Kidney injury molecule-1 and osteopontin: New markers for prediction of early kidney transplant rejection

Investigation on the association between Osteopontin and Apolipoprotein E gene polymorphisms and vancomycin-induced acute kidney injury: A pharmacokinetic/pharmacogenetic study in critically ill patients

Vancomycin is a commonly administered antibiotic for various Gram-positive infections in critically ill patients. Vancomycin has a narrow therapeutic index and its main adverse drug reaction is acute kidney injury (AKI). In this regard, various pharmacokinetic parameters have been widely considered for therapeutic drug monitoring (TDM) purposes. Higher vancomycin trough concentration and area under the curve (AUC) values would be associated with higher rates of AKI. Therefore, dose adjustment based on targeted pharmacokinetic values would be essential to avoid toxicity and achieve optimal clinical response. However, there are numerous reports regarding the discrepancy between pharmacokinetic parameter values and AKI. In this regard, we examined the possible role of pharmacogenetics in vancomycin-induced AKI to distinguish patients who are genetically prone to AKI. In this cross-sectional study, polymorphisms of osteopontin (OPN) and Apolipoprotein E (APOE) along with pharmacokinetic parameters were assessed in 87 critically ill patients admitted to ICU wards and received vancomycin. The results indicated a significant difference in OPN and APOE genotype distribution between AKI and non-AKI patients (P = 0.001 and 0.02, respectively). Stepwise multivariate logistic regression analysis showed that patients with e2e3 genotype were 4.2-fold more prone to AKI (P = 0.029; OR = 4.2; 95 %CI = 1.2-15.7). Moreover, there was a significant correlation between pharmacokinetic parameters (calculated trough concentration, AUCτ, AUC24h, and t1/2) and vancomycin-induced AKI. Genotyping the patients for OPN and APOE polymorphisms before vancomycin initiation would be promising as a routine clinical practice to obtain an efficient clinical response and prevent vancomycin-induced AKI, especially in critically ill patients.

The immune duality of osteopontin and its therapeutic implications for kidney transplantation

Osteopontin (OPN) is a multifunctional glycoprotein with various structural domains that enable it to perform diverse functions in both physiological and pathological states. This review comprehensively examines OPN from multiple perspectives, including its protein structure, interactions with receptors, interactions with immune cells, and roles in kidney diseases and transplantation. This review explores the immunological duality of OPN and its significance and value as a biomarker and therapeutic target in kidney transplantation. In cancer, OPN typically promotes tumor evasion by suppressing the immune system. Conversely, in immune-related kidney diseases, particularly kidney transplantation, OPN activates the immune system by enhancing the migration and activation of immune cells, thereby exacerbating kidney damage. This immunological duality may stem from different OPN splice variants and the exposure, after cleavage, of different structural domains, which play distinct biological roles in cellular interactions. Additionally, OPN has a significant biological impact posttransplantation and on chronic kidney disease and, highlighting its importance as a biomarker and potential therapeutic target. Future research should further explore the specific mechanisms of OPN in kidney transplantation to improve treatment strategies and enhance patient quality of life.

Assessment of osteopontin as an early nephrotoxicity indicator in human renal proximal tubule cells and its application in evaluating lanthanum-induced nephrotoxicity

Nephrotoxicity is a common adverse effect induced by various chemicals, necessitating the development of reliable toxicity screening models for nephrotoxicity assessment. In this study, we assessed a group of nephrotoxicity indicators derived from different toxicity pathways, including conventional endpoints and kidney tubular injury biomarkers such as clusterin (CLU), kidney injury molecule-I (KIM-1), osteopontin (OPN), and neutrophil gelatinase-associated lipocalin (NGAL), using HK-2 and induced pluripotent stem cells (iPSCs)-derived renal proximal tubular epithelial-like cells (PTLs). Among the biomarkers tested, OPN emerged as the most discerning and precise marker. The predictive potential of OPN was tested using a panel of 10 nephrotoxic and 5 non-nephrotoxic compounds. The results demonstrated that combining OPN with the half-maximal inhibitory concentration (IC50) enhanced the diagnostic accuracy in both cellular models. Additionally, PTLs cells showed superior predictive efficacy for nephrotoxicity compared to HK-2 cells in this investigation. The two cellular models were utilized to evaluate the nephrotoxicity of lanthanum. The findings indicated that lanthanum possesses nephrotoxic properties; however, the degree of nephrotoxicity was relatively low, consistent with the outcomes of in vivo experiments.

Renal tubular dysfunction in greenhouse farmers exposed to pesticides unveiled by a panel of molecular biomarkers of kidney injury

Growing evidence suggests that chronic exposure to pesticides may cause adverse effects on the health of the exposed population leading to organ-specific toxicity, including kidney damage. Traditional markers used to assess renal function (glomerular filtration rate (GFR), and serum creatinine and cystatin C -Cys-C-) are inadequate to evaluate a potential subclinical renal impairment linked to occupational exposure to pesticides, since levels above the upper limit of normal only occur when renal damage is very extensive. The use of more sensitive biomarkers is therefore needed. This study investigated novel urinary biomarkers of kidney function (microalbuminuria, osteopontin (OPN), trefoil factor 3 (TFF3), β-2-microglobulin, neutrophil gelatinase-associated lipocalin (NGAL), and Cys-C), together with the aforementioned traditional serum biomarkers, to assess potential kidney damage in farmers exposed to pesticides in an intensive agriculture setting. The study population consisted of 175 greenhouse workers and 91 healthy control subjects from Almeria (Southeastern Spain), a major hub of greenhouse agriculture. Data were collected at two different time-points of the same crop season: a period with greater pesticide use (high exposure period) and another with lower pesticide use (low exposure period). Significantly higher urinary levels of OPN and TFF3 were found in greenhouse workers than in controls, and in the high pesticide exposure period compared to that of low exposure. These changes suggest a subclinical tubular damage linked to pesticide exposure. In contrast, microalbuminuria, GFR, serum creatinine and Cys-C failed to be associated with pesticide exposure, suggesting that glomerular function was spared. Increased OPN and TFF3 levels over time may suggest a gradual progression from tubular dysfunction to chronic kidney disease in the exposed population.

Evaluation of NAG, NGAL, and KIM-1 as Prognostic Markers of the Initial Evolution of Kidney Transplantation

Kidney transplantation is the best option for end-stage chronic kidney disease. Transplant viability is conditioned by drugs' nephrotoxicity, ischemia-reperfusion damage, or acute rejection. An approach to improve graft survival is the identification of post-transplant renal function prognostic biomarkers. Our objective was to study three early kidney damage biomarkers (N-acetyl-d-glucosaminidase, NAG; neutrophil gelatinase-associated lipocalin, NGAL; and kidney injury molecule-1, KIM-1) in the initial period after transplantation and to identify possible correlations with main complications. We analysed those biomarkers in urine samples from 70 kidney transplant patients. Samples were taken on days 1, 3, 5, and 7 after intervention, as well as on the day that renal function stabilised (based on serum creatinine). During the first week after transplant, renal function improved based on serum creatinine evolution. However, increasing levels of biomarkers at different times during that first week could indicate tubular damage or other renal pathology. A relationship was found between NGAL values in the first week after transplantation and delayed graft function. In addition, higher NAG and NGAL, and lower KIM-1 values predicted a longer renal function stabilisation time. Therefore, urinary NAG, NGAL, and KIM-1 could constitute a predictive tool for kidney transplant complications, contributing to improve graft survival rates.

p-Coumaric Acid Nanoparticles Ameliorate Diabetic Nephropathy via Regulating mRNA Expression of KIM-1 and GLUT-2 in Streptozotocin-Induced Diabetic Rats

Diabetic nephropathy (DN) has become a leading cause of end-stage renal failure worldwide. The goal of the current study was to examine the protective effects of chitosan-loaded p-Coumaric acid nanoparticles (PCNPs) in nephrotoxicity induced by streptozotocin (STZ). Because of the antidiabetic, anti-inflammatory, and antioxidant properties of PCNPs, the development of DN may be considerably decreased. In this study, the rats received a single intraperitoneal injection (i.p.) of STZ (45 mg/kg) to induce DN. PCNPs were given orally 80 mg/kg b.w to the rats for a duration of four weeks. Body weight, kidney weight, blood glucose, and insulin levels were measured at the end of the experiment. Serum and urine parameters were also examined, along with the histological, immunobiological, and tumor necrosis factor (TNF) and interleukin-6 (IL-6) expression of the nephrotic rats. To comprehend the impact of PCNPs, the expression patterns of the kidney injury molecule (KIM-1) and glucose transporter-2 (GLUT-2) were evaluated. Administration of PCNPs significantly increased body weight, decreased kidney weight and also ameliorated blood glucose levels in the nephropathic rats. The administration of PCNPs also reverted the levels of urea, serum creatinine, urinary NAG, β-glucuronidase and albumin to near-normal levels. The administration of PCNPs also caused the levels of serum and urine parameters to return to near-normal levels. Additionally, the PCNP-treated rats had markedly reduced TNF-α, IL-6, and KIM-1 expressions as well as enhanced GLUT-2 mRNA expression. Our findings clearly showed that PCNP administration prevents the onset of DN in rats by lowering hyperglycemia, decreasing inflammation, and improving the expression of GLUT-2 mRNA in nephropathic rats.

The Most Promising Biomarkers of Allogeneic Kidney Transplant Rejection

Clinical transplantology is a constantly evolving field of medicine. Kidney transplantation has become standard clinical practice, and it has a significant impact on reducing mortality and improving the quality of life of patients. Allogenic transplantation induces an immune response, which may lead to the rejection of the transplanted organ. The gold standard for evaluating rejection of the transplanted kidney by the recipient's organism is a biopsy of this organ. However, due to the high invasiveness of this procedure, alternative diagnostic methods are being sought. Therefore, the biomarkers may play an essential predictive role in transplant rejection. A review of the most promising biomarkers for early diagnosis and prognosis prediction of allogenic kidney transplant rejection summarizes novel data on neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), C-X-C motif chemokine 10 (CXCL-10), cystatin C (CysC), osteopontin (OPN), and clusterin (CLU) and analyses the dynamics of changes of the biomarkers mentioned above in kidney diseases and the mechanism of rejection of the transplanted kidney.

Association of osteopontin with kidney function and kidney failure in chronic kidney disease patients: the GCKD study

BACKGROUND

Osteopontin (OPN), synthesized in the thick ascending limb of Henle's loop and in the distal tubule, is involved in the pathogenesis of kidney fibrosis, a hallmark of kidney failure (KF). In a cohort of chronic kidney disease (CKD) patients, we evaluated OPN's association with kidney markers and KF.

METHODS

OPN was measured from baseline serum samples of German Chronic Kidney Disease study participants. Cross-sectional regression models for estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (UACR) as well as Cox regression models for all-cause mortality and KF were evaluated to estimate the OPN effect. Additionally, predictive ability, of OPN and time-dependent population-attributable fraction were evaluated.

RESULTS

Over a median follow-up of 6.5 years, 471 KF events and 629 deaths occurred among 4,950 CKD patients. One-unit higher log(OPN) was associated with 5.5 mL/min/1.73m2 lower eGFR (95%CI: [-6.4,-4.6]) and 1% change in OPN with 0.7% higher UACR (estimated effect 0.7, 95%CI: [0.6,0.8]). Moreover, higher OPN levels were associated with a higher risk of KF (hazard ratio [HR] 1.4, 95%CI: [1.2,1.7]) and all-cause mortality (HR 1.5, 95%CI: [1.3,1.8]). After 6 years, 31% of the KF events could be attributed to higher OPN levels (95%CI: [3%,56%]).

CONCLUSIONS

In this study, higher OPN levels were associated with kidney function markers worsening, and a higher risk for adverse outcomes. A larger proportion of KF could be attributed to higher OPN levels warranting further research on OPN with regards to its role in CKD progression and possible treatment options.

Identification of kidney injury released circulating osteopontin as causal agent of respiratory failure

Tissue injury can drive secondary organ injury; however, mechanisms and mediators are not well understood. To identify interorgan cross-talk mediators, we used acute kidney injury (AKI)-induced acute lung injury (ALI) as a clinically important example. Using kidney and lung single-cell RNA sequencing after AKI in mice followed by ligand-receptor pairing analysis across organs, kidney ligands to lung receptors, we identify kidney-released circulating osteopontin (OPN) as a novel AKI-ALI mediator. OPN release from kidney tubule cells triggered lung endothelial leakage, inflammation, and respiratory failure. Pharmacological or genetic OPN inhibition prevented AKI-ALI. Transplantation of ischemic wt kidneys caused AKI-ALI, but not of ischemic OPN-global knockout kidneys, identifying kidney-released OPN as necessary interorgan signal to cause AKI-ALI. We show that OPN serum levels are elevated in patients with AKI and correlate with kidney injury. Our results demonstrate feasibility of using ligand-receptor analysis across organs to identify interorgan cross-talk mediators and may have important therapeutic implications in human AKI-ALI and multiorgan failure.

Association of serum osteopontin with first hospitalization and all-cause mortality after kidney transplantation

Objective:

Osteopontin (OPN) is involved in vascular calcification and atherosclerosis. We evaluated the association between serum OPN levels and the first postoperative hospitalization and all-cause mortality in patients who received kidney transplantation (KT).

Materials and Methods:

Seventy KT recipients were enrolled in this study from January to April 2012. The primary end point was first postoperative hospitalization or death. All patients were monitored in the outpatient clinics until June 30, 2017. Serum OPN level was measured by enzyme-linked immunosorbent assay.

Results:

During follow-up (median length, 65 months), 47 first postoperative hospitalizations and 8 deaths occurred. In comparison with serum median OPN levels, serum OPN level was positively associated with KT duration (P = 0.048), serum blood urea nitrogen (BUN; P = 0.043), and serum creatinine levels (P = 0.045) but negatively associated with estimated glomerular filtration rate (eGFR; P = 0.049). Hospitalized KT recipients had a higher prevalence of diabetes mellitus (DM) (P = 0.032), BUN (P = 0.002), and serum OPN level (P = 0.001) but lower eGFR (P = 0.030) than did patients not hospitalized. KT recipients who died had higher serum level of creatinine (P = 0.009) and OPN (P = 0.001) but lower eGFR (P = 0.036) than did surviving patients. Multivariate Cox analysis adjusted for age, gender, DM, hypertension, eGFR, KT duration, and steroid used showed that serum OPN level was associated with both first postoperative hospitalization (P = 0.049) and all-cause mortality (P = 0.017).

Conclusions:

Serum OPN level is a potential biomarker for first postoperative hospitalization and all-cause mortality in KT recipients.

Osteopontin in Cardiovascular Diseases

Unprecedented advances in secondary prevention have greatly improved the prognosis of cardiovascular diseases (CVDs); however, CVDs remain a leading cause of death globally. These findings suggest the need to reconsider cardiovascular risk and optimal medical therapy. Numerous studies have shown that inflammation, pro-thrombotic factors, and gene mutations are focused not only on cardiovascular residual risk but also as the next therapeutic target for CVDs. Furthermore, recent clinical trials, such as the Canakinumab Anti-inflammatory Thrombosis Outcomes Study trial, showed the possibility of anti-inflammatory therapy for patients with CVDs. Osteopontin (OPN) is a matricellular protein that mediates diverse biological functions and is involved in a number of pathological states in CVDs. OPN has a two-faced phenotype that is dependent on the pathological state. Acute increases in OPN have protective roles, including wound healing, neovascularization, and amelioration of vascular calcification. By contrast, chronic increases in OPN predict poor prognosis of a major adverse cardiovascular event independent of conventional cardiovascular risk factors. Thus, OPN can be a therapeutic target for CVDs but is not clinically available. In this review, we discuss the role of OPN in the development of CVDs and its potential as a therapeutic target.

Osteopontin and Transplantation: Where Are We Now?

Organ transplantation represents the optimal therapeutic tool for patients with end-stage organ failure. Hematopoietic stem cell transplantation (HSCT) is likewise an effective therapy for a wide range of malignant and non-malignant diseases. Better understanding of transplantation immunology and the use of multi-modal immunosuppression protocols, can decrease the risk of graft failure and graft-versus-host disease (GVHD) after HSCT. Nevertheless, a major challenge of modern transplantology still seems to be finding non-invasive biomarkers for recipients selection, monitoring of allograft function, and diagnosis of rejection. Since proinflammatory cytokine osteopontin (OPN) is closely involved in regulating both adaptive and innate immune responses, as well as the pathogenesis of inflammatory and autoimmune diseases, it is likely to play an important role in organ and HSC transplantation. This review is to summarize recent advances in our knowledge about OPN function in the kidney, heart, liver, lung, and HSC transplantation. Most studies found that elevated OPN is associated with poorer graft function in kidney, heart, liver and lung recipients. Moreover, some reports suggested that this protein can play role in GVHD pathogenesis. However, due to relatively small number of similar studies, as well as some inconclusive results, future investigation in this field is needed to verify if OPN can serve as a biomarker of organ and HSC transplantation. The knowledge about such markers will promote our understanding of the mechanisms underlying graft dysfunction and posttransplant mortality. In addition, such knowledge may be helpful in the development of new treatment strategies and identification of recipients with increased risk of allograft failure.

Exploration of zebrafish larvae as an alternative whole-animal model for nephrotoxicity testing

Due to an increasing demand for testing of new and existing chemicals and legal restrictions for the use of animals, there is a strong need for alternative approaches to assess systemic toxicity. Embryonic and larval zebrafish (Danio rerio) are increasingly recognized as a promising alternative whole-animal model that may be able to overcome limitations of cell-based in vitro assays and bridge the gap between high-throughput in vitro screening and low-throughput in vivo tests in animals. Despite the relatively simple anatomical structure of the zebrafish larval kidney (pronephros) - composed of only two nephrons - the pronephros shares major functions and cell types with mammalian nephrons. Glomerular filtration begins at 48 h post fertilization. The aim of the present study was to investigate if early zebrafish larvae might be a suitable model for nephrotoxicity testing. On day 3 post fertilization, larval zebrafish were treated with selected nephrotoxins (aristolochic acid, cadmium chloride, potassium bromate, ochratoxin A, gentamicin) for 48 h. Histological evaluation of zebrafish larvae exposed to model nephrotoxins revealed tubule injury as evidenced by dilated tubules with loss of the brush border, tubule cell necrosis and disorganization of the tubular epithelium. These changes were most severe after treatment with gentamicin, which also impaired pronephros function as evidenced by reduced clearance of FITC-dextran. Whole-mount in situ hybridization showing loss of cdh17 expression revealed site-specific injury to the proximal tubule segment. Analysis of genes previously identified as novel biomarkers of kidney injury in mammals showed upregulation of the kidney injury marker genes heme oxygenase 1 (hmox1), clusterin (clu), secreted phosphoprotein/osteopontin (spp1), connective tissue growth factor (ctgf) and kim-1 (havcr-1) in response to nephrotoxin treatment, although the response of individual genes varied across compounds. Consistent with the severity of lesions and impaired kidney function, the most prominent gene expression changes occurred in larvae exposed to gentamicin. Overall, our results suggest that larval zebrafish may be a suitable alternative model organism for nephrotoxicity screening, yet further improvements and integration with quantitative in vitro to in vivo extrapolation will be needed to predict human toxicity.

Sulphated polysaccharide from Sargassum myriocystum confers protection against gentamicin-induced nephrotoxicity in adult zebrafish

The beneficial effect of purified fraction of sulphated polysaccharide extracted from Sargassum myriocystum (SMP) was examined on the gentamicin-induced nephrotoxicity in adult zebrafish. The major purified fractions (SMP1, SMP2 and SMP3) were obtained by anion-exchange and size-exclusion chromatography and characterized by FTIR, GCMS and NMR. The in vitro antioxidant activities of all purified SMP fractions were analysed. The SMP2 showed maximum carbohydrate, sulphate and fucose content with strong antioxidant activity than other fractions. Further, we evaluated the efficacy of SMP2 against gentamicin-induced nephrotoxicity in zebrafish model. The SMP2 administered group showed a significant attenuation in oxidative stress and histopathological alterations observed in renal tissues of gentamicin treated group. Moreover, the SMP2 supressed renal mRNA expression levels of KIM-1, NF-κB, TNF-α and IL-6 in dose-dependent manner. Thus, the present study suggests that the SMP2 is a potent antioxidant with anti-inflammatory and renoprotective properties that ameliorated the GEN induced nephrotoxicity in adult zebrafish.

Dynamic variation of kidney injury molecule-1 mRNA and protein expression in blood and urine of renal transplant recipients: a cohort study

BACKGROUND

Acute renal dysfunction still constitutes a highly significant obstacle to renal transplantation outcome. Kidney injury molecule-1 is highly upregulated in proximal tubular cells and shed into the urine and blood circulation following kidney injury. The aim of current cohort study was to evaluate the urine KIM-1 (uKIM-1) mRNA expression level and its protein concentration in blood and urine samples to determine whether sequential monitoring of KIM-1 in renal allograft recipients is a reliable biomarker for predicting the clinical status and outcome.

METHODS

Both uKIM-1 mRNA expression level and the level of serum and uKIM-1 protein concentration in the 52 renal transplant recipients were respectively quantified using real-time PCR and ELISA methods at 2, 90 and 180 days after transplantation.

RESULT

KIM-1 mRNA and protein expression level in the blood and urine samples of patients with graft dysfunction was significantly higher than patients with well-functioning graft on days 2, 90 and 180 after transplantation. Receiver-operating characteristic curve analysis of mRNA and protein expression levels showed that urinary and blood KIM-1 at months 3 and 6 could predict acute renal dysfunction at 6 months and 1 year after transplantation.

CONCLUSION

Sequential monitoring of uKIM-1 mRNA expression level and its protein concentration in the serum and urine samples of renal transplant patients suggests that KIM-1 could be a sensitive and specific biomarker for early diagnosis and prognosis of kidney allograft injury.

Non-invasive differentiation of non-rejection kidney injury from acute rejection in pediatric renal transplant recipients

Acute kidney injury (AKI) is a major concern in pediatric kidney transplant recipients, where non-alloimmune causes must be distinguished from rejection. We sought to identify a urinary metabolite signature associated with non-rejection kidney injury (NRKI) in pediatric kidney transplant recipients. Urine samples (n = 396) from 60 pediatric transplant participants were obtained at time of kidney biopsy and quantitatively assayed for 133 metabolites by mass spectrometry. Metabolite profiles were analyzed via projection on latent structures discriminant analysis. Mixed-effects regression identified laboratory and clinical predictors of NRKI and distinguished NRKI from T cell-mediated rejection (CMR), antibody-mediated rejection (AMR), and mixed CMR/AMR. Urine samples (n = 199) without rejection were split into NRKI (n = 26; ΔSCr ≥25%), pre-NRKI (n = 35; ΔSCr ≥10% and <25%), and no NRKI (n = 138; ΔSCr <10%) groups. The NRKI discriminant score (dscore) distinguished between NRKI and no NRKI (AUC = 0.86; 95% CI = 0.79-0.94), confirmed by leave-one-out cross-validation (AUC = 0.79; 95% CI = 0.68-0.89). The NRKI dscore also distinguished between NRKI and pre-NRKI (AUC = 0.82; 95% CI = 0.71-0.93). In a linear mixed-effects regression model to account for repeated measures, the NRKI dscore was independent of concurrent rejection, but there was a non-statistical trend for higher dscores with rejection severity. A second exploratory classifier developed to distinguish NRKI from clinical rejection had similar test characteristics (AUC = 0.81, 95% CI = 0.70-0.92, confirmed by LOOCV). This study demonstrates the potential of a urine metabolite classifier to detect NRKI in pediatric kidney transplant patients and non-invasively discriminate NRKI from rejection.

Biomarkers for individualized dosage adjustments in immunosuppressive therapy using calcineurin inhibitors after organ transplantation

Calcineurin inhibitors (CNIs), such as cyclosporine A and tacrolimus, are widely used immunosuppressive agents for the prevention of post-transplantation rejection and have improved 1-year graft survival rates by up to 90%. However, CNIs can induce severe reactions, such as acute or chronic allograft nephropathy, hypertension, and neurotoxicity. Because CNIs have varied bioavailabilities, narrow therapeutic ranges, and individual propensities for toxic effects, therapeutic drug monitoring is necessary for all CNIs. Identifying the genetic polymorphisms in drug-metabolizing enzymes will help to determine personalized dosage regimens for CNIs, as CNIs are substrates for CYP3A5 and P-glycoprotein (P-gp, MDR1). CNIs are often concomitantly administered with voriconazole or proton pump inhibitors (PPIs), giving rise to drug interaction problems. Voriconazole and PPIs can increase the blood concentrations of CNIs, and both are primarily metabolized by CYP2C19. Thus, it is expected that interactions between CNIs and voriconazole or PPI would be affected by CYP2C19 and CYP3A5 polymorphisms. CNI-induced acute kidney injury (AKI) is a serious complication of transplantations. Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (KIM-1) are noninvasive urinary biomarkers that are believed to be highly sensitive to CNI-induced AKI. In this article, we review the adverse events and pharmacokinetics of CNIs and the biomarkers related to CNIs, including CYP3A5, CYP2C19, MDR1, NGAL, and KIM-1. We hope that these data will help to identify the optimal biomarkers for monitoring CNI-based immunosuppressive therapy after organ transplantation.

Osteopontin Levels in Patients With Chronic Kidney Disease Stage 5 on Hemodialysis Directly Correlate With Intact Parathyroid Hormone and Alkaline Phosphatase

Chronic kidney disease stage 5 (CKD5) marks the fifth stage of renal failure, frequently causing dysregulation of bone and mineral metabolism. Challenges exist in evaluating and managing chronic kidney disease-mineral bone disorder (CKD-MBD) with the standard panel of biomarkers. Our objective was to profile osteopontin (OPN) in patients with CKD5 on maintenance hemodialysis (CKD5-HD) and elucidate its relationship to phosphorus (P), calcium (Ca2+), alkaline phosphatase (AP), and intact parathyroid hormone (iPTH) to improve understanding of the present model of CKD-MBD. Elevation of plasma OPN was seen in the CKD5-HD cohort (n = 92; median: 240.25 ng/mL, interquartile range [IQR]: 169.85 ng/mL) compared to a normal group (n = 49; median: 63.30 ng/mL, IQR: 19.20 ng/mL; p < .0001). Spearman correlation tests revealed significant positive correlations of OPN with iPTH (p < .0001; r = 0.561, 95% confidence interval = 0.397-0.690) and OPN with AP (p < .0001; r = 0.444, 95% confidence interval = 0.245-0.590) in CKD5-HD patients. Ultimately, OPN may play an integral role in the MBD axis, suggesting that it may be important to actively monitor OPN when managing CKD5-HD.

Moringa oleifera Leaves Extract Protects Titanium Dioxide Nanoparticles-Induced Nephrotoxicity via Nrf2/HO-1 Signaling and Amelioration of Oxidative Stress

The efficacy of Moringa oleifera leaf extract (MO) in alleviating nephrotoxicity induced by titanium dioxide nanoparticles (TiO₂ NPs) was studied. Rats were divided into four groups. Group I received distilled water. Group II received TiO₂NPs. Group III received both TiO₂NPs suspension beside MO. Group IV received MO only. Kidney KIM-1, NF-кB TNF-α, and HSP-70 expression were significantly upregulated while both Nrf2 and HO-1were significantly downregulated in TiO₂NPs-treated rats. MO decreases expression of KIM-1, NF-кB, TNF-α, and HSP-70. In addition, MO has markedly upregulated the expression of Nrf2 and HO-1. In conclusion, MO can inhibit nephrotoxicity by suppressing oxidative stress and inflammation. These effects are suggested to be mediated by activating Nrf2/HO-1.The biochemical analysis and histopathological finding reinforced these results. These data support the antioxidant properties' nutraceutical role of MO against TiO₂NPs-induced toxicity.

The role of osteopontin in kidney diseases

BACKGROUND

Osteopontin (OPN) is a pleiotropic glycoprotein expressed in various cell types in animals and in humans, including bone, immune, smooth muscle, epithelial and endothelial cells. Moreover, OPN is found in kidneys (in the thick ascending limbs of the loop of Henle and in distal nephrons) and urine. The protein plays an important role in mineralization and bone resorption. In addition, OPN is involved in the regulation of immunity and inflammation, angiogenesis and apoptosis. It was demonstrated that OPN and some OPN gene polymorphic variants are associated with the pathogenesis and progression of multiple disorders, such as cancer, autoimmune, neurodegenerative and cardiovascular diseases. Moreover, recent studies suggested that OPN is associated with the pathogenesis of renal failure.

METHODS

In this review, I briefly discussed the role of OPN and its gene polymorphisms in kidney physiology, as well as in various kidney diseases.

FINDINGS AND CONCLUSION

Most studies reported that OPN expression is elevated in urolithiasis, and also in acute and chronic kidney diseases, and in renal allograft dysfunction. Moreover, it was demonstrated that polymorphic variants of the OPN gene may be associated with renal failure. However, some reports suggested that OPN is essential for tubulogenesis, and that it inhibits calcium oxalate crystal formation and retention, nitric oxide synthesis, cell apoptosis and promotes cell regeneration. Thus, further studies are required to fully understand the role of OPN in kidney physiology and pathology. Eventually, these studies may result in the identification of OPN as a valuable marker for renal dysfunction prognosis and treatment.

Anti-carcinogenic effect of hesperidin against renal cell carcinoma by targeting COX-2/PGE2 pathway in Wistar rats

The present study was designed to evaluate the protective effects of hesperidin, a flavonoid on DEN initiated and Fe-NTA promoted renal carcinogenesis in Wistar rats. Renal cancer was initiated by a single i.p. injection of DEN (200 mg/kg b.wt.) and promoted with Fe-NTA (9 mg Fe/kg b.wt. i.p.) twice a week for 16 weeks. Rats were simultaneously administered with hesperidin (100 and 200 mg/kg b.wt.) for 16 consecutive weeks. The chemopreventive effect of hesperidin was assessed in terms of antioxidant activities, renal function, PGE2 level, and the expressions of COX-2 and VEGF. Hesperidin decreased the DEN and Fe-NTA induced lipid peroxidation, improved the renal function (by decreasing the levels of BUN, creatinine, and KIM-1) and restored the renal antioxidant armory (GSH, GPx, GR, SOD, and catalase). Hesperidin was also found to decrease the level of PGE2 and downregulate the expressions of COX-2 and VEGF. Histological findings further revealed the protective effects of hesperidin against DEN and Fe-NTA induced kidney damage. The result of our present findings suggest that hesperidin may be a promising modulator in preventing renal cancer possibly by virtue of its ability to alleviate oxidative stress and inhibit COX-2/PGE2 pathway.

Multiple-biomarkers provide powerful prediction of early acute renal allograft rejection by combination of serum fractalkine, IFN-γ and IP-10

Biomarkers are urgently required for predicting rejection so that anti-rejection treatment can be taken early to protect the allograft from irreversible damage. We hypothesized that the combination of circulating fractalkine, IFN-γ and IP-10 might serve as effective biomarkers for predicting early acute renal allograft rejection. We conducted a retrospective study of 87 subjects, who were classified into acute rejection group (ARG; n = 38) and non-rejection group (NRG; n = 49). Serum fractalkine, IFN-γ and IP-10 levels were measured by Luminex. The levels of fractalkine on day 0 and 7th day, IP-10 on 4th and 7th day, and IFN-γ on 7th day in ARG was significantly higher than that in NRG. Kaplan-Meier survival analysis highlighted the higher-levels groups of fractalkine on day 0, 4th and 7th day, IFN-γ on day 0, 1st, 4th, and 7th day and IP-10 on the 4th and 7th day in rejection-free survival probability were significantly lower than low-levels groups. ROC analyses highlight the superiority of fractalkine on day 0, IP-10 on day 0, 4th and 7th day, and IFN-γ on day 0, 1st and 7th day in prediction of acute rejection. We found the combination of fractalkine on day 0, IP-10 on 7th day and IFN-γ on 7th day had the highest AUC (0.866) for predicting rejection with a sensitivity of 86.8% and a specificity of 89.8%. Our findings demonstrated a more powerful prediction of early acute renal allograft rejection during the first month after transplantation by combination of multiple-biomarkers of fractalkine, IFN-γ and IP-10, and the results might help stratify the immunologic risk of acute allograft rejection in recipients.

Protective effect of Rotula aquatica Lour against gentamicin induced oxidative stress and nephrotoxicity in Wistar rats

Gentamicin is an aminoglycoside antibiotic widely used for the treatment of life-threatening infections caused by Gram-negative bacteria. The use of gentamicin was limited due to its ototoxic and nephrotoxic adverse effects. The current study was designed to evaluate the protective effect of ethyl acetate fraction from Rotula aquatica (EFRA) against gentamicin induced nephrotoxicity. The antioxidant enzymes status, lipid peroxidation, nitrate and ROS level, serum markers like creatinine, Urea, BUN were estimated in the present study. The histopathological analysis of renal tissues was done by H&E and PAS staining. The mRNA level expression of KIM-1, NF-κB, TNF- α, and IL-6 were measured by semi-quantitative reverse transcription-polymerase chain reaction. The changes in antioxidant parameters were restored by the treatment of EFRA at different dose (50 mg/kg bwt, 100 mg/kg bwt). The serum parameters, ROS, MDA and nitrate level were decreased by administration of EFRA. The EFRA ameliorates histological changes associated with gentamicin induced nephrotoxicity. The mRNA level expression of KIM-1, NF-κB, TNF- α, and IL-6 were downregulated in EFRA treated groups. The results from present study reveals the role of EFRA as good anti-inflammatory and nephro protective drug.

High expression of TIM-3 and KIM-1 in blood and urine of renal allograft rejection patients

BACKGROUND

T cell immunoglobulin and mucin domain 3 (TIM-3) is involved in alloimmune and autoimmune responses, as well as tolerance induction in kidney transplantation. Kidney injury molecule-1 (KIM-1) is highly expressed in epithelial cells of the injured proximal tubule. In this study, we have investigated both urinary and blood TIM-3 mRNA expressions, urinary KIM-1 mRNA expression, and urinary and serum KIM-1 proteins in renal allograft recipients diagnosed with acute allograft rejection (AR) and chronic allograft dysfunction (CAD), as well as those with well-functioning transplants (WFG).

METHODS

We divided 85 patients into the following groups: AR (n=24), CAD (n=19), and WFG (n=42). TIM-3 and KIM-1 mRNA expressions were quantified using real-time reverse-transcription TaqMan probe polymerase chain reaction (RT-PCR). An ELISA test was used to measure the amount of KIM-1 protein in serum and urine samples.

RESULTS

AR and CAD patients had significantly greater urinary and blood TIM-3 mRNA expressions, urinary KIM-1 mRNA expression, and urinary and serum KIM-1 proteins compared to WFG patients. Receiver operating characteristic (ROC) analysis showed that these molecules discriminated Allograft rejections from WFG.

CONCLUSION

Quantification of TIM-3 and KIM-1 mRNA expressions, along with KIM-1 protein measurements in urine and blood could be employed as promising tools for noninvasive diagnosis of allograft dysfunction.

[Evaluation of markers for renal graft dysfunction in patients with type 1 diabetes mellitus after kidney transplantation and simultaneous pancreas-kidney transplantation]

AIM

To study the markers of renal graft dysfunction in patients with type 1 diabetes mellitus (T1DM) after kidney transplantation (KT) and simultaneous pancreas-kidney transplantation (SPKT).

SUBJECTS AND METHODS

The investigation enrolled 20 patients after successful SPKT and 41 patients after KT (of them 21 received continuous subcutaneous insulin infusion with an insulin doser; 20 had multiple insulin injections). The periods after KT and SPKT at patient inclusion were 8 (7; 8) and 11 (8; 18) months, respectively. A control group comprised 15 patients with T1DM without diabetic nephropathy. The patients were matched for gender, age, and T1DM duration. At a 9-month follow-up, the main biomarkers of kidney graft dysfunction were identified using the standard kits: Cystatin C (Cys C; serum; urine), NGAL, KIM-1, Podocin, Nephrin, IL-18, MMP-9 (urine), TGF-β1, VEGF-A, and Osteopontin (OPN; serum). Fasting blood was taken; a morning urinary portion was examined.

RESULTS

The posttransplantation glomerular filtration rate (GFR) in the patients corresponded to Stage C2; albuminuria did to Category A1 chronic kidney disease. Despite successful SPKT in the group of patients with T1DM, as in that of patients after isolated KT, there was a statistically significant increase in the level of kidney dysfunction markers (Cys C, NGAL, Podocin, and OPN) versus the control group regardless of the compensation for glucose metabolism. compensation. It was found that the level of Cys C was high and correlated negatively with GFR (r=-0.36; p<0.05) and positively with the level of albuminuria (r=0.40; p<0.05). There was also a direct correlation of urinary podocin concentrations with blood creatinine levels (r=0.35; p<0.05) and that of NGAL with albuminuria (r=0.35; p<0.05) in recipients after transplantation.

CONCLUSION

The high levels of biomarkers for kidney graft dysfunction in the examinees (including subjects after SPKT) reflect the persistence of graft microstructural injuries in clinically stable function.

Ectopic Adipose Tissue Storage in the Left and the Right Renal Sinus is Asymmetric and Associated With Serum Kidney Injury Molecule-1 and Fibroblast Growth Factor-21 Levels Increase

OBJECTIVE

A potential mechanism by which obesity could promote hypertension and kidney diseases is through accumulation of adipose tissue in the renal sinus (RS). The aim of the study was to quantify RS and abdominal adipose tissue volumes and to evaluate serum kidney injury molecule (sKIM)-1 and fibroblast growth factor (FGF)-21 association with different adipose tissue compartments.

METHODS

The cross-sectional study included 280 and follow-up study-40 asymptomatic participants; aged 38.30±4.10. For all study participants computed tomography examination was performed, sKIM-1 and FGF-21 levels were measured.

RESULTS

The results indicated asymmetrical deposition of adipose tissue into the RS even after corresponding kidney volume adjustment. The cross-sectional and the follow-up studies showed that sKIM-1 level was positively associated with RS adipose tissue volume increase for both genders. FGF-21 was positively associated with RS and retroperitoneal adipose tissue amount.

CONCLUSIONS

Regardless of gender adipose tissue in RS accumulates asymmetrically-the left RS accumulates a significantly higher amount of adipose tissue. Thus, primarily RS adipose tissue effects should be assessed on the left kidney. Accumulation of adipose tissue in the RS is related with the visceral adipose amount, KIM-1 and FGF-21 concentration increase in the blood serum.

Establishment of Simple and Routine Methods in Early Diagnosis of Gentamicin-Induced Kidney Injury Based on a Rat Model

The changes in biomarkers of gentamycin- (GM-) induced kidney injury have been studied by using simple and routine methods and also assessed the efficacy and utility of these routine biomarkers in early diagnosis. Eighty Sprague-Dawley (SD) rats were randomly divided into 4 groups: three experimental groups treated with different GM dosages (4, 20, and 100 mg·kg(-1)) and a control group. The experimental groups were given intramuscular GM injections once daily for 14 days, and the control group was given intramuscular sterile water. Blood and urine samples were collected on treatment days 1, 3, 7, and 14 to test for total protein (TP), albumin (ALB), blood urea nitrogen (BUN), creatinine (CRE), uric acid (UA), pH, specific gravity (SG), proteins (PRO), and cells in urinary sediment. Histopathology and kidney coefficient were performed on excised kidney specimens. The result indicated that serum CRE, BUN, and TP, urine PRO, and urinary hyaline casts and low-transitional epithelium showed an immediate and highly sensitive response to kidney injury, and the combined diagnosis with the above methods could be used in early diagnosis. Particularly, the process of the test was simple and quick, no special equipment, so it is more suit for primary medical institution.

Circulating Organ-Specific MicroRNAs Serve as Biomarkers in Organ-Specific Diseases: Implications for Organ Allo- and Xeno-Transplantation

Different cell types possess different miRNA expression profiles, and cell/tissue/organ-specific miRNAs (or profiles) indicate different diseases. Circulating miRNA is either actively secreted by living cells or passively released during cell death. Circulating cell/tissue/organ-specific miRNA may serve as a non-invasive biomarker for allo- or xeno-transplantation to monitor organ survival and immune rejection. In this review, we summarize the proof of concept that circulating organ-specific miRNAs serve as non-invasive biomarkers for a wide spectrum of clinical organ-specific manifestations such as liver-related disease, heart-related disease, kidney-related disease, and lung-related disease. Furthermore, we summarize how circulating organ-specific miRNAs may have advantages over conventional methods for monitoring immune rejection in organ transplantation. Finally, we discuss the implications and challenges of applying miRNA to monitor organ survival and immune rejection in allo- or xeno-transplantation.

Serum Cytokines as Biomarkers in Islet Cell Transplantation for Type 1 Diabetes

Background

Islet cell transplantation holds a potential cure for type 1 diabetes, but many islet recipients do not reach long-lasting insulin independence. In this exploratory study, we investigated whether serum cytokines, chemokines and adipokines are associated with the clinical outcome of islet transplantation.

Methods

Thirteen islet transplant patients were selected on basis of good graft function (reaching insulin independence) or insufficient engraftment (insulin requiring) from our cohort receiving standardized grafts and immune suppressive therapy. Patients reaching insulin independence were divided in those with continued (>12 months) versus transient (<6 months) insulin independence. A panel of 94 proteins including cytokines and adipokines was measured in sera taken before and at one year after transplantation using a validated multiplex immunoassay platform.

Results

Ninety serum proteins were detectable in concentrations varying markedly among patients at either time point. Thirteen markers changed after transplantation, while another seven markers changed in a clinical subpopulation. All other markers remained unaffected after transplantation under generalized immunosuppression. Patterns of cytokines could distinguish good graft function from insufficient function including IFN-α, LIF, SCF and IL-1RII before and after transplantation, by IL-16, CCL3, BDNF and M-CSF only before and by IL-22, IL-33, KIM-1, S100A12 and sCD14 after transplantation. Three other proteins (Leptin, Cathepsin L and S100A12) associated with loss of temporary graft function before or after transplantation.

Conclusions

Distinct cytokine signatures could be identified in serum that predict or associate with clinical outcome. These serum markers may help guiding patient selection and choice of immunotherapy, or act as novel drug targets in islet transplantation.

Kidney injury molecule-1 expression in human kidney transplants with interstitial fibrosis and tubular atrophy

Background

Kidney injury molecule-1 (KIM-1) is expressed in tubular epithelial cells after injury and may have a role in the development of renal graft fibrosis. In this study we evaluated the molecular and protein expressions of KIM-1 in dysfunctional allografts and also mRNA KIM-1 expression in urine as potential biomarkers of graft fibrosis.

Methods

Protein and mRNA levels in renal tissue and urinary sediment cells of 69 kidney transplant recipients that undertook for-cause graft biopsies were evaluated by immunohistochemistry and real-time polymerase chain reaction. The histopathology was classified according to the 2007 Banff schema.

Results

KIM-1 protein expression was increased in biopsies with interstitial fibrosis and tubular atrophy (IF/TA) compared with biopsies showing acute calcineurin inhibitor nephrotoxicity (CIN) (P <0.05). Kidney tissue KIM-1 mRNA signaling (in) was increased in biopsies with IF/TA compared with all other groups (P <0.05). In the urine cells KIM-1 mRNA was also increased in patients with IF/TA compared with patients with acute CIN (P <0.05). Significant correlations were found between KIM-1 protein and mRNA levels in tissue, between mRNA expressions in tissue and urine and between protein tissue expression and gene expression in the urine.

Conclusions

KIM-1 seems to be a marker of kidney graft fibrosis. Urinary KIM-1 mRNA may become a useful non-invasive biomarker of the injuries that can trigger intra-graft fibrotic processes, such as interstitial fibrosis and tubular atrophy.

Does the kidney injury molecule-1 predict cisplatin-induced kidney injury in early stage?

BACKGROUND

It is not possible to diagnose acute kidney injury (AKI) in early stages with traditional biomarkers. Kidney injury molecule-1 (KIM-1) is a novel biomarker promising the diagnosis of AKI in early stages. We studied whether urinary and serum KIM-1 (KIM-1 U and KIM-1 S ) concentrations were useful in predicting cisplatin-induced AKI in early stages.

METHODS

We prospectively analysed 22 patients on cisplatin treatment. KIM-1 S and KIM-1 U concentrations were assessed in the samples of the patients on four different time periods (before treatment [BT], first [AT1], third [AT3] and fifth [AT5] day after treatment).

RESULTS

KIM-1 U concentrations on the first day after cisplatin treatment in patients with AKI were significantly increased compared to both KIM-1 U concentrations of the same patients BT (P=0.009) and to AT1-KIM-1 U concentrations of the patients without AKI (P=0.008). A receiver operating characteristic analysis revealed that AT1-KIM-1 U concentrations may predict AKI with an 87.5% sensitivity and 93.3% specificity (area under the curve=0.94). KIM-1 S concentrations were not significantly changed between BT and AT periods.

CONCLUSIONS

KIM-1 U concentrations may predict cisplatin-induced AKI in early stages with high sensitivity and specificity.

Through a glass darkly: seeking clarity in preventing late kidney transplant failure

A common lament is that long-term kidney transplant outcomes remain the same despite improvements in early graft survival. To be fair, progress has been made-in both our understanding of chronic injury and modestly, graft survival. However, we are still a long way from actually solving this important and difficult problem. In this review, we outline recent data supporting the existence of several causes of renal allograft loss, the incidences of which peak at different time points after transplantation. On the basis of this broadened concept of chronic renal allograft injury, we examine the challenges of clinical trial design in long-term studies, including the use of surrogate end points and biomarkers. Finally, we suggest a path forward that, ultimately, may improve long-term renal allograft survival.

KIM-1 and NGAL as biomarkers of nephrotoxicity induced by gentamicin in rats

Gentamicin is a member of aminoglycosides, which has represented highly effective antimicrobial agents especially in Gram-negative infections despite their toxic effects in the kidney. Rapid diagnosis is vital to preserve renal function and to slow down renal injury. Owing to the poor sensitivity and specificity of serum creatinine (SCr) and blood urea nitrogen (BUN), new biomarkers for earlier and more accurate detection are needed. The aim of our study was to determine whether kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) may be useful biomarkers in the assessment of gentamicin-induced nephrotoxicity in rats. In this study, the two biomarkers of renal toxicity were assessed via ELISA, quantitative real-time PCR, and immunohistochemistry in rats treated with gentamicin for up to 7 days. Repeated administration of gentamicin to male SD rats for 1, 3, or 7 days resulted in a dose- and time-dependent increase in the expression of KIM-1 and NGAL. Changes in gene and protein expressions were found to correlate with the progressive histopathological alterations and preceded effects on traditional clinical parameters indicative of impaired kidney function. Both of the biomarkers are supported to be used as sensitive indicators of acute kidney injury caused by gentamicin.