Efficacy of Sishen Wan on dinitrobenzene sulfonic acid-induced ulcerative colitis and its effect on toll-like receptor 2/interleukin-1 receptor-associated kinase-4/nuclear factor-κB signal pathway.

OBJECTIVE: To investigate the therapeutic effect of Sishen Wan (, SSW) on ulcerative colitis (UC) induced by dinitrobenzene sulfonic acid and its effect on toll-like receptor 2/interleukin-1 receptor-associated kinase-4/nuclear factor-κB (TLR2/IRAK4/NF-κB) sig-naling pathway in colonic tissue. METHODS: In this study, 120 Sprague-Dawley rats were randomly divided into blank and model groups. The experimental UC model in rats was established by subcutaneous injection of hydrocortisone + senna gavage for 21 d + dinitrobenzene sulfonic acid (DNBS)/ ethanol solution enema. The successful model rats were randomly divided into the model group; mesalazine (0.36 g/kg) group; and high-, medium-, and low- dose SSW (24, 12, and 6 g/kg) groups. The model and blank groups were gavaged with equal volumes of distilled water once a day for 21 d. The general condition of the rats was observed, and the body mass, fecal properties, and occult blood were recorded for calculating the disease activity index (DAI) score. The colonic tissue of the rats was collected, and its general morphology and pathological form were noted for obtaining the colonic mucosal injury index (CMDI) score. Hematoxylin-eosin staining was used to view the pathological changes of the colon tissue in each group, apoptosis of the cells was detected using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining, and quantitative real-time polymerase chain reaction was used to measure the expressions of TLR2, myeloid differentiation primary response gene 88 (MyD88), IRAK4, and NF-κB p65 mRNA in the colon tissue. The expressions of TLR2, MyD88, IRAK4, and NF-κB p65 protein were detected using western blotting and immunohistochemistry assay, and the levels of interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α) in the colon tissue were determined using enzyme linked immunosorbent assay. RESULTS: Compared with the blank group, the general condition of the model group was relatively poor. The DAI and CMDI scores of the model group increased significantly (< 0.01), the glands and intestinal mucosa disappeared partially, and several inflammatory cells infiltrated and gathered in the mucosal layer and base layer of the rats in the model group. Furthermore, the cell apoptosis and expression levels of TLR2, MyD88, IRAK4, and NF-κB p65 mRNA and protein in the colon tissue of rats in the model group increased significantly (< 0.01). The levels of IL-1ß and TNF-α increased significantly in the colon tissue of rats in the model group (< 0.01). After treatment with SSW, compared with the model group, the general condition of the UC rats improved. Moreover, the DAI and CMDI scores of the UC rats decreased significantly (< 0.05), and the pathological changes in the colon tissue of the UC rats tended to be normal. The cell apoptosis and expression levels of TLR2, MyD88, IRAK4, and NF-κB p65 mRNA and protein in the colon tissue of the UC rats decreased gradually ( < 0.01), and the levels of IL-1ß and TNF-α decreased significantly (< 0.01). CONCLUSION: SSW can improve the general condition and alleviate the intestinal mucosal injury of UC model rats. Additionally, SSW can inhibit the TLR2/IRAK4/ NF-κB signaling pathway, but further studies are required to confirm it.

Mechanism of miRNA-146b regulating proliferation, metastasis and apoptosis of thyroid papillary carcinoma cells / 中华内分泌外科杂志

Objective:To investigate the role and mechanism of miR-146b in the proliferation, metastasis and apoptosis of thyroid papillary carcinoma cells.Methods:qRT-PCR was used to detect the expression of miR-146b in thyroid papillary carcinoma cells (NPA, GLAG-66, ONCNO-DG1 and B-CPAP) and normal human thyroid cell line HTori3. After B-CPAP cells were transfected with miR-146b inhibitor, the inhibition efficiency was detected by qRT-PCR, the effect of miR-146b on PTC cells proliferation was detected by MTT assay, the effect of miR-146b on PTC cells invasion was studied by Transwell assay, and the effect of miR-146b on tumor cell apoptosis was detected by flow cytometry. SiRNA-IRAK1 was transfected into B-CPAP cell line. The cell proliferation rate, migration ability and apoptosis rate were detected by MTT, cell scratch test and flow cytometry respectively. The target gene of miR-146b, interleukin-1 associated receptor kinase 1 (IRAK1) , was predicted by bioinformatics software, and the regulatory effect of miR-146b on IRAK1 was verified by double fluorescein reporter gene experiment.Results:QRT-PCR showed that the expression of miR-146b in NPA87, KAT-5, FTC-133 and B-CPAP cell lines was significantly higher than that in normal cell HTori3, especially B-CPAP ( P<0.05) . MiR-146b inhibitor transfection could significantly reduce the expression level of miR-146b in B-CPAP cells ( P<0.01) . MTT results showed that miR-146b inhibitor could inhibit the proliferation of B-CPAP cells ( P<0.05) . Flow cytometry showed that miR-146b inhibitor could promote the apoptosis of B-CPAP cells ( P<0.05) . Transwell results showed that miR-146b inhibitor could reduce the invasive ability of B-CPAP cells ( P<0.05) . After transfection with siRNA-IRAK1, the proliferation rate of B-CPAP cells increased significantly (MTT test) , the migration ability increased (cell scratch test) , and the apoptosis rate decreased significantly (flow cytometry) ( P<0.05) . The results of double luciferase reporter gene showed that irak1 was the target gene of miR-146b, and miR-146b inhibitor could significantly up regulate the expression level of irak1 protein in B-CPAP cells. Conclusion:miR-146b may play a role in promoting the proliferation and metastasis and inhibiting cell apoptosis of PTC cells by inhibiting the downstream target protein IRAK1.

Molecular features of interleukin-1 receptor-associated kinase-b and a in Mytilus coruscus, regulating their function by infection of aquatic pathogens and the expression of their serine/threonine protein kinase functional domains.

Interleukin-1 receptor-associated kinases (IRAKs) play important roles in the innate immune system of TLR (Toll-like receptor) signaling pathway. In this paper, interleukin-1 receptor-associated kinase-b (designated as McIRAK-b) and interleukin-1 receptor-associated kinase-a (named as McIRAK-a) were obtained based on the transcriptome data, the full length of McIRAK-b was 1815 bp and McIRAK-a was 3168bp, encoding 532 and 978 amino acids, respectively. BLASTp analysis and phylogenetic relationship strongly suggested that the deduced amino acid sequence of McIRAK-b had high homology with IRAK-4 and McIRAK-a was similar to IRAK-1 of other mollusks, especially at their function domains. The expressions of McIRAK-b and McIRAK-a were detected in six tissues including adductor muscle, hemocyte, gills, gonad and hepatopancreas, and the highest expressions appeared both in gills. The expressions of McIRAK-b and McIRAK-a in gills were observed with time-dependent manners after bacterial infections. After being challenged with Vibrio alginolyticus, McIRAK-b expressed significantly and got the peak at 8 h (9.47 times compared with the control group), but the peak appeared at 4 h by being infected with Vibrio parahaemolyticus (12.02 times compared with the control group). The highest point of McIRAK-a mRNA appeared at 12 h (5.16 times) after being challenged with V.alginolyticus and 8 h (4.21 times) for V.parahaemolyticus challenge. The results suggested that IRAK-b and IRAK-a might be important in immune signaling pathway of mussels. The kinase functional domain sequences (S_TKc) of McIRAK-b and McIRAK-a expressed in BL21(DE3) and purified by Ni-NAT Superflow resin conforming to the expected molecular weight with many active sites for their conferring protein-protein interaction functions. This study may provide some further understandings of the regulatory mechanisms in the bivalve innate immune system for IRAKs family.

Down-regulation of IRAK1 attenuates podocyte apoptosis in diabetic nephropathy through PI3K/Akt signaling pathway.

Diabetic nephropathy (DN) is one of the most common microvascular complications of diabetes mellitus and often results in chronic renal failure. Here, we found that Interleukin 1 receptor associated kinases (IRAK1) was up-regulated in kidney in both DN patients and high-fat diet (HFD)/streptozotocin (STZ)-induced diabetic mice. In vivo, down regulation of IRAK1 ameliorated renal injury and function, with lower podocyte apoptosis, increased expression of Nephrin, attenuated thickness of the glomerular basement membrane and podocyte footprocess effacement. Furthermore, in vitro, down regulation of IRAK1 in podocytes treated with high glucose (HG), podocyte apoptosis and inflammatory cytokines were significantly decreased, but Nephrin increased. Meanwhile, apoptosis-related genes caspase-3/-9 were inhibited and phosphorylation levels of PI3K/Akt were dramatically down regulated. Thus, IRAK1 is one of the critical components involved in podocyte apoptosis in DN.

Crystal structure of human IRAK1.

Interleukin 1 (IL-1) receptor-associated kinases (IRAKs) are serine/threonine kinases that play critical roles in initiating innate immune responses against foreign pathogens and other types of dangers through their role in Toll-like receptor (TLR) and interleukin 1 receptor (IL-1R) mediated signaling pathways. Upon ligand binding, TLRs and IL-1Rs recruit adaptor proteins, such as myeloid differentiation primary response gene 88 (MyD88), to the membrane, which in turn recruit IRAKs via the death domains in these proteins to form the Myddosome complex, leading to IRAK kinase activation. Despite their biological and clinical significance, only the IRAK4 kinase domain structure has been determined among the four IRAK family members. Here, we report the crystal structure of the human IRAK1 kinase domain in complex with a small molecule inhibitor. The structure reveals both similarities and differences between IRAK1 and IRAK4 and is suggestive of approaches to develop IRAK1- or IRAK4-specific inhibitors for potential therapeutic applications. While the IRAK4 kinase domain is capable of homodimerization in the unphosphorylated state, we found that the IRAK1 kinase domain is constitutively monomeric regardless of its phosphorylation state. Additionally, the IRAK1 kinase domain forms heterodimers with the phosphorylated, but not unphosphorylated, IRAK4 kinase domain. Collectively, these data indicate a two-step kinase activation process in which the IRAK4 kinase domain first homodimerizes in the Myddosome, leading to its trans-autophosphorylation and activation. The phosphorylated IRAK4 kinase domain then forms heterodimers with the IRAK1 kinase domain within the Myddosome, leading to its subsequent phosphorylation and activation.

Toll-like receptor 2 dominance over Toll-like receptor 4 in stressful conditions for its detrimental role in the heart.

It has been suggested that Toll-like receptor (TLR)4 promotes IL-10-mediated cardiac cell survival, whereas another receptor, TLR2, from the same family, is detrimental. Here, we examined the interactive role of these two innate signaling molecules under stressful conditions, including IL-10 knockout (IL-10-/-) mice, global ischemia-reperfusion (I/R) injury in rat hearts, and in vitro short hairpin RNA experimental models in the presence or absence of IL-10 (10 ng/ml). Circulating and myocardial levels of TNF-α as well as apoptosis and fibrosis were higher in IL-10-/- mice. The increase in TLR2 in IL-10-/- hearts indicated its negative regulation by IL-10. Ex vivo I/R also caused a marked upregulation of TLR2 and TNF-α as well as apoptotic and fibrotic signals. However, a 40-min reperfusion with IL-10 triggered an increase in TLR4 expression and improved recovery of cardiac function. The increase in IL-1 receptor-associated kinase (IRAK)-M and IRAK-2 activity during I/R injury suggested their role in TLR2 signaling. In vitro inhibition of TLR4 activity as a consequence of RNA inhibition-mediated suppression of myeloid differentiation gene (MyD)88 suggested MyD88-dependent activation of TLR4. The inclusion of IL-10 during reperfusion also downregulated the expression of IRAK-2, TNF-α receptor-associated factor 1-interacting protein (TRAIP) and apoptotic signals, caspase-3, and the Bax-to-Bcl-xL ratio. IL-10 reduced the TNF-α receptor-associated increase in TRAIP-induced apoptosis during I/R injury, which led to an increase in IL-1ß to mitigate transforming growth factor-ß receptor type I-mediated fibrosis. The IL-10 mitigation of these changes suggests that the stimulation through TLR4 signaling promotes IRAK-4 and phosphorylates IRAK-1 instead of IRAK-2 and may be an important therapeutic approach in restoring heart health in stress.NEW & NOTEWORTHY Under stress conditions such as downregulation of the IL-10 gene or ischemia-reperfusion injury, Toll-like receptor (TLR)4 and IL-1 receptor-associated kinase (IRAK)-1 activation is suppressed, along with the upregulation of TLR-2 and IRAK-2, resulting in fibrosis and apoptosis. It is suggested that IL-10 helps to maintain heart function during stress via myeloid differentiation gene 88/IRAK-4/IRAK-1-dependent TLR4 signaling.

Involvement of interleukin-1 receptor-associated kinase-1 in vascular smooth muscle cell proliferation and neointimal formation after rat carotid injury.

OBJECTIVE: Reduced frequency of atherosclerotic plaques is observed in interleukin-1 receptor-associated kinase-1 (IRAK1)-deficient mice; however, the underlying mechanism is not clear. Therefore, this study investigate the role of IRAK1 in vascular smooth muscle cell proliferation and neointimal hyperplasia. APPROACH AND RESULTS: Stimulation of rat primary vascular smooth muscle cells with fetal bovine serum (10%) or platelet-derived growth factor-BB (20 ng/mL) for 15 minutes to 24 hours induced a time-dependent increase in IRAK1 and extracellular signal-regulated kinase (ERK) activation, proliferating cell nuclear antigen upregulation and p27Kip1 downregulation as assessed by Western blotting. Inhibitors of ERK pathway (U0126, 10 µmol/L), IRAK (IRAK1/4, 3 µmol/L), protein kinase C (PKC; Ro-31-8220, 1 µmol/L), siRNA of toll-like receptor-4 (200 nmol/L), and PKC-ε (200 nmol/L) significantly attenuated these changes. Platelet-derived growth factor induced endogenous IRAK-ERK-PKC-ε association in a toll-like receptor-4 and PKC-ε-dependent manner. A time-dependent increase in IRAK1 and ERK activation was observed after 15 minutes, 30 minutes, 1 hour, 6 hours, 12 hours, and 24 hours of carotid balloon injury in rats. Balloon injury induced endogenous IRAK-ERK-PKC-ε interaction. Perivascular application of IRAK1/4 inhibitor (100 µmol/L), U0126 (100 µmol/L), and IRAK1 siRNA (220 and 360 nmol/L) in pluronic gel abrogated balloon injury-induced ERK phosphorylation, activation, and p27Kip1 downregulation. Hematoxylin and eosin staining and immunohistochemistry of proliferating cell nuclear antigen and smooth muscle actin demonstrated that balloon injury-induced intimal thickening and neointimal vascular smooth muscle cell proliferation were significantly abrogated in the presence of IRAK1/4 inhibitor, IRAK1 siRNA, and U0126. CONCLUSIONS: IRAK1 mediates vascular smooth muscle cell proliferation and neointimal hyperplasia by regulating PKC-ε-IRAK1-ERK axis.

Autophagy-dependent PELI3 degradation inhibits proinflammatory IL1B expression.

Lipopolysaccharide (LPS)-induced activation of TLR4 (toll-like receptor 4) is followed by a subsequent overwhelming inflammatory response, a hallmark of the first phase of sepsis. Therefore, counteracting excessive innate immunity by autophagy is important to contribute to the termination of inflammation. However, the exact molecular details of this interplay are only poorly understood. Here, we show that PELI3/Pellino3 (pellino E3 ubiquitin protein ligase family member 3), which is an E3 ubiquitin ligase and scaffold protein in TLR4-signaling, is impacted by autophagy in macrophages (MΦ) after LPS stimulation. We noticed an attenuated mRNA expression of proinflammatory Il1b (interleukin 1, ß) in Peli3 knockdown murine MΦ in response to LPS treatment. The autophagy adaptor protein SQSTM1/p62 (sequestosome 1) emerged as a potential PELI3 binding partner in TLR4-signaling. siRNA targeting Sqstm1 and Atg7 (autophagy related 7), pharmacological inhibition of autophagy by wortmannin as well as blocking the lysosomal vacuolar-type H(+)-ATPase by bafilomycin A1 augmented PELI3 protein levels, while inhibition of the proteasome had no effect. Consistently, treatment to induce autophagy by MTOR (mechanistic target of rapamycin (serine/threonine kinase)) inhibition or starvation enhanced PELI3 degradation and reduced proinflammatory Il1b expression. PELI3 was found to be ubiquitinated upon LPS stimulation and point mutation of PELI3-lysine residue 316 (Lys316Arg) attenuated Torin2-dependent degradation of PELI3. Immunofluorescence analysis revealed that PELI3 colocalized with the typical autophagy markers MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 ß) and LAMP2 (lysosomal-associated membrane protein 2). Our observations suggest that autophagy causes PELI3 degradation during TLR4-signaling, thereby impairing the hyperinflammatory phase during sepsis.

Role of interleukin-1 receptor-associated kinase 4 activity in flap ischemia-reperfusion injury / 中国组织工程研究

BACKGROUND:Interleukin-1 receptor-associated kinase 4 activity-induced inflammations and infection have been extensively accepted. However, there was no report concerning its effects on flap ischemia-reperfusion injury. OBJECTIVE:To explore the significance of interleukin-1 receptor-associated kinase 4 activity in flap ischemia-reperfusion injury. METHODS:A total of 36 adult male Sprague-Dawley rats were randomized into sham-operated group (n=12), ischemia-reperfusion group (n=12) and interleukin-1 receptor-associated kinase 4 group (n=12). The models of right lower abdominal island flap ischemia-reperfusion injury were set up. Interleukin-1 receptor-associated kinase 4 group was intraperitoneal y injected with 1 mL of interleukin-1 receptor-associated kinase 4 (100μmol/L) before reperfusion. The flaps were col ected at 1, 2, 4, and 6 hours after ischemia-reperfusion injury for histopathhological observation. At 1 hour after ischemia-reperfusion, protein expression of interleukin-1 receptor-associated kinase 4 was detected in flaps. The proportion of flap survival was calculated at 7 days after surgery.RESULTS AND CONCLUSION:Histopathological observation demonstrated that compared with the ischemia-reperfusion injury group, neutrophil infiltration and edema was evidently improved, and the protein expression of interleukin-1 receptor-associated kinase 4 was gradual y reduced in the interleukin-1 receptor-associated kinase 4 group. Flap survival proportions were respectively (51.70 ±7.62)%and (86.56±12.23)%in the ischemia-reperfusion injury group and interleukin-1 receptor-associated kinase 4 group at 7 days after surgery. There were significant differences in the flap survival proportion between the two groups (P<0.01). These results showed that after flap ischemia-reperfusion injury, the inhibition of interleukin-1 receptor-associated kinase 4 activities could elevate the survival rate of transplanted flap.

(E)-3-(3,4-Dimethoxyphenyl)-1-(5-hydroxy-2,2-dimethyl-2H-chromen-6-yl)prop-2-en-1-one ameliorates the collagen-arthritis via blocking ERK/JNK and NF-κB signaling pathway.

Our previous report has shown a natural pyranochalcones-derived compound, (E)-3-(3,4-Dimethoxyphenyl)-1-(5-hydroxy-2,2-dimethyl-2H-chromen-6-yl)prop-2-en-1-one (5b), that exerted protection against carrageenan-induced hind paw edema and adjuvant-induced arthritis. In this study, collagen-induced arthritis (CIA) model was used to further examine the anti-arthritic effects of 5b in vivo; the underlying molecular mechanisms of action were also investigated using a murine monocytic cell line, RAW264.7 cells. Here we showed that oral administration of 5b (20mg/kg) significantly suppressed the progression of arthritis. Improvement in disease severity was accompanied by inhibition of CD68-positive cells in knee joint and reduced pro-inflammatory cytokines TNF-α, IL-1ß and IL-6 in serum. In vitro, 5b suppressed expressions of iNOS, cyclooxygenase-2 (COX-2), TNF-α, IL-6 and IL-1ß as well as productions of nitric oxide (NO) and prostaglandin E2 (PGE2) in lipopolysaccharide (LPS)-treated macrophages. This compound also significantly suppressed LPS-induced NF-κB activation, including phosphorylation of I-κB, degradation of I-κB, and nuclear translocation of p65 and p50. Treatment with 5b also blocked LPS-induced expression of TLR4 remarkably, suppressed degradation of IRAKs and phosphorylations of JNK and ERK, but had little effect to p38 kinase activation. These findings indicated that 5b might be a therapeutic agent for rheumatoid arthritis, and exerted an anti-inflammatory effect mainly through mediating TLR4, NF-κB and ERK/JNK signaling pathways in monocytes.

The structural network of inflammation and cancer: merits and challenges.

Inflammation, the first line of defense against pathogens can contribute to all phases of tumorigenesis, including tumor initiation, promotion and metastasis. Within this framework, the Toll-like receptor (TLR) pathway plays a central role in inflammation and cancer. Although extremely useful, the classical representation of this, and other pathways in the cellular network in terms of nodes (proteins) and edges (interactions) is incomplete. Structural pathways can help complete missing parts of such diagrams: they demonstrate in detail how signals coming from different upstream pathways merge and propagate downstream, how parallel pathways compensate each other in drug resistant mutants, how multi-subunit signaling complexes form and in particular why they are needed and how they work, how allosteric events can control these proteins and their pathways, and intricate details of feedback loops and how kick in. They can also explain the mechanisms of some oncogenic SNP mutations. Constructing structural pathways is a challenging task. Here, our goal is to provide an overview of inflammation and cancer from the structural standpoint, focusing on the TLR pathway. We use the powerful PRISM (PRotein Interactions by Structural Matching) tool to reveal important structural information of interactions in and within key orchestrators of the TLR pathway, such as MyD88.

Dynamic expressions of interleukin-1 receptor associated kinase-4 and interleukin-1 receptor associated kinase-M in rats with endotoxin tolerance and their significance / 中华传染病杂志

Objective To explore the dynamic expressions of interleukin-1 (IL-1)receptor associated kinase (IRAK)-M and IRAK-4 in rats with or without endotoxin tolerance (ETT)in acute liver failure (ALF).Methods Sixty-six male SD rats were divided into three groups:ALF group,ETT group and control group.The rats in ETT group received daily lipopolysaccharide (LPS)intraperitoneal injection for 5 days,while the rats in ALF group received daily injection with same volume of 0.75% NaCl solution.Both ETT group and ALF group received intraperitoneal injection with D-galactosamine (D-GalN)and LPS at 24 hours after the 5th injection of LPS or NaCl solution.At 2,6,12,24 and 48 h after D-GalN and LPS injection,the serum levels of tumor necrosis factor-α (TNF-α)and interleukin-6 (IL-6)were detected by enzyme-linked immunosorbent assay (ELISA).The liver pathologic changes were observed with HE staining by microscope.The mRNA expressions of IRAK-4,IRAK-M and NF-κB (p65)were detected by reverse transcriptase polymerase chain reaction (RT-PCR).The pairwise comparison between groups was done by lease significant difference (LSD)and Dunnet's t test.Results The liver pathologic changes in ETT group were much milder than those of ALF group.In ALF group,IRAK-4 mRNA/β-actin absorbance ratios at 2,6,12,24and 48 h after D-GalN and LPS challenge were 0.711 ±0.074,0.904±0.118,1.012 ±0.098,1.534±0.279 and 1.451±0.290,respectively,while the IRAK-M mRNA/β-actin absorbance ratios were 0.496±0.018,0.516±0.089,0.503±0.023,0.503±0.057 and 0.469±0.142,respectively.In ETT group,the IRAK-4 mRNA/β-actin absorbance ratios at 2,6,12,24 and 48 h after D-GalN and LPS challenge were 0.619±0.083,0.587±0.033,0.623±0.034,0.720±0.044 and 0.654±0.041,respectively,while the IRA'K-M mRNA/β-actin absorbance ratios were 0.929 ± 0.064,1.111±0.138,1.113±0.027,1.891±0.315 and 1.710±0.303,respectively.The IRAK-M mRNA expression level was significantly increased and IRAK-4 mRNA expression level was relatively decreased in ETT group compared to ALF group.The differences were all statistically significant at 2,6,12,24 and 48 h after D-GalN and LPS challenge (F= 17.305,54.921,121.031,67.607,55.279,respectively; F=19.506,43.777,110.823,302.681,202.822,respectively; F=172.003,59.519,987.055,68.463,96.601,respectively; all P＜0.05).Conclusion LPS pretreatment may induce ETT in rat model by downregulating the expression of IRAK-4 and upregulating the expression of IRAK-M.

Effects of curcumin on mRNA expression of cytokines related to Tou-like receptor 4 signaling in THP-1 cells / 中华皮肤科杂志

Objective To investigate the effects of curcumin on mRNA expression of cytokines related to Toll-like receptor (TLR) 4 signaling in THP-1 cells.Methods After pretreatment with different concentrations (50,25,12.5 mg/L) of curcumin or dexamethasone for 12 hours,THP-1 cells were stimulated by lipopolysaccharide (LPS.1 mg/L) for 4 hours followed by the collection of cells.Then total RNA was isolated from these cells and subjected to reverse transcription-polymerase chain reaction (RT-PCR) for the detection of mRNA expression of tumor necrosis factor receptor-associated factor 6 (TRAF6),interleukin-1 receptorassociated kinase (IRAK1) and nuclear factor (NF)-κB.THP-1 cells without pretreatment or stimulation served as negative control,and those only stimulated with LPS served as LPS group.Results After stimulation with LPS (1 mg/L) for 4 hours,the mRNA expressions of TRAF6,IRAK1 and NF-κB were significantly upregulated in THP-1 cells compared with negative control cells (f=38.69,39.13,23.99,all P<0.01).Curcumin of 50 mg/L and 25 mg/L significantly inhibited the mRNA expressions of TRAF6.IRAK 1 and NF-κB upregulated by LPS with an inhibition rate of more than 50% (all P<0.0 1).Conclusions Certain concentrations of curcumin can inhibit the mRNA expressions of TRAF6.IRAK1 and NF-κB.which demonstrates the regulatory effect of curcumin on the mRNA expressions of TLR4 signaling pathway-associated cytokines.