Macroscopic hematuria-associated severe acute kidney injury triggered by kidney stone formation in a patient with thin basement membrane and no history of microscopic hematuria

Macroscopic hematuria (MH)-associated acute kidney injury (AKI) is a rare condition that causes acute tubular damage due to severe glomerular bleeding with MH. A 66-year-old Japanese woman with no significant past medical history was referred for severe kidney injury with oliguric MH. Her prior medical checkup results showed no occult blood in her urine. Seven days earlier, she had experienced transient severe acute right lumbar back pain. On admission, her serum urea nitrogen was 147 mg/dL, serum creatinine (sCr) 18.3 mg/dL, urinary red blood cells (RBCs) > 100/hpf, urinary protein 28.8 g/gCr, with no hydronephrosis in either kidney, but two stones were found in the right kidney and right ureteropelvic junction. At the start of her hemodialysis, the patient was treated with high-dose steroids because of suspected rapidly progressive glomerulonephritis. A renal biopsy of the left kidney showed acute tubular injury with massive RBC casts filling the tubular lumen. Glomerulitis was not detected, but electron microscopy revealed diffuse glomerular thin basement membrane (TBM). Despite immediate steroid discontinuation, the patient's renal function and MH improved, and she was weaned from hemodialysis. The stones resolved 2 months after onset, but microscopic hematuria persisted for 7 months post-onset. The sCr level was fixed at 1.1 mg/dL 20 months post-onset. This is the first report of MH-AKI in a TBM without the risk of MH-AKI development, such as bleeding tendency or iron overload. In this TBM, a colic attack of the renal urinary tract induced glomerular bleeding, and intolerance to hematuria may have caused severe tubular damage.

Contemporary review of IgA nephropathy

IgA nephropathy (IgAN) is considered the most common primary glomerulonephritis worldwide with a predilection for Asian-Pacific populations and relative rarity in those of African descent. Perhaps 20%-50% of patients progress to kidney failure. The pathogenesis is incompletely understood. Mesangial deposition of immune complexes containing galactose-deficient IgA1 complexed with anti-glycan IgG or IgA antibodies results in mesangial cell activation and proliferation, inflammatory cell recruitment, complement activation, and podocyte damage. Diagnosis requires a biopsy interpreted by the Oxford criteria. Additional pathologic features include podocytopathy, thrombotic microangiopathy, and C4d staining. Biomarkers predicting adverse outcomes include proteinuria, reduced GFR, hypertension, and pathology. Acceptable surrogate endpoints for therapeutic trials include ongoing proteinuria and rate of eGFR decline. The significance of persisting hematuria remains uncertain. The mainstay of therapy is supportive, consisting of lifestyle modifications, renin-angiotensin inhibition (if hypertensive or proteinuric), sodium-glucose-transporter 2 inhibition (if GFR reduced or proteinuric), and endothelin-receptor antagonism (if proteinuric). Immunosuppression should be considered for those at high risk after maximal supportive care. Corticosteroids are controversial with the most positive results observed in Chinese. They carry a high risk of serious side effects. Similarly, mycophenolate may be most effective in Chinese. Other immunosuppressants are of uncertain benefit. Tonsillectomy appears efficacious in Japanese. Active areas of investigation include B-cell inhibition with agents targeting the survival factors BAFF and APRIL and complement inhibition with agents targeting the alternate pathway (Factors B and D), the lectin pathway (MASP-2), and the common pathway (C3 and C5). Hopefully soon, the who and the how of immunosuppression will be clarified, and kidney failure can be forestalled.

Clinical Implications of C2 Lesion in IgA Nephropathy: A Cohort Study

INTRODUCTION

In 2016, the Oxford Classification of IgA nephropathy (IgAN) updated its scoring system for the glomerular crescents. Despite this, the clinical significance of crescentic lesions in the updated Oxford classification is still unexplored through prospective cohort studies.

METHODS

134 patients diagnosed with IgAN accompanied with C2 lesions at Peking University First Hospital were consecutively enrolled and prospectively followed up for analysis. Multivariate Cox regression in combination with LASSO regression was used to analyze risk factors associated with end-stage kidney disease (ESKD).

RESULTS

During biopsy, the mean estimated glomerular filtration rate (eGFR) was 39.3 mL/min/1.73 m2, and the mean proteinuria was 4.4 g/day. The proportion of kidney failure at 1 year, 2 years, and 3 years were 24%, 34%, and 47%, respectively. The results of LASSO in combination with Cox regression showed that mean arterial pressure (hazard ratio [HR] = 1.035, 95% confidence interval [95% CI] 1.013-1.056, p = 0.001), eGFR at biopsy (HR = 0.968, 95% CI [0.948-0.990], p < 0.004) and T2 lesions (HR = 2.490, 95% CI [1.179-5.259], p = 0.017) were independent risk factor associated with ESKD in patients with C2 lesions. Furthermore, based on univariate analyses, we found that patients with kidney function declined more than 50% within 3 months prior to biopsy or pathological findings indicated a proportion of crescents exceeding 50% were both associated with a poor kidney prognosis. Lastly, when the proportion of the crescent was less than 50%, patients receiving combined steroid and immunosuppressant treatment did not exhibit a better renal prognosis than those receiving steroid only.

CONCLUSION

Patients diagnosed with IgAN and concurrent C2 lesions exhibited a poor clinical prognosis, necessitating more effective treatment strategies.

Megalin-related mechanism of hemolysis-induced acute kidney injury and the therapeutic strategy

Hemolysis-induced acute kidney injury (AKI) is attributed to heme-mediated proximal tubule epithelial cell (PTEC) injury and tubular cast formation due to intratubular protein condensation. Megalin is a multiligand endocytic receptor for proteins, peptides, and drugs in PTECs and mediates the uptake of free hemoglobin and the heme-scavenging protein α1-microglobulin. However, understanding of how megalin is involved in the development of hemolysis-induced AKI remains elusive. Here, we investigated the megalin-related pathogenesis of hemolysis-induced AKI and a therapeutic strategy using cilastatin, a megalin blocker. A phenylhydrazine-induced hemolysis model developed in kidney-specific mosaic megalin knockout (MegKO) mice confirmed megalin-dependent PTEC injury revealed by the co-expression of kidney injury molecule-1 (KIM-1). In the hemolysis model in kidney-specific conditional MegKO mice, the uptake of hemoglobin and α1-microglobulin as well as KIM-1 expression in PTECs was suppressed, but tubular cast formation was augmented, likely due to the nonselective inhibition of protein reabsorption in PTECs. Quartz crystal microbalance analysis revealed that cilastatin suppressed the binding of megalin with hemoglobin and α1-microglobulin. Cilastatin also inhibited the specific uptake of fluorescent hemoglobin by megalin-expressing rat yolk sac tumor-derived L2 cells. In a mouse model of hemolysis-induced AKI, repeated cilastatin administration suppressed PTEC injury by inhibiting the uptake of hemoglobin and α1-microglobulin and also prevented cast formation. Hemopexin, another heme-scavenging protein, was also found to be a novel ligand of megalin, and its binding to megalin and uptake by PTECs in the hemolysis model were suppressed by cilastatin. Mass spectrometry-based semiquantitative analysis of urinary proteins in cilastatin-treated C57BL/6J mice indicated that cilastatin suppressed the reabsorption of a limited number of megalin ligands in PTECs, including α1-microglobulin and hemopexin. Collectively, cilastatin-mediated selective megalin blockade is an effective therapeutic strategy to prevent both heme-mediated PTEC injury and cast formation in hemolysis-induced AKI. © 2024 The Pathological Society of Great Britain and Ireland.

Role of Iron in Children With Immunoglobulin A Nephropathy and Macrohematuria-Induced Acute Kidney Injury

Introduction

The role of iron in, and the prognosis of, pediatric Immunoglobulin A nephropathy (IgAN) with macrohematuria (MH)-induced acute kidney injury (AKI) (MH-AKI) have not been evaluated. Thirty percent of adults with MH-AKI, and especially those who are older, show progression to chronic kidney disease.

Methods

We evaluated the immunohistopathologic characteristics of renal biopsy samples from pediatric patients with MH-AKI IgAN and controls, using Berlin Blue to identify iron, CD163 (a hemoglobin-scavenging receptor), and CD68 (a total macrophage marker), then compared the findings against the clinical characteristics of the patients.

Results

We enrolled 44 children as follows: 19 with IgAN but no MH or AKI; 5 with IgAN and MH but no AKI (MH(+)AKI(-) IgAN); 11 with MH-AKI IgAN; and 9 with no IgAN, MH, or AKI, according to a renal biopsy. Berlin Blue staining was detected predominantly at the injured tubulointerstitium, and the areas of staining in children with MH(+)AKI(-) and MH-AKI IgAN were significantly more extensive. The areas of Berlin Blue and CD163 staining did not perfectly match; however, areas of Berlin Blue were surrounded by immunopositivity for CD163. No children with MH-AKI IgAN showed decreased renal function at their last visit.

Conclusion

Children with IgAN and MH, with or without AKI, showed considerable iron deposition in their renal tubules. CD163-positive cells might scavenge hemoglobin in patients with MH-AKI IgAN, but not their roles as macrophages. The renal prognosis of pediatric MH-AKI IgAN is good.

Oral anticoagulant treatment and risk of kidney disease-a nationwide, population-based cohort study

Background

Direct oral anticoagulants (DOACs) are recommended as first-line treatment of atrial fibrillation. Whether DOAC use is associated with lower risks of kidney complications compared with vitamin K antagonists (VKAs) remains unclear. We examined this association in a nationwide, population-based cohort study.

Methods

We conducted a cohort study including patients initiating oral anticoagulant treatment within 3 months after an atrial fibrillation diagnosis in Denmark during 2012-18. Using routinely collected creatinine measurements from laboratory databases, we followed patients in an intention-to-treat approach for acute kidney injury (AKI) and chronic kidney disease (CKD) progression. We used propensity-score weighting to balance baseline confounders, computed weighted risks and weighted hazard ratios (HRs) with 95% confidence intervals (CIs) comparing DOACs with VKAs. We performed several subgroup analyses and a per-protocol analysis.

Results

We included 32 781 persons with atrial fibrillation initiating oral anticoagulation (77% initiating DOACs). The median age was 75 years, 25% had a baseline estimated glomerular filtration rate <60 mL/min/1.73 m2, and median follow-up was 2.3 (interquartile range 1.1-3.9) years. The weighted 1-year risks of AKI were 13.6% in DOAC users and 15.0% in VKA users (HR 0.86, 95% CI 0.82; 0.91). The weighted 5-year risks of CKD progression were 13.9% in DOAC users and 15.4% in VKA users (HR 0.85, 95% CI 0.79; 0.92). Results were similar across subgroups and in the per-protocol analysis.

Conclusions

Initiation of DOACs was associated with a decreased risk of AKI and CKD progression compared with VKAs. Despite the potential limitations of observational studies, our findings support the need for increased clinical awareness to prevent kidney complications among patients who initiate oral anticoagulants.

Intravascular hemolysis triggers NAFLD characterized by a deregulation of lipid metabolism and lipophagy blockade

Intravascular hemolysis is a common feature of different clinical entities, including sickle cell disease and malaria. Chronic hemolytic disorders are associated with hepatic damage; however, it is unknown whether heme disturbs lipid metabolism and promotes liver steatosis, thereby favoring the progression to nonalcoholic fatty liver disease (NAFLD). Using an experimental model of acute intravascular hemolysis, we report here the presence of liver injury in association with microvesicular lipid droplet deposition. Hemolysis promoted serum hyperlipidemia and altered intrahepatic triglyceride fatty acid composition, with increments in oleic, palmitoleic, and palmitic acids. These findings were related to augmented expression of transporters involved in fatty acid uptake (CD36 and MSR1) and deregulation of LDL transport, as demonstrated by decreased levels of LDL receptor and increased PCSK9 expression. Hemolysis also upregulated hepatic enzymes associated with cholesterol biosynthesis (SREBP2, HMGC1, LCAT, SOAT1) and transcription factors regulating lipid metabolism (SREBP1). Increased LC3II/LC3I ratio and p62/SQSTM1 protein levels were reported in mice with intravascular hemolysis and hepatocytes stimulated with heme, indicating a blockade of lipophagy. In cultured hepatocytes, cell pretreatment with the autophagy inductor rapamycin diminished heme-mediated toxicity and accumulation of lipid droplets. In conclusion, intravascular hemolysis enhances liver damage by exacerbating lipid accumulation and blocking the lipophagy pathway, thereby promoting NAFLD. These new findings have a high translational potential as a novel NAFLD-promoting mechanism in individuals suffering from severe hemolysis episodes. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Predictors of Gross Hematuria After SARS-CoV-2 mRNA Vaccination in Patients with IgA Nephropathy

Key Points

Little is known about the clinical characteristics of patients with immunoglobulin A nephropathy (IgAN) who present with gross hematuria in relation to SARS-CoV-2 mRNA vaccination. The relationship between the clinical features in patients with IgAN at the time of SARS-CoV-2 mRNA vaccination and the subsequent appearance of gross hematuria was investigated. This study demonstrates the clinical significance of microscopic hematuria in patients with IgAN as a predictor of gross hematuria after SARS-CoV-2 mRNA vaccination.

Background

There have been several reports of immunoglobulin A nephropathy (IgAN) patients with gross hematuria and acute deterioration of urinary findings and kidney function after severe acute respiratory syndrome coronavirus 2 mRNA vaccination. Recent case series studies have indicated a possible link between the status of urinary findings at the time of vaccination and the subsequent appearance of gross hematuria. In this study, we aimed to determine whether the status of prevaccination urinary findings was associated with postvaccination gross hematuria in patients already diagnosed with IgAN.

Methods

Outpatients with IgAN who had been followed up before vaccination were included. We analyzed the association between the remission of prevaccination microscopic hematuria (urine sediment <5 red blood cells/high-power field) or proteinuria (<0.3 g/gCr) and postvaccination gross hematuria.

Results

A total of 417 Japanese patients with IgAN (median age, 51 years; 56% female; eGFR, 58 ml/min per 1.73 m2) were included. The frequency of gross hematuria after vaccination was higher in 20 of 123 patients (16.3%) with microscopic hematuria than in 5 of 294 patients (1.7%) without microscopic hematuria before vaccination (P < 0.001). There was no association between prevaccination proteinuria and postvaccination gross hematuria. After adjusting for potential confounders, such as sex (female), age (younger than 50 years), eGFR (≥60 ml/min per 1.73 m2), and histories of tonsillectomy and corticosteroid therapy, prevaccination microscopic hematuria was still associated with postvaccination gross hematuria (odds ratio, 8.98; P < 0.001). As the severity of prevaccination microscopic hematuria increased, the incidence of postvaccination gross hematuria increased (P < 0.001).

Conclusions

Prevaccination microscopic hematuria in patients with IgAN is a major predictor of postvaccination gross hematuria, regardless of potential confounders, including previous treatments of IgAN.

Carboxyhemoglobin (COHb): Unavoidable Bystander or Protective Player?

Carbon monoxide (CO) is a cytoprotective endogenous gas that is ubiquitously produced by the stress response enzyme heme-oxygenase. Being a gas, CO rapidly diffuses through tissues and binds to hemoglobin (Hb) increasing carboxyhemoglobin (COHb) levels. COHb can be formed in erythrocytes or in plasma from cell-free Hb. Herein, it is discussed as to whether endogenous COHb is an innocuous and inevitable metabolic waste product or not, and it is hypothesized that COHb has a biological role. In the present review, literature data are presented to support this hypothesis based on two main premises: (i) there is no direct correlation between COHb levels and CO toxicity, and (ii) COHb seems to have a direct cytoprotective and antioxidant role in erythrocytes and in hemorrhagic models in vivo. Moreover, CO is also an antioxidant by generating COHb, which protects against the pro-oxidant damaging effects of cell-free Hb. Up to now, COHb has been considered as a sink for both exogenous and endogenous CO generated during CO intoxication or heme metabolism, respectively. Hallmarking COHb as an important molecule with a biological (and eventually beneficial) role is a turning point in CO biology research, namely in CO intoxication and CO cytoprotection.

Regulated cell death pathways in kidney disease

Disorders of cell number that result from an imbalance between the death of parenchymal cells and the proliferation or recruitment of maladaptive cells contributes to the pathogenesis of kidney disease. Acute kidney injury can result from an acute loss of kidney epithelial cells. In chronic kidney disease, loss of kidney epithelial cells leads to glomerulosclerosis and tubular atrophy, whereas interstitial inflammation and fibrosis result from an excess of leukocytes and myofibroblasts. Other conditions, such as acquired cystic disease and kidney cancer, are characterized by excess numbers of cyst wall and malignant cells, respectively. Cell death modalities act to clear unwanted cells, but disproportionate responses can contribute to the detrimental loss of kidney cells. Indeed, pathways of regulated cell death - including apoptosis and necrosis - have emerged as central events in the pathogenesis of various kidney diseases that may be amenable to therapeutic intervention. Modes of regulated necrosis, such as ferroptosis, necroptosis and pyroptosis may cause kidney injury directly or through the recruitment of immune cells and stimulation of inflammatory responses. Importantly, multiple layers of interconnections exist between different modalities of regulated cell death, including shared triggers, molecular components and protective mechanisms.

Association between microscopic hematuria and albuminuria in patients with chronic kidney disease caused by diabetes and hypertension: the Fukuoka Kidney disease Registry Study

BACKGROUND

The association between microscopic hematuria (MH) and albuminuria in patients with chronic kidney disease (CKD) caused by diabetes and hypertension remains unclear.

METHODS

The Fukuoka Kidney disease Registry Study is a Japanese multicenter prospective cohort study of 4476 patients with non-dialysis-dependent CKD. In this cohort, we conducted a cross-sectional study in 994 patients with diabetic nephropathy and hypertensive nephrosclerosis. Patients were divided into three groups according to erythrocyte count in urine sediment [T1: < 5/high power field (HPF); T2: 5-9/HPF; T3: ≥ 10/HPF]. Macroalbuminuria was defined as urinary albumin-creatinine ratio > 300 mg/g. Associations between the degree of MH (T1-T3) and the prevalence of macroalbuminuria were analyzed using logistic regression.

RESULTS

The prevalence of macroalbuminuria was 50.8%, 50.4%, and 67.4% in T1 (n = 725), T2 (n = 226), and T3 (n = 43), respectively. The multivariable-adjusted odds ratios for the presence of macroalbuminuria were 0.95 [95% confidence interval (CI) 0.65-1.39; P = 0.86] and 2.50 (95% CI 1.15-5.47; P = 0.022) for patients in T2 and T3, respectively, compared with patients in T1.

CONCLUSIONS

MH with erythrocytes ≥ 10/HPF was significantly associated with increased prevalence of macroalbuminuria in patients with non-dialysis-dependent CKD caused by diabetes and hypertension.

Podocytes are likely the therapeutic target of IgA nephropathy with isolated hematuria: Evidence from repeat renal biopsy

Background: The present study aimed to prove the progression of immunoglobulin A nephropathy (IgAN) patients with isolated hematuria based on repeat renal biopsy data for the first time. Methods: 29 IgAN patients with isolated hematuria who received repeat renal biopsies were analyzed retrospectively, while 29 non-isolated hematuria IgAN patients with similar age and background were randomly selected as the control group. Clinical parameters were collected at the time of biopsy. The treatment strategies (conservative treatment with RASS blocker or immunosuppressive treatment) were choosen according to the pathological results at the first renal biopsy. The activity and chronicity indexes of renal lesions were evaluated. Markers of cell inflammation and proliferation were tseted by immunochemistry. The ultrastructure of podocytes was observed by transmission electron microscopy (TEM). Podocyte and oxidative stress marker (NPHS2 and 4-HNE) were detected by immunofluorescence. Results: The IgAN patients with isolated hematuria had better clinical indicators than those with no-isolated hematuria, such as better renal function, higher albumin and lower uric acid. The interval between two biopsies in IgAN patients with isolated hematuria was 630 (interquartile range, 409.5-1,171) days. The hematuria of the patients decreased significantly from 30 (IQR, 4.00-35.00) RBC/ul in the first biopsy to 11 (IQR, 2.50-30.00) RBC/ul in the repeated biopsy (p < 0.05). The level of triglyceride decreased significantly (p < 0.05). The other clinical indicators were not statistically significant (p > 0.05). Deposits of IgA and C3 in the glomerulus were persistent. The activity index decreased, especially cellular crescent formation, while the chronicity index increased. The ultrastructure of podocytes was improved after treatment. The oxidative stress products of podocytes reduced after treatment. Conclusion: Although the clinical indicators of the IgAN patients with isolated hematuria were in the normal range, various acute and chronic pathological changes have occurred, and irreversible chronic changes have been progressing. Cell inflammation and proliferation persisted. Oxidative stress of podocytes was likely to be the therapeutic target. This study provided a strong basis for the progress of IgAN with isolated hematuria through pathological changes before and after treatment. This study will help clinicians recognize the harm of hematuria, change the traditional treatment concept, and help such patients get early treatment.

Effect of hemoglobin on Nile tilapia (Oreochromis niloticus) kidney (NTK) cell line damage

Bacteria or viral outbreaks can cause tilapia hemorrhage, ensuring considerable volume of hemoglobin (Hb) into the tissue. However, the hemoglobin toxicity on tissue and high doses also effect on tissue this phenomena is still under consideration. Therefore, current study exploited Nile tilapia kidney (NTK) cells to deeply expose the toxic effect of Hb on NTK cells. Toxicity of Hb on NTK cells was determined in terms of cells growth, expression of iron metabolism and inflammation-related genes, consequently examined antioxidant-related enzymes genes expression, intracellular iron and reactive oxygen species (ROS) contents, and apoptosis-related genes expression. The results showed that Hb and heme significantly inhibited NTK cells growth and up-regulated iron metabolism-related genes expression in different degrees. The Hb and heme activated the expression of pro-inflammatory cytokines (TNF-α, tumor necrosis factor-α; IL-1β, interleukin 1β; IL-6, interleukin 6), the anti-inflammatory factor (IL-10, interleukin 10) and the chemotactic factors (IL-4, interleukin 4; IL-8, interleukin 8) through NF-κB pathway, meanwhile activated the expression of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px). Moreover, the Hb significantly increased intracellular iron and ROS contents while the expression of apoptosis-related genes was significantly activated by both Hb and heme. Current investigation suggested that high oxidative activity of Hb could activate iron metabolism- and inflammation-related genes expression, and increase intracellular iron and ROS levels, lead to up-regulated the expression of apoptosis genes in NTK cells.

Rapidly progressive IgA nephropathy: clinicopathological characteristics and outcomes assessed according to the revised definition of the KDIGO 2021 Guideline

BACKGROUND

Rapidly progressive immunoglobulin A nephropathy (RPIgAN) is a severe clinical phenotype of IgAN associated with a poor outcome. The recently published Kidney Disease: Improving Global Outcomes (KDIGO) 2021 Guideline for the Management of Glomerular Diseases has proposed a new definition for RPIgAN that is based simply on a ≥50% decline in the estimated glomerular filtration rate (eGFR) over ≤3 months.

METHODS

In 1677 IgAN patients followed at a single centre in China, we evaluated the utility of this new definition to identify the highest-risk IgAN patients who might be suitable for combination immunosuppressive therapy.

RESULTS

The proportion of a ≥50% decline in eGFR over ≤3 months was 5.2%. The majority of these patients had reversible causes, with only 2.3% (39/1677) meeting the KDIGO 2021 criteria for RPIgAN. These patients had a significantly higher risk for end-stage kidney disease (ESKD) than non-RPIgAN patients (logrank P < 0.001). RPIgAN was an independent risk factor for ESKD [hazard ratio 3.99 (95% confidence interval 2.25-7.09); P <0.001]. A minority of the RPIgAN patients (25.6%) had ≥50% crescents. There was no significant difference in the risk for ESKD between patients in the RPIgAN group with ≥50% crescents and ˂50% crescents (logrank P = 0.27). Patients with RPIgAN and ≥50% crescents had a higher risk for ESKD than patients with non-RPIgAN and ≥50% crescents (logrank P = 0.04).

CONCLUSIONS

These data support the validity of the KDIGO 2021 definition but require independent validation in other non-Chinese cohorts.

Time-Averaged Hematuria as a Prognostic Indicator of Renal Outcome in Patients with IgA Nephropathy

We aim to investigate the association of time-averaged hematuria (TA-hematuria) with the progression of IgA nephropathy (IgAN). Based on TA-hematuria during follow-up, 152 patients with IgAN were divided into a hematuria remission group (≤28 red blood cells [RBCs]/μL) and a persistent hematuria group (>28 RBCs/μL). The persistent hematuria group had a higher percentage of patients with macroscopic hematuria, lower levels of hemoglobin and TA-serum albumin, and more severe renal pathologic lesions. The composite endpoint is defined as a doubling of the baseline SCr level (D-SCr), or the presence of ESRD. During the mean follow-up of 58.08 ± 23.51 months, 15 patients (9.9%) reached the primary outcome of ESRD and 19 patients (12.5%) reached the combined renal endpoint. Kaplan-Meier analysis showed that the persistent hematuria group had a lower renal survival rate. The persistent hematuria patients who were incorporated with proteinuria (≥1.0 g/day) and low TA-serum albumin (<40 g/L) had the worst renal outcomes. Multivariate Cox regression indicated that TA-hematuria (hazard ratio [HR] = 0.004, 95% CI: 0.001, 0.008; p = 0.010) was independently associated with the progression of IgAN. Receiver operating characteristic analysis indicated the optimal TA-hematuria cutoff value for predicting the progression of IgAN was 201.21 RBCs/μL in females and 37.25 RBCs/μL in males.

IgA nephropathy with acute kidney disease: Characteristics, prognosis, and causes

BACKGROUND

The clinical manifestations and prognosis of IgA nephropathy (IgAN) are diverse. Some patients may present with kidney dysfunction lasting shorter than 3 months and meet the acute kidney disease (AKD) criteria. This study aimed to investigate the clinicopathological features, causes and prognosis of newly diagnosed cases of IgAN with AKD.

METHODS

1320 IgAN patients diagnosed via kidney biopsy between January 2012 and June 2018 were included in this retrospective study, with a median follow-up period of 35 months. We analyzed the clinicopathological, etiological variables, as well as short-term and long-term prognosis. The main outcome was a composite event of 40% decline in eGFR, kidney failure or death.

RESULTS

Incidence of AKD was 8.8% in the newly diagnosed IgAN patients, and was found to be an independent risk factor affecting the short-term (HR, 7.1; 95% CI, 2.3-22.2; P = 0.001) and long-term (HR, 1.8; 95% CI, 1.2-2.6; P = 0.006) prognosis, respectively. The most common cause of AKD was malignant hypertension-related AKD (MHT-AKD; 24.1%), followed by hematuria-related AKD (H-AKD; 12.9%), nephrotoxic-drug-exposure-related AKD (NTDE-AKD; 12.1%) and crescents-related AKD (C-AKD; 11.2%). The patients in AKD group had more severe clinicopathological characteristics and poor short-term and long-term prognosis than non-AKD group. In subgroup analysis, the MHT-AKD had the worst 5 years survival rate, followed by NTDE-AKD and C-AKD, whereas H-AKD had the best survival rate.

CONCLUSIONS

AKD is not rare among IgAN patients, and is an independent risk factor for short-term and long-term prognosis. IgAN patients with AKD resulting from different causes have different prognosis.

Blocking Periostin Prevented Development of Inflammation in Rhabdomyolysis-Induced Acute Kidney Injury Mice Model

Background: Rhabdomyolysis is the collapse of damaged skeletal muscle and the leakage of muscle-cell contents, such as electrolytes, myoglobin, and other sarcoplasmic proteins, into the circulation. The glomeruli filtered these products, leading to acute kidney injury (AKI) through several mechanisms, such as intratubular obstruction secondary to protein precipitation. The prognosis is highly mutable and depends on the underlying complications and etiologies. New therapeutic plans to reduce AKI are now needed. Up to now, several cellular pathways, with the nuclear factor kappa beta (NF-kB), as well as the proinflammatory effects on epithelial and tubular epithelial cells, have been recognized as the major pathway for the initiation of the matrix-producing cells in AKI. Recently, it has been mentioned that periostin (POSTN), an extracellular matrix protein, is involved in the development of inflammation through the modulation of the NF-kB pathway. However, how POSTN develops the inflammation protection in AKI by rhabdomyolysis is uncertain. This study aimed to investigate the role of POSTN in a rhabdomyolysis mice model of AKI induced by an intramuscular injection of 50% glycerol. Methods: In vivo, we performed an intramuscular injection of 50% glycerol (5 mg/kg body weight) to make rhabdomyolysis-induced AKI. We examined the expression level of POSTN through the progression of AKI after glycerol intramuscular injection for C57BL/6J wildtype (WT) mice. We sacrificed mice at 72 h after glycerol injection. We made periostin-null mice to examine the role of POSTN in acute renal failure. The role of periostin was further examined through in vitro methods. The development of renal inflammation is linked with the NF-kB pathway. To examine the POSTN function, we administrated hemin (100 μM) on NIH-3T3 fibroblast cells, and the following signaling pathways were examined. Results: The expression of periostin was highly increased, peaking at about 72 h after glycerol injection. The expression of inflammation-associated mRNAs such as monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-a) and IL-6, and tubular injury score in H-E staining were more reduced in POSTN-null mice than WT mice at 72 h after glycerol injection. Conclusion: POSTN was highly expressed in the kidney through rhabdomyolysis and was a positive regulator of AKI. Targeting POSTN might propose a new therapeutic strategy against the development of acute renal failure.

Urinary Protein Profiling for Potential Biomarkers of Chronic Kidney Disease: A Pilot Study

Proteinuria is a risk factor for chronic kidney disease (CKD) progression and associated complications. However, there is insufficient information on individual protein components in urine and the severity of CKD. We aimed to investigate urinary proteomics and its association with proteinuria and kidney function in early-stage CKD and in healthy individuals. A 24 h urine sample of 42 individuals (21-CKD and 21-healthy individuals) was used for mass spectrometry-based proteomics analysis. An exponentially modified protein abundance index (emPAI) was calculated for each protein. Data were analyzed by Mascot software using the SwissProt database and bioinformatics tools. Overall, 298 unique proteins were identified in the cohort; of them, 250 proteins belong to the control group with median (IQR) emPAI 39.1 (19−53) and 142 proteins belong to the CKD group with median (IQR) emPAI 67.8 (49−117). The level of 24 h proteinuria positively correlated with emPAI (r = 0.390, p = 0.011). The emPAI of some urinary proteomics had close positive (ALBU, ZA2G, IGKC) and negative (OSTP, CD59, UROM, KNG1, RNAS1, CD44, AMBP) correlations (r < 0.419, p < 0.001) with 24 h proteinuria levels. Additionally, a few proteins (VTDB, AACT, A1AG2, VTNC, and CD44) significantly correlated with kidney function. In this proteomics study, several urinary proteins correlated with proteinuria and kidney function. Pathway analysis identified subpathways potentially related to early proteinuric CKD, allowing the design of prospective studies that explore their response to therapy and their relationship to long-term outcomes.

The severity of acute kidney injury correlates with plasma venom levels in Bothrops atrox envenomings

The Brazilian Amazon has high rates of snakebite envenomings (SBEs), with ∼90% caused by Bothrops atrox. Envenomings by this species can trigger local and systemic effects, such as acute kidney injury (AKI). Our aim was to identify predictors of AKI in Bothrops SBEs in patients from Manaus, Western Brazilian Amazon. A total of 127 patients were enrolled, with a predominance of men between 16 and 45 years old from rural areas. Of the 127 patients, 38.6% developed AKI, with 61.2% presenting stage I, 34.7% presenting stage II and 4.1% presenting stage III severity. The age groups 0-10 years and ≥60 years presented a significantly higher frequency of AKI compared to the 11-40 years group. Moderate/severe edema in the affeccted limb was significantly associated with lower risk of AKI [p = 0.01; OR = 0.11 (95%CI 0.02-0.53)]. Nausea [p = 0.01; OR = 54.44 (95%CI = 3.26-909.27)] and high blood urea levels [p = 0.01; OR = 5.38 (95%CI = 2.12-13.66)] were risk factors for AKI. There was a significant positive correlation between circulating venom levels and the highest creatinine serum values during the hospital stay (p = 0.03) and with the difference between the maximum creatinine levels and the creatinine levels on admission (p = 0.02). A positive correlation between serum venom concentrations and creatinine levels suggests a direct or indirect dose-dependent participation of the venom toxins in the pathogenesis of AKI.

An evaluation of the roles of hematuria and uric acid in defining the prognosis of patients with IgA nephropathy

In recent years, many significant advances have been made in determining which clinical manifestations and pathologic lesions can provide prognostic information for patients with IgA nephropathy (IgAN). However, some important questions remain, including the long-term consequences of hematuria, both macroscopic (MH) and microscopic (mH), in patients with IgAN. The importance of distinguishing patients who have a single episode of MH of long duration from those with recurrent episodes of short duration and the prognostic importance of the episodes of acute kidney injury (AKI) that sometimes accompany episodic MH will be discussed. Studies that have evaluated the mechanisms that may be responsible for recurrent MH and the toxic effects of red blood cells (RBCs), or their constituents, on kidney tubules will also be addressed. In the last section, I will review the evidence that hyperuricemia (HU) may be a significant independent risk factor for progressive kidney disease in patients with IgAN.

The Oxidative Injury of Extracellular Hemoglobin Is Associated With Reactive Oxygen Species Generation of Grass Carp (Ctenopharyngodon idella)

Intravascular hemolysis is a fundamental feature of hemorrhagic venereal infection or tissue and releases the endogenous damage-associated molecular pattern hemoglobin (Hb) into the plasma or tissues, which results in systemic inflammation, vasomotor dysfunction, thrombophilia, and proliferative vasculopathy. However, how the cytotoxic Hb affects the tissues of grass carp remains unclear. Here, we established a hemolysis model in grass carp by injecting phenylhydrazine (PHZ). The data revealed that the PHZ-induced hemolysis increased the content of Hb and activated the antioxidant system in plasma. The histopathology analysis data showed that the PHZ-induced hemolysis increased the accumulation of Hb and iron both in the head and middle kidney. The results of quantitative real-time PCR (qRT-PCR) detection suggested that the hemolysis upregulated the expressions of iron metabolism-related genes. In addition, the immunofluorescence and immunohistochemistry data revealed that the hemolysis caused an obvious deposition of collagen fiber, malondialdehyde (MDA), and 4-hydroxynonenal (4-HNE) accumulation and increased the content of oxidative-related enzymes such as β-galactosidase (β-GAL), lipid peroxide (LPO), and MDA in both the head and middle kidney. Furthermore, the PHZ-induced hemolysis significantly increased the production of reactive oxygen species (ROS), which resulted in apoptosis and modulated the expressions of cytokine-related genes. Taken together, excess of Hb released from hemolysis caused tissue oxidative damage, which may be associated with ROS and inflammation generation.

IgA nephropathy is the most common underlying disease in patients with anticoagulant-related nephropathy

Introduction

Anticoagulant-related nephropathy (ARN) is a relatively novel recognized entity characterized by hematuria-associated acute kidney injury (AKI) in the context of overanticoagulation. Preexisting or underlying kidney disease seems to be a predisposing factor; however, few studies have described histologic findings in patients with ARN. We aimed to evaluate underlying kidney pathology in patients on oral anticoagulation who presented an episode of AKI with hematuria in whom a kidney biopsy was performed.

Methods

Retrospective observational multicenter case study in patients treated with oral anticoagulants who developed macroscopic or intense hematuria followed by AKI. Only patients with available kidney biopsy specimens were included. Histologic findings and clinical data throughout follow-up were analyzed.

Results

A total of 26 patients were included with a median age of 75 years (62–80) and a follow-up period of 10.1 months. Of the patients, 80% were male, and most cases (92%) were on anticoagulation with vitamin K antagonists (VKAs). At admission, median serum creatinine (SCr) level was 4.2 mg/dl (2.8–8.2), median international normalized ratio (INR) 2.4 (1.5–3.4), and 11 patients (42%) required acute dialysis during hospitalization. Kidney biopsy results revealed that all patients except 1 had an underlying nephropathy: IgA nephropathy (IgAN) in 19, probable IgAN in 1, diabetic nephropathy in 3, nephrosclerosis in 1, and idiopathic nodular glomerulosclerosis in 1. At 12 weeks after discharge, only 6 subjects (24%) attained complete kidney recovery whereas 7 (28%) remained on chronic dialysis.

Conclusion

IgAN was the most common underlying kidney disease in our biopsy-proven series of ARN, in which a significant percentage of patients did not achieve kidney function recovery.

Physiology of Continuous-Flow Left Ventricular Assist Device Therapy

The expanding use of continuous-flow left ventricular assist devices (CF-LVADs) for end-stage heart failure warrants familiarity with the physiologic interaction of the device with the native circulation. Contemporary devices utilize predominantly centrifugal flow and, to a lesser extent, axial flow rotors that vary with respect to their intrinsic flow characteristics. Flow can be manipulated with adjustments to preload and afterload as in the native heart, and ascertainment of the predicted effects is provided by differential pressure-flow (H-Q) curves or loops. Valvular heart disease, especially aortic regurgitation, may significantly affect adequacy of mechanical support. In contrast, atrioventricular and ventriculoventricular timing is of less certain significance. Although beneficial effects of device therapy are typically seen due to enhanced distal perfusion, unloading of the left ventricle and atrium, and amelioration of secondary pulmonary hypertension, negative effects of CF-LVAD therapy on right ventricular filling and function, through right-sided loading and septal interaction, can make optimization challenging. Additionally, a lack of pulsatile energy provided by CF-LVAD therapy has physiologic consequences for end-organ function and may be responsible for a series of adverse effects. Rheological effects of intravascular pumps, especially shear stress exposure, result in platelet activation and hemolysis, which may result in both thrombotic and hemorrhagic consequences. Development of novel solutions for untoward device-circulatory interactions will facilitate hemodynamic support while mitigating adverse events. © 2021 American Physiological Society. Compr Physiol 12:1-37, 2021.

Sequential Organ Failure Assessment Score for Prediction of Mortality of Patients With Rhabdomyolysis Following Exertional Heatstroke: A Longitudinal Cohort Study in Southern China

Background: Heatstroke is a medical emergency that causes multi-organ injury and death without intervention, but limited data are available on the illness scores in predicting the outcomes of exertional heat stroke (EHS) with rhabdomyolysis (RM). The aim of our study was to investigate the Sequential Organ Failure Assessment (SOFA) score in predicting mortality of patients with RM after EHS. Methods: A retrospective cohort study was performed, which included all patients with EHS admitted into the intensive care unit (ICU) of General Hospital of Southern Theater Command of Peoples Liberation Army from January 2008 to June 2019. RM was defined as creatine kinase (CK) > 1,000 U/L. Data, including the baseline data at admission, vital organ function indicators, and 90-day mortality, were reviewed. Results: A total of 176 patients were enrolled; among them, 85 (48.3%) had RM. Patients with RM had a significantly higher SOFA score (4.0 vs. 3.0, p = 0.021), higher occurrence rates of disseminated intravascular coagulation (DIC) (53.1 vs. 18.3%, p < 0.001) and acute liver injury (ALI) (21.4 vs. 5.5%, p = 0.002) than patients with non-RM. RM was positively correlated with ALI and DIC, and the correlation coefficients were 0.236 and 0.365, respectively (both p-values <0.01). Multivariate logistics analysis showed that the SOFA score [odds ratio (OR) 1.7, 95% CI 1.1-2.6, p = 0.024] was the risk factor for 90-day mortality in patients with RM after EHS, with the area under the curve (AUC) 0.958 (95% CI 0.908-1.000, p < 0.001) and the optimal cutoff 7.5 points. Conclusions: Patients with RM after EHS have severe clinical conditions, which are often accompanied by DIC or ALI. The SOFA score could predict the prognosis of patients with RM with EHS. Early treatment strategies based on decreasing the SOFA score at admission may be pivotal to reduce the 90-day mortality of patients with EHS.

Association of Hematuria with Renal Progression and Survival in Patients Who Underwent Living Donor Liver Transplant

Background: This study aimed to determine the association between episodic or persistent hematuria after liver transplantation and long-term renal outcomes. Methods: Patients who underwent living donor liver transplantation between July 2005 and June 2019 were recruited and divided into two groups based on the finding of microscopic or gross hematuria after transplantation. All patients were followed up from the index date until the end date in May 2020. The risks of chronic kidney disease, death, and 30% and 50% declines in estimated glomerular filtration rate (eGFR) were compared between groups. Results: A total of 295 patients underwent urinalysis for various reasons after undergoing transplantation. Hematuria was detected in 100 patients (group A) but was not present in 195 patients (group B). Compared with group B, group A had a higher risk of renal progression, including eGFR decline >50% [aHR = 3.447 (95%CI: 2.24~5.30), p < 0.001] and worse survival. In addition, patients who took non-steroidal anti-inflammatory drugs (NSAIDs) continuously for over seven days within six months before transplant surgery had high risks of rapid renal progression, including a >30% decline in eGFR [aHR = 1.572 (95%CI: 1.12~2.21), p = 0.009)]. Conclusion: Development of hematuria after surgery in patients who underwent living donor liver transplant and were exposed to NSAIDs before surgery were associated with worse long-term renal dysfunction and survival.

Current treatment of IgA nephropathy

IgA nephropathy (IgAN) is the most common type of glomerulonephritis in Asia and the Western world. In most patients, it follows an asymptomatic to oligosymptomatic course and GFR loss, if any, is slow. The mainstay of therapy therefore is optimized supportive care, i.e., measures that lower blood pressure, reduce proteinuria, minimize lifestyle risk factors, and otherwise help to reduce non-specific insults to the kidneys. The value of immunosuppression has become controversial and if at all, systemic high-dose corticosteroid therapy should be considered for a few months taking into account patient characteristics that would caution against or preclude such therapy. In addition, adverse events related to corticosteroid therapy markedly increase as GFR declines. Beyond corticosteroids, there is little evidence that any additional immunosuppression is helpful, with the exception of mycophenolate mofetil in patients of Asian descent. A considerable number of clinical trials ranging from enteric coated budesonide to blockade of B-cell function to complement inhibitors are currently ongoing and will hopefully allow a more targeted therapy of high-risk patients with progressive IgAN in the future.

Sickle cell nephropathy. Clinical manifestations and new mechanisms involved in kidney injury

Kidney problems are among the most common complications in sickle cell disease (SCD). They occur early in childhood and are one of the main factors related to mortality in these patients. The main underlying pathogenic mechanisms are vaso-occlusion and haemolysis. The renal medulla has ideal conditions for the sickling of red cells due to its low partial pressure of oxygen, high osmolarity and acidic pH. Initially, sickle-cell formation in the vasa recta of the renal medulla causes hyposthenuria. This is universal and appears in early childhood. Microscopic and macroscopic haematuria also occur, in part related to renal papillary necrosis when the infarcts are extensive. Release of prostaglandins in the renal medulla due to ischaemia leads to an increase in the glomerular filtration rate (GFR). Adaptively, sodium reabsorption in the proximal tubule increases, accompanied by increased creatinine secretion. Therefore, the GFR estimated from creatinine may be overestimated. Focal segmental glomerulosclerosis is the most common glomerular disease. Albuminuria is very common and reduction has been found in 72.8% of subjects treated with ACE inhibitors or ARB. Recent evidence suggests that free haemoglobin has harmful effects on podocytes, and may be a mechanism involved in impaired kidney function in these patients. These effects need to be better studied in SCD, as they could provide a therapeutic alternative in sickle cell nephropathy.

Precision medicine in immunoglobulin A nephropathy: still a journey ahead

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerular disease worldwide and since its first description extensive research has identified a number of key central pathogenetic contributors, including genetic, immunological and environmental factors. Along with its multifaceted pathophysiology, the clinical presentation of IgAN varies, ranging from mild forms with only minor urinary findings and preserved renal function to cases that rapidly progress to end-stage renal disease. Because of this, early identification of patients at risk for a progressive course is urgently needed. The search for valid and easily accessible biomarkers showed urinary Dickkopf-3 as a promising candidate to predict the course of kidney function. In addition, a recently established IgAN risk prediction tool derived from an international cohort of IgAN patients allows estimation of the risk of a 50% loss of kidney function over several years upon diagnosis. This might serve as a significant tool to individually predict the course of renal function by combining biometric, clinical, histological and treatment information at the time of diagnosis. Today there is no doubt that a comprehensive supportive treatment regimen is the main pillar for all IgAN patients. The value of an additional immunosuppressive treatment in IgAN patients at risk for disease progression is less clear. Early risk stratification and individualized therapies would be desirable for IgAN patients to facilitate the choice of treatment strategies, which is still a matter of ongoing discussion.

Renal hemosiderosis presenting with acute kidney Injury and macroscopic hematuria in Immunoglobulin A nephropathy: a case report

Background

Macroscopic hematuria-associated acute kidney injury (AKI) is a well-known complication of immunoglobulin A (IgA) nephropathy. In such cases, intratubular obstruction by red blood cell (RBC) casts and acute tubular necrosis are mainly observed pathologically. Herein, we report the case of a patient with IgA nephropathy presenting with AKI following an episode of macrohematuria. The patient presented with severe renal tubular hemosiderosis and acute tubular necrosis and without any obvious obstructive RBC casts.

Case presentation

A 68-year-old woman, who was diagnosed with IgA nephropathy on renal biopsy 6 years ago, was admitted to our hospital after an episode of macroscopic glomerular hematuria and AKI following upper respiratory tract infection. Renal biopsy showed mesangial proliferation of the glomeruli, including crescent formation in 17 % of the glomeruli, and acute tubular necrosis without obvious hemorrhage or obstructive RBC casts. The application of Perls’ Prussian blue stain showed hemosiderin deposition in the renal proximal tubular cells. Immunofluorescence showed granular mesangial deposits of IgA and C3. Based on these findings, she was diagnosed with acute tubular necrosis with a concurrent IgA nephropathy flare-up. Moreover, direct tubular injury by heme and iron was considered to be the cause of AKI. She was treated with intravenous pulse methylprednisolone followed by oral prednisolone. Thereafter, the gross hematuria gradually faded, and her serum creatinine levels decreased.

Conclusions

IgA nephropathy presenting with acute kidney injury accompanied by macrohematuria may cause renal hemosiderosis and acute tubular necrosis without obstructive RBC casts. Hemosiderosis may be a useful indicator for determining the pathophysiology of macroscopic hematuria-associated AKI. However, renal hemosiderosis may remain undiagnosed. Thus, Perls’ Prussian blue iron staining should be more widely used in patients presenting with hematuria.

Sickle cell nephropathy. Clinical manifestations and new mechanisms involved in kidney injury

Kidney problems are among the most common complications in sickle cell disease (SCD). They occur early in childhood and are one of the main factors related to mortality in these patients. The main underlying pathogenic mechanisms are vaso-occlusion and haemolysis. The renal medulla has ideal conditions for the sickling of red cells due to its low partial pressure of oxygen, high osmolarity and acidic pH. Initially, sickle-cell formation in the vasa recta of the renal medulla causes hyposthenuria. This is universal and appears in early childhood. Microscopic and macroscopic haematuria also occur, in part related to renal papillary necrosis when the infarcts are extensive. Release of prostaglandins in the renal medulla due to ischaemia leads to an increase in the glomerular filtration rate (GFR). Adaptively, sodium reabsorption in the proximal tubule increases, accompanied by increased creatinine secretion. Therefore, the GFR estimated from creatinine may be overestimated. Focal segmental glomerulosclerosis is the most common glomerular disease. Albuminuria is very common and reduction has been found in 72.8% of subjects treated with ACE inhibitors or ARB. Recent evidence suggests that free haemoglobin has harmful effects on podocytes, and may be a mechanism involved in impaired kidney function in these patients. These effects need to be better studied in SCD, as they could provide a therapeutic alternative in sickle cell nephropathy.

Hematuria was a high risk for renal progression and ESRD in immunoglobulin a nephropathy: a systematic review and meta-analysis

Background: The relationship between hematuria, a typical presentation of immunoglobulin A nephropathy (IgAN), and long-term adverse prognosis of these patients is still controversial. This meta-analysis aims to clarify the effect of hematuria on renal outcomes in IgAN.

Methods: Observational cohort studies reporting associations between various forms of hematuria and renal outcomes among IgAN patients were identified from the PubMed and Embase databases. The pooled adjusted risk ratios (RRs) were computed with random effects models.

Results: Thirteen studies encompassing 5660 patients with IgAN were included. Patients with initial hematuria did not have a significantly increased risk of developing end-stage renal disease (ESRD) compared with those without hematuria (RR, 1.32; 95% CI, 0.87–2.00; p = .19). However, initial microscopic hematuria was associated with an 87% increase in the risk of ESRD (RR, 1.87; 95% CI, 1.40–2.50; p < .001), while macroscopic hematuria was associated with a 32% decrease in the risk of ESRD (RR, 0.68; 95% CI, 0.58–0.79; p < .001). Additionally, persistent hematuria might be an independent risk factor for ESRD or a 50% decline in eGFR.

Conclusions: Among IgAN patients, hematuria, including initial microscopic hematuria and even persistent hematuria, was possibly associated with renal progression and ESRD. However, independent of other classical predictors, initial macroscopic hematuria might be a protective factor for IgAN.

Ferrotoxicity and Its Amelioration by Calcitriol in Cultured Renal Cells

Globally, acute kidney injury (AKI) is associated with significant mortality and an enormous economic burden. Whereas iron is essential for metabolically active renal cells, it has the potential to cause renal cytotoxicity by promoting Fenton chemistry-based oxidative stress involving lipid peroxidation. In addition, 1,25-dihydroxyvitamin D3 (calcitriol), the active form of vitamin D, is reported to have an antioxidative role. In this study, we intended to demonstrate the impact of vitamin D on iron-mediated oxidant stress and cytotoxicity of Vero cells exposed to iohexol, a low osmolar iodine-containing contrast media in vitro. Cultured Vero cells were pretreated with 1,25-dihydroxyvitamin D3 dissolved in absolute ethanol (0.05%, 2.0 mM) at a dose of 1 mM for 6 hours. Subsequently, iohexol was added at a concentration of 100 mg iodine per mL and incubated for 3 hours. Total cellular iron content was analysed by a flame atomic absorption spectrophotometer at 372 nm. Lipid peroxidation was determined by TBARS (thiobarbituric acid reactive species) assay. Antioxidants including total thiol content were assessed by Ellman’s method, catalase by colorimetric method, and superoxide dismutase (SOD) by nitroblue tetrazolium assay. The cells were stained with DAPI (4 ${}^{\prime }$ ,6-diamidino-2-phenylindole), and the cytotoxicity was evaluated by viability assay (MTT assay). The results indicated that iohexol exposure caused a significant increase of the total iron content in Vero cells. A concomitant increase of lipid peroxidation and decrease of total thiol protein levels, catalase, and superoxide dismutase activity were observed along with decreased cell viability in comparison with the controls. Furthermore, these changes were significantly reversed when the cells were pretreated with vitamin D prior to incubation with iohexol. Our findings of this in vitro model of iohexol-induced renotoxicity lend further support to the nephrotoxic potential of iron and underpin the possible clinical utility of vitamin D for the treatment and prevention of AKI.

Cross-sectional and longitudinal associations between dipstick hematuria and chronic kidney disease in patients with type 2 diabetes

AIMS

To examine the association of dipstick hematuria with kidney function and albuminuria in patients with type 2 diabetes (T2D).

METHODS

A total of 7,945 patients with T2D were studied. In the cross-sectional study, patients were classified into 6 groups based on the stage of albuminuria and estimated glomerular filtration rate (eGFR) of 60 mL/min/1.73 m² at baseline. In the longitudinal study where patients were classified by the presence of hematuria, the primary composite endpoint was a 30% decrease in eGFR from baseline or the initiation of kidney replacement therapy. Other outcomes included eGFR slope and stage progression of albuminuria.

RESULTS

Cross-sectionally, hematuria was more prevalent in patients with more advanced stages of albuminuria and with lower eGFR, independently of each other. In the longitudinal study, patients with hematuria experienced 50% increased incidence of the primary endpoint (p < 0.001). The eGFR slope was steeper in patients with hematuria than in those without hematuria (p < 0.001). On the other hand, hematuria was unlikely to be associated with the progression of albuminuria.

CONCLUSIONS

In patients with T2D, dipstick hematuria was associated with prevalent albuminuria and reduced eGFR, as well as faster decline in kidney function but not higher risk of development or progression of albuminuria.

Ferrotoxicity and Its Amelioration by Calcitriol in Cultured Renal Cells

Globally, acute kidney injury (AKI) is associated with significant mortality and an enormous economic burden. Whereas iron is essential for metabolically active renal cells, it has the potential to cause renal cytotoxicity by promoting Fenton chemistry-based oxidative stress involving lipid peroxidation. In addition, 1,25-dihydroxyvitamin D3 (calcitriol), the active form of vitamin D, is reported to have an antioxidative role. In this study, we intended to demonstrate the impact of vitamin D on iron-mediated oxidant stress and cytotoxicity of Vero cells exposed to iohexol, a low osmolar iodine-containing contrast media in vitro. Cultured Vero cells were pretreated with 1,25-dihydroxyvitamin D3 dissolved in absolute ethanol (0.05%, 2.0 mM) at a dose of 1 mM for 6 hours. Subsequently, iohexol was added at a concentration of 100 mg iodine per mL and incubated for 3 hours. Total cellular iron content was analysed by a flame atomic absorption spectrophotometer at 372 nm. Lipid peroxidation was determined by TBARS (thiobarbituric acid reactive species) assay. Antioxidants including total thiol content were assessed by Ellman's method, catalase by colorimetric method, and superoxide dismutase (SOD) by nitroblue tetrazolium assay. The cells were stained with DAPI (4',6-diamidino-2-phenylindole), and the cytotoxicity was evaluated by viability assay (MTT assay). The results indicated that iohexol exposure caused a significant increase of the total iron content in Vero cells. A concomitant increase of lipid peroxidation and decrease of total thiol protein levels, catalase, and superoxide dismutase activity were observed along with decreased cell viability in comparison with the controls. Furthermore, these changes were significantly reversed when the cells were pretreated with vitamin D prior to incubation with iohexol. Our findings of this in vitro model of iohexol-induced renotoxicity lend further support to the nephrotoxic potential of iron and underpin the possible clinical utility of vitamin D for the treatment and prevention of AKI.

Association of Proteinuria and Hematuria with Acute Kidney Injury and Mortality in Hospitalized Patients with COVID-19

INTRODUCTION

Acute kidney injury (AKI) is strongly associated with poor outcomes in hospitalized patients with coronavirus disease 2019 (COVID-19), but data on the association of proteinuria and hematuria are limited to non-US populations. In addition, admission and in-hospital measures for kidney abnormalities have not been studied separately.

METHODS

This retrospective cohort study aimed to analyze these associations in 321 patients sequentially admitted between March 7, 2020 and April 1, 2020 at Stony Brook University Medical Center, New York. We investigated the association of proteinuria, hematuria, and AKI with outcomes of inflammation, intensive care unit (ICU) admission, invasive mechanical ventilation (IMV), and in-hospital death. We used ANOVA, t test, χ2 test, and Fisher's exact test for bivariate analyses and logistic regression for multivariable analysis.

RESULTS

Three hundred patients met the inclusion criteria for the study cohort. Multivariable analysis demonstrated that admission proteinuria was significantly associated with risk of in-hospital AKI (OR 4.71, 95% CI 1.28-17.38), while admission hematuria was associated with ICU admission (OR 4.56, 95% CI 1.12-18.64), IMV (OR 8.79, 95% CI 2.08-37.00), and death (OR 18.03, 95% CI 2.84-114.57). During hospitalization, de novo proteinuria was significantly associated with increased risk of death (OR 8.94, 95% CI 1.19-114.4, p = 0.04). In-hospital AKI increased (OR 27.14, 95% CI 4.44-240.17) while recovery from in-hospital AKI decreased the risk of death (OR 0.001, 95% CI 0.001-0.06).

CONCLUSION

Proteinuria and hematuria both at the time of admission and during hospitalization are associated with adverse clinical outcomes in hospitalized patients with COVID-19.

Clinical assessment and pathophysiology of Bothrops venom-related acute kidney injury: a scoping review

Bothrops are one of the most common medically important snakes found in Latin America. Its venom is predominantly hemotoxic and proteolytic, which means that local lesion (edema and redness) and hemorrhagic symptoms are recurrent in envenoming by this snake. Although hemorrhage is usually the major cause of death, snakebite-related acute kidney injury is another potentially fatal clinical complication that may lead to chronic kidney disease. The present review highlights the main studies on Bothrops venom-related acute kidney injury, including observational, cross-sectional, case-control and cohort human studies available up to December 2019. The following descriptors were used according to Medical Subject Headings (MeSH): on Medline/Pubmed and Google Scholar "acute kidney injury" or "kidney disease" and "Bothrops"; on Lilacs and SciELO "kidney disease" or "acute kidney injury" and "Bothrops". Newcastle-Ottawa quality assessment scale was used to appraise the quality of the cross-sectional and cohort studies included. The selection of more severe patients who looked for health care units and tertiary centers is a risk of bias. Due to the methodological heterogeneity of the studies, a critical analysis of the results was performed based on the hypothesis that the design of the included studies influences the incidence of acute kidney injury. Fifteen human studies (total participants 4624) were included according to stablished criteria. The coagulation abnormalities (hemorrhagic symptoms, abnormal fibrinogen and activated partial thromboplastin time) were associated with acute kidney injury in the most recent studies reported. The findings observed in this review provide up-to-date evidence about the acute kidney injury pathogenesis following Bothrops syndrome. Studies pointed out that coagulation abnormalities comprise the major pathway for acute kidney injury development. This review may improve patient management by primary healthcare providers, allowing earlier diagnosis and treatment of Bothrops venom-related acute kidney injury.

Hematuria Is Associated with More Severe Acute Tubulointerstitial Nephritis

Acute tubulointerstitial nephritis (ATIN) is a common cause of acute kidney injury. Although haematuria is a risk factor for the development of renal disease, no previous study has analyzed the significance of haematuria in ATIN. Retrospective, observational analysis of 110 patients with biopsy-proven ATIN was conducted. Results: Haematuria was present in 66 (60%) ATIN patients. A higher percentage of ATIN patients with haematuria had proteinuria than patients without haematuria (89.4% vs. 59.1%, p = 0.001) with significantly higher levels of proteinuria (median (interquartile range) protein:creatinine ratio 902.70 (513–1492) vs. 341.00 (177–734) mg/g, p <0.001). Moreover, those patients with more haematuria intensity had a higher urinary protein:creatinine ratio (1352.65 (665–2292) vs. 849.60 (562–1155) mg/g, p = 0.02). Those patients with higher proteinuria were more likely to need renal replacement therapy (22.7 vs. 0%, p = 0.03) and to suffer relapse (4 vs. 0%, p = 0.03). At the end of follow up, haematuric ATIN patients had higher serum creatinine levels (3.19 ± 2.91 vs. 1.91 ± 1.17 mg/dL, p = 0.007), and a trend towards a higher need for acute dialysis (7 vs. 1%, p = 0.09) and renal replacement therapy (12.1 vs. 2.3%, p = 0.12). Haematuria is common in ATIN and it is associated with worse renal function outcomes.

Ferroptosis and kidney disease

Cell death is a finely regulated process occurring through different pathways. Regulated cell death, either through apoptosis or regulated necrosis offers the possibility of therapeutic intervention. Necroptosis and ferroptosis are among the best studied forms of regulated necrosis in the context of kidney disease. We now review the current evidence supporting a role for ferroptosis in kidney disease and the implications of this knowledge for the design of novel therapeutic strategies. Ferroptosis is defined functionally, as a cell modality characterized by peroxidation of certain lipids, constitutively suppressed by GPX4 and inhibited by iron chelators and lipophilic antioxidants. There is functional evidence of the involvement of ferroptosis in diverse forms of kidneys disease. In a well characterized nephrotoxic acute kidney injury model, ferroptosis caused an initial wave of death, triggering an inflammatory response that in turn promoted necroptotic cell death that perpetuated kidney dysfunction. This suggests that ferroptosis inhibitors may be explored as prophylactic agents in clinical nephrotoxicity or ischemia-reperfusion injury such as during kidney transplantation. Transplantation offers the unique opportunity of using anti-ferroptosis agent ex vivo, thus avoiding bioavailability and in vivo pharmacokinetics and pharmacodynamics issues.

Acute Kidney Injury due to Anticoagulant-Related Nephropathy : A Suggestion for Therapy

The relationship between kidneys and anticoagulation is complex, especially after introduction of the direct oral anticoagulants (DOAC). It is recently growing evidence of an anticoagulant-related nephropathy (ARN), a form of acute kidney injury caused by excessive anticoagulation. The pathogenesis of kidney damage in this setting is multifactorial, and nowadays, there is no established treatment. We describe a case of ARN, admitted to our Nephrology Unit with a strong suspicion of ANCA-associated vasculitis due to gross haematuria and haemoptysis; the patient was being given dabigatran. Renal biopsy excluded ANCA-associated vasculitis and diagnosed a red blood cell cast nephropathy superimposed to an underlying IgA nephropathy. Several mechanisms are possibly responsible for kidney injury in ARN: tubular obstruction, cytotoxicity of heme-containing molecules and free iron, and activation of proinflammatory/profibrotic cytokines. Therefore, the patient was given a multilevel strategy of treatment. A combination of reversal of coagulopathy (i.e., withdrawal of dabigatran and infusion of its specific antidote) along with administration of fluids, sodium bicarbonate, steroids, and mannitol resulted in conservative management of AKI and fast recovery of renal function. This observation could suggest a prospective study aiming to find the best therapy of ARN.

IgA nephropathy in children and in adults: two separate entities or the same disease?

IgA nephropathy (IgAN) is observed in subjects of any age, however perspective and management of this disease are different between adult and pediatrician Nephrologists. Most children with IgAN present with gross hematuria rapidly vanishing or persistent mild microscopic hematuria, which rarely progresses to end stage renal disease (ESRD) over the pediatric observation. The perspective of IgAN in adults is of a slowly progressive glomerular disease with 30-40% probabilities to reach ESRD. However, mild cases of IgAN in children might be missed with manifestation of irreversible damage only decades after the true onset, as 50% of subjects with IgAN enter renal replacement treatment before the age of 50 years. In both adults and children the assessment of risk profile is crucial to avoid overtreatment in benign cases or institute a prompt and valid therapy in potentially progressive cases. In case of common risk factors, new therapeutic opportunities tested in adults might be applied to children with the expectation of similar results. If IgAN is the same disease in spite of different clinical profiles in children and adults, an early intervention may be the correct way to prevent progression decades later. On the contrary, if we are dealing with different clinical entities, the treatment in pediatric and in adult settings must be kept apart. This review addresses to report similarities and differences of IgAN across the life periods in order to reason on the application of newly offered treatments over the entire spectrum of this disease or in focused age indications.

Molecular pathways driving omeprazole nephrotoxicity

Omeprazole, a proton pump inhibitor used to treat peptic ulcer and gastroesophageal reflux disease, has been associated to chronic kidney disease and acute interstitial nephritis. However, whether omeprazole is toxic to renal cells is unknown. Omeprazole has a lethal effect over some cancer cells, and cell death is a key process in kidney disease. Thus, we evaluated the potential lethal effect of omeprazole over tubular cells. Omeprazole induced dose-dependent cell death in human and murine proximal tubular cell lines and in human primary proximal tubular cell cultures. Increased cell death was observed at the high concentrations used in cancer cell studies and also at lower concentrations similar to those in peptic ulcer patient serum. Cell death induced by omeprazole had features of necrosis such as annexin V/7-AAD staining, LDH release, vacuolization and irregular chromatin condensation. Weak activation of caspase-3 was observed but inhibitors of caspases (zVAD), necroptosis (Necrostatin-1) or ferroptosis (Ferrostatin-1) did not prevent omeprazole-induced death. However, omeprazole promoted a strong oxidative stress response affecting mitochondria and lysosomes and the antioxidant N-acetyl-cysteine reduced oxidative stress and cell death. By contrast, iron overload increased cell death. An adaptive increase in the antiapoptotic protein BclxL failed to protect cells. In mice, parenteral omeprazole increased tubular cell death and the expression of NGAL and HO-1, markers of renal injury and oxidative stress, respectively. In conclusion, omeprazole nephrotoxicity may be related to induction of oxidative stress and renal tubular cell death.

Hematuria in aging men with hemophilia: Association with factor prophylaxis

INTRODUCTION

Macroscopic hematuria is considered a significant risk factor for urologic disease, and it is highly prevalent in people with hemophilia.

AIM

To determine whether prophylactic factor replacement therapy is associated with reduced occurrence of macroscopic hematuria in people with hemophilia in a post hoc analysis using data from a cross-sectional study conducted by the Age-Related Developments and Comobordities in Hemophilia (ADVANCE) Working Group that included males with hemophilia ≥40 years of age.

METHODS

Data from 16 contributing centers, in 13 European countries and Israel, were analyzed using logistic regression. Of 532 recruited individuals, this analysis included 370 patients with moderate or severe hemophilia who received on-demand or prophylactic therapy.

RESULTS

For patients with a history of macroscopic hematuria, we analyzed the association between prophylaxis and reoccurrence of macroscopic hematuria within the past 5 years (n = 235 patients). Frequent (≥3 times/wk) prophylaxis was negatively associated with a recent episode of macroscopic hematuria (odds ratio [OR], 0.38; 95% confidence interval [CI], 0.18-0.76). We also analyzed whether prophylaxis corresponded to a lower lifetime number of macroscopic hematuria episodes (n = 285 patients). Frequent prophylaxis for >15 years was associated with a lower number of episodes compared to on-demand treatment (OR, 0.29; 95% CI, 0.16-0.54), whereas nonsteroidal anti-inflammatory drugs (NSAIDs) and severe hemophilia were associated with a higher number. There was no association of prophylaxis <3 times/wk with hematuria.

CONCLUSION

Frequent prophylaxis was negatively associated with the number of episodes of macroscopic hematuria in people with hemophilia. Prevalence of macroscopic hematuria was higher among individuals with severe hemophilia and those regularly using NSAIDs.

Local hepcidin increased intracellular iron overload via the degradation of ferroportin in the kidney

BACKGROUND

Hepcidin is a key regulator of iron homeostasis. Some studies showed that exogenous hepcidin decreased the expression of divalent metal transporter (DMT1) rather than ferroportin(FPN1) to regulate renal iron metabolism. This study explored the effects of hepcidin synthesized by the kidney and its mechanism of iron regulation.

METHODS

In the in vivo experiments, mice were divided into a unilateral ureter obstruction (UUO) model group and a sham operation group, and mice in the UUO model group were sacrificed on days 1, 3, 5 and 7. The expression of renal hepcidin, FPN1, DMT1 and the retention of renal iron were studied. In the in vitro experiments, we overexpressed hepcidin in HK-2 cells. Then we tested the expression of renal hepcidin, FPN1, DMT1 and observed the production of intracellular ferrous ions.

RESULTS

Renal hepcidin expression was consistently higher in the UUO group than in the sham group from the first day. The expression of FPN1 gradually decreased, and the expression of DMT1 gradually increased in the UUO model. Intracellular ferrous ions significantly increased on the first day of the UUO model. In hepcidin overexpressed HK-2 cells, the expression of FPN1 was decreased, while the expression of DMT1 has no significant change. In addition, production of intracellular ferrous ions increased.

CONCLUSION

local hepcidin can regulate iron metabolism in the kidney by adjusting the expression of FPN1.

Dabigatran-induced anticoagulant-related nephropathy with undiagnosed IgA nephropathy in a patient with normal baseline renal function

Occasionally, over-anticoagulation with warfarin induces acute kidney injury (AKI) characterized by glomerular hemorrhage with tubular obstruction by red blood cell casts, which is widely acknowledged as warfarin-related nephropathy. Owing to extensive use of direct oral anticoagulants, similar AKI cases have been reported among patients treated with dabigatran. Dabigatran is primarily excreted by the kidneys; thus, renal impairment is one of the risk factors for dabigatran-induced bleeding complications. Nevertheless, risk factors for dabigatran-induced anticoagulant-related nephropathy (ARN) remain partially clarified. Here, we report a histologically established case of dabigatran-induced ARN with undiagnosed IgA nephropathy in a patient with normal baseline renal function. In addition, we summarize previously published cases of biopsy-proven, dabigatran-related ARN. A 67-year-old female with normal preexisting renal function developed macrohematuria and AKI. She had been treated with dabigatran for deep vein thrombosis. A renal biopsy diagnosed ARN with inactive IgA nephropathy. After dabigatran withdrawal, her macrohematuria and renal function improved. This report demonstrates that ARN could occur in patients with normal baseline renal function. Our case and prior reports suggest that IgA nephropathy could be a risk factor for dabigatran-induced ARN.