The Mechanism Of Iron Metabilism Related Protein In Effecting Diabetic Kindney Disease And Iron Deficiency After Metabolic Surgery

The etiology of diabetes is complex,previous studies suggest that molecular markers can reflect metabolic states,therefore,exploring the relationship between molecular markers and metabolic states is critical to deepening understanding of the disease.Disease-related molecular markers can provide important evidence for prevention and early warning of diabetes development and progress,also provide the basis for molecular diagnosis and customized therapy.Studies showed that iron metabolism-related proteins can affect the function and metabolic status of the liver,kidneys,and gastrointestinal by regulating iron uptake,transport,and circulation.During the progression of diabetes,about 60–70% of patients will develop different types of complications,among which diabetic kidney disease(DKD)is a serious microvascular complication and the leading cause of renal failure.However,there are no available molecular markers directly related to DKD that can be used as early warnings.Therefore,searching for molecular markers related to the development of DKD not only facilitates the investigations of the etiology of DKD but also help in the early warning and prediction of diabetes complications.In terms of diabetes treatment,in addition to traditional medical treatments,metabolic/bariatric surgery(MBS)has shown remarkable effects on glucose control and weight loss,especially for those diabetes patients with morbid obesity,MBS is the optimal choice.While reducing weight and improving diabetes,MBS will also be accompanied by other metabolic changes,of which the incidence of iron deficiency is very high.However,we lack available molecular markers that can assess the states of systemic iron regulation after MBS,furthermore,changes in iron status before and after MBS and the related regulatory mechanism remains unclear.Therefore,this study focused on the whole process of diabetes development,progress,and treatment,aimed at finding the molecular markers that can be used to evaluate metabolic status,especially the correlation of iron metabolic-related proteins and DKD and MBS treatment,and revealing the related mechanism.This study was conducted from the following two aspects: first,in terms of diabetes complications,we investigate the potential relationship between serum haptoglobin level and DKD in type 2 diabetes mellitus(T2DM)patients in a Chinese Han population.We recruited a total of 233 T2 DM patients,including 118 subjects with DKD(case)and 115 subjects without DKD(control).The results showed that serum Hp levels were significantly higher(P = 0.0258)in the case group than the control.The serum Hp level was significantly positively associated with renal function indexes serum creatinine and albuminuria levels and was negatively associated with estimated glomerular filtration rate.Further multiple linear regression analysis revealed that serum Hp levels were significantly correlated with serum creatinine levels(P = 0.010)after adjusting for confounding factors.Our findings suggest that serum Hp levels may be used as a potential biomarker for the early diagnosis and of the monitoring the progress of DKD in T2 DM patients.Then,in terms of diabetes therapy,methods for treating diabetes based on Roux-en-Y gastric bypass(RYGB)or sleeve gastrectomy(SG)surgery were applied,aimed at investigating the expression changes of iron homeostasis regulatory hormone hepcidin and its related regulatory factors,and further reveal the related mechanism.Transcriptomics analysis showed that the m RNA expression of Hamp,the gene encoding hepcidin,decreased markedly after two operations;The enzyme linked immunosorbent assay showed that the expression of the protein hepcidin-25 was also significantly reduced after the two operations.The Hamp gene expression in the RYGB group changed the most with most significant,and the Hamp m RNA and protein expression in the SG group were both significantly higher than RYGB group.Further based on the DNA bisulfite conversion method,combined with Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry analysis to determine the DNA methylation level in the promoter region of the Hamp gene,the results showed that,the DNA methylation level of the Hamp promoter region was significantly higher in RYGB-operated rats than SHAM,while SG operated rats increased slightly in DNA methylation.Consistent with the change of hepcidin-25,serum iron was significantly lower for both bariatric groups than SHAM and particularly low in RYGB.The Liquid-Phase Chip System was used to detect the changes in the levels of inflammatory factors before and after surgery.The results showed that the levels of pro-inflammatory factors IL-6,MCP-1 and TNF-? in the serum after the two procedures were compared with those in the preoperative and SHAM-operation groups.No significant changes of inflammatory factors suggesting that postoperative serum level of inflammatory factor may have limited influence on the regulation of hepcidin expression.Our data demonstrate that rats underwent either RYGB or SG surgery showed different degrees of serum iron decrease;Elevated DNA methylation of the Hamp promoter region suppresses its expression,and this epigenetic modification likely occurs in reaction to the iron deficiency after bariatric surgery,helping to maintain system iron homeostasis.In summary,this study demonstrates the potential role of serum Hp levels as a molecular marker for early diagnosis and monitoring the progression of DKD.Also revealed the changes in hepcidin levels and its regulatory factors after MBS,and indicated the potential role of DNA methylation in affecting hepcidin synthesis and regulation of iron homeostasis after MBS,suggesting that the serum level of hepcidin at baseline and post-operation may be used as an important indicator for assessing iron status,providing a basis for nutritional supplement before and after surgery.