Table 2.

Brief summary of clinical research on neuroinflammation.

Examination of serum or plasma cytokines during migraine attacks in patients with migraine	No changes in proinflammatory cytokine TNF-α levels have been reported in serum or plasma during migraine attacks [63,64,65,66,67,68]; results for IL-6 and IL-1β levels are inconsistent. Lower or unchanged anti-inflammatory cytokine, IL-4, levels, and increased or unchanged IL-10 levels during migraine attacks have been reported, with inconsistent results throughout. However, serial analyses of cytokines in jugular venous blood collected by catheterization during migraine attacks resulted in consistent data, an initial increase in IL-1β, followed by increases in IL-6 and TNF-α, and a decrease in IL-4, which returned to its initial value at the end of the attack [64]. This study revealed no change in cytokine levels in peripheral blood collected simultaneously [64].
Examination of serum or plasma cytokines during the interictal period in patients with migraine	Most studies examining the interictal period of TNF-α [70,82,83] and IL-6 [64,65,67,70,71,72,82,88,89,90,91] have reported higher levels compared to controls and no change with respect to IL-1β levels [69,72,82,83,84,87]. IL-10 levels during attacks in migraine patients have been reduced compared to controls [67,79,83,89,93], but IL-4 levels have been reported less frequently and without certainty.
Cerebrospinal fluid (CSF) analysis of patients with migraine	CSF studies are limited and not definitive, and a certain view of inflammatory and non-inflammatory cytokines has not been obtained. However, soluble vascular adhesion molecule-1 (sVCAM-1) in CSF, but not plasma, is higher with more frequent headache frequency, suggesting that sVCAM-1 levels in CSF might be a potential biomarker for frequent migraine and CM [79].
Saliva study of patients with migraine	There are markedly fewer saliva-based tests, and no certain view of cytokines has been obtained. IL-1β might be useful in discriminating against migraine [102].