Urine Biomarkers to Predict Response to Lupus Nephritis Therapy in Children and Young Adults

Efficacy and Safety of Pharmacokinetically-Driven Dosing of Mycophenolate Mofetil for the Treatment of Pediatric Proliferative Lupus Nephritis-A Double-Blind Placebo Controlled Clinical Trial (The Pediatric Lupus Nephritis Mycophenolate Mofetil Study)

Background

The safety and efficacy of mycophenolate mofetil (MMF) for lupus nephritis (LN) treatment is established in adults and in some children. MMF is rapidly converted to the biologically active metabolite mycophenolic acid (MPA) whose pharmacokinetics (PK) is characterized by large inter- and intra-individual variability.

Methods/Design

This randomized, double-blind, active comparator, controlled clinical trial of pediatric subjects with proliferative LN compares pharmacokinetically-guided precision-dosing of MMF (MMFPK, i.e. the dose is adjusted to the target area under the concentration-time curve (AUC0-12h) of MPA ≥ 60-70 mg*h/L) and MMF dosed per body surface area (MMFBSA, i.e. MMF dosed 600 mg/m2 body surface area), with MMF dosage taken about 12 hours apart. At baseline, subjects are randomized 1:1 to receive blinded treatment with MMFPK or MMFBSA for up to 53 weeks. The primary outcome is partial clinical remission of LN (partial renal response, PRR) at week 26, and the major secondary outcome is complete renal response (CRR) at week 26. Subjects in the MMFBSA arm with PRR at week 26 will receive MMFPK from week 26 onwards, while subjects with CRR will continue MMFBSA or MMFPK treatment until week 53. Subjects who achieve PRR at week 26 are discontinued from study intervention.

Discussion

The Pediatric Lupus Nephritis Mycophenolate Mofetil (PLUMM) study will provide a thorough evaluation of the PK of MMF in pediatric LN patients, yielding a head-to-head comparison of MMFBSA and MMFPK for both safety and efficacy. This study has the potential to change current treatment recommendations for pediatric LN, thereby significantly impacting childhood-onset SLE (cSLE) disease prognosis and current clinical practice.

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.

Bibliometric analysis of lupus nephritis in children from 1999 to 2022: A review

Lupus nephritis (LN) is a complication of systemic lupus erythematosus and a damaging disease of the kidney. The injury of LN in children is more serious than that in adults. However, the literature in this field is numerous and complex, which brings great challenges for researchers to extract information. The purpose of this study is to carry out bibliometric analysis and visualization of published literatures, and identify current research hotspots and future research trends in this field. Literature was retrieved from the Web Of Science database from 1999 to 2022. The literature was analyzed and visualized using Citespace 6.1.R6, VOSviewer 1.6.18, and Microsoft Excel 2019. A total of 1059 articles were included in this study. In the past 13 years, an increase in the number of publications every year. Brunner HI is the author with the highest number of published and cited papers in this field, followed by Wenderfer SE. The United States and China are the countries with the highest number of published papers. University Toronto is the most productive institution, followed by University Cincinnati. The most prolific journal was Pediatric nephrology (IF 2.67), followed by lupus (IF 2.21). Lupus was cited the most, followed by Pediatric nephrology. The keyword burst showed the earliest and longest burst was antiphospholipid antibody, validation/risk/rituximab/safety is the current research hotspot. The article with the highest number of citations was Hochberg MC 1997 published in Arthritis Rheum. This study provides valuable information summary for the field of LN in children, which is helpful to strengthen the cooperation among countries, institutions and authors, and promote the research in the field of LN in children.

External Validation of a Urinary Biomarker Risk Score for the Prediction of Steroid Responsiveness in Adults With Nephrotic Syndrome

Introduction

In idiopathic nephrotic syndrome, response to corticosteroids remains the best indicator of prognosis. Noninvasive markers to predict a patient's response to steroids would allow improved prognostication and a more personalized approach to management. We have previously derived a urinary biomarker risk score which can differentiate steroid sensitive nephrotic syndrome (SSNS) from steroid resistant nephrotic syndrome (SRNS) in children. The goal of this study was to validate this previously derived biomarker risk score in a cohort of steroid-naïve adult patients, to determine whether the panel could be used to predict steroid responsiveness at the time of initial diagnosis.

Methods

In this external validation study, clinical data, and urinary specimens (obtained before initiation of steroid treatment) from adult patients were used in the Nephrotic Syndrome Study Network (NEPTUNE) cohort. A panel of 5 previously identified and validated urinary biomarkers, including neutrophil gelatinase-associated lipocalin (NGAL), vitamin D binding protein (VDBP), Fetuin-A (FetA), Transthyretin (TTR), and alpha-1 acid glycoprotein 2 (AGP2) was measured. A summary risk score for steroid resistance was calculated based on biomarker concentrations. Receiver operating characteristic curves were created for each log-transformed biomarker concentration and for the individual and combined biomarker risk score.

Results

The urine biomarker risk score predicted development of steroid resistance, with optimal sensitivity and specificity of 0.74, and area under the receiver operating characteristic curve (AUC) of 0.79 using both absolute and creatinine-corrected concentrations.

Conclusion

This study validates the previously derived urinary biomarker risk score to predict steroid resistance in adult patients with nephrotic syndrome at initial diagnosis.

Measurement of Urinary Gc-Globulin by a Fluorescence ELISA Technique: Method Validation and Clinical Evaluation in Septic Patients-A Pilot Study

A major complication of sepsis is the development of acute kidney injury (AKI). In case of acute tubular damage, Gc-globulin, a known serum sepsis marker is increasingly filtrated into the urine therefore, urinary Gc-globulin (u-Gc) levels may predict septic AKI. We developed and validated a competitive fluorescence ELISA method for u-Gc measurement. Serum and urine samples from septic patients were collected in three consecutive days (T1, T2, T3) and data were compared to controls. Intra- and interassay imprecisions were CV < 14% and CV < 20%, respectively, with a recovery close to 100%. Controls and septic patients differed (p < 0.001) in their u-Gc/u-creatinine levels at admission (T1, median: 0.51 vs. 79.1 µg/mmol), T2 (median: 0.51 vs. 57.8 µg/mmol) and T3 (median: 0.51 vs. 55.6 µg/mmol). Septic patients with AKI expressed higher u-Gc/u-creatinine values than those without AKI at T1 (median: 23.6 vs. 136.5 µg/mmol, p < 0.01) and T3 (median: 34.4 vs. 75.8 µg/mmol, p < 0.05). AKI-2 stage patients exhibited more increased u-Gc/u-creatinine levels at T1 (median: 207.1 vs. 53.3 µg/mmol, p < 0.05) than AKI-1 stage individuals. Moderate correlations (p < 0.001) were observed between u-Gc/u-creatinine and se-urea, se-creatinine, se-hsCRP, WBC, u-total protein, u-albumin, u-orosomucoid/u-creatinine, and u-Cystatin C/u-creatinine levels. U-Gc testing may have a predictive value for AKI in septic patients.

Urine proteomics by mass spectrometry identifies proteins involved in key pathogenic pathways in patients with juvenile dermatomyositis

OBJECTIVES

To identify and validate biomarkers in JDM patients using a multiplexing tandem mass tag urine proteome profiling approach.

METHODS

First morning void urine samples were collected from JDM patients (n = 20) and healthy control subjects (n = 21) and processed for analysis using a standardized liquid chromatography-tandem mass spectrometry approach. Biomarkers with significantly altered levels were correlated with clinical measures of myositis disease activity and damage. A subset of candidate biomarkers was validated using commercially available ELISA kits.

RESULTS

In total, 2348 proteins were detected in the samples, with 275 proteins quantified across all samples. Among the differentially altered proteins, cathepsin D and galectin-3 binding protein were significantly increased in the urine of JDM patients (adjusted P < 0.05), supporting previous findings in myositis patients. These two candidate biomarkers were confirmed with ELISAs. Cathepsin D positively correlated with Myositis Damage Index (r = 0.57, P < 0.05) and negatively correlated with the Childhood Myositis Assessment Scale (r = -0.54, P < 0.05). We also identified novel JDM candidate biomarkers involved with key features of myositis, including extracellular matrix remodelling proteins.

CONCLUSION

This study confirmed the presence of several proteins in the urine of JDM patients that were previously found to be elevated in the blood of myositis patients and identified novel candidate biomarkers that require validation. These results support the use of urine as a source for biomarker development in JDM.

Urine biomarker score captures response to induction therapy with lupus nephritis

BACKGROUND

The Renal Activity Index for Lupus (RAIL) consists of urine protein assessment of neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, monocyte chemotactic protein 1, adiponectin, hemopexin, and ceruloplasmin, which non-invasively identifies lupus nephritis (LN). We aimed to delineate RAIL scores with inactive versus active LN and changes over time with response to LN induction therapy.

METHODS

There were 128 pediatric patients with systemic lupus erythematosus (SLE) and age-matched healthy controls recruited in a prospective case control study, with kidney biopsy confirmation of LN. Laboratory and clinical information was recorded and urine collected at diagnosis and end of induction and during maintenance therapy. Response to therapy was assessed by repeat kidney biopsy or laboratory parameters. Urine was assayed for RAIL biomarkers and the RAIL score calculated.

RESULTS

Pediatric RAIL (pRAIL) scores from 128 children and young adults with SLE (with/without LN: 70/38) including 25 during LN induction therapy, differentiated clinically active LN from inactive LN or without LN, and controls (all p < 0.0017). pRAIL scores significantly decreased with complete LN remission by 1.07 ± 1.7 (p = 0.03).

CONCLUSIONS

The RAIL biomarkers differentiate LN patients based on activity of kidney disease, with decreases of ≥ 1 in pRAIL scores indicating complete response to induction therapy. Significantly lower RAIL scores in healthy controls and in SLE patients without known LN raise the possibility of subclinical kidney disease. A higher resolution version of the Graphical abstract is available as Supplementary information.

Usefulness of the lupus low disease activity state as a treatment target in childhood-onset SLE

OBJECTIVE

Treat-to-target (T2T) strategies are advocated to improve prognosis in childhood-onset SLE (cSLE). Proposed T2T states include SLEDAI score of <4 (SLEDAI-LD), limited corticosteroid use (low-CS), and lupus low disease activity state (LLDAS). We sought to compare T2T states for their association with cSLE prognosis under consideration of relevant disease characteristics such as pre-existing damage, race and lupus nephritis (LN).

METHODS

Longitudinal data from 165 patients enrolled in the Cincinnati Lupus Registry were included. LN presence was based on renal biopsy, and patients were followed up until 18 years of age.

RESULTS

The 165 patients (LN: 45, white: 95) entered the registry within a median of 0 (IQR: 0-1) year post diagnosis and were followed up for a median of 4 (IQR: 2-5) years during which 80%, 92% and 94% achieved LLDAS, low-CS and SLEDAI-LD. Patients with LN were significantly less likely to achieve any T2T state (all p<0.03) and required a significantly longer time to reach them (all p<0.0001). Over the study period, patients maintained low-CS, SLEDAI-LD or LLDAS for a median of 76% (IQR: 48%-100%), 86% (IQR: 55%-100%) or 39% (IQR: 13%-64%) of their follow-up. Significant predictors of failure to maintain LLDAS included LN (p≤0.0062), pre-existing damage (p≤0.0271) and non-white race (p≤0.0013). There were 22%, 20% and 13% of patients who reached SLEDAI-LD, CS-low and LLDAS and nonetheless acquired new damage. Patients with LN had a higher risk of new damage than patients without LN even if achieving low-CS (p=0.009) or LLDAS (p=0.04).

CONCLUSIONS

Patients with LN and pre-existing damage are at higher risk of increased future damage acquisition, even if achieving a T2T state such as LLDAS. Among proposed common T2T states, the LLDAS is the hardest to achieve and maintain. The LLDAS may be considered the preferred T2T measure as it conveys the highest protection from acquiring additional disease damage.

Current views on lupus in children

PURPOSE OF REVIEW

This manuscript provides an update on clinical and pathophysiological features of juvenile-onset systemic lupus erythematosis (jSLE), challenges applying adult-derived classification criteria, and recent advances in treatment and care.

RECENT FINDINGS

Significant scientific advances have improved the understanding of genetic factors (both genetic causes and risk alleles) and associated phenotypic features. Panels of urine/blood biomarker candidates aid in diagnosing jSLE, monitoring disease activity and predicting treatment response. Available classification criteria have been extensively assessed, with differences in clinical and immunological phenotypes of patients across age groups and ethnicities affecting their performance in jSLE. Therapeutic options remain limited and are based on protocols for adult-onset SLE patients. International efforts to inform development of a treat-to-target (T2T) approach for jSLE have yielded cohort-level evidence that target attainment reduces the risk of severe flare and new damage, and treatment compliance.

SUMMARY

Recent studies have significantly improved our understanding of jSLE pathogenesis, highlighting important differences between jSLE and adult SLE, and providing the basis of biomarker development and target-directed individualized treatment and care. Future work focused on development of a T2T approach in jSLE is eagerly awaited.

The first-year course of urine MCP-1 and its association with response to treatment and long-term kidney prognosis in lupus nephritis

OBJECTIVES

The present study aims to assess the course of uMCP-1 and its association with response to therapy and long-term kidney function in a prospective cohort of adults who received a kidney biopsy for suspicion of active lupus nephritis (LN).

METHODS

Subjects were segregated into a histologically active LN group and a histologically chronic LN group. Both groups were followed for > = 36 months and urine were collected at flare, 3, 6, and 12 months of follow-up. The association between the course of uMCP-1, response to treatment, and progression to 30% loss of the eGFR was evaluated by linear mixed models for repeated measures.

RESULTS

A kidney biopsy was performed on 125 subjects. In 114, the report was consistent with histologically active LN; in 11, with histologically chronic LN. Urine MCP-1 levels were significantly higher in the active LN than in the chronic LN group. Urine MCP-1 levels correlated with the histological findings of cellular crescents, endocapillary hypercellularity, interstitial inflammation, glomerular sclerosis, interstitial fibrosis, and tubular atrophy. The mean estimates of uMCP-1 at flare were higher in the non-response group than in the complete response group, and decreased in the complete/partial response groups by the third month, while they remained elevated in the non-response group. The mean estimates for uMCP-1 were higher at LN flare and remained elevated in patients who progressed to loss of 30% of the eGFR, while they decreased in patients with stable kidney function.

CONCLUSION

The first-year course of uMCP-1 is associated with response to therapy and kidney survival in LN. Key Points •Urine MCP-1 levels differentiate histologically-active lupus nephritis from histologically-chronic lupus nephritis •Urine MCP-1 levels decrease by 3 months of therapy in subjects with a favorable response whose kidney function remains stable long-term •Urine MCP-1 levels remain elevated during the first year of therapy in subjects the will later lose kidney function.

Urinary HER2, TWEAK and VCAM-1 levels are associated with new-onset proteinuria in paediatric lupus nephritis

Objective

Lupus nephritis is a key driver of morbidity and mortality in SLE. Detecting active nephritis on a background of pre-existing renal damage is difficult, leading to potential undertreatment and accumulating injury. An unmet need is a biomarker that distinguishes active lupus nephritis, particularly important in paediatrics where minimising invasive procedures is desirable.

Methods

This was a multicentre, prospective study of 113 paediatric patients with biopsy-proven lupus nephritis. Clinical data and urine were obtained every 3–4 months and patients averaged 2 years on study with seven time points. Urine was analysed for human epidermal growth factor receptor 2 (HER2), tumour necrosis factor-like weak inducer of apoptosis and vascular cell adhesion molecule-1 (VCAM-1) by ELISA. We defined active disease as either a rise in serum creatinine ≥0.3 mg/dL from baseline or a rise in renal Systemic Lupus Erythematosus Disease Activity Index score from the previous visit. These markers were also studied in patients with acute kidney injury, juvenile idiopathic arthritis (JIA), amplified pain syndrome and healthy controls.

Results

The rate of active disease was 56% over an average of 2 years of follow-up. HER2 and VCAM-1 were significantly elevated at time points with active disease defined by increased serum creatinine compared with time points with inactive disease or patients who never flared. All three biomarkers were associated with new-onset proteinuria and VCAM-1 was elevated at time points preceding new-onset proteinuria. These biomarkers were not increased in acute kidney injury or JIA.

Conclusion

All three biomarkers were associated with new onset proteinuria and increased VCAM-1 may predict impending proteinuria. These biomarkers provide potential non-invasive measures for monitoring that may be more sensitive to impending flare than conventional measures.

Stability of novel urinary biomarkers used for lupus nephritis

Background

The Renal Activity Index for Lupus (RAIL) is a composite score of six urinary biomarkers (neutrophil gelatinase-associated lipocalin (NGAL), monocyte chemoattractant protein-1 (MCP-1), kidney injury molecule-1 (KIM-1), ceruloplasmin, adiponectin, and hemopexin) used to monitor lupus nephritis activity in children. We tested stability of RAIL biomarkers prior to meaningful clinical use.

Methods

Urine samples were tested by ELISA under shipping conditions, freeze/thaw, ambient and longer-term storage. Statistical analysis was performed via Deming Regression, Bland-Altman and Spearman Correlation Coefficient.

Results

Biomarker concentration were comparable to freshly collected urine following storage at -80 °C for up to 3 months, and at 4 or 25 °C up to 48 h followed by -80 °C. Neither shipping on dry or wet ice exposure nor addition of two freeze-thaw cycles led to loss of signal, with excellent Spearman Correlation coefficients under all conditions.

Conclusions

RAIL biomarkers are stable following short-term storage at clinically relevant conditions.

Identification and Validation of a Urinary Biomarker Panel to Accurately Diagnose and Predict Response to Therapy in Lupus Nephritis

Background

We have previously shown that 15 urinary biomarkers (of 129 tested by Luminex), discriminate between active Lupus Nephritis (ALN) and non-LN patients. The aim of this study was to evaluate the ability of these 15 previously-identified urinary biomarkers to predict treatment responses to conventional therapy, and for the most predictive of these biomarkers to validate their utility to identify ALN patients in an independent prospectively-acquired lupus cohort.

Methods

Our study had a 3-stage approach. In stage 1, we used Luminex to examine whether our previously identified urinary biomarkers at the time of the renal flare ( ± 3 months) or 12 ± 3 months after treatment of biopsy-proven ALN could predict treatment responses. In stage 2, a larger prospectively-acquired cross-sectional cohort was used to further validate the utility of the most predictive urinary biomarkers (identified in stage 1) to detect ALN patients. In this 2^nd stage, cut-offs with the best operating characteristics to detect ALN patients were produced for each biomarker and different combinations and/or numbers of elevated biomarkers needed to accurately identify ALN patients were analyzed. In stage 3, we aimed to further corroborate the sensitivity of the cut-offs created in stage 2 to detect ALN patients in a biopsy-proven ALN cohort who had a urine sample collection within 3 months of their biopsy.

Results

Twenty-one patients were included in stage 1. Twelve (57.1%), 4 (19.1%), and 5 (23.8%) patients had a complete (CR), partial (PR) and no (NR) remission at 24 ± 3 months, respectively. The percentage decrease following 12 ± 3 months of treatment for Adiponectin, MCP-1, sVCAM-1, PF4, IL-15 and vWF was significantly higher in patients with CR in comparison to those with PR/NR. In stage 2, a total of 247 SLE patients were included, of which 24 (9.7%) had ALN, 79 (31.9%) had LN in remission (RLN) and 144 (58.3%) were non-LN (NLN) patients. Based on the combinations of biomarkers with the best operating characteristics we propose “rule out” and “rule in” ALN criteria. In stage 3, 53 biopsy-proven ALN patients were included, 35 with proliferative LN and 18 with non-proliferative ALN, demonstrating that our “rule in ALN” criteria operate better in detecting active proliferative than non-proliferative classes.

Conclusions

Our results provide further evidence to support the role of Adiponectin, MCP-1, sVCAM-1 and PF4 in the detection of proliferative ALN cases. We further show the clinical utility of measuring multiple rather than a single biomarker and we propose novel “rule in” and “rule out” criteria for the detection of proliferative ALN with excellent operating characteristics.

Different roles of urinary light chains and serum light chains as potential biomarkers for monitoring disease activity in systemic lupus erythematosus

Objective

The assessment system for monitoring systemic lupus erythematosus (SLE) disease activity is complex and lacks reliable laboratory indicators. It is necessary to find rapid and noninvasive biomarkers. The aim of this study was to screen and identify the differentially expressed proteins in urine samples between active SLE and stable SLE and to further explore the expression of light chains.

Methods

First, we used a label-free quantitative proteomics approach to establish the urine protein expression profile of SLE, and then screened differentially expressed proteins. Subsequently, the expression of overall light chains was examined by immunofixation electrophoresis and immunoturbidimetric methods, respectively.

Results

Mass spectrometry data analysis found a total of 51 light chain peptides in the urinary protein expression spectrum, of which 27 light chain peptides were differentially expressed between the two groups. The largest difference was IGLV5-45 located in the variable region of the immunoglobulin Lambda light chain. The levels of urinary light chains and serum light chains were both significantly elevated in active SLE, and the levels of urinary light chains increased with the severity of disease activity.

Conclusions

The measurement of light chains would help to monitor SLE disease activity. Serum light chains had better discriminatory capacity than urinary light chains, while urine light chains were closely related to the severity of disease activity and could be used for dynamically monitoring the progress of disease activity.

Clinical measurement of lupus nephritis activity is inferior to biomarker-based activity assessment using the renal activity index for lupus nephritis in childhood-onset systemic lupus erythematosus

OBJECTIVES

The renal activity index for lupus (RAIL) measures lupus nephritis (LN) activity considering urine levels of 6 biomarkers (neutrophil gelatinase-associated lipocalin, monocyte chemoattractant protein-1, kidney injury molecule-1, adiponectin, haemopexin, ceruloplasmin). We aimed to compare the accuracy of the RAIL and the renal domain-score of the SLE disease activity index (rSLEDAI) in detecting LN activity.

METHODS

Random urine samples of patients with childhood-onset SLE with and without LN were assayed and scores of the RAIL, and RAIL standardised for urine creatinine (RAIL-Cr) were calculated. Clinical LN activity was measured by the rSLEDAI, and histological activity of LN was categorised as inactive/low-moderate/high for National Institute of Health-activity index scores of <2/2-10/>10, respectively.

RESULTS

115 patients were included in the analysis (47 patients without and 68 with LN). RAIL, RAIL-Cr and rSLEDAI scores at the time (±3 months) of kidney biopsy were available for 32 patients. Median rSLEDAI, RAIL and RAIL-Cr values were 4, -0.04, 0.02 for inactive LN, 12, 0.7 and 0.9 for low-moderate LN activity and 12, 2 and 1.8 for high LN activity, respectively. The area under the receiver operating characteristic curve (AUC) to capture high LN activity was the lowest for the rSLEDAI (AUC=0.62), followed by the RAIL-Cr (AUC=0.73) and RAIL (AUC=0.79). Notably, when testing urine samples collected during routine clinic visits remote (>3 months) from a kidney biopsy, 50% patients with rSLEDAI scores of 0 had RAIL scores reflecting low-moderate LN activity.

CONCLUSION

Monitoring of renal inflammation in children and adolescents with SLE can be improved by the measurement of urine biomarkers. The RAIL may constitute important auxiliary tool for the surveillance of LN in a clinical setting and assist with the decision to obtain a kidney biopsy.

Predicting treatment response and clinicopathological findings in lupus nephritis with urine epidermal growth factor, monocyte chemoattractant protein-1 or their ratios

Introduction

There is a need for sensitive and specific biomarkers to predict kidney damage and therapeutic response in lupus nephritis (LN). Monocyte chemoattractant protein-1 (MCP-1) and epidermal growth factor (EGF) are cytokines with divergent roles. EGF or EGF/MCP1 ratio have been shown to correlate with prognosis in primary glomerulonephritis, but there is limited information in lupus nephritis (LN). This study evaluated the roles of MCP-1, EGF or their ratio as biomarkers of histopathology and response to treatment in LN.

Methods

This was a cross-sectional and observational study. Baseline urine MCP-1 and EGF levels in systemic lupus erythematosus (SLE) patients and controls (total n = 101) were compared, and levels were correlated with clinicopathological findings and subsequent response to treatment.

Results

MCP-1 was higher in active LN (n = 69) compared to other SLE groups and controls, whereas EGF was not different. MCP-1 correlated with disease activity (proteinuria, renal SLEDAI, classes III/IV/V, and high activity index.) By contrast, EGF correlated with eGFR, but not with proteinuria, activity index, or class III/IV/V. MCP-1 was higher, and EGF was lower in high chronicity index. EGF/MCP-1 decreased with greater clinicopathological severity. In a subgroup with proliferative LN who completed six months of induction therapy (n = 41), EGF at baseline was lower in non-responders compared to responders, whereas MCP-1 was similar. By multivariable analysis, baseline EGF was independently associated with subsequent treatment response. Area under the curve for EGF to predict response was 0.80 (0.66–0.95). EGF ≥ 65.6 ng/ mgCr demonstrated 85% sensitivity and 71% specificity for response. EGF/MCP-1 did not improve the prediction for response compared to EGF alone.

Conclusion

MCP-1 increased with disease activity, whereas EGF decreased with low GFR and chronic damage. Urine EGF may be a promising biomarker to predict therapeutic response in LN. EGF/MCP-1 did not improve the prediction of response.

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.

Prognostic and Diagnostic Values of Novel Serum and Urine Biomarkers in Lupus Nephritis: A Systematic Review

INTRODUCTION

While renal biopsy remains the gold standard for diagnosing lupus nephritis (LN), the prognostic and diagnostic role of non-invasive biomarkers for LN is currently debated.

METHODS

Available studies published in last 5 years (2015-2020) assessing the diagnostic and prognostic value of urinary and/or serological biomarkers in subjects with LN were analyzed in this systematic review.

RESULTS

Eighty-five studies were included (comprehending 13,496 patients with systemic lupus erythematosus [SLE], 8,872 LN, 487 pediatric LN, 3,977 SLE but no LN, 160 pediatric SLE but no LN and 7,679 controls). Most of the studies were cross-sectional (62; 73%), while 14 (17%) were prospective. In sixty studies (71%), the diagnosis of LN was biopsy-confirmed. Forty-four out of 85 (52%) investigated only serological biomarkers, 29 studies (34%) tested their population only with urinary biomarkers, and 12 (14%) investigated the presence of both. Outcome measures to assess the clinical utility of the analyzed biomarkers were heterogeneous, including up to 21 different activity scores, with the SLEDAI (in 60%) being the most used. Despite some heterogeneity, promising results have been shown for biomarkers such as urinary monocyte chemoattractant protein, urinary adiponectin, and urinary vascular cell adhesion protein 1.

DISCUSSION/CONCLUSION

While serum and urine biomarkers have the potential to improve diagnostic and prognostic pathways in patients with LN, the vast heterogeneity across studies severely limits their applicability in current clinical practice. With the kidney biopsy still representing the gold standard, future efforts should focus on harmonizing study inclusion criteria and outcomes, particularly in clinical trials, in order to improve comparability and facilitate the implementations of available biomarkers into the daily practice.

Biomarkers Associated with Organ-Specific Involvement in Juvenile Systemic Lupus Erythematosus

Juvenile systemic lupus erythematosus (JSLE) is characterised by onset before 18 years of age and more severe disease phenotype, increased morbidity and mortality compared to adult-onset SLE. Management strategies in JSLE rely heavily on evidence derived from adult-onset SLE studies; therefore, identifying biomarkers associated with the disease pathogenesis and reflecting particularities of JSLE clinical phenotype holds promise for better patient management and improved outcomes. This narrative review summarises the evidence related to various traditional and novel biomarkers that have shown a promising role in identifying and predicting specific organ involvement in JSLE and appraises the evidence regarding their clinical utility, focusing in particular on renal biomarkers, while also emphasising the research into cardiovascular, haematological, neurological, skin and joint disease-related JSLE biomarkers, as well as genetic biomarkers with potential clinical applications.

Successful Urine Multiplex Bead Assay to Measure Lupus Nephritis Activity

Introduction

Lupus nephritis (LN) confers a poor prognosis, mainly from lack of effective laboratory tests to diagnose and to evaluate therapies. We have previously shown that a set of 6 urinary biomarkers (NGAL, KIM-1, MCP-1, adiponectin, hemopexin, and ceruloplasmin) are highly sensitive and specific to identify adult and pediatric patients with active LN using renal biopsy as reference standard. Using these combinatorial urinary biomarkers, the Renal Activity Score for Lupus (RAIL) score was established, with biomarkers measured by enzyme-linked immunosorbent assay (ELISA). To enhance clinical utility of the biomarkers and RAIL, we tested the performance of RAIL with biomarkers measured by ELISA to that of biomarkers measured by the bead multiplex method, hypothesizing that the multiplex bead method would be comparable.

Methods

Spot urine samples (n = 341) of 46 patients aged 20 to 73 years with or without LN were used. Samples were assayed both by ELISA and multiplex using LUMINEX. RAIL scores and biomarker quantities were assessed for agreement with intraassay correlation coefficients and compared using Bland−Altman and regression.

Results

Biomarker measurement by LUMINEX was successful for NGAL, KIM-1, MCP-1, and adiponectin, but not for ceruloplasmin and hemopexin. There was good agreement of the RAIL obtained from these 4 biomarkers, irrespective of assay method (intraclass correlation coefficient [ICC] = 0.78, 95% confidence interval [CI] = 0.78−0.82). The RAIL scores from 4 biomarkers further correlated with those when considering all 6 biomarkers (ICC = 0.97, 95% CI = 0.96−0.98).

Conclusion

The LUMINEX platform allows for the convenient and simultaneous measurement of 4 RAIL biomarkers. RAIL scores considering only these 4 biomarkers may be sufficient to accurately capture LN activity.

Vitamin D and Glomerulonephritis

Vitamin D presents a plethora of different functions that go beyond its role in skeletal homeostasis. It is an efficient endocrine regulator of the Renin–Angiotensin–Aldosterone System (RAAS) and erythropoiesis, exerts immunomodulatory effects, reduces the cardiovascular events and all-cause mortality. In Chronic Kidney Disease (CKD) patients, Vitamin D function is impaired; the renal hydrolyzation of its inactive form by the action of 1α-hydroxylase declines at the same pace of reduced nephron mass. Moreover, Vitamin D major carrier, the D-binding protein (DBP), is less represented due to Nephrotic Syndrome (NS), proteinuria, and the alteration of the cubilin–megalin–amnionless receptor complex in the renal proximal tubule. In Glomerulonephritis (GN), Vitamin D supplementation demonstrated to significantly reduce proteinuria and to slow kidney disease progression. It also has potent antiproliferative and immunomodulating functions, contributing to the inhibitions of kidney inflammation. Vitamin D preserves the structural integrity of the slit diaphragm guaranteeing protective effects on podocytes. Activated Vitamin D has been demonstrated to potentiate the antiproteinuric effect of RAAS inhibitors in IgA nephropathy and Lupus Nephritis, enforcing its role in the treatment of glomerulonephritis: calcitriol treatment, through Vitamin D receptor (VDR) action, can regulate the heparanase promoter activity and modulate the urokinase receptor (uPAR), guaranteeing podocyte preservation. It also controls the podocyte distribution by modulating mRNA synthesis and protein expression of nephrin and podocin. Maxalcalcitol is another promising alternative: it has about 1/600 affinity to vitamin D binding protein (DBP), compared to Calcitriol, overcoming the risk of hypercalcemia, hyperphosphatemia and calcifications, and it circulates principally in unbound form with easier availability for target tissues. Doxercalciferol, as well as paricalcitol, showed a lower incidence of hypercalcemia and hypercalciuria than Calcitriol. Paricalcitol demonstrated a significant role in suppressing RAAS genes expression: it significantly decreases angiotensinogen, renin, renin receptors, and vascular endothelial growth factor (VEGF) mRNA levels, thus reducing proteinuria and renal damage. The purpose of this article is to establish the Vitamin D role on immunomodulation, inflammatory and autoimmune processes in GN.

The utility of urinary biomarker panel in predicting renal pathology and treatment response in Chinese lupus nephritis patients

Given the urgent need for non-invasive biomarkers of LN, we aim to identify novel urinary biomarkers that facilitate diagnosis, assessment of disease activity and prediction of treatment response in a retrospective SLE cohort. A total of 154 SLE patients and 55 healthy controls were enrolled, among whom 73 were active LN patients. We measured renal activity by renal SLEDAI. The treatment response of the active LN patients who finished 6-month induction therapy was assessed based on the American College of Rheumatology response criteria. The expression levels of 10 urinary biomarkers (UBMs): β2-MG, calbindin D, cystatin C, IL-18, KIM-1, MCP-1, nephrin, NGAL, VCAM-1, and VDBP were tested using Luminex high-throughput proteomics technology. All but urinary nephrin levels were significantly increased in active LN compared to healthy controls. uCystatinC, uMCP-1, uKIM-1 levels were significantly higher in active LN group compared to inactive LN group. Correlation analysis revealed positive correlation between uCystatinC, uKIM-1, uMCP-1, uNGAL, uVDBP and RSLEDAI score. In renal pathology, uCystatinC, uKIM-1, uVCAM-1, and uVDBP positively correlated with activity index (AI) while uVCAM-1 positively correlated with chronicity index (CI). Moreover, the combination of uVCAM-1, uCystatinC, uKIM-1 discriminated proliferative LN from membranous LN with an AUC of 0.80 (95%CI: 0.69–0.90). Most importantly, baseline uNGAL demonstrated good prediction ability to discriminate responders from non-responders in active LN patients after 6-month induction therapy. Using a multiplex bead technique, we have identified the combination of uVCAM-1, uCystatinC, uKIM-1 as a biomarker panel to reflect renal pathology and NGAL as a promising urinary biomarker to both reflect disease activity and predict treatment response.

Utility of serum ferritin and soluble interleukin-2 receptor as markers of disease activity in childhood systemic lupus erythematosus

Objective

To assess the usefulness of serum ferritin and soluble interleukin-2 receptor (sIL-2r) levels as markers of disease activity in childhood systemic lupus erythematosus (cSLE) and their role in screen for subclinical macrophage activation syndrome (MAS).

Patients and methods

This is a cross-sectional analysis of prospectively collected data. Consecutive children who met the Systemic Lupus International Collaborating Clinics (SLICC) criteria were enrolled between June 2015 and June 2017. All patients interviewed and assessed for disease activity using SLE disease activity index (SLEDAI). Biochemical and serological tests including markers of disease activity and MAS were measured by standard laboratory procedure.

Results

A total of 31 (25 female; 6 male) consecutive cSLE patients with a mean age of 10.6 (±3.2) years were included. The most frequent manifestations were mucocutaneous and musculoskeletal (84%) followed by hematological (64.5%) then renal involvement (58%). Twenty-two patients had active disease (SLEDAI ≥ 4), with a mean of 9.8. Mean serum ferritin and sIL-2r were 555 (±1860) and 2789 (±1299) respectively. Both correlated significantly with leucocyte, platelet count, transferrin, C3 and SLEDAI (p < 0.05). Additionally, sIL-2r had positive correlation with ANA, ds-DNA and C4. Both ferritin and sIL-2r had weak correlation with ESR, but no correlation with CRP. Twelve patients had a recent infection. However, they were comparable to patients without infection with regard to all clinical and laboratory features. Three patients had MAS proved by bone marrow aspiration.

Conclusion

Measurement of serum ferritin and sIL-2r might help in assessing disease activity of cSLE. Both might be good screening markers for MAS in cSLE. A larger prospective study is required to allow more definitive conclusions.

Comparative efficacy and safety of mycophenolate mofetil and cyclophosphamide in the induction treatment of lupus nephritis: A systematic review and meta-analysis

BACKGROUND

Lupus nephritis (LN) remains a predominant cause of morbidity and mortality in SLE. Here we performed a meta-analysis to evaluate the efficacy and safety of the induction treatment with mycophenolate mofetil (MMF) and cyclophosphamide (CYC) for LN.

METHODS

Relevant literature was searched by computer from the establishment of the database to November 2019. A meta-analysis was conducted to analysis the efficacy and safety between mycophenolate mofetil and cyclophosphamide as induction therapy in LN patients. The primary end-point was response to urine protein, serum creatinine (Scr) and serum complement C3, and the secondary end-points were complete remission and adverse reactions.

RESULTS

Eighteen articles were selected for the final meta-analysis, involving 1989 patients with LN, of which the renal biopsy result could be classified into class III-V according to the standards of WHO/ISN. The results revealed that MMF was superior to CYC in increasing the level of serum complement C3 [SMD = 0.475, 95%CI (0.230-0.719)] and complete remission [RR = 1.231, 95%CI (1.055-1.437)]. Furthermore, the subgroup analysis showed that it was in Asian patients, rather than in Caucasian patients, that CYC exerted a better effect on lowering the level of urine protein (UPRO) than MMF [SMD = 0.405, 95%CI (0.081-0.730)]. Besides, when the initial UPRO level was less than 4 g/day, the effect of CYC was better than MMF [SMD = 0.303, 95%CI (0.014-0.591)]. There was no significant difference between MMF and CYC in improving Scr [SMD = 0.090, 95%CI (-0.060-0.239)]. When it came to the comparison of safety between MMF and CYC, the meta-analysis showed that MMF was superior to CYC in decreasing infection in Caucasian patients [RR = 0.727, 95%CI (0.532-0.993)], reducing the risk of leukopenia and menstrual abnormalities in Asian patients and lowering the frequency of gastrointestinal symptoms [RR = 0.639, 95%CI (0.564-0.724)], independent of race.

CONCLUSIONS

MMF precedes CYC in improving serum complement C3 and complete remission regardless of race, as well as shows fewer adverse drug reactions in the induction treatment of LN belonging to type III-V. But for Asian patients or those initial UPRO levels are less than 4 g/day, CYC may be superior to MMF.

Evidence of Renal Iron Accumulation in a Male Mouse Model of Lupus

Lupus nephritis represents a common and serious complication of the autoimmune disease Systemic Lupus Erythematosus (SLE). Clinical studies suggest that several proteins related to iron metabolism, including transferrin, serve as urinary biomarkers of lupus nephritis. We previously reported that in female NZBWF1 mice, a commonly used mouse model of SLE with a female sex bias, increased urinary transferrin excretion and renal iron accumulation occur around the onset of albuminuria. The current study investigated whether similar findings occur in male mice of a different mouse model of SLE, the MRL/lpr mouse. Two different cohorts were studied: MRL/lpr mice at an early, pre-albuminuric age (8 weeks), and after developing albuminuria (>100 mg/dL, confirmed by ELISA); age-matched MRL/MpJ control strain mice served for comparison. Urinary transferrin excretion was dramatically increased in the older, albuminuric MRL/lpr mice compared to the age-matched MRL/MpJ (P < 0.05), but there was no significant difference between strains at 8 weeks of age. Similarly, there were no significant differences between strains in renal cortical or outer medullary non-heme iron concentrations at 8 weeks. In the older, albuminuric MRL/lpr mice, renal cortical and outer medullary non-heme iron concentrations were significantly increased compared with age-matched MRL/MpJ mice, as was the expression of the iron storage protein ferritin (P < 0.01). Together, these data show that increased urinary transferrin excretion and renal tissue iron accumulation also occurs in albuminuric male MRL/lpr mice, suggesting that renal iron accumulation may be a feature of multiple mouse models of SLE.

Clinical and histological significance of urinary CD11c+ macrophages in lupus nephritis

Background

Infiltration of immune cells into the kidney is one of the key features of lupus nephritis (LN). The presence of immune cells in the urine may be used as a non-invasive biomarker of LN. Here, we aimed to analyze the clinicopathologic significance of urinary CD11c⁺ macrophages in patients with LN.

Methods

The numbers and proportions of CD11c⁺ macrophages in the urine samples of patients with LN at the time of kidney biopsy were examined using flow cytometry. We also examined the association between the levels of urinary CD11c⁺ macrophages and the clinical and pathologic features of patients with LN.

Results

Compared with patients without LN or those with non-proliferative LN, patients with proliferative LN had significantly higher numbers and proportions of urinary CD11c⁺ macrophages, which were strongly correlated with the serum anti-dsDNA antibody titer. The numbers and proportions of urinary CD11c⁺ macrophages were significantly associated with the values of chronicity indices such as tubular atrophy and interstitial fibrosis. No significant relationships were found between the levels of urinary CD11c⁺ macrophages and the activity scores, degree of proteinuria, or lupus disease activity. Urinary CD11c⁺ macrophages were more abundant in patients who did not achieve renal response to induction treatment with immunosuppressants than in those who achieved complete or partial response. The receiver operating characteristic (ROC) curve analysis showed that the number of urinary CD11c⁺ macrophages was the most powerful predictor of renal response at 6 months (ROC-AUC = 1.00, p = 0.0004).

Conclusion

The urinary levels of CD11c⁺ macrophages were closely associated with the chronic pathologic changes of LN and renal response and may thus be used as a novel biomarker in LN.

Urinary Soluble CD163: a Novel Noninvasive Biomarker of Activity for Lupus Nephritis

BACKGROUND

Clinical distinction between patients with lupus nephritis who have active inflammation or chronic kidney damage is challenging. Studies have shown soluble CD163, which derives from cleavage of the CD163 M2c macrophage receptor and can be quantified in urine, correlates with active lupus nephritis.

METHODS

We measured urine CD163 at lupus nephritis flares in patients from a Mexican cohort and cross-sectional and longitudinal United States cohorts. We also performed serial urine CD163 measurements during the treatment of flares in a subset of patients from the Mexican and longitudinal United States cohorts, and assessed response to therapy at 12 months. In addition, we evaluated urinary CD163 agreement with histologic activity in 19 patients from the Mexican cohort who had repeated kidney biopsies on follow-up.

RESULTS

Urinary CD163 levels were significantly higher in patients with active lupus nephritis than in patients with active extrarenal SLE, inactive SLE, and other glomerular diseases, and correlated with disease clinical severity, histologic class, and the histologic activity index. Urinary CD163 increased from 6 months preflare to flare, diminishing progressively in complete and partial responders, whereas it remained elevated in nonresponders. Urinary CD163 <370 ng/mmol at 6 months predicted complete renal response at 12 months with >87% sensitivity and >87% specificity. Urinary CD163 <370 ng/mmol or >370 ng/mmol perfectly agreed (κ=1.0) with a histologic activity index ≤1 or >1 in repeated biopsies, respectively. Evaluation of urinary CD163 in patients with persistent proteinuria at 6 months improved the prediction of who would achieve complete renal response at 12 months.

CONCLUSIONS

Urinary CD163 reflects histologic inflammation in lupus nephritis and is a promising activity biomarker that varies over time with lupus nephritis activity and treatment.

Urinary biomarkers in lupus nephritis

Systemic lupus erythematosus (SLE) is the prototypical autoimmune disease that can affect any organ of the body. Multiple mechanisms may contribute to the pathophysiology of systemic lupus, including failure to remove apoptotic bodies, hyperactivity of self-reactive B and T lymphocytes, abnormal exposure to autoantigens, and increased levels of B-cell stimulatory cytokines. The involvement of the kidney, called lupus nephritis (LN), during the course of the disease affects between 30% and 60% of adult SLE patients, and up to 70% of children. LN is an immune-mediated glomerulonephritis that is a common and serious finding in patients with SLE. Nowadays, renal biopsy is considered the gold standard for classifying LN, besides its degree of activity or chronicity. Nevertheless, renal biopsy lacks the ability to predict which patients will respond to immunosuppressive therapy and is a costly and risky procedure that is not practical in the monitoring of LN because serial repetitions would be necessary. Consequently, many serum and urinary biomarkers have been studied in SLE patients for the complementary study of LN, existing conventional biomarkers like proteinuria, protein/creatinine ratio in spot urine, 24 ​h urine proteinuria, creatinine clearance, among others and non-conventional biomarkers, like Monocyte chemoattractant protein-1 (MCP-1), have been correlated with the histological findings of the different types of LN. In this article, we review the advances in lupus nephritis urinary biomarkers. Such markers ideally should be capable of predicting early sub-clinical flares and could be used to follow response to therapy. In addition, some of these markers have been found to be involved in the pathogenesis of lupus nephritis.

Juvenile-onset systemic lupus erythematosus: Update on clinical presentation, pathophysiology and treatment options

Juvenile-onset systemic lupus erythematosus (jSLE) accounts for up to 20% of all SLE patients. Key differences between juvenile- and adult-onset (aSLE) disease include higher disease activity, earlier development of damage, and increased use of immunosuppressive treatment in jSLE suggesting (at least partial) infectivity secondary to variable pathomechanisms. While the exact pathophysiology of jSLE remains unclear, genetic factors, immune complex deposition, complement activation, hormonal factors and immune cell dysregulation are involved to variable extents, promising future patient stratification based on immune phenotypes. Though less effective and potentially toxic, jSLE patients are treated based upon evidence from studies in aSLE cohorts. Here, age-specific clinical features of jSLE, underlying pathomechanisms, treatment options and disease outcomes will be addressed. Future directions to improve the care of jSLE patients, including implementation of the Single Hub and Access point for pediatric Rheumatology in Europe (SHARE) recommendations, biomarkers, treat to target and personalized medicine approaches are discussed.

Glomerular Expression of Some Profibrotic Factors in Progressive Childhood Lupus Nephritis

BACKGROUND

Lupus nephritis (LN) is a major cause of mortality and morbidity in both adult and pediatric patients. However, studies regarding pathogenesis and predictors of renal outcomes in childhood LN are limited. Transforming growth factor-β1 (TGF-β1) and Connective tissue growth factor (CTGF) have an important role in proliferative and fibrotic changes in many renal diseases. We aim to evaluate the role of such two profibrotic factors in the progression of childhood onset LN and to detect if their glomerular expression could represent an early predictor of future deterioration of renal function.

METHODS

34 children with new onset of LN were included. Glomerular expressions of TGF-β1 and CTGF were evaluated by immunohistochemical analysis in the renal tissue of such patients and in control tissue. GFR was estimated at time of renal biopsy at the onset of LN and after 2 years of follow-up. Rate of GFR change (ΔGFR) was calculated and used as indicative of degree of renal disease progression.

RESULTS

Glomerular TGF-β1 and CTGF expressions in children with LN were significantly higher than in control tissue (LN 15.41 ± 9.84 and 15.56 ± 10.51 vs. 2.15 ± 1.45 and 1.35 ± 1.07 in control respectively, with p < 0.001 in both). In addition, the glomerular expressions of TGF-β1 and CTGF were significantly higher in patients with further decline in GFR (20.68 ± 7.73 and 21.05 ± 8.75) versus (5.75 ± 4.37 and 5.50 ± 3.78) in those without change in GFR with (p = 0.000 for both of them).

CONCLUSIONS

Patients with LN have increased glomerular expressions of TGF-β1 and CTGF, which were higher in those with further decline in GFR. These profibrotic factors are suspected to be involved in pathogenesis of LN and could be evaluated as a target for therapeutic intervention to stop progression of LN. In addition, their glomerular expression could be used as an early predictor of progression of LN, to justify early aggressive therapy in those with suspected rapid progression.

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.

Urinary biomarkers for lupus nephritis: the role of the vascular cell adhesion molecule-1

Renal involvement is one of the main complications of systemic lupus erythematosus, causing a significant impact on patients' morbidity and mortality. Renal biopsy is still the gold standard of diagnosis, but it has many limitations. In this sense, several recent studies aim to identify biomarkers that not only predict disease activity and renal histology, but also lead to earlier treatment. In previous studies, the soluble vascular cell adhesion molecule-1 measured in urine showed a strong association with the presence of lupus nephritis, with clinical and histological activity indexes of the disease and with more severe renal lesions. This paper reviews the main urinary biomarkers of lupus nephritis that have been studied, with special emphasis on vascular cell adhesion molecule-1 results.

Urine biomarkers of chronic kidney damage and renal functional decline in childhood-onset systemic lupus erythematosus

OBJECTIVES

To delineate urine biomarkers that reflect kidney structural damage and predict renal functional decline in pediatric lupus nephritis (LN).

METHODS

In this prospective study, we evaluated kidney biopsies and urine samples of 89 patients with pediatric LN. Urinary levels of 10 biomarkers [adiponectin, ceruloplasmin, kidney injury molecule-1, monocyte chemotactic protein-1, neutrophil gelatinase-associated lipocalin, osteopontin, transforming growth factor-ß (TGFß), vitamin-D binding protein, liver fatty acid binding protein (LFABP), and transferrin] were measured. Regression analysis was used to identify individual and combinations of biomarkers that determine LN damage status [NIH-chronicity index (NIH-CI) score ≤ 1 vs. ≥ 2] both individually and in combination, and biomarker levels were compared for patients with vs. without renal functional decline, i.e., a 20% reduction of the glomerular filtration rate (GFR) within 12 months of a kidney biopsy.

RESULTS

Adiponectin, LFABP, and osteopontin levels differed significantly with select histological damage features considered in the NIH-CI. The GFR was associated with NIH-CI scores [Pearson correlation coefficient (r) = - 0.49; p < 0.0001] but not proteinuria (r = 0.20; p > 0.05). Similar to the GFR [area under the ROC curve (AUC) = 0.72; p < 0.01], combinations of osteopontin and adiponectin levels showed moderate accuracy [AUC = 0.75; p = 0.003] in discriminating patients by LN damage status. Renal functional decline occurred more commonly with continuously higher levels of the biomarkers, especially of TGFß, transferrin, and LFABP.

CONCLUSION

In combination, urinary levels of adiponectin and osteopontin predict chronic LN damage with similar accuracy as the GFR. Ongoing LN activity as reflected by high levels of LN activity biomarkers heralds renal functional decline.

KEY MESSAGES

• Levels of osteopontin and adiponectin measured at the time of kidney biopsy are good predictors of histological damage with lupus nephritis. • Only about 20% of children with substantial kidney damage from lupus nephritis will have an abnormally low urine creatinine clearance. • Continuously high levels of biomarkers reflecting lupus nephritis activity are risk factors of declining renal function.

A Markov Multi-State model of lupus nephritis urine biomarker panel dynamics in children: Predicting changes in disease activity

BACKGROUND

A urine 'biomarker panel' comprising alpha-1-acid-glycoprotein, ceruloplasmin, transferrin and lipocalin-like-prostaglandin-D synthase performs to an 'excellent' level for lupus nephritis identification in children cross-sectionally. The aim of this study was to assess if this biomarker panel predicts lupus nephritis flare/remission longitudinally.

METHODS

The novel urinary biomarker panel was quantified by enzyme linked immunoabsorbant assay in participants of the United Kingdom Juvenile Systemic Lupus Erythematosus (UK JSLE) Cohort Study, the Einstein Lupus Cohort, and the South African Paediatric Lupus Cohort. Monocyte chemoattractant protein-1 and vascular cell adhesion molecule-1 were also quantified in view of evidence from other longitudinal studies. Serial urine samples were collected during routine care with detailed clinical and demographic data. A Markov Multi-State model of state transitions was fitted, with predictive clinical/biomarker factors assessed by a corrected Akaike Information Criterion (AICc) score (the better the model, the lower the AICc score).

RESULTS

The study included 184 longitudinal observations from 80 patients. The homogeneous multi-state Markov model of lupus nephritis activity AICc score was 147.85. Alpha-1-acid-glycoprotein and ceruloplasmin were identified to be the best predictive factors, reducing the AICc score to 139.81 and 141.40 respectively. Ceruloplasmin was associated with the active-to-inactive transition (hazard ratio 0.60 (95% confidence interval [0.39, 0.93])), and alpha-1-acid-glycoprotein with the inactive-to-active transition (hazard ratio 1.49 (95% confidence interval [1.10, 2.02])). Inputting individual alpha-1-acid-glycoprotein/ceruloplasmin values provides 3, 6 and 12 months probabilities of state transition.

CONCLUSIONS

Alpha-1-acid-glycoprotein was predictive of active lupus nephritis flare, whereas ceruloplasmin was predictive of remission. The Markov state-space model warrants testing in a prospective clinical trial of lupus nephritis biomarker led monitoring.

Lipocalin-Like Prostaglandin D Synthase but Not Hemopoietic Prostaglandin D Synthase Deletion Causes Hypertension and Accelerates Thrombogenesis in Mice

Prostaglandin (PG) D₂ is formed by two distinct PGD synthases (PGDS): lipocalin-type PGDS (L-PGDS), which acts as a PGD₂-producing enzyme and as extracellular lipophilic transporter, and hematopoietic PGDS (H-PGDS), a σ glutathione-S-transferase. PGD₂ plays an important role in the maintenance of vascular function; however, the relative contribution of L-PGDS– and H-PGDS–dependent formation of PGD₂ in this setting is unknown. To gain insight into the function played by these distinct PGDS, we assessed systemic blood pressure (BP) and thrombogenesis in L-Pgds and H-Pgds knockout (KO) mice. Deletion of L-Pgds depresses urinary PGD₂ metabolite (PGDM) by ∼35%, whereas deletion of H-Pgds does so by ∼90%. Deletion of L-Pgds, but not H-Pgds, elevates BP and accelerates the thrombogenic occlusive response to a photochemical injury to the carotid artery. HQL-79, a H-PGDS inhibitor, further depresses PGDM in L-Pgds KO mice, but has no effect on BP or on the thrombogenic response. Gene expression profiling reveals that pathways relevant to vascular function are dysregulated in the aorta of L-Pgds KOs. These results indicate that the functional impact of L-Pgds deletion on vascular homeostasis may result from an autocrine effect of L-PGDS–dependent PGD₂ on the vasculature and/or the L-PGDS function as lipophilic carrier protein.

Urinary vitamin D-binding protein, a novel biomarker for lupus nephritis, predicts the development of proteinuric flare

Lupus nephritis (LN) is a major complication of systemic lupus erythematosus (SLE). Conventional biomarkers for assessing renal disease activity are imperfect in predicting clinical outcomes associated with LN. The aim of this study is to identify urinary protein biomarkers that reliably reflect the disease activity or predict clinical outcomes. A quantitative proteomic analysis was performed to identify protein biomarker candidates that can differentiate between SLE patients with and without LN. Selected biomarker candidates were further verified by enzyme-linked immunosorbent assay using urine samples from a larger cohort of SLE patients ( n = 121) to investigate their predictive values for LN activity measure. Furthermore, the association between urinary levels of a selected panel of potential biomarkers and prognosis of LN was assessed with a four-year follow-up study of renal outcomes. Urinary vitamin D-binding protein (VDBP), transthyretin (TTR), retinol binding protein 4 (RBP4), and prostaglandin D synthase (PTGDS) were significantly elevated in SLE patients with LN, especially in patients with active LN ( n = 21). Among them, VDBP well correlated with severity of proteinuria (rho = 0.661, p < 0.001) and renal SLE Disease Activity Index (renal SLEDAI) (rho = 0.520, p < 0.001). In the four-year follow-up, VDBP was a significant risk factor (hazard ratio 9.627, 95% confidence interval 1.698 to 54.571, p = 0.011) for the development of proteinuric flare in SLE patients without proteinuria ( n = 100) after adjustments for multiple confounders. Urinary VDBP correlated with proteinuria and renal SLEDAI, and predicted the development of proteinuria.

Utility of urinary transferrin and ceruloplasmin in patients with systemic lupus erythematosus for differentiating patients with lupus nephritis

BACKGROUND AND OBJECTIVE

Diagnosis of lupus nephritis (LN) is usually based on renal biopsy, which is an invasive technique that involves multiple risks. Therefore, different biomarkers have emerged as alternatives for the diagnosis of LN. Nonetheless, studies regarding urinary biomarkers in Latin American patients are limited. The objective of this study was to assess the diagnostic value of urinary transferrin and ceruloplasmin to differentiate patients who have renal involvement from those who do not.

MATERIALS AND METHODS

Systemic lupus erythematosus (SLE) patients that met the revised American College of Rheumatology (ACR) classification criteria were recruited. Patients with another autoimmune disease, active infection (urinary tract or systemic infection), renal replacement therapy, human immunodeficiency virus infection or pregnancy were excluded. A urine sample was collected from each patient. LN was diagnosed according to ACR criteria. The activity and chronicity of LN were measured using the Austin indices. Urinary transferrin and ceruloplasmin levels were measured using commercial enzyme-linked immunosorbent assay (ELISA) kits. Mann-Whitney U test and Student's t-test were used to compare data. Spearman's rank correlation was used to determine associations. Lastly, receiver operating characteristic (ROC) curves were created.

RESULTS

The study involved 120 SLE patients. In all, 85% were female, 76% mestizo, the mean age was 32.8±12.1years and mean systemic lupus erythematosus disease activity index (SLEDAI) was 8.4±8.9; 64% had renal involvement. Urinary levels of the two biomarkers were significantly higher in patients with LN compared to those without LN. Similarly, urinary levels of both biomarkers were significantly higher in patients with active LN compared to those with inactive LN. Furthermore, urinary transferrin levels were significantly higher in Afro-Latin American patients. On the other hand, urinary transferrin levels correlated with SLEDAI and proteinuria, and transferrin and ceruloplasmin levels correlated with each other. The diagnostic value of ROC curves for these urinary biomarkers for LN were good.

CONCLUSIONS

In our cohort of SLE patients, we found that transferrin and ceruloplasmin were potential biomarkers for LN, and can even differentiate active LN.