Kidney Injury Molecule-1 Staining Research Articles

Acute kidney injury decreases pulmonary vascular growth and alveolarization in neonatal rat pups.

Acute kidney injury (AKI) is common in sick neonates and associated with poor pulmonary outcomes, however, the mechanisms responsible remain unknown. We present two novel neonatal rodent models of AKI to investigate the pulmonary effects of AKI. In rat pups, AKI was induced surgically via bilateral ischemia-reperfusion injury (bIRI) or pharmacologically using aristolochic acid (AA). AKI was confirmed with plasma blood urea nitrogen and creatinine measurements and kidney injury molecule-1 staining on renal immunohistochemistry. Lung morphometrics were quantified with radial alveolar count and mean linear intercept, and angiogenesis investigated by pulmonary vessel density (PVD) and vascular endothelial growth factor (VEGF) protein expression. For the surgical model, bIRI, sham, and non-surgical pups were compared. For the pharmacologic model, AA pups were compared to vehicle controls. AKI occurred in bIRI and AA pups, and they demonstrated decreased alveolarization, PVD, and VEGF protein expression compared controls. Sham pups did not experience AKI, however, demonstrated decreased alveolarization, PVD, and VEGF protein expression compared to controls. Pharmacologic AKI and surgery in neonatal rat pups, with or without AKI, decreased alveolarization and angiogenesis, producing a bronchopulmonary dysplasia phenotype. These models provide a framework for elucidating the relationship between AKI and adverse pulmonary outcomes. There are no published neonatal rodent models investigating the pulmonary effects after neonatal acute kidney injury, despite known clinical associations. We present two novel neonatal rodent models of acute kidney injury to study the impact of acute kidney injury on the developing lung. We demonstrate the pulmonary effects of both ischemia-reperfusion injury and nephrotoxin-induced AKI on the developing lung, with decreased alveolarization and angiogenesis, mimicking the lung phenotype of bronchopulmonary dysplasia. Neonatal rodent models of acute kidney injury provide opportunities to study mechanisms of kidney-lung crosstalk and novel therapeutics in the context of acute kidney injury in a premature infant.

MO069: Therapeutic Effects of Semaglutide as Mono and Combination Treatment with Lisinopril in a Mouse Model of Hypertension-Accelerated Diabetic Kidney Disease

Abstract BACKGROUND AND AIMS Obesity, hyperglycemia and hypertension are critical risk factors for the onset and progression of diabetic kidney disease (DKD). Emerging evidence suggests that sodium-glucose cotransporter-2 (SGLT2) inhibitors and glucagon-like peptide-1 receptor (GLP-1R) agonists improve cardiovascular and renal outcomes in type 2 diabetes patients. We have recently profiled the effects of SGLT2 and angiotensin-converting enzyme (ACE) inhibition in a model of advanced DKD facilitated by adeno-associated virus (AAV)-mediated renin overexpression in uninephrectomized (UNx) diabetic db/db mice (Østergaard et al., AJP Renal Physiol 321: F149–F161, 2021). In the present study, we evaluated the nephroprotective effects of the long-acting GLP1R agonist semaglutide, a long-acting GLP1R agonist currently approved for diabetes and obesity treatment and in clinical development for DKD. Semaglutide was profiled with and without combination treatment with lisinopril, a standard ACE inhibitor, in the db/db UNx-ReninAAV mouse model of DKD. METHOD Female db/db mice received a single intravenous injection of reninAAV 1 week prior to UNx. Six weeks post-nephrectomy, mice were randomized into treatment groups based on body weight and blood glucose in the fed state, and received vehicle (SC, QD), semaglutide 30 nmol/kg or semaglutide 30 nmol/kg (SC, QD) in combination with lisinopril 30 mg/kg (PO, QD) for 11 weeks. Treatment endpoints included blood pressure, plasma/urine biochemistry and histomorphometric markers of kidney injury. RESULTS Vehicle-dosed db/db UNx-ReninAAV mice developed hallmarks of hypertensive DKD characterized by severe albuminuria and advanced glomerulosclerosis. Compared with vehicle, semaglutide significantly reduced fed blood glucose and hemoglobin A1C levels, whereas no significant effect on plasma insulin was observed. Semaglutide significantly reduced both diastolic and systolic blood pressure as well as albuminuria and urine kidney injury molecule-1 (KIM-1) levels. Semaglutide improved kidney histopathology with notable reductions in glomerulosclerosis severity and percent area of KIM-1 staining. Combined lisinopril treatment led to further improvements in blood pressure, albuminuria and glomerulosclerosis. Semaglutide with and without lisinopril coadministration did not influence plasma urea, cystatin C and kidney CD11 expression. CONCLUSION Semaglutide improved disease hallmarks in the db/db UNx-ReninAAV mouse model of advanced DKD. Further benefits on renal functional and histological markers were obtained by combination with antihypertensive standard-of-care treatment.

Combination therapy of cisplatin with cilastatin enables an increased dose of cisplatin, enhancing its antitumor effect by suppression of nephrotoxicity

Cisplatin, one of the most active anticancer agents, is widely used in standard chemotherapy for various cancers. Cisplatin is more poorly tolerated than other chemotherapeutic drugs, and the main dose-limiting toxicity of cisplatin is its nephrotoxicity, which is dose-dependent. Although less toxic methods of cisplatin administration have been established, cisplatin-induced nephrotoxicity remains an unsolved problem. Megalin is an endocytic receptor expressed at the apical membrane of proximal tubules. We previously demonstrated that nephrotoxic drugs, including cisplatin, are reabsorbed through megalin and cause proximal tubular cell injury. We further found that cilastatin blocked the binding of cisplatin to megalin in vitro. In this study, we investigated whether cilastatin could reduce cisplatin-induced nephrotoxicity without influencing the antitumor effects of cisplatin. Nephrotoxicity was decreased or absent in mice treated with cisplatin and cilastatin, as determined by kidney injury molecule-1 staining and the blood urea nitrogen content. Combined with cilastatin, a twofold dose of cisplatin was used to successfully treat the mice, which enhanced the antitumor effects of cisplatin but reduced its nephrotoxicity. These findings suggest that we can increase the dose of cisplatin when combined with cilastatin and improve the outcome of cancer patients.

Kidney injury molecule-1, a sensitive and specific marker for identifying acute proximal tubular injury, can be used to predict renal functional recovery in native renal biopsies.

Kidney injury molecule-1 (KIM-1) staining has been shown to be very useful in identifying acute proximal tubular injury, but its sensitivity, specificity and predicting values for the recovery of renal function after injury in renal biopsies have not been well established. In the first study, we randomly selected 184 renal biopsies from a wide age range of patients (children to elderly) with various renal diseases. KIM-1 staining scores were significantly correlated with serum creatinine (sCr) levels (P < 0.05) in all age groups. Receiver-operating characteristic curve (ROC) was generated to evaluate true-positive rate (sensitivity) and true-negative rate (1-specificity). The area under the curve (AUC) in pediatric cases was 0.74, which demonstrated KIM-1 was a fair index in correlating with sCr. In adults, the AUC was 0.87, indicating that KIM-1 was an even better index in the adult population in correlating to sCr. The second study was to determine whether KIM-1 could be a potential predictor of the recovery of acute kidney injury (AKI), and 51 indicated native biopsies with acute tubular injury were randomly selected for KIM-1 staining and sCr follow-up over a 6-month period. A higher KIM-1/sCr ratio (0.57 ± 0.06) was significantly and positively associated with a better reduction in sCr over 6months. In summary, our data demonstrated that KIM-1 staining in renal biopsies is a sensitive and specific marker to identify acute tubular injury and KIM-1/sCr ratio is useful for predicting the recovery of renal function after injury, although some patients' sCr levels cannot return to their baseline levels.

Kidney injury molecule-1 identifies antemortem injury in postmortem adult and fetal kidney.

There is currently no technique to unambiguously diagnose antemortem kidney injury on postmortem examination since postmortem tissue damage and autolysis are common. We assessed the ability to detect kidney injury molecule-1 (KIM-1) expression in adult and fetal kidneys examined at autopsy. In adult kidneys ( n = 52 subjects), we found that the intensity of KIM-1 staining significantly correlated with the antemortem level of serum creatinine, and this was independent of the extent of tissue autolysis. In addition, kidneys from a total of 52 fetal/neonatal subjects, 30 stillborns and 22 liveborns, were assessed for KIM-1 staining. Given that serum creatinine is unreliable and often unavailable in fetuses and newborns, we assessed preterminal hypoxia in fetuses by the presence of squames in pulmonary alveoli and by required intubation. KIM-1 expression correlated with these clinical indexes of hypoxia. The expression of KIM-1 was seen in a majority of the fetal and neonatal autopsy kidneys (77%, 40/52) as early as 16 wk of gestation, even in the presence of autolysis. Thus KIM-1 is a specific and stable marker of antemortem tubular injury in kidneys of adults and fetuses despite postmortem autolysis.

Kidney injury molecule-1 staining in renal allograft biopsies 10 days after transplantation is inversely correlated with functioning proximal tubular epithelial cells.

Kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) are promising biomarkers for monitoring delayed graft function (DGF) after kidney transplantation. Here we investigated localization and distribution of KIM-1 and NGAL staining in renal allograft biopsies and studied their association with histological features, functional DGF (fDGF) and the tubular function slope (TFS), a functioning proximal tubular epithelial cell (PTEC) marker. Day 10 protocol biopsies of 64 donation after circulatory death recipients were stained for KIM-1 and NGAL and the positive area was quantified using ImageJ software. Biopsies were scored according to Banff and acute tubular necrosis (ATN) criteria. A 99mtechnetium-mercaptoacetyltriglycine (99mTc-MAG3)-renography was performed to calculate TFS. KIM-1 staining was located on the brush border of tubular epithelial cells (TECs) and correlated with denudation, while NGAL was present more focally in a cytoplasmic distribution. KIM-1 and NGAL staining were not correlated and no co-localization was observed. Quantitative stainings were not associated with fDGF, but KIM-1 tended to be higher in patients with prolonged fDGF (≥21 days; P = 0.062). No correlation was observed between the quantitative tissue stainings and urinary KIM-1 or NGAL. Quantitative KIM-1 staining was inversely correlated with the TFS (Spearman's ρ = -0.53; P < 0.001), whereas NGAL was not. The latter finding might be because cortical NGAL staining is dependent on filtration and subsequent reabsorption by functioning PTECs. Staining of NGAL was indeed restricted to PTECs, as shown by co-localization with a PTEC-specific lectin. KIM-1 and NGAL staining showed different localization and distribution. Quantitative KIM-1 staining was inversely correlated with functioning PTECs.

Expression of Kidney Injury Molecule-1 in Healthy and Diseased Feline Kidney Tissue.

Sensitive markers to detect acute kidney injury (AKI) in cats are lacking. Kidney injury molecule-1 (KIM-1) is a promising marker of acute tubular injury in humans, and sequence and structure of feline KIM-1 have been determined. KIM-1 is shed into urine of cats with natural AKI. The objectives of this study were to characterize temporal and cellular expression of KIM-1 in kidneys from cats without and with experimental and natural AKI using histopathology and immunohistochemistry. Tissue sections from 8 cats without kidney disease, 3 to 4 cats with experimentally induced AKI on each day 1, 3, 6, and 12 after unilateral ischemia/reperfusion, and 9 cats with natural AKI were assessed. In sections from cats without kidney disease, patterns of periodic acid-Schiff and aquaporin-1 staining allowed identification of 3 distinct segments of the proximal tubule. KIM-1 staining was absent in segments 1 (S1) and S2, and faint in S3. Injury of S3 in cats with experimental and natural AKI was characterized by cell loss and necrosis, and remaining intact cells had cytoplasmic blebs and reduced brush borders. In experimental AKI, intensity of KIM-1 expression increased in proportion to the severity of injury and was consistently present in S3 but only transiently in other segments. Vimentin was absent in proximal tubules of healthy cats but expressed in injured S3. These findings indicate that S3 is the proximal tubular segment most susceptible to ischemic injury and that KIM-1 is a sensitive tissue indicator of AKI in cats.

Proximal Tubular Injury in Medullary Rays Is an Early Sign of Acute Tacrolimus Nephrotoxicity.

Tacrolimus (FK506) is one of the principal immunosuppressive agents used after solid organ transplantations to prevent allograft rejection. Chronic renal injury induced by tacrolimus is characterized by linear fibrosis in the medullary rays; however, the early morphologic findings of acute tacrolimus nephrotoxicity are not well characterized. Kidney injury molecule-1 (KIM-1) is a specific injury biomarker that has been proven to be useful in the diagnosis of mild to severe acute tubular injury on renal biopsies. This study was motivated by a patient with acute kidney injury associated with elevated serum tacrolimus levels in whom KIM-1 staining was present only in proximal tubules located in the medullary rays in the setting of otherwise normal light, immunofluorescent, and electron microscopy. We subsequently evaluated KIM-1 expression in 45 protocol and 39 indicated renal transplant biopsies to determine whether higher serum levels of tacrolimus were associated with acute segment specific injury to the proximal tubule, as reflected by KIM-1 staining in the proximal tubules of the cortical medullary rays. The data suggest that tacrolimus toxicity preferentially affects proximal tubules in medullary rays and that this targeted injury is a precursor lesion for the linear fibrosis seen in chronic tacrolimus toxicity.

Urinary β2-Microglobulin Is a Good Indicator of Proximal Tubule Injury: A Correlative Study with Renal Biopsies.

Objective. After filtration through glomeruli, β2-microglobulin is reabsorbed in proximal tubules. Increased urinary β2-microglobulin indicates proximal tubule injury and measurement of β2-microglobulin in urine is useful to determine the source of renal injury. Kidney injury molecule-1 (KIM-1) has been characterized as a selective proximal tubule injury marker. This study was designed to evaluate the correlation of urinary β2-microglobulin concentration and KIM-1 expression as evidence of proximal tubule injury. Methods. Between 2009 and 2012, 46 patients with urine β2-microglobulin (RenalVysion) had follow-up kidney biopsy. Diagnoses included glomerular and tubule-interstitial disease. Immunohistochemical staining for KIM-1 was performed and the intensity was graded from 0 to 3+. Linear regression analysis was applied to correlate the values of urinary β2-microglobulin and KIM-1 staining scores. P < 0.05 was considered statistically significant. Results. Thirty patients had elevated urinary β2-microglobulin. KIM-1 staining was positive in 35 kidney biopsies. There was a significant correlation between urinary β2-microglobulin and KIM-1 staining (P < 0.05). Sensitivity was 86.6%, specificity was 43.7%, positive predictive value was 74.2%, and negative predictive value was 63.6%. Conclusion. Increased urinary β2-microglobulin is significantly correlated with KIM-1 staining in injured proximal tubules. Measurement of urine β2-microglobulin is a sensitive assay for proximal tubule injury.

Changes of Kidney Injury Molecule-1 Expression and Renal Allograft Function in Protocol and for Cause Renal Allograft Biopsy

Background: Kidney injury molecule-1 (KIM-1) is known as a good ancillary marker of acute kidney injury (AKI) and its expression has also been observed in acute rejection and chronic graft dysfunction. We tested usefulness of KIM-1 as an indicator of acute and chronic renal graft injury by correlating KIM-1 expression with renal graft function and histology. Methods: A total of 133 zero-time biopsies and 42 follow-up biopsies obtained within 1 year posttransplantation were selected. Renal tubular KIM-1 staining was graded semiquantitatively from 0 to 3 and the extent of staining was expressed as the ratio of KIM-1 positive/CD10 positive proximal tubules using Image J program. Results: KIM-1 was positive in 39.8% of zero-time biopsies. KIM-1 positive cases were predominantly male and had received grafts from donors with older age, deceased donors, and poor renal function at the time of donation, compared with KIM-1 negative cases. KIM-1 expression showed correlation with delayed graft function and acute tubular necrosis. In comparison of KIM-1 expression between stable grafts (n=23) and grafts with dysfunction (n=19) at the time of repeated biopsy, the intensity/extent of KIM-1 staining and renal histology at zero-time did not differ significantly between the two groups. Histologically, KIM-1 expression was significantly increased with both acute and chronic changes of glomeruli, tubules and interstitium, peritubular capillaritis, and arteriolar hyalinosis. Conclusions: KIM-1 can be used as an ancillary marker of AKI and a nonspecific indicator of acute inflammation and tubulointerstitial fibrosis. However, KIM-1 expression at zero-time is not suitable for prediction of long-term graft dysfunction.

Acute Tubular Injury Is an Important Component in Type I Acute Antibody-Mediated Rejection

Background“Acute tubular necrosis (ATN)-like” changes in type I acute antibody- mediated rejection (AAMR) have been proposed since 2005, but the presence of “ATN-like” injury in AAMR has not well been established. The aim of this study was to confirm the presence of acute tubular injury in type I AAMR, using the specific proximal tubular injury marker, kidney injury molecule-1 (KIM-1). DesignThe study included 3 groups of cases, namely, a negative control group (normal nontransplantation renal parenchyma as group 1, n = 11), a positive control group (transplant ATN with negative C4d staining as group 2, n = 12), and study cases (type 1 AAMR as group 3, n = 19). Biopsy specimens from all groups were stained immunohistochemically for KIM-1 (monoclonal antibody) and KIM-1 staining intensity in proximal tubules was graded from 0.5 to 3+. Clinical indices were also correlated and analyzed. ResultsGroup 1 demonstrated significantly lower serum creatinine levels (1.02 ± 0.10 mg/dL) when compared with both group 2 and group 3. Both groups 2 and 3 showed similar serum creatinine levels (4.02 ± 0.59 mg/dL in group 2 and 3.24 ± 0.34 mg/dL in group 3). The negative control group demonstrated negative proximal tubule staining for KIM-1, whereas both groups 2 and 3 showed positive KIM-1 staining in proximal tubules (intensity ranging from 1+ to 3+ in group 2 and from 0.5 to 3+ in group 3). ConclusionOur results, using KIM-1 immunohistochemistry, demonstrated that acute tubular injury is an important component of type I AAMR.

Tissue Kidney Injury Molecule-1 Expression in the Prediction of Renal Function for Several Years after Kidney Biopsy

Objectives. Retrospective study was designed to examine the importance of tissue kidney injury molecule-1 (KIM-1) expression in predicting kidney function in sixty patients (27 males) aged 34.15 ± 12.23 years with different kidney diseases over three years after kidney biopsy. Materials and Methods. Tissue KIM-1 expression was determined immunohistochemically and KIM-1 staining was scored semiquantitatively, as well as tubulointerstitialis (TIN), inflammation, atrophy, and fibrosis. Kidney function (MDRD formula) and proteinuria/day were evaluated at the time of biopsy (GFR0) and 6, 12, 24, and 36 months later. Results. Significantly positive correlations between tissue KIM-1 expression and age (r = 0.313), TIN inflammation (r = 0.456), fibrosis (r = 0.317), and proteinuria at 6 months (r = 0.394) as well as negative correlations with GFR0 (r = −0.572), GFR6 (r = −0.442), GFR24 (r = −0.398), and GFR36 (r = −0.412) were found. Meanwhile, TIN inflammation was the best predictor of all measured kidney functions during three years, while tissue KIM-1 expression (P = 0.016) was a predictor only at 6 months after biopsy. Conclusion. Tissue KIM-1 expression significantly predicts kidney function solely at 6 months after biopsy, when the effects of immune and nonimmune treatments are the strongest.

Glomerular Expression of Kidney Injury Molecule-1 and Podocytopenia in Diabetic Glomerulopathy

Background/Aims: Studies have shown that kidney injury molecule-1 (KIM-1) is upregulated in damaged renal proximal tubules. In this study, we examined KIM-1 expression in glomerular epithelial cells in diabetic glomerulopathy. Methods: Renal histology, immunostaining and Western blot for protein level, and real-time PCR for mRNA expression of KIM-1 and podocyte markers were evaluated in untreated or losartan-treated Zucker lean (Fa/+) and Zucker diabetic fatty (Fa/Fa) rats. Results: The diabetic rats showed an increased glomerular expression of KIM-1. KIM-1 staining was localized primarily in the hyperplastic parietal epithelium of Bowman’s capsule in the early stages of diabetes with subsequent increase in KIM-1-positive cells in the glomerular tuft in the more advanced stages. The increase in glomerular KIM-1 was associated with a decrease in podocytes in Fa/Fa rats. Antiproteinuric treatment with losartan attenuated podocytopenia and decreased renal expression of KIM-1 in treated diabetic rats. In an in vitro study, albumin overload increased KIM-1 protein in the primary cultures of rat glomerular epithelial cells. Conclusion: These results show that glomerular KIM-1 expression was increased, in proportion to the extent of proteinuria and podocytopenia in the diabetic animals, supporting that KIM-1 could be used as a potential biomarker for glomerular injury in proteinuric kidney disease.

Tubular Expression of KIM-1 Does not Predict Delayed Function After Transplantation

Injured epithelial cells of the proximal tubule upregulate the glycoprotein kidney injury molecule 1 (KIM-1), suggesting its potential as a biomarker of incipient kidney allograft injury. It is unknown whether KIM-1 expression changes in kidney allografts with delayed graft function (DGF), which often follows ischemia-reperfusion injury. Here, we prospectively measured KIM-1 RNA and protein expression in preperfusion biopsies of 30 living- and 85 deceased-donor kidneys and correlated the results with histologic and clinical outcomes after transplantation. We detected KIM-1 expression in 62% of deceased-donor kidneys and only 13% of living-donor kidneys (P < 0.0001). The level of KIM-1 expression before reperfusion correlated inversely with renal function at the time of procurement and correlated directly with the degree of interstitial fibrosis. Surprising, however, we did not detect a significant correlation between KIM-1 staining intensity and the occurrence of DGF. Our findings are consistent with a role for KIM-1 as an early indicator of tubular injury but do not support tissue KIM-1 measurement before transplantation to identify kidneys at risk for DGF.

Kidney injury molecule-1 expression in transplant biopsies is a sensitive measure of cell injury

Kidney injury molecule-1 (KIM-1) is a specific histological biomarker for diagnosing early tubular injury on renal biopsies. In this study, KIM-1 expression was quantitated in renal transplant biopsies by immunohistochemistry and correlated with renal function. None of the 25 protocol biopsies showed detectable tubular injury on histologic examination, yet 28% had focal positive KIM-1 expression. Proximal tubule KIM-1 expression was present in all biopsies from patients with histological changes showing acute tubular damage and deterioration of kidney function. In this group, higher KIM-1 staining predicted a better outcome with improved blood urea nitrogen (BUN), serum creatinine, and estimated glomerular filtration rate (eGFR) over an ensuing 18 months. KIM-1 was expressed focally in affected tubules in 92% of kidney biopsies from patients with acute cellular rejection. By contrast, there was little positive staining for Ki-67, a cell proliferation marker, in any of the groups. KIM-1 expression significantly correlated with serum creatinine and BUN, and inversely with the eGFR on the biopsy day. Our study shows that KIM-1 staining sensitively and specifically identified proximal tubular injury and correlated with the degree of renal dysfunction. KIM-1 expression is more sensitive than histology for detecting early tubular injury, and its level of expression in transplant biopsies may indicate the potential for recovery of kidney function.