A bio-engineered probiotic could “revolutionize the way we treat chronic diseases,” according to a new study.
In the research, which was published in Nature on Wednesday, the authors tested an engineered probiotic bacteria in mice on a disease that closely resembles multiple sclerosis (MS) in humans. The researchers found they were able to more precisely target brain inflammation caused by MS, and also saw fewer negative side effects compared to standard therapies used for the condition.
Despite the limitations of the study — treatments that appear to work on mice don’t always translate to humans — the researchers from Brigham and Women’s Hospital in Boston are optimistic about the potential for the new therapy.
“Engineered probiotics could revolutionize the way we treat chronic diseases,” lead author Francisco Quintana, Ph.D., of the Ann Romney Center for Neurologic Diseases at Brigham and Women’s Hospital, said in a statement. Dr. Quintana went on to explain that when traditional drugs are taken, their concentration peaks after an initial dose, and then levels drop over time. “However, if we can use living microbes to produce medicine from within the body, they can keep producing the active compound as it’s needed, which is essential when we consider lifelong diseases that require constant treatment.”
Autoimmune diseases of the brain like MS happen when a person's immune system cells begin attacking healthy immune cells and tissue of the central nervous system such as the brain and the spinal cord.
According to the Centers for Disease Control and Prevention, autoimmune diseases affect 8% of the population. Eight in 10 of those affected by this condition are women. Even though it’s widespread, treatment options for several conditions such as MS are limited and difficult to treat because of where it occurs — the brain.
To find alternative treatment options, researchers analyzed dendritic cells, a type of immune cells found in the gut and spaces around the brain that help control the rest of the immune system. However, until now, their effects on autoimmune diseases hadn’t been studied.
The authors found that by mimicking the dendritic cells, they could stop the immune system from attacking healthy cells.
“The mechanism we found is like a brake for the immune system,” Dr. Quintana said. “In most of us, it’s activated, but in people with autoimmune diseases, there are problems with this brake system, which means the body has no way to protect itself from its own immune system.”
To reactivate the “biochemical brake,” the researchers found that they needed lactate (or lactic acid). So, they genetically engineered probiotic bacteria to produce the lactate — this is different from the probiotics you see sold as supplements.
“Probiotics are nothing new – we’ve all seen them sold as supplements and marketed as a way to promote health,” Dr. Quintana explained. “By using synthetic biology to get probiotic bacteria to produce specific compounds relevant to diseases, we can take the benefits of probiotics and amp them up to the max.”
The authors tested the designer probiotic bacteria on mice with an autoimmune condition similar to MS. What they found was the bacteria, even though it lives in the gut, was able to reduce some of the MS-like inflammation in the brain.
In addition to this, the researchers didn’t find the bacteria circulating in the bloodstream of the mice. In other words, the bacteria didn’t travel to the brain. This, the authors suggest, might mean the immune cells sent biochemical signals to the cells in the brain directly from the gut.
In recent years, studies have shown that gut bacteria can affect the central nervous system and might have a role to play between the nervous system’s function and development. Research shows this effect is often referred to as the “gut-brain axis.”
The study researchers, through their focus on MS and designer bacteria and based on the results of the study, hope to leverage the gut-brain axis in treating other autoimmune conditions that affect the brain and other parts of the body.
“The ability to use living cells as a source of medicine in the body has tremendous potential to make more personalized and precise therapies,” Dr. Quintana said. “If these microbes living in the gut are powerful enough to influence inflammation in the brain, we’re confident we’ll be able to harness their power elsewhere as well.