Krüppel-like factor 2 is an endoprotective transcription factor in diabetic kidney disease.

Diabetic kidney disease (DKD) is a microvascular complication of diabetes, and glomerular endothelial cell (GEC) dysfunction is a key driver of DKD pathogenesis. Krüppel-like factor 2 (KLF2), a shear stress-induced transcription factor, is among the highly regulated genes in early DKD. In the kidney, KLF2 expression is mostly restricted to endothelial cells, but its expression is also found in immune cell subsets. KLF2 expression is upregulated in response to increased shear stress by the activation of mechanosensory receptors but suppressed by inflammatory cytokines, both of which characterize the early diabetic kidney milieu. KLF2 expression is reduced in progressive DKD and hypertensive nephropathy in humans and mice, likely due to high glucose and inflammatory cytokines such as TNF-α. However, KLF2 expression is increased in glomerular hyperfiltration-induced shear stress without metabolic dysregulation, such as in settings of unilateral nephrectomy. Lower KLF2 expression is associated with CKD progression in patients with unilateral nephrectomy, consistent with its endoprotective role. KLF2 confers endoprotection by inhibition of inflammation, thrombotic activation, and angiogenesis, and thus KLF2 is considered a protective factor for cardiovascular disease (CVD). Based on similar mechanisms, KLF2 also exhibits renoprotection, and its reduced expression in endothelial cells worsens glomerular injury and albuminuria in settings of diabetes or unilateral nephrectomy. Thus KLF2 confers endoprotective effects in both CVD and DKD, and its activators could potentially be developed as a novel class of drugs for cardiorenal protection in diabetic patients.

MAFLD and glomerular hyperfiltration in subjects with normoglycemia, prediabetes and type 2 diabetes: A cross-sectional population study.

BACKGROUND: Metabolic dysfunction-associated fatty liver disease (MAFLD, 2020 diagnostic criteria) and glomerular hyperfiltration share common risk factors, including obesity, insulin resistance, impaired glucose tolerance, diabetes, dyslipidemia, and hypertension. AIMS: To assess the prevalence of MAFLD and its association with glomerular hyperfiltration and age-related worsening of kidney function in subjects with normoglycemia, prediabetes and type 2 diabetes mellitus (T2DM). METHODS: We analysed data recorded during occupational health visits of 125,070 Spanish civil servants aged 18-65 years with a de-indexed glomerular filtration rate (GFR) estimated with the chronic-kidney-disease-epidemiological (CKD-EPI) equation (estimated glomerular filtration rate [eGFR]) ≥60 mL/min. Subjects were categorised according to fasting plasma glucose levels <100 mg/dL (normoglycemia), ≥100 and ≤ 125 mg/dL (prediabetes), or ≥126 mg/dL and/or antidiabetic treatment (T2DM). The association between MAFLD and glomerular hyperfiltration, defined as a de-indexed eGFR above the age- and gender-specific 95th percentile, was assessed by multivariable logistic regression. RESULTS: In the whole study group, MAFLD prevalence averaged 19.3%. The prevalence progressively increased from 14.7% to 33.2% and to 48.9% in subjects with normoglycemia, prediabetes and T2DM, respectively (p < 0.001 for trend). Adjusted odds ratio (95% CI) for the association between MAFLD and hyperfiltration was 9.06 (8.53-9.62) in the study group considered as a whole, and 8.60 (8.03-9.21), 9.52 (8.11-11.18) and 8.31 (6.70-10.30) in subjects with normoglycemia, prediabetes and T2DM considered separately. In stratified analyses, MAFLD amplified age-dependent eGFR decline in all groups (p < 0.001). CONCLUSIONS: MAFLD prevalence increases across the glycaemic spectrum. MAFLD is significantly associated with hyperfiltration and amplifies the age-related eGFR decline.

Prevalence and risk factors of glomerular hyperfiltration in adults with type 2 diabetes: A population-based study.

AIMS: Glomerular hyperfiltration characterises the earliest stage of diabetic nephropathy and predicts adverse kidney and cardiovascular outcomes. We aimed to assess the prevalence and risk factors of glomerular hyperfiltration in a population-based contemporary cohort of individuals with type 2 diabetes (T2D). MATERIALS AND METHODS: The prevalence of unequivocal glomerular hyperfiltration (defined by an estimated glomerular filtration rate >120 mL/min/1.73 m2 ) and its associated risk factors were identified in a cohort of 202,068 adult patients with T2D receiving specialist care in 2021-2022, whose center-aggregated data were automatically extracted from electronic medical records of 75 diabetes clinics in Italy. RESULTS: Glomerular hyperfiltration was identified in 1262 (0.6%) participants. The prevalence of glomerular hyperfiltration varied widely across centers (0%-3.4%) and correlated with mean center age, HbA1c , body mass index (BMI), and low-density lipoprotein cholesterol. Patients in centers with high glomerular hyperfiltration prevalence (>0.8%) were more often men and had lower age and BMI, but more frequent albuminuria and worse glucose, lipid, and blood pressure control, compared with low-normal prevalence centers. CONCLUSIONS: Unequivocal glomerular hyperfiltration can be identified in up to 3.4% of patients receiving up-to-date specialist diabetes care. Glomerular hyperfiltration prevalence varies across centers and substantially increases with suboptimal control of metabolic risk factors, which would require improved management to mitigate the negative health consequences of this pathological condition.

Glomerular hyperfiltration as a therapeutic target for CKD.

The global burden of chronic kidney disease (CKD) is high and increasing. Early diagnosis and intervention are key to improve outcomes. Single-nephron glomerular hyperfiltration is an early pathophysiologic manifestation of CKD that may result in absolute glomerular hyperfiltration, i.e. a high glomerular filtration rate (GFR), or be associated with normal or low GFR because of nephron loss (relative glomerular hyperfiltration). Even though compensatory glomerular hyperfiltration may contribute to maintain kidney function after the loss of kidney mass, the associated increased glomerular capillary pressure and glomerular and podocyte size drive podocyte loss, albuminuria and proximal tubular overload, contributing to CKD progression. In this regard, all kidney protective drugs in clinical use so far, from renin-angiotensin system blockers to mineralocorticoid receptor blockers to sodium-glucose co-transporter 2 inhibitors to tolvaptan, induce an early dip in glomerular filtration that is thought to represent reversal of hyperfiltration. As glomerular hyperfiltration may be present early in the course of kidney disease, its recognition may provide an effective intervention window that may predate current criteria based on high albuminuria or loss of GFR. Nevertheless, there is no diagnostic method with high sensitivity and specificity to identify single-nephron glomerular hyperfiltration, except when it leads to obvious absolute glomerular hyperfiltration, as observed in the early stages of diabetic kidney disease when nephron mass is still preserved. We now review the concept of glomerular hyperfiltration as an indicator of CKD risk, including definitions, challenges in diagnosis and evaluation, underlying pathophysiological mechanisms, potential therapeutic approaches and unanswered questions.

Pre-transplant glomerular hyperfiltration is not a risk factor for increased renal morbidity and mortality in pediatric stem cell transplant patients.

Low glomerular filtration rate (GFR) prior to stem cell transplant (SCT) is associated with increased morbidity and mortality. The implications of abnormally high GFRs, or glomerular hyperfiltration, prior to SCT are unknown. Twenty-two of 74 consecutive pediatric SCT patients over 2 years old at a single center were hyperfiltrating prior to SCT, median nuclear medicine GFR 154 mL/min/1.73 m2 [interquartile range: 146-170]. There was no association between hyperfiltration and any transplant demographics, nor between hyperfiltration and acute kidney injury (p = .8), renal replacement therapy (p = .63), 1-year event-free survival (p = 1), or abnormal creatinine-based estimated GFR at a median follow-up of 4.7 years (p = .73).

The Relationship of Alcohol Consumption and Drinking Pattern to the Risk of Glomerular Hyperfiltration in Middle-aged Japanese Men: The Kansai Healthcare Study.

BACKGROUND: Glomerular hyperfiltration has been reported to be associated with adverse renal outcomes in the general population. It is not known whether drinking pattern is associated with the risk of glomerular hyperfiltration in healthy individuals. METHODS: We prospectively followed middle-aged 8,640 Japanese men with normal renal function, no proteinuria, no diabetes, and no use of antihypertensive medications at entry. Data on alcohol consumption were gathered by questionnaire. Glomerular hyperfiltration was defined as estimated glomerular filtration rate (eGFR) ≥117 mL/min/1.73 m2, which was the upper 2.5th percentile value of eGFR in the entire cohort. RESULTS: During 46,186 person-years of follow-up, 330 men developed glomerular hyperfiltration. In a multivariate model, for men who consumed alcohol on 1-3 days per week, alcohol consumption of ≥69.1 g ethanol/drinking day was significantly associated with the risk of glomerular hyperfiltration (hazard ratio [HR] 2.37; 95% confidence interval [CI], 1.18-4.74) compared with non-drinkers. For those who consumed alcohol on 4-7 days per week, higher alcohol consumption per drinking day was associated with a higher risk of glomerular hyperfiltration: the HRs for alcohol consumption of 46.1-69.0, and ≥69.1 g ethanol/drinking day were 1.55 (95% CI, 1.01-2.38), and 1.78 (95% CI, 1.02-3.12), respectively. CONCLUSION: For high drinking frequency per week, more alcohol intake per drinking day was associated with an increased risk of glomerular hyperfiltration, while for low drinking frequency per week, only very high alcohol intake per drinking day was associated with an increased risk of glomerular hyperfiltration in middle-aged Japanese men.

Favorable changes in the eGFR slope after dapagliflozin treatment and its association with the initial dip.

BACKGROUND: Renoprotective effects of sodium glucose transporter 2 (SGLT2) inhibitors, including dapagliflozin, were observed in randomized controlled trials (RCTs). The suspected underlying mechanism is a correction of hyperfiltration, observed as an "initial dip". Whether SGLT2 inhibitors can attenuate the rate of decline in the estimated glomerular filtration rate (eGFR) in clinical settings, even when considering the pre-treatment decline rate, is unknown. Although several RCTs identified an association between the initial dip and long-term renal prognoses, a conclusion has not been reached. METHODS: We collected the eGFR data of patients for whom dapagliflozin was initiated in our hospital and then calculated their eGFR slopes before and after the start of the treatment. We investigated the changes in the eGFR slopes (ΔeGFR slope) and the association between the ΔeGFR slope and the initial dip. Risks for rapid eGFR decliners (eGFR slope < - 3 mL/min/1.73 m2/year) were also examined. RESULTS: The eGFR slope was significantly milder after dapagliflozin treatment (p < 0.01). A deeper initial dip was associated with a milder rate of eGFR decline (adjusted beta: - 0.29, p < 0.001). Dapagliflozin treatment reduced the proportion of rapid eGFR decliners from 52.9 to 14.7%, and a smaller initial dip was identified as a significant risk for post-treatment rapid eGFR decline (adjusted odds ratio: 1.73, p < 0.05). CONCLUSIONS: Compared to before the administration of dapagliflozin, the rate of eGFR decline was significantly milder after its administration. The initial dip was significantly associated with long-term renoprotective effects and may be a useful predictor of treatment response.

Prevalence and associated factors of glomerular hyperfiltration among adult stable sickle cells in Kinshasa, DR Congo.

INTRODUCTION: Glomerular hyperfiltration is highly frequent, theoretically dependent on cardiac output, low systemic vascular resistance and hemolysis markers. In sickle cell disease (SCD), hyperfiltration is an extremely common phenomenon and occurred in young and early adult patients. Despite the fact that the glomerular hyperfiltration is known as the early manifestations of sickle cell nephropathy, its burden among adult sickle cell disease in sub-Saharan is poor studied. This study aimed to determine the prevalence and associated factors of hyperfiltration. METHODS: This was an analytical multicentric cross-sectional study involving stable adult sickle cell patients in Kinshasa, recruited between March and October 2023. Parameters of interest encompasses demographic, clinical, biological, echocardiographic and pulse wave measurement data. Hyperfiltration was defined using the CDK-EPI equation based on cystatin C; eGFR >130 for women and >140 ml/min/1.73m2 for men. We used multivariate logistic regression analysis to search determinants of glomerular hyperfiltration. RESULTS: Two hundred and fourty six (246) patients with SCD were enrolled. The prevalence of hyperfiltration was 20.7%. In multiple logistic regression analysis, hyperfiltration status was independently associated with age (< 25 years) [3.57 (1.78-7.49); p = 0.027)], female sex [4.36 (2.55-5.62); p = 0.031), CRP (< 6 mg/l) [0.77 (0.61-0.97); p = 0.028)], central systolic pressure (< 100 mmHg) and central diastolic pressure (< 60 mmHg) [0.86(0.74-0.98), p = 0.028)], [(0.83 (0.71-0.98); p = 0.032)]. CONCLUSION: One out of five SS adults exhibits hyperfiltration, which is associated with young age and female sex, whereas low CRP and blood pressure were negative risk factors.

A Cross-Sectional Study of Glomerular Hyperfiltration in Polycystic Ovary Syndrome.

Glomerular hyperfiltration (GH) has been reported to be higher in women with polycystic ovary syndrome (PCOS) and is an independent risk factor for renal function deterioration, metabolic, and cardiovascular disease. The aim of this study was to determine GH in type A PCOS subjects and to identify whether inflammatory markers, markers of CKD, renal tubule injury markers, and complement system proteins were associated. In addition, a secondary cohort study was performed to determine if the eGFR had altered over time. In this comparative cross-sectional analysis, demographic, metabolic, and proteomic data from Caucasian women aged 18-40 years from a PCOS Biobank (137 with PCOS, 97 controls) was analyzed. Slow Off-rate Modified Aptamer (SOMA)-scan plasma protein measurement was undertaken for inflammatory proteins, serum markers of chronic kidney disease (CKD), tubular renal injury markers, and complement system proteins. A total of 44.5% of the PCOS cohort had GH (eGFR ≥ 126 mL/min/1.73 m2 (n = 55)), and 12% (n = 17) eGFR ≥ 142 mL/min/1.73 m2 (super-GH(SGH)). PCOS-GH women were younger and had lower creatinine and urea versus PCOS-nonGH. C-reactive protein (CRP), white cell count (WCC), and systolic blood pressure (SBP) were higher in PCOS versus controls, but CRP correlated only with PCOS-SGH alone. Complement protein changes were seen between controls and PCOS-nonGH, and decay-accelerator factor (DAF) was decreased between PCOS-nonGH and PCOS-GSGH (p < 0.05). CRP correlated with eGFR in the PCOS-SGH group, but not with other inflammatory or complement parameters. Cystatin-c (a marker of CKD) was reduced between PCOS-nonGH and PCOS-GSGH (p < 0.05). No differences in tubular renal injury markers were found. A secondary cohort notes review of the biobank subjects 8.2-9.6 years later showed a reduction in eGFR: controls -6.4 ± 12.6 mL/min/1.73 m2 (-5.3 ± 11.5%; decrease 0.65%/year); PCOS-nonGH -11.3 ± 13.7 mL/min/1.73 m2 (-9.7 ± 12.2%; p < 0.05, decrease 1%/year); PCOS-GH (eGFR 126-140 mL/min/17.3 m2) -27.1 ± 12.8 mL/min/1.73 m2 (-19.1 ± 8.7%; p < 0.0001, decrease 2%/year); PCOS-SGH (eGFR ≥ 142 mL/min/17.3 m2) -33.7 ± 8.9 mL/min/17.3 m2 (-22.8 ± 6.0%; p < 0.0001, decrease 3.5%/year); PCOS-nonGH eGFR versus PCOS-GH and PCOS-SGH, p < 0.001; no difference PCOS-GH versus PCOS-SGH. GH was associated with PCOS and did not appear mediated through tubular renal injury; however, cystatin-c and DAF were decreased, and CRP correlated positively with PCOS-SGH, suggesting inflammation may be involved at higher GH. There were progressive eGFR decrements for PCOS-nonGH, PCOS-GH, and PCOS-SGH in the follow-up period which, in the presence of additional factors affecting renal function, may be clinically important in the development of CKD in PCOS.

What Not to Overlook in the Management of Patients with Type 2 Diabetes Mellitus: The Nephrological and Hepatological Perspectives.

Diabetes mellitus (DM) significantly impacts renal and hepatic function, necessitating comprehensive understanding and management strategies. Renal involvement, namely diabetic kidney disease (DKD), presents a global challenge, with increasing prevalence paralleling DM rates. Lifestyle modifications and pharmacotherapy targeting hypertension and glycemic control have pivotal roles in DKD management. Concurrently, hepatic involvement in DM, characterized by metabolic dysfunction-associated steatotic liver disease (MASLD), presents a bidirectional relationship. DM exacerbates MASLD progression, while MASLD predisposes to DM development and worsens glycemic control. Screening for MASLD in DM patients is of high importance, utilizing non-invasive methods like ultrasound and fibrosis scores. Lifestyle modifications, such as weight loss and a Mediterranean diet, mitigate MASLD progression. Promising pharmacotherapies, like SGLT2 inhibitors and GLP-1 agonists, demonstrate efficacy in both DM and MASLD management. Special populations, such as diabetic individuals undergoing hemodialysis or kidney transplant recipients, demand special care due to unique clinical features. Similarly, DM exacerbates complications in MASLD patients, elevating the risks of hepatic decompensation and hepatocellular carcinoma. Recognizing the interconnectedness of DM, renal, and hepatic diseases underscores the need for multidisciplinary approaches for optimal patient outcomes. The present review aims to present the main characteristics and crucial points not to be overlooked regarding the renal and hepatic involvement in DM patients focusing on the inter-relationships between the renal and the hepatic involvements.

Hyperfiltration can be detected by transcutaneous assessment of glomerular filtration rate in diabetic obese mice.

We addressed if hyperfiltration can be assessed transcutaneously in male diabetic obese mice (BTBRob/ob) at 12 and 24 wk and how this relates to glomerular parameters indicative for hyperfiltration. Transcutaneous assessment of FITC-Sinistrin clearance [transcutaneous assessment of glomerular filtration rate (tGFR)] was compared against classical plasma clearance. Kidney from SV620C-01-PEI perfused mice were harvested at 24 wk and processed for tissue clearing and classical histology. Perfusion patterns of glomerular capillaries, glomerular size, and vasodilation of the afferent arterioles were assessed. Although at 12 wk FITC-Sinistrin half-life (t1/2) for both tGFR and plasma clearance suggested hyperfiltration, this was not significant anymore at 24 wk. In kidneys of diabetic mice the diameter of the afferent arteriole was significantly larger and positively correlated with glomerular size. Glomerular perfusion pattern in these mice was heterogeneous ranging from non- to well-perfused glomeruli. Nonperfused glomerular areas displayed a strong periodic acid-Schiff's (PAS) positive staining. Collectively our data demonstrate that tGFR is a valid method to detect hyperfiltration. Hyperfiltration occurs early in BTBRob/ob mice and disappears with disease progression as a consequence of a reduced filtration surface. It remains to be assessed if tGFR is also a valid method in diabetic mice with severely compromised renal function.NEW & NOTEWORTHY tGFR measurement is a relatively new method to assess kidney function in conscious rodents, which can be repeated multiple times in the same animal to track the course of the disease and/or the effect of potential treatments. Since the literature was inconclusive on the suitability of this technique in obese mice, we validated it for the first time against classical plasma clearance in the commonly used BTBRob/ob mouse model.

Metabolically healthy obesity is associated with higher risk of both hyperfiltration and mildly reduced estimated glomerular filtration rate: the role of serum uric acid in a cross-sectional study.

BACKGROUND: The impact of metabolically healthy obesity (MHO) on kidney dysfunction remains debatable. Moreover, few studies have focused on the early stages of kidney dysfunction indicated by hyperfiltration and mildly reduced eGFR. Thus, we aimed to investigate the association between the MHO and early kidney dysfunction, which is represented by hyperfiltration and mildly reduced estimated glomerular filtration rate (eGFR), and to further explore whether serum uric acid affects this association. METHODS: This cross-sectional study enrolled 1188 residents aged ≥ 40 years old from Yonghong Communities. Metabolically healthy phenotypes were categorized based on Adult Treatment Panel III criteria. Obesity was defined as body mass index (BMI) ≥ 25 kg/m2. Mildly reduced eGFR was defined as being in the range 60 < eGFR ≤ 90 ml/min/1.73m2. Hyperfiltration was defined as eGFR > 95th percentile after adjusting for sex, age, weight, and height. RESULTS: Overall, MHO accounted for 12.8% of total participants and 24.6% of obese participants. Compared to metabolically healthy non-obesity (MHNO), MHO was significantly associated with an increased risk of mildly reduced eGFR (odds ratio [OR] = 1.85, 95% confidence interval [CI] 1.13-3.01) and hyperfiltration (OR = 2.28, 95% CI 1.03-5.09). However, upon further adjusting for uric acid, the association between the MHO phenotype and mildly reduced eGFR was reduced to null. Compared with MHNO/non-hyperuricemia, MHO/non-hyperuricemia was associated with an increased risk of mildly reduced eGFR (OR = 2.04, 95% CI 1.17-3.58), whereas MHO/hyperuricemia was associated with an observably increased risk (OR = 3.07, 95% CI 1.34-7.01). CONCLUSIONS: MHO was associated with an increased risk of early kidney dysfunction, and the serum uric acid partially mediated this association. Further prospective studies are warranted to clarify the causality.

Long-term effects of primary aldosteronism treatment on patients with primary aldosteronism and chronic kidney disease.

OBJECTIVE: Primary aldosteronism (PA) is a major cause of secondary hypertension and is associated with chronic renal injury. The glomerular filtration rate (GFR) in PA rapidly decreases after the removal of glomerular hyperfiltration due to aldosterone excess by adrenalectomy (ADX) or mineralocorticoid receptor antagonist (MRA) treatment and is stable in the long term. However, the effects of these treatments on the long-term renal function of PA patients with chronic kidney disease (CKD) is not well understood. DESIGN AND PATIENTS: In this single-center, retrospective study, acute and chronic changes in the estimated GFR (eGFR) were examined in 107 patients with PA, including 49 patients with post-treatment CKD　defined as eGFR < 60 ml/min/1.73 m2 . RESULTS: The reduction in eGFR observed 1 month after ADX in the CKD group (N = 31) was -20.1 ± 8.2 ml/min/1.73 m2 . Multivariate analysis showed that pre-treatment eGFR and plasma aldosterone concentration were independent predictive factors of the acute reduction in eGFR after ADX. The reduction of eGFR observed 1 month after MRA administration in the post-treatment CKD group (N = 18) was -9.2 ± 5.9 ml/min/1.73 m2 . Multivariate analysis showed that the duration of hypertension and pre-treatment eGFR were independent predictive factors of the acute reduction in eGFR after ADX administration. In 20 patients with CKD (N = 12 ADX and N = 8 MRA) followed for more than 5 years post-treatment, there was no further significant decline in eGFR over a follow-up period of 7 (6, 8) years nor any difference between the two treatment modalities. CONCLUSIONS: Our study suggests that treatment of PA in stage 3 CKD is safe and useful in preventing renal injury.

The Relationship of Kidney Function, Cardiovascular Morbidity, and All-Cause Mortality: a Prospective Primary Care Cohort Study.

BACKGROUND: Lower-than-normal estimated glomerular filtration rate (eGFR) is associated with the risk for all-cause mortality and adverse cardiovascular events. In this regard, the role of higher-than-normal eGFR is still controversial. OBJECTIVE: Investigate long-term clinical consequences across the levels of eGFR calculated by the creatinine-based Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation among apparently healthy cardiovascular risk subjects. DESIGN: Prospective study. PARTICIPANTS: Participants (n=1747) of a population-based screening and intervention program for cardiovascular risk factors in Finland during the years 2005-2007. MAIN MEASURES: Cardiovascular morbidity and all-cause mortality. KEY RESULTS: Over the 14-year follow-up, subjects with eGFR ≥105 ml/min/1.73 m2 (n=97) had an increased risk for all-cause mortality [HR 2.15 (95% CI: 1.24-3.73)], incident peripheral artery disease [HR 2.62 (95% CI: 1.00-6.94)], and atrial fibrillation/flutter [HR 2.10 (95% CI: 1.21-3.65)] when compared to eGFR category 90-104 ml/min after adjustment for cardiovascular and lifestyle-related risk factors. The eGFR category ≥105 ml/min was also associated with a two-fold increased mortality rate compared to the Finnish general population. CONCLUSIONS: Renal hyperfiltration defined as eGFR ≥105 ml/min/1.73 m2 is a frequent and important finding in patients commonly treated in primary care. These patients should be followed closely for timely interventions, such as strict BP and blood glucose regulation.

Beneficial effects of brief early life angiotensin-converting enzyme inhibition wane with time in sheep with solitary functioning kidney.

A child with a congenital solitary functioning kidney (SFK) may develop kidney disease from early in life due to hyperfiltration injury. Previously, we showed in a sheep model of SFK that brief angiotensin-converting enzyme inhibition (ACEi) early in life is reno-protective and increases renal functional reserve (RFR) at 8 months of age. Here we investigated the long-term effects of brief early ACEi in SFK sheep out to 20 months of age. At 100 days gestation (term = 150 days) SFK was induced by fetal unilateral nephrectomy, or sham surgery was performed (controls). SFK lambs received enalapril (SFK+ACEi; 0.5 mg/kg, once daily, orally) or vehicle (SFK) from 4 to 8 weeks of age. At 8, 14 and 20 months of age urinary albumin excretion was measured. At 20 months of age, we examined basal kidney function and RFR via infusion of combined amino acid and dopamine (AA+D). SFK+ACEi resulted in lower albuminuria (∼40%) at 8 months, but not at 14 or 20 months of age compared with vehicle-SFK. At 20 months, basal GFR (∼13%) was lower in SFK+ACEi compared with SFK, but renal blood flow (RBF), renal vascular resistance (RVR) and filtration fraction were similar to SFK. During AA+D, the increase in GFR was similar in SFK+ACEi and SFK animals, but the increase in RBF was greater (∼46%) in SFK+ACEi than SFK animals. Brief ACEi in SFK delayed kidney disease in the short-term but these effects were not sustained long-term.

Prostanoid receptors in hyperfiltration-mediated glomerular injury: Novel agonists and antagonists reveal opposing roles for EP2 and EP4 receptors.

Increased fluid-flow shear stress (FFSS) contributes to hyperfiltration-induced podocyte and glomerular injury resulting in progression of chronic kidney disease (CKD). We reported that increased FFSS in vitro and in vivo upregulates PGE2 receptor EP2 (but not EP4 expression), COX2-PGE2 -EP2 axis, and EP2-linked Akt-GSK3ß-ß-catenin signaling pathway in podocytes. To understand and use the disparities between PGE2 receptors, specific agonists, and antagonists of EP2 and EP4 were used to assess phosphorylation of Akt, GSK3ß and ß-catenin in podocytes using Western blotting, glomerular filtration barrier function using in vitro albumin permeability (Palb ) assay, and mitigation of hyperfiltration-induced injury in unilaterally nephrectomized (UNX) mice at 1 and 6 months. Results show an increase in Palb by PGE2 , EP2 agonist (EP2AGO ) and EP4 antagonist (EP4ANT ), but not by EP2 antagonist (EP2ANT ) or EP4 agonist (EP4AGO ). Pretreatment with EP2ANT blocked the effect of PGE2 or EP2AGO on Palb . Modulation of EP2 and EP4 also induced opposite effects on phosphorylation of Akt and ß-Catenin. Individual agonists or antagonists of EP2 or EP4 did not induce significant improvement in albuminuria in UNX mice. However, treatment with a combination EP2ANT + EP4AGO for 1 or 6 months caused a robust decrease in albuminuria. EP2ANT + EP4AGO combination did not impact adaptive hypertrophy or increased serum creatinine. Observed differences between expression of EP2 and EP4 on the glomerular barrier highlight these receptors as potential targets for intervention. Safe and effective mitigating effect of EP2ANT + EP4AGO presents a novel opportunity to delay the progression of hyperfiltration-associated CKD as seen in transplant donors.

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.

Glomerular hyperfiltration: part 1 - defining the threshold - is the sky the limit?

Glomerular hyperfiltration (GHF) is an increase in single-nephron glomerular filtration rate (GFR) that occurs in both physiological states and pathological states. Whole-kidney GHF is often used as a surrogate for single-nephron hyperfiltration since determining single-nephron GFR is impossible in routine clinical care. A clear definition (read threshold) of GHF is lacking. The aim of the first part of this review was to find evidence for defining the threshold for GHF, based on literature review, including systematic reviews and meta-analysis data, with both measured and estimated GFR. The consensus pediatric threshold for GHF as obtained from reviews, measured and estimated GFR studies, can reliably be set to 135 mL/min/1.73 m2 for children aged > 2 years. Diagnosing GHF from SCr-based estimated GFR is not reliable in subjects with reduced muscle mass. In these cases, it could be of interest to confirm the state of GHF using cystatin C-based eGFR, or preferably, by measured GFR, using methods that are accurate in the high GFR-range.

Trajectories of eGFR and risk of albuminuria in youth with type 2 diabetes: results from the TODAY cohort study.

BACKGROUND: We conducted exploratory analyses to identify distinct trajectories of estimated glomerular filtration rate (eGFR) and their relationship with hyperfiltration, subsequent rapid eGFR decline, and albuminuria in participants with youth-onset type 2 diabetes enrolled in the Treatment Options for type 2 Diabetes in Adolescents and Youth (TODAY) study. METHODS: Annual serum creatinine, cystatin C, urine albumin, and creatinine measurements were obtained from 377 participants followed for ≥ 10 years. Albuminuria and eGFR were calculated. Hyperfiltration peak is the greatest eGFR inflection point during follow-up. Latent class modeling was applied to identify distinct eGFR trajectories. RESULTS: At baseline, participants' mean age was 14 years, type 2 diabetes duration was 6 months, mean HbA1c was 6%, and mean eGFR was 120 ml/min/1.73 m2. Five eGFR trajectories associated with different rates of albuminuria were identified, including a "progressive increasing eGFR" group (10%), three "stable eGFR" groups with varying starting mean eGFR, and an "eGFR steady decline" group (1%). Participants who exhibited the greatest peak eGFR also had the highest levels of elevated albuminuria at year 10. This group membership was characterized by a greater proportion of female and Hispanic participants. CONCLUSIONS: Distinct eGFR trajectories that associate with albuminuria risk were identified, with the eGFR trajectory characterized by increasing eGFR over time associating with the highest level of albuminuria. These descriptive data support the current recommendations to estimate GFR annually in young persons with type 2 diabetes and provide insight into eGFR-related factors which may contribute to predictive risk strategies for kidney disease therapies in youth with type 2 diabetes. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00081328, date registered 2002. A higher resolution version of the Graphical abstract is available as Supplementary information.

Urinary protein to creatinine ratio during the first month of life in very preterm infants-a prospective cohort study (PROTIPREMA).

BACKGROUND: Preterm infants have physiological proteinuria and values of urine protein to creatinine ratio (UPr/Cr) are higher compared to full-term infants during the first week of life. Few investigations explored the changes of proteinuria in very preterm infants (VPI, ≤ 31 weeks of gestation) older than a week, and it is unclear whether high and persistent proteinuria is associated with kidney injury in this population. This study aimed to (1) observe the changes of UPr/Cr during the first month of life in VPI and (2) describe clinical and biological variables associated with the changes of UPr/Cr. METHODS: Spot urine samples for UPr/Cr were collected on the first day of life (DOL1) and then on DOL2-3, DOL5-6, second week of life (WOL2), WOL3, and WOL4 in VPI cared for in a third-level NICU. We tested the relationship of UPr/Cr with perinatal variables and diseases. RESULTS: A total of 1140 urine samples were obtained for 190 infants. UPr/Cr values (mg/mmol) (median with interquartile) at DOL1, DOL2, DOL3, WOL2, WOL3, and WOL4 were, respectively, 191 (114-399), 226 (152-319), 225 (156-350), 282 (200-488), 308 (188-576), and 325 (175-664). At the multivariate analysis, lower gestational age (GA) and increasing postnatal age were the only variables significantly associated with higher UPr/Cr values (p < 0.001). There was wide intra- and interindividual variability in UPr/Cr, especially in infants with higher GA and clinical stability. CONCLUSIONS: In VPI, UPr/Cr is higher at lower GA and increases with advancing postnatal age. High persistent proteinuria is not associated with clinical and biological variables reflecting kidney injury during the first month of life. A higher resolution version of the Graphical abstract is available as Supplementary information.