CXCL1-Deficient Mice Are Highly Sensitive toPseudomonas aeruginosabut Not Herpes Simplex Virus Type 1 Corneal Infection

Abstract

PURPOSE.To determine the role of the chemokine CXCL1 on leukocyte recruitment, cytokine production and host resistance during HSV-1 and Pseudomonas aeruginosa infection.METHODS. Viral titer and bacterial load were compared following infection of wild-type (WT) and CXCL1 À/À mice. Corneal leukocyte recruitment was determined using flow cytometry. Cytokine levels were assessed by luminex-based suspension arrays. Hematoxylin and eosin (H&E) staining, confocal microscopy, and optical coherence tomography (OCT) were used to visualize leukocyte recruitment and corneal thickening. RESULTS. HSV-1-infected WT and CXCL1À/À mice possessed similar viral titers in the cornea during late acute infection. Flow cytometry analysis detected similar leukocyte levels in the cornea following infection as well. By comparison, there was a significant increase in P. aeruginosa recovered from CXCL1 À/À corneas as compared with WT mice. Imaging analysis and histochemical staining revealed impaired leukocyte recruitment to the central cornea and earlier corneal thickening in CXCL1 À/À mice. IFN-c, CCL2, and CCL5 protein levels were similar between WT and CXCL1 À/À corneas following HSV-1 or P. aeruginosa infection. However, CXCL2 levels were significantly reduced in the CXCL1 À/À corneas following either infection.CONCLUSIONS. The absence of CXCL1 and CXCL2 expression significantly impairs the ability of the host to control P. aeruginosa replication through the recruitment of leukocytes to the central cornea. In contrast, CXCL1, CXCL2, and the cells they recruit, are not required for HSV-1 clearance during acute infection. (Invest Ophthalmol Vis Sci. 2012;53:6785-6792)

Monitoring of Strain-Dependent Responsiveness to TLR Activation in the Mouse Anterior Segment Using SD-OCT

“…Corneal thickness changes using OCT imaging have been reported in an infectious model of P. aeruginosa keratitis in C57BL/6 mice. 32 In this study, we report strain-dependent differences in corneal thickness changes in BALB/c and C57BL/6 mice following TLR9 ligand-induced inflammation. While corneal thickness in C57BL/6 mice peaked at 24 hours post treatment and had returned to baseline levels within 1 week, BALB/c corneas showed a delayed corneal thickness response, with a dramatic (approximately 30%) increase in thickness and evidence of a hyperreflective, subepithelial band at 1 week that may reflect an anterior stromal scarring response.…”

The Neonatal Fc Receptor and Complement Fixation Facilitate Prophylactic Vaccine-Mediated Humoral Protection against Viral Infection in the Ocular Mucosa

“…Noninvasive in vivo imaging of the anterior segment was performed on anesthetized animals using a Bioptigen spectral domain optical coherence tomography (SD-OCT) system (Leica Microsystems, Triangle Park, NC) to assess corneal structure and inflammation as previously characterized (28, 29). …”

Anterior segment optical coherence tomography: its application in clinical practice and experimental models of disease

“…Using AS‐OCT, it was reported that Pseudomonas aeruginosa elicited a greater degree of corneal inflammation in patients than other causative organisms of bacterial keratitis . In an experimental model of P. aeruginosa ‐infected microbial keratitis, SD‐OCT demonstrated elevated corneal oedema in Cxcl1 −/− mice, which lack the neutrophil‐attracting chemokine CXCL1, up to 24 hours post‐infection . In this study, SD‐OCT provided a higher sensitivity for detecting clinical corneal pathology compared to histological analysis, with corneal oedema visible at six hours post‐infection using SD‐OCT, but only after 12 hours post‐infection in histology sections .…”

“…Similar to its clinical use, novel applications of AS‐OCT to longitudinally monitor and quantitate the extent of inflammation have been documented in multiple experimental models of ocular inflammation, including uveitis, microbial keratitis, sterile inflammation and dry eye disease . Additionally, AS‐OCT has been used to monitor the resolution of inflammation in experimental models of corneal transplantation and corneal wound healing .…”