Vanin-2 is expressed in peripheral blood T cells and upregulated in patients with systemic lupus erythematosus.

Members of the vanin gene family include VNN1, VNN2, and VNN3 in humans. Although the functions of vanins have been widely examined in myeloid cells, their expression and functions have not been clarified in T lymphocytes. This study aimed to elucidate the significance of Vanin-2 (VNN2) on human peripheral blood T lymphocytes and study its expression in systemic lupus erythematosus (SLE). The differential expression of Vanins was analyzed by bioinformatics. VNN2 expressions in peripheral blood T-cell subsets were analyzed by single-cell RNA sequencing data and flow cytometry. Changes of VNN2 expression before and after T-cell activation were further clarified by western blot. The function of VNN2+ cells was studied by granzyme B (GZMB) and perforin detection. Changes in VNN2+ proportions in T-cell subsets of patients with SLE were further analyzed. In the present study, only VNN2 among vanins showed distinguishable expression in T cells. VNN2+ percentages were higher in CD8+ T cells those in CD4+ T cells. VNN2+ T cells were with a higher memory T-cell composition. VNN2 expression was significantly increased after T-cell stimulation. VNN2+ T cells had higher levels of GZMB and perforin secretion than VNN2- T cells. Clinically, VNN2+ percentages in T cells of patients with SLE were upregulated. Together, these data suggested that VNN2 is expressed in peripheral blood T cells characterized more GZMB and perforin secretion, and increased VNN2+ T cells in patients with SLE could reflect altered T-cell functions in vivo.