Proper sight is not possible without a smooth, transparent cornea, which is highly exposed to environmental threats. The abundant corneal nerves are interspersed with epithelial cells in the anterior corneal surface and are instrumental to corneal integrity and immunoregulation. Conversely, corneal neuropathy is commonly observed in some immune-mediated corneal disorders but not in others, and its pathogenesis is poorly understood. Here we hypothesized that the type of adaptive immune response may influence the development of corneal neuropathy. To test this, we first immunized OT-II mice with different adjuvants that favor T helper (Th)1 or Th2 responses. Both Th1-skewed mice (measured by interferon-γ production) and Th2-skewed (measured by interleukin-4 production) developed comparable ocular surface inflammation and conjunctival CD4+ T cell recruitment but no appreciable corneal epithelial changes upon repeated local antigenic challenge. Th1-skewed mice showed decreased corneal mechanical sensitivity and altered corneal nerve morphology (signs of corneal neuropathy) upon antigenic challenge. However, Th2-skewed mice also developed milder corneal neuropathy immediately after immunization and independently of ocular challenge, suggestive of adjuvant-induced neurotoxicity. All these findings were confirmed in wild-type mice. To circumvent unwanted neurotoxicity, CD4+ T cells from immunized mice were adoptively transferred to T cell-deficient mice. In this setup, only Th1-transferred mice developed corneal neuropathy upon antigenic challenge. To further delineate the contribution of each profile, CD4+ T cells were polarized in vitro to either Th1, Th2, or Th17 cells and transferred to T cell-deficient mice. Upon local antigenic challenge, all groups had commensurate conjunctival CD4+ T cell recruitment and macroscopic ocular inflammation. However, none of the groups developed corneal epithelial changes and only Th1-transferred mice showed signs of corneal neuropathy. Altogether, the data show that corneal nerves, as opposed to corneal epithelial cells, are sensitive to immune-driven damage mediated by Th1 CD4+ T cells in the absence of other pathogenic factors. These findings have potential therapeutic implications for ocular surface disorders.
Proper sight is not possible without a smooth, transparent cornea, which is highly exposed to environmental threats. The abundant corneal nerves are interspersed with epithelial cells in the anterior corneal surface and are instrumental to corneal integrity and immunoregulation. Conversely, corneal neuropathy is commonly observed in some immune-mediated corneal disorders but not in others, and its pathogenesis is poorly understood. Here we hypothesized that the type of adaptive immune response may influence the development of corneal neuropathy. To test this, we first immunized OT-II mice with different adjuvants that favor T helper (Th)1 or Th2 responses. Both Th1-skewed mice (measured by interferon-γproduction) and Th2-skewed (measured by interleukin-4 production) developed comparable ocular surface inflammation and conjunctival CD4+ T cell recruitment but no appreciable corneal epithelial changes upon repeated local antigenic challenge. Th1-skewed mice showed decreased corneal mechanical sensitivity and altered corneal nerve morphology (signs of corneal neuropathy) upon antigenic challenge. However, Th2-skewed mice also developed milder corneal neuropathy immediately after immunization and independently of ocular challenge, suggestive of adjuvant-induced neurotoxicity. All these findings were confirmed in wild-type mice. To circumvent unwanted neurotoxicity, CD4+ T cells from immunized mice were adoptively transferred to T cell-deficient mice. In this setup, only Th1-transferred mice developed corneal neuropathy upon antigenic challenge. To further delineate the contribution of each profile, CD4+ T cells were polarized in vitro to either Th1, Th2, or Th17 cells and transferred to T cell-deficient mice. Upon local antigenic challenge, all groups had commensurate conjunctival CD4+ T cell recruitment and macroscopic ocular inflammation. However, none of the groups developed corneal epithelial changes and only Th1-transferred mice showed signs of corneal neuropathy. Altogether the data show that corneal nerves, as opposed to corneal epithelial cells, are sensitive to immune-driven damage mediated by Th1 CD4+ T cells in the absence of other pathogenic factors. These findings have potential therapeutic implications for ocular surface disorders.
Purpose: To evaluate the protective effect of different concentrations of sodium hyaluronate (SH) on the Benzalkonium chloride (BAK)‐induced toxicity using an in vitro model. Methods: The NAV14 cell line (SV40‐immortalized murine conjunctival epithelium) was used. Cell monolayers were exposed to different combinations of BAK (0.001%; 0.005%; 0.01%) and SH (0.2%; 0.3%; 0.4%) for 15 minutes; then cells were washed, and fresh culture media was added. Cell viability was evaluated after 2 h by resazurin reduction and lactate dehydrogenase (LDH) release. Also, cell migration and proliferation over 24 hours were determined by the scratch wound‐healing assay. Data were analysed by two‐way ANOVA and are shown as mean ± SD of two independent experiment with 4–6 replicates each. Results: BAK induced a concentration‐dependent decrease on cell viability (BAK 0.001%: 91 ± 14%, BAK 0.005%: 45 ± 9% and BAK 0.01%: 22 ± 10% of control cells, p < 0.001) and an increase in LDH release (no BAK:0.22 ± 0.02, BAK 0.001%: 0.31 ± 0.02, BAK 0.005%: 1.14 ± 0.05 and BAK 0.01%: 1.21 ± 0.05, p < 0.001). Conversely, SH neutralized these effects also in a concentration‐dependent manner (p < 0.001). In the presence of SH 0.4% (highest effect), cell viability was BAK 0.001%: 104 ± 22%, BAK 0.005%: 109 ± 9% and BAK 0.01%: 75 ± 13% of control cells (p < 0.001 for BAK 0.005–0.01%) while LDH release was no BAK: 0.24 ± 0.03, BAK 0.001%: 0.26 ± 0.01, BAK 0.005%: 0.37 ± 0.02 and BAK 0.01%: 0.49 ± 0.22, (vs. no SH: p < 0.001 for BAK 0.005–0.01%). BAK also reduced wound closure in vitro (after 24 h, no BAK: 76 ± 14%, BAK 0.001%: 42 ± 12%, BAK 0.005%: 17 ± 16% and BAK 0.01%: 0.0% wound closure, p < 0.001 for all BAK). Conversely, SH neutralized this effect in a concentration‐dependent fashion (p < 0.001). In the presence of SH 0.4% (highest effect), wound closure at 24 h was: no BAK: 81 ± 15%, BAK 0.001%: 58 ± 6%, BAK 0.005%: 63 ± 10%, BAK 0.01%: 60 ± 8% (vs no SH: p < 0.001 for BAK 0.005–0.01%). Conclusions: Sodium hyaluronate neutralized BAK toxicity on conjunctival epithelial cells in a concentration‐dependent manner. SH 0.4% was even protective at the highest preservative concentrations. These findings support the use of SH to mitigate BAK toxicity in long‐term antiglaucomatous treatment, although more studies are needed.
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.