Objective:To study the role of cadherin 1 (CDH1) gene DNA methylation in autoimmune thyroiditis (AIT) in population from different water-iodine regions.Methods:From May to June 2019, the information of AIT cases and healthy individuals in Shandong Province were collected in three types of water-iodine regions: iodine-fortification (IF) region, iodine-adequate (IA) region and iodine-excess (IE) region. A case-control study design was applied to match 176 AIT cases (case group) with age, gender, body mass index, and place of residence in a 1 ∶ 1 ratio to 176 healthy individuals (control group). Fasting urine and whole blood samples were collected to test the contents of urinary iodine, thyroid function indicators [serum free triiodothyronine (FT 3), free thyroxine (FT 4), thyroid stimulating hormone (TSH)], and serum iodine. The DNA methylation levels of the target region of the CDH1 gene and its four CpG sites in whole blood were determined using methylation sequencing technology for target regions (MethylTarget TM). Results:The DNA methylation level of the target region of CDH1 gene in the case group was 0.832 ± 0.044, and that in the control group was 0.828 ± 0.049, there was no statistically significant difference between the two groups ( t = 0.76, P = 0.448). There was no statistically significant difference in DNA methylation levels of the four CpG sites in the target region of CDH1 gene between the case group and the control group ( P > 0.05). There was no statistically significant difference in the DNA methylation level of the CDH1 gene target region between the case group and the control group in IF, IA and IE regions ( P > 0.05). The detection results of DNA methylation levels at CpG sites in the target region of CDH1 gene in different water iodine regions showed that the DNA methylation level at site 83 in case group in IF region was higher than that in the control group ( t = 2.30, P = 0.023). However, there was no statistically significant difference in the DNA methylation levels of the four CpG sites between the case group and the control group in IA and IE regions ( P > 0.05). The DNA methylation level of CDH1 gene target region in AIT patients was not significantly correlated with urinary iodine, serum iodine, and serum FT 3, FT 4, and TSH contents ( P > 0.05), but was significantly negatively correlated with age ( r =-0.19, P = 0.014). Conclusions:The DNA methylation level at CpG site 83 of CDH1 gene in AIT patients in IF region is significantly higher than that in control population, indicating that DNA methylation at this locus may be involved in the occurrence and development of AIT after iodine fortification. The DNA methylation level of CDH1 gene is negatively correlated with age.

Objective:To study the role of cadherin 1 (CDH1) gene DNA methylation in autoimmune thyroiditis (AIT) in population from different water-iodine regions.Methods:From May to June 2019, the information of AIT cases and healthy individuals in Shandong Province were collected in three types of water-iodine regions: iodine-fortification (IF) region, iodine-adequate (IA) region and iodine-excess (IE) region. A case-control study design was applied to match 176 AIT cases (case group) with age, gender, body mass index, and place of residence in a 1 ∶ 1 ratio to 176 healthy individuals (control group). Fasting urine and whole blood samples were collected to test the contents of urinary iodine, thyroid function indicators [serum free triiodothyronine (FT 3), free thyroxine (FT 4), thyroid stimulating hormone (TSH)], and serum iodine. The DNA methylation levels of the target region of the CDH1 gene and its four CpG sites in whole blood were determined using methylation sequencing technology for target regions (MethylTarget TM). Results:The DNA methylation level of the target region of CDH1 gene in the case group was 0.832 ± 0.044, and that in the control group was 0.828 ± 0.049, there was no statistically significant difference between the two groups ( t = 0.76, P = 0.448). There was no statistically significant difference in DNA methylation levels of the four CpG sites in the target region of CDH1 gene between the case group and the control group ( P > 0.05). There was no statistically significant difference in the DNA methylation level of the CDH1 gene target region between the case group and the control group in IF, IA and IE regions ( P > 0.05). The detection results of DNA methylation levels at CpG sites in the target region of CDH1 gene in different water iodine regions showed that the DNA methylation level at site 83 in case group in IF region was higher than that in the control group ( t = 2.30, P = 0.023). However, there was no statistically significant difference in the DNA methylation levels of the four CpG sites between the case group and the control group in IA and IE regions ( P > 0.05). The DNA methylation level of CDH1 gene target region in AIT patients was not significantly correlated with urinary iodine, serum iodine, and serum FT 3, FT 4, and TSH contents ( P > 0.05), but was significantly negatively correlated with age ( r =-0.19, P = 0.014). Conclusions:The DNA methylation level at CpG site 83 of CDH1 gene in AIT patients in IF region is significantly higher than that in control population, indicating that DNA methylation at this locus may be involved in the occurrence and development of AIT after iodine fortification. The DNA methylation level of CDH1 gene is negatively correlated with age.

Objective To observe prolactin (PRL) and estradiol (E2) levels in lactating women in different iodine nutrition areas.Methods According to the recent national water-borne high iodine area survey and the monitoring results of iodine deficiency disorders,the following places were selected,including Nankang,Xinggang and Yingpan towns of Beihai City,Guangxi (water iodine ≤ 10 μg/L,low iodine areas),Yangcheng Township and Jiajiazhuang Township of Fenyang City,Shanxi (water iodine 50-100 μg/L,adaptive iodine areas),Pingyao County and Jicun Town of Fenyang City,Shanxi (water iodine ≥300 μg/L,high iodine areas),and urinary and blood samples were collected in lactating women (n =100,97,123) from the three regions.The urinary iodine concentration was tested by arsenic cerium catalytic spectrophotometry.Serum levels of PRL and E2 were determined by chemiluminescence immunoassay.Results The urinary iodine medians of lactating women were 51.42,283.62,842.31 μg/L,respectively,in the three regions,the difference between the regions was statistically significant (x2 =241.09,P ＜ 0.05);the iodine levels of lactating women in low iodine areas,adaptive iodine areas and high iodine areas were in the state of iodine deficiency (＜ 100 μg/L),sufficient or adequate (200-299 μg/L) and iodine excess status (≥ 300 μg/L),respectively.Serum PRL and E2 levels of lactating women in the three types of areas were 38.81,20.98,16.41 μg/L and 29.57,43.70,45.51 ng/L,respectively.The differences between the regions were statistically significant (x2 =41.54,24.03,P ＜ 0.05).Conclusion With the increase of iodine nutrition level,PRL in lactating women has presented a gradually decreasing trend,E2 is increased.

Objective To observe the changes of sodium iodide symporter (NIS) in mammary gland of rats at different lactation periods,and to explore iodine uptake mechanism.Methods Seventy-five adult Wistar rats were selected,including 60 females,15 males,weighting 220-250 g.All female Wistar rats were divided into 4 groups according to their body mass via random number table method:normal non-pregnant group,lactating for 7-,14-and 21-day groups,15 rats in each group.All rats were fed with adequate conventional fodder and tap water.In addition to normal non-pregnant group,other three groups of female and male rats were mated at 3 ∶ 1,respectively,then after lactating for 7th,14th and 21th days,mammary gland tissues were harvested.The expressions of NIS mRNA and protein were measured with real time quantitative PCR (qRT-PCR) and immunohistochemical staining,respectively.Results NIS protein was expressed in the small ductal epithelium of mammary gland and the basal lateral membrane under light microscope,obvious brown particles visible.The expression of NIS mRNA (0.79 ± 0.11,1.05 ± 0.21,0.98 ± 0.18,0.89 ± 0.16) in mammary gland showed significant differences between groups (F =5.965,P ＜ 0.05),the expressions of NIS mRNA in 7th and 14th day groups were higher than that of normal non-pregnant group (P ＜ 0.05).The expression of NIS protein in mammary gland showed significant differences between groups (H =32.747,P ＜ 0.05),the staining intensity of mammary gland tissue after lactating for 7th,14th and 21th days groups was stronger than that of normal non-pregnant rats (P ＜ 0.05).Conclusions NIS is expressed in mammary gland of rats at different lactation periods.The iodine uptake of mammary gland is enhanced in early lactation period.

Objective To observe the expressions of thyroid-stimulating hormone receptor (TSHR) protein and mRNA in thyroid gland of lactating rats.Methods Eighty adult Wistar rats (60 females and 20 males),weighting 210-250 g were selected.The 60 female Wistar rats were divided into 6 groups according to their body weight by means of random number table:normal non-pregnant group,lactating for 5,10,15 and 20 days groups and weaning for 5 days group,10 rats in each group.All rats were fed with conventional fodder and tap water freely,and the rats of lactating groups except the normal non-pregnant group cohabited with male rats (3 ∶ 1).Then all rats were killed on the 5th,10th,15th and 20th day after lactation and on the 5th day after weaning to get thyroid tissues.The expressions of TSHR protein and mRNA were determined by immunohistochemical staining and realtime quantitative PCR.Results TSHR protein was expressed in cytoplasm and membrane of rat thyroid follicular cells.The expression of TSHR protein in thyroid gland was significant different statistically between groups (x2 =11.227,P ＜ 0.05); the staining intensity of rat thyroid tissues in the normal non-pregnant gruop (weak,n =2; moderate,n =5; strong,n =3) was stronger than that of rats lactating for 5 days (weak,n =7; moderate,n =3; x2 =5.895,P ＜ 0.05).But the expression of TSHR protein in thyroid tissues in the normal non-pregnant group was not significantly different statistically compared with the expression of TSHR protein in other groups (lactating for 10,15and 20 days) and weaning for 5 days group (all P ＞ 0.05).The expression of TSHR mRNA in thyroid gland was significantly different statistically between groups (F =2.970,P ＜ 0.05); the expression of TSHR mRNA in lactating for 5 days group (0.74 ± 0.13) was lower than that of the non-pregnant group (1.02 ± 0.24,P ＜ 0.05); and the expression of TSHR mRNA in the normal non-pregnant group was not significantly different statistically compared with those of other groups (lactating for 10,15 and 20 days) and weaning for 5 days group (all P ＞ 0.05).Conclusion TSHR is widely expressed in thyroid gland of lactating rats,but relatively lower in early lactation period.