Changes in cerebrospinal fluid and serum cytokine levels in severe traumatic brain injury patients

Introduction

Inflammatory response following brain injury begins with brain tissue injury triggered neuroinflammation, which induces a systemic inflammatory response syndrome. We investigated the characteristics of the acute inflammatory response following severe traumatic brain injury through changes in cerebrospinal fluid (CSF) and serum cytokine levels.

Methods

The subjects were 24 patients with severe traumatic brain injury. We measured levels of the proinflammatory cytokines IL-6 and IL-8, and the anti-inflammatory cytokine IL-10 in peripheral blood and CSF on four occasions, at the time of admission and after 24 hours, 72 hours and 1 week.

Results

CSF and serum IL-6 levels continued to rise until 72 hours after admission. CSF IL-6 levels were 50 to 400 times serum levels. Serum IL-8 levels remained at 20 to 30 pg/ml. CSF IL-8 levels were 100 to 800 times the serum levels, and remained high after the peak of 23,500 pg/ml at the time of admission. CSF and serum IL-10 levels were high, but not abnormally high as for IL-6 and IL-8, and decreased with time. The difference in CSF and serum levels, as seen for IL-6 and IL-8, was not seen for IL-10.

Conclusion

We elucidated the following points concerning the acute inflammatory response following severe traumatic brain injury. High levels of IL-6 and IL-8 are maintained in both CSF and serum. CSF levels of IL-6 and IL-8 are one or two orders of magnitude greater than serum levels. Upregulation of IL-10 is minimal in comparison with IL-6 and IL-8, suggesting that in neuroinflammation IL-10 functions poorly as an anti-inflammatory cytokine.