Ddr2 Regulates Macrophage Polarization And Its Role In Obesity

Objective:Obesity is an excessive increase in energy caused by excessive intake or changes in the body’s metabolism.It has been considered as the fifth leading risk factor for death.Overweight and obesity have become an urgent problem in global public health.It is of great significance to explore the pathological mechanism of obesity and determine the target gene.Some experiments have found that there is a correlation between Ddr2 gene and glucose and lipid metabolism.This study aims to construct a model of obesity induced by a high-fat diet to observe and detect the related metabolism of mice with specific deletion of Ddr2 gene in myeloid macrophages.Indicators,preliminary exploration of the effect of Ddr2 gene on glucose and lipid metabolism in metabolic dysfunction.Methods:1.Using the gene knockout technology of the Cre/Lox P system,C57BL/6 mice were used for incrossing to construct macrophage Ddr2 gene-specific knockout mice(genotype Ddr2^flox/flox-Lys MCre^+/-)And its control mice(Ddr2^flox/flox).2.Divide them into 9 mice in the Chow diet group and 12 mice in the high fat diet（high fat diet,HFD）group.In the chow diet group（chow diet,CHOW）,6 mice in the wild type（wild type,WT）group(Ddr2^flox/flox)were fed with normal diet,and 3 mice in the Conditional gene knockout（Conditional gene knockout,KO）group(Ddr2^flox/flox-Lys MCre^+/-);the HFD group was given high Fat diet（60%kcal fat）was fed with 8 mice in the WT group(Ddr2^flox/flox)and 4 mice in the KO group(Ddr2^flox/flox-Lys MCre^+/-)to construct an obese mouse model;14 weekly,weigh the body weight of the mice at a fixed time every week,and perform glucose tolerance and insulin tolerance tests on the HFD group mice to detect the glucose and lipid metabolism of the obese mice.3.Use real-time fluorescence to quantitatively detect whether there is a correlation between the obesity status of WT mice and the expression of Ddr2 m RNA in subcutaneous fat and visceral fat.4.Analyze the potential inflammatory changes after the Ddr2 gene knockout in the Chow diet group and HFD group mice,verify the effect of Ddr2 gene on the polarization typing of macrophages by real-time fluorescence quantitative method,and detect the inflammation-specific indicator gene（TNF-α,IL-6,IL-1β,i NOS,IL-12）and other m RNA expression levels.Results:1.We used C57BL/6 mice for incrossing and successfully constructed a Ddr2gene-specific knockout mouse model in macrophages(genotype is Ddr2^flox/flox-Lys MCre^+/-).2.The obese mouse model was successfully constructed.In the CHOW group,the weight of the KO group was higher than that of the WT group;in the HFD group,compared with the WT group,the weight of the KO group increased（P<0.05）.3.Glucose tolerance test was performed on the HFD group mice.Compared with the WT group mice,the fasting blood glucose level of the KO group mice was significantly increased（P<0.05）,and the insulin tolerance test results showed that the KO group mice had a significant 15-minute blood glucose level Higher than the WT group mice,the two have significant differences（P<0.05）.4.In the HFD group of mice,compared with the WT group,the body fat rate（BFR）and body fat content（FAT）of the KO group increased significantly（P<0.05）.5.Under the obesity environment,the expression of Ddr2 m RNA in subcutaneous fat and visceral fat of WT mice did not change significantly（P>0.05）.6.In the HFD group,compared with the WT group,the expression of M1 type macrophage marker molecules（such as TNF-α,IL-6,IL-12）in the insulin-related target organs in the KO group Significant increase in skeletal muscle and visceral fat（P<0.05）.7.In the CHOW group of mice,compared with the WT group,the M1 type macrophage marker molecules（such as IL-1β,IL-12）in the skeletal tissue of insulin-related target organs in the KO group were significantly increased（P<0.05）.Conclusion:Our results reveal for the first time that knocking out the Ddr2 gene in macrophages in an obese environment can lead to impaired environmental glucose homeostasis and lipid metabolism disorders in the body,indicating that knocking out the Ddr2 gene can induce macrophages to differentiate into M1 type and inhibit their differentiation It is M2type,which induces an inflammatory response.The above results show that Ddr2 can be used as a potential therapeutic target for the prevention and treatment of metabolic-related diseases including obesity and diabetes.