Anti-glomerular Basement Membrane Nephritis Research Articles

Atypical Anti-Glomerular Basement Membrane Nephritis: A Case Series From the French Nephropathology Group

Rationale & ObjectiveAtypical anti-glomerular basement membrane (GBM) nephritis is characterized by a bright linear immunoglobulin staining along the GBM by immunofluorescence without a diffuse crescentic glomerulonephritis nor serum anti-GBM antibodies by conventional ELISA. We characterized a series of patients with atypical anti-GBM disease. Study DesignCase series. Setting & ParticipantsPatients were identified by the French Nephropathology Group as having atypical anti-GBM nephritis between 2003 and 2022. FindingsAmong 38 potential cases, 25 were included. 14 (56%) were female and 23 (92%) had hematuria. Median [interquartile range (IQR)] serum creatinine at diagnosis was 150 [102-203] μmol/L and median [IQR] urine protein to creatinine ratio was 2.4 [1.3-5.2] g/g. 9 (36%) patients had endocapillary proliferative glomerulonephritis (GN), 4 (16%) had mesangial proliferative GN, 4 (16%) had membranoproliferative GN, 2 (8%) had pure and focal crescentic GN, 1 (4%) had focal segmental glomerulosclerosis, and 5 had glomeruli that were unremarkable on histopathology. Nine patients (36%) had crescents, involving a median of 9% of glomeruli. Bright linear staining for IgG was seen in 22 cases (88%) and for IgA in 3 cases (12%). The nine patients (38%) who had a monotypic staining pattern tended to be older with less proteinuria and rarely had crescents. Kidney survival rate at one year was 83% and did not appear to be associated with the light chain restriction. LimitationsRetrospective case series with a limited number of biopsies including electron microscopy. ConclusionsCompared to typical anti-GBM disease, atypical anti-GBM nephritis frequently presents with endocapillary or mesangial proliferative glomerulonephritis pattern and appears to have slower disease progression. Further studies are needed to fully characterize its pathophysiology and associated clinical outcomes.

The Characteristics of Concurrent Anti-Glomerular Basement Membrane Nephritis and Membranous Nephropathy

The Characteristics of Concurrent Anti-Glomerular Basement Membrane Nephritis and Membranous Nephropathy

Recurrent atypical antiglomerular basement membrane nephritis in the kidney transplant

Atypical antiglomerular basement membrane (anti-GBM) nephritis can be defined as linear GBM staining for monotypic or polytypic immunoglobulin (Ig) by immunofluorescence (IF) without a diffuse crescentic pattern. We describe the clinicopathologic features of 6 patients (18 biopsies) in this first series of recurrent atypical anti-GBM nephritis after kidney transplantation. Recurrent glomerulonephritis occurred at a mean of 3.8 months posttransplant (range 1-7 months). Three index biopsies were for clinical indication, and 3 were protocol biopsies. Glomerular histologic changes were mild, with 2 showing segmental endocapillary hypercellularity, 1 focal glomerular microangiopathy, and the others no significant glomerular histologic changes. All 6 allografts showed monotypic linear glomerular Ig staining by IF: IgG kappa (n = 2), IgG lambda, IgA kappa, IgA lambda, and IgM lambda. Follow-up biopsies were available for 5 patients and showed similar histologic and IF findings without evidence of significant progression. No patients had detectable serum anti-GBM antibody or monoclonal proteins. The mean serum creatinine level on follow-up (24-62 months posttransplant) was 1.8 (range 0.93-2.77) mg/dL; no grafts were lost to recurrent disease. This series demonstrates that monotypic atypical anti-GBM recurs in the allograft and supports the idea that this disease is due to a circulating monoclonal protein.

Atypical form of Goodpasture's disease.

Goodpasture's disease and anti-glomerular basement membrane nephritis (anti-GBM nephritis) are rare autoimmune small vessel vasculitis predominantly affecting young men. Goodpasture's disease plays an important part in differential diagnosis of pulmonary - renal syndrome. The evidence of circulating autoantibodies, a typical histological appearance of the kidney biopsy with finding of the crescent glomerulonephritis and clinical presentation of nephritic syndrome play an important role in diagnosis. Our case report describes a case of a young male with anti-GBM nephritis that presents as rapidly progressive glomerulonephritis (RPGN) with progression to dialysis-dependent renal failure. The atypical sign of the case was development of nephrotic syndrome with volume-dependent hypertension. The case was complicated by heparin-induced thrombocytopenia. During combined immunosuppressive therapy with plasmapheresis, the condition of the patient has stabilized. However, renal function did not recover. This previously fatal disease has nowadays a very good survival rate because of immunosuppresion therapy, plasmapheresis and hemodialysis.

The Characteristics of Concurrent Anti-Glomerular Basement Membrane Nephritis and Membranous Nephropathy

The Characteristics of Concurrent Anti-Glomerular Basement Membrane Nephritis and Membranous Nephropathy

#5592 THE SODIUM PHOSPHATE COTRANSPORTER NAPI-IIB IS UPREGULATED AND EXPRESSED DE NOVO IN KIDNEYS OF PATIENTS WITH CHRONIC KIDNEYS DISEASE

Abstract Background and Aims Renal reabsorption of phosphate is mediated by 3 main transporters located in the luminal brush border membrane of the proximal tubule, namely NaPi-IIa (SLC34A1), NaPi-IIc (SLC34A3), and Pit2 (SLC20A2). The expression of all three proteins has been shown to be reduced in animal models of kidney disease [1]. Recently, we demonstrated that NaPi-IIb, a paralogue of the SLC34 subfamily that is mostly expressed in small intestine and lungs, is also expressed in the loop of Henle. Its mRNA expression is enhanced in rodent models of kidney injury. However, the expression of NaPi-IIb has not been characterized in humans and it is unknown whether NaPi-IIb is also upregulated in chronic kidney disease (CKD). Method In this study, we examined the localization of NaPi-IIa, IIb, and IIc in kidneys of control healthy individuals (kidney donors) (eGFR: 111.6 ± 22.9 ml/min/1.73m2) and patients with diabetic nephropathy (eGFR: 31.9 ± 7.7 ml/min/1.73m2), anti-glomerular basement membrane nephritis (anti-GMB) (eGFR: 27.2 ± 22.6 ml/min/1.73m2), and hypertensive nephropathy (eGFR: 31.5 ± 5.3 ml/min/1.73m2) by immunofluorescence. Moreover, we analyzed data from various transcriptome data bases from healthy individuals and patients with CKD. Results In kidneys from healthy donors, NaPi-IIb staining was restricted to thin and thick limbs of the loop of Henle, while AQP1 was observed in proximal tubules and descending thin limbs. NaPi-IIc was abundantly found in proximal tubule cells. In biopsies from patients, NaPi-IIb signal was also found in addition to thin and thick limbs in cells of the collecting duct and in many proximal tubules. In contrast, the staining of NaPi-IIc was reduced in all groups of patients with CKD. RNA expression data from the European Renal cDNA Bank (ERCB) confirmed our immunofluorescence findings. SLC34A2 (NaPi-IIb) mRNA was progressively more expressed in kidneys of patients with kidney disease of tubulointerstitial origin from CKD stages 1 to 5, while it was strongly upregulated from stage 4 onwards in CKD of glomerular origin. Single cell RNA sequencing data of patients with acute kidney injury and CKD [2] showed elevation of SLC34A2 expression in injured thick ascending limb, degenerative proximal tubule cells (14x higher, adj. p≪0.0001) (de novo expression), and descending thin limb (3.7x higher, adj. p≪0.0001). SLC34A1 (NaPi-IIa) expression levels were reduced in whole kidneys (ERCB data) and SLC34A1 and SLC34A3 expression also decreased in proximal tubule cells of patients with CKD. Conclusion The phosphate transporter NaPi-IIb is highly upregulated in kidneys from patients with various etiologies of CKD and its expression spreads to proximal tubule and collecting duct. In contrast, the expression of the main physiological phosphate transporters NaPi-IIa and NaPi-IIc is reduced in CKD. These findings may have implications for the development and maintenance of hyperphosphatemia in CKD patients and limit the use of specific NaPi-IIa and/or NaPi-IIc inhibitors in patients with CKD.

Clinicopathological and immunological features of new onset kidney disease: a rare event after SARS-CoV-2 vaccination.

The onset of various kidney diseases has been reported after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. However, detailed clinical and pathological features are lacking. We screened and analyzed patients with newly diagnosed kidney diseases after inactivated SARS-CoV-2 vaccination in Peking University First Hospital from January 2021 to August 2021, and compared them with the reported cases in the literature. We obtained samples of blood, urine and renal biopsy tissues. Clinical and laboratory information, as well as light microscopy, immunostaining and ultrastructural observations, were described. The SARS-CoV-2 spike protein and nucleoprotein were stained using the immunofluorescence technique in the kidney biopsy samples. SARS-CoV-2 specific antibodies were tested using magnetic particle chemiluminescence immunoassay. The study group included 17 patients with a range of conditions including immune-complex-mediated kidney diseases (IgA nephropathy, membranous nephropathy and lupus nephritis), podocytopathy (minimal change disease and focal segmental glomerulosclerosis) and others (antineutrophil-cytoplasmic-antibody-associated vasculitis, anti-glomerular basement membrane nephritis, acute tubulointerstitial nephritis and thrombotic microangiopathy). Seven patients (41.18%) developed renal disease after the first dose and ten (58.82%) after the second dose. The kidney disease spectrum as well as clinicopathological features are similar across different types of SARS-CoV-2 vaccines. We found no definitive evidence of SARS-CoV-2 spike protein or nucleoprotein deposition in the kidney biopsy samples. Seropositive markers implicated abnormal immune responses in predisposed individuals. Treatment and follow-up (median=86 days) showed that biopsy diagnosis informed treatment and prognosis in all patients. In conclusion, we observed various kidney diseases following SARS-CoV-2 vaccine administration, which show a high consistency across different types of SARS-CoV-2 vaccines. Our findings provide evidence against direct vaccine protein deposition as the major pathomechanism, but implicate abnormal immune responses in predisposed individuals. These findings expand our understanding of SARS-CoV-2 vaccine renal safety.

Effects of an immunosuppressive agent on the anti-glomerular basement membrane nephritis model rat

Effects of an immunosuppressive agent on the anti-glomerular basement membrane nephritis model rat

Type IV Collagen and SOX9 Are Molecular Targets of BET Inhibition in Experimental Glomerulosclerosis.

Progressive glomerulonephritis (GN) is characterized by an excessive accumulation of extracellular (ECM) proteins, mainly type IV collagen (COLIV), in the glomerulus leading to glomerulosclerosis. The current therapeutic approach to GN is suboptimal. Epigenetic drugs could be novel therapeutic options for human disease. Among these drugs, bromodomain and extra-terminal domain (BET) inhibitors (iBETs) have shown beneficial effects in experimental kidney disease and fibrotic disorders. Sex-determining region Y-box 9 (SOX9) is a transcription factor involved in regulating proliferation, migration, and regeneration, but its role in kidney fibrosis is still unclear. We investigated whether iBETs could regulate ECM accumulation in experimental GN and evaluated the role of SOX9 in this process. For this purpose, we tested the iBET JQ1 in mice with anti-glomerular basement membrane nephritis induced by nephrotoxic serum (NTS). In NTS-injected mice, JQ1 treatment reduced glomerular ECM deposition, mainly by inhibiting glomerular COLIV accumulation and Col4a3 gene overexpression. Moreover, chromatin immunoprecipitation assays demonstrated that JQ1 inhibited the recruitment and binding of BRD4 to the Col4a3 promoter and reduced its transcription. Active SOX9 was found in the nuclei of glomerular cells of NTS-injured kidneys, mainly in COLIV-stained regions. JQ1 treatment blocked SOX9 nuclear translocation in injured kidneys. Moreover, in vitro JQ1 blocked TGF-β1-induced SOX9 activation and ECM production in cultured mesangial cells. Additionally, SOX9 gene silencing inhibited ECM production, including COLIV production. Our results demonstrated that JQ1 inhibited SOX9/COLIV, to reduce experimental glomerulosclerosis, supporting further research of iBET as a potential therapeutic option in progressive glomerulosclerosis.

Hydroxychloroquine suppresses anti-GBM nephritis via inhibition of JNK/p38 MAPK signaling.

Anti-glomerular basement membrane (anti-GBM) nephritis, characterized by glomerular crescent formation, requires early treatment because of poor prognosis. Hydroxychloroquine (HCQ) is an antimalarial drug with known immunomodulatory, anti-inflammatory, and autophagy inhibitory effects; it is recognized in the treatment of autoimmune diseases such as systemic lupus erythematosus. However, its effect on anti-GBM nephritis remains unknown. In this study, we investigated the effect of HCQ on anti-GBM nephritis in rats. Seven-weeks-old male WKY rats were administered anti-GBM serum to induce anti-GBM nephritis. Either HCQ or vehicle control was administered from day 0 to day 7 after the induction of nephritis. Renal function was assessed by measuring serum creatinine, proteinuria, and hematuria. Renal histological changes were assessed by PAS staining and Masson trichrome staining, and infiltration of macrophages was assessed by ED-1 staining. Mitogen-activated protein kinase (MAPK) was evaluated by western blotting, while chemokine and inflammatory cytokines were evaluated by enzyme-linked immunosorbent assay using urine sample. HCQ treatment suppressed the decline in renal function. Histologically, extracapillary and intracapillary proliferations were observed from day 1, while fibrinoid necrosis and ED-1 positive cells were observed from day 3. Rats with anti-GBM nephritis showed high levels of monocyte chemotactic protein-1 and tumor necrosis factor-α. These changes were significantly suppressed following HCQ treatment. In addition, HCQ suppressed JNK/p38 MAPK phosphorylation. HCQ attenuates anti-GBM nephritis by exerting its anti-inflammatory effects via the inhibition of JNK/p38 MAPK activation, indicating its therapeutic potential against anti-GBM nephritis.

Retinal drusen in glomerulonephritis with or without immune deposits suggest systemic complement activation in disease pathogenesis

Retinal drusen are characteristic of macular degeneration and complement activation, but also occur in C3, lupus and IgA nephropathy. This cross-sectional observational study compared drusen counts in different forms of glomerulonephritis. Consecutive individuals with glomerulonephritis attending a general renal or transplant clinic underwent retinal imaging with a non-mydriatic camera. Drusen were counted in deidentified images by trained graders, compared with matched hospital patients, and correlated with clinical features. Eighty-four individuals with glomerulonephritis had a mean drusen count of 10 ± 27 compared with 3 ± 8 in hospital controls (p = 0.007). Fourteen individuals with glomerulonephritis (17%) and 4 hospital controls (4/49, 8%) had increased drusen counts (≥ 10) (p = 0.20). Increased drusen counts ≥ 10 were present in 13 (13/63, 21%) of those with glomerulonephritis and immune deposits [membranous (n = 8), antiglomerular basement membrane nephritis (n = 6), FSGS (n = 49)], and one of the 21 (5%) with glomerulonephritis without immune deposits [ANCA-associated (n = 15), minimal change disease (n = 6)]. In antibody-mediated glomerulonephritis (n = 14), mean drusen counts were 2 ± 3 in individuals with normal kidney function, 16 ± 41 with impaired function and 5 ± 7 with kidney failure . Mean counts were 24 ± 56 in individuals with glomerular IgG deposits and 1 ± 1 in those without (p = 0.76), and 23 ± 60 with complement deposits and 4 ± 8 in those without. Drusen counts were also less in immunosuppressed individuals (p = 0.049). The demonstration of retinal drusen in some forms of glomerulonephritis is consistent with systemic complement activation, and suggests that treatment targeting the complement pathways is worthwhile.

Epigenetic Modulation of Gremlin-1/NOTCH Pathway in Experimental Crescentic Immune-Mediated Glomerulonephritis.

Crescentic glomerulonephritis is a devastating autoimmune disease that without early and properly treatment may rapidly progress to end-stage renal disease and death. Current immunosuppressive treatment provides limited efficacy and an important burden of adverse events. Epigenetic drugs are a source of novel therapeutic tools. Among them, bromodomain and extraterminal domain (BET) inhibitors (iBETs) block the interaction between bromodomains and acetylated proteins, including histones and transcription factors. iBETs have demonstrated protective effects on malignancy, inflammatory disorders and experimental kidney disease. Recently, Gremlin-1 was proposed as a urinary biomarker of disease progression in human anti-neutrophil cytoplasmic antibody (ANCA)-associated crescentic glomerulonephritis. We have now evaluated whether iBETs could regulate Gremlin-1 in experimental anti-glomerular basement membrane nephritis induced by nephrotoxic serum (NTS) in mice, a model resembling human crescentic glomerulonephritis. In NTS-injected mice, the iBET JQ1 inhibited renal Gremlin-1 overexpression and diminished glomerular damage, restoring podocyte numbers. Chromatin immunoprecipitation assay demonstrated BRD4 enrichment of the Grem-1 gene promoter in injured kidneys, consistent with Gremlin-1 epigenetic regulation. Moreover, JQ1 blocked BRD4 binding and inhibited Grem-1 gene transcription. The beneficial effect of iBETs was also mediated by modulation of NOTCH pathway. JQ1 inhibited the gene expression of the NOTCH effectors Hes-1 and Hey-1 in NTS-injured kidneys. Our results further support the role for epigenetic drugs, such as iBETs, in the treatment of rapidly progressive crescentic glomerulonephritis.

Successful treatment with intense immunosuppressive therapy in an initially 100% crescentic lesion of anti-GBM nephritis

Anti-glomerular basement membrane (anti-GBM) nephritis is uncommon glomerular disease caused by autoantibodies targeting the capillary beds of the kidney. The clinical presentation of the disease is a variable nephritic syndrome, rapidly progressing to glomerulonephritis. Treatment outcomes are dependent on predictors at first diagnosis. We presented a case of 58-year-old man who did not have underlying disease presented with marked abdominal distension and acute kidney injury. He had no evidence of chronic renal disease before admission however, laboratory test showed microscopic haematuria (RBC 30-50 per high-powered field), proteinuria (2.9 g/d), and renal failure (serum creatinine 610 µmol/L) compatible with rapidly progressive glomerulonephritis; hence, a renal biopsy was conducted. The pathology showed 100% crescentic glomerulonephritis with IgG deposits in a linear pattern at the GBM. The initial serum anti-GBM titre was 105.59 RU/mL. This patient had poor renal prognosis factors for treatment response. After a discussion regarding treatment option with the patient, we decided to give intensive immunosuppressive therapy and plasmapheresis due to his good baseline functional status. The patient achieved partial remission and is not dialysis dependent. In conclusion, despite a poor renal prognosis with 100% crescents and serum creatinine ≥ 600 µmol/L, the treated patient had a good survival status and did not become dialysis-dependent. However, immunosuppressive treatment should be performed along with careful monitoring for infection to avoid infection-related morbidity and mortality.

Kidney complications following COVID-19 vaccination; a review of the literature

Objective: To review the reported cases of kidney injury following vaccination for coronavirus disease 2019 (COVID-19) with a focus on renal pathology. Methods: We searched for case reports of kidney complications after COVID-19 vaccine in PubMed. Results: A total of 36 articles including 49 case reports were reported. These included minimal change disease (n=17), IgA nephropathy (IgAN) (n=15), IgA nephritis/vasculitis (n=5), ANCA glomerulonephritis/vasculitis (n=5), anti-glomerular basement membrane (GBM) nephritis (n=2), and 1 case of each granulomatous vasculitis, acute tubulointerstitial nephritis, scleroderma renal crisis, IgG4-related disease nephritis, and primary membranous nephropathy (MN). Conclusion: We give an overview of the reported cases of post-COVID-19 renal complications. Further investigations of the underlying pathogenesis of post-COVID-19 vaccination renal adverse events are required, as prompt workup, diagnosis, and treatment of patients with renal complications may lead to complete remission, prevent kidney failure, and long-term complications such as end-stage renal disease (ESRD). However, these complications are overall extremely rare and the benefit of vaccination outweighs the potential risks.

The development of rapidly progressive glomerulonephritis associated with both antineutrophil cytoplasmic antibody-associated vasculitis and anti-glomerular basement membrane nephritis in the course of nontuberculous mycobacterium infection: a case report

BackgroundAntineutrophil cytoplasmic antibodies (ANCA) and Anti-glomerular basement membrane (GBM) antibodies often induce rapidly progressive glomerulonephritis (RPGN). Some reports have demonstrated RPGN with the sequential appearance of ANCA then anti-GBM antibodies, suggesting that ANCA may induce the development of anti-GBM antibodies. Whereas, many reports have shown that the development of ANCA is associated with various infectious diseases, such as non-tuberculous mycobacterial infection.Case presentationA 65-year-old woman with pulmonary non-tuberculous mycobacterial (NTM) infection was monitored without treatment. One year later, serum myeloperoxidase (MPO)- ANCA were elevated (14.1 U/mL (normal value < 3.0 U/ml)). A high fever and RPGN appeared 1 year later, and serum MPO-ANCAs were 94.1 U/mL. Anti-GBM antibodies were also detected. A renal biopsy revealed crescentic glomerulonephritis with linear deposits of IgG and C3c along the GBM and interstitial inflammation with endarteritis of arterioles. The diagnosis was RPGN associated with anti-GBM nephritis and ANCA-associated vasculitis.ConclusionThis report shows that preceding NTM infection may have induced ANCA and anti-GBM antibodies and caused the development of RPGN.

(Pro)renin receptor promotes crescent formation via the ERK1/2 and Wnt/β-catenin pathways in glomerulonephritis.

(Pro)renin receptor [(P)RR] has multiple functions, but its regulation and role in the pathogenesis in glomerulonephritis (GN) are poorly defined. The aims of the present study were to determine the effects of direct renin inhibition (DRI) and demonstrate the role of (P)RR on the progression of crescentic GN. The anti-glomerular basement membrane nephritis rat model developed progressive proteinuria (83.64 ± 10.49 mg/day) and glomerular crescent formation (percent glomerular crescent: 62.1 ± 2.3%) accompanied by increased macrophage infiltration and glomerular expression of monocyte chemoattractant protein (MCP)-1, (P)RR, phospho-extracellular signal-regulated kinase (ERK)1/2, Wnt4, and active β-catenin. Treatment with DRI ameliorated proteinuria (20.33 ± 5.88 mg/day) and markedly reduced glomerular crescent formation (20.9 ± 2.6%), induction of macrophage infiltration, (P)RR, phospho-ERK1/2, Wnt4, and active β-catenin. Furthermore, primary cultured parietal epithelial cells stimulated by recombinant prorenin showed significant increases in cell proliferation. Notably, while the ERK1/2 inhibitor PD98059 or (P)RR-specific siRNA treatment abolished the elevation in cell proliferation, DRI treatment did not abrogate this elevation. Moreover, cultured mesangial cells showed an increase in prorenin-induced MCP-1 expression. Interestingly, (P)RR or Wnt4-specific siRNA treatment or the β-catenin antagonist XAV939 inhibited the elevation of MCP-1 expression, whereas DRI did not. These results suggest that (P)RR regulates glomerular crescent formation via the ERK1/2 signaling and Wnt/β-catenin pathways during the course of anti-glomerular basement membrane nephritis and that DRI mitigates the progression of crescentic GN through the reduction of (P)RR expression but not inhibition of prorenin binding to (P)RR.

Concurrent Anti-glomerular Basement Membrane Nephritis and IgA Nephropathy.

Anti–glomerular basement membrane (GBM) nephritis is characterized by circulating anti-GBM antibodies and crescentic glomerulonephritis (GN) with deposition of IgG along the GBM. In a limited number of cases, glomerular immune complexes have been identified in anti-GBM nephritis. A 38-year-old female presented azotemia, hematuria, and proteinuria without any pulmonary symptoms. A renal biopsy showed crescentic GN with linear IgG deposition along the GBM and mesangial IgA deposition. The patient was diagnosed as concurrent anti-GBM nephritis and IgA nephropathy. Therapies with pulse methylprednisolone and cyclophosphamide administration were effective. Concurrent cases of both anti-GBM nephritis and IgA nephropathy are rare among cases of anti-GBM diseases with deposition of immune complexes. This rare case of concurrent anti-GBM nephritis and IgA nephropathy with literature review is noteworthy.

Renal transplantation in patients with Alport syndrome: patient selection, outcomes, and donor evaluation

Alport syndrome is an inherited disorder of basement membrane collagen IV that frequently results in end-stage renal disease. Patients with Alport syndrome who undergo renal transplantation have generally excellent outcomes. Posttransplant antiglomerular basement membrane nephritis is a rare complication of renal transplantation for Alport syndrome. Because Alport syndrome is a genetic disorder, potential related donors must be carefully evaluated in order to minimize harm.

Characterization of Glomerular Sox9+ Cells in Anti-Glomerular Basement Membrane Nephritis in the Rat

Mechanisms of glomerular crescent formation and podocyte repair processes are still unclear. Therefore, we investigated the expression of the transcription factor Sox9 as a potential marker of a subpopulation of parietal epithelial cells (PECs) with potential regenerative properties. Glomerular Sox9 expression was characterized in detail in a rat anti-glomerular basement membrane (GBM) nephritis model using immunofluorescence and confocal laser scanning microscopy. In healthy kidneys Sox9 is expressed in a subpopulation of PECs restricted to approximately 20% to 50% of PEC nuclei and was highly conserved in all investigated species. During rat anti-GBM nephritis the number of glomerular Sox9+ cells increased and was associated with proliferation activity. In nephritic glomeruli Sox9 expression was not restricted to Bowman's capsule lining but was also found on cells of the glomerular tuft. Nearly all Sox9+ cells also expressed the PEC marker Pax8, whereas endothelial cells, mesangial cells, macrophages, and T lymphocytes lacked Sox9 expression. At the margins of crescents Sox9+/Pax8+ cells additionally expressed podocyte markers. In contrast, in sclerotic lesions a minority of Sox9+/Pax8+ cells expressed the myofibroblast marker α-smooth muscle actin. In glomerular Sox9+ cells Jagged 1 was up-regulated. During anti-GBM nephritis Sox9+ PECs proliferate and migrate onto the glomerular tuft. Future studies are needed to confirm the origin of Sox9+ cells from PECs and differentiation in both podocytes and/or myofibroblasts.

Therapeutic Mechanism of Glucocorticoids on Cellular Crescent Formation in Patients With Antiglomerular Basement Membrane Disease

BackgroundThis study aimed to explore the therapeutic mechanism of glucocorticoids (GCs) in antiglomerular basement membrane disease. Materials and MethodsThirty-four patients with biopsy-proven antiglomerular basement membrane nephritis were divided into the following 2 groups: group 1 (patients treated with GCs, n = 22) and group 2 (patients who were not treated with GCs, n = 12). The expression of parietal epithelial cells (PECs), activated PECs and glucocorticoid receptors (GRs) was examined quantitatively and compared between the 2 groups. Correlations between GR expression in glomeruli and patients’ clinicopathological indices were also analyzed. ResultsCompared with patients in group 2, patients in group 1 showed lower levels of serum creatinine (SCr) (P = 0.03), average cellular crescent percentage (P = 0.005) and macrophages infiltrating in renal interstitium (P = 0.03). PECs (P = 0.007) and activated PECs (P = 0.03) were strongly detected in the cellular components of classic crescents, and both were significantly reduced in group 1 compared to group 2. GR expression either in glomeruli (P = 0.01) or interstitium (P = 0.009) was lower in group 1 after GCs treatment than in group 2. Additionally, GR expression in glomeruli was strongly correlated with renal function (SCr: r = 0.45, P = 0.009; eGFR: r = −0.35, P = 0.046), the proportion of cellular crescents (r = 0.67, P < 0.001), PECs (r = 0.64, P < 0.001) and activated PECs (r = 0.72, P < 0.001), and the degree of interstitial (r = 0.50, P = 0.004) and glomerular (r = 0.49, P = 0.007) macrophage infiltration. ConclusionsGCs might exert their therapeutic effects via inhibiting the activation and proliferation of PECs, as well as macrophage infiltration, which could contribute to crescent formation and determine renal survival. GRs are involved in this process as well.