April 2011
Volume 52, Issue 14
Free
ARVO Annual Meeting Abstract  |   April 2011
Association of the Complement Pathway with Retinal Degeneration in the AY9944-Induced Rat Model of Smith-Lemli-Opitz Syndrome
Author Affiliations & Notes
  • Lowell G. Sheflin
    Research Service, VAWNYHS, Buffalo, New York
  • Joyce E. Young
    Ophthalmology & Biochemistry, SUNY-Buffalo/SUNY Eye Institute, Buffalo, New York
  • Bruce A. Pfeffer
    Ophthalmology & Biochemistry, SUNY-Buffalo/SUNY Eye Institute, Buffalo, New York
  • Steven J. Fliesler
    Research Service, VAWNYHS, Buffalo, New York
    Ophthalmology & Biochemistry, SUNY-Buffalo/SUNY Eye Institute, Buffalo, New York
  • Footnotes
    Commercial Relationships  Lowell G. Sheflin, None; Joyce E. Young, None; Bruce A. Pfeffer, None; Steven J. Fliesler, None
  • Footnotes
    Support  NEI/NIH RO1 EY007361 (SJF); Unrestricted Grant, Research To Prevent Blindness (SJF).
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 1007. doi:
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      Lowell G. Sheflin, Joyce E. Young, Bruce A. Pfeffer, Steven J. Fliesler; Association of the Complement Pathway with Retinal Degeneration in the AY9944-Induced Rat Model of Smith-Lemli-Opitz Syndrome. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1007.

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

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Abstract

Purpose: : Microarray analysis has demonstrated marked alteration of the retinal transcriptome during progressive retinal degeneration in the AY9944-induced rat model of Smith-Lemli-Opitz syndrome (SLOS), a disease involving defective cholesterol biosynthesis. One of the up-regulated genes was complement component C3, a key player in both the "classical" and "alternative" immune system pathways. Here, we evaluated retinal C3 expression in SLOS rats fed a cholesterol-free vs. high (2%)-cholesterol diet, and also localized C3 in normal and SLOS rat retinas.

Methods: : The SLOS model was generated by treating Sprague-Dawley rats with AY9944, a cholesterol pathway inhibitor, as previously described (Arch. Ophthalmol. 122:1190, 2004); untreated age-matched rats served as controls. Retinas were harvested at 2-3 months; total RNA and protein were isolated by TRIzol® extraction. Rat-specific C3 primers were used for qRT-PCR. Western blot analysis was performed on equal amounts of retinal protein, probing with anti-rat C3 polyclonal antibody; immunoreactive bands were quantified using a StormTM Imager. Indirect immunofluorescence localization of C3, as well as Iba1 (microglia/macrophage marker), was performed on sections from treated and control retinas.

Results: : qRT-PCR and Western analysis validated the up-regulation of C3 mRNA and protein expression in SLOS rat retinas, vs. controls. Feeding SLOS rats a high-cholesterol diet significantly decreased the levels of C3 transcript and protein in retinas, vs. those on a normal diet. C3 immunoreactivity was localized to RPE/choroid and retinal endothelial cells; while no differences in C3 immunoreactivity were noted, Iba1-positive cells were found in the photoreceptor layer of treated, but not control, retinas.

Conclusions: : Retinal degeneration in the SLOS rat model appears to involve recruitment of the immune system, via up-regulation of complement C3 and microglia/macrophage migration. Feeding a high-cholesterol diet (the standard of care for SLOS management) suppresses C3 up-regulation. Thus, immunomodulation may be an important factor in the pathophysiology and clinical management of SLOS.

Keywords: retinal degenerations: cell biology • immunomodulation/immunoregulation • microglia 
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