Introduction:
Despite recent progress in the management of the immunological causes of crescentic glomerulonephritis (CGN) (KDIGO 2024), there is still no treatment to reverse the dedifferentiation and proliferation of glomerular cells leading to the formation of crescentic lesions. These events are due to the activation of the epidermal growth factor receptor (EGFR) by de novo expression of heparin-binding EGF-like growth factor (HB-EGF) and its membrane precursor form pro-HB-EGF (Bollée et al., Nat Med 2011). In order to test the capacity of DTR8, a therapeutic protein candidate antagonist of HB-EGF, to prevent the formation of glomerular crescents, we set up a pig model of CGN.
Methods:
The pig model of CGN was based on the administration of sheep immune serum raised against glomerular basement membranes extracted from pig kidney. The sera from 12 sheep were tested by immunofluorescence for their capacity to bind to the podocyte/endothelium interface. Sera giving background labeling of other glomerular structures were discarded. Selected sera were pooled and decomplemented, resulting in a nephrotoxic serum (NTS). Pigs were pre-immunized with sheep IgG at D-6. They received 0.1 and 0.2 mL/kg of NTS intravenously at D0 and D1, respectively. Negative control pigs received decomplemented pre-immune sheep serum instead of NTS. Blood and urine samples were collected at given time points up to D21. At D21, the animals were sacrificed and kidneys were collected for histopathological observations. To test the efficacy of the therapeutic candidate DTR8, 10 pigs of about 30 kg were treated from the afternoon of D1 with 9 mg of DTR8 by intramuscular injection. The following days they received 2 such injections every day, 8 hours apart, except on weekends when they received only one. Twelve control pigs received vehicle only according to the same regimen.
Results:
Pigs receiving NTS developed a nephritic syndrome with high proteinuria, hypoalbuminemia, edema, and crescentic lesions typical of CGN. Podocytes and parietal epithelial cells expressed immunoreactive HB-EGF, lost nephrin expression, and exhibited phosphorylation of the EGFR. Periglomerular lymphocyte infiltration and interstitial fibrosis were observed. Control pigs receiving pre-immune sheep serum lacked these features and had histologically normal glomeruli. DTR8 treatment significantly reduced the percentage of crescentic glomeruli (p=0.037), prevented nephrin loss (p=0.003), EGFR phosphorylation (p=0.016), and interstitial fibrosis (p=0.031) compared to vehicle only.
Conclusions:
We developed a model of CGN in pigs that display biological and histological alterations typical of the human disease. Treatment with the therapeutic protein candidate DTR8, antagonist of HB-EGF, significantly reduced the histopathological damage to kidney glomeruli. Reduction of EGFR phosphorylation highly suggests that DTR8 acts by inhibiting the HB-EGF/EGFR signaling pathway.
Part of these results were presented at ERA 2024 and ASN Kidney Week 2024
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.