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Sharon A. McClellan, Yunfan Zhang, Elizabeth A. Berger, Norbert Wolf, Linda D. Hazlett; The Role of HIF-1α in Pseudomonas aeruginosa Keratitis. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5818.
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HIF-1α regulates vascular endothelial growth factor (VEGF), a presumed mediator of angiogenesis. However, its role in corneal disease resolution, as seen in BALB/c (resistant) mice after infection with Pseudomonas (P.) aeruginosa has not been explored and is the purpose of current studies.
HIF-1α was silenced in BALB/c mice by subconjunctival and topical delivery of siRNA for HIF-1α and mice were infected with P. aeruginosa. Controls were similarly treated, but using a scrambled siRNA. Disease was graded by clinical score and photographed with a slit lamp. Real time RT-PCR, immunohistochemistry, and ELISA were used to test angiogenic molecules and cytokines.
HIF-1α knockdown vs control treatment resulted in worsened corneal disease and reduced vascularity in the peripheral cornea. ELISA revealed that VEGF-A protein levels were similar between the two groups. In contrast, in the HIF-1α knockdown vs scrambled control, VEGF-R1 protein levels were decreased significantly at 1 day postinfection (p.i.), and were reduced, but not significant at 5 days p.i. VEGF-R2 protein levels were significantly (3 fold) reduced at 5 days p.i. in siHIF-1α compared to scrambled controls. For cytokines, no effects were observed at 5 days p.i. in mRNA levels of IL-1β, MIP-2, TNF-α or IL-6. However, mRNA levels of IL-18 (pro-inflammatory) were significantly elevated, while SIGIRR (anti-inflammatory), required for resistance in BALB/c mice, was significantly reduced in silenced vs scrambled control treated mice.
Silencing HIF-1α leads to decreased VEGF-R2, less vascularity, increased levels of IL-18, and reduced levels of SIGIRR, resulting in enhanced disease in resistant mice.
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