protective and inflammatory bacteria that increase the risk of disease – breaking latest news

A growing body of evidence indicates that the tens of trillions of gut microbes, the so-called intestinal microbiota
, has important effects for the correct functioning of our body. More recent studies suggest that the intestinal microbiota also plays a crucial role in our health brain and intestinal bacteria appear to play a vital role in the development of malattie neurodegenerative, although the exact mechanism behind this relationship remains unknown today. Studies suggest that a less diversity in the gut microbiota (condition common to Alzheimer’s patients) are associated with neurodegenerative diseases through neuroinflammatory processes of the microbiota-intestine-brain axis. In January a major study published in Science of a group of researchers at Washington University in St. Louis/Missouri with work on mice had discovered that intestinal bacteria influence the behavior of immune cells throughout the body, including those of the brain that can damage brain tissue, and aggravate the neurodegeneration in conditions such as Alzheimer’s disease.

Pro inflammatory bacteria and protective bacteria

Now a maxi study by a team of researchers from the University of Nevada published on Scientific Reports investigated in more detail relationship between Alzheimer’s disease and intestinal bacteria in the human microbiota. The researchers studied the composition of the microbiota of patients with Alzheimer’s compared to that of the control group composed of healthy patients. To do this they used a risk-based assessment genetic correlations known with the disease in relation to 119 species of intestinal microbes taken from each individual. They found that 20 of these 119 bacterial strains had a significant association with Alzheimer’s disease. Six of these 20 bacteria have been identified as species linked to an Alzheimer’s risk while the other 14 would be potentially protective against the disease. The species associated with the most significant risk is il Bacteroides while the most protective gender is the Intestinibacter.

Scientists have observed that there is an association between abundance of pro-inflammatory bacterial strains and the APOE genotype (people with APOE variant 4 have a higher risk of developing Alzheimer’s). A result that suggests that the genetic vulnerability associated with the APOE genotype could also act by modifying the intestinal microbiota, making it richer in pro-inflammatory bacteria and thus making the individual more susceptible to neurodegenerative disease. In this case it emerged that the pro-inflammatory bacterium
Collinsella aerofaciens
it is especially abundant in people with the APOE4 gene.

“Inflamed” microbiota in patients with Alzheimer’s

This new work is only the latest of many studies on the subject. In recent years, researchers have focused on this complex relationship between intestinal microflora, immune system e neurological functioning in an attempt to understand why brain areas degenerate and give rise to symptoms such as memory loss or cognitive decline typical of Alzheimer’s disease. «We know that neurodegenerative and psychiatric diseases also have one inflammatory componentmoreover a risk factor for various pathologies such as cardiovascular, metabolic and immunological diseases» he comments Annamaria Cattaneo, Head of the Biological Psychiatry Laboratory of the IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, professor at the University of Milan, Department of Pharmacological and Biomolecular Sciences and author of numerous studies on the subject. «Over time we have seen that the microbiota shapes what our immune system is, as if they developed together. The fact that in various mental pathologies there was altered inflammation without an apparent motivation prompted research to look for an answer in the intestinal microbiota. It has thus been noted in the various studies, including those conducted at the Fatebenefratelli of Brescia, that patients with Alzheimer’s disease present a microbiota with more abundant pro-inflammatory strains compared to control subjects. In particular, in our work we had noticed that the bacterium was less abundant in patients with Alzheimer’s disease Roseburia, known to be protective, hence suggesting Roseburia
as a
protective factor for neurodegenerative disease.

A balance that is not always harmonious

Already from the moment we are born and in the development phase, the human organism is colonized by a mix of bacteria, fungi and viruses which establish a sort of temporary “truce” with the immune system. In most cases this kind of organization is mutually beneficial: the microbes get a place to live and the man a battery of tiny front-line defenders willing to work hard to protect their home. This does not mean that the balance is always harmonious: changes in the immune system can in fact favor certain species of microbes over others. Likewise i changes in the intestinal florafor example with dietary changes, can profoundly affect the functioning of the body, for better or for worse.

«There are no bacteria that predispose to one disease rather than another, to depression, to an autoimmune disease or to anorexia. Rather certain bacteria predispose to biological alterations which are then common to various pathologies» clarifies Dr. Cattaneo. «Each person – she adds – has his own genetic background and someone may be more predisposed than another to developing a disease. Lifestyles, nutrition and stress matter a lot».

Measure the microbiota

It’s actually not yet clear whether these differences in bacterial flora are the cause or the consequence of neurodegenerative diseases or if there is a mix of correlation. Certainly research is paving the way for the possibility of remodel the intestinal microbiota per to prevent o deal with the neurodegeneration. «Today, with the technologies available, we can measure all bacterial strains from a quantitative point of view, even if in truth many still don’t have a name and for many we don’t know their functions» underlines Cattaneo.

But we know that a microbiota is healthy when they are present abundant and diverse bacteria in order to perform various functions. As mentioned, several studies have shown that in patients with Alzheimer’s disease the microbiota appears a little poorer, with less diversification of bacterial strains and a smaller amount of those strains that are instead protective against inflammation

How to manipulate the microbiota (with probiotics ah hoc)

It may then be possible manipulate the gut microbiota to have an effect on the brain….without touching the brain? «To date, there really isn’t a microbiota profile that tells me “I’m a healthy person and I don’t risk anything” nor a microbiota profile that can tell me if I risk developing one or the other pathology. Certainly having a rich and diversified microbiota can help protect us from some pathologies, but it is not credible to be able to fix everything with the microbiota» reflects Cattaneo.

The good news is that anyway the microbiota is highly modifiable, even quickly. Suffice it to say that the same person, while maintaining the same diet, has a different microbiota profile in summer and winter. In fact, there are many factors that come into play. «With an active lifestyle and theprobiotic supplementation – underlines Annamaria Cattaneo – the microbiota can be made richer. Today we have several probiotics on the market that have beneficial effects but the goal in the future is to be able easily analyze the microbiota of the individual (today serious analyzes are still complex) e identify which protective bacteria are deficient and intervene with probiotics for this based on the deficiencies of the individual, exactly as it is done with vitamins. A kind of microbiota supplement».

The integration of the microbiota for preventive purposes

The hope of the research is to be able to contribute, through themicrobiota integration, to prevent or delay neurodegenerative diseases: «It is difficult to go back from the disease in people with full-blown Alzheimer’s – concludes the expert – but by acting in people with mild cognitive impairment or with a risk of developing the disease it will perhaps be possible to slow down the progression of the pathology , also intervening on the microbiota. One more weapon to deal with a disease, Alzheimer’s, which in Italy alone has over 600,000 patients».