June 2021
Volume 62, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2021
Chemokine CCL5 promotes robust optic nerve regeneration and mediates many of the effects of CNTF gene therapy
Author Affiliations & Notes
  • Lili Xie
    Boston Children's Hospital, Boston, Massachusetts, United States
  • Yuqin Yin
    Boston Children's Hospital, Boston, Massachusetts, United States
  • Larry Benowitz
    Boston Children's Hospital, Boston, Massachusetts, United States
  • Footnotes
    Commercial Relationships   Lili Xie, None; Yuqin Yin, None; Larry Benowitz, None
  • Footnotes
    Support  none
Investigative Ophthalmology & Visual Science June 2021, Vol.62, 2361. doi:
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      Lili Xie, Yuqin Yin, Larry Benowitz; Chemokine CCL5 promotes robust optic nerve regeneration and mediates many of the effects of CNTF gene therapy. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2361.

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

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Abstract

Purpose : Ciliary neurotrophic factor (CNTF) is a therapeutic candidate for several ocular diseases and has been widely employed in studies of optic nerve regeneration. However, whereas recombinant CNTF (rCNTF) generally induces only low levels of optic nerve regeneration (unless SOCS3, suppressor of cytokine signaling-3) is deleted in retinal ganglion cells (RGCs), AAV-mediated CNTF expression in RGCs induces strong regeneration. Intravitreal virus injections induce moderate intraocular inflammation, and CNTF is a known immune modulator. We therefore tested whether the beneficial effects of AAV- mediated CNTF delivery are due to intraocular inflammation and elevation of pro-regenerative and neuroprotective factors.

Methods : rCNTF, AAV2-CNTF, AAV2-sh-CNTFR (targeting CNTFRa, the CNTF receptor) or control agents were injected intravitreally. Intravenous anti-Ly6G antibody (vs. isotype-matched IgG2a) was used to deplete neutrophils. C-C motif chemokine receptor 2 (CCR2) knockout mice were used to inhibit monocyte infiltration. Immunohistochemistry was used to identify various inflammatory cell types, inflammation-related growth factors (C-C motif chemokine ligand 5, CCL5, etc.) and relevant receptors. RT-PCR was used to quantify mRNA levels of these and other gene products. We also tested CCR5 general knockout, a receptor antagonist, and RGC-specific CCR5 knockdown.

Results : Whereas intravitreal rCNTF induced little axon regeneration, AAV2-CNTF had strong effects on RGC survival and axon regeneration. CNTFRa was expressed primarily in non-neuronal cells, and CNTFRa knockdown in RGCs did not alter AAV2-CNTF-induced regeneration. AAV2-CNTF attracted inflammatory cells, particularly in the optic nerve head, and increased mRNA levels for CCL5 9.5-fold. Either neutrophil depletion or blocking monocyte infiltration dramatically decreased AAV2-CNTF-induced RGC survival and axon regeneration. Administration of a CCR5 antagonist or RGC-specific CCR5 knockdown both reduced axon regeneration ~ 70%. In gain-of-function studies, intraocular rCCL5 stimulated considerable optic nerve regeneration in vivo

Conclusions : The beneficial effects of CNTF gene therapy after optic nerve injury are mediated through immune modulation and upregulation of CCL5. Our results also raise the possibility that other widely used gene therapies could act in an indirect manner via unanticipated indirect mechanisms

This is a 2021 ARVO Annual Meeting abstract.

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