ARMS2 interference leads to decrease of proinflammatory mediators

Age-related macular degeneration (AMD) is a major cause of irreversible blindness among elderly people in developed countries. Many studies suggested that age-related maculopathy susceptibility 2 (ARMS2) is the second major susceptibility gene for AMD. Increasing evidence was found recently that inflammatory processes and oxidative stress may contribute to the pathogenesis of AMD. Meanwhile, the mechanisms underlying the contributions of ARMS2 to the pathogenesis of AMD remain unclear. The purpose of the current study was to elucidate the relationship between the ARMS2 gene and proinflammatory mediators, for further assessment of the associated biologic effects.

siRNA was used to knock down ARMS2 mRNA, and Western blotting and reverse real-time PCR were used to detect the effect of siRNA on the expression of ARMS2 in ARPE-19 cells. The expressions of C3, C5, IL-6, IL-8, and TNF-α after si-RNA knockdown were evaluated by SYBR Green I real-time PCR and ELISA.

Transcription accumulative indexes (TAI = 2^{−delta delta CT}) of ARMS2 by real-time PCR revealed that the transfection rate in the positive control group was 72.0 ± 2.07 % (P < 0.01). The ratio of absorbance values (by Western blotting) of AMRS2 to β-actin was 0.85 ± 0.122, 0.87 ± 0.143, and 0.61 ± 0.240 in the blank control group, scrambled ARMS2-siRNA group, and ARMS2-siRNA group respectively (F = 42.5, P < 0.01). The secreted protein levels of C3, C5, IL-6, IL-8, and TNF-α were found by ELISA to be reduced by 34.24 ± 1.81 %, 37.15 ± 2.02 %, 35.11 ± 1.75 %, 30.11 ± 2.19 %, and 34.33 ± 2.18 % respectively, in the siRNA-ARMS2 group (P < 0.05). Compared with the blank control group, reduced TAI of C3, C5, IL-6, IL-8, and TNF-α were detected by real-time PCR in the ARMS2-siRNA group.

This study produced evidence supporting the notion that the ARMS2 risk allele for AMD is linked directly or indirectly to proinflammatory mediators. More importantly, our data indicate that the change in ARMS2 may affect C3, C5, IL-6, IL-8, and TNF-α levels, and this may be one of the mechanisms of AMD development.