Urinary Biomarkers In Lupus Nephritis Research Articles

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) and kidney injury molecule-1 (uKIM-1) as markers of active lupus nephritis

Background and objectivesDespite much research about lupus nephritis, none of the urinary biomarkers has been proven to be truly reflecting lupus nephritis activity, response to treatment, or prognosis. We aimed to study urinary biomarkers in lupus nephritis and test their relation to kidney damage.Patients and methodsForty patients with systemic lupus erythematosus (SLE) were divided into two graoups: (1) lupus nephritis group with biopsy-proven proliferative lupus nephritis (classes III and IV) and who did not receive immunosuppressive drugs within the preceding 3 months except for glucocorticoids and (2) lupus non-nephritis group with SLE patients without any renal manifestation. We assessed disease activity by the SLE disease activity index. uNGAL, uKim-1, uNGAL to urinary creatinine excretion (mg/dl), and uKim-1 to urinary creatinine excretion were measured in random spot urine samples at the time of renal biopsy and 6 months after the induction therapy.ResultsThe LN group before treatment showed higher levels of uNGAL and uKIM-1 (P-value < 0.001). ROC analysis showed that uNGAL at level of > 59 has a 95 % sensitivity, a 100 % specificity, and an AUC = 0.996 in the ability to diagnose LN. While the uKIM-1 ROC showed that at level of > 1.6, it has an 85 % sensitivity, an 80 % specificity, and an AUC = 0.919. uNGAL and uKIM levels were significantly lower after treatment (P-value < 0.001). No significant correlations were found between urinary markers before and after treatment with other clinical, inflammatory, and serological markers of lupus nephritis.ConclusionuNGAL, uKIM, uNGAL/Creat ratio, and uKIM/Creat ratio can be used as a predictor and a marker of disease activity for lupus nephritis.Key Points• Renal biopsy is the current standard for diagnosis of lupus nephritis and none of the urinary biomarkers has been fully concluded to have a diagnostic power to reflect the activity or the response to treatment.• However, based on the finding of the current study, uNGAL, uKIM, uNGAL/Creat ratio, and uKIM/Creat ratio showed significant diagnostic performance and were powerful indices of renal involvement in systemic lupus patients and as markers of disease activity.

Diagnostic test accuracy of novel biomarkers for lupus nephritis-An overview of systematic reviews.

IntroductionSystemic lupus erythematosus (SLE) is a chronic autoimmune disease with multiorgan inflammatory involvement and a mortality rate that is 2.6-fold higher than individuals of the same age and sex in the general population. Approximately 50% of patients with SLE develop renal impairment (lupus nephritis). Delayed diagnosis of lupus nephritis is associated with a higher risk of progression to end-stage renal disease, the need for replacement therapy, and mortality. The initial clinical manifestations of lupus nephritis are often discrete or absent and are usually detected through complementary tests. Although widely used in clinical practice, their accuracy is limited. A great scientific effort has been exerted towards searching for new, more sensitive, and specific biomarkers in recent years. Some systematic reviews have individually evaluated new serum and urinary biomarkers tested in patients with lupus nephritis. This overview aimed to summarize systematic reviews on the accuracy of novel serum and urinary biomarkers for diagnosing lupus nephritis in patients with SLE, discussing how our results can guide the clinical management of the disease and the direction of research in this area.MethodsThe research question is “What is the accuracy of the new serum and urinary biomarkers studied for the diagnosis of LN in patients with SLE?”. We searched for systematic reviews of observational studies evaluating the diagnostic accuracy of new serum or urinary biomarkers of lupus nephritis. The following databases were included: PubMed, EMBASE, BIREME/LILACS, Scopus, Web of Science, and Cochrane, including gray literature found via Google Scholar and PROQUEST. Two authors assessed the reviews for inclusion, data extraction, and assessment of the risk of bias (ROBIS tool).ResultsTen SRs on the diagnostic accuracy of new serum and urinary BMs in LN were selected. The SRs evaluated 7 distinct BMs: (a) antibodies (anti-Sm, anti-RNP, and anti-C1q), (b) cytokines (TWEAK and MCP-1), (c) a chemokine (IP-10), and (d) an acute phase glycoprotein (NGAL), in a total of 20 review arms (9 that analyzed serum BMs, and 12 that analyzed BMs in urine). The population evaluated in the primary studies was predominantly adults. Two SRs included strictly adults, 5 reviews also included studies in the paediatric population, and 4 did not report the age groups. The results of the evaluation with the ROBIS tool showed that most of the reviews had a low overall risk of bias.ConclusionsThere are 10 SRs of evidence relating to the diagnostic accuracy of serum and urinary biomarkers for lupus nephritis. Among the BMs evaluated, anti-C1q, urinary MCP-1, TWEAK, and NGAL stood out, highlighting the need for additional research, especially on LN diagnostic panels, and attempting to address methodological issues within diagnostic accuracy research. This would allow for a better understanding of their usefulness and possibly validate their clinical use in the future.RegistrationThis project is registered on the International Prospective Registry of Systematic Reviews (PROSPERO) database (CRD42020196693).

Quantitative planar array screen of 1000 proteins uncovers novel urinary protein biomarkers of lupus nephritis

ObjectiveThe goal of these studies is to discover novel urinary biomarkers of lupus nephritis (LN).MethodsUrine from systemic lupus erythematosus (SLE) patients was interrogated for 1000 proteins using a novel, quantitative...

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.

Comprehensive aptamer-based screening identifies a spectrum of urinary biomarkers of lupus nephritis across ethnicities

Emerging urinary biomarkers continue to show promise in evaluating lupus nephritis (LN). Here, we screen urine from active LN patients for 1129 proteins using an aptamer-based platform, followed by ELISA validation in two independent cohorts comprised of 127 inactive lupus, 107 active LN, 67 active non-renal lupus patients and 74 healthy controls, of three different ethnicities. Urine proteins that best distinguish active LN from inactive disease are ALCAM, PF-4, properdin, and VCAM-1 among African-Americans, sE-selectin, VCAM-1, BFL-1 and Hemopexin among Caucasians, and ALCAM, VCAM-1, TFPI and PF-4 among Asians. Most of these correlate significantly with disease activity indices in the respective ethnic groups, and surpass conventional metrics in identifying active LN, with better sensitivity, and negative/positive predictive values. Several elevated urinary molecules are also expressed within the kidneys in LN, based on single-cell RNAseq analysis. Longitudinal studies are warranted to assess the utility of these biomarkers in tracking lupus nephritis.

Identification of Low-Abundance Urinary Biomarkers in Lupus Nephritis Using Electrochemiluminescence Immunoassays.

To investigate the utility of a sensitive platform using electrochemiluminescence (ECL) for the identification of low-abundance urinary protein biomarkers in lupus nephritis (LN). Forty-eight urine samples were obtained from subjects in 2 independent cohorts, each consisting of 3 groups (matched for age, sex, and race) of 8 patients with active LN (renal Systemic Lupus Erythematosus Disease Activity Index [SLEDAI] >0), 8 patients with inactive SLE (renal SLEDAI 0), and 8 healthy controls. Samples were tested using a preexisting 40-plex ECL panel. A custom 5-plex ECL panel was then developed for further validation studies and used to test 140 urine samples (from 44 patients with active LN, 41 patients with inactive SLE, 28 healthy controls, and 27 patients with other kidney diseases). Levels of 17 urinary proteins were elevated (P < 0.05 by 2-tailed Mann-Whitney U test) in samples from patients with active LN compared to samples from patients with inactive SLE and healthy controls in cohort 1, while 9 were similarly elevated in cohort 2. Of these, interleukin-7 (IL-7), IL-12p40, IL-15, interferon-γ-inducible protein 10 (IP-10), and thymus and activation-regulated chemokine (TARC) were chosen for further validation. These 5 proteins were undetectable by enzyme-linked immunosorbent assay (ELISA). Hence, a custom 5-plex ECL panel was developed and used to validate the results from the initial 40-plex screening panel. Urinary IL-7, IL-12p40, IL-15, IP-10, and TARC levels were again significantly elevated in patients with active LN compared to those with inactive SLE and healthy controls, and correlated well with the renal SLEDAI and physician's global assessment of disease activity (R > 0.67, P < 0.05). All 5 urinary proteins were more frequently elevated in LN compared to controls with other chronic kidney diseases, although overall group differences attained significance only for urinary IL-7 and IL-15. Urinary levels of IL-7, IL-12p40, IL-15, IP-10, and TARC are potentially useful diagnostic tools in LN. The use of ECL assays may allow detection of urinary biomarkers that are below ELISA detection limits.

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.

Urinary neutrophil gelatinase-associated lipocalin and monocyte chemoattractant protein 1 as biomarkers for lupus nephritis in Colombian SLE patients.

Background Information regarding urinary biomarkers in Mestizo and Afro-Latin-American patients is very limited. We investigated whether levels of urinary neutrophil gelatinase-associated lipocalin (NGAL), and monocyte chemoattractant protein 1 (MCP-1) are good biomarkers to differentiate patients with lupus nephritis among Latin-American systemic lupus erythematosus (SLE) patients. Methods SLE patients meeting the revised American College of Rheumatology classification criteria for SLE were recruited. Urinary levels of NGAL and MCP-1 were measured using a commercial ELISA kit. Serum anti-C1q antibodies were measured by ELISA. SLE activity was measured with the systemic lupus erythematosus disease activity index (SLEDAI). Mann-Whitney tests were used to compare data and Spearman's rank correlations were used to examine associations between continuous variables. In addition, receiver operating characteristic curves were performed. Results One hundred and twenty SLE patients were recruited (87% women) with a median age of 32.8 ± 12.1 years and median disease duration of 7.3 ± 6.9 years. Afro-Latin-Americans had a significantly higher prevalence of lupus nephritis and higher SLEDAI scores than Mestizos. The three biomarkers were significantly higher in patients with lupus nephritis than in patients without lupus nephritis. In addition, urinary NGAL and MCP-1 were significantly higher in patients with active lupus nephritis than in inactive lupus nephritis. Urinary NGAL levels were significantly higher in Afro-Latin-American patients. A receiver operating characteristic curve for urinary biomarkers for lupus nephritis in all SLE patients showed a good level of sensitivity and specificity. Conclusion In our cohort of SLE patients, we found that urinary NGAL and MCP-1 in addition to anti-C1q antibodies were useful biomarkers for the identification of renal involvement and discrimination of active lupus nephritis among patients with renal disease.

Urinary haptoglobin, alpha-1 anti-chymotrypsin and retinol binding protein identified by proteomics as potential biomarkers for lupus nephritis.

The study was aimed at identification by proteomics and validation by enzyme-linked immunosorbent assay (ELISA) of potential urinary biomarkers for lupus nephritis. Study subjects comprised 88 systemic lupus erythematosus (SLE) patients and 60 controls (rheumatoid arthritis, diabetes mellitus and healthy individuals). Based on the SLE disease activity index (SLEDAI), patients were classified as active renal (AR), active non-renal (ANR) or inactive disease (ID). Urinary proteins from a group of patients with AR or ID were resolved by two-dimensional gel electrophoresis and identified by matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS/MS). The selected biomarkers were validated by ELISA using samples from all patients and controls. AR patients were followed-up for 12 months after start of therapy. Three urinary proteins, alpha-1 anti-chymotrypsin (ACT), haptoglobin (HAP) and retinol binding protein (RBP), were detected in patients with AR and not ID. Upon validation, ACT levels were higher in AR patients than the other groups (P < 0·001) and showed good correlation with renal SLEDAI (r = 0·577, P < 0·001) as well as SLEDAI (r = 0·461, P < 0·001). Similarly, HAP levels were >10-fold higher in AR than other groups (P < 0·001) and correlated well with renal SLEDAI (r = 0·594, P < 0·001) and SLEDAI (r = 0·371, P < 0·01). RBP levels were also higher in AR patients than in other groups (P < 0·05), except diabetes, and showed moderate correlation with renal SLEDAI (r = 0·284, P < 0·008) and SLEDAI (r = 0·316, P < 0·003). Upon follow-up with treatment, levels of all three proteins declined at 6 and 12 months (P < 0·01). Multiple logistic regression identified ACT as the best marker to differentiate AR from ANR. Urinary HAP, ACT and RBP are potential biomarkers for lupus nephritis activity.

Urinary Biomarkers in Lupus Nephritis

Renal involvement in patients with systemic lupus erythematosus in the form of severe lupus nephritis is associated with a significant burden of morbidity and mortality. Conventional laboratory biomarkers in current use have not been very successful in anticipating disease flares, predicting renal histology, or decreasing unwanted outcomes. Since early treatment is associated with improved clinical results, it is thus essential to identify new biomarkers with substantial predictive power to reduce the serious sequelae of this difficult to control lupus manifestation. Indeed, considerable efforts and progress have been made over the last few years in the search for novel biomarkers. Since urinary biomarkers are more easily obtainable with much less risk to the patient than repeat renal biopsies, and these may more accurately discern between renal disease and other organ manifestations than their serum counterparts, there has been tremendous interest in studying new candidate urine biomarkers. Below, we review several promising urinary biomarkers under investigation, including total proteinuria and microalbuminuria, urinary proteomic signatures, and the individual inflammatory mediators interleukin-6, vascular cell adhesion molecule-1, CXCL16, IP-10, and tumor necrosis factor-like weak inducer of apoptosis.

Lipocalin‐2, TWEAK, and Other Cytokines as Urinary Biomarkers for Lupus Nephritis

Lupus nephritis (LN) is a major cause of morbidity and mortality in systemic lupus erythematosus (SLE). As the course of LN is often unpredictable, it is important to identify reliable, noninvasive methods to repeatedly assess the condition of the kidneys in these patients. Urinary biomarkers are easily obtained and probably are best at reflecting the current renal status, as they specifically represent local inflammatory activity. In this article, we review a number of potential urinary biomarkers, including Lipocalin-2, MCP-1, IP-10, IL-6, and IL-8. Additionally, we provide evidence for the possible utility of the novel cytokine TWEAK as a urinary biomarker for LN.

Points: Measles immunisation

<h3>Objective</h3> The goal of these studies is to discover novel urinary biomarkers of lupus nephritis (LN). <h3>Methods</h3> Urine from systemic lupus erythematosus (SLE) patients was interrogated for 1000 proteins using a novel, quantitative planar protein microarray. Hits were validated in an independent SLE cohort with inactive, active non-renal (ANR) and active renal (AR) patients, in a cohort with concurrent renal biopsies, and in a longitudinal cohort. Single-cell renal RNA sequencing data from LN kidneys were examined to deduce the cellular origin of each biomarker. <h3>Results</h3> Screening of 1000 proteins revealed 64 proteins to be significantly elevated in SLE urine, of which 17 were ELISA validated in independent cohorts. Urine Angptl4 (area under the curve (AUC)=0.96), L-selectin (AUC=0.86), TPP1 (AUC=0.84), transforming growth factor-β1 (TGFβ1) (AUC=0.78), thrombospondin-1 (AUC=0.73), FOLR2 (AUC=0.72), platelet-derived growth factor receptor-β (AUC=0.67) and PRX2 (AUC=0.65) distinguished AR from ANR SLE, outperforming anti-dsDNA, C3 and C4, in terms of specificity, sensitivity and positive predictive value. In multivariate regression analysis, urine Angptl4, L-selectin, TPP1 and TGFβ1 were highly associated with disease activity, even after correction for demographic variables. In SLE patients with serial follow-up, urine L-selectin (followed by urine Angptl4 and TGFβ1) were best at tracking concurrent or pending disease flares. Importantly, several proteins elevated in LN urine were also expressed within the kidneys in LN, either within resident renal cells or infiltrating immune cells, based on single-cell RNA sequencing analysis. <h3>Conclusion</h3> Unbiased planar array screening of 1000 proteins has led to the discovery of urine Angptl4, L-selectin and TGFβ1 as potential biomarker candidates for tracking disease activity in LN.