“Paralysis” of the immune system
Is the immune system also paralyzed after spinal cord injury? Yes, say scientists and present new data that are also relevant for clinicians.
People with spinal cord injuries tend to get more infections, much more than before their injury. One of these infections is pneumonia, the leading cause of death after acute spinal cord injury. It has been long believed that higher susceptibility to get infections was due to motor dysfunction, e.g. the impairment of the muscles involved in breathing and coughing. Although these factors are surely to blame, they aren’t the only ones. Evidence is now accumulating that a “paralysis” of the immune system, the so-called SCI-IDS (spinal cord injury-induced immune deficiency syndrome) is co-responsible.
How can a spinal cord injury paralyze the immune system?
Several organs which either contribute to or regulate the immune system are indirectly controlled by the nervous system. Like leg movements are controlled by the nervous system and affected by a spinal cord injury, the same holds true for the immune system. The experimental data of the paper of Brommer et al, published in the journal Brain, January 2016, show that high thoracic lesions of the spinal cord cause the interruption of the central axons innervating the major immune organs. This de-afferentiation anatomically results in an atrophy of the spleen, and functionally in the dysfunction of these immune organs. In consequence this diminishes the capacity of the body to defend itself from infections. These experimental data are mirrored by data observed in patients with complete high thoracic SCI, who suffer from more infections.
What are the consequences of such immune “paralysis”?
Functional recovery can be observed up to several years after the injury. SCI subjects that developed infections, mostly shortly after the injury, are less likely to regain such functions. Persons who contracted a severe case of pneumonia acutely after SCI might not be able to recover to their full potential. This compromises their quality of life.
What will happen next?
Scientists need to better understand the mechanisms of this syndrome in order to decrease or even eliminate this so-called immune paralysis. Also, the medical community should be more aware of such devastating effects and the need to detect and treat infections before they fully develop.
Source: Brommer B, Engel O, Kopp MA, Watzlawick R, Müller S, Prüss H, Chen Y, DeVivo MJ, Finkenstaedt FW, Dirnagl U, Liebscher T, Meisel A, Schwab JM. Spinal cord injury-induced immune deficiency syndrome enhances infection susceptibility dependent on lesion level. Brain. 2016 Jan 10.