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Interleukin-1 receptor associated kinase 4 (IRAK-4), acting as a serine threonine kinase, is considered as a key signal node for the transduction of IL-1R family and TLRs signal pathway. Studies have found that IRAK-4 has a hand in many signal pathways, involving the inflammatory response of human joints, intestines, liver and nervous system, as well as other autoimmune diseases. It is also one of the causes of drug resistance of some cancer cells. Therefore, IRAK-4 tends to be an effective therapeutic target for inflammatory diseases and cancer. The prospects for the development of drugs in this pathway is to develop novel IRAK-4 small molecule inhibitors and investigate their safety and effectiveness, enrich the clinical treatment of inflammatory and cancer diseases finally. This paper classified and summarized the latest research progress on small molecule inhibitors of IRAK-4 signaling pathway according to structures of the compounds, in order to provide assistances and references for the research and development of related drugs.
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Objective To explore the effects of bilirubin on myeloid differentiation factor 88 (MyD88)and interleukin-1 receptor associated kinase-4(IRAK-4).Methods Seven-day-old Sprague Daw-ley rats (clean grade),male or female,weighing 12.0 to 15.0 g,were randomly assigned to 6 groups.There were normal saline group(Ⅰ),lipopolysaccharide(LPS)control group (LPS,Ⅱ),15 mg /kg bilirubin con-trol (free-LPS)group (Ⅲ),15 mg /kg group (Ⅳa),30 mg /kg group (Ⅳb)and 50 mg /kg group (Ⅳc), and then subsequently divided into 2 h,5 h and 24 h subgroups in each groups.Some of the 200 newborn rats died amid the experiment.Finally a total of 144 were involved in the analysis of results,and 8 rats in each subgroups.Newborn Sprague Dawley rats were administered at various doses of bilirubin (15 mg /kg, 30 mg /kg and 50 mg /kg respectively)intravenously;1 h after injection,the rats were administered LPS intrap-eritoneally at a dose of 1 mg /kg;MyD88 and IRAK-4 were detected by immunohistochemistry at 2 h,5 h and 24 h after the injection of bilirubin.Results (1 )LPS could stimulate the expression of MyD88 and IRAK-4 in spleen cells (qMyD88 2 h =49.89,qMyD88 5 h =139.54,qIRAK-4 2 h =7.93,qIRAK-4 5 h =24.30,qIRAK-4 24 h =6.97 ,P 0.05).Effects of medium and high concentration of bilirubin on LPS stim-ulation MyD88 were inhibitory(qⅣb 2 h =42.87,qⅣc 2 h =51.38,qⅣb 5 h =103.61 ,qⅣc 5 h =1 15.44,qⅣb 24 h =1.18,qⅣc 24 h =1 1.66,P <0.01 ).(4)Effects of low,medium and high concentration of bilirubin on LPS stimulation IRAK-4 were inhibitory(qⅣa 2 h =9.52,qⅣb 2 h =14.39,qⅣc 2 h =25.55,qⅣa 5 h =38.83,qⅣb 5 h =54.62,qⅣc 5 h =60.51 ,qⅣa 24 h =2.41 ,qⅣb 24 h =1.47,qⅣc 24 h =7.61 ,P <0.01 ).(5)The inhibition of biliru-bin to MyD88 and IRAK-4 was observed at 2 h,strengthened at 5 h,disappeared at 24 h in low-mid concen-trations of bilirubin(P <0.01 )while still visible at 24 h in high concentration of bilirubin.(6)There was neg-atively correlation between the expression level of MyD88,IRAK-4 and bilirubin concentration(rsMyD88 2 h =-0.86, rsMyD88 5 h =-0.92,rsMyD88 24 h =-0.53,rsIRAK-4 2 h =-0.82,rsIRAK-4 5 h =-0.86,rsIRAK-4 24 h =-0.57,P <0.01).(7) Under the effect of bilirubin and LPS,there were positively correlation between the expression levels of MyD88 and IRAK-4 of spleen cells(r2 h =0.77,r5 h =0.9,r24 h =0.67,P <0.01).Conclusion Bilirubin could inhibit the expression of MyD88 and IRAK-4.As the concentration of bilirubin increasing,its inhibition is more obvious and prolonged.The mechanism that bilirubin affects immune function of newborn rat may be related to regulation of expression of MyD88 and IRAK-4 at toll-like receptor 4 signal pathway.
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Objective To investigate the dynamic changes of interleukin-1 receptor-associated kinases (IRAK-4) in hypoxic neurons and explore their role in regulation of inflammatory reaction. Methods The B35 cells exposed to hypoxia of 3% O2,5% CO2 and 92% N2 were cultured for 1,3,6, 12,24,48,72 and 96 hours respectively. Then, mRNA and protein expressions of IRAK-4 were detected by RT-PCR and Western blot, the expression of IRAK-4 in the cells were observed by laser scanning con-focal microscope (LSCM), and the concentration of IL-6 was measured by ELISA method. Results After hypoxia, the mRNA and protein expressions of IRAK-4 were increased at one hour, reached the peak at six hours (P<0.05), kept at a high level at 12 hours (P<0.05) , but decreased gradually to the normal oxygen level at 24 hours (P < 0.05) and to below the normal oxygen level at 48 hours (P < 0.05). Immunofluorescence results showed that the fluorescence intensity of IRAK-4 was gradually increased with time. The changes of IL-6 in the supernatant were positively correlated with protein expression of IRAK-4 (r =0.84, P < 0.05 ). Conclusions Hypoxia can increase the expression of IRAK-4 at transcription and translation levels in a certain period of time, which may participate in down-stream inflammatory reaction and lead to increase of IL-6 expression.
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Objective To explore the mechanism of the microglia inflammatory response through observing the changes of interleukin-1 receptor associated kinase-4(IRAK-4) expression in murine N9 microglia cells under hypoxia.Methods N9 cells were exposed to 3%O2,5%CO2,92%N2 for 1,3,6,12 and 24 h respectively.The IRAK-4 protein level was detected by Western blotting and the celluar change was observed by laser scanning confocal microscope(LSCM).The TNF-? level was measured by ELISA.Results After hypoxia,the expression of IRAK-4 protein was increased in a time-dependent manner.The elevation began at 1 h after hypoxia,increased significantly at 3 h(P0.05).The fluorescence intensity of IRAK-4 also increased with the extension of anoxic time.The TNF-? level change were similar.There were significant positive correlations between the expression of IRAK-4 and TNF-?(P
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AIM: To observe the changes of interleukin1 receptor associated kinase-4(IRAK-4) in ischemia/reperfusion(I/R) liver pretreated with lipopolysaccharide(LPS) and to explore the protective mechanisms of LPS pretreatment against hepatic I/R injury.METHODS: Male Sprague-Dawley rats,weighing 240-280 g,were divided into three groups: control,ischemia/reperfusion group(I/R group) and LPS-pretreated group(LPS group).On the first day,LPS group received 0.1 mg/kg LPS via the tail vein,followed by 0.5 mg/kg on the 2nd,3rd,4th and 5th day.I/R group received the equivalent volumes(0.5 mL) of sterile PBS.Experiments of I/R injury was induced by temporary ischemia of the left lateral liver lobe for 90 min followed by 3 h reperfusion on 2 days after the last LPS treatment.At 0 min,60 min and 180 min after reperfusion,the expression of IRAK-4 gene and protein level were determined by RT-PCR and Western blotting.The activity of NF-?B and the serum TNF-? level were also detected by ELISA.RESULTS: Although the level of IRAK-4 gene and protein were higher in the LPS group than that in I/R group and control group(P0.05) at 0 min after reperfusion.However,all those indexes were evidently lower in the LPS group than those in I/R group(P