The Study On The Correlation Between Enterotypes With Whole Blood Trace Elements In Patients With Infertility

Objective:Infertility is a state of fertility disorder caused by multiple causes,and the disorder of trace elements is closely related to female infertility.Gut microbiota plays an important role in the absorption and metabolism of trace elements.The stable microbial community pattern of the gut microbiota is called the enterotypes and can be divided into Prevotella-enterotype and Bacteroides-enterotype according to the dominant genus.However,the relationship between enterotypes and whole blood trace elements in infertile women is still unclear.Therefore,this research is intended to investigate the correlation of the enterotypes and the whole blood microelements（copper,zinc,calcium,magnesium,iron）,in order to provide theoretical basis for treating female infertility from the point of view of nutritional metabolism.Methods:1.A total of 651 Han Chinese subjects aged 20-40 years（469 infertile patients and 182 normal controls）were recruited from the Center of Reproductive Medicine,Shengjing Hospital of China Medical University from 2020 to 2022.General information of the subjects was collected,and a dietary questionnaire was completed to detect intestinal microecology.Fasting venous blood and stool samples were obtained.2.The contents of copper,zinc,calcium,magnesium and iron in whole blood were determined by flame atomic absorption spectrometry;Quantitative real-time polymerase chain reaction（q PCR）was used to measure the number of Prevotella and Bacteroides in the feces of the subjects;Gas chromatography-mass spectrometry was used to measure the content of short chain fatty acids（SCFAs）in feces.3.According to the ratio of Prevotella to Bacteroides（P/B）in the stool,the subjects were divided into Prevotella-enterotype（P-enterotype）group and Bacteroides-enterotype（B-enterotype）group;According to the 5^th percentile（P5）and 95^thpercentile（P95）of whole blood trace element levels,the subjects were divided into low level（LL）group（<P5）,normal level（NL）group（P5-P95）and high level（HL）group（>P95）;Based on body mass index（BMI）,the study population was classified as normal weight group（BMI<24 kg/m²）,overweight group（BMI:24-28 kg/m²）,and obese group（BMI>28 kg/m²）.4.Categorical variables were compared using the chi-square test and Fisher’s exact test,and continuous variables were compared using Student’s t test and Kruskal-Wallis test;The correlation of P/B and trace elements in whole blood was tested by Pearson correlation coefficient,and the predictive effect of P/B on LL and HL was analyzed by the receiver operating characteristic curve（ROC）.Results:（1）Of all the subjects studied,Log（P/B）was negatively associated with whole blood copper（r=-0.087,P=0.026）,zinc（r=-0.109,P=0.005）,magnesium（r=-0.173,P<0.001）,iron（r=-0.185,P<0.001）.（2）Among the infertile women,the levels of copper（P=0.033）,zinc（P<0.001）,magnesium（P<0.001）and iron（P<0.001）in the P-enterotype patients were significantly lower than those in the B-enterotype patients;There was a significant negative linear correlation between Log（P/B）and whole blood copper（r=-0.105,P=0.024）,zinc（r=-0.181,P<0.001）,magnesium（r=-0.280,P<0.001）,iron（r=-0.314,P<0.001）;There was only significant difference in whole blood iron among LL,NL and HL groups,but no significant difference in copper,zinc,calcium and magnesium among the three groups.（3）There was no significant difference in trace element levels between the two enterotypes in normal controls.There was no significant correlation between Log（P/B）and blood trace element levels.The microelements in whole blood of LL,NL,HL were not significantly different of the two enterotypes.（4）There were differences in BMI among different iron levels in infertile people,so infertile people were divided into three groups according to BMI.In the obese infertility population,Log（P/B）had predictive power for whole blood iron LL.When the cutoff value of Log（P/B）was-0.27,the area under the ROC curve（AUC）was 0.894,the sensitivity was 98.8%,and the specificity was 78.8%（P=0.042）.In the normal weight infertile population,Log（P/B）had predictive power for HL of whole blood iron,and the AUC of Log（P/B）at the cutoff value of-2.76 was 0.648,the sensitivity was 55.7%,and the specificity was 82.4%（P=0.041）.In the overweight infertility population,Log（P/B）had predictive power for whole blood iron HL.When the cutoff value of Log（P/B）was-3.99,the AUC was 0.863,the sensitivity was 78.1%,and the specificity was 92.7%（P=0.013）.Conclusion:The levels of whole blood copper,zinc,magnesium and iron in P-enterotype infertile women were significantly lower than those in B-enterotype.There was a significant negative linear correlation between Log（P/B）and the levels of whole blood copper,zinc,magnesium and iron.Log（P/B）had a certain predictive power for whole blood iron LL in obese infertile women.