Lupus Nephritis: Current Perspectives and Moving Forward

Real-world treatment patterns, healthcare resource utilisation and costs in patients with SLE in the USA

OBJECTIVE

To evaluate the treatment patterns, medication adherence, concomitant corticosteroid use, factors influencing sequence of therapies (SOTs), healthcare resource utilisation (HCRU) and associated costs in adults with SLE in the USA.

METHODS

Claims data from the Merative MarketScan Commercial and Medicare Supplemental Database between 2011 and 2019 were used to identify patients with incident SLE. The date of first claim with SLE was defined as the index date, with a 24-month pre-index and ≥24-month post-index period. Descriptive statistics were used to evaluate patient demographics and baseline clinical characteristics, treatment patterns, adherence, HCRU and cost. Multivariable-adjusted logistic regression models were used to identify factors associated with transition between SOTs.

RESULTS

Overall, 2476 patients received SLE treatment. The mean (SD) age was 46.9 (14.1) years and the mean (SD) follow-up duration was 47.8 (15.7) months. High corticosteroid use was prevalent in all SOTs (≥1 corticosteroid; average dose, 16.8-19.3 mg/day; 50%-60% patients). Antimalarials were most commonly prescribed in SOT 1 (85.7%), and immunosuppressants in SOT 2 and 3 (85.4% and 77.5%, respectively). Transition frequency from SOT 1-2 (38.4%) and SOT 2-3 (16.9%) was influenced by immunosuppressant prescription, concomitant corticosteroid use, sex, severe disease activity, non-persistence and age. Adherence was highest for biologics, followed by antimalarials and immunosuppressants. SLE-related HCRU and associated costs increased with SOT progression (mean (SD) at baseline vs SOT 3, US$19 489 (US$45 336) vs US$23 201 (US$39 628)).

CONCLUSION

SLE treatment regimens with greater adherence and reduced corticosteroid use, HCRU and associated costs are needed.

Urinary biomarkers for active Lupus Nephritis that have survived independent validation across cohorts

Most reported biomarkers for lupus nephritis (LN) have not been independently validated across cohorts. Moreover, many of the documented biomarker candidates have been reported to be elevated in LN compared to healthy controls. However, biomarkers that distinguish patients with active LN (ALN) from inactive systemic lupus erythematosus (iSLE) hold significant clinical utility. Hence, our review attempts to identify urine protein biomarkers for LN that have been independently validated across two or more cohorts and exhibit good diagnostic potential for distinguishing ALN from iSLE. PubMed and OVID were screened for studies assessing the diagnostic value of urinary biomarkers in patients with ALN compared to iSLE. Forty peer-reviewed articles were evaluated, encompassing urine biomarker data from 3,411 distinct patients. Of the 32 candidate biomarkers identified, fourteen were repeatedly reported/tested in four or more papers each, namely ALCAM, CCL2 (MCP1), CD163, HAVCR1 (KIM-1), HPGDS, ICAM-1 (CD54), ICAM-2 (CD102), IGFBP-2, LCN2, NCAM-1 (CD56), SELE (E-Selectin), SELL (L-Selectin), TNFSF12 (TWEAK), and VCAM-1, with most exhibiting C-statistics of 0.80 or more across multiple studies when discriminating patients with ALN from iSLE. The 32 reproducibly elevated biomarkers for active LN mapped to nine functional categories. The urinary proteins reported here promise to serve as a liquid biopsy for ALN. Besides representing potential candidates for diagnostic, monitoring, predictive, and prognostic biomarkers in LN, they also provide a window into potential molecular processes within the kidney that may be driving LN. Thus, ongoing advances in proteomics, which offer wider proteome coverage at increased sensitivity, are likely to further reshape our perspective of urinary biomarkers for LN.

Long-term outcome of tacrolimus-based immunosuppressive treatment for patients with paediatric-onset lupus nephritis

AIM

We have previously reported the mid-term efficacy and safety of tacrolimus (Tac)-based immunosuppressive therapy in such patients, and herein, we aimed to determine their long-term outcomes (over 10 years).

METHODS

We retrospectively evaluate the data of 13 consecutive patients with biopsy-proven long-standing LN who underwent a long-term Tac-based treatment regimen. Tac was administered once daily at a dose of 3 mg as reinduction or maintenance treatment. Treatment outcomes were defined using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), urinary protein/creatinine ratio (Up/cr), serum creatinine, estimated glomerular filtration rate (eGFR) and serological lupus markers (complement C3, complement hemolytic activity [CH 50], and anti-dsDNA antibody titre), and the concomitantly administered prednisolone (PDN) dose. Data on clinical parameters and serological lupus activity were collected annually from each patient throughout the study period.

RESULTS

The patients' baseline characteristics at the treatment initiation were as follows: mean age, 18 years; Up/cr, 0.63 ± 0.69; serum C3 level, 57.2 ± 22.4 mg/dL (normal range, 79-152 mg/dL); CH50, 27.9 ± 15.7 U/mL (normal range, 23.0-46.0 U/mL); serum anti-dsDNA antibody titre, 111.7 ± 123.4 IU/mL (normal range, <12.0 IU/mL); serum creatinine, 0.60 ± 0.19 mg/dL; eGFR, 115.6 ± 21.3 mL/min and SLEDAI, 13 ± 8.1. Despite the gradual tapering of the concomitantly administered PDN dose from 18.7 ± 13.5 mg/day at baseline to 3.5 ± 2.8 mg/day at 10 years (p = .002), a marked improvement in the outcomes, compared with the baseline values, was observed within a year. Additionally, these favourable changes persisted throughout study period in most patients. Compared with the baseline values, the following measures confirmed sustained outcome improvements after a 10-year treatment: SLEDAI, 1.7 ± 2.0; serum C3 level, 83.8 ± 16.1 mg/dL; CH50, 45.6 ± 10.9 U/mL (all p < .01) and Up/cr, 0.16 ± 0.18 and serum anti-dsDNA antibody titre, 25.8 ± 28.8 IU/mL (both p < .05). Serum creatinine level and eGFR remained within the normal range in all study participants except for one patient who experienced several flare-ups. No serious adverse effects were observed.

CONCLUSION

Our results suggest that long-term Tac-based immunosuppressive treatment as maintenance therapy is beneficial and has low cytotoxicity. Therefore, it represents an attractive option for the treatment of selected patients with paediatric-onset LN in a real-world setting.

Investigation of Nutritional Factors and Malnutrition Risk Prediction Model in Hospitalized Patients with Systemic Lupus Erythematosus in China

Introduction

Nutritional status is a critical indicator of overall health and immune function, significantly influencing treatment outcomes. Despite its importance, the nutritional status of patients with systemic lupus erythematosus (SLE) often receives insufficient attention. This study aims to evaluate the nutritional status of patients with SLE, identify factors associated with malnutrition, and develop a risk prediction model for malnutrition in this population.

Methods

We collected clinical data from a convenience sample of SLE patients at a general hospital in Ningxia Province, China, between January and December 2022. Univariate and multivariate logistic regression analyses were performed to determine the independent risk factors for malnutrition. A risk prediction model was constructed and evaluated using the receiver operating characteristic (ROC) curve.

Results

This study included 420 patients with SLE (mean age: 41.43 years, 91.7% women), of whom 46.2% were malnourished based on their serum albumin levels. Multivariate logistic regression analysis identified monthly income (OR=0.192, P<0.05), sleep quality (OR=2.559, P<0.05), kidney involvement (OR=4.269, P<0.05), disease activity (OR=2.743, P<0.05), leukocyte count (OR=1.576, P<0.05), lymphocyte count (OR=0.393, P<0.05), hemoglobin (OR=0.972, P<0.05), complement C3 (OR=0.802, P<0.05), and complement C4 (OR=0.493, P<0.05) as independent risk factors for malnutrition. The prediction model showed good predictive value with an area under the ROC curve of 0.895 (95% CI: 0.823-0.840), sensitivity of 0.907, and specificity of 0.827. The Hosmer-Lemeshow test indicated a good model fit (χ²=10.779, P=0.215).

Discussion

Malnutrition is a significant concern among SLE patients, influenced by a range of socioeconomic and clinical factors. Our risk prediction model, with its high sensitivity and specificity, provides a robust tool for early identification of malnutrition in this population. Implementing this model in clinical practice can guide healthcare providers in prioritizing at-risk patients, enabling proactive nutritional interventions that could potentially improve clinical outcomes, enhance quality of life, and reduce healthcare costs associated with SLE.

Precision medicine in lupus nephritis

Lupus nephritis (LN) is a prominent manifestation of systemic lupus erythematosus (SLE), characterized by diverse clinical and histopathological features, imposing a substantial burden on patients. Although the exact cause of SLE remain undetermined, several genetic, epigenetics, hormonal, and other factors are implicated in LN pathogenesis. The management of LN rely on invasive renal biopsies, while the standard therapy of the proliferative form of LN remains empirical and relies on indiscriminate immunosuppressants (IS). These treatments exhibit unsatisfactory remission rates, trigger recurrent renal flares, and entail grave adverse effects (ADEs). The advent of precision medicine into LN entails a concentrated effort to pinpoint essential biomarkers, reshaping the landscape of LN management. The primary objective of this review is to synthesize and summarize existing research findings by elucidating the most prevalent immunological, genetic, and epigenetic alterations and deliberate on management strategies that can pave the way for precision medicine in tackling LN. Novel clinical biomarker such as serum anti-complement component 1q (anti-C1q), with urinary markers including neutrophil gelatinase-associated lipocalin (NGAL), monocyte chemoattractant protein-1 (MCP1) and tumour necrosis-like weak inducers of apoptosis (TWEAK) are strongly correlated with LN. These biomarkers have good sensitivity and specificity and perform better than conventional biomarkers in assessing LN activity. Similarly, more renal-specific genetic and epigenetic alteration have been correlated with LN susceptibility and severity. This includes variants of hyaluronan synthase 2 (HAS2), and platelet-derived growth factor receptor alpha (PDGFRA). In the future, integrating clinical, genetic, epigenetic, and targeted therapies holds promise for guiding precision medicine and improving LN outcomes.

Clinical and laboratory characteristics of early-onset and delayed-onset lupus nephritis patients: A single-center retrospective study

BACKGROUND

Lupus nephritis (LN) manifests systemic lupus erythematosus (SLE) and is characterized by various clinical and laboratory features. This study aimed to comprehensively evaluate the characteristics of LN patients according to the time of LN diagnosis: early-onset (LN diagnosed within one year from SLE diagnosis) vs. delayed-onset (LN diagnosed more than one year after SLE diagnosis).

METHODS

We conducted a retrospective analysis of medical records from all SLE patients treated at the University Hospital in Kraków, Poland, from 2012 to 2022. We collected data on demographic, clinical, and laboratory characteristics, including histological findings, treatment modalities, and disease outcomes. Statistical analyses were performed to identify factors impacting LN development and prognosis.

RESULTS

Among 331 LN patients, early-onset was diagnosed in 207 (62.54%) and delayed-onset was documented in 122 cases (36.86%). In 2 (0.6%) LN cases, the time of first kidney manifestation in the SLE course was unknown. Delayed-onset LN had a higher female-to-male ratio and younger age at SLE diagnosis. This group was associated with more severe clinical manifestations. In turn, studied subgroups did not differ in internist comorbidities, kidney histopathology, and family history regarding autoimmune diseases. Delayed-onset LN exhibited a higher frequency of anti-dsDNA, anti-Smith, anti-Ro, anti-RNP, and anti-cardiolipin IgG autoantibodies. During a 14-year follow-up period, 16 patients died. Mortality rate and causes of death were comparable in both analyzed subgroups.

CONCLUSIONS

More severe clinical manifestations in delayed-onset LN prompt strict monitoring of non-LN SLE patients to diagnose and treat kidney involvement early. Also, recognizing the higher frequency of autoantibodies such as anti-dsDNA or anti-Smith in delayed-onset LN underscores the potential value of autoantibody profiling as a diagnostic and prognostic tool.

Macrophages communicate with mesangial cells through the CXCL12/DPP4 axis in lupus nephritis pathogenesis

Lupus nephritis (LN) occurs in 50% of cases of systemic lupus erythematosus (SLE) and is one of the most serious complications that can occur during lupus progression. Mesangial cells (MCs) are intrinsic cells in the kidney that can regulate capillary blood flow, phagocytose apoptotic cells, and secrete vasoactive substances and growth factors. Previous studies have shown that various types of inflammatory cells can activate MCs for hyperproliferation, leading to disruption of the filtration barrier and impairment of renal function in LN. Here, we characterized the heterogeneity of kidney cells of LN mice by single-nucleus RNA sequencing (snRNA-seq) and revealed the interaction between macrophages and MCs through the CXC motif chemokine ligand 12 (CXCL12)/dipeptidyl peptidase 4 (DPP4) axis. In culture, macrophages modulated the proliferation and migration of MCs through this ligand-receptor interaction. In LN mice, treatment with linagliptin, a DPP4 inhibitor, effectively inhibited MC proliferation and reduced urinary protein levels. Together, our findings indicated that targeting the CXCL12/DPP4 axis with linagliptin treatment may serve as a novel strategy for the treatment of LN via the CXCL12/DPP4 axis.

Mechanism of tacrolimus in the treatment of lupus nephritis

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder, with more than half of the patients developing lupus nephritis (LN), which significantly contributes to chronic kidney disease (CKD) and end-stage renal disease (ESRD). The treatment of lupus nephritis has always been challenging. Tacrolimus (TAC), an effective immunosuppressant, has been increasingly used in the treatment of LN in recent years. This review aims to explore the mechanisms of action of tacrolimus in treating LN. Firstly, we briefly introduce the pharmacological properties of tacrolimus, including its role as a calcineurin (CaN) inhibitor, exerting immunosuppressive effects by inhibiting T cell activation and cytokine production. Subsequently, we focus on various other immunomodulatory mechanisms of tacrolimus in LN therapy, including its effects on T cells, B cells, and immune cells in kidney. Particularly, we emphasize tacrolimus' regulatory effect on inflammatory mediators and its importance in modulating the Th1/Th2 and Th17/Treg balance. Additionally, we review its effects on actin cytoskeleton, angiotensin II (Ang II)-specific vascular contraction, and P-glycoprotein activity, summarizing its impacts on non-immune mechanisms. Finally, we summarize the efficacy and safety of tacrolimus in clinical studies and trials. Although some studies have shown significant efficacy of tacrolimus in treating LN, its safety remains a challenge. We outline the potential adverse reactions of long-term tacrolimus use and provide suggestions on effectively monitoring and managing these adverse reactions in clinical practice. In general, tacrolimus, as a novel immunosuppressant, holds promising prospects for treating LN. Of course, further research is needed to better understand its therapeutic mechanisms and ensure its safety and efficacy in clinical practice.

Urinary biomarkers associated with podocyte injury in lupus nephritis

The most prevalent and devastating form of organ damage in systemic lupus erythematosus (SLE) is lupus nephritis (LN). LN is characterized by glomerular injury, inflammation, cell proliferation, and necrosis, leading to podocyte injury and tubular epithelial cell damage. Assays for urine biomarkers have demonstrated significant promise in the early detection of LN, evaluation of disease activity, and tracking of reaction to therapy. This is because they are non-invasive, allow for frequent monitoring and easy self-collection, transport and storage. Podocyte injury is believed to be a essential factor in LN. The extent and type of podocyte injury could be connected to the severity of proteinuria, making podocyte-derived cellular debris and injury-related urinary proteins potential markers for the diagnosis and monitoring of LN. This article focuses on studies examining urinary biomarkers associated with podocyte injury in LN, offering fresh perspectives on the application of biomarkers in the early detection and management of LN.

Genetic Reduction of IRF5 Expression after Disease Initiation Reduces Disease in a Mouse Lupus Model by Impacting Systemic and End-Organ Pathogenic Pathways

Gain-of-function polymorphisms in the transcription factor IFN regulatory factor 5 (IRF5) are associated with an increased risk of developing systemic lupus erythematosus. Global homozygous or heterozygous deficiency of IRF5 from birth confers protection in many lupus mouse models. However, less is known about the effects of IRF5 targeting after autoimmunity has already developed. This is an important point to clarify when considering IRF5 as a potential therapeutic target in lupus. In this study, we demonstrate that genetic reduction of IRF5 expression after disease initiation reduces disease severity in the FcγRIIB-/- Y-linked autoimmune accelerating mouse lupus model. Reduction of IRF5 expression resulted in a decrease in splenomegaly and lymphadenopathy and a reduction in splenic B cell activation and plasmablast numbers. Splenic T cell activation and differentiation were also impacted as demonstrated by an increase in the number of naive CD4+ and CD8+ T cells and a reduction in the number of memory/effector CD4+ and CD8+ T cells. Although serum antinuclear autoantibody levels were not altered, reduction in IRF5 expression led to decreased immune complex deposition and complement activation, diminished glomerular and interstitial disease, and a reduction in immune cell infiltrate in the kidney. Mechanistically, myeloid cells in the kidney produced less inflammatory cytokines after TLR7 and TLR9 activation. Overall, we demonstrate that genetic reduction of IRF5 expression during an active autoimmune process is sufficient to reduce disease severity. Our data support consideration of IRF5 as a therapeutic target and suggest that approaches targeting IRF5 in systemic lupus erythematosus may need to impact IRF5 activity both systemically and in target organs.

From systemic lupus erythematosus to lupus nephritis: The evolving road to targeted therapies

Systemic lupus erythematosus is a chronic autoimmune disease characterized by loss of tolerance against nuclear and cytoplasmic self-antigens, induction of immunity and tissue inflammation. Lupus nephritis (LN), the most important predictor of morbidity in SLE, develops in almost 30% of SLE patients at disease onset and in up to 50-60% within the first 10 years. Firstly, in this review, we put the pathogenic mechanisms of the disease into a conceptual frame, giving emphasis to the role of the innate immune system in this loss of self-tolerance and the induction of the adaptive immune response. In this aspect, many mechanisms have been described such as dysregulation and acceleration of cell-death pathways, an aberrant clearance and overload of immunogenic acid-nucleic-containing debris and IC, and the involvement of antigen-presenting cells and other innate immune cells in the induction of this adaptive immune response. This result in a clonal expansion of autoreactive lymphocytes with generation of effector T-cells, memory B-cells and plasma cells that produce autoantibodies that will cause kidney damage. Secondly, we review the immunological pathways of damage in the kidney parenchyma, initiated by autoantibody binding and immune complex deposition, and followed by complement-mediated microvascular injury, activation of kidney stromal cells and the recruitment of leukocytes. Finally, we summarize the rationale for the treatment of LN, from conventional to new targeted therapies, focusing on their systemic immunologic effects and the minimization of podocytary damage.

Disease modification achievement in patients with lupus nephritis in a real-life setting: mission impossible?

OBJECTIVE

A preliminary definition of disease modification (DM) in lupus nephritis (LN) was recently developed focusing on long-term remission and damage prevention, with minimal treatment-associated toxicity. We aimed to further specify aspects of DM criteria in LN, assess DM achievement in a real-world setting and examine potential DM predictors and long-term outcomes.

METHODS

We collected clinical/laboratory and histological inception cohort data from biopsy-proven LN patients (82% females) with ≥72 months follow-up at two joint academic centres. Specific criteria for 24-hour proteinuria, estimated glomerular filtration rate (eGFR), renal flares and glucocorticoids dose were set at three time frames (months 0-12, 13-60 and 72) to assess DM. In the first model, DM was achieved if patients fulfilled all four criteria at all three time frames (achievers). In the second model, the continued glucocorticoids reduction criterion was excluded. Logistic regression analyses were performed. Possible different trends in DM achievement between past and recent decades were also investigated.

RESULTS

DM was achieved by 60% of patients, increased to 70% when glucocorticoids excluded from DM criteria. 24-hour proteinuria at 9 months predicted DM achievement (OR 0.72, 95% CI 0.53 to 0.97, p=0.03), but none of baseline characteristics. Among patients with >72 month follow-up, non-achievers had worse renal outcomes (flares, >30% proteinuria increase, eGFR decline) than achievers at the end of follow-up (median 138 months). Patients diagnosed between 1992 and 2005 were found to have significantly lower percentages of DM achievement and met less often the glucocorticoids dose reduction criterion in all three time frames, compared with those diagnosed between 2006 and 2016 (p=0.006 and p<0.01, respectively).

CONCLUSIONS

DM was achieved by only 60% of LN patients in a real-life setting, partly due to lack of glucocorticoids dose target attainment, while DM failure was associated with worse long-term renal outcomes. This may imply limitations in the effectiveness or implementation of current LN treatments, supporting the need for novel therapeutic strategies.

Uremic Toxin Indoxyl Sulfate Promotes Macrophage-Associated Low-Grade Inflammation and Epithelial Cell Senescence

In this study, we investigated the impact of the uremic toxin indoxyl sulfate on macrophages and tubular epithelial cells and its role in modulating the response to lipopolysaccharide (LPS). Indoxyl sulfate accumulates in the blood of patients with chronic kidney disease (CKD) and is a predictor of overall and cardiovascular morbidity/mortality. To simulate the uremic condition, primary macrophages and tubular epithelial cells were incubated with indoxyl sulfate at low concentrations as well as concentrations found in uremic patients, both alone and upon LPS challenge. The results showed that indoxyl sulfate alone induced the release of reactive oxygen species and low-grade inflammation in macrophages. Moreover, combined with LPS (proinflammatory conditions), indoxyl sulfate significantly increased TNF-α, CCL2, and IL-10 release but did not significantly affect the polarization of macrophages. Pre-treatment with indoxyl sulfate following LPS challenge induced the expression of aryl hydrocarbon receptor (Ahr) and NADPH oxidase 4 (Nox4) which generate reactive oxygen species (ROS). Further, experiments with tubular epithelial cells revealed that indoxyl sulfate might induce senescence in parenchymal cells and therefore participate in the progression of inflammaging. In conclusion, this study provides evidence that indoxyl sulfate provokes low-grade inflammation, modulates macrophage function, and enhances the inflammatory response associated with LPS. Finally, indoxyl sulfate signaling contributes to the senescence of tubular epithelial cells during injury.