They’re our oldest partners – they are with us since the day we are born, they change with us as we grow, and they constitute an inseparable part of who we are. Trillions of bacteria live in our bodies – and despite their bad PR, most of them are actually desirable, and have a crucial role in nourishing us and maintaining our health. So, what can one do when the balance of “good” bacteria is shaken? Researcher Rotem Sisso explains what the Microbiome is and how new treatments that affect it are expected to change the face of medicine.
The microbiome is the genetic material of the collection of microorganisms that naturally live on and inside our bodies – bacteria, fungi, and viruses. Even though such microorganisms are typically notorious for their negative effects on our health, the microbiome is actually vital and has many important roles within the human body: it protects us from pathogens, aids in the development of the immune system and permits us to produce energy out of various foods. As the microbiome plays a key role in the interface between the body and the environment, microorganisms can affect the manner in which we react to substances and foods and alter the body’s ability to handle various conditions, such as infections.
Many studies conducted in recent years have proven that the microbiome is not only linked with the body’s normal mechanisms of handling existing diseases, but also with promoting or preventing the development of certain diseases. Thus, for instance, a relationship has been found between certain microbiome compositions and the development of diabetes, cardiac and neurological diseases, allergies, liver diseases and inflammatory bowel diseases such as Crohn’s disease and colitis.
Can’t maintain your weight? The problem may lie in bacterial composition
A study conducted at the Weizmann Institute and published in the leading journal Nature in 2016 has found that particular microbiome compositions make it difficult to maintain one’s weight and promote obesity. First, researchers took gut bacteria from two types of mice: thin mice that were fed a balanced diet, and mice that were fed high-fat diets – and, once they have gained weight, were fed low-fat diets and lost weight again. These bacteria were transferred to normal mice, and the surprising results indicated that the mice that received the microbiome from mice fed high-fat diets have gained more weight and developed diabetes at higher rates than the mice who received bacteria from mice that were thin to begin with. In practice, this study pointed to the microbiome as a target for developing potential treatments to aid in combatting the obesity epidemic.
Bacteriotherapy – treatments that assist with gastrointestinal diseases
In recent years, the novel concept of bacteriotherapy – treatments to improve the bacterial balance of the microbiome to cure patients of various illnesses – has been steadily gaining ground. Bacteria are taken from the stool of a healthy person with a proper microbiome composition, and transferred into a patient in special capsules.
Bacterial transplants have proven to be effective in several medical conditions. A distinctive example for this is microbiome transfers from healthy donors to patients with persistent Clostridium difficile bacterial infections, which causes gut inflammation and may be actually life-threatening in certain patients. Studies have proven that treatment with fecal microbiota transplant (FMT) is significantly more efficient in comparison with antibiotics – and currently, it is standard practice to progress to this treatment in patients that do not respond to antibiotics.
Additional examples include an improvement of symptoms in patients with irritable bowel syndrome and patients with chronic constipation that received fetal microbiota transplant, and the existence of several ongoing clinical studies attempting to demonstrate the efficacy of bacteriotherapy in inflammatory bowel diseases such as Crohn’s disease and colitis.
A revolution in cancer treatment?
A groundbreaking study published on February 2021 in the leading journal Science has examined the effect of microbiome transplants on metastatic melanoma skin cancer. The researchers took bacteria from the stool of metastatic melanoma patients that had an excellent reaction to immunotherapies (medication that help the immune system attack the cancer cells) and transplanted them into patients that did not respond to these therapies. Following the microbiome transplants, 40% of study participants have overcome their treatment resistance and developed a response to the immunotherapies.
Another study published on July 2021 examined the effects of fecal microbiota transplantation from overweight donors to patients with severe weight loss due to gastroesophageal cancer. The study found that patients who received the fecal microbiome donation responded to treatments better and survived longer.
Where are we headed?
In order to succeed in making microbiome treatments more accessible in a simple, quick and accurate way for a variety of diseases, the possibility of synthetically manufacturing various, exact microbiome compositions in a laboratory is being currently examined. These studies are still in early stages and it is too soon to determine their efficacy, but it may be possible that in several years, cures for many diseases will depend on a small capsule containing our old friends since the dawn of time.
