Fibulin-5 enhances extracellular matrix proteins production through integrin signaling pathway in human dermal fibroblasts: A potential application of four-leaf clover extract for well-aging

Summary: Abstract Body: Fibulin-5 is generally known as a structural protein involved in the formation of elastic fibers in various tissues including skin. Additionally, fibulin-5 is considered as a signaling molecule regulating cell proliferation, angiogenesis, and tumorigenesis in endothelial cells. However, little is known about its signaling potential in skin, particularly in human dermal fibroblasts. We investigated the effects of recombinant fibulin-5 on the production of the three major extracellular matrix (ECM) proteins namely elastin, collagen I, and collagen IV in normal human dermal fibroblasts under normal physiological conditions. Since fibulin-5 mediates integrin signaling, we also investigated the impact of a potent integrin inhibitor, Cilengitide, on fibulin-5-induced collagen I production. The protein levels of elastin, collagen I, and collagen IV were measured by ELISA techniques following the manufacturer instructions. Fibulin-5 was found to stimulate the synthesis and release of elastin, collagen I and collagen IV in the medium of cultured fibroblasts in a concentration-dependent manner. To further elucidate the mechanism, we incubated the fibroblasts with fibulin-5 in the presence or absence of different concentrations of Cilengitide for various time intervals (24, 48, 72 hrs), followed by the measurement of collagen I. Cilengitide dose- and time-dependently inhibited the fibulin-5-induced production of collagen I. The overall data suggests that fibulin-5-integrin signaling pathway is necessary for ECM components production. Interestingly, a natural extract derived from the leaves of the four-leaf clover (Trifolium repens) was identified as a potent stimulator of fibulin-5 production in human dermal fibroblasts. Therefore, by increasing the production of collagen I & IV, and elastin via fibulin-5, the four-leaf clover extract could hold a great potential as a cosmeceutical ingredient for well-aging applications. Kazal Boron Biswas¹, Yuka Kawai¹, Masakazu Hashimoto¹, Kiyotaka Tanaka¹, Arunasiri Iddamalgoda¹, Kotaro Sakamoto¹ 1. Research and Development, Ichimaru Pharcos Co. Ltd, Motosu, Gifu, Japan. Translational Studies: Cell and Molecular Biology