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Electroacupuncture Attenuates Immune-Inflammatory Response in Hippocampus of Rats with Vascular Dementia by Inhibiting TLR4/MyD88 Signaling Pathway.

ABSTRACT: OBJECTIVE:To investigate whether electroacupuncture (EA) alleviates cognitive impairment by suppressing the toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88) signaling pathway, which triggers immune-inflammatory responses in the hippocampus of rats with vascular dementia (VaD). METHODS:The experiments were conducted in 3 parts and in total the Sprague-Dawley rats were randomly divided into 8 groups by a random number table, including sham, four-vessel occlusion (4-VO), 4-VO+EA, 4-VO+non-EA, sham+EA, 4-VO+lipopolysaccharide (LPS), 4-VO+LPS+EA, and 4-VO+TAK-242 groups. The VaD model was established by the 4-VO method. Seven days later, rats were treated with EA at 5 acupoints of Baihui (DV 20), Danzhong (RN 17), Geshu (BL 17), Qihai (RN 6) and Sanyinjiao (SP 6), once per day for 3 consecutive weeks. Lymphocyte subsets, lymphocyte transformation rates, and inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor α(TNF-α) were measured to assess immune function and inflammation in VaD rats. Transmission electron microscopy was used to observe the ultrastructure of nerve cells in the hippocampus. The levels of TLR4, MyD88, IL-6, and TNF-α were detected after EA treatment. TLR4/MyD88 signaling and cognitive function were also assessed after intracerebroventricular injection of TLR4 antagonist TAK-242 or TLR4 agonist LPS with or without EA. RESULTS:Compared with the 4-VO group, EA notably improved immune function of rats in the 4-VO+EA group, inhibited the protein and mRNA expressions of TLR4 and MyD88 in the hippocampus of rats, reduced the expressions of serum IL-6 and TNF-α (all P<0.05 or P<0.01), and led to neuronal repair in the hippocampus. There were no significant differences between the 4-VO+LPS+EA and 4-VO+EA groups, nor between the 4-VO+TAK-242 and 4-VO+EA groups (P>0.05). CONCLUSIONS:EA attenuated cognitive impairment associated with immune inflammation by inhibition of the TLR4/MyD88 signaling pathway. Thus, EA may be a promising alternative therapy for the treatment of VaD.

SUBMITTER: Bu Y

PROVIDER: S-EPMC8672855 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundIt is widely accepted that inflammation may contribute to cognitive impairment in patients with vascular dementia (VD). Our prior clinical researches have reported that acupuncture can alleviate cognitive function in VD, but the underlying mechanisms are still unclear. The purpose of this research was to explore whether acupuncture alleviates cognitive impairment by suppressing the microRNA-93- (miR-93-) mediated Toll-like receptor (TLR) signaling pathway, which triggers inflammatory responses in the central nervous system.MethodsVD was established by permanent bilateral common carotid artery occlusion in male Wistar rats. Three days after operation, the rats began daily treatment with acupuncture for two weeks. The levels of miR-93, Toll-like receptors (TLR2 and TLR4), intracellular signaling molecules (myeloid differentiation factor 88 (MyD88) and nuclear factor-kappa B (NF-κB)), and inflammatory cytokines were subsequently detected. TLR4 colocalized with neurons, microglia, and astrocytes in the hippocampus was evaluated. Neuroinflammation and cognitive function were determined after intracerebroventricular injection of TLR4 antagonist TAK-242 or agonist lipopolysaccharide (LPS) with or without acupuncture.ResultsWe found that acupuncture notably repressed the expression of inflammatory cytokines in the hippocampus and plasma of VD rats. The expression of TLR4, but not TLR2, was markedly downregulated by acupuncture, accompanied by a decrease in miR-93 and MyD88/NF-κB signaling pathway activation. The overexpression of TLR4 in microglia, but not in astrocytes and neurons, was reversed by acupuncture. Furthermore, intracerebroventricular injection of TAK-242 had similar effects to acupuncture on inflammation and cognitive function, while LPS injection abolished the beneficial effects of acupuncture.ConclusionsTaken together, these findings provide evidence that acupuncture attenuates cognitive impairment associated with inflammation through inhibition of the miR-93-mediated TLR4/MyD88/NF-κB signaling pathway in experimental VD. Acupuncture serves as a promising alternative therapy and may be an underlying TLR4 inhibitor for the treatment of VD.

Project description:Introduction: Low molecular weight heparin (LMWH), a natural sulfated glycosaminoglycan with an affinity for proangiogenic factors, is produced by chemical or enzymatic depolymerization of unfractionated heparin (UFH). Known for its anticoagulant effects, LMWH has recently been reported to have a strong anti-inflammatory effect on colitis, myocarditis, and airway inflammation. However, as a newly-developed drug, its anti-inflammatory mechanism in upper respiratory tract inflammation has not been well-studied. Methods: SD rats were randomly divided into control and experimental groups. The experimental group was established by building an acute nasal sinusitis model with expansion sponges mixed with Streptococcus pneumoniae. Then the experimental group rats were subcutaneously injected with different concentrations of LMWH. After seven consecutive days of injection, some rats were sacrificed, and blood and nasal mucosa samples were taken to determine their inflammation status. The remaining acute sinusitis rats were randomly selected for a week of nasal irrigation with normal saline or saline mixed with different concentrations of LMWH. One week later, rats were sacrificed, and samples of blood and nasal mucosa were taken to determine the inflammation status. Results: Rat nasal mucosa in the model group had obvious inflammation. The degree of nasal mucosa inflammation damage in the experimental group was lower than in the experimental control group, proving that LMWH has a protective effect on the nasal mucosa and that the effect correlates with dosage. Irrigation of the nose with saline mixed with LMWH can improve the anti-inflammatory effect. Protein related to the TLR4-MyD88-NF-κB signaling pathway was activated in the acute sinusitis rat model, and LMWH can significantly inhibit its expression. Conclusion: This is the first report of the anti-inflammatory effect of LMWH in acute upper respiratory tract inflammation, together with an explanation of its anti-inflammatory mechanism. The findings contribute a theoretical basis for its potential anti-tumor effect.

Project description:BackgroundThere is currently no effective treatment for vascular dementia (VaD). Scalp electroacupuncture (EA) has served clinically as an alternative treatment for VaD, but its mechanism is still unclear. In this study, we investigated the effect of EA at the Baihui (GV 20) and Shenting (GV 24) acupoints on spatial learning and memory ability, and the expression level of microRNA-81 (miR-81), interleukin-16 (IL-16), and postsynaptic density protein-95 (PSD-95) in the frontal cortex of VaD rats.MethodsMale Sprague-Dawley rats were randomly divided into four groups, sham, VaD, non-acupuncture (non-AP) and EA group. The VaD model was established by permanent bilateral occlusion of the common carotid arteries. Morris Water Maze was used to assess the rats' spatial learning and memory. Immunochemistry (IHC), quantitative reverse transcription polymerase chain reaction (qRT-PCR), and western blot analysis were performed to detect the expression level of miR-81, IL-16, and PSD-95. Finally, luciferase assay was used to determine the effect of miR-81 on IL-16 expression in PC12 cells.ResultsThe space exploration experiment of MWM showed the time and distance of the rat's activities around the platform were decreased in the EA group. Compared to the VaD and non-AP group, the number of terminal deoxynucleotidyl transferase-mediated dUDP nick-end labeling (TUNEL)-positive frontal cortical neurons was significantly decreased in EA group. The number of the PSD-95-positive cells and the miR-81 expression level in the frontal cortical in the EA group was dramatically increased in comparison with the other groups. In the PC12 cell validation experiment, IL-16 expression level was reduced under the condition of the miR-81 mimic treatment, while increased in the miR-81 inhibitor group. The PSD-95 protein level was up-regulated in the small interfering (si)RNA-IL16 group compared to the NC-IL16 groups with or without oxygen/glucose deprivation/reperfusion (OGD/R) conditions (P<0.05). However, this was abolished by miR-81 mimic.ConclusionsIn VaD rats, EA may improve spatial learning and memory through miR-81/IL-16/PSD-95 pathway.

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Electroacupuncture Attenuates Immune-Inflammatory Response in Hippocampus of Rats with Vascular Dementia by Inhibiting TLR4/MyD88 Signaling Pathway.

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