July 2019
Volume 60, Issue 9
Free
ARVO Annual Meeting Abstract  |   July 2019
Integrative metabolomics and transcriptomics analysis reveals a Krebs cycle metabolite “itaconate” in promoting inflammation resolution in bacterial endophthalmitis
Author Affiliations & Notes
  • Sukhvinder Singh
    Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
  • Pawan Kumar Singh
    Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
  • Shailendra Giri
    Department of Neurology, Henry Ford Health System, Detroit, Michigan, United States
  • Ashok Kumar
    Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
  • Footnotes
    Commercial Relationships   Sukhvinder Singh, None; Pawan Kumar Singh, None; Shailendra Giri, None; Ashok Kumar, None
  • Footnotes
    Support  NIH R01 EY026964, EY027381, P30 EY004068, RPB
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 4636. doi:https://doi.org/
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      Sukhvinder Singh, Pawan Kumar Singh, Shailendra Giri, Ashok Kumar; Integrative metabolomics and transcriptomics analysis reveals a Krebs cycle metabolite “itaconate” in promoting inflammation resolution in bacterial endophthalmitis. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4636. doi: https://doi.org/.

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

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Abstract

Purpose : While recent advances in “omics” technologies have been dramatic, extracting biological insight from complex metabolic and transcriptome profiles remains a challenge. We integrated these two high throughput screening approaches, to determine key signaling pathways perturbed in bacterial endophthalmitis. This led to the identification of an endogenous metabolite “itaconate” which is altered in this disease. Hence, this study is designed to determine the role of itaconate in bacterial endophthalmitis.

Methods : Staphylococcal endophthalmitis was induced in, C57BL/6 or Irg1-/- mice. The therapeutic efficacy of itaconate was evaluated by intravitreal injections of dimethyl itaconate (DMI) or 4-octyl itaconate (OI) in infected eyes. In vitro studies were performed using human Müller glia and mouse bone marrow-derived macrophages (BMDMs) and challenging them with S. aureus in the presence or absence of DMI or OI. The pro-inflammatory cytokines were measured by qRT-PCR and ELISA. Western blot was performed to assess the activation of itaconate-mediated signaling pathways.

Results : Metabolomics analysis revealed a time-dependent increase in the production of itaconate in S. aureus-infected retina. This coincided with induced expression of Irg1 as revealed by transcriptomics approach. In comparison with C57BL/6, Irg1-/- mice exhibited the exacerbated endophthalmitis with increased inflammation and retinal tissue damage. Administration of DMI or OI significantly reduced intraocular inflammation resulting in preserved retinal architecture and function. Similarly, itaconate attenuated bacterial-induced inflammation in Müller glia and mouse BMDMs, potentially by activating anti-oxidant pathways (NRF2, HO-1, and Keap1). Activation of this signaling cascade was also observed in retina in vivo. Most importantly, co-administration of itaconate with vancomycin at sub-MIC levels resulted in ameliorated disease severity.

Conclusions : Our findings demonstrate retinal metabolism is altered in endophthalmitis, leading to the production of itaconate, which exerts anti-inflammatory actions to limit tissue damage by promoting inflammation resolution. Moreover, itaconate can be used as an adjunct anti-inflammatory therapy along with antibiotics to improve visual outcome in endophthalmitis.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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