Urinary monocyte chemoattractant protein-1 correlates with disease activity in lupus nephritis

Urinary Biomarkers for Lupus Nephritis: A Systems Biology Approach

Systemic lupus erythematosus (SLE) is the prototypical systemic autoimmune disorder. Kidney involvement, termed lupus nephritis (LN), is seen in 40-60% of patients with systemic lupus erythematosus (SLE). After the diagnosis, serial measurement of proteinuria is the most common method of monitoring treatment response and progression. However, present treatments for LN-corticosteroids and immunosuppressants-target inflammation, not proteinuria. Furthermore, subclinical renal inflammation can persist despite improving proteinuria. Serial kidney biopsies-the gold standard for disease monitoring-are also not feasible due to their inherent risk of complications. Biomarkers that reflect the underlying renal inflammatory process and better predict LN progression and treatment response are urgently needed. Urinary biomarkers are particularly relevant as they can be measured non-invasively and may better reflect the compartmentalized renal response in LN, unlike serum studies that are non-specific to the kidney. The past decade has overseen a boom in applying cutting-edge technologies to dissect the pathogenesis of diseases at the molecular and cellular levels. Using these technologies in LN is beginning to reveal novel disease biomarkers and therapeutic targets for LN, potentially improving patient outcomes if successfully translated to clinical practice.

Low nephron endowment increases susceptibility to renal stress and chronic kidney disease

Preterm birth results in low nephron endowment and increased risk of acute kidney injury (AKI) and chronic kidney disease (CKD). To understand the pathogenesis of AKI and CKD in preterm humans, we generated potentially novel mouse models with a 30%-70% reduction in nephron number by inhibiting or deleting Ret tyrosine kinase in the developing ureteric bud. These mice developed glomerular and tubular hypertrophy, followed by the transition to CKD, recapitulating the renal pathological changes seen in humans born preterm. We injected neonatal mice with gentamicin, a ubiquitous nephrotoxic exposure in preterm infants, and detected more severe proximal tubular injury in mice with low nephron number compared with controls with normal nephron number. Mice with low nephron number had reduced proliferative repair with more rapid development of CKD. Furthermore, mice had more profound inflammation with highly elevated levels of MCP-1 and CXCL10, produced in part by damaged proximal tubules. Our study directly links low nephron endowment with postnatal renal hypertrophy, which in this model is maladaptive and results in CKD. Underdeveloped kidneys are more susceptible to gentamicin-induced AKI, suggesting that AKI in the setting of low nephron number is more severe and further increases the risk of CKD in this vulnerable population.

Sickle cell nephropathy: A review of novel biomarkers and their potential roles in early detection of renal involvement

Whether the underlying mutations are homozygous, heterozygous, or co-inherited with other hemoglobinopathies, sickle cell disease is known to afflict the kidneys, leading to the clinical entity known as sickle cell nephropathy (SCN). Although common, SCN remains diagnostically elusive. Conventional studies performed in the context of renal disorders often fail to detect early stage SCN. This makes the quest for early diagnosis and treatment more challenging, and it increases the burden of chronic kidney disease-related morbidity among patients. Novel diagnostic tools have been employed to overcome this limitation. In this study, we discuss various biomarkers of SCN, including those employed in clinical practice and others recently identified in experimental settings, such as markers of vascular injury, endothelial dysfunction, tubulo-glomerular damage, and oxidative stress. These include kidney injury molecule-1, monocyte chemoattractant protein-1, N-acetyl-B-D-glucosaminidase, ceruloplasmin, orosomucoid, nephrin, and cation channels, among others. Furthermore, we explore the potential of novel biomarkers for refining diagnostic and therapeutic approaches and describe some obstacles that still need to be overcome. We highlight the importance of a collaborative approach to standardize the use of promising new biomarkers. Finally, we outline the limitations of conventional markers of renal damage as extensions of the pathogenic process occurring at the level of the organ and its functional subunits, with a discussion of the expected pattern of clinical and biochemical progression among patients with SCN.

Biomarkers in Childhood-Onset Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a complex, multisystem chronic autoimmune disease. Because of its diverse phenotypes, diagnosis of SLE can be challenging, and current biomarkers are insufficient. Childhood-onset SLE (cSLE), although less prevalent, has higher morbidity and mortality, and early diagnosis is critical for improving outcomes. Many studies have focused on discovering new biomarkers to better diagnose and monitor SLE and cSLE. Herein, the authors aim to review the most investigated biomarkers in development for cSLE, focusing on those that can be measured in the blood or urine.

Urinary Tumor Necrosis Factor-Like Weak Inducer of Apoptosis as a Biomarker for Diagnosis and Evaluating Activity in Lupus Nephritis: A Meta-analysis

OBJECTIVE

Urinary tumor necrosis factor-like weak inducer of apoptosis (uTWEAK) has been identified as a candidate biomarker for lupus nephritis (LN). However, its diagnostic value remains unclear. This meta-analysis was conducted to comprehensively evaluate the value of uTWEAK for diagnosis and evaluating activity in LN.

METHODS

Medline, Web of Science, Chinese Biomedical Medical, and Chinese National Knowledge Infrastructure databases were searched to acquire eligible studies published before September 30, 2019. The quality of the studies was evaluated by Quality Assessment of Diagnostic Accuracy Studies-2. Summary receiver operating characteristic curve and area under the curve were applied to summarize the overall diagnostic performances. The pooled sensitivity, specificity, and diagnostic odds ratio (DOR) were calculated with the fixed-effects model. RevMan 5.3, Stata 12.0, and Meta-disc 1.4 software were used.

RESULTS

A total of 7 studies were included. Of these, 4 studies were available for comparison between SLE with and without LN, and 3 studies were for active and inactive LN. The total area under the curve was 0.8640, and DOR was 14.89 (95% confidence interval [CI], 7.95-27.86). For LN diagnosis, the pooled sensitivity, specificity, and DOR were 0.55 (95% CI, 0.47-0.63), 0.92 (95% CI, 0.86-0.96), and 16.54 (95% CI, 7.57-36.15), respectively. For assessing LN activity, the pooled sensitivity, specificity, and DOR were 0.91 (95% CI, 0.82-0.96), 0.70 (95% CI, 0.58-0.81), and 18.45 (95% CI, 7.45-45.87), respectively.

CONCLUSIONS

This meta-analysis indicated that uTWEAK has relatively moderate sensitivity and specificity for diagnosis and evaluating activity in LN, suggesting that uTWEAK can serve as a helpful biomarker for LN.

Proteomic profiling of urine: implications for lupus nephritis

INTRODUCTION

Lupus nephritis (LN) is a common and significant manifestation, affecting 60% of adults and 80% of children with systemic lupus erythematosus, with up to 30% of patients progressing to end stage renal disease. There remains an unmet need for non-invasive markers of disease activity, damage, and response to therapy. In addition, non-invasive biomarkers that predict therapeutic efficacy are needed to enable cost-effective clinical trials of novel agents. Areas covered: This review examines the methodological aspects of urinary proteomics, the role of proteome profiling in identifying promising urinary biomarkers in LN, and the translation of research findings into clinically useful tools in the management of LN. Expert opinion: Targeted and unbiased proteomics have identified several promising urinary biomarkers that predict LN activity, damage (chronicity), and response to therapy. In particular, a combination of biologically plausible urinary biomarkers termed as RAIL (Renal Activity Index for Lupus) has emerged as an excellent predictor of LN activity as well as response to therapy, being able to predict efficacy within 3 months of therapy. If validated in additional large prospective studies, the RAIL biomarkers will transform the care of patients with LN, allowing for a personalized and predictive approach and improved outcomes.

Differential expressions of plasma proteins in systemic lupus erythematosus patients identified by proteomic analysis

INTRODUCTION

Systemic lupus erythematosus (SLE) is a chronic and complex autoimmune disease with a wide range of clinical manifestations that affects multiple organs and tissues. Therefore the differential expression of proteins in the serum/plasma have potential clinical applications when treating SLE.

METHODS

We have compared the plasma/serum protein expression patterns of nineteen active SLE patients with those of twelve age-matched and gender-matched healthy controls by proteomic analysis. To investigate the differentially expressed proteins among SLE and controls, a 2-dimensional gel electrophoresis coupled with high-resolution liquid chromatography tandem mass spectrometry was performed. To further understand the molecular and biological functions of the identified proteins, PANTHER and Gene Ontology (GO) analyses were employed.

RESULTS

A total of 14 significantly expressed (p < 0.05, p < 0.01) proteins were identified, and of these nine were up-regulated and five down-regulated in the SLE patients. The functional enrichment analysis assigned the majority of the identified proteins including alpha 2 macroglobulin, complement C4, complement factor H, fibrinogen beta chain, and alpha-1-antitrypsin were part of the complement/coagulation cascade, which is an important pathway that plays a crucial role in SLE pathogenesis. In addition to these proteins the differential expressions of ceruloplasmin, transthyretin, and haptoglobin play a potential role in the renal system abnormalities of SLE.

CONCLUSION

Therefore, the identified differentially expressed proteins are relevant to SLE patient's cohort. Most importantly the up-regulated proteins might be the potential candidates for renal system involvement in SLE disease pathogenesis. In order to confirm the diagnostic/therapeutic potential of the identified proteins, future validation studies are required.

Rapid detection of urinary soluble intercellular adhesion molecule-1 for determination of lupus nephritis activity

The current methods of monitoring the activity of lupus nephritis (LN) may cause unnecessary hospital visits or delayed immunosuppressive therapy. We aimed to find a urinary biomarker that could be developed as a home-based test for monitoring the activity of LN.Urine samples were collected immediately before a renal biopsy from patients of suspected active LN, and also from patients with inactive LN, systemic lupus erythematous without LN or healthy controls. Biomarker search was conducted on a cytokine antibody array and confirmation was done by quantitative evaluation with enzyme-linked immunosorbent assay. The Mann-Whiney test or Student t test was used to compare the levels of 9 cytokines between different groups. The sensitivity and specificity of each cytokine for diagnosis of LN was evaluated by receiver operating characteristic curve. A rapid test based on colloidal gold immunochromatography was then developed for bedside or home use. Furthermore, an experimental e-healthcare system was constructed for recording and sharing the results of the rapid test a cloud-assisted internet of things (IoT) consisting of a sensing device, an IoT device and a cloud server.Adiponectin (Acrp30), soluble intercellular cell adhesion molecule-1 (sICAM-1), neural cell adhesion molecule 1 (NCAM-1), and CD26 were significantly higher in urine samples of active LN patients. sICAM-1 appeared more sensitive and specific among these candidates. When the cut-off value of sICAM-1 was set at 1.44 ng/mL, the sensitivity reached 98.33% with a specificity at 85.71%. The sICAM-1 strip test showed comparable sensitivity of 95% and a specificity of 83.3% for assessing the LN activity. Meanwhile, the e-healthcare system was able to conveniently digitize and share the sICAM-1 rapid test results.sICAM-1 appeared to be an excellent biomarker for monitoring LN activity. The e-healthcare system with cloud-assisted IoT could assist the digitalization and sharing of the bedside or home-based sICAM-1 test results.

Plasma proteomic analysis of systemic lupus erythematosus patients using liquid chromatography/tandem mass spectrometry with label-free quantification

CONTEXT

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease with unknown etiology.

OBJECTIVE

Human plasma is comprised of over 10 orders of magnitude concentration of proteins and tissue leakages. The changes in the abundance of these proteins have played an important role in various human diseases. Therefore, the research objective of this study is to identify the significantly altered expression levels of plasma proteins from SLE patients compared with healthy controls using proteomic analysis. The plasma proteome profiles of both SLE patients and controls were compared.

METHODS

A total of 19 active SLE patients and 12 healthy controls plasma samples were analyzed using high-resolution electrospray ionization liquid chromatography-tandem mass spectrometry (LC-ESI-MS/MS) followed by label-free quantification.

RESULTS

A total of 19 proteins showed a significant level of expression in the comparative LC-ESI-MS/MS triplicate analysis; among these, 14 proteins had >1.5- to three-fold up-regulation and five had <0.2- to 0.6-fold down-regulation. Gene ontology and DAVID (Database Annotation Visualization, and Integrated Discovery) functional enrichment analysis revealed that these proteins are involved in several important biological processes including acute phase inflammatory responses, complement activation, hemostasis, and immune system regulation.

CONCLUSION

Our study identified a group of differentially expressed proteins in the plasma of SLE patients that are involved in the imbalance of the immune system and inflammatory responses. Therefore, these findings may have the potential to be used as prognostic/diagnostic markers for SLE disease assessment or disease monitoring.

Serum IP-10 is useful for identifying renal and overall disease activity in pediatric systemic lupus erythematosus

BACKGROUND

Traditional serological biomarkers often fail to assess systemic lupus erythematosus (SLE) disease activity and discriminate lupus nephritis (LN). The aim of this study was to identify novel markers for evaluating renal and overall disease activity in Chinese patients with pediatric systemic lupus erythematosus (pSLE).

METHODS

The study included 46 patients with pSLE (35 girls, 11 boys; average age 13.3 ± 2.6 years) and 31 matched healthy controls (22 girls, 9 boys; average age 12.3 ± 2.4 years). The SLE Disease Activity Index (SLEDAI) and renal SLEDAI were used to assess disease activity. Nine different soluble mediators in plasma, including tumor necrosis factor alpha (TNF-α), platelet-derived growth factor-BB (PDGF-BB), interferon (IFN) gamma inducible protein 10 (IP-10), interleukin (IL)-1β, IFN-γ, IL-17A, IL-2, Fas and Fas ligand, were measured by Luminex assay and compared between patients with active and inactive pSLE as well as between patients with pSLE with active and inactive renal disease. Receiver operating characteristic curve analysis was used to measure the discrimination accuracy.

RESULTS

Of the 46 patients with pSLE, 30 (65.2%) had LN. These patients had significantly elevated levels of serum TNF-α, PDGF-BB, IP-10 and Fas. The serum levels of IP-10 were also significantly higher in patients with active pSLE. We found that IP-10 was also more sensitive and specific than conventional laboratory parameters, including anti-double-stranded DNA and complement components C3 and C4, for distinguishing active lupus from quiescent lupus. The serum level of IP-10 was also significantly increased in children with pSLE with active renal disease relative to those with inactive renal disease. There was also a positive correlation between serum IP-10 levels and renal SLEDAI scores as well as with 24 h urine protein.

CONCLUSIONS

Serum IP-10 is useful for identifying renal and overall disease activity in children with pSLE.

Identification of macrophage-related candidate genes in lupus nephritis using bioinformatics analysis

Lupus nephritis (LN) is a chronic autoimmune disorder. Here we try to identify the candidate genes in macrophages related to LN. We performed a systematic search in the Gene Expression Omnibus (GEO) database for microarray in human mononuclear cells and mouse macrophages of LN. The results of clustering and venn analysis of different GEO datasets showed that 8 genes were up-regulated and 2 genes down-regulated in samples from both human and mouse LN. The data from gene network and GO analysis revealed that CD38 and CCL2 were localized in the core of the network. Immunofluorescence staining showed that CD38 expression was markedly increased in macrophages from kidneys with LN. Our study identifies the gene expression profile for macrophages and demonstrated the induction of CCL2 and CD38 in macrophages from patients with LN. However, regarding the limited patient number included in this study, the results are preliminary and more studies are still needed to further decipher the macrophage-related candidate genes for the pathogenesis of LN.

Low level of circulating basophil counts in biopsy-proven active lupus nephritis

Basophils have been shown to be important players in promoting lupus nephritis (LN). However, the relationship between circulating basophil counts and renal pathology activity of LN remains unclear. In this retrospective study, 159 clinical and pathology samples from patients with biopsy-proven LN were analyzed. The renal activity and classification were evaluated according to renal pathology. The correlations between circulating basophil counts and renal pathology activity index were assessed. Overall, circulating basophil counts correlated with total systemic lupus erythematosus disease activity index (SLEDAI) score (r = - 0.31), renal SLEDAI score (r = - 0.35), activity index (AI) score(r = - 0.40), and renal histologic activity parameters (p < 0.05, respectively). Compared with systemic lupus erythematosus (SLE) non-LN patients, the LN group had lower basophil counts (0.007 ± 0.007 vs. 0.011 ± 0.010 × 10⁹/L, p = 0.04). Subgroup analyses revealed that the circulating basophil counts in group B (AI > 8) were significantly lower than that in group A (AI ≤ 8) (0.004 ± 0.006 vs. 0.009 ± 0.009 × 10⁹/L, p < 0.001). The difference was still significant when eliminating the influence of SLEDAI. Significant differences were found in circulating basophil counts among LN pathology classification groups (p < 0.01). Groups of classes III, IV, and V were more likely to have lower circulating basophil counts when compared with group of class I/II (p < 0.05). These findings suggest a potential role of circulating basophil counts as a convenient and helpful marker for renal activity of LN.

Do classic blood biomarkers of JSLE identify active lupus nephritis? Evidence from the UK JSLE Cohort Study

Background Lupus nephritis (LN) affects up to 80% of juvenile-onset systemic lupus erythematosus (JSLE) patients. The value of commonly available biomarkers, such as anti-dsDNA antibodies, complement (C3/C4), ESR and full blood count parameters in the identification of active LN remains uncertain. Methods Participants from the UK JSLE Cohort Study, aged <16 years at diagnosis, were categorized as having active or inactive LN according to the renal domain of the British Isles Lupus Assessment Group score. Classic biomarkers: anti-dsDNA, C3, C4, ESR, CRP, haemoglobin, total white cells, neutrophils, lymphocytes, platelets and immunoglobulins were assessed for their ability to identify active LN using binary logistic regression modeling, with stepAIC function applied to select a final model. Receiver-operating curve analysis was used to assess diagnostic accuracy. Results A total of 370 patients were recruited; 191 (52%) had active LN and 179 (48%) had inactive LN. Binary logistic regression modeling demonstrated a combination of ESR, C3, white cell count, neutrophils, lymphocytes and IgG to be best for the identification of active LN (area under the curve 0.724). Conclusions At best, combining common classic blood biomarkers of lupus activity using multivariate analysis provides a 'fair' ability to identify active LN. Urine biomarkers were not included in these analyses. These results add to the concern that classic blood biomarkers are limited in monitoring discrete JSLE manifestations such as LN.

MCP1 triggers monocyte dysfunctions during abnormal osteogenic differentiation of mesenchymal stem cells in ankylosing spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory disease characterized by pathological osteogenesis and inflammation. However, the pathogenesis of AS and the pathological relationship between osteogenesis and inflammation in this disease remain largely unknown. Mesenchymal stem cells (MSCs) are multipotent progenitor cells capable of osteogenic differentiation and immunoregulation. Recently, we demonstrated that MSCs from AS patients (ASMSCs) have a greater potential for osteogenic differentiation than MSCs from healthy donors (HDMSCs), which therefore seems to be a component of pathological osteogenesis in AS. Previous studies have indicated that the immunoregulatory abilities of MSCs change following differentiation. However, the subsequent effects of ASMSCs during abnormal osteogenic differentiation are unclear. Here, we further demonstrated that ASMSCs secreted more monocyte chemoattractant protein 1 (MCP1) than HDMSCs during osteogenic differentiation. This enhanced MCP1 secretion augmented monocyte migration, increased classical macrophage polarization, and enhanced TNF-α secretion. Inhibiting MCP1 secretion from osteogenic differentiated ASMSCs using lentiviruses encoding short hairpin RNAs ameliorated these dysfunctions. Blocking the ERK1/2 pathway in ASMSCs with U0126 corrected the abnormal osteogenic differentiation, inhibited MCP1 overexpression, and prevented subsequent monocyte dysfunction. Finally, MCP1 expression was up-regulated during osteogenic differentiation in ASMSCs in vivo and was locally augmented in osteoblasts at ossification sites in AS patients. In summary, our study determined that MCP1 overexpression during abnormal osteogenic differentiation of ASMSCs triggers monocyte dysfunctions. We propose the novel hypothesis that pathological osteogenesis can lead to inflammation in AS. This hypothesis may contribute to reveal the precise pathological relationship between osteogenesis and inflammation in the field of osteoimmunology.

KEY MESSAGE

ASMSCs secreted more MCP1 during abnormal osteogenic differentiation. MCP1 overexpression leads to monocyte dysfunctions. Pathological osteogenesis can lead to inflammation in AS.

A discrete cluster of urinary biomarkers discriminates between active systemic lupus erythematosus patients with and without glomerulonephritis

Background

Management of lupus nephritis (LN) would be greatly aided by the discovery of biomarkers that accurately reflect changes in disease activity. Here, we used a proteomics approach to identify potential urinary biomarkers associated with LN.

Methods

Urine was obtained from 60 LN patients with paired renal biopsies, 25 active non-LN SLE patients, and 24 healthy controls. Using Luminex, 128 analytes were quantified and normalized to urinary creatinine levels. Data were analyzed by linear modeling and non-parametric statistics, with corrections for multiple comparisons. A second cohort of 33 active LN, 16 active non-LN, and 30 remission LN SLE patients was used to validate the results.

Results

Forty-four analytes were identified that were significantly increased in active LN as compared to active non-LN. This included a number of unique proteins (e.g., TIMP-1, PAI-1, PF4, vWF, and IL-15) as well as known candidate LN biomarkers (e.g., adiponectin, sVCAM-1, and IL-6), that differed markedly (>4-fold) between active LN and non-LN, all of which were confirmed in the validation cohort and normalized in remission LN patients. These proteins demonstrated an enhanced ability to discriminate between active LN and non-LN patients over several previously reported biomarkers. Ten proteins were found to significantly correlate with the activity score on renal biopsy, eight of which strongly discriminated between active proliferative and non-proliferative/chronic renal lesions.

Conclusions

A number of promising urinary biomarkers that correlate with the presence of active renal disease and/or renal biopsy changes were identified and appear to outperform many of the existing proposed biomarkers.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1120-0) contains supplementary material, which is available to authorized users.

Urinary sediment suggests lupus nephritis histology

Objectives

The objective of this paper was to evaluate correlations between kidney biopsy indexes (activity and chronicity) and urinary sediment findings; the secondary objective was to find which components of urinary sediment can discriminate proliferative from other classes of lupus nephritis.

Methods

Lupus nephritis patients scheduled for a kidney biopsy were included in our study. The morning before the kidney biopsy, we took urine samples from each patient. Receiver operating characteristic (ROC) curves were plotted to determine the area under the curve (AUC) of each test for detecting proliferative lupus nephritis; a classification tree was calculated to select a set of values that best-predicted lupus nephritis classes.

Results

We included 51 patients, 36 of whom were women (70.6%). Correlations of lupus nephritis activity index with the counts in the urinary sediment of erythrocytes (isomorphic and dysmorphic), acanthocytes, and leukocytes were 0.65 ( p < 0.0001) 0.62 ( p < 0.0001) and 0.22 ( p = 0.1228), respectively. Correlations of lupus nephritis chronicity index with the counts of erythrocytes, acanthocytes, and leukocytes were 0.60 ( p ≤ 0.0001), 0.52 ( p = 0.0001) and 0.17 ( p = 0.2300), respectively. Our classification tree had an accuracy of 84.3%.

Conclusions

Evaluation of urine sediment reflects lupus nephritis histology.

Monocyte chemoattractant protein-1 and the kidney

PURPOSE OF REVIEW

Recently, initial studies have been carried out in patients using monocyte chemoattractant protein-1 (MCP-1) inhibitors. This review summarizes the known function of MCP-1 in regulating monocytes during inflammation and its role in inflammatory disease of the kidney.

RECENT FINDINGS

MCP-1 is one of the first chemokines described and plays an important role in renal inflammatory disease. The function of MCP-1 has been investigated and analyzed in both animal models of renal disease and renal patients. MCP-1 mediates firstly the release of monocytes from the bone marrow, and then generates a gradient in the endothelial glycocalyx to direct monocytes to sites of inflammation, thereby alleviating the migration of blood leukocytes into the inflamed tissue. In addition, MCP-1 has direct signaling effects in monocytes and influences migration, proliferation, and differentiation of leukocytes. Blockade of MCP-1 in several models of renal disease has ameliorated the disease, suggesting that inhibition of MCP-1 is a promising and valid strategy to treat patients with renal inflammatory disease.

SUMMARY

Understanding the role of MCP-1 in monocyte homeostasis and the implications of MCP-1 inhibition in renal disease will help in designing better diagnostic and therapeutic strategies in patients with inflammatory renal disease.

Lupus nephritis biomarkers

Lupus nephritis (LN), a potentially destructive outcome of SLE, is a real challenge in the management of SLE because of the difficulty in diagnosing its subclinical onset and identifying relapses before serious complications set in. Conventional clinical parameters such as proteinuria, GFR, urine sediments, anti-dsDNA and complement levels are not sensitive or specific enough for detecting ongoing disease activity in lupus kidneys and early relapse of nephritis. There has long been a need for biomarkers of disease activity in LN. Such markers ideally should be capable of predicting early sub-clinical flares and could be used to gauge response to therapy, thus obviating the need for serial renal biopsies with their possible hazardous complications. Since urine can be readily obtained, it lends itself as an obvious biological substrate. In this review, the use of urine and serum as sources of lupus nephritis biomarkers is described, and the results of biomarker discovery studies using candidate and proteomic approaches are summarized.

Urinary biomarkers in childhood lupus nephritis

Juvenile-onset systemic lupus erythematosus (JSLE) is a rare, severe multisystem autoimmune disease affecting the kidney (Lupus Nephritis, LN) in up to 80% of children. LN is more severe in children than adults, with potential for irreversible kidney damage requiring dialysis or transplant. Renal biopsy is currently the gold standard for diagnosing and monitoring LN, however, it is invasive and associated with complications. Urine biomarkers have been shown to be better than serum biomarkers in differentiating renal disease from other organ manifestations. Over the past decade, there have been an increasing number of studies investigating specific candidate biomarkers implicated in the pathogenesis of LN or screening for urinary biomarkers using hypothesis free methods. In this review, developments in urine biomarkers for LN will be reviewed, highlighting those that are of relevance to children and have gone through validation in independent international patient cohorts, bringing them close to clinical translation.

Chemokines and Chemokine Receptors in the Development of Lupus Nephritis

Lupus nephritis (LN) is a major cause of morbidity and mortality in the patients with systemic lupus erythematosus (SLE), an autoimmune disease with damage to multiple organs. Leukocyte recruitment into the inflamed kidney is a critical step to promote LN progression, and the chemokine/chemokine receptor system is necessary for leukocyte recruitment. In this review, we summarize recent studies on the roles of chemokines and chemokine receptors in the development of LN and discuss the potential and hurdles of developing novel, chemokine-based drugs to treat LN.

Urinary neutrophil gelatinase-associated lipocalin for diagnosis and estimating activity in lupus nephritis: a meta-analysis

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) is relatively specific in lupus nephritis (LN) patients. However, its diagnostic value has not been evaluated. The aim of this review was to determine the value of uNGAL for diagnosis and estimating activity in LN. A comprehensive search was performed on PubMed, EMBASE, Web of Knowledge, Cochrane electronic databases through December 2014. Meta-analysis of sensitivity and specificity was performed with a random-effects model. Additionally, summary receiver operating characteristic (SROC) curves and area under the curve (AUC) values were calculated. Fourteen studies were selected for this review. With respect to diagnosing LN, the pooled sensitivity and specificity were 73.6% (95% confidence interval (CI), 61.9–83.3) and 78.1% (95% CI, 69.0–85.6), respectively. The SROC-AUC value was 0.8632. Regarding estimating LN activity, the pooled sensitivity and specificity were 66.2% (95% CI, 60.4–71.7) and 62.1% (95% CI, 57.9–66.3), respectively. The SROC-AUC value was 0.7583. In predicting renal flares, the pooled sensitivity and specificity were 77.5% (95% CI, 68.1–85.1) and 65.3% (95% CI, 60.0–70.3), respectively. The SROC-AUC value was 0.7756. In conclusion, this meta-analysis indicates that uNGAL has relatively fair sensitivity and specificity in diagnosing LN, estimating LN activity and predicting renal flares, suggesting that uNGAL is a potential biomarker in diagnosing LN and monitoring LN activity.

Anti-dsDNA antibody induces soluble fibronectin secretion by proximal renal tubular epithelial cells and downstream increase of TGF-β1 and collagen synthesis

The level of anti-dsDNA antibodies correlates with disease activity in lupus nephritis, but their role in pathogenic mechanisms remains to be defined. We investigated the effect of anti-dsDNA antibodies isolated from lupus nephritis patients on fibronectin synthesis and downstream fibrogenesis in proximal renal tubular epithelial cells (PTEC). Kidney biopsies were obtained from patients with active severe proliferative lupus nephritis. In vitro studies with cultured PTEC were performed to investigate the effect of human polyclonal IgG anti-dsDNA antibodies and mycophenolic acid (MPA). The role of IL-6, IL-8, MCP-1, TNF-α, TGF-β1, and MAPK and PKC signaling pathways on soluble and cell-associated fibronectin synthesis was investigated using neutralizing antibodies or specific inhibitors. The effect of exogenous endotoxin-free soluble fibronectin on downstream fibrotic processes was also examined. Fibronectin expression was markedly increased in the tubulo-interstitium of lupus nephritis renal biopsies and it co-localized with IgG deposition. Anti-dsDNA antibodies significantly increased both secreted and cell-associated fibronectin, through prior activation of ERK, p38 MAPK, JNK, PKC-α and PKC-βII. There was downstream induction of IL-6, IL-8, MCP-1, TNF-α and TGF-β1. MPA inhibited the induction of inflammatory and fibrotic processes by anti-dsDNA antibody. Exogenous soluble fibronectin induced TGF-β1 secretion and type I collagen synthesis in PTEC in a dose-dependent manner. Our data demonstrate that anti-dsDNA antibody contributes to tubulo-interstitial fibrosis in lupus nephritis through its action on PTEC. Anti-dsDNA antibody induces both cell-associated and soluble fibronectin secretion in PTEC, the former adds to extracellular matrix deposition while the latter amplifies the fibrotic process through induction of TGF-β1 and collagen type I. The pro-fibrotic effects of anti-dsDNA antibody are ameliorated by MPA.

Measuring eosinophiluria, urinary eosinophil cationic protein and urinary interleukin-5 in patients with Lupus Nephritis

BACKGROUND

Urine is increasingly becoming an attractive biological fluid in clinical practice due to being an easily obtained, non-invasive sampling method, containing proteins and peptides. The aim of this study was to investigate eosinophiluria, urinary eosinophil cationic protein (uECP) and urinary IL-5 (uIL-5) in patients with Lupus Nephritis.

METHODS

Seventy-four patients with SLE-20 with clinical and laboratory evidence of lupus nephritis (LN group) and 54 without evidence of renal involvement (non-LN group)-were analyzed regarding eosinophiluria, uECP and uIL-5. Eosinophiluria was observed by Hansel's stain, ECP by fluoroenzymeimmunoassay and uIL-5 by quantitative sandwich enzyme immunoassay. Both uECP and urinary IL-5 (uIL-5) were corrected by urinary creatinine. Eosinophiluria and uECP were compared with glomerular erythrocyturia, protein/creatinine ratio (Pr/Cr ratio), serum creatinine, estimated glomerular filtration rate (eGFR), anti-double-stranded DNA (anti-dsDNA), serum levels of complement (C3 and C4), uIL-5/Cr ratio, and SLE disease activity index.

RESULTS

Patients of the LN group had higher eosinophiluria, uECP, uECP/Cr ratio levels, and uIL-5 than patients of the non-LN group (p<0.001 for all). These variables showed a statistically significant correlation with glomerular erythrocyturia, casts, Pr/Cr ratio, serum creatinine, eGFR, anti-dsDNA, uIL-5/Cr, and SLE disease activity index (all p<0.05).

CONCLUSION

These results provide evidence of increased urinary eosinophils, ECP and IL-5 in patients with SLE and LN; uECP/Cr ratio showed better correlation with markers of renal function and SLE disease activity.

Impaired B cell inhibition by lupus bone marrow mesenchymal stem cells is caused by reduced CCL2 expression

Mesenchymal stem cells (MSC) from healthy human and normal mice can inhibit normal B cell proliferation, differentiation, and Ab secretion in vitro. However, it remains unknown whether MSC from lupus-like mice and patients with systemic lupus erythematosus (SLE) exhibit the same immunoregulatory activity as normal MSC for B cell inhibition and, if not, what the underlying molecular mechanism would be. In this study, we showed that bone marrow-derived MSCs from lupus-like mice and SLE patients had an impairment in suppressing normal B cell proliferation and differentiation, which was caused by the reduction of CCL2 levels. Knockdown of CCL2 in normal MSC damaged their suppressive capacity for B cells. Conversely, overexpression of CCL2 in lupus MSCs restored their immunoregulatory ability for B cells in vitro and ameliorated the pathology of lupus nephritis and serological changes in MRL/lpr mice in vivo. Mechanistically, MSC-mediated B cell inhibition was dependent on matrix metalloproteinase proteolytic processing of CCL2. These findings reveal a novel function of CCL2 in B cell regulation by MSCs and suggest that CCL2 manipulation on MSCs may serve as a potential pathway for developing the more effective MSC-based therapy in autoimmune diseases associated with B cell activation, such as SLE.

Yin and Yang of PDGF-mediated signaling pathway in the context of HIV infection and drug abuse

The control and eradication of neurological complications associated with AIDS continues to be an important goal in efforts toward improving the well being of HIV-infected patients. Although combined antiretroviral therapies have contributed significantly to increasing the longevity of patients by suppressing the virus burden in the systemic compartments, the prevalence of HIV-associated neurological disorders continues to be on the rise. This in turn, leads to an impaired quality of life of the infected individuals who continue to suffer from mild to moderate cognitive decline and memory loss. Developing therapeutic interventions that reverse neuronal injury in the context of HIV infection, is thus of paramount importance in the field. Our previous studies have demonstrated that platelet-derived growth factor (PDGF) has a neuroprotective potential against HIV envelope protein gp120 and Tat. Paradoxically, PDGF is also a cerebrovascular permeant with deleterious effects on the blood-brain barrier resulting in increased influx of monocytes in the CNS. Herein, we review the opposing roles of PDGF in the context of HIV-associated neurodegenerative disorder (HAND).

Urine biomarkers for monitoring juvenile lupus nephritis: a prospective longitudinal study

BACKGROUND

In juvenile-onset systemic lupus erythematosus (JSLE), renal involvement (lupus nephritis) is frequently seen and can result in long-term morbidity. This prospective longitudinal study aimed to identify the utility of standard and/or novel biomarkers for monitoring and predicting lupus nephritis in a real world setting.

METHODS

Using an unselected JSLE cohort, urine samples were collected during routine clinical review. Protein concentrations of urinary monocyte chemo-attractant protein 1 (uMCP1) and neutrophil gelatinase-associated lipocalin (uNGAL) were analysed along with standard disease activity markers, and were compared with current and subsequent disease activity.

RESULTS

JSLE patients (n = 64; median age 14.1 years) were seen at 3 (interquartile range: 2-5) clinical reviews over 364 (182-532) days. Multivariate analysis demonstrated uMCP1 and serum C3 as independent variables (p < 0.001) for active renal disease at the time of the current review. uMCP1 was an excellent predictor of improved renal disease over time (AUC: 0.81; p = 0.013). uNGAL was a good predictor of worsened renal disease activity (AUC 0.76; p = 0.04) over time.

CONCLUSION

Biomarkers (uMCP1, serum C3) can indicate current renal involvement in JSLE, whilst uMCP1 and uNGAL are able to predict subsequent renal disease activity changes. Moving towards biomarker-led monitoring may improve the renal outcome for our patients.

A study of hepcidin and monocyte chemoattractant protein-1 in Egyptian females with systemic lupus erythematosus

BACKGROUND

Lupus nephritis is one of the most serious manifestations of systemic lupus erythematosus (SLE). Novel biomarkers are necessary to enhance the diagnostic accuracy, prognostic stratification, monitoring of treatment response, and detection of early renal flares.

METHODS

Our study was conducted on 90 participants. They were divided into three groups, group I (controls) encompassed 30 ages and sex-matched healthy personnel. Group II included 30 non-nephritic SLE patients and finally group III included 30 SLE nephritic patients. Urinary monocyte chemoattractant protein-1 (UMCP-1) and hepcidin were evaluated by ELISA technique, compared and correlated in different groups, with each other and with other routine variables and with renal biopsy done to study group (III).

RESULTS

Both UMCP-1 and hepcidin in group III showed significant increase compared to other two groups (controls and group II) (468 ± 128, 111 ± 12, 252 ± 56 pg/ml, respectively, for UMCP-1 and 40 ± 12, 11 ± 2, 20 ± 5 ng/ml, respectively, for hepcidin, P < 0.01). Also both UMCP-1 and hepcidin in group III showed significant increase in diffuse proliferative subgroup compared to focal proliferative and mesangioproliferative subgroups (580 ± 43, 502 ± 46, and 352.6 ± 100 pg/ml, respectively, for UMCP-1 and 47.8 ± 9.5, 41.4 ± 6, and 32.9 ± 10.8 ng/ml, respectively, for urinary hepcidin, P < 0.05).

CONCLUSION

UMCP-1 and hepcidin could be associated with the susceptibility of lupus nephritis.

Chemokines as potential markers in pediatric renal diseases

Glomerular diseases and obstructive uropathies are the two most frequent causes of chronic kidney disease (CKD) in children. Recently, biomarkers have become a focus of clinical research as potentially useful diagnostic tools in pediatric renal diseases. Among several putative biomarkers, chemokines emerge as promising molecules since they play relevant roles in the pathophysiology of pediatric renal diseases. The evaluation of these inflammatory mediators might help in the management of diverse renal diseases in children and the detection of patients at high risk to develop CKD. The aim of this paper is to revise general aspects of chemokines and the potential link between chemokines and the most common pediatric renal diseases by including experimental and clinical evidence.

Use of biomarkers in the management of children with lupus

Childhood systemic lupus erythematosus (SLE) is known to have a worse prognosis than adult-onset disease, and monitoring and treatment of the disease are still a challenge. Thus, there is an urgent need for highly reliable, non-invasive biomarkers for early detection of relapses, to avoid long-term complications and to optimize the management of children with LN. Recent studies of pediatric patients have yielded novel specific biomarkers for SLE diagnosis which can be used for monitoring disease activity and response to treatment. The most promising biomarkers in juvenile-onset SLE include cell-bound complement activation products, some genomic profiles, and urinary proteins such as neutrophil gelatinase-associated lipocalin, monocyte chemoattractant protein-1, and alpha-1-acid glycoprotein. None of these might be suitable for use as a single SLE-biomarker. More likely a combination of novel biomarkers with traditionally used data, including autoantibodies and complement, might help to enhance sensitivity and specificity for early diagnosis, disease monitoring, and prediction of relapses.cp.

Urine biomarkers in juvenile-onset SLE nephritis

Over 80 % of patients with juvenile-onset systemic lupus erythematosus will have renal involvement compared to 40 % with adult-onset disease. Up to 44 % of children who do have lupus nephritis (LN) progress to renal failure in early adulthood. Improved methods of detecting onset of LN would allow earlier treatment, which may prevent irreversible renal scarring and a decline in renal function. Current conventional markers of disease activity fail to adequately predict renal lupus flares and include proteinuria, complement levels, anti-double-stranded DNA antibodies and serum creatinine concentrations. Standardized histological classification is currently the gold standard for diagnosing and classifying LN, but its invasive nature limits routine use for monitoring, especially in a childhood population. Novel biomarkers need to be sensitive and specific-and preferably non-invasive and cost-effective. The most promising biomarkers in juvenile-onset LN include urinary neutrophil gelatinase associated lipocalin, monocyte chemoattractant protein 1 and transforming growth factor-beta, although many others have been identified and are under investigation. No one biomarker yet discovered is unique to LN, indicating an overlap in disease pathophysiology. It is likely that a combination of biomarkers will be required for assessing disease flare detection, response to treatment and prognostic information. Potential biomarkers require longitudinal validation in large paediatric, prospective cohorts to assess their ability to act as clinically useful adjuncts.

Cytokines in chronic kidney disease: potential link of MCP-1 and dyslipidemia in glomerular diseases

BACKGROUND

Many studies have indicated a role for cytokines in chronic kidney disease (CKD). The aim of this study was to evaluate plasma and urinary levels of monocyte chemoattractant protein-1 (MCP-1/CCL2), transforming growth factor-beta1 (TGF-β1), and interleukin-8 (IL-8/CXCL8) in pediatric patients with CKD stages 2-4.

METHODS

Cytokines were measured in 37 healthy controls and in 42 CKD patients by enzyme-linked immunoassay. Patients were divided into groups according to CKD etiology: glomerular disease (group 1, n = 11) and congenital anomalies of the kidney and urinary tract (group 2, n = 31). Urinary cytokine measurements were standardized for creatinine.

RESULTS

Plasma and urinary levels of MCP-1/CCL2 were significantly higher in both CKD groups compared to the control group. Between the two CKD groups, only urinary MCP-1/CCL2 levels were significantly different, with MCP-1/CCL2 levels higher in group 1 patients. Plasma and urinary levels of IL-8/CXCL8 and TGF-β1 were undetectable in the control group but comparable between the two CKD groups. In group 1 patients, urinary MCP-1/CCL2 levels were negatively correlated to serum albumin levels and positively correlated to the levels of total cholesterol and triglycerides. In group 2 patients, urinary levels of IL-8/CXCL8 were negatively correlated with the estimated glomerular filtration rate and positively correlated with body mass index.

CONCLUSIONS

Differences in cytokine profiles may be related to CKD etiology and other disease-associated alterations.

Urinary angiostatin--a novel putative marker of renal pathology chronicity in lupus nephritis

There is a critical need to identify biomarkers for Systemic Lupus Erythematosus (SLE) which has a high prevalence of renal failure. When urine from patients with lupus nephritis was recently screened for the levels of ∼280 molecules using an exploratory array-based proteomic platform, elevated angiostatin levels were noted. Angiostatin is a bioactive fragment of plasminogen, and has been known to have modulatory function in angiogenesis and inflammation. The significant elevation in urinary angiostatin was next validated in an independent cohort of SLE patients (n = 100) using ELISA. Among patients with SLE, urine angiostatin was significantly increased in active SLE compared with inactive SLE, correlating well with the SLEDAI disease activity index and SLICC renal activity score (r = 0.66, p < 0.0001). ROC curve analysis further confirmed that urinary angiostatin had the capacity to discriminate patients with active SLE from those with inactive disease. Patients with Class IV lupus nephritis exhibited the highest levels of urinary angiostatin. Immunohistochemistry staining localized angiostatin expression to the renal tubular cells in these patients. Finally, when paired urine-kidney samples procured concurrently from patients with LN were next examined, urine angiostatin levels correlated strongly with the renal pathology chronicity index, but not with the activity index. Given that Class IV lupus nephritis and renal pathology chronicity changes forebode poor renal and patient survival, urinary angiostatin emerges as a novel noninvasive marker of renal disease in SLE. Longitudinal studies are in progress to further assess the disease-predictive potential of urinary angiostatin.

Platelet-derived growth factor (PDGF)-BB-mediated induction of monocyte chemoattractant protein 1 in human astrocytes: implications for HIV-associated neuroinflammation

Chemokine (C-C motif) ligand 2, also known as monocyte chemoattractant protein 1 (MCP-1) is an important factor for the pathogenesis of HIV-associated neurocognitive disorders (HAND). The mechanisms of MCP-1-mediated neuropathogenesis, in part, revolve around its neuroinflammatory role and the recruitment of monocytes into the central nervous system (CNS) via the disrupted blood-brain barrier (BBB). We have previously demonstrated that HIV-1/HIV-1 Tat upregulate platelet-derived growth factor (PDGF)-BB, a known cerebrovascular permeant; subsequently, the present study was aimed at exploring the regulation of MCP-1 by PDGF-BB in astrocytes with implications in HAND. Specifically, the data herein demonstrate that exposure of human astrocytes to HIV-1 LAI elevated PDGF-B and MCP-1 levels. Furthermore, treating astrocytes with the human recombinant PDGF-BB protein significantly increased the production and release of MCP-1 at both the RNA and protein levels. MCP-1 induction was regulated by activation of extracellular-signal-regulated kinase (ERK)1/2, c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein (MAP) kinases and phosphatidylinositol 3-kinase (PI3K)/Akt pathways and the downstream transcription factor, nuclear factor κB (NFκB). Chromatin immunoprecipitation (ChIP) assays demonstrated increased binding of NFκB to the human MCP-1 promoter following PDGF-BB exposure. Conditioned media from PDGF-BB-treated astrocytes increased monocyte transmigration through human brain microvascular endothelial cells (HBMECs), an effect that was blocked by STI-571, a tyrosine kinase inhibitor (PDGF receptor (PDGF-R) blocker). PDGF-BB-mediated release of MCP-1 was critical for increased permeability in an in vitro BBB model as evidenced by blocking antibody assays. Since MCP-1 is linked to disease severity, understanding its modulation by PDGF-BB could aid in understanding the proinflammatory responses in HAND. These results suggest that astrocyte activation by PDGF-BB exaggerates monocyte recruitment into the brain via MCP-1 and underscores the critical role astrocytes play in HAND.

Estrogen receptor-alpha mediates Toll-like receptor-2 agonist-induced monocyte chemoattractant protein-1 production in mesangial cells

TLR2 agonists are well known for inducing NF-kB activation and inflammation, while estrogen receptor-alpha (ER-α) is a regulator of estrogen-mediated anti-inflammatory responses. In the present work, we determined the role of ER-α and phosphorylated ER-α in TLR2 agonist-induced MCP1 production in mesangial cells. We found that TLR2 agonists induced nuclear localization of phospho-ER-α (serine 118), and estrogen and TLR2 agonists both induced phosphorylation of ER-α at the serine 118 and 104/106 positions. Incubation of MRL/lpr mesangial cells with estrogen was found to attenuate TLR2 agonist-mediated MCP1 production. To determine the mode of action of ER-α/pER-α (serine-118), we used the ER-α inhibitor MPP and transfected mesangial cells with ER-α siRNA. ER-α inhibition was found to decrease MCP1 production in mesangial cells. Thus, ER-α/pER-α is an intermediate regulator for both TLR2-mediated MCP1 production during inflammation and estrogen-mediated anti-inflammatory signals in mesangial cells.

Autoantibodies in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multifactorial disorder with multigenic inheritance and various environmental factors implicated in its aetiopathogenesis. Despite the multiple mechanisms involved in the aetiology of SLE being elusive, recent studies have made progress in our understanding of the pathogenic mechanisms via abnormal regulation of cell-mediated and humoral immunity that lead to tissue damage. The heterogeneity of the clinical manifestations probably reflects the complexity of the disease pathogenesis itself. The immune system in SLE is characterised by a complex interplay between overactive B cells, abnormally activated T cells and antigen-presenting cells. This interplay leads to the production of an array of inflammatory cytokines, apoptotic cells, diverse autoantibodies and immune complexes that in turn activate effector cells and the complement system, leading to tissue injury and damage which are the hallmarks of the clinical manifestations. SLE patients have dysregulation of inflammatory cytokines, chemokines and immune response-related genes, as well as of the genes involved in apoptosis, signal transduction and the cell cycle.

Role of TWEAK in lupus nephritis: a bench-to-bedside review

There is significant unmet need in the treatment of lupus nephritis (LN) patients. In this review, we highlight the role of the TWEAK/Fn14 pathway in mediating key pathologic processes underlying LN involving both glomerular and tubular injury, and thus the potential for renal protection via blockade of this pathway. The specific pathological mechanisms of TWEAK - namely promoting inflammation, renal cell proliferation and apoptosis, vascular activation and fibrosis - are described, with supporting data from animal models and in vitro systems. Furthermore, we detail the translational relevance of these mechanisms to clinical readouts in human LN. We present the opportunity for an anti-TWEAK therapeutic as a renal protective agent to improve efficacy relative to current standard of care treatments hopefully without increased safety risk, and highlight a phase II trial with BIIB023, an anti-TWEAK neutralizing antibody, designed to assess efficacy in LN patients. Taken together, targeting the TWEAK/Fn14 axis represents a potential new therapeutic paradigm for achieving renal protection in LN patients.

Increased serum concentration of sphingosine-1-phosphate in juvenile-onset systemic lupus erythematosus

PURPOSE

Sphingosine-1-phosphate (S1P) is an active sphingolipid with chemotactic abilities and has been linked to inflammatory mediators and autoimmune disease. The aim of this study was to assess whether children with juvenile-onset systemic lupus erythematosus (JSLE) express increased systemic and/or urinary concentrations of S1P.

METHODS

A subgroup of patients participating in the UK JSLE Cohort Study, were invited to participate. Cross sectional serum and urine samples were prospectively collected along with demographic and standard clinical data. Results were compared to a cohort of disease controls (Henoch Schonlein Purpura; HSP) and healthy controls (HC).

RESULTS

The median age of JSLE patients (n = 15) was 13.6 years (7.2-16.9 years). The serum concentrations of S1P in JSLE patients (7.4 uM, IQR 6.3-12.3 uM) were statistically significantly increased when compared to patients with HSP (n = 10; 5.2 uM, IQR 4.0-7.9 uM; p = 0.016) and HCs (n = 10; 3.8 uM, IQR 2.1-5.8 uM; p = 0.003). There was a trend towards increased serum S1P concentrations between patients with active lupus nephritis (n = 8; 8.7 uM, IQR 6.2-15.3 uM) compared to lupus non-nephritis (n = 7; 6.6 uM, IQR 6.3-10.6 uM; p = 0.355). No relationship was found between disease activity markers and S1P. Urine S1P concentrations were no different between JSLE patients (56.0 nM, IQR 40.3-96.6 nM) and HCs (58.7 nM, IQR 0-241.9 nM; p = 0.889).

CONCLUSIONS

We have demonstrated, for the first time, an increased serum concentration of S1P in a cohort of JSLE patients. These findings highlight a role of S1P in the pathophysiology of JSLE that warrants further investigation.

Mechanisms of tissue injury in lupus nephritis

Systemic lupus erythematosus is a prototypic autoimmune disease characterized by autoantibody production and immune complex formation/deposition in target organs such as the kidney. Resultant local inflammation then leads to organ damage. Nephritis, a major cause of morbidity and mortality in patients with lupus, occurs in approximately 50% of lupus patients. In the present review, we provide an overview of the current research and knowledge concerning mechanisms of renal injury in both lupus-prone mouse models and human lupus patients.

Urinary monocyte chemoattractant protein 1 and alpha 1 acid glycoprotein as biomarkers of renal disease activity in juvenile-onset systemic lupus erythematosus

A higher proportion of patients with juvenile-onset systemic lupus erythematosus (JSLE) will have renal involvement compared with adult-onset disease, some progressing to renal failure in adulthood. Histological examination is the gold standard for diagnosing lupus nephritis (LN), but its invasive nature limits routine use. Using cross-sectional cohort analysis, we aimed to determine whether urinary concentrations of monocyte chemoattractant protein-1 (MCP1), alpha-1-acid glycoprotein (AGP) and interferon-inducible protein 10 (IP10) are biomarkers of active LN. Sixty JSLE patients recruited to the UK JSLE Cohort Study were categorized according to the British Isles Lupus Assessment Group (BILAG) activity index. Patients with active renal JSLE (n = 8; renal BILAG score A, B) had significantly higher urinary MCP1 concentrations than patients with inactive renal disease (n = 52; renal BILAG score C, D, E; 582 pg/mg creatinine [Cr], 207 pg/mg Cr; p = 0.018) or healthy controls (n = 23; 117 pg/mg Cr; p = 0.005). Urinary AGP concentration was significantly elevated in patients with active renal disease compared with inactive renal disease (1517 ng/mg Cr, 485 ng/mg Cr; p = 0.027) or healthy controls (313 ng/mg Cr; p = 0.013). Urinary IP10 concentration was not significantly different between groups, but did strongly correlate with uMCP and uAGP levels (rho = 0.38, p = 0.009; rho = 0.33, p = 0.021). Urinary MCP1 and AGP are biomarkers of LN, providing insight into its pathophysiology. Longitudinal studies are warranted.

Urinary monocyte chemoattractant protein-1 in renal disease

Monocyte chemoattractant protein-1 (MCP-1/CCL2) has a critical role in the development of various renal diseases. Data from disease specific experimental animal models and clinical studies confirm that MCP-1 plays an important part in the pathogenesis of renal diseases. The action of MCP-1 in these studies has been shown to be more complex than the traditional concept of monocyte/macrophage recruitment to the inflammatory site. MCP-1 is expressed in renal tissues and it is detectable in urine of patients with a variety of renal diseases. Measurement of urinary levels of MCP-1 can provide valuable information not only for the diagnosis of active renal disease, but also for monitoring of response to therapy. Urinary MCP-1 measurement can provide help with evaluation of the prognosis in various renal diseases. Furthermore, selective targeting of MCP-1 could be an effective treatment in suppressing a number of renal diseases as blocking MCP-1 has already been shown to ameliorate renal diseases in experimental animal models. The advantage of measuring urinary MCP-1 rather than the conventional markers must now be validated using a larger cohort of patients in different renal diseases. Also the therapeutic potential of MCP-1 targeting agents needs to be investigated in clinical studies.

Markers of childhood lupus nephritis indicating disease activity

Current treatment regimens for childhood lupus nephritis (LN) are associated with significant side-effects and toxicity in vulnerable phases of growth and development. The paucity of biomarkers particularly in childhood impedes the appropriate clinical management and the development of new therapeutics. We analyzed markers of immune system (BAFF, RANTES), complement (Bb, C1q, C3d-CIC, C5a) and endothelial cell activation (sVCAM-1) in children with LN (n=22, mean age 14.8±4.7 years), nephrotic syndrome (n=13) and age-matched healthy controls (n=20) to define parameters that correlate with LN activity. Complement fragments of the alternative (Bb, p=0.0004) classical (C3d-CIC, p<0.0001) and common pathway (C5a, p<0.0001) and the levels of BAFF (p<0.0001), RANTES (p=0.0002) and sVCAM-1 (p=0.0004) were significantly higher in active compared to inactive LN. Activation of complement was associated with the occurrence of anti-C1q antibodies and reduced complement C1q. Complement-activation fragments highly correlated with the markers for immune system and endothelial cell activation. The ensemble of these parameters may be of great value in identifying early flares or remissions of childhood LN, and moreover may prove useful in the assessment of new treatments and in determining the optimization of their use.