The Kidney Biopsy in Systemic Lupus Erythematosus: A View of the Past and a Vision of the Future

A rare case of non-lupus full house nephropathy in a transplanted kidney, case report

Key Clinical Message

Non-lupus full house nephropathy is a rare entity that is still poorly understood. It can complicate post-transplant kidneys and result in a de novo process. Treatment is difficult but can be possibly achieved with optimization of immune suppression.

Abstract

Non-lupus full house nephropathy is a rare entity with an unclear incidence. It describes the kidney biopsy findings of positive deposits for IgG, IgA, IgM, C3, and C1q on immunofluorescence in the absence of the classical diagnostic features of systemic lupus nephritis. This disease entity is becoming more recognized but further studies are still needed to evaluate the incidence, etiologies, and management of this condition. Transplant glomerulopathy is a major cause for renal graft loss. It can present with a wide variety of manifestations; it can cause AKI, CKD, or glomerular inflammations through an immune complex or autoimmune-mediated damage.

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.

A nomogram predicting the histologic activity of lupus nephritis from clinical parameters

BACKGROUND

The 2021 clinical guidelines of the Kidney Disease: Improving Global Outcomes emphasize the importance of the histological activity index (AI) in the management of lupus nephritis (LN). Patients with LN and a high AI have poor renal outcomes and high rates of nephritic relapse. In this study we constructed prediction models for the AI in LN.

METHODS

The study population comprised 337 patients diagnosed with LN using kidney biopsy. The participants were randomly divided into training and testing cohorts. They were further divided into high-activity (AI >2) and low-activity (AI ≤2) groups. This study developed two clinical prediction models using logistic regression and least absolute shrinkage and selection operator (LASSO) analyses with laboratory test results collected at the time of kidney biopsy. The performance of models was assessed using 5-fold cross-validation and validated in the testing cohort. A nomogram for individual assessment was constructed based on the preferable model.

RESULTS

Multivariate analysis showed that higher mean arterial pressure, lower estimated glomerular filtration rate, lower complement 3 level, higher urinary erythrocytes count and anti-double-stranded DNA seropositivity were independent risk factors for high histologic activity in LN. Both models performed well in the testing cohort regarding the discriminatory ability to identify patients with an AI >2. The average area under the curve of 5-fold cross-validation was 0.855 in the logistic model and 0.896 in the LASSO model. A webtool based on the LASSO model was created for clinicians to enter baseline clinical parameters to produce a probability score of an AI >2.

CONCLUSIONS

The established nomogram provides a quantitative auxiliary tool for distinguishing LN patients with a high AI and helps physicians make clinical decisions in their comprehensive assessment.

Kidney Biopsy in Management of Lupus Nephritis: A Case-Based Narrative Review

Kidney involvement in patients with lupus highly increases morbidity and mortality. In recent years, several reports have emphasized the dissociation between clinical and histological findings and highlighted the role of kidney biopsy as an instrument for diagnosis and follow-up of lupus nephritis. The kidney biopsy at initial diagnosis allows an early diagnosis, assessment of activity and chronicity, and detection of nonimmune complex nephritis. A kidney biopsy repeated months after treatment aids in the detection of persistent histological inflammation, which has been linked to the occurrence of future kidney relapses. A kidney biopsy at a relapse detects histological changes including chronic scarring. Finally, a kidney biopsy in patients with a clinical response undergoing maintenance immunosuppression may aid therapy tapering and/or suspension. The evidence supporting the use of a kidney biopsy in different scenarios across the course of lupus nephritis is heterogeneous, with most reports assessing the value for the diagnosis of a first or relapsing flare. In contrast, less evidence suggests additional therapeutic-modifying information derived from repeat posttreatment biopsies and biopsies to evaluate treatment tapering or suspension. In this clinical case-based review, we examine the role of kidney biopsy as a tool to improve clinical outcomes of patients with lupus nephritis.

Research progress in functional magnetic resonance imaging assessment of lupus nephritis kidney injury

Lupus nephritis is one of the most common and severe complications of systemic lupus erythematosus and is also a major predictor of poor prognosis and mortality. Lupus nephritis has the characteristics of insidious onset, complex pathological types, rapid progression of organ damage, and easy recurrence. Currently, kidney damage in lupus nephritis is usually assessed based on urine analysis, renal biopsy, and glomerular filtration rates. However, they all have certain limitations, making it difficult to diagnose lupus nephritis early and assess its severity and progression. With the rapid development of functional magnetic resonance, multiple functional imaging techniques are expected to provide more useful information for the pathophysiological development, early diagnosis, progression, prognosis, and renal function evaluation of lupus nephritis. This article reviews the principle of multiple functional magnetic resonance imaging and the research status of evaluating renal function in lupus nephritis.

Diagnosis and treatment of lupus nephritis: a summary of the Consensus Document of the Spanish Group for the Study of Glomerular Diseases (GLOSEN)

Lupus nephritis (LN) is the most frequent serious manifestation of patients with systemic lupus erythematosus (SLE). Up to 60% of SLE patients develop LN, which has a significant impact on their quality of life and prognosis. Recent advances have improved the diagnostic approach to LN, and new drugs that block specific pathways and kidney damage progression have been developed. Several randomized and well-powered clinical trials have confirmed the efficacy of these agents in terms of proteinuria remission and preservation of kidney function in the medium and long term, with an acceptable safety profile and good tolerance. The combination of different therapies allows for reduction of the dose and duration of corticosteroids and other potentially toxic therapies and leads to an increase in the number of patients achieving complete remission of the disease. This consensus document carried out by the Spanish Group for the Study of Glomerular Diseases (GLOSEN) provides practical and updated recommendations, based on the best available evidence and clinical expertise of participating nephrologists.

KDOQI US Commentary on the 2021 KDIGO Clinical Practice Guideline for the Management of Glomerular Diseases

The KDIGO 2021 Clinical Practice Guideline for the Management of Glomerular Diseases represents the first update to this set of recommendations since the initial set of KDIGO guideline recommendations was published in 2012. The pace of growth in our molecular understanding of glomerular disease has quickened and a number of newer immunosuppressive and targeted therapies have been introduced since the original set of guideline recommendations, making such an update necessary. Despite these updates, many areas of controversy remain. In addition, further updates since the publication of KDIGO 2021 have occurred which this guideline does not encompass. With this commentary, the KDOQI work group has generated a chapter-by-chapter companion opinion article that provides commentary specific to the implementation of the KDIGO 2021 guideline in the United States.

Predicting kidney outcomes among Latin American patients with lupus nephritis: The prognostic value of interstitial fibrosis and tubular atrophy and tubulointerstitial inflammation

OBJECTIVE

To assess the effect of tubulointerstitial inflammation (TII) and interstitial fibrosis and tubular atrophy (IFTA) on kidney survival in lupus nephritis (LN).

METHODS

Two hundred eighty five patients with biopsy-proven LN were retrospectively studied. Kidney survival was defined as the time from initial biopsy to end-stage kidney disease (ESKD), dialysis, or transplant. Kidney survival analysis was performed by the Kaplan-Meier method and the statistical difference between survival curves compared by the log-rank test. Cumulative incidence functions with competing risk of death for kidney survival were also graphed. Multivariable Cox proportional hazards regression and competing-risk analyses were performed to identify independent predictors of ESKD.

RESULTS

Fifty-seven patients (20%) progressed to ESKD during a median time of 4.2 (2.0-55.2) months after biopsy. TII was present in 206 (72.3%) biopsies, while IFTA in 99 (34.7%) biopsies. Patients with moderate-to-severe IFTA had worse kidney survival than those with none or mild IFTA in both the Kaplan-Meier (p = 0.018) and the competing-risk analyses (p = 0.017). Patients with class IV ± V LN had worse kidney survival than those with non-class IV LN by the Kaplan-Meier method (p = 0.050), but not in the competing-risk analysis (p = 0.154). Worse kidney survival was also found among those with fibrous crescents than those without, in both the Kaplan-Meier (p = 0.010) and the competing-risk (p = 0.011) analyses. By multivariable Cox regression analysis, older age (HR 1.04, 95% CI 1.01-1.07) and class IV ± V LN (HR 5.06, 95% CI 1.82-14.09) were associated with higher risk of ESKD after adjusting for sex, ethnicity, TII, and IFTA. By competing-risk analyses, class IV ± V LN (SHR 3.32, 95% CI 1.25-8.83) and no response to immunosuppressive therapy (SHR 4.55, 95% CI 1.54-13.41) were associated with a higher risk of ESKD, while eGFR >90 mL/min/1.73 m² (SHR 0.98 for each ml/min/1.73 m², 95% 0.97-0.99) with a lower risk.

CONCLUSIONS

Patients with moderate-to-severe IFTA had worse kidney survival than those with none or mild IFTA. Worse kidney survival was also found among those with class IV LN and fibrous crescents versus those without IV LN and fibrous crescents, respectively.

Consensus document of the Spanish Group for the Study of the Glomerular Diseases (GLOSEN) for the diagnosis and treatment of lupus nephritis

A significant number of patients with systemic lupus erythematosus (between 20% and 60% according to different reported series) develop lupus nephritis in the course of its evolution, which directly influences their quality of life and vital prognosis. In recent years, the greater knowledge about the pathogenesis of systemic lupus and lupus nephritis has allowed relevant advances in the diagnostic approach and treatment of these patients, achieving the development of drugs specifically aimed at blocking key pathogenic pathways of the disease. Encouragingly, these immunomodulatory agents have shown in well-powered, randomized clinical trials good clinical efficacy in the medium-term, defined as proteinuria remission and preservation of kidney function, with an acceptable safety profile and good patient tolerability. All this has made it possible to reduce the use of corticosteroids and other potentially more toxic therapies, as well as to increase the use of combined therapies. The present consensus document carried out by the Glomerular Diseases Working Group of the Spanish Society of Nephrology (GLOSEN), collects in a practical and summarized, but rigorous way, the best currently available evidence about the diagnosis, treatment, and follow-up of lupus nephritis patients, including cases of special situations, with the main objective of providing updated information and well-founded clinical recommendations to treating physicians, to improve the diagnostic and therapeutic approach to our patients.

Urinary galectin-3 binding protein (G3BP) as a biomarker for disease activity and renal pathology characteristics in lupus nephritis

Objective

There is an urgent need to identify novel biomarkers of LN to reflect renal histological changes. This study aims to investigate urinary G3BP levels in LN patients and their association with renal disease activity both clinically and pathologically.

Methods

This is a cross-sectional study. A total of 119 lupus nephritis patients were recruited. Thirty patients with chronic kidney diseases (CKD) and 27 healthy volunteers were also recruited as controls. Urinary G3BP was tested by ELISA. Renal histopathology was reviewed by an experienced renal pathologist. Other clinical variables were collected through chart review.

Results

The levels of uG3BP were significantly increased in active LN patients compared to those in inactive LN (p<0.001), CKD patients (p=0.01), and healthy controls (p<0.001). ROC analysis indicated a good discrimination ability of uG3BP to differentiate active LN from CKD patients (AUC=0.7), inactive LN (AUC=0.76), or healthy controls (AUC=0.87). uG3BP was positively correlated with SLEDAI (ρ=0.352, p<0.001), rSLEDAI (ρ=0.302, p<0.001), and SLICC RAS (ρ=0.465, p<0.001), indicating a role as a biomarker of disease activity. It also correlated with clinical parameters, including 24-h urine protein, ESR, and serum C3 levels. In patients with 24-h urine protein > 3.0 g/24h, uG3BP levels were higher in proliferative LN than in membranous LN (p=0.04). They could discriminate the two pathogenic types of LN (AUC=0.72), and they also positively correlated with AI (ρ=0.389, p=0.008) and scores of hyaline deposits (ρ=0.418, p=0.006). While in patients with 24-h urine protein ≤ 3.0 g/24h, uG3BP levels were not significantly different between proliferative and membranous LN, and there was no apparent relationship between uG3BP levels with AI or with scores of hyaline deposits, but they correlated positively with scores of cellular/fibrocellular crescents (ρ=0.328, p=0.04).

Conclusion

uG3BP is a non-invasive biomarker for clinically and histologically reflecting disease activity. It is associated with active histological changes and can be used as a surrogate biomarker when the renal biopsy is impractical.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02763-4.

Prediction models of treatment response in lupus nephritis

In order to develop prediction models of one-year treatment response in lupus nephritis, an approach using machine learning to combine traditional clinical data and novel urine biomarkers was undertaken. Contemporary lupus nephritis biomarkers were identified through an unbiased PubMed search. Thirteen novel urine proteins contributed to the top 50% of ranked biomarkers and were selected for measurement at the time of lupus nephritis flare. These novel markers along with traditional clinical data were incorporated into a variety of machine learning algorithms to develop prediction models of one-year proteinuria and estimated glomerular filtration rate (eGFR). Models were trained on 246 individuals from four different sub-cohorts and validated on an independent cohort of 30 patients with lupus nephritis. Seven models were considered for each outcome. Three-quarters of these models demonstrated good predictive value with areas under the receiver operating characteristic curve over 0.7. Overall, prediction performance was the best for models of eGFR response to treatment. Furthermore, the best performing models contained both traditional clinical data and novel urine biomarkers, including cytokines, chemokines, and markers of kidney damage. Thus, our study provides further evidence that a machine learning approach can predict lupus nephritis outcomes at one year using a set of traditional and novel biomarkers. However, further validation of the utility of machine learning as a clinical decision aid to improve outcomes will be necessary before it can be routinely used in clinical practice to guide therapy.

The lupus nephritis management renaissance

Over the past year, and for the first time ever, the US Food and Drug Administration approved 2 drugs specifically for the treatment of lupus nephritis (LN). As the lupus community works toward understanding how to best use these new therapies, it is also an ideal time to begin to rethink the overall management strategy of LN. In addition to new drugs, this must include how to use kidney biopsies for management and not just diagnosis, how molecular technologies can be applied to interrogate biopsies and how such data can impact management, and how to incorporate LN biomarkers into management paradigms. Herein, we will review new developments in these areas of LN and put them into perspective for disease management now and in the future.

Collagen Type III and VI Remodeling Biomarkers Are Associated with Kidney Fibrosis in Lupus Nephritis

Background

Lupus nephritis (LN) occurs in <40% of patients with SLE. Reliable biomarkers of kidney damage are needed to identify patients with SLE at risk of developing LN to improve screening, treat the disease earlier, and halt progression to kidney failure. Novel biomarkers of extracellular matrix remodeling were evaluated as markers of kidney fibrosis and disease activity in patients with LN.

Methods

Biomarkers of the interstitial collagen type III (PRO-C3) and type VI (PRO-C6) formation and of collagen type III (C3M) degradation were evaluated in the serum and urine of 40 patients with LN, 20 patients with SLE but without LN, 20 healthy controls, and ten biopsy controls (histologic kidney inflammation/damage without SLE). Their association with histologic markers of interstitial fibrosis and tubular atrophy, with inflammatory cell infiltration and with disease activity and chronicity in the patients with LN was assessed.

Results

Despite PRO-C3 (serum) and PRO-C6 (serum and urine) being significantly elevated in patients with LN compared with healthy controls, the markers did not differentiate patients with LN from those with SLE. C3M (urine) levels were not different in LN compared with the other groups. C3M (urine) strongly correlated and PRO-C6 (serum and urine) inversely correlated with kidney function (eGFR). The biomarkers of interstitial collagen turnover PRO-C6 (serum) and C3M (urine) correlated with histologic markers of interstitial fibrosis, tubular atrophy, and monocyte infiltration.

Conclusions

Noninvasive collagen turnover biomarkers are promising tools to identify patients with SLE with kidney histologic modifications.

Lupus Membranous Nephropathy

Background

Lupus membranous nephropathy (LMN) is a rare disease, usually associated with nephrotic syndrome.

Methods

We reviewed the literature by searching for the following terms on Pubmed.gov: lupus nephritis, membranous nephropathy (MN), lupus membranous nephropathy, nephrotic syndrome, and Class V lupus nephritis.

Results

The histology of LMN at light microscopy is similar to that of primary MN. Cases of MN associated with focal or diffuse proliferation are not considered LMN by the International Society of Nephrology/Renal Pathology Society classification. Immunofluorescence study of LMN shows deposits of all immunoglobulins and complement. Tubulo-reticular structures, extraglomerular deposits, subepithelial, and scanty subendothelial deposits can be seen on electron microscopy. Phospholipase A2 receptor deposits are usually but not necessarily absent in LMN. The pathogenesis is still not completely understood. The inflammatory milieu of lupus may favor the development of autoantigens and intraglomerular assembly of immune complexes. These are more often associated with mesangial or endocapillary hypercellular lesions. Alternatively, autoantibodies may bind autoantigens in the glomerular subepithelium, triggering a signaling cascade leading to LMN. A central role in the development of podocyte injury and proteinuria is played by the components of complement C5b-C9. CKD progression in LMN is slow but may be accelerated by the frequency of renal flares. Persistent nephrotic syndrome and/or the frequent use of corticosteroids may lead to a series of life-threatening complications.

Discussion

Treatment of arterial hypertension, dyslipidemia, and diabetes are of paramount importance. Besides specific therapies of these complications, hydroxychloroquine and vitamin D supplementation are recommended. Immunosuppression should be limited to patients with nephrotic proteinuria. The most frequently used drugs are corticosteroids, calcineurin inhibitors, cyclophosphamide, mycophenolate, and rituximab, alone or combined. Early detection and treatment of renal flares is of paramount importance to prevent CKD progression.

Correlations of serum beta 2-microglobulin level with disease activity and renal involvement in patients with systemic lupus erythematosus

Objectives

To determine correlations of serum beta 2-microglobulin (β2-MG) level with disease activity and renal involvement in patients with systemic lupus erythematosus (SLE).

Methods

Two hundred eligible SLE patients were assigned into remission and active stage groups according to SLE disease activity index (SLEDAI) scores. They were also assigned into kidney damage and no kidney damage groups. Serum β2-MG, Scr, ALB, BUN, anti-dsDNA, complements C3, C4 and 24-h urinary total protein (UTP) were detected. Estimated glomerular filtration rate (eGFR) was calculated. Correlations of β2-MG level with SLEDAI score and eGFR were subjected to Spearman analysis. Affecting factors were explored by logistic multivariate regression analysis, and predictive values of β2-MG level for SLE, disease activity and renal damage were assessed by ROC curves.

Results

β2-MG, Scr, ALB, C3, C4, anti-dsDNA and UTP levels, eGFR and SLEDAI score were different between patients with different disease activities, and, except for eGFR, also between patients with different renal damage degrees (p<0.05). Serum β2-MG, Scr, ALB, C3, C4, anti-dsDNA, UTP, eGFR and SLEDAI score were independent factors for disease activity (p<0.05), and β2-MG, ALB, C3, UTP, eGFR and SLEDAI score were factors affecting renal damage (p<0.05). β2-MG level was correlated positively with SLEDAI score (r=0.877, p=0.000) and negatively with eGFR (r=−0.873, p=0.000). This level was highly valuable for predicting SLE, disease activity and renal damage.

Conclusions

Serum β2-MG levels in SLE patients are correlated positively with disease activity and negatively with renal involvement, being highly sensitive and specific for predicting SLE, disease activity and eGFR.

Secondary Membranous Nephropathy. A Narrative Review

Membranous nephropathy (MN) is a common cause of proteinuria and nephrotic syndrome all over the world. It can be subdivided into primary and secondary forms. Primary form is an autoimmune disease clinically characterized by nephrotic syndrome and slow progression. It accounts for ~70% cases of MN. In the remaining cases MN may be secondary to well-defined causes, including infections, drugs, cancer, or autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), urticarial vasculitis, sarcoidosis, thyroiditis, Sjogren syndrome, systemic sclerosis, or ankylosing spondylitis. The clinical presentation is similar in primary and secondary MN. However, the outcome may be different, being often related to that of the original disease in secondary MN. Also, the treatment may be different, being targeted to the etiologic cause in secondary MN. Thus, the differential diagnosis between primary and secondary MN is critical and should be based not only on history and clinical features of the patient but also on immunofluorescence and electron microscopy analysis of renal biopsy as well as on the research of circulating antibodies. The identification of the pathologic events underlying a secondary MN is of paramount importance, since the eradication of the etiologic factors may be followed by remission or definitive cure of MN. In this review we report the main diseases and drugs responsible of secondary MN, the outcome and the pathogenesis of renal disease in different settings and the possible treatments.

Update on Lupus Nephritis: Looking for a New Vision

Lupus nephritis (LN) is one of the most common manifestations of systemic lupus erythematosus (SLE), affecting approximately 40% of patients with lupus. It represents a major risk factor for morbidity and mortality, and 10% of patients with LN will develop end-stage kidney disease (ESKD). Therefore, there are a number of areas for improvement in the field of LN such as the search for new clinical biomarkers with a more accurate correlation with lupus activity and the redefinition of the histological classification into different subgroups in order to guide a personalized treatment. Although the role of protocol repeat kidney biopsies in LN is controversial, recent publications suggest that repeat histological assessment can be useful in guiding therapeutic decisions that may yield toward precision medicine. In the last decade, LN therapy has remained largely unchanged, with a probability of achieving complete or partial remission not exceeding 60-70%. Thus, optimization of old treatment strategies and search for new agents are urgently needed in order to improve outcomes such as mortality or development of ESKD. Future trials should focus in addressing unanswered issues such as the appropriate dose and duration of immunosuppressive treatment, timing of steroid withdrawal, and drug toxicity. In addition, data are still lacking regarding pregnancy and kidney transplantation in LN and knowledge about these important areas is essential for the management of a subset of patients with SLE. In summary, several major gaps are still present in the therapeutic approach and follow-up of patients with LN. The development of new clinical trial designs will be crucial in the search to improve long-term outcomes.

What is the value of repeat kidney biopsies in patients with lupus nephritis?

INTRODUCTION

Recent studies with protocol biopsies have shown a mismatch between clinical and histological remission in lupus nephritis (LN). We aimed to evaluate histological changes in repeat kidney biopsies by clinical indication in patients with LN.

METHODS

We analyzed 107 patients with LN in which a kidney biopsy was performed between 2008 and 2018. Of those, we included 26 (24.2%) who had ≥2 kidney biopsies. Classification was done according to the International Society of Nephrology/Renal Pathology Society.

RESULTS

Mean time between biopsies was 71.5 ± 10.7 months. 73.1% of patients presented a change of class at repeat biopsy; 38.4% to a higher class and 34.6% to a lower class. A significant increase in glomerulosclerosis (% GS) (3.8% vs 18.7%, p = 0.006), interstitial fibrosis (3.8% vs 26.9%, p = 0.021), tubular atrophy (15.4% vs 57.7%, p = 0.001) and chronicity index (CI) (1 vs 3, p < 0.001) was observed at repeat biopsy. Subjects who developed chronic kidney disease progression had a lower rate of complete remission at 12 months (0% vs 37.5%, p = 0.02), higher % GS at first biopsy (7.9% vs 1.2%, p = 0.02) and higher CI (4 vs 2, p = 0.006), tubular atrophy (90% vs 37.6%, p = 0.008), interstitial fibrosis (50% vs 12.5%, p = 0.036) and vascular lesions (60% vs 18.8%, p = 0.031) at second biopsy.

CONCLUSIONS

Our major finding was that patients with LN showed a significant increase in % GS, interstitial fibrosis, tubular atrophy and vascular lesions in repeat biopsies performed by clinical indication. This suggest that a second kidney biopsy may provide valuable and useful information regarding kidney disease progression.