The fact that kidneys can get infected by the coronavirus is known, but what exactly happens in the kidney as a result of the infection, remained elusive. Until now. In a new study, published in Cell Stem Cell, a team led by Erasmus MC researchers Rafael Kramann and Rebekka Schneider investigated the kidney tissue of COVID-19 patients admitted to the Intensive Care Unit (ICU). They found more scarring of the tissue as compared to ICU patients with a non-COVID-19 lung infection and a control group of age and comorbidity matched patients.
Next, the researchers questioned what exactly the cause was of the kidney damage. Could this be a direct effect of the virus, independent of systemic inflammation or other systemic effects? To investigate this, the researchers cultured mini kidneys in the lab, called organoids. Kidney organoids are developed from stem cells and contain many different kidney cells, except immune cells. This allowed the researchers to study the direct effect of the virus on kidney cells, independent of potential secondary effects caused by immune cells or other systemic effects.
The researchers infected the kidney organoids with SARS-CoV-2 and found, in line with the COVID-19 patient tissues, scarring of the kidney organoids and accompanied signals that contribute to the scarring process. Importantly, they also showed that a novel drug developed by the COVID Moonshot consortium – an open-science project aiming to develop a drug to treat SARS-CoV-2 – could inhibit the infection of kidney organoids and thus be a potential future therapeutic strategy.
Long term kidney damage
According to the researchers, the scar tissue in the infected kidneys may suggest a possible negative impact on kidney outcomes in the long term. ‘There are some reports that indicate loss of kidney function in COVID-19 survivors and thus it’s likely that a certain percentage of long covid patients might have higher risk of kidney disease. However, since we only included patients that died from COVID after ICU treatment, we can only say this about severe cases’, explains Kramann from Erasmus MC and RWTH Aachen. He co-led the study together with Rebekka Schneider from Erasmus MC and RWTH Aachen, Ivan Costa from RWTH Aachen and Bart Smeets from Radboudumc.
The researchers’ recommendation to ward off kidney damage is to prevent infection by getting vaccinated and boostered, practicing social distancing and wearing masks.