General prognostic models may neglect vulnerable subgroups in ANCA-associated vasculitis.

BACKGROUND: ANCA-associated vasculitis is an organ and life-threatening disease with the highest incidence in elderly patients. However, few studies have focussed on characteristics and treatment outcomes in a direct comparison of elderly and younger patients. METHODS: In a retrospective, single-centre, renal biopsy-cohort, patients were dichotomized by age ≥ 65 years to analyse baseline clinical, histological, laboratory and immunological characteristics and outcome differences in elderly and younger patients as regard to mortality, renal recovery from dialysis and eGFR after two years. RESULTS: In the biopsy registry, n = 774 patients were identified, of whom 268 were ≥ 65 years old. Among them, ANCA-associated vasculitis was the most prevalent kidney disease (n = 54 ≈ 20%). After a follow-up of 2 years, overall mortality was 13.4%, with 19% and 4% in patients ≥ and < 65 years of age, respectively. While 41% of elderly and 25% of younger patients were dialysis-dependent at the time of biopsy, renal recovery was achieved in 41% and 57% of patients, respectively. The accuracy of prediction differed significantly between the whole cohort and elderly patients as regard to mortality (sensitivity 46% vs. 90%, respectively) and between younger and elderly patients as regard to eGFR (r2 = 0.7 vs. 0.46, respectively). Age-group-wise analysis revealed patients above 80 years of age to have particularly dismal renal outcome and survival. CONCLUSION: In our cohort, ANCA-associated vasculitis is the single most frequent histopathological diagnosis among the elderly patients in our cohort. Elderly and younger patients have comparable chances of recovering from dialysis-dependent renal failure, with comparable residual independent kidney function after two years. This study suggests (1) relevant predictors differ between age groups and hence (2) models involving all patients with ANCA-associated vasculitis neglect important features of vulnerable subgroups, i.e., patients above 80 years old.

Efficacy of Double Membrane Filtration Immunoadsorption in Severe C1q-Binding Donor-Specific Antibody-Positive Acute Humoral Kidney Allograft Rejection: A Case Series.

INTRODUCTION: Acute antibody-mediated rejection (ABMR) is an important threat to renal allograft survival in the early transplant period and the major single cause of graft loss in the first postoperative year. Semi-selective immunoadsorption (IA) remains one of the commonly applied treatments in ABMR, reducing allo-reactive antibody load. Adding double filtration plasmapheresis (DFPP) to IA might enhance therapeutic efficacy by also addressing innate humoral effectors like complement factors. METHODS: Four patients with ABMR were treated with DFPP + IA. Clinical, histological, and immunological data and adverse events were retrospectively collected. RESULTS: Here we present four high-risk treatment-refractory ABMR cases with C1q-binding donor-specific antibodies and histology of humoral rejection under treatment with DFPP + IA. While the earlier cases (within the first year after transplantation) showed marked reduction in ABMR severity and improvement of kidney function, the later cases did not respond accordingly. Late ABMR patient 1 stabilized, whereas late ABMR patient 2 did not respond to treatment. CONCLUSIONS: Our data support the consideration of DFPP + IA as a rescue treatment option in early, severe, high-risk ABMR cases in which other treatments failed.

IFNγ Causes Keratinocyte Necroptosis in Acute Graft-Versus-Host Disease.

Epidermal keratinocytes form the first-line cellular barrier of the skin for protection against external injuries and maintenance of local tissue homeostasis. Expression of ZBP1 was shown to cause necroptotic keratinocyte cell death and skin inflammation in mice. We sought to characterize the relevance of ZBP1 and necroptosis in human keratinocytes and type 1-driven cutaneous acute graft-versus-host disease. in this study, we identify ZBP1 expression, necroptosis, and interface dermatitis as being the hallmarks of acute graft-versus-host disease. ZBP1 expression was dependent on leukocyte-derived IFNγ, and interference with IFNγ signaling by Jak inhibition prevented cell death. In predominantly IL-17-driven psoriasis, both ZBP1 expression and necroptosis could not be detected. Of note, in contrast to the signaling in mice, ZBP1 signaling in human keratinocytes was not affected by RIPK1's presence. These findings show that ZBP1 drives inflammation in IFNγ-dominant type 1 immune responses in human skin and may further point to a general role of ZBP1-mediated necroptosis.

Development of a new macrophage-specific TRAP mouse (MacTRAP) and definition of the renal macrophage translational signature.

Tissue macrophages play an important role in organ homeostasis, immunity and the pathogenesis of various inflammation-driven diseases. One major challenge has been to selectively study resident macrophages in highly heterogeneous organs such as kidney. To address this problem, we adopted a Translational Ribosome Affinity Purification (TRAP)- approach and designed a transgene that expresses an eGFP-tagged ribosomal protein (L10a) under the control of the macrophage-specific c-fms promoter to generate c-fms-eGFP-L10a transgenic mice (MacTRAP). Rigorous characterization found no gross abnormalities in MacTRAP mice and confirmed transgene expression across various organs. Immunohistological analyses of MacTRAP kidneys identified eGFP-L10a expressing cells in the tubulointerstitial compartment which stained positive for macrophage marker F4/80. Inflammatory challenge led to robust eGFP-L10a upregulation in kidney, confirming MacTRAP responsiveness in vivo. We successfully extracted macrophage-specific polysomal RNA from MacTRAP kidneys and conducted RNA sequencing followed by bioinformatical analyses, hereby establishing a comprehensive and unique in vivo gene expression and pathway signature of resident renal macrophages. In summary, we created, validated and applied a new, responsive macrophage-specific TRAP mouse line, defining the translational profile of renal macrophages and dendritic cells. This new tool may be of great value for the study of macrophage biology in different organs and various models of injury and disease.

Phenprocoumon based anticoagulation is an underestimated factor in the pathogenesis of calciphylaxis.

BACKGROUND: Calciphylaxis is a life threatening complication in renal patients. Of great importance is the identification of concomitant factors for calciphylaxis. Due to the variability of clinical presentation the evaluation of such factors may be obscured when calciphylaxis diagnosis is based just on clinical features. We aimed to characterize associated factors only in patients with calciphylaxis proven by histomorphological parameters in addition to clinical presentation. METHODS: In a single center retrospective study we analyzed 15 patients in an 8 year period from 2008 to 2016. Only patients with clinical features and histomorphological proof of calciphylaxis were included. Criteria for histological diagnosis of calciphylaxis were intimal hyperplasia, micro thrombi or von Kossa stain positive media calcification. RESULTS: The mean age of patients was 64.8 years. Nine patients (60%) were female; 12 (80%) were obese with a Body-Mass-Index (BMI) > 30 kg/m2; 3 (20%) had no renal disease; 12 (80%) had CKD 4 or 5 and 10 (66.7%) had end-stage renal disease (ESRD). One-year mortality in the entire cohort was 73.3%. With respect to medication history, the majority of patients (n = 13 (86.7%)) received vitamin K antagonists (VKA); 10 (66.7%) were treated with vitamin D; 6 (40%) had oral calcium supplementation; 5 (33.3%) had been treated with corticosteroids; 12 (80%) were on proton pump inhibitors (PPI); 13 (86.7%) patients had a clinical proven hyperparathyroidism. Ten (66.7%) patients presented with hypoalbuminemia at diagnosis. CONCLUSIONS: The evaluation of biopsy proven calciphylaxis demonstrates that especially treatment with vitamin K antagonists and liver dysfunction are most important concomitant factors in development of calciphylaxis. As progression and development of calciphylaxis are chronic rather than acute processes, early use of DOACs instead of VKA might be beneficial and reduce the incidence of calciphylaxis.