Divergent effects of biolistic gene transfer in a mouse model of allergic airway inflammation

Particle-mediated epidermal delivery (PMED) of allergen genes efficiently prevents systemic sensitization and suppresses specific immunoglobulin E synthesis. We investigated in a mouse model of allergic airway disease the effect of PMED on the elicitation of local inflammatory reactions in the lung. BALB/c mice were biolistically transfected with plasmids encoding beta-galactosidase (betaGal) as model allergen under control of the DC-targeting fascin promoter and the ubiquitously active cytomegalovirus promoter, respectively. Mice were challenged intranasally with betaGal-protein with or without intermediate sensitization with betaGal adsorbed to aluminiumhydroxide. Subsequently, local cytokine production and recruitment of IFN-gamma-producing CD8(+) effector T cells into the airways were determined, and inflammatory parameters such as cellular infiltration in the bronchoalveolar lavage (BAL) and airway hyperresponsiveness (AHR) were measured. PMED of betaGal-encoding plasmids before sensitization significantly reduced frequencies of eosinophils in the BAL and shifted the local T helper (Th) cell response from a distinct Th2 response toward a Th1-biased response. However, AHR triggered by allergen challenge via the airways was not alleviated in vaccinated mice. Most important, we show that PMED using betaGal-encoding DNA without subsequent sensitization recruited Tc1 cells into the lung and caused a Th1-prone local immune response after subsequent intranasal provocation, accompanied by neutrophilic infiltration into the airways and elicitation of AHR. We conclude that robust Th1/Tc1 immune responses, although highly effective in the counter-regulation of local Th2-mediated pathology, might as well trigger local inflammatory reactions in the lung and provoke the induction of AHR in the mouse model of allergic airway disease.