The HMG ‐ CoA Reductase Inhibitor Fluvastatin Promotes Th2‐Skewed Immune Responses by Modulating Dendritic Cell Differentiation

ABSTRACT Statins, inhibitors of HMG‐CoA reductase, exert immunomodulatory effects beyond lipid lowering, yet how they regulate T helper (Th) cell differentiation remains poorly understood. We show that fluvastatin administration to C57BL/6 mice for 7 days suppressed interferon‐γ and elevated interleukin‐4 production by splenic CD4 + T cells, shifting the immune balance toward Th2 without altering splenocyte numbers or major immune cell subset proportions. This effect was not shared by rosuvastatin, suggesting that lipophilicity‐dependent cellular uptake influences immunomodulatory potency. In vitro experiments confirmed a direct Th2‐promoting action of fluvastatin on CD4 + T cells. Basophils were excluded as mediating cells, as fluvastatin suppressed rather than enhanced basophil interleukin‐4 production. Continuous fluvastatin exposure during granulocyte‐macrophage colony‐stimulating factor (GM‐CSF)‐driven dendritic cell (DC) differentiation altered the phenotype of the resulting DCs and markedly enhanced their Th2‐polarizing capacity in co‐cultures with antigen‐specific CD4 + T cells. These functional changes were accompanied by alterations in DC surface molecule expression, although their causal contribution remains to be established. These findings indicate that continuous fluvastatin exposure during DC differentiation is associated with an altered DC phenotype and enhanced Th2‐polarizing capacity.