The Relationship Between Complement C3 Complex And Complement C3 Enzymatic Glycosylation And Various Types Of Diabetes

Background:Diabetes and its complications are important global concerns.The current management and monitoring methods of diabetes mainly depend on blood glucose-related markers,such as HbAlc and glycated albumin(GA).However,patients with a similar level of blood glucose control still have different outcomes.Abnormal expression of complement C3 is one of the strongest inflammation markers of diabetes prevalence and complication.It is previously reported that complement C3 forms two diabetes-specific complexes in the serum of diabetes patients.However,it is still unknown how to monitor diabetes-specific complement activation in clinical practice.Objectives 1)To study the association of diabetes-specific C3 complexes with diabetes,and to evaluate its potential application;2)To establish a method of identifying complement C3 glycosylation types and to analyze their associations with diabetes-related markers.METHODS:This research included the samples from two case-control studies performed in PUMCH.1)Part 1 and Part 2:diabetes-specific C3 complexes,T1 and T2,in patients' serum were separated by Native-PAGE,and their relationships with diabetes-related markers were tested by linear regression and other statistical methods.We also used ROC curve analysis to evaluate the ability of these complexes to distinguish different types of diabetes from each other;mediation analysis was performed to test whether the complexes mediated the BMI-insulin resistance association;2)Part 3:The complement C3? was isolated by SDS-PAGE,and the glycopeptides of complement C3? were enriched with g-C3N4 and analyzed using the mass spectrum.Results 1)The blood glucose and inflammation markers of patients with type 1 diabetes mellitus(T1D)and type 2 diabetes mellitus(T2D)were significantly higher than those of MODY2 or healthy controls.There was no significant difference in the inflammatory state between MODY2 group and the control.After adjusted for age,gender,and BMI,the ratio of T2 complex(T2%)was significantly negatively correlated with insulin resistance and HbAlc(p<10-3),while the T2%-HbA1c association seems to depend on insulin sensitivity;2)ROC analysis suggested that T2%can significantly distinguish T2D from MOD Y2 or healthy people(p?0.001).Logistic regression,adjusted for age,gender,BMI and HbAlc,indicated that T2%could still distinguish T2D from MODY2 significantly;3)Mediation analysis showed that decreased T2%significantly mediated 35%of the relationship between BMI and insulin resistance(p=0.024),after adjustment for age and gender;4)The C3 glycosylation assay established in this experiment could relatively stably identify 11 major glycosylation types of C3;5)Glycosylation type G4,G10 and G11 of C3? were significantly associated with higher HbA1c and increased insulin resistance.Conclusion:We first discovered that the ratio of a complex mostly composed of complement C3 is a good predictor of insulin resistance in non-T1 D patients.This complex also played an important role in insulin resistance caused by elevated BMI.The C3 glycosylation assay described in this research is suitable for the determination of major glycosylation type of complement C3.Glycosylation types of C3 might play an important role in diabetes.