Propolis Components And Mechanisms On Macrophage-associated Inflammation

Macrophages are an important barrier to the body's innate immunity and play an irreplaceable role in sterilization,phagocytosis,and tissue damage repairing.Macrophages exist in almost all tissues.When the body is damaged,macrophages secrete a large number of inflammatory factors,such as TNF-? and IL-1?,triggering or amplifying inflammatory reactions,thereby promoting the body to eliminate pathogens.In general,the inflammatory response will disappear in time after the pathogen is removed.However,if the inflammatory response is too intense or external stimuli persist,it will cause continuous inflammatory reactions and even body damage and chronic diseases such as colitis and diabetes.As the longest digestive organ,the intestine is in direct contact with the external environment and is constantly exposed to environmental factors,including various foods and microorganisms.The intestine contains a large number of macrophages,ensuring the best defense against millions of intestinal bacteria and protecting the host from inflammation,which is important for maintaining the mucosal homeostasis of the microbiota surface and the constantly renewed epithelium cells.If the homeostasis is disrupted,it will trigger a series of inflammatory reactions.Inflammatory Bowel Disease(IBD)is a typical intestinal inflammatory injury,and the number of macrophages in IBD patients is significantly increased.As a natural product of medicinal and food homology,propolis is rich in flavonoids and polyphenols.These substances have been proven to have a variety of health functions,such as anti-cancer,antioxidant and anti-inflammatory effects.This article mainly intends to analyze the composition of propolis,and based on its composition characteristics,using IBD as a model to further explore whether the protective effect of propolis on inflammatory bowel disease and its mechanism are related to targeting macrophages.In order to confirm the above conjecture,total phenol and total flavonoid content in propolis were measured by chemical methods,and qualitative and quantitative analysis of some flavonoids were performed by UPLC.It was found that propolis contains rich flavonoids and polyphenols.Substances,among which chrysin and caffeic acid phenethyl ester,have the highest abundance,suggesting that propolis is likely to have anti-inflammatory activity.So,we performed a 3% Dextran sulfate sodium salt(DSS)-induced mouse colitis model in vivo.Mice were randomly divided into three groups: control group,DSS group and 0.01% propolis(PE)group.The control group was given drinking water and chow diet.DSS group and propolis group were both given 3%(w/v)DSS dissolved in drinking water,and chow feed or feed supplemented with 0.01% propolis extract,respectively.After a week of dietary intervention,we found that half of the mice in the DSS group died.The integrity of the colon was also damaged,and obvious macrophage infiltration occurred.After propolis treatment,these phenomena were significantly improved,indicating that propolis has a good protective effect on colitis.We then explored the mechanism by which propolis inhibits macrophages to resist inflammation.We found that intestinal macrophage infiltration in mice was significantly reduced after propolis treatment,and the expression levels of inflammatory factors such as TNF-? and IL-1? were significantly down-regulated.An in vitro inflammation model of monocyte macrophages was then used and expression of inflammatory factors were inhibited by propolis confirmed by Real Time-PCR.Induced phosphorylation of p65,p38 and ERK by those inflammatory factors were also significantly inhibited after propolis treatment analyzed by Western Blotting.In summary,propolis treatment can inhibit the inflammatory activation of macrophages by inhibiting the phosphorylation of p65,p38 and ERK-related inflammation pathways,thereby inhibiting the inflammatory response.