2. Oncomicrobiotics to fight cancer, bacteria’s role in aids and a whole ecosystem to discover
New knowledge of the microbiome has given rise to a new term. In addition to what is known as probiotics, we may soon be talking about oncomicrobiotics: cocktails of microorganisms that could boost the effectiveness of cancer therapies.
These are the conclusions of the work presented by Laurence Zitvogel, director of Research at the Institut Gustave Roussy in Villejuif, France, who believes, “The microbiome could have an impact on cancer treatment, both for chemotherapy and immunotherapy.”
Her studies are surprising and are based on the fact that tumors are always being watched by our immune system. Although tumor development implies that it has insufficient control, this can be improved. This is the aim of new treatments based on immunotherapy, but it is also what traditional chemotherapy does indirectly. The latter, in destroying the tumor cells, sends many of its foreign substances into the body, which in theory makes them easier for our defenses to identify if they are working properly. This is where oncomicrobiotics could help.
When patients are given chemotherapy like that based on cyclophosphamide, “There is a translocation of bacteria from the intestine into the bloodstream," explains Zitvogel. Some of them "train" our defenses’ CD8 lymphocytes, making them more effective in fighting the tumor. In fact, the effectiveness of the treatment decreases significantly in the presence of antibiotics in lab mice, but increases enormously when combined with to specific types of bacteria. These are the ones that, if their role is confirmed, could be considered as oncomicrobiotics.
The microbiome and AIDS: what do they have to do with each other?
This apparent paradox was mentioned in the press conference by Bonaventura Clotet, director of the HIV Unit of the irsiCaixa Foundation: “You're probably wondering what an AIDS researcher is doing on a panel about the microbiome." The answer lies in part in the fact that the virus, in attacking the immune system, makes it easier for intestinal bacteria to move into the bloodstream. Once there, their presence causes chronic inflammation and accelerated aging. This is why Clotet doesn't hesitate in saying that “an AIDS vaccine will require a healthy microbiome”.
Moreover, the intestinal ecosystem seems to change in the presence of the disease. This was proven by Roger Paredes, irsiCaixa Microbial Genomics group leader. Patients, especially those not as strictly monitored, lose bacterial diversity, similar to what happens under other circumstances like metabolic syndrome. And, as explained by Dusko Ehrlich, emeritus director of the Institut National de la Recherche Agronomique of France, “In terms of the microbiome, it's also better to be rich than poor." This is why scientists are working to identify the bacteria affected and those that should be repopulated to improve the health of AIDS patients.
AN ECOSYSTEM OF MICROORGANISMS
The microbiome doesn't refer only to bacteria, but also to other microorganisms like viruses. These are omnipresent in all of us. There are very old viruses inside our DNA; there are viruses from illnesses we have already had or that lie in wait in some of our cells, like the rear-guard; there are active infections, and there is the huge amount of bacteriophage viruses that we host in our intestines and that only infect bacteria (and that, according to Frederic Bushman, president of the Department of Microbiology at the University of Pennsylvania in Philadelphia, “kill between 0.1% and 10% of all of our bacteria each day). Despite their importance, they are more difficult to study than bacteria, and aren't as well profiled.
And the microbiome also includes fungi, which don't tend to be mentioned as much because they also don't demand this importance. For example, as highlighted by Gary Wu, professor of Medicine at the University of Pennsylvania, "Frequent use of antibiotics is associated with increased risk of inflammatory intestinal disease an increased amounts of fungi in the intestine." In fact, some hypotheses believe they could play a role in developing the disease, whose origin is still unknown.