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Introduction: The prevalence and diversity of methicillin-resistant Staphylococcus aureus (MRSA) virulent factors as well as the host inflammatory response makes managing MRSA keratitis challenging. Alternative treatments are being investigated that can both neutralize the MRSA toxins while also reducing the host immune response. One such alternative is Photodynamic Antimicrobial Therapy (PDAT); however, limited research has been performed to understand the impact of PDAT on the host immune response during MRSA-related infections.
Purpose: To measure the immune response (Interleukin(IL)-1, 6 and 8) of human corneal epithelial cells in an ex-vivo tissue model following MRSA infection and rose bengal PDAT.
Methods: EpiCorneal tissue models (Maktek) were prepared according to manufacturer’s protocol. All groups were tested in duplicate: Control, Infection, Infection-PDAT. Infections were created in the tissue with three separate MRSA inocula (10E5 CFU/mL). For the Infection-PDAT group, 0.1% rose bengal solution was applied and wells were irradiated with a custom-made green LED light source. After 30 minutes, fluid from all of the tissue model wells was collected and IL-1, 6 and 8 were quantified with ELISA kits (Thermo Fisher Scientific).
Results: The EpiCorneal Tissue model simulated the immune response of human corneal epithelial cells during MRSA infection and treatment with PDAT. Compared to the control, the immune response increased in all three MRSA infection groups. Of the cytokines tested, IL-8 showed the greatest response in the tissue models, followed by IL-6 and IL-1. In the Infection-PDAT groups, immune response was mixed depending on the MRSA strain. The largest downregulation of immune factors was observed in the community-associated MRSA strain.
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