UVA-mediated down-regulation of MMP-2 and MT1-MMP coincides with impaired angiogenic phenotype of human dermal endothelial cells

Rhus coriaria L. Fruit Extract Prevents UV-A-Induced Genotoxicity and Oxidative Injury in Human Microvascular Endothelial Cells

Rhus coriaria L. (sumac) is a small plant widely diffused in the Mediterranean region. Its fruit are often consumed as a spice but are also present in traditional medicine of several countries. Recently, interest in this plant has increased and many scientific works reported its beneficial effects including antioxidant and anti-inflammatory properties. Plant extracts can be successfully used against ultraviolet rays, which are able to reach and damage the human skin; however, sumac extracts were never applied to this usage. Thus, in this study, we used a macerated ethanol extract of Rhus coriaria L. dried fruit (mERC) to demonstrate its preventive role against the damage induced by ultraviolet-A rays (UV-A) on microvascular endothelial cells (HMEC-1). In vitro effects of the extract pre-treatment and UV-A exposure were evaluated in detail. The antioxidant capacity was assessed by reactive oxygen species (ROS) formation and cellular antioxidant activity measurement. Genoprotective effects of mERC were investigated as well. Our findings indicate that the extract acts as a cell cycle inhibitor or apoptosis inducer, according to the level of damage. The present work provides new insights into the usage of Rhus coriaria extracts against skin injuries.

Ultraviolet-irradiated endothelial cells secrete stem cell factor and induce epidermal pigmentation

Ultraviolet (UV)-associated hyperpigmented skins are characterized with increased vasculature underlying pigmentation, suggestive of the possible biological role of endothelial cells in the regulation of skin pigmentation during UV irradiation. In this study, we showed that UV-irradiated endothelial cells significantly increased the pigmentation of melanocytes through epithelial-mesenchymal crosstalk. The stimulatory effect of endothelial cells was further demonstrated using ex vivo human skin. RNA sequence analysis and enzyme-linked immunosorbent assay showed that endothelial cells secrete more stem cell factor (SCF) upon UV irradiation than non-irradiated cells. The increased pigmentation elicited by endothelial cells was abrogated following inhibition of SCF/c-KIT signaling. Together these results suggest that endothelial cells are activated upon UV exposure to release melanogenic factors such as SCF, which contributes to the development of skin hyperpigmentation during chronic sun exposure.

Effects of matrix metalloproteinases on the fate of mesenchymal stem cells

Mesenchymal stem cells (MSCs) have great potential as a source of cells for cell-based therapy because of their ability for self-renewal and differentiation into functional cells. Moreover, matrix metalloproteinases (MMPs) have a critical role in the differentiation of MSCs into different lineages. MSCs also interact with exogenous MMPs at their surface, and regulate the pericellular localization of MMP activities. The fate of MSCs is regulated by specific MMPs associated with a key cell lineage. Recent reports suggest the integration of MMPs in the differentiation, angiogenesis, proliferation, and migration of MSCs. These interactions are not fully understood and warrant further investigation, especially for their application as therapeutic tools to treat different diseases. Therefore, overexpression of a single MMP or tissue-specific inhibitor of metalloproteinase in MSCs may promote transdifferentiation into a specific cell lineage, which can be used for the treatment of some diseases. In this review, we critically discuss the identification of various MMPs and the signaling pathways that affect the differentiation, migration, angiogenesis, and proliferation of MSCs.

Renal Therapeutic Angiogenesis Using a Bioengineered Polymer-Stabilized Vascular Endothelial Growth Factor Construct

Renovascular disease (RVD) induces renal microvascular (MV) rarefaction that drives progressive kidney injury. In previous studies, we showed that renal vascular endothelial growth factor (VEGF) therapy attenuated MV damage, but did not resolve renal injury at practical clinical doses. To increase the bioavailability of VEGF, we developed a biopolymer-stabilized elastin-like polypeptide (ELP)-VEGF fusion protein and determined its in vivo potential for therapeutic renal angiogenesis in RVD using an established swine model of chronic RVD. We measured single-kidney blood flow (RBF) and GFR and established the degree of renal damage after 6 weeks of RVD. Pigs then received a single stenotic kidney infusion of ELP-VEGF (100 μg/kg), a matching concentration of unconjugated VEGF (18.65 μg/kg), ELP alone (100 μg/kg), or placebo. Analysis of organ distribution showed high renal binding of ELP-VEGF 4 hours after stenotic kidney infusion. Therapeutic efficacy was determined 4 weeks after infusion. ELP-VEGF therapy improved renal protein expression attenuated in RVD, restoring expression levels of VEGF, VEGF receptor Flk-1, and downstream angiogenic mediators, including phosphorylated Akt and angiopoietin-1 and -2. This effect was accompanied by restored MV density, attenuated fibrogenic activity, and improvements in RBF and GFR greater than those observed with placebo, ELP alone, or unconjugated VEGF. In summary, we demonstrated the feasibility of a novel therapy to curtail renal injury. Recovery of the stenotic kidney in RVD after ELP-VEGF therapy may be driven by restoration of renal angiogenic signaling and attenuated fibrogenic activity, which ameliorates MV rarefaction and improves renal function.

UVA irradiation induced heme oxygenase-1: a novel phototherapy for morphea

Long wave UVA radiation (340-400 nm) causes detrimental as well as beneficial effects on human skin. Studies of human skin fibroblasts irradiated with UVA demonstrate increased expression of both antifibrotic heme oxygenase-1 (HO-1) and matrix metalloproteinase 1 (MMP-1). The use of UVA-induced MMP-1 is well-studied in treating skin fibrotic conditions such as localized scleroderma, now called morphea. However, the role that UVA-induced HO-1 plays in phototherapy of morphea has not been characterized. In the present manuscript, we have illustrated and reviewed the biological function of HO-1 and the use of UVA1 wavebands (340-400 nm) for phototherapy; the potential use of HO-1 induction in UVA therapy of morphea is also discussed.

Chk1 and Hsp90 cooperatively regulate phosphorylation of endothelial nitric oxide synthase at serine 1179

The effects of DNA damage on NO production have not been completely elucidated. Using ultraviolet (UV) irradiation as a DNA-damaging agent, we studied its effect on NO production in bovine aortic endothelial cells (BAEC). UV irradiation acutely increased NO production, the phosphorylation of endothelial NO synthase (eNOS) at serine 1179, and eNOS activity. No alterations in eNOS expression nor phosphorylation at eNOS Thr(497) or eNOS Ser(116) were found. SB218078, a checkpoint kinase 1 (Chk1) inhibitor, inhibited UV-irradiation-stimulated eNOS-Ser(1179) phosphorylation and NO production. Similarly, ectopic expression of small interference RNA for Chk1 or a dominant-negative Chk1 repressed the UV-irradiation stimulatory effect, whereas wild-type Chk1 increased basal eNOS-Ser(1179) phosphorylation. Purified Chk1 directly phosphorylated eNOS Ser(1179) in vitro. Confocal microscopy and coimmunoprecipitation studies revealed a colocalization of eNOS and Chk1. In basal BAEC, heat shock protein 90 (Hsp90) predominantly interacted with Chk1. This interaction, which decreased significantly in response to UV irradiation, was accompanied by increased interaction of Hsp90 with eNOS. The Hsp90 inhibitor geldanamycin attenuated UV-irradiation-stimulated eNOS-Ser(1179) phosphorylation by dissociating Hsp90 from eNOS. UV irradiation and geldanamycin did not alter the interaction between eNOS and Chk1. Overall, this is the first study demonstrating that Chk1 directly phosphorylates eNOS Ser(1179) in response to UV irradiation, which is dependent on Hsp90 interaction.