Extended Contact Lens Wear Promotes Corneal Norepinephrine Secretion and Pseudomonas aeruginosa Infection in Mice

Abstract

PURPOSE. Extended contact lens (CL) wear predisposes the wearer to Pseudomonas aeruginosa infection of the cornea, but the mechanism involved remains incompletely understood. The purpose of this study was to investigate the role of the stress hormone norepinephrine (NE) in the pathogenesis of CL-induced P. aeruginosa keratitis. METHODS. A total 195 adult C57BL/6 mice were used in this study. Corneal NE content was measured after 48 hours of sterile CL wear in mice. The effect of NE on P. aeruginosa adhesion and biofilm formation on the CL surface was examined in vitro. Moreover, mouse eyes were covered with P. aeruginosa-contaminated CLs, and either 500-μM NE was topically applied or the eyes were subconjunctivally injected with 100 μg of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) to deplete local NE. Clinical scores, neutrophil infiltration, proinflammatory cytokine levels, and bacterial load on the corneas and CLs were evaluated. RESULTS. Corneal NE content was elevated with extended CL wear in mice. In vitro, NE promoted the adhesion and biofilm formation of P. aeruginosa on the CL surface. In mice, topical application of NE aggravated P. aeruginosa infection, accompanied with increased clinical scores, neutrophil infiltration, proinflammatory cytokine expression, and bacterial burden on the corneas and CLs. However, pre-depletion of local NE with DSP-4 significantly alleviated the severity of P. aeruginosa keratitis. CONCLUSIONS. Extended CL wear elevates corneal NE content, which promotes the pathogenesis of CL-induced P. aeruginosa keratitis in mice. Targeting NE may provide a potential strategy for the treatment of CL-related corneal infection caused by P. aeruginosa.

Preparation and Evaluation of Starch Hydrogel/Contact Lens Composites as Epigallocatechin Gallate Delivery Systems for Inhibition of Bacterial Adhesion

“…The cytotoxicity of EGCG loaded starch hydrogel/contact lens composites was evaluated based on the effects of contact lenses extracts on the proliferation of human corneal epithelial cells (HCECs, Seoul, Korea) through cell counting kit-8 (CCK-8) assay. 2.5 and 5 mg of different type contact lenses were respectively dipped in 10 ml DMEM/F12 (Sigma-Aldrich) containing 10% (v/v) fetal bovine serum (Sigma-Aldrich) and 1% (v/v) antibiotic/antimycotics (Sigma-Aldrich) in 37°C, 5% CO 2 incubator for 24 h to obtain contact lenses extracts with concentrations of 1:4 and 1:2 ( Li et al, 2020 ). While the HCECs were plated into a 96-well plate at 2000/well and cultured in standard culture medium (DMEM/F12, 10% FBS, 1% antibiotic/antimycotics) for 24 h in 37°C, 5% CO 2 incubator.…”

Corneal Infection Models: Tools to Investigate the Role of Biofilms in Bacterial Keratitis

“…In vivo modelling involves the use of live animals. Rat [ 171 ] and rabbit [ 172 , 173 , 174 ] models have been reported, but mouse models currently dominate the literature [ 131 , 137 , 138 , 175 , 176 , 177 , 178 ]. Despite its smaller size, the murine cornea contains more corneal epithelial cell layers than the human cornea and the ratio of epithelial to stromal cells is larger [ 179 ].…”

“…This has allowed researchers to begin to characterise the process of biofilm formation at the ocular surface ( Table 2 ). In vivo infection models have also played an integral role in other areas of bacterial keratitis research, including: biofilm formation on contact lenses in rabbit [ 172 ] and mice [ 175 ], host–pathogen interactions on ocular samples using proteomics [ 184 , 185 ], activation of immune signalling pathways [ 186 ], the role of virulence factors in keratitis [ 142 , 173 , 178 , 187 ] and drug testing of new ophthalmic antimicrobials [ 174 , 176 , 188 ]. Drug testing has included synthetic analogues of host antimicrobial peptides, with one study reporting reduced corneal bioburden and improved ocular scores following treatment with their lead peptide [ 188 ].…”

β2-adrenoceptor blocker ICI118551 attenuates Pseudomonas aeruginosa corneal infection in mice

“…Mice were anesthetized and the left corneas were scratched to create three 1-mm incisions using a sterile 25-gauge needle, then inoculated with bacterial suspension containing 1 × 10 5 colony-forming units (CFU) of P. aeruginosa (ATCC 19660). The procedure of corneal infection was performed according to the protocol reported previously (Li et al ., 2020). Sterile saline was used to dissolve the six AR blockers: the α1/2-AR blocker Phentolamine (50 mg/ml), β1-AR blocker Atenolol (8 mg/ml), β2-AR blocker ICI118551 (5 mg/ml), β2-AR blocker Butoxamine (40 mg/ml), β1/2-AR blocker Timolol (4.4 mg/ml), or β3-AR blocker SR58894A (5 mg/ml), and 5 μL was instilled 30 min before P. aeruginosa inoculation, restarted from 6 h after infection, and continued for 3 days (six times a day).…”