C-X-C chemokine receptor type 5 (CXCR5) influences corneal wound healing in vivo

Abstract

Purpose : Recently we characterized the expression of CXCR5 in the cornea and its potential role in corneal injury and inflammation in vivo. This study investigated the role of CXCR5 in corneal wound healing and inflammatory events post-injury in vivo using CXCR5-deficient (CXCR5^-/-) and wild-type (CXCR5^+/+) mice.

Methods : One hundred and sixty mice (8-10 weeks) were divided into four groups: Group-1 CXCR5^+/+ alkali injured mouse cornea (n = 40), Group-2 CXCR5^-/- alkali injured mouse cornea (n = 40), Group-3 CXCR5^+/+ mouse naïve cornea (n = 40) and Group-4 CXCR5^-/- mouse naïve cornea (n = 40). One eye of each mouse in Groups 1 and 2 were injured with an alkali solution of sodium hydroxide (NaOH; 0.5M) for 30s under anesthesia. Groups 3 and 4 served as naïve controls for the corresponding groups 1 and 2, respectively. Clinical corneal imaging was performed pre-injury and post-injury at various times with stereomicroscope. After humane euthanasia, eyes were used for histology, immunofluorescence, and qRT-PCR studies.

Results : Corneas of wildtype mice post-injury showed significantly increased mRNA (p < 0.001) and protein (p < 0.01 or p <0.0001) levels of CXCR5 in a time dependent manner. Uninjured CXCR5^-/- (naïve) corneas displayed no phenotype or structural changes in clinical, histological, and molecular analyses. Conversely, CXCR5^-/- injured corneas showed significantly increased inflammatory and angiogenic responses. A varied levels of corneal inflammation were observed from 4h to day-14. Initiation of neovascularization happened at day 7 and kept growing progressively until longest tested day-14. At day 14 post-injury, corneal neovascularization in CXCR5^-/- eyes was significantly higher than the CXCR5^+/+eyes (p < 0.01). Additionally, corneas of CXCR5^-/- mice showed significantly increased expression of angiogenic (VEGF up to 15-fold, p <0.01), inflammatory (TNFα up to 3-fold, p <0.05; COX-2 up to 5-fold, p <0.0001; IL-6 up to 10-fold, p <0.01; and IL-1β up to 5-fold, p <0.0001), and fibrotic (α-SMA up to 17 fold, p <0.05) markers compared to CXCR5^+/+corneas in a time-dependent manner.

Conclusions : CXCR5 appears to play an important role in corneal inflammation and wound healing events post injury. Mechanistic studies are ongoing.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.