| Inflammation refers to the defense response of the living tissue with the vascular system to the injury factor.However,excessive and chronic inflammatory reactions lead to a variety of inflammatory diseases or inflammation-related diseases,such as atherosclerosis,rheumatoid arthritis,etc.,which seriously endanger the health of patients.At present,there are many toxic and side effects in the treatment of inflammation-related diseases.The exploration of inflammatory cells and inflammatory signaling pathways and their role in the inflammatory reaction process are of great significance for finding effective and low-toxic inflammatory therapeutic drugs.As a key class of immune cells,macrophages are not only the first line of defense against pathogen invasion,but also cause excessive inflammatory reactions by secreting inflammatory factors,resulting in a variety of inflammatory diseases.Macrophages have very strong phenotypic plasticity and heterogeneity in the body’s immune response.When macrophages are stimulated by lipopolysaccharides(LPS),M1 type polarization occurs,and secreting a large number of inflammatory factors such as Tumor NecrosisFactor(TNF-α)and interleukin-1β(IL-1β),cyclooxygenase-ase(COX-2),promotes the occurrence of inflammatory reactions.Macrophages can also be stimulated by IL-4,and M2 polarization occurs,mainly secreting anti-inflammatory factors such as interleukin-10(IL-10),CD206,and human arginase 1(Arg1),inhibiting the inflammatory response.Therefore,promoting the polarization of macrophages from M1 to M2 can inhibit the inflammatory response,which is now considered as a new idea for the development of anti-inflammatory drugs.Mitogen-Activated Protein Kinases(MAPK)are a family of intracellular protein kinases,including extracellular signal-regulated kinase(ERK),mitogen-activated protein p38(MAPK p38)and c-Jun N-terminal kinase(JNK).The literature indicates that LPS stimulates macrophages to activate the phosphorylation of MAPK family proteins.Finally,the activation of nuclear factor-kB(Nuclear factor-kappa B,NF-κB)causes the release of inflammatory factors TNF-α,IL-1β,COX-2 and to trigger an inflammatory response.It is currently believed that activation of the MAPKs signaling pathway is a key molecular pathway for LPS-induced M1 type polarization in macrophages.Studies have shown that JAK Kinase 2(JAK2)/Signal transducers and activators of transcription(STAT3)signaling pathways are highly phosphorylated and activated in M2 macrophages.It is currently believed that the JAK2/STAT3 signaling pathway is an important signaling pathway in macrophage M2 polarization.Numerous studies have shown that natural compounds are an important source of drug discovery and drug design,and natural compounds have important research significance in the fields of pharmacology and clinical therapeutics.Broussonetia kazinoki is a kind of Chinese medicinal material with a wide range of functions.Its extract has anti-inflammatory,anti-oxidant and other biological activities.Broussonin E is a phenolic compound isolated from Broussonetia kazinoki.This topic was first discovered to have anti-inflammatory new functions in the early drug screening process.In this study,we explored the anti-inflammatory effect and mechanism of the natural product,Broussonin E,from the macrophage phenotypic transition and related signaling pathways.It provides an experimental basis for the natural product,Broussonin E,for the treatment of inflammation-related diseases.This research is mainly carried out from the following aspects.In the first aspect,the optimal conditions for LPS-induced RAW264.7 macrophage to establish an inflammatory cell model were determined by ELISA and MTT assays.And determine the maximum tolerated concentration of the natural compound,Broussonin E,in RAW264.7 macrophages and the effective anti-inflammatory concentration of Broussonin E in inflammatory cell models.In the second aspect,it was verified by qPCR experiments that the natural compound,Broussonin E,inhibits the release of pro-inflammatory factors and promotes the release of anti-inflammatory factors.In the third aspect,it was verified by Western Blot experiments that Broussonin E inhibited theactivation of MAPK signaling pathway proteins(ERK,P38,JNK)by LPS;It was confirmed that Broussonin E can promote the polarization of macrophages to M2 phenotype by activating JAK2/STAT3 signaling pathway and inhibiting the polarization of macrophages to M1 phenotype,and exert anti-inflammatory effects.The results of this study indicate that Broussonin E has anti-inflammatory effects,and its anti-inflammatory effect may inhibit the polarization of macrophages to M1 and promote macrophage polarization to M2 type,enhance the expression of anti-inflammatory related factors by inhibiting ERK and p38 MAPK signaling pathways and activating JAK2/STAT3 signaling pathways. |
