Our saliva is much more than a simple biological lubricant. It hosts a complex ecosystem of bacteria whose role in our health is still largely underestimated. In recent years, researchers have started to decipher this oral flora with ever more precise tools, revealing unexpected structures. Among them, inocles could well embody a missing piece of the puzzle between microbiome and immunity, even a new path in the fight against certain forms of cancer.
These structures resemble plasmids, but their size and their complexity clearly distinguish them. They contain hundreds of genes, a large part of which is still mysterious. However, some functions have already been identified, such as resistance to oxidative stress or DNA repair. These are as many mechanisms that bacteria use to survive in an environment as fluctuating as the human mouth, subject to variations in temperature, pH or humidity.
The team led by Yuya Kiguchi found these inocles in almost 74% of saliva samples collected, which suggests that they are widely used in the world's population, according to data published in Nature Communications. Their main host would be a specific strain of Streptococcus, a common bacteria and yet underestimated in its adaptive capacities.
The inocles model our immune system without our knowing
In addition to helping bacteria to adapt, inocles could also directly influence our own physiology. This is what the peripheral blood analyzes carried out on a group of volunteers carrying inocles. The researchers observed a positive correlation between the presence of these elements and the abundance of B cells, key cells in the adaptive immune system. This link was also accompanied by reinforced activation of certain proteins linked to the response against bacterial and viral infections.
In other words, the presence of inocles in the mouth seems to be accompanied by a particular immune signature, marked by increased vigilance of the defense system. The exact link between bacterial DNA and this modulation remains to be explored, but the first results indicate a possible dialogue between bacteria carrying inocles and human cells.
This hypothesis gains in solidity thanks to the very nature of the genes contained in these DNA loops. Several of them produce proteins capable of interacting with the cell wall, a process that certain bacteria exploit to modulate inflammation or escape detection by the host organism. The study of these interactions opens a new window on the way in which the oral microbiome discreetly shapes our general health.
From oral cavity to digestive cancers, a track to explore
The role of inocles may not stop at immunity. An analysis comparing saliva of patients with head and neck cancer to that of healthy people has highlighted a significant drop in the presence of inocles in patients. This observation, relayed by researchers from the University of Tokyo, suggests a potential link between the disappearance of these elements and the progression of certain cancers.
Another study on patients with colorectal cancer also highlighted a similar phenomenon, since researchers have found a reduced presence of inocles in patients compared to healthy subjects. On the other hand, the analyzes carried out in people with pancreatitis or rheumatoid arthritis have revealed any significant change, which reinforces the idea that this association specifically concerns certain pathologies of the digestive tract.
Nothing yet makes it possible to assert whether the reduction in the number of inocles promotes cancer, or if the disease itself alters the balance of the microbiome. But their potential as an early biomarker, detectable in saliva without invasive intervention, already attracts the attention of researchers. In the near future, a simple oral direct debit could perhaps reveal much more than a risk of cavities, giving an overview of our immune state or an underlying imbalance.
