Koo H, et al. J Korean Med Sci. 2012 Dec;27(12):1574-1579. http://dx.doi.org/10.3346/jkms.2012.27.12.1574

Angiogenin (ANG) is reportedly multifunctional, with roles in angiogenesis and autoimmune diseases. This protein is involved in the innate immune system and has been implicated in several inflammatory diseases. Although ANG may be involved in the anti-inflammatory response, there is no evidence that it has direct anti-inflammatory effects. In this study we sought to determine whether ANG has an anti-inflammatory effect in human corneal fibroblasts (HCFs) exposed to media containing tumor necrosis factor-alpha (TNF-α). We found that ANG reduced the mRNA expression of interleukin-1 beta (IL-1β), -6, -8 and TNF-αreceptors (TNFR) 1 and 2. In contrast, ANG increased the mRNA expression of IL-4 and -10. Protein levels of TANK-binding kinase 1 (TBK1) were reduced by ANG in HCFs treated with TNF-α. Moreover, ANG diminished the expression of IL-6 and -8 and monocyte chemotactic protein- (MCP-) 1. The protein expression of nuclear factor-κB (NF-κB) was downregulated by ANG treatment. These findings suggest that ANG suppressed the TNF-α-induced inflammatory response in HCFs through inhibition of TBK1-mediated NF-κB nuclear translocation. These novel results are likely to play a significant role in the selection of immune-mediated inflammatory therapeutic targets and may shed light on the pathogenesis of immune-mediated inflammatory diseases.

Purpose.: Stromal cell-derived factor 1 (SDF-1) and its interaction with chemokine receptor 4 (CXCR4) have been noted for participating in the wound healing process, and may paradoxically develop hypertrophic scarring. With viewing pterygia as a product of exaggerated wound formation, we evaluated the effects of SDF-1 and CXCR4 on determining the severity of pterygia. Methods.: Human pterygial fibroblasts were cultured from excised tissues. Then, expression levels of SDF-1 and CXCR4 were assessed at both the mRNA and protein levels and analyzed with respect to the severity (grade T1 to T3) of pterygia. Expression patterns of SDF-1 and CXCR4 in pterygium tissues were evaluated by immunohistochemistry. Additionally, to investigate the SDF-1–induced myofibroblast transformation of pterygial fibroblasts, the correlation between SDF-1 and α-smooth muscle actin (α-SMA) expression levels was evaluated. Furthermore, α-SMA levels in pterygial fibroblasts were determined before and after knockdown of SDF-1 and blockade of CXCR4 by AMD3100. Results.: Stromal cell-derived factor 1 and CXCR4 were expressed in identical areas in severe pterygium tissues (grade T3) and CXCR4-immunopositive cells were concentrated at perivascular regions. Stromal cell-derived factor 1 levels in cultured pterygial fibroblasts correlated positively with the severity of pterygia. Stromal cell-derived factor 1 levels had a significant, positive correlation with α-SMA levels in pterygial fibroblasts. Furthermore, each knockdown of SDF-1 expression and blockade of SDF-1/CXCR4 signaling in severe pterygia significantly reduced α-SMA levels. Conclusions.: Stromal cell-derived factor 1 expression is upregulated in severe pterygia, and SDF-1 and CXCR4 interaction may contribute to the myofibroblast transformation, which can be possibly restored through the downregulation of the SDF-1/CXCR4 axis.

Purpose.: Angiogenin (ANG) originally was identified as an angiogenic tumor factor, and recently its biologic activity is extended to stimulating cell proliferation. With viewing pterygium as a tumorigenic mimicry, we investigated ANG profiles within pterygia. Methods.: Expression levels of ANG were assessed using immunohistochemistry, RT-PCR, and Western blotting through examination of excised specimens and cultured fibroblasts from pterygium and conjunctiva tissues. The phenotypes of pterygia were classified by four grading indices, including recurrence, growth activity, pterygium body translucency (T), and vascularity (V). Then, ANG levels in pterygia were differentiated according to phenotypes of pterygia, and were compared to levels in normal conjunctiva. Furthermore, to investigate ANG-related acquisition of proliferative potency in fibroblasts, the correlation between ANG and α-smooth muscle actin (α-SMA) levels was evaluated. Results.: In immunohistochemistry, ANG was expressed strongly in pterygium stroma with all four severe phenotypes (with recurrence, active growth, thick body [T3], and marked vascularization [V3]), especially at the perivascular areas. There was a trend toward higher ANG expression in cultured fibroblasts of pterygia with severe phenotype, compared to those without and with normal conjunctiva. However, pterygium body V had a weak association with ANG expression. Additionally, Western blotting revealed a significant positive correlation between the expression levels of α-SMA and ANG. Conclusions.: Overexpression of ANG in pterygium body fibroblasts might be involved in active pterygium growth with thick pterygium body formation and increased risk of recurrence. A possible mechanism for this finding includes ANG-related transition of pterygium fibroblasts to the proliferative state.