Gasdermin D deficiency aborts myeloid calcium influx to drive granulopoiesis in lupus nephritis.

Gasdermin D (GSDMD) is emerging as an important player in autoimmune diseases, but its exact role in lupus nephritis (LN) remains controversial. Here, we identified markedly elevated GSDMD in human and mouse LN kidneys, predominantly in CD11b+ myeloid cells. Global or myeloid-conditional deletion of GSDMD was shown to exacerbate systemic autoimmunity and renal injury in lupus mice with both chronic graft-versus-host (cGVH) disease and nephrotoxic serum (NTS) nephritis. Interestingly, RNA sequencing and flow cytometry revealed that myeloid GSDMD deficiency enhanced granulopoiesis at the hematopoietic sites in LN mice, exhibiting remarkable enrichment of neutrophil-related genes, significant increases in total and immature neutrophils as well as granulocyte/macrophage progenitors (GMPs). GSDMD-deficient GMPs and all-trans-retinoic acid (ATRA)-stimulated human promyelocytes NB4 were further demonstrated to possess enhanced clonogenic and differentiation abilities compared with controls. Mechanistically, GSDMD knockdown promoted self-renewal and granulocyte differentiation by restricting calcium influx, contributing to granulopoiesis. Functionally, GSDMD deficiency led to increased pathogenic neutrophil extracellular traps (NETs) in lupus peripheral blood and bone marrow-derived neutrophils. Taken together, our data establish that GSDMD deletion accelerates LN development by promoting granulopoiesis in a calcium influx-regulated manner, unraveling its unrecognized critical role in LN pathogenesis.

Serum antineutrophil cytoplasmic antibody positivity at the time of renal biopsy is associated with disease activity of lupus nephritis.

OBJECTIVE: To investigate the correlations between serum antineutrophil cytoplasmic antibody (ANCA) and clinicopathological features, induction treatment response, and prognosis of lupus nephritis (LN) patients. METHODS: In this retrospective study, biopsy-proven LN patients from October 2010 to September 2020 were tested for serum ANCA by indirect immunofluorescence and ELISA and were divided into ANCA-positive group and ANCA-negative group. The clinicopathological data of the two groups were analyzed and compared. RESULTS: Thirty-five of 115 patients (30.43%) were seropositive for ANCA. ANCA-positive patients had significantly higher systemic lupus erythematosus activity index and activity index scores, higher 24-h urinary protein, and lower complement three levels (p = 0.001, 0.028, 0.023, 0.009, respectively). The incidences of oral ulcers, thrombocytopenia, and leukocyturia, and the positive rates of anti-dsDNA antibody and anti-histone antibody were significantly higher in ANCA-positive group (p = 0.006, 0.019, 0.012, 0.001, 0.019, respectively). Class IV LN and fibrinoid necrosis/karyorrhexis were significantly more common in the ANCA-positive group (p = 0.027, 0.002). There was no significant difference in the total remission rate of ANCA-positive patients receiving cyclophosphamide and mycophenolate mofetil as induction therapies (83.33% vs. 66.67%, p > 0.05), while patients receiving cyclophosphamide as induction therapy had a higher total remission rate than those receiving other immunosuppressants (83.33% vs. 20%, p = 0.028). CONCLUSIONS: LN patients with ANCA seropositivity at renal biopsy have a significantly higher disease activity, and their pathological manifestations are predominantly proliferative LN. These patients require a more active immunosuppressive therapy with cyclophosphamide or mycophenolate mofetil to improve their remission rate.

Mitochondrial Dysfunction in Systemic Lupus Erythematosus with a Focus on Lupus Nephritis.

Systemic lupus erythematosus (SLE) is an autoimmune disease affecting mostly women of child-bearing age. Immune dysfunction in SLE results from disrupted apoptosis which lead to an unregulated interferon (IFN) stimulation and the production of autoantibodies, leading to immune complex formation, complement activation, and organ damage. Lupus nephritis (LN) is a common and severe complication of SLE, impacting approximately 30% to 40% of SLE patients. Recent studies have demonstrated an alteration in mitochondrial homeostasis in SLE patients. Mitochondrial dysfunction contributes significantly to SLE pathogenesis by enhancing type 1 IFN production through various pathways involving neutrophils, platelets, and T cells. Defective mitophagy, the process of clearing damaged mitochondria, exacerbates this cycle, leading to increased immune dysregulation. In this review, we aim to detail the physiopathological link between mitochondrial dysfunction and disease activity in SLE. Additionally, we will explore the potential role of mitochondria as biomarkers and therapeutic targets in SLE, with a specific focus on LN. In LN, mitochondrial abnormalities are observed in renal cells, correlating with disease progression and renal fibrosis. Studies exploring cell-free mitochondrial DNA as a biomarker in SLE and LN have shown promising but preliminary results, necessitating further validation and standardization. Therapeutically targeting mitochondrial dysfunction in SLE, using drugs like metformin or mTOR inhibitors, shows potential in modulating immune responses and improving clinical outcomes. The interplay between mitochondria, immune dysregulation, and renal involvement in SLE and LN underscores the need for comprehensive research and innovative therapeutic strategies. Understanding mitochondrial dynamics and their impact on immune responses offers promising avenues for developing personalized treatments and non-invasive biomarkers, ultimately improving outcomes for LN patients.

Multiscale topology classifies cells in subcellular spatial transcriptomics.

Spatial transcriptomics measures in situ gene expression at millions of locations within a tissue1, hitherto with some trade-off between transcriptome depth, spatial resolution and sample size2. Although integration of image-based segmentation has enabled impactful work in this context, it is limited by imaging quality and tissue heterogeneity. By contrast, recent array-based technologies offer the ability to measure the entire transcriptome at subcellular resolution across large samples3-6. Presently, there exist no approaches for cell type identification that directly leverage this information to annotate individual cells. Here we propose a multiscale approach to automatically classify cell types at this subcellular level, using both transcriptomic information and spatial context. We showcase this on both targeted and whole-transcriptome spatial platforms, improving cell classification and morphology for human kidney tissue and pinpointing individual sparsely distributed renal mouse immune cells without reliance on image data. By integrating these predictions into a topological pipeline based on multiparameter persistent homology7-9, we identify cell spatial relationships characteristic of a mouse model of lupus nephritis, which we validate experimentally by immunofluorescence. The proposed framework readily generalizes to new platforms, providing a comprehensive pipeline bridging different levels of biological organization from genes through to tissues.

The PP2A inhibitor LB-100 mitigates lupus nephritis by suppressing tertiary lymphoid structure formation.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by multi-organ involvement and autoantibody production. Patients with SLE face a substantial risk of developing lupus nephritis (LN), which imposes a substantial burden on both patients and their families. Protein phosphatase 2A (PP2A) is a widely distributed serine/threonine phosphatase that participates in regulating multiple signaling pathways. Inhibition of PP2A has been implicated in the treatment of various diseases. LB-100, a small molecule inhibitor of PP2A, has demonstrated anti-tumor therapeutic effects and high safety profile in preclinical experiments. However, the role of PP2A and its inhibitor has been insufficiently studied in LN. In this study, we assessed the potential effects of LB-100 in both MRL/lpr mice and R848-induced BALB/c mice. Our findings indicated that LB-100 administration led to reduced spleen enlargement, decreased deposition of immune complexes, ameliorated renal damage, and improved kidney function in both spontaneous and R848-induced lupus mouse models. Importantly, we observed the formation of tertiary lymphoid structures (TLSs) in the kidneys of two distinct lupus mouse models. The levels of signature genes of TLS were elevated in the kidneys of lupus mice, whereas LB-100 mitigated chemokine production and inhibited TLS formation. In addition, we confirmed that inhibition or knockdown of PP2A reduced the production of T cell-related chemokines by renal tubular epithelial cells (RTEC). In summary, our study highlighted the renal protective potential of the PP2A inhibitor LB-100 in two distinct lupus mouse models, suggesting its potential as a novel strategy for treating LN and other autoimmune diseases.

Purification and analysis of kidney-infiltrating leukocytes in a mouse model of lupus nephritis.

Renal injury often occurs as a complication in autoimmune diseases such as systemic lupus erythematosus (SLE). It is estimated that a minimum of 20% SLE patients develop lupus nephritis, a condition that can be fatal when the pathology progresses to end-stage renal disease. Studies in animal models showed that incidence of immune cell infiltrates in the kidney was linked to pathological injury and correlated with severe lupus nephritis. Thus, preventing immune cell infiltration into the kidney is a potential approach to impede the progression to an end-stage disease. A requirement to investigate the role of kidney-infiltrating leukocytes is the development of reproducible and efficient protocols for purification and characterization of immune cells in kidney samples. This chapter describes a detailed methodology that discriminates tissue-resident leukocytes from blood-circulating cells that are found in kidney. Our protocol was designed to maximize cell viability and to reduce variability among samples, with a combination of intravascular staining and magnetic bead separation for leukocyte enrichment. Experiments included as example were performed with FcγRIIb[KO] mice, a well-characterized murine model of SLE. We identified T cells and macrophages as the primary leukocyte subsets infiltrating into the kidney during severe nephritis, and we extensively characterized them phenotypically by flow cytometry.

Machine learning models predicts risk of proliferative lupus nephritis.

Objective: This study aims to develop and validate machine learning models to predict proliferative lupus nephritis (PLN) occurrence, offering a reliable diagnostic alternative when renal biopsy is not feasible or safe. Methods: This study retrospectively analyzed clinical and laboratory data from patients diagnosed with SLE and renal involvement who underwent renal biopsy at West China Hospital of Sichuan University between 2011 and 2021. We randomly assigned 70% of the patients to a training cohort and the remaining 30% to a test cohort. Various machine learning models were constructed on the training cohort, including generalized linear models (e.g., logistic regression, least absolute shrinkage and selection operator, ridge regression, and elastic net), support vector machines (linear and radial basis kernel functions), and decision tree models (e.g., classical decision tree, conditional inference tree, and random forest). Diagnostic performance was evaluated using ROC curves, calibration curves, and DCA for both cohorts. Furthermore, different machine learning models were compared to identify key and shared features, aiming to screen for potential PLN diagnostic markers. Results: Involving 1312 LN patients, with 780 PLN/NPLN cases analyzed. They were randomly divided into a training group (547 cases) and a testing group (233 cases). we developed nine machine learning models in the training group. Seven models demonstrated excellent discriminatory abilities in the testing cohort, random forest model showed the highest discriminatory ability (AUC: 0.880, 95% confidence interval(CI): 0.835-0.926). Logistic regression had the best calibration, while random forest exhibited the greatest clinical net benefit. By comparing features across various models, we confirmed the efficacy of traditional indicators like anti-dsDNA antibodies, complement levels, serum creatinine, and urinary red and white blood cells in predicting and distinguishing PLN. Additionally, we uncovered the potential value of previously controversial or underutilized indicators such as serum chloride, neutrophil percentage, serum cystatin C, hematocrit, urinary pH, blood routine red blood cells, and immunoglobulin M in predicting PLN. Conclusion: This study provides a comprehensive perspective on incorporating a broader range of biomarkers for diagnosing and predicting PLN. Additionally, it offers an ideal non-invasive diagnostic tool for SLE patients unable to undergo renal biopsy.

Elucidating the function of STING in systemic lupus erythematosus through the STING Goldenticket mouse mutant.

The complexity of systemic lupus erythematosus (SLE) arises from intricate genetic and environmental interactions, with STING playing a pivotal role. This study aims to comprehend the function of STING using the pristane-induced lupus (PIL) model in Sting missense mutant mice (Goldenticket or StingGt), which contrasts with previous research using Sting knockout mice. Investigating two-month-old StingGt mice over six months post-PIL induction, we observed a profound reduction in autoimmune markers, including antinuclear and anti-dsDNA antibodies, germinal center B cells, and plasma cells, compared to their wild-type counterparts. A pivotal finding was the marked decrease in IL-17-producing T cells. Notably, the severity of lupus nephritis and pulmonary hemorrhages was significantly diminished in StingGt mice. These findings demonstrate that different genetic approaches to interfere with STING signaling can lead to contrasting outcomes in SLE pathogenesis, which highlights the need for a nuanced understanding of the role of STING in drug development for SLE. In summary, the loss of Sting function in Goldenticket mutant mice rescued autoimmune phenotypes in PIL. This study reveals the critical nature of STING in SLE, suggesting that the method of STING modulation significantly influences disease phenotypes and should be a key consideration in developing targeted therapies.

Tubular biomarkers and histology in lupus nephritis.

INTRODUCTION: The relevance of tubulo-interstitial involvement for kidney prognosis has recently been emphasized, but validated biomarkers for predicting histology are still lacking. The aim of our study was to evaluate different serum and urinary markers of tubular damage in patients with lupus nephritis (LN) and to correlate them with kidney histopathology. METHODS: A single-center retrospective study was conducted from January 2016 to December 2021. Serum and urine samples were collected on the same day of kidney biopsy and correlated with histologic data from a cohort of 15 LN patients. We analyzed the following urinary markers, adjusted for urine creatinine: beta 2-microglobulin, alpha 1-microglobulin, NGAL, uKIM-1, MCP-1, uDKK-3, and uUMOD. The serum markers sKIM-1 and sUMOD were also analyzed. RESULTS: A positive and strong correlation was observed between the degree of interstitial fibrosis (rho = 0.785, p = .001) and tubular atrophy (rho = 0.781, p = .001) and the levels of uDKK3. uUMOD also showed an inverse and moderate correlation with interstitial fibrosis (rho = -0.562, p = .037) and tubular atrophy (rho = -0.694, p = .006). Patients with >10% cortical interstitial inflammation had higher levels of uKIM-1 [4.9 (3.9, 5.5) vs. 0.8 (0.6, 1.5) mcg/mg, p = .001], MCP-1 [3.8 (2. 3, 4.2) vs. 0.7 (0.3, 1.2) mcg/mg, p = .001], sKIM-1 [9.2 (5.9, 32.7) vs. 1.4 (0, 3.5) pg/mL, p = .001], and lower sUMOD [8.7 (0, 39.7) vs. 46.1 (35.7, 53) ng/mL, p = .028]. CONCLUSION: The use of specific urinary and serum biomarkers of tubular dysfunction or injury may help to predict certain histologic parameters in LN patients.

Podocyte SIRPα reduction aggravates lupus nephritis via promoting T cell inflammatory responses.

Signal-regulatory protein alpha (SIRPα) has recently been found to be highly expressed in podocytes and is essential for maintaining podocyte function. However, its immunoregulatory function in podocytes remains elusive. Here, we report that SIRPα controls podocyte antigen presentation in specific T cell activation via inhibiting spleen tyrosine kinase (Syk) phosphorylation. First, podocyte SIRPα under lupus nephritis (LN) conditions is strongly downregulated. Second, podocyte-specific deletion of SIRPα exacerbates renal disease progression in lupus-prone mice, as evidenced by an increase in T cell infiltration. Third, SIRPα deletion or knockdown enhances podocyte antigen presentation, which activates specific T cells, via enhancing Syk phosphorylation. Supporting this, Syk inhibitor GS-9973 prevents podocyte antigen presentation, resulting in a decrease of T cell activation and mitigation of renal disease caused by SIRPα knockdown or deletion. Our findings reveal an immunoregulatory role of SIRPα loss in promoting podocyte antigen presentation to activate specific T cell immune responses in LN.

The STING inhibitor (ISD-017) reduces glomerulonephritis in 129.B6.Fcgr2b-deficient mice.

The absence of stimulator of interferon genes (STING) in 129.B6.Fcgr2b-deficient mice rescue lupus phenotypes. The administration of a STING inhibitor (ISD017) into the young 129.B6.Fcgr2b-deficient mice prevents lupus nephritis development. This study mainly aimed to evaluate the effects of STING inhibition (ISD107) on established SLE in mice to prove that ISD017 could be a good therapeutic drug to reverse the already set-up autoimmunity and kidney impairment. Twenty-four-week-old Fcgr2b-deficient mice were treated with cyclophosphamide (25 mg/kg, intraperitoneal, once per week), ISD017 (10 mg/kg, intraperitoneal, three times per week), or control vehicle for 8 weeks, and were analyzed for phenotypes. Both ISD017 and cyclophosphamide treatment increased long-term survival and reduced the severity of glomerulonephritis in Fcgr2b-deficient mice. While cyclophosphamide reduced activated B cells (B220+GL-7+), ISD017 decreased activated T cells (CD4+CD69+) and neutrophils (Ly6c+Ly6g+) in Fcgr2b-deficient mice. In addition, ISD017 reduced IL-1ß and interferon-inducible genes. In summary, ISD017 treatment in symptomatic 129.B6.Fcgr2b-deficient mice reduced the severity of glomerulonephritis and increased long-term survival. ISD017 worked comparably to cyclophosphamide for treating lupus nephritis in 129.B6.Fcgr2b-deficient mice. ISD017 reduced activated T cells and neutrophils, while cyclophosphamide targeted activated B cells. These results suggested that STING inhibitors can potentially be a new therapeutic drug for treating lupus.

Tubular expression of Toll-like receptor 9 in lupus and primary membranous nephropathy.

INTRODUCTION: Toll-like- receptors (TLR) control important aspects of innate and adaptive immune responses. Renal cells are among the non-immune cells that express (TLR). Therefore, their activation might be implicated in renal tubulo-interstitial injury. AIM: The study aimed to compare TLR9 expression in patients with primary membranous nephropathy (MN) to patients with lupus membranous nephropathy. METHODS: Kidney sections from 10 Lupus nephritis (LN) patients and ten patients with primary MN were analyzed by immunohistochemistry using anti-human TLR9 antibody. RESULTS: Results showed that TLR9 expression was weak and exclusively tubular in primary MN patients' biopsies. There was a significant difference between LN patients' biopsies and primary MN patients' biopsies. TLR9 expression was more diffused in LN patients' specimen than in those with primary MN. CONCLUSION: This study focuses on molecular level pathogenesis of MN. The data suggest that the receptors TLR9 may play role in tubulointerstitial injury in the pathogenesis of LN but not primary membranous nephropathy.

Characterizing Glomerular Barrier Dysfunction with Patient-Derived Serum in Glomerulus-on-a-Chip Models: Unveiling New Insights into Glomerulonephritis.

Glomerulonephritis (GN) is characterized by podocyte injury or glomerular filtration dysfunction, which results in proteinuria and eventual loss of kidney function. Progress in studying the mechanism of GN, and developing an effective therapy, has been limited by the absence of suitable in vitro models that can closely recapitulate human physiological responses. We developed a microfluidic glomerulus-on-a-chip device that can recapitulate the physiological environment to construct a functional filtration barrier, with which we investigated biological changes in podocytes and dynamic alterations in the permeability of the glomerular filtration barrier (GFB) on a chip. We also evaluated the potential of GN-mimicking devices as a model for predicting responses to human GN. Glomerular endothelial cells and podocytes successfully formed intact monolayers on opposite sides of the membrane in our chip device. Permselectivity analysis confirmed that the chip was constituted by a functional GFB that could accurately perform differential clearance of albumin and dextran. Reduction in cell viability resulting from damage was observed in all serum-induced GN models. The expression of podocyte-specific marker WT1 was also decreased. Albumin permeability was increased in most models of serum-induced IgA nephropathy (IgAN) and membranous nephropathy (MN). However, sera from patients with minimal change disease (MCD) or lupus nephritis (LN) did not induce a loss of permeability. This glomerulus-on-a-chip system may provide a platform of glomerular cell culture for in vitro GFB in formation of a functional three-dimensional glomerular structure. Establishing a disease model of GN on a chip could accelerate our understanding of pathophysiological mechanisms of glomerulopathy.

The atypical chemokine receptor 2 reduces T cell expansion and tertiary lymphoid tissue but does not limit autoimmune organ injury in lupus-prone B6lpr mice.

Introduction: The atypical chemokine receptor 2 (ACKR2) is a chemokine scavenger receptor, which limits inflammation and organ damage in several experimental disease models including kidney diseases. However, potential roles of ACKR2 in reducing inflammation and tissue injury in autoimmune disorders like systemic lupus erythematosus (SLE) and lupus nephritis are unknown, as well as its effects on systemic autoimmunity. Methods: To characterize functional roles of ACKR2 in SLE, genetic Ackr2 deficiency was introduced into lupus-prone C57BL/6lpr (Ackr2-/- B6lpr) mice. Results: Upon inflammatory stimulation in vitro, secreted chemokine levels increased in Ackr2 deficient tubulointerstitial tissue but not glomeruli. Moreover, Ackr2 expression was induced in kidneys and lungs of female C57BL/6lpr mice developing SLE. However, female Ackr2-/- B6lpr mice at 28 weeks of age showed similar renal functional parameters as wildtype (WT)-B6lpr mice. Consistently, assessment of activity and chronicity indices for lupus nephritis revealed comparable renal injury. Interestingly, Ackr2-/- B6lpr mice showed significantly increased renal infiltrates of CD3+ T and B cells, but not neutrophils, macrophages or dendritic cells, with T cells predominantly accumulating in the tubulointerstitial compartment of Ackr2-/- B6lpr mice. In addition, histology demonstrated significantly increased peribronchial lung infiltrates of CD3+ T cells in Ackr2-/- B6lpr mice. Despite this, protein levels of pro-inflammatory chemokines and mRNA expression of inflammatory mediators were not different in kidneys and lungs of WT- and Ackr2-/- B6lpr mice. This data suggests compensatory mechanisms for sufficient chemokine clearance in Ackr2-deficient B6lpr mice in vivo. Analysis of systemic autoimmune responses revealed comparable levels of circulating lupus-associated autoantibodies and glomerular immunoglobulin deposition in the two genotypes. Interestingly, similar to kidney and lung CD4+ T cell numbers and activation were significantly increased in spleens of Ackr2-deficient B6lpr mice. In lymph nodes of Ackr2-/- B6lpr mice abundance of activated dendritic cells decreased, but CD4+ T cell numbers were comparable to WT. Moreover, increased plasma levels of CCL2 were present in Ackr2-/- B6lpr mice, which may facilitate T cell mobilization into spleens and peripheral organs. Discussion: In summary, we show that ACKR2 prevents expansion of T cells and formation of tertiary lymphoid tissue, but is not essential to limit autoimmune tissue injury in lupus-prone B6lpr mice.

STAT3 inhibition ameliorates renal interstitial inflammation in MRL/lpr mice with diffuse proliferative lupus nephritis.

BACKGROUND AND OBJECTIVES: Acute kidney injury (AKI) is one of the most common and severe clinical syndromes of diffuse proliferative lupus nephritis (DPLN), of which poor prognosis is indicated by aggravated renal function deterioration. However, the specific therapy and mechanisms of AKI in DPLN remain to be explored. METHODS: The correlation between AKI and clinical pathological changes in DPLN patients was analyzed. Expression of STAT3 signaling was detected in MRL/lpr mice with DPLN using immunohistochemical staining and immunoblotting. Inhibition of STAT3 activation by combination therapy was assessed in MRL/lpr mice. RESULTS: Correlation analysis revealed only the interstitial leukocytes were significantly related to AKI in endocapillary DPLN patients. MRL/lpr mice treated with vehicle, which can recapitulate renal damages of DPLN patients, showed upregulation of STAT3, pSTAT3 and caspase-1 in renal cortex. FLLL32 combined with methylprednisolone therapy significantly inhibited the STAT3 activation, improved acute kidney damage, reduced the interstitial infiltration of inflammatory cells and decreased the AKI incidence in MRL/lpr mice. CONCLUSION: STAT3 activation may play an important role in the pathogenesis of DPLN and the development of AKI. Hence, STAT3 inhibition based on the combination of FLLL32 with methylprednisolone may represent a new strategy for treatment of DPLN with AKI.

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.

Zhen-Wu-Tang ameliorates lupus nephritis by diminishing renal tissue-resident memory CD8+ T cells via suppressing IL-15/STAT3 pathway.

Zhen-Wu-Tang (ZWT), a conventional herbal mixture, has been recommended for treating lupus nephritis (LN) in clinic. However, its mechanisms of action remain unknown. Here we aimed to define the immunological mechanisms underlying the effects of ZWT on LN and to determine whether it affects renal tissue-resident memory T (TRM) cells. Murine LN was induced by a single injection of pristane, while in vitro TRM cells differentiated with IL-15/TGF-ß. We found that ZWT or mycophenolate mofetil treatment significantly ameliorated kidney injury in LN mice by decreasing 24-h urine protein, Scr and anti-dsDNA Ab. ZWT also improved renal pathology and decreased IgG and C3 depositions. In addition, ZWT down-regulated renal Desmin expression. Moreover, it lowered the numbers of CD8+ TRM cells in kidney of mice with LN while decreasing their expression of TNF-α and IFN-γ. Consistent with in vivo results, ZWT-containing serum inhibited TRM cell differentiation induced by IL-15/TGF-ß in vitro. Mechanistically, it suppressed phosphorylation of STAT3 and CD122 （IL2/IL-15Rß）expression in CD8+ TRM cells. Importantly, ZWT reduced the number of total F4/80+CD11b+ and CD86+, but not CD206+, macrophages in the kidney of LN mice. Interestingly, ZWT suppressed IL-15 protein expression in macrophages in vivo and in vitro. Thus, we have provided the first evidence that ZWT decoction can be used to improve the outcome of LN by reducing CD8+ TRM cells via inhibition of IL-15/IL-15R /STAT3 signaling.

Percutaneous kidney biopsies in children: a 24-year review in a tertiary center in northern Portugal.

INTRODUCTION: Percutaneous kidney biopsy (KB) is crucial to the diagnosis and management of several renal pathologies. National data on native KB in pediatric patients are scarce. We aimed to review the demographic and clinical characteristics and histopathological patterns in children who underwent native percutaneous KB over 24 years. METHODS: Retrospective observational study of patients undergoing native percutaneous KB in a pediatric nephrology unit between 1998 and 2021, comparing 3 periods: period 1 (1998-2005), period 2 (2006-2013), and period 3 (2014-2021). RESULTS: We found that 228 KB were performed, 78 (34.2%) in period 1, 91 (39.9%) in period 2, and 59 (25.9%) in period 3. The median age at KB was 11 (7-14) years. The main indications for KB were nephrotic syndrome (NS) (42.9%), hematuria and/or non-nephrotic proteinuria (35.5%), and acute kidney injury (13.2%). Primary glomerulopathies were more frequent (67.1%), particularly minimal change disease (MCD) (25.4%), IgA nephropathy (12.7%), and mesangioproliferative glomerulonephritis (GN) (8.8%). Of the secondary glomerulopathies, lupus nephritis (LN) was the most prevalent (11.8%). In group 1, hematuria and/or non-nephrotic proteinuria were the main reasons for KB, as opposed to NS in groups 2 and 3 (p < 0.01). LN showed an increasing trend (period 1-3: 2.6%-5.3%) and focal segmental glomerular sclerosis (FSGS) showed a slight decreasing trend (period 1-3: 3.1%-1.8%), without statistical significance. CONCLUSIONS: The main indication for KB was NS, which increased over time, justifying the finding of MCD as main histological diagnosis. LN showed an increase in incidence over time, while FSGS cases did not increase.

Moesin deficiency leads to lupus-like nephritis with accumulation of CXCL13-producing patrolling monocytes.

Moesin is a member of the ezrin-radixin-moesin (ERM) family of proteins that link plasma membrane proteins to the cortical cytoskeleton and thus regulate diverse cellular processes. Mutations in the human moesin gene cause a primary immunodeficiency called X-linked moesin-associated immunodeficiency (X-MAID), which may be complicated by an autoimmune phenotype with kidney involvement. We previously reported that moesin-deficient mice exhibit lymphopenia similar to that of X-MAID and develop a lupus-like autoimmune phenotype with age. However, the mechanism through which moesin defects cause kidney pathology remains obscure. Here, we characterized immune cell infiltration and chemokine expression in the kidney of moesin-deficient mice. We found accumulation of CD4+ T and CD11b+ myeloid cells and high expression of CXCL13, whose upregulation was detected before the onset of overt nephritis. CD4+ T cell population contained IFN-γ-producing effectors and expressed the CXCL13 receptor CXCR5. Among myeloid cells, Ly6Clo patrolling monocytes and MHCIIlo macrophages markedly accumulated in moesin-deficient kidneys and expressed high CXCL13 levels, implicating the CXCL13-CXCR5 axis in nephritis development. Functionally, Ly6Clo monocytes from moesin-deficient mice showed reduced migration toward sphingosine 1-phosphate. These findings suggest that moesin plays a role in regulating patrolling monocyte homeostasis, and that its defects lead to nephritis associated with accumulation of CXCL13-producing monocytes and macrophages.

Upregulation of PD-1 and its ligands and expansion of T peripheral helper cells in the nephritic kidneys of lupus-prone BXSB-Yaa mice.

OBJECTIVE: This study aimed to investigate the role of the programmed cell death protein 1 (PD-1) pathway and T peripheral helper (Tph) cells in the pathogenesis of lupus nephritis using lupus-prone BXSB-Yaa mice. METHODS: Male BXSB-Yaa mice and age-matched male C57BL/6 mice were used. The expression of PD-1 and its ligands (programmed cell death 1 ligand-1, PD-L1 and programmed cell death 1 ligand-2, PD-L2) and the phenotypes of kidney-derived cells and splenocytes expressing these molecules were analyzed by immunofluorescence and flow cytometry. RESULTS: Nephritis spontaneously developed in 16-week-old but not in 8-week-old BXSB-Yaa or C57BL/6 mice. PD-1 was expressed on CD4+ mononuclear cells (MNCs) that infiltrated the glomeruli of 16-week-old BXSB-Yaa mice. The frequency of CD4+PD-1+CXCR5-ICOS+ kidney-derived Tph cells was higher in 16-week-old than in 8-week-old BXSB-Yaa and C57BL/6 mice, whereas the frequency of CD4+PD-1+CXCR5+ICOS+ kidney-derived T follicular helper (Tfh) cells was not significantly different between the mice. PD-L1 was constitutively expressed in the renal tubules. PD-L2 was expressed in the glomeruli of 16-week-old BXSB-Yaa mice. The frequency of PD-L1highCD11c+CD3-CD19- and PD-L2+CD11c+CD3-CD19- kidney-derived MNCs in 16-week-old BXSB-Yaa mice was significantly higher than that of the control mice. The percentage of kidney-derived Tph cells but not Tfh cells was correlated with the urinary protein levels in the nephritic mice. CONCLUSION: The results of this study suggest that kidney-infiltrating PD-1+ Tph cells expanded concomitantly with the upregulation of PD-L1 and PD-L2 in the kidneys and the progression of lupus nephritis.