Critical Role of TNF-alpha-Induced Macrophage VEGF and iNOS Production in the Experimental Corneal Neovascularization

Department of Ophthalmology, the First Affiliated Hospital of Soochow University, Suzhou City, China.
Investigative ophthalmology & visual science (Impact Factor: 3.4). 05/2012; 53(7):3516-26. DOI: 10.1167/iovs.10-5548
Source: PubMed


We evaluated the roles of tumor necrosis factor (TNF)-α in alkali-induced corneal neovascularization (CNV).
CNV was induced by alkali injury and compared in wild-type (WT) BALB/c mice, and TNF receptor 1-deficient (TNF-Rp55 KO) counterparts, or in mice treated with TNF-α antagonist and recombinant TNF-α. Angiogenic factor expression and leukocyte accumulation in the early phase after injury were quantified by real-time PCR and immunohistochemical analysis, respectively.
Alkali injury augmented the intraocular mRNA expression of TNF-α and its receptor, together with a transient macrophage and neutrophil infiltration. Compared to WT mice, TNF-Rp55 KO mice exhibited reduced CNV. Intraocular F4/80-positive macrophages and Ly-6G-positive neutrophils infiltration did not change in KO mice compared to WT mice after the injury. Alkali injury induced a massively increased intraocular mRNA expression of angiogenic factors, including vascular endothelial growth factor (VEGF), inducible nitric oxide synthase (iNOS), interleukin (IL)-6, E-selectin, and intercellular adhesion molecule (ICAM)-1 in WT mice, whereas these increments were retarded severely in KO mice. Immunofluorescence analysis demonstrated that F4/80-positive cells expressed VEGF and iNOS. Moreover, TNF-α enhanced VEGF and iNOS expression by peritoneal macrophage from WT, but not KO mice. Topical application of TNF-α antagonist reduced CNV, while topical application of recombinant TNF-α enhanced it.
TNF-Rp55-KO mice exhibited impaired alkali-induced CNV through reduced intracorneal infiltrating macrophage VEGF and iNOS expression.

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    • "Interestingly, Zakaria et al. (2012) have shown from studies of human tears that inflammatory cytokines such as IL-6, IL-8 are positively correlated with the presence of corneal neovascularization. Inhibition of early recruitment or maturation of macrophages by anti-angiogenic agents may also play an important role in later corneal neovascularization (Cursiefen et al., 2004; Lu et al., 2012; Sakurai et al., 2003; Sunderkötter et al., 1994). As expected, VEGF-A expression was suppressed in the treatment groups, alongside with IL-6, a widespread inflammatory cytokine that has been shown to have bidirectional associations with VEGF-A (Tartour et al., 2011; Zakaria et al 2012). "
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