Mora, SamiaAmmar, Mohammed Ahmed2025-09-1820252025-05-012025Ammar, Mohammed Ahmed. 2025. Plasma N-Glycome as a Novel Biomarker for Cardiovascular Risk. Masters Thesis, Harvard Medical School.32000167https://dash.harvard.edu/handle/1/42719915First Project: Title: Plasma N-Glycome as a Novel Biomarker for Cardiovascular Risk: Secondary Analysis of the JUPITER and TNT Trials. Background: Glycosylation, a key post-translational enzymatic modification of proteins, plays a crucial role in biological pathways related to atherosclerosis. However, the relationship between plasma N-glycans and clinical cardiovascular disease (CVD) is underexplored. Methods: Using a discovery-validation study design, we measured baseline plasma N-glycans with ultra-high-performance liquid chromatography in two nested case-control studies within the JUPITER (NCT00239681; N=513 case-control pairs, discovery) and TNT (NCT00327691; N=436 case-control pairs, validation) trials. Incident CVD cases were matched 1:1 by age and sex in JUPITER and by statin randomization and disease risk score in TNT. Using conditional logistic regression, we examined associations between baseline plasma N-glycans and future CVD in JUPITER, adjusting for age, sex, race, LDL-C, HDL-C, hypertension, smoking, hs- CRP, BMI, aspirin use, and statin randomization. Significant associations were validated in TNT. We conducted a meta-analysis to combine effect estimates and performed sex- and age-adjusted Spearman correlations between plasma glycans and clinical biomarkers. Additionally, we derived a plasma glycan score in JUPITER via stepwise conditional regression. Results: In JUPITER, five plasma N-glycans were significantly associated with lower CVD risk after false discovery rate (FDR) adjustment: two core fucosylated-galactosylated (GP5,10), two tetragalactosylated-tetrasialylated (GP37,38), and one oligomannose (GP19) glycan. All were negatively associated with CVD. GP10 was replicated in TNT (FDR.05). Meta-analysis confirmed these findings, linking core fucosylation, galactosylation, and sialylation to lower CVD risk across multiple glycans (GP5,10,16, 21,37, and 38) and identifying a positive association between antennary fucosylation (GP27) and CVD in a model excluding inflammatory variables. Seven GPs comprised the plasma glycan score, which was associated with a nearly 2-fold increase in CVD risk per standard deviation (aHR:1.91, 95%CI: 1.59–2.30, P.001) in JUPITER after adjusting for traditional risk factors, with validation in TNT. In JUPITER, adding the glycan score improved the AUC from 0.73 (95%CI: 0.64–0.82) to 0.76 (95%CI: 0.67–0.84), P.001, with further replication in TNT (P=0.03). Conclusion: Specific baseline plasma N-glycan profiles are associated with future CVD. Core fucosylation, galactosylation, and sialylation show independent negative associations, while antennary fucosylation is positively associated to risk, potentially via inflammatory pathways. The glycan score improves model prediction performance, independent of cardiovascular risk factors. ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Second Project: Title: Immunoglobulin G N-Glycosylation as a Novel Biomarker for Premature Myocardial Infarction: a Case-Control Study. Background: Glycosylation, a key post-translational modification, plays a crucial role in biological pathways related to atherosclerosis. Purpose: To investigate whether immunoglobulin-G (IgG) N-glycosylation profiles are associated with premature myocardial infarction (MI) and to evaluate whether a glycan-based score improves case identification beyond traditional cardiovascular risk factors. Methods: We measured 27 IgG N-glycans using capillary gel electrophoresis in 377 cases with premature first MI (men≤55 years; women≤65 years) and 377 controls matched for age (±5 years), sex, and nationality from the Gulf PREVENT study, a case-control study investigating risk factors for premature MI in the United Arab Emirates. We performed conditional logistic regression to evaluate associations between IgG-N-glycans and premature MI, adjusting for age, body mass index, LDL-C, HDL-C, hs-CRP, hypertension, diabetes, and smoking. Using LASSO regression, we derived a novel IgG-glycan score as a linear combination of selected glycans associated with premature MI. We evaluated model performance using likelihood ratio tests and the area under the curve (AUC) adapted for the case-control design, using 10-fold cross-validation. Results: After adjusting for cardiovascular risk factors, glycan peaks (P) 4,13,23, and 27 were positively associated with premature MI (false discovery rate[FDR].05). Bisecting N- acetylglucosamine (GlcNAc) was the consistent glycosylation pattern among these four glycans. In contrast, P22, a core-fucosylated and monogalactosylated glycan, had inverse association (FDR=0.02) with premature MI. An IgG-glycan score, composed of Ps 2,4,8,17,20, and 24, was associated with twofold increase in premature MI risk per standard deviation increment (aOR,1.98 [95%CI,1.56–2.52];P.001) after adjusting for cardiovascular risk factors. Furthermore, the IgG- glycan score significantly improved model fit, as indicated by the likelihood ratio test (P.001), and enhanced model performance, increasing the AUC from 0.72(95%CI,0.64–0.79) to 0.75(95%CI,0.68– 0.81). Conclusion: We identified novel IgG N-glycosylation patterns that were associated with premature MI independent of cardiovascular risk factors. While core fucosylation, galactosylation, and sialylation were common to both positively and negatively associated glycans, the crucial distinction was that glycans linked to increased premature MI risk consistently contained bisecting GlcNAc, whereas those negatively associated lacked this modification. A novel IgG-glycan score was associated with premature MI risk independent of other risk factors and improved model performance.application/pdfenMedicineThesis or Dissertation2025-09-180000-0003-3710-2214