Australian researchers have discovered a previously unknown method used by bacteria to evade immune responses.
- Some bacterial infections evade the immune response by targeting mitochondria.
- Our immune cells have the ability to sense that their mitochondria are no longer functional at the time of an infection, which triggers apoptosis, the process by which cells trigger their self-destruction.
- By directly targeting apoptotic factors, researchers were able to reduce inflammation in tests conducted on mice.
Bacteria and our immune system are in a constant battle, one to infect us and the other to protect us. In this game of cat and mouse, Australian researchers have managed to shed light on one of the previously unknown methods used by bacteria to evade immune responses. They published the results of their research on August 17 in the journal Nature Microbiology.
Targeting apoptotic factors
Some bacterial infections evade the immune response by targeting mitochondria. The researchers succeeded in showing that immune cells have the ability to sense that their mitochondria are no longer functional at the time of an infection, which triggers apoptosis, a process by which cells trigger their self-destruction. “Ironically, it is the activation of host cell death factors that deals the final blow to mitochondria that induces apoptosis, not the bacterial toxins themselves.”, describes Dr. Pankaj Deo, lead author of the study.
By directly targeting apoptotic factors, researchers were able to reduce inflammation in tests conducted on mice. They used pathogenic bacteria Neisseria gonorrhoeae, Uropathogenic Escherichia coli and the mortal Pseudomonas aeruginosa, widespread in hospitals and which can be multi-resistant. “However, the results would also apply to other species of bacteria.”, says Pankaj Deo.
Towards new therapeutic avenues
These results open the way to new therapeutic practices. “There’s been a lot of effort to try and block endotoxins that kill immune cells, but this study really shifts the focus to different toxins that might be more important.develops the researcher. This gives us some good leads that we can look at as a next step..” Accelerating the immune response by targeting mitochondria offers many perspectives. “The other aspect is that if this response persists and we get constant inflammation — which is usually associated with bacterial infection and causes a lot of tissue damage — we have a new way to stop this tissue-damaging inflammation”, believes Pankaj Deo.
Previously, scientists believed that when endotoxins are released by bacteria, they induce an inflammatory type of programmed cell death called pyroptosis in immune cells. “We found that pathogenic bacteria use a similar mechanism to release additional toxinscontinues the researcher. They kill immune cells by releasing small surface structures called outer membrane vesicles, packets of toxins that target mitochondria. Mitochondria are disarmed, become dysfunctional and then die due to apoptosis or cell suicide.”
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