The Role Of CD4~+T In Intrauterine Overnutrition-induced Offspring Susceptibility To Asthma

Part I High fat diet-induced intrauterine overnutrition leads to susceptibility to asthma in the adult offspringObjective:The present study was designed to investigate the effect of high fat diet during pregnancy on susceptibility to asthma in the adult offspring.Materials and methods:C57BL/6 dams were fed a high fat diet(60%fat Calories,HFD)or normal chow diet(10%fat Calories,NCD)during pregnancy.Pups were fed NCD since birth(HFD-F1 refers to offspring of mice fed high fat diet during pregnancy,NCD-F1 refers to offspring of mice fed normal chow diet during pregnancy).Body weight of offspring was monitored on different ages.Asthma was induced by ovalbumin(OVA).The number of total infiltrated immune cells and eosinophils in bronchoalveolar lavage fluid(BALF)and lung,hematoxylin(HE)and eosin periodic acid shiff(PAS)of lung sections was subsequently analyzed to determine the severity of asthma.Results:Fetal weights at E18.5 in HFD-F1 were significantly higher compared to NCD-F1.Adult HFD-F1 were found to be overweight since the age of 6 weeks for male and 10 weeks for female.High fat diet during pregnancy exacerbated allergic airway disease induced by OVA in adult offspring,including increased inflammatory cell infiltration and airway mucus secretion.Moreover,HFD-F1 exhibited increased lung and BALF total immune cells(p<0.01)and eosinophils(p<0.05).Notably,HFD-F1exhibited increased T cell numbers both in BALF(p<0.01)and lung(p<0.01).Conclusions:A high-fat diet during pregnancy can result in intrauterine excessive growth and long-term obesity in offspring.A high-fat diet during pregnancy might exacerbate the susceptibility to asthma in adult offspring through mechanisms involving T cells.Part II The role of CD4~+T in adult asthma susceptibility exacerbated by maternal high fat diet during pregnancyObjective:The present study was designed to investigate the role of CD4~+T cells in HFD-F1 induced asthma susceptibility in offspring.Materials and methods:C57BL/6 dams were fed a HFD(60%fat Calories,HFD)or normal-fat diet(10%fat Calories,NCD)during pregnancy.Offspring were stimulated by OVA to induce asthma.Numbers of CD4~+T and CD8~+T in BALF,lung and tracheobronchial lymph node(t LN)were detected by FACS.Protein and m RNA levels of type 2cytokines were assessed by means of real-time quantitative PCR and Elisa respectively.Splenic CD4~+T cells were magnetic sorted and stimulated by?-CD3/?-CD28 or by phorbol myristate acetate(PMA)+ionomycin(ION)in vitro to analyze effects of pregnancy high fat diet on CD4~+T proliferation and Th2 profile.Then mice were challenged by OVA in vivo,Ki67~+CD4~+T cells from t LN and Th2 profiles of pulmonary immune cells and t LN cells from the offspring were analyzed.Results:Increased numbers of CD4~+T cells were observed in BALF(p<0.05),lung(p<0.01)and t LN(p<0.05)from HFD-F1 after OVA challenge,while the numbers of CD8~+T showed no significant difference between two groups.OVA-induced allergic airway inflammation in HFD-F1 increased the m RNA level of lung Il4(p<0.05),Il13(p<0.05)and protein level of BALF IL4(p<0.05),IL13(p<0.05),while the m RNA and protein level of IFN?remained unchanged.We further analyze the proliferation ability of CD4~+T cells and the relation between CD4~+T cells and type 2 cytokines.We found that splenic CD4~+T cells from HFD-F1showed enhanced proliferation as well as increased relative m RNA expression of Il4(p<0.05),Il5(p<0.05)and Il13(p<0.05).Moreover,when challenged by OVA in vivo,increased numbers and percentage of Ki67~+CD4~+T cell were found in CD4~+T cells in t LN from HFD-F1 mice.At the same time,lung and t LN CD4~+T cells from HFD-F1 showed increased intracellular expression of IL4(p<0.05)and IL13(p<0.05)but not IFN?(p>0.05)compared to NCD-F1.Conclusions:A high-fat diet during pregnancy can result in enhanced CD4~+T cell proliferation,and increased IL4 and IL13 secretion in adult offspring,which plays an important role in their asthma susceptibility.Part III The effect of intrauterine overnutrition on the CD4~+T cell immune response in human offspringObjective:The present study was designed to investigate the effect of intrauterine overnutrition on the CD4~+T cell immune response in offspring.Materials and methods:Samples of umbilical cord blood were collected from large for gestational age infants(LGA,n=13)and normal for gestational age infants(NGA,n=24).Clinical data were collected by clinical investigation.CD4~+T cells were obtained by magnetic sorting.Purified CD4~+T cells were stimulated by PMA+ION for 3h.The expression of cytokine Il4,Il5,Il13 and Ifng m RNA was detected by Real-Time PCR.Results:Compared with NGA,maternal data from LGA showed significantly higher pregnancy weight gain(p<0.05)and prenatal BMI(p<0.05).Notably,non-sensitized CD4~+T cells from LGA already exhibited increased relative m RNA expression of Il4(p<0.05)and Il13(p<0.05),the expression of Il4(p<0.05),Il5(p<0.01)and Il13(p<0.05)further increased in PMA+ION challenged CD4~+T cells compared with those in NGA.However,there was no difference between two groups in the relative m RNA expression of Ifng no matter challenged or not.Conclusions:Intrauterine overnutrition resulted in exacerbated expression of type 2 cytokines in CD4+T cells from human cord blood.