Immune Responses to Functional Electrical Stimulation Exercise in Humans with Spinal Cord Injury
Spinal Cord Injury (SCI) typically results in long-term depression of immune function. As a result, people with SCI are more susceptible to infection, which is the leading cause of death in the chronic stage of injury. The incidences of certain forms of infection, such as pneumonia and septicemia, are much higher among people with SCI than in the general population. Although increased susceptibility to infection after SCI is widely reported, the underlying mechanisms of immune dysfunction are not fully understood. The purpose of this study is to seek insight into these mechanisms by investigating stress hormone and immune cell fluctuations in response to different forms of exercise in groups of subjects with different levels of SCI. The findings will provide new information regarding immune cell activation that could lead to the understanding of mechanisms that may be exploited by special exercise interventions for people with SCI.
The primary aim of this study is to examine the impact of SCI on specific immune responses to a single bout of moderate aerobic exercise. Individuals with high cervical SCI have an impaired sympathetic nervous system and thereby a reduced catecholamine response to exercise compared to individuals with lower thoracic-level SCI and able-bodied individuals. Acute exercise is known to transiently stimulate immune cell activity in able-bodied individuals due to the release of certain stress hormones, but less is known about the immune response to acute exercise in individuals with SCI. If adrenergic activity stimulated by the sympathetic nervous system is important for modulating the amount of immune cell activity during exercise and after exercise, then a blunted immune response would be expected in quadriplegics. A secondary aim of this study is to determine changes in expression of beta receptors over the course of SCI. Thus, mechanisms other than those regulated by adrenergic catecholamines may be suggested.
This study represents a translational research project, the results of which will have direct application to the human SCI population. It is the first step in a line of research that aims to address immunodeficiency, which is one of the most important, unsolved problems in SCI. Our long-term goal is to develop exercise-based interventions that can improve immune function and overall quality of life. This project will generate preliminary data for use in a grant application to fund the larger project.