We identified that mucin-degraders, short-chain fatty acid (SCFA) producers, and Programmed Cell Death Protein 1/Programmed Death-Ligand 1 (PD-1/PD-L1)-related biomarkers were associated with lower AD risk, while cardiovascular microbes, Amyloid-beta (Aβ)-related proteins, and lipoproteins were linked to higher risk. The gene discussed is CD274; the disease is Alzheimer disease.