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Nephron[JOURNAL]

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Immunosuppressant Agents as Add-On Therapy Failed to Improve the Outcome of Immunoglobulin A Nephropathy with Crescent Score C1.

Bi X, Yu Y, Zhou S … +3 more , Zhou Y, Zhao J, Xiong J

Nephron · 2024 · PMID 38723614 · Publisher ↗

INTRODUCTION: The renoprotective benefits of adding immunosuppressant therapy to corticosteroid (CS) treatment for immunoglobulin A nephropathy (IgAN) patients with less than 25% crescent formation (C1) remain uncertain,... INTRODUCTION: The renoprotective benefits of adding immunosuppressant therapy to corticosteroid (CS) treatment for immunoglobulin A nephropathy (IgAN) patients with less than 25% crescent formation (C1) remain uncertain, warranting further research. METHODS: A retrospective study was conducted on IgAN patients with crescent C1 lesions confirmed by renal biopsy at Xinqiao Hospital between May 1, 2017, and May 1, 2020. Patients were stratified into either the CS treatment group or the CS combined with an additional immunosuppressant therapy group. Follow-up assessments were conducted within 24 months. Propensity score analysis was used to match patients receiving CS and CS + immunosuppressant drug treatment in a 1:1 ratio. Primary outcomes included changes in estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio (UACR). Subgroup analyses were performed to evaluate the benefits of different populations. Composite endpoint outcomes comprised a 30% eGFR decrease, end-stage kidney disease (ESKD) necessitating dialysis or transplant, or kidney disease-related mortality. Adverse events were also compared between the two groups. RESULTS: 296 IgAN patients with C1 lesions were included in the analysis. Baseline characteristics indicated that IgAN patients in the CS + immunosuppressant group exhibited poorer renal function and higher UACR levels. Propensity score analysis effectively minimized the influence of baseline clinical characteristics, including age, serum creatinine, initial eGFR, UACR, and 24-h proteinuria. Both treatment groups demonstrated continuous eGFR improvement and significant UACR reduction during follow-up, especially at 6 months. However, no significant differences in eGFR and UACR reduction rates were observed between the two groups throughout the entire follow-up period, both before and after matching. Subgroup analysis revealed improved eGFR in both treatment groups, notably among patients with an initial eGFR below 90 mL/min/1.73 m2. Conversely, IgAN patients with C1 lesions and a cellular crescent ratio exceeding 50% treated with CS and immunosuppressant therapy experienced a significant improvement in renal function and a decline in urinary protein creatinine ratio. Composite endpoint outcomes did not significantly differ between the two groups, while the incidence of adverse events was comparable. CONCLUSION: Our findings suggest that the addition of immunosuppressant therapy to corticosteroid monotherapy did not confer significant therapeutic advantages in patients with C1 lesions compared to CS monotherapy, although some specific patient populations appeared to derive modest benefits from this combined approach.

Indirect Markers of Intestinal Damage in IgA Nephropathy.

Pohjonen J, Kaukinen K, Huhtala H … +4 more , Pörsti I, Lindfors K, Mustonen J, Mäkelä S

Nephron · 2024 · PMID 38723612 · Full text

INTRODUCTION: Presence of subclinical intestinal inflammation has repeatedly been shown in IgA nephropathy (IgAN) and the degree of histological inflammation has correlated with abnormal urinary findings. There is lack o... INTRODUCTION: Presence of subclinical intestinal inflammation has repeatedly been shown in IgA nephropathy (IgAN) and the degree of histological inflammation has correlated with abnormal urinary findings. There is lack of noninvasive biomarkers evaluating the presence of subclinical intestinal damage in IgAN. We conducted this study hypothesizing that selected biomarkers regarded as indirect markers of intestinal damage could be elevated in IgAN. METHODS: Eighty-five primary IgAN patients (median age 55 years, 54% men) participated in this single-center study in Tampere, Finland. None had end-stage kidney disease or previously diagnosed enteropathies. Celiac disease was excluded with serum transglutaminase 2 antibody (TG2Ab) and endomysial antibody tests and inflammatory bowel disease with fecal calprotectin. Intestinal damage was evaluated from sera with analyses of intestinal fatty-acid binding protein (I-FABP), soluble cluster of differentiation molecule 14 (sCD14), and lipopolysaccharide binding protein. Fourteen people suffering from dyspepsia and 15 healthy people served as controls. RESULTS: I-FABP levels among IgAN patients were higher than in the healthy controls (median 830 pg/mL vs. 289 pg/mL, p < 0.001). Also, sCD14 was increased in IgAN patients compared to dyspepsia controls. Although TG2Ab levels were within the normal range among IgAN patients, they were higher than in the healthy controls (median 1.3 U/mL vs. 0.6 U/mL, p < 0.001). CONCLUSIONS: Elevated serum levels of I-FABP were present in primary IgAN patients without known enteropathies. Serum I-FABP may indicate the presence of subclinical intestinal damage. These findings encourage further investigation into the role of the intestine in the pathophysiology of IgAN.

Remote Surveillance Technology of Dialysis Arteriovenous Access: Retrospective Evaluation in a UK Renal Centre.

Eltahan AR, Pondor Z, Donne RL … +5 more , Lewis D, Raman M, Hinchliffe P, Cowperthwaite J, Poulikakos D

Nephron · 2024 · PMID 38688245 · Full text

BACKGROUND: Early identification of dysfunctional arteriovenous haemodialysis (HD) vascular access (VA) is important for timely referral and intervention. METHOD: We retrospectively calculated VA risk score using Vasc-Al... BACKGROUND: Early identification of dysfunctional arteriovenous haemodialysis (HD) vascular access (VA) is important for timely referral and intervention. METHOD: We retrospectively calculated VA risk score using Vasc-Alert surveillance software technology from HD treatment sessions in 2 satellite HD units over 18 months. We included in the analysis HD patients dialysing with arteriovenous fistula or graft (AVF/G) with available Vasc-Alert data for≥ 2 months. For group one (eventful) that included patients who developed vascular access thrombosis or stenosis over the study period, we collected Vasc-Alert risk score 2 months prior to the event and, for group two (uneventful), over 5 consecutive months. Vasc-Alert technology utilises routinely collected data during HD to calculate VA risk score and triggers an alert if the score is ≥7 in 3 consecutive dialysis sessions. Patients with >2 alerts (vascular access score ≥7) per month were considered to have positive alerts. RESULTS: From 140 HD patients, 81 patients dialysed via AVF/G. 77/81 had available Vasc-Alert data and were included in the final analysis. Out of 17 eventful patients, 11 (64.7%) had positive alerts 2 months prior to the vascular event. Out of the 60 patients without vascular events, 20 patients (33.3%) had positive alert. Vasc-Alert's sensitivity and specificity for vascular events were 64.7% and 66.6%, respectively. Within the 6 patients with thrombosed access, 2 patients (33.3%) detected by Vasc-Alert were not detected with clinical monitoring. CONCLUSION: Vascular access risk score can be a useful non-invasive vascular access surveillance method to assist clinical decision making.

Feasibility and Safety of Percutaneous Kidney Biopsy in Small Kidneys: Breaking the Paradigm.

Zepeda-Quiroz I, Juarez-Villa D, Gomez-Johnson VH … +7 more , Sanchez-Vazquez OH, Toledo-Ramirez SE, Rodriguez-Castellanos FE, Cortez-Flores BG, Garcia-Rivera A, Madero Rovalo M, Moguel-Gonzalez B

Nephron · 2024 · PMID 38657584 · Publisher ↗

INTRODUCTION: The percutaneous kidney biopsy (PKB) is an essential tool in nephrology; small kidney size has been a relative contraindication to PKB and there is limited data on the safety and utility of performing PKB i... INTRODUCTION: The percutaneous kidney biopsy (PKB) is an essential tool in nephrology; small kidney size has been a relative contraindication to PKB and there is limited data on the safety and utility of performing PKB in this setting. Our aim was to describe the complications of PKB in small kidneys and to assess if kidney biopsy results have an impact on medical decisions and outcomes. METHODS: This was a retrospective, descriptive, and observational study. Patients older than 16 years of age with a decreased kidney size (≤8 cm) and undergoing PKB of native kidneys from July 2019 to December 2022 were included. RESULTS: Twenty-five patients were included, 19 women and 6 men. The mean age was 42.3 ± 18.04. The mean kidney length was 7.56 ± 0.33 and the mean width was 4.2 cm. All patients received only 1 puncture, obtaining an average of 12 glomeruli. The mean blood urea nitrogen and serum creatinine were 36 mg/dL and 1.94 mg/dL, respectively and the mean Hgb (hemoglobin) was 12.87 ± 2.81 g/dL. Minor complications occurred in 5 patients, perirenal hematoma in 3 patients, hematuria in 1 patient, and hematoma plus hematuria in 1 patient. Histological examination showed FSGS, lupus nephritis, other Glomerular disease, crescentic glomerulonephritis, and tubulointerstitial nephritis in 36%, 20%, 16%, 16%, and 12% of the cases, respectively. Biopsy resulted in management modification in 64% of cases. In a bivariate analysis, kidney size was not associated with higher complication rates. CONCLUSIONS: PKB in small kidneys is a feasible and safe procedure when properly planned, providing an adequate sample in all cases, with an insignificant number of minor complications, and that is clinically relevant.

Renal Cystinuria and Immune Cells (T Lymphocytes) Dysfunction: What We Know about?

Caprio F, Orefice G, Secondulfo F … +7 more , Carone Fabiani F, Iervolino A, Capasso G, Simeoni M, Zacchia M, Trepiccione F, Capolongo G

Nephron · 2024 · PMID 38657578 · Publisher ↗

INTRODUCTION: Cystinuria (CYS) is the most common monogenic kidney stone disease. METHODS: Starting from an unusual case of CYS associated to primary sclerosing cholangitis, inflammatory bowel disease (IBD), and autoimmu... INTRODUCTION: Cystinuria (CYS) is the most common monogenic kidney stone disease. METHODS: Starting from an unusual case of CYS associated to primary sclerosing cholangitis, inflammatory bowel disease (IBD), and autoimmune hepatitis in a young male, we carefully review the literature and propose here a working hypothesis regarding the potential risk of cystinuric patients to develop conditions due to immune system dysregulation. To corroborate this hypothesis, we retrospectively evaluate the frequency of dysimmunity in a monocentric cohort including 36 cystinuric patients compared to healthy and disease controls. RESULTS: CYS patients have an increased prevalence of atopic disease compared to disease controls (p = 0.03) and 16.7% of CYS subjects were diagnosed with allergic disease to a variety of antigens. CONCLUSION: Further studies are needed to define the relationship between proximal tubular transport defect of CYS and dysregulated immunity.

Extended-Release Calcifediol: A Data Journey from Phase 3 Studies to Real-World Evidence Highlights the Importance of Early Treatment of Secondary Hyperparathyroidism.

Merante D, Schou H, Morin I … +4 more , Manu M, Ashfaq A, Bishop C, Strugnell S

Nephron · 2024 · PMID 38657576 · Full text

BACKGROUND: Early secondary hyperparathyroidism (SHPT) diagnosis and treatment are crucial to delay the progression of SHPT and related complications, in particular, cardiovascular events and bone fractures. Extended-rel... BACKGROUND: Early secondary hyperparathyroidism (SHPT) diagnosis and treatment are crucial to delay the progression of SHPT and related complications, in particular, cardiovascular events and bone fractures. Extended-release calcifediol (ERC) has been developed for the treatment of SHPT in patients with stage 3/4 chronic kidney disease (CKD) and vitamin D insufficiency (VDI). SUMMARY: This review compares baseline characteristics and treatment responses of SHPT patients receiving ERC in phase 3 studies with those treated with ERC in a real-world study. Mean ± standard deviation baseline parathyroid hormone (PTH) levels were 147 ± 56 pg/mL and 148 ± 64 pg/mL in the phase 3 ERC cohorts, and 181 ± 98 pg/mL in the real-world study. Other baseline laboratory parameters were consistent between the clinical and real-world studies. ERC treatment increased 25-hydroxyvitamin D (25(OH)D) and significantly reduced PTH levels, regardless of baseline CKD stage, in all studies. In the pooled phase 3 per-protocol populations, 74% of the ERC cohort were uptitrated to 60 μg/day after 12 weeks at 30 μg/day, 97% attained 25(OH)D levels ≥30 ng/mL, and 40% achieved ≥30% PTH reduction. Despite a much lower rate of uptitration in the real-world study, 70% of patients achieved 25(OH)D levels ≥30 ng/mL, and 40% had a ≥30% reduction in PTH. KEY MESSAGES: These data establish a "continuum" of clinical and real-world evidence of ERC effectiveness for treating SHPT, irrespective of CKD stage, baseline PTH levels, and ERC dose. This evidence supports early treatment initiation with ERC, following diagnosis of SHPT, VDI, and stage 3 CKD, to delay SHPT progression.

Validation of a Risk Prediction Equation for Incident Chronic Kidney Disease in a Hypertensive Non-Diabetes Cohort in Singapore Primary Care Patients.

Weng W, Wong SY, Ang GY … +3 more , Xian Ng SH, Lim CK, Yeo SC

Nephron · 2024 · PMID 38636463 · Publisher ↗

BACKGROUND: Accurate identification of individuals at risk of developing chronic kidney disease (CKD) may improve clinical care. Nelson et al. developed prediction equations to estimate the risk of incident eGFR of less... BACKGROUND: Accurate identification of individuals at risk of developing chronic kidney disease (CKD) may improve clinical care. Nelson et al. developed prediction equations to estimate the risk of incident eGFR of less than 60 mL/min/1.73 m2 in diabetic and non-diabetes patients using data from 34 multinational cohorts. We aim to validate the non-diabetes equation in our local multi-ethnic cohort and develop further prediction models. METHODS: Demographics, clinical and laboratory data of hypertensive non-diabetes patients with baseline eGFR ≥60 mL/min/1.73 m2 on follow-up with primary care clinics between 2010 and 2015 were collected. Follow-up was 5 years from entry to study. We validated Nelson's equation and developed our own model which we subsequently validated. The developmental cohort included patients between 2010 and 2014 while the validation cohort included patients in 2015. Variables included age, sex, eGFR, history of cardiovascular disease, ever smoker, body mass index, albuminuria, cholesterol, and treatment. Primary outcome was incident eGFR <60/min/1.73 m2 within 5 years. Model performance was evaluated by C-statistics and calibration was assessed. RESULTS: In the developmental cohort of 27,800 patients, 2823 (10.2%) developed the outcome during a mean follow-up of 4.4 years while 638 (12.8%) patients developed the outcome in the validation cohort of 4,994 patients. Applicability of Nelson's equation was limited by missing albuminuria, absence of black race, and exclusion of non-hypertensive patients in our cohort. Nonetheless, the modified Nelson's model demonstrated C-statistic of 0.85 (95% CI: 0.84-0.86). The C-statistic of our bespoke model was 0.85 (0.85-0.86) and 0.87 (0.85-0.88) for the developmental cohort and validation cohort, respectively. Calibration was suboptimal as the predicted risk exceeded the observed risk. CONCLUSIONS: The modified Nelson's equation and our locally derived novel model demonstrated high discrimination. Both models may potentially be used in predicting risk of CKD in hypertensive patients who are managed in primary care, allowing for early interventions in high-risk population.

Complement-Mediated Thrombotic Microangiopathy after Kidney Transplant: Should Treatment with C5 Inhibitor Be Lifelong?

Musalem P, Pedreros-Rosales C, Müller-Ortiz H … +2 more , Gutierrez-Navarro C, Carpio JD

Nephron · 2024 · PMID 38615653 · Publisher ↗

Complement-mediated thrombotic microangiopathy (CM-TMA) is a rare and life-threatening complication that can occur in kidney transplant recipients, with various potential triggers including immunosuppressive medications.... Complement-mediated thrombotic microangiopathy (CM-TMA) is a rare and life-threatening complication that can occur in kidney transplant recipients, with various potential triggers including immunosuppressive medications. The optimal management and duration of treatment with C5 inhibitors (C5i) for CM-TMA in this patient population remain areas of ongoing investigation. We present the case of a 38-year-old female with a history of IgA nephropathy who underwent preemptive living-related kidney transplantation and subsequently developed CM-TMA 7 years post-transplant. Treatment with ravulizumab led to a rapid hematologic response and stabilized platelet counts. Serial measurements of complement functional tests and clinical stability guided the discontinuation of C5i therapy. The case highlights the complexity of managing CM-TMA in kidney transplant recipients, particularly in determining the appropriate duration of C5i therapy. The absence of an established protocol for discontinuation necessitates a personalized approach based on clinical and laboratory stability, absence of complement gene variants, and serial complement functional tests. Further prospective investigations are warranted to define the optimal strategies for monitoring and safely discontinuing C5i therapy in this unique patient population. This case underscores the importance of individualized care in the management of CM-TMA post-kidney transplantation, offering insights into potential criteria for therapy discontinuation.

Chronic Myeloid Leukemia in Renal Transplantation Patients in the Era of Tyrosine Kinase Inhibitors: A Case Report and Review of the Literature.

Murt A, Bayram B, Yılmaz U … +2 more , Seyahi N, Eşkazan AE

Nephron · 2024 · PMID 38574488 · Publisher ↗

Lifelong immunosuppression, cytotoxic effects of some immunosuppressive drugs, and opportunistic oncogenic viruses increase malignancy risks in solid organ recipients. The risk of myeloid neoplasms including chronic myel... Lifelong immunosuppression, cytotoxic effects of some immunosuppressive drugs, and opportunistic oncogenic viruses increase malignancy risks in solid organ recipients. The risk of myeloid neoplasms including chronic myeloid leukemia (CML) is also increased in this patient population. Tyrosine kinase inhibitors (TKIs), the key element of CML therapy, should be used cautiously in transplantation patients as they may interact with calcineurin inhibitors. With this report, a 63-year-old female kidney transplant recipient who developed CML 9 years after kidney transplantation is presented. CML in this patient was treated with a slightly reduced dose of imatinib (300 mg) due to concerns of adverse events including its interaction with tacrolimus. Deep molecular response (DMR) was achieved at 12 months under imatinib treatment. The patient is still in DMR after 30 months of follow-up, and she did not experience any adverse events or acute rejection episodes. CML and the use of TKIs in kidney transplant patients have been discussed with an extensive literature review. In this patient population, TKIs are generally well tolerated with achievement of treatment responses and good prognosis. Graft functions are also well maintained as long as drug interactions are monitored.

Larger Degree of Renal Function Decline in Chronic Kidney Disease Is a Favorable Factor for the Attenuation of eGFR Slope Worsening by SGLT2 Inhibitors: A Retrospective Observational Study.

Miyaoka Y, Moriyama T, Saito S … +7 more , Rinno S, Kato M, Tsujimoto R, Suzuki R, China R, Nagai M, Kanno Y

Nephron · 2024 · PMID 38560981 · Publisher ↗

INTRODUCTION: Sodium-glucose cotransporter 2 inhibitors (SGLT2Is) have beneficial effects on the renal function of chronic kidney disease (CKD) patients, although the types of patients suitable for this treatment remain... INTRODUCTION: Sodium-glucose cotransporter 2 inhibitors (SGLT2Is) have beneficial effects on the renal function of chronic kidney disease (CKD) patients, although the types of patients suitable for this treatment remain unclear. METHODS: A retrospective observational study was conducted on CKD patients who were treated with SGLT2I in our department from 2020 to 2023. The estimated glomerular filtration rate (eGFR) just before treatment was defined as the baseline and the difference between pre-and post-treatment eGFR slopes were used to compare the improvement of renal function. Logistic regression analysis was used to evaluate the independent factors for its improvement. RESULTS: A total of 128 patients were analyzed (mean age: 67.2 years; number of women: 28 [22%]). The mean eGFR was 42.1 mL/min/1.73 m2, and urine protein was 0.66 g/gCr. The eGFR slopes of patients with an eGFR <30 mL/min/1.73 m2 were improved significantly after treatment (-0.28 to -0.14 mL/min/1.73 m2/month, p < 0.001) but were worsened in patients with an eGFR ≥30 mL/min/1.73 m2. Logistic analysis for the improvement in eGFR slopes showed that women (odds ratio [OR], 5.63; 95% confidence interval [CI], 1.16-27.3; p = 0.03), use of mineralocorticoid receptor antagonists (OR, 11.79; 95% CI, 1.05-132.67; p = 0.012) and rapid decline of eGFR before treatment (OR, 12.8 per mL/min/1.73 m2/month decrease in eGFR; 95% CI, 3.32-49.40; p < 0.001) were significant independent variables. CONCLUSION: SGLT2Is may have beneficial effects, especially for rapid decliners of eGFR, including advanced CKD.

Trigenic COL4A3/COL4A4/COL4A5 pathogenic variants in Alport syndrome: a case report.

Rao D, Maas R, Cornelissen M … +2 more , Wetzels J, Geel MV

Nephron · 2024 Mar · PMID 38547857 · Full text

Alport syndrome (AS) is a hereditary kidney disorder of type IV collagen caused by pathogenic variants in the COL4A3, COL4A4 and COL4A5 genes. Previously several cases of digenic AS, caused by two pathogenic variants in... Alport syndrome (AS) is a hereditary kidney disorder of type IV collagen caused by pathogenic variants in the COL4A3, COL4A4 and COL4A5 genes. Previously several cases of digenic AS, caused by two pathogenic variants in two of the three COL4A genes, have been reported. Patients with digenic AS may present with a more severe phenotype compared to patients with single variants, depending on the percentage affected type IV trimeric collagen chain. We report a newly discovered case of trigenic AS. A 52-year-old female presented with hematuria at the age of 24 years and developed hypertension by the age of 30. Over the years she developed chronic kidney disease; the most recent eGFR was 44ml/min/1.73m2. She has symmetric high-tone sensorineural hearing loss. Full genetic analysis revealed a heterozygous pathogenic variant c.2691del in COL4A3, a heterozygous pathogenic variant c.1663dup in COL4A4, and a complete heterozygous deletion of COL4A5. We describe the first patient with AS caused by pathogenic variants in all three COL4A genes, designated trigenic AS. This case report emphasizes the importance of examining all three COL4A genes, even in patients with a mild Alport phenotype, for optimal follow-up of the patient and adequate genetic counseling of family members.

Introducing Exome Sequencing as Part of the Diagnostic Algorithm for Pediatric Nephrology Patients in Bulgaria: A Single-Center Experience.

Beltcheva O, Kamenarova K, Zlatanova G … +8 more , Mihova K, Roussinov D, Kachakova D, Georgiev M, Nikolova E, Gaydarova M, Mitev V, Kaneva R

Nephron · 2024 · PMID 38547852 · Publisher ↗

INTRODUCTION: In pediatric kidney patients, where clinical presentation is often not fully developed, and renal biopsy is too risky or inconclusive, it may be difficult to establish the underlying pathology. In cases suc... INTRODUCTION: In pediatric kidney patients, where clinical presentation is often not fully developed, and renal biopsy is too risky or inconclusive, it may be difficult to establish the underlying pathology. In cases such as these, genetic diagnosis may be used to guide treatment, prognosis, and counseling. Given the large number of genes involved in kidney disease, introducing next-generation sequencing with extended gene panels as part of the diagnostic algorithm presents a viable solution. METHODS: A cohort of 87 consecutive independent cases (83 children and 4 terminated pregnancies) with renal disease was recruited. Exome sequencing with MiSeq or NovaSeq 6000 (Illumina) platforms and analysis of extended gene panels were used for genetic testing. RESULTS: Depending on the presenting pathology, the cases were grouped as patients with glomerular disease, ciliopathies, congenital anomalies, renal electrolyte imbalances, and chronic/acute kidney disease. The overall diagnostic yield was approximately 42% (37 out of 87), with most disease-causing mutations found in COL4A3, COL4A4, COL4A5, and PKHD1 genes. A change or clarification of preliminary diagnosis or adjustment of initial treatment plan based on the results of the genetic testing was made for approximately one-third of the children with meaningful genetic findings (11 out of 37). DISCUSSION: Our results prove the value of targeted exome sequencing as a non-invasive, versatile, and reliable diagnostic tool for pediatric renal disease patients. Providing genetic diagnosis will help for a better understanding of disease etiology and will give the basis for optimal clinical management and insightful genetic counseling.

Kidney Failure Secondary to Hereditary Xanthinuria due to a Homozygous Deletion of the XDH Gene in the Absence of Overt Kidney Stone Disease.

Gonçalves PL, Diniz H, Tavares I … +5 more , Dória S, Dong J, Kyriss M, Fairbanks L, Oliveira JP

Nephron · 2024 · PMID 38527446 · Publisher ↗

Hereditary xanthinuria (HXAN) is a rare metabolic disorder that results from mutations in either the xanthine dehydrogenase (XDH) or the molybdenum cofactor sulfurase genes (MOCOS), respectively defining HXAN type I and... Hereditary xanthinuria (HXAN) is a rare metabolic disorder that results from mutations in either the xanthine dehydrogenase (XDH) or the molybdenum cofactor sulfurase genes (MOCOS), respectively defining HXAN type I and type II. Hypouricemia, hypouricosuria, and abnormally high plasma and urine levels of xanthine, causing susceptibility to xanthine nephrolithiasis and deposition of xanthine crystals in tissues, are the metabolic hallmarks of HXAN. Several pathogenic variants in the XDH gene have so far been identified in patients with HXAN type I, but the clinical phenotype associated with the whole deletion of the human XDH gene is unknown. Herein, we report the case of a woman diagnosed with HXAN, whose molecular genetic testing revealed a homozygous microdeletion involving the XDH gene. Distinctive features of her medical history were the diagnosis of arterial hypertension and microalbuminuria at 22 years of age; a single pregnancy at the age of 25, complicated by proteinuria and transient kidney function deterioration in the third trimester; unexplained severe hypouricemia incidentally discovered during pregnancy; inability to breastfeed her newborn daughter due to primary agalactia; chronic kidney disease (CKD) stage 3 diagnosed at age 35; and progression to end-stage kidney disease over the next 12 years. Protocol noninvasive laboratory and imaging investigation was not informative as to the cause of CKD. This is the first description of the clinical phenotype associated with a natural knockout of the human XDH gene. Despite the lack of kidney histopathology data, the striking similarities with the phenotypes exhibited by comparable murine models validate the latter as useful sources of mechanistic insights for the pathogenesis of the human disease, supporting the hypothesis that the absence of xanthine dehydrogenase activity might represent a susceptibility factor for chronic tubulointerstitial nephritis, even in patients without kidney stones.

Serum Myostatin at Dialysis Initiation May Predict 1-Year Mortality and Hospitalization.

Sakashita M, Hamasaki Y, Oki R … +6 more , Komaru Y, Miyamoto Y, Yoshida T, Matsuura R, Doi K, Nangaku M

Nephron · 2024 · PMID 38522414 · Full text

OBJECTIVE: Myostatin, which is known as a negative skeleton muscle regulator, is associated with mortality in maintenance hemodialysis patients. However, the significance of serum myostatin concentrations at dialysis ini... OBJECTIVE: Myostatin, which is known as a negative skeleton muscle regulator, is associated with mortality in maintenance hemodialysis patients. However, the significance of serum myostatin concentrations at dialysis initiation has not been established. We investigated the relation between serum myostatin concentrations and mortality or hospitalization within 1 year in incident dialysis patients. METHODS: After a patient initiating hemodialysis or peritoneal dialysis during 2016-2018 was enrolled, the patient's serum myostatin at dialysis initiation was measured. Composite outcomes comprising mortality and hospitalization within 1 year after dialysis initiation were compared between two groups divided according to myostatin levels. The Cox proportional hazards model was used to assess significant relations between myostatin and outcomes. RESULTS: This study examined 104 incident dialysis patients with a mean age of 65.5 ± 14.0 years (68% male). Kaplan-Meier analyses indicated the 1-year hospitalization-free and survival rate as significantly lower in the lower myostatin group than in the higher myostatin group (p = 0.0020). Cox proportional hazards regression analyses revealed that the value of myostatin logarithm at dialysis initiation was inversely associated with the occurrence of a composite outcome, independently of age (hazard ratio 0.16, 95% confidence interval: 0.05-0.57). Receiver operating characteristic analysis showed the area under the curve of serum myostatin for predicting death or hospitalization within 1 year as higher than those of clinical indices of nutritional disturbance and frailty. CONCLUSION: Serum myostatin concentration at dialysis initiation is inversely associated with adverse outcomes in these dialysis-initiated patients.

SARS-CoV-2 Omicron Infections among Vaccinated Maintenance Hemodialysis Patients: Outcomes and Comparison to Delta Variant.

Wand O, Drori I, Einbinder Y … +4 more , Nacasch N, Benchetrit S, Breslavsky A, Cohen-Hagai K

Nephron · 2024 · PMID 38484724 · Full text

BACKGROUND: Infections with B.1.1.529 (Omicron) variants of SARS-CoV-2 became predominant worldwide since late 2021, replacing the previously dominant B.1.617.2 variant (Delta). While those variants are highly transmissi... BACKGROUND: Infections with B.1.1.529 (Omicron) variants of SARS-CoV-2 became predominant worldwide since late 2021, replacing the previously dominant B.1.617.2 variant (Delta). While those variants are highly transmissible and can evade vaccine protection, population studies suggested that outcomes from infection with Omicron variants are better compared with Delta. Data regarding prognosis of maintenance hemodialysis (MHD) patients infected with Omicron versus Delta variants, however, are scarce. METHODS: This retrospective cohort study includes all patients with end-stage kidney disease treated with MHD in Meir Medical Center, Kfar-Saba, Israel, that were diagnosed with SARS-CoV-2 infection between June 2021 and May 2022. RESULTS: Twenty-six subjects were diagnosed with the Delta variant and 71 with Omicron. Despite comparable age between groups and higher mean vaccine doses prior to the infection among the Omicron group (p < 0.001), SARS-CoV-2 infection severity was significantly worse among MHD infected with the Delta variant: 50% developed severe or critical COVID-19 versus 5% in the Omicron group (p < 0.001). Over half of MHD infected with Omicron (57%) were asymptomatic during their illness. The 30-day mortality rate for the whole cohort was 5.2%. It was significantly higher among MHD in the Delta group than in the Omicron group (5/26, 19.2% vs. 0/71, p < 0.001), as was the 90-day mortality rate (5/26, 19.2% vs. 3/71, 4.2%, p = 0.02). CONCLUSIONS: Infection with the SARS-CoV-2 Delta variant was associated with worse outcomes compared with Omicron, among subjects on MHD. However, despite mild disease among vaccinated MHD patients, infection with Omicron variant was still associated with the significant 90-day mortality rate.

Remarkable Improvement of Diabetic Nephropathy in Transplanted Allograft after Kidney Transplantation.

Tanaka R, Imamura R, Matsumura S … +9 more , Fukae S, Taniguchi A, Nakazawa S, Yamanaka K, Namba-Hamano T, Kakuta Y, Takao T, Fushimi H, Nonomura N

Nephron · 2024 · PMID 38452745 · Publisher ↗

Although glomerular damage caused by diabetic nephropathy was thought to be irreversible, in recent years, there have been reports on improvement in glomerular damage with strict glycemic control. However, few reports ar... Although glomerular damage caused by diabetic nephropathy was thought to be irreversible, in recent years, there have been reports on improvement in glomerular damage with strict glycemic control. However, few reports are available on the pathologic course after renal transplantation of donor-derived grafts with findings of diabetic nephropathy. A 53-year-old woman underwent an ABO blood-type compatible living-donor renal transplant. The recipient had no history of diabetes, and fasting blood glucose and hemoglobin A1c levels were both normal. The donor was a 57-year-old male who had received treatment for type 2 diabetes mellitus for 10 years. Transplant renal biopsy performed 1 h after revascularization showed mesangial matrix expansion and arterial hyalinosis due to diabetic nephropathy. The blood glucose level was within the normal range after transplantation. Mesangial matrix expansion and arterial hyalinosis disappeared in allograft biopsy samples 7 years after transplantation. We observed significant improvement in the pathological findings of donor-derived diabetic nephropathy after renal transplantation in the subsequent follow-ups.

The Complement C3a and C5a Signaling in Renal Diseases: A Bridge between Acute and Chronic Inflammation.

Buelli S, Imberti B, Morigi M

Nephron · 2024 · PMID 38452744 · Publisher ↗

The complement system, a cornerstone of the innate immune defense, typically confers protection against pathogens. However, in various clinical scenarios the complement's defensive actions can harm host cells, exacerbati... The complement system, a cornerstone of the innate immune defense, typically confers protection against pathogens. However, in various clinical scenarios the complement's defensive actions can harm host cells, exacerbating immune and inflammatory responses. The central components C3 and C5 undergo proteolytic cleavage during complement activation, yielding small active fragments C3a and C5a anaphylatoxins. Traditionally, these fragments were associated with inflammation via the specific receptors C3a receptor (R), C5aR1 and C5aR2. Recent insights, however, spotlight the excessive C3a/C3aR and C5a/C5aR1 signaling as culprits in diverse disorders of inflammatory and autoimmune etiology. This is particularly true for several kidney diseases, where the potential involvement of anaphylatoxins in renal damage is supported by the enhanced renal expression of their receptors and the high levels of C3a and C5a in both plasma and urine. Furthermore, the production of complement proteins in the kidney, with different renal cells synthesizing C3 and C5, significantly contributes to local tissue injury. In the present review, we discuss the different aspects of C3a/C3aR and C5a/C5aR signaling in acute and chronic kidney diseases and explore the therapeutic potential of emerging targeted drugs for future clinical applications.

Medullary Sponge Kidney and Its Relationship with Primary Distal Renal Tubular Acidosis: Case Reports and a Comprehensive Genetics-First Approach.

van den Berg G, Claus LR, van der Zwaag B … +6 more , Lakeman P, Genomics England Research Consortium, Kaasenbrood L, Sayer JA, Lilien MR, van Eerde AM

Nephron · 2024 · PMID 38447554 · Full text

Medullary sponge kidney (MSK) is a description of radiographic features. However, the pathogenesis of MSK remains unclear. MSK is supposed to be the cause of secondary distal renal tubular acidosis (dRTA), although there... Medullary sponge kidney (MSK) is a description of radiographic features. However, the pathogenesis of MSK remains unclear. MSK is supposed to be the cause of secondary distal renal tubular acidosis (dRTA), although there are case reports suggesting that MSK is a complication of primary dRTA. In addition to these reports, we report 3 patients with metabolic acidosis and MSK, in whom primary dRTA is confirmed by molecular genetic analyses of SLC4A1 and ATP6V1B1 genes. With a comprehensive genetics-first approach using the 100,000 Genomes Rare Diseases Project dataset, the association between MSK and primary dRTA is examined. We showed that many patients with MSK phenotypes are genetically tested with a gene panel which does not contain dRTA-associated genes, revealing opportunities for missed genetic diagnosis. Our cases highlight that the radiological description of MSK is not a straightforward disease or clinical phenotype. Therefore, when an MSK appearance is noted, a broader set of causes should be considered including genetic causes of primary dRTA as the underlying reason for medullary imaging abnormalities.

Hospital Readmissions for Fluid Overload among Individuals with Diabetes and Diabetic Kidney Disease: Risk Factors and Multivariable Prediction Models.

Cai J, Huang D, Abdul Kadir HB … +8 more , Huang Z, Ng LC, Ang A, Tan NC, Bee YM, Tay WY, Tan CS, Lim CC

Nephron · 2024 · PMID 38447535 · Full text

AIMS: Hospital readmissions due to recurrent fluid overload in diabetes and diabetic kidney disease can be avoided with evidence-based interventions. We aimed to identify at-risk patients who can benefit from these inter... AIMS: Hospital readmissions due to recurrent fluid overload in diabetes and diabetic kidney disease can be avoided with evidence-based interventions. We aimed to identify at-risk patients who can benefit from these interventions by developing risk prediction models for readmissions for fluid overload in people living with diabetes and diabetic kidney disease. METHODS: This was a single-center retrospective cohort study of 1,531 adults with diabetes and diabetic kidney disease hospitalized for fluid overload, congestive heart failure, pulmonary edema, and generalized edema between 2015 and 2017. The multivariable regression models for 30-day and 90-day readmission for fluid overload were compared with the LACE score for discrimination, calibration, sensitivity, specificity, and net reclassification index (NRI). RESULTS: Readmissions for fluid overload within 30 days and 90 days occurred in 8.6% and 17.2% of patients with diabetes, and 8.2% and 18.3% of patients with diabetic kidney disease, respectively. After adjusting for demographics, comorbidities, clinical parameters, and medications, a history of alcoholism (HR 3.85, 95% CI: 1.41-10.55) and prior hospitalization for fluid overload (HR 2.50, 95% CI: 1.26-4.96) were independently associated with 30-day readmission in patients with diabetic kidney disease, as well as in individuals with diabetes. Additionally, current smoking, absence of hypertension, and high-dose intravenous furosemide were also associated with 30-day readmission in individuals with diabetes. Prior hospitalization for fluid overload (HR 2.43, 95% CI: 1.50-3.94), cardiovascular disease (HR 1.44, 95% CI: 1.03-2.02), eGFR ≤45 mL/min/1.73 m2 (HR 1.39, 95% CI: 1.003-1.93) was independently associated with 90-day readmissions in individuals with diabetic kidney disease. Additionally, thiazide prescription at discharge reduced 90-day readmission in diabetic kidney disease, while the need for high-dose intravenous furosemide predicted 90-day readmission in diabetes. The clinical and clinico-psychological models for 90-day readmission in individuals with diabetes and diabetic kidney disease had better discrimination and calibration than the LACE score. The NRI for the clinico-psychosocial models to predict 30- and 90-day readmissions in diabetes was 22.4% and 28.9%, respectively. The NRI for the clinico-psychosocial models to predict 30- and 90-day readmissions in diabetic kidney disease was 5.6% and 38.9%, respectively. CONCLUSION: The risk models can potentially be used to identify patients at risk of readmission for fluid overload for evidence-based interventions, such as patient education or transitional care programs to reduce preventable hospitalizations.

Bile Acids and Farnesoid X Receptor in Renal Pathophysiology.

Yang J, Pontoglio M, Terzi F

Nephron · 2024 · PMID 38412845 · Publisher ↗

BACKGROUND: Bile acids (BAs) act not only as lipids and lipid-soluble vitamin detergents but also function as signaling molecules, participating in diverse physiological processes. The identification of BA receptors in o... BACKGROUND: Bile acids (BAs) act not only as lipids and lipid-soluble vitamin detergents but also function as signaling molecules, participating in diverse physiological processes. The identification of BA receptors in organs beyond the enterohepatic system, such as the farnesoid X receptor (FXR), has initiated inquiries into their organ-specific functions. Among these organs, the kidney prominently expresses FXR. SUMMARY: This review provides a comprehensive overview of various BA species identified in kidneys and delves into the roles of renal apical and basolateral BA transporters. Furthermore, we explore changes in BAs and their potential implications for various renal diseases, particularly chronic kidney disease. Lastly, we center our discussion on FXR, a key BA receptor in the kidney and a potential therapeutic target for renal diseases, providing current insights into the protective mechanisms associated with FXR agonist treatments. KEY MESSAGES: Despite the relatively low concentrations of BAs in the kidney, their presence is noteworthy, with rodents and humans exhibiting distinct renal BA compositions. Renal BA transporters efficiently facilitate either reabsorption into systemic circulation or excretion into the urine. However, adaptive changes in BA transporters are evident during cholestasis. Various renal diseases are accompanied by alterations in BA concentrations and FXR expression. Consequently, the activation of FXR in the kidney could be a promising target for mitigating kidney damage.
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