Decipher the Immunopathological Mechanisms and Set Up Potential Therapeutic Strategies for Patients with Lupus Nephritis

Bioinformatic analysis and experimental verification reveal expansion of monocyte subsets with an interferon signature in systemic lupus erythematosus patients

BACKGROUND

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder characterized by chronic inflammation and multi-organ damage. A central factor in SLE pathogenesis is the excessive production of type I interferon (IFN-I), which drives immune dysregulation. Monocytes, key components of the immune system, significantly contribute to IFN-I production. However, their specific roles in SLE remain incompletely understood.

METHODS

This study utilized bioinformatics and statistical analyses, including robust rank aggregation (RRA), DESeq2, and limma, to analyze transcriptome data from peripheral blood mononuclear cells (PBMCs) and monocytes of SLE patients and healthy controls. Single-cell RNA sequencing (scRNA-seq) data were processed using the Seurat R package to identify and characterize monocyte subsets with a strong IFN-driven gene signature. Flow cytometry was employed to validate key findings, using markers such as CD14, SIGLEC1, and IRF7 to confirm monocyte subset composition.

RESULTS

Our research has found that monocytes in SLE undergo IFN-driven transcriptional reprogramming, with the upregulation of key interferon signature genes (ISGs), forming the SLE-Related Monocyte Signature (SLERRAsignature). Moreover, the composition of mononuclear phagocyte subsets in SLE patients changes, with an increase trend in the proportion of the CD14Mono8 subset in the flare group. The differentially expressed genes (DEGs) in 13 mononuclear phagocyte subsets of SLE are mainly ISGs, and the expression of ISGs is higher in severe patients. We identified SIGLEC1+IRF7+ monocytes among these subsets and for the first time discovered this group of cells in the peripheral blood of healthy individuals. In SLE, the enrichment score of the gene set representing SIGLEC1+IRF7+ monocytes is positively correlated with the severity of SLE. Finally, flow cytometry confirmed that the frequency of CD14+SIGLEC1+IRF7+ monocytes in PBMCs was higher in SLE compared with healthy controls.

CONCLUSIONS

Our study found that the expansion of IFN-I-producing monocyte subsets, particularly the CD14+SIGLEC1+IRF7+ subset, plays a crucial role in SLE pathogenesis. This subset may serve as a potential biomarker and therapeutic target for managing SLE.

Integrative bioinformatics analysis reveals STAT1, ORC2, and GTF2B as critical biomarkers in lupus nephritis with Monkeypox virus infection

The monkeypox virus (MPXV) is currently spreading rapidly around the world, but the mechanisms by which it interacts with lupus nephritis (LN) are unknown. The aim of this study was to investigate the role and mechanism of lupus nephritis combined with monkeypox virus infection. The data comes from GEO and GeneCards.Through Limma and Weighted Gene Co-expression Network Analysis (WGCNA) analysis, differential expression genes (DEGs) and module genes were identified, and KEGG and GO enrichment analysis was carried out.In addition, a protein-protein interaction (PPI) network was constructed and LASSO regression was used to screen genes related to senescence. The diagnostic effectiveness was evaluated using a Nomogram and the receiver operating characteristic (ROC) curve and verified using GSE99967.Immune infiltration and gene set enrichment analysis (GSEA) Were also included in the study.In the end, miRNet was used to construct a miRNA-mRNA-TF network and screen targeted drugs through DGIdb. 5707 DEGs were identified in the lupus nephritis and 737 in the monkeypox data. WGCNA and Lasso regression analyses screened for three important targets (STAT1, ORC2, and GTF2B) .Predictive modeling and ROC of STAT1, ORC2 and GTF2B by Nomogram showed good diagnostic value .Immune infiltration analysis showed immune cell disorders and related pathway activation.The miRNA-mRNA-TF network covers 516 miRNAs and 15 transcription factors, and enrichment analysis shows that it plays an important role in senescence and inflammation.Potential Target Drugs Screened Include Guttiferone K And Silicon Phthalocyanine 4. This study identifies STAT1, ORC2, and GTF2B as key factors in cellular senescence and immune dysregulation associated with lupus nephritis and monkeypox infection, suggesting they may serve as important predictive targets.

Renal and Peripheral Blood Transcriptome Signatures That Predict Treatment Response in Proliferative Lupus Nephritis-A Prospective Study

Mechanisms contributing to non-response to treatment in lupus nephritis (LN) are unclear. We characterised the transcriptome of paired peripheral blood mononuclear cells (PBMCs) and renal tissues in LN before and after cyclophosphamide (CYC) treatment and identified markers that predicted treatment response. Total RNA isolated from paired PBMCs (n = 32) and renal tissues (n = 25) of 16 proliferative LN before CYC treatment, 6 months post-treatment, and during renal flare, was sequenced on Illumina Novaseq-6000 platform. Post-treatment, eight patients were clinical responders (CR), of whom four flared (FL), and eight were non-responders (NR). Comparative transcriptomic analyses before and after treatment within CR, NR, and FL groups was performed using DESeq2. Weighted gene co-expression network analysis (WGCNA) and ROC analysis was performed to identify and validate hub genes predictive of treatment response. Based on this, we observed that pathways such as degradation of cell cycle proteins, expression of G0 and G1 phase proteins, and apoptosis, were upregulated in CR PBMCs post-treatment, while IFN-γ signalling and ECM organisation were downregulated. In NR PBMCs, ECM molecules, neddylation and BCR signalling were upregulated post-CYC treatment, while in NR renal tissue, TLR, IFN and NF-κB signalling pathways were upregulated. In FL PBMCs, neutrophil degranulation and ROS and RNS production in phagocytes were downregulated following treatment, whereas, in the corresponding renal tissue, cell-ECM interactions and ISG15 antiviral mechanism were downregulated. After WGCNA and subsequent ROC analysis, TENM2, NLGN1 and AP005230.1 from PBMCs each predicted NR (AUC-0.91; p = 0.03), while combined model improved prediction (AUC-0.94; p = 0.02). AP005230.1 from renal tissue also predicted non-response (AUC-0.94; p = 0.01) and AC092436.3 from PBMCs predicted renal flare (AUC-0.81; p = 0.04). Our study identified significant DEGs/pathways specific to different treatment outcomes and hub genes that predicted non-response and renal flare.

Isolated anti-ribosomal P antibodies are associated with reduced risk of renal and articular involvement in systemic lupus erythematosus patients. An observational study from one center

Introduction

The aim of the study was to compare the specific clinical manifestations of systemic lupus erythematosus (SLE) or laboratory findings between patients with and without anti-ribosomal P (anti-P) antibodies and to investigate possible associations between isolated anti-P antibodies and these features.

Material and methods

Seventy-five SLE patients were enrolled in this study. They were recruited from the Department of Internal Medicine and Department of Rheumatology at the University Hospital of Monastir, Tunisia (January 2008 - December 2022). All patients met at least four American College of Rheumatology criteria or Systemic Lupus Erythematosus International Collaborating Clinics criteria at the time of disease diagnosis. Antibody typing was performed using a commercial line blot technique. Statistical analysis was performed using the χ2 test, Fisher's test when appropriate, Student's t-test, or Mann-Whitney U test according to normality of the data distribution.

Results

Thirty patients (40%) were positive for anti-P (anti-P+). The anti-P+ had higher frequency of skin features (26/49 [53.1%] vs. 4/26 [15.4%], p = 0.003) and central nervous system (CNS) involvement (10/15 [66.7%] vs. 20/60 [33.3%], p = 0.018) than patients without anti-P. Interestingly, anti-P+ showed a lower frequency of SLE/rheumatoid arthritis overlap syndrome (1/11 [9.1%] vs. 29/64 [45.3%], p = 0.042). The comparison between groups of patients according to the presence of anti-P, anti-dsDNA, and anti-Sm showed that the group with anti-P lacking anti-dsDNA and anti-Sm had the highest frequency of neuropsychiatric SLE (75%, p = 0.034), and the lowest frequency of lupus nephritis (0%, p = 0.029) and arthritis (12.5%, p = 0.039).

Conclusions

This study supports the association of anti-P antibodies with CNS and cutaneous manifestations. To the best of our knowledge, this is the first study to report a negative association between isolated anti-P antibodies and renal and articular involvement in SLE.

Exploring genetic associations in systemic lupus erythematosus through Mendelian randomization: implications for novel biomarkers and therapeutic targets

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by a significant health burden. There is an essential need for novel biomarkers and therapeutic targets to improve diagnosis and management. Mendelian randomization (MR) was applied to explore causal links between SLE and various biomarkers like immune cells, metabolites, and inflammatory cytokines using multiple databases. Initially, biomarkers significantly associated with SLE were identified. Bidirectional MR helped clarify these relationships, and a two-step mediation MR examined their effects on SLE risk. Intersection analysis was used to identify biomarkers with consistent effects across datasets. Four biomarkers were identified as having significant associations with SLE risk: 1-palmitoyl-2-arachidonoyl-GPI levels [odds ratio (OR), 1.379; 95% confidence interval (CI), 1.180 to 1.613; FDR, 0.046], IL-17A levels (OR, 2.197; 95% CI, 1.412 to 3.418; FDR, 0.044), N-acetyl-aspartyl-glutamate (NAAG) levels (OR, 0.882; 95% CI, 0.831 to 0.936; FDR, 0.030), and ribitol levels (OR, 0.743; 95% CI, 0.644 to 0.857; FDR, 0.012). Bidirectional MR showed an inverse effect of NAAG on IL-17A levels (OR, 0.978; 95% CI, 0.962 to 0.994; p = 0.006). Mediation analysis indicated that NAAG influenced SLE risk both directly (beta =  - 0.108) and indirectly through IL-17A (beta =  - 0.018), highlighting the potential mediating role of IL-17A. After expanding the significance criteria to p < 0.05, intersection analysis across multiple datasets revealed 29 biomarkers with consistent beta directions, including 19 potential risk factors (beta > 0) and 10 protective factors (beta < 0) for SLE. This research has revealed significant genetic associations with SLE and demonstrated that IL-17A mediates the relationship between NAAG levels and SLE risk, highlighting potential new targets for personalized therapeutic interventions. Key Points • This study employs MR to identify significant genetic associations between various biomarkers and SLE, providing novel insights into potential biomarkers and therapeutic targets. • Four key biomarkers were identified as significantly associated with SLE risk: 1-palmitoyl-2-arachidonoyl-GPI, IL-17A, N-acetyl-aspartyl-glutamate (NAAG), and ribitol. • The findings suggest that NAAG levels have a protective effect against SLE, partly mediated through IL-17A, indicating a complex interplay between these biomarkers in the pathogenesis of SLE. • Intersectional analysis across multiple datasets revealed 29 biomarkers with consistent effects on SLE risk, highlighting new directions for future research and potential personalized therapeutic strategies.

Exploring novel markers for coronary heart disease associated with systemic lupus erythematosus: A review

Systemic lupus erythematosus (SLE) is an autoimmune condition that is characterized by the production of autoantibodies and sustained inflammatory damage. Coronary heart disease (CHD) is a common complication of SLE, significantly increases CHD-related mortality in SLE patients. Despite conventional risk factors, the mechanisms contributing to a higher CHD risk require further investigation, with the immune and inflammatory aspects of SLE playing a significant role. Endothelial cell damage and dysfunction are key factors in the progression of coronary atherosclerosis in SLE patients. This review specifically focuses on endothelial dysfunction and the role of specific microRNAs in the context of SLE and CHD. In addition, we discuss the effects and functions of oxidative stress markers, endothelial progenitor cells, and circulating endothelial cells in individuals with both SLE and CHD. We also explored the typical inflammatory markers associated with SLE and CHD, addressing their clinical significance and limitations.

Roles of macrophages in lupus nephritis

LN is a serious complication of systemic lupus erythematosus (SLE), affecting up to 60% of patients with SLE and may lead to end-stage renal disease (ESRD). Macrophages play multifaceted roles in the pathogenesis of LN, including clearance of immune complexes, antigen presentation, regulation of inflammation, and tissue repair. Macrophages are abundant in the glomeruli and tubulointerstitium of LN patients and are positively correlated with serum creatinine levels and the severity of renal pathology. It has been shown that the infiltration of macrophages is closely associated with several clinical indicators, such as serum creatinine and complement C3 levels, anti-dsDNA antibody titers, Austin score, interstitial fibrosis and renal tubular atrophy. Moreover, cytokines expressed by macrophages were upregulated at LN onset and downregulated after remission, suggesting that macrophages may serve as markers of LN pathogenesis and remission. Therapies targeting macrophages have been shown to alleviate LN. There are two main types of macrophages in the kidney: kidney-resident macrophages (KRMs) and monocyte-derived macrophages (MDMs). KRMs and MDMs play different pathological roles in LN, with KRMs promoting leukocyte recruitment at sites of inflammation by expressing monocyte chemokines, while MDMs may exacerbate autoimmune responses by presenting immune complex antigens. Macrophages exhibit high plasticity and can differentiate into various phenotypes in response to distinct environmental stimuli. M1 (proinflammatory) macrophages are linked to the progression of active SLE, whereas the M2 (anti-inflammatory) phenotype is observed during the remission phase of LN. The polarization of macrophages in LN can be manipulated through multiple pathways, such as the modulation of signaling cascades including TLR 2/1, S1P, ERS, metabolic reprogramming, and HMGB1. This paper provides a comprehensive overview of the role of macrophages in the progression of lupus nephritis (LN), and elucidates how these cells and their secretory products function as indicators and therapeutic targets for the disease in the context of diagnosis and treatment of LN.

Therapeutically targeting proinflammatory type I interferons in systemic lupus erythematosus: efficacy and insufficiency with a specific focus on lupus nephritis

Type I interferons (IFN-Is) are important players in the immunopathogenesis of systemic lupus erythematosus (SLE). Pathogenic events in patients with SLE are potent triggers of IFN-I induction, yet IFN-I may induce or initiate the immunopathogenesis leading to these events. Because blocking IFN-I is effective in some clinical manifestations of SLE patients, concerns about the efficacy of anti-IFN-I therapy in patients with lupus nephritis remain. Tissues from kidney biopsies of patients with lupus nephritis revealed infiltration of various immune cells and activation of inflammatory signals; however, their correlation with renal damage is not clear, which raises serious concerns about how critical the role of IFN-I is among the potential contributors to the pathogenesis of lupus nephritis. This review addresses several issues related to the roles of IFN-I in SLE, especially in lupus nephritis, including (1) the contribution of IFN-I to the development and immunopathogenesis of SLE; (2) evidence supporting the association of IFN-I with lupus nephritis; (3) therapies targeting IFN-I and IFN-I downstream signaling molecules in SLE and lupus nephritis; (4) findings challenging the therapeutic benefits of anti-IFN-I in lupus nephritis; and (5) a perspective associated with anti-IFN-I biologics for lupus nephritis treatment. In addition to providing clear pictures of the roles of IFN-I in SLE, especially in lupus nephritis, this review addresses the lately published observations and clinical trials on this topic.

MME and PTPRC: key renal biomarkers in lupus nephritis

Background

Lupus nephritis (LN) is an autoimmune-related kidney disease with a poor prognosis, however the potential pathogenic mechanism remains unclear and there is a lack of precise biomarkers. Therefore, a thorough screening and identification of renal markers in LN are immensely beneficial to the research on its pathogenic mechanisms and treatment strategies.

Methods

We utilized bioinformatics to analyze the differentially expressed genes (DEGs) at the transcriptome level of three clusters: total renal, glomeruli, and renal tubulointerstitium in the GEO database to discover potential renal biomarkers of LN. We utilized NephroSeq datasets and measured mRNA and protein levels in the kidneys of MRL/lpr mice to confirm the expression of key DEGs.

Results

Seven significantly differential genes (EGR1, MME, PTPRC, RORC, MX1, ZBTB16, FKBP5) were revealed from the transcriptome database of GSE200306, which were mostly enriched in the pathway of the hematopoietic cell lineage and T cell differentiation respectively by KEGG and GO analysis. The seven hot differential genes were verified to have consistent change trends using three datasets from NephroSeq database. The receiver operating characteristic (ROC) curve indicated that five DEGs (PTPRC, MX1, EGR1, MME and RORC) exhibited a higher diagnostic ROC value in both the glomerulus and tubulointerstitium group. Validation of core genes using MRL/lpr mice showed that MME and PTPRC exhibit significantly differential mRNA and protein expression patterns in mouse kidneys like the datasets.

Conclusions

This study identified seven key renal biomarkers through bioinformatics analysis using the GEO and NephroSeq databases. It was identified that MME and PTPRC may have a high predictive value as renal biomarkers in the pathogenesis of LN, as confirmed by animal validation.

Lupus Nephritis from Pathogenesis to New Therapies: An Update

Lupus Nephritis (LN) still represents one of the most severe complications of Systemic Lupus Erythematosus (SLE) and a major risk factor for morbidity and mortality. However, over the last few years, several studies have paved the way for a deeper understanding of its pathogenetic mechanisms and more targeted treatments. This review aims to provide a comprehensive update on progress on several key aspects in this setting: pathogenetic mechanisms of LN, including new insight into the role of autoantibodies, complement, vitamin D deficiency, and interaction between infiltrating immune cells and kidney resident ones; the evolving role of renal biopsy and biomarkers, which may integrate information from renal histology; newly approved drugs such as voclosporin (VOC) and belimumab (BEL), allowing a more articulate strategy for induction therapy, and other promising phase III-immunosuppressive (IS) agents in the pipeline. Several adjunctive treatments aimed at reducing cardiovascular risk and progression of chronic renal damage, such as antiproteinuric agents, represent an important complement to IS therapy. Furthermore, non-pharmacological measures concerning general lifestyle and diet should also be adopted when managing LN. Integrating these therapeutic areas requires an effort towards a holistic and multidisciplinary approach. At the same time, the availability of an increasingly wider armamentarium may translate into improvements in patient's renal outcomes over the next decades.

Understanding the podocyte immune responses in proteinuric kidney diseases: from pathogenesis to therapy

The glomerular filtration barrier, comprising the inner layer of capillary fenestrated endothelial cells, outermost podocytes, and the glomerular basement membrane between them, plays a pivotal role in kidney function. Podocytes, terminally differentiated epithelial cells, are challenging to regenerate once injured. They are essential for maintaining the integrity of the glomerular filtration barrier. Damage to podocytes, resulting from intrinsic or extrinsic factors, leads to proteinuria in the early stages and eventually progresses to chronic kidney disease (CKD). Immune-mediated podocyte injury is a primary pathogenic mechanism in proteinuric glomerular diseases, including minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, and lupus nephritis with podocyte involvement. An extensive body of evidence indicates that podocytes not only contribute significantly to the maintenance of the glomerular filtration barrier and serve as targets of immune responses but also exhibit immune cell-like characteristics, participating in both innate and adaptive immunity. They play a pivotal role in mediating glomerular injury and represent potential therapeutic targets for CKD. This review aims to systematically elucidate the mechanisms of podocyte immune injury in various podocyte lesions and provide an overview of recent advances in podocyte immunotherapy. It offers valuable insights for a deeper understanding of the role of podocytes in proteinuric glomerular diseases, and the identification of new therapeutic targets, and has significant implications for the future clinical diagnosis and treatment of podocyte-related disorders.

Changes in macrophage infiltration and podocyte injury in lupus nephritis patients with repeated renal biopsy: Report of three cases

BACKGROUND

In this study, we retrospectively analysed macrophage infiltration and podocyte injury in three patients with diffuse proliferative lupus nephritis (LN) who underwent repeated renal biopsy.

CASE SUMMARY

Clinical data of three diffuse proliferative LN patients with different pathological characteristics (case 1 was LN IV-G (A), case 2 was LN IV-G (A) + V, and case 3 was LN IV-G (A) + thrombotic microangiopathy) were reviewed. All patients underwent repeated renal biopsies 6 mo later, and renal biopsy specimens were studied. Macrophage infiltration was assessed by CD68 expression detected by immunohistochemical staining, and an immunofluorescence assay was used to detect podocin expression to assess podocyte damage. After treatment, Case 1 changed to LN III-(A), Case 2 remained as type V LN lesions, and Case 3, which changed to LN IV-S (A), had the worst prognosis. We observed reduced macrophage infiltration after therapy. However, two of the patients with active lesions after treatment still showed macrophage infiltration in the renal interstitium. Before treatment, the three patients showed discontinuous expression of podocin. Notably, the integrity of podocin was restored after treatment in Case 1.

CONCLUSION

It may be possible to reverse podocyte damage and decrease the infiltrating macrophages in LN patients through effective treatment.

The Role of TRIM Proteins in Vascular Disease

There are more than 80 different tripartite motifs (TRIM) proteins within the E3 ubiquitin ligase subfamily, including proteins that regulate intracellular signaling, apoptosis, autophagy, proliferation, inflammation, and immunity through the ubiquitination of target proteins. Studies conducted in recent years have unraveled the importance of TRIM proteins in the pathophysiology of vascular diseases. In this review, we describe the effects of TRIM proteins on vascular endothelial cells, smooth muscle cells, heart, and lungs. In particular, we discuss the potential mechanisms by which TRIMs regulate diseases and shed light on the potential therapeutic applications of TRIMs.

Angiotensin II Type 2 Receptor Antibodies in Glomerular Diseases

We evaluated the concentration of AT2R antibodies in 136 patients with primary and secondary glomerular diseases: membranous nephropathy (n = 18), focal and segmental glomerulosclerosis (n = 25), systemic lupus erythematosus (n = 17), immunoglobulin A (IgA) nephropathy (n = 14), mesangial (non-IgA) proliferative nephropathy (n = 6), c-ANCA vasculitis (n = 40), perinuclear anti-neutrophil cytoplasmic antibodies (p-ANCA) vasculitis (n = 16), and compared it with a healthy control group (22 patients). Serum creatinine levels, proteinuria, serum albumin, and total protein concentrations were prospectively recorded for 2 years. The mean levels of AT2R antibodies in the lupus nephropathy group were significantly higher compared to the control group, 64.12 ± 26.95 units/mL and 9.72 ± 11.88 units/mL, respectively. There was no association between this level and the clinical course of the disease. The AT2R levels in other kinds of glomerular disease were no different from the control group. We found significant correlations between AT1R and AT2R in patients with membranous nephropathy (r = 0.66), IgA nephropathy (r = 0.61), and c-ANCA vasculitis (r = 0.63). Levels of AT2R antibodies in systemic lupus erythematosus are higher compared to other types of glomerulonephritis, vasculitis, and a healthy control group. Levels of AT2R antibodies correlate with AT1R antibodies in the groups of patients with membranous nephropathy, IgA nephropathy, and c-ANCA vasculitis. These kinds of AT2R antibodies have a stimulative effect on AT2R, but we have not found the influence of these antibodies on the clinical course of glomerular diseases.

Lupus Nephritis Risk Factors and Biomarkers: An Update

Lupus nephritis (LN) represents the most severe organ manifestation of systemic lupus erythematosus (SLE) in terms of morbidity and mortality. To reduce these risks, tremendous efforts have been made in the last decade to characterize the different steps of the disease and to develop biomarkers in order to better (i) unravel the pre-SLE stage (e.g., anti-nuclear antibodies and interferon signature); (ii) more timely initiation of therapy by improving early and accurate LN diagnosis (e.g., pathologic classification was revised); (iii) monitor disease activity and therapeutic response (e.g., recommendation to re-biopsy, new urinary biomarkers); (iv) prevent disease flares (e.g., serologic and urinary biomarkers); (v) mitigate the deterioration in the renal function; and (vi) reduce side effects with new therapeutic guidelines and novel therapies. However, progress is poor in terms of improvement with early death attributed to active SLE or infections, while later deaths are related to the chronicity of the disease and the use of toxic therapies. Consequently, an individualized treat-to-target strategy is mandatory, and for that, there is an unmet need to develop a set of accurate biomarkers to be used as the standard of care and adapted to each stage of the disease.