December 27, 2021 – 20:23
Scar tissue in the kidneys can lead to decreased kidney function
Researchers from Radboudumc and RWTH Uniklinik Aachen in Germany have shown that the SARS-CoV-2 coronavirus infects the kidneys and causes scarring. The infection creates scar tissue in the kidneys with a potentially long-term adverse effect on the kidney function of ex-Covid patients.
It is already known that the coronavirus can cause severe damage to the body and that the kidneys are also a victim of the virus. But we don’t yet know exactly what happens to the kidneys and how much damage there is. In this study, published in Cell Stem Cell, researchers looked at the kidney tissue of deceased COVID-19 patients admitted to intensive care. The tissue contained a lot more scar tissue, more than patients with non-COVID respiratory infection in the intensive care unit or in a healthy control group. Scar tissue can lead to decreased kidney function and, in the worst cases, acute kidney failure.
Small kidneys from the lab
Follow-up question for researchers: What causes kidney damage? Is this due to the virus itself, or to a violent inflammatory response of the immune system? For more insight, the researchers grew small kidneys in the lab, kidney organoids. These transplanted renal organelles come from stem cells and contain different types of kidney cells, but no immune cells. They infected kidney organelles with SARS-CoV-2. In these miniature kidneys, the researchers examined the direct effects of the virus on kidney cells, independent of any effects of the immune system, such as an overreaction. Here, too, as with the patients’ kidney tissue, the researchers saw more scar tissue and signals that lead to the development of scar tissue.
This scar tissue is caused by virus particles that enter the kidney cell during infection. They use the cell as a factory to produce new virus particles, with a mechanism in the cell. This causes great stress to the cell, as it disrupts normal biochemical processes. An inflammatory reaction also occurs in the tissues. This leads to the production of connective tissue and collagen. This creates scar tissue in the kidneys and in the kidney organelles.
Decreased kidney function due to corona virus
The findings of the Dutch and German researchers are in line with those of a large US study, in which researchers saw kidney function decrease due to infection with MERS (Bowe et al, JASN). People who contracted COVID-19 with mild symptoms had a 15 percent greater risk of developing serious kidney problems than people who were not affected by the virus. As a result, patients may end up on dialysis.
Research Team Leader Jitske Jansen from Radboudumc: “With this research, we looked in depth at the cause of kidney damage caused by COVID infection. Infected kidney organelles show that the damage is caused by the virus itself, not just an overreaction of the immune system. This gives us a new piece of the puzzle. Explains the direct damage that the Corona virus can cause in the body.”
Source: Radboudumc and RWTH Uniklinik Aachen
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