Identification of Pathogenic Pathways for Recurrence of Focal Segmental Glomerulosclerosis after Kidney Transplantation.

Primary focal segmental glomerulosclerosis (FSGS) is a disease of the podocytes and glomerulus, leading to nephrotic syndrome and progressive loss of renal function. One of the most serious aspects is its recurrence of disease in over 30% of patients following allogeneic kidney transplantation, leading to early graft loss. This research investigates the individual genetic predispositions and differences in the immune responses leading to recurrence of FSGS after transplantation. We performed exome sequencing on six patients with recurrent FSGS to identify variants in fifty-one genes and found significant variations in the alpha-2-macroglobulin (A2M). Immunoblotting was used to investigate effects of specific gene variants at the protein level. Further expression analysis identified A2M, exophilin 5 (EXPH5) and plectin (PLEC) as specific proteins linked to podocytes, endothelial cells, and the glomerulus. Subsequent protein array screening revealed the presence of non-HLA-specific antibodies, including TRIM21, after transplantation. Using Metascape for pathway and process enrichment analysis, we focused on the IL-17 signaling and chemotaxis pathways. ELISA measurements showed significantly elevated IL-17 levels in patients with recurrent FSGS (32.30 ± 9.12 pg/mL) compared to individuals with other glomerular diseases (23.16 ± 2.49 pg/mL; p < 0.01) and healthy subjects (22.28 ± 0.94 pg/mL; p < 0.01), with no significant difference in plasma CCL2/MCP-1 levels between groups. This study explores the molecular dynamics underlying recurrence of FSGS after transplantation, offering insights into potential biomarkers and therapeutic targets for the future development of individualized treatments for transplant patients.

Shedding Light on Viral Shedding: Novel Insights into Nuclear Assembly, Cytoplasmic Transformation and Extracellular Vesicle Release of the BK Virus.

Despite the high prevalence of BK polyomavirus (BKPyV) and the associated risk for BKPyV-associated nephropathy (BKPyVAN) in kidney transplant (KTX) recipients, many details on viral processes such as replication, maturation, assembly and virion release from host cells have not been fully elucidated. VP1 is a polyomavirus-specific protein that is expressed in the late phase of its replicative cycle with important functions in virion assembly and infectious particle release. This study investigated the localization and time-dependent changes in the distribution of VP1-positive viral particles and their association within the spectrum of differing cell morphologies that are observed in the urine of KTX patients upon active BKPyV infection. We found highly differing recognition patterns of two anti-VP1 antibodies with respect to intracellular and extracellular VP1 localization, pointing towards independent binding sites that were seemingly associated with differing stages of virion maturation. Cells originating from single clones were stably cultured out of the urine sediment of KTX recipients with suspected BKPyVAN. The cell morphology, polyploidy, virus replication and protein production were investigated by confocal microscopy using both a monoclonal (mAb 4942) and a polyclonal rabbit anti-VP1-specific antibody (RantiVP1 Ab). Immunoblotting was performed to investigate changes in the VP1 protein. Both antibodies visualized VP1 and the mAb 4942 recognized VP1 in cytoplasmic vesicles exhibiting idiomorphic sizes when released from the cells. In contrast, the polyclonal antibody detected VP1 within the nucleus and in cytoplasm in colocalization with the endoplasmic reticulum marker CNX. At the nuclear rim, VP1 was recognized by both antibodies. Immunoblotting revealed two smaller versions of VP1 in urinary decoy cell extracts, potentially from different translation start sites as evaluated by in silico analysis. Oxford Nanopore sequencing showed integration of BKPyV DNA in chromosomes 3, 4 and 7 in one of the five tested primary cell lines which produced high viral copies throughout four passages before transcending into senescence. The different staining with two VP1-specific antibodies emphasizes the modification of VP1 during the process of virus maturation and cellular exit. The integration of BKPyV into the human genome leads to high virus production; however, this alone does not transform the cell line into a permanently cycling and indefinitely replicating one.

Pregnancy outcomes of Fabry disease in Austria (PROFABIA)-a retrospective cohort-study.

BACKGROUND: Pregnancy and delivery outcomes in women with Fabry disease are not well described. METHODS: Retrospective cohort-study of women with Fabry disease in Austria using a specific questionnaire and the Austrian Mother-Child Health Passport. RESULTS: Out of a total of 44 enrolled women (median age at study entry 44 years, p25: 30, p75: 51), 86.4% showed signs and symptoms of Fabry disease with an increase in pain burden during pregnancy, primarily in women with moderate pain before pregnancy. Thirty-two of 44 women with Fabry disease reported a total of 70 pregnancies (median age at first pregnancy 24 years, p25: 21, p75: 31), 61 (87.1%) of which resulted in 64 live births including 3 sets of twins, six miscarriages (8.6%) in five women, and three induced abortions (4.3%) in two women. Risk factors for poor maternal and foetal outcomes during pregnancy, overrepresented in our cohort as compared to the general population, were hypertension (n = 10, 16.4%), proteinuria (n = 17, 27.9%) and smoking (n = 24, 39.3%). Preeclampsia was reported in 7 pregnancies (11.5%). Fifty-one (79.7%) children were born at term and 13 (20.3%) were preterm (including one neonatal death), with a median gestational age of 39 weeks (p25: 38, p75: 40) and delivery by C-section in 15 pregnancies (24.6%). Thirteen (20.3%) children presented with low birth weight and 18 (28.1%) were small for their gestational age. In comparison to global and national data-sets, preeclampsia, prematurity, low birth weight, being small for their gestational age as well as inpatient stay were significantly more common in patients with Fabry disease. CONCLUSIONS: Our cohort-study in women with Fabry disease shows an increase of pain burden during pregnancies and clearly points to an increased risk for preeclampsia, prematurity, and neonates small for gestational age. With a substantial number of high-risk pregnancies, neonatal outcomes are somewhat worse in Fabry disease than in the general public. Thus, we provide valuable data enabling informed decision-making in pregnancy counselling for Fabry disease.

Rescue From Permanent Kidney Injury in Acute Thrombosis of Both Renal Veins, the Inferior Vena Cava, and Both Iliofemoral Veins by Catheter-Based Thrombectomy.

CASE: A 33-year-old man with previously diagnosed lupus membranous nephropathy presented with painful swelling in both legs. Laboratory tests revealed acute kidney injury, and imaging studies by duplex ultrasound and computed tomography scan showed acute thrombosis of both renal veins, the infrahepatic inferior vena cava, and both iliofemoral venous segments. Initially, pharmacomechanical thrombolysis led to an insufficient morphological result. The therapeutic breakthrough was achieved by catheter-based mechanical thrombectomy of the infrarenal vena cava and both renal veins, which successfully cleared all affected venous segments from thrombus, paralleled by improvement of the patient's condition. However, after 1 week, the patient experienced recurrent thrombosis of the right renal vein with hemorrhagic infarction of the right kidney. After further optimization of immunomodulatory and antithrombotic therapy, a repeated catheter-based mechanical thrombectomy resulted in sustained clinical improvement and preservation of renal venous drainage and kidney function. CONCLUSION: Extensive acute thrombosis of both renal veins, the inferior vena cava, and both iliofemoral venous segments is a rare emergency potentially threatening kidney function. Immediate effective thrombus removal is essential to preserve kidney function and can be achieved by catheter-based mechanical thrombectomy embedded in a comprehensive immunomodulatory and antithrombotic therapeutic concept. CLINICAL IMPACT: This case demonstrated the efficacy of a catheter-based therapeutic approach in patients with extensive thrombosis of the venous system. A catheter-based approach must be embedded in a comprehensive medical therapeutic concept, which is essential to achieve a sustainable result.

Urinary Collectrin as Promising Biomarker for Acute Kidney Injury in Patients Undergoing Cardiac Surgery.

BACKGROUND: Early detection of acute kidney injury (AKI) is crucial for timely intervention and improved patient outcomes after cardiac surgery. This study aimed to evaluate the potential of urinary collectrin as a novel biomarker for AKI in this patient population. METHODS: In this prospective, observational cohort study, 63 patients undergoing elective cardiac surgery with cardiopulmonary bypass (CPB) were studied at the Medical University of Vienna between 2016 and 2018. We collected urine samples prospectively at four perioperative time points, and urinary collectrin was measured using an enzyme-linked immunosorbent assay. Patients were divided into two groups, AKI and non-AKI, defined by Kidney Disease: Improving Global Outcomes Guidelines, and differences between groups were analyzed. RESULTS: Postoperative AKI was found in 19 (30%) patients. Urine sample analysis revealed an inverse correlation between urinary collectrin and creatinine and AKI stages, as well as significant changes in collectrin levels during the perioperative course. Baseline collectrin levels were 5050 ± 3294 pg/mL, decreased after the start of CPB, reached their nadir at the end of surgery, and began to recover slightly on postoperative day (POD) 1. The most effective timepoint for distinguishing between AKI and non-AKI patients based on collectrin levels was POD 1, with collectrin levels of 2190 ± 3728 pg/mL in AKI patients and 3768 ± 3435 pg/mL in non-AKI patients (p = 0.01). CONCLUSIONS: Urinary collectrin shows promise as a novel biomarker for the early detection of AKI in patients undergoing cardiac surgery on CPB. Its dynamic changes throughout the perioperative period, especially on POD 1, provide valuable insights for timely diagnosis and intervention. Further research and validation studies are needed to confirm its clinical usefulness and potential impact on patient outcomes.

Acute Kidney Injury and BK Polyomavirus in Urine Sediment Cells.

Polyomaviruses are widespread, with BK viruses being most common in humans who require immunosuppression due to allotransplantation. Infection with BK polyomavirus (BKV) may manifest as BK virus-associated nephropathy and hemorrhagic cystitis. Established diagnostic methods include the detection of polyomavirus in urine and blood by PCR and in tissue biopsies via immunohistochemistry. In this study, 79 patients with pathological renal retention parameters and acute kidney injury (AKI) were screened for BK polyomavirus replication by RNA extraction, reverse transcription, and virus-specific qPCR in urine sediment cells. A short fragment of the VP2 coding region was the target of qPCR amplification; patients with (n = 31) and without (n = 48) a history of renal transplantation were included. Urine sediment cell immunofluorescence staining for VP1 BK polyomavirus protein was performed using confocal microscopy. In 22 patients with acute renal injury, urinary sediment cells from 11 participants with kidney transplantation (KTX) and from 11 non-kidney transplanted patients (nonKTX) were positive for BK virus replication. BK virus copies were found more frequently in patients with AKI stage III (n = 14). Higher copy numbers were detected in KTX patients having experienced BK polyoma-nephropathy (BKPyVAN) in the past or diagnosed recently by histology (5.6 × 109-3.1 × 1010). One patient developed BK viremia following delayed graft function (DGF) with BK virus-positive urine sediment. In nonKTX patients with BK copies, decoy cells were absent; however, positive staining of cells was found with epithelial morphology. Decoy cells were only found in KTX patients with BKPyVAN. In AKI, damage to the tubular epithelium itself may render the epithelial cells more permissive for polyoma replication. This non-invasive diagnostic approach to assess BK polyomavirus replication in urine sediment cells has the potential to identify KTX patients at risk for viremia and BKPyVAN during AKI. This method might serve as a valuable screening tool for close monitoring and tailored immunosuppression decisions.

Pregnancy in Complement-Mediated Thrombotic Microangiopathy: Maternal and Neonatal Outcomes.

Rationale & Objective: Pregnancy, delivery, and neonatal outcomes in women with complement-mediated thrombotic microangiopathy (cTMA) have not been well described. A better understanding of these outcomes is necessary to provide women with competent pregnancy counseling. Study Design: Cohort study. Setting and Participants: Women with a history of cTMA and pregnancies enrolled into the Vienna thrombotic microangiopathy cohort. Exposure: New onset or relapses of cTMA. Outcomes: Pregnancy, delivery, and neonatal outcomes of pregnancies in women (a) before cTMA manifestation, (b) complicated by pregnancy-associated cTMA (P-cTMA), and (c) after first manifestation of cTMA or P-cTMA. Analytical Approach: Mixed models were used to adjust the comparison of pregnancy, delivery, and neonatal outcomes between conditions (before, with, and after cTMA) for repeated pregnancies using the mother's ID as random factor. In addition, the fixed factors, mother's age and neonate's sex, were used for adjustment. For (sex-adjusted and age-adjusted) centile outcomes, only the mother's age was used. Adjusted odds ratios were derived from a generalized linear mixed model with live birth as the outcome. Least squares means and pairwise differences between them were derived from the linear mixed models for the remaining outcomes. Results: 28 women reported 74 pregnancies. Despite higher rates of fetal loss before the diagnosis of P-cTMA and preterm births with P-cTMA, most of the women were able to conceive successfully. Neonatal development in all 3 conditions of pregnancies was excellent. Pregnancy and neonatal outcomes were better in women with a pregnancy after the diagnosis of cTMA. Limitations: Although our data set comprises a considerable number of 74 pregnancies, the effective sample size is lower because only 28 mothers with multiple pregnancies were observed. The statistical power for detecting clinically relevant effects was probably low. A recall bias for miscarriages cannot be ruled out. Conclusions: Prepregnancy counseling of women with a history of cTMA can be supportive of their desire to become pregnant.

Lessons from Polyomavirus Immunofluorescence Staining of Urinary Decoy Cells.

Decoy cells that can be detected in the urine sediment of immunosuppressed patients are often caused by the uncontrolled replication of polyomaviruses, such as BK-Virus (BKV) and John Cunningham (JC)-Virus (JCV), within the upper urinary tract. Due to the wide availability of highly sensitive BKV and JCV PCR, the diagnostic utility of screening for decoy cells in urine as an indicator of polyomavirus-associated nephropathy (PyVAN) has been questioned by some institutions. We hypothesize that specific staining of different infection time-dependent BKV-specific antigens in urine sediment could allow cell-specific mapping of antigen expression during decoy cell development. Urine sediment cells from six kidney transplant recipients (five males, one female) were stained for the presence of the early BKV gene transcript lTag and the major viral capsid protein VP1 using monospecific antibodies, monoclonal antibodies and confocal microscopy. For this purpose, cyto-preparations were prepared and the BK polyoma genotype was determined by sequencing the PCR-amplified coding region of the VP1 protein. lTag staining began at specific sites in the nucleus and spread across the nucleus in a cobweb-like pattern as the size of the nucleus increased. It spread into the cytosol as soon as the nuclear membrane was fragmented or dissolved, as in apoptosis or in the metaphase of the cell cycle. In comparison, we observed that VP1 staining started in the nuclear region and accumulated at the nuclear edge in 6-32% of VP1+ cells. The staining traveled through the cytosol of the proximal tubule cell and reached high intensities at the cytosol before spreading to the surrounding area in the form of exosome-like particles. The spreading virus-containing particles adhered to surrounding cells, including erythrocytes. VP1-positive proximal tubule cells contain apoptotic bodies, with 68-94% of them losing parts of their DNA and exhibiting membrane damage, appearing as "ghost cells" but still VP1+. Specific polyoma staining of urine sediment cells can help determine and enumerate exfoliation of BKV-positive cells based on VP1 staining, which exceeds single-face decoy staining in terms of accuracy. Furthermore, our staining approaches might serve as an early readout in primary diagnostics and for the evaluation of treatment responses in the setting of reduced immunosuppression.

Complement-Mediated Thrombotic Microangiopathy Related to COVID-19 or SARS-CoV-2 Vaccination.

Introduction: Infectious diseases and vaccinations are trigger factors for thrombotic microangiopathy. Consequently, the COVID-19 pandemic could have an effect on disease manifestation or relapse in patients with atypical hemolytic syndrome/complement-mediated thrombotic microangiopathy (aHUS/cTMA). Methods: We employed the Vienna TMA cohort database to examine the incidence of COVID-19 related and of SARS-CoV-2 vaccination-related relapse of aHUS/cTMA among patients previously diagnosed with aHUS/cTMA during the first 2.5 years of the COVID-19 pandemic. We calculated incidence rates, including respective confidence intervals (CIs) and used Cox proportional hazard models for comparison of aHUS/cTMA episodes following infection or vaccination. Results: Among 27 patients with aHUS/cTMA, 13 infections triggered 3 (23%) TMA episodes, whereas 70 vaccinations triggered 1 TMA episode (1%; odds ratio 0.04; 95% CI 0.003-0.37, P = 0.01). In total, the incidence of TMA after COVID-19 or SARS-CoV-2 vaccination was 6 cases per 100 patient years (95% CI 0.017-0.164) (4.5/100 patient years for COVID-19 and 1.5/100 patient years for SARS-CoV-2 vaccination). The mean follow-up time was 2.31 ± 0.26 years (total amount: 22,118 days; 62.5 years) to either the end of the follow-up or TMA relapse (outcome). Between 2012 and 2022 we did not find a significant increase in the incidence of aHUS/cTMA. Conclusion: COVID-19 is associated with a higher risk for aHUS/cTMA recurrence when compared to SARS-CoV-2 vaccination. Overall, the incidence of aHUS/cTMA after COVID-19 infection or SARS-CoV-2 vaccination is low and comparable to that described in the literature.

Severe nephrotic syndrome and early end-stage diabetic kidney disease in ABCC8-MODY12: A case report.

A 24-year-old man with diabetes mellitus presented with advanced kidney disease and severe proteinuria. Genetic testing revealed ABCC8-MODY12 (OMIM 600509), and a kidney biopsy showed nodular glomerulosclerosis. He commenced dialysis shortly thereafter, and glycemic control improved on treatment with a sulfonylurea. Diabetic end-stage kidney disease in patients with ABCC8-MODY12 has not been reported until now. Thus, our case highlights the risk for early-onset and severe diabetic kidney disease in patients with ABCC8-MODY12 and the importance of timely genetic diagnosis in unusual cases of diabetes to allow for proper treatment and prevention of late sequelae of diabetes.

SARS-CoV-2 IgG spike protein antibody response in mRNA-1273 Moderna® vaccinated patients on maintenance immunoapheresis - a cohort study.

Background: The SARS-CoV-2 pandemic increased mortality and morbidity among immunocompromised populations. Vaccination is the most important preventive measure, however, its effectiveness among patients depending on maintenance immunoglobulin G (IgG) apheresis to control autoimmune disease activity is unknown. We aimed to examine the humoral immune response after mRNA-1273 Moderna® vaccination in immunoapheresis patients. Methods: We prospectively monitored SARS-CoV-2 IgG spike (S) protein antibody levels before and after each IgG (exposure) or lipid (LDL) apheresis (controls) over 12 weeks and once after 24 weeks. Primary outcome was the difference of change of SARS-CoV-2 IgG S antibody levels from vaccination until week 12, secondary outcome was the difference of change of SARS-CoV-2 IgG S antibody levels by apheresis treatments across groups. Results: We included 6 IgG and 18 LDL apheresis patients. After 12 weeks the median SARS-CoV-2 IgG S antibody level was 115 (IQR: 0.74, 258) in the IgG and 1216 (IQR: 788, 2178) in the LDL group (p=0.03). Median SARS-CoV-2 IgG S antibody reduction by apheresis was 76.4 vs. 23.7% in the IgG and LDL group (p=0.04). The average post- vs. pre-treatment SARS-CoV-2 IgG S antibody rebound in the IgG group vs. the LDL group was 46.1 and 6.44%/week from prior until week 12 visit. Conclusions: IgG apheresis patients had lower SARS-CoV-2 IgG S antibody levels compared to LDL apheresis patients, but recovered appropriately between treatment sessions. We believe that IgG apheresis itself probably has less effect on maintaining the immune response compared to concomitant immunosuppressive drugs. Immunization is recommended independent of apheresis treatment.

Tubular epithelial progenitors are excreted in urine during recovery from severe acute kidney injury and are able to expand and differentiate in vitro.

Background: Acute kidney injury (AKI) is a serious condition associated with chronic kidney disease, dialysis requirement and a high risk of death. However, there are specialized repair mechanisms for the nephron, and migrated committed progenitor cells are the key players. Previous work has described a positive association between renal recovery and the excretion of tubular progenitor cells in the urine of kidney transplant recipients. The aim of this work was to describe such structures in non-transplanted AKI patients and to focus on their differentiation. Methods: Morning urine was obtained from four patients with AKI stage 3 and need for RRT on a consecutive basis. Urine sediment gene expression was performed to assess which part of the tubular or glomerular segment was affected by injury, along with measurement of neprilysin. Urine output and sediment morphology were monitored, viable hyperplastic tubular epithelial clusters were isolated and characterized by antibody or cultured in vitro. These cells were monitored by phase contrast microscopy, gene, and protein expression over 9 days by qPCR and confocal immunofluorescence. Furthermore, UMOD secretion into the supernatant was quantitatively measured. Results: Urinary neprilysin decreased rapidly with increasing urinary volume in ischemic, toxic, nephritic, and infection-associated AKI, whereas the decrease in sCr required at least 2 weeks. While urine output increased, dead cells were present in the sediment along with debris followed by hyperplastic agglomerates. Monitoring of urine sediment for tubular cell-specific gene transcript levels NPHS2 (podocyte), AQP1 and AQP6 (proximal tubule), and SLC12A1 (distal tubule) by qPCR revealed different components depending on the cause of AKI. Confocal immunofluorescence staining confirmed the presence of intact nephron-specific epithelial cells, some of which appeared in clusters expressing AQP1 and PAX8 and were 53% positive for the stem cell marker PROM1. Isolated tubule epithelial progenitor cells were grown in vitro, expanded, and reached confluence within 5-7 days, while the expression of AQP1 and UMOD increased, whereas PROM1 and Ki67 decreased. This was accompanied by a change in cell morphology from a disproportionately high nuclear/cytoplasmic ratio at day 2-7 with mitotic figures. In contrast, an apoptotic morphology of approximately 30% was found at day 9 with the appearance of multinucleated cells that were associable with different regions of the nephron tubule by marker proteins. At the same time, UMOD was detected in the culture supernatant. Conclusion: During renal recovery, a high replicatory potential of tubular epithelial progenitor cells is found in urine. In vitro expansion and gene expression show differentiation into tubular cells with marker proteins specific for different nephron regions.

Urinary Collectrin (TMEM27) as Novel Marker for Acute Kidney Injury.

Acute kidney injury (AKI) is a leading complication in hospitalized patients of different disciplines due to various aetiologies and is associated with the risk of chronic kidney disease, the need for dialysis and death. Since nephrons are not supplied with pain signals, kidney injury is mostly diagnosed by serum creatinine with a time delay. Recent work has shown that certain urinary biomarkers are available for early detection of AKI. In total, 155 subjects, including 102 patients with AKI at various stages and 53 subjects without AKI, were enrolled, and their course and laboratory data were recorded. Urinary collectrin (TMEM27) was measured by a commercially available ELISA assay. Changes in serum creatinine were used to determine AKI stage. Patients with AKI presented with significantly lower levels of urinary collectrin compared to patients without AKI (1597 ± 1827 pg/mL vs. 2855 ± 2073; p = 0.001). Collectrin was found to inversely correlate with serum creatinine and stages of AKI. Collectrin levels were lowest in AKI stage III (1576 ± 1686 pg/mL; p = 0.001) and also significantly lower in stage II (1616 ± 2148 pg/mL; p = 0.021) and stage I (1630 ± 1956 pg/mL; p = 0.019) compared to subjects without AKI. An optimal minimum collectrin cut-off value of 1606 [95% CI 1258 to 1954] pg/mL was determined to detect AKI. In conclusion, urinary collectrin represents an indicator of AKI that, unlike all other established AKI biomarkers, decreases with stage of AKI and thus may be associated with a novel pathogenic pathway.

Vaccination with BNT162b2 and ChAdOx1 nCoV-19 Induces Cross-Reactive Anti-RBD IgG against SARS-CoV-2 Variants including Omicron.

SARS-CoV-2 variants of concern (VOCs) have caused a significant increase in infections worldwide. Despite high vaccination rates in industrialized countries, the fourth VOC, Omicron, has outpaced the Delta variant and is causing breakthrough infections in individuals with two booster vaccinations. While the magnitude of morbidity and lethality is lower in Omicron, the infection rate and global spread are rapid. Using a specific IgG multipanel-ELISA with the spike protein's receptor-binding domain (RBD) from recombinant Alpha, Gamma, Delta, and Omicron variants, sera from health-care workers from the Medical University of Vienna were tested pre-pandemic and post-vaccination (BNT162b2; ChAdOx1 nCoV-19). The cohort was continuously monitored by SARS-CoV-2 testing and commercial nucleocapsid IgG ELISA. RBD IgG ELISA showed significantly lower reactivity against the Omicron-RBD compared to the Alpha variant in all individuals (p < 0.001). IgG levels were independent of sex, but were significantly higher in BNT162b2 recipients <45 years of age for Alpha, Gamma, and Delta (p < 0.001; p = 0.040; p = 0.004, respectively). Pre-pandemic cross-reactive anti-Omicron IgG was detected in 31 individuals and was increased 8.78-fold after vaccination, regardless of vaccine type. The low anti-RBD Omicron IgG level could explain the breakthrough infections and their presence could also contribute to a milder COVID-19 course by cross-reactivity and broadening the adaptive immunity.

Preclinical Establishment of a Divalent Vaccine against SARS-CoV-2.

First-generation vaccines against SARS-CoV-2 do not provide adequate immune protection. Therefore, we engineered a divalent gene construct combining the receptor-binding domain (RBD) of the spike protein and the immunodominant region of the viral nucleocapsid. This fusion protein was produced in either E. coli or a recombinant baculovirus system. Subsequently, the fusion protein was mixed with adjuvant and administered to mice in a prime-booster mode. Mice (72%) produced an IgG response against both proteins (titer: 10-4-10-5) 14 days after the first booster injection, which was increased to 100% by a second booster. Comparable IgG responses were detected against the delta, gamma and omicron variants of the RBD region. Durability testing revealed IgGs beyond 90 days. In addition, cytolytic effector cell molecules were increased in lymphocytes isolated from peripheral blood. Ex vivo stimulation of T cells by nucleocapsid and RBD peptides showed antigen-specific upregulation of CD44 among the CD4+ and CD8+ T cells of vaccinated mice. No side effect was documented in the central nervous system. Cumulatively, these data represent a proof-of-principle approach alternative to existing mRNA vaccination strategies.

Eculizumab use in a tertiary care nephrology center: data from the Vienna TMA cohort.

BACKGROUND: Practice patterns of eculizumab use are not well described. We examined indications for, and outcomes of, eculizumab therapy in a tertiary care nephrology center. METHODS: We used the "Vienna TMA cohort" and the hospital pharmacy database at the Medical University of Vienna to identify patients that received eculizumab treatment between 2012 and 2019. We describe clinical characteristics, details of eculizumab use, and outcomes of patients with complement gene-variant mediated TMA (cTMA), secondary TMA (sTMA) and C3 glomerulopathy (C3G). RESULTS: As of December 2019, 23 patients received complement blockade at the Division of Nephrology and Dialysis: 15 patients were diagnosed with cTMA, 6 patients with sTMA and 2 patients with C3G. Causes of sTMA were bone marrow transplantation (n = 2), malignant hypertension, malignant tumor, systemic lupus erythematosus, antiphospholipid syndrome and lung transplantation (each n = 1). Across all indications, patients had a median age of 31 and were predominantly female (78%) and the median duration of treatment was 227 days. Hematological recovery was seen in most patients, while renal response was best in patients with cTMA. Adverse events were recorded in 26%. CONCLUSIONS: In summary, eculizumab is the treatment of choice for cTMA patients that do not respond to plasma therapy. In patients with sTMA and C3G, the response rates to therapy are much lower and therefore, the decision to start therapy needs to be considered carefully.

Urinary C3 levels associated with sepsis and acute kidney injury-A pilot study.

Acute kidney injury (AKI) is an abrupt deterioration of renal function often caused by severe clinical disease such as sepsis, and patients require intensive care. Acute-phase parameters for systemic inflammation are well established and used in routine clinical diagnosis, but no such parameters are known for AKI and inflammation at the local site of tissue damage, namely the nephron. Therefore, we sought to investigate complement factors C3a/C3 in urine and urinary sediment cells. After the development of a C3a/C3-specific mouse monoclonal antibody (3F7E2), urine excretion from ICU sepsis patients was examined by dot blot and immunoblotting. This C3a/C3 ELISA and a C3a ELISA were used to obtain quantitative data over 24 hours for 6 consecutive days. Urine sediment cells were analyzed for topology of expression. Patients with severe infections (n = 85) showed peak levels of C3a/C3 on the second day of ICU treatment. The majority (n = 59) showed C3a/C3 levels above 20 µg/ml at least once in the first 6 days after admission. C3a was detectable on all 6 days. Peak C3a/C3 levels correlated negatively with peak C-reactive protein (CRP) levels. No relationship was found between peak C3a/C3 with peak leukocyte count, age, or AKI stage. Analysis of urine sediment cells identified C3a/C3-producing epithelial cells with reticular staining patterns and cells with large-granular staining. Opsonized bacteria were detected in patients with urinary tract infections. In critically ill sepsis patients with AKI, urinary C3a/C3 inversely correlated with serum CRP. Whether urinary C3a/C3 has a protective function through autophagy, as previously shown for cisplatin exposure, or is a by-product of sepsis caused by pathogenic stimuli to the kidney must remain open in this study. However, our data suggest that C3a/C3 may function as an inverse acute-phase parameter that originates in the kidney and is detectable in urine.