Role of Toll-like receptor 4 and Janus kinase and signal transducer and activator of transcription signal transduction pathway in sepsis-induced brain damage

The Janus kinase and signal transducer and activator of transcription （JAK/STAT） signal transduction pathway is involved in sepsis-induced functional damage to the heart, liver, kidney, and other organs. However, the cellular and molecular mechanisms underlying sepsis-induced brain damage remain elusive. In the present study, we found severe loss of neurons in the hippocampal CA1 region in rats with sepsis-induced brain damage following intraperitoneal injection of endotoxin, The expression of toll-like receptor 4, tumor necrosis factor a, and interleukin-6 was significantly increased in brain tissues following lipopolysaccharide exposure. AG490 （JAK2 antagonist） and rapamycin （STAT3 antagonist） significantly reduced neuronal loss and suppressed the increased expression of toll-like receptor 4, tumor necrosis factor a, and interleukin-6 in the hippocampal CA1 region in sepsis-induced brain damaged rats. Overall, these data suggest that blockade of the JAK/STAT signal transduction pathway is neuroprotective in sepsis-induced brain damage via the inhibition of toll-like receptor 4, tumor necrosis factor a, and interleukin-6 exoression.

Chaihu Longgu Muli Decoction relieving temporal lobe epilepsy in rats by inhibiting TLR4 signaling pathway through miR-146a-3p and miR-146a-5p

Objective To explore the effect and mechanism of Chaihu Longgu Muli Decoction(柴胡龙骨牡蛎汤,CHLGMLD)in rats with temporal lobe epilepsy(TLE).Methods A total of 80 Sprague-Dawley(SD)male rats were randomized into control(CON),model(MOD),carbamazepine(CBZ,0.1 g/kg),CHLGMLD low dose(CHLGMLD-L,12.5 g/kg),and high dose(CHLGMLD-H,25 g/kg)groups,with 16 rats in each group.TLE rat models were established in the four groups with the use of lithium-pilocarpine except for the CON group.After the successful establishment of TLE models,all drugs were administered through gavage,and distilled water was given to rats in the CON and MOD groups for four weeks.The frequency and duration of seizures before and after treatment were recorded for the evaluation of the alleviation degree.Quantitative real-time polymerase chain reaction(qRT-PCR)was used to detect the expression levels of miR-146a-3p and miR-146a-5p.The expression levels of toll-like receptor 4(TLR4),interleukin-1 receptor-associated kinase 1(IRAK1),tumor necrosis factor(TNF)receptor-associated factor 6(TRAF6),TAK1-binding protein(TAB),nuclear factor-kappa B(NF-κB),and interleukin-1 beta(IL-1β)in hippocampus were tested by immunofluorescence assay.Correlation analysis between the above factors and expressions of miR-146a-3p and miR-146a-5p were performed separately.Results CHLGMLD decreased the frequency(P<0.05)and duration(P<0.01)of seizures in rats.CHLGMLD down-regulated the expression levels of miR-146a-5p and miR-146a-3p(P<0.05),and inhibited the expression levels of TLR4,IRAK1,TRAF6,TAB,NF-κB,and IL-1β(P<0.01).The correlation analysis revealed that the expression levels of TLR4,IRAK1,TRAF6,TAB,NF-κB,and IL-1β were positively correlated with the expression levels of miR-146a-3p and miR-146a-5p detected by qRT-PCR,respectively(P<0.01).Conclusion CHLGMLD can inhibite the TLR4 signaling pathway by lowering the expression levels of miR-146a-3p and miR-146a-5p to alleviate hippocampal dentate gyrus inflammation in TLE rats,thus relieving seizures.

Oxymatrine reduces neuroinflammation in rat brain A signaling pathway

Cerebral neuroinflammation models were established by injecting 10μg lipopolysaccharide into the hippocampus of male Sprague-Dawley rats. The rats were treated with an intraperitoneal injection of 120, 90, or 60 mg/kg oxymatrine daily for three days prior to the lipopolysaccharide injection. Twenty-four hours after model induction, the hippocampus was analyzed by real-time quantitative PCR, and the cerebral cortex was analyzed by enzyme-linked immunosorbent assay and western blot assay. The results of the enzyme-linked immunosorbent assay and the real-time quantitative PCR showed that the secretion and mRNA expression of the pro-inflammatory cytokines interleukin-113 and tumor necrosis factor-a were significantly decreased in the hippocampus and cerebral cortex of model rats treated with oxymatrine. Western blot assay and real-time quantitative PCR analysis indicated that toll-like receptor 4 mRNA and protein expression were significantly decreased in the groups receiving different doses of oxymatrine. Additionally, 120 and 90 mg/kg oxymatrine were shown to reduce protein levels of nuclear factor-KB p65 in the nucleus and of phosphorylated IKBa in the cytoplasm of brain cells, as detected by western blot assay. Experimental findings indicate that oxymatrine may inhibit neuroinflammation in rat brain via downregulating the expression of molecules in the toll-like receptor 4/nuclear factor-KB signaling Dathwav.

Melatonin inhibits high glucose-induced cell proliferation and expressions of inflammatoryfactor via Toll-like receptor 4 signaling pathway inmouse mesangial cells

Objective To investigate effects of melatonin (MT)on high glucose-induced cell proliferation,Toll-like receptor4 ( TLR4) signaling pathway and expressions ofinflammatory factor in mouse mesangial cells ( SV40).Methods SV40 cells were divided into mannitol controlgroup ( 30 mmol /L mannitol ),normal control group(5 mmol /L glucose),control ( 5 mmol /L glucose) +1000 μmol /L MT group,high glucose group (25 mmol /L glucose),high glucose + 10,100,1000 μmol /L MTgroup and high glucose + TLR4 inhibitor ( TAK242 )group. (1) The cell viability was measured by CCK-8cytotoxicity kits,and cell proliferation was measured byEdU kits. The expression of TLR4 and the nuclear translocationof nuclear factor-κB ( NF-κB p65 ) were observedby immunofluorescence.

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.

Effect of Soothing Gan(Liver) and Invigorating Pi(Spleen) Recipes on TLR4-p38 MAPK Pathway in Kupffer Cells of Non-alcoholic Steatohepatitis Rats

Objective: To investigate the mechanism of inflammatory-mediated toll-like receptor 4(TLR4)-p38 mitogen-activated protein kinase(p38 MAPK) pathway in Kupffer cells(KCs) of non-alcoholic steatohepatitis(NASH) rats and the intervention effect of soothing Gan(Liver) and invigorating Pi(Spleen) recipes on this pathway. Methods: After 1 week of acclimatization, 120 Sprague-Dawley male rats were randomly divided into 8 groups using a random number table(n=15 per group): normal group, model group, low-dose Chaihu Shugan Powder(柴胡疏肝散, CHSG) group(3.2 g/kg), high-dose CHSG group(9.6 g/kg), low-dose Shenling Baizhu Powder(参苓白术散, SLBZ) group(10 g/kg), high-dose SLBZ(30 g/kg) group, and low-and highdose integrated recipe(L-IR, H-IR) groups. All rats in the model and treatment groups were fed with a high-fat diet(HFD). The treatments were administrated by gastrogavage once daily and lasted for 26 weeks. The liver tissues were detected with hematoxylin-eosin(HE) and oil red O staining. Levels of liver lipids, serum lipids and transaminases were measured. KCs were isolated from the livers of rats to evaluate the mRNA expressions of TLR4 and p38 MAPK by real-time fluorescence quantitative polymerase chain reaction, and proteins expressions of TLR4, p-p38 MAPK and p38 MAPK by Western blot. Levels of inflammatory cytokines including tumor necrosis factor α(TNF-α), interleukin(IL)-1 and IL-6 in KCs were measured by enzyme-linked immunosorbent assay. Results: After 26 weeks of HFD feeding, HE and oil red O staining showed that the NASH model rats successfully reproduced typical pathogenesis and histopathological features. Compared with the normal group, the model group exhibited significant increases in body weight, liver weight, liver index, serum levels of total cholesterol(TC), triglyceride(TG), low-density lipoprotein cholesterol, and aspartate aminotransferase as well as TC and TG levels in liver tissues, and significant decrease in serum level of high-density lipoprotein cholesterol(P<0.05 or P<0.01), while those indices were significantly ameliorated in the H-IR group(P<0.05 or P<0.01). Higher levels of TNF-α, IL-1 and IL-6 in KCs were observed in the model group compared with the normal group(P<0.01). Significant decreases in TNF-α, IL-1 and IL-6 were observed in the H-SLBZ, H-IR and L-IR groups compared with the model group(P<0.05 or P<0.01). The m RNA expressions of TLR4 and p38 MAPK and protein expressions of TLR4, p38 MAPK and p-p38 MAPK in KCs in the model group were significantly higher than the normal group(P<0.01), while those expression levels in the L-IR and H-IR groups were significantly lower than the model group(P<0.05 or P<0.01). Conclusions: Inflammation in KCs might play an important role in the pathogenesis of NASH in rats. The data demonstrated the importance of TLR4-p38 MAPK signaling pathway in KCs for the anti-inflammatory effect of soothing Gan and invigorating Pi recipes.

Multiomics reveal human umbilical cord mesenchymal stem cells improving acute lung injury via the lung-gut axis

BACKGROUND Acute lung injury(ALI)and its final severe stage,acute respiratory distress syndrome,are associated with high morbidity and mortality rates in patients due to the lack of effective specific treatments.Gut microbiota homeostasis,including that in ALI,is important for human health.Evidence suggests that the gut microbiota improves lung injury through the lung-gut axis.Human umbilical cord mesenchymal cells(HUC-MSCs)have attractive prospects for ALI treatment.This study hypothesized that HUC-MSCs improve ALI via the lung-gut microflora.AIM To explore the effects of HUC-MSCs on lipopolysaccharide(LPS)-induced ALI in mice and the involvement of the lung-gut axis in this process.METHODS C57BL/6 mice were randomly divided into four groups(18 rats per group):Sham,sham+HUC-MSCs,LPS,and LPS+HUC-MSCs.ALI was induced in mice by intraperitoneal injections of LPS(10 mg/kg).After 6 h,mice were intervened with 0.5 mL phosphate buffered saline(PBS)containing 1×10^(6) HUC-MSCs by intraperitoneal injections.For the negative control,100 mL 0.9%NaCl and 0.5 mL PBS were used.Bronchoalveolar lavage fluid(BALF)was obtained from anesthetized mice,and their blood,lungs,ileum,and feces were obtained by an aseptic technique following CO_(2) euthanasia.Wright’s staining,enzyme-linked immunosorbent assay,hematoxylin-eosin staining,Evans blue dye leakage assay,immunohistochemistry,fluorescence in situ hybridization,western blot,16S rDNA sequencing,and non-targeted metabolomics were used to observe the effect of HUC-MSCs on ALI mice,and the involvement of the lung-gut axis in this process was explored.One-way analysis of variance with post-hoc Tukey’s test,independent-sample Student’s t-test,Wilcoxon rank-sum test,and Pearson correlation analysis were used for statistical analyses.RESULTS HUC-MSCs were observed to improve pulmonary edema and lung and ileal injury,and decrease mononuclear cell and neutrophil counts,protein concentrations in BALF and inflammatory cytokine levels in the serum,lung,and ileum of ALI mice.Especially,HUC-MSCs decreased Evans blue concentration and Toll-like receptor 4,myeloid differentiation factor 88,p-nuclear factor kappa-B(NF-κB)/NF-κB,and p-inhibitorαof NF-κB(p-IκBα)/IκBαexpression levels in the lung,and raised the pulmonary vascular endothelial-cadherin,zonula occludens-1(ZO-1),and occludin levels and ileal ZO-1,claudin-1,and occludin expression levels.HUC-MSCs improved gut and BALF microbial homeostases.The number of pathogenic bacteria decreased in the BALF of ALI mice treated with HUCMSCs.Concurrently,the abundances of Oscillospira and Coprococcus in the feces of HUS-MSC-treated ALI mice were significantly increased.In addition,Lactobacillus,Bacteroides,and unidentified_Rikenellaceae genera appeared in both feces and BALF.Moreover,this study performed metabolomic analysis on the lung tissue and identified five upregulated metabolites and 11 downregulated metabolites in the LPS+MSC group compared to the LPS group,which were related to the purine metabolism and the taste transduction signaling pathways.Therefore,an intrinsic link between lung metabolite levels and BALF flora homeostasis was established.CONCLUSION This study suggests that HUM-MSCs attenuate ALI by redefining the gut and lung microbiota.