Ferulic acid, a phenolic phytochemical, inhibits UVB-induced matrix metalloproteinases in mouse skin via posttranslational mechanisms.

Matrix metalloproteinases MMP-2 and -9 are known to be overexpressed in ultraviolet B (UVB)-irradiated skin tissues and contribute to the acceleration of photoaging and the development of skin cancer. But the specific molecular mechanisms that can control or interfere with the expression and regulation of these MMP-2 and -9 activities in skin are not clearly understood. The aim of the present study was to analyze the suppressive effects of ferulic acid (FA), an abundant phenolic compound present in various dietary and medicinal plants, on UVB radiation-induced MMP-2 and -9 activities in mouse skin. For attenuation of chronic UVB irradiation damage to skin, inhibition of MMP-2 and -9 protein expression was detected using immunohistochemistry analysis. However, the in situ suppressive effects of FA did not interfere with the transcription or translation of MMP-2 and -9, suggesting that its action could be mediated via the proteasome pathway. Histological analyses showed that FA attenuates the degradation of collagen fibers, abnormal accumulation of elastic fibers and epidermal hyperplasia induced by UVB, demonstrating the functional and physiological relevance of FA effects in UVB-irradiated skin tissues. Together, our findings provide a novel and increased insight into the in vivo action of FA and suggest a possible clinical application in skin pathophysiological conditions associated with overexpression of MMP-2 and -9.

Genomics and proteomics of immune modulatory effects of a butanol fraction of echinacea purpurea in human dendritic cells.

BACKGROUND: Echinacea spp. extracts and the derived phytocompounds have been shown to induce specific immune cell activities and are popularly used as food supplements or nutraceuticals for immuno-modulatory functions. Dendritic cells (DCs), the most potent antigen presenting cells, play an important role in both innate and adaptive immunities. In this study, we investigated the specific and differential gene expression in human immature DCs (iDCs) in response to treatment with a butanol fraction containing defined bioactive phytocompounds extracted from stems and leaves of Echinacea purpurea, that we denoted [BF/S+L/Ep]. RESULTS: Affymetrix DNA microarray results showed significant up regulation of specific genes for cytokines (IL-8, IL-1beta, and IL-18) and chemokines (CXCL 2, CCL 5, and CCL 2) within 4 h after [BF/S+L/Ep] treatment of iDCs. Bioinformatics analysis of genes expressed in [BF/S+L/Ep]-treated DCs revealed a key-signaling network involving a number of immune-modulatory molecules leading to the activation of a downstream molecule, adenylate cyclase 8. Proteomic analysis showed increased expression of antioxidant and cytoskeletal proteins after treatment with [BF/S+L/Ep] and cichoric acid. CONCLUSION: This study provides information on candidate target molecules and molecular signaling mechanisms for future systematic research into the immune-modulatory activities of an important traditional medicinal herb and its derived phytocompounds.

Immunomodulatory effects of phytocompounds characterized by in vivo transgenic human GM-CSF promoter activity in skin tissues.

To investigate the immunomodulatory activities of phytocompounds for potential therapeutics, we devised an in vivo, transgenic, human cytokine gene promoter assay using defined epidermal skin cells as test tissue. Test compounds were topically applied to mouse skin before or after gene gun transfection, using a cytokine gene promoter-driven luciferase reporter. Croton oil, an inflammation inducer, induced transgenic GM-CSF and TNF-alpha promoter activities in skin epidermis 6-fold and 3.4-fold, respectively; however, it produced a less than 1.5-fold and 1.7-fold change in IL-1beta and IL-18 promoter activity, respectively. The phytocompound shikonin drastically inhibited inducible GM-CSF promoter activity. However, a fraction of Dioscorea batatas extract significantly increased the GM-CSF promoter activity in normal and inflamed skin. Shikonin suppressed the transcriptional activity of GM-CSF promoter by inhibiting the binding of TFIID protein complex (TBP) to TATA box. Our results demonstrate that this in vivo transgenic promoter activity assay system is cytokine gene-specific, and highly responsive to pro-inflammatory or anti-inflammatory stimuli. Currently it is difficult to profile the expression and cross-talk of various types of cytokines in vivo. This investigation has established a bona fide in vivo, in situ, immune tissue system for research into cytokine response to inflammation.

Caffeic acid suppresses UVB radiation-induced expression of interleukin-10 and activation of mitogen-activated protein kinases in mouse.

Ultraviolet B (UVB) radiation present in sunlight causes sustained immune suppression, photocarcinogenesis and photoaging in humans. Interleukin-10 (IL-10) plays a critical role in UVB-induced immune suppression by inhibiting cell-mediated immune reactions. Mitogen-activated protein kinases (MAPKs) have been implicated in UVB-induced skin carcinogenesis. Caffeic acid (CA), a phenolic acid present in many dietary plants has been shown to confer antioxidant, anti-inflammatory and anticancer activities. In this study, we evaluated the protective effects of CA against UVB radiation-induced IL-10 expression and phosphorylation of MAPKs in mouse skin. An in vivo transgenic IL-10 promoter-luciferase-reporter gene based assay revealed that CA inhibits the transcriptional activation of UVB-induced IL-10 promoter. This was further confirmed by significant inhibition of UVB radiation-induced IL-10 mRNA expression and protein production by CA in mouse skin. Contact hypersensitivity assay showed that CA could attenuate the local immune suppression induced by UVB radiation against a hapten, dinitrofluorobenzene. Our results indicated that CA might inhibit IL-10 production by interfering with an early step, prostaglandin E2 synthesis, in the activation of UVB-induced immune suppressive cytokine cascade. CA also significantly inhibited the UVB-induced activation of MAPK signal transduction pathways, such as extracellular signal-regulated protein kinase, c-Jun N-terminal protein kinase and p38 mitogen-activated protein kinase, and the downstream transcription factors activator protein-1 and nuclear factor-kappa B. The findings of our study suggest that CA may confer significant protection against UVB-induced immune suppression and photocarcinogenesis in vivo and provide the possible underlying molecular basis for its actions. Therefore, CA may have therapeutic potential as a topical protective agent against the deleterious effects of UVB radiation.

Shikonins, phytocompounds from Lithospermum erythrorhizon, inhibit the transcriptional activation of human tumor necrosis factor alpha promoter in vivo.

Tumor necrosis factor alpha (TNF-alpha) contributes to the pathogenesis of both acute and chronic inflammatory diseases and has been a target for the development of new anti-inflammatory drugs. Shikonins, the naphthoquinone pigments present in the root tissues of Lithospermum erythrorhizon Sieb. et Zucc. (Boraginaceae), have been reported to exert anti-inflammatory effects both in vitro and in vivo. In this study, we evaluated the effects of shikonin and its derivatives on the transcriptional activation of human TNF-alpha promoter in a gene gun-transfected mouse skin system by using a luciferase reporter gene assay. The crude plant extract of L. erythrorhizon as well as derived individual compounds shikonin, isobutyryl shikonin, acetyl shikonin, dimethylacryl shikonin and isovaleryl shikonin showed significant dose-dependent inhibition of TNF-alpha promoter activation. Among the tested compounds, shikonin and isobutyryl shikonin exhibited the highest inhibition of TNF-alpha promoter activation and also showed significant suppression of transgenic human TNF-alpha mRNA expression and protein production. We demonstrated that shikonin-inhibitory response was retained in the core TNF-alpha promoter region containing the TATA box and a 48-bp downstream sequence relative to the transcription start site. Further our results indicated that shikonin suppressed the basal transcription and activator-regulated transcription of TNF-alpha by inhibiting the binding of transcription factor IID protein complex (TATA box-binding protein) to TATA box. These in vivo results suggest that shikonins inhibit the transcriptional activation of the human TNF-alpha promoter through interference with the basal transcription machinery. Thus, shikonins may have clinical potential as anti-inflammatory therapeutics.