Mechanistic Study of NT5E in Reg3β-Induced Macrophage Polarization and Cooperation with Plasma Proteins in Myocarditis Injury and Repair.

We aimed to explore the mechanism by which extracellular-5'-nucleotidase (NT5E) regulates macrophage polarization via regenerating islet-derived protein 3 beta (Reg3β) and other plasma proteins that mediate immune-cell effects on myocarditis. Methods: The involvement of NT5E in Reg3β-induced macrophage polarization was first analyzed using RNA sequencing, Western blotting, and quantitative polymerase chain reaction. Mendelian randomization was employed to identify NT5E and various plasma proteins as potential therapeutic targets for myocarditis. Mediation analysis, enrichment analysis, protein-protein interaction network analysis, drug prediction, molecular docking, and single-cell RNA sequencing were integrated to further evaluate the biological functions and pharmacological potential of the identified targets. Finally, phenome-wide association studies were conducted to assess the safety of targeting these proteins. NT5E expression was elevated in Reg3β-stimulated M2 macrophages. The expression of Arg-1, a marker of M2 macrophages, decreased upon NT5E knockdown, suggesting that NT5E is involved in the Reg3β-mediated polarization of macrophages to the M2 phenotype. Mendelian randomization analysis identified NT5E and 80 other plasma proteins as being causally associated with myocarditis. Mediation analysis revealed 12 immune-cell types were mediators of the effects of plasma protein on myocarditis progression. Drug prediction identified candidates such as ICN 1229 and chrysin, which showed strong binding affinities in molecular docking analyses. These findings may contribute to the development of effective treatments for myocarditis. : NT5E plays a dual role in Reg3β-induced macrophage polarization and in interacting with plasma proteins that influence the onset and progression of myocarditis through immune-cell pathways.