Myeloperoxidase-ANCA IgG induces different forms of small vessel vasculitis based on type of synergistic immune stimuli.

Anti-neutrophil cytoplasmic autoantibody (ANCA) vasculitis has diverse patterns of injury including microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Necrotizing and crescentic glomerulonephritis (NCGN) occurs in all syndromes and as renal limited vasculitis (RLV). Single-dose intravenous ANCA IgG-specific for mouse myeloperoxidase (MPO) causes RLV in mice. Although multiple mouse models have elucidated ANCA-IgG induced necrotizing and crescentic glomerulonephritis (NCGN), pathogenesis of ANCA-induced granulomatosis and vasculitis outside the kidney has not been clarified. To investigate this, we used intravenous MPO-ANCA IgG in the same strain of mice to induce different patterns of lung disease mirroring patients with granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Repeated intravenous MPO-ANCA IgG induced GPA with NCGN, lung capillaritis, arteritis and granulomatosis. Lung leukocyte phenotypes were evaluated by immunohistochemical image analysis and by flow cytometry. ANCA lung capillaritis and microabscesses began within one day and evolved into granulomas in under seven days. Influenza plus single-dose MPO-ANCA IgG induced MPA with NCGN, lung capillaritis and arteritis, but no granulomatosis. Allergic airway disease caused by house dust mites or ovalbumin plus single-dose intravenous MPO-ANCA IgG induced EGPA with eosinophilic bronchiolitis, NCGN, capillaritis, arteritis, and granulomatosis. Thus, our study shows that the occurrence and pattern of lung lesions are determined by the same ANCA IgG accompanied by different synergistic immune factors.

An unusual etiology in an 8-year-old girl with chest pain and elevated troponin-I.

Acute post-streptococcal glomerulonephritis (APSGN) is the most common glomerulonephritis of childhood, and clinical presentation can vary widely. This case report presents an atypical manifestation of APSGN in an 8-year-old female patient with pleuritic chest pain and elevated troponin-I, despite lacking classical kidney symptoms. Imaging studies showed cardiomegaly and interstitial lung opacities. Further investigations revealed hematuria and proteinuria, and the diagnosis was confirmed through elevated antistreptolysin-O (ASO) titers and low complement 3 (C3) levels. The patient was successfully managed with fluid restriction, diuretics, and antihypertensives, resulting in the resolution of symptoms and normalization of laboratory values. This case highlights the significance of recognizing atypical manifestations of APSGN for ensuring prompt diagnosis and proper management in the pediatric population.

Diagnostic accuracy of ANCA serology in ANCA-associated vasculitis with renal involvement.

BACKGROUND: Pauci-immune glomerulonephritis (GN) due to antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a common cause of crescentic GN. Despite advances in treatment, rates of mortality and progression to end-stage kidney disease remain high. Renal involvement is diagnosed by histological examination of kidney tissue. Serum ANCAs play a significant role in AAV; however, the value of serum ANCA quantification to predict renal involvement is not well-established. AIM: We aimed to evaluate the diagnostic accuracy of serum ANCA titres in diagnosing AAV with renal involvement. METHODS: We conducted a retrospective study of consecutive native kidney biopsies reported at our centre from 2016 to 2021. We included all adults who had both a kidney biopsy and ANCA serology. ANCA serology was tested using indirect immunofluorescence with reporting of titres. Antibodies to proteinase 3 and myeloperoxidase were measured using a chemiluminescent immunoassay. RESULTS: Eight hundred and forty-eight native kidney biopsies were reported during the study period. Five hundred and seven cases were included. The biopsy prevalence of pauci-immune GN in paired samples was 41/507 (8.1%). Most of the cohort had haematuria (66.6%), proteinuria (93.4%) and/or acute kidney injury (65.0%). A positive ANCA at any titre demonstrated a sensitivity of 97.6% and a specificity of 71.2% for a diagnosis of pauci-immune GN. The area under the curve for the receiver operator characteristic was 0.93 (95% confidence interval [CI]: 0.89-0.97). A cutoff ANCA titre of 1:160 provided the optimum balance between a sensitivity of 75.6% (95% CI: 59.7%-87.6%) and a specificity of 94.0% (95% CI: 91.6%-96.0%). CONCLUSIONS: ANCA titres are highly predictive of pauci-immune GN in the appropriate context. While serum ANCA quantitation may not replace renal biopsy, reporting will assist in the decision to start treatment early for patients with organ or life-threatening disease.

Routine cardiac biomarkers for the prediction of incident major adverse cardiac events in patients with glomerulonephritis: a real-world analysis using a global federated database.

RATIONALE & OBJECTIVE: Glomerulonephritis (GN) is a leading cause of chronic kidney disease (CKD). Major adverse cardiovascular events (MACE) are prolific in CKD. The risk of MACE in GN cohorts is multifactorial. We investigated the prognostic significance of routine cardiac biomarkers, Troponin I and N-terminal pro-BNP (NT-proBNP) in predicting MACE within 5 years of GN diagnosis. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: Data were obtained from TriNetX, a global federated health research network of electronic health records (EHR). EXPOSURE OR PREDICTOR: Biomarker thresholds: Troponin I: 18 ng/L, NT-proBNP: 400 pg/mL. OUTCOMES: Primary outcome: Incidence of major adverse cardiovascular events (MACE). SECONDARY OUTCOME: was the risk for each individual component of the composite outcome. ANALYTICAL APPROACH: 1:1 propensity score matching using logistic regression. Cox proportional hazard models were used to assess the association of cardiac biomarkers with the primary and secondary outcomes, reported as Hazard Ratio (HR) and 95% confidence intervals (CI). Survival analysis was performed which estimates the probability of an outcome over a 5-year follow-up from the index event. RESULTS: Following PSM, 34,974 and 18,218 patients were analysed in the Troponin I and NTproBNP cohorts, respectively. In the Troponin I all cause GN cohort, 3,222 (9%) developed composite MACE outcome HR 1.79; (95% CI, 1.70, 1.88, p < 0.0001). In the NTproBNP GN cohort, 1,686 (9%) developed composite MACE outcome HR 1.99; (95% CI, 1.86, 2.14, p < 0.0001). LIMITATIONS: The data are derived from EHR for administrative purposes; therefore, there is the potential for data errors or missing data. CONCLUSIONS: In GN, routinely available cardiac biomarkers can predict incident MACE. The results suggest the clinical need for cardiovascular and mortality risk profiling in glomerular disease using a combination of clinical and laboratory variables.

[Comparison of thrombodynamic methods and routine hemostasis tests in the evaluation of hypercoagulable syndrome in chronic glomerulonephritis].

BACKGROUND: Nephrotic syndrome (NS) is associated with a high risk of thrombotic complications. In this group of patients, routine local tests for assessing hemostasis do not accurately reflect hypercoagulable state. Global functional tests for assessing hemostasis, including thrombodynamics (TD), are considered promising for assessing disorders in the blood coagulation system of these patients. AIM: To compare the rate of hypercoagulability according to routine hemostatic tests and TD and to evaluate the factors associated with increased risk of thrombotic complications in patients with chronic glomerulonephritis (CGN). MATERIALS AND METHODS: The study included 94 patients with active CGN who were not receiving anticoagulant therapy; 63 (80.3%) patients had NS, and 31 (19.7%) had active CGN without NS. Hemostasis parameters were assessed using local coagulation tests and TD test. Using logistic regression analysis, factors associated with the risk of thrombosis were assessed. RESULTS: Of the 94 patients with active CGN in 63 without preventive anticoagulant therapy, hypercoagulability according to routine tests was detected in 6 (9.5%) patients with NS and in 3 (9.7%) patients without NS (p<0.05). Hypercoagulability according to the TD test was detected in 24 (53.9%) patients with NS and in 5 (32.2%) without NS (p<0.05). The formation of spontaneous clots was observed in 29 (30.9%) of patients with CGN, most of them 24 (83%) with NS. 10.6% of patients in our cohort experienced thromboembolic events. The risk of thromboembolic events according to the univariate regression analysis was associated with older age, higher lipid levels, use of glucocorticosteroids and detection of spontaneous clots by the TD test. No association of thromboembolic events with abnormalities in routine hemostasis tests was obtained. CONCLUSION: In patients with CGN with nephrotic syndrome, hypercoagulability is detected in 9.5% of cases with routine coagulation tests and in 53.9% of cases with TD test. Detection of spontaneous clots by TD test is associated with a risk of thromboembolic events.

[Anemia of chronic diseases in the early stages of chronic kidney disease as a risk factor for cardiovascular complications in patients with glomerulonephritis].

AIM: To determine biomarkers of anemia of chronic disease (ACD) in patients with glomerulonephritis (GN) in the early stages of CKD, to assess their role as risk factors for cardiovascular complications (CVС). MATERIALS AND METHODS: Seventy nine patients with GN were studied, among them: 40 with primary сhronic GN (CGN), 39 with secondary forms:19 - GN with ANCA-associated systemic vasculitis, 20 - GN with systemic lupus erythematosus (SLE) at early (all I-II) CKD stages. In all patients, the level of serum C-reactive protein (CRP), hepcidin, interferon γ, and the circulating form of protein Klotho (s-Klotho) were determined. When a relative iron deficiency was detected [transferrin iron saturation coefficient (TSAT) <20%], patients were administered parenterally iron [III] sucrose hydroxide complex (Venofer). RESULTS: The frequency of anemia among patients with systemic diseases is 3.2 times higher than among patients with primary CGN. Patients with anemia (group I; n=43) had higher rates of daily proteinuria (p<0.001), systolic blood pressure (p<0.05), serum levels of interferon γ (p<0.001) and hepcidin (p<0.001) and lower values of eGFR (p<0.05) than patients without anemia (group II; n=36). A strong inverse correlation was noted between the level of hepcidin and the content of iron in serum (r=-0.856; p<0.001), between the level of hemoglobin and the level of interferon γ (r=-0.447; p<0.05), hepcidin (r=-0.459; p<0.05) and CRP (r=-0.453; p<0.05). A significant inverse correlation was found between the level of hemoglobin and CVC risk factors - the value of systolic blood pressure (r=-0.512; p<0.05) and the mass index of the left ventricular myocardium (r=-0.619; p<0.01). At the same time, the contribution of 2 from 6 analyzed factors, hepcidin and eGFR, to the development of ACD was 92.5%, of which 86.6% accounted for hepcidin. A strong direct correlation was also found between a decrease in hemoglobin level and a decrease in the level of s-Klotho protein (r=0.645; p<0.001), a decrease in the level of s-Klotho and an increase in the level of serum hepcidin (r=-0.541; p<0.05). The leading value of anemia (beta -0,29; p=0,04) and depression of the s-Klotho level (beta -0,44; p=0,02) as independent cardiovascular risk factors in this group of patients was confirmed by multivariate analysis. In patients with identified deficiency of iron (n=40), after 3-4 weeks of intravenous administration of venofer, the target level of hemoglobin (Нb>120 g/l) and transferrin saturation with iron (TSAT>20%) were achieved. CONCLUSION: Among the biomarkers of ACD in patients with immunoinflammatory diseases of the kidneys (primary and secondary СGN), the increase in the serum level of hepcidin is greatest importance. The concomitant to anemia decrease in s-Klotho is a leading risk factor for CVС in CKD. Early correction of ACD with iron supplements makes it possible to achieve target levels of Hb and TSAT and have subsequently a positive effect on the production of s-Klotho and the severity of left ventricular hypertrophia.

[Effective substances and mechanism of Yishen Guluo Mixture in treatment of chronic glomerulonephritis based on metabolomics and serum pharmacochemistry].

This study aimed to investigate the effective substances and mechanism of Yishen Guluo Mixture in the treatment of chronic glomerulonephritis(CGN) based on metabolomics and serum pharmacochemistry. The rat model of CGN was induced by cationic bovine serum albumin(C-BSA). After intragastric administration of Yishen Guluo Mixture, the biochemical indexes related to renal function(24-hour urinary protein, serum urea nitrogen, and creatinine) were determined, and the efficacy evaluations such as histopathological observation were carried out. The serum biomarkers of Yishen Guluo Mixture in the treatment of CGN were screened out by ultra-performance liquid chromatography-quadrupole time-of-flight/mass spectrometry(UPLC-Q-TOF-MS) combined with multivariate statistical analysis, and the metabolic pathways were analyzed. According to the mass spectrum ion fragment information and metabolic pathway, the components absorbed into the blood(prototypes and metabolites) from Yishen Guluo Mixture were identified and analyzed by using PeakView 1.2 and MetabolitePilot 2.0.4. By integrating metabolomics and serum pharmacochemistry data, a mathematical model of correlation analysis between serum biomarkers and components absorbed into blood was constructed to screen out the potential effective substances of Yishen Guluo Mixture in the treatment of CGN. Yishen Guluo mixture significantly decreased the levels of 24-hour urinary protein, serum urea nitrogen, and creatinine in rats with CGN, and improved the pathological damage of the kidney tissue. Twenty serum biomarkers of Yishen Guluo Mixture in the treatment of CGN, such as arachidonic acid and lysophosphatidylcholine, were screened out, involving arachidonic acid metabolism, glycerol phosphatide metabolism, and other pathways. Based on the serum pharmacochemistry, 8 prototype components and 20 metabolites in the serum-containing Yishen Guluo Mixture were identified. According to the metabolomics and correlation analysis of serum pharmacochemistry, 12 compounds such as genistein absorbed into the blood from Yishen Guluo Mixture were selected as the potential effective substances for the treatment of CGN. Based on metabolomics and serum pharmacochemistry, the effective substances and mechanism of Yishen Guluo Mixture in the treatment of CGN are analyzed and explained in this study, which provides a new idea for the development of innovative traditional Chinese medicine for the treatment of CGN.

Anti-Factor B Antibodies and Acute Postinfectious GN in Children.

BACKGROUND: The pathophysiology of the leading cause of pediatric acute nephritis, acute postinfectious GN, including mechanisms of the pathognomonic transient complement activation, remains uncertain. It shares clinicopathologic features with C3 glomerulopathy, a complement-mediated glomerulopathy that, unlike acute postinfectious GN, has a poor prognosis. METHODS: This retrospective study investigated mechanisms of complement activation in 34 children with acute postinfectious GN and low C3 level at onset. We screened a panel of anticomplement protein autoantibodies, carried out related functional characterization, and compared results with those of 60 children from the National French Registry who had C3 glomerulopathy and persistent hypocomplementemia. RESULTS: All children with acute postinfectious GN had activation of the alternative pathway of the complement system. At onset, autoantibodies targeting factor B (a component of the alternative pathway C3 convertase) were found in a significantly higher proportion of children with the disorder versus children with hypocomplementemic C3 glomerulopathy (31 of 34 [91%] versus 4 of 28 [14%], respectively). In acute postinfectious GN, anti-factor B autoantibodies were transient and correlated with plasma C3 and soluble C5b-9 levels. We demonstrated that anti-factor B antibodies enhance alternative pathway convertase activity in vitro, confirming their pathogenic effect. We also identified crucial antibody binding sites on factor B, including one correlated to disease severity. CONCLUSIONS: These findings elucidate the pathophysiologic mechanisms underlying acute postinfectious GN by identifying anti-factor B autoantibodies as contributing factors in alternative complement pathway activation. At onset of a nephritic syndrome with low C3 level, screening for anti-factor B antibodies might help guide indications for kidney biopsy to avoid misdiagnosed chronic glomerulopathy, such as C3 glomerulopathy, and to help determine therapy.

C3 glomerulonephritis associated with monoclonal gammopathy: a retrospective case series study from a single institute in China.

OBJECTIVE: To investigate the demographic and clinicopathological features and renal outcomes of Chinese patients with C3 glomerulonephritis in the setting of monoclonal gammopathy. METHODS: Patients with renal biopsy-proven C3 glomerulonephritis and detectable serum and/or urine monoclonal immunoglobulin from 2006 to 2018 in Peking University First Hospital were included, their clinical data, renal pathology type, treatment, and prognosis were collected and analyzed. RESULTS: Nineteen patients were enrolled, accounting for 24% of C3GN patients in the study period. The mean age of onset was 55 years old and the gender ratio was 4/15 (female/male). The mean eGFR at biopsy was 49.55 ± 29.81 ml/min/1.73m2. The prominent clinical manifestations included nephrotic syndrome (58%), anemia (68%), microscopic hematuria and leukocyturia (58%), and hypocomplementemia (13, 68%). The IgG was the most common isotype of monoclonal Ig on immunofixation electrophoresis. Kidney biopsies revealed a relatively prominent MPGN pattern. Only two patients had direct evidence of monocle immunoglobulins acting as C3GN pathogenic factors. Two patients had concurrent TMA-like renal injuries. The median renal survival was 12 and 15 months, respectively in patients receiving conservative therapy and immunosuppressant therapy, without statistical significance. The efficacy of clone-targeted therapy needed further investigation. Plasma exchange therapy only improved one patient's renal outcome. CONCLUSIONS: This is the first case series report of C3GN combined with monoclonal Ig in northern China. The renal prognosis of these patients is poor, and immunosuppressant therapies show no advantage over supportive therapy in renal prognosis, while the benefit of clone-targeted chemotherapy is still requiring investigation.

Complement Components C3 and C4 Indicate Vasculitis Manifestations to Distinct Renal Compartments in ANCA-Associated Glomerulonephritis.

Acute kidney injury (AKI) is a common and severe complication of antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) causing progressive chronic kidney disease (CKD), end-stage renal disease (ESRD) or death. Pathogenic ANCAs, in particular proteinase 3 (PR3) and myeloperoxidase (MPO), trigger a deleterious immune response resulting in pauci-immune necrotizing and crescentic glomerulonephritis (GN), a common manifestation of glomerular injury in AAV. However, there is growing evidence that activation of the complement pathway contributes to the pathogenesis and progression of AAV. We here aimed to compare glomerular and tubulointerstitial lesions in ANCA GN and extrarenal manifestation of AAV in association with levels of circulating complement components C3c and C4. METHODS: Plasma levels of C3c and C4 in a total number of 53 kidney biopsies with ANCA GN were retrospectively included between 2015 and 2020. Glomerular and tubulointerstitial lesions were evaluated according to established scoring systems for ANCA GN and analogous to the Banff classification. RESULTS: We here show that circulating levels of C3c and C4 in ANCA GN were comparable to the majority of other renal pathologies. Furthermore, hypocomplementemia was only detectable in a minor subset of ANCA GN and not correlated with renal or extrarenal AAV manifestations. However, low levels of circulating C3c correlated with AKI severity in ANCA GN independent of systemic disease activity or extrarenal AAV manifestation. By systematic scoring of glomerular and tubulointerstitial lesions, we provide evidence that low levels of circulating C3c and C4 correlated with vasculitis manifestations to distinct renal compartments in ANCA GN. CONCLUSIONS: We here expand our current knowledge about distinct complement components in association with vasculitis manifestations to different renal compartments in ANCA GN. While low levels of C4 correlated with glomerulitis, our observation that low levels of circulating complement component C3c is associated with interstitial vasculitis manifestation reflected by intimal arteritis implicates that C3c contributes to tubulointerstitial injury in ANCA GN.

VISTA deficiency protects from immune complex-mediated glomerulonephritis by inhibiting neutrophil activation.

V-type immunoglobulin domain-containing suppressor of T-cell activation (VISTA) is a negative checkpoint regulator of T cells. We assessed VISTA deficient mice in the murine nephrotoxic nephritis models of acute and chronic immune-complex mediated glomerulonephritis. We show that VISTA deficiency protects from crescentic glomerulonephritis, with no effect on the nephritogenic adaptive immune response. The early neutrophil influx was unaffected but proteinuria was reduced suggesting a reduction in neutrophil activation. In vivo, there was reduced neutrophil degranulation in VISTA deficienct mice and, in vitro, VISTA-deficient neutrophils had an impaired response to immune complexes but not to fMLP or PMA. Mice with a genetic deficiency of neutrophils due to myeloid-specific deletion of myeloid cell leukemia 1 (Mcl-1) were also protected from crescentic glomerulonephritis, indicating an essential role for neutrophils. Therefore, VISTA deficiency inhibits neutrophil activation by immune complexes and neutrophil-dependent crescentic glomerulonephritis. This suggests that VISTA is a therapeutic target for inflammatory disease. However, this would need to be balanced against a potential enhancing effect on autoimmunity.

Basic Research and Clinical Reports Associated with Low Serum IgG4 Concentrations.

Elevated IgG4 concentrations in serum have received a great deal of attention recently, whereas the significance of decreased IgG4 levels was frequently neglected in spite of its close relation with infectious and noninfectious inflammations. In this review, based on the structural and functional characteristics of IgG4, we bring together case reports and research related to low levels of IgG4 and try to scratch the importance of decreased IgG4 concentrations in serum. As with elevated IgG4 levels, low serum IgG4-related diseases can be involved in multiple systems such as infection in the respiratory system, stroke in the circulatory system, and glomerulonephritis in the urinary system. Both genetic and immune dysregulation can contribute to decreased IgG4 levels. In the light of animal experiments, we believe that the mystery of low IgG4 can be revealed as long as enough attention is acquired.

Red Blood Cell Distribution Width is Associated with Glomerulonephritis in Diabetic Patients with Albuminuria.

BACKGROUND The aim of this study was to explore predictive factors to inform accurate diagnosis of glomerulonephritis (GNs) in patients with diabetes. MATERIAL AND METHODS Clinical characteristics and laboratory data were retrospectively analyzed from 200 patients with diabetes including 115 patients who had undergone a renal biopsy. Eligible patients were categorized into three groups: pure type 2 diabetes mellitus (T2DM), isolated diabetic nephropathy (DN), and GN. Odds ratios (ORs) were calculated to evaluate the contributions of predictive factors for GN. A receiver operating characteristic curve (ROC) was created to obtain cut-off values for predictive factors for GNs and investigate their corresponding predictive accuracy. RESULTS Red cell distribution width (RDW) was significantly higher in the GN group than in the DN group. Multivariate regression analysis revealed that baseline RDW level (OR=1.988, 95% CI=1.237~3.194, P=0.005) was an independent predictive factor for development of GNs. CONCLUSIONS Increased RDW levels are independently associated with a greater risk of GN in patients with diabetes who have albuminuria, and may be an additional valuable and noninvasive predictive tool for differentiating GNs and DN.

Shrunken pore syndrome and mortality: a cohort study of patients with measured GFR and known comorbidities.

Shrunken pore syndrome (SPS) is defined by a cystatin C-based estimation of glomerular filtration rate (eGFRCYS) being less than 60% or 70% of a creatinine-based GFR estimation (eGFRCR) in the absence of extrarenal influences on cystatin C or creatinine concentrations. SPS has been associated with a substantial increase in mortality or morbidity in all investigated populations. However, in these studies, neither the diagnoses, nor causes of death were described, and only estimated GFR was available. The present study concerns 2781 individuals with measured GFR (mGFR), known diagnoses, and known causes of death during 5.6 years in median. Cox multivariate proportional hazards regression model was used to estimate hazard ratios (HR) for all-cause and cancer, cardiovascular, diabetes or chronic kidney disease (CKD) as cause-specific mortality among patients with SPS. At an eGFRCYS/eGFRCR-ratio <0.70, the adjusted SPS death risk in the total cohort (HR 3.0, 95% CI 2.4-3.7) was clearly higher than that for the other diagnosis groups. In a sub-cohort of 1300 persons with or without diagnosis, but with normal mGFR, the all-cause mortality of SPS was markedly increased (HR 4.1, 95% CI 2.6-6.5). In a sub-cohort of 567 persons with normal mGFR and no diagnosis, the all-cause mortality of SPS was even more increased (HR 7.3, 95% CI 2.3-23). The prevalence of SPS in the total cohort was 23% and in the sub-cohorts 17 and 12%, respectively. As SPS is associated with a high mortality, occurs in the absence of reduced mGFR and albuminuria, it expands the spectrum of kidney disorders.

Epidemiological features of primary glomerular disease in Turkey: a multicenter study by the Turkish Society of Nephrology Glomerular Diseases Working Group.

BACKGROUND: The largest data on the epidemiology of primary glomerular diseases (PGDs) are obtained from the databases of countries or centers. Here, we present the extended results of the Primary Glomerular Diseases Study of the Turkish Society of Nephrology Glomerular Diseases (TSN-GOLD) Working Group. METHODS: Data of patients who underwent renal biopsy and received the diagnosis of PGD were recorded in the database prepared for the study. A total of 4399 patients from 47 centers were evaluated between May 2009 and May 2019. The data obtained at the time of kidney biopsy were analyzed. After the exclusion of patients without light microscopy and immunofluorescence microscopy findings, a total of 3875 patients were included in the study. RESULTS: The mean age was 41.5 ± 14.9 years. 1690 patients were female (43.6%) and 2185 (56.3%) were male. Nephrotic syndrome was the most common biopsy indication (51.7%). This was followed by asymptomatic urinary abnormalities (18.3%) and nephritic syndrome (17.8%). The most common PGD was IgA nephropathy (25.7%) followed by membranous nephropathy (25.6%) and focal segmental glomerulosclerosis (21.9%). The mean total number of glomeruli per biopsy was 17 ± 10. The mean baseline systolic blood pressure was 130 ± 20 mmHg and diastolic blood pressure was 81 ± 12 mmHg. The median proteinuria, serum creatinine, estimated GFR, and mean albumin values were 3300 (IQR: 1467-6307) mg/day, 1.0 (IQR: 0.7-1.6) mg/dL, 82.9 (IQR: 47.0-113.0) mL/min and 3.2 ± 0.9 g/dL, respectively. CONCLUSIONS: The distribution of PGDs in Turkey has become similar to that in other European countries. IgA nephropathy diagnosed via renal biopsy has become more prevalent compared to membranous nephropathy.

Parvovirus B19 infection and kidney injury: report of 4 cases and analysis of immunization and viremia in an adult cohort of 100 patients undergoing a kidney biopsy.

BACKGROUND: The seroprevalence of human Parvovirus B19 (PVB19) is 70-85% in adults worldwide. PVB19 is the etiologic agent of the fifth disease, is a cause of aplastic anemia, and can be associated with kidney injury. We aimed to describe the cases of 4 patients with kidney injury related to PVB19 primary infection, and to evaluate the seroprevalence of PVB19 and the incidence of PVB19 primary infection in patients undergoing a native kidney biopsy. METHODS: Cases of PVB19 infection with kidney injury were reviewed from the archives of the department of Nephrology. A systematic screening of anti-PVB19 IgG and IgM antibodies and viral DNA was performed in sera from 100 consecutive patients with a kidney biopsy in 2017-2018. RESULTS: The 4 patients with PVB19 infection-associated kidney disease displayed: one lupus-like glomerulonephritis (GN) without lupus auto-antibodies, one minimal change disease with tubular necrosis, one secondary hemolytic and uremic syndrome and one membrano-proliferative GN. In the 100 patients biopsied, 67 had elevated anti-PVB19 IgG, among whom 8 had elevated IgM, without circulating viral DNA, without any particular renal pathological pattern. One additional patient showed a seroconversion at the time of kidney biopsy, which revealed a class V lupus nephritis. CONCLUSION: PVB19 primary infection can be associated with different kidney diseases. The seroprevalence of PVB19 among patients with a kidney biopsy is similar to the overall population, and primary infection is rarely documented (1%) after systematic screening. Whether PV19 is nephrotoxic, or triggers renal endothelial injury and immune activation, remains to be elucidated.

Serum levels of DNAJB9 are elevated in fibrillary glomerulonephritis patients.

Fibrillary glomerulonephritis (FGN) is a rare glomerular disease. Kidney biopsy is required to establish the diagnosis. Recent studies have identified abundant glomerular deposition of DNAJB9 as a unique histological marker of FGN. We developed an immunoprecipitation-based multiple reaction monitoring method to measure serum levels of DNAJB9. We detected a 4-fold higher abundance of serum DNAJB9 in FGN patients when compared to controls, including patients with other glomerular diseases. Serum DNAJB9 levels were also negatively associated with estimated glomerular filtration rate in patients with FGN. Serum DNAJB9 levels accurately predicted FGN with moderate sensitivity (67%) and with high specificity (98%) and positive and negative predictive value (89% and 95%, respectively). A receiver operating curve analysis demonstrated an AUC of 0.958. These results suggest that serum levels of DNAJB9 could be a valuable marker to predict FGN, with the potential to complement kidney biopsy for the diagnosis of FGN.

The TNF-derived TIP peptide activates the epithelial sodium channel and ameliorates experimental nephrotoxic serum nephritis.

In mice, the initial stage of nephrotoxic serum-induced nephritis (NTN) mimics antibody-mediated human glomerulonephritis. Local immune deposits generate tumor necrosis factor (TNF), which activates pro-inflammatory pathways in glomerular endothelial cells (GECs) and podocytes. Because TNF receptors mediate antibacterial defense, existing anti-TNF therapies can promote infection; however, we have previously demonstrated that different functional domains of TNF may have opposing effects. The TIP peptide mimics the lectin-like domain of TNF, and has been shown to blunt inflammation in acute lung injury without impairing TNF receptor-mediated antibacterial activity. We evaluated the impact of TIP peptide in NTN. Intraperitoneal administration of TIP peptide reduced inflammation, proteinuria, and blood urea nitrogen. The protective effect was blocked by the cyclooxygenase inhibitor indomethacin, indicating involvement of prostaglandins. Targeted glomerular delivery of TIP peptide improved pathology in moderate NTN and reduced mortality in severe NTN, indicating a local protective effect. We show that TIP peptide activates the epithelial sodium channel(ENaC), which is expressed by GEC, upon binding to the channel's α subunit. In vitro, TNF treatment of GEC activated pro-inflammatory pathways and decreased the generation of prostaglandin E2 and nitric oxide, which promote recovery from NTN. TIP peptide counteracted these effects. Despite the capacity of TIP peptide to activate ENaC, it did not increase mean arterial blood pressure in mice. In the later autologous phase of NTN, TIP peptide blunted the infiltration of Th17 cells. By countering the deleterious effects of TNF through direct actions in GEC, TIP peptide could provide a novel strategy to treat glomerular inflammation.

Parathyroid Hormone-Related Protein Contributes to Early Healing of Habu Snake Venom-Induced Glomerulonephritis in Mice.

Proliferative glomerulonephritis is characterized by local inflammation and mesangial cell deterioration, followed by mesangial proliferation and glomerular healing. Parathyroid hormone-related peptide (PTHrP) is a mesangial cytokine-like growth factor implicated in mesangial proliferation and survival. No data are available about its role in glomerulonephritis. Herein, we analyzed the expression and role of PTHrP in glomerular inflammation and healing in an experimental model of glomerulonephritis induced by i.v. injection of Habu snake venom in mice. The temporal analysis showed marked renal damage in the first days after venom injection and the beginning of recovery within 7 days. Glomerular expression of PTHrP (transcript and protein) was observed in the early phase after venom injection (from day 1 to day 3), along with an inflammatory environment. The inactivation of secreted PTHrP with PTHrP-neutralizing antibody (PTH2E11; 120 µg i.p. daily) reduced the markers of local inflammation (expression of macrophage chemotactic protein-1; regulated upon activation, normal T cell expressed and secreted; cyclooxygenase 2; IL-6; and macrophage infiltration) and abolished the expression of PTHrP itself. Moreover, the glomerular cell proliferation was hampered, and the healing process was prevented on day 7 after venom injection. These results show that PTHrP has antinomic actions in glomerulonephritis, participating in both the proinflammatory condition and the healing process. Our work reveals the essential role of PTHrP in early glomerular repair in an experimental model of glomerulonephritis.

Proteinase-3 and myeloperoxidase serotype in relation to demographic factors and geographic distribution in anti-neutrophil cytoplasmic antibody-associated glomerulonephritis.

Background: In anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis, antigen specificity varies between myeloperoxidase (MPO) and proteinase 3 (PR3). This has been reported to vary in relation to age, gender, geography and extrarenal manifestations. However, studies are difficult to compare as criteria for inclusion vary. The aim of this study was to investigate the relationship between ANCA serotype, latitude, ultraviolet (UV) radiation levels, age, gender and renal function at diagnosis in a large study with uniform inclusion criteria. Methods: Patients with biopsy-proven ANCA-associated glomerulonephritis were identified from regional or nationwide registries in 14 centres in Norway, Sweden, the UK, the Czech Republic, Croatia, Italy and the USA during the period 2000-13. UV radiation levels for 2000-13 in Europe were obtained from the Swedish Meteorological and Hydrological Institute. Results: A total of 1408 patients (45.2% PR3-ANCA) were included in the study. In univariable analysis, PR3-ANCA was significantly associated with male gender {odds ratio [OR] 2.12 [95% confidence interval (CI) 1.71-2.62]}, younger age [OR per year 0.97 (95% CI 0.96-0.98)] and higher glomerular filtration rate [OR per mL/min 1.01 (95% CI 1.01-1.02); P < 0.001] at diagnosis but not with latitude or UV radiation. In multivariable logistic regression analysis, latitude and UV radiation also became significant, with higher odds for PR3-ANCA positivity at northern latitudes/lower UV radiation levels. However, the latitudinal difference in MPO:PR3 ratio is smaller than differences previously reported concerning microscopic polyangiitis and granulomatosis with polyangiitis. Conclusions: The ratio between PR3-ANCA and MPO-ANCA varies in glomerulonephritis with respect to age, gender, renal function and geographic latitude/UV radiation levels.