Cytokines may be protective for Staphylococcus in a mouse keratitis model

Abstract

Abstract: : Purpose: Staphylococcus is the leading cause of the potentially blinding disease microbial keratitis. Despite the use of antibiotics, the host inflammatory response continues to cause damage to the cornea, which may lead to blindness. Manipulation of the host response may be a useful tool to help improve patient outcome from this devastating disease. We aim to understand the contribution of the host response to S. aureus infection. Methods:A S. aureus keratitis mouse model was developed in both C57BL/6 and BALB/c mice using two different strains of S. aureus (8325–4 and Staph 38). Twenty–four hours post–infection, mice were sacrificed and eyes harvested for enumeration of bacteria, polymorphonuclear leukocytes, chemokines and cytokines. Results:The laboratory strain 8325–4 was not as infective as the clinical isolate Staph 38. Additionally, BALB/c mice were susceptible to S. aureus infection whereas C57BL/6 mice were resistant. The resistant C57BL6 mice polarized towards a Th2 response, which may be protective for these mice. IL–4 and IL–10 were elevated significantly in C57BL/6 mice (41 ± 6 pg/eye and 169 ± 17 pg/eye; p < 0.05). The susceptible BALB/c mice did not evoke a cytokine response, which suggests that S. aureus are walling off during infection and may be evading host defences. Conclusions:IL–4 and IL–10 cytokines are protective for S. aureus keratitis and may be useful for adjunct or stand–alone therapies in the treatment of this disease.

Keywords: Staphylococcus • keratitis • cytokines/chemokines