Urinary KIM-1 Research Articles

The clinical efficacy of cGMP-specific sildenafil on mitochondrial biogenesis induction and renal damage in cats with acute on chronic kidney disease

BackgroundMitochondrial biogenesis (MB) induction has recently emerged as potential therapeutic approaches in kidney pathology and the mitochondria-targeted therapies should be investigated to improve treatment of animals with kidney diseases. This study aimed to investigate the effects of MB induction with sildenafil citrate on the cGMP/NO pathway, glomerular filtration, and reduction of kidney damage and fibrosis (TGF-β/SMAD pathway) in cats with acute on chronic kidney disease (ACKD). Thirty-three cats were divided into the non-azotemic (healthy) group (n:8) and the ACKD group (n:25), comprising different breeds, sexes, and ages. Sildenafil citrate was administered to the non-azotemic and ACKD groups (2.5 mg/kg, PO, q12 hours) for 30 days. Serum and urine NO, MDA, NGAL, KIM-1, TGF-β1, IL-18, FGF 23, PGC-1α and cGMP concentrations were measured.ResultsSerum cGMP concentrations increased (P < 0.05) in the non-azotemic group during the 2nd (median 475.99 pmol/mL) and 3rd (median 405.01 pmol/mL) weeks of the study, whereas serum cGMP concentrations decreased in the ACKD group during the 4th(median 188.52 pmol/mL) week compared to the non-azotemic group (P < 0.05). No difference was observed in serum biomarker concentrations except NO, which increased in the 4th week (P < 0.05). The urinary concentrations of NO, MDA, PGC-1α, TGF-β1, NGAL, KIM-1, IL-18, and FGF 23 in the ACKD group were found to be higher compared to those in the non-azotemic group from the 1st to the 4th week (P < 0.05). In the ACKD group, the urine PGC-1α concentration in the 2nd (median 6.10 ng/mL) week was lower compared to that in the 0 and 1st (median 7.65 and 7.21 ng/mL, respectively) week, and the NO concentration in the 3rd (median 28.94 µmol/mL) week was lower than that in the 0th (median 37.43 µmol/mL) week (P < 0.05).ConclusionsWhile sildenafil citrate has been determined to induce a low level of MB and to have a beneficial effect on glomerular filtration, it is observed to be ineffective in mitigating renal damage and fibrosis via the TGF-β/SMAD pathway in cats with ACKD.

Lung-Kidney Axis in Cystic Fibrosis: Early Urinary Markers of Kidney Injury Correlate with Neutrophil Activation and Worse Lung Function.

Adult people with cystic fibrosis (PwCF) have a higher risk of end-stage kidney disease than the general population. The nature and mechanism of kidney disease in CF are unknown. This study quantifies urinary kidney injury markers and examines the hypothesis that neutrophil activation and lung infection are associated with early kidney injury in CF. Urinary total protein, albumin, and markers of kidney injury and neutrophil activation, normalized to creatinine, as well as urinary immune cells, were quantified in CF (n = 48) and healthy (n = 33) cohorts. Infection burden and chronicity were defined by sputum culture and serum titers of anti-bacterial antibodies. PwCF had increased urinary protein levels, consisting of low-molecular-weight tubular injury markers, independent of glomerular filtration rate (eGFR). This finding suggests subclinical renal injury processes. Urinary analysis of the CF cohort identified different associations of urinary injury markers with aminoglycoside exposure, lung function, and neutrophil activation. High urinary KIM-1 levels and increased prevalence of neutrophils among urine immune cells correlated with decreased lung function in PwCF. The relationship between tubular injury and decreased lung function was most prominent in patients harboring chronic Pseudomonas aeruginosa infection. Increased urinary tubular injury markers in PwCF suggest early subclinical renal injury not readily detected by eGFR. The strong association of high urinary KIM-1 and neutrophils with diminished lung function and high Pseudomonas aeruginosa burden suggests that pulmonary disease may contribute to renal injury in CF.

Renal protective and immunoregulatory effects of Lactobacillus casei strain Shirota in nephropathy-prone mice.

The incidence of severe acute kidney injury (AKI) is considerably high worldwide. A previous study showed that gut microbial dysbiosis was a hallmark of AKI in mice. Whether the probiotic Lactobacillus casei strain Shirota (LcS) plays a role in kidney disease, particularly AKI, remains unclear. To investigate the effects of LcS on kidney injury, tubule-specific conditional von Hippel-Lindau gene-knockout C57BL/6 mice (Vhlhdel/del mice) were supplemented without (Ctrl) or with probiotics (LcS) in Experiment 1, and their lifespan was monitored. Additionally, the Vhlhdel/+ mice were supplemented without (Ctrl and AA) or with probiotics (LcS and LcS + AA) in Experiment 2. Probiotic LcS (1 × 109 colony-forming units) was supplemented once daily. After 4 weeks of LcS supplementation, AA and LcS + AA mice were administered aristolochic acid (AA; 4 mg/kg body weight/day)-containing purified diet for 2 weeks to induce AA nephropathy before sacrifice. Supplementation of LcS significantly prolonged the lifespan of Vhlhdel/del mice, suggesting a potential renal protective effect. AA induced-nephropathy increased not only the indicators of renal dysfunction and injury, including urinary protein and kidney injury molecule (KIM)-1, serum blood urea nitrogen (BUN) and creatinine, but also serum interleukin (IL)-6 levels, renal macrophage infiltrations, and pathological lesions in Vhlhdel/+ mice. LcS supplementation significantly reduced urinary protein and KIM-1 levels, serum BUN and IL-6 levels, and renal M1 macrophages, tissue lesions, and injury scores. We also found that LcS maintained gut integrity under AA induction and increased intestinal lamina propria dendritic cells. Furthermore, LcS significantly reduced pro-inflammatory IL-17A and upregulated anti-inflammatory IL-10 production by immune cells from intestinal Peyer's patches (PP) or mesenteric lymph nodes (MLN), and significantly increased IL-10 and reduced IL-6 production by splenocytes. Prior supplementation with probiotic LcS significantly alleviated the severity of renal injury. This renal protective effect was partially associated with the enhancements of intestinal and systemic anti-inflammatory immune responses, suggesting that LcS-induced immunoregulation might contribute to its renal protective effects.

Potential effects of Resatorvid and alpha lipoic acid on gentamicin-induced nephrotoxicity in rats.

Gentamicin is an aminoglycoside antibiotic with a rapid bactericidal effect on the treatment of many infections. However, its use at high concentrations for more than 7 days causes nephrotoxic side effects. This study investigated the potential of Resatorvid and alpha lipoic acid (ALA) in mitigating gentamicin-induced nephrotoxicity in rats, considering biochemical, histopathological, and molecular parameters. This study randomly distributed 34 Wistar albino rats into four groups: healthy control (n = 6), Gentamicin (80 mg/kg, n = 7), Gentamicin + Sham (%10 hydroalcoholic solution, n = 7), Gentamicin + Resatorvid (5 mg/kg, n = 7), and Gentamicin + ALA (100 mg/kg, n = 7). Resatorvid treatment led to a statistically significant decrease in urinary IL-18, KIM-1, and NGAL levels, whereas ALA treatment significantly reduced KIM-1 levels compared to the gentamicin-only group. Both Resatorvid and ALA showed partial reductions in urine creatinine levels. Moreover, treatments with Resatorvid and ALA resulted in statistically significant decreases in NRF-2, CAS-3, and NR4A2 expressions. However, only Resatorvid demonstrated a statistically significant decrease in NF-B expression. These findings highlight the potential of Resatorvid in ameliorating gentamicin-induced nephrotoxicity, thereby expanding the therapeutic utility of gentamicin and enhancing its efficacy against infections.

Diagnostic efficacy of urinary neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 for early detection of acute kidney injury in dogs with leptospirosis or babesiosis.

This study evaluates the diagnostic efficacy of urinary biomarkers, Neutrophil Gelatinase-Associated Lipocalin (uNGAL), and Kidney Injury Molecule-1 (uKIM-1), in identifying Acute Kidney Injury (AKI) in dogs affected with leptospirosis or babesiosis. Acute kidney injury was diagnosed based on the increase in serum creatinine levels above 0.3mg/dL within 48h and dogs were categorized according to AKI grades based on International Renal Interest Society guidelines. Traditional biomarkers (serum creatinine and blood urea nitrogen) and novel biomarkers like urinary NGAL and urinary KIM-1 levels were measured and compared to concentrations obtained in control dogs. Statistical analysis assessed significant differences (P < 0.01) across AKI grades, specifically noting elevated urinary NGAL and KIM-1 in IRIS grade I AKI (P < 0.001). The study highlights the diagnostic significance of urinary NGAL and KIM-1 as early indicators of renal damage, particularly valuable in non-azotemic AKI cases, offering promising markers for early AKI diagnosis in veterinary clinical settings. These biomarkers demonstrate clinical utility and underscore their potential for improving AKI management in veterinary medicine. Further validation studies involving larger cohorts and diverse etiologies of AKI are needed to confirm the diagnostic accuracy and clinical utility of urinary NGAL and KIM-1 in veterinary practice.

#2308 The effect of Dapagliflozin on albuminuria and biomarkers associated with renal function in patients with β-thalassemia and/or sickle-cell disease

Abstract Background and Aims Patients with β-thalassemia present already from the 1st year of life with serious anemia thus needing regular blood transfusions in order to attain normal hemoglobin levels. Chronic anemia, iron overload and the use of iron chelating agents have been associated with renal dysfunction. In sickle-cell syndromes, which include sickle-cell anemia and sickle-cell trait, patients present with typical kidney functional and structural defects, resulting in urinary concentrating defects, distal nephron dysfunction and albuminuria. Sodium–glucose cotransporter-2 inhibitors (SGLT-2i) have shown beneficial effects on renal outcomes in large clinical trials with the added benefit of a substantial decrease in albuminuria. The aim of this prospective, non randomized open label study is to investigate the effect of Dapagliflozin at a dose of 10 mg daily on albuminuria and the overall progression of CKD in patients with β-thalassemia and/or sickle-cell disease undergoing regular blood transfusions. Method In this study we included adult patients undergoing regular blood transfusions with a baseline albuminuria of ACR&amp;gt;30 mg/gCr (assessed with a spot urine sample) who received treatment with Dapagliflozin, a second group with no albuminuria that did not receive treatment and a group of adults with no kidney disease (Controls). In all patients renal function biomarkers were measured in urine and serum with commercial ELISA kits (NGAL and uPAR in serum, MMP9 and KIM-1 in urine), while in patients that received Dapagliflozin additional measurements of ACR and eGFR (CKD-EPI formula) were performed after 3 months of treatment initiation. Results In this study we included 16 patients (7 males) with β-thalassemia and/or sickle-cell disease with ACR&amp;gt;30 mg/gCr, 35 patients (17 males) with β-thalassemia and/or sickle-cell disease without albuminuria and 20 controls (13 males). Patients that received Dapagliflozin showed a significant reduction in albuminuria three months post-initiation of treatment (ACR: 0.52 ± 1.2 vs. 0.3 ± 0.68 mg/g, p=0.006) while kidney function showed a slight non-significant reduction (eGFR: 99.3 ± 21.7 vs. 94.7 ± 28.9 ml/min/1.73m2, p=0.36). Concerning the urine and serum biomarkers of tubular dysfunction, inflammation and kidney disease progression, all were significantly increased in patients with β-thalassemia and/or sickle-cell disease in comparison to controls (Table 1). In patients that received treatment with Dapagliflozin, NGAL, MMP-9 and suPAR at 3 months post-treatment initiation did not show any significant reduction (Table 2). Conclusion Patients with β-thalassemia and/or sickle-cell disease show increased urine and serum levels of kidney damage biomarkers in comparison to healthy controls. Treatment of these patients with Dapagliflozin for 3 months has a significant effect in albuminuria reduction while it does not alter urine and serum levels of these biomarkers.

#1548 The involvement of soluble fms-like tyrosine kinase-1 in the transition from acute kidney injury to chronic kidney disease

Abstract Background and Aims Fms-like tyrosine kinase-1 (Flt-1) is a receptor for vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) and, playing a crucial role in angiogenesis and inflammation pathways. Soluble Flt-1 (sFlt-1) acts as a decoy for both VEGF and PlGF, regulating Flt-1-mediated angiogenesis and inflammation. We investigated the involvement of sFlt-1 in the transition from acute kidney injury to chronic kidney disease (CKD). Method Wild-type (WT) and sFlt-1 knock-out (KO) mice underwent ischemia-reperfusion injury (IRI) treatment. A unilateral 23-minute IRI and contralateral nephrectomy were performed to examine kidney function (AKI to CKD) for 2 weeks. To explore the downstream signaling pathway for sFlt-1 in the kidney, a unilateral 28-minute IRI was performed, and angiogenesis and cytokine expression arrays (Proteome Profiler Array Kits) were used to compare the relative expressions between 28-minute IRI and the contralateral untreated kidney cortices in both WT and sFlt-1 KO mice. Results A plasma sFlt-1 concentration was elevated just after IRI and reached its peak after 12 hours. Blood urea nitrogen (BUN) and plasma creatinine (pCre) levels peaked at 24 hours after IRI. The peak levels of BUN and pCre were significantly lower in sFlt-1 KO compared to those in WT mice (BUN 43.23 ± 5.9 mg/dL and 82.7 ± 13.0 mg/dL, p = 0.008, pCre 0.18 ± 0.03 mg/dL and 0.31 ± 0.04 mg/dL, p = 0.008 in KO and WT mice, respectively). Urinary KIM-1 (uKIM-1) levels 12 hours after IRI in WT mice were higher than those in sFlt-1 KO mice (WT vs sFlt-1 KO; uKIM-1 4.82 ± 0.83 pg/day vs 2.39 ± 0.98 pg/day, p = 0.09). Histopathological evaluation of the kidneys showed reduced monocyte infiltration in sFlt-1 KO mice compared to WT mice 14 days after IRI. In cytokine expression assay of kidney cortices 3 days after IRI, IRI-induced increased expressions of tissue repairs and immune response proteins such as TIMP-1, C5/C5a, and TREM-1 were alleviated in sFlt-1 KO mice compared to those in WT mice. In the Angiogenesis expression array of kidney cortices 1 day after IRI, there were no significant differences in the levels of IRI-induced increased expression of anti-/pro-angiogenesis factors, including TIMP-1, Cyr61, SerpinE1, angiogenin, platelet factor 4, collagen factor 3, MMP-9, and SDF-1, between WT and sFlt-1 KO mice. Conclusion The acute and chronic kidney damages after IRI was reduced in sFlt-1 KO mice compared to WT mice. The protective effect on the kidneys by eliminating sFlt-1 would be associated with immune response signaling such as TIMP-1, C5/C5a, and TREM-1 but not with anti-/pro-angiogenesis factors.

The use of urinary kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin for diagnosis of hepato-renal syndrome in advanced cirrhotic patients

Background Chronic liver disease is a common and important clinical problem.Hepatorenal syndrome (HRS) is a life threatening complication. Serum creatinine (Cr) remains the only conventional indicator of renal function. However, the interpretation of serum Cr level can be confounded by malnutrition and reduced muscle mass often observed in patients with severe liver disease. Here, we present a cross-sectional study to explore the sensitivity and specificity of other markers as urinary KIM-1 and NGAL for cases of HRS. Methods Cross-sectional study was conducted on 88 patients who were admitted to Alexandria main university hospital. Enrolled patients were divided in two groups; group 1: patients with advanced liver cirrhosis (child B and C) who have normal kidney functions while group 2: patients who developed HRS. Stata© version 14.2 software package was used for analysis. Results Group 1 included 18 males and 26 females compared to 25 males and 19 females in group 2 (p = 0.135). Only the urinary KIM-1 showed a statistically significant difference between both groups in the multivariate logistic regression analysis adjusted for gender, serum bilirubin, serum albumin, INR, serum K, AST and ALT levels. Conclusion In conclusion, our study aligns with prior research, as seen in the consistent findings regarding Urinary NGAL elevation in cirrhotic patients with AKI. Urinary KIM-1, independent of Urinary NGAL, may have a role in precisely distinguishing between advanced liver cirrhosis and HRS and merits further exploration.

Mildronate ameliorates kidney injury and reduces inflammation in Sickle Cell Disease mice

INTRODUCTION: Sickle cell disease (SCD) is a hereditary hemoglobin disorder characterized by hemolytic anemia, vaso-occlusive crisis and chronic inflammation that affects multiple organs including kidney, liver, brain, spleen, and heart. Renal disease, the most common complication in SCD, is a progressive disease that begins in childhood as glomerular hyperfiltration, then advances to albuminuria, following by a fast decline in glomerular filtration. It may further progress to a renal failure in adults. More than 50% of SCD patients develop chronic kidney disease (CKD), and 14-18% progress to the end-stage kidney disease. Renal injury in SCD results from a cascade of events starting with chronic red blood cells sickling and hemolysis leading to increased blood viscosity, microvascular obstruction and dilation, hypoxia in the medulla, oxidative stress, and inflammation. Mildronate (meldonium) is an anti-ischemic and anti-inflammatory medication approved in Eastern Europe. HYPOTHESIS: We hypothesized that mildronate administration reduces renal medullary hypoxia and decreases oxidative stress and inflammation ameliorating renal injury in SCD mice. METHODS: The study was approved by the Howard University IACUC. Townes SCD mice, expressing human HbS, and control mice, expressing human HbA, were injected with mildronate (400 mg/kg in saline) intraperitoneally or saline as vehicle control over the course of ten days. Blood was collected and used for hematological parameters analysis. Cytokines were measured by Bio-Plex suspension array in plasma. Hypoxyprobe Biotin kit (Hypoxyprobe Inc) was used for visualization of organ hypoxia. The effect of Mildronate on systemic and renal oxidative stress was measured by malondialdehyde (MDA) using ELISA (Abcam). Urinary KIM-1 was measured by TIM-1/KIM-1 ELISA kit (R&amp;D Systems). RESULTS: Mildornate injections did not affect hematological parameters of SCD mice including hematocrit, MCV, MCH, CMCH, erythrocytes and hemoglobin. Mildronate administration resulted in a significant reduction of the circulating pro-inflammatory cytokines IFN-γ, IL-1β and TNF-α and a trend toward reduction of IL-6, and IL-17 in SCD mice. We found higher level of hypoxia in the medulla of SCD mice compared to control mice. Mildronate injections did not reduced hypoxia in renal medulla of SCD mice. Also, mildronate injections did not change MDA levels in plasma or kidney of SCD mice. We found a significant reduction of proteinuria in SCD mice injected with mildronate compared to SCD mice injected with vehicle. Analysis of H&amp;E-stained kidneys showed significant reduction of glomerular size and medullar congestion areas in the mildronate injected SCD mice. Urinary KIM-1 levels were reduced by mildronate administration. CONCLUSIONS: Our results demonstrate that mildronate ameliorates glomerular and tubular injury in SCD mice and reduces capillary congestion. Mildronate improves renal function, in part by reducing inflammation but not through the reduction of hypoxia or oxidative stress. In future, we plan to assess the mildronate’s impact on kidney function and vessel inflammation. This work was supported by NIH grants R01HL125005, U54MD007597, and SC1HL150685. We thank Xiaomei Niu for helping with the Bio-Plex assay. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

CD8+ T cells mediate kidney fibrosis in diet-induced obese mice

Diet-induced obesity (DIO) is an epidemic in the United States and globally. Obesity is well known to exacerbate and/or promote kidney disease. Inflammation is a major factor in DIO and kidney disease. Utilizing a 20-week DIO mouse model (45% fat) and a normal diet (ND; 10% fat), our lab previously showed greater kidney medullary interstitial fibrosis as well as increased kidney medullary CD3+ T cells in DIO mice when compared to ND mice. Specifically, we found increased kidney CD8+ T cells, but similar CD4+ T cells, in DIO mice compared to ND mice. We hypothesized that CD8+ T cells in DIO mice are a primary factor in promoting kidney interstitial fibrosis. DIO mice were treated with anti-CD8 antibody or control anti-IgG antibody and ND mice were treated with control anti-IgG antibody for the final two weeks of the DIO protocol (n=7-9). DIO/anti-IgG and DIO/anti-CD8 mice had significantly higher body weight than ND/anti-IgG mice as expected (one-way ANOVA; p&lt;0.0001). Administration of anti-CD8 treatment in DIO mice had null effects on body weight (one-way ANOVA, p=0.509) and kidney weight (one-way ANOVA; p=0.067). Utilizing flow cytometry, we verified that anti-CD8 treatment significantly reduced CD8+ T cells compared to anti-IgG in the kidney (one-way ANOVA; p=0.0077; DIO/anti-IgG vs DIO/anti-CD8, p=0.0066) and in the blood (one-way ANOVA; p=0.0034; DIO/anti-IgG vs DIO/anti-CD8, p=0.0048). Using Picrosirius Red histological staining to assess kidney fibrosis, we found that anti-CD8 treatment significantly blunted kidney medullary fibrosis (one-way ANOVA, p=0.0177, ND/anti-IgG vs DIO/anti-IgG, p=0.0329; DIO/anti-IgG vs DIO/anti-CD8, p=0.0318), whereas glomerular fibrosis was not affected by anti-CD8 treatment in DIO mice (one-way ANOVA, p=0.31). Urine was collected in 12-hour increments and analyzed for markers of kidney damage. All groups of mice showed similar urinary KIM-1 excretion (one-way ANOVA; p=0.62) and protein excretion (one-way ANOVA; p=0.69). DIO mice with anti-CD8 or anti-IgG treatment had significantly increased urinary NGAL excretion compared to ND mice (one-way ANOVA; p=0.0203). In summary, anti-CD8 treatment reduced circulating and kidney CD8+ T cells, as well as kidney medullary interstitial fibrosis but not urinary NGAL excretion. These results indicate that CD8+ T cells mediate kidney medullary interstitial fibrosis in a 20 week DIO mouse model. Funding: R01 DK134562, R25 DK115353, F31HL167626. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The Human Phospholipase B-II Precursor (HPLBII-P) in Urine as a Novel Biomarker of Increased Glomerular Production or Permeability in Diabetes Mellitus?

Background: A previous report showed that the urine output of HPLBII-P in patients with diabetes mellitus and SARS-CoV-2 infection was increased as a sign of glomerular dysfunction. The aim of this report was to investigate the relation of the urine output of HPLBII-P to diabetes mellitus in two large community-based elderly populations, i.e., the ULSAM and PIVUS cohorts. Methods: HPLBII-P was measured by an ELISA in the urine of a community-based cohort of 839 men (ULSAM) collected at 77 years of age and in the urine of a community-based cohort of 75-year-old men, n = 387, and women, n = 401 (PIVUS). KIM-1, NGAL, and albumin were measured in urine and cathepsin S and cystatin C in serum. Results: HPLBII-P was significantly raised among males with diabetes in the ULSAM (p < 0.0001) and PIVUS cohorts (p ≤ 0.02), but not in the female cohort of PIVUS. In the female subpopulation of insulin-treated diabetes, HPLBII-P was raised (p = 0.02) as compared to women treated with oral antidiabetics only. In the ULSAM cohort, HPLBII-P was correlated to NGAL, KIM-1, and albumin in urine both in non-DM (all three biomarkers; p < 0.0001) and in DM (NGAL; p = 0.002, KIM-1; p = 0.02 and albumin; p = 0.01). Plasma glucose and HbA1c in blood showed correlations to U-HPLBII-P (r = 0.58, p < 0.001 and r = 0.42, p = 0.004, respectively). U-HPLBII-P and cathepsin S were correlated in the ULSAM group (r = 0.50, p < 0.001). No correlations were observed between U-HPLBII-P and serum creatinine or cystatin C. Conclusions: The urine measurement of HPLBII-P has the potential to become a novel and useful biomarker in the monitoring of glomerular activity in diabetes mellitus.

Urinary Epidermal Growth Factor Level as a Noninvasive Indicator of Tubular Repair in Patients with Acute Kidney Injury.

Epidermal growth factor (EGF), an essential factor for the proliferation and survival of renal tubular cells, is expressed by distal tubules and normally excreted via urine. Previous studies in rats demonstrated that acute tubular injury reduces urinary EGF levels. However, it is unclear whether urinary EGF is a suitable monitoring marker of tubular repair status after acute kidney injury (AKI) in humans. To address this question, we measured serum and urinary EGF in patients with AKI (n = 99) using ELISA and investigated whether urinary EGF levels were associated with the severity of tubular injury and renal prognosis. Urinary EGF was abundant in healthy controls but showed a significant decrease in AKI patients (14,522 ± 2190 pg/mL vs. 3201 ± 459.7 pg/mL, p < 0.05). The urinary EGF level in patients with renal AKI was notably lower than that in patients with pre-renal AKI. Furthermore, the urinary EGF level in patients with AKI stage 3 was significantly lower than that in patients with AKI stage 1. Urinary EGF levels were negatively correlated with urinary β-2MG and serum creatinine levels but positively correlated with hemoglobin levels and eGFR. Urinary EGF was not significantly correlated with urinary NAG, α-1MG, L-FABP, NGAL, KIM-1, or urinary protein concentrations. No significant correlation was observed between serum and urinary EGF levels, suggesting that urinary EGF is derived from the renal tubules rather than the blood. In living renal transplantation donors, the urinary EGF/Cr ratio was approximately half the preoperative urinary EGF/Cr ratio after unilateral nephrectomy. Collectively, these data suggest that urinary EGF is a suitable noninvasive indicator of not only the volume of functional normal renal tubules but also the status of tubular repair after AKI.

Pharmacokinetics and Nephrotoxicity of Polymyxin MRX-8 in Rats: A Novel Agent against Resistant Gram-Negative Bacteria.

MRX-8 is a novel polymyxin for carbapenem-resistant Gram-negative infections that has been recently evaluated in Phase I clinical trials. Herein, its pharmacokinetics (PK) and nephrotoxicity in rats are reported for the first time. This study aimed at pre-clinical PK and safety assessments. An LC-MS/MS method was developed to determine concentrations of MRX-8 and its major deacylation metabolite, MRX-8039, in rat plasma. Animals were administered a single dose of MRX-8 (2, 4, 6, and 8 mg/kg) or comparator polymyxin B (PMB) (4 and 8 mg/kg) to compare the kidney injury known for the polymyxin drug class. Nephrotoxicity was evaluated using serum creatinine, blood urea nitrogen (BUN) biomarkers, and renal histopathology. In rats, MRX-8 displayed linear PK within the range of 2-8 mg/kg, with approximately 4% of MRX-8 converted to MRX-8039. MRX-8 induced only mild increases in serum creatinine and BUN levels, with an apparent decrease in nephrotoxicity within 24 h, in contrast to PMB, which exhibited a significant and more persistent toxicity. Additional nephrotoxicity biomarkers (plasma NGAL and urinary NGAL, KIM-1, and TIMP-1) have confirmed attenuated MRX-8 kidney injury. Histopathology has revealed significantly greater cellular/tissue toxicity for PMB as compared to MRX-8 (variances of p = 0.008 and p = 0.048 vs. saline control, respectively). Thus, MRX-8 induces a mild and reversible kidney injury in rats compared to PMB. These data support a continued evaluation of the novel polymyxin in human trials.

Environmental exposure to melamine and its derivatives and kidney outcomes in children

Melamine caused acute nephrotoxicity in a past food adulteration incident, but it is unclear whether and how widespread ambient exposure to melamine and related compounds might affect pediatric kidney health. We assessed cross-sectional associations between childhood exposure to melamine and its derivatives and biomarkers of kidney injury and health and explored potential heterogeneity by sex suggested by sex-dependent differences in renal physiology. We measured melamine and its derivatives ammeline, ammelide, and cyanuric acid (CYA) in spot urine samples collected from 192 children from an urban site (Seattle, WA) and 187 children from a rural site (Yakima, WA) aged 4–8 years in the Global Alliance to Prevent Prematurity and Stillbirth (GAPPS) Study. In addition, biomarkers of kidney injury were measured in the same urine samples, including albumin, total protein, KIM-1, NAG, NGAL, and EGF. We utilized linear regressions to examine associations between individual chemical exposures and kidney biomarkers. Interaction terms examined association modification by sex, as well as potential interactions between melamine and CYA. Despite comparable exposures, girls had higher levels of many kidney injury biomarkers compared to boys. A ten-fold higher melamine concentration was associated with a 18% (95% CI: 5.6%, 31%) higher EGF in the full sample, while ten-fold higher melamine was associated with a 76% (14.1%, 173%) higher KIM-1 in boys but not in girls (−10.1% (−40.6%, 36.1%), interaction p = 0.026). Melamine exhibited significant negative interactions with CYA in association with total protein and NAG that appeared to be specific to girls. Our results suggest possible associations between melamine exposure and markers of kidney injury that may be more pronounced in boys. These findings provide novel insights into melamine and related derivative compound health effects at low levels of exposure in children and emphasize the role of sex in mediating the relationship between nephrotoxicant exposure and kidney injury.

Potential Utility of Urinary Follistatin as a Non-Invasive Indicator of Acute Tubular Damage in Patients with Acute Kidney Injury.

Activin A is known to impede tubular repair following renal ischemia, whereas exogenous follistatin, an activin A antagonist, has been shown to ameliorate kidney damage in rats. Despite these findings, the precise role of endogenous follistatin in the kidney has yet to be elucidated. In this study, we investigated the localization of follistatin in the normal human kidney and its potential utility as a marker for acute kidney injury (AKI). In a total of 118 AKI patients and 16 healthy adults, follistatin levels in serum and urine were quantified using ELISA, and correlations with clinical parameters were analyzed. Follistatin-producing cells were positive for Na-Cl co-transporter and uromodulin, but negative for aquaporin 1 and aquaporin 2. Unlike healthy adults, urinary follistatin significantly increased in AKI patients, correlating positively with AKI severity. Urinary follistatin levels were notably higher in patients needing renal replacement therapy. Significant correlations were observed with urinary protein, α1 microglobulin, and urinary NGAL, but not with urinary KIM-1, urinary L-FABP, urinary NAG, urinary β2 microglobulin, or serum creatinine. Interestingly, no correlation between urinary and serum follistatin levels was identified, indicating a renal origin for urinary follistatin. In conclusion, follistatin, produced by distal tubules, is detectable in the urine of AKI patients, suggesting its potential as a valuable marker for monitoring acute tubular damage severity in AKI.

Serum high mobility group box 1 as a potential biomarker for the progression of kidney disease in patients with type 2 diabetes.

As a damage-associated molecular pattern protein, high mobility group box 1 (HMGB1) is associated with kidney and systemic inflammation. The predictive and therapeutic value of HMGB1 as a biomarker has been confirmed in various diseases. However, its value in diabetic kidney disease (DKD) remains unclear. Therefore, this study aimed to investigate the correlation between serum and urine HMGB1 levels and DKD progression. We recruited 196 patients with type 2 diabetes mellitus (T2DM), including 109 with DKD and 87 T2DM patients without DKD. Additionally, 60 healthy participants without T2DM were also recruited as controls. Serum and urine samples were collected for HMGB1 analysis. Simultaneously, tumor necrosis factor receptor superfamily member 1A (TNFR-1) in serum and kidney injury molecule (KIM-1) in urine samples were evaluated for comparison. Serum and urine HMGB1 levels were significantly higher in patients with DKD than in patients with T2DM and healthy controls. Additionally, serum HMGB1 levels significantly and positively correlated with serum TNFR-1 (R 2=0.567, p<0.001) and urine KIM-1 levels (R 2=0.440, p<0.001), and urine HMGB1 has a similar correlation. In the population with T2DM, the risk of DKD progression increased with an increase in serum HMGB1 levels. Multivariate logistic regression analysis showed that elevated serum HMGB1 level was an independent risk factor for renal function progression in patients with DKD, and regression analysis did not change in the model corrected for multiple variables. The restricted cubic spline depicted a nonlinear relationship between serum HMGB1 and renal function progression in patients with DKD (p-nonlinear=0.007, p<0.001), and this positive effect remained consistent across subgroups. Serum HMGB1 was significantly correlated with DKD and disease severity. When the HMGB1 level was ≥27 ng/ml, the risk of renal progression increased sharply, indicating that serum HMGB1 can be used as a potential biomarker for the diagnosis of DKD progression.

Development and application of an amplified luminescent proximity homogeneous assay-linked immunosorbent assay for the accurate quantification of kidney injury molecule-1.

Background: Kidney injury molecule-1 (Kim-1), a specific marker of kidney injury, is usually not expressed in normal kidneys or at very low levels but is highly expressed in injured renal tubular epithelial cells until the damaged cells recover completely. Therefore, we aimed to develop an efficient and highly sensitive assay to accurately quantify Kim-1 levels in human serum and urine. Methods: In this study, a novel immunoassay was developed and named amplified luminescent proximity homogeneous assay-linked immunosorbent assay (AlphaLISA). Anti-Kim-1 antibodies can be directly coupled to carboxyl-modified donor and acceptor beads for the rapid detection of Kim-1 by double-antibody sandwich method. Serum and urine samples for Kim-1 measurements were obtained from 129 patients with nephropathy and 17 healthy individuals. Results: The linear range of Kim-1 detected by AlphaLISA was 3.83-5000 pg/mL, the coefficients of variation of intra-assay and inter-assay batches were 3.36%-4.71% and 5.61%-11.84%, respectively, and the recovery rate was 92.31%-99.58%. No cross reactions with neutrophil gelatinase-associated lipocalin, liver-type fatty acid binding protein, and matrix metalloproteinase-3 were observed. A good correlation (R 2 = 0.9086) was found between the findings of Kim-1-TRFIA and Kim-AlphaLISA for the same set of samples. In clinical trials, both serum and urine Kim-1 levels were significantly higher in patients with nephropathy than in healthy individuals, especially in patients with acute kidney injury. Furthermore, serum Kim-1 was superior to urinary Kim-1 in distinguishing between patients with nephropathy and healthy individuals. Conclusion: The developed Kim-1-AlphaLISA is highly efficient, precise, and sensitive, and it is suitable for the rapid detection of patients with acute kidney injury.

The Value of Urinary NGAL, KIM-1, and IL-18 Measurements in the Early Detection of Kidney Injury in Oncologic Patients Treated with Cisplatin-Based Chemotherapy.

Cisplatin is still a widely used anticancer drug characterized by significant nephrotoxicity. Acute kidney injury (AKI), diagnosed based on the Kidney Disease: Improving Global Outcomes (KDIGO) criteria, has limitations, including a delayed increase in creatinine. We determined the usefulness of neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and interleukin-18 (IL-18) in diagnosing AKI according to the KDIGO criteria in patients treated with cisplatin. We recruited 21 subjects starting cisplatin-based chemotherapy (Cisplatin-based group) and 11 treated with carboplatin-based chemotherapy or 5-fluorouracil regimens (non-cisplatin-based group). Blood and urine samples were collected during four subsequent cycles of chemotherapy (68 and 38 cycles, respectively). AKI occurred in four patients in the cisplatin-based group (5.9% of 68 cisplatin-based chemotherapy cycles). Among them, three urinary markers were increased by over 100% in two cases, two in one case and one in another. A doubling of at least one investigated parameter was observed more frequently during cisplatin-based chemotherapy (80.3% vs. 52.8%; OR = 3.65, 95% CI: 1.49-8.90; p < 0.01). The doubling of at least one new urinary AKI marker was more common in patients receiving cisplatin and frequently was not associated with overt AKI. Thus, a subclinical kidney injury detected by these markers occurs more frequently than deterioration in kidney function stated with creatinine changes.

Mediation analysis of chronic kidney disease risk factors using kidney biomarkers in women living with HIV.

Novel urinary biomarkers reflecting kidney tubule health are associated with chronic kidney disease (CKD) risk in persons living with HIV. However, it is unknown whether these biomarkers provide mechanistic insight into the associations between clinical risk factors for CKD and subsequent CKD risk. Among 636 women living with HIV in the Women's Interagency HIV Study with estimated glomerular filtration rate (eGFR) >60 ml/min/1.73 m 2 , we used a counterfactual approach to causal mediation analysis to evaluate the extent to which systolic blood pressure (SBP), diastolic blood pressure (DBP), hemoglobin a1c (Hba1c) and serum albumin associations with incident CKD were mediated by eight urine proteins. These biomarkers reflect proximal tubular reabsorptive dysfunction (α1-microglobulin [a1m], β2-microglobulin, trefoil factor 3); tubular injury (interleukin 18 [IL-18], kidney injury molecule 1 [KIM-1]); kidney repair (epidermal growth factor); tubular reserve (uromodulin); and glomerular injury (urinary albumin). Incident CKD was defined as eGFR <60 ml/min/1.73 m 2 measured at two consecutive 6-month visits with an average annual eGFR decline ≥3% per year. During a median follow-up of 7 years, 11% developed CKD. Urinary albumin and KIM-1 mediated 32% (95% CI: 13.4%, 76.6%) and 23% (6.9%, 60.7%) of the association between SBP and incident CKD, respectively; and 19% (5.1%, 42.3%) and 22% (8.1%, 45.7%) of the association between DBP and incident CKD, respectively. Urinary albumin, α1m, and IL-18 were significant mediators of the association between Hba1c and incident CKD. None of the eight biomarkers mediated the association between serum albumin and incident CKD. Among women living with HIV, several urinary biomarkers reflecting distinct dimensions of kidney health may partially explain the associations between SBP, DBP, and Hba1c and subsequent CKD risk.

Renal Biomarkers in Heart Failure: Systematic Review and Meta-Analysis

BackgroundCystatin C, neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule (KIM)-1 are renal biomarkers increasingly appreciated for their role in the risk stratification and prognostication of heart failure (HF) patients. However, very few have been adopted clinically, owing to the lack of consistency. ObjectivesThe authors aimed to study the association between cystatin C, NGAL, and KIM-1 and outcomes, mortality, hospitalizations, and worsening renal function (WRF) in patients with acute and chronic HF. MethodsWe included peer-reviewed English-language articles from PubMed and EMBASE published up to December 2021. We analyzed the above associations using random-effects meta-analysis. Publication bias was assessed using funnel plots. ResultsAmong 2,631 articles, 100 articles, including 45,428 patients, met the inclusion criteria. Top-tertile of serum cystatin C, when compared to the bottom-tertile, carried a higher pooled hazard ratio (pHR) for mortality (pHR: 1.59, 95% CI: 1.42-1.77) and for the composite outcome of mortality and HF hospitalizations (pHR: 1.49, 95% CI: 1.23-1.75). Top-tertile of serum NGAL had a higher hazard for mortality (pHR: 2.91, 95% CI: 1.49-5.67) and composite outcome (HR: 4.11, 95% CI: 2.69-6.30). Serum and urine NGAL were significantly associated with WRF, with pHRs of 2.40 (95% CI: 1.48-3.90) and 2.01 (95% CI: 1.21-3.35). Urine KIM-1 was significantly associated with WRF (pHR: 1.60, 95% CI: 1.24-2.07) but not with other outcomes. High heterogeneity was noted between studies without an obvious explanation based on meta-regression. ConclusionsSerum cystatin C and serum NGAL are independent predictors of adverse outcomes in HF. Serum and urine NGAL are important predictors of WRF in HF.