The splenic response to stroke: from rodents to stroke subjects

BACKGROUND: Stroke is the fifth leading cause of death and the leading cause of long-term disability in the USA, costing $40.2 billion in direct and indirect costs. Globally, stroke is the second leading cause of death and has a higher prevalence in lower- and middle-income countries compared to high-income countries. The role of the spleen in stroke has been studied in rodent models of stroke and is seen as a major contributor to increased secondary neural injury after stroke. Splenectomy 2 weeks prior to ischemic and hemorrhagic stroke in mice and rats shows decreased infarct volumes. Additionally, the spleen decreases in size following stroke in rodents. Pro-inflammatory mediators are also increased in the spleen and subsequently the brain after stroke. These data in preclinical models of stroke have led stroke neurologists to look at the splenic response in stroke subjects. The outcomes of these studies suggest the spleen is responding in a similar manner in stroke subjects as it is in animal models of stroke. CONCLUSION: Animal models demonstrating the detrimental role of the spleen in stroke are providing strong evidence of how the spleen is responding during stroke in human subjects. This indicates treatments targeting the splenic immune response in animals could provide useful targets and treatments for stroke subjects.