Urine Soluble CD163 Is a Promising Biomarker for the Diagnosis and Evaluation of Lupus Nephritis

Urinary MCP-1 and VCAM-1 as non-invasive biomarkers for the diagnosis and activity assessment of lupus nephritis

INTRODUCTION

Accurate diagnosis of lupus nephritis (LN) and effective assessment of its disease activity are essential for optimal management. This study aimed to evaluate the potential of novel urinary biomarkers, MCP-1 and VCAM-1, in diagnosing and assessing LN activity, comparing their efficacy to traditional urinary biomarkers, and proposing a new standard for clinical application.

METHODS

A total of 55 LN patients who met the 1997 ACR diagnostic criteria for systemic lupus erythematosus (SLE) and 34 healthy controls (HCs) were included in this study. The LN patients were categorized into two groups based on their SLE disease activity indices (SLEDAI): the inactive lupus nephritis (NALN) group (SLEDAI 0-4, n = 32) and the active lupus nephritis (ALN) group (renal SLEDAI ≥ 4, n = 22). Additionally, the patients were further classified into mild (SLEDAI 5-9), moderate (SLEDAI 10-14), and severe (SLEDAI > 14) subgroups. All LN patients underwent testing for urinary MCP-1 (uMCP-1), urinary VCAM-1 (uVCAM-1), urinary α1-microglobulin (u-α1MG), urinary β2-microglobulin (u-β2MG), urinary IgG (u-IgG), and urinary albumin (u-ALB), as well as a percutaneous renal biopsy.

RESULTS

The levels of urinary MCP-1 and VCAM-1 (uMCP-1 and uVCAM-1) in the LN group were significantly elevated compared to the HCs (uMCP-1: P < 0.001; uVCAM-1: P < 0.01). Receiver operating characteristic (ROC) curve analysis revealed that the diagnostic efficacy of uMCP-1 and uVCAM-1 surpassed that of traditional biomarkers (uMCP-1: AUC = 0.79, P < 0.001; uVCAM-1: AUC = 0.77, P < 0.001). Multivariate logistic regression demonstrated a significant association between uMCP-1 and uVCAM-1 levels and the occurrence of LN (P < 0.001). Furthermore, these novel biomarkers exhibited stronger correlations with SLEDAI scores than traditional biomarkers (P < 0.001). Notably, patients with ALN had significantly higher levels of uMCP-1 and uVCAM-1 compared to those with NALN (uMCP-1: P < 0.01; uVCAM-1: P < 0.01).

CONCLUSION

The production of uMCP-1 and uVCAM-1 is closely associated with the onset and progression of LN (ISN/RPS: Class I - IV). These biomarkers may serve as valuable references for the diagnosis and prediction of LN and aid in the assessment of LN activity.

Association of low-grade proteinuria with changes of lupus nephritis in kidney biopsy in SLE patients

BackgroundA kidney biopsy is essential for definitive histopathological diagnosis in lupus nephritis, informing therapeutic strategies. Current guidelines (ACR and EULAR/ERA-EDTA) do not include a kidney biopsy for patients with isolated proteinuria of less than 500 mg/g. We explored the histopathologic findings in patients with SLE with proteinuria ≤500 mg/g.MethodsWe conducted a retrospective review of 27 biopsies of lupus patients with proteinuria ≤500 mg/g who underwent a kidney biopsy at Johns Hopkins. Clinical and laboratory data were obtained from a review of the medical records. The study was approved by the Office of Human Subjects Research and Institutional Review Board.ResultsMost individuals were females (93%) and African American (56%), with a mean age of 42.1 (12.4) years at the time of biopsy. Twelve individuals had no prior history of lupus nephritis. The average creatinine at the biopsy was 1.05 mg/dl, and UPCR was 0.27 grams/gram. Most patients (100%) were on hydroxychloroquine, 41% were on prednisone, and 33% were on mycophenolate mofetil. Kidney biopsies were most commonly performed based on extra-renal disease activity, new-onset or worsening proteinuria (88.9%) and worsening dsdNA levels (55.6%). At the time of biopsy, 55.6% of patients presented with extrarenal lupus, most commonly arthritis or arthralgias and mucosal ulcers. Of the 27 patients, 23 patients had evidence of lupus nephritis (85.1%), including class III (33%), V (30%), III/V (7%), class II (4%) and class I (11%). Nine patients had a UPCR of 200 mg/g or lower. Among these patients, 22% did not show signs of lupus nephritis in the kidney biopsy, 44% had class V LN, and 11% had class I and III LN. Kidney biopsy was well tolerated, with the majority (93%) not developing post-biopsy complications.ConclusionsWe identified patients with proteinuria ≤500 mg/g who had lupus nephritis, with the majority ranging from Class III to V with only one class II. This study supports that normal or low UPCR <500 mg/g lacks the sensitivity to detect early lupus nephritis. Better biomarkers for the cutoff of biopsy are needed to improve kidney outcomes and trial design.

Urinary presepsin is a novel biomarker capable of directly assessing monocyte/macrophage infiltration in kidney diseases

Serum presepsin levels are elevated during sepsis and are widely employed in clinical practice. However, the association between urinary presepsin and kidney diseases remains elusive. Given that monocytes/macrophages, primary presepsin producers, are closely associated with the pathophysiology of nephritis, we explored the potential of urinary presepsin as a kidney disease biomarker. In a cross-sectional study involving patients who underwent kidney biopsy (n = 463 patients; 43% female, median age 58 years), the median urinary presepsin/creatinine levels were 590 (interquartile range [IQR], 244-1276), 1023 (IQR, 491-2749), 1429 (IQR, 644-2725), and 3518 (IQR, 2084-6321) ng/g creatinine, indicating minimal (< 5%), mild (5-25%), moderate (26-50%), and severe (> 50%) interstitial inflammatory cell infiltration in biopsy samples, respectively. The area under the curve of urinary presepsin/creatinine (0.81) had a higher accuracy for distinguishing severe interstitial inflammatory cell infiltration than that of the N-acetyl-β-D-glucosaminidase/creatinine (0.70) (P = 0.003). The tubulointerstitial nephritis group had the highest urinary presepsin/creatinine level. Immunofluorescence staining revealed that monocytes and macrophages predominantly expressed presepsin in the kidney interstitium, with the stained area positively and significantly correlated with presepsin/creatinine values (r = 0.57, P = 0.02). Urinary presepsin could be a biomarker for directly assessing monocyte/macrophage infiltration in kidney disease.

Biomarkers for systemic lupus erythematosus: A scoping review

BACKGROUND

In recent years, newly discovered potential biomarkers have great research potential in the diagnosis, disease activity prediction, and treatment of systemic lupus erythematosus (SLE).

OBJECTIVE

In this study, a scoping review of potential biomarkers for SLE over several years has identified the extent to which studies on biomarkers for SLE have been conducted, the specificity, sensitivity, and diagnostic value of potential biomarkers of SLE, the research potential of these biomarkers in disease diagnosis, and activity detection is discussed.

METHODS

In PubMed and Google Scholar databases, "SLE," "biomarkers," "predictor," "autoimmune diseases," "lupus nephritis," "neuropsychiatric SLE," "diagnosis," "monitoring," and "disease activity" were used as keywords to systematically search for SLE molecular biomarkers published from 2020 to 2024. Analyze and summarize the literature that can guide the article.

CONCLUSIONS

Recent findings suggest that some potential biomarkers may have clinical application prospects. However, to date, many of these biomarkers have not been subjected to repeated clinical validation. And no single biomarker has sufficient sensitivity and specificity for SLE. It is not scientific to choose only one or several biomarkers to judge the complex disease of SLE. It may be a good direction to carry out a meta-analysis of various biomarkers to find SLE biomarkers suitable for clinical use, or to evaluate SLE by combining multiple biomarkers through mathematical models. At the same time, advanced computational methods are needed to analyze large data sets and discover new biomarkers, and strive to find biomarkers that are sensitive and specific enough to SLE and can be used in clinical practice, rather than only staying in experimental research and data analysis.

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.