Abstract
Collagen tripeptide (CTP) is defined as a functional food material derived from collagenase digests of type I collagen and contains a high concentration of tripeptides with a Gly-X-Y sequence. CTP has several biological effects, including the acceleration of fracture healing, ameliorating osteoarthritis, and improving dryness and photoaging of the skin. Recently, an antiatherosclerotic effect of CTP has been reported, although its molecular mechanism is yet to be determined. In this study, we examined the effects of CTP on primary cultured human aortic endothelial cells (HAECs) under oxidative stress, because oxidative endothelial dysfunction is a trigger of atherosclerosis. DNA microarray and RT-qPCR analyses showed that CTP treatment recovered the downregulated expression of several genes, including the interleukin-3 receptor subunit alpha (IL3RA), which were suppressed by reactive oxygen species (ROS) treatment in HAECs. Furthermore, IL3RA knockdown significantly decreased the viability of HAECs compared with control cells. RT-qPCR analysis also showed that solute carrier 15 family peptide transporters, which are involved in CTP absorption into cells, were expressed in HAECs at levels more than comparable to those of a CTP-responsive human osteoblastic cell line. These results indicated that CTP exerts a protective effect for HAECs, at least in part, by regulating the recovery of ROS-induced transcriptional repression.
Highlights
Collagen tripeptide (CTP) is a functional food material prepared from porcine type I collagen by digestion [1]
To identify the mechanisms underlying the protective effects of CTP on atherosclerosis, this study examined the effects of CTP on global gene expression changes in human aortic endothelial cells (ECs) (HAECs) under oxidative stress and showed that CTP exerts a protective effect on human aortic endothelial cells (HAECs) through the recovery of reactive oxygen species (ROS)-induced transcriptional repression
We examined the effects of CTP on the overall gene expression in HAECs under oxidative stress with H2 O2 [18]
Summary
Collagen tripeptide (CTP) is a functional food material prepared from porcine type I collagen by digestion [1]. The tripeptide component of CTP is selectively absorbed into connective tissue according to whole-body autoradiography with the administration of a single dose of tritium-labeled Gly-Pro-Hyp [4]. Tsuruoka et al demonstrated that the oral administration of CTP by rats with femur fractures accelerated fracture healing by promoting type I collagen gene expression [2], whereas another study reported that periodic knee injections of CTP delayed cartilage degeneration in an experimental osteoarthritis rabbit model [5]. Oral administration of CTP improved skin barrier function in ultraviolet B-exposed hairless mice [7] and dryness or pruritus of dry skin in humans [8,9]. The molecular mechanisms underlying the protective effects of CTP for atherosclerosis are yet to be determined
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