Proximity extension assay proteomics and renal single cell transcriptomics uncover novel urinary biomarkers for active lupus nephritis.

OBJECTIVE: To identify urinary biomarkers that can distinguish active renal involvement in Lupus Nephritis (LN), a severe manifestation of systemic lupus erythematosus (SLE). METHODS: Urine from 117 subjects, comprised of inactive SLE, active non-renal lupus, active LN, and healthy controls, were subjected to Proximity Extension Assay (PEA) based comprehensive proteomics followed by ELISA validation in an independent, ethnically diverse cohort. Proteomic data is also cross-referenced to renal transcriptomic data to elucidate cellular origins of biomarkers. RESULTS: Systems biology analyses revealed progressive activation of cytokine signaling, chemokine activity and coagulation pathways, with worsening renal disease. In addition to validating 30 previously reported biomarkers, this study uncovers several novel candidates. Following ELISA validation in an independent cohort of different ethnicity, the six most discriminatory biomarkers for active LN were urinary ICAM-2, FABP4, FASLG, IGFBP-2, SELE and TNFSF13B/BAFF, with ROC AUC ≥80%, with most correlating strongly with clinical disease activity. Transcriptomic analyses of LN kidneys mapped the likely origin of these proteins to intra-renal myeloid cells (CXCL16, IL-1RT2, TNFSF13B/BAFF), T/NK cells (FASLG), leukocytes (ICAM2) and endothelial cells (SELE). CONCLUSION: In addition to confirming the diagnostic potential of urine ALCAM, CD163, MCP1, SELL, ICAM1, VCAM1, NGAL and TWEAK for active LN, this study adds urine ICAM-2, FABP4, FASLG, IGFBP-2, SELE, and TNFSF13B/BAFF as additional markers that warrant systematic validation in larger cross-sectional and longitudinal cohorts.

Late onset granulomatous interstitial nephritis after booster dose of COVID-19 vaccination: Case report and review of literature.

Billions of doses of COVID-19 vaccine have been administered to combat the coronavirus pandemic. Though the vaccine is generally well tolerated, several cases of new onset or relapsing glomerulonephritis have been reported. In comparison, post-vaccination tubulointerstitial nephritis (TIN) has rarely been reported, mostly after the first or the second dose of the vaccine. Acute interstitial nephritis after booster dose of COVID-19 vaccination has not yet been reported. We report a case of acute granulomatous TIN shortly after the booster dose of Moderna vaccine. Our patient had no clinical evidence of renal injury after the first two doses of vaccine. Renal dysfunction was incidentally observed ~ 1 month after the booster dose of vaccine. The patient responded to steroids with rapid improvement in kidney function. While it is difficult to ascertain the causal relationship between the vaccination and development of TIN, it is important to be vigilant about such delayed side effects of the vaccine.

Upregulation of Proinflammatory Bradykinin Peptides in Systemic Lupus Erythematosus and Rheumatoid Arthritis.

Our recent study has implicated bradykinin (BK) signaling as being of pathogenic importance in lupus. This study aims to investigate the biomarker potential of BK peptides, BK and BK-des-arg-9, in lupus and other rheumatic autoimmune diseases. Sera from systemic lupus erythematosus (SLE) patients and healthy subjects were screened for BK and BK-des-arg-9 by liquid chromatography-mass spectrometry metabolomics. Serum from 6-mo-old C57BL/6 mice and three murine lupus strains were also screened for the two peptides by metabolomics. Given the promising initial screening results, validation of these two peptides was next conducted using multiple reaction monitoring in larger patient cohorts. In initial metabolomics screening, BK-des-arg-9 was 22-fold higher in SLE serum and 106-fold higher in mouse lupus serum compared with healthy controls. In validation assays using multiple reaction monitoring and quadrupole time-of-flight mass spectrometry, BK and BK-des-arg-9 showed significant elevations in SLE serum compared with controls (p < 0.0001; area under the curve = 0.79-0.88), with a similar but less pronounced increase being noted in rheumatoid arthritis serum. Interestingly, increased renal SLE disease activity index in lupus patients was associated with reduced circulating BK-des-arg-9, and the reasons for this remain to be explored. To sum, increased conversion of BK to the proinflammatory metabolite BK-des-arg-9 appears to be a common theme in systemic rheumatic diseases. Besides serving as an early marker for systemic autoimmunity, independent studies also show that this metabolic axis may also be a pathogenic driver and therapeutic target in lupus.

De novo or recurrent glomerulonephritis and acute tubulointerstitial nephritis after COVID-19 vaccination: A report of six cases from a single center.

Billions of COVID-19 vaccine doses have been administered to combat the ongoing global pandemic caused by severe acute respiratory syndrome coronavirus-2. While these vaccines are considered safe, with most adverse events being mild to moderate and transient, uncommon systemic side effects of the vaccines, including de novo or re-activation of various glomerular diseases have recently been observed. We report 6 patients who developed glomerular or acute tubulointerstitial disease shortly after receiving COVID-19 vaccinations. Five of these patients received mRNA vaccines (3 Moderna, 2 Pfizer-BioNTech) and 1 received adenovirus-26 vector vaccine (Johnson and Johnson/Janssen). Four of our patients developed de novo glomerulonephritis or acute tubulointerstitial nephritis (ATIN), while the other 2 had re-activation of prior glomerulonephritis. Two patients presented with acute kidney injury (AKI) characterized by severe ATIN. While both of them also had evidence of immune complex glomerular disease, ATIN was the dominant feature on the biopsies. Two other patients presented with high-grade proteinuria and AKI. Like the aforementioned patients, these patients had evidence of immune complex glomerular disease, but acute onset nephrotic syndrome was the leading clinical feature. Another patient presented with de novo myeloperoxidase-anti-neutrophil-cytoplasmic-antibody-associated pauci-immune crescentic glomerulonephritis. Yet another patient had re-activation of immunoglobulin-A glomerulonephritis that had been quiescent for several years prior to the vaccination. It is difficult to ascertain any causal relationship between COVID-19 vaccination and onset/recurrence of kidney diseases. However, vigilance about occurrence of such complications is imperative. Importantly, all our cases responded well to the immunosuppressive treatment.

Peritoneal Dialysis Use in Patients With Ascites: A Review.

The past few decades have seen steady increase in the prevalence of kidney failure needing kidney replacement therapy. Concomitantly, there has been progressive growth of heart failure and chronic liver disease, and many such patients develop ascites. Therefore, it is not uncommon to encounter patients with kidney failure who concurrently have ascites. The presence of ascites adds many challenges in the management of kidney failure. Poor hemodynamics make volume management difficult. The presence of coagulopathy, malnutrition, and encephalopathy compounds the complexity of the management. Such patients do not tolerate hemodialysis well. However, several concerns have limited the use of peritoneal dialysis (PD), so hemodialysis remains the predominant dialysis modality in these patients. However, observational studies have illustrated that PD provides hemodynamic stability and facilitates better volume management compared with hemodialysis. Moreover, PD obviates the need for therapeutic paracentesis by facilitating continuous drainage of ascites. PD potentially reduces hemorrhagic complications by avoiding routine anticoagulation use. Moreover, small studies have suggested that outcomes such as peritonitis and mechanical complications are comparable to those in PD patients without ascites. PD does not affect transplant candidacy, and these patients can successfully receive combined liver and kidney transplants. Hence, PD should be considered a viable dialysis option in kidney failure patients with ascites.

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

OBJECTIVE: The goal of these studies is to discover novel urinary biomarkers of lupus nephritis (LN). METHODS: 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. RESULTS: 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-ß1 (TGFß1) (AUC=0.78), thrombospondin-1 (AUC=0.73), FOLR2 (AUC=0.72), platelet-derived growth factor receptor-ß (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 TGFß1 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 TGFß1) 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. CONCLUSION: Unbiased planar array screening of 1000 proteins has led to the discovery of urine Angptl4, L-selectin and TGFß1 as potential biomarker candidates for tracking disease activity in LN.

Elevated oxidized lipids, anti-lipid autoantibodies and oxidized lipid immune complexes in active SLE.

BACKGROUND: Here, we explore the serum levels of anti-oxidized lipid autoantibodies as well as immune complexes in patients with SLE and determine their correlation with disease. METHODS: Serum levels of oxidized-LDL immune complexes, autoantibodies to dsDNA, ox-LDL, MDA-LDL, 9-HODE, 13-HODE and POVPC were detected by ELISA in 64 SLE patients and 9 healthy controls. RESULTS: Active SLE patients exhibited increased serum levels of autoantibodies compared to healthy controls, including anti-MDA-LDL-IgG (p = .003), anti-ox-LDL-IgG (p = .004), anti-9-HODE-IgG (p = .001), anti-13-HODE-IgG (p = .0003), anti-POVPC-IgG (p = .001) and ox-LDL-IC (p = .003). Serum anti-ox-LDL-IgG was positively correlated with SLEDAI (r = 0.34; p = .01), and negatively with C3 (r = -0.40; p = .01). Anti-9-HODE-IgG and anti-POVPC-IgG were positively correlated with SLEDAI and negatively with C4. CONCLUSIONS: Active SLE patients exhibit significantly increased serum levels of IgG anti-oxidized-lipid autoantibodies. Coordinated elevation of oxidized lipids, autoantibodies to these lipids, and immune complexes of these lipid-antibody components could potentially serve as pathogenic drivers and serum markers of SLE disease activity.

Neisseria mucosa Peritonitis in the Setting of a Migrated Intrauterine Device.

Peritonitis is a major complication in peritoneal dialysis (PD) patients, often requiring a switch to hemodialysis (HD). Common sources of bacterial peritonitis are touch contamination and PD catheter-related infection. Intra-abdominal pathology is a less common cause of peritonitis in PD patients, and rarely is Neisseria mucosa the causative organism.We present an uncommon case of N. mucosa peritonitis in a 30-year-old African American female patient treated with nocturnal intermittent PD. The infection occurred in the setting of a translocated intrauterine contraceptive device (IUCD) in the infrahepatic region because of transmural migration. Our patient underwent laparoscopic removal of the IUCD and received empiric intraperitoneal (IP) vancomycin and intravenous ceftriaxone. After the isolate was identified as N. mucosa, her regimen was changed to IP ceftriaxone for a total of 21 days. Cell count after completion of antibiotics showed resolution of the peritonitis. The PD catheter was salvaged and transition to HD was avoided.

Prognostic significance of repeat biopsy in lupus nephritis: Histopathologic worsening and a short time between biopsies is associated with significantly increased risk for end stage renal disease and death.

BACKGROUND/PURPOSE: Approximately half of patients with systemic lupus erythematosus (SLE) develop lupus nephritis (LN), a major cause of morbidity and early mortality in that disease. Prolonged renal inflammation is associated with irreversible kidney damage which confers a 30% risk of end stage renal disease (ESRD), making early, aggressive treatment mandatory. Failure to achieve therapeutic response or recurrence of renal flare often prompts repeat biopsy. However, the role of repeat biopsy in determining long-term renal prognosis remains controversial. For this reason repeat biopsies are usually not utilized unless clinical evidence of refractory or recurrent disease is already present, despite known mismatches between clinical and biopsy findings. The current study quantifies the degree to which histopathologic worsening between first and second biopsies and duration between them predicts ESRD and death. METHODS: Medical records of 141 LN patients with more than one biopsy were obtained from a single large urban medical center. Cases were attained using billing codes for diagnosis and procedures from 1/1999-1/2015. Biopsy worsening was defined as unfavorable histopathologic classification transitions and/or increased chronicity; if neither were present, the patient was defined as non-worsening. We used Cox proportional hazard models to study the relationship between ESRD and survival adjusting for covariates which included age at first biopsy, gender, race, initial biopsy class, and initial induction therapy. RESULTS: Of 630 patients screened, 141 had more than one biopsy. Advancing chronicity was detected in 48 (34.0%) and a renal class switch to worse grade of pathology was found in 54 (38.3%). At least one of these adverse second biopsy features was reported in 79 (56.0%) patients. Five years following initial biopsy, 28 (35.4%) of those with worsening histopathology on second biopsy developed ESRD, compared to 6 (9.7%) of non-worsening patients and 10 (12.7%) of patients with worsening histopathology had died compared to 2 (3.2%) of non-worsening patients. Biopsy worsening was associated with a significantly greater 15-year risk of ESRD (Hazard Ratio 4.2, p=0.0001) and death (Hazard Ratio 4.3, p=0.022), adjusting for age, gender, race, biopsy class, and treatment. Time between first and second biopsies was <1year in 32 patients, 1-5years in 81, and >5years in 28. Over a 15-year period, those with <1year between first and second biopsies (presumably enriched for patients with early clinical signs of progression) had a significantly greater risk of ESRD (Hazard Ratio 13.7, p<0.0001) and death (Hazard Ratio 16.9, p=0.0022) after adjusting for age, gender, race, biopsy class, and treatment. CONCLUSION: A repeat renal biopsy demonstrating worsening pathology increases the risk of ESRD and death more than four-fold compared to non-worsening patients. Given known potential mismatch between biopsy and clinical data, repeat biopsies may add important information and justify changes in treatment not considered on clinical grounds. Earlier detection of poor prognostic signs in those without early clinical deterioration might improve outcomes in enough patients to reconsider cost effectiveness of routine repeat biopsy.

Antibody-Array-Based Proteomic Screening of Serum Markers in Systemic Lupus Erythematosus: A Discovery Study.

A discovery study was carried out where serum samples from 22 systemic lupus erythematosus (SLE) patients and matched healthy controls were hybridized to antibody-coated glass slide arrays that interrogated the level of 274 human proteins. On the basis of these screens, 48 proteins were selected for ELISA-based validation in an independent cohort of 28 SLE patients. Whereas AXL, ferritin, and sTNFRII were significantly elevated in patients with active lupus nephritis (LN) relative to SLE patients who were quiescent, other molecules such as OPN, sTNFRI, sTNFRII, IGFBP2, SIGLEC5, FAS, and MMP10 exhibited the capacity to distinguish SLE from healthy controls with ROC AUC exceeding 90%, all with p < 0.001 significance. These serum markers were next tested in a cohort of 45 LN patients, where serum was obtained at the time of renal biopsy. In these patients, sTNFRII exhibited the strongest correlation with eGFR (r = -0.50, p = 0.0014) and serum creatinine (r = 0.57, p = 0.0001), although AXL, FAS, and IGFBP2 also correlated with these clinical measures of renal function. When concurrent renal biopsies from these patients were examined, serum FAS, IGFBP2, and TNFRII showed significant positive correlations with renal pathology activity index, while sTNFRII displayed the highest correlation with concurrently scored renal pathology chronicity index (r = 0.57, p = 0.001). Finally, in a longitudinal cohort of seven SLE patients examined at ∼3 month intervals, AXL, ICAM-1, IGFBP2, SIGLEC5, sTNFRII, and VCAM-1 demonstrated the ability to track with concurrent disease flare, with significant subject to subject variation. In summary, serum proteins have the capacity to identify patients with active nephritis, flares, and renal pathology activity or chronicity changes, although larger longitudinal cohort studies are warranted.

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

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

Duplex Vertical-Flow Rapid Tests for Point-of-Care Detection of Anti-dsDNA and Anti-Nuclear Autoantibodies.

The goal of this study is to develop a rapid diagnostic test for rheumatic disease and systemic lupus erythematosus (SLE) screening. A novel rapid vertical flow assay (VFA) was engineered and used to assay anti-nuclear (ANA) and anti-dsDNA (αDNA) autoantibodies from systemic lupus erythematosus (SLE) patients and healthy controls (HCs). Observer scores and absolute signal intensities from the VFA were validated via ELISA. The rapid point-of-care VFA test that was engineered demonstrated a limit of detection of 0.5 IU/mL for ANA and αDNA autoantibodies in human plasma with an inter-operator CV of 19% for ANA and 12% for αDNA. Storage stability was verified over a three-month period. When testing anti-dsDNA and ANA levels in SLE and HC serum samples, the duplex VFA revealed 95% sensitivity, 72% specificity and an 84% ROC AUC value in discriminating disease groups, comparable to the gold standard, ELISA. The rapid αDNA/ANA duplex VFA can potentially be used in primary care clinics for evaluating patients or at-risk subjects for rheumatic diseases and for planning follow-up testing. Given its low cost, ease, and rapid turnaround, it can also be used to assess SLE prevalence estimates.

Advancing Point-of-Care Diagnosis: Digitalizing Combinatorial Biomarker Signals for Lupus Nephritis.

To improve the efficiency and patient coverage of the current healthcare system, user-friendly novel homecare devices are urgently needed. In this work, we developed a smartphone-based analyzing and reporting system (SBARS) for biomarker detection in lupus nephritis (LN). This system offers a cost-effective alternative to traditional, expensive large equipment in signal detection and quantification. This innovative approach involves using a portable and affordable microscopic reader to capture biomarker signals. Through smartphone-based image processing techniques, the intensity of each biomarker signal is analyzed. This system exhibited comparable performance to a commercial Genepix scanner in the detection of two potential novel biomarkers of LN, VISG4 and TNFRSF1b. Importantly, this smartphone-based analyzing and reporting system allows for discriminating LN patients with active renal disease from healthy controls with the area-under-the-curve (AUC) value = 0.9 for TNFRSF1b and 1.0 for VSIG4, respectively, indicating high predictive accuracy.

Physiological principles underlying the kidney targeting of renal nanomedicines.

Kidney disease affects more than 10% of the global population and is associated with considerable morbidity and mortality, highlighting a need for new therapeutic options. Engineered nanoparticles for the treatment of kidney diseases (renal nanomedicines) represent one such option, enabling the delivery of targeted therapeutics to specific regions of the kidney. Although they are underdeveloped compared with nanomedicines for diseases such as cancer, findings from preclinical studies suggest that renal nanomedicines may hold promise. However, the physiological principles that govern the in vivo transport and interactions of renal nanomedicines differ from those of cancer nanomedicines, and thus a comprehensive understanding of these principles is needed to design nanomedicines that effectively and specifically target the kidney while ensuring biosafety in their future clinical translation. Herein, we summarize the current understanding of factors that influence the glomerular filtration, tubular uptake, tubular secretion and extrusion of nanoparticles, including size and charge dependency, and the role of specific transporters and processes such as endocytosis. We also describe how the transport and uptake of nanoparticles is altered by kidney disease and discuss strategic approaches by which nanoparticles may be harnessed for the detection and treatment of a variety of kidney diseases.

iTRAQ-based mass spectrometry screen to identify serum biomarkers in systemic lupus erythematosus.

OBJECTIVE: Systemic lupus erythematosus (SLE) is a complex systemic autoimmune disorder with no reliable serum biomarkers currently available other than autoantibodies. METHODS: In the present study, isobaric tags for relative and absolute quantitation-based mass spectrometry was used to screen the sera of patients with SLE to uncover potential disease biomarkers. RESULTS: 85 common proteins were identified, with 16 being elevated (≥1.3) and 23 being decreased (≤0.7) in SLE. Of the 16 elevated proteins, serum alpha-1-microglobulin/bikunin precursor (AMBP), zinc alpha-2 glycoprotein (AZGP) and retinol-binding protein 4 (RBP4) were validated in independent cross-sectional cohorts (Cohort I, N=52; Cohort II, N=117) using an orthogonal platform, ELISA. Serum AMBP, AZGP and RBP4 were validated to be significantly elevated in both patients with inactive SLE and patients with active SLE compared with healthy controls (HCs) (p<0.05, fold change >2.5) in Cohort I. All three proteins exhibited good discriminatory power for distinguishing active SLE and inactive SLE (area under the curve=0.82-0.96), from HCs. Serum AMBP exhibited the largest fold change in active SLE (5.96) compared with HCs and correlated with renal disease activity. The elevation in serum AMBP was validated in a second cohort of patients with SLE of different ethnic origins, correlating with serum creatinine (r=0.60, p<0.001). CONCLUSION: Since serum AMBP is validated to be elevated in SLE and correlated with renal disease, the clinical utility of this novel biomarker warrants further analysis in longitudinal cohorts of patients with lupus and lupus nephritis.

Rare case of Ralstonia mannitolilytica peritonitis in an adult peritoneal dialysis patient.

Peritonitis is a common complication of peritoneal dialysis (PD) usually caused by skin-dwelling Gram-positive bacteria and Gram-negative bacteria colonizing the gut and urinary tract. Occasionally, uncommon bacteria can cause peritonitis in PD patients. We describe a case of Ralstonia mannitolilytica peritonitis in a 67-year-old woman who has been on PD for more than 10 years with no prior episodes of peritonitis. To our knowledge, this is the first reported case of Ralstonia peritonitis in the United States. She initially presented with abdominal tenderness, right flank pain, and cloudy output from her nephrostomy tube. PD fluid and urine cultures grew E. coli which responded to treatment. However, her symptoms recurred after completion of antibiotic therapy with PD fluid growing Ralstonia species. She again responded to intraperitoneal antibiotics but had recurrence of symptoms after the completion of her second course of antibiotics. PD fluid grew Ralstonia mannitolilytica resistant to the prior antibiotic regimen. The PD catheter was removed, and she was transitioned to hemodialysis. Subsequent treatment led to the resolution of her symptoms. Ralstonia species are Gram-negative bacteria that are prevalent in water supplies and can form biofilms. They have been known to cause infection particularly in neonates, immunocompromised patients, or patients in intensive care. In our patient, prior antibiotic treatment for E. coli peritonitis is likely to have contributed to the development of Ralstonia peritonitis. Clinical improvement after removal of the PD catheter revealed that seeding from the PD catheter was the likely culprit for the recurrent infections.

Treatment of lupus nephritis: consensus, evidence and perspectives.

Despite the continuing development of immunomodulatory agents and supportive care, the prognosis associated with lupus nephritis (LN) has not improved substantially in the past decade, with end-stage kidney disease still developing in 5-30% of patients within 10 years of LN diagnosis. Moreover, inter-ethnic variation in the tolerance of, clinical response to and level of evidence regarding various therapeutic regimens for LN has led to variation in treatment prioritization in different international recommendations. Modalities that better preserve kidney function and reduce the toxicities of concomitant glucocorticoids are unmet needs in the development of therapeutics for LN. In addition to the conventional recommended therapies for LN, there are newly approved treatments as well as investigational drugs in the pipeline, including the newer generation calcineurin inhibitors and biologic agents. In view of the heterogeneity of LN in terms of clinical presentation and prognosis, the choice of therapies depends on a number of clinical considerations. Molecular profiling, gene-signature fingerprints and urine proteomic panels might enhance the accuracy of patient stratification for treatment personalization in the future.

V-Set Immunoglobulin Domain-Containing Protein 4 as a Novel Serum Biomarker of Lupus Nephritis and Renal Pathology Activity.

OBJECTIVE: To discover novel serum biomarkers that have diagnostic or predictive value in lupus nephritis (LN). METHODS: Using a quantitative protein microarray, we screened for high-abundant proteome expression in the serum of patients with LN compared to healthy controls. Top candidates from this screening were validated using a larger cohort of patients with LN compared to a disease control cohort (subjects with other chronic kidney diseases) and a healthy control cohort. Promising markers were then selected using a machine-learning model and further validated with a larger patient cohort. The corresponding autoantibodies and immune complexes containing these proteins were also examined. RESULTS: In total, 13 proteins were found to be significantly elevated in LN patient serum in the screening, among which 8 proteins were validated by enzyme-linked immunosorbent assay using 81 serum samples from LN patients and control subjects. Three serum markers with LN diagnostic potential were identified using feature importance analysis and further validated using 155 serum samples from LN patients and control subjects. V-set immunoglobulin domain-containing protein 4 (VSIG4) appeared to be the most promising marker in distinguishing LN from healthy controls, with an area under the curve of 0.93. VSIG4 could also discriminate active LN from inactive LN. Furthermore, serum VSIG4 levels were positively correlated with all of the following clinical parameters: the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score (Spearman's rank correlation rs = 0.42, P < 0.001), the renal domain score of the SLEDAI (rs = 0.46, P < 0.001), the urinary protein-to-creatinine ratio (rs = 0.56, P < 0.001), and the serum creatinine level (rs = 0.41, P < 0.001). Importantly, we found that serum VSIG4 levels tracked with LN disease activity longitudinally, and that serum VSIG4 levels reflected the renal pathology activity index (AI), particularly the AI components of crescent formation and hyaline deposits. CONCLUSION: VSIG4 may be a promising novel serum biomarker and therapeutic target in patients with LN.

Urine L-selectin reflects clinical and histological renal disease activity and treatment response in lupus nephritis across multi-ethnicity.

Objective: There is an urgent need for novel biomarkers in lupus nephritis (LN). We report a non-invasive urinary biomarker, L-selectin, in two independent multi-ethnic cohorts. Methods: uL-selectin was tested cross-sectionally in a Chinese cohort (n=255) and a US cohort (n=219) of SLE patients and controls using ELISA. A longitudinal cohort includes 20 active Chinese LN patients. Results: uL-selectin was significantly increased in active LN patients compared to active non-renal SLE, inactive LN, inactive non-renal SLE, chronic kidney disease patients, and healthy controls. uL-selectin positively correlated with global and renal disease activities as well as histological activity index and chronicity index (CI). Low uL-selectin was an independent predictor for high CI. During follow-up, uL-selectin levels decreased significantly in the complete renal remission group. Conclusion: uL-selectin is a novel biomarker of disease activity and renal histopathology in LN across multiple ethnicities. It also reflects treatment response in LN patients during follow up.