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Shiga toxin-producing Escherichia coli-associated haemolytic uraemic syndrome (STEC-HUS) is one of the most important causes of acute kidney injury in patients of all ages, especially in children. It can occur sporadically or in outbreaks. STEC-HUS is a systemic illness caused by toxin-mediated injury to the vascular endothelium and a generalized inflammatory response. The kidney and the brain are the two primary target organs. Nearly 40% of patients with STEC-HUS require at least temporary renal replacement therapy and up to 20% will have permanent residual kidney dysfunction. Neurological injury can be sudden and severe and is the most frequent cause of acute mortality in patients with STEC-HUS. Over the past 30 years, a wide range of inflammatory mediators have been linked to the pathogenesis of STEC-HUS and associated renal and neurological complications. Recently, evidence has accumulated that abnormal activation of the alternative pathway of complement occurs in patients with STEC-HUS. In the large outbreak of STEC-HUS caused by E. coli O104:H4 that occurred in Germany in May 2011, a large number of patients received eculizumab, a monoclonal antibody directed against C5, in an open-label manner. We describe the experience with eculizumab under these emergent circumstances at one large centre. [ABSTRACT FROM AUTHOR]

Background and Purpose: Injuries frequently occur in competitive wrestling, with the elbow joint representing about 25% of all injuries. Specific to the elbow, the ulnar collateral ligament (UCL) can be injured traumatically from takedowns in wrestling. In athletes with complete UCL tears, surgical management is often recommended with nonoperative management resulting in less favorable outcomes. The purpose of this case report is to present a nonoperative criterion-based rehabilitation program for a high school wrestler with a complete UCL tear of the elbow., Case Description: A 17-year-old male wrestler presented to outpatient physical therapy with a complete UCL tear sustained from falling on an outstretched hand during a wrestling match. He presented with limited elbow range of motion (ROM), medial elbow instability, and weakness of the involved shoulder and forearm musculature. A three staged criterion-based rehabilitation protocol was developed for this subject based on specific criteria, including pain, elbow ROM, arm strength, and functional outcomes., Outcomes: The subject was treated for nine visits over six weeks, and demonstrated improvements in all strength tests of the involved upper extremity, with elbow flexion strength improving the most by 58%. Return to sport (RTS) tests were used to assess the subject's ability to return to practice. At approximately eight weeks after initial injury, the subject was able to return to full participation in competitive wrestling with no reports of elbow pain or instability., Discussion: Through the utilization of a criterion-based rehabilitation protocol for the nonoperative management of an UCL injury, this high school wrestler was able to safely progress back to wrestling without pain or instability in an accelerated time frame. Previously, no detailed rehabilitation guidelines for nonoperative management of UCL injuries in contact sports have been described. Additionally, few studies exist which report on the inclusion of RTS testing following an injury to the UCL of the elbow, as RTS testing is optimal for determining readiness for sport., Level of Evidence: 4, Case Report., (© 2020 by the Sports Physical Therapy Section.)

Introduction : Membranous nephropathy (MN) is the most common cause of a nephrotic syndrome in Caucasian adults. The identification of target antigens in MN in the last decade has had a major impact on the clinical approach to these patients. Areas covered : Since the discoveries in animal models in the 1980s that circulating autoantibodies induce disease upon in situ binding to glomerular podocytes, many attempts have been undertaken to define the human antigens responsible for disease induction. Only in 2009 was Phospholipase A 2 Receptor 1 described as the major antigen responsible for MN onset in about 70% of patients. Subsequently, in 2014, Thrombospondin Type-1 Domain-Containing 7A was identified as a second antigen, accounting for 2-3% of patients with MN. The knowledge of the role of these antibodies in MN has improved the diagnosis and management of patients and helped to better define the need for immunosuppressive treatment. Expert commentary : These discoveries over the last 10 years in the discipline of nephrology have clearly shown the improvements a better understanding of disease pathogenesis can bring for patient care.

Systemic lupus erythematosus (SLE) is a common autoimmune disorder with a complex and poorly understood immunopathogenesis. However, a pathogenic role for the T helper type 17 (Th17) axis was demonstrated by many studies, while regulatory T cells (T regs ) were shown to mediate protection. Recently, we and others characterized a novel and independent T cell population expressing both the T reg characteristic transcription factor forkhead box protein 3 (FoxP3) and the Th17-defining retinoic acid receptor-related orphan nuclear receptor γt (RORγt). Studies in a model of acute glomerulonephritis unveiled potent regulatory, but also proinflammatory, functions of RORγt + FoxP3 + T regs . This bi-functional nature prompted us to suggest the name 'biT regs '. Importantly, the pathogenic biT reg effects were dependent upon expression of RORγt. We thus aimed to evaluate the contribution of RORγt + FoxP3 + biT regs to pristane-induced SLE and explored the therapeutic potential of interference with RORγt activation. Our analyses revealed expansion of IL-17 producing biT regs in a distinctive time-course and organ-specific pattern, coincident with the development of autoimmunity and tissue injury. Importantly, specific ablation of RORγt activation in endogenous biT regs resulted in significant amelioration of pristane-induced pulmonary vasculitis and lupus nephritis. As potential mechanisms underlying the observed protection, we found that secretion of IL-17 by biT regs was abrogated completely in FoxP3 Cre  × RORC fl/fl mice. Furthermore, T regs showed a more activated phenotype after cell-specific inactivation of RORγt signalling. Finally, and remarkably, biT regs were found to potently suppress anti-inflammatory Th2 immunity in a RORγt-dependent manner. Our study thus identifies biT regs as novel players in SLE and advocates RORγt-directed interventions as promising therapeutic strategies., (© 2016 British Society for Immunology.)

We recently described a case of a Thrombospondin Type-1 Domain containing 7A (THSD7A) associated membranous nephropathy in a female patient who was synchronously suffering from a THSD7A-positive malignancy. We here investigated the role of THSD7A as a new potential tumor antigen by evaluating over 20 000 tissue spots in more than 70 different tumor entities by immunohistochemistry using tissue microarrays. THSD7A expression was highly variable in different neoplasias with differing staining patterns. Both gain and loss of THSD7A expression compared to expression status in non-tumor tissue were linked to tumor-specific markers in the different tumor entities and were of prognostic value. The potential role of THSD7A in tumor development and therapy needs further investigation., (© 2017 Wiley Periodicals, Inc.)

Thrombospondin type 1 domain-containing 7A (THSD7A) is a target antigen identified in adult membranous nephropathy (MN) along with the major antigen phospholipase A 2 receptor 1 (PLA 2 R1). The prevalence of THSD7A-Ab-positive patients is unknown, and it is unclear whether the clinical presentation differs between patients positive for PLA 2 R1-Ab or THSD7A-Ab. We screened serum samples of 1276 patients with MN from three different cohorts for the presence of THSD7A-Ab by Western blot analysis and a newly developed indirect immunofluorescence test (IFT). Compared with Western blot analysis, the IFT had a 92% sensitivity and a 100% specificity. The prevalence of THSD7A-associated MN in a prospective cohort of 345 patients with MN was 2.6%, and most were women. In this cohort, the percentage of patients with THSD7A-associated MN and malignant disease significantly exceeded that of patients with PLA 2 R1-associated MN and malignant disease. In all cohorts, we identified 40 patients with THSD7A-associated MN, eight of whom developed a malignancy within a median time of 3 months from diagnosis of MN. In one patient with THSD7A-associated MN and metastases of an endometrial carcinoma, immunohistochemistry showed THSD7A expression on the metastatic cells and within follicular dendritic cells of the metastasis-infiltrated lymph node. We conclude that the IFT allows sensitive and specific measurement of circulating THSD7A-Ab in patients with MN. Patients with THSD7A-associated MN differ in their clinical characteristics from patients with PLA 2 R1-associated MN, and more intensive screening for the presence of malignancies may be warranted in those with THSD7A-associated MN., (Copyright © 2017 by the American Society of Nephrology.)

Recent studies suggest that platelet transfusions are harmful in patients with thrombotic thrombocytopenic purpura, an entity of thrombotic microangiopathies. As the typical or Shiga toxin-producing Escherichia coli-induced hemolytic uremic syndrome (STEC-HUS) is also classified as thrombotic microangiopathy, we complement these data with an analysis of 250 patients from the German O104:H4 STEC-HUS outbreak. The effect of platelet transfusion in 44 patients who received platelet transfusions vs 206 control patients was investigated. Criteria for both groups were severe thrombocytopenia less than 50/nL, severe hemolysis with administration of packed red blood cells, and a complicated clinical course with admission to intensive care units. Readouts were clinical complications and changes in routine clinical chemistry and whole blood count. Chemistry values at admission and demographic parameters were comparable. Platelet transfusions were administered in 44 cases a median of 7 (interquartile range, 6-9) days after diarrhea onset. After platelet transfusion, we observed a transient and slight increase in inflammation parameters. No significant difference in major complications such as seizures, or requirement for ventilation or renal replacement therapy could be observed. Thrombotic events such as thrombosis or embolism were comparably rare in both groups (2.3% in platelet transfused vs 4.4% in controls, P=not significant). The mortality was not significantly different (0% vs 2.6%, P=not significant) in our study cohort, but overall in the outbreak, 6 of 711 STEC-HUS patients in Germany died of a procedural-related bleeding complications. In conclusion, platelet transfusions seem comparably safe in adult STEC-HUS patients, considering both the possible necessity for invasive procedures and potential risk for severe bleeding., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Th1 cells are central pathogenic mediators of crescentic GN (cGN). Mechanisms responsible for Th1 cell downregulation, however, remain widely unknown. Recently, it was proposed that activation of the Th1-characteristic transcription factor T-bet optimizes Foxp3 + regulatory T (Treg) cells to counteract Th1-type inflammation. Because very little is known about the role of T-bet + Treg1 cells in inflammatory diseases, we studied the function of these cells in the nephrotoxic nephritis (NTN) model of cGN. The percentage of Treg1 cells progressively increased in kidneys of nephritic wild-type mice during the course of NTN, indicating their functional importance. Notably, naïve Foxp3 Cre xT-bet fl/fl mice, lacking Treg1 cells, showed spontaneous skewing toward Th1 immunity. Furthermore, absence of Treg1 cells resulted in aggravated NTN with selectively dysregulated renal and systemic Th1 responses. Detailed analyses of Treg cells from Foxp3 Cre xT-bet fl/fl mice revealed unaltered cytokine production and suppressive capacity. However, in competitive cotransfer experiments, wild-type Treg cells outcompeted T-bet-deficient Treg cells in terms of population expansion and expression levels of Foxp3, indicating that T-bet expression is crucial for general Treg fitness. Additionally, T-bet-deficient Treg cells lacked expression of the Th1-characteristic trafficking receptor CXCR3, which correlated with significant impairment of renal Treg infiltration. In summary, our data indicate a new subtype of Treg cells in cGN. These Treg1 cells are characterized by activation of the transcription factor T-bet, which enhances the overall fitness of these cells and optimizes their capacity to downregulate Th1 responses by inducing chemokine receptor CXCR3 expression., (Copyright © 2016 by the American Society of Nephrology.)

The T H 17 immune response has a central role in the pathogenesis of autoimmune diseases, implicating the T H 17 master cytokine, IL-17A, as the critical mediator of diseases such as human and experimental crescentic GN. However, the relative importance of additional T H 17 effector cytokines, including IL-17F, in immune-mediated tissue injury remains to be fully elucidated. Here, using a mouse model of acute crescentic GN (nephrotoxic nephritis), we identified CD4 + T cells and γδ T cells as the major cellular source of IL-17F in the inflamed kidney. Interventional studies using IL-17F gene-deficient mice, IL-17F-neutralizing antibodies, and adoptive transfer experiments into Rag1 -/- mice demonstrated that CD4 + T cell-derived IL-17F drives renal tissue injury in acute crescentic GN. Notably, IL-17F-deficient nephritic mice had fewer renal infiltrating neutrophils than wild-type nephritic mice, and neutrophil depletion did not affect the course of GN in IL-17F-deficient mice. Moreover, in the chronic model of pristane-induced SLE, IL-17F-deficient mice developed less severe disease than wild-type mice, with respect to survival and renal injury. Finally, we show that IL-17F induced expression of the neutrophil-attracting chemokines CXCL1 and CXCL5 in kidney cells. The finding that IL-17F has a nonredundant function in the development of renal tissue injury in experimental GN might be of great importance for the development of anti-IL-17 cytokine therapies in T H 17-mediated human autoimmune diseases., (Copyright © 2016 by the American Society of Nephrology.)

Opportunistic infections are a major concern in renal and transplant medicine. We present the case of a renal transplant recipient with a generalised Mycobacterium haemophilum infection after an increase in immunosuppressive therapy and treatment with a tumour necrosis factor-α (TNF-α) inhibitor. Infection involved skin and soft tissue, joints and bones, as well as the renal transplant with an interstitial nephritis. Rapid diagnosis using PCR and DNA sequencing allowed early appropriate treatment. Triple antibiotic therapy and reduction in immunosuppression resulted in a slow but sustained recovery. Immunosuppression causes severe opportunistic infections. TNF-α inhibitors are very effective and well tolerated but have an increased susceptibility to infections with mycobacteria. Mycobacterial infections represent a significant clinical risk to transplant recipients because of their aggressive clinical course and the need for complex toxic antibiotic treatments. In these patients, M. haemophilum is a cause of skin infections., Competing Interests: Conflicts of Interest: None declared., (2016 BMJ Publishing Group Ltd.)

The ability of CD4(+) T cells to differentiate into pathogenic Th1 and Th17 or protective T regulatory cells plays a pivotal role in the pathogenesis of autoimmune diseases. Recent data suggest that CD4(+) T cell subsets display a considerable plasticity. This plasticity seems to be a critical factor for their pathogenicity, but also for the potential transition of pathogenic effector T cells toward a more tolerogenic phenotype. The aim of the current study was to analyze the plasticity of Th17 cells in a mouse model of acute crescentic glomerulonephritis and in a mouse chronic model of lupus nephritis. By transferring in vitro generated, highly purified Th17 cells and by using IL-17A fate reporter mice, we demonstrate that Th17 cells fail to acquire substantial expression of the Th1 and Th2 signature cytokines IFN-γ and IL-13, respectively, or the T regulatory transcription factor Foxp3 throughout the course of renal inflammation. In an attempt to therapeutically break the stability of the Th17 phenotype in acute glomerulonephritis, we subjected nephritic mice to CD3-specific Ab treatment. Indeed, this treatment induced an immunoregulatory phenotype in Th17 cells, which was marked by high expression of IL-10 and attenuated renal tissue damage in acute glomerulonephritis. In summary, we show that Th17 cells display a minimum of plasticity in acute and chronic experimental glomerulonephritis and introduce anti-CD3 treatment as a tool to induce a regulatory phenotype in Th17 cells in the kidney that may be therapeutically exploited., (Copyright © 2016 by The American Association of Immunologists, Inc.)

Glomerulonephritis encompasses a group of diseases that are characterized by inflammatory glomerular processes and clinically usually present with a nephritic and / or a nephrotic syndrome, as well as a deterioration of the renal function. Often, the diseases are accompanied by arterial hypertension and severe edema. In many cases however, the clinical symptoms are very mild or missing in the early phase of disease and therefore lead to a delayed diagnosis only after an impairment of renal function has developed. Urinalysis shows abnormalities in the very early phases of glomerulonephritis and should be performed in all patients, as soon as any evidence of renal involvement is present. Glomerulonephritis may occur primarily in the glomeruli, or present as renal involvement in the context of systemic diseases, most often vasculitis. In some cases, a symptomatic therapy is sufficient, while in other patients, a glomerulonephritis may represent as a medical emergency, which should be immediately and aggressively treated in order to prevent loss of renal function. Here we summarize the most important entities of glomerulonephritis, focusing on the pathogenesis, diagnostic tools and treatment options. The primary goal is the early diagnosis and a targeted, effective treatment of these patients., (© Georg Thieme Verlag KG Stuttgart · New York.)

Membranous nephropathy (MN) is the most common cause of nephrotic syndrome in adults, and one-third of patients develop end-stage renal disease (ESRD). Circulating autoantibodies against the podocyte surface antigens phospholipase A2 receptor 1 (PLA2R1) and the recently identified thrombospondin type 1 domain-containing 7A (THSD7A) are assumed to cause the disease in the majority of patients. The pathogenicity of these antibodies, however, has not been directly proven. Here, we have reported the analysis and characterization of a male patient with THSD7A-associated MN who progressed to ESRD and subsequently underwent renal transplantation. MN rapidly recurred after transplantation. Enhanced staining for THSD7A was observed in the kidney allograft, and detectable anti-THSD7A antibodies were present in the serum before and after transplantation, suggesting that these antibodies induced a recurrence of MN in the renal transplant. In contrast to PLA2R1, THSD7A was expressed on both human and murine podocytes, enabling the evaluation of whether anti-THSD7A antibodies cause MN in mice. We demonstrated that human anti-THSD7A antibodies specifically bind to murine THSD7A on podocyte foot processes, induce proteinuria, and initiate a histopathological pattern that is typical of MN. Furthermore, anti-THSD7A antibodies induced marked cytoskeletal rearrangement in primary murine glomerular epithelial cells as well as in human embryonic kidney 293 cells. Our findings support a causative role of anti-THSD7A antibodies in the development of MN.

Chemokines and chemokine receptors are implicated in regulatory T cell (Treg) trafficking to sites of inflammation and suppression of excessive immune responses in inflammatory and autoimmune diseases; however, the specific requirements for Treg migration into the inflamed organs and the positioning of these cells within the tissue are incompletely understood. Here, we report that Tregs expressing the TH1-associated chemokine receptor CXCR3 are enriched in the kidneys of patients with ANCA-associated crescentic GN and colocalize with CXCR3(+) effector T cells. To investigate the functional role of CXCR3(+) Tregs, we generated mice that lack CXCR3 in Tregs specifically (Foxp3(eGFP-Cre) × Cxcr3(fl/fl)) and induced experimental crescentic GN. Treg-specific deletion of CXCR3 resulted in reduced Treg recruitment to the kidney and an overwhelming TH1 immune response, with an aggravated course of the nephritis that was reversible on anti-IFNγ treatment. Together, these findings show that a subset of Tregs expresses CXCR3 and thereby, acquires trafficking properties of pathogenic CXCR3(+) TH1 cells, allowing Treg localization and control of excessive TH1 responses at sites of inflammation., (Copyright © 2016 by the American Society of Nephrology.)

Adaptive and innate immune responses contribute to hypertension and hypertensive end-organ damage. Here, we determined the role of anaphylatoxin C5a, a major inflammatory effector of the innate immune system that is generated in response to complement activation, in hypertensive end-organ damage. For this purpose, we assessed the phenotype of C5a receptor 1 (C5aR1)-deficient mice in ANG II-induced renal and cardiac injury. Expression of C5aR1 on infiltrating and resident renal as well as cardiac cells was determined using a green fluorescent protein (GFP)-C5aR1 reporter knockin mouse. Flow cytometric analysis of leukocytes isolated from the kidney of GFP-C5aR1 reporter mice showed that 28% of CD45-positive cells expressed C5aR1. Dendritic cells were identified as the major C5aR1-expressing population (88.5%) followed by macrophages and neutrophils. Using confocal microscopy, we detected C5aR1 in the kidney mainly on infiltrating cells. In the heart, only infiltrating cells stained C5aR1 positive. To evaluate the role of C5aR1 deficiency in hypertensive injury, an aggravated model of hypertension was used. Unilateral nephrectomy was performed followed by infusion of ANG II (1.5 ng·g(-1)·min(-1)) and salt in wild-type (n = 34) and C5aR1-deficient mice (n = 32). C5aR1-deficient mice exhibited less renal injury, as evidenced by significantly reduced albuminuria. In contrast, cardiac injury was accelerated with significantly increased cardiac fibrosis and heart weight in C5aR1-deficient mice after ANG II infusion. No effect was found on blood pressure. In summary, the C5a:C5aR1 axis drives end-organ damage in the kidney but protects from the development of cardiac fibrosis and hypertrophy in experimental ANG II-induced hypertension., (Copyright © 2016 the American Physiological Society.)

Cells expressing both the regulatory T cell (Treg)-inducing transcription factor Foxp3 and the Th17 transcription factor RORγt have been identified (biTregs). It is unclear whether RORγt(+)Foxp3(+) biTregs belong to the Th17-specific Treg17 cells, represent intermediates during Treg/Th17 transdifferentiation, or constitute a distinct cell lineage. Because the role of biTregs in inflammatory renal disease is also unknown, we studied these cells in the nephrotoxic nephritis (NTN) model of acute crescentic GN. Induction of NTN resulted in rapid renal and systemic expansion of biTregs. Notably, analyses of the biTreg expression profile revealed production of both anti-inflammatory (IL-10, IL-35) and proinflammatory (IL-17) cytokines. Additionally, biTregs expressed a signature of surface molecules and transcription factors distinct from those of Th17 cells and conventional Tregs (cTregs), and biTregs were identified in Treg17-deficient mice. Finally, fate reporter and cell transfer studies confirmed that biTregs are not Treg/Th17 transdifferentiating cells. Therapeutic transfer of biTregs suppressed the development of nephritis to an extent similar to that observed with transferred cTregs, but in vitro studies indicated different mechanisms of immunosuppression for biTregs and cTregs. Intriguingely, as predicted from their cytokine profile, endogenous biTregs displayed additional proinflammatory functions in NTN that were abrogated by cell-specific deletion of RORγt. In summary, we provide evidence that RORγt(+)Foxp3(+) biTregs are a novel and independent bifunctional regulatory T cell lineage distinct from cTregs, Treg17 cells, and Th17 cells. Furthermore, biTregs appear to contribute to crescentic GN and hence may be novel therapeutic targets., (Copyright © 2016 by the American Society of Nephrology.)

Systemic lupus erythematosus (SLE) is a complex and potentially fatal autoimmune disorder. Although Th17 cells are thought to be central mediators of SLE, mechanisms underlying their counter regulation remain largely unknown. To help define this, we studied the function of the newly defined Stat3-dependent Th17-specific regulatory T cells (Treg17). Treg-specific deletion of Stat3 was achieved by generating Foxp3(Cre) × Stat3(fl/fl) mice and SLE was induced by intraperitoneal injection of pristane. Lack of Treg17 cells in these mice caused selectively enhanced peritoneal Th17 inflammation. Importantly, Treg17 deficiency also resulted in aggravated pulmonary vasculitis with increased percentages of Th17 cells and significantly higher mortality. Similarly, 4 and 9 months after pristane injection, analysis of renal and systemic immunity showed overshooting Th17 responses in the absence of Treg17 cells, associated with the aggravation of lupus nephritis. Expression of the Th17 characteristic trafficking receptor CCR6 was strikingly reduced on Tregs of Foxp3(Cre) × Stat3(fl/fl) mice, resulting in impaired renal Treg infiltration. Thus, Stat3-induced Treg17 cells are novel antiinflammatory mediators of SLE. One mechanism enabling Treg17 cells to target pathogenic Th17 responses is shared expression of the chemokine receptor CCR6., (Copyright © 2015 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Background: Phospholipase A2 receptor antibodies (PLA2R-Ab) and thrombospondin type-1 domain-containing 7A antibodies (THSD7A-Ab) are present in 70-80% of patients with membranous nephropathy (MN). Little, however, is known about the pathogenesis of MN and the clinical outcome in PLA2R-Ab- and THSD7A-Ab-negative patients., Methods: In this prospective multicentre observational study, the clinical outcome of 37 patients with biopsy-proven MN who were negative for PLA2R-Ab and THSD7A-Ab in the serum was analysed., Results: A total of 198 patients were screened for inclusion in the study. Of these, 157 patients were positive for PLA2R-Ab and 4 patients for THSD7A-Ab. The remaining 37 patients were negative for both antibodies were and included in this study. Six patients died during the follow-up, five because of malignant diseases and one of an infection. One patient went into end-stage renal disease, and two patients were lost to follow-up. The remaining 28 patients were followed for at least 24 months (35.6 ± 8.9 months). Seventeen patients received immunosuppressive (IS) therapy, and 11 received supportive care only. At the end of the follow-up, 14 of the 17 patients treated with immunosuppressants and 10 of 11 patients on supportive therapy had a remission of proteinuria. The time to reach remission of proteinuria and serum creatinine levels at the end of the follow-up were not different between both groups. A univariate Cox regression analysis indicated that the use of immunosuppression did not alter the chance to reach a remission of proteinuria., Conclusions: A high number of PLA2R-Ab- and THSD7A-Ab-negative patients with MN have a good prognosis and might not need IS therapy., (© The Author 2015. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.)

ANCA-associated vasculitis is the most frequent cause of crescentic GN. To define new molecular and/or cellular biomarkers of this disease in the kidney, we performed microarray analyses of renal biopsy samples from patients with ANCA-associated crescentic GN. Expression profiles were correlated with clinical data in a prospective study of patients with renal ANCA disease. CC chemokine ligand 18 (CCL18), acting through CC chemokine receptor 8 (CCR8) on mononuclear cells, was identified as the most upregulated chemotactic cytokine in patients with newly diagnosed ANCA-associated crescentic GN. Macrophages and myeloid dendritic cells in the kidney were detected as CCL18-producing cells. The density of CCL18(+) cells correlated with crescent formation, interstitial inflammation, and impairment of renal function. CCL18 protein levels were higher in sera of patients with renal ANCA disease compared with those in sera of patients with other forms of crescentic GN. CCL18 serum levels were higher in patients who suffered from ANCA-associated renal relapses compared with those in patients who remained in remission. Using a murine model of crescentic GN, we explored the effects of the CCL18 murine functional analog CCL8 and its receptor CCR8 on kidney function and morphology. Compared with wild-type mice, Ccr8(-/-) mice had significantly less infiltration of pathogenic mononuclear phagocytes. Furthermore, Ccr8(-/-) mice maintained renal function better and had reduced renal tissue injury. In summary, our data indicate that CCL18 drives renal inflammation through CCR8-expressing cells and could serve as a biomarker for disease activity and renal relapse in ANCA-associated crescentic GN., (Copyright © 2015 by the American Society of Nephrology.)

IL-6 can mediate proinflammatory effects, and IL-6 receptor (IL-6R) blockade as a treatment for inflammatory diseases has entered clinical practice. However, opposing effects of IL-6 have been observed in models of GN. Although IL-6 is proinflammatory in murine lupus nephritis, protective effects have been observed for IL-6 in the nephrotoxic nephritis (NTN) model of acute crescentic GN. In light of the potential dangers of IL-6-directed treatment, we studied the mechanisms underlying the contradictory findings in GN. IL-6 can signal through the membrane-bound IL-6R, which is expressed only on hepatocytes and certain leukocytes (classic), or through the soluble IL-6R, which binds the ubiquitously expressed gp130 (alternative). Preemptive treatment of mice with anti-IL-6R or anti-IL-6 worsened NTN, whereas selective blockade of alternative IL-6 signaling by the fusion protein sgp130Fc did not. FACS analysis of mouse spleen cells revealed proinflammatory macrophages express the highest levels of IL-6Rα, and in vitro treatment with IL-6 blocked macrophage proliferation. Furthermore, proinflammatory macrophages were expanded during inflammation in IL-6(-/-) mice. Late application of anti-IL-6 after establishment of adaptive nephritogenic immunity was sufficient to aggravate NTN within 2.5 days, a period when macrophages are active. Finally, NTN was aggravated in mice with macrophage-specific impairment of IL-6 classic signaling, coincident with enhanced macrophage proliferation and accumulation in the kidney. Our data thus reveal a novel mechanism in which IL-6-mediated dampening of macrophage activation protects tissues from overshooting immune responses. This finding has important implications for potential IL-6-directed therapies and supports the careful choice of recipient patients and timing., (Copyright © 2015 by the American Society of Nephrology.)

Parietal epithelial cells have been identified as potential progenitor cells in glomerular regeneration, but the molecular mechanisms underlying this process are not fully defined. Here, we established an immortalized polyclonal human parietal epithelial cell (hPEC) line from naive human Bowman's capsule cells isolated by mechanical microdissection. These hPECs expressed high levels of PEC-specific proteins and microRNA-193a (miR-193a), a suppressor of podocyte differentiation through downregulation of Wilms' tumor 1 in mice. We then investigated the function of miR-193a in the establishment of podocyte and PEC identity and determined whether inhibition of miR-193a influences the behavior of PECs in glomerular disease. After stable knockdown of miR-193a, hPECs adopted a podocyte-like morphology and marker expression, with decreased expression levels of PEC markers. In mice, inhibition of miR-193a by complementary locked nucleic acids resulted in an upregulation of the podocyte proteins synaptopodin and Wilms' tumor 1. Conversely, overexpression of miR-193a in vivo resulted in the upregulation of PEC markers and the loss of podocyte markers in isolated glomeruli. Inhibition of miR-193a in a mouse model of nephrotoxic nephritis resulted in reduced crescent formation and decreased proteinuria. Together, these results show the establishment of a human PEC line and suggest that miR-193a functions as a master switch, such that glomerular epithelial cells with high levels of miR-193a adopt a PEC phenotype and cells with low levels of miR-193a adopt a podocyte phenotype. miR-193a-mediated maintenance of PECs in an undifferentiated reactive state might be a prerequisite for PEC proliferation and migration in crescent formation., (Copyright © 2015 by the American Society of Nephrology.)

Objective: The CD4+ T cell immune response plays a pivotal role in the immunopathogenesis of human and experimental lupus nephritis, but the contribution of the Th17/interleukin-17 (IL-17) immune pathway to renal tissue injury in systemic lupus erythematosus (SLE) remains to be elucidated. The aim of this study was to characterize the function of the Th17/IL-17A immune response in 2 murine models of lupus nephritis., Methods: IL-17A-deficient MRL/MPJ-Fas(lpr) /2J (MRL/lpr) mice were generated, and the clinical course of nephritis was monitored by assessing the levels of albuminuria, extent of renal tissue injury, and functional parameters. In addition, lupus-prone (NZB × NZW)F1 (NZB/NZW) mice were treated with anti-IL-17A and anti-interferon-γ (anti-IFNγ) antibodies, and their effects on the clinical course of lupus nephritis were assessed., Results: Characterization of renal IL-17A-producing and IFNγ-producing T cells in MRL/lpr and NZB/NZW mice revealed low numbers of infiltrating CD3+IL-17A+ cells. Renal IL-17A was mainly produced by CD4/CD8 double-negative CD3+ T cells and CD4+ Th17 cells. In contrast, the number of renal CD3+IFNγ+ cells continuously increased over time and largely consisted of typical CD4+ Th1 cells. IL-17A deficiency did not affect the morphologic or functional parameters in MRL/lpr mice with lupus nephritis, nor did IL-17A neutralization affect the clinical course of nephritis in NZB/NZW mice, but anti-IFNγ treatment attenuated the severity of the disease., Conclusion: The Th17/IL-17A immune response plays no major role in the immunopathogenesis of lupus nephritis in MRL/lpr and NZB/NZW mice. Thus, the results of this study do not support the hypothesis that IL-17A targeting could be an intriguing new therapeutic approach for the management of proliferative lupus nephritis in SLE patients., (Copyright © 2015 by the American College of Rheumatology.)

Neutrophil trafficking to sites of inflammation is essential for the defense against bacterial and fungal infections, but also contributes to tissue damage in TH17-mediated autoimmunity. This process is regulated by chemokines, which often show an overlapping expression pattern and function in pathogen- and autoimmune-induced inflammatory reactions. Using a murine model of crescentic GN, we show that the pathogenic TH17/IL-17 immune response induces chemokine (C-X-C motif) ligand 5 (CXCL5) expression in kidney tubular cells, which recruits destructive neutrophils that contribute to renal tissue injury. By contrast, CXCL5 was dispensable for neutrophil recruitment and effective bacterial clearance in a murine model of acute bacterial pyelonephritis. In line with these findings, CXCL5 expression was highly upregulated in the kidneys of patients with ANCA-associated crescentic GN as opposed to patients with acute bacterial pyelonephritis. Our data therefore identify CXCL5 as a potential therapeutic target for the restriction of pathogenic neutrophil infiltration in TH17-mediated autoimmune diseases while leaving intact the neutrophil function in protective immunity against invading pathogens., (Copyright © 2015 by the American Society of Nephrology.)

Background and Objectives: Loss of renal function in patients with primary membranous nephropathy cannot be reliably predicted by laboratory or clinical markers at the time of diagnosis. M-type phospholipase A2 receptor autoantibodies have been shown to be associated with changes in proteinuria. Their eventual effect on renal function, however, is unclear., Design, Setting, Participants, & Measurements: In this prospective, open, multicenter study, the potential role of M-type phospholipase A2 receptor autoantibodies levels on the increase of serum creatinine in 118 consecutive patients with membranous nephropathy and positivity for serum M-type phospholipase A2 receptor autoantibodies was analyzed. Patients were included in the study between April of 2010 and December of 2012 and observed until December of 2013. The clinical end point was defined as an increase of serum creatinine by ≥ 25% and serum creatinine reaching ≥ 1.3 mg/dl., Results: Patients were divided into tertiles according to their M-type phospholipase A2 receptor autoantibody levels at the time of inclusion in the study: tertile 1 levels=20-86 units/ml (low), tertile 2 levels=87-201 units/ml (medium), and tertile 3 levels ≥ 202 units/ml (high). The median follow-up time of all patients in the study was 27 months (interquartile range=18-33 months). The clinical end point was reached in 69% of patients with high M-type phospholipase A2 receptor autoantibodies levels (tertile 3) but only 25% of patients with low M-type phospholipase A2 receptor autoantibodies levels. The average time to reach the study end point was 17.7 months in patients with high M-type phospholipase A2 receptor autoantibodies levels and 30.9 months in patients with low M-type phospholipase A2 receptor autoantibodies levels. A multivariate Cox regression analysis showed that high M-type phospholipase A2 receptor autoantibodies levels-in addition to men and older age-are an independent predictor for progressive loss of renal function., Conclusions: High M-type phospholipase A2 receptor autoantibodies levels were associated with more rapid loss of renal function in this cohort of patients with primary membranous nephropathy and therefore, could be helpful for treatment decisions., (Copyright © 2014 by the American Society of Nephrology.)

Podocytes are the key cells affected in nephrotic glomerular kidney diseases, and they respond uniformly to injury with cytoskeletal rearrangement. In nephrotic diseases, such as membranous nephropathy and FSGS, persistent injury often leads to irreversible structural damage, whereas in minimal change disease, structural alterations are mostly transient. The factors leading to persistent podocyte injury are currently unknown. Proteolysis is an irreversible process and could trigger persistent podocyte injury through degradation of podocyte-specific proteins. We, therefore, analyzed the expression and functional consequence of the two most prominent proteolytic systems, the ubiquitin proteasome system (UPS) and the autophagosomal/lysosomal system, in persistent and transient podocyte injuries. We show that differential upregulation of both proteolytic systems occurs in persistent human and rodent podocyte injury. The expression of specific UPS proteins in podocytes differentiated children with minimal change disease from children with FSGS and correlated with poor clinical outcome. Degradation of the podocyte-specific protein α-actinin-4 by the UPS depended on oxidative modification in membranous nephropathy. Notably, the UPS was overwhelmed in podocytes during experimental glomerular disease, resulting in abnormal protein accumulation and compensatory upregulation of the autophagosomal/lysosomal system. Accordingly, inhibition of both proteolytic systems enhanced proteinuria in persistent nephrotic disease. This study identifies altered proteolysis as a feature of persistent podocyte injury. In the future, specific UPS proteins may serve as new biomarkers or therapeutic targets in persistent nephrotic syndrome., (Copyright © 2014 by the American Society of Nephrology.)

Patients with primary membranous nephropathy (MN) who experience spontaneous remission of proteinuria generally have an excellent outcome without need of immunosuppressive therapy. It is, however, unclear whether non-nephrotic proteinuria at the time of diagnosis is also associated with good prognosis since a reasonable number of these patients develop nephrotic syndrome despite blockade of the renin-angiotensin system. No clinical or laboratory parameters are available, which allow the assessment of risk for development of nephrotic proteinuria. Phospholipase A2 Receptor antibodies (PLA2R-Ab) play a prominent role in the pathogenesis of primary MN and are associated with persistence of nephrotic proteinuria. In this study we analysed whether PLA2R-Ab levels might predict development of nephrotic syndrome and the clinical outcome in 33 patients with biopsy-proven primary MN and non-nephrotic proteinuria under treatment with blockers of the renin-angiotensin system. PLA2R-Ab levels, proteinuria and serum creatinine were measured every three months. Nephrotic-range proteinuria developed in 18 (55%) patients. At study start (1.2±1.5 months after renal biopsy and time of diagnosis), 16 (48%) patients were positive for PLA2R-Ab. A multivariate analysis showed that PLA2R-Ab levels were associated with an increased risk for development of nephrotic proteinuria (HR = 3.66; 95%CI: 1.39-9.64; p = 0.009). Immunosuppressive therapy was initiated more frequently in PLA2R-Ab positive patients (13 of 16 patients, 81%) compared to PLA2R-Ab negative patients (2 of 17 patients, 12%). PLA2R-Ab levels are associated with higher risk for development of nephrotic-range proteinuria in this cohort of non-nephrotic patients at the time of diagnosis and should be closely monitored in the clinical management.

Background: The diarrhea associated hemolytic uremic syndrome (HUS) is a major cause of acute uremic failure in children, but not very common in adults. The enterohaemorrhagic Escherichia coli-epidemic in Germany in 2011 affected mostly young and healthy adults. While their immediate deficits have been published, not much is known about the time course and degree of recovery concerning cognitive and behavioral impairment., Methods and Findings: Twenty patients with Shiga toxin-producing Escherichia coli infection and neurological symptoms underwent comprehensive neuropsychological assessment 3 months and 1 year after the acute disease. Overall, there was an excellent recovery of cognitive functions. In a detailed neuropsychological analysis no significant deficits could be noticed 1 year after the infection in terms of cognitive function, alertness, executive functions and speech. Interestingly there were no correlations between different indicators for severity of disease (hemoglobin and creatinine levels, days of hospitalization, neurological symptoms and MRI changes) and neuropsychological outcome. However, there were a small number of patients with limitations in every day and professional life even one year after the acute disease., Conclusions: Our study does not provide definitive answers regarding risk factors for these limitations. Still since Shiga toxin -producing Escherichia coli infection is a rare condition in adults, the information this study provides is important for the clinical practice. On one hand for consulting patients and on the other to raise the awareness of the physicians to possible long term complains and the consideration of neuropsychological assessment and supportive psychological treatment.

Podocytes are terminally differentiated cells of the glomerular filtration barrier that react with hypertrophy in the course of injury such as in membranous nephropathy (MGN). The neuronal deubiquitinase ubiquitin C-terminal hydrolase L1 (UCH-L1) is expressed and activated in podocytes of human and rodent MGN. UCH-L1 regulates the mono-ubiquitin pool and induces accumulation of poly-ubiquitinated proteins in affected podocytes. Here, we investigated the role of UCH-L1 in podocyte hypertrophy and in the homeostasis of the hypertrophy associated "model protein" p27(Kip1). A better understanding of the basic mechanisms leading to podocyte hypertrophy is crucial for the development of specific therapies in MGN. In human and rat MGN, hypertrophic podocytes exhibited a simultaneous up-regulation of UCH-L1 and of cytoplasmic p27(Kip1) content. Functionally, inhibition of UCH-L1 activity and knockdown or inhibition of UCH-L1 attenuated podocyte hypertrophy by decreasing the total protein content in isolated glomeruli and in cultured podocytes. In contrast, UCH-L1 levels and activity increased podocyte hypertrophy and total protein content in culture, specifically of cytoplasmic p27(Kip1). UCH-L1 enhanced cytoplasmic p27(Kip1) levels by nuclear export and decreased poly-ubiquitination and proteasomal degradation of p27(Kip1). In parallel, UCH-L1 increased podocyte turnover, migration and cytoskeletal rearrangement, which are associated with known oncogenic functions of cytoplasmic p27(Kip1) in cancer. We propose that UCH-L1 induces podocyte hypertrophy in MGN by increasing the total protein content through altered degradation and accumulation of proteins such as p27(Kip1) in the cytoplasm of podocytes. Modification of both UCH-L1 activity and levels could be a new therapeutic avenue to podocyte hypertrophy in MGN., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Membranous nephropathy (MN) is the most common cause of nephrotic syndrome in adults, with an uncertain clinical outcome. The characterization of the phospholipase A2 receptor (PLA2R) as the major target antigen in primary MN and the detection of circulating autoantibodies in these patients is a major advance in understanding this disease. To test whether PLA2R antibody levels reflect disease activity or clinical outcome, we performed a prospective multicenter study of 133 adult patients with primary MN and detectable serum PLA2R antibodies who had not received immunosuppressive therapy. Patients were followed ≤24 months. PLA2R antibody levels associated with clinical disease activity (proteinuria) in patients with immunosuppressive therapy (n=101) or supportive care (n=32). Within 3 months, immunosuppressive therapy led to a sustained 81% reduction in PLA2R antibody levels paralleled by a 39% reduction in proteinuria. Patients who experienced remission of proteinuria after 12 months had significantly lower PLA2R antibody levels at the time of study inclusion compared with patients with no remission. Patients with high PLA2R antibody levels achieved remission of proteinuria significantly later than patients with low PLA2R antibody levels. PLA2R antibody levels fell over time in patients with spontaneous remission but remained elevated in patients who did not show a reduction in proteinuria. Multivariable Cox regression analysis confirmed PLA2R antibody level as an independent risk factor for not achieving remission of proteinuria. We conclude that a decrease in PLA2R antibody level is associated with a decrease of proteinuria in patients with primary MN., (Copyright © 2014 by the American Society of Nephrology.)

A pathogenic role for Th17 cells in inflammatory renal disease is well established. The mechanisms underlying their counter-regulation are, however, largely unknown. Recently, Th17 lineage-specific regulatory T cells (Treg17) that depend on activation of the transcription factor Stat3 were identified. We studied the function of Treg17 in the nephrotoxic nephritis (NTN) model of crescentic GN. The absence of Treg17 cells in Foxp3(Cre)×Stat3(fl/fl) mice resulted in the aggravation of NTN and skewing of renal and systemic immune responses toward Th17. Detailed analysis of Stat3-deficient Tregs revealed that the survival, activation, proliferation, and suppressive function of these cells remained intact. However, Tregs from Foxp3(Cre)×Stat3(fl/fl) mice lacked surface expression of the chemokine receptor CCR6, which resulted in impaired renal trafficking. Furthermore, aggravation of NTN was reversible in the absence of Th17 responses, as shown in CD4(Cre)×Stat3(fl/fl) mice lacking both Treg17 and Th17 cells, suggesting that Th17 cells are indeed the major target of Treg17 cells. Notably, immunohistochemistry revealed CCR6-bearing Treg17 cells in kidney biopsy specimens of patients with GN. CCR6 expression on human Treg17 cells also appears dependent on STAT3, as shown by analysis of Tregs from patients with dominant-negative STAT3 mutations. Our data indicate the presence and involvement of Stat3/STAT3-dependent Treg17 cells that specifically target Th17 cells in murine and human crescentic GN, and suggest the kidney-specific action of these Treg17 cells is regulated by CCR6-directed migration into areas of Th17 inflammation., (Copyright © 2014 by the American Society of Nephrology.)

IL-10-secreting regulatory B cells have been postulated as negative mediators of inflammation. However, their impact on immune-mediated diseases requires further investigation. We recently found that IL-10-secreting B cells infiltrate the kidney during crescentic glomerulonephritis (GN). We therefore studied the function of B-cell-derived IL-10 in light of the potential risks associated with increasingly used B-cell depleting therapies. Lack of IL-10 production by B cells, however, did not influence acute or adaptively mediated progressive renal injury in terms of renal function and histological damage in the nephrotoxic nephritis model of GN. Renal leukocyte infiltration and cytokine expression were similar apart from increased macrophages in mice lacking B-cell-derived IL-10. Systemic immune responses as assessed by cytokine production, leukocyte composition, proliferation, and activation were indistinguishable, while production and renal deposition of Ag-specific IgG were mildly impaired in the absence of B-cell-produced IL-10. Importantly, detailed analysis of systemic and renal regulatory T cells did not show any differences between nephritic mice bearing IL-10-deficient B cells and WT controls. Finally, studies in reporter mice revealed that B cells are only a minor source of systemic IL-10. In summary, our data reveal that endogenous B-cell-derived IL-10 does not play a major role in the nephrotoxic nephritis model of crescentic GN., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

T cells participate in angiotensin II (Ang II)-induced hypertension. However, the specific subsets of T cells that are important in the end-organ damage are unknown. T-helper 17 cells are a recently identified subset that produces interleukin 17 (IL-17) and requires interleukin 23 (IL-23) for expansion. To evaluate the role of the T-helper 17 immune response in hypertensive renal and cardiac end-organ damage, hypertension was induced with deoxycorticosterone acetate (DOCA)+Ang II in wild-type (n=39) and IL-17-deficient (n=31) mice. The injury was evaluated at day 4 and day 14. To inactivate the IL-17/IL-23 axis at a different point, DOCA+Ang II hypertension was also induced in IL-23p19-deficient mice. Renal infiltration by T-helper 17 cells was increased in hypertensive wild-type mice. Systolic blood pressure did not differ between hypertensive IL-17-deficient and wild-type mice. Three days after induction of hypertension, a significantly higher albuminuria was found in IL-17-deficient than in wild-type mice (196±64 versus 58±16 mg/mg albumin/creatinine). Histology revealed significantly more glomerular injury (1.04±0.06 versus 0.67±0.05) and renal infiltration of γδ T cells in IL-17-deficient than in wild-type mice after 14 days. Similarly, significantly higher albuminuria, glomerular injury, and γδ T cell infiltration were found in IL-23p19-deficient mice with DOCA+Ang II-induced hypertension. DOCA+Ang II also induced cardiac damage as assessed by heart weight, cardiac fibrosis, as well as expression of fetal genes and matrix components, but no significant differences were found among IL-17(-/-), IL-23p19(-/-), and wild-type mice. IL-17/IL-23 deficiency accelerates DOCA+Ang II-induced albuminuria and hypertensive renal but not cardiac end-organ damage.

CD4(+) T cells play a pivotal role in the pathogenesis of autoimmune disease, including human and experimental crescentic GN. Micro-RNAs (miRs) have emerged as important regulators of immune cell development, but the impact of miRs on the regulation of the CD4(+) T cell immune response remains to be fully clarified. Here, we report that miR-155 expression is upregulated in the kidneys of patients with ANCA-associated crescentic GN and a murine model of crescentic GN (nephrotoxic nephritis). To elucidate the potential role of miR-155 in T cell-mediated inflammation, nephritis was induced in miR-155(-/-) and wild-type mice. The systemic and renal nephritogenic TH17 immune response decreased markedly in nephritic miR-155(-/-) mice. Consistent with this finding, miR-155-deficient mice developed less severe nephritis, with reduced histologic and functional injury. Adoptive transfer of miR-155(-/-) and wild-type CD4(+) T cells into nephritic recombination activating gene 1-deficient (Rag-1(-/-)) mice showed the T cell-intrinsic importance of miR-155 for the stability of pathogenic TH17 immunity. These findings indicate that miR-155 drives the TH17 immune response and tissue injury in experimental crescentic GN and show that miR-155 is a potential therapeutic target in TH17-mediated diseases.

The role of parietal epithelial cells (PECs) in glomerular disease is unclear because they also express podocyte proteins under pathophysiological conditions. To help resolve this, we established a novel PEC isolation technique in rats and mice to investigate which regulatory mechanisms lead to podocyte protein expression in PECs. This pure pool of naive PECs was then compared with PECs in primary culture and immortalized PECs in permanent culture. The naive PECs expressed low levels of podocyte-specific mRNA. Accordingly, in crescentic glomerulonephritis, single PECs activated the podocin promoter in vivo. In primary culture, PECs expressed a distinct morphology from podocytes but with high transcript and protein levels of PEC markers. In contrast to naive PECs, cultured PECs also expressed podocyte proteins, and this correlated with reduced proteolytic activity but not with increased transcript levels. Activation of autophagy or proteasomal degradation decreased the levels of podocyte proteins in PECs, whereas inhibition of proteasomal degradation led to the stabilization of podocyte proteins in PECs. Thus, naive PECs express podocyte transcripts physiologically and these podocyte proteins are stable under pathological conditions through decreased proteolysis.

Objective: In Spring 2011, an unprecedented outbreak of Shiga toxin-producing Escherichia coli serotype O104:H4-associated hemolytic uremic syndrome occurred in Northern Germany. The aim of this study was to describe the clinical characteristics, treatments, and outcomes of critically ill patients with Shiga toxin-producing E. coli-associated hemolytic uremic syndrome during this outbreak., Design, Setting, and Patients: Multicenter, retrospective, observational study of critically ill adult patients with Shiga toxin-producing E. coli-associated hemolytic uremic syndrome in six hospitals in Hamburg, Germany, between May 2011 and August 2011., Measurements and Main Results: During the study period, 106 patients with Shiga toxin-producing E. coli-associated hemolytic uremic syndrome were admitted to eight ICUs. The median age was 40 years (range, 18-83) with a female:male ratio of 3:1. The median time from onset of clinical symptoms to hospital admission was 3 days and from hospital to ICU admission an additional 3 days. A total of 101 patients (95.3%) had acute renal failure and 78 (73.6%) required renal replacement therapy. Intubation and mechanical ventilation were required in 38 patients (35.8%) and noninvasive ventilation was required in 17 patients (16.0%). The median duration of invasive ventilation was 7 days (range, 1-32 days) and the median ICU stay was 10 days (range, 1-45 days). Fifty-one patients (48.1%) developed sepsis; of these 51 patients, 27 (25.4%) developed septic shock. Seventy patients (66.0%) developed severe neurological symptoms. Ninety-seven patients (91.5%) were treated with plasma exchange and 50 patients (47.2%) received eculizumab (monoclonal anti-C5 antibody). The mortality rate was 4.7%. Mild residual neurological symptoms were present in 21.7% of patients at ICU discharge, and no patient required renal replacement therapy 6 months after ICU admission., Conclusions: During the 2011 Shiga toxin-producing E. coli-associated hemolytic uremic syndrome outbreak in Germany, critical illness developed rapidly after hospital admission, often in young women. The infection was associated with severe neurological and renal symptoms, requiring mechanical ventilation and renal replacement therapy in a substantial proportion of patients. Overall, recovery was much better than expected.

Background: Autoantibodies against the M-type phospholipase A2 receptor (PLA2R1) are specific markers for primary membranous nephropathy (pMN) and anti-PLA2R1 serum levels may be useful to monitor disease activity. So far, a recombinant cell-based indirect immunofluorescence assay (RC-IFA) using recombinant PLA2R1 as a substrate has been widely available but lacks a finely graduated assessment of antibody concentrations., Methods: In order to setup a standardized ELISA, the extracellular domain of human PLA2R1 was expressed in HEK293. The purified protein was used to form the solid-phase in an ELISA which was then employed to analyze sera from 200 patients with primary MN, 27 patients with secondary MN, 230 patients with other glomerular diseases, 316 patients with systemic autoimmune diseases, and from 291 healthy blood donors., Results: At a set specificity of 99.9% the sensitivity of the anti-PLA2R1 IgG ELISA was found to be 96.5%. A similar sensitivity (98.5%) was obtained when binding of only subclass IgG4 was analyzed. The calibrated assay showed a good class correlation with the results of the RC-IFA, was robust and could be stored for several months without any loss of quality., Conclusion: The results demonstrate that the new test system is qualified for routine use and that it has an almost perfect agreement with both, the clinical characterization of the patients and the results generated with RC-IFA., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Matrix metalloproteinase 9 (MMP9) is a conditionally expressed enzyme and is upregulated in glomerulonephritis. Its function in these diseases, however, remains to be fully elucidated. The induction of nephrotoxic serum nephritis (NTN) in wild-type mice resulted in an upregulation of MMP9, followed by leukocyte infiltration, albuminuria, and subsequent renal failure. MMP9 deficiency ameliorated the course of NTN as indicated by reduced histological injury and reduced infiltration of proinflammatory macrophages. The chemotaxis of MMP9-deficient macrophages in vitro was impaired. Intrarenal macrophages isolated from the kidneys of nephritic MMP9 knockout mice still displayed the typical features of a proinflammatory phenotype and were indistinguishable from wild type-derived cells. Bone marrow transplantation restored renal tissue injury and macrophage recruitment when wild type-derived donor cells were transplanted onto MMP9-deficient mice prior to the induction of NTN. Thus, leukocyte-derived MMP9 mediates the recruitment of proinflammatory macrophages into kidneys during experimental crescentic glomerulonephritis.

Immature renal dendritic cells (DCs) are protective early in murine crescentic GN, but the mechanisms underlying this protection are unknown. Here, depletion of DCs reduced the recruitment of invariant natural killer T (iNKT) cells, which attenuate GN, into the kidney in the early stage of experimental crescentic GN. More than 90% of renal iNKT cells expressed the chemokine receptor CXCR6, and renal DCs produced high amounts of the cognate ligand CXCL16 early after induction of nephritis, suggesting that renal DC-derived CXCL16 might attract protective CXCR6(+) iNKT cells. Consistent with this finding, CXCR6-deficient mice exhibited less iNKT cell recruitment and developed nephritis that was more severe, similar to the aggravated nephritis observed in mice depleted of immature DCs. Finally, adoptive transfer of CXCR6-competent NKT cells ameliorated nephritis. Taken together, these results suggest an immunoprotective mechanism involving immature DCs, CXCL16, CXCR6, and regulatory iNKT cells, which might stimulate the development of new therapeutic strategies for GN.

Shiga toxin-associated hemolytic uremic syndrome (HUS) is an entity of thrombotic microangiopathy characterized by hemolytic anemia, thrombocytopenia, central nervous symptoms, and renal insufficiency. In May 2011, an outbreak of enterohemorrhagic Escherichia coli (EHEC; O104:H4) occurred in Northern Germany. By the end of July 2011, the outbreak was over but nearly 4000 patients had an EHEC infection, 855 cases of hemolytic-uraemic syndrome were reported to the Robert Koch Institute, and there were 35 (4.1%) deaths. Shiga toxin-induced HUS is a rare disease and no controlled clinical trials on therapeutic options are available. First analyses of this outbreak suggest that therapeutic plasma exchange, which was used in the majority of patients, had no benefit and might even be harmful. The role of eculizumab, a monoclonal antibody which inhibits the complement system, is being examined in a multicenter study: the results have not been published yet. Promising is the use of some antibiotics. This would change a paradigm that antibiotics should be avoided. Ongoing and future analyses of the epidemic should be awaited before a final recommendation regarding the different treatment strategies can be made.

The M-type phospholipase A2 receptor (PLA2R) is the major target antigen in idiopathic membranous nephropathy with detectable autoantibodies in the serum of up to 70% of patients. In retrospective studies, the PLA2R-autoantibody titer in the serum was sometimes negative indicating their measurement alone may be inconclusive. In order to better differentiate between primary and secondary membranous nephropathy, we conducted a prospective study that included 88 patients with a histologic diagnosis of membranous nephropathy. Immunohistochemical analysis for PLA2R was faintly positive in kidneys from normal individuals and patients with various other glomerular injuries. In 61 of the 88 patients, PLA2R expression was strongly positive in glomeruli, and in 60 of these patients PLA2R autoantibodies were also detected in the serum. The 27 patients negative for serum PLA2R autoantibodies were faintly positive for PLA2R staining in glomeruli and in 15 of these patients a secondary cause was found. The remaining 12 patients have a yet undetected secondary cause of membranous nephropathy or have different glomerular antigens other than PLA2R. Thus, increased staining for PLA2R in glomeruli of renal biopsies tightly correlates with the presence of PLA2R autoantibodies in the serum and this may help discriminate between primary and secondary membranous nephropathy.

The Th17 immune response appears to contribute to the pathogenesis of human and experimental crescentic GN, but the cell types that produce IL-17A in the kidney, the mechanisms involved in its induction, and the IL-17A-mediated effector functions that promote renal tissue injury are incompletely understood. Here, using a murine model of crescentic GN, we found that CD4(+) T cells, γδ T cells, and a population of CD3(+)CD4(-)CD8(-)γδT cell receptor(-)NK1.1(-) T cells all produce IL-17A in the kidney. A time course analysis identified γδ T cells as a major source of IL-17A in the early phase of disease, before the first CD4(+) Th17 cells arrived. The production of IL-17A by renal γδ T cells depended on IL-23p19 signaling and retinoic acid-related orphan receptor-γt but not on IL-1β or IL-6. In addition, depletion of dendritic cells, which produce IL-23 in the kidney, reduced IL-17A production by renal γδ T cells. Furthermore, the lack of IL-17A production in γδ T cells, as well as the absence of all γδ T cells, reduced neutrophil recruitment into the kidney and ameliorated renal injury. Taken together, these data suggest that γδ T cells produce IL-17A in the kidney, induced by IL-23, promoting neutrophil recruitment, and contributing to the immunopathogenesis of crescentic GN.

Th1 and Th17 subtype effector CD4(+) T cells are thought to play a critical role in the pathogenesis of human and experimental crescentic glomerulonephritis. The time course, mechanism, and functions of Th1 and Th17 cell recruitment, and their potential interaction in glomerulonephritis, however, remain to be elucidated. We performed interventional studies using IL-17- and IFN-γ-gene-deficient mice, as well as neutralizing antibodies that demonstrated the importance of the Th17-mediated immune response during the early phase of the disease. At a later stage, we found that Th1 cells were critical mediators of renal tissue injury. Early recruitment of IL-17-producing Th17 cells triggered expression of the chemokine CXCL9 in the kidney that drove the infiltration of Th1 cells bearing its receptor CXCR3. At a later stage, Th1 cell-derived IFN-γ was found to inhibit local chemokine CCL20 expression, acting through its receptor CCR6 on Th17 cells, thereby limiting the renal Th17 immune response. Thus, our findings provide mechanistic evidence for a cytokine-chemokine-driven feedback loop that orchestrates the observed differential Th1 and Th17 cell infiltration into the inflamed kidney. This contributes to the observed time-dependent function of these two major pathogenic effector CD4(+) T cell subsets in crescentic glomerulonephritis.

Interleukin-17A (IL-17) promotes inflammatory renal tissue damage in mouse models of crescentic glomerulonephritis, including murine experimental autoimmune anti-myeloperoxidase glomerulonephritis, which most likely depends on IL-17-producing Th17 cells. In human anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis, however, the cellular sources of IL-17 remain to be elucidated. Therefore, we analyzed human kidney biopsies of active necrotizing and crescentic ANCA-associated glomerulonephritis by immunohistochemistry using an IL-17-specific antibody and by immunofluorescent colocalization with cell type markers. We detected numerous IL-17-expressing (IL-17(+)) cells in the glomeruli and in the tubulointerstitium. Unexpectedly, most of these IL-17(+) cells were polymorphonuclear neutrophilic granulocytes, while IL-17(+) T cells and IL-17(+) mast cells were present at significantly lower frequencies. IL-17 was not detected in other infiltrating or resident kidney cells. In those patients who had not received immunosuppressive treatment before biopsy, serum creatinine levels were positively correlated with tubulointerstitial IL-17(+) neutrophils as well as IL-17(+) T cells. Furthermore, we could demonstrate that purified human blood neutrophils expressed IL-17 protein and released it upon stimulation in vitro. In conclusion, these results support a pathogenic role for IL-17 in human ANCA-associated glomerulonephritis. Our data suggest that in the acute stage of the disease neutrophils may act as an important immediate-early innate source of IL-17 and may thereby initiate and promote ongoing renal inflammation. IL-17 may thus be a target for treating acute ANCA-associated glomerulonephritis.

Leukocyte infiltration is a characteristic feature of human and experimental lupus nephritis and is closely correlated with loss of renal function. The chemokine receptor CCR5 is expressed on monocyte and T cell subsets and is thought to play an important role in recruiting these cells into inflamed organs. To investigate the functional role of CCR5 in lupus nephritis, CCR5-deficient mice were backcrossed onto the lupus-prone MRL-Fas(lpr) (MRL/lpr) genetic background. Unexpectedly, CCR5(-/-) MRL/lpr mice developed an aggravated course of lupus nephritis in terms of glomerular tissue injury and albuminuria. Deterioration of the nephritis was associated with an overall increase in mononuclear cell infiltration into the kidney, whereas renal leukocyte subtype balance, systemic T cell response, and autoantibody formation were unaffected by CCR5 deficiency. Renal and systemic protein levels of the CCR5 ligand CCL3, which can also attract leukocytes via its alternate receptor CCR1, were significantly increased in nephritic CCR5(-/-) MRL/lpr mice. Further studies revealed that the systemic increase in the CCR5/CCR1 ligand is also observed in nonimmune CCR5(-/-) C57BL/6 mice and that this increase was due to a reduced clearance, rather than an overproduction, of CCL3. Taken together, our data support the hypothesis that CCR5-dependent consumption of its own ligands may act as a negative feedback loop to restrain local chemokine levels within inflamed tissues, thereby limiting inflammatory cell influx.

Background: CCR5 is expressed on infiltrating T cells in hypertensive mice and CCR5 antagonists reduce hypertension making CCR5 an interesting target in treatment of hypertension., Methods: To evaluate the role of CCR5 in hypertensive renal and cardiac end-organ damage, we induced hypertension with desoxycorticosterone acetate (DOCA) and angiotensin II (Ang II) in wild-type (WT) and CCR5-deficient mice., Results: CCR5 expression was increased in renal cortex and cardiac tissue as measured by quantitative PCR. Systolic blood pressure and renal function did not differ between hypertensive CCR5(-/-) and WT mice. DOCA + Ang II induced massive albuminuria and glomerular injury but no difference was found between CCR5(-/-) and WT mice. In addition, no difference was found for renal inflammation as measured by infiltrating T cells, macrophages, and CCL2 expression. The renal expression of the CCR5 ligands, CCL3, and CCL5 was increased in the kidney of hypertensive mice. For CCL3 the increase was significantly higher in CCR5(-/-) than in WT mice. DOCA + Ang II induced cardiac damage as assessed by heart weight, cardiac fibrosis as well as expression of fetal and matrix components but no significant difference was found between CCR5(-/-) and WT mice., Conclusions: CCR5 deficiency does not influence hypertensive renal and cardiac end-organ damage. Cells that infiltrate by expression of CCR5 are either not pathogenic or CCR5-positive leukocytes can migrate via alternative chemokine receptors. Beneficial effects of CCR5 antagonists in hypertension are most likely due to unspecific effects of the antagonists. Possibly, other chemokine receptors in concert with CCR5 are important for hypertensive injury.

Background: Minimal change disease (MCD) is one of the leading causes of nephrotic syndrome. Steroid therapy is effective in achieving remission, but relapses, steroid dependence, and steroid resistance are therapeutic challenges. The use of second-line agents such as cyclophosphamide is associated with toxicity and adverse effects. Therefore, we studied the effect of rituximab (RTX) on proteinuria in adult patients with immunosuppressive (IS)-dependent MCD., Methods: In this single-center, prospective, open series study, 6 consecutive patients with IS-dependent MCD and frequent relapses on different IS regimens - one of them after previous RTX treatment - were included. Patients were treated with a single dose of RTX (375 mg/m²). An additional dose of RTX was administered depending on B-cell count and proteinuria., Results: 5 out of 6 patients achieved complete remission at the end of the follow-up; the other patient had a partial remission. All patients are free of additional IS agents and other medications were remarkably reduced. Three patients had a relapse, which was successfully treated with a further RTX treatment., Conclusions: RTX could be an alternative in the therapy of patients with IS-dependent MCD, leading to successful cessation of other IS treatment.