Staphylococcus aureus accelerates an experimental allergic conjunctivitis by Toll-like receptor 2-dependent manner

Allergic conjunctivitis is an inflammatory eye disease mediated by Th2-type cytokines and Staphylococcus aureus (S. aureus) colonization has been suggested as playing a role. This study used an experimental allergic conjunctivitis model to determine whether colonization by S. aureus affects the development of allergic conjunctivitis and modifies the immune response to OVA allergen. Mice challenged with OVA via conjunctival sac following systemic challenge with OVA in alum had severe allergic conjunctivitis. Of interest, inoculation of S. aureus markedly accelerated the signs of allergic conjunctivitis and was associated with higher levels of IgE Ab in serum. In addition, mice inoculated with S. aureus had more IL-4, IL-5, IL-13 and eotaxin secretion than non-inoculated group. In contrast, inoculation of TLR2−/− mice with S. aureus had no effect on severity of allergic conjunctivitis. The findings suggest that activation of TLR2 signal by S. aureus induces Th2-type immune responses and accelerates experimental allergic conjunctivitis.