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2019 OMIG Abstract

Immune Response in a Rabbit Model of Pythium Insidiosum Keratitis

Savitri Sharma1, Lalit K Ahirwar1, Ranjith Konduri1, Paavan Kalra2
1Jhaveri Microbiology Centre, L V Prasad Eye Institute, India; 2Tej Kohli Cornea Institute, L V Prasad Eye Institute, India

Purpose: Pythium insidiosum keratitis is being increasingly reported and the clinical features along with diagnostic methods have been recently described in a number of publications from India. However, there is paucity of information related to immuno-pathogenesis of P. insidiosum in the literature. We developed a rabbit model of P. insidiosum keratitis to study the pathogenesis, immune response and therapeutic options. The aim of this study is to report the innate and adaptive immune response in rabbit cornea infected with P. insidiosum.

Methods: New Zealand white rabbits were infected with two doses (low and high) via two routes: intra-corneal or topical with or without immunosuppression. Cornea from both right (infected with Pythium) and left eye (PBS pH 7.4- control) were harvested at different stages of infection (early, progressive, late) and a portion was preserved in RNALater to perform reverse transcriptase qPCR for cytokines, chemokines and antimicrobial peptides (AMPs).

Results: Innate cytokines (IL-1 and CCL4), AMPs (CAP18 and LeukoP) and IL-17A (adaptive cytokine) were highly upregulated in progressive stage followed by early and late stage of infection. IL6, IL22, TGF and IFNY (interlink between the innate and adaptive immunity) and IL8 (innate cytokine) showed lower expression in comparison to these cytokines although the expression level was in the same descending order. There was no difference in cytokine expression between the groups of rabbit infected with low and high doses of Pythium, however, the cytokine expression was higher in steroid group compared to non-steroid group.

Conclusion: Innate immune mediators and AMPs seem to play a critical role in host defense mechanism against P. insidiosum in rabbit cornea and are not dependent on the infective dose.

Disclosure: N


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