| In order to evaluate the effects of obesity on immune regulation and local tissue defense state, and for the further study of obesity on immune function provide a theoretical basis, we detected the inflammatory reactions during intranasal instillation of different concentrations of Escherichia coli (E.coli) in obese mice induced by high-fat diet.(1) 30 24-to 25-days healthy Kunming male mice were randomly divided into group ND (10) fed with regular diet and group HD (20) fed with high fat diet for 8 weeks to detect the resistin, glucose and insulin concentrations in the serum and the number of WBC in the BALF and the morphological changes of lungs.The results showed that the body weight, epididymal fat weight, blood glucose, serum insulin, RETN in serum, Lee's index, WBC, GRA, LYM, MID counts in BALF of HD group were significantly higher than those of the ND group after feeding for 8 weeks.(2) 32 obese mice were randomly divided into group A(6), B(20) and C(6), and non-obese mice were randomly divided into group D(6), E(20) and F(6). Mice in group A, D were intranasally infected with 40?l of a bacterial suspension containing approximately 109 CFUs. And mice in group B, E were infected with 1010 CFUs of E.coli diluted in PBS, mice in group C, F were gave 40?L PBS via intranasal instillation as control groups. The lungs of six mice of each group were collected to detect the counting of E.coli and pathological morphology changes of lungs after 24 h. The results showed that mice in group A, B, D and E had typical symptoms of respiratory infection. Group A and D had no death, while the mortality rate of group B was 25%, and in group E was 10%. The number of E.coli of group A was significantly higher than that in group D, but there was no significant difference between group B and group E. The lungs of each experimental group occurred pathological morphology changes of congestion, hemorrhage, inflammatory cells infiltration in different degrees. The local damage of group A was more serious than group D, and group B was more serious than group E.(3) 180 obese Kunming mice were divided into Oh (6), group ? (42). ?(90), V (42). and 150 non-obese mice were divided into Oh (6), group ? (42), ? (90), ? (42). Mice in Oh. picked samples directly, and done nothing. And mice in group ?, ? were intranasally infected with 40?l of a bacterial suspension containing approximately 109 CFUs and mice in group ?, IV were infected with 1010 CFUs of E.coli diluted in PBS, mice in group V, VI were intranasally challenged with 40?l normal saline.2 h,6 h,12 h,24 h,48 h.72 h,96 h post-infection,6 mice in each group were selected to collect blood, BALF and lung tissues.The leukocytes in blood and BALF were detected by automatic blood cell counter. The cytokines concentrations in serum and lung tissue were measured with mouse ELISA kits And the pathological changes of lungs were stained with hematoxylin and eosin (M&F.). The results showed that:? After received with E.coli, the WBC in blood of group ? and ? increased first, then decreased, and was lowest at 24 h, and gradually increased later. While. in group ? and IV, WBC decreased slightly at 2 h following with gradually increased, then decreased fast, and was lowest at 48 h following a slight rebound. Serum TNF-a. IL-6, IL-10 and RETN concentrations increased rapidly after infection, and maintained high levels up to 48 h, then decreased gradually.?) During infection, TNF-?, IL-6. IL-10, RETN concentrations in serum rised quickly maintained to 48 h following with decreased gradually. Inner 24 h after infection, the cytokines we detected in group ? were higher than group ?, group ? were higher than group IV. At 96h post-infection, IL-10 and RETN concentrations of group ? were significantly lower than group ?, meanwhile IL-6. IL-10 concentrations of group ? were significantly higher than group ?. ? Inoculated with E.coli, WBC, GRA, LYM, MID in BALF increased rapidly, and reached the peak at 24 h following dropping sharply in all mice. And comparing the leukocytes among groups, group ? were higher than group ?, and group ? were higher than group ?. ? After E.coli infection, the concentrations of RETN, TNF-a, IL-6, IL-8, IL-10 and MIP-2, IL-12. MCP-1 in lung tissues decreased slightly first and increased gradually later, and reached a peak at 24 h or 48 h following decreased gradually. Inner 72h post infection, all the cytokines were higher in group ?than group ?. Untill 96 h, the concentrations of TNF-?. IL-10, IL-12 in group ? were significantly lower than group ?, while MIP-2 and IL-6 were significantly higher than those of group ?. Compared with group IV, concentrations of TNF-?, IL-6 and MIP-2, IL-8 and MCP-1 in group ? were significantly higher throughout the experimental period. ? After E.coli infection, the lungs of mice appeared different degree of congestion and hemorrhage, inflammatory infiltration, pathological changes and inflammatory damage mitigation subsequently with organizational structures were clear gradually. At 6 h and 24 h, group ? and ? had more inflammatory cell infiltration, and greater widened alveolar septum. While in 96h, the inflammatory infiltration was less and the structure was more clearly of group ? than group ?, meanwhile there were more inflammatory cells infiltration and more tissue damages of group ? than group ?.Conclusions:1. The model of obesity could be established successfully by feeding Kunming mice with high-fat diet for 8 weeks.2. The model of milder lung infection was established successfully via intranasal instillation of 40?L 1 ×10~8 CFU/?L E. coli. And the more severe infection was established by intranasal instillation of 40?L 1×10~9CFU/?L E.coli.3. Obesity improved the sensitivity of host to pathogens. It also had two-sided capacity to repair local organizations, on the one hand, it can reduce the damage and promote the dissipation of the local inflammation and repair of organizational structures in mice with milder infection, however it has an opposite effect on the mice with severe infection, and extended the time for recovery. |
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