Tim-1-Fc suppresses chronic cardiac allograft rejection and vasculopathy by reducing IL-17 production

Previously, we demonstrated that Tim-1-Fc prevents acute cardiac graft rejection by inhibiting Th1 response. In the present report, we tackled the impact of Tim-1-Fc on Th17 cells in a model of cardiac chronic rejection. Administration of Tim-1-Fc did not result in a detectable impact on innate immunity and regulatory T cells, while it provided protection for Bm12-derive cardiac grafts against chronic rejection in B6 recipients, as manifested by the reduction of inflammatory infiltration along with less severity of vasculopathy. Studies in T-bet(-/-) recipients by implanting Bm12-derived cardiac grafts further revealed that Tim-1-Fc significantly protected cardiac grafts from chronic rejection along with attenuated production of IL-17 producing T cells. Depletion of CD4 and CD8 T cells or blockade of IL-17 in T-bet(-/-) recipients demonstrated that Tim-1-Fc selectively suppresses Th17 differentiation along with attenuated IL-17 secretion. Together, our data suggest that Tim-1-Fc protects cardiac grafts from chronic rejection by suppressing CD4 Th17 development and functionality. Therefore, Tim-1-Fc might be a potential immunosuppressive agent in the setting of cardiac transplantation.

Diagnostic value of urinary kidney injury molecule 1 for acute kidney injury: a meta-analysis

Background

Urinary Kidney Injury Molecule 1 (KIM-1) is a proximal tubular injury biomarker for early detection of acute kidney injury (AKI), with variable performance characteristics depending on clinical and population settings.

Methods

Meta-analysis was performed to assess the diagnostic value of urinary KIM-1 in AKI. Relevant studies were searched from MEDLINE, EMBASE, Pubmed, Elsevier Science Direct, Scopus, Web of Science, Google Scholar and Cochrane Library. Meta-analysis methods were used to pool sensitivity and specificity and to construct summary receiver operating characteristic (SROC) curves.

Results

A total of 2979 patients from 11 eligible studies were enrolled in the analysis. Five prospective cohorts, two cross-sectional and four case-control studies were identified for meta-analysis. The estimated sensitivity of urinary KIM-1 for the diagnosis of AKI was 74.0% (95% CI, 61.0%–84.0%), and specificity was 86.0% (95% CI, 74.0%–93.0%). The SROC analysis showed an area under the curve of 0.86(0.83–0.89). Subgroup analysis suggested that population settings and detection time were the key factors affecting the efficiency of KIM-1 for AKI diagnosis.

Limitation

Various population settings, different definition of AKI and Serum creatinine level used as the standard might have influence on AKI diagnosis. The relatively small number of studies and heterogeneity between them also affected the evaluation.

Conclusion

Urinary KIM-1 may be a promising biomarker for early detection of AKI with considerable predictive value, especially for cardiac surgery patients, and its potential value needs to be validated in large studies and across a broader scope of clinical settings.

Kidney injury molecule-1: a translational journey

Kidney injury molecule-1 (KIM-1, also named TIM-1 and HAVCR-1) was identified as the most highly upregulated protein in the proximal tubule of the kidney after injury. This protein is present with injury in multiple species including man, and also after a large number of acute and chronic insults to the kidney. It is a type-1 membrane protein whose ectodomain is released into the lumen of the tubule. The ectodomain is heavily glycosylated and stable and appears in the urine after injury. It has been qualified by the United States Food and Drug Administration and the European Medicines Agency for preclinical assessment of nephrotoxicity and on a case-by-case basis for clinical evaluation. As a biomarker in humans, its utility has been demonstrated in acute and chronic injury and in renal cell carcinoma, a condition similar to injury, where there is dedifferentiation of the epithelial cell. KIM-1 is a phosphatidylserine receptor which recognizes apoptotic cells directing them to lysosomes. It also serves as a receptor for oxidized lipoproteins and hence is important for uptake of components of the tubular lumen which may be immunomodulatory and/or toxic to the cell. KIM-1 is unique in being the first molecule, not also present on myeloid cells, that transforms kidney proximal epithelial cells into semi-professional phagocytes. Data suggest that KIM-1 expression is protective during early injury, whereas in chronic disease states, prolonged KIM-1 expression may be maladaptive and may represent a target for therapy of chronic kidney disease.

Reference intervals for urinary renal injury biomarkers KIM-1 and NGAL in healthy children

AIM

The aim of this study was to establish reference intervals in healthy children for two novel urinary biomarkers of acute kidney injury, kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL).

MATERIALS & METHODS

Urinary biomarkers were determined in samples from children in the UK (n = 120) and the USA (n = 171) using both Meso Scale Discovery (MSD) and Luminex-based analytical approaches.

RESULTS

95% reference intervals for each biomarker in each cohort are presented and stratified by sex or ethnicity where necessary, and age-related variability is explored using quantile regression. We identified consistently higher NGAL concentrations in females than males (p < 0.0001), and lower KIM-1 concentrations in African-Americans than Caucasians (p = 0.02). KIM-1 demonstrated diurnal variation, with higher concentrations in the morning (p < 0.001).

CONCLUSION

This is the first report of reference intervals for KIM-1 and NGAL using two analytical methods in a healthy pediatric population in both UK and US-based populations.

Acute kidney injuries induced by various irrigation pressures in rat models of mild and severe hydronephrosis

OBJECTIVE

To clarify whether tolerance to irrigation pressure could be modified over varying degrees of kidney obstruction during the endoscopic treatment of kidney stones in a rat model.

METHODS

A total of 126 rats were randomly allocated into 2 experimental groups and a control group. The experimental groups underwent a surgical procedure to induce mild (group M, n = 60) or severe (group S, n = 60) hydronephrosis. In each group, the rats were then randomly allocated into 4 subgroups (M0 to M3 and S0 to S3) of respectively 6, 18, 18, and 18 rats. Groups 0 to 3 were respectively perfused with 0 (no irrigation), 20, 60, and 100 mm Hg pressure fluid. The control group underwent no surgical procedures and was only perfused with 100 mm Hg pressure fluid. Acute kidney injuries were assessed by analyzing the kidney microstructure, tubular cell apoptosis, kidney injury molecule-1, and cysteine-rich 61 (Cyr61/CCN1) expression using immunohistochemistry.

RESULTS

No abnormalities were observed for the control group, groups 0, or 1. In group 2, abnormalities were observed only in the S group, whereas all kidneys in group 3 suffered acute kidneys injuries, along with occurrence of tubular cells necrosis, increased apoptosis, and increased expression of kidney injury molecule-1 and Cyr61.

CONCLUSION

Rats with severely obstructed kidneys were more likely to suffer acute kidney injuries than those with less obstructed kidneys when exposed to higher kidney irrigation pressures. This suggests that the pressure should be controlled and reduced when performing endourologic procedures in the context of kidney obstruction.

Urinary biomarkers and renal near-infrared spectroscopy predict intensive care unit outcomes after cardiac surgery in infants younger than 6 months of age

OBJECTIVE

To assess the ability of urinary acute kidney injury biomarkers and renal near-infrared spectroscopy (NIRS) to predict outcomes in infants after surgery for congenital heart disease.

METHODS

Urinary levels of neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), kidney injury molecule-1 (KIM-1), and cystatin C were measured preoperatively and postoperatively in 49 infants younger than 6 months of age. Renal NIRS was monitored for the first 24 hours after surgery. A composite poor outcome was defined as death, the need for renal replacement therapy, prolonged time to first extubation, or prolonged intensive care unit length of stay.

RESULTS

Forty-two (86%) patients had acute kidney injury as indicated by at least Acute Kidney Injury Network/Kidney Disease: Improving Global Outcomes (AKIN/KDIGO) stage 1 criteria, and 17 (35%) patients had poor outcomes, including 3 deaths. With the exception of KIM-1, all biomarkers demonstrated significant increases within 24 hours postoperatively among patients with poor outcomes. Low levels of NGAL and IL-18 demonstrated high negative predictive values (91%) within 2 hours postoperatively. Poor outcome infants had greater cumulative time with NIRS saturations less than 50% (60 vs 1.5 minutes; P = .02) in the first 24 hours.

CONCLUSIONS

Within the first 24 hours after cardiopulmonary bypass, infants at increased risk for poor outcomes demonstrated elevated urinary NGAL, IL-18, and cystatin C and increased time with low NIRS saturations. These findings suggest that urinary biomarkers and renal NIRS may differentiate patients with good versus poor outcomes in the early postoperative period, which could assist clinicians when counseling families and inform the development of future clinical trials.

Biomarkers of acute kidney injury in pediatric cardiac surgery

OBJECTIVES

Acute kidney injury (AKI) is a significant problem in children undergoing cardiopulmonary bypass (CPB). The aims of this study were to assess the diagnostic validity of serum CysC (sCysC), serum neutrophil gelatinase lipocalin (sNGAL), urine neutrophil gelatinase lipocalin (uNGAL), urine kidney injury molecule (uKIM)-1, and urine liver fatty acid-binding protein (uL-FABP) to predict AKI presence and severity in children undergoing CPB.

DESIGN AND METHODS

We performed a prospective single-center evaluation of sCysC, sNGAL, uNGAL, uKIM-1 and uL-FABP at 0, 2, 6, 24 and 48 h postoperatively in children undergoing CPB during cardiac surgery. AKI was defined as ≥25% decrease in the estimated creatinine clearance (eCCl) from pre-operative baseline at 48h after surgery.

RESULTS

Of the 112 patients, 18 patients (16.1%) developed AKI; four of them needed acute dialysis treatment and three AKI patients died. In the AKI compared to the non-AKI group, sCysC at 2h, and uNGAL and uL-FABP at 2-48 h were significantly increased, as well as CPB, aortic cross clamp time and length of hospital stay. Biomarkers increased with worsening AKI severity. At 2h after CPB the best accuracy for diagnosis of AKI had uL-FABP and sCysC with area under the receiver operator curve (AUC) of 0.89 and 0.73, respectively. At 6 and 24h after CPB the best AUC was found for uL-FABP (0.75 and 0.87 respectively) and for uNGAL (0.70 and 0.93, respectively).

CONCLUSIONS

sCysC, uNGAL and uL-FABP are reliable early predictors for AKI after CPB. By allowing earlier timing of injury and earlier intervention, they could improve AKI outcome.

[Prevention of contrast-induced nephropathy in the context of evidence-based medicine]

The paper considers the mechanisms of development of contrast-induced nephropathy in the use of iodinated radiopaque contrast agents (RCAs), as well as the criteria of their assessment. It gives different existing recommendations for prevention of the nephrotoxic effects of RCAs.

Review and discussion of tubular biomarkers in the diagnosis and management of diabetic nephropathy

The prevalence of diabetic nephropathy has tremendously increased with the relentless rise in the incidence of diabetes over the last couple decades. Diabetic nephropathy is a leading cause of morbidity and mortality, and it invariably leads to an end-stage renal disease (ESRD). In an effort to delay the onset of ESRD systematic screening and appropriate management are needed to evaluate the progression of renal damage in diabetic nephropathy. The reliability of current tests in predicting the onset, progression and response to various regimens for diabetic nephropathy is still under debate; and it has engendered a search for more sensitive and specific urinary biomarkers, especially those reflective of tubular dysfunctions. It is well-known that there is a good correlation between the degree of damage to the tubulo-interstitial compartment and the deterioration of renal functions. In view of this, the utility of urinary biomarkers, reflective of tubular injury, reported in the literature is discussed in this brief review.

Current developments in early diagnosis of acute kidney injury

Acute kidney injury (AKI) is a very frequent and serious clinical problem, accounting for overall high morbidity and mortality. Up to date, mortality due to AKI is virtually unchanged over the past 50 years. This may partly be explained due to a delay in initiating renal protective and appropriate therapeutic measures since until now there are no reliable early-detecting biomarkers. The gold standard, serum creatinine, displays poor specificity and sensitivity with regard to identification of the incipient phase of AKI, and this is also true for cystatin C. We aimed to review novel biomarkers of AKI in urine and serum which have now progressed to the clinical phase. The main focus refers to their diagnostic and prognostic value. For this purpose, a web-based literature search using PubMed was performed comprising the following terms: renal failure, acute kidney injury and biomarkers. New molecules such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), N-acetyl-β-D-glucosaminidase (NAG), monocyte chemotactic peptide (MCP-1), Il-18, liver-type fatty acid-binding protein (L-FABP) and Netrin-1 are available and represent promising new markers that, however, need to be further evaluated in the clinical setting for suitability. In clinical settings with incipient AKI, not only the development and the implementation of more sensitive, practicable and accurate biomarkers are required for well-timed treatment initiation. Just as important is a substantial improvement of refined and applicable prophylactic therapeutic options in these situations. Before full adoption in clinical practice can be accomplished, adequately powered clinical trials testing a row of biomarkers are strongly warranted.

Noninvasive analyses of kidney injury molecule-1 messenger RNA in kidney transplant recipients with graft dysfunction

BACKGROUND

Kidney graft fibrosis is a major factor related to chronic loss of kidney function. At present, the finding of fibrosis depends on the analysis of tissue in the renal biopsy, which has important limitations. In this study, we evaluated the messenger mRNA transcription and gene expression of kidney injury molecule-1 (KIM-1) in kidney tissue and in urinary sediment cells of kidney transplant patients with graft dysfunction aiming at the development of techniques that may allow the noninvasive diagnosis of interstitral fibrosis/tubular atrophy (IF/TA).

PATIENTS AND METHODS

RNA extracted from cells in tissue and urine of 77 renal transplant patients whose biopsies were classified according to the Banff scheme-2007. Four diagnostic groups were established: (1) acute tubular necrosis (n = 9); (2) acute rejection (n = 49); (3) acute calcineurin inhibitors nephrotoxicity (n = 10); and (4) interstitial fibrosis and tubular atrophy (IFTA, n = 29). Tissue and urine cell RNA was amplified and quantification were made by real-time polymerase chain reactron. Data from the quantification of gene expression are presented as median and 25th to 75th percentiles.

RESULTS

Messenger RNA levels of the KIM-1 gene were higher in the biopsies (26.17; 3.38-294.53) and urinary sediment cells (0.09; 0-5.81) of the patients classified as having IF/TA as compared with all others groups. A significant correlation between gene expression in samples of urine and tissue cells was found (P < .01).

CONCLUSION

These initial data suggests that KIM-1 gene mRNA quantification can be used as a noninvasive biomarker of IF/TA.

Diabetic nephropathy: traditional to proteomic markers

Diabetic nephropathy (DN) is one of the major microvascular complications of diabetes and it is defined as a rise in the urinary albumin excretion (UAE) rate and abnormal renal function. Currently, changes in albuminuria are considered a hallmark of onset or progression of DN. However, some patients with diabetes have advanced renal pathological changes and progressive kidney function decline even if urinary albumin levels are in the normal range, indicating that albuminuria is not the perfect marker for the early detection of DN. The present article provides an overview of the literature reporting some relevant biomarkers that have been found to be associated with DN and that potentially may be used to predict the onset and/or monitor the progression of nephropathy. In particular, biomarkers of renal damage, inflammation, and oxidative stress may be useful tools for detection at an early stage or prediction of DN. Proteomic-based biomarker discovery represents a novel strategy to improve diagnosis, prognosis and treatment of DN; however, proteomics-based approaches are not yet available in most of the clinical chemistry laboratories. The use of a panel with a combination of biomarkers instead of urinary albumin alone seems to be an interesting approach for early detection of DN, including markers of glomerular damage (e.g., albumin), tubular damage (e.g., NAG and KIM-1), inflammation (e.g., TNF-α) and oxidative stress (e.g., 8-OHdG) because these mechanisms contribute to the development and outcomes of this disease.

Molecular markers for ischemia, do we have something better then creatinine and glomerular filtration rate?

Acute kidney injury (AKI) can occur spontaneously or iatrogenically, and rates of AKI continue to rise over the last two decades despite improvements in clinical care and development of preventive strategies. Serum creatinine (sCr) is the current gold standard for measuring changes in kidney function and identifying AKI. Detection of AKI by sCr, however, is delayed and small rises connote significantly increased morbidity and mortality. Diagnosis of AKI by sCr is therefore likely too late to prevent some of the early structural changes that characterize renal injury. Several urinary biomarkers including neutrophil gelatinase-associated lipocalin (NGAL), N-acetyl-β-D-glucosaminidase (NAG), Interleukin-18 (IL-18), kidney injury molecule-1 (KIM-1), liver fatty-acid-binding protein (L-FABP), and cystatin-C, have shown an ability to predict AKI days before an elevation in sCr, and a few even seem to predict AKI-related morbidity and mortality better than sCr alone. A review of the current literature regarding these biomarkers reveals that they individually have unique strengths and weaknesses that can provide different types of information about patients. Currently, NGAL is the urine biomarker with the most promise as an individual marker. However, combining multiple markers to form a 'biomarker panel' along with sCr is an improvement over current clinical risk prediction models alone, and may be able to provide more individualized detail about the type and location of renal injury.

[Early markers of acute kidney injury in newborns]

The incidence of acute kidney injury (AKI) at neonatal intensive care units (NICU) is estimated as 6-24%. Traditional AKI markers i.e. serum creatinine (SCr) concentration, fractional sodium exertion, urine sodium concentration and renal failure index--are low sensitivity and low specificity markers but beside remain very late ones. Serum creatinine concentration arises 48 hours after renal tissue damage. The paper presents contemporary knowledge concerning concentration reference ranges of some early AKI biomarkers (NGAL, hKIM1, OPN, IL18)--either in term or preterm newborns. The most current reports about chosen AKI biomarkers in newborns with uncomplicated clinical course and in children with AKI within the course of sepsis or after cardiopulmonary bypass surgery--were discussed. Disposing of the reliable clinical data referring to early AKI biomarkers constitutes a valuable aid for clinicians who having got to know about the actual risk possess the time for proper clinical interventions.

HAVcR-1 expression in human colorectal cancer and its effects on colorectal cancer cells in vitro

BACKGROUND

Hepatitis A virus cellular receptor 1 (HAVcR-1) may function as part of the regulatory apparatus for tight junction in human endothelial cells, and is overexpressed in renal cell and ovarian clear cell carcinomas.

MATERIALS AND METHODS

HAVcR-1 expression in colorectal cancer and matched background tissues was determined using quantitative-PCR. HAVcR-1 was overexpressed in three colorectal cancer cell lines and the effect of this overexpression was assessed by changes in cell behaviour.

RESULTS

HAVcR-1 expression was increased in colorectal cancer (p<0.001) and the disease-free time of patients with high levels of HAVcR-1 expression was significantly longer (p=0.045). HAVcR-1 overexpression reduced colorectal cancer cell adhesion and invasion (p<0.016).

CONCLUSION

HAVcR-1 overexpression may be a diagnostic biomarker for colorectal cancer and a prognostic marker for a longer disease-free interval after surgery for colorectal cancer. HAVcR-1 overexpression can reduce cell adhesion and invasion and could thus be involved in the metastatic cascade.

Chronic renal allograft damage after transplantation: what are the reasons, what can we do?

PURPOSE OF REVIEW

Chronic renal allograft damage is one of the main problems after kidney transplantation. This review enumerates causes, describes available therapeutic options, and discusses options of the future.

RECENT FINDINGS

Alloantigen-dependent and alloantigen-independent factors are responsible for allograft damage. Prevention of renal allograft damage starts with interventions that occur surrounding the explantation in cadaveric organs. These include the use of dopamine or machine perfusion systems.Followed by the critical phase of ischemia/reperfusion injury, the LCN2/lipocalin-2, HAVCR1, and p38 MAPK pathway are new players involved in that process. Innate immunity plays a part, too. Cold ischemia time is associated with genes of apoptosis. Nondonor-specific antibodies like antihuman leukocyte antibodies-Ia or angiotensin type 1 receptor may also play a role. Recent research indicates that genetic polymorphism like the Ficolin-2 Ala258Ser polymorphism and the mannose-binding lectin-2 polymorphism are involved in that process. New therapeutic options are rare and in the future. However, there is some evidence that drugs interfering with metalloproteinases, sexual hormones like dihydroandrosterone, and mesenchymal stem cell therapy may be of importance.

SUMMARY

Taken together, although the understanding of chronic rejection has improved, the available therapeutic options remain scarce.

[Clinical study of kidney injury molecule-1 in the treatment of sepsis patients]

OBJECTIVE

To investigate the relationship between kidney injury molecule-1 (KIM-1) in urine and acute physiology and chronic health evaluation II (APACHEII) score, and the prognosis in the patients suffered from sepsis.

METHODS

In the perspective study, 56 patients in intensive care unit (ICU) from March 2010 to September 2011 suffered from sepsis were enrolled and treated according to the early goal-directed therapy (EGDT). The patients were divided into two groups according to the perform in EGDT or not within 6 hours (groupI, group II). Monitoring included APACHEII score, KIM-1, blood urea nitrogen (BUN) and creatinine (Cr) at before resuscitation (T0), 6 hours after resuscitation (T6 h), and 1 day (T1 d), 2 days (T2 d), 3 days (T3 d), 4 days (T4 d) and 5 days (T5 d) after ICU admission. According to the 28-day prognosis, all the patients were divided into survival group or death group.

RESULTS

The value of APACHEII score, urine KIM-1, BUN and Cr in groupI(n=30), decreased after fluid resuscitation and decreased to the lowest at T5 d. The value of APACHEII score, urine KIM-1, BUN and Cr in groupII(n=26), increased after failure of fluid resuscitation and increased to the highest at T5 d. The value of APACHEII score at T2 d and urine KIM-1 at T1 d in groupII were significantly higher than those in groupI (APACHEII score: 26.35±6.18 vs. 13.25±4.72, urine KIM-1: 4.721±1.432 μg/L vs. 0.909±0.325 μg/L, both P<0.05). The mortality in groupI was significantly lower than that in group II [10.0% (3/30) vs. 73.1% (19/26), P<0.05]. The value of APACHEII score, urine KIM-1, BUN and Cr in survival group (n=34) decreased with the clinical condition improved and decreased to the lowest at T5 d, while the value of APACHEII score, urine KIM-1, BUN and Cr in death group (n=22) increased and increased to the highest at T5 d. The value of APACHEII score at T1 d, and urine KIM-1 at T6 d in death group were significantly higher than those in survival group (APACHEII score:26.39±8.95 vs. 14.27±5.11, urine KIM-1:3.134±1.117 μg/L vs. 1.447±0.472 μg/L, both P<0.05).

CONCLUSIONS

KIM-1 in urine could be a good index for evaluation of sepsis, and it is helpful to understand the disease development by continuous surveillance. It is very important for the appraisal of prognosis, development and prognosis in sepsis, combined with APACHEII score.

Analytical and biological validation of a multiplex immunoassay for acute kidney injury biomarkers

BACKGROUND

Acute kidney injury (AKI) is a dynamic process that can involve inflammatory, hypoxic, and structural changes to the kidney. We evaluated a multiplex panel of markers representing different AKI mechanisms as a tool to provide integrated assessment of AKI status in a single assay.

METHODS

Urinary cystatin C (CysC), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1) and interleukin-18 (IL-18) were measured by multiplex electrochemiluminescence immunoassay. Analytical performance was compared to the biological and pathological variation of these markers in human samples.

RESULTS

Linearity was established over a 3- to 4-log range for all markers, which spanned the reference ranges established from healthy donors. Imprecision was below 15%, comparing favorably with the observed biological variation of these markers. Control patients fell within donor-derived reference ranges for most markers, but a subset of patients showed CysC and KIM-1 elevations in the absence of documented AKI.

CONCLUSION

The multiplex assay is reliable for simultaneous quantitation of CysC, IL-18, KIM-1 and NGAL in human urine, and performs at levels sufficient for clinical application. The observed differences in biological variability and baseline levels suggest that clinical strategies to detect AKI will need to vary depending upon the specific markers used.

Kidney injury molecule-1 is up-regulated in renal epithelial cells in response to oxalate in vitro and in renal tissues in response to hyperoxaluria in vivo

Oxalate is a metabolic end product excreted by the kidney. Mild increases in urinary oxalate are most commonly associated with Nephrolithiasis. Chronically high levels of urinary oxalate, as seen in patients with primary hyperoxaluria, are driving factor for recurrent renal stones, and ultimately lead to renal failure, calcification of soft tissue and premature death. In previous studies others and we have demonstrated that high levels of oxalate promote injury of renal epithelial cells. However, methods to monitor oxalate induced renal injury are limited. In the present study we evaluated changes in expression of Kidney Injury Molecule-1 (KIM-1) in response to oxalate in human renal cells (HK2 cells) in culture and in renal tissue and urine samples in hyperoxaluric animals which mimic in vitro and in vivo models of hyper-oxaluria. Results presented, herein demonstrate that oxalate exposure resulted in increased expression of KIM-1 m RNA as well as protein in HK2 cells. These effects were rapid and concentration dependent. Using in vivo models of hyperoxaluria we observed elevated expression of KIM-1 in renal tissues of hyperoxaluric rats as compared to normal controls. The increase in KIM-1 was both at protein and mRNA level, suggesting transcriptional activation of KIM-1 in response to oxalate exposure. Interestingly, in addition to increased KIM-1 expression, we observed increased levels of the ectodomain of KIM-1 in urine collected from hyperoxaluric rats. To the best of our knowledge our studies are the first direct demonstration of regulation of KIM-1 in response to oxalate exposure in renal epithelial cells in vitro and in vivo. Our results suggest that detection of KIM-1 over-expression and measurement of the ectodomain of KIM-1 in urine may hold promise as a marker to monitor oxalate nephrotoxicity in hyperoxaluria.

Mechanism-based urinary biomarkers to identify the potential for aminoglycoside-induced nephrotoxicity in premature neonates: a proof-of-concept study

Premature infants are frequently exposed to aminoglycoside antibiotics. Novel urinary biomarkers may provide a non-invasive means for the early identification of aminoglycoside-related proximal tubule renal toxicity, to enable adjustment of treatment and identification of infants at risk of long-term renal impairment. In this proof-of-concept study, urine samples were collected from 41 premature neonates (≤32 weeks gestation) at least once per week, and daily during courses of gentamicin, and for 3 days afterwards. Significant increases were observed in the three urinary biomarkers measured (Kidney Injury Molecule-1 (KIM-1), Neutrophil Gelatinase-associated Lipocalin (NGAL), and N-acetyl-β-D-glucosaminidase (NAG)) during treatment with multiple courses of gentamicin. When adjusted for potential confounders, the treatment effect of gentamicin remained significant only for KIM-1 (mean difference from not treated, 1.35 ng/mg urinary creatinine; 95% CI 0.05–2.65). Our study shows that (a) it is possible to collect serial urine samples from premature neonates, and that (b) proximal tubule specific urinary biomarkers can act as indicators of aminoglycoside-associated nephrotoxicity in this age group. Further studies to investigate the clinical utility of novel urinary biomarkers in comparison to serum creatinine need to be undertaken.

Clinical implication of urinary tubular markers in the early stage of nephropathy with type 2 diabetic patients

AIM

The aim of this study was to evaluate the association of urinary tubular markers, interleukin-18 (IL-18) and angiotensinogen with albuminuria in early nephropathy of type 2 diabetics.

METHODS

Urine levels of tubular markers (kidney injury molecule [KIM]-1, neutrophil gelatinase-associated lipocalin [NGAL] and liver-type fatty acid-binding protein [L-FABP]), proinflammatory marker (IL-18), and a marker of intrarenal renin-angiotensin system (RAS) status (angiotensinogen) were determined in 118 patients with type 2 diabetes mellitus and 25 non-diabetic controls with estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73 m(2).

RESULTS

Urinary levels of KIM-1, NGAL, IL-18 and angiotensinogen were significantly higher in macroalbuminuria group compared with control and normo- and microalbuminuria groups but not significantly different between control and normoalbuminuria group. Urinary tubular markers were positively correlated with urinary IL-18 and angiotensinogen, respectively. The urinary albuminuria was correlated with all investigated urinary markers in univariate analysis. After adjusting for several clinical parameters, urinary KIM-1, NGAL and angiotensinogen were significantly associated with albuminuria.

CONCLUSIONS

The results of this study suggest that urinary tubular markers may be independently associated with albuminuria in the early stage of nephropathy in type 2 diabetics (eGFR ≥ 60 mL/min/1.73 m(2)) and may reflect inflammatory processing and the activation of the intrarenal RAS.

Proximal tubular renal dysfunction or damage in HIV-infected patients

Antiretroviral-associated toxicity, especially in the case of tenofovir plus boosted protease inhibitors, could affect different functions of the proximal renal tubule. Considering the long-term use of antiretroviral therapy and the concomitant presence of other risk factors, several degrees of proximal tubular toxicity, from chronic subclinical renal dysfunction to Fanconi syndrome, could be observed in HIV-infected patients. However, the clinical significance of isolated tubular dysfunction, in the short and long term, remains unclear. In addition, primary tubular abnormalities, even severe, may be missed until they affect the glomerular function. Therefore, there is a need for new biomarkers, not only based in serum creatinine and estimated glomerular filtration rates, that might help to identify tubular cell toxicity and predict the clinical outcome in HIV-infected patients. Increased values of urinary beta-2-microglobulin and retinol-binding protein, observed in up to 70% of patients, have been associated to tenofovir-associated mitochondrial dysfunction. Together with other tubular parameters or in isolation, both biomarkers could be useful for diagnosing proximal tubular toxicity. Other molecules, such as urinary kidney injury molecule- 1, neutrophil gelatinase associated lipocalin, or N-acetyl-b-D-glucosaminidase, could help to distinguish between tubular cell damage and dysfunction. Here, we review the current knowledge on tubular toxicity in HIV-infected patients on antiretroviral therapy.

Acute Kidney Injury (AKI) biomarker

The kidney has a remarkable capacity to withstand insults for an extended period of time. The sensitivities of individual renal cells to injury vary depending on their type, position in the nephron, local vascularization, and the nature of injury. The resulting kidney injury is a product of the interplay between cell dysfunction, cell death, proliferation, inflammation, and recovery. The Acute Kidney Injury Network (AKIN) defined Acute Kidney Injury (AKI) as "functional and structural disorder or signs of renal damage including any defect from blood and urine test, or tissue imaging that is less than 3 months". RIFLE (Risk, Injury, Failure, Loss, End-Stage Kidney Disease) criteria is the most frequently used system. Ideal biomarker for AKI should be affordable, quick and measurable, precise and accurate, with prognostic ability to define severity of renal dysfunction, specific for renal, increase in the early stage dysfunction, with high sensitivity and specificity. Efforts to detect AKI in the earlier stage has resulted in some promising biomarkers such as KIM-1, NGAL, IL-18, Clusterin, etc. Cystatin C is a biomarker for glomerular filtration function, while 2-microglobulin, 1-microglobulin, NAG, RBP, IL-18, NGAL, Netrin-1, KIM-1, Clusterin, Sodium Hydrogen Exchanger Isoform and Fetuin A are biomarkers for tubular reabsorption function.

Binding of hepatitis A virus to its cellular receptor 1 inhibits T-regulatory cell functions in humans

BACKGROUND & AIMS

CD4+ T-regulatory (Treg) cells suppress immune responses and control self-tolerance and immunity to pathogens, cancer, and alloantigens. Most pathogens activate Treg cells to minimize immune-mediated tissue damage and prevent clearance, which promotes chronic infections. However, hepatitis A virus (HAV) temporarily inhibits Treg-cell functions. We investigated whether the interaction of HAV with its cellular receptor 1 (HAVCR1), a T-cell co-stimulatory molecule, inhibits the function of Treg cells to control HAV infection.

METHODS

We studied the effects of HAV interaction with HAVCR1 on human T cells using binding, signal transduction, apoptosis, activation, suppression, cytokine production, and confocal microscopy analyses. Cytokines were analyzed in sera from 14 patients with HAV infection using bead arrays.

RESULTS

Human Treg cells constitutively express HAVCR1. Binding of HAV to HAVCR1 blocked phosphorylation of Akt, prevented activation of the T-cell receptor, and inhibited function of Treg cells. At the peak viremia, patients with acute HAV infection had no Treg-cell suppression function, produced low levels of transforming growth factor-β , which limited leukocyte recruitment and survival, and produced high levels of interleukin-22, which prevented liver damage.

CONCLUSIONS

Interaction between HAV and its receptor HAVCR1 inhibits Treg-cell function, resulting in an immune imbalance that allows viral expansion with limited hepatocellular damage during early stages of infection-a characteristic of HAV pathogenesis. The mechanism by which HAV is cleared in the absence of Treg-cell function could be used as a model to develop anticancer therapies, modulate autoimmune and allergic responses, and prevent transplant rejection.

Kim-1/Tim-1 and immune cells: shifting sands

Kim-1/Tim-1 is an apoptotic-cell phagocytosis and scavenger receptor that is most highly upregulated in proximal tubular epithelium in acute and chronic kidney injury. While Kim-1/Tim-1 has been proposed to be a costimulatory molecule for immune cells, its potential immunological role has been controversial. In the presence of very high epithelial cell expression, understanding the influence of immune cell Kim-1/Tim-1 expression in kidney injury relies on a better definition of its functional significance in immune cells and better characterization of antibodies used to probe function.