Purpose: The host inflammatory response to ocular infection with herpes simplex virus (HSV) can be either protective, with disease-free survival, or it can promote diseases such as HSV corneal disease (or herpes stromal keratitis [HSK] in humans) and encephalitis (HSE), depending on mouse strain. The role of CXCR3 chemokine signaling in HSV-induced central nervous system (CNS) inflammation and corneal disease was evaluated, and responses in genetically susceptible and resistant strains of mice were contrasted.
Methods: Resistant C57BL/6J (B6) and susceptible 129S6 (129) mice were given monoclonal antibodies (mAbs) to neutralize the CXCR3 ligands monokine induced by interferon-gamma (MIG, CXCL9) and interferon inducible protein-10 (IP-10, CXCL10) during HSV infection. In addition, the development of HSV disease was monitored in CXCR3-null mutant mice derived from resistant (B6) and susceptible (BALB/c) strains. Inflammatory cells infiltrating the cornea and brain stem were isolated and stained for flow cytometric analysis.
Results: MIG and IP-10 were induced in nervous system tissue after HSV inoculation by the corneal route. HSV-infected 129 mice treated with MIG- or IP-10-neutralizing mAbs showed significantly enhanced survival compared with mice treated with control isotype antibody, whereas survival of the B6 mice was unaltered. Similarly, greater survival was observed for BALB.CXCR3(-/-) mice compared with control BALB/c mice. Reduced CNS inflammation was documented that extended to the cornea, such that HSV corneal disease severity was reduced in susceptible BALB.CXCR3(-/-). In contrast, although survival of B6 and B6.CXCR3(-/-) mice was indistinguishable, B6.CXCR3(-/-) mice developed more severe corneal and periocular skin disease.
Conclusions: The effects of CXCR3 signaling in HSV infection are strongly dependent on mouse strain.