Regulatory role of IL-1beta in the expression of IL-6 and IL-8 in human corneal epithelial cells during Pseudomonas aeruginosa colonization.

Pseudomonas aeruginosa is a virulent pathogen and is frequently associated with bacterial keratitis. Recent studies have shown that high levels of interleukin (IL)-1beta and macrophage inflammatory protein-2 are associated with the severity of corneal infection. Interleukin-1beta is a principal inflammatory mediator. Understanding the regulatory role of IL-1beta would provide better understanding of host responses during P. aeruginosa corneal infection. A human corneal epithelial (HCE) cell line and three P. aeruginosa strains were used in this experiment. Confluent HCE cells were challenged with P. aeruginosa and monoclonal antihuman IL-1beta antibody (IL-1beta mAb). The culture supernatants were collected for measuring cytotoxicity and protein levels of IL-1beta, IL-8 and IL-6 by enzyme-linked immunosorbent assay. Results showed that HCE cells expressed low levels of IL-1beta and high levels of IL-6 and IL-8 during P. aeruginosa colonization. Paer1-colonized HCE cells produced higher levels of IL-1beta, IL-6 and IL-8 protein compared to those produced by 6206- and 6294-colonized HCE cells. Administration of IL-1beta mAb decreased the production of IL-8 and IL-6. In conclusion, P. aeruginosa-colonized HCE cells produced low levels of IL-1beta and high levels of IL-6 and IL-8. Neutralizing IL-1beta protein significantly downregulated the production of IL-8 and IL-6.