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The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic led to rapid vaccine development and large global vaccination schemes. However, patients with immune-mediated kidney disease, chronic kidney diseases and kidney transplant recipients show high non-response rates to vaccination despite more than three vaccinations and, consequently, reduced viral clearance capacity when infected while receiving certain immunosuppressants, carrying an elevated risk for coronavirus disease 2019 (COVID-19)-related morbidity and mortality. SARS-CoV-2 evolution has been characterized by the emergence of novel variants and spike mutations contributing to waning efficacy of neutralizing antibodies. To this end, the therapeutic field expands from vaccination towards a combined approach of immunization, pre-exposure prophylaxis and early post-exposure treatment using direct-acting antivirals and neutralizing monoclonal antibodies to treat early in the disease course and avoid hospitalization. This expert opinion paper from the Immunonephrology Working Group of the European Renal Association (ERA-IWG) summarizes available prophylactic and/or early treatment options (i.e. neutralizing monoclonal antibodies and direct-acting antivirals) of SARS-CoV-2-infected patients with immune-mediated kidney disease, chronic kidney disease and kidney transplant recipients.

Background. Patients on kidney replacement therapy comprise a vulnerable population and may be at increased risk of death from coronavirus disease 2019 (COVID-19). Currently, only limited data are available on outcomes in this patient population. Methods. We set up the ERACODA (European Renal Association COVID-19 Database) database, which is specifically designed to prospectively collect detailed data on kidney transplant and dialysis patients with COVID-19. For this analysis, patients were included who presented between 1 February and 1 May 2020 and had complete information available on the primary outcome parameter, 28-day mortality. Results. Of the 1073 patients enrolled, 305 (28%) were kidney transplant and 768 (72%) dialysis patients with a mean age of 60 ± 13 and 67 ± 14 years, respectively. The 28-day probability of death was 21.3% [95% confidence interval (95% CI) 14.3–30.2%] in kidney transplant and 25.0% (95% CI 20.2–30.0%) in dialysis patients. Mortality was primarily associated with advanced age in kidney transplant patients, and with age and frailty in dialysis patients. After adjusting for sex, age and frailty, in-hospital mortality did not significantly differ between transplant and dialysis patients [hazard ratio (HR) 0.81, 95% CI 0.59–1.10, P = 0.18]. In the subset of dialysis patients who were a candidate for transplantation (n = 148), 8 patients died within 28 days, as compared with 7 deaths in 23 patients who underwent a kidney transplantation Conclusions. The 28-day case-fatality rate is high in patients on kidney replacement therapy with COVID-19 and is primarily driven by the risk factors age and frailty. Furthermore, in the first year after kidney transplantation, patients may be at increased risk of COVID-19-related mortality as compared with dialysis patients on the waiting list for transplantation. This information is important in guiding clinical decision-making, and for informing the public and healthcare authorities on the COVID-19-related mortality risk in kidney transplant and dialysis patients.

Background and Aims Several glomerular disease registries in Europe, and they shared their data; however, there was a lack of current data on trends of primary glomerulopathy in Turkey. Glomerular disease patterns can change geographical areas and populations decade by decade. Our aim is to present Turkey's primary glomerular disease pattern from 2009 to 2017. Method 3878 native kidney biopsy records were assessed in the Turkish Society of Nephrology Glomerulopathy (TSN-GOLD) Working Group Registry. Secondary disease (lupus, etc.) and transplant biopsies do not enroll in the registry. These records divided into four periods, before 2009, 2009 to 2013, 2013 to 2017, and 2017 to current. Results A total of 3858 patients (M = 2173, K = 1685) were examined. There was no difference in the distribution of number of patients according to periods (Q1 = 968, Q2 = 960, Q3 = 968, Q4 = 962). Nephrotic syndrome was the most common biopsy indication in all quarters (58.6%, 53%, 44.1%, 51.6%, respectively). Glomerulopathy types; Membranous GN (29.9%, n = 290) was the first in Q1 and IgA nephropathy (17.7%, n = 172) was the second. IgA nephropathy (28.5%, n = 274) was the most common glomerulopathy in Q2, while Membranous GN (25.5%, n = 245) was the second most common. IgA nephropathy (29.9%, n = 285) was the most common glomerulopathy in Q3, followed by FSGS (22.9%, n = 222) and Membranous GN. In Q4, FSGS (26.8, n = 258) was the most common glomerulopathy, followed by IgA nephropathy (26.7%, n = 257) and Membranous GN (24.5%, n = 236) (Figure 1). Conclusion While biopsy indications did not change over the years, the incidence of FSGS and IgA nephropathy gradually increased.

Background and Aims The combination of new onset haematuria, proteinuria and declining GFR, often referred to as the nephritic syndrome, constitute a strong indication for renal biopsy. Several different disease entities can underlie these findings, many of them requiring prompt treatment. Epidemiological studies of glomerular diseases are in general hampered by the strong influence of differences in biopsy practices. However, there is reason to believe that such differences are less pronounced in cases of acute/subacute nephritic syndrome. The aim of the present study is to compare the frequencies of diseases causing the nephritic syndrome in Japan and Europe using data from renal biopsy registries. Method Data were retrieved from national or regional renal biopsy registries in Japan, Sweden, Norway, Scotland, Austria, Croatia and Turkey from 2007-01-01 to 2018-12-31. Only patients biopsied due to acute or subacute nephritic syndrome, defined as a combination of new onset haematuria, sub-nephrotic proteinuria and reduced GFR, were included. Demographic, clinical and laboratory data were collected from the time of renal biopsy. Results A total number of 2789 patients from Japan and 1202 patients from Europe were included. Among the Japanese patients, 46% were women, median age was 67 years (IQR 54-74) and median creatinine concentration at the time of renal biopsy was 198 µmol/L (IQR 109-343). In Europe, 43% were women, median age was 58 years (IQR 42-70) and median creatinine concentration was 210 µmol/L (IQR 127-390). Figures from the different European countries are presented in Table 1. The most common diagnosis in both Japan and Europe was ANCA-associated nephritis (44% in Japan, 34% in Europe), followed by IgA nephritis (8.5% in Japan, 18.6% in Europe) and acute tubulointerstitial nephritis (6.2% in Japan and 7.1% in Europe). Conclusion We describe preliminary data from a large multicenter cohort of patients presenting with the nephritic syndrome. This clinical presentation is most often encountered in the 6th and 7th decade of life and the distribution between men and women is fairly equal. The most common underlying cause of the nephritic syndrome in both Japan and Europe is ANCA-associated nephritis.

Background and Aims Hematuria is one of the most common laboratory findings in nephrology practice. In different regions of the world, the etiologic causes differ. To date, there is no enough data regarding the clinical and histopathologic characteristics of primary glomerular diseases (PGD) patients with hematuria in our country. Method Data were obtained from national multicenter (47 centers) data entered into the Turkish Society of Nephrology Glomerular Diseases (TSN-GOLD) database between May 2009 and June 2019. The data of all PGD patients over the age of 16 years who were diagnosed with renal biopsy and had hematuria data were included in the study. The biopsy samples were processed using a light microscopy and immunofluorescence examination. Demographic characteristics such as age, sex, indications for biopsy, primary glomerular diseases, comorbidities, laboratory and biopsy findings of all patients were also recorded. Hematuria was defined as the presence of at least 5 red blood cells/hpf. Results Data of 3394 patients were included to the study after the exclusion of patients with secondary glomerulonephritis and patients with missing biopsy findings. While 1699 (50.1%) patients had hematuria, 1695 (49.9%) patients did not have hematuria. Demographic, laboratory, and histopathological characteristics of patients with and without hematuria are given in Table. Patients with hematuria had statistically higher systolic blood pressure (SBP), serum blood urea nitrogen, creatinine, albumin, levels and urine pyuria, however, these patients had statistically lower age, body mass index, presence of hypertension and diabetes, eGFR, 24-hour proteinuria, serum total, HDL and LDL-cholesterol and C3 levels when compared with patients without hematuria. Figure depicted the etiologic causes of patients with and without hematuria. According to histopathological findings, number of global sclerotic glomeruli, cellular and fibrocellular crescents, the levels of mesangial proliferation, endocapillary proliferation, exudative changes in glomeruli, severe tubular atrophy, interstitial inflammation, subendothelial deposition, moderate and severe IgA and C3 deposition were found to be significantly higher and the levels of basal membrane thickening, interstitial fibrosis, subepithelial deposition, severe IgG staining were found to be significantly lower in patients with hematuria. Conclusion This is the first multicenter national report regarding the demographic and histopathologic data of PGD patients with or without hematuria. Hematuria, a feature of nephritic syndrome, was found at a higher than expected in the PGDs presenting with nephrotic syndrome in our national database.

Background and Aims According to the data of the Turkish Society of Nephrology-Glomerular Diseases Working Group (TSN-GOLD Working Group), IgA nephropathy is the most common primary glomerular disease in Turkey. The purpose of this study was to investigate the epidemiological and clinical data of IgA nephropathy patients in Turkey. Method 4399 patients with primary glomerular diseases from 47 centers who were followed up between May 2009 and May 2019 were included in the study conducted by TSN-GOLD Working Group. 524 patients were excluded due to lack of pathological data. Among the remaining patients, demographic, clinical and laboratory data of 994 patients with IgA nephropathy were analyzed. Results The median age of the patients was 37 (28-47) years, and 37.3% of them were female. The laboratory and clinical data at the time of diagnosis is presented in Figure-1, and biopsy indications are described in Figure-2. The median number of glomeruli was 16 (IQR: 3.5-4.3), sclerotic glomeruli was 2 (IQR: 1-5), and segmental sclerotic glomeruli was 1 (IQR: 1-2). Exudative changes, subendothelial and subepithelial deposition were present in 566 patients (56.9%), 46 patients (4.6%) and in 38 patients (3.8%), respectively. 662 (66.1%) and 611 of the patients (61.4%) had tubular atrophy and interstitial fibrosis in varying degrees, respectively. 672 (%67.6) and 416 patients (%41.9) had interstitial inflammation and vascular changes, respectively. In immunofluorescence staining, 18%, 30.1%, 4.4%, 68% of the patients had IgG, IgM, C1q and C3 positivity, respectively. Crescentic glomeruli were detected in 227 patients (3.3 ± 3.1 glomeruli). Patients with crescentic glomeruli had significantly higher proteinuria and lower eGFR than the patients without [2203 mg/day (15-26078) vs 1807 mg/day (15-29112); p=0.001; 55.3 ml/min/1.73 m2 (3.72-141.9) vs 72 ml/min/1.73 m2 (3.84-150.81); p Conclusion In this study we found that, the most common presentation of IgA nephropathy patients in our country was asymptomatic urinary abnormalities followed by nephritic and nephrotic syndrome. Higher proteinuria and lower eGFR values in patients with crescentic glomeruli, support the adoption of crescentic lesions in the new Oxford classification (MEST-C) to predict more precise outcome of IgA nephropathy patients. The high number of patients to whom the Oxford classification was applied provided us with the opportunity to examine the clinical reflections of pathological features. Evaluation of the follow-up data of the patients will give us the possibility to reveal the effect of initial clinical and pathological features on clinical findings and renal outcome.

Background and Aims In IgA nephropathy (IgAN), which is characterized by mesangial IgA accumulation, there is the formation of circulating autoantibodies against galactose deficient IgA1s (Gd-IgA1). IgG / Gd-IgA1 immunocomplexes accumulate in the glomerular mesangium and play a role in the pathogenesis of IgAN. Recent studies have suggested a relationship between glomerular IgG deposition and the severity of glomerular inflammation. However, detection of the presence and severity of IgG in routine immunofluorescence microscopy (IFM) may fail. This study aims to investigate whether IgG positivity detected by IFM is associated with poor renal prognostic indicators and whether renal prognosis can be predicted according to IgG positivity. Method 4399 patients who were enrolled between May 2009-June 2019 in database of Turkish Society of Nephrology, Glomerular Diseases Working Group (TSN-GOLD) including 44 centers were evaluated. After exclusion criteria, 994 primary IgAN patients were included in the study. Glomerular IgG negative and positive patients were compared by means of Oxford classification scores, histopathological evaluations, proteinuria, creatinine, albumin, blood pressures. IgG positive patients were divided into subgroups according to the grade of the IFM positivity. The relationship between IgG positivity and poor prognosis criteria were evaluated. Results Demographic and biochemical findings of glomerular IgG positive and negative patients at the time of biopsy are shown in Table 1. No difference was found between the groups. There was no difference in the demographic and biochemical findings at the time of biopsy in IgG subgroup analyses (Table 2). There was no difference between the histopathological and Oxford MEST scores of the subgroups. Glomerular IgG positivity was not associated with diastolic blood pressure, systolic blood pressure, urea, uric acid, age, eGFR, albumin, proteinuria (p> 0.05 for all, r= -0.084, r= -0.102, r= -0.006, r=0.062, r= 0.014, r= -0.044, r= -0.061, r= -0.066, r= 0.150, respectively). Conclusion Glomerular IgG positivity detected by routine IFM in IgAN is not associated with poor renal prognostic indicators. It is difficult to predict renal prognosis by looking at the severity of IgG positivity at the baseline evaluation.

Background and Aims Rapidly progressive glomerulonephritis (RPGN) is a clinical condition that develops due to different etiologic causes, characterized by a rapid and progressive decrease in renal function and progresses to end-stage renal failure in weeks to months if not treated. In our study, diagnostic and demographic characteristics of patients diagnosed with RPGN by biopsy, clinical and laboratory findings in our country were investigated. Method Data were obtained from national multicenter (47 centers) data entered into the Turkish Society of Nephrology Glomerular Diseases (TSN-GOLD) Working Group database between May 2009 and June 2019. Demographic characteristics such as age, sex, indications for biopsy, diagnosis of the glomerular diseases, comorbidities, laboratory and biopsy findings of all patients were recorded. The data presented is cross-sectional and includes application data for the biopsy period. According to their types, RPGN patients were classified as type 1 (anti-GBM related), type 2 (immunocomplex related) and type 3 (immune-negative; “pauci-immune”). Results After exclusion of 46 patients with missing data, 200 patients (mean age 47.9 ± 16.7 years, 44% female) were included in the study which constitutes 5.2% of the total glomerulonephritis database (total number of patients: 3875). Hypertension was present in 62 patients (31.0%) and diabetes was present in 18 patients (9.0%). Renal biopsy was performed in 147 (73.5%) patients due to nephritic syndrome (RPGN included). 80.2% of the patients' biopsies were performed in nephrology clinics and 19.8% of them were performed in radiology clinics. ANCA positivity was found in 121 (60.5%) patients (proteinase 3-ANCA was positive in 55 and myeloperoxidase-ANCA positive in 66 patients). Type 1 RPGN was detected in 11 (5.5%), type 2 RPGN in 42 (21%) and type 3 RPGN in 147 (73.5%) patients. In 21 patients (10.5%), biopsy revealed RPGN with advanced chronic changes (fibrous global sclerotic glomeruli, advanced interstitial fibrosis and tubular atrophy). Mean serum creatinine was 4.2 ± 3.4 mg/dl, median glomerular filtration rate was 18 (10-37) ml/min and proteinuria 2100 (1229-3526) mg/day according to CKD-EPI formula. The mean number of glomeruli in the biopsies was 18.8 ± 10.6 and the number of crescentic glomeruli was 9.9 ± 7.7 (ratio: 52.7%) (Figure). The patients were divided into 3 groups according to their crescentic glomeruli ratios. The proportion of crescentic glomeruli is 10-50% in group 1, 50-80% in group 2, and >80% in group 3. The demographic, laboratory and histopathological characteristics of the groups are given in Figure. It was observed that urea and creatinine increased and calcium and hemoglobin decreased with increasing crescentic glomerular ratio. Conclusion Our study provides valuable demographic, clinical, laboratory and histopathological data about RPGN in our country. Our data are generally compatible with the literature. In our study, advanced chronic histopathological findings were prominent in the biopsy of 21 patients. Early biopsy should be performed to confirm the diagnosis of RPGN and to avoid unnecessary intensive immunosuppressive therapy. In addition to the treatments applied, detailed data, including patient and renal survival are needed.

Background and Aims Fabry Disease (FD) is a lysosomal glycosphingolipid storage disorder. Kidneys are affected in FD. Despite enzyme replacement theraphy (ERT), some patient still have an ongoing deterioration of renal functions probably secondary to inappropriate immune responses. There is no data regarding NK cell subtypes and the exact relation with B-T lymphocytes and NK cells in patients with FD. We aimed to analyze subtypes of NK cells in patients with FD and compared these results with healthy subjects. Additionally, we analyzed the renal biopsy (RBx) materials of our patients prior to ERT in terms of B, T and NK cell infiltration and compared these cells in some of our FD patients after 4 years of ERT. Method 15 patients with FD and 10 healthy controls were included in the study. Of 15 patients, 8 patients were receiving agalsidase alfa or beta. Blood samples obtained from both group were taken into 2 ml EDTA tube to evaluate peripheral NK cell subgroups according to CD56 and CD16 expression and CD3, CD4, CD8 expression to determine subtypes T cells. These cells were evaluated by flow cytometry technique. The RBx of 10 patients with FD were evaluated before ERT and 3 were reevaluated after 4 years of ERT in terms of T-B, NK and plasma cells infiltration of kidney. The paraffin blocks of specimens were examined with HE, PAS, Masson-trichrome and toluidine blue staining and frozen blocks were examined with red-oil 10 staining Results The characteristics of patients with FD and healthy controls are depicted in Figure 1. Except proteinuria, there were no significant differences in terms of biochemical parameters between two groups. According to flow-cytometric analyses, total percentage of NK and T helper 1, 2, 17 and Treg cells of FD patients are similar to controls (Fig 1). When we analyzed subgroups of NK cells and determined that CD56dimCD16dimNK cells were increased, however, CD56dimCD16brightNK cells were decreased in patients with FD compared to controls (Fig1). We performed RBx of 10 patients. The percentages of CD3, 4, 8 positive Tcells, CD19, CD20 positive B cells, CD 16, 56 positive NK cells and CD 138 positive plasma cell infiltration are shown in Fig 2. According to RBx findings prior to ERT, all patients had interstistial fibrosis (IF), podocyte vacuoles (PV), podocyte inclusion (PI), CD3, CD4, CD16, CD56 positivity at different levels. In contrast, almost none of the patients had CD19, CD20, CD138 positivity. We rebiopsied 3 patients after 4 years of ERT and reevaluated specimens in terms of IF, global and segmental sclerosis (SS), PV, PI and the percentages of CD3, CD4, CD16, CD56, CD 19, CD 20, CD 138 positivity. 2 rebiopsied patients from the same family had increased serum creatinine and proteinuria despite 4 years of regular ERT. In the second biopsy of these two patients, we found that global sclerosis (GS), IF and PI are increased and abundant CD19, CD20 and CD 138 positive cells were seen which were almost absent in the first biopsy. The other patient from another family, had mildly increased proteinuria and had no creatinine increment after 4 years of ERT. In this patient, we found that GS, SS, IF, PI and arterial sclerosis were increased, however CD 3, 4, 8 positive T cells were decreased and no changes in the percentage of CD16, 56 positive NK cells. We could not demonstrate CD 19, 20, 138 positivity in the latter patient. Conclusion Our group, for the first time, demonstrated that CD56dimCD16dimsubtype of NK cells is increased in FD which is closely associated with cellular cytotoxity in normal population. Additionaly, CD 19 and CD 20 positive B cell infiltration are increased and glomerular and interstitial changes are advanced in some patients with ongoing kidney function deterioration despite 4 years of regular ERT. Hence, infiltration of Bcells in the kidneys of patients under ERT might change our therapeutic approaches in the near future. Further studies are needed to clarify the exact roles of B T and NK cells in FD.

Background and Aims Therapeutic plasma exchange (PEX) has an increasingly long list of indications in recent years, in addition to immunosuppressive therapies in many life-threatening immune activations, it provides significant improvements in mortality and morbidity. In this study, we aimed to investigate the laboratory and clinical effects of PEX performed with nephrologic indication in our clinic. Method The records of 67 patients (36 females, 31 males; mean age, 45.7±15.8 years) who underwent PEX with nephrological indication between 2012 and 2017 in our clinic were retrospectively reviewed. Characteristics of the patients such as, indications of PEX, laboratory values and number of PEX sessions were recorded. In addition, clinical responses were also evaluated. Results When a total 398 PEX sessions were examined, the most common indication (40.3%) was acute humoral rejection after renal transplantation, followed by granulomatosis with polyangiitis (19.4%) and thrombotic microangiopathy (9%), respectively. The average of the PEX sessions was 5.94. There was a statistically significant increase in the bicarbonate value when the arterial blood gas of the patients was evaluated after PEX (p=0.002). However, no significant difference was observed in the pH and ionized calcium values (p=0.135, p=0.969, respectively) (Table 1). When all the patients were evaluated, there was no significant change in hemoglobin values (p=0.174), but platelet values decreased significantly (p=0.011) after PEX. However, when the patient group admitted with thrombotic microangiopathy was examined, it was observed that platelet count increased and LDH level decreased significantly (p=0.063, p=0.028, respectively). When the serum creatinine values of all patients were evaluated, a significant decrease was observed in the serum creatinine values after PEX (p=0.001). In addition, after 2 years following PEX treatment, 70.1% of patients were still alive and 12.5% of patients undergoing PEX for acute humoral rejection were undergoing on hemodialysis treatment. Conclusion According to the results of our study, patients should be followed up especially for acid-base and electrolyte changes after PEX. In addition, therapeutic PEX might be effective in terms of improving morbidity and 2 year-mortality of these patients.

Background and Aims The largest data on the epidemiology of primary glomerular diseases (PGD) are obtained from the databases of countries or centers. Here, we presented the extended results of the Primary Glomerular Diseases Study of the Turkish Society of Nephrology Glomerular Diseases (TSN-GOLD)Working Group. Method The data of patients who underwent renal biopsy and diagnosed as primary glomerular disease were recorded in the database prepared for the study. Between May 2009 and May 2019, a total of 4399 patients from 47 centers were evaluated. Basal data of 3875 patients were analyzed after exclusion of those lacking light microscopy and immunofluorescence findings. Results The mean age was 41.5 ± 14.9 years. Of the patients, 1690 were female (43.6%) and 2180 (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 PGH was IgA nephropathy (25.7%), followed by membranous nephropathy (25.6%) and FSGS (21.9%). The mean total number of glomeruli per biopsy was 17 ± 10. Mean baseline systolic blood pressure was 130 ± 20 mmHg and diastolic blood pressure was 81 ± 12 mmHg. Median proteinuria was 3300 (IQR: 1467-6307) mg / day, mean serum creatinine, estimated GFR and albumin values were 1.4 ± 1.5 mg / dl, 80.7 ± 39.1 ml / min and 3.2 ± 0.9 g / dl, respectively. Conclusion In Turkey, the incidence of IgA nephropathy patients have become more common than membranous nephropathy among PGD patients diagnosed with renal biopsy.