A Novel Norepinephrine-β2-Adrenoceptor Based Therapy for Pseudomonas aeruginosa Keratitis Via Regulating Bacterial Virulence and Inflammatory Response

Background: Tissue injury causes the secretion of stress hormone catecholamine and increases susceptibility to opportunistic infection. This study explored the role of norepinephrine (NE)-b2-adrenoceptor (AR) signaling on the progression of Pseudomonas aeruginosa (P. aeruginosa) corneal infection in mice. Methods: C57BL/6 mouse cornea was inoculated with P. aeruginosa after scarification. Exogenous NE, DSP-4, and various AR antagonists were applied after or before infection. Clinical score, bacterial load, neutrophil infiltration, bacterial virulence factor and mouse proinflammatory factor expression were evaluated. Findings: Corneal scarification elevated NE levels. The progression of P. aeruginosa keratitis was accelerated by exogenous NE, while reversed by local NE depletion with DSP-4. Among 6 antagonists, the selective β2-AR antagonist ICI118551 showed the most significant effect on the reduction of disease severity, which was accompanied with the attenuation of bacterial load, neutrphil infiltration, bacterial virulence factor and proinflammatory factor levels. In addition, ICI118551 possessed similar antibacterial activity towards P. aeruginosa, Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) in vitro. Interpretation: Increased NE content caused by injury facilitated P. aeruginosa corneal infection. Selective β2-AR antagonist ICI118551 attenuated the disease severity and assumed similar inhibition on multiple bacteria, which may represent a novel therapeutic approach for the treatment of bacterial keratitis. Funding: This work was supported by the National Natural Science Foundation of China, Shandong Provincial Nature Science Fund for Distinguished Young Scholars, Taishan Scholar Program and Innovation Project of Shandong Academy of Medical Sciences. Declaration of Interest: All authors: No reported conflicts of interest. Ethical Approval: All animals were treated in compliance with the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research and the Public Health Policy on Humane Care and Use of Laboratory Animals (US Public Health Review). All procedures were approved by the Institutional Animal Care and Use Committee.