As to whether the technique works, there seems to be no more doubts. The points to be clarified, if anything, concern the aspects that can amplify or reduce the effectiveness of the therapy. Fecal microbiota transplantation represents an already validated solution to eradicate Clostridium difficile, a bacterium capable of colonizing the intestine and now resistant to almost all antibiotics. And it is also studied for what could be a use in the management of very different diseases – from metabolic syndrome to Tourette’s – but which appear to be linked to a significant alteration of the intestinal bacterial flora.
In addition to investigating how broad the spectrum of treatable diseases can be by transferring the microorganisms that live in the intestine of an individual (donor) into that of the patient, it remains to be understood which aspects regulate the success or failure of this intervention. A puzzle with a varied composition, which the researchers of the Gemelli Polyclinic in Rome, the European Institute of Oncology and the University of Trento have begun to compose. With important results in order to imagine a more extensive use of the treatment.
Donor and recipient
For fecal microbiota transplantation to be successful, the greatest number of transferred microorganisms must take root in the host’s intestine. In a nutshell, this is the message that emerges from a study published in the journal “Nature Medicine”, at the end of a long and sophisticated sequencing activity of over 1,300 donor stool samples and patients suffering from eight different diseases: in addition to infection Clostridium difficile, others caused by various bacteria, metabolic syndrome, melanoma, inflammatory bowel disease (Crohn’s and ulcerative colitis), irritable bowel syndrome, chemotherapy diarrhea and Tourette’s syndrome. By reconstructing the DNA sequence of these microorganisms directly in the intestine, the researchers identified the different strains present in each individual’s microbiota. And, considering at that point the knowledge of the donor’s profile and that of the recipient, assessed the engraftment in the new host.
The higher this was, “the better was the clinical response to disease,” he explains Gianluca Ianirogastroenterologist at the Gemelli Polyclinic in Rome and first signature of the publication -. We also noted that engraftment is greater in patients with an infectious disease than that recorded among those who were suffering from a chronic disease. “Sign, in all likelihood, that transplantation is more effective in restoring a condition of imbalance altered by an infection and not one dictated by a more complex and protracted cause.
The complex role of the intestinal microbiota
The procedure, as mentioned, is already validated at the clinical level. But only for the treatment of Clostridium difficile, for which it is now safe: as well as effective in 9 out of 10 cases (without relapses). However, the interest on the part of the scientific community is considerable, attracted by the possibility that the “manipulation” of the microbiota can contribute to reducing the risk factors of some diseases, if not helping to cure them. A hypothesis derived from the fact that several studies have shown that many diseases – including some tumors, as also demonstrated by the researchers of the University of Trento in February, in “Nature Medicine” – have been linked to an alteration of the composition and the functions of the intestinal microbiota. A plausible hypothesis, considering that bacteria, fungi and protozoa that make up what experts now consider to be an organ perform various functions: they hinder colonization by external pathogens, participate in metabolism through the digestion of complex sugars, contribute to development of the immune system, modify the efficacy and toxicity of the drugs taken and regulate intestinal motility.
How the transplant is done
How then to reconstruct the microbiota, in case of disease? The transplant is performed by isolating and purifying the donor microbiota collected from the faeces and transferring it in various ways – in capsules or during a colonoscopy – to the donor patient. The big unknown of this procedure, however, is represented by the level of engraftment of the microorganisms transplanted in the intestine of the recipient patient. “We also found – continues Ianiro – that patients treated with antibiotics before the transplant procedure had a greater engraftment. And that the infusion of the microbiota through multiple routes of administration favors engraftment”. Better, that is, with a capsule and an infusion through the colonoscopy together than through only one of the two approaches.