Integrated Strategy for Discovery and Validation of Glycated Candidate Biomarkers for Hemodialysis Patients with Cardiovascular Complications

Comprehensive characterization of differential glycation in hepatocellular carcinoma using tissue proteomics with stable isotopic labeling

Glycation is a non-enzymatic posttranslational modification coming from the reaction between reducing sugars and free amino groups in proteins, where early glycation products (fructosyl-lysine, FL) and advanced glycation end products (AGEs) are formed. The occurrence of glycation and accumulation of AGEs have been closely associated with hepatocellular carcinoma (HCC). Here, we reported the characterization of differential glycation in HCC using tissue proteomics with stable isotopic labeling; early glycation-modified peptides were enriched with boronate affinity chromatography (BAC), and AGEs-modified peptides were fractionated with basic reversed-phase separation. By this integrated approach, 3717 and 1137 early and advanced glycated peptides corresponding to 4007 sites on 1484 proteins were identified with a false discovery rate (FDR) of no more than 1%. One hundred fifty-five sites were modified with both early and advanced end glycation products. Five early and 7 advanced glycated peptides were quantified to be differentially expressed in HCC tissues relative to paired adjacent tissues. Most (8 out of 10) of the proteins corresponding to the differential glycated peptides have previously been reported with dysregulation in HCC. The results together may deepen our knowledge of glycation as well as provide insights for therapeutics.

Discovery of age-related early-stage glycated proteins based on deep quantitative serum glycated proteome analysis

Aging is a pressing global health issue that is linked to various diseases, such as diabetes and Alzheimer's disease. It is well known that glycation plays a pathological role in the aging process and age-related diseases. Thus, it is of great significance to discover protein glycation at an early stage for monitoring and intervention in the aging process. However, the endogenous age-related early-stage glycated proteome remains insufficiently profiled. To address this research gap, our study focuses on assessing glycated proteomics profiles in the serum of mice. We employ a robust and quantitative strategy previously developed by our team, to analyze endogenous glycated proteome in serum samples of 4 age groups of mice (10 weeks, 16 weeks, 48 weeks and 80 weeks). In total, 2959 endogenous glycated peptides corresponding to 296 serum proteins are identified from 48 runs of serum samples from 16 mice across the four age groups. By comparing these glycated peptides between adjacent age groups, we discover 49 glycated peptides from 35 proteins that show significant upregulation between the 48-week and 80-week age groups. Furthermore, we identify 10 glycated proteins (or protein groups) that are significantly upregulated only between the 48-week and 80-week age groups, including lecithin-cholesterol acyltransferase (LCAT) and apolipoprotein A-II (Apo A-II). These novel findings provide unique signatures for understanding the aging process and age-related diseases. By shedding light on the early-stage glycated proteome, our study contributes valuable insights that may have implications for future interventions and therapeutic approaches.

Effects of High Flux Hemodialysis Combined with L-Carnitine on Microinflammation and Arteriovenous Fistula in Maintenance Hemodialysis Patients

Objective

To explore the effects of high-flux hemodialysis combined with L-carnitine on microinflammation and arteriovenous fistulas in maintenance hemodialysis patients.

Methods

A total of 65 patients admitted to our hospital from May 2017 to May 2019 were selected and divided into a control group of 30 cases and an experimental group of 35 cases according to the selected treatment plan. Combined with L-carnitine, the cardiac function of the two groups of patients before and after the treatment was evaluated, the microinflammatory indexes of the two groups were compared, and the clinical efficacy of the combined treatment on MHD patients was analyzed.

Results

The two groups were not significantly different in general information such as age, gender, course of disease, and past medical history (P > 0.05). The experimental group generated a notably higher total effective rate of treatment in relation to the control group (P < 0.05). After treatment, lower heart function levels of LVST and LEVDD were observed in the experimental group as compared to the control group, but LVEF was higher than that in the control group (P < 0.05). The GQOLI-74 score of the experimental group was better than that of the control group (P < 0.05). The incidence of venous fistula complications in the experimental group was significantly lower than that in the control group (P < 0.05). The microinflammatory index hs-CRP in the experimental group was lower (P < 0.05) and the microinflammatory index TNF-α was significantly lower (P < 0.05). The HAD score after treatment of the experimental group was better than that of the control group (P < 0.05).

Conclusion

High-flux hemodialysis combined with L-carnitine therapy has achieved satisfactory results in patients with MHD in terms of alleviating the level of inflammatory factors, improving heart function, enhancing patients' living standards, reducing complications of intravenous fistula, and boosting the prognosis. It is worthy of promotion.

Specific and Reversible Enrichment of Early-Stage Glycated Proteome Based on Thiazolidine Chemistry and Palladium-Mediated Cleavage

Comprehensive analysis of protein glycation is important for better understanding of its formation mechanism and biological significance. The current preconcentration methods of glycated proteome mainly depend on the reversible combination of boronic acid and cis-dihydroxy group by pH adjustment, but it has inherent limitations (e.g., poor specificity and time-consuming). Herein, for the first time, a novel enrichment method for glycated peptides is proposed based on the reversible chemical reaction between aldehyde and 1,2-aminothiol groups, in which oxidized glycated peptides are captured onto the magnetic nanoparticles via thiazolidine chemistry and then released by palladium-mediated cleavage. The method is rapid, with excellent selectivity (even at a 1:1000 molar ratio of glycated peptides/nonglycated peptides) and high sensitivity (1 fmol/μL). As a good evidence, 1549 glycated peptides were identified from glycated human serum with 94.6% specificity, providing a powerful technique for high-throughput analysis of glycated peptides.

Targeted liquid chromatography-tandem mass spectrometry analysis of proteins: Basic principles, applications, and perspectives

Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) is now the main analytical method for the identification and quantification of peptides and proteins in biological samples. In modern research, identification of biomarkers and their quantitative comparison between samples are becoming increasingly important for discovery, validation, and monitoring. Such data can be obtained following specific signals after fragmentation of peptides using multiple reaction monitoring (MRM) and parallel reaction monitoring (PRM) methods, with high specificity, accuracy, and reproducibility. In addition, these methods allow measurement of the amount of post-translationally modified forms and isoforms of proteins. This review article describes the basic principles of MRM assays, guidelines for sample preparation, recent advanced MRM-based strategies, applications and illustrative perspectives of MRM/PRM methods in clinical research and molecular biology.