Dill Extract Preserves Dermal Elastic Fiber Network and Functionality: Implication of Elafin.

INTRODUCTION: Elastic skin fibers lose their mechanical properties during aging due to enzymatic degradation, lack of maturation, or posttranslational modifications. Dill extract has been observed to increase elastin protein expression and maturation in a 3D skin model, to improve mechanical properties of the skin, to increase elastin protein expression in vascular smooth muscle cells, to preserve aortic elastic lamella, and to prevent glycation. OBJECTIVE: The aim of the study was to highlight dill actions on elastin fibers during aging thanks to elastase digestion model and the underlying mechanism. METHODS: In this study, elastic fibers produced by dermal fibroblasts in 2D culture model were injured by elastase, and we observed the action of dill extract on elastic network by elastin immunofluorescence. Then action of dill extract was examined on mice skin by injuring elastin fibers by intradermal injection of elastase. Then elastin fibers were observed by second harmonic generation microscopy, and their functionality was evaluated by oscillatory shear stress tests. In order to understand mechanism by which dill acted on elastin fibers, enzymatic tests and real-time qPCR on cultured fibroblasts were performed. RESULTS: We evidence in vitro that dill extract is able to prevent elastin from elastase digestion. And we confirm in vivo that dill extract treatment prevents elastase digestion, allowing preservation of the cutaneous elastic network in mice and preservation of the cutaneous elastic properties. Although dill extract does not directly inhibit elastase activity, our results show that dill extract treatment increases mRNA expression of the endogenous inhibitor of elastase, elafin. CONCLUSION: Dill extract can thus be used to counteract the negative effects of elastase on the cutaneous elastic fiber network through modulation of PI3 gene expression.

Aging is associated with impaired triggering of TRPV3-mediated cutaneous vasodilation: a crucial process for local heat exposure.

Sensing temperature is vitally important to adapt our body to environmental changes. Local warm detection is required to initiate regulation of cutaneous blood flow, which is part of the peripheral thermoregulatory mechanisms, and thus avoid damage to surrounding tissues. The mechanisms mediating cutaneous vasodilation during local heat stress are impaired with aging. However, the impact of aging on the ability of the skin to detect subtle thermal changes is unknown. Among heat-activated cation channels, transient receptor potential vanilloid 3 (TRPV3) is a thermo-sensor predominantly expressed on keratinocytes and involved in local vascular thermoregulatory mechanisms of the skin in young mice. In the present study, using a murine in vivo model of local heat exposure of the skin, we showed that heat-induced vasodilation was reduced in old mice associated with reduced expression of TRPV3 channels. We also found a decrease in expression and activity of TRPV3 channel, as well as reduced TRPV3-dependent adenosine tri-phosphate release in human primary keratinocytes from old donors. This study shows that aging alters the epidermal TRPV3 channels, which might delay the detection of changes in skin temperature, thereby limiting the mechanisms triggered for local vascular thermoregulation in the old skin.

Skin Cell and Tissue Responses to Cross-Linked Hyaluronic Acid in Low-Grade Inflammatory Conditions.

Hyaluronic acid (HA), used in a variety of medical applications, is associated in rare instances to long-term adverse effects. Although the aetiology of these events is unknown, a number of hypotheses have been proposed, including low molecular weight of HA (LMW-HA) in the filler products. We hypothesized that cross-linked HA and its degradation products, in a low-grade inflammatory microenvironment, could impact immune responses that could affect cell behaviours in the dermis. Using two different cross-linking technologies VYC-15L and HYC-24L+, and their hyaluronidase-induced degradation products, we observed for nondegraded HA, VYC-15L and HYC-24L+, a moderate and transient increase in IL-1ß, TNF-α in M1 macrophages under low-grade inflammatory conditions. Endothelial cells and fibroblasts were preconditioned using inflammatory medium produced by M1 macrophages. 24 h after LMW-HA fragments and HA stimulation, no cytokine was released in these preconditioned cells. To further characterize HA responses, we used a novel in vivo murine model exhibiting a systemic low-grade inflammatory phenotype. The intradermal injection of VYC-15L and its degradation products induced an inflammation and cell infiltration into the skin that was more pronounced than those by HYC-24L+. This acute cutaneous inflammation was likely due to mechanical effects due to filler injection and tissue integration rather than its biological effects on inflammation. VYC-15L and its degradation product potentiated microvascular response to acetylcholine in the presence of a low-grade inflammation. The different responses with 2D cell models and mouse model using the two tested cross-linking HA technologies showed the importance to use integrative complex model to better understand the effects of HA products according to inflammatory state.

Neurovascular Response to Pressure in Patients With Diabetic Foot Ulcer.

Diabetic foot ulcer (DFU) is a problem worldwide, and prevention is crucial. We hypothesized that the inability of the skin to respond to pressure is involved in DFU pathogenesis and could be an important predictive factor to take into account. We included 29 patients with DFU and 30 patients with type 2 diabetes without DFU. Neuropathy and skin blood flow at rest were assessed in response to acetylcholine, sodium nitroprusside, local heating (42°C), and to nonnoxious locally applied pressure. Results were compared with those obtained from 10 healthy age-matched control subjects. Vasodilatation in response to pressure was significantly impaired in both groups with diabetes compared with healthy subjects. The vasodilator capacity to pressure was significantly lower in patients with DFU compared with those without DFU, despite the absence of significant difference in cutaneous pressure perception threshold and vascular reactivity to acetylcholine, sodium nitroprusside, and heat. This pronounced alteration of neurovascular response to pressure in patients with DFU is a good marker of skin vulnerability and could be used to better predict individuals at risk.

Altered blood rheology and impaired pressure-induced cutaneous vasodilation in a mouse model of combined type 2 diabetes and sickle cell trait.

OBJECTIVE: Type 2 diabetes (T2D)-related vascular dysfunction and hemorheological abnormalities could possibly be amplified by sickle cell trait (SCT). These alterations could potentially increase the risk of vascular complications in individuals with combined T2D and SCT. Therefore, this study used a mouse model to determine whether vascular function and blood rheology were more severely altered in combined T2D and SCT than in T2D or SCT alone. METHODS: Townes transgenic mice with or without SCT received a 12-week high fat high sucrose or standard diet to create models of combined T2D-SCT, T2D, SCT, and controls. Pressure-induced vasodilation (PIV) and sodium nitroprusside (SNP)-mediated vasodilation in-vivo, and hemorheological parameters were measured. RESULTS: No significant differences in blood viscosity, hematocrit, erythrocyte deformability, or PIV were observed between the control and T2D mice, or the control and SCT mice. However, blood viscosity, erythrocyte deformability, and PIV were significantly altered in the T2D-SCT mice compared to the control mice. There were no differences in SNP response between the groups. CONCLUSIONS: Although neither T2D nor SCT alone had significant effects on blood rheology parameters or vascular function, combined T2D-SCT mice had significantly altered blood rheology and significantly impaired vascular function.

Cutaneous and renal vasodilatory response to local pressure application: A comparative study in mice.

BACKGROUND AND AIM: We have reported a novel relationship involving mechanical stimulation and vasodilation in rodent and human skin, referred to as pressure-induced vasodilation (PIV). It is unknown whether this mechanism exists in kidney and reflects the microcirculation in deep organs. Therefore, we compared the skin and kidney PIV to determine whether their changes were similar. METHODS: In anesthetized mice fed a normal salt-diet, laser Doppler flux (LDF) signals were measured when an increase in local pressure was applied to the surface of the head skin with the rate of 2.2Pa/s (1mmHg/min) and to the left kidney with a rate of 4.4Pa/s (2mmHg/min). The mechanism underlying renal PIV was also investigated. The skin and kidney PIV were also compared during salt load (4% NaCl diet). RESULTS: The kidney had higher baseline LDF and vascular conductance compared to those of the skin. Pressure application increased the LDF in the kidney as well as in the skin with a comparable maximal magnitude (about 25% from baseline value), despite different kinetics of PIV evolution. As we previously reported in the skin, the kidney PIV response was mediated by the activation of transient receptor potential vanilloid type 1 channels, the release of calcitonin gene-related peptide, and the participation of prostaglandins and nitric oxide. In the absence of hypertension, high salt intake abolished the cutaneous PIV response and markedly impaired the renal one. CONCLUSION: PIV response in the mouse kidney results from a neuro-vascular interaction. Despite some differences between the skin and the kidney PIV, the similarities in their response and signaling mechanisms suggest that the cutaneous microcirculation could reflect, in part, the microcirculation of the renal cortex.

Disruption of TRPV3 Impairs Heat-Evoked Vasodilation and Thermoregulation: A Critical Role of CGRP.

Sensing environmental temperature is a key factor allowing individuals to maintain thermal homeostasis via thermoregulatory mechanisms, including changes to skin blood flow. Among transient receptor potential channels, transient receptor potential vanilloid 3 (TRPV3) is a heat-activated cation channel highly expressed in keratinocytes. However, the role of TRPV3 in triggering heat-evoked cutaneous vasodilation is unknown. Using a murine in vivo model of local acute environmental heat exposure in the skin, we show that TRPV3 is involved in the local thermoregulatory control of skin blood flow by initiating the release of calcitonin gene-related peptide and nitric oxide in response to local heating of the skin. In addition to their contribution in local heat-evoked vasodilation, TRPV3, calcitonin gene-related peptide, and nitric oxide also contribute to internal body temperature stability during passive whole-body heating. This study provides in vivo demonstration of the role of TRPV3 as a strong modulator of cutaneous vascular thermoregulatory mechanisms.

Intradermal injection of human adipose-derived stem cells accelerates skin wound healing in nude mice.

BACKGROUND: The use of stem cells from adipose tissue or adipose-derived stem cells (ASCs) in regenerative medicine could be an interesting alternative to bone marrow stem cells because they are easily accessible and available in large quantities. The aim of this study was to evaluate the potential effect of ASCs on the healing of 12 mm diameter-excisional wounds (around 110 mm(2)) in nude mice. METHODS: Thirty nude mice underwent surgery to create one 12-mm excisional wound per mouse (spontaneous healing, n = 6; Cytocare® 532, n = 12; ASCs, n = 12). The Galiano wound model was chosen to avoid shrinkage and thus slow the spontaneous healing (SH) of mouse skin, making it closer to the physiology of human skin healing. Transparent dressings were used to enable daily healing time measurements to be taken. Immunohistochemistry, histological and blood perfusion analysis were carried out on the healed skin. RESULTS: The in vivo results showed the effectiveness of using ASCs on reducing the time needed for complete healing to 21.2 days for SH, 17.4 days for vehicle alone (Cytocare® 532) and 14.6 days with the addition of ASCs (p < 0.001). Moreover, cutaneous perfusion of the healed wound was significantly improved in ASC-treated mice compared to SH group, as shown by laser Doppler flowmetry and the quantitation of blood vessels using immunohistochemistry of αsmooth muscle actin. CONCLUSIONS: The tolerance and efficacy of cryopreserved ASCs to accelerate the complete closure of the wound by increasing the maturation of the skin and its blood perfusion, shows their therapeutic benefit in the wound healing context.