A novel murine model for contact lens wear reveals clandestine IL-1R dependent corneal parainflammation and susceptibility to microbial keratitis upon inoculation with Pseudomonas aeruginosa

Abstract

Purpose Contact lens wear carries a risk of complications, including corneal infection. Solving these complications has been hindered by limitations of existing animal models. Here, we report development of a new murine model of contact lens wear. Methods C57BL/6 mice were fitted with custom-made silicone-hydrogel contact lenses with or without prior inoculation with Pseudomonas aeruginosa (PAO1-GFP). Contralateral eyes served as controls. Corneas were monitored for pathology, and examined ex vivo using high-magnification, time-lapse imaging. Fluorescent reporter mice allowed visualization of host cell membranes and immune cells. Lens-colonizing bacteria were detected by viable counts and FISH. Direct-colony PCR was used for bacterial identification. Results Without deliberate inoculation, lens-wearing corneas remained free of visible pathology, and retained a clarity similar to non-lens wearing controls. CD11c-YFP reporter mice revealed altered numbers, and distribution, of CD11c-positive cells in lens-wearing corneas after 24 h. Worn lenses showed bacterial colonization, primarily by known conjunctival or skin commensals. Corneal epithelial cells showed vacuolization during lens wear, and after 5 days, cells with phagocyte morphology appeared in the stroma that actively migrated over resident keratocytes that showed altered morphology. Immunofluorescence confirmed stromal Ly6G-positive cells after 5 days of lens wear, but not in MyD88 or IL-1R gene-knockout mice. P. aeruginosa-contaminated lenses caused infectious pathology in most mice from 1 to 13 days. Conclusions This murine model of contact lens wear appears to faithfully mimic events occurring during human lens wear, and could be valuable for experiments, not possible in humans, that help solve the pathogenesis of lens-related complications.

Neutrophil Extracellular Traps Confine Pseudomonas aeruginosa Ocular Biofilms and Restrict Brain Invasion

“…However, there is growing evidence that the antimicrobial property of tears and the unique surface of the eye, combined with the nightly vacuuming by neutrophils and help from resident populations of other immune cells such as macrophages, prevent infections (Liyanage et al, 2016;Liu et al, 2017). While the eye has also been reported to have a microbiome (Lu and Liu, 2016), pathogen growth is infrequent unless there is foreign body involvement (i.e., contact lenses) or an injury (i.e., abrasion) that exposes the underlying surface (Metruccio et al, 2019). In addition, when the host is immunosuppressed and neutropenic, following organ transplantation or cancer treatment, for example (Ozkan et al, 2017;Nanda et al, 1991), the eye may rapidly succumb to opportunistic bacteria such as Pseudomonas aeruginosa, a leading cause of bacterial keratitis (Sy et al, 2012).…”

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

“…A lack of standardised methods and paucity of information on animal models means comparing ex vivo studies is difficult, and there is dispute regarding the suitability of different animal models. Ex vivo models used to investigate bacterial keratitis include mice [ 137 , 138 , 139 , 140 , 141 ], rabbits [ 140 , 141 , 142 , 143 , 144 , 145 , 146 ], goats [ 147 ], cows [ 148 ] and pigs [ 149 , 150 , 151 ]. It is currently unknown if interspecies differences in the thickness of the corneal epithelium [ 108 , 152 ] and stroma [ 153 , 154 , 155 ] play a major role in development and progression of infection in the ex vivo cornea.…”

“…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 ].…”

“…In vivo corneal models are ideal for studies of host immune defences, inflammation and corneal healing processes. However, these models are not suitable for studying the early stages of infection, as the healthy, intact cornea is difficult to infect unless contaminated contact lenses are used [ 138 , 182 , 183 ]. Additionally, initiating and developing infection takes days and is not always guaranteed [ 182 ].…”

Repair Process Impairment by Pseudomonas aeruginosa in Epithelial Tissues: Major Features and Potential Therapeutic Avenues

“…Indeed, several groups described that epithelial cells at the wound edges of injured airway epithelia exposed to P. aeruginosa bacteria or P. aeruginosa virulence factors feature reduced or loss of lamellipodial structures, stress fibers, focal adhesions and destruction of the actin cytoskeleton (de Bentzmann et al, 2000; Geiser et al, 2001; Losa et al, 2015) (Figure 1B). In a novel murine model of contact lens wear, it has been shown that PAO1 inoculation is associated with altered cell morphology, disrupted basal membrane and disorganized epithelial structure, with or without corneal opacity (Metruccio et al, 2019).…”