78 research outputs found

    Toll-Like Receptors in Wound Healing: Location, Accessibility, and Timing

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    Toll-like receptors (TLRs) are considered to be the first responders in the defense against invading pathogens. TLR engagement by ligands triggers inflammatory responses in injury and trauma, and thus can impair or contribute to the healing process, depending on TLRs' expression pattern, cellular localization, signaling, and deployment of inflammatory responses. Understanding these attributes could improve therapeutic strategies for treating chronic wounds

    Resveratrol Prevents High Fluence Red Light-Emitting Diode Reactive Oxygen Species-Mediated Photoinhibition of Human Skin Fibroblast Migration.

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    BackgroundSkin fibrosis is a significant medical problem that leads to a functional, aesthetic, and psychosocial impact on quality-of-life. Light-emitting diode-generated 633-nm red light (LED-RL) is part of the visible light spectrum that is not known to cause DNA damage and is considered a safe, non-invasive, inexpensive, and portable potential alternative to ultraviolet phototherapy that may change the treatment paradigm of fibrotic skin disease.ObjectiveThe goal of our study was to investigate the how reactive oxygen species (ROS) free radicals generated by high fluence LED-RL inhibit the migration of skin fibroblasts, the main cell type involved in skin fibrosis. Fibroblast migration speed is increased in skin fibrosis, and we studied cellular migration speed of cultured human skin fibroblasts as a surrogate measure of high fluence LED-RL effect on fibroblast function. To ascertain the inhibitory role of LED-RL generated ROS on migration speed, we hypothesized that resveratrol, a potent antioxidant, could prevent the photoinhibitory effects of high fluence LED-RL on fibroblast migration speed.MethodsHigh fluence LED-RL generated ROS were measured by flow cytometry analysis using dihydrorhodamine (DHR). For purposes of comparison, we assessed the effects of ROS generated by hydrogen peroxide (H2O2) on fibroblast migration speed and the ability of resveratrol, a well known antioxidant, to prevent LED-RL and H2O2 generated ROS-associated changes in fibroblast migration speed. To determine whether resveratrol could prevent the high fluence LED-RL ROS-mediated photoinhibition of human skin fibroblast migration, treated cells were incubated with resveratrol at concentrations of 0.0001% and 0.001% for 24 hours, irradiated with high fluences LED-RL of 480, 640, and 800 J/cm2.ResultsHigh fluence LED-RL increases intracellular fibroblast ROS and decreases fibroblast migration speed. LED-RL at 480, 640 and 800 J/cm2 increased ROS levels to 132.8%, 151.0%, and 158.4% relative to matched controls, respectively. These LED-RL associated increases in ROS were prevented by pretreating cells with 0.0001% or 0.001% resveratrol. Next, we quantified the effect of hydrogen peroxide (H2O2)-associated ROS on fibroblast migration speed, and found that while H2O2-associated ROS significantly decreased relative fibroblast migration speed, pretreatment with 0.0001% or 0.001% resveratrol significantly prevented the decreases in migration speed. Furthermore, we found that LED-RL at 480, 640 and 800 J/cm2 decreased fibroblast migration speed to 83.0%, 74.4%, and 68.6% relative to matched controls, respectively. We hypothesized that these decreases in fibroblast migration speed were due to associated increases in ROS generation. Pretreatment with 0.0001% and 0.001% resveratrol prevented the LED-RL associated decreases in migration speed.ConclusionHigh fluence LED-RL increases ROS and is associated with decreased fibroblast migration speed. We provide mechanistic support that the decreased migration speed associated with high fluence LED-RL is mediated by ROS, by demonstrating that resveratrol prevents high fluence LED-RL associated migration speed change. These data lend support to an increasing scientific body of evidence that high fluence LED-RL has anti-fibrotic properties. We hypothesize that our findings may result in a greater understanding of the fundamental mechanisms underlying visible light interaction with skin and we anticipate clinicians and other researchers may utilize these pathways for patient benefit

    A Concise Review of the Conflicting Roles of Dopamine-1 versus Dopamine-2 Receptors in Wound Healing.

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    Catecholamines play an important regulatory role in cutaneous wound healing. The exact role of dopamine in human epidermis has yet to be fully elucidated. Current published evidence describes its differential effects on two separate families of G protein coupled receptors: D1-like and D2-like dopamine receptors. Dopamine may enhance angiogenesis and wound healing through its action on dopamine D1 receptors, while impairing wound healing when activating D2 receptors. This review summarizes the evidence for the role of dopamine in wound healing and describes potential mechanisms behind its action on D1 versus D2-like receptors in the skin

    β-Adrenergic Receptor Activation Inhibits Keratinocyte Migration via a Cyclic Adenosine Monophosphate-independent Mechanism

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    There is increasing evidence that G-protein-coupled receptors cross-talk with growth factor receptor-mediated signal transduction in a variety of cell types. We have investigated mechanisms by which the activation of β-adrenergic receptors, classically GTP-binding proteins coupled receptors, influence the migration of cultured human keratinocytes. We found that iso-proterenol, a β-adrenergic receptor-selective agonist, inhibited cell migration stimulated by either epidermal growth factor, or extracellular Ca2+ in a concentration-dependent manner. This was prevented by pretreatment of the cells with the β-adrenergic receptor-selective antagonist timolol. Interestingly, isoproterenol, at a concentration of 1 nM, did not measurably increase intracellular cyclic adenosine monophosphate concentrations yet inhibited cell migration by 50%. To test further if isoproterenol's actions were mediated via activation of adenylyl cyclase, two inhibitors of its activity, 2′5′-dideoxyadenosine and SQ22536, were used. Both compounds significantly diminished iso-proterenol-induced increases in intracellular cyclic adenosine monophosphate concentrations but did not attenuate isoproterenol-induced inhibition of cell migration. Also, forskolin (1 μM) markedly increased intracellular cyclic adenosine monophosphate concentrations but did not significantly inhibit cell migration. As mitogen-activated protein kinases are known to signal growth factor-stimulated cell migration, we examined whether β-adrenergic receptor-mediated inhibition of keratinocyte migration might occur via inactivation of mitogen-activated protein kinases. We found that isoproterenol inhibited phosphorylation of extracellular signal-regulated kinase mitogen-activated protein kinase in a concentration-dependent manner but had no effect on the phosphorylation of the stress mitogen-activated protein kinases c-jun N-terminal kinase and stress-activated protein kinase-2. Neither forskolin nor a membrane permeable cyclic adenosine monophosphate analog inhibited phosphorylation of any of these mitogen-activated protein kinases. These findings suggest that β-adrenergic receptor-induced inhibition of keratinocyte migration is mediated through inhibition of the extracellular signal-regulated kinase mitogen-activated protein kinase signaling in a cyclic adenosine monophosphate-independent manner

    Plasminogen Activator in Differentiating Mouse Keratinocytes

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    The activity of the serine protease plasminogen activator (PA) was measured in cell lysates from primary mouse keratinocyte cultures as well as from a number of established mouse keratinocyte lines. Enzyme activity was generally higher in the transformed lines than in the primary cultures; however, among the lines tested, those that expressed the highest degree of morphologic differentiation had the highest levels of cell-associated PA. In both the normal (primary) and transformed (established) keratinocyte cultures, PA activity increased when cultures reached confluence and morphologic evidence of differentiation was noted. The highest specific activity of the enzyme was found in cells shed from differentiating cultures, which consisted predominantly of detergent-resistant cornified envelopes. As the cultures differentiated and these cells were shed from the culture surface, the total cell-associated PA activity of the culture decreased accordingly. In both the normal and transformed keratinocyte cultures, peak PA activity occurred at a time when DNA synthesis was declining. These findings indicate that as keratinocytes differentiate, their intracellular levels of PA increase. The modulation of this endogenous keratinocyte enzyme may play an important, although as yet undefined, role in the normal maturation and terminal differentiation of these cells

    Deferoxamine: potential novel topical therapeutic for chronic wounds

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136734/1/bjd14956.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136734/2/bjd14956_am.pd

    Power-line frequency electromagnetic fields do not induce changes in phosphorylation, localization, or expression of the 27-kilodalton heat shock protein in human keratinocytes.

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    The linkage of the exposure to the power-line frequency (50-60 Hz) electromagnetic fields (EMF) with human cancers remains controversial after more than 10 years of study. The in vitro studies on the adverse effects of EMF on human cells have not yielded a clear conclusion. In this study, we investigated whether power-line frequency EMF could act as an environmental insult to invoke stress responses in human keratinocytes using the 27-kDa heat shock protein (HSP27) as a stress marker. After exposure to 1 gauss (100 micro T) EMF from 20 min to 24 hr, the isoform pattern of HSP27 in keratinocytes remained unchanged, suggesting that EMF did not induce the phosphorylation of this stress protein. EMF exposure also failed to induce the translocation of HSP27 from the cytoplasm to the nucleus. Moreover, EMF exposure did not increase the abundance of HSP27 in keratinocytes. In addition, we found no evidence that EMF exposure enhanced the level of the 70-kDa heat shock protein (HSP70) in breast or leukemia cells as reported previously. Therefore, in this study we did not detect any of a number of stress responses in human keratinocytes exposed to power-line frequency EMF
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