Clinical and Histopathologic Characteristics Associated with Renal Outcomes in Lupus Nephritis

Animal models of lupus nephritis: the past, present and a future outlook

Lupus nephritis (LN) is the most severe end-organ pathology in Systemic Lupus Erythematosus (SLE). Research has enhanced our understanding of immune effectors and inflammatory pathways in LN. However, even with the best available therapy, the rate of complete remission for proliferative LN remains below 50%. A deeper understanding of the resistance or susceptibility of renal cells to injury during the progression of SLE is critical for identifying new targets and developing effective long-term therapies. The complex and heterogeneous nature of LN, combined with the limitations of clinical research, make it challenging to investigate the aetiology of this disease directly in patients. Hence, multiple murine models resembling SLE-driven nephritis are utilised to dissect LN's cellular and genetic mechanisms, identify therapeutic targets, and screen novel compounds. This review discusses commonly used spontaneous and inducible mouse models that have provided insights into pathogenic mechanisms and long-term maintenance therapies in LN.

Unraveling the proteomic landscape of fibrosis in lupus nephritis through CI-based analysis

INTRODUCTION

The underlying mechanism by which lupus nephritis (LN) progresses to chronic kidney disease remains elusive. Fibrosis is a hallmark feature of chronic kidney disease, including LN. The chronicity index (CI) score, which incorporates glomerular sclerosis, fibrous crescents, tubular atrophy, and interstitial fibrosis, summarizes the extent of kidney tissue fibrosis.

METHOD

In this study, we employed label-free quantitative proteomics based on mass spectrometry to generate kidney protein profiles with varying CI scores.

RESULTS

A total of 98 proteins exhibiting linear correlation with CI scores were initially screened out by linear model (CI linearly related proteins), and subsequently, 12 key proteins were derived based on the CI linearly related proteins using Cytohubba. LN patients were stratified into two subtypes based on CI scores and epithelial-mesenchymal transition (EMT) characteristics. These subtypes exhibited significant disparities in immune infiltration and molecular pathways. The high EMT group exhibited heightened activation of immune cells, such as memory B cells, gamma delta T cells, and resting mast cells. Gene Set Enrichment Analysis (GSEA) uncovered substantial dysregulation in critical biological processes and signaling pathways, including NF-κB, JNK, PI3K/AKT/mTOR signaling pathway, lipoprotein biosynthetic process, and endocytosis, in both subgroups.

CONCLUSION

In conclusion, this study establishes molecular subgroups based on the CI score, providing novel insights into the molecular mechanisms governing chronicity in the kidneys of diverse LN patients. Key Points • Fibrosis is a fundamental and characteristic pathological process underlying the NIH-CI in LN. • Different EMT status presented variant clinical characteristics, immune features in LN.

Sex differences in mortality among patients with lupus nephritis

OBJECTIVE

To evaluate the prognostic importance of sex in lupus nephritis (LN).

METHODS

A retrospective cohort of 1048 biopsy-confirmed LN patients, diagnosed between January 1, 1996, and December 31, 2018, was analyzed. Demographics, clinical characteristics, laboratory findings, and renal pathology were assessed. The primary outcome was mortality, and the secondary outcomes included doubling of serum creatinine and end-stage renal disease (ESRD). Sex-associated risks were evaluated using Cox regression models.

RESULTS

Among the1048 patients, 178 (17%) were male and 870 (83%) were female. Male patients exhibited more aggressive features: higher blood pressure, earlier disease onset, and elevated levels of serum creatinine (Scr), uric acid, blood urea nitrogen. Intriguingly, male patients also displayed more severe histopathological alterations, such as more total crescents, cellular crescents formations, higher level of glomerular leukocyte infiltration and Activity Index (AI), even when overall renal pathology was comparable between sexes. During a median follow-up of 112 months, mortality was registered in 141 patients (15.3%). Mortality rates were conspicuously higher in males (24.2% males vs. 13.4% females, p = 0.0029). Secondary outcomes did not show significant sex differences. Cox regression analysis highlighted male, age of renal biopsy, eGFR, and Chronicity Index (CI) as independent risk factors for survival in LN patients. Notably, infections emerged as the leading cause of mortality among LN patients, with a significant higher rate in male patients.

CONCLUSION

In our cohort with LN, there was a higher rate of all-cause mortality and proportion of infection-related death in male. Recognizing and further exploring these sex disparities is crucial for optimized LN patients care.

The anti-mCRP199-206 antibodies aggravate tubulointerstitial lesions in lupus nephritis

Tubulointerstitial lesions could also be prominent in lupus nephritis, and the pathogenesis of tubulointerstitial lesions may be different from glomerular lesions. Previous studies have showed that plasma antibodies against modified /monomeric C-reactive protein (mCRP) are associated with renal tubulointerstitial lesions in patients with lupus nephritis, and amino acid (aa) 199-206 was one of the major epitopes of mCRP. However, the role of anti-mCRP199-206 antibodies in the pathogenesis of tubulointerstitial lesions in lupus nephritis is unknown. A total of 95 patients with renal biopsy-proven lupus nephritis were enrolled in this study. Plasma levels of anti-mCRP199-206 antibodies were screened by enzyme-linked immunosorbent assay (ELISA). A lupus prone mouse model was immunized using peptides mCRP199-206 to explore the potential role of anti-mCRP199-206 antibodies in tubulointerstitial lesions. The mechanism of anti-mCRP199-206 antibodies damage to renal tubular epithelial cells was investigated in vitro. Plasma antibodies against mCRP199-206 were associated with renal tubulointerstitial lesions and prognosis in patients with lupus nephritis. Immunization with peptides mCRP199-206 in lupus prone mice could aggravate tubulointerstitial lesions and drive tubulointerstitial inflammation and fibrosis. Anti-mCRP 199-206 antibodies could activate the TGF-β1/Smad3 signal pathway and induce tubular damage by binding with CRP. Circulating antibodies against mCRP199-206 could be a biomarker to reveal tubulointerstitial lesion, and participate in the pathogenesis of tubulointerstitial lesions, which might provide a potential therapeutic target for lupus nephritis.

Interstitial fibrosis increases the risk of end-stage kidney disease in patients with lupus nephritis

OBJECTIVE

To evaluate the risk of end-stage kidney disease (ESKD) in LN patients using tubulointerstitial lesion scores.

METHODS

Clinical profiles and histopathological presentations of 151 biopsy-proven LN patients were retrospectively examined. Risk factors of ESKD based on characteristics and scoring of their tubulointerstitial lesions [e.g. interstitial inflammation (II), tubular atrophy (TA) and interstitial fibrosis (IF)] were analysed.

RESULTS

The mean age of 151 LN patients was 36 years old, and 136 (90.1%) were female. The LN cases examined included: class I/II (n = 3, 2%), class III/IV (n = 119, 78.8%), class V (n = 23, 15.2%) and class VI (n = 6, 4.0%). The mean serum creatinine level was 1.4 mg/dl. Tubulointerstitial lesions were recorded in 120 (79.5%) patients. Prior to receiving renal biopsy, nine (6.0%) patients developed ESKD. During the follow-up period (mean, 58 months), an additional 47 patients (31.1%) progressed to ESKD. Multivariate analyses identified serum creatinine [hazard ratio (HR): 1.7, 95% CI: 1.42-2.03, P < 0.001] and IF (HR: 3.2, 95% CI: 1.58-6.49, P = 0.001) as independent risk factors of ESKD. Kaplan-Meier analysis further confirmed a heightened risk of ESKD associated with IF.

CONCLUSION

Tubulointerstitial involvement is commonly observed in the histopathological presentation of LN. However, IF, rather than II or TA, was found to increase the risk of ESKD in our cohort. Therefore, to predict renal outcome in LN patients prior to adjusting immunosuppressive treatment, the degree of IF should be reviewed.

Prognostic factors and validation of the histologic chronicity score for C3 glomerulopathy: a registry analysis

Background

Data on the prognostic factors for C3 glomerulopathy (C3G) are limited, and validation of the new C3G histologic index (C3G-HI) in different settings is still needed. We aimed to evaluate the chronicity score of C3G-HI and probable prognostic factors in our population.

Methods

In this registry study, 74 patients from 20 centers with adequate follow-up data were included. Total chronicity score (TCS) was calculated according to percentages of glomerulosclerosis, interstitial fibrosis, tubular atrophy, and presence of arterio- and arteriolosclerosis. Primary composite outcome was defined as doubling of serum creatinine from baseline, undergoing dialysis or transplantation, development of stage 5 chronic kidney disease, or death.

Results

Median age was 34 [interquartile range (IQR) 24-46] years, and 39 patients (52.7%) were male. Median follow-up duration was 36 (IQR 12-60) months, and median TCS was 3 (IQR 1-5). Overall, 19 patients (25.7%) experienced primary composite outcome. Multivariate Cox regression model showed that only hemoglobin [adjusted HR (aHR) 0.67, 95% confidence interval 0.46-0.97, P = .035] predicted primary composite outcome, and TCS fell short of the statistical significance (aHR 1.26, 0.97-1.64, P = .08). Receiver operating characteristic analysis demonstrated that TCS showed an area under the curve value of 0.68 (0.56-0.78, P = .028) in discriminating primary composite outcome at 3 years, and 3-year kidney survival was lower in patients with TCS ≥4 (72.4%) compared with TCS <4 (91.1%) in Kaplan-Meier analysis (P = .036).

Conclusions

Low hemoglobin levels predicted dismal outcomes in patients with C3G. TCS ≥4 was associated with a worse 3-year kidney survival, which validated the 3-year prognostic value of the TCS of C3G-HI in our population.

Early-onset lupus nephritis

Early-onset systemic lupus erythematous (SLE) is a distinct clinical entity characterized by the onset of disease manifestations during childhood. Despite some similarities to patients who are diagnosed during adulthood, early-onset SLE typically displays a greater disease severity, with aggressive multiorgan involvement, lower responsiveness to classical therapies, and more frequent flares. Lupus nephritis is one of the most severe complications of SLE and represents a major risk factor for long-term morbidity and mortality, especially in children. This review focuses on the clinical and histological aspects of early-onset lupus nephritis, aiming at highlighting relevant differences with adult patients, emphasizing long-term outcomes and discussing the management of long-term complications. We also discuss monogenic lupus, a spectrum of conditions caused by single gene variants affecting the complement cascade, extracellular and intracellular nucleic acid sensing and processing, and occasionally other metabolic pathways. These monogenic forms typically develop early in life and often have clinical manifestations that resemble sporadic SLE, whereas their response to standard treatments is poor.

Functional consequence of Iron dyshomeostasis and ferroptosis in systemic lupus erythematosus and lupus nephritis

Systemic lupus erythematosus (SLE) and its renal manifestation Lupus nephritis (LN) are characterized by a dysregulated immune system, autoantibodies, and injury to the renal parenchyma. Iron accumulation and ferroptosis in the immune effectors and renal tubules are recently identified pathological features in SLE and LN. Ferroptosis is an iron dependent non-apoptotic form of regulated cell death and ferroptosis inhibitors have improved disease outcomes in murine models of SLE, identifying it as a novel druggable target. In this review, we discuss novel mechanisms by which iron accumulation and ferroptosis perpetuate immune cell mediated pathology in SLE/LN. We highlight intra-renal dysregulation of iron metabolism and ferroptosis as an underlying pathogenic mechanism of renal tubular injury. The basic concepts of iron biology and ferroptosis are also discussed to expose the links between iron, cell metabolism and ferroptosis, that identify intracellular pro-ferroptotic enzymes and their protein conjugates as potential targets to improve SLE/LN outcomes.

Granulin in renal tubular epithelia is associated with interstitial inflammation and activates the TLR9-IFN-α pathway in lupus nephritis

OBJECTIVE

This study aimed to investigate the possible role of granulin (GRN) in activating the TLR9-IFN-α pathway in renal tubular epithelial cells (RTECs) and explore clues that RTECs regulate the micro-environment of inflammatory response in lupus nephritis (LN).

METHODS

Renal sections from 57 LN patients and 30 non-LN patients were sampled for histological study, and GRN overexpression RTECs were applied for cytological study.

RESULTS

In the histological study, GRN is highly expressed in LN RTECs with tubulointerstitial inflammation (TII) and well co-localized with TLR9. ROC analysis suggested a potential relationship between GRN expression in RTECs and therapeutic response. Moreover, IFN-α also highly expressed in LN RTECs with TII, and the intensity of IFN-α is positively correlated with the co-localization intensity of GRN and TLR9. In the cytological study, LN serum, especially serum from LN with TII, activates the expression of TLR9 in RTECs, and GRN engages the interaction of TLR9 to activate the expression of IFN-α in RTECs. While TLR9 inhibitors can suppress the expression of IFN-α in RTECs, the degree of inhibition is dose-dependent.

CONCLUSION

The expression of GRN in RTECs is associated with interstitial inflammation and therapeutic response. GRN may mediate the activation of the TLR9-IFN-α pathway in RTECs and involve in the micro-environment of inflammatory response in LN.

High- and low-dose cyclophosphamide in Egyptian lupus nephritis patients: a multicenter retrospective analysis

BACKGROUND

Lupus nephritis (LN) is a common serious presentation of systemic lupus erythematosus. Cyclophosphamide (CYC) and mycophenolate mofetil (MMF) are listed as the first-line drugs in induction therapy for LN.

OBJECTIVE

This study aimed to compare high- and low-dose CYC in a cohort of Egyptian LN patients.

PATIENTS AND METHODS

The data of 547 patients with class III/IV active LN who received CYC as induction therapy were retrospectively analyzed. Whereas 399 patients received 6‑monthly 0.5-1 g/m2 CYC doses, 148 patients received six biweekly 500 mg CYC doses. Demographic data, laboratory test results, and disease activity index were recorded and compared at presentation and at 6, 12, 18, 24, and 48 months of follow-up.

RESULTS

After 48 months, the proportion of patients maintaining normal creatinine levels was higher in the group receiving induction therapy with high-dose CYC (67.9%, 60.4%, p = 0.029), and these patients also had higher proteinuria remission at 36 (26.6%, 14.8%, p = 0.014) and 48 months (24.3%, 12.8%, p = 0.006). Comparison of patient outcomes according to both induction and maintenance therapy showed the best results in patients who received high-dose CYC and continued MMF as maintenance therapy.

CONCLUSION

High- and low-dose CYC are comparable in early phases of treatment. However, after a longer duration of follow-up, high-dose CYC was associated with higher remission rates in the current cohort.

Systemic lupus erythematosus complicated with Fanconi syndrome: a case report and literature review

Background

Systemic lupus erythematosus is an autoimmune disease with diverse clinical manifestations. The symptoms of SLE in children are more atypical than adults. Childhood SLE complicated with Fanconi syndrome is extremely rare and even more difficult to diagnose.

Case presentation

This article reports a preschool boy with SLE who presented with renal tubular acidosis, accompanied by weakness in both lower limbs, delayed growth, and malnutrition. It was later found that the patient had the complication of Fanconi syndrome with renal tubular acidosis. Ultimately, renal biopsy confirmed lupus nephritis. The patient was treated with corticosteroid combined with mycophenolate mofetil, hydroxychloroquine, and belimumab. The symptoms of the child were relieved.

Conclusion

Here we report an extremely rare case of childhood SLE complicated with Fanconi syndrome. There has been no similar clinical report. It is necessary to be alert to the possibility of atypical SLE in children to avoid missed diagnosis and misdiagnosis.

International cohort of 382 children with lupus nephritis - presentation, treatment and outcome at 24 months

BACKGROUND

Children with lupus have a higher chance of nephritis and worse kidney outcome than adult patients.

METHODS

We retrospectively analyzed clinical presentation, treatment and 24-month kidney outcome in a cohort of 382 patients (≤ 18 years old) with lupus nephritis (LN) class ≥ III diagnosed and treated in the last 10 years in 23 international centers.

RESULTS

The mean age at onset was 11 years 9 months and 72.8% were females. Fifty-seven percent and 34% achieved complete and partial remission at 24-month follow-up, respectively. Patients with LN class III achieved complete remission more often than those with classes IV or V (mixed and pure). Only 89 of 351 patients maintained stable complete kidney remission from the 6th to 24th months of follow-up. eGFR ≥ 90 ml/min/1.73 m2 at diagnosis and biopsy class III were predictive of stable kidney remission. The youngest and the oldest age quartiles (2y-9y, 5m) (14y, 2m-18y,2m) showed lower rates of stable remission (17% and 20.7%, respectively) compared to the two other age groups (29.9% and 33.7%), while there was no difference in gender. No difference in achieving stable remission was found between children who received mycophenolate or cyclophosphamide as induction treatment.

CONCLUSION

Our data show that the rate of complete remission in patients with LN is still not high enough. Severe kidney involvement at diagnosis was the most important risk factor for not achieving stable remission while different induction treatments did not impact outcome. Randomized treatment trials involving children and adolescents with LN are needed to improve outcome for these children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Clinicopathologic characteristics and outcomes of late onset lupus nephritis: a single centre experience

Systemic Lupus Erythematosus (SLE) occurs in the reproductive age group. Renal involvement occurs less frequently in late-onset SLE than in reproductive-age SLE patients. Here, we aimed to study the clinical, serological and histopathological characteristics of late-onset lupus nephritis (LN). Late-onset LN was defined as disease onset after 47 years of age, corresponding to the average menopausal age. Records of biopsy proven late-onset lupus nephritis patients diagnosed between June 2000 and June 2020 were reviewed. Late-onset LN constituted 53 of 4420 patients (1.2%) biopsied during the study period. Females represented 90.65% of the cohort. Mean age of the cohort was 49.5 ± 7.05 years at the time of SLE diagnosis while its renal presentation was delayed by median duration of 10 months (IQR 3-48 months). Renal failure was present in 28 patients (52.8%) with acute kidney injury (AKI) (28.3%, n = 15) as the most common presentation. On histopathological analysis, class IV was observed in 23 patients (43.5%), crescents were observed in one-third cases and lupus vasculopathy in 4 patients (7.5%). All patients received steroids. Majority of patients (43.3%; n = 23) received Euro lupus protocol for induction. On median follow up duration of 82 months, renal flares were noted in 9 patients (17%) and 8 patients (15.1%) became dialysis dependent. Among 11 patients (21%) with infectious complications, 7 patients (13.2%) suffered from tuberculosis. Infections caused three-fourth of the deaths. Late-onset lupus nephritis is rare and presents as renal failure in majority. Renal biopsy affects the clinical decision of judicious use of immunosuppression which is imperative due to high rate of infections in this cohort.

Flares in Lupus Nephritis: Risk Factors and Strategies for Their Prevention

PURPOSE OF REVIEW

Discuss the prognostic significance of kidney flares in patients with lupus nephritis, associated risk factors, and possible preventative strategies.

RECENT FINDINGS

Recently performed clinical trials and observational cohort studies underscore the high frequency of relapses of kidney disease, following initial response, in patients with proliferative and/or membranous lupus nephritis. Analysis of hard disease outcomes such as progression to chronic kidney disease or end-stage kidney disease, coupled with histological findings from repeat kidney biopsy studies, have drawn attention to the importance of renal function preservation that should be pursued as early as lupus nephritis is diagnosed. In this respect, non-randomized and randomized evidence have suggested a number of factors associated with reduced risk of renal flares such as attaining a very low level of proteinuria (< 700-800 mg/24 h by 12 months), using mycophenolate over azathioprine, adding belimumab to standard therapy, maintaining immunosuppressive/biological treatment for at least 3 to 5 years, and using hydroxychloroquine. Other factors that warrant further clarification include serological activity and the use of repeat kidney biopsy to guide the intensity and duration of treatment in selected cases. The results from ongoing innovative studies integrating kidney histological and clinical outcomes, together with an expanding spectrum of therapies in lupus nephritis, are expected to facilitate individual medical care and long-term disease and patient prognosis.

Clinicopathological Characteristics and Prognosis of Lupus Nephritis Patients with Acute Kidney Injury

INTRODUCTION

Acute kidney injury (AKI) is common in lupus nephritis (LN) and a risk factor for chronic kidney failure. Here, we aimed to assess the characteristics and prognosis of LN patients with AKI.

METHODS

AKI and AKI severity stages in LN patients were defined by the Kidney Disease Improving Global Outcomes (KDIGO) classification. Long-term renal outcomes and patient mortality between different stages of AKI were compared by Cox regression analysis.

RESULTS

Of 1272 LN patients, 225 (17.69%) had AKI and 72 (5.66%) were AKI stage 3. Compared with the non-AKI group, the proportion of male patients was significantly higher in the AKI group (p = 0.002). In addition, there were markedly higher proportions of hematologic system damage, more severe renal manifestations, and higher Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores in the AKI group than in the non-AKI group. The active and chronic lesions in renal biopsy were significantly higher in LN patients with AKI than those without AKI. During a median follow-up of 53 months, Kaplan-Meier curve showed that LN patients with AKI stage 3 had significantly poorer long-term renal outcomes (p = 0.002) and patient survival (p < 0.001) than those without AKI. Furthermore, AKI stage 3, but not stage 1 or 2 was significantly associated with adverse renal outcomes (hazard ratio [HR] = 2.52, 95% confidence interval [CI] 1.01-6.28, p = 0.048) and all-cause mortality (HR = 2.80, 95% CI: 1.18-6.61, p = 0.019) in LN patients. In patients with AKI, increased baseline serum creatinine and severe glomerular sclerosis were independent risk factors for worse renal outcomes, while higher blood pressure, increased baseline serum creatinine, and anti-Sjogren's syndrome A positivity could indicate poor survival.

DISCUSSION

LN patients with AKI stage 3, but not stages 1 and 2, have poorer long-term renal outcomes and patient survival. Our study demonstrates the importance of early identification and management of AKI in LN patients.

Renal Histopathology Associated With Kidney Failure and Mortality in Patients With Lupus Nephritis: A Long-Term Real-World Data Study

OBJECTIVE

Lupus nephritis (LN), a common manifestation of systemic lupus erythematosus, is associated with a higher risk of kidney failure and death. The renal pathology of LN helps elucidate the severity of inflammation and the extent of irreversible damage. We aimed to identify histologic variables that correlate with risks of kidney failure and mortality.

METHODS

Between 2006 and 2019, a total of 526 patients with LN were enrolled. Renal pathology was classified according to the International Society of Nephrology/Renal Pathology Society classification. Components of activity and chronicity indices were analyzed to determine which variables correlated with an increased risk of kidney failure and death, with the adjustment of potential confounders.

RESULTS

During the follow-up period (median 7.5, IQR 3.5-10.7 years), 58 patients progressed to kidney failure and 64 died. In the multivariate Cox regression analysis, tubular atrophy (hazard ratio [HR] 2.28, 95% CI 1.66-3.14) and tubulointerstitial inflammation (HR 3.13, 95% CI 1.34-7.33) predicted kidney failure. The renal outcome was even worse if tubular atrophy and tubulointerstitial inflammation coexisted (10-year kidney survival rate: 63.22%). The presence of cellular crescents was associated with an increased risk of death in male patients with LN (HR 1.91, 95% CI 1.02-3.57), whereas the presence of fibrous crescents predicted death in female patients with LN (HR 5.70, 95% CI 1.61-20.25).

CONCLUSION

Histologic variables of renal biopsy in LN could be regarded as prognostic indicators for kidney failure and mortality.

Multidisciplinary approach to lupus nephritis: Clinical pearls, pitfalls, and positioning of newly-approved agents

Lupus nephritis (LN) is a major course of morbidity and mortality in patients with systemic lupus erythematosus (SLE), best managed by a multidisciplinary group. To this end, we gathered a group of rheumatologists, nephrologists and a nephropathologist to review current evidence regarding diagnosis and management of LN. In this consensus paper, we summarize the key points from this meeting and provide practice guidelines for the management of kidney involvement in SLE, in view of emerging new data concerning novel agents approved recently. Renal biopsy is indispensable for the management of LN. Yet, important pearls and pitfalls need to be considered regarding indications and interpretation, which are summarized in informative tables. In new-onset LN, experts agreed that, although belimumab may be added from disease onset, patients with moderate to severe proliferative nephritis (defined as: NIH activity index > 5 plus ≥ 1 of the following: (i) NIH chronicity index > 2, (ii) proteinuria > 3 g/24 h, and (iii) increase in serum creatinine > 20%) may be more likely to benefit the most. In all other patients who have already started standard-of-care treatment with either mycophenolate mofetil (MMF) or cyclophosphamide (CY), belimumab could be considered in cases with an inadequate clinical response by 3 months, or in cases that experience a nephritic flare following initial response, or have an inability to reduce the dose of glucocorticoids. In all circumstances, the drug should be given as add-on therapy, that is, in combination with a standard-of-care therapy (MMF or CY). Voclosporin could be considered for up to 3 years, in combination with MMF, in patients with heavy proteinuria (well above the nephrotic range), wherein a quick reduction of protein loss in urine is desirable to avoid the complications of the nephrotic syndrome, either as part of the initial regimen, or in cases of inadequate reduction of proteinuria with MMF. In view of the potential scarring effects, long-term administration beyond the first year requires further documentation.

Association between glomerular mTORC1 activation and crescents formation in lupus nephritis patients

OBJECTIVE

This study aims to explore the association between glomerular mammalian target of rapamycin complex 1 (mTORC1) pathway activation and crescents' degree in lupus nephritis (LN) patients.

METHODS

A total of 159 biopsy-proven LN patients were enrolled in this retrospective study. The clinical and pathological data of them were collected at the time of renal biopsy. mTORC1 pathway activation was measured by immunohistochemistry, expressed by the mean optical density (MOD) of p-RPS6 (ser235/236), and multiplexed immunofluorescence. The association of mTORC1 pathway activation with clinico-pathological features especially renal crescentic lesions, and the composite outcomes in LN patients was further analyzed.

RESULTS

mTORC1 pathway activation could be detected in the crescentic lesions and was positively correlated with the percentage of crescents (r = 0.479, P < 0.001) in LN patients. Subgroup analysis showed mTORC1 pathway was more activated in patients with cellular or fibrocellular crescentic lesions (P < 0.001), but not fibrous crescentic lesions (P = 0.270). The optimal cutoff value of the MOD of p-RPS6 (ser235/236) was 0.0111299 for predicting the presence of cellular-fibrocellular crescents in >7.39% of the glomeruli by the receiver operating characteristic curve. Cox regression survival analysis showed that mTORC1 pathway activation was an independent risk factor for the worse outcome (defined by composite endpoints of death, end-stage renal disease and a decrease of >30% in eGFR from baseline).

CONCLUSION

Activation of mTORC1 pathway was closely associated with the cellular-fibrocellular crescentic lesions and could be a prognostic marker in LN patients.

Characteristics and outcomes of a Hispanic lupus nephritis cohort from Mexico

OBJECTIVES

To characterize the clinical presentation and outcomes of LN in a Hispanic cohort from Mexico.

METHODS

We studied 440 subjects with systemic lupus erythematosus and biopsy-proven LN followed for >36 months. We obtained demographic, clinical, laboratory, histopathological and treatment variables. All outcomes were analysed by survival analysis and included response to therapy, renal relapses, progression of kidney disease (decline in eGFR ≥ 30%, doubling of serum creatinine, end-stage kidney disease) and patient survival.

RESULTS

The median age of the study cohort was 29 years (IQR 23-37) and 96% were female. The median eGFR at inclusion was 81 mL/min/1.73m2 (IQR 48-118) and 24 h-uPCR was 3.4 g/g (IQR 1.9-5.6). Mixed class LN (III/IV+V) was the most frequently observed (69%). Over a median follow-up of 79 months, complete response rates were 22.3%, 40.5% and 51.6%, at 6, 12 and 24 months, respectively. Renal relapse rates were 32.3% and 50.6% at 3 and 5 years. By 3 and 5 years, 20.7% and 31.4% had decline in eGFR ≥30%, 14.4% and 22.5% doubled their serum creatinine, and 9.1% and 17.7% progressed to ESKD. The factors associated with loss of kidney function were age, eGFR at presentation, the histologic chronicity index in the kidney biopsy, and the type of response to therapy. Patient survival was 98.2% and 97.1% at 3 and 5 years.

CONCLUSION

Although the response to treatment and patient survival in this Latin American cohort is comparable to that observed in other regions, there is still a high rate of renal relapses and progression to decline in kidney function.

Kidney tubular epithelial cell ferroptosis links glomerular injury to tubulointerstitial pathology in lupus nephritis

Ferroptosis is a druggable, iron-dependent form of cell death that is characterized by lipid peroxidation but has received little attention in lupus nephritis. Kidneys of lupus nephritis patients and mice showed increased lipid peroxidation mainly in the tubular segments and an increase in Acyl-CoA synthetase long-chain family member 4, a pro-ferroptosis enzyme. Nephritic mice had an attenuated expression of SLC7A11, a cystine importer, an impaired glutathione synthesis pathway, and low expression of glutathione peroxidase 4, a ferroptosis inhibitor. Lipidomics of nephritic kidneys confirmed ferroptosis. Using nephrotoxic serum, we induced immune complex glomerulonephritis in congenic mice and demonstrate that impaired iron sequestration within the proximal tubules exacerbates ferroptosis. Lupus nephritis patient serum rendered human proximal tubular cells susceptibility to ferroptosis which was inhibited by Liproxstatin-2, a novel ferroptosis inhibitor. Collectively, our findings identify intra-renal ferroptosis as a pathological feature and contributor to tubular injury in human and murine lupus nephritis.

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.

The Role of New 3D Pathology and Lymphocyte Expression of Interstitial Inflammation in Pediatric-Onset Lupus Nephritis

Lupus nephritis (LN) is a common and severe manifestation of pediatric-onset systemic lupus erythematosus (pSLE). It is one of the major causes of long-term glucocorticoid/immune suppressants use in pSLE. It causes long-term glucocorticoid/immune suppressants use and even end-stage renal disease (ESRD) in pSLE. It is now well known that high chronicity, especially the tubulointerstitial components in the renal biopsy, predicts a poor renal outcome. Interstitial inflammation (II), a component of activity in LN pathology, can be an early predictor for the renal outcome. With the advent of 3D pathology and CD19-targeted CAR-T cell therapy in the 2020s, the present study focuses on detailed pathology and B cell expression in II. We recruited 48 pSLE patients with class III/IV LN to analyze the risk of ESRD based on different II scores. We also studied 3D renal pathology and immunofluorescence (IF) staining of CD3, 19, 20, and 138 in patients with a high II score but low chronicity. Those pSLE LN patients with II scores of 2 or 3 showed a higher risk for ESRD (p = 0.003) than those with II scores of 0 or 1. Excluding patients with chronicity >3, high II scores still carried a higher risk for ESRD (p = 0.005). Checking the average scores from the renal specimens from different depths, the II, and chronicity showed good consistency between 3D and 2D pathology (interclass correlation coefficient [ICC], II = 0.91, p = 0.0015; chronicity = 0.86, p = 0.024). However, the sum of tubular atrophy plus interstitial fibrosis showed no good consistency (ICC = 0.79, p = 0.071). The selected LN patients with negative CD19/20 IF stains showed scattered CD3 infiltration and a different IF pattern of Syndecan-1 expression. Our study provides unique data in LN, including 3D pathology and different in situ Syndecan-1 patterns in LN patients.

Role of crescents for lupus nephritis in clinical, pathological and prognosis: a single-center retrospective cohort study

BACKGROUND

Referring to the International Society of Nephrology/Renal Pathology Society (ISN/RPS) 2018 pathological classification, we aim to reveal the significance of cellular/fibrocellular crescents in lupus nephritis (LN) patients.

METHODS

Patients with LN proven by renal biopsy at the First Affiliated Hospital of Wenzhou Medical University from December 2001 to November 2017 were identified, and eligible cases were divided into two groups according to the presence or absence of cellular/fibrocellular crescents in renal biopsy tissues.

RESULTS

A total of 401 LN patients were identified from our follow-up database, and 296 eligible LN patients were enrolled in the study. Of these patients, 146 patients in the group without cellular/fibrocellular crescents (non-crescent group) and 150 patients in the group with cellular/fibrocellular crescents (Crescent group). The median follow-up time of patients was 47 months, and a total of 54 patients progressed to the composite endpoint. Crescent group had higher serum creatinine, lower serum albumin, higher systemic lupus erythematosus (SLE) disease activity index, and higher activity index of renal tissue. The interaction between cellular/fibrocellular crescents and proteinuria at baseline was associated with the prognostic risk of LN (P = 0.006). In the group with proteinuria < 3.5 g/24 h, the prognosis of crescent group was significantly worse than of non-crescent group (P < 0.001), while in the group with proteinuria ≥ 3.5 g/24 h, there was no significant relationship between crescents and prognosis (p = 0.452). By multivariable Cox hazard analysis, positive anti-dsDNA, chronic index of renal biopsy tissue, cellular/fibrocellular crescents and its interaction with 24 h proteinuria were independent risk factors for poor prognosis of LN.

CONCLUSIONS

LN patients with cellular/fibrocellular crescents had more severe and active disease features, and cellular/fibrocellular crescents is a risk factor for poor prognosis of LN. There was an interaction between cellular/fibrocellular crescents and proteinuria in predicting poor prognosis, and among patients with low levels of proteinuria at the time of renal biopsy, those with crescents had a worse long-term prognosis than those without crescents.

Circulating and renal fibrocytes are associated with interstitial fibrosis in lupus nephritis

OBJECTIVES

Fibrocytes, the extracellular matrix-producing cells derived from bone marrow progenitors, contribute to organ fibrosis. We investigated the presence and characteristics of fibrocytes in the peripheral blood and kidney of patients with lupus nephritis (LN), and the association of the abundance of fibrocytes with renal tubular epithelial cells (RTECs) in LN fibrogenesis.

METHODS

Fibrocytes were identified with type I collagen (colI), α-smooth muscle actin (α-SMA), CD34 and CD45 using flow cytometry and confocal imaging. The associations between the levels of fibrocytes and pathological features of patients with LN were analysed. The contribution of RTECs to fibrocyte generation was determined using LN sera-treated HK-2 cells.

RESULTS

Spindle-shaped fibrocytes (colI+α-SMA+CD34+CD45+ cells) were present in the peripheral blood and their abundance was especially high in LN patients with interstitial fibrosis compared with healthy control. Renal fibrocytes (colI+α-SMA+CD45+ cells) were found in the tubulointerstitium in patients with LN, and their numbers were significantly associated with the degrees of chronicity indices including interstitial fibrosis and renal dysfunction. Stimulation of peripheral blood mononuclear cells with supernatants from LN serum-treated HK-2 cells led to a significant generation of fibrocytes, which was abrogated by the addition of IL-6 neutralizing antibody.

CONCLUSION

Fibrocytes were significantly increased in the blood and kidney tissue of patients with LN, especially those with interstitial fibrosis. Fibrocytes could be differentiated from blood cells, with an active contribution from RTECs. Our results show a possible link between fibrocytes and tubulointerstitial fibrosis, which may serve as a novel therapeutic target for LN fibrogenesis.

Development of an instrument to predict proliferative histological class in lupus nephritis based on clinical and laboratory data

OBJECTIVES

To compare the correlations of histological class inferences based on clinical manifestations and laboratory tests between rheumatologists and nephrologists, to determine the associations of clinical and laboratory data with histological classes and to develop an instrument that can assist histological class identification in lupus nephritis (LN).

METHODS

Retrospective study based on medical records of 80 systemic lupus erythematosus patients (SLICC criteria classification, 2012) who underwent kidney biopsy between 2010 and 2017. Two rheumatologists and two nephrologists received clinical and laboratory data and answered questions regarding which histological class was expected on kidney biopsy. Kappa (K) coefficient was used to assess agreement between evaluators. A decision tree was constructed using the chi-square interaction detector and logistic regression was performed for the development of the proliferative histological class predictor instrument.

RESULTS

The mean age and disease duration were 33 ± 10.3 years and 11.5 ± 6.7 years, respectively. The level of agreement between the evaluators and kidney biopsy was poor (global K 0.364 ± 0.029; p < .001). Analyzing clinical and laboratory variables as predictors of proliferative histological class, patients with abnormal urinary sediment and positive anti-dsDNA antibodies presented 13.96 and 4.96 times higher risks of presenting class III or IV, respectively (p < 0.001). Our instrument has a sensitivity of 87.8% and specificity of 80%, using abnormal urinary sediment, anti-dsDNA antibodies, and serum creatinine as variables.

CONCLUSIONS

Rheumatologists and nephrologists with experience in treating LN generated evaluations that correlated weakly with kidney biopsy. When kidney biopsy is unavailable or is contraindicated for medical reasons, instruments based on clinical and laboratory predictors may be helpful.

Response to therapy at 6 months predicts long-term renal outcome in lupus nephritis with poor kidney function

OBJECTIVE

It is unclear whether aggressive treatment would benefit lupus nephritis (LN) with poor renal function, which has been excluded from most clinical trials. We aimed at demonstrating their clinicopathological features and prognosis.

METHODS

From August 2012 to December 2018, patients with active LN with poor renal function (estimated glomerular filtration rate (eGFR) between 15 and 59 mL/min/1.73 m²) receiving induction therapy were included. Complete response (CR) was defined as proteinuria <0.5 g/24 hours, while partial response (PR) was defined as ≥50% proteinuria reduction to subnephrotic levels (<3.5 g/24 hours), with (near) normal eGFR. The primary outcome was end-stage renal disease (ESRD). The significant variables were selected via the least absolute shrinkage and selection operator method to construct prediction models for ESRD and treatment response.

RESULTS

A total of 107 patients were included. At 6 months, 18.7%, 38.3% and 43.0% of patients achieved CR, PR and no response (NR), respectively. During a median follow-up of 60 months, 40.2% ended up with reduced renal function (eGFR <60 mL/min/1.73 m²) and 14.0% progressed to ESRD. The proportions of NR at 6 months were significantly higher in these patients compared with those with recovered renal function (p<0.001). In multivariable analysis, baseline eGFR ≤33 mL/min/1.73 m² (HR 3.499, 95% CI 1.044 to 11.730), fibrous crescent (HR 3.439, 95% CI 1.029 to 11.490) and NR at 6 months (HR 17.070, 95% CI 2.155 to 135.240) independently predicted ESRD (C-index 0.911, 95% CI 0.866 to 0.956). Further, baseline hypertension (HR 2.517, 95% CI 0.820 to 8.580), SLE duration>3 months (2.517, 1.012-7.226) and chronicity index (HR 1.757, 95% CI 1.371 to 2.414) predicted NR at 6 months (C-index 0.833, 95% CI 0.756 to 0.910).

CONCLUSIONS

In patients with LN with poor renal function, no response at 6 months predicts a poor long-term renal outcome.

Renal Tissue Expression of BAFF and BAFF Receptors Is Associated with Proliferative Lupus Nephritis

Background: The B-cell activating factor (BAFF) controls the maturation and survival of B cells. An imbalance in this cytokine has been associated with systemic autoimmunity in SLE and lupus nephritis (LN). However, few investigations have evaluated the tissular expression of BAFF in LN. This study aimed to associate BAFF system expression at the tissular level with the proliferative LN classes. Methods: The analysis included eighteen kidney tissues, with sixteen LN (class III = 5, class IV = 6, class III/IV+V = 4, and class V = 1), and two controls. The tissular expression was evaluated with an immunochemistry assay. A Cytation5 imaging reader and ImageJ software were used to analyze the quantitative expression. A p-value < 0.05 was considered significant. Results: The expressions of BAFF, A proliferation-inducing ligand (APRIL), and their receptors were observed in glomerular, tubular, and interstitial zones, with BAFF being the most strongly expressed in the overall analysis. BAFF-Receptor (BR3), transmembrane activator and CALM interactor (TACI), and B-Cell maturation antigen (BCMA) displayed higher expressions in LN class IV in all zones analyzed (p < 0.05). Additionally, a positive correlation was found between APRIL, TACI, and BCMA at the glomerular level; BCMA and APRIL in the interstitial zone; and BR3, TACI, and BCMA in the tubule (p < 0.05). Conclusions: The expression of BAFF and BAFF receptors is mainly associated with LN class IV, emphasizing the participation of these receptors as an essential pathogenic factor in kidney involvement in SLE patients.

Novel aspects in the pathophysiology and diagnosis of glomerular diseases

Immune deposits/complexes are detected in a multitude of tissues in autoimmune disorders, but no organ has attracted as much attention as the kidney. Several kidney diseases are characterised by the presence of specific configurations of such deposits, and many of them are under a 'shared care' between rheumatologists and nephrologists. This review focuses on five different diseases commonly encountered in rheumatological and nephrological practice, namely IgA vasculitis, lupus nephritis, cryoglobulinaemia, anti-glomerular basement membrane disease and anti-neutrophil cytoplasm-antibody glomerulonephritis. They differ in disease aetiopathogenesis, but also the potential speed of kidney function decline, the responsiveness to immunosuppression/immunomodulation and the deposition of immune deposits/complexes. To date, it remains unclear if deposits are causing a specific disease or aim to abrogate inflammatory cascades responsible for tissue damage, such as neutrophil extracellular traps or the complement system. In principle, immunosuppressive therapies have not been developed to tackle immune deposits/complexes, and repeated kidney biopsy studies found persistence of deposits despite reduction of active inflammation, again highlighting the uncertainty about their involvement in tissue damage. In these studies, a progression of active lesions to chronic changes such as glomerulosclerosis was frequently reported. Novel therapeutic approaches aim to mitigate these changes more efficiently and rapidly. Several new agents, such as avacopan, an oral C5aR1 inhibitor, or imlifidase, that dissolves IgG within minutes, are more specifically reducing inflammatory cascades in the kidney and repeat tissue sampling might help to understand their impact on immune cell deposition and finally kidney function recovery and potential impact of immune complexes/deposits.

[Characteristics of serum autoantibodies in patients with lupus nephritis and tubulointerstitial damage]

OBJECTIVE

To observe the tubulointerstitial damage (TID) in lupus nephritis (LN) and investigate the relationship between autoantibodies and TID in lupus nephritis.

METHODS

This cross-sectional study was conducted in a comprehensive tertiary hospital in Peking University Shenzhen Hospital. From March 2012 to July 2021, LN patients who performed renal biopsy were enrolled in the study. Clinical, laboratory and pathology data were collected. We classified the patients into none-or-mild group and moderate-to-severe groups according to the severity of interstitial fibrosis (IF) /tubular atrophy (TA) or tubulointerstitial inflammation (TII). The t test, U test and Chi-square test were used for statistical analysis as appropriate.

RESULTS

A total of 226 patients were included, of who 190 (84%) were female with a median age of 32 (26, 39) years. 89% (201/226) of the patients who pathologically proved to be proliferative LN by renal biopsy. The frequency of moderate-to-severe TII and moderate-to-severe IF/TA was 30% (67/226) and 34% (76/226) respectively. For autoantibodies, the patients with moderate-to-severe TII had a lower rate of positive serum anti-ribonucleoprotein (anti-RNP) antibodies than the patients with none-or-mild TII (34% vs. 51%), and moderate-to-severe IF/TA had a lower rate of positive anti-ribosomal P protein (anti-P) antibodies than patients with none-or-mild IF/TA (19% vs. 33%). For other clinical indicators, the patients with moderate-to-severe TII and moderate-to-severe IF/TA were more often combined with proliferative LN, hypertension and anemia than the patients with none-or-mild TII and none-or-mild IF/TA, respectively. The patients with moderate-to-severe TII had higher serum creatinine values and lower glomerular filtration rates than the patients with none-or-mild TII. The patients with moderate-to-severe IF/TA had higher serum creatinine values, and lower glomerular filtration rates than the patients with none-or-mild IF/TA.

CONCLUSION

In patients with LN in Southern China, anti-RNP antibodies and anti-P antibodies may be potential protective factors for TII and IF/TA, respectively. More studies are needed to identify the risk factors of lupus patients with TID and investigate the correlation between autoantibodies and TID, which are critical for developing better preventive and therapeutic strategies to improve the survival rate of LN.

Performance of Clinical and Biochemical Parameters in Identifying Renal Histopathology and Predictors of One-Year Renal Outcome in Lupus Nephritis-A Single Centre Study from India

Objectives: To assess the performance of clinical and biochemical parameters in identifying renal histopathology. To assess the performance of a combination of demographic, clinical, serological and histopathological parameters in determining renal response at one year. Methods: Data of biopsy-proven (ISN/RPS—2003 criteria) Lupus Nephritis (LN) were extracted from the institute database. Demographic, clinical and biochemical parameters at the time of biopsy were noted, and their associations with histopathological class, activity and chronicity scores were evaluated. Follow-up data at one year were collected. Complete, partial or no response (CR, PR, NR) for renal outcomes at one year and the predictors of NR were assessed. Results: Out of the 333 renal biopsies, 240 (71.8%) were Class III/IV. More patients with Class III/IV LN had hypertension (52.1%) and low eGFR (p < 0.001). Among Class III/IV, AS correlated weakly with UPCR (r = 0.31, p < 0.01), eGFR (r = −0.172; p < 0.01) and CS with eGFR (r = −0.212; p < 0.01). The presence of either hypertension, UPCR > 0.5 g/day, active urinary sediments or serum creatinine >1.3 g/dL had a sensitivity of >96% and specificity of <9% in detecting proliferative LN, crescents, interstitial inflammation and chronicity. NR was higher in males (aOR:3.9, 95% CI:1.4−11.0, p < 0.001), those with abnormal baseline creatinine (aOR: 1.9, 95% CI: 1.1−3.2, p < 0.001), higher renal SLEDAI (p < 0.05), higher AS, CS (p < 0.001) and interstitial inflammation (p < 0.005). In the binary logistic regression, the combination of male sex, baseline creatinine, UPCR and CS performed best in predicting NR (AUC: 0.762; 95% CI: 0.684−0.840, p < 0.001). Conclusions: Clinical and biochemical parameters alone have a poor specificity in identifying renal histopathology. A combination of demographic, clinical and histopathology parameters can better predict renal outcomes at one year.

Utility of the 2018 revised ISN/RPS thresholds for glomerular crescents in childhood-onset lupus nephritis: a Pediatric Nephrology Research Consortium study

BACKGROUND

The revised 2018 ISN/RPS Classification System for lupus nephritis (LN) includes calculations for both activity index (A.I.) and chronicity index (C.I.). Unchanged were the thresholds of < 25%, 25-50%, and > 50% crescents to distinguish between mild, moderate, and severe activity/chronicity. We aimed to evaluate these thresholds for percent crescents in childhood-onset LN.

METHODS

Eighty-six subjects < 21 years of age were enrolled from the Pediatric Glomerulonephritis with Crescents Registry, a retrospective multi-center cohort sponsored by the Pediatric Nephrology Research Consortium. Thresholds of 10%, 25%, and 50% for both cellular/fibrocellular and fibrous crescents were interrogated for primary outcomes of kidney failure, eGFR, and eGFR slope.

RESULTS

Median age at time of initial biopsy was 14 years (range 1-21). Median follow-up time was 3 years (range 1-11). Cumulative incidence of kidney failure was 6% at 1 year and 10% at latest follow-up. Median eGFR slope was - 18 mL/1.73 m²/min (IQR - 51 to + 8) at 1 year and - 3 mL/min/1.73 m²/year (IQR - 19 to + 6) at latest follow-up. We found no difference in kidney failure at the proposed < 25% and 25-50% cellular crescents thresholds, and thus added a new provisional threshold of 10% that better predicted outcomes in children. Moreover, use of 10% and 25% thresholds for fibrous crescents showed a fourfold and sevenfold increase in risk of kidney failure.

CONCLUSIONS

In children with crescentic LN, use of 10% and 25% thresholds for cellular crescents better reflects disease activity, while these thresholds for fibrous crescents better discriminates kidney disease outcomes. A higher resolution version of the Graphical abstract is available as Supplementary information.

Renal Fibrosis in Lupus Nephritis

Fibrosis can be defined as a pathological process in which deposition of connective tissue replaces normal parenchyma. The kidney, like any organ or tissue, can be impacted by this maladaptive reaction, resulting in persistent inflammation or long-lasting injury. While glomerular injury has traditionally been regarded as the primary focus for classification and prognosis of lupus nephritis (LN), increasing attention has been placed on interstitial fibrosis and tubular atrophy as markers of injury severity, predictors of therapeutic response, and prognostic factors of renal outcome in recent years. This review will discuss the fibrogenesis in LN and known mechanisms of renal fibrosis. The importance of the chronicity index, which was recently added to the histological categorization of LN, and its role in predicting treatment response and renal prognosis for patients with LN, will be explored. A better understanding of cellular and molecular pathways involved in fibrosis in LN could enable the identification of individuals at higher risk of progression to chronic kidney disease and end-stage renal disease, and the development of new therapeutic strategies for lupus patients.

The influence of repeated flares in response to therapy and prognosis in lupus nephritis

Background

Repeated renal flares in lupus nephritis (LN) have been associated with worse long-term kidney function. This study aimed to assess the impact of repeated LN flares in response to therapy, kidney and patient prognosis.

Methods

All patients from a biopsy-proven LN cohort between 2008 and 2018 were segregated into three groups according to the number of LN flares when they entered our cohort: first LN flare, second LN flare or third LN flare. The following outcomes were evaluated by unadjusted and adjusted time-to-event analyses: complete and partial response, disease relapses, progression to decline of 30% of the estimated glomerular filtration rate (eGFR), doubling of serum creatinine, end-stage kidney disease and patient survival.

Results

A total of 441 patients were included: 257 (58%) in their first LN flare, 102 (23%) in their second LN flare and 82 (19%) in their third LN flare. There were significant differences in LN flare presentation in age, eGFR, serum albumin, pyuria and hematuria among groups. The National Institutes of Health chronicity indices and the percentage of patients with vascular lesions were higher in groups at progressive LN flares. In the adjusted analyses, complete and partial response rates decreased, as well as kidney and patient survival, at a progressive number of LN flares. No differences in the dynamic course of all surveillance laboratory parameters were observed in the first year after initial therapy among LN flare groups.

Conclusions

A progressive number of LN flares is associated with a lower response to therapy and an adverse prognosis for kidney function and patient survival.

Acute kidney injury requiring kidney replacement therapy in childhood lupus nephritis: a cohort study of the Pediatric Nephrology Research Consortium and Childhood Arthritis and Rheumatology Research Alliance

BACKGROUND

Acute kidney injury (AKI) is common in lupus nephritis (LN) and a risk factor for development of chronic kidney disease. In adults with LN, AKI severity correlates with the incidence of kidney failure and patient survival. Data on AKI outcomes in children with LN, particularly those requiring kidney replacement therapy (KRT), are limited.

METHODS

A multicenter, retrospective cohort study was performed in children diagnosed between 2010 and 2019 with LN and AKI stage 3 treated with dialysis (AKI stage 3D). Descriptive statistics were used to characterize demographics, clinical data, and kidney biopsy findings; treatment data for LN were not included. Logistic regression was used to examine the association of these variables with kidney failure.

RESULTS

Fifty-nine patients (mean age 14.3 years, 84.7% female) were identified. The most common KRT indications were fluid overload (86.4%) and elevated blood urea nitrogen/creatinine (74.6%). Mean follow-up duration was 3.9 ± 2.9 years. AKI recovery without progression to kidney failure occurred in 37.3% of patients. AKI recovery with later progression to kidney failure occurred in 25.4% of patients, and there was no kidney recovery from AKI in 35.6% of patients. Older age, severe (> 50%) tubular atrophy and interstitial fibrosis, and National Institutes of Health (NIH) chronicity index score > 4 on kidney biopsy were associated with kidney failure.

CONCLUSIONS

Children with LN and AKI stage 3D have a high long-term risk of kidney failure. Severe tubular atrophy and interstitial fibrosis at the time of AKI, but not AKI duration, are predictive of kidney disease progression. A higher resolution version of the Graphical abstract is available as Supplementary information.

Worse long-term renal outcome of lupus nephritis patients of African descent living in Europe

INTRODUCTION

Prognosis of lupus nephritis (LN) among patients of African descent living in Europe has been understudied.

METHODS

In a retrospective study performed in two European university hospitals, we compared the prognosis of LN in patients of African descent or Caucasians. Remission was defined as a urine protein to creatinine (uP/C) ratio<0.5 g/g and a serum creatinine value<120% of baseline. Renal relapse was defined as the reappearance of a uP/C>1 g/g, leading to a repeat kidney biopsy and/or immunosuppressive treatment change. Chronic kidney disease (CKD) was defined as estimated glomerular filtration rate≤60 mL/min/1.73 m². Adherence was retrospectively assessed through medical files and/or hydroxychloroquine level measurements.

RESULTS

52 patients of African descent and 85 Caucasian patients were included in this analysis. Class III and isolated class V LN were more common among patients of African descent. Time to first renal remission did not differ between ethnic subgroups. By contrast, patients of African descent suffered from earlier renal flares, CKD was more common and time to CKD was shorter after a flare. In a multivariate analysis, African ancestry was an independent risk factor for progression to CKD. We observed no significant difference in non-adherence to treatment between the two groups.

CONCLUSION

LN patients of African descent have worse renal outcomes, mainly explained by a higher rate of renal flare.

Interstitial Inflammation in the ISN/RPS 2018 Classification of Lupus Nephritis Predicts Renal Outcomes and is Associated With Bcl-2 Expression

Objective

To investigate the histopathological characteristics of patients with lupus nephritis in the 2018 revised International Society of Nephrology/Renal Pathology Society (ISN/RPS) classification and assess the prognostic factors.

Methods

This study enrolled 92 patients with lupus nephritis, who had conventional treatment and renal biopsy. Each renal tissue was evaluated according to 2018 ISN/RPS classification, and quantified apoptotic regulator protein, the B-cell lymphoma-2 protein (Bcl-2), expressions in selected lymphocyte subsets were measured using novel computational approaches using multicolor confocal images. Histopathological characteristics and prognostic factors of end-stage renal disease (ESRD) and chronic kidney disease (CKD) were compared. Follow-up data were obtained, and survival analysis was conducted.

Results

During follow-up period (average 74.3 months), 16 and 18 patients progressed ESRD and CKD, respectively. Multivariable analysis of age, sex, disease activity and pathological features in ISN/RPS demonstrated the extent of interstitial inflammation (grade 0~3) was significantly associated with both ESRD and CKD. When interstitial inflammation was divided into mild (grade 0, 1) and severe (grade 2, 3), Cox regression analysis showed that patients with severe interstitial inflammation were significantly increased risk of both ESRD and CKD (hazard ratio 4.67 and 3.8, respectively). Bcl-2 expression in CD4+ and CD20 cells was significantly higher in the severe interstitial inflammation group compared to in mild interstitial inflammation patients (p=0.006 and 0.010, respectively).

Conclusion

The extent of interstitial inflammation can predict clinical renal outcomes. Significantly elevated Bcl-2 expression in both CD4+ and CD20 cells was found in severe interstitial inflammation compared with mild interstitial inflammation.

Persistent Isolated C3 Hypocomplementemia as a Strong Predictor of End-Stage Kidney Disease in Lupus Nephritis

Introduction

Proliferative lupus nephritis (LN) progresses to end-stage kidney disease (ESKD) in roughly 10% of the cases despite treatment. Other than achieving <0.8 g/24h proteinuria at 12 months after treatment, early biomarkers predicting ESKD or death are lacking. Recent studies encompassing not only LN have highlighted the central role of the alternative complement pathway (ACP), with or without histological evidence of thrombotic microangiopathy (TMA), as a key promotor of renal death.

Methods

We assessed whether persistent isolated C3 hypocomplementemia (PI-LowC3), that is not accompanied by C4 hypocomplementemia, 6 months after kidney biopsy, is associated with an increased risk of death or ESKD in proliferative LN.

Results

We retrospectively followed-up 197 patients with proliferative LN (51 with PI-LowC3) for a median of 4.5 years (interquartile-range: 1.9-9.0), 11 of whom died and 22 reached ESKD. After adjusting for age, gender, ethnicity, hypertension, mycophenolate, or cyclophosphamide use, PI-LowC3 was associated with a hazard ratio [HR] of the composite outcome ESKD or death of 2.46 (95% confidence interval [CI]: 1.22-4.99, P = 0.012). These results were confirmed even after controlling for time-varying estimated glomerular filtration rate (eGFR) measurements in joint longitudinal-survival multiple regression models. After accounting for the competing risk of death, PI-LowC3 patients showed a strikingly increased risk of ESKD (adjusted HR 3.41, 95% CI: 1.31-8.88, P = 0.012).

Conclusion

Our findings support the use of PI-LowC3 as a low-cost readily available biomarker, allowing clinicians to modify treatment strategies early in the course of disease and offering a rationale for complement blockade trials in this particularly at-risk subgroup of LN patients.

A Histology-Guided Approach to the Management of Patients with Lupus Nephritis: Are We There Yet?

Renal involvement is a frequent complication of systemic lupus erythematosus (SLE). It occurs in up to two-thirds of patients, often early during the disease course, and is the most important predictor of the morbidity and mortality of SLE patients. Despite tremendous improvements in the approach of the lupus nephritis (LN) therapy, including the recent approval of two new disease-modifying therapies, up to 50% of patients do not obtain a renal response and up to 25% will eventually progress to end-stage renal disease (ESRD) within 10 years of diagnosis. Given the lack of correlation between clinical features and histological lesions, there is an increasing need for a histology-guided approach to the management of patients with LN. Apart from the initial diagnosis of type and severity of renal injury in SLE, the concept of a repeat kidney biopsy (either in a for-cause or a per-protocol scenario) has begun to gain increasing popularity in the nephrology community. Herein, we will provide a comprehensive overview of the most important areas of utility of the kidney biopsy in patients with LN.

Differences and similarities of proliferative and non-proliferative forms of biopsy-proven lupus nephritis: Single centre, cross-disciplinary experience

OBJECTIVE

We aimed to compare clinical features, outcomes, treatments, and to define the predictive factors of complete renal response (CRR) in patients with proliferative and non-proliferative lupus nephritis (LN).

METHODS

Patients with systemic lupus erythematosus (SLE) followed between 2014 and 2020 at Hacettepe University Hospitals and who had a kidney biopsy were the subject of the study. One hundered and sixteen patients' kidney biopsies reported as LN were evaluated retrospectively. Clinical characteristics and laboratory values at the time of kidney biopsy, histopathological forms of LN, and renal response (complete or partial) were recorded. We analyzed the association between CRR rates during the 2-year follow-up after induction therapy and the predictive factors for CRR.

RESULTS

Of 116 (93 females, 23 males) patients, 95 (81.9%) were in the proliferative group (class III and IV) and 21 (18.1%) were in the non-proliferative group (class II and V). In the proliferative group, the percentage of the patients with elevated basal creatinine levels, median daily proteinuria, anti-double-stranded DNA (dsDNA) positivity, low C3 and C4 levels, the presence of active urinary sediment, and median renal SLE Disease Activity Index (SLEDAI) scores at the time of kidney biopsy were significantly higher than the non-proliferative group. Renal response status during the 2-year follow-up after induction therapy was available for 99 patients. During this time, 70 (70.7%) patients had achieved CRR and time-to-CRR was similar between the proliferative and non-proliferative groups (p = 0.64, log-rank test). The Cox proportional hazards model showed that achievement of CRR was associated with female gender [HR: 2.15 (1.19-3.89 95% CI), p = 0.011], newly diagnosed SLE with renal biopsy [HR: 2.15 (1.26-3.67 95% CI), p = 0.005], hypertension [HR: 0.40 (0.27-0.94 95% CI), p = 0.032], eGFR increase [HR: 1.01 (1.00-1.01 95% CI), p = 0.046], and the presence of active urinary sediment [HR: 0.46 (0.22-0.96 95% CI), p = 0.039].

CONCLUSIONS

Achieving CRR was similar in proliferative and non-proliferative LN patients, although certain laboratory parameters differed at the onset. Our results indicated the importance of kidney biopsy in the decision-making of treatment of SLE patients with renal involvement and that the defined factors associated with CRR achievement help to predict good renal response.

Effect of Combined Mycophenolate and Rapamycin Treatment on Kidney Fibrosis in Murine Lupus Nephritis

Background: A significant proportion of lupus nephritis patients develop chronic kidney disease (CKD) and progressive kidney fibrosis, for which there is no specific treatment. We previously reported that mycophenolate or rapamycin monotherapy showed comparable efficacy in suppressing kidney fibrosis in a murine model of lupus nephritis through their direct action on mesangial cells. We extended our study to investigate the effect of combined mycophenolate and rapamycin treatment (MR) on kidney fibrosis in NZBWF1/J mice.

Methods: Female NZBWF1/J mice with active nephritis were randomized to receive vehicle or treatment with mycophenolate (50 mg/kg/day) and rapamycin (1.5 mg/kg/day) (MR) for up to 12 weeks, and the effect of treatment on clinical parameters, kidney histology, and fibrotic processes was investigated.

Results: Progression of nephritis in untreated mice was accompanied by mesangial proliferation, glomerulosclerosis, tubular atrophy, protein cast formation, increased mTOR and ERK phosphorylation, and induction of TGF-β1, IL-6, α-smooth muscle actin, fibronectin, and collagen expression. Combined MR treatment prolonged survival, improved kidney function, decreased anti-dsDNA antibody level, and ameliorated histopathological changes. The effect of combined MR treatment on kidney histology and function was comparable to that of mycophenolate or rapamycin monotherapy. In vitro studies in human mesangial cells showed that exogenous TGF-β1 and IL-6 both induced mTOR and ERK phosphorylation and downstream fibrotic processes. Both mycophenolic acid and rapamycin inhibited inflammatory and fibrotic processes induced by TGF-β1 or IL-6 by downregulating mTOR and ERK phosphorylation.

Conclusions: Our findings indicate that combined mycophenolate and rapamycin, at reduced dose, improves kidney fibrosis in murine lupus nephritis through their distinct effect on mTOR and ERK signaling in mesangial cells.

Lupus Nephritis: Improving Treatment Options

Despite improvements in patient and renal death rates following the introduction of potent immunosuppressive drugs in earlier decades, a sizeable fraction of patients with lupus nephritis is burdened with suboptimal or delayed responses, relapses, chronic use of glucocorticoids and accrual of renal (chronic renal insufficiency) and extra-renal organ damage. The recently approved combinatory treatments comprising belimumab or voclosporin added to conventional agents, especially mycophenolate, hold promise for further improving disease outcomes and enabling a faster steroid tapering, thus being relevant to the treat-to-target context. However, it remains uncertain whether these dual regimens should become the first-line choice for all patients or instead be prioritized to certain subgroups. In the present article, we summarize the existing lupus nephritis management recommendations, followed by a critical appraisal of the randomized trials of belimumab and voclosporin, as well as the available data on obinutuzumab and other novel compounds under development. We conclude that pending the identification of accurate clinical, histological, or translational predictors for guiding personalized decisions, it is of utmost importance that lupus nephritis patients are monitored closely with appropriate treatment adjustments aiming at a prompt, deep response to ensure long-term preservation of kidney function.

Association of Bowman's capsule rupture with prognosis in patients with lupus nephritis

BACKGROUND AND OBJECTIVE

Lupus nephritis is one of the most severe manifestations of systemic lupus erythematosus. The clinical and prognostic significance of Bowman's capsule rupture in patients with lupus nephritis is unknown.

METHODS

One hundred eighty patients with lupus nephritis were enrolled in the study and the integrity of Bowman's capsule was assessed. Both inflammatory and proliferative cells were detected by immunochemistry staining. The primary events of interest were end-stage renal disease and death.

RESULTS

After retrospective analysis of the data, 52 (28.9%) patients were found to have Bowman's capsule rupture, which was accompanied by high levels of serum creatinine, 24 h urine protein, and Activity/Chronicity Index. Bowman's capsule rupture was correlated with the level of crescents, tubular atrophy, and interstitial fibrosis. The number of CD20⁺ cells was higher in the Bowman's capsule rupture ( +) group compared with the Bowman's capsule rupture (-) group, while no differences in other inflammatory cells were observed. In addition, the end stage renal disease-free survival in the Bowman's capsule rupture ( +) group was lower than in the Bowman's capsule rupture (-) group. Moreover, serum creatinine (HR 39.56, P < 0.001), Activity Index (HR 1.50, P < 0.05) as well as Bowman's capsule rupture (HR 1.09, P < 0.05) predicted end-stage renal disease progression. Notably, for patients with existing crescents, Bowman's capsule rupture increased the cumulative risk of end-stage renal disease.

CONCLUSIONS

Bowman's capsule rupture is an important renal pathological lesion, which correlates with severe clinical manifestations, pathological changes, and poor prognosis in patients with lupus nephritis.

Conceptual framework for defining disease modification in systemic lupus erythematosus: a call for formal criteria

Disease modification has become a well-established concept in several therapeutic areas; however, no widely accepted definition of disease modification exists for SLE.

We reviewed established definitions of disease modification in other conditions and identified a meaningful effect on ‘disease manifestations’ (ie, signs, symptoms and patient-reported outcomes) and on ‘disease outcomes’ (eg, long-term remission or progression of damage) as the key principles of disease modification, indicating a positive effect on the natural course of the disease. Based on these findings and the treatment goals and outcome measures for SLE, including lupus nephritis, we suggest a definition of disease modification based on disease activity indices and organ damage outcomes, with the latter as a key anchor. A set of evaluation criteria is also suggested.

Establishing a definition of disease modification in SLE will clarify which treatments can be considered disease modifying, provide an opportunity to harmonise future clinical trial outcomes and enable comparison between therapies, all of which could ultimately help to improve patient outcomes. This publication seeks to catalyse further discussion and provide a framework to develop an accepted definition of disease modification in SLE.

The small heat shock protein HSPB5 attenuates the severity of lupus nephritis in lupus-prone mice

Lupus nephritis (LN) is a common and serious complication of systemic lupus erythematosus. The current treatments for LN are accompanied with severe immunotoxicity and have limits of effectiveness. Since our in vitro experiments demonstrated that a small heat shock protein (HSP), alpha-B crystallin (HSPB5; CRYAB), selectively modulates myeloid cells towards anti-inflammatory and tolerogenic phenotypes, the aim of this study was to investigate whether HSPB5 can attenuate the severity of LN. MRL/lpr mice were treated intravenously with HSPB5 at 2.5 or 10 μg/dose twice per week after disease onset, from 11 to 21 weeks of age. Disease progression was monitored by weekly measurements of proteinuria, and sera, spleens, and kidneys were collected for assessment at the terminal time point. Treatment with 10 μg HSPB5 substantially reduced endocapillary proliferation and tubular atrophy, which significantly reduced proteinuria and blood urea nitrogen (BUN). Compared to vehicle, 10 μg HSPB5 treatment substantially decreased activation/proliferation of splenocytes, increased IL-10+ macrophages, T and B regulatory cells (Treg, Breg), increased serum IL-10, and lowered expression of IL-6 in kidneys, which correlated with improved kidney function and pathology. This study demonstrated the utility of exogenous human HSPB5 to attenuate severe nephropathy in MRL/lpr mice and provides evidence in favour of a novel therapeutic approach for lupus nephritis.

Impact of Consensus Definitions on Identification of Glomerular Lesions by Light and Electron Microscopy

Introduction

In 2020, a working group of 13 renal pathologists published consensus definitions for 47 individual glomerular lesions found on light microscopy (LM) and 47 glomerular lesions and 9 normal structures found on electron microscopy (EM).

Methods

To test the impact of these definitions on identification of these lesions and structures, 2 surveys were circulated to all members of the Renal Pathology Society (RPS), each having 32 images (19 LM, 13 EM) and accompanying questions with 5 multiple-choice answers, one being the consensus choice of the working group. The first survey (survey 1 [S1]), answered by 297 RPS members, was sent in September 2020, before publication of the consensus definitions. The second (survey 2 [S2]), with images of the same lesions and structures (but not the same images) and the same questions and multiple choices in different order, was sent in April 2020, 5 months after the publication of the definitions.

Results

S2 was taken by 181 RPS members; 64% also took S1 and 61% reported having read the definitions paper (def. paper). Mean agreement with the consensus answers increased modestly between the 2 surveys (65.2% vs. 72.0%, P = 0.097); the increase was greater and significant when only respondents to S2 who read the def. paper were considered (65.2% vs. 74.8%, P = 0.026). Furthermore, in S2 agreement with consensus answers was greater among respondents who read this paper versus those who did not (66.9% vs. 74.8%, P < 0.0001).

Conclusions

Publication of the consensus definitions modestly improved interobserver agreement in identification of glomerular lesions.

Immune gene expression and functional networks in distinct lupus nephritis classes

OBJECTIVE

To explore the utility of the NanoString platform in elucidating kidney immune transcripts for class III, IV and V lupus nephritis (LN) using a retrospective cohort of formalin-fixed paraffin-embedded (FFPE) kidney biopsy tissue.

METHODS

Immune gene transcript analysis was performed using the NanoString nCounter platform on RNA from LN (n=55), thin basement membrane (TBM) disease (n=14) and membranous nephropathy (MN) (n=9) FFPE kidney biopsy tissue. LN samples consisted of single class III (n=11), IV (n=23) and V (n=21) biopsies with no mixed lesions. Differential gene expression was performed with NanoString nSolver, with visualisations of volcano plots and heatmaps generated in R. Significant transcripts were interrogated to identify functional networks using STRING and Gene ontogeny terms.

RESULTS

In comparison to TBM, we identified 52 significantly differentially expressed genes common to all three LN classes. Pathway analysis showed enrichment for type I interferon (IFN) signalling, complement and MHC II pathways, with most showing the highest expression in class IV LN. Our class IV LN biopsies also showed significant upregulation of NF-κB signalling and immunological enrichment in comparison to class V LN biopsies. Transcripts from the type I IFN pathway distinguished class V LN from MN.

CONCLUSION

Our whole kidney section transcriptomic analysis provided insights into the molecular profile of class III, IV and V LN. The data highlighted important pathways common to all three classes and pathways enriched in our class IV LN biopsies. The ability to reveal molecular pathways in LN using FFPE whole biopsy sections could have clinical utility in treatment selection for LN.

Changing trends in presentation and indications of biopsy in lupus nephritis: data from the Spanish Registry of Glomerulonephritis

Background

With the ageing population and changes in the indications of diagnostic and protocol biopsies in systemic lupus erythematosus in recent years, an impact on the incidence and presentation of lupus nephritis (LN) is expected. The aim of this study was to analyse the epidemiological changes regarding clinical and histological presentation of LN in kidney biopsies performed from 1994 to 2019 included in the Spanish Registry of Glomerulonephritis.

Methods

We analysed data from 28 791 kidney biopsies from 130 Spanish hospitals comparing demographic, clinical and histological data. We divided the cohort according to the age of onset of LN into pediatric onset (<18 years), adult onset (18–50 years) and late onset (>50 years).

Results

The incidence of LN has decreased from 9.6% of all kidney biopsies in the period 1994–2013 to 7% in the last quarter of the observation period (2014–2019) (P < 0.001), despite an increase in the proportion of patients with LN that underwent repeat biopsies (16.6–24%; P < 0.001). The age of onset of LN has increased from 32 ± 14 to 38 ± 14 years (P < 0.001), with an increase in the proportion of late-onset LN (from 13% to 22% of incident LN; P < 0.001). There were no differences in the distribution of histological features at presentation over the study period. Patients with late-onset LN showed fewer gender differences, had lower GFR and presented with less-proliferative forms of LN compared with early-onset LN.

Conclusions

The frequency of biopsy-proven LN has been decreasing in recent years, despite an increasing number of repeat biopsies. Late-onset LN is increasing, presenting with worse kidney function but fewer proliferative lesions compared with younger-onset LN.