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Objective: To investigate the regulatory mechanism of manual acupuncture (MA) on microglial polarization–mediated neuroinflammation after traumatic brain injury (TBI), focusing on the RhoA/Rho-associated coiled coil-forming protein kinase (ROCK2) pathway. Methods: Sprague Dawley (SD) rats were used to generate a TBI model using Feeney’s freefall epidural impact method. MA was performed on half of the TBI model rats, while the others remained untreated. Acupuncture was administered at GV15, GV16, GV20, GV26, and LI4. At the end of the intervention, rat brain tissue samples were collected, and the microglial M1 polarization status was observed by immunofluorescence labeling of CD86, an M1 microglia-specific protein. RhoA/ROCK2 signaling components were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. An enzyme-linked immunosorbent assay (ELISA) was used to detect the expression levels of inflammatory factors. Results: Compared with normal rats, the CD86 expression density in the untreated TBI model rats was high and showed an aggregated expression pattern. The genes and proteins of the RhoA/ROCK2 signaling pathway were highly expressed, and inflammatory factors were significantly increased. The CD86 expression density in TBI rats after MA was reduced compared to that in untreated TBI rats and showed a scattered distribution. The expression of RhoA/ROCK2 signaling pathway genes and proteins was also significantly reduced, and inflammatory factors were decreased. Conclusion: These results show that MA may inhibit M1 polarization of microglia by regulating the RhoA/ROCK2 signaling pathway, thereby reducing neuroinflammation in TBI.

Objective: Neuroinflammation caused by traumatic brain injury (TBI) can lead to neurological deficits. Acupuncture can inhibit neuroinflammation and promote nerve repair; however, the specific mechanism is still unclear. The purpose of this study was to explore whether acupuncture could modulate the M1 and M2 phenotypic polarization of microglia in a rat model of TBI via the toll-like receptor 4 (TLR4)/intracellular toll-interleukin-1 receptor (TIR) domain-containing adaptor inducing interferon-β (TRIF)/myeloid differentiation factor 88 (MyD88) pathway. Methods: A total of 90 adult male Sprague-Dawley (SD) rats, SPF grade, were randomly divided into a normal group, model group and acupuncture group. Each group was further divided into three subgroups (first, third, and fifth day groups) according to the treatment time ( n = 10 rats/subgroup). We used the modified neurological severity score (mNSS) method to quantify neurological deficits before and after modeling. We used Nissl staining to observe the pathological changes in brain tissue, flow cytometry to detect the proportion of M1 and M2 polarized microglia in the injured area on the first, third and fifth day, and co-immunoprecipitation (Co-IP) to examine TLR4/TRIF/MyD88 expression in microglia on the first, third and fifth day, as well as expression of the amount of binding of TLR4 with TRIF and MyD88. Results: Compared to the model group, mNSS in the acupuncture group gradually decreased and pathological morphology improved. The proportion of CD11b/CD86 positive cells was decreased, while that of CD11b/CD206 was increased in the acupuncture group. Expression of IP TLR4, IP TRIF and IP MyD88 also decreased in the acupuncture group. Conclusion: The results of this study demonstrate that one of the mechanisms through which acupuncture mitigates neuroinflammation and promotes nerve repair in TBI rats may be inhibition of M1 phenotypic polarization and promotion of M2 phenotypic polarization through inhibition of the TLR4/TRIF/MyD88 signaling pathway.