anti-GBM Glomerulonephritis Research Articles

Production of Acetylcholine by Podocytes and its Protection from Kidney Injury in Glomerulonephritis.

One of the most important factors modulating endothelial health is acetylcholine, and while it is associated as a cholinergic neurotransmitter; it is also expressed by non-neuronal cells. However, its role in the kidney, which does not receive cholinergic innervation, remains unknown. To determine if acetylcholine is produced in the kidney, we used ChAT(BAC)-eGFP (ChAT mice) transgenic mice in which enhanced green fluorescent protein (eGFP) is expressed under the control of the endogenous choline acetyltransferase (ChAT) transcriptional regulatory elements. We then investigated the role of acetylcholine in kidney disease by inducing anti- glomerular basement membrane glomerulonephritis (anti-GBM GN) in ChAT transgenic mice. We demonstrate ChAT, the sole enzyme responsible for acetylcholine production, was expressed in glomerular podocytes and produced acetylcholine. We also show during anti-GBM GN in ChAT transgenic mice, ChAT expression was induced in the glomeruli, mainly in podocytes and protects mice from kidney injury with marked reduction of glomerular proliferation/fibrinoid necrosis (by 71%) crescent formation (by 98%), and tubular injury (by 78%). In contrast, specific knockout of podocyte ChAT worsened the severity of the disease. The mechanism of protection included reduction of inflammation, attenuation of angiogenic factors reduction, and increase of eNOS expression. In vitro and in vivo studies demonstrated available drugs like cholinesterase inhibitors and ChAT inducers increased the expression of podocyte-ChAT and acetylcholine production. These findings suggest de novo synthesis of acetylcholine by podocytes protected against inflammation and glomerular endothelium damage in anti-GBM glomerulonephritis.

Diagnosis of membranous nephropathy with Anti-GBM glomerulonephritis: a case series report

BackgroundThe concomitant occurrence of membranous nephropathy and anti-glomerular basement (anti-GBM) disease has been previously described but is extremely rare. However, delayed recognition or misdiagnosis leads to delayed treatment, resulting in worse renal and patient outcomes.Case presentationWe present 3 patients with rapidly progressive glomerulonephritis (RPGN), anti-GBM and serum-positive M-type phospholipase A2 receptor (anti-PLA2R) antibody. Renal biopsies revealed PLA2R-associated membranous nephropathy with anti-GBM glomerulonephritis. We analyzed the clinical and pathological characteristics and discussed that the correct diagnosis of membranous nephropathy with anti-GBM should rely on a combination of renal biopsy findings and serological testing. Despite aggressive treatment, one patient received maintenance hemodialysis, one patient progressed to CKD 3 stage, and the other patient died of cerebral infarction.ConclusionThe simultaneous occurrence of membranous nephropathy and anti-GBM disease is extremely rare. The correct diagnosis of membranous nephropathy with anti-GBM relies on a combination of renal biopsy findings and serological testing. Early diagnosis is needed to improve the renal dysfunction.

Haemoptysis in a stable kidney transplant patient previously seropositive for anti-GBM and ANCA glomerulonephritis.

Haemoptysis in a stable kidney transplant patient previously seropositive for anti-GBM and ANCA glomerulonephritis.

353 Diagnostic Conundrum: Drug-Induced Interstitial Nephritis, Atypical Anti-GBM or Fibrillary Glomerulonephritis?

353 Diagnostic Conundrum: Drug-Induced Interstitial Nephritis, Atypical Anti-GBM or Fibrillary Glomerulonephritis?

Short-chain fatty acids ameliorate experimental anti-glomerular basement membrane disease

BackgroundShort-chain fatty acids (SCFAs), as the link between gut microbiota and the immune system, had been reported to be protective in many autoimmune diseases by the modulation of T cell differentiation. The pathogenic role of autoreactive Th1 and Th17 cells and the protective role of Treg cells in the pathogenesis of anti-GBM disease have been fully demonstrated. Thus, the present study aimed to investigate the therapeutic effects of SCFAs in a rat model of anti-GBM disease. Materials and methodsExperimental anti-GBM disease was constructed by immunizing Wistar Kyoto rats with a nephrogenic T cell epitope α3127–148, and intervened by sodium acetate, sodium propionate, or sodium butyrate, 150 mM in the drinking water from day 0 to 42. Kidney injury was accessed by the biochemical analyzer, immunofluorescence, and immunohistochemistry. Antibody response was detected by ELISA. T cell clustering and proliferation were detected by flow cytometry. Human kidney 2 (HK2) cells were stimulated in vitro and cytokines were assessed by quantitative real-time PCR. ResultsTreatment with sodium acetate, sodium propionate, or sodium butyrate ameliorated the severity of kidney impairment in rats with anti-GBM glomerulonephritis. In the sodium butyrate-treated rats, the urinary protein, serum creatinine, and blood urea nitrogen levels were significantly lower; the percentage of crescent formation in glomeruli was significantly reduced; and the kidneys showed reduced IgG deposition, complement activation, T cell, and macrophage infiltration as well as the level of circulating antibodies against anti-α3(IV)NC1. The treatment of sodium butyrate reduced the α3127–148-specific T cell activation and increased the Treg cells differentiation and the intestinal beneficial bacteria flora. It also alleviated the damage of HK2 cells treated with inflammatory factors and complement. ConclusionTreatment with SCFAs, especially butyrate, alleviated anti-GBM nephritis in rat model, indicating its potential therapeutic effects in clinical usage.

Laminin-521: a novel target for pathogenic autoantibodies in anti–glomerular basement membrane disease

Anti-glomerular basement membrane (anti-GBM) disease is typically characterized by autoimmunity against the α3 chain of type IV collagen. Rarely, circulating autoantibodies are not detected. These atypical cases follow a more indolent clinical course, and underlying mechanisms, including alternative target antigens, require investigation. In this issue of Kidney International, Kuang etal. describe a case of anti-GBM disease with autoantibodies against the GBM component laminin-521 and demonstrate that laminin-521 is pathogenic in a rat model of anti-GBM glomerulonephritis.

Heparanase-2 protein and peptides have a protective effect on experimental glomerulonephritis and diabetic nephropathy.

Introduction: The endothelial glycocalyx degrading enzyme heparanase-1 (HPSE1) is a major contributor to kidney diseases, such as glomerulonephritis and diabetic nephropathy. Therefore, inhibition of HPSE1 could be an interesting therapeutic strategy to treat glomerular diseases. A possible HPSE1 inhibitor is heparanase-2 (HPSE2) because HPSE2 is a structural homolog of HPSE1 without enzymatic activity. The importance of HPSE2 has been recently demonstrated in HPSE2-deficient mice, since these mice developed albuminuria and died within a few months after birth. We postulate that inhibition of HPSE1 activity by HPSE2 is a promising therapeutic strategy to target albuminuria and resulting renal failure. Methods: First, we evaluated the regulation of HPSE2 expression in anti-GBM and LPS-induced glomerulonephritis, streptozotocin-induced diabetic nephropathy, and adriamycin nephropathy by qPCR and ELISA. Second, we measured the HPSE1 inhibiting capacity of HPSE2 protein and 30 different HPSE2 peptides and assessed their therapeutic potential in both experimental glomerulonephritis and diabetic nephropathy using kidney function and cortical mRNA expression of HPSE1 and cytokines as outcome parameters. Results: HPSE2 expression was downregulated under inflammatory and diabetic conditions, whereas this effect on HPSE2 expression was absent with HPSE1 inhibition and in HPSE1-deficient mice. Both HPSE2 protein and a mixture of the three most potent HPSE1 inhibitory HPSE2 peptides could prevent LPS and streptozotocin induced kidney injury. Discussion: Taken together, our data suggest a protective effect of HPSE2 in (experimental) glomerular diseases and support the therapeutic potential of HPSE2 as HPSE1 inhibitor in glomerular diseases.

Double-Positive Anti-Glomerular Basement Membrane Antibody and Myeloperoxidase Antineutrophil Cytoplasmic Autoantibody-Associated Glomerulonephritis Post COVID-19 mRNA vaccine: A Case Series of 4 Patients.

Vaccines remain central to the management of COVID-19 pandemic, including the need for repeat doses of vaccines to boost immunity. There has been an accumulating case count of glomerulopathies temporally associated with COVID-19 vaccination. This case series presents 4 patients who developed double-positive anti-glomerular basement membrane antibody (anti-GBM) and myeloperoxidase (MPO) antineutrophil cytoplasmic autoantibody (ANCA)-associated glomerulonephritis after COVID-19 mRNA vaccination. This report contributes to our collective knowledge about the pathophysiology and clinical outcomes associated with this rare complication. Four patients developed nephritic syndrome within 1 to 6 weeks after receiving a COVID-19 mRNA vaccine (3 post Pfizer-BioNTech and 1 post Moderna vaccination). Three of the 4 patients also had hemoptysis. Three of the 4 patients had double-positive serology, whereas the fourth patient had renal biopsy findings consistent with double-positive disease, although anti-GBM serology was negative. All patients had renal biopsy findings consistent with double-positive anti-GBM and ANCA-associated glomerulonephritis. All 4 patients were treated with pulse steroids, cyclophosphamide, and plasmapheresis. Of the 4 patients, 1 demonstrated complete remission, 2 remained dialysis-dependent, and the fourth is deceased. Of the 2 patients who received repeat vaccination with COVID-19 mRNA vaccine, 1 patient had second serologic flare of anti-GBM in response to the vaccine. This case series reinforces growing evidence that COVID-19 mRNA vaccine-induced glomerulonephritis is a rare but real phenomenon. Dual ANCA and anti-GBM nephritis can present after the first dose of COVID-19 mRNA vaccine or after several administrations of the vaccine. We are the first to report cases of double-positive MPO ANCA and anti-GBM nephritis after Pfizer-BioNTech vaccination. To our knowledge, we are also the first to report outcomes of repeat COVID-19 vaccination in patients with de novo flare of ANCA and anti-GBM nephritis temporally associated with COVID-19 vaccination.

Axl regulated survival/proliferation network and its therapeutic intervention in mouse models of glomerulonephritis

BackgroundLupus nephritis (LN) is the most common and serious complication of systemic lupus erythematosus (SLE). LN pathogenesis is not fully understood. Axl receptor tyrosine kinase is upregulated and contributes to the pathogenic progress in LN. We have reported that Axl disruption attenuates nephritis development in mice.MethodsIn this study, we analyzed the gene expression profiles with RNA-seq using renal cortical samples from nephritic mice. Axl-KO mice were bred onto a B6.lpr spontaneous lupus background, and renal disease development was followed and compared to the Axl-sufficient B6.lpr mice. Finally, anti-glomerular basement membrane (anti-GBM) Ab-induced nephritic mice were treated with Axl small molecule inhibitor, R428, at different stages of nephritis development. Blood urine nitrogen levels and renal pathologies were evaluated.ResultsTranscriptome analysis revealed that renal Axl activation contributed to cell proliferation, survival, and motility through regulation of the Akt, c-Jun, and actin pathways. Spontaneous lupus-prone B6.lpr mice with Axl deficiency showed significantly reduced kidney damages and decreased T cell infiltration compared to the renal damage and T cell infiltration in Axl-sufficient B6.lpr mice. The improved kidney function was independent of autoAb production. Moreover, R428 significantly reduced anti-GBM glomerulonephritis at different stages of GN development compared to the untreated nephritic control mice. R428 administration reduced inflammatory cytokine (IL-6) production, T cell infiltration, and nephritis disease activity.ConclusionsResults from this study emphasize the important role of Axl signaling in LN and highlight Axl as an attractive target in LN.

Anti-glomerular basement membrane disease: Treatment outcome of cyclophosphamide vs. rituximab induction therapy regimen.

To study the clinical profile of anti-glomerular basement membrane (anti-GBM) disease and its outcome with two different treatment regimens comprising either cyclophosphamide (CYC) or rituximab (RTX). A retrospective analysis of anti-GBM crescentic glomerulonephritis patients admitted to our hospital over 5 years. 14 patients were diagnosed with anti-GBM crescentic glomerulonephritis. The mean duration of symptoms was 3.6±1.9 weeks. All patients presented with rapidly progressive glomerulonephritis (RPGN). Five (35.7%) patients had concomitant urinary tract infection (UTI), 2 (14.3% had underlying type 2 diabetes mellitus, 5 (35.7%) patients also had positive anti-neutrophil cytoplasmic antibodies (ANCA), and 9 (64.3%) were dialysis-dependent at presentation. Four (28.6%) patients developed diffuse alveolar hemorrhage (DAH). All patients received baseline corticosteroids, and 7 (50%) patients also received plasmapheresis. Nine (64.3%) patients were treated with CYC, and 3 (21.4%) patients received RTX. In the CYC arm, 2 (28.6%) patients died, 3 had end-stage kidney disease (ESKD) at 3 months, and 2 had chronic kidney disease (CKD) stage III at 3 months of follow-up. Two patients were lost to follow-up. In the RTX arm, all 3 patients survived with no incidence of DAH, 1patient each had ESKD and CKD stage III, and 1 dialysis-dependent patient achieved normal kidney function at the end of 3 months. Most patients presented late with dialysis-dependent renal failure, and many had concomitant UTI. Concomitant infection causes diagnostic confusion with RPGN and DAH, which delays diagnosis and treatment. RTX as an alternative to CYC in addition to baseline corticosteroids and/or plasmapheresis and is associated with favorable outcomes.

Clinicopathological characteristics and outcome predictors of anti-glomerular basement membrane glomerulonephritis

Objective To explore the clinicopathological features of anti-glomerular basement membrane (anti-GBM) glomerulonephritis (anti-GBM-GN) and the prognostic values of clinical and laboratory indicators at diagnosis on renal and patient survival. Methods A total of 76 patients (34 males and 42 females) with anti-GBM-GN who were hospitalized in the First Affiliated Hospital of Nanjing Medical University between January 2010 and June 2021 were included in this study. The baseline clinical features, histopathological data from renal biopsies, and predictors of renal and patient survival were retrospectively analyzed. Results Among the 76 patients, the median serum creatinine at diagnosis was 618.0 (350.98, 888.25) μmol/L and the median estimated glomerular filtration rate (eGFR) was 6.62 (4.39, 14.41) mL/min. Of these 76 patients, 55 (72.4%) received initial kidney replacement therapy (KRT) and 39 (51.3%) received plasma exchange or double-filtered plasmapheresis (DFPP). During a median follow-up duration of 28.5 (6.0, 71.8) months, 53 (69.7%) patients progressed to kidney failure with replacement therapy (KFRT) and received maintenance dialysis. Initial KRT (HR = 3.48, 95% CI = 1.22–9.97, p = 0.020) was a significant risk factor for renal survival. During the follow-up, 49 (64.5%) of 76 patients survived. Age (≥60 years, HR = 4.13, 95% CI = 1.65–10.38, p = 0.003) and initial KRT (HR = 2.87, 95% CI = 1.01–8.14, p = 0.047) were predictive of patient survival. Conclusions Among patients with anti-GBM-GN, initial KRT at presentation was predictive of KFRT while older age and initial KRT were associated with higher all-cause mortality.

Clinical and pathological features of anti-glomerular basement membrane disease associated with membranous nephropathy: an observational study

To investigate the clinical manifestations, pathological features, pathogenesis, treatment, and prognosis of anti-glomerular basement membrane (anti-GBM) disease with membranous nephropathy (MN). Seven patients with anti-GBM disease and concurrent MN were enrolled in this study. Control subjects included 13 patients with anti-GBM glomerulonephritis (GN) and 6 with anti-GBM disease and concurrent anti-neutrophil cytoplasmic antibodies-associated disease (anti-GBM + ANCA). Laboratory tests and pathological information were analyzed before immunosuppressive therapy or plasmapheresis administration. Prognosis was assessed in continuous follow-up. In the anti-GBM + MN group, 28.57% of patients exhibited acute kidney disease, lower than that in the anti-GBM GN group (84.62%, p = .022). None of the anti-GBM + MN or + ANCA patients exhibited hemoptysis, but 15.4% of anti-GBM GN patients did, with no significant difference (p = .720). Only 14.3% of anti-GBM + MN patients had crescentic GN. The proportion of necrosis averaged 29.0% in the anti-GBM + MN group. Survival curve analysis revealed that renal outcomes in the anti-GBM + MN group were better than those in the anti-GBM GN group (p = .019). Patients with both anti-GBM disease and MN showed atypical anti-GBM GN. They had a lower proportion of glomerular crescents and a better renal function prognosis than patients with classical anti-GBM GN. To improve renal recovery, early identification and treatment of anti-GBM disease associated with MN is needed.

Clinical features and prognosis of MPO-ANCA and anti-GBM double-seropositive patients.

Several lines of evidence implicate that there are distinct differences between patients with myeloperoxidase (MPO)-antineutrophil cytoplasmic antibody (ANCA) and anti-glomerular basement membrane (GBM) antibody double-seropositive patients (DPPs) and single-positive patients. Hence, we conducted a retrospective study from a single center in China to analyze the clinical and pathological features, and prognosis of DPPs. 109 patients with MPO-ANCA-associated vasculitis (MPO-AAV), 20 DPPs and 23 patients diagnosed with anti-GBM disease from a large center in China were included in this study. The ratio of patients with renal biopsy in three groups were 100%, 50% and 100%, respectively. Their clinical and pathological characteristics, and outcomes were analyzed. The intensity of immune deposits in the kidney at diagnosis was detected by immunofluorescence (IF). Furthermore, multivariate Cox hazard model analysis was used to assess the clinical and histological predictors of end-stage renal disease (ESRD) and death for DPPs. In our study, we found that patients in the DPPs group were older than the other two groups (p = 0.007, MPO-AAV vs. DPPs; p < 0.001, DPPs vs. anti-GBM). The DPPs group had a higher value of serum creatinine (p = 0.041) and lower estimated glomerular filtration rate (eGFR) (p = 0.032) compared with MPO-AAV patients. On the contrary, the DPPs group had a lower serum creatinine (p = 0.003) compared with patients with anti-GBM group. The proportion of patients with cardiac system involvement in the DPPs group was higher than anti-GBM patients (p = 0.014). Cellular crescents could be generally observed in renal biopsy of DPPs and patients with anti-GBM glomerulonephritis. In addition, Bowman's capsule rupture was more common in DPPs than MPO-AAV patients (p = 0.001). MPO-AAV had a better renal and overall survival outcome than DPPs (p < 0.001). There was no significant difference of renal and overall survival outcome between DPPs and patients with anti-GBM disease. The incidence of ESRD in DPPs was negatively associated with lymphocyte count (HR 0.153, 95% CI 0.027 to 0.872, p = 0.034) and eGFR (HR 0.847, 95% CI 0.726 to 0.989, p = 0.036). Elevated serum creatinine was confirmed as a risk factor of both renal (HR 1.003, 95% CI 1.000 to 1.005, p = 0.019) and patient survival in DPPs (HR1.461, 95% CI 1.050 to 2.033, p = 0.024). In summary, compared with anti-GBM disease, DPPs tended to involve multi-organ damage rather than limited to the kidney. It is highlighted that serologic DPPs have a worse renal and patient prognosis than MPO-AAV. Moreover, we found that the risk factors of renal survival of DPPs include low lymphocyte count, elevated serum creatinine and reduced eGFR, and serum creatinine can predict patient survival.

Inhibition of the chemokine signal regulator FROUNT by disulfiram ameliorates crescentic glomerulonephritis

Activated monocytes/macrophages promote glomerular injury, including crescent formation, in anti-glomerular basement membrane (GBM) glomerulonephritis. Disulfiram, an alcohol-aversion drug, inhibits monocyte/macrophage migration by inhibiting FROUNT, a cytosolic protein that enhances chemokine receptor signaling. Our study found that disulfiram at a human equivalent dose successfully blocked albuminuria and crescent formation with podocyte loss, and later stage kidney fibrotic lesions, in a rat model of anti-GBM glomerulonephritis. A disulfiram derivative, DSF-41, with more potent FROUNT inhibition activity, inhibited glomerulonephritis at a lower dose than disulfiram. Disulfiram markedly reduced the number of monocytes or macrophages at the early stage of glomerulonephritis and that of CD3+ and CD8+ lymphocytes at the established stage. Impaired pseudopodia formation was observed in the glomerular monocytes/macrophages of the disulfiram group; consistent with the invitro observation that disulfiram blocked chemokine-dependent pseudopodia formation and chemotaxis of bone marrow-derived monocytes/macrophages. Furthermore, disulfiram suppressed macrophage activation as revealed by reduced expression of inflammatory cytokines and chemokines (TNF-α, CCL2, and CXCL9) and reduced CD86 and MHC class II expressions in monocytes/macrophages during glomerulonephritis. The dramatic reduction in monocyte/macrophage number might have resulted from disulfiram suppression of both the chemotactic response of monocytes/macrophages and their subsequent activation to produce cytokines and chemokines, which further recruit monocytes. Additionally, FROUNT was expressed in CD68+ monocytes/macrophages infiltrating the crescentic glomeruli in human anti-GBM glomerulonephritis. Thus, disulfiram can be a highly effective and safe drug for the treatment of glomerulonephritis by blocking the chemotactic responses of monocytes/macrophages and their activation status in the glomerulus.

Acquired aplastic anemia complicated with anti-glomerular basement membrane disease successfully treated with immunosuppressive therapy: a case report

BackgroundAplastic anemia (AA) is a rare but fatal disorder characterized by pancytopenia due to bone marrow hypoplasia. Anti-glomerular basement membrane disease (anti-GBM disease) is an immune complex small-vessel vasculitis that presents as rapidly progressive glomerulonephritis and/or pulmonary hemorrhage. Although both involve autoreactive T cells that are partially triggered by human leukocyte antigen (HLA)-DR15, there have been no reports of their co-existence and the treatment strategy is not well understood.Case presentationA 67-year-old woman presented with fever, malaise, and acute kidney injury with proteinuria and hematuria requiring hemodialysis. She was diagnosed with anti-GBM antibody disease based on high serum anti-GBM antibody titer and crescentic glomerulonephritis on a renal biopsy. Pulse administration of methylprednisolone (MP), oral prednisolone (PSL), and plasmapheresis were performed. Only 2 weeks after the diagnosis of anti-GBM disease, the patient developed pancytopenia requiring frequent blood transfusions. The blood cell count did not recover even 1 month after discontinuing the drugs that could cause pancytopenia. Bone marrow examination showed hypocellularity without abnormal infiltrates or fibrosis, which led to the diagnosis of severe acquired AA. Further HLA phenotyping revealed that she had HLA-DR15. Increased dose of PSL with the secondary MP pulse and the addition of cyclosporine improved pancytopenia. Although she remained dialysis-dependent, anti-GBM disease and pancytopenia did not recur for more than 2 years.ConclusionsWe report the first case of acquired AA complicated with anti-GBM disease in an elderly woman with HLA-DR15, which was successfully treated with immunosuppressive therapy (IST). This report is valuable not only because it shows they may co-occur, but also because it provides a therapeutic option for this complex condition. It was also suggested that pancytopenia in patients with anti-GBM disease recalls serious hematologic diseases including AA that require immediate treatment based on bone marrow examination.

Glucocorticoids Inhibit EGFR Signaling Activation in Podocytes in Anti-GBM Crescentic Glomerulonephritis.

Glucocorticoids are commonly used to treat anti-GBM crescentic glomerulonephritis, however, the mechanism underlying its therapeutic effectiveness is not completely understood. Since podocyte EGFR/STAT3 signaling is known to mediate the development of anti-GBM glomerulonephritis, we investigated the effect of glucocorticoids on EGFR/STAT3 signaling in podocytes. We found that the levels of phosphorylated (activated) EGFR and STAT3 in podocytes were markedly elevated in anti-GBM patients without glucocorticoids treatment, but were normalized in patients with glucocorticoids treatment. In a rat model of anti-GBM glomerulonephritis, glucocorticoids treatment significantly attenuated the proteinuria, crescent formation, parietal epithelial cell (PEC) activation and proliferation, accompanied by elimination of podocyte EGFR/STAT3 signaling activation. In cultured podocytes, glucocorticoids were found to inhibit HB-EGF-induced EGFR and STAT3 activation. The conditioned medium from podocytes treated with HB-EGF in the absence but not presence of glucocorticoids was capable of activating Notch signaling (which is known to be involved in PEC proliferation and crescent formation) and enhancing proliferative activity in primary PECs, suggesting that glucocorticoids prevent podocytes from producing secreted factors that cause PEC proliferation and crescent formation. Furthermore, we found that glucocorticoids can downregulate the expression of EGFR ligands, EGF and HB-EGF, while upregulate the expression of EGFR inhibitor, Gene 33, explaining how glucocorticoids suppress EGFR signaling. Taken together, glucocorticoids exert therapeutic effect on anti-GBM crescentic glomerulonephritis through inhibiting podocyte EGFR/STAT3 signaling and the downstream pathway that leads to PEC proliferation and crescent formation.

Soluble receptor for advanced glycation end products protects from ischemia- and reperfusion-induced acute kidney injury.

ABSTRACTThe full-length receptor for advanced glycation end products (RAGE) is a multiligand pattern recognition receptor. High-mobility group box 1 (HMGB1) is a RAGE ligand of damage-associated molecular patterns that elicits inflammatory reactions. The shedded isoform of RAGE and endogenous secretory RAGE (esRAGE), a splice variant, are soluble isoforms (sRAGE) that act as organ-protective decoys. However, the pathophysiologic roles of RAGE/sRAGE in acute kidney injury (AKI) remain unclear. We found that AKI was more severe, with enhanced renal tubular damage, macrophage infiltration, and fibrosis, in mice lacking both RAGE and sRAGE than in wild-type (WT) control mice. Using murine tubular epithelial cells (TECs), we demonstrated that hypoxia upregulated messenger RNA (mRNA) expression of HMGB1 and tumor necrosis factor α (TNF-α), whereas RAGE and esRAGE expressions were paradoxically decreased. Moreover, the addition of recombinant sRAGE canceled hypoxia-induced inflammation and promoted cell viability in cultured TECs. sRAGE administration prevented renal tubular damage in models of ischemia/reperfusion-induced AKI and of anti-glomerular basement membrane (anti-GBM) glomerulonephritis. These results suggest that sRAGE is a novel therapeutic option for AKI.

The effect of rose hip on experimental anti-GBM glomerulonephritis in systemic lupus erythematosus murine models

Background: Systemic lupus erythematosus (SLE or lupus) is a chronic autoimmune disease with ominous end organ manifestations significantly affecting the kidneys and joints. One of the most frequent manifestations is glomerulonephritis (GN), a renal disease distinguished by inflammation of the glomeruli that often leads to end stage kidney failure. Treatments often have severe side effects. Rose hip (RH) is derived from Rosa canina L. and has been used as a medicinal plant for centuries; it contains numerous beneficial constituents, and has the capacity to counter lipid peroxidation, oxidative stress, and inflammation. Methods: Nephritis was induced in 129/svJ strain mice using anti-glomerular basement membrane antibodies (anti-GBM). The experimental group was fed whole RH preparation (100mg/kg body weight per day) by oral gavage from D5 to D10; the control group was fed the diluent used to dissolve RH (10 mice per group). Mice were sacrificed on D11 and phenotyped for disease. Blood urea nitrogen (BUN) and proteinuria were measured; flow cytometry of kidneys was performed on both groups. Results: RH treatment decreased proteinuria, blood urea nitrogen, CD4+, CD8+, CD11b+Gr-1+ (neutrophil), and CD11b+CD11c+ (myeloid cells) compared with nephritis control. The presence of vitamin C was confirmed. RH largely maintained its total antioxidant capacity and some vitamin C content for 24 hours, as well as at least 7 days after preparation. Conclusion: Our preliminary results confirmed that RH has antioxidative properties, significant anti-inflammatory effects, and may be useful in managing glomerulonephritisKeywords: Rose hip, glomerulonephritis, systemic lupus erythematosus, lupus, proteinuria, blood urea nitrogen, CD4+, CD8+, CD11b+Gr-1+(neutrophil), and CD11b+CD11c+ (myeloid cells)

Regulatory role and mechanisms of myeloid TLR4 in anti-GBM glomerulonephritis

Myeloid cells and TLR4 play a critical role in acute kidney injury. This study investigated the regulatory role and mechanisms of myeloid TLR4 in experimental anti-glomerular basement membrane (GBM) glomerulonephritis (GN). Anti-GBM GN was induced in tlr4flox/flox and tlr4flox/flox−lysM−cre mice by intravenous injection of the sheep anti-mouse GBM antibody. Compared to control mice, conditional disruption of tlr4 from myeloid cells, largely macrophages (> 85%), suppressed glomerular crescent formation and attenuated progressive renal injury by lowering serum creatinine and 24-h urine protein excretion while improving creatinine clearance. Mechanistically, deletion of myeloid tlr4 markedly inhibited renal infiltration of macrophages and T cells and resulted in a shift of infiltrating macrophages from F4/80+iNOS+ M1 to F4/80+CD206+ M2 phenotype and inhibited the upregulation of renal proinflammatory cytokines IL-1β and MCP-1. Importantly, deletion of myeloid tlr4 suppressed T cell-mediated immune injury by shifting Th1 (CD4+IFNγ+) and Th17 (CD4+IL-17a+) to Treg (CD4+CD25+FoxP3+) immune responses. Transcriptome analysis also revealed that disrupted myeloid TLR4 largely downregulated genes involving immune and cytokine-related pathways. Thus, myeloid TLR4 plays a pivotal role in anti-GBM GN by immunological switching from M1 to M2 and from Th1/Th17 to Treg and targeting myeloid TLR4 may be a novel therapeutic strategy for immune-mediated kidney diseases.

A Novel Treatment for Glomerular Disease: Targeting the Activated Macrophage Folate Receptor with a Trojan Horse Therapy in Rats.

Since activated macrophages express a functional folate receptor β (FRβ), targeting this macrophage population with folate-linked drugs could increase selectivity to treat inflammatory diseases. Using a macrophage-mediated anti-glomerular basement membrane (anti-GBM) glomerulonephritis (GN) in WKY rats, we investigated the effect of a novel folic acid-aminopterin (AMT) conjugate (EC2319) designed to intracellularly deliver AMT via the FR. We found that treatment with EC2319 significantly attenuated kidney injury and preserved renal function. Kidney protection with EC2319 was blocked by a folate competitor, indicating that its mechanism of action was specifically FRβ-mediated. Notably, treatment with methotrexate (MTX), another folic acid antagonist related to AMT, did not protect from kidney damage. EC2319 reduced glomerular and interstitial macrophage infiltration and decreased M1 macrophage recruitment but not M2 macrophages. The expression of CCL2 and the pro-fibrotic cytokine TGF-β were also reduced in nephritic glomeruli with EC2319 treatment. In EC2319-treated rats, there was a significant decrease in the deposition of collagens. In nephritic kidneys, FRβ was expressed on periglomerular macrophages and macrophages present in the crescents, but its expression was not observed in normal kidneys. These data indicate that selectively targeting the activated macrophage population could represent a novel means for treating anti-GBM GN and other acute crescentic glomerulonephritis.