Herpes simplex virus type 1 (HSV-1) is a leading cause of neurotrophic keratitis characterized by decreased corneal sensation because of damage to the corneal sensory fibers. We and others have reported regression of corneal nerves during acute HSV-1 infection. To determine whether denervation is caused directly by the virus or indirectly by the elicited immune response, mice were infected with HSV-1 and topically treated with dexamethasone (DEX) or control eye drops. Corneal sensitivity was measured using a Cochet-Bonnet esthesiometer and nerve network structure via immunohistochemistry. Corneas were assessed for viral content by plaque assay, leukocyte influx by flow cytometry, and content of chemokines and inflammatory cytokines by suspension array. DEX significantly preserved corneal nerve structure and sensitivity on infection. DEX reduced myeloid and T-cell populations in the cornea and did not affect viral contents at 4 and 8 days post infection. The elevated protein contents of chemokines and inflammatory cytokines on infection were greatly suppressed by DEX. Subconjunctival delivery of neutralizing antibody against IL-6 to infected mice resulted in partial preservation of corneal nerve structure and sensitivity. Our study supports a role for the immune response, but not local virus replication in the development of HSV-1einduced neurotrophic keratitis. IL-6 is one of the factors produced by the elicited inflammatory response to HSV-1 infection contributing to nerve regression.
Herpes simplex virus type 1 (HSV-1) infection of the cornea induces VEGF-A-dependent lymphangiogenesis that continues to develop well beyond the resolution of infection. Inflammatory leukocytes infiltrate the cornea and have been implicated to be essential for corneal neovascularization, an important clinically relevant manifestation of stromal keratitis. Here, we report that cornea infiltrating leukocytes including neutrophils and T cells do not have a significant role in corneal neovascularization past virus clearance. Antibody mediated depletion of these cells did not impact lymphatic or blood vessel genesis. Multiple pro-angiogenic factors including IL-6, angiopoietin-2, HGF, FGF-2, VEGF-A, and MMP-9 were expressed within the cornea following virus clearance. A single bolus of dexamethasone (DEX) at day 10 pi resulted in suppression of blood vessel genesis and regression of lymphatic vessels at day 21 pi compared to control-treated mice. Whereas IL-6 neutralization had a modest impact on hemangiogenesis (day 14–21 pi) and lymphangiogenesis (day 21 pi) in a time-dependent fashion, neutralization of FGF-2 had a more pronounced effect on the suppression of neovascularization (blood and lymphatic vessels) in a time-dependent, leukocyte-independent manner. Furthermore, FGF-2 neutralization suppressed the expression of all pro-angiogenic factors measured and preserved visual acuity.
The capacity of licensed vaccines to protect the ocular surface against infection is limited. Common ocular pathogens such as herpes simplex virus type 1 (HSV-1) are increasingly recognized as major contributors to visual morbidity worldwide. Humoral immunity is an essential correlate of protection against HSV-1 pathogenesis and ocular pathology, yet the ability of antibody to protect against HSV-1 is deemed limited due to the slow IgG diffusion rate in the healthy cornea. We show that a live-attenuated HSV-1 vaccine elicits humoral immune responses that are unparalleled by a glycoprotein subunit vaccine vis-à-vis antibody persistence and host protection. The live-attenuated vaccine was utilized to assess the impact of immunization route on vaccine efficacy. The hierarchical rankings of primary immunization route with respect to efficacy were: subcutaneous ≥ mucosal > intramuscular. Prime-boost vaccination via sequential subcutaneous and intramuscular administration yielded greater efficacy than any other primary immunization route alone. Moreover, our data also support a role of complement in prophylactic protection as evidenced by intracellular deposition of C3d in the corneal epithelium of vaccinated animals following challenge and delayed viral clearance in C3-deficient mice. We also identify that the neonatal Fc receptor (FcRn) is upregulated in the cornea following infection or injury concomitant with increased antibody perfusion. Lastly, selective siRNA-mediated knockdown of FcRn in the cornea impeded protection against ocular HSV-1 challenge in vaccinated mice. Collectively, these findings establish a novel mechanism of humoral protection in the eye involving FcRn and may facilitate vaccine and therapeutic development for other ocular surface diseases.
Herpes simplex virus type 1 (HSV-1) infection of the cornea induces vascular endothelial growth factor (VEGF)-A-dependent lymphangiogenesis. However, the extent to which HSV-1-induced corneal lymphangiogenesis impacts the adaptive immune response has not been characterized. Here, we used floxed VEGF-A mice to study the importance of newly created corneal lymphatic vessels in the host adaptive immune response to infection. Whereas the mice infected with the parental virus (strain SC16) exhibited robust corneal lymphangiogenesis, mice that received the recombinant virus (SC16 ICP0-Cre) that expresses Cre recombinase under the control of infected cell protein 0 (ICP0), an HSV-1 immediate early gene, showed a significant reduction in lymphangiogenesis. There was no difference in virus recovered from the cornea of mice infected with SC16 vs SC16 ICP0-Cre. However, viral loads were significantly elevated in the trigeminal ganglia (TG) of mice with reduced corneal lymphangiogenesis. The increase in viral titer correlated with a significant loss of HSV-1-specific CD8+ T cells that traffic to the TG of mice infected with the recombinant virus. Intrastromal delivery of size exclusion dye (FITC-dextran) revealed a time-dependent defect in the ability of the lymphatic vessels in SC16 ICP0-Cre infected mice to transport soluble antigen from the cornea to the draining lymph nodes. We interpret these results to suggest that the newly created lymphatic vessels in the cornea driven by HSV-1 infection are critical in the delivery of soluble viral antigen to the draining lymph node and subsequent development of the CD8+ T cell response to HSV-1.
PurposeHerpes simplex virus type-1 (HSV-1) is a leading cause of neurotrophic keratitis, characterized by decreased or absent corneal sensation due to damage to the sensory corneal innervation. We previously reported the elicited immune response to infection contributes to the mechanism of corneal nerve regression/damage during acute HSV-1 infection. Our aim is to further establish the involvement of infiltrated macrophages in the mechanism of nerve loss upon infection.MethodsMacrophage Fas-Induced Apoptosis (MAFIA) transgenic C57BL/6 mice were systemically treated with AP20187 dimerizer or vehicle (VEH), and their corneas, lymph nodes, and blood were assessed for CD45+CD11b+GFP+ cell depletion by flow cytometry (FC). Mice were ocularly infected with HSV-1 or left uninfected. At 2, 4, and/or 6 days post infection (PI), corneas were assessed for sensitivity and harvested for FC, nerve structure by immunohistochemistry, viral content by plaque assay, soluble factor content by suspension array, and activation of signaling pathways by Western blot analysis. C57BL6 mice were used to compare to the MAFIA mouse model.ResultsMAFIA mice treated with AP20187 had efficient depletion of CD45+CD11b+GFP+ cells in the tissues analyzed. The reduction of CD45+CD11b+GFP+ cells recruited to the infected corneas of AP20187-treated mice correlated with preservation of corneal nerve structure and function, decreased protein concentration of inflammatory cytokines, and decreased STAT3 activation despite no changes in viral content in the cornea compared to VEH-treated animals.ConclusionsOur results suggest infiltrated macrophages are early effectors in the nerve regression following HSV-1 infection. We propose the neurodegeneration mechanism involves macrophages, local up-regulation of IL-6, and activation of STAT3.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.