Abstract
ObjectiveThis study was aimed to evaluate the anti-photoaging effects of baicalin on Ultraviolet B (UVB)-induced photoaging in the dorsal skin of hairless mice and premature senescence in human dermal fibroblasts.MethodsWe established in vivo and in vitro photoaging models by repeated exposures to UVB irradiation. By HE staining, masson staining, immunohistostaing and real-time RT-PCR, we analyzed epidermal thickness, collagen expression and the mRNA and protein levels of type I collagen, type III collagen, interstitial collagenase (MMP-1 and MMP-3) in UVB exposed dorsal mice skin. The aging condition in human dermal fibroblasts was determined by senescence-associated β-galactosidase (SA-β-gal) staining. Cell viability was determined using the Cell Counting Kit-8 (CCK-8). The G1 phase cell growth arrest was analyzed by flow cytometry. The senescence-related protein levels of p16INK-4a, p21WAF-1, and p53 and protein levels of phosphorylated histone H2AX were estimated by Western blotting.ResultsTopically application of baicalin treatment reduced UVB-induced epidermal thickening of mouse skin and also result in an increase in the production of collagen I and III, and a decrease in the expression of MMP-1 and MMP-3. Compared with the UVB-irradiated group, we found that the irradiated fibroblasts additionally treated with baicalin demonstrated a decrease in the expression of SA-β-gal, a increase in the cell viability, a decrease in the G1 phase cell proportion, a downregulation in the level of senescence-associated and γ-H2AX proteins. However, Baicalin had no difference in the normal fibroblasts without UVB irradiation and long-term Baicalin incubation of UVB-SIPS fibroblasts gave no effects on the cell proliferation.ConclusionsTaken together, these results suggest that baicalin significantly antagonizes photoaging induced by UVB in vivo and in vitro, indicating the potential of baicalin application for anti-photoaging treatment.
Highlights
Skin aging involves intrinsic and extrinsic processes
The degradation of type I and III fibrillar collagens is initiated by matrix metalloproteinases-1 (MMP-1) and MMP-3 respectively, which belongs to the matrix metalloproteinases (MMPs), a large family of zinc-dependent endo-proteases with a broad range of substrate specificities and the capacity of degrading all extracellular matrix proteins
Baicalin suppresses Ultraviolet B (UVB)-induced epidermal thickening in mouse skin Because epidermal thickening is a major biomarker of photoaging [18], we evaluated the effect of baicalin on UVB
Summary
Skin aging involves intrinsic and extrinsic processes. Environmental factors, primarily ultraviolet (UV) light, cause extrinsic skin aging. There are various etiologies of skin photoaging, common points include less dermal type I and III collagen expression [1]. Type I collagen is characterized by thick fiber that confer stiffness and resistance to perform a crucial function in maintaining the structure of dermis. Whereas collagen type III is characterized by thin fiber that present the resiliency of skin. Fibroblasts exposed to UV reduce collagen by both promoting its degradation and interfering with its production [3]. Fibroblasts could be photoaged by UVB in vitro and in vivo and these experimental models were proven to be applicable in various skin aging studies [5], [6], [7], [8]
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