Aim:
This study primarily seeks to assess changes in proteome profiles and glycosylation status following COVID-19 vaccination in people with HIV (PWH) and to identify immune-related biomarkers that may indicate vaccine non-responsiveness.
Methods:
Among participants, PWH vaccinated (n=70) and control group (healthy) (n=40). Participants were sub categorized as immune responders (IR) or non-responders (INR) based on SARS-CoV-2 spike protein IgG ELISA results. Plasma samples underwent depletion of 7-most abundant proteins using MARS affinity cartridges. Depleted samples were digested using in-solution protocol and processed for proteomics analysis via mass spectrometry. Protein identification is done using Proteome Discoverer 2.5 against dataset of Homo sapiens and we used enzymatic deglycosylation of N-glycans with PNGase F and mass difference at Asp-Asn substitute (-0.98 Da) was identified. Further proteomic results were validated using western-blot.
Results:
Proteomic analysis identified 261 differentially expressed proteins (DEPs) in PWH and 302 DEPs in the control group with Log2-fold change (FC) ≥ ±1.0, p-value <0.05. KEGG pathway enrichment analysis of DEPs revealed downregulation in T-cell activation and immune response (HLA-A, FCGR3A, FCGR3B, C4B, CFHR1) by more than 1-fold. we also observed the presence of Vitamin D binding protein (GC) in the INR, while it was not present in IR groups. Further, we identified 221 glycosylated proteins from that GC and Serum amyloid A-1 protein identified only in INR with p-value <0.05, and express only in INR for the first two dose intervals. Western blot analysis confirmed the GC in the INR.
Conclusions:
Presence of GC in INR highlights its potential role in vaccine non-responsiveness in PWH. Vitamin D is known to play an immunomodulatory role by inhibiting IFN-γ-producing Th1 cells, thereby regulating immune responses. Our findings suggest that excess GC may limit availability of active vitamin D to immune cells, contributing to altered immune function and reduced vaccine efficacy.