SARS-CoV-2 can cause gastrointestinal problems
The most common symptoms of the COVID-19 disease caused by the SARS-CoV-2 coronavirus are fever, cough, runny nose, headache and body aches, fatigue and scratchy throat. In addition, there may be a temporary loss of smell and taste or pneumonia with shortness of breath and shortness of breath. It is now known that gastrointestinal problems can also occur. According to the researchers, such effects indicate a severe course.
Since SARS-CoV-2 only spread to humans relatively recently, experts only learn more about their behavior and the medical consequences of the infection in the course of the current pandemic. So far, COVID-19 has mainly focused on respiratory and lung symptoms, but an infection with the virus can also lead to gastrointestinal complaints.
Indication of severe disease
At the beginning of the coronavirus pandemic, COVID-19 was considered a pure respiratory disease with symptoms ranging from coughing to pneumonia. But now completely different symptoms are known, including nausea and diarrhea.
Like Ulm University in a current one Message reported, such effects on the gastrointestinal tract even indicate a severe course. Molecular insights into the infection process with SARS-CoV-2 in the intestinal model is provided by a study that was recently published in the specialist journal “Cellular and Molecular Gastroenterology and Hepatology“Has appeared.
The authors of the Ulm University Medical Center also used “mini intestines” made from stem cells to examine the antiviral potential of drugs such as remdesivir in the digestive tract.
Viral load in the stool is particularly high
When researching COVID-19, the focus was initially on the lungs, because, according to the report, around 20 percent of those infected develop severe, possibly fatal pneumonia.
However, SARS-CoV-2 multiplies in many other organs. Around half of the patients show symptoms of the gastrointestinal tract such as diarrhea or nausea – many of them are seriously ill.
As the experts explain, it was noticeable in this context that the viral load in the stool of infected people is particularly high. Even days after a negative corona test result using a nasopharynx swab, the pathogen can therefore be detected in stool samples. Future treatment strategies against SARS-CoV-2 should therefore also be effective in the gastrointestinal tract.
Researchers used “mini casings”
A research team from Ulm led by the virologist Professor Jan Münch and the gastroenterologist Professor Alexander Kleger examined the molecular processes involved in a coronavirus infection in the gastrointestinal tract.
“An infection with SARS-CoV-2 is only possible if the ACE2 receptor, to which the virus can dock, and the TMPRSS2 protease are present in the tissue. In healthy intestines, we found these proteins consistently and particularly frequently in the duodenum, ”explains Professor Jan Münch from the Institute for Molecular Virology at the Ulm University Hospital.
In the next step, the scientists wanted to find out which cells in the digestive tract can be infected with the coronavirus. They used so-called organoids, which are grown from embryonic stem cells.
“These ‘mini intestines’ from the laboratory come very close to the human small intestine and have large numbers of the necessary docking points,” explains Dr. Sandra Heller, biologist at the University Clinic for Internal Medicine I. The researchers exposed these organoids to the coronavirus and examined the infection process using various molecular biological methods.
“In fact, most cell types, including hormone-producing enteroendocrine cells and Paneth cells that are important for the immune system, can be infected with SARS-CoV-2. You immediately start replicating, that is, producing new, infectious viruses. The only exception are mucus-producing goblet cells, ”says first author Jana Krüger, who together with the virologists Rüdiger Groß, Dr. Janis Müller and Carina Conzelmann carried out the most important experiments of the work.
Drug has been shown to be effective
But how can the infection process in the digestive tract be stopped? The researchers tested various drugs on the infected intestinal organoids. Remdesivir has proven to be antiviral: The active ingredient, which was originally developed for Ebola treatment, blocks RNA polymerase and thus the reproduction of SARS-CoV-2.
In addition, the peptide EK1 was able to suppress the corona infection in the mini intestine. This is a so-called fusion inhibitor that prevents the virus from entering the cell.
“Interestingly, the antiviral effectiveness of Remdesivir in the mini intestine is considerably lower than in simple intestinal cell cultures. This observation underpins the need to test antiviral substances against SARS-CoV-2 in sufficiently complex systems, ”says Heisenberg Professor Alexander Kleger, senior physician at the Clinic for Internal Medicine I at the Ulm University Hospital.
The study provides the details necessary to explain the gastrointestinal symptoms and the high viral load in the stool of COVID-19 sufferers: The digestive tract offers SARS-CoV-2 sufficient docking points to infect various cell types, which in turn produce new coronaviruses. The resulting loss of specialized intestinal cells can lead to symptoms such as diarrhea and nausea.
In addition, the researchers have succeeded in testing drugs using intestinal organoids: In addition to coronavirus research, these investigations prove the added value of these mini intestines. (ad)
Author and source information
This text complies with the requirements of specialist medical literature, medical guidelines and current studies and has been checked by medical professionals.
- Ulm University: How SARS-CoV-2 affects the gastrointestinal tract, Remdesivir suppresses coronavirus infection in the “mini intestine”, (accessed: November 18, 2020), Ulm University
- Jana Krüger, Rüdiger Groß, Carina Conzelmann, Janis A. Müller, Lennart Koepke, Konstantin M.J. Sparrer, Tatjana Weil, Desirée Schütz, Thomas Seufferlein, Thomas F.E. Barth, Steffen Stenger, Sandra Heller, Jan Münch, Alexander Kleger: Drug inhibition of SARS-CoV-2 replication in human pluripotent stem cell-derived intestinal organoids; in: Cellular and Molecular Gastroenterology and Hepatology, (Accepted Date: 03.11.2020), Cellular and Molecular Gastroenterology and Hepatology
This article is for general guidance only and should not be used for self-diagnosis or self-treatment. He can not substitute a visit at the doctor.