NAMPT (nicotinamide phosphoribosyltransferase) serves as the rate-limiting enzyme in mammalian NAD+ biosynthesis, catalyzing the conversion of nicotinamide to nicotinamide mononucleotide 12. The enzyme exists in two forms: intracellular NAMPT maintains cellular NAD+ pools essential for redox metabolism, while extracellular NAMPT (eNAMPT) functions as a cytokine with immunomodulatory and adipokine properties 2. NAMPT regulates diverse cellular processes through NAD+-dependent mechanisms, including energy metabolism, DNA repair via PARP proteins, and deacetylation by sirtuins 1. The enzyme plays crucial roles in immune regulation by driving interferon-γ-induced PD-L1 expression through NAD+-dependent epigenetic mechanisms involving Tet1 demethylase 3. In aging, NAMPT governs the senescence-associated secretory phenotype (SASP) by enhancing glycolysis and mitochondrial respiration through NAD+-mediated AMPK suppression 4. Circulating eNAMPT levels decline with age and are transported via extracellular vesicles, with supplementation extending lifespan in aged mice 5. Clinically, NAMPT is implicated in metabolic disorders including obesity, diabetes, and NAFLD, while also being overexpressed in various cancers 2. Recent studies identify eNAMPT as a damage-associated molecular pattern (DAMP) protein contributing to pulmonary fibrosis pathogenesis 6.