Spinal Cord Injury Could Harm Immune System
A severe spinal cord injury is traumatic enough, but new research now shows that trauma can trigger an immune deficiency that puts patients at risk for developing life-threatening infections.
A new study from a team of international researchers sheds light on spinal cord injury-induced immune deficiency syndrome, which was initially discovered in experimental models.
“Infections and subsequent sepsis are the main cause of death after spinal-cord injury,” said study co-author Dr. Jan Schwab, a professor of neurology and neurosciences at the Ohio State College of Medicine.
“Our study provides evidence for an immune deficiency that sets spinal cord-injured patients up to develop infections," Schwab said in a university news release. He is also medical director of the Belford Center for Spinal Cord Injury and a Scholar of the Chronic Brain Injury Initiative at Ohio State.
The team studied this in 111 patients, finding that monocytes, white blood cells that fight bacterial infections, were deactivated shortly after spinal-cord injury. These patients also had reductions in blood levels of antibody and immunoglobulins, which are part of the body's "learned," or adaptive, immunity.
Researchers measured the levels of a cell-surface molecule called mHLA-DR on monocytes. A low number of these molecules has been shown to predict susceptibility to sepsis in critically ill patients.
This adds to other factors involved in weakening the immune system in patients who have spinal cord injury, including being bedridden, receiving anesthesia and undergoing surgery.
The findings may help those caring for patients with a spinal cord injury and potentially lead to development of new treatments to reduce patient susceptibility to infection.
The risk of developing an immune deficiency syndrome was greatest for patients with complete, higher-level injury, the fourth thoracic vertebra or above, compared to those with incomplete, lower-level injury, the fifth thoracic vertebra or lower, and compared with a reference group of patients who had vertebral fracture that did not involve the spinal cord.
Patients with complete spinal-cord injury have total loss of motor and sensory function below the level of injury. Those with lower-level injury may maintain some function.
“Those patients with complete injuries and consequent loss of central nervous system control over immune system function displayed the highest odds for an immune deficiency,” Schwab said.
Researchers made a number of specific findings, including that patients with more severe injury had the highest burden of pulmonary and urinary tract infections. Patients with infections met the criteria for immune suppression within two weeks after injury.
Those with an infection within a week or two of injury had especially low mHLA-DR values just 15 hours after injury.
"Overall, our study suggests that a neurogenic immune deficiency syndrome drives infection susceptibility in spinal-cord injury patients, and it does so in a severity-dependent manner," Schwab said.
The findings were published June 28 in the journal Brain.
The U.S. National Institutes of Health has more on spinal cord injury.
SOURCE: Ohio State University Wexner Medical Center, news release, June 29, 2023