Electroacupuncture Alleviates the Inflammatory Response via Effects on M1 and M2 Macrophages after Spinal Cord Injury

BACKGROUND: Macrophages/microglia are important effector cells at the site of spinal cord injury (SCI). M1-type macrophages facilitate innate immunity to remove foreign microbes and wound debris from the injury site. M2-type macrophages exhibit tissue repair properties and attenuate production of pro-inflammatory cytokines. Regulation of the polarisation of M1/M2 macrophages may affect the inflammatory response in SCI and may be related to neurotrophin-3 (NT-3). Electroacupuncture (EA) at GV acupuncture points can be used as an adjuvant therapy for SCI. AIM: To investigate the effects of EA on Basso, Beattie and Bresnahan (BBB) functional evaluation and inflammatory cytokines (tumour necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-10), and on the proportions of M1/M2 macrophages, and to provide a greater understanding of the mechanisms underlying the potential clinical treatment of SCI. METHODS: A rat SCI model was induced by spinal segment transection at T10 in 16 Sprague-Dawley rats. A further eight rats were included as a Control group. Ten surviving SCI model rats were divided into two groups (n=5 each): an SCI group that remained untreated; and an SCI+EA group that received EA at GV6 and GV9. RESULTS: EA improved BBB scores, inhibited the proportion of M1 macrophages and TNF-α, IL-1β and IL-6 levels, and downregulated the M1 marker CD86. By contrast, EA enhanced IL-10, the proportion of M2 macrophages and upregulated the M2 marker CD206 and NT-3 expression. CONCLUSIONS: EA had a positive impact on SCI model rats. This may be related to the neuroprotective effect of NT-3, which may increase the polarisation of M2 microglia/macrophages.