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Two-Way Brain-Gut Interactions May Worsen Outcome After TBI

University of Maryland School of BOB体育 (UMSOM) researchers have found a two-way link between traumatic brain injury (TBI) and intestinal changes. These interactions may contribute to increased infections in these patients, and may also worsen chronic brain damage.

This is the first study to find that TBI in mice can trigger delayed, long-term changes in the colon and that subsequent bacterial infections in the gastrointestinal system can increase posttraumatic brain inflammation and associated tissue loss. The findings were published recently in the journal Brain, Behavior, and Immunity.

“These results indicate strong two-way interactions between the brain and the gut that may help explain the increased incidence of systemic infections after brain trauma and allow new treatment approaches,” said the lead researcher, , the David S. Brown Professor in Trauma in the Departments of , , , , and at UMSOM, and director of the .

‌Researchers have known for years that TBI has significant effects on the gastrointestinal tract, but until now, scientists have not recognized that brain trauma can make the colon more permeable, potentially allowing allow harmful microbes to migrate from the intestine to other areas of the body, causing infection.. People are 12 times more likely to die from blood poisoning after TBI, which is often caused by bacteria, and 2.5 times more likely to die of a digestive system problem, compared with those without such injury.

In this study, the researchers examined mice that received an experimental TBI. They found that the intestinal wall of the colon became more permeable after trauma, changes that were sustained over the following month.

It is not clear how TBI causes these gut changes. A key factor in the process may be enteric glial cells (EGCs), a class of cells that exist in the gut. These cells are similar to brain astroglial cells, and both types of glial cells are activated after TBI. After TBI, such activation is associated with brain inflammation that contributes to delayed tissue damage in the brain. Researchers don’t know whether activation of ECGs after TBI contributes to intestinal injury or is instead an attempt to compensate for the injury.

The researchers also focused on the two-way nature of the process: how gut dysfunction may worsen brain inflammation and tissue loss after TBI. They infected the mice with Citrobacter rodentium, a species of bacteria that is the rodent equivalent of E. coli, which infects humans. In mice with a TBI who were infected with this the bacteria, brain inflammation worsened. Furthermore, in the hippocampus, a key region for memory, the mice who had TBI and were then infected lost more neurons than animals without infection.

This suggests that TBI may trigger a vicious cycle, in which brain injury causes gut dysfunction, which then has the potential to worsen the original brain injury. “These results really underscore the importance of bi-directional gut-brain communication on the long-term effects of TBI,” said Dr. Faden.

Other authors of this paper include Elise Ma, a doctoral student; , professor of radiation oncology; , associate professor of anesthesiology ; and , associate professor of anesthesiology- all at UMSOM.

“This research has the potential to eventually connect bench to bedside in a groundbreaking way,” said , Executive Vice President for Medical Affairs at the University of Maryland and John Z. and Akiko K. Bowers Distinguished Professor and Dean of the University of Maryland School of BOB体育. “Dr. Faden is part of a first-rate collection of scientists at the School who are unraveling the complexities of traumatic brain injury and its effects on the body.”

About the University of Maryland School of BOB体育

Commemorating its 210^th Anniversary, the University of Maryland School of BOB体育 was chartered in 1807 as the first public medical school in the United States. It continues today as one of the fastest growing, top-tier biomedical research enterprises in the world -- with 43 academic departments, centers, institutes, and programs; and a faculty of more than 3,000 physicians, scientists, and allied health professionals, including members of the National Academy of Sciences, and a distinguished recipient of the Albert E. Lasker Award in Medical Research.  With an operating budget of more than $1 billion, the School of BOB体育 works closely in partnership with the University of Maryland Medical Center and Medical System to provide research-intensive, academic and clinically-based care for more than 1.2 million patients each year. The School has over 2,500 students, residents, and fellows, and nearly $450 million in extramural funding, with more than half of its academic departments ranked in the top 20 among all public medical schools in the nation in research funding. As one of the seven professional schools that make up the University of Maryland, Baltimore campus, the School of BOB体育 has a total workforce of nearly 7,000 individuals. The combined School and Medical System (“University of Maryland BOB体育”) has a total budget of $5 billion and an economic impact of nearly $15 billion on the state and local community. The School of BOB体育 faculty, which ranks as the 8^th-highest public medical school in research productivity, is an innovator in translational medicine with 600 active patents and 24 start-up companies. The School works locally, nationally, and globally, with research and treatment facilities in 36 countries around the world. Visit

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