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

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 factorα(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-αwere 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.

Therapeutic Effect of Crocin on Diabetic Retinopathy in Rats Based on TLR4/My D88/NF-κB Pathway

Objective:To study the therapeutic effect of crocin on diabetic retinopathy(DR)in rats based on toll-like receptor 4(TLR4)/myeloid differentiation factor 88(My D88)/nuclear factor-κB(NF-κB)pathway.Methods:Thirty SPF SD rats were used in the experiment,which were randomly divided into DR group,control group and crocin group,with 10 rats in each group.The DR rat model was established by feeding the rats in both the DR group and crocin group with a high glucose and high fat diet,along with intraperitoneal injection(IP)of streptozotocin.Crocin IP was administered to the rats in the crocin group,whereas the rats in the DR group and control group received an equivalent dosage of saline IP for 12 weeks.A comparison was made among the three groups regarding retinal thickness,vascular permeability,expression of TLR4/My D88/NF-κB pathway protein,levels of inflammatory factors,and levels of Bcl-2,Bax,and Bcl-2/Bax.Results:The DR group and crocins group exhibited a lower retinal thickness compared to the control group,while the crocins group displayed a higher thickness than the DR group.The DR group and crocins group had higher retinal vascular permeability than the control group,and the crocins group had lower retinal vascular permeability than the DR group(P<0.05).TLR4,My D88,and P-NF-κB relative expressions were higher in the DR and crocin groups than in the control group,whereas TLR4,My D88,and P-NF-κB relative expressions were lower in the crocin group than in the DR group(P<0.05).The DR group and crocin group exhibited elevated levels of inflammatory cytokines compared to the control group,while the crocin group displayed decreased levels in comparison to the DR group(P<0.05).The DR group and crocin group exhibited lower levels of Bcl-2 and Bcl-2/Bax compared to the control group,whereas the control group displayed higher levels of Bax.The crocin group exhibited elevated levels of Bcl-2 and Bcl-2/Bax compared to the DR group,whereas the DR group displayed diminished levels of Bax(P<0.05).Conclusion:Crocin has the potential to enhance the retinal thickness and vascular permeability of DR rats,and the inhibition of the TLR4/My D88/NF-κB pathway by crocin could play a crucial role in impeding the advancement of DR.

Toll样受体4介导的MyD88信号通路在脑缺血损伤中的作用

脑缺血损伤发生机制十分复杂,目前有多种相关学说,大量研究表明炎症反应是脑缺血损伤主要机制之一,然而炎性瀑布反应触发后更加剧了脑损伤的发展,其中炎性受体发挥了重要作用。研究表明Toll样受体4(TLR4)在脑缺血的发生、发展和继发性脑损伤中起重要作用,髓样分化因子88(MyD88)是TLR4信号转导通路中关键的衔接蛋白,能够启动下游炎性因子的转导。对TLR4介导的MyD88信号通路在脑缺血损伤中的作用进展做一综述。