Weightlessness made parasitic bacteria more successful

(ORDO NEWS) — American scientists have shown that the parasitic bacterium Salmonella typhimurium infects intestinal cells more successfully in microgravity than in terrestrial conditions. The results of the study are important for ensuring the health of astronauts during long-term flights.

In the process of evolution, parasitic microorganisms have developed many mechanisms for entering host cells. However, in investigating the infection process, scientists often overlooked the physical forces that influence host-pathogen interactions and disease outcomes.

Now, researchers at Arizona State University (USA) have shown that under conditions that mimic the conditions of weightlessness during space flight, the bacterium Salmonella typhimurium , the causative agent of salmonellosis, infects three-dimensional models of human intestinal tissue much more successfully than on Earth.

Throughout its 3.7 billion year history, life on our planet has evolved under the influence of gravity. Cells of living organisms are exposed to extracellular fluid.

The sliding force of the liquid on the cell surface is reduced under weightless conditions, and this may affect the success of the parasite penetration. Understanding such processes is necessary to ensure the health of astronauts, especially during long flights, because bacteria will always accompany people.

To recreate weightless conditions, the scientists placed cultures of S. typhimurium and 3D cell models of the gut in a rotating wall bioreactor. As the cylinder of cells rotates, they are kept in suspension, gently turning over in their surrounding culture medium.

The study revealed significant changes in both gene expression and the bacteria’s ability to infect tissues. Two strains of S. typhimurium “participated” in the experiments a wild-type strain and a mutant strain that lacked the Hfq protein, the main regulator of the stress response in Salmonella.

Previously, scientists have found that Hfq is the main regulator of infection in spaceflight. However, to the surprise of the authors, under weightless conditions the mutant strain was able to attach to cells and infect them at levels comparable to the wild-type strain.

This was due to an increase in the expression of proteins necessary for the penetration of bacteria into the cell.

Thus, astronauts will face a double risk of contracting infections while away from Earth. The stressful environment of spaceflight itself weakens the immune system, while the conditions of weightlessness can make some pathogens more dangerous infectious agents.

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