Infections after a traumatic brain injury: The complex interplay between the immune and neurological systems

Research output: Contribution to journalReview article

Authors

  • Rishabh Sharma
  • Sandy R Shultz
  • Marcus J Robinson
  • Margaret L Hibbs
  • Terence J O'Brien
  • Bridgette D Semple

External organisations

  • Department of Neuroscience, Central Clinical School at the Alfred Hospital, Monash University, Melbourne, VIC, Australia.
  • Department of Neuroscience, Central Clinical School at the Alfred Hospital, Monash University, Melbourne, VIC, Australia; Department of Medicine (Royal Melbourne Hospital), Melbourne Medical School, The University of Melbourne, Parkville, VIC, Australia.
  • Department of Immunology and Pathology, Central Clinical School at the Alfred Hospital, Monash University, Melbourne, VIC, Australia.
  • a Institute of Inflammation and Ageing , College of Medical and Dental Sciences , University of Birmingham , Birmingham , UK.
  • Department of Neuroscience, Central Clinical School at the Alfred Hospital, Monash University, Melbourne, VIC, Australia; Department of Medicine (Royal Melbourne Hospital), Melbourne Medical School, The University of Melbourne, Parkville, VIC, Australia. Electronic address: Bridgette.Semple@monash.edu.

Abstract

Traumatic brain injury (TBI) is a serious global health issue, being the leading cause of death and disability for individuals under the age of 45, and one of the largest causes of global neurological disability. In addition to the brain injury itself, it is increasingly appreciated that a TBI may also alter the systemic immune response in a way that renders TBI patients more vulnerable to infections in the acute post-injury period. Such infections pose an additional challenge to the patient, increasing rates of mortality and morbidity, and worsening neurological outcomes. Hospitalization, surgical interventions, and a state of immunosuppression induced by injury to the central nervous system (CNS), may all contribute to the high rate of infections seen in the population with TBI. Ongoing research to better understand the immunomodulators that underlie TBI-induced immunosuppression may aid in the development of effective therapeutic strategies to improve the recovery trajectory for patients. This review first describes the clinical scenario, posing the question of whether TBI patients are more susceptible to infections such as pneumonia, and if so, why? We then consider how cross-talk between the injured brain and the systemic immune system occurs, and further, how the additional immune challenge of an acquired infection can contribute to ongoing neuroinflammation and neurodegeneration after a TBI. Experimental models combining TBI with infection are discussed, as well as current treatment options available for this double-barreled insult. The aims of this review are to summarize current understanding of the bidirectional relationship between the CNS and the immune system when faced with a mechanical trauma combined with a concomitant infection, and to highlight key outstanding questions that remain in the field.

Bibliographic note

Crown Copyright © 2019. Published by Elsevier Inc. All rights reserved.

Details

Original languageEnglish
JournalBrain, Behavior, and Immunity
Publication statusE-pub ahead of print - 25 Apr 2019