Simvastatin reduced infiltration of memory subsets of T lymphocytes in the lung tissue during Th2 allergic inflammation

Abstract

Lymphocytes infiltration is a key mechanism that drives asthma lung inflammation. Our previous results demonstrated a significant increase in the frequency and persistence of central memory T (TCM) cells in inflamed lung tissue. This could be due to an increase in the infiltration of TCM in the lung tissue, or the possible differentiation of lung effector memory T (TEM) cells into TCM during lung inflammation. Thus, targeting the accumulation of memory T cells provides a potential approach for asthma treatment. Simvastatin and other statins were shown to impact both the structural and immune lung cells, presenting a distinct immunomodulatory effect on T lymphocyte activation, infiltration, and function. Therefore, we sought to evaluate the effect of simvastatin on the frequency and function of CD4 and CD8 TEM and TCM cells in an ovalbumin (OVA)-induced mouse model of asthma. Simvastatin treatment significantly attenuated the infiltration of both TEM and TCM memory subtypes, along with their production of IL-4 and IL-13 cytokines in a T helper 2 (Th2) OVA-sensitized mouse model. Furthermore, we detected a reduction in ICAM-1 and VCAM-1 levels in the lung homogenate of OVA-sensitized and challenged mice, as well as in human umbilical vein endothelial cells (HUVECs) following treatment with simvastatin. The reduction in leucocyte homing receptors following simvastatin treatment might have contributed to the observed decrease in infiltrated memory T cell numbers. In conclusion, this study demonstrated how statin drug may attenuate allergic asthma lung inflammation by targeting memory T cells and reducing their numbers, whilst limiting their cytokine production at the site of inflammation. Longer clinical trials are required to assess the effectiveness and safety of statin treatment in different asthma phenotypes.