April 2014
Volume 55, Issue 13
ARVO Annual Meeting Abstract  |   April 2014
IL-17A-Mediated Protection against Acanthamoeba Keratitis
Author Affiliations & Notes
  • Amol Suryawanshi
    Ophthalmology, New England Eye Center, Tufts University School of Medicine, Boston, MA
  • Zhiyi Cao
    Ophthalmology, New England Eye Center, Tufts University School of Medicine, Boston, MA
  • James Sampson
    Immunology, Tufts University School of Medicine, Boston, MA
  • Noorjahan A Panjwani
    Ophthalmology, New England Eye Center, Tufts University School of Medicine, Boston, MA
    Biochemistry, Tufts University School of Medicine, Boston, MA
  • Footnotes
    Commercial Relationships Amol Suryawanshi, None; Zhiyi Cao, None; James Sampson, None; Noorjahan Panjwani, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 1689. doi:
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      Amol Suryawanshi, Zhiyi Cao, James Sampson, Noorjahan A Panjwani; IL-17A-Mediated Protection against Acanthamoeba Keratitis. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1689.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: Acanthamoeba Keratitis (AK) is a very painful and vision impairing condition of the cornea that is difficult to treat. Although past studies have indicated a critical role of neutrophils and macrophages in AK, the relative contribution of a proinflammatory cytokine, IL-17A that promotes migration, activation and function of neutrophils in the cornea is poorly defined. Moreover, the role of the adaptive immune response, particularly contribution of CD4+ T cell subsets such as Th17 and Tregs, in AK is yet to be understood.

Methods: C57BL/6 mice corneas were intrastromally injected with 2.5 × 104 Acanthamoebae for corneal infection. Acanthamoeba infected mice corneas and local draining lymph nodes (dLN) were analyzed on day 5 and day 8 post infection (pi) for neutrophils, CD4+ T cells, Th1, Th2, Th17 and Treg cell composition by flow cytometry. In another set of experiments, corneal IL-17A expression was analyzed on day 1, 3, 5 and 8 pi. Furthermore, infected mice were treated with anti-IL-17A or isotype monoclonal antibody every alternate day starting from day 1 until day 7 pi. The severity of AK was scored on day 1, 3, 5 and 7 pi. On day 8 pi, corneas and dLN were collected to analyze the effect of anti-IL-17A treatment on various CD4+ T cell subsets by flow cytometry.

Results: Corneal Acanthamoeba infection induced both Teffector (Th1, Th2 and Th17) and regulatory T cell response in the cornea at all tested days pi. More importantly, our studies revealed that Acanthamoeba infection induces IL-17A expression and that IL-17A is essential for host protection against severe AK pathology. Accordingly, IL-17A neutralization in Acanthamoeba infected animals resulted in a significantly increased corneal AK pathology, increased migration of inflammatory cells at the site of inflammation and a significant increase in effector CD4+ T cell response in dLN. Further studies indicated that neutrophils and CD4+ T cells contribute to the source of IL-17A during early and late stages of AK respectively.

Conclusions: Corneal Acanthamoeba infection induces both Teffector and Treg response in the cornea. Moreover, in sharp contrast to other corneal infections such as Herpes and Pseudomonas aeruginosa keratitis where IL-17A exacerbates corneal pathology and inflammation, findings reported in this study indicate that IL-17A response after Acanthamoeba infection plays an important role in host protection against invading parasites.

Keywords: 402 Acanthamoeba • 573 keratitis • 557 inflammation  

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