Application of antibody array technology in the analysis of urinary cytokine profiles in patients with chronic kidney disease

Urinary Biomarkers and Point-of-Care Urinalysis Devices for Early Diagnosis and Management of Disease: A Review

Biosensing and microfluidics technologies are transforming diagnostic medicine by accurately detecting biomolecules in biological samples. Urine is a promising biological fluid for diagnostics due to its noninvasive collection and wide range of diagnostic biomarkers. Point-of-care urinalysis, which integrates biosensing and microfluidics, has the potential to bring affordable and rapid diagnostics into the home to continuing monitoring, but challenges still remain. As such, this review aims to provide an overview of biomarkers that are or could be used to diagnose and monitor diseases, including cancer, cardiovascular diseases, kidney diseases, and neurodegenerative disorders, such as Alzheimer’s disease. Additionally, the different materials and techniques for the fabrication of microfluidic structures along with the biosensing technologies often used to detect and quantify biological molecules and organisms are reviewed. Ultimately, this review discusses the current state of point-of-care urinalysis devices and highlights the potential of these technologies to improve patient outcomes. Traditional point-of-care urinalysis devices require the manual collection of urine, which may be unpleasant, cumbersome, or prone to errors. To overcome this issue, the toilet itself can be used as an alternative specimen collection and urinalysis device. This review then presents several smart toilet systems and incorporated sanitary devices for this purpose.

Urine-Based Detection of Biomarkers Indicative of Chronic Kidney Disease in a Patient Cohort from Ghana

Chronic kidney disease (CKD) is a global health burden with a continuously increasing prevalence associated with an increasing incidence of diabetes and hypertension in aging populations. CKD is characterized by low glomerular filtration rate (GFR) and other renal impairments including proteinuria, thus implying that multiple factors may contribute to the etiology this disease. While there are indications of ethnic differences, it is hard to disentangle these from confounding social factors. Usually, CKD is detected in later stages of the disease when irreversible renal damage has already occurred, thus suggesting a need for early non-invasive diagnostic markers. In this study, we explored the urine secretome of a CKD patient cohort from Ghana with 40 gender-matched patients and 40 gender-matched healthy controls employing a kidney injury and a more general cytokine assay. We identified panels of kidney-specific cytokine markers, which were also gender-specific, and a panel of gender-independent cytokine markers. The gender-specific markers are IL10 and MME for male and CLU, RETN, AGER, EGFR and VEGFA for female. The gender-independent cytokine markers were APOA1, ANGPT2, C5, CFD, GH1, ICAM1, IGFBP2, IL8, KLK4, MMP9 and SPP1 (up-regulated) and FLT3LG, CSF1, PDGFA, RETN and VEGFA (down-regulated). APOA1-the major component of HDL particles-was up-regulated in Ghanaian CKD patients and its co-occurrence with APOL1 in a subpopulation of HDL particles may point to specific CKD-predisposing APOL1 haplotypes in patients of African descent-this, however, needs further investigation. The identified panels, though preliminary, lay down the foundation for the development of robust CKD-diagnostic assays.

Recent Advances in Biosensor Technologies for Point-of-Care Urinalysis

Human urine samples are non-invasive, readily available, and contain several components that can provide useful indicators of the health status of patients. Hence, urine is a desirable and important template to aid in the diagnosis of common clinical conditions. Conventional methods such as dipstick tests, urine culture, and urine microscopy are commonly used for urinalysis. Among them, the dipstick test is undoubtedly the most popular owing to its ease of use, low cost, and quick response. Despite these advantages, the dipstick test has limitations in terms of sensitivity, selectivity, reusability, and quantitative evaluation of diseases. Various biosensor technologies give it the potential for being developed into point-of-care (POC) applications by overcoming these limitations of the dipstick test. Here, we present a review of the biosensor technologies available to identify urine-based biomarkers that are typically detected by the dipstick test and discuss the present limitations and challenges that future development for their translation into POC applications for urinalysis.

Targeted biomarkers of progression in chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is an increasingly significant health issue worldwide. Early stages of CKD can be asymptomatic and disease trajectory difficult to predict. Not everyone with CKD progresses to kidney failure, where kidney replacement therapy is the only life-sustaining therapy. Predicting which patients will progress to kidney failure would allow better use of targeted treatments and more effective allocation of health resources. Current diagnostic tests to identify patients with progressive disease perform poorly but there is a suite of new and emerging predictive biomarkers with great clinical promise.

METHODS

This narrative review describes new and emerging biomarkers of pathophysiologic processes of CKD development and progression, accessible in blood or urine liquid biopsies. Biomarkers were selected based on their reported pathobiological functions in kidney injury, inflammation, oxidative stress, repair and fibrosis. Biomarker function and evidence of involvement in CKD development and progression are reported.

CONCLUSION

Many biomarkers reviewed here have received little attention to date, perhaps because of conflicting conclusions of their utility in CKD. The functional roles of the selected biomarkers in the underlying pathobiology of progression of CKD are a powerful rationale for advancing and validating these molecules as prognosticators and predictors of CKD trajectory.

Global Detection of Proteins by Label-Based Antibody Array

Because of narrow availability of antibody pairs and potential cross-reactivity between antibodies, the development of sandwich-based antibody arrays which need a pair of antibodies for each target has been restricted to higher density resulting in limited proteomic breadth of detection. Label-based array is one way to overcome this obstacle by directly labeling all targets in samples with fluorescent dyes such as Cy3 and Cy5. The labeled samples are then applied on the antibody array chip composed of capture antibodies. In this chapter, we will introduce this technology including array production and sample detection assay.

Resistant starch supplementation attenuates inflammation in hemodialysis patients: a pilot study

PURPOSE

In chronic kidney disease (CKD) patients, dysbiosis is associated with inflammation and cardiovascular risk, so many nutritional strategies are being studied to reduce these complications. Resistant starch (RS) can be considered a prebiotic that promotes many benefits, including modulation of gut microbiota which is linked to immune-modulatory effects. The aim of this study was to evaluate the effects of RS supplementation on proinflammatory cytokines in CKD patients on hemodialysis (HD).

METHODS

A double-blind, placebo-controlled, randomized trial was conducted with sixteen HD patients (55.3 ± 10.05 years, body mass index (BMI) 25.9 ± 5.42 kg/m², 56% men, time on dialysis 38.9 ± 29.23 months). They were allocated to the RS group (16 g RS/day) or placebo group (manioc flour). The serum concentration of ten cytokines and growth factors was detected through a multiparametric immunoassay based on XMap-labeled magnetic microbeads (Luminex Corp, USA) before and after 4 weeks with RS supplementation.

RESULTS

After RS supplementation, there was a reduction of Regulated upon Activation, Normal T-Cell Expressed and Secreted (p < 0.001), platelet-derived growth factor (two B subunits) (p = 0.014) and interferon-inducible protein 10 (IP-10) (p = 0.027). The other parameters did not change significantly.

CONCLUSION

This preliminary result indicates that RS may contribute to a desirable profile of inflammatory markers in CKD patients.

Analysis of the differential urinary protein profile in IgA nephropathy patients of Uygur ethnicity

Background

IgA nephropathy (IgAN) is one of the most common forms of idiopathic glomerular diseases and might lead to end-stage kidney disease. Accurate and non-invasive biomarkers for early diagnosis are required for early intervention and consequent therapy for IgAN patients. Because variance in the disease incidence and predisposing genes of IgAN has been detected among different ethnicities, the ethnicity factor should be considered in IgAN biomarker discovery. The differences in the protein profiles and pathological mechanisms of IgAN in patients of Uygur ethnicity need to be clearly illustrated.

Methods

In this study, we used urinary proteomics to discover candidate biomarkers of IgAN in patients of Uygur ethnicity. The urinary proteins from Uygur normal control and Uygur IgAN patients were extracted and analyzed using 2D-LC-MS/MS and isobaric tags for relative and absolute quantitation (iTRAQ) analysis.

Results

A total of 277 proteins were found to be differentially represented in Uygur IgAN compared with the respective normal controls. The bioinformatics analysis revealed that the immune response, cell survival, and complement system were activated in Uygur IgAN. Many differentially expressed proteins were found to be related to nephropathy and kidney injuries. Four candidate biomarkers were validated by Western blot, and these results were consistent with the iTRAQ results. ICAM1, TIMP1, SERPINC1 and ADIPOQ were upregulated in Uygur IgAN. Bioinformatic analysis revealed that the increase of ICAM1 and TIMP1 might be caused by IgAN, but the increase of SERPINC1 and ADIPOQ might be caused by proteinuria. SERPINC1 and ICAM1 were identified as the candidate biomarkers with excellent area-under-the-curve (AUC) values (0.84) for distinguishing Uygur IgAN from normal controls.

Conclusions

Using urinary proteomic analysis, we identified several candidate biomarkers for IgAN in patients of Uygur ethnicity. These results will prove helpful for exploring the pathological mechanism of IgAN in patients of Uygur ethnicity and for developing better treatments for these patients.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1139-3) contains supplementary material, which is available to authorized users.

Urinary Biomarkers for Chronic Kidney Disease with a Focus on Gene Transcript

Objective:

In the upcoming era of precision medicine, searching for the early, noninvasive biomarkers has been the cornerstone and major challenge in the management of chronic kidney disease (CKD). Urine contains rich biological information which could be the ideal source for noninvasive biomarkers of CKD. This review will discuss the recent advance in urinary biomarker.

Data Sources:

This review was based on data in articles published in the PubMed databases up to June 20, 2017, with the following keywords: “Chronic kidney disease”, “Biomarker”, and “Urine”.

Study Selection:

Original articles and important reviews on urinary biomarker were selected for this review.

Results:

Urinary biomarker studies of CKD mainly focused on urine sediment, supernatant, and urinary extracellular vesicles. The gene transcript (microRNA [miRNA], messenger RNA [mRNA]) biomarkers have been recently shown with diagnostic potential for CKD reflecting kidney function and histological change. However, challenges regarding technique and data analysis need to be resolved before translation to clinic.

Conclusions:

Different fractions of urine contain rich information for biomarker discovery, among which urine (extracellular vesicles) mRNA, miRNA, might represent promising biomarker for CKD.

Neuroproteomics Studies: Challenges and Updates

The Human Genome Project in 2003 has resulted in the complete sequence of ~99% of the human genome paving the road for the Human Proteome Project (HPP) assessing the full characterization of the translated protein map of the 20,300 protein-coding genes. Consequently, the emerging of the proteomics field has successfully been adopted as the method of choice for the proteome characterization. Proteomics is a term that is used to encompass multidisciplinary approaches combining different technologies that aim to study the entire spectrum of protein changes at a specific physiological condition. Proteomics research has shown excellent outcomes in different fields, among which is neuroscience; however, the complexity of the nervous systems necessitated the genesis of a new subdiscipline of proteomics termed as "neuroproteomics." Neuroproteomics studies involve assessing the quantitative and qualitative aspects of nervous system components encompassing global dynamic events underlying various brain-related disorders ranging from neuropsychiatric disorders, degenerative disorders, mental illness, and most importantly brain-specific neurotrauma-related injuries. In this introductory chapter, we will provide a brief historical perspective on the field of neuroproteomics. In doing so, we will highlight on the recent applications of neuroproteomics in the areas of neurotrauma, an area that has benefitted from neuroproteomics in terms of biomarker research, spatiotemporal injury mechanism, and its use to translate its findings from experimental settings to human translational applications. Importantly, this chapter will include some recommendation to the general studies in the area of neuroproteomics and the need to move from this field from being a descriptive, hypothesis-free approach to being an independent mature scientific discipline.

Update on Urinary Tract Markers in Interstitial Cystitis/Bladder Pain Syndrome

Interstitial cystitis (IC)/painful bladder syndrome/bladder pain syndrome (BPS) is a chronic hypersensory condition of unknown etiology. Moreover, the optimal modality for diagnosing IC remains disputed. Several urinary markers have been investigated that may have potential utility in the diagnosis or confirmation of IC/BPS. Thus, inflammatory mediators, proteoglycans, urinary hexosamines, proliferative factors, nitric oxide (NO), BK polyomavirus family, and urothelial proinflammatory gene analysis have been found to correlate with varying degrees with the clinical diagnosis or cystoscopic findings in patients with IC/BPS. The most promising urinary biomarker for IC/BPS is antiproliferative factor, a sialoglycopeptide that has demonstrated inhibitory effects on urothelial cell proliferation and a high sensitivity and specificity for IC/BPS symptoms and clinical findings. In this article, we review the urinary markers, possible future therapies for IC/BPS, and the clinical relevance and controversies regarding the diagnosis of IC/BPS.

Detection of inflammatory biomarkers in saliva and urine: Potential in diagnosis, prevention, and treatment for chronic diseases

Inflammation is a part of the complex biological response of inflammatory cells to harmful stimuli, such as pathogens, irritants, or damaged cells. This inflammation has been linked to several chronic diseases including cancer, atherosclerosis, rheumatoid arthritis, and multiple sclerosis. Major biomarkers of inflammation include tumor necrosis factor, interleukins (IL)-1, IL-6, IL-8, chemokines, cyclooxygenase, 5-lipooxygenase, and C-reactive protein, all of which are regulated by the transcription factor nuclear factor-kappaB. Although examining inflammatory biomarkers in blood is a standard practice, its identification in saliva and/or urine is more convenient and non-invasive. In this review, we aim to (1) discuss the detection of these inflammatory biomarkers in urine and saliva; (2) advantages of using salivary and urinary inflammatory biomarkers over blood, while also weighing on the challenges and/or limitations of their use; (3) examine their role(s) in connection with diagnosis, prevention, treatment, and drug development for several chronic diseases with inflammatory consequences, including cancer; and (4) explore the use of innovative salivary and urine based biosensor strategies that may permit the testing of biomarkers quickly, reliably, and cost-effectively, in a decentralized setting.

Selected renal cells modulate disease progression in rodent models of chronic kidney disease via NF-κB and TGF-β1 pathways

AIM

Identification of mechanistic pathways for selected renal cell (SRC) therapeutic bioactivity in rodent models of chronic kidney disease.

MATERIALS & METHODS

In vivo and in vitro functional bioassays applied to investigate regenerative outcomes associated with delivery of SRC to diseased rodent kidney.

RESULTS

In vivo, SRC reduces chronic infiltration by monocytes/macrophages. SRC attenuates NF-κB and PAI-1 responses while simultaneously promoting host tubular cell expansion through trophic cues. In vitro, SRC-derived conditioned media attenuates TNF-α-induced NF-κB response, TGF-β-mediated PAI-1 response and increases expression of transcripts associated with cell cycle regulation. Observed bioactive responses were from vesicle and nonvesicle-associated factors, including specific miRNAs.

CONCLUSION

We identify a paracrine mechanism for SRC immunomodulatory and trophic cues on host renal tissues, catalyzing long-term functional benefits in vivo.

Discovering cancer biomarkers from clinical samples by protein microarrays

Cancer biomarkers are of potential use in early cancer diagnosis, anticancer therapy development, and monitoring the responses to treatments. Protein-based cancer biomarkers are major forms in use, as they are much easier to be monitored in body fluids or tissues. For cancer biomarker discovery, high-throughput techniques such as protein microarrays hold great promises, because they are capable of global unbiased monitoring but with a miniaturized format. In doing so, novel and cancer type specific biomarkers can be systematically discovered at an affordable cost. In this review, we give a relatively complete picture on protein microarrays applied to clinical samples for cancer biomarker discovery, and conclude this review with the future perspectives.

T helper (Th)-cytokines in the urine of patients with primary glomerulonephritis treated with immunosuppressive drugs: Can they predict outcome?

BACKGROUND

Glomerulonephritides (GNs) represent common causes of chronic kidney disease associated with a wide spectrum of clinical and histological features. Various factors that activate the inflammatory cascade are involved in the development of kidney injury. The aim of this study was to estimate the urinary excretion of pro-inflammatory (IL-2, INF-γ, TNF-α, IL-6, IL-17) and anti-inflammatory (IL-4, IL-10, TGF-β1) cytokines, as well as the chemokine MCP-1 in patients with various types of GN treated by immunosuppressive drugs and to identify any prognostic value of excreted cytokines for future renal function.

PATIENTS AND METHODS

Ninety-seven patients (62 M/35 F, age 53.1 ± 15.6 years) with primary glomerulonephritis and 32 healthy controls were studied. The original diagnoses were membranous nephropathy (MN, n=36), IgA nephropathy (IgAN, n=31) and minimal changes disease or focal segmental glomerulosclerosis (MCD/FSGS, n=30). All patients had been treated with immunosuppressive drugs and, at the time of measurement of urinary cytokine excretion, were either in clinical remission or still had active disease with persistent proteinuria.

RESULTS

GN patients had significantly higher levels of all cytokines and MCP-1 compared to healthy controls. A strong positive correlation between TGF-β1 and MCP-1 concentrations was observed in all GN patients. Increased urinary excretion of all tested cytokines apart from TNF-α and TGF-β1 was observed even in patients with clinical remission. The main difference between patients with proteinuria and those in clinical remission was the level of MCP-1 urinary excretion. The urinary excretion of MCP-1 and TGF-β1 was significantly higher in patients with MN who showed deterioration of renal function over a follow-up period of five years.

CONCLUSIONS

Increased levels of cytokines are observed in the urine of patients with different types of glomerulonephritis, even after the achievement of clinical remission with the administration of immunosuppressive drugs. Urinary excretion of MCP-1 and TGF-β1 indicates the ongoing inflammatory and fibrotic processes in the kidney and is probably related to unfavourable outcomes.

Inhibition of Thrombin-Activated Fibrinolysis Inhibitor Increases Survival in Experimental Kidney Fibrosis

Uncontrolled diabetes, inflammation, and hypertension are key contributors to progressive renal fibrosis and subsequent loss of renal function. Reduced fibrinolysis appears to be a feature of ESRD, but its contribution to the fibrotic program has not been extensively studied. Here, we show that in patients with CKD, the activity levels of serum thrombin-activated fibrinolysis inhibitor and plasmin strongly correlated with the degree of renal function impairment. We made similar observations in rats after subtotal nephrectomy and tested whether pharmacologic inhibition of thrombin-activated fibrinolysis inhibitor with UK-396082 could reduce renal fibrosis and improve renal function. Compared with untreated animals, UK-396082-treated animals had reduced glomerular and tubulointerstitial fibrosis after subtotal nephrectomy. Renal function, as measured by an increase in creatinine clearance, was maintained and the rate of increase in proteinuria was reduced in UK-396082-treated animals. Furthermore, cumulative survival improved from 16% to 80% with inhibition of thrombin-activated fibrinolysis inhibitor. Taken together, these data support the importance of the fibrinolytic axis in regulating renal fibrosis and point to a potentially important therapeutic role for suppression of thrombin-activated fibrinolysis inhibitor activity.

Antibody arrays in biomarker discovery

All of life is regulated by complex and organized chemical reactions that help dictate when to grow, to move, to reproduce, and to die. When these processes go awry, or are interrupted by pathological agents, diseases such as cancer, autoimmunity, or infections can result. Cytokines, chemokines, growth factors, adipokines, and other chemical moieties make up a vast subset of these chemical reactions that are altered in disease states, and monitoring changes in these molecules could provide for the identification of disease biomarkers. From the first identification of carcinoembryonic antigen, to the discovery of prostate-specific antigen, to numerous others described within, biomarkers of disease are detectable in a plethora of sample types. The growing number of biomarkers for infection, autoimmunity, and cancer allow for increasingly early detection, to identification of novel drug targets, to prognostic indicators of disease outcome. However, more and more studies are finding that a single cytokine or growth factor is insufficient as a true disease biomarker and that a more global perspective is needed to understand true disease biology. Such a broad view requires a multiplexed platform for chemical detection, and antibody arrays meet and exceed this need by performing this detection in a high-throughput fashion. Herein, we will discuss how antibody arrays have evolved, and how they have helped direct new drug target design, helped identify therapeutic disease markers, and helped in earlier disease detection. From asthma to renal disease, and neurological dysfunction to immunologic disorders, antibody arrays afford a bright future for new biomarkers discovery.

Tumor necrosis factor-α regulates matrix metalloproteinase-2 expression and cell migration via ERK pathway in rat glomerular mesangial cells

Mesangial cells (MCs), vascular smooth muscle-derived cells, contribute to glomerular injury by generating a number of cytokines such as tumor necrosis factor-α (TNF-α). Matrix metalloproteinases (MMPs), regulated by various stimuli, are important in remodeling of glomerular ECM, which leads to a number of renal diseases. We investigated whether TNF-α participated in the regulation of MMPs and explored signal pathways involved in TNF-α-induced MMPs expression in rat glomerular MCs. Western blot and RT-qPCR results showed that treatment with TNF-α significantly increased the expression of MMP-2, but not MMP-9 at both protein and mRNA levels in rat glomerular MCs. The extracellular signal-regulated kinase (ERK) and nuclear factor-kappaB (NF-κB) signal pathways were activated by TNF-α. Moreover, the activation of NF-κB pathway in rat MCs was effectively inhibited by PD98059, specific inhibitor of ERK, suggesting a role for ERK in regulating NF-κB function. PD98059 or NF-κB signal pathway selective inhibitor Bay 11-7082 effectively blocked TNF-α-induced expression of MMP-2 in rat MCs, as determined by gene and protein expression. C-jun N-terminal kinase (JNK) signal pathway had no effect on TNF-α-induced expression of MMP-2, even though it was also activated by TNF-α in rat MCs. Furthermore, TNF-α could induce the cell migration of rat MCs, whereas ERK signal pathway specific inhibitor PD98059 compromised the cell migration triggered by TNF-α. Thus, TNF-α upregulates the expression of MMP-2 via activation of ERK-dependent NF-κB pathway in rat MCs, which may contribute to the cell migration of rat MCs.

A population of selected renal cells augments renal function and extends survival in the ZSF1 model of progressive diabetic nephropathy

New treatment paradigms that slow or reverse progression of chronic kidney disease (CKD) are needed to relieve significant patient and healthcare burdens. We have shown that a population of selected renal cells (SRCs) stabilized disease progression in a mass reduction model of CKD. Here, we further define the cellular composition of SRCs and apply this novel therapeutic approach to the ZSF1 rat, a model of severe progressive nephropathy secondary to diabetes, obesity, dyslipidemia, and hypertension. Injection of syngeneic SRCs into the ZSF1 renal cortex elicited a regenerative response that significantly improved survival and stabilized disease progression to renal structure and function beyond 1 year posttreatment. Functional improvements included normalization of multiple nephron structures and functions including glomerular filtration, tubular protein handling, electrolyte balance, and the ability to concentrate urine. Improvements to blood pressure, including reduced levels of circulating renin, were also observed. These functional improvements following SRC treatment were accompanied by significant reductions in glomerular sclerosis, tubular degeneration, and interstitial inflammation and fibrosis. Collectively, these data support the utility of a novel renal cell-based approach for slowing renal disease progression associated with diabetic nephropathy in the setting of metabolic syndrome, one of the most common causes of end-stage renal disease.

Urinary mRNA markers of epithelial-mesenchymal transition correlate with progression of diabetic nephropathy

OBJECTIVE

Epithelial-mesenchymal transition (EMT) plays an important role in the pathogenesis and progression of diabetic nephropathy (DN). Quantification of messenger RNA (mRNA) expression in urinary sediment is emerging as a noninvasive method of screening DN-associated biomarkers. The aim of our study was to examine whether urinary mRNA profile of EMT-associated genes may provide valuable clinical insight into the different stages of DN.

DESIGN AND METHODS

Diabetic nephropathy patients (n = 44) and healthy controls (n = 12) were enrolled in this study. DN patients were divided into three groups according to the levels of estimated glomerular filtration rate (eGFR): Group A (eGFR > 60 ml/min per 1·73 m(2), n = 27), Group B (45 < eGFR < 60 ml/min per 1·73 m(2), n = 9), and Group C (eGFR < 45 ml/min per 1·73 m(2), n = 8). Relative mRNA abundance of α-smooth muscle actin (α-SMA), fibronectin, FSP1 and matrix metalloproteinase-9 (MMP-9) were quantified, and correlations between target mRNAs and clinical parameters were examined.

RESULTS

The urinary mRNA levels of α-SMA, fibronectin and MMP-9 were significantly higher in the DN group compared with controls (P < 0·05), and mRNA levels increased with DN progression. Urinary mRNA levels of all target genes positively correlated with both urinary albumin excretion (UAE) and blood urea nitrogen (BUN). Moreover, the expression of α-SMA, fibronectin and MMP-9 mRNA correlated with serum creatinine levels (r = 0·514, r = 0·53 and r = 0·469, all P < 0·001) and GFR levels (r = -0·374, r = -0·392 and r = -0·487, all P < 0·01).

CONCLUSIONS

Quantification of EMT-associated genes in urinary sediment may be a novel approach for searching new biomarkers of DN.

Preclinical perspective of urinary biomarkers for the detection of nephrotoxicity: what we know and what we need to know

The assessment of kidney damage is a challenge and must incorporate assessment of the functional capacity of the kidney, as well as a comprehensive understanding of the kidney's role. Multiple parameters have been used for many years to measure renal functionality to assess renal damage. It is astonishing that, beside histopathology, the most common traditional parameters are serum based. However, urine is also used to obtain additional information regarding the health status of the kidneys. Since 2008, several novel urinary protein biomarkers have been qualified by the US FDA and the European Medicines Agency in conjunction with the Predictive Safety Testing Consortium in a specially developed qualification process. Subsequently, the Pharmaceuticals and Medical Devices Agency accepted the qualification of these seven urinary biomarkers. This review will give an overview of the state-of-the-art detection based on urinary biomarkers, which will enhance toxicological research in the future. In addition, the qualification process that leads to acceptance of these biomarkers will be described because of its uniqueness and importance for the field of biomarker research.

Low-level laser irradiation alters cardiac cytokine expression following acute myocardial infarction: a potential mechanism for laser therapy

OBJECTIVES

Low-level laser irradiation (LLLI) has the potential of exerting cardioprotective effect following myocardial infarction (MI). The authors hypothesized that LLLI could influence the expression of cardiac cytokines and contribute to the reversal of ventricular remodeling.

BACKGROUND

LLLI regulates the expression of cytokines after tissue damage. However, little is known concerning the alteration of the cardiac cytokine expression profile after LLLI.

METHODS

MI was created by coronary ligation. The surviving rats were divided randomly into laser and control groups. 33 rats were exposed to a diode laser (635  nm, 5  mW, CW, laser, beam spot size 0.8  cm(2), 6  mW/cm(2), 150  sec, 0.8  J, 1J/cm(2)) as laser group. Another 33 rats received only coronary ligation and served as control group. 28 rats received a thoracotomy without coronary ligation (sham group). One day after laser irradiation, 5 rats from each group were sacrificed and the heart tissues were analyzed by cytokine antibody arrays. Enzyme-linked immunosorbent assay (ELISA) was performed to confirm its reliability. Two weeks after MI, cardiac function and structure were evaluated by echocardiography and histological study.

RESULTS

Cytokine antibody array indicated 4 cytokines were significantly changed after laser therapy. ELISA confirmed that granulocyte-macrophage colony stimulating factor and fractalkine were the cytokines involved in the response to therapeutic laser irradiation. However, there was no difference in cytokine release between various groups at 2 weeks after MI. Although LLLI did not improve the damaged heart function, it did reduce the infarct area expansion.

CONCLUSIONS

The antibody-based protein array technology was applied for screening the cytokine expression profile following MI, with or without laser irradiation. The expression of multiple cytokines was regulated in the acute phase after LLLI. Our results revealed a potential novel mechanism for applying laser therapy to the treatment of heart disease.

Effect of primate bone marrow stromal cells on survival and neurite outgrowth

We tested whether bone marrow stromal cells (BMSCs) could enhance the survival and neurite growth of dorsal root ganglia (DRG) through substrate effects or secreted factors. Our results showed that in DRG with BMSCs and BMSC-conditioned media cultures compared with DRG-fibroblast cultures, there was a significant increase in the number and length of, area covered by, and number of cells with definite neurites. In cytokine assays with conditioned media, vascular endothelial growth factor, granulocyte macrophage colony-stimulating factor, and IL-6 secreted by BMSCs may contribute to observed neurotrophic effects. These findings indicate that BMSCs of adult Macaca fascicularis increased neuronal survival and promoted neurite outgrowth of DRG by means of secretory factors.

Performance of novel kidney biomarkers in preclinical toxicity studies

The kidney is one of the main targets of drug toxicity, but early detection of renal damage is often difficult. As part of the InnoMed PredTox project, a collaborative effort aimed at assessing the value of combining omics technologies with conventional toxicology methods for improved preclinical safety assessment, we evaluated the performance of a panel of novel kidney biomarkers in preclinical toxicity studies. Rats were treated with a reference nephrotoxin or one of several proprietary compounds that were dropped from drug development in part due to renal toxicity. Animals were dosed at two dose levels for 1, 3, and 14 days. Putative kidney markers, including kidney injury molecule-1 (Kim-1), lipocalin-2 (Lcn2), clusterin, and tissue inhibitor of metalloproteinases-1, were analyzed in kidney and urine using quantitative real-time PCR, ELISA, and immunohistochemistry. Changes in gene/protein expression generally correlated well with renal histopathological alterations and were frequently detected at earlier time points or at lower doses than the traditional clinical parameters blood urea nitrogen and serum creatinine. Urinary Kim-1 and clusterin reflected changes in gene/protein expression and histopathological alterations in the target organ in the absence of functional changes. This confirms clusterin and Kim-1 as early and sensitive, noninvasive markers of renal injury. Although Lcn2 did not appear to be specific for kidney toxicity, its rapid response to inflammation and tissue damage in general may suggest its utility in routine toxicity testing.

Recent progress of proteomics in critical illness

Critical illness, such as sepsis or septic shock with multiple organ dysfunction syndrome, is the leading cause of morbidity and mortality in intensive care units. The complexity of critical illness requires a robust methodology to explore the underlying mechanisms. Proteomics represents a powerful postgenomic biotechnology used for simultaneous examination of a large number of proteins or the proteome. Recent progress in proteomic techniques allows thorough evaluation of molecular changes associated with critical illness, thereby permitting to identify novel biomarkers and therapeutic targets. This review provides an update on the recent progress and potential of rapidly evolving proteomics approach to facilitate new discoveries in the field of critical care medicine.

Role of matrix metalloproteinases in viral-associated glomerulonephritis

BACKGROUND

Viral infections are a major problem worldwide. Many of these infections are frequently complicated by a virus-associated glomerulonephritis. In glomerulonephritis, progression of renal failure is mainly attributed to the development of extensive glomerular and interstitial fibrosis. Advanced glomerular disease is characterized by the accumulation of extracellular matrix components in the mesangial matrix and glomerular basement membrane. These matrix components are metabolized by matrix metalloproteinases (MMPs) as well as tissue inhibitors of metalloproteinase (TIMPs).

METHODS

The expression of MMP2, MMP9 and TIMP-1 in human mesangial cells in culture was analysed by RT-PCR.

RESULTS

Mesangial cells express the viral receptors toll-like receptor 3 and RIG-I. Activation of these viral receptors by viral RNA exemplified by poly (I:C) RNA leads to a time- and dose-dependent expression of MMP9 without affecting the expression of MMP2 and TIMP-1. To show the specific effect of viral receptors, knockdown experiments with siRNA specific for TLR3 and RIG-I were performed.

CONCLUSION

This novel finding of the functional expression of these viral sensors on glomerular fibrosis may indicate a novel link between viral infections and glomerular inflammation and indicates a pathophysiologic role of viral receptors in these processes.

Effect of renin-angiotensin-aldosterone system inhibition, dietary sodium restriction, and/or diuretics on urinary kidney injury molecule 1 excretion in nondiabetic proteinuric kidney disease: a post hoc analysis of a randomized controlled trial

BACKGROUND

Tubulointerstitial damage plays an important role in chronic kidney disease (CKD) with proteinuria. Urinary kidney injury molecule 1 (KIM-1) reflects tubular KIM-1 and is considered a sensitive biomarker for early tubular damage. We hypothesized that a decrease in proteinuria by using therapeutic interventions is associated with decreased urinary KIM-1 levels.

STUDY DESIGN

Post hoc analysis of a randomized, double-blind, placebo-controlled, crossover trial.

SETTING & PARTICIPANTS

34 proteinuric patients without diabetes from our outpatient renal clinic.

INTERVENTION

Stepwise 6-week interventions of losartan, sodium restriction (low-sodium [LS] diet), their combination, losartan plus hydrochlorothiazide (HCT), and the latter plus an LS diet.

OUTCOMES & MEASUREMENTS

Urinary excretion of KIM-1, total protein, and N-acetyl-beta-d-glucosaminidase (NAG) as a positive control for tubular injury.

RESULTS

Mean baseline urine protein level was 3.8 +/- 0.4 (SE) g/d, and KIM-1 level was 1,706 +/- 498 ng/d (increased compared with healthy controls; 74 ng/d). KIM-1 level was decreased by using placebo/LS (1,201 +/- 388 ng/d; P = 0.04), losartan/high sodium (1,184 +/- 296 ng/d; P = 0.09), losartan/LS (921 +/- 176 ng/d; P = 0.008), losartan/high sodium plus HCT (862 +/- 151 ng/d; P = 0.008) and losartan/LS plus HCT (743 +/- 170 ng/d; P = 0.001). The decrease in urinary KIM-1 levels paralleled the decrease in proteinuria (R = 0.523; P < 0.001), but not blood pressure or creatinine clearance. 16 patients reached target proteinuria with protein less than 1 g/d, whereas KIM-1 levels normalized in only 2 patients. Urinary NAG level was increased at baseline and significantly decreased during the treatment periods of combined losartan plus HCT only. The decrease in urinary NAG levels was not closely related to proteinuria.

LIMITATIONS

Post hoc analysis.

CONCLUSIONS

Urinary KIM-1 level was increased in patients with nondiabetic CKD with proteinuria and decreased in parallel with proteinuria by using losartan, sodium restriction, their combination, losartan plus HCT, and the latter plus sodium restriction. These results are consistent with the hypothesis of amelioration of proteinuria-induced tubular damage. Long-term studies are warranted to evaluate whether targeting treatment on KIM-1 can improve outcomes in patients with CKD with proteinuria.

Clinical application of antibody microarray in chronic kidney disease: How far to go?

Chronic kidney disease (CKD) that affects about 10% of the adult population has been shown as a worldwide public health problem in recent years. Both basic and clinical investigations have identified complex disease-associated protein networks involved in the pathophysiologic processes of CKD. The traditional single-assay approach and proteomic analysis of those related proteins have given birth to a steadily increasing panel of molecules that may have the potential to serve as biomarkers for CKD. However, both approaches suffered from some shortcomings from a technological point of view. Antibody microarray (AbM) is characterized by high sensitivity, specificity, and quantitative ability for a particular set of known proteins. However, its application in CKD has been very limited so far. The objective of this review, therefore, is to address the potential applications of AbM in studying of CKD. We will briefly discuss the proteins involved in the development of CKD, future directions in which AbM approaches would probably display its potential and also some key issues that need to be considered in application of this novel technique.

High-throughput antibody microarrays for quantitative proteomic analysis

The antibody microarray is an intrinsically robust and quantitative system that delivers high-throughput and parallel measurements on particular sets of known proteins. It has become an important proteomics research tool, complementary to the conventional unbiased separation-based and mass spectrometry-based approaches. This review summarizes the technical aspects of production and the application for quantitative proteomic analysis with an emphasis on disease proteomics, especially the identification of biomarkers. Quality control, data analysis methods and the challenges for quantitative assays are also discussed.

TNF-alpha and IL-1 beta-mediated regulation of MMP-9 and TIMP-1 in human glomerular mesangial cells

BACKGROUND

Renal cells such as mesangial cells are known to secrete metalloproteinases that are capable of degrading the constituents of the glomerular basement membrane (GBM). Disruption of the GBM via cytokine-induced alterations in matrixmetalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) may be an important mechanism in the renal disease process. In renal disease, both resident renal cells and infiltrating immune cells are capable of secreting pro-inflammatory cytokines including tumour necrosing factor-alpha (TNFalpha) and interleukin-1 beta (IL-1 beta). In this study, we examine the potential of these cytokines to alter levels of MMPs and TIMPs in human mesangial cells.

METHODS

The T-HMC human mesangial cell line was cultured in RPMI 1640 containing 5% serum. Cells at confluency were serum starved for 24 h prior to exposure to TNF-alpha (0.1-100 ng/ml) or IL-1 beta (0.1-100 ng/ml) or a combination of both for 48 h. Activity of MMP-9 was examined by gelatin zymography and TIMP-1 expression was analysed by Western blotting.

RESULTS

TNF-alpha but not IL-1 beta resulted in a dose-dependent increase in the latent form of MMP-9 and a decrease in TIMP-1 production. Co-treatment with IL-1 beta had no effect on the induction of MMP-9 but increased the inhibition of TIMP-1 in the presence of TNF-alpha. Inhibition of PKC provided evidence of the importance of this pathway in mediating the TNF-alpha-induced suppression of TIMP-1. Activation of the ERK 1/2 MAPK mediated both the upregulation of MMP-9 and the inhibition of TIMP-1 following TNF-alpha treatment. p38 MAPK activation was also found to be involved in the TNF-alpha-stimulated MMP-9.

CONCLUSION

The cytokine TNF-alpha causes different effects on human mesangial MMP-9 and TIMP-1 expression which are mediated through the TNF-RI, and the different signalling pathways of PKC, ERK 1/2 and p38 MAPK. This suggests an important role for pro-inflammatory cytokines in renal disease progression.

Recent progress in urinary proteomics

Urinary proteomics has become one of the most attractive subdisciplines in clinical proteomics as the urine is an ideal source for the discovery of noninvasive biomarkers for kidney and nonkidney diseases. This field has been growing rapidly as indicated by >80 original research articles on urinary proteome analyses appearing since 2001, of which 28 (approximately 1/3) had been published within the year 2006. The most common technologies used in recent urinary proteome studies remain gel-based methods (1-DE, 2-DE and 2-D DIGE), whereas LC-MS/MS, SELDI-TOF MS, and CE-MS are other commonly used techniques. In addition, mass spectrometric immunoassay (MSIA) and array technology have also been applied. This review provides an extensive but concise summary of recent applications of urinary proteomics. Proteomic analyses of dialysate and ultrafiltrate fluids derived from renal replacement therapy (or artificial kidney) are also discussed.

Therapeutic potential of TGF-beta inhibition in chronic renal failure

Chronic kidney diseases are emerging as a worldwide public health problem. The progression of kidney diseases closely correlates with the accumulation of extracellular matrix leading to glomerulosclerosis and tubulointerstitial injury. Transforming growth factor (TGF)-beta has been identified as a key mediator of kidney matrix accumulation. Overexpression of TGF-beta isoforms and their receptors was observed in a variety of renal diseases in both animals and humans. Given its crucial role in fibrotic kidney disease, TGF-beta has been recently considered as a possible target in the management of chronic renal diseases. This review discusses the role of TGF-beta in renal fibrosis and provides an overview of the strategies that, when interfering with TGF-beta expression and signalling, could be employed as new renoprotective treatments.

Antibody arrays--an emerging tool in cancer proteomics

Cancer is a result of complex changes that occur in normal cells as they transform to become malignant and further when they become metastatic. These changes are not a consequence of a single protein but rather involve multiple proteins that function in pathways and networks. Thus, profiling cancer-associated changes requires simultaneous measurement of many proteins in a single sample. Identifying these changes may lead to the discovery of cancer-associated biomarkers that may assist in diagnosis, prognosis, patient monitoring and possibly for therapeutic purposes. Antibody arrays are a relatively new technology that enables one to perform multiplex high-throughput protein expression profiling. This review describes current technologies in antibody array and assay design, and presents a survey of the current literature on the use of these arrays in cancer research.

Mechanisms of disease: regulation of RANTES (CCL5) in renal disease

Chemokines (chemoattractant cytokines) are fundamental regulators of immune cell movement from the bloodstream into tissues. Regulating expression of chemokines might, therefore, alleviate inflammation in autoimmune diseases and transplant rejection, or augment immune responses in cancer and immunodeficiency. RANTES (regulated upon activation, normal T cell expressed and secreted [also known as CCL5]) is a model chemokine of relevance to a myriad of diseases. Regulation of RANTES expression is complex. In fibroblasts and monocytes, rel proteins alone suffice to induce transcription of RANTES. By contrast, expression of RANTES in T lymphocytes 3-5 days after activation requires the development of a molecular complex (enhancesome) including KLF13 (Krueppel-like factor 13), rel proteins p50 and p65, and scaffolding proteins. This complex recruits enzymes involved in acetylation, methylation and phosphorylation of chromatin, and ultimately in the expression of RANTES. In addition, KLF13-the lynchpin for recruitment of this molecular complex-is itself translationally regulated. Such complex regulation of biological systems has major implications for the rational design of drugs aimed at increasing or decreasing inflammatory responses in patients.

Diagnostic potential for urinary proteomics

Urine represents a modified ultrafiltrate of plasma, with protein concentrations typically approximately 1000-fold lower than plasma. Urine’s low protein concentration might suggest it to be a less promising diagnostic specimen than plasma. However, urine can be obtained noninvasively and tests of many urinary proteins are well-established in clinical practice. Proteomic technologies expand opportunities to analyze urinary proteins, identifying more than 1000 proteins and peptides in urine. Urine offers a sampling of most plasma proteins, with increased proportions of low-molecular-weight protein and peptide components. Urine also offers enriched sampling of proteins released along the urinary tract. Although urine presents some challenges as a diagnostic specimen, its diverse range of potential markers offers great potential for diagnosis of both systemic and kidney diseases. Examples of clinical situations where this may be of value are for more sensitive detection of kidney transplant rejection or of renal toxicity of medications.