Regulation of airway eosinophil and neutrophil infiltration by α-galactosylceramide in a mouse model for respiratory syncytial virus (RSV) vaccine-augmented disease

Respiratory syncytial virus (RSV) is a leading cause of respiratory disease among infants, the elderly and immunocompromised adults. In this study, we assessed the effects of α-galactosylceramide, a known immunoregulatory lipid, on liposomal RSV vaccine-induced responses in BALB/c mice subsequently challenged with RSV. Liposomes containing a recombinant fragment of the RSV G protein were prepared with and without α-galactosylceramide and used to immunize mice by the intranasal route. The inclusion of α-galactosylceramide in the liposomal formulation caused a dramatic reduction in bronchoalveolar lavage neutrophils, but also an increase in eosinophils, following subsequent RSV challenge. The reduction in neutrophils was specific to mice receiving α-galactosylceramide-containing liposomes and was not reproduced in mice administered liposomes containing another α-galactosyl lipid, α-galactosylphosphatidylglyceroylalkylamine. Lung IL-13 mRNA levels were particularly elevated in mice administered α-galactosylceramide-containing liposomes followed by RSV challenge. This study demonstrates a striking ability of α-galactosylceramide to modulate the cellular airway infiltrate in mice immunized with liposomal RSV vaccine followed by RSV challenge.