COVID-19-associated nephropathy includes tubular necrosis and capillary congestion, with evidence of SARS-CoV-2 in various segments of the nephron, investigators reported in Kidney 360.
A team led by Antoine Bouquegneau, MD, of ULiège Academic Hospital (ULiège CHU) in Liège, Belgium, performed 16 post-mortem renal biopsies in patients with COVID-19 (mean age 68.2 years; 68.7% males; 100% White) within 3 hours of their deaths and compared the findings with renal biopsy results from 5 control patients who died from unrelated sepsis. Proteinuria occurred in 53.3% of all patients, and acute kidney injury developed in 60% during their hospital stay. In addition, 62.5%, 56.3%, and 42.9% of patients had hypertension, diabetes, and chronic kidney disease, respectively.
On biopsy, all COVID-19 and control cases displayed acute tubular necrosis (ATN) of variable severity, characterized by tubular vacuolization, loss of proximal tubule brush border, cell shedding or apoptosis. However, the investigators observed unusual congestion within the glomerular and peritubular capillaries in 56.3% and 87.5% of cases in the COVID-19 group, whereas only 1 control patient (20%) showed aggregation of erythrocytes in peritubular capillaries. The investigators found no evidence of thrombi or significant glomerular or interstitial inflammation. Notably, all patients had received anticoagulation during their hospital stay and none had received cardiopulmonary resuscitation.
The investigators also detected a positive signal for SARS-CoV-2 in various segments of the nephron such as proximal and distal tubule cells using immunostaining at both the RNA and protein levels. SARS-CoV-2 mRNA was detected in a few glomerular and endothelial cells.
“Our findings strengthen the first histological observations highlighting a preferentially tubular pattern of kidney injury, including ATN lesions and [proximal tubule] vacuolization,” Dr Bouquegneau’s team wrote.
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Bouquegneau A, Erpicum P, Grosch S, et al. COVID-19-associated nephropathy includes tubular necrosis and capillary congestion, with evidence of SARS-CoV-2 in the nephron. Kidney 360. Published online on February 12, 2021. doi:10.34067/KID.0006992020