The Absence of CCL Chemokines Protects Against Retinal Function Loss during Staphylococcus aureus endophthalmitis

Abstract

Purpose : To test the hypothesis that CCL chemokines, CCL2 and CCL3, contribute to retinal function decline during Staphylococcus aureus endophthalmitis.

Methods : Experimental S. aureus endophthalmitis was induced by intravitreal injection of 5000 colony forming units (CFU) of S. aureus into the eyes of C57BL/6J, CCL2^-/- (C57BL/6.129S4-Ccl2^tm1Rol/J) or CCL3^-/- (C57BL/6.129P2-Ccl3^tm1Unc/J) mice. At 12 and 24 hours postinfection, bacterial load and retinal function were quantified.

Results : During S. aureus endophthalmitis, we observed a significant improvement in retinal function in CCL2^-/- mice relative to C57BL/6J mice at 12 hours (p ≤ 0.0131), but not at 24 hours postinfection (p ≥ 0.8968). However, in CCL3^-/- mice, retinal function was significantly improved relative to C57BL/6J mice at both 12 and 24 hours postinfection (p ≤ 0.0249). At 12 and 24 hours postinfection, the absence of CCL2 did not alter intraocular S. aureus intraocular concentrations (p ≥ 0.2926). However, significantly lower concentrations of S. aureus were observed in CCL3^-/- mice relative to C57BL/6J mice at 12 hours (p = 0.0008) but not at 24 hours (p = 0.9882) postinfection.

Conclusions : The absence of CCL2 resulted in a delay in retinal function decline. In contrast, the absence of CCL3 resulted in improved retinal function retention at both early and later timepoints, suggesting a more important role for CCL3 in S. aureus endophthalmitis.

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