverse pathological mechanisms and hence do not inform optimal therapy. Instead, we propose grouping GN disorders into five categories according to their immunopathogenesis: infection-related GN, autoimmune GN, alloimmune GN, autoinflammatory GN and monoclonal gammopathy-related GN. This categorization can inform the appropriate treatment; for example, infection control for infection-related GN, suppression of adaptive immunity for autoimmune GN and alloimmune GN, inhibition of single cytokines or complement factors for autoinflammatory GN arising from inborn errors in innate immunity, and plasma cell clone-directed or B cell clone-directed therapy for monoclonal gammopathies. Here we present the immunopathogenesis of GN and immunotherapies in use and in development and discuss how an immunopathogenesis-based GN classification can focus research, and improve patient management and teaching.

MAFLD and Glomerular Hyperfiltration in Subjects with Prediabetes, Visceral Obesity and "Preserved" Kidney Function:A Cross-Sectional Study

AIMS

To investigate the prevalence of metabolic dysfunction-associated fatty liver disease (MAFLD) in prediabetes, visceral obesity, and preserved kidney function, and explore whether MAFLD is associated with hyperfiltration.

METHODS

We analyzed data from 6697 Spanish civil servants, aged 18-65 years, with fasting plasma glucose ≥100 and ≤125 mg/dL (prediabetes, ADA), waist circumference ≥94 cm in men and ≥80 cm in women (visceral obesity, IDF) and de-indexed estimated glomerular filtration rate (eGFR) ≥60 mL/min, collected during occupational health visits. The association between MAFLD and hyperfiltration (eGFR >age- and sex-specific 95^th percentile) was tested by multivariable logistic regression analyses.

RESULTS

Overall, 4213 patients (62.9%) had MAFLD, and 330 (4.9%) were hyperfiltering. MAFLD was more frequent in hyperfiltering than in non-hyperfiltering subjects (86.4% vs 61.7%, P<0.001). BMI, waist circumference, systolic, diastolic, mean arterial pressure, and prevalence of hypertension were higher in hyperfiltering than in non-hyperfiltering subjects (P<0.05). MAFLD was independently associated with hyperfiltration, even after adjusting for common confounders [OR (95% CI): 3.36 (2.33-4.84), P<0.001]. In stratified analyses MAFLD potentiated age-related eGFR decline vs. non-MAFLD (P<0.001).

CONCLUSIONS

More than half of subjects with prediabetes, visceral obesity and eGFR ≥60 ml/min presented MAFLD that was associated with hyperfiltration and potentiated the age-related eGFR decline.

Pregnancy-related hemodynamic biomarkers in relation to trimester-specific maternal per - and polyfluoroalkyl substances exposures and adverse birth outcomes

The fate of environmental chemicals in maternal and fetal tissues might be affected by pregnancy-related hemodynamic changes that occur across gestation. Specifically, hemodilution and renal function are hypothesized to confound associations between per- and polyfluoroalkyl substances (PFAS) exposure measures in late pregnancy with gestational length and fetal growth. We sought to analyze two pregnancy-related hemodynamic biomarkers, creatinine and estimated glomerular filtration rate (eGFR), as confounders of the trimester-specific relationships between maternal serum PFAS concentrations and adverse birth outcomes. Participants were enrolled in the Atlanta African American Maternal-Child Cohort between 2014 and 2020. Biospecimens were collected at up to two timepoints, which were categorized into the 1st trimester (N = 278; 11 mean weeks gestation), 2nd trimester (N = 162; 24 mean weeks gestation), and 3rd trimester (N = 110; 29 mean weeks gestation). We quantified six PFAS in serum, creatinine in serum and urine, and eGFR using the Cockroft-Gault equation. Multivariable regression models estimated the associations between single PFAS and their sum with gestational age at delivery (weeks), preterm birth (PTB, <37 gestational weeks), birthweight z-scores, and small for gestational age (SGA). Primary models were adjusted for sociodemographics. We additionally adjusted for serum creatinine, urinary creatinine, or eGFR in the confounding assessments. An interquartile range increase in perfluorooctanoic acid (PFOA) produced a non-significant reduction in birthweight z-score during the 1st and 2nd trimesters (β = -0.01 g [95% CI = -0.14, 0.12] and β = -0.07 g [95% CI = -0.19, 0.06], respectively) whereas the relationship was significant and positive during the 3rd trimester (β = 0.15 g; 95% CI = 0.01, 0.29). Trimester-specific effects were similar for the other PFAS and adverse birth outcomes, which persisted after adjusting for creatinine or eGFR. The relationships between prenatal PFAS exposure and adverse birth outcomes were not strongly confounded by renal function or hemodilution. However, 3rd trimester samples consistently exhibited different effects than those collected during the 1st and 2nd trimesters.

Studies in Zebrafish and Rat Models Support Dual Blockade of EP2 and EP4 (Prostaglandin E2 Receptors Type 2 and 4) for Renoprotection in Glomerular Hyperfiltration and Albuminuria

BACKGROUND

Glomerular hyperfiltration (GH) is an important mechanism in the development of albuminuria in hypertension. Upregulation of COX2 (cyclooxygenase 2) and prostaglandin E₂ (PGE₂) was linked to podocyte damage in GH. We explored the potential renoprotective effects of either separate or combined pharmacological blockade of EP2 (PGE₂ receptor type 2) and EP4 (PGE₂ receptor type 4) in GH.

METHODS

We conducted in vivo studies in a transgenic zebrafish model (Tg[fabp10a:gc-EGFP]) suitable for analysis of glomerular filtration barrier function and a genetic rat model with GH, albuminuria, and upregulation of PGE₂. Similar pharmacological interventions and primary outcome analysis on albuminuria phenotype development were conducted in both model systems.

RESULTS

Stimulation of zebrafish embryos with PGE₂ induced an albuminuria-like phenotype, thus mimicking the suggested PGE₂ effects on glomerular filtration barrier dysfunction. Both separate and combined blockade of EP2 and EP4 reduced albuminuria phenotypes in zebrafish and rat models. A significant correlation between albuminuria and podocyte damage in electron microscopy imaging was identified in the rat model. Dual blockade of both receptors showed a pronounced synergistic suppression of albuminuria. Importantly, this occurred without changes in arterial blood pressure, glomerular filtration rate, or tissue oxygenation in magnetic resonance imaging, while RNA sequencing analysis implicated a potential role of circadian clock genes.

CONCLUSIONS

Our findings confirm a role of PGE₂ in the development of albuminuria in GH and support the renoprotective potential of combined pharmacological blockade of EP2 and EP4 receptors. These data support further translational research to explore this therapeutic option and a possible role of circadian clock genes.

SUMO specific peptidase 6 regulates the crosstalk between podocytes and glomerular endothelial cells in diabetic kidney disease

There is increasing evidence that the crosstalk between podocytes and glomerular endothelial cells (GECs) exacerbates the progression of diabetic kidney disease (DKD). Here, we investigated the underlying role of SUMO specific peptidase 6 (SENP6) in this crosstalk. In the diabetic mice, SENP6 was decreased in glomerular tissues and its knockdown further exacerbated glomerular filtration barrier injury. In the mouse podocyte cell line MPC5 cells, SENP6 overexpression reversed HG-induced podocyte loss by suppressing the activation of Notch1 signaling. Notch1 intracellular domain (N1ICD) is the active form of Notch1. SENP6 upregulated the ubiquitination of N1ICD by deSUMOylating Notch1, thereby reducing N1ICD and suppressing Notch1 signaling activation in MPC5 cells. Endothelin-1 (EDN1) is a protein produced by podocytes and has been reported to promote GEC dysfunction. The supernatant from HG-treated MPC5 cells induced mitochondrial dysfunction and surface layer injury in GECs, and the supernatant from SENP6-deficient podocytes further exacerbated the above GEC dysfunction, while this trend was reversed by an EDN1 antagonist. The following mechanism study showed that SENP6 deSUMOylated KDM6A (a histone lysine demethylase) and then decreased the binding potency of KDM6A to EDN1. The latter led to the upregulation of H3K27me2 or H3K27me3 of EDN1 and suppressed its expression in podocytes. Taken together, SENP6 suppressed the HG-induced podocyte loss and ameliorated GEC dysfunction caused by crosstalk between podocytes and GECs, and the protective effect of SENP6 on DKD is attributed to its deSUMOylation activity.

The CARDINAL Trial of Bardoxolone Methyl in Alport Syndrome: When Marketing Interests Prevail over Patients Clinical Needs

CONTEXT

Alport syndrome (AS) is a hereditary chronic kidney disease (CKD) with X-linked, autosomal, and digenic patterns of transmission. Sieving dysfunction of the glomerular basement membrane caused by congenitally defective type IV collagen results in persistent proteinuria, hematuria, and progressive renal dysfunction. There are no disease-specific medications and treatment is based on conservative interventions in particular with renin-angiotensin-aldosterone-system (RAAS) inhibitors. Subject of Review: Evidence that AS is accompanied by glomerular and tubular inflammatory changes and that bardoxolone methyl exerts anti-inflammatory effects through suppression of NF-kB and activation of transcription of antioxidant and anti-inflammatory genes, provided a justification for the CARDINAL study, a prospective, randomized controlled trial testing the potential renoprotective effect of bardoxolone methyl in 157 adolescent or adult patients with AS. The authors concluded that bardoxolone methyl preserved estimated glomerular filtration rate (eGFR) relative to placebo at 48 and 100 weeks after randomization. However, exactly the same number of patients (n = 3) in each group developed kidney failure. Second Opinion: Despite alarming safety signals from previous trials in type 2 diabetics with CKD (increased hospitalizations for heart failure, fatal and nonfatal cardiovascular events, liver toxicity, and increased blood pressure and albuminuria), major marketing interests encouraged the drug manufacturer to pursue this line of research. Finding that type IV collagen gene mutations account for nearly one-third of cases of hereditary glomerulopathies implies that the population of potential target-patients could probably be much larger than estimated. Moreover, any new medication approved for AS might receive orphan drug designation which might be associated with shortened time to approval, monetary benefits, and a period of market exclusivity. In actual facts, CARDINAL failed to demonstrate any nephro-protective effect of bardoxolone methyl and found an increase in liver enzymes in 70 of the 77 (90.9%) bardoxolone-treated patients consistent with chronic liver toxicity. Indeed, in Zucker diabetic fatty rats treated with an analog of bardoxolone methyl, elevations of liver aminotransferases were associated with enhanced liver weight, severe and diffuse hepatocyte vacuolization, swelling, and degeneration. Moreover, bardoxolone-induced increase in eGFR was associated with a concomitant increase in geometric mean urinary albumin/creatinine ratio, a finding consistent with worsening glomerular hyperfiltration. Considering also the consequent increase in the biomechanical strain on the fragile Alport glomerular basement membrane, this hemodynamic effect is expected to translate into accelerated renal disease progression (consistently with evidence that a bardoxolone methyl analog worsened proteinuria, glomerulosclerosis, and tubular damage in Zucker diabetic fatty rats). These concerns induced the Food and Drug Administration to reject the new drug application for bardoxolone methyl submitted by Reata Pharmaceuticals, Inc. with the proposed indication to slow CKD progression in AS patients 12 years of age and older. Thus, bardoxolone methyl is devoid of any nephro-protective effect and is associated with significant heart, liver, and renal toxicity in patients with CKD, including those with AS. Because of these safety signals, it should not be used in this clinical context. Research programs could explore the potential clinical applications, even outside the kidney field, of novel NF erythroid 2-like 2 modulators devoid of bardoxolone methyl toxicity.

Effects of Octreotide-Long-Acting Release Added-on Tolvaptan in Patients with Autosomal Dominant Polycystic Kidney Disease: Pilot, Randomized, Placebo-Controlled, Cross-Over Trial

BACKGROUND

Tolvaptan and octreotide-long-acting release (LAR) have renoprotective effects in autosomal dominant polycystic kidney disease (ADPKD) that are partially mediated by amelioration of compensatory glomerular hyperfiltration. We compared the effects of tolvaptan and octreotide-LAR combination therapy versus those of tolvaptan monotherapy in patients with ADPKD.

METHODS

This pilot, randomized, placebo-controlled, cross-over trial primarily compared the effects of 1- and 4-week treatments with octreotide-LAR (two 20-mg i.m. injections) or placebo (two i.m. 0.9% saline solution injections) added-on tolvaptan (up to 90 and 30 mg/d) on GFR (iohexol plasma clearance) in 19 consenting patients with ADPKD referred to a clinical research center in Italy. Analyses were intention-to-treat. The local ethical committee approved the study.

RESULTS

At 4 weeks, GFR significantly decreased by a median (interquartile range) of 3 (-1 to 5) ml/min per 1.73 m2 with tolvaptan and placebo (P=0.01) and by 7 (3-14) ml/min per 1.73 m2 with tolvaptan and octreotide-LAR (P=0.03). GFR changes during the two treatment periods differed by 2 (-5 to 14) ml/min per 1.73 m2 (P=0.28). At 1 week, GFR significantly decreased by 3 (0-7) ml/min per 1.73 m2 with tolvaptan and placebo (P=0.006) and by 10 (-6 to 16) ml/min per 1.73 m2 with tolvaptan and octreotide-LAR add-on therapy (P<0.001). GFR changes during the two treatment periods significantly differed by 3 (0-12) ml/min per 1.73 m2 (P=0.012). Total kidney volume nonsignificantly changed by 4 (-48 to 23) ml with tolvaptan and placebo (P=0.74), whereas it decreased significantly by 41 (25-77) ml with tolvaptan and octreotide-LAR (P=0.001). Changes during the two treatment periods differed by 36 (0-65) ml (P=0.01). Octreotide-LAR also attenuated (P=0.02) the aquaretic effect of tolvaptan. Treatments were well tolerated.

CONCLUSIONS

In patients with ADPKD, octreotide-LAR added-on tolvaptan reduced GFR more effectively than octreotide-LAR and placebo. Octreotide-LAR also reduced total and cystic kidney volumes and attenuated the acquaretic effect of tolvaptan.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Tolvaptan-Octreotide LAR Combination in ADPKD (TOOL), NCT03541447.

Glomerular hyperfiltration is a predictor of adverse outcomes following major urologic oncology surgery

PURPOSE

Glomerular hyperfiltration (GHF) has been associated with cardiovascular disease and all-cause mortality. We aimed to evaluate whether preoperative GHF is associated with 30-day complications following major urologic oncology procedures.

METHODS

We conducted a retrospective cohort study using subjects from the 2006 to 2019 American College of Surgeons National Surgical Quality Improvement Program database who underwent prostatectomy, cystectomy, or nephrectomy. Estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI equation. Patients were classified as having either low, normal, or high eGFR based on the 5th and 95th percentiles of age- and sex-specific quintiles for eGFR. Using multivariable logistic regression, we evaluated GHF as an independent predictor of postoperative complications.

RESULTS

A total of 120,013 patients were eligible for analysis, of which 1706 (1.4%) were identified as having GHF, with a median eGFR of 105.37 ml/min per 1.73 m² (IQR 94.84-116.77). Compared to patients with normal eGFR, patients with GHF were older (68 years, [IQR 60-71], p < 0.001), had a lower BMI (27.52 kg/m² [IQR 23.71-31.95], p < 0.001), and greater 5-item modified frailty index scores (≥ 1, 70.6%, p < 0.001). Multivariable logistic regression demonstrated that GHF was associated with greater odds of any complication (OR 1.23, 95% CI 1.08-1.40, p = 0.002), non-home discharge (OR 1.86, 95% CI 1.50-2.30, p < 0.001), and prolonged LOS (OR 1.33, 95% CI 1.18-1.51, p < 0.001).

CONCLUSION

GHF is associated with greater odds of 30-day complications following major urologic oncology surgery.

The Bidirectional Relationship between Chronic Kidney Disease and Hyperuricemia: Evidence from a Population-Based Prospective Cohort Study

BACKGROUND

Although several studies have examined the association between chronic kidney disease (CKD) and hyperuricemia (HUA), the direction of the association remains unclear. We aimed to investigate whether there was a bidirectional association between them.

METHODS

The present study was conducted in three analyses. Analysis I included 25,433 participants free of HUA at baseline to evaluate the associations between CKD and estimated glomerular filtration rate (eGFR) with incident HUA. Analysis II had 28,422 participants free of CKD at baseline to analyze the relationships between HUA and serum uric acid (sUA) with new-onset CKD. Cox proportional hazards regression models were applied to evaluate the association involved in Analysis I and II. Analysis III included 31,028 participants with complete data and further dissected the bidirectional association between sUA and eGFR using cross-lag models.

RESULTS

New-onset HUA and CKD were observed in the first round of the follow-up study among 1597 and 1212 participants, respectively. A significantly higher risk of HUA was observed in individuals with CKD compared to individuals without CKD (HR = 1.58, 95% CI: 1.28-1.95). The adjusted HRs (95% CIs) of HUA were 3.56 (2.50-5.05) for the participants in the group of eGFR less than 60 mL·min^-1·1.73 m^-2, 1.61 (1.42-1.83) for those in the group of eGFR between 60 and 90 mL·min^-1·1.73 m^-2, and 1.74 (1.42-2.14) for those in the group of eGFR more than 120 mL·min^-1·1.73 m^-2, compared with the group of eGFR between 90 and 120 mL·min^-1·1.73 m^-2. A higher risk of CKD was also observed in individuals with HUA compared to individuals without HUA (HR = 1.28, 95% CI: 1.12-1.47). Compared with the first quintile of sUA, the adjusted HR (95% CI) of CKD was 1.24 (1.01-1.51) for the participants in the fourth quantile. There was a bidirectional relationship between sUA and eGFR, with the path coefficients (ρ₁ = -0.024, p < 0.001) from baseline eGFR to follow-up sUA and the path coefficients (ρ₂ = -0.015, p = 0.002) from baseline sUA to follow-up eGFR.

CONCLUSIONS

The present study indicated that CKD and HUA were closely associated, and there was a bidirectional relationship between sUA and eGFR.

Long-Term Effects of Severe Burns on the Kidneys: Research Advances and Potential Therapeutic Approaches

Burns are a seriously underestimated form of trauma that not only damage the skin system but also cause various complications, such as acute kidney injury (AKI). Recent clinical studies have shown that the proportion of chronic kidney diseases (CKD) in burn patients after discharge is significantly higher than that in the general population, but the mechanism behind this is controversial. The traditional view is that CKD is associated with hypoperfusion, AKI, sepsis, and drugs administered in the early stages of burns. However, recent studies have shown that burns can cause long-term immune dysfunction, which is a high-risk factor for CKD. This suggests that burns affect the kidneys more than previously recognized. In other words, severe burns are not only an acute injury but also a chronic disease. Neglecting to study long-term kidney function in burn patients also results in a lack of preventive and therapeutic methods being developed. Furthermore, stem cells and their exosomes have shown excellent comprehensive therapeutic properties in the prevention and treatment of CKD, making them increasingly the focus of research attention. Their engineering strategy further improved the therapeutic performance. This review will focus on the research advances in burns on the development of CKD, illustrating the possible mechanism of burn-induced CKD and introducing potential biological treatment options and their engineering strategies.

Ion channels and channelopathies in glomeruli

An essential step in renal function entails the formation of an ultrafiltrate that is delivered to the renal tubules for subsequent processing. This process, known as glomerular filtration, is controlled by intrinsic regulatory systems and by paracrine, neuronal, and endocrine signals that converge onto glomerular cells. In addition, the characteristics of glomerular fluid flow, such as the glomerular filtration rate and the glomerular filtration fraction, play an important role in determining blood flow to the rest of the kidney. Consequently, disease processes that initially affect glomeruli are the most likely to lead to end-stage kidney failure. The cells that comprise the glomerular filter, especially podocytes and mesangial cells, express many different types of ion channels that regulate intrinsic aspects of cell function and cellular responses to the local environment, such as changes in glomerular capillary pressure. Dysregulation of glomerular ion channels, such as changes in TRPC6, can lead to devastating glomerular diseases, and a number of channels, including TRPC6, TRPC5, and various ionotropic receptors, are promising targets for drug development. This review discusses glomerular structure and glomerular disease processes. It also describes the types of plasma membrane ion channels that have been identified in glomerular cells, the physiological and pathophysiological contexts in which they operate, and the pathways by which they are regulated and dysregulated. The contributions of these channels to glomerular disease processes, such as focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, as well as the development of drugs that target these channels are also discussed.

Cardiovascular Risk Related to Glomerular Hyperfiltration in Nondiabetic Individuals: Increasing Visibility is Crucial

Glomerular hyperfiltration (GHF), defined by different estimation formulas, has been widely studied as a predictor of proteinuria and progression to chronic kidney disease (CKD) in diabetic patients. GHF is also an important cardiovascular (CV) risk factor and is related to allcause mortality in non-diabetic populations; however, the upper limit of glomerular filtration rate (GFR) above which it indicates the presence of GHF is weakly defined. This higher risk is as high as in the intermediate stages of CKD and is greater than the presence of diabetes or smoking and is still present in non-albuminuria patients. The original Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) estimation GFR formula showed lower error at higher glomerular filtration (GF) values, was the most used in population studies, and behaved as a better risk predictor. In our review (including approximately 3.6 million individuals), higher GFR values related to increased mortality risk varied from 106.6 to 113.7 ml/min, which are usually not considered risk values for standard guidelines in non-albuminuric patients. However, the lack of consensus on a GF cutoff value, as well as its variability due to sex and progressive reduction with age, affect the knowledge of this serious phenomenon in clinical practice. Although the elderly population is not exempted from the effects of GHF, the search for this phenomenon should be intensified in middle-aged populations because of their lower disease burden, where this situation may be more evident, and the possibility of reversing the consequences is greater. A population group often considered healthy includes obese people, essential hypertensives, smokers, and carriers of fatty liver, where the GHF phenomenon is frequent and is associated with CV disease, kidney disease, and higher mortality. Increasing its visibility by the medical community is essential to reduce the effects of GHF, emphasizing more frequent controls and implementing general measures that include strict control of hypertension, Na restriction, rich in vegetables diets and increased physical activity. Initiatives to confirm the beneficial effects of sodium-glucose cotransporter-2 inhibitors to treat isolated GHF would be an important breakthrough in reducing the severe consequences of this phenomenon.