Researchers show how spinal cord injury causes profound changes in gut microbiota

The community of bacteria that live in our intestines, also called the "gut microbiome," is important to normal intestinal function. Knowing that spinal cord injuries often negatively affect the gut's ability to do its job, researchers at The Ohio State University Wexner Medical Center showed that spinal cord injury causes profound changes in the gut microbiota. They also showed that feeding mice probiotics after a spinal cord injury confers neuroprotection and improves functional recovery.

The findings are published online in the Journal of Experimental Medicine.

"The trillions of microbes that exist in the gastrointestinal tract have emerged as pivotal regulators of human development and physiology. Spinal cord injuries cause dramatic shifts in the types of bacteria normally found in the gut, resulting in dysbiosis, which can cause or contribute to neurologic disease," said principal investigator Philip Popovich, professor of neuroscience and director of The Center for Brain and Spinal Cord Repair at Ohio State's Neurological Institute.

Whether dysbiosis affects recovery after spinal cord injury has not been determined, but Popovich's research team showed that:

• - Traumatic spinal cord injury causes bacterial translocation (movement of bacteria from gut into sterile tissues throughout the body) and dysbiosis. These changes are associated with activation of immune cells in gut-associated lymph tissue (GALT). 

  - Experimental induction of dysbiosis before spinal cord injury impairs functional recovery and exacerbates spinal cord pathology. Importantly, antibiotics used to induce dysbiosis are used often in spinal cord injury clinics to treat pneumonia (gentamycin), wound infections (streptomycin) or cystitis (ciprofloxacin).

  - Conversely, commercially available probiotics, when given after spinal cord injury, protect the microbiome and confer neuroprotection, improve neurological recovery and elicit a protective immune response in GALT.

"Although paralysis and loss of neurologic function are well-known consequences of spinal cord injury, the current data reveal a previously unappreciated role for spinal cord injury in changing the gut microbiome with reciprocal effects on the magnitude of functional recovery and spinal cord neuropathology," said first author Kristina A. Kigerl of Ohio State.

These data will help shape future pre-clinical and clinical research programs focused on understanding the importance of the gut-immune-central nervous system axis in recovery from spinal cord injury, Popovich said.