bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2023.04.05.535688

Calcineurin inhibitor nephrotoxicity revisited: perspectives emerging from differential impact on renal compartments

Demirci, H.·Popovic, S.·Dittmayer, C.·Yilmaz, D. E.·El-Shimy, I. A.·Mülleder, M.·Hinze, C.·Mutig, K.·Bachmann, S.
View original source ↗Export metadata ↓

Abstract

Calcineurin inhibitors (CNI) are the backbone for immunosuppression after solid organ transplantation. Although successful in preventing kidney transplant rejection, their nephrotoxic side effects notoriously contribute to allograft injury despite attempts to optimize their application, often with additional medications. Complex renal parenchymal damage occurs for cyclosporine A (CsA) as well as for the currently favoured tacrolimus (Tac). To test for distinct CsA and Tac damaging patterns, we combined multiomics analysis with histopathology from rat kidneys exposed to continuous CNI delivery. Damage forms varied strikingly. Both drugs caused significant albeit differential damage in vasculature and nephron. The glomerular filtration barrier was more affected by Tac than by CsA, showing prominent deteriorations in pore endothelium and podocytes along with impaired VEGF/VEGFR2 signaling and podocyte-specific gene expression. By contrast, proximal tubule epithelia were more severely affected by CsA than by Tac, revealing lysosomal dysfunction and enhanced apoptosis along with impaired proteostasis and oxidative stress. We conclude that pathogenetic alterations in renal microenvironments are specific for either treatment. Should this translate to the clinical setting, CNI choice should reflect individual risk factors for renal vasculature and tubular epithelia. As a step in this direction, we share products identified from multiomics for differential pathognomonic biomarkers. Translational StatementCalcineurin inhibitors (CNI) are first-choice immunosuppressive agents. Their nephrotoxic side effects may often limit their use. Tacrolimus is currently preferred to cyclosporine although its superiority remains unclear. Within the nephron, damage to the filtration barrier is greater for tacrolimus, whereas cyclosporine side effects locate more to the proximal tubular epithelium when compared in our rodent model. We identify the distinctive location and nature of damage by both drugs and unravel involved mechanisms. By detecting differential protein signatures we make available pathognomonic biomarkers for renal allograft health under CNI treatment.

Source connections

Explore related subjects

pathologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Demirci, H., Popovic, S., Dittmayer, C., Yilmaz, D. E., El-Shimy, I. A., Mülleder, M., Hinze, C., Mutig, K., Bachmann, S.. 2023-04-06. Calcineurin inhibitor nephrotoxicity revisited: perspectives emerging from differential impact on renal compartments. https://doi.org/10.1101/2023.04.05.535688

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

NAE1-Dependent Protein Neddylation Preserves Endothelial Identity and Vascular Integrity

Background: Endothelial dysfunction is a central driver of cardiovascular and inflammatory diseases, yet the post-translational mechanisms that preserve endothelial homeostasis remain incompletely understood. Protein neddylation, the covalent conjugation of a ubiquitin-like modifier, regulates diverse cellular processes, yet its physiological role in the vascular endothelium remains unknown. This study investigated whether protein neddylation is required to preserve endothelial identity and vascular homeostasis. Methods: We generated tamoxifen-inducible endothelial-specific Nae1 knockout mice to inhibit neddylation and combined bulk RNA sequencing, single-cell and single-nucleus transcriptomics, quantitative proteomics, biochemical analyses, and gain- and loss-of-function approaches to define the role of endothelial neddylation in vascular homeostasis and inflammatory injury. Results: Endothelial-specific Nae1 deletion caused rapid mortality associated with vascular leakage, platelet accumulation, inflammation, and multi-organ injury. Multi-omics analyses demonstrated profound loss of endothelial identity, characterized by suppression of core endothelial programs and activation of inflammatory, procoagulant, and pyroptotic pathways. Single-cell analyses revealed progressive endothelial dysfunction culminating in depletion of the endothelial population and remodeling of the vascular niche. Mechanistically, endothelial neddylation deficiency activated gasdermin D (GSDMD)- and gasdermin E (GSDME)-dependent pyroptosis, whereas dual inhibition of GSDMD and GSDME markedly attenuated inflammatory transcriptomic remodeling, vascular injury, hepatocyte death, immune cell infiltration, and platelet accumulation. Translational analyses demonstrated reduced endothelial neddylation in experimental endotoxemia and decreased expression of neddylation pathway components in human atherosclerosis and COVID-19 datasets. Conversely, restoration of endothelial neddylation partially reversed inflammatory endothelial transcriptomic reprogramming in vivo. Conclusions: NAE1-dependent protein neddylation is an essential regulator of endothelial identity and vascular integrity. Loss of endothelial neddylation promotes gasdermin-dependent pyroptosis and thrombo-inflammatory vascular injury, whereas restoration of the neddylation pathway mitigates inflammatory endothelial dysfunction. These findings identify endothelial neddylation as a fundamental mechanism maintaining vascular homeostasis and a potential therapeutic target for cardiovascular and inflammatory diseases.

pathology↗
bioRxiv2023

EZH2 inhibition stimulates viral mimicry in resting splenic B cells

In mammalian cells expression of repetitive genomic sequences is repressed by heterochromatin, underscoring the potential threat of repeat expression to cellular homeostasis. However, the specific consequences of ectopic repeat expression remains unclear. Here we demonstrate that EZH2 inhibitors stimulate repeat misexpression and cell death in resting splenic B cells. We show that B cells are uniquely sensitive to these agents because of high levels of H3K27me3 at repeats and correspondingly low DNA methylation. We generated a pattern recognition receptor loss-of-function mouse model called RIC with mutations in Rigi, Ifih1 (MDA5), and Cgas to specifically block the consequences of repeat misexpression. In both WT and RIC mutant B cells, EZH2 inhibition caused focused loss of H3K27me3 at repetitive elements and upregulated their expression. However, expression of inflammatory chemokines and cell death were interrupted by the RIC mutations. Furthermore, the chemokine expression patterns induced by EZH2 inhibitors resemble the B cell response to Epstein-Barr virus infection. This study demonstrates a viral mimicry effect induced by pharmacological activation of repeat expression that induces inflammation and B cell death.

pathology↗
bioRxiv2023

NON-TOXIC ACID-FREE GLYOXAL FIXATIVE FOR VETERINARY HISTOPATHOLOGY, IMMUNOHISTOCHEMISTRY AND MOLECULAR ANALYSIS

Formaldehyde fixation is worldwide the most used system for histopathological examination. However, its toxicity is well known, and preservation of proteins and nucleic acids is not optimal. Alternative fixatives warranting similar morphological quality of tissues and costs, but lacking toxicity and allowing better preservation of proteins and nucleic acids would therefore increase both safety of operators and quality of molecular analysis in pathology. This multi-institutional study aimed to compare the morphological, histochemical, immunohistochemical (IHC), and molecular analyses outcomes of a newly patented, non-toxic, acid-free Glyoxal (GAF) fixative with neutral buffered formaldehyde (NBF). Tissues from a total of 73 subjects were analyzed, including 13 necropsies. Gross features were preserved after GAF fixation, with no tissue hardening or discoloration. Cellular ultrastructure was also better preserved with GAF and histology and histochemistry on GAF-fixed samples showed good results when compared to NBF-fixed samples, with the exception of loss of tinctorial affinity of erythrocytes and mast cell granules. IHC analyses also showed comparable results with only slight and rare protocol adjustment. DNA and RNA yields were higher from GAF-fixed samples (P<0.05) and the tested genes (p53 and COX1) were better amplified. RNA scope showed positive results for c-KIT expression in GAF-fixed mast cell tumors. Based on these data, the non-toxic GAF fixative allows good macroscopical, histological and immunohistochemical analyses of tissue samples, including on-field application, and better molecular analyses when compared to NBF. This represents a promising possibility for teaching, diagnostic, and research in veterinary pathology.

pathology↗