Abstract
Background: Acute and chronic stress can lead to a dysregulation of the immune response. Growing evidence suggests peripheral immune dysregulation and low-grade systemic inflammation in posttraumatic stress disorder (PTSD), with numerous reports of elevated plasma interleukin-6 (IL-6) levels. However, only a few studies have assessed IL-6 levels in the cerebrospinal fluid (CSF). Most of those have used single time-point measurements, and thus cannot take circadian level variability and CSF-plasma IL-6 correlations into account.
Methods: This study used time-matched, sequential 24-h plasma and CSF measurements to investigate the effects of combat stress and PTSD on physiologic levels and biorhythmicity of IL-6 in 35 male study volunteers, divided in 3 groups: (PTSD = 12, combat controls, CC = 12, and non-deployed healthy controls, HC = 11).
Results: Our findings show no differences in diurnal mean concentrations of plasma and CSF IL-6 across the three comparison groups. However, a significantly blunted circadian rhythm of plasma IL-6 across 24 h was observed in all combat-zone deployed participants, with or without PTSD, in comparison to HC. CSF IL-6 rhythmicity was unaffected by combat deployment or PTSD.
Conclusions: Although no significant group differences in mean IL-6 concentration in either CSF or plasma over a 24-h timeframe was observed, we provide first evidence for a disrupted peripheral IL-6 circadian rhythm as a sequel of combat deployment, with this disruption occurring in both PTSD and CC groups. The plasma IL-6 circadian blunting remains to be replicated and its cause elucidated in future research.
Original language | English |
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Pages (from-to) | 237-245 |
Number of pages | 9 |
Journal | Psychoneuroendocrinology |
Volume | 100 |
DOIs | |
Publication status | Published - Feb 2019 |
Keywords
- Interleukin-6 (IL-6)
- Cytokines
- Stress
- Trauma
- Posttraumatic stress disorder (PTSD)
- Circadian system
- Immune system
- Cerebrospinal fluid (CSF)
- Plasma
- Neuroimmunomodulation
- Blood-brain-barrier
- Serial sampling
- C-REACTIVE PROTEIN
- PRO-INFLAMMATORY CYTOKINES
- PITUITARY-ADRENAL AXIS
- CENTRAL-NERVOUS-SYSTEM
- GENE-EXPRESSION
- MAJOR DEPRESSION
- DEPLOYED MARINES
- DNA METHYLATION
- PTSD RISK
- IMMUNE