Combination Blockade of OX40L and CD30L Inhibits Allergen-driven Memory Th2 Reactivity and Lung Inflammation.

Abstract Background The selective reduction of memory Th2 responses could be key to affording tolerance and protection from the reoccurrence of damaging allergic pathology. Objective We asked whether TNF family costimulatory molecules co-operated to promote accumulation and reactivity of effector memory CD4 T cells to inhaled complex allergen, and if their neutralization could promote airway tolerance to subsequent re-exposure to allergen. Methods Mice were sensitized intraperitoneally or intranasally with house dust mite (HDM), and challenged with intranasal allergen after memory had developed. We assessed whether single or combined blockade of OX40L/CD252 and CD30L/CD153 inhibited memory T cells from driving acute asthmatic lung inflammation, and protected mice upon exposure to allergen at a later time. Results OX40- or CD30-deficient animals showed strong or partial protection against allergic airway inflammation, however neutralizing either molecule alone during the secondary response to allergen had little effect on the frequency of effector memory CD4 T cells formed and acute lung inflammation. In contrast, a significant reduction in eosinophilic inflammation was observed when OX40L and CD30L were simultaneously neutralized, with dual blockade inhibiting effector memory Th2 expansion in the lungs while formation of peripherally-induced Treg remained intact. Moreover, dual blockade during the secondary response resulted in a tolerogenic state such that mice did not develop a normal tertiary memory Th2 cell and lung inflammatory response when challenged weeks later with allergen. Conclusion Memory T cell responses to complex allergens are controlled by several TNF costimulatory interactions, and their combination targeting might represent a strategy to reduce the severity of inflammatory reactions upon re-exposure to allergen.