Crescentic Glomerulonephritis: an update on Pauci-immune and Anti-GBM diseases

Three Diseases Mediated by Different Immunopathologic Mechanisms-ANCA-Associated Vasculitis, Anti-Glomerular Basement Membrane Disease, and Immune Complex-Mediated Glomerulonephritis-A Common Clinical and Histopathologic Picture: Rapidly Progressive Crescentic Glomerulonephritis

Immune mechanisms play an important role in the pathogenesis of glomerulonephritis (GN), with autoimmunity being the main underlying pathogenetic process of both primary and secondary GN. We present three autoimmune diseases mediated by different autoimmune mechanisms: glomerulonephritis in vasculitis mediated by anti-neutrophil cytoplasmic antibodies (ANCAs), glomerulonephritis mediated by anti-glomerular basement membrane antibodies (anti-GBM antibodies), and immune complex-mediated glomerulonephritis. Some of these diseases represent a common clinical and histopathologic scenario, namely rapidly progressive crescentic glomerulonephritis. This is a severe illness requiring complex therapy, with the main role being played by therapy aimed at targeting immune mechanisms. In the absence of immune therapy, the crescents, the characteristic histopathologic lesions of this common presentation, progress toward fibrosis, which is accompanied by end-stage renal disease (ESRD). The fact that three diseases mediated by different immunopathologic mechanisms have a common clinical and histopathologic picture reveals the complexity of the relationship between immunopathologic mechanisms and their clinical expression. Whereas most glomerular diseases progress by a slow process of sclerosis and fibrosis, the glomerular diseases accompanied by glomerular crescent formation can progress, if untreated, in a couple of months into whole-nephron glomerulosclerosis and fibrosis. The outcome of different immune processes in a common clinical and histopathologic phenotype reveals the complexity of the relationship of the kidney with the immune system. The aim of this review is to present different immune processes that lead to a common clinical and histopathologic phenotype, such as rapidly progressive crescentic glomerulonephritis.

Crescentic Glomerulonephritis Due to Enterococcal Endocarditis

Glomerulonephritis following an enterococcal endocarditis is an extremely rare and life-threatening condition. We present the case of a 71-year-old patient with rapidly progressive glomerulonephritis following enterococcal endocarditis after surgical replacement of the aortic valve. The combination of antibiotic therapy, corticosteroid therapy and haemodialysis led to an improvement in renal function; however, the severity of cardiac deterioration resulted in a fatal outcome.

The Diagnostic and Therapeutic Dilemma of Seronegative Pulmonary Renal Syndrome: A Case Report

Pulmonary renal syndrome (PRS) is a combination of rapid progressive glomerulonephritis (RPGN) and diffuse alveolar hemorrhage (DAH) caused by a variety of immunological and non-immunological etiologies. The difficulty in identifying and reporting seronegative PRS cases could be attributed to the lack of specific immunological markers. Thus, we report a rare case of a 13-year-old boy who was initially diagnosed with idiopathic pauci-immune pulmonary capillaritis (IPIPC). A year later, his condition became complicated, and was referred for further workup. During his hospital stay, he underwent a renal biopsy that showed stage II membranous nephropathy (MN). He tested negative for immunological markers and a diagnosis of seronegative PRS was established. He responded well to the immunosuppression therapy with monthly follow-ups. As in our patient, PRS may manifest as acute renal failure symptoms and non-specific respiratory symptoms that require extensive workup. The severity of the disease is inferred from the renal function at the time of presentation. Management involves immunosuppression and treatment of the underlying condition, with dialysis dependency occurring in a significant percentage of patients and a high mortality rate, especially in critically ill and older patients. In conclusion, timely diagnosis and treatment are essential given the condition's rapid progression and high mortality rate.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Pulmonary renal syndrome: a clinical review

The term "pulmonary renal syndrome" describes a clinical syndrome which is characterised by the presence of both diffuse alveolar haemorrhage and glomerulonephritis. It encompasses a group of diseases with distinctive clinical and radiological manifestations, as well as different pathophysiological processes. The most common diseases implicated are anti-neutrophil cytoplasm antibodies (ANCA)-positive small vessel vasculitis and anti-glomerular basement membrane (anti-GBM) disease. Prompt recognition is required as respiratory failure and end-stage renal failure can rapidly occur. Treatment includes a combination of glucocorticoids, immunosuppression, plasmapheresis and supportive measures. The use of targeted treatments has significantly reduced mortality. Thus, an understanding of pulmonary renal syndrome is essential for the respiratory physician.

Clinical and histopathological study of renal biopsy in Nepalese children: A single center experience

BACKGROUND

Glomerular diseases are important causes of morbidity and mortality among children in developing countries. Renal biopsy is the gold standard for determining histological diagnosis, prognosis, and therapy options. This study aimed to investigate the clinical, histopathological, and direct immunofluorescence findings of renal biopsy results in Nepalese children under 18 years old.

METHODS

In this retrospective cross-sectional study, the available data from children who had undergone kidney biopsy between 2016 and the end of 2020 were evaluated. Demographic data, indications of biopsy, histopathologic findings, and direct immunofluorescence findings were collected and presented.

RESULTS

The mean age of the patients was 12.14 ± 4.07 years. Male/female ratio was 1:1. The majority of biopsy cases were aged between 11-15 years of age. The most common indication for biopsy in children was nephrotic syndrome (68.25%). Lupus nephritis with 28 cases (22.22%) had the highest frequency in overall renal biopsies. Minimal change disease (MCD) with 22 cases (17.46%) followed by Ig A nephropathy with 16 cases (12.69%) were the most frequent primary glomerulonephritis. Lupus nephritis showed full house positivity, and MCD showed full house negativity in all Direct immunofluorescence (DIF) parameters, whereas immunoglobulin A nephropathy showed 100% positivity in Ig A in DIF.

CONCLUSIONS

Nephrotic syndrome was the most common indication for renal biopsy. The most common primary glomerulonephritis was MCD, while secondary glomerulonephritis was lupus nephritis. Clinical data, light microscopy, and direct DIF played an integral role in the overall final diagnosis.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSION

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.

A Case of Paediatric Anti-Glomerular Basement Membrane Disease Associated with Thrombotic Thrombocytopenic Purpura

Anti-GBM disease is a rare vasculitis that causes rapid progressive glomerulonephritis and pulmonary haemorrhage. It is usually an adult diagnosis with isolated paediatric cases reported. Thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic microangiopathy mainly affecting adults that causes multiorgan ischaemia, microangiopathic haemolytic anaemia, and thrombocytopenia. We present the first paediatric case of concurrent anti-GBM disease and TTP. A 14-year-old boy presented with acute kidney failure and severe pulmonary haemorrhage due to anti-GBM disease, confirmed on auto-antibody testing. There was thrombocytopenia and moderately low ADAMTS13 activity suggestive of TTP. The renal prognosis was poor with a need for dialysis. He was severely unwell with pulmonary haemorrhages requiring the use of extracorporeal membrane oxygenation (ECMO). His disease was treated with corticosteroids, plasma exchange (PEX), rituximab, and cyclophosphamide, resulting in remission. Anti-GBM disease is rare in children but should be considered in those presenting with acute kidney injury, particularly where there has been exposure to pulmonary irritants. An aggressive presentation warrants aggressive treatment with methylprednisolone, PEX, and cyclophosphamide. Rituximab may benefit patients that have concurrent TTP. TTP may exacerbate pulmonary disease, but complete respiratory recovery is possible. Disease relapse is rare in the paediatric age group, and these patients are candidates for kidney transplantation.

Clinical impact of urinary CD11b and CD163 on the renal outcomes of anti-neutrophil cytoplasmic antibody-associated glomerulonephritis

BACKGROUND

The detection of leukocyte-derived CD11b (α subunit of integrin Mac-1) and CD163 (scavenger receptor) in urine may reflect renal inflammation in antineutrophil cytoplasmic antibody-associated glomerulonephritis (ANCA-GN). The objective of this study was to evaluate the clinical significance of urinary CD11b (U-CD11b) and CD163 (U-CD163) in ANCA-GN.

METHODS

U-CD11b and U-CD163 were examined using enzyme-linked immunosorbent assay in ANCA-GN urine samples from our institutional cohort (n = 88) and a nationwide cohort (n = 138), and their association with renal histology was subsequently analyzed. Logistic regression analyses were performed on a nationwide ANCA cohort to determine the associations of the two urinary molecules with renal remission failure at 6 months or with yearly estimated glomerular filtration rate (eGFR) slope over a 24-month observation period.

RESULTS

U-CD11b and U-CD163 were significantly associated with cellular crescent formation and leukocyte accumulation in glomerular crescents. With regard to interstitial inflammation, both levels of U-CD11b and U-CD163 at diagnosis remarkably increased in ANCA-GN compared with the levels observed in nonglomerular kidney disorders including nephrosclerosis, immunoglobulin G4-related disease and tubulointerstitial nephritis; however, the presence of U-CD11b alone was significantly correlated with tubulointerstitial leukocyte infiltrates. Although neither U-CD11b nor U-CD163 at diagnosis was associated with remission failure at 6 months, multivariate analysis demonstrated that the baseline U-CD11b levels were significantly associated with the increase in eGFR following immunosuppressive therapy.

CONCLUSIONS

Although both U-CD11b and U-CD163 reflect renal leukocyte accumulation, U-CD11b at diagnosis provides additional clinical value by predicting the recovery rate after the treatment of ANCA-GN.

Peptidylarginine deiminases 2 and 4 modulate innate and adaptive immune responses in TLR-7-dependent lupus

The peptidylarginine deiminases PAD2 and PAD4 are implicated in the pathogenesis of several autoimmune diseases. PAD4 may be pathogenic in systemic lupus erythematosus (SLE) through its role in neutrophil extracellular trap (NET) formation that promotes autoantigen externalization, immune dysregulation, and organ damage. The role of this enzyme in mouse models of autoimmunity remains unclear, as pan-PAD chemical inhibitors improve clinical phenotype, whereas PAD4-KO models have given conflicting results. The role of PAD2 in SLE has not been investigated. The differential roles of PAD2 and PAD4 in TLR-7-dependent lupus autoimmunity were examined. Padi4-/- displayed decreased autoantibodies, type I IFN responses, immune cell activation, vascular dysfunction, and NET immunogenicity. Padi2-/- mice showed abrogation of Th subset polarization, with some disease manifestations reduced compared with WT but to a lesser extent than Padi4-/- mice. RNA sequencing analysis revealed distinct modulation of immune-related pathways in PAD-KO lymphoid organs. Human T cells express both PADs and, when exposed to either PAD2 or PAD4 inhibitors, displayed abrogation of Th1 polarization. These results suggest that targeting PAD2 and/or PAD4 activity modulates dysregulated TLR-7-dependent immune responses in lupus through differential effects of innate and adaptive immunity. Compounds that target PADs may have potential therapeutic roles in T cell-mediated diseases.

Kidney disease models: tools to identify mechanisms and potential therapeutic targets

Acute kidney injury (AKI) and chronic kidney disease (CKD) are worldwide public health problems affecting millions of people and have rapidly increased in prevalence in recent years. Due to the multiple causes of renal failure, many animal models have been developed to advance our understanding of human nephropathy. Among these experimental models, rodents have been extensively used to enable mechanistic understanding of kidney disease induction and progression, as well as to identify potential targets for therapy. In this review, we discuss AKI models induced by surgical operation and drugs or toxins, as well as a variety of CKD models (mainly genetically modified mouse models). Results from recent and ongoing clinical trials and conceptual advances derived from animal models are also explored.

C3 deposits worsens the prognosis in type iii extracapillary glomerulonephritis

INTRODUCTION

Type iii extracapillary glomerulonephritis (PEGN) is a common cause of rapidly progressive glomerulonephritis and it is usually associated with circulating anti-neutrophil cytoplasmic antibodies (ANCAs). Recent evidence points to complement activation as an important factor in the pathogenesis of PEGN. The aim of the present study was to assess the value of C3 deposits in the prognosis of PEGN.

METHODS

All patients diagnosed of PEGN from 1995 to 2015 (n=72) were included in this study. Progression of renal disease in patients with positive staining for C3 by immunofluorescence was compared with those with negative staining. Mean follow up was 73 months. Progression to end-stage renal disease in relation to clinical and histological variables was analyzed.

RESULTS

Positive staining for C3 was observed in 22 out of the 72 patients (30.5%). At the time of diagnosis, patients with C3 deposits had higher serum creatinine concentration than those without C3 staining (5.00 vs. 3.85mg/dl, P=0.050). Renal survival at 10 years was 36.9% in patients with positive C3 staining vs. 64.4% in patients with negative staining (P=0.005). Mortality at 10 years was higher in patients with C3 deposits than in patients without deposits (77 vs. 49.3%).

CONCLUSIONS

Thus, our study shows that PEGN with deposits of C3 is associated with worse renal prognosis and greater mortality. These results would support the hypothesis that activation of the alternative pathway complement may play an important role in the generation of renal injury associated with PEGN.

C3 glomerulonephritis with a severe crescentic phenotype

BACKGROUND

C3 glomerulopathy (C3G) is rare type of glomerulonephritis resulting from the glomerular deposition of C3 due to dysregulation of the alternative pathway of complement. It is further subdivided into C3 glomerulonephritis (C3GN) and dense deposit disease (DDD), depending on the ultrastructural features. C3GN usually presents with a membranoproliferative pattern of injury. Crescents may or may not be present. However, we have noted a severe necrotizing and crescentic glomerulonephritis in a small subset of C3GN patients.

CASE DIAGNOSIS/TREATMENT

We present the clinical features, kidney biopsy findings, complement evaluation, treatment, and follow-up of four C3GN patients. We also compare the findings with four DDD patients with a severe necrotizing and crescentic glomerulonephritis. The patients were young and presented with hematuria and proteinuria. The biopsy was remarkable for the large number of crescents, in association with bright glomerular staining for C3. The patients were treated with steroids/immunosuppressive drugs. Three of the 4 C3GN patients and 2 of the 4 DDD patients showed stable renal function at follow-up. We find remarkable similarities between our C3GN patients with crescents and the previously described entity of juvenile acute nonproliferative glomerulonephritis.

CONCLUSIONS

To summarize, C3G with a severe crescentic phenotype is rare, affects children and young adults, and has a variable response to steroid and immunosuppressive treatment. It is important to recognize this rare cause of crescentic glomerulonephritis so that appropriate evaluation and treatment can be carried out.

Crescentic glomerulonephritis: data from the Spanish Glomerulonephritis Registry

BACKGROUND

Crescentic glomerulonephritis (CGN) is a histological finding that implies rapid deterioration of renal function and can be related to different diseases, such as type 1 or anti-glomerular basement membrane antibody (Goodpasture) disease, type 2 or immune complex CGN and type 3 or pauci-immune disease.

AIM

The present study describes CGN and its characteristics based on the data from the Spanish Glomerulonephritis Registry.

METHODS

An analysis was made of all native renal biopsies obtained from patients during 1994-2013 and classified as CGN. A patient epidemiological and clinical data questionnaire was completed by the 120 centres involved.

RESULTS

A total of 21,774 biopsies was performed, of which 2089 (8.1%) corresponded to CGN (211 type 1, 177 type 2 and 1701 type 3). Renal function was poorer in type 1 compared with types 2 and 3, and proteinuria was higher in type 2 compared to types 1 and 3. Patients diagnosed with CGN type 3 were older than those with types 1 and 2, but less hypertensive than the type 2 patients. No differences in the urine test findings were found between types 1 and 2. Microhaematuria was the most frequent feature in general, as well as in type 3 compared with types 1 and 2. The main indication for biopsy was acute renal injury. Age was the only difference between type 1 patients with and without alveolar haemorrhage (53 [33-67] vs 64 [46-73], P = 0.008).

CONCLUSION

Although classified as the same entity, the different types of CGN have different features that must be taken into account.

Rapidly progressive glomerulonephritis due to coexistent anti-glomerular basement membrane disease and fibrillary glomerulonephritis

Anti-glomerular basement membrane (anti-GBM) disease is a major cause of rapidly progressive glomerulonephritis (RPGN). On the other hand, fibrillary glomerulonephritis (GN) typically presents as proteinuria, hematuria and renal insufficiency, but rarely as RPGN. Without electron microscopy, the diagnosis of fibrillary GN can be missed. We report a 68-year-old white woman who presented with RPGN with kidney biopsy demonstrating diffuse crescentic GN on light microscopy. By immunofluorescence, there was bright linear staining of the GBMs and smudgy mesangial staining for immunoglobulin G, C3, and kappa and lambda light chain. Electron microscopy revealed fibrillary deposits in the GBM and mesangium. A serum test for anti-GBM antibody was positive. To our knowledge, this is the first report of coexistence of fibrillary GN in a patient with anti-GBM disease. Electron microscopy is critical to identify the coexistence of other GN in patients presenting with crescentic GN.

Pauci-Immune Crescentic Glomerulonephritis: An ANCA-Associated Vasculitis

Rapidly progressive glomerulonephritis (RPGN) is a syndrome signified by a precipitous loss of renal function, with features of glomerulonephritis including dysmorphic erythrocyturia and glomerular proteinuria. RPGN is associated with extensive crescent formation, and, thus, the clinical term RPGN is often used interchangeably with the pathologic term crescentic glomerulonephritis (CGN). From an immunopathologic standpoint, primary RPGN is divided into pauci-immune GN (PICG), anti-GBM GN, and immune complex GN. PICG, the most common etiology of primary RPGN, refers to a necrotizing glomerulonephritis with few or no immune deposits by immunofluorescence (IF) or electron microscopy (EM). In most patients, pauci-immune CGN is a component of a systemic small vessel vasculitis such as granulomatosis with polyangiitis (GPA). Approximately 90% of patients with PICG have circulating ANCA antibodies, leading to the nomenclature ANCA-associated vasculitis (AAV). Recent research has identified several other antibodies associated with PICG, which is now understood to be a complex spectrum of disease with considerable overlap in terms of clinical phenotype and outcomes. In addition, several genetic and environmental factors have recently been implicated in the pathogenesis of this disorder. With new prognostic classifications, enhanced understanding of immunopathologic mechanisms, and novel treatment paradigms, clinical and experimental interest in PICG remains high.

Pauci-immune glomerulonephritis in children: a clinicopathologic study of 21 patients

BACKGROUND

Pauci-immune glomerulonephritis (GN) represents a severe form of glomerular injury and is the most common cause of crescentic GN in adults. To date, the clinicopathologic features of pauci-immune GN are not well characterized in the pediatric population.

METHODS

Twenty-six biopsies from 21 pediatric patients with pauci-immune GN were identified retrospectively from the pathology archives of the University of Chicago (biopsy incidence 5 % among pediatric patients).

RESULTS

There was distinct female predominance (2.5:1) among the patient cohort. Serologic studies identified anti-neutrophil cytoplasmic antibodies (ANCA) in 85 % of patients, and 80 % had systemic manifestations of vasculitis. The median estimated glomerular filtration rate (eGFR) at presentation was 43 ml/min/1.73 m(2). Based on a previously proposed classification of ANCA-associated GN, we identified a spectrum of injury, including crescentic (n = 9), focal (n = 7), mixed (n = 5) and sclerotic GN (n = 5). Necrotizing arteritis was identified in a minority of patients (n = 3). The majority of those patients for whom data were available had been treated with cyclophosphamide and corticosteroids, with or without rituximab. Of the 21 pediatric patients, 58 % had developed chronic kidney disease at follow-up (eGFR <90 ml/min/1.73 m(2)), of whom 85 % of those had crescentic, mixed or sclerotic GN.

CONCLUSION

Pediatric patients with pauci-immune GN are similar to their adult counterparts in terms of clinical manifestations and histopathologic findings. Among the 21 patients in our study, those with focal GN had the best outcomes while patients with crescentic, mixed or sclerotic GN overwhelmingly had a poor long-term outcome for kidney function.

Urological manifestations and treatment of the primary systemic vasculitides

The primary systemic vasculitides (PSV) are a group of rare inflammatory disorders affecting blood vessels of varying size and multiple organs. Urological manifestations of PSV are uncommon. Testicular vasculitis is the most commonly reported finding and is associated with Polyarteritis Nodosa (PAN), Henoch-Schönlein Purpura (HSP), anti-neutrophil cytoplasm antibody associated Vasculitides (AAV), Giant Cell Arteritis (GCA) and Kawasaki disease. Prostatic vasculitis has been reported in association with GCA and AAV. Ureteric involvement has been noted in PAN, HSP and AAV. Other urogenital manifestations of PSV include genital ulceration and bladder dysfunction in Behçets Disease and haematuria which is commonly seen in many of the PSV. Finally, therapies used to treat the PSV, especially cyclophosphamide, are associated with urological side-effects including haemorrhagic cystitis and urothelial malignancy. The aim of this review is to examine how the urological system is involved in the PSV. Each PSV is examined in turn, with a brief clinical description of the disease followed by a description of the urological manifestations and management. Identification of urological manifestations of PSV is important as in many cases symptoms may improve with immunosuppressive therapy, avoiding the need for invasive surgery. Additionally, patients who present with isolated urogenital PSV are at higher risk of developing subsequent systemic vasculitis and will need to be followed up closely.

Update on endocarditis-associated glomerulonephritis

Glomerulonephritis (GN) due to infective endocarditis (IE) is well documented, but most available data are based on old autopsy series. To update information, we now present the largest biopsy-based clinicopathologic series on IE-associated GN. The study group included 49 patients (male-to-female ratio of 3.5:1) with a mean age of 48 years. The most common presenting feature was acute kidney injury. Over half of the patients had no known prior cardiac abnormality. However, the most common comorbidities were cardiac valve disease (30%), intravenous drug use (29%), hepatitis C (20%), and diabetes (18%). The cardiac valve infected was tricuspid in 43%, mitral in 33%, and aortic in 29% of patients. The two most common infective bacteria were Staphylococcus (53%) and Streptococcus (23%). Hypocomplementemia was found in 56% of patients tested and ANCA antibody in 28%. The most common biopsy finding was necrotizing and crescentic GN (53%), followed by endocapillary proliferative GN (37%). C3 deposition was prominent in all cases, whereas IgG deposition was seen in <30% of cases. Most patients had immune deposits detectable by electron microscopy. Thus, IE-associated GN most commonly presents with AKI and complicates staphylococcal tricuspid valve infection. Contrary to infection-associated glomerulonephritis in general, the most common pattern of glomerular injury in IE-associated glomerulonephritis was necrotizing and crescentic glomerulonephritis.

M2 macrophage infiltrates in the early stages of ANCA-associated pauci-immune necrotizing GN

BACKGROUND AND OBJECTIVES

This study examined kidney biopsies with focal segmental glomerular fibrinoid necrosis to identify early features of pauci-immune necrotizing GN and the primary effector cells mediating initial capillary injury.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Seventeen consecutive kidney biopsies with focal pauci-immune necrotizing GN, obtained over a 6-year period (2007-2012), were studied. Neutrophils and CD68(+), CD163(+), CD3(+), CD56(+), and CD20(+) cells were scored in paraffin sections counterstained with periodic acid-Schiff. Electron microscopy was performed in 15 of 17 biopsies and additional examples of pauci-immune necrotizing GN (n=25). Biopsies with thin basement membrane nephropathy (n=5) served as immunohistologic normal controls.

RESULTS

Biopsies with pauci-immune necrotizing GN had a mean of 10 (range=3-25) normal-appearing glomeruli, a mean of 2 (range=1-5) glomeruli with segmental fibrinoid necrosis, and a mean of 2 (range=1-11) glomeruli with cellular crescents. CD68(+) and CD163(+) macrophages predominated at sites of fibrinoid necrosis in pauci-immune necrotizing GN, exceeding the quantity of neutrophils and T cells (mean scores [SD]=2.5 [0.7] and 2.2 [0.75] versus 0.6 [0.5] and 0.1 [0.3], respectively; P<0.001). B and natural killer cells were rare. Normal-appearing glomeruli in pauci-immune necrotizing GN had significantly more CD68(+) and CD163(+) macrophages than the controls (CD68(+), 0.9 [0.3] versus 0.4 [0.3]; CD163(+), 1 [0.4] versus 0.4 [0.3]; P<0.001). The quantity of other glomerular infiltrates did not differ from controls. The serum creatinine level at biopsy correlated with the glomerular CD68 and neutrophil scores (r=0.74 and r=0.71, respectively; P=0.001) but did not correlate with the extent of fibrinoid necrosis (r=0.36). Macrophages were localized at minute perforations and attenuations of the capillary basement membrane by electron microscopy.

CONCLUSIONS

Early pauci-immune necrotizing GN is characterized by a selective localization of CD163(+) M2 macrophages at sites of glomerular fibrinoid necrosis and in normal-appearing glomeruli. These observations indicate that alternatively activated macrophages are positioned as potential effectors of glomerular injury in the early stages of pauci-immune necrotizing GN and may be potential targets for therapeutic intervention.

Goodpasture's Syndrome and p-ANCA Associated Vasculitis in a Patient of Silicosiderosis: An Unusual Association

Introduction. Goodpasture's syndrome is a rare clinical entity and is characterized by circulating autoantibodies which are principally directed against the glomerular/alveolar basement membrane. The etiology of Goodpasture's syndrome is still unknown. Lung involvement occurs as a result of lung injury and the exposure of new epitopes to the immune system. Recently, several studies have suggested the role of silica as one of etiological factors in ANCA associated vasculitis and glomerulonephritis. Materials and Methods. We present a case of a 40-year-old welder with silicosiderosis, who developed anti-GBM disease with p-ANCA positivity. Case Report. Patient presented to an emergency with gradually increasing breathlessness along with renal failure and died after short hospital stay. Autopsy pathology findings revealed crescentic glomerulonephritis with linear glomerular basement membrane antibody deposition, splenic vasculitis, pulmonary haemorrhage, and pulmonary silicosiderosis. Conclusion. This case reinforces the role of environmental triggers like exposure to silica, metal dust, and tobacco in pathogenesis of Goodpasture's syndrome and p-ANCA associated vasculitis.

TNF receptors: signaling pathways and contribution to renal dysfunction

Tumor necrosis factor (TNF), initially reported to induce tumor cell apoptosis and cachexia, is now considered a central mediator of a broad range of biological activities from cell proliferation, cell death and differentiation to induction of inflammation and immune modulation. TNF exerts its biological responses via interaction with two cell surface receptors: TNFR1 and TNFR2. (TNFRs). These receptors trigger shared and distinct signaling pathways upon TNF binding, which in turn result in cellular outputs that may promote tissue injury on one hand but may also induce protective, beneficial responses. Yet the role of TNF and its receptors specifically in renal disease is still not well understood. This review describes the expression of the TNFRs, the signaling pathways induced by them and the biological responses of TNF and its receptors in various animal models of renal diseases, and discusses the current outcomes from use of TNF biologics and TNF biomarkers in renal disorders.

Maternal, pregnancy and fetal outcomes in de novo anti-glomerular basement membrane antibody disease in pregnancy: a systematic review

Background

Outside of pregnancy, anti-glomerular basement membrane (GBM) antibody disease is associated with significant morbidity and mortality. However, there is limited knowledge regarding de novo anti-GBM disease in pregnancy.

Methods

A systematic review was performed to identify maternal, pregnancy and fetal outcomes in de novo anti-GBM disease in pregnancy. Studies were selected from PubMed, EMBASE, Cochrane Library databases and conference proceedings, without language restriction.

Results

Data from eight patients were derived from seven case reports and one unpublished case. Most (6/8) patients presented after the first trimester. During pregnancy, acute kidney injury (5/8), anemia (5/8), hematuria (8/8) and proteinuria (8/8) were common. When hemodialysis was required antepartum (5/8), renal function recovery to independence of renal replacement was unlikely (2/5). While pulmonary involvement was common (5/8), no permanent damage was reported (0/8). The majority of cases ended in live births (6/8) although prematurity (6/6), intrauterine growth restriction (2/6), small for gestational age (4/6) and complications of prematurity (1/6) were common. When anti-GBM levels were tested in the living newborn, they were detectable (2/5), but no newborn renal or lung disease was reported (0/6). Complications in pregnancy included gestational diabetes (3/8), hyperemesis gravidarum (2/8) and preeclampsia (2/8).

Conclusions

Live births can be achieved in de novo anti-GBM disease in pregnancy, but are commonly associated with adverse maternal, pregnancy and fetal outcomes. Only with awareness of common presentations, and management strategies can outcomes be optimized.

Comparison of double filtration plasmapheresis with immunoadsorption therapy in patients with anti-glomerular basement membrane nephritis

Background

Double filtration plasmapheresis (DFPP) and (IA) are both used to clear antibody. However, the clinical efficacy and safety of DFPP in patients with anti-glomerular basement membrane (anti-GBM) disease are unclear.

Methods

The 28 enrolled patients diagnosed serologically and pathologically with anti-GBM disease from 2003 to 2013 included 16 treated with DFPP and 12 with IA, with all patients administered immunosuppressive agents. DFPP consisted of an EC50W filter for plasma separation and an EC20W filter for plasma fractionation. A double volume of plasma was processed, and each patient received a 30–40 g human albumin supplement during each session. IA consisted of 10 cycles per session, with 8–10 sessions performed daily or every other day and each session regenerating 30–60 L of plasma. Serum anti-GBM antibodies and IgG were measured, and urinary and blood tests were performed, before and after each procedure. Renal function and outcome were determined.

Results

The 28 patients consisted of 13 males and 15 females, of median age 44.5 years (range, 22.5–57 years). Six patients had pulmonary hemorrhage and 18 had serum creatinine concentrations >500 umol/L. The average serum creatinine concentration at early onset of disease was 525 umol/L while the peak concentration was 813 umol/L. All patients showed progressive increases in serum creatinine and required CRRT during the course of disease. Pathological examination showed an average 73.9% of crescents (range, 54.6–95.4%).The clinical and pathological features of the DPPP and IA groups were similar. Efficacy of clearing anti-GBM antibody was similar in the two groups (59.0 vs. 71.2%, P = 1.00), although fewer patients in the DFPP group experienced reduced IgG (62.7 vs. 83.5%, p = 0.002). One patient each had a pulmonary hemorrhage and a subcutaneous hemorrhage during treatment, but there were no other serious complications. At the end of follow-up, patient survival and renal survival were similar in the DFPP and IA groups.

Conclusion

DPPP plus immunosuppressive therapy efficiently and safely removed anti-GBM antibodies. The fewer plasma-associated side effects and reduced loss of IgG suggest that DFPP may be a better treatment choice for anti-GBM disease, especially in patients with insufficient plasma.

An essential role of interleukin-17 receptor signaling in the development of autoimmune glomerulonephritis

In recent years, proinflammatory cytokines in the nephritic kidney appear to contribute to the pathogenesis of AGN. The complex inflammatory cytokine network that drives renal pathology is poorly understood. IL-17, the signature cytokine of Th17 cells, which promotes autoimmune pathology in a variety of settings, is beginning to be identified in acute and chronic kidney diseases as well. However, the role of IL-17-mediated renal damage in the nephritic kidney has not been elucidated. Here, with the use of a murine model of experimental AGN, we showed that IL-17RA signaling is critical for the development of renal pathology. Despite normal systemic autoantibody response and glomerular immune-complex deposition, IL-17RA(-/-) mice exhibit a diminished influx of inflammatory cells and kidney-specific expression of IL-17 target genes correlating with disease resistance in AGN. IL-17 enhanced the production of proinflammatory cytokines and chemokines from tECs. Finally, we were able to show that neutralization of IL-17A ameliorated renal pathology in WT mice following AGN. These results clearly demonstrated that IL-17RA signaling significantly contributes to renal tissue injury in experimental AGN and suggest that blocking IL-17RA may be a promising therapeutic strategy for the treatment of proliferative and crescentic glomerulonephritis.

Glutathione S-transferase Mu 2-transduced mesenchymal stem cells ameliorated anti-glomerular basement membrane antibody-induced glomerulonephritis by inhibiting oxidation and inflammation

INTRODUCTION

Oxidative stress is implicated in tissue inflammation, and plays an important role in the pathogenesis of immune-mediated nephritis. Using the anti-glomerular basement membrane antibody-induced glomerulonephritis (anti-GBM-GN) mouse model, we found that increased expression of glutathione S-transferase Mu 2 (GSTM2) was related to reduced renal damage caused by anti-GBM antibodies. Furthermore, mesenchymal stem cell (MSC)-based therapy has shed light on the treatment of immune-mediated kidney diseases. The aim of this study was to investigate if MSCs could be utilized as vehicles to deliver the GSTM2 gene product into the kidney and to evaluate its potential therapeutic effect on anti-GBM-GN.

METHODS

The human GSTM2 gene (hGSTM2) was transduced into mouse bone marrow-derived MSCs via a lentivirus vector to create a stable cell line (hGSTM2-MSC). The cultured hGSTM2-MSCs were treated with 0.5 mM H2O2, and apoptotic cells were measured by terminal dUTP nick-end labeling (TUNEL) assay. The 129/svj mice, which were challenged with anti-GBM antibodies, were injected with 10⁶ hGSTM2-MSCs via the tail vein. Expression of hGSTM2 and inflammatory cytokines in the kidney was assayed by quantitative PCR and western blotting. Renal function of mice was evaluated by monitoring proteinuria and levels of blood urea nitrogen (BUN), and renal pathological changes were analyzed by histochemistry. Immunohistochemical analysis was performed to measure inflammatory cell infiltration and renal cell apoptosis.

RESULTS

MSCs transduced with hGSTM2 exhibited similar growth and differentiation properties to MSCs. hGSTM2-MSCs persistently expressed hGSTM2 and resisted H2O2-induced apoptosis. Upon injection into 129/svj mice, hGSTM2-MSCs migrated to the kidney and expressed hGSTM2. The anti-GBM-GN mice treated with hGSTM2-MSCs exhibited reduced proteinuria and BUN (58% and 59% reduction, respectively) and ameliorated renal pathological damage, compared with control mice. Mice injected with hGSTM2-MSCs showed alleviated renal inflammatory cell infiltration and reduced expression of chemokine (C-C motif) ligand 2 (CCL2), interleukin (IL)-1β and IL-6 (53%, 46% and 52% reduction, respectively), compared with controls. Moreover, hGSTM2-MSCs increased expression of renal superoxide dismutase and catalase, which may associate with detoxifying reactive oxygen species to prevent oxidative renal damage.

CONCLUSIONS

Our data suggest that the enhanced protective effect of GSTM2-transduced MSCs against anti-GBM-GN might be associated with inhibition of oxidative stress-induced renal cell apoptosis and inflammation, through over-expression of hGSTM2 in mouse kidneys.

Nature and mediators of parietal epithelial cell activation in glomerulonephritides of human and rat

Bowman's capsule parietal epithelial cell activation occurs in several human proliferative glomerulonephritides. The cellular composition of the resulting hyperplastic lesions is controversial, although a population of CD133(+)CD24(+) progenitor cells has been proposed to be a major constituent. Mediator(s) involved in proliferation and migration of progenitor cells into the Bowman's space have been poorly explored. In a series of 36 renal biopsies of patients with proliferative and nonproliferative glomerulopathies, dysregulated CD133(+)CD24(+) progenitor cells of the Bowman's capsule invade the glomerular tuft exclusively in proliferative disorders. Up-regulation of the CXCR4 chemokine receptor on progenitor cells was accompanied by high expression of its ligand, SDF-1, in podocytes. Parietal epithelial cell proliferation might be sustained by increased expression of the angiotensin II (Ang II) type-1 (AT1) receptor. Similar changes of CXCR4, SDF-1, and AT1 receptor expression were found in Munich Wistar Frömter rats with proliferative glomerulonephritis. Moreover, an angiotensin-converting enzyme inhibitor normalized CXCR4 and AT1 receptor expression on progenitors concomitant with regression of crescentic lesions in a patient with crescentic glomerulonephritis. These results suggest that glomerular hyperplastic lesions derive from the proliferation and migration of renal progenitors in response to injured podocytes. The Ang II/AT1 receptor pathway may participate, together with SDF-1/CXCR4 axis, to the dysregulated response of renal precursors. Thus, targeting the Ang II/AT1 receptor/CXCR4 pathways may be beneficial in severe forms of glomerular proliferative disorders.

Limited scleroderma with pauci-immune glomerulonephritis in the presence of renal cell carcinoma

Connective tissue disorders increase the risk of malignancy; conversely, they may manifest as rheumatological paraneoplastic syndromes due to an underlying malignancy. We describe the case of a patient with limited scleroderma whose rapid disease progression coincided with the discovery of a renal tumor. A woman, age 75 years, presented with a 3-month history of progressive difficulty grasping objects, unsteadiness, dyspnea, xerostomia, xerophthalmia, and significant weight loss. She had a 10-year history of gastroesophageal reflux and Raynaud's phenomenon. Pertinent physical examination findings included facial telangiectasias, bibasilar inspiratory rales, sclerodactyly, and absent pinprick and vibratory sensation in her toes. She also had swelling and tenderness in several metacarpophalangeal and interphalangeal joints and in both ankles. A renal mass was demonstrated on abdominal computed tomography. A left partial nephrectomy was performed, confirming an unclassified type of renal cell carcinoma, along with a focal proliferative crescentic pauci-immune glomerulonephritis. Medical therapy with rituximab, pulse methylprednisolone, and prednisone led to improvement in her symptoms. The patient's presentation is consistent with a rapid progression of pre-existing limited scleroderma with the development of new rheumatological symptoms, including vasculitis. We propose that this progression was secondary to paraneoplastic stimulation by the renal cell carcinoma. Clinicians should consider looking for a malignancy in patients with connective tissue disorders who present with a myriad of new symptoms.

Monoclonal gammopathy-associated pauci-immune extracapillary-proliferative glomerulonephritis successfully treated with bortezomib

Extracapillary-proliferative glomerulonephritis is a rare complication of multiple myeloma. Partial remission of kidney involvement with cyclophosphamide therapy has previously been described. We report the case of a 60-year-old male patient diagnosed with rapidly progressive glomerulonephritis associated with IgG kappa monoclonal gammopathy. His kidney biopsy revealed pauci-immune extracapillary-proliferative glomerulonephritis without cryoglobulinaemia. Treatment with the proteasome inhibitor bortezomib induced rapid clinical and histological remission of his kidney disease. The patient's renal function remained stable on bortezomib maintenance therapy. Our findings suggest that bortezomib is a promising therapeutic approach to ameliorate severe kidney damage in monoclonal gammopathy- and myeloma-associated pauci-immune extracapillary-proliferative glomerulonephritis.

Pulmonary renal syndrome in a child with coexistence of anti-neutrophil cytoplasmic antibodies and anti-glomerular basement membrane disease: case report and literature review

BACKGROUND

Pulmonary renal syndrome (PRS), denoting the presence of diffuse alveolar hemorrhage and glomerulonephritis as manifestations of systemic autoimmune disease, is very rare in childhood. The coexistence of circulating anti-neutrophil cytoplasmic antibody (ANCA) and anti-glomerular basement membrane (GBM) disease in children affected by this syndrome is exceptional, with unfavorable outcome in five out of seven patients reported to date. We describe a child with PRS associated with both circulating anti-myeloperoxidase (anti-MPO) ANCA and anti-GBM disease on renal biopsy who was successfully treated with immunosuppressive therapy.

CASE PRESENTATION

A 10-year old girl presented with fever, fatigue, malaise, and pallor followed by hemoptysis and severe anemia. Diffuse alveolar hemorrhage was revealed on fiberoptic bronchoscopy. Renal findings consisted of microscopic hematuria, moderate proteinuria, and anti-GBM disease on renal biopsy. ANCA with anti-MPO specificity were present whereas anti-GBM antibodies were on borderline for positivity. Methyl-prednisolone pulses followed by prednisone led to cessation of hemoptysis, marked improvement of lung fuction, and normal finding on chest x-ray within 10 days. An immunosuppressive regimen was then given consisting of prednisone daily for 4 weeks with subsequent taper on alternate day, i.v. cyclophosphamide pulses monthly for 6 doses, followed by mycophenolate mofetil that resulted in normal lung function tests, hemoglobin concentration, and anti-MPO level within four subsequent weeks. During 10-months of follow-up she remained well, her blood pressure and renal function tests were normal, and proteinuria and hematuria gradually resolved.

CONCLUSION

We report a child with an exceptionally rare coexistence of circulating ANCA and anti-GBM disease manifesting as PRS in whom renal disease was not the prominent part of clinical presentation, contrary to other reported pediatric patients. A review of literature on disease with double positive antibodies is also presented. Evaluation of a patient with PRS should include testing for presence of different antibodies. An early diagnosis and rapid institution of aggressive immunosuppressive therapy can induce remission and preserve renal function. Renal prognosis depends on the extent of kidney injury at diagnosis and appropriate treatment.

Serum BAFF and APRIL might be associated with disease activity and kidney damage in patients with anti-glomerular basement membrane disease

AIM

B cell activating factor belonging to the tumour necrosis factor family (BAFF) and a proliferation inducing ligand (APRIL) are two tumour necrosis factor (TNF)-like cytokines that were found to be elevated in many autoimmune diseases. Anti-glomerular basement membrane (GBM) disease is a typical severe autoimmune disease characterized by raised serum anti-GBM antibodies. In this study we aimed to detect the serum levels of BAFF and APRIL in patients with anti-GBM disease, and their clinical significance was further analyzed.

METHODS

Forty-seven patients with anti-GBM disease were enrolled in this study. Forty-eight healthy individuals were used as normal controls. The levels of serum BAFF and APRIL were assessed using commercially available enzyme linked immunosorbent assay kits. The association between the levels of serum BAFF and APRIL, and the clinical and pathological parameters were further evaluated.

RESULTS

The serum levels of BAFF and APRIL in patients with anti-GBM disease were significantly higher than that in normal controls (12.3 ± 14.1 ng/mL vs. 0.9 ± 0.3 ng/mL, P < 0.001; 19.1 ± 22.9 ng/mL vs. 1.6 ± 4.6 ng/mL, P < 0.001), respectively. The levels of serum APRIL were correlated with the titres of anti-GBM antibodies (r = 0.347, P = 0.041), and the levels of serum BAFF were associated with the percentage of glomeruli with crescents (r = 0.482, P = 0.015) in patients with anti-GBM disease.

CONCLUSION

The levels of serum BAFF and APRIL were raised in patients with anti-GBM disease and might be associated with disease activity and kidney damage.

Anti-glomerular basement membrane antibody disease: a rare autoimmune disorder affecting the kidney and the lung

Anti-glomerular basement membrane antibody disease is a rare, but well characterized cause of glomerulonephritis. By definition serum anti-GBM antibody and/or a linear binding of IgG detected by direct immunofluorescence (IF) in a histological specimen of the kidney or the lung have to be detected. These antibodies can lead to acute rapid progressive glomerulonephritis(RPGN) and/or pulmonary hemorrhage (PH) because of collagen similarities in the basement membrane. Principally anti-GBM antibody disease can be divided into two groups: anti-GBM antibody disease without PH was regarded as renal-limited anti-GBM antibody disease and that with PH was defined as Goodpasture's syndrome (GPS). The important determinant for the response of therapy and long term diagnosis on anti-GBM disease is early diagnosis to prevent endstage renal disease. Therefore, standard treatment is a combined therapy of plasmapherisis, prednisolone and cyclophosphamide. The aim of this review is an overview of the pathogenesis, clinical presentation, diagnosis and treatment of anti-GBM disease.