Stress-mediated increases in systemic and local epinephrine impair skin wound healing: potential new indication for beta blockers

Host-Microbiome Crosstalk in Chronic Wound Healing

The pathogenesis of chronic wounds (CW) involves a multifaceted interplay of biochemical, immunological, hematological, and microbiological interactions. Biofilm development is a significant virulence trait which enhances microbial survival and pathogenicity and has various implications on the development and management of CW. Biofilms induce a prolonged suboptimal inflammation in the wound microenvironment, associated with delayed healing. The composition of wound fluid (WF) adds more complexity to the subject, with proven pro-inflammatory properties and an intricate crosstalk among cytokines, chemokines, microRNAs, proteases, growth factors, and ECM components. One approach to achieve information on the mechanisms of disease progression and therapeutic response is the use of multiple high-throughput 'OMIC' modalities (genomic, proteomic, lipidomic, metabolomic assays), facilitating the discovery of potential biomarkers for wound healing, which may represent a breakthrough in this field and a major help in addressing delayed wound healing. In this review article, we aim to summarize the current progress achieved in host-microbiome crosstalk in the spectrum of CW healing and highlight future innovative strategies to boost the host immune response against infections, focusing on the interaction between pathogens and their hosts (for instance, by harnessing microorganisms like probiotics), which may serve as the prospective advancement of vaccines and treatments against infections.

A New Ex Vivo Human Skin Burn Model

Currently, most burn models for preclinical testing are on animals. For obvious ethical, anatomical, and physiological reasons, these models could be replaced with optimized ex vivo systems. The creation of a burn model on human skin using a pulsed dye laser could represent a relevant model for preclinical research. Six samples of excess human abdominal skin were obtained within one hour after surgery. Burn injuries were induced on small samples of cleaned skin using a pulsed dye laser on skin samples, at varying fluences, pulse numbers and illumination duration. In total, 70 burn injuries were performed on skin ex vivo before being histologically and dermato-pathologically analyzed. Irradiated burned skin samples were classified with a specified code representing burn degrees. Then, a selection of samples was inspected after 14 and 21 days to assess their capacity to heal spontaneously and re-epithelize. We determined the parameters of a pulsed dye laser inducing first, second, and third degree burns on human skin and with fixed parameters, especially superficial and deep second degree burns. After 21 days with the ex vivo model, neo-epidermis was formed. Our results showed that this simple, rapid, user-independent process creates reproducible and uniform burns of different, predictable degrees that are close to clinical reality. Human skin ex vivo models can be an alternative to and complete animal experimentation, particularly for preclinical large screening. This model could be used to foster the testing of new treatments on standardized degrees of burn injuries and thus improve therapeutic strategies.

Macrophage β2-AR activation amplifies inflammation in wound healing by upregulating Trem1 via the cAMP/PKA/CREB pathway

BACKGROUND

Inflammation is an important part of the wound healing process. The stress hormone epinephrine has been demonstrated to modulate the inflammatory response via its interaction with β2-adrenergic receptor (β2-AR). However, the precise molecular mechanism through which β2-AR exerts its influence on inflammation during the wound healing process remains an unresolved question.

METHODS

Transcriptome datasets of wound and macrophages from the GEO database were reanalyzed using bioinformatics. The role of β2-AR in wound healing was explored by a mouse hind paw plantar wound model, and histological analyses were performed to assess wound healing. In vivo and in vitro assays were performed to elucidate the role of β2-AR on the inflammatory response. Triggering receptor expressed on myeloid cells 1 (Trem1) was knocked down with siRNA on RAW cells and western blot and qPCR assays were performed.

RESULTS

Trem1 was upregulated within 24 h of wounding, and macrophage β2-AR activation also upregulated Trem1. In vivo experiments demonstrated that β2-AR agonists impaired wound healing, accompanied by upregulation of Trem1 and activation of cAMP/PKA/CREB pathway, as well as by a high level of pro-inflammatory cytokine production. In vitro experiments showed that macrophage β2-AR activation amplified LPS-induced inflammation, and knockdown of Trem1 reversed this effect. Using activator and inhibitor of cAMP, macrophage β2-AR activation was confirmed to upregulate Trem1 via the cAMP/PKA/CREB pathway.

CONCLUSION

Our study found that β2-AR agonists increase Trem1 expression in wounds, accompanied by amplification of the inflammatory response, impairing wound healing. β2-AR activation in RAW cells induces Trem1 upregulation via the cAMP/PKA/CREB pathway and amplifies LPS-induced inflammatory responses.

Mechanism and application of β-adrenoceptor blockers in soft tissue wound healing

Soft tissue damage stimulates sympathetic nerves to release large amounts of catecholamine hormones which bind to β-adrenergic receptors (β-ARs) on the cell membrane surface. It activates the downstream effector molecules and impairs soft tissue wound healing. β-blockers specifically inhibit β-ARs activation in acute/chronic skin lesions and ulcerative hemangiomas. They also accelerate soft tissue wound healing by shortening the duration of inflammation, speeding keratinocyte migration and reepithelialization, promoting wound contraction and angiogenesis, and inhibiting bacterial virulence effects. In addition, β-blockers shorten wound healing periods in patients with severe thermal damage by reducing the hypermetabolic response. While β-blockers promote/inhibit corneal epithelial cell regeneration and restores limbal stem/progenitor cells function, it could well accelerate/delay corneal wound healing. Given these meaningful effects, a growing number of studies are focused on examining the efficacy and safety of β-blockers in soft tissue wound repair, including acute and chronic wounds, severe thermal damage, ulcerated infantile hemangioma, corneal wounds, and other soft tissue disorders. However, an intensive investigation on their acting mechanisms is imperatively needed. The purpose of this article is to summerize the roles of β-blockers in soft tissue wound healing and explore their clinical applications.

Repeated stress-induced crosstalk between the sympathetic nervous system and mast cells contributes to delayed cutaneous wound healing in mice

The study identifies a link between the neuroimmune interaction and the impairment of wound healing induced by repeated stress. Stress increased mast cell mobilization and degranulation, levels of IL-10, and sympathetic reinnervation in mouse wounds. In contrast to mast cells, macrophage infiltration into wounds was significantly delayed in stressed mice. Chemical sympathectomy and the blockade of mast cell degranulation reversed the effect of stress on skin wound healing in vivo. In vitro, high epinephrine levels stimulated mast cell degranulation and IL-10 release. In conclusion, catecholamines released by the sympathetic nervous system stimulate mast cells to secrete anti-inflammatory cytokines that impair inflammatory cell mobilization, leading to a delay in the resolution of wound healing under stress conditions.

The orchestra of human bacteriome by hormones

Human microbiome interact reciprocally with the host. Recent findings showed the capability of microorganisms to response towards host signaling molecules, such as hormones. Studies confirmed the complex response of bacteria in response to hormones exposure. These hormones impact many aspects on bacteria, such as the growth, metabolism, and virulence. The effects of each hormone seem to be species-specific. The most studied hormones are cathecolamines also known as stress hormones that consists of epinephrine, norepinephrine and dopamine. These hormones affect the growth of bacteria either inhibit or enhance by acting like a siderophore. Epinephrine and norepinephrine have also been reported to activate QseBC, a quorum sensing in Gram-negative bacteria and eventually enhances the virulence of pathogens. Other hormones were also reported to play a role in shaping human microbiome composition and affect their behavior. Considering the complex response of bacteria on hormones, it highlights the necessity to take the impact of hormones on bacteria into account in studying human health in relation to human microbiome.

Immunomodulatory effect of dopamine in human keratinocytes and macrophages under chronical bisphenol-A exposure conditions

Dopamine is a key neurotransmitter that links the nervous and the immune system. Bisphenol A (BPA) is an endocrine disruptor with a wide distribution in the environment that is used in the manufacturing of plastic products. Evidence shows that BPA can interfere with the central dopaminergic transmission; however, there are no previous reports of this effect outside the central nervous system. Thus, the aim of this work was to investigate the in vitro mechanisms of action involved in the response to dopamine in both human keratinocyte and macrophage cell lines chronically exposed to BPA. Dopamine modulates cytokine secretion and NF-κB expression in BPA-treated HaCaT keratinocytes, without modifying these parameters in BPA-treated THP-1 macrophages. In addition, dopamine increases MMP activity in both BPA-treated cell lines, although it decreases keratinocytes migration. We suggest the immunomodulatory effect of dopamine might be different in keratinocytes and macrophages under chronical BPA exposure conditions. These findings revealed for the first time the in vitro immunomodulatory effect of dopamine in the presence of BPA at peripheral level.

microRNA regulation of skin pigmentation in golden-back mutant of crucian carp from a rice-fish integrated farming system

BACKGROUND

MicroRNAs (miRNAs) are endogenous small non-coding RNAs (21-25 nucleotides) that act as essential components of several biological processes. Golden-back crucian carp (GBCrC, Carassius auratus) is a naturally mutant species of carp that has two distinct body skin color types (golden and greenish-grey), making it an excellent model for research on the genetic basis of pigmentation. Here, we performed small RNA (sRNA) analysis on the two different skin colors via Illumina sequencing.

RESULTS

A total of 679 known miRNAs and 254 novel miRNAs were identified, of which 32 were detected as miRNAs with significant differential expression (DEMs). 23,577 genes were projected to be the targets of 32 DEMs, primarily those involved in melanogenesis, adrenergic signaling in cardiomyocytes, MAPK signaling pathway and wnt signaling pathway by functional enrichment. Furthermore, we built an interaction module of mRNAs, proteins and miRNAs based on 10 up-regulated and 13 down-regulated miRNAs in golden skin. In addition to transcriptional destabilization and translational suppression, we discovered that miRNAs and their target genes were expressed in the same trend at both the transcriptional and translational levels. Finally, we discovered that miR-196d could be indirectly implicated in regulating melanocyte synthesis and motility in the skin by targeting to myh7 (myosin-7) gene through the luciferase reporter assay, antagomir silencing in vivo and qRT-PCR techniques.

CONCLUSIONS

Our study gives a systematic examination of the miRNA profiles expressed in the skin of GBCrC, assisting in the comprehension of the intricate molecular regulation of body color polymorphism and providing insights for C. auratus breeding research.

Sympathetic System in Wound Healing: Multistage Control in Normal and Diabetic Skin

In this review, we discuss sympathetic regulation in normal and diabetic wound healing. Experimental denervation studies have confirmed that sympathetic nerve endings in skin have an important and complex role in wound healing. Vasoconstrictor neurons secrete norepinephrine (NE) and neuropeptide Y (NPY). Both mediators decrease blood flow and interact with inflammatory cells and keratinocytes. NE acts in an ambiguous way depending on receptor type. Beta2-adrenoceptors could be activated near sympathetic endings; they suppress inflammation and re-epithelialization. Alpha1- and alpha2-adrenoceptors induce inflammation and activate keratinocytes. Sudomotor neurons secrete acetylcholine (ACh) and vasoactive intestinal peptide (VIP). Both induce vasodilatation, angiogenesis, inflammation, keratinocytes proliferation and migration. In healthy skin, all effects are important for successful healing. In treatment of diabetic ulcers, mediator balance could be shifted in different ways. Beta2-adrenoceptors blockade and nicotinic ACh receptors activation are the most promising directions in treatment of diabetic ulcers with neuropathy, but they require further research.

Targeted inhibition of osteoclastogenesis reveals the pathogenesis and therapeutics of bone loss under sympathetic neurostress

Sympathetic cues via the adrenergic signaling critically regulate bone homeostasis and contribute to neurostress-induced bone loss, but the mechanisms and therapeutics remain incompletely elucidated. Here, we reveal an osteoclastogenesis-centered functionally important osteopenic pathogenesis under sympatho-adrenergic activation with characterized microRNA response and efficient therapeutics. We discovered that osteoclastic miR-21 was tightly regulated by sympatho-adrenergic cues downstream the β2-adrenergic receptor (β₂AR) signaling, critically modulated osteoclastogenesis in vivo by inhibiting programmed cell death 4 (Pdcd4), and mediated detrimental effects of both isoproterenol (ISO) and chronic variable stress (CVS) on bone. Intriguingly, without affecting osteoblastic bone formation, bone protection against ISO and CVS was sufficiently achieved by a (D-Asp₈)-lipid nanoparticle-mediated targeted inhibition of osteoclastic miR-21 or by clinically relevant drugs to suppress osteoclastogenesis. Collectively, these results unravel a previously underdetermined molecular and functional paradigm that osteoclastogenesis crucially contributes to sympatho-adrenergic regulation of bone and establish multiple targeted therapeutic strategies to counteract osteopenias under stresses.

Neurobiology, Stem Cell Biology, and Immunology: An Emerging Triad for Understanding Tissue Homeostasis and Repair

The peripheral nervous system (PNS) endows animals with the remarkable ability to sense and respond to a dynamic world. Emerging evidence shows the PNS also participates in tissue homeostasis and repair by integrating local changes with organismal and environmental changes. Here, we provide an in-depth summary of findings delineating the diverse roles of peripheral nerves in modulating stem cell behaviors and immune responses under steady-state conditions and in response to injury and duress, with a specific focus on the skin and the hematopoietic system. These examples showcase how elucidating neuro-stem cell and neuro-immune cell interactions provides a conceptual framework that connects tissue biology and local immunity with systemic bodily changes to meet varying demands. They also demonstrate how changes in these interactions can manifest in stress, aging, cancer, and inflammation, as well as how these findings can be harnessed to guide the development of new therapeutics.

Adrenergic receptor signaling induced by Klf15, a regulator of regeneration enhancer, promotes kidney reconstruction

Despite the recent discovery of tissue regeneration enhancers in highly regenerative animals, upstream and downstream genetic programs connected by these enhancers still remain unclear. Here, we performed a genome-wide analysis of enhancers and associated genes in regenerating nephric tubules of Xenopus laevis. Putative enhancers were identified using assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) and H3K27ac chromatin immunoprecipitation sequencing (ChIP-seq) analyses. Their target genes were predicted based on their proximity to enhancers on genomic DNA and consistency of their transcriptome profiles to ATAC-seq/ChIP-seq profiles of the enhancers. Motif enrichment analysis identified the central role of Krüppel-like factors (Klf) in the enhancer. Klf15, a member of the Klf family, directly binds enhancers and stimulates expression of regenerative genes, including adrenoreceptor alpha 1A (adra1a), whereas inhibition of Klf15 activity results in failure of nephric tubule regeneration. Moreover, pharmacological inhibition of Adra1a-signaling suppresses nephric tubule regeneration, while its activation promotes nephric tubule regeneration and restores organ size. These results indicate that Klf15-dependent adrenergic receptor signaling through regeneration enhancers plays a central role in the genetic network for kidney regeneration.

Signaling Pathways Associated with Chronic Wound Progression: A Systems Biology Approach

Previously we have shown that several oxidative stress-driven pathways in cutaneous chronic wounds are dysregulated in the first 48 h post-wounding. Here, we performed an RNASeq analysis of tissues collected up to day 20 after wounding, when we have determined full chronicity is established. Weighted Gene Correlation Network Analysis was performed in R segregating the genes into 14 modules. Genes in the modules significantly correlated (p < 0.05) to early and full chronicity were used for pathway analysis using pathfindR. In early chronicity, we observed enrichment of several pathways. Dysregulation of Ephrin/Eph signaling leads to growth cone collapse and impairs neuronal regeneration. Adra2b and Adra2a overexpression in early and full chronicity, respectively, decreased cAMP production and impaired re-epithelialization and granulation tissue formation. Several pathways involving a Smooth-muscle-actin (Acta1) were also enriched with Acta1 overexpression contributing to impaired angiogenesis. During full chronicity, the ‘JAK-STAT’ pathway was suppressed undermining host defenses against infection. Wnt signaling was also suppressed, impairing re-epithelialization and granulation tissue formation. Biomarkers of cancer such as overexpression of SDC1 and constitutive activation of ErbB2/HER2 were also identified. In conclusion, we show that during progression to full chronicity, numerous signaling pathways are dysregulated, including some related to carcinogenesis, suggesting that chronic wounds behave much like cancer. Experimental verification in vivo could identify candidates for treatment of chronic wounds.

The use of propranolol in adult burn patients: Safety and outcome influence

OBJECTIVES

This study investigated safety and effect of propranolol on adult patients with severe burn.

METHODS

A prospective study was conducted on 124 severely adult burn patients who were randomly divided into propranolol and non-propranolol group. Propranolol was given by nasogastric tube to achieve the target of lowering 15-20% of initial heart rate.

RESULTS

Average dose of propranolol was 1.9 ± 0.5 mg/kg/day ranging from 0.9 to 3.3 mg/kg/day and was not affected by burn extent and inhalation injury. Mean heart rate reduced by 21.2% during the 28 day period. Recorded adverse events included hypotension (11.9%), bradycardia (1.6%), hypoglycemia (17.7%) and total number of held events was 8 occurring in 7 (11.3%) patients. Serum levels of glucose, total protein, albumin, cholesterol and triglyceride at different times were not significantly different between the two groups. Significantly lower resting energy expenditure on the 7^th and 14^th day were seen in propranolol group (p < 0.05). After 3 weeks, liver size in the propranolol group did not change significantly from admission, while in the non-propranolol group, liver size increased significantly (p < 0.05). The complete healing time of partial-thickness burns and donor sites were significantly shorter in propranolol group (p < 0.01). Duration of ventilation, length of stay in intensive care unit and in hospital, number of operations, rate of multiple organ failure, and death were not different between the two groups (p > 0.05).

CONCLUSION

For severely burned adults, propranolol was safe and effective on reducing energy expenditure, limited hepatomegaly, and accelerated partial burn wound and donor site closure, but does not affect length of stay in ICU, hospitalization, complication ormortality rate.

Role of neurotransmitters in the regulation of cutaneous wound healing

Wound healing is a highly coordinated and dynamic process of tissue repair after injury. The global burden of disease associated with wounds, both acute and chronic, is a significantly rising health concern. Upon skin wounding, neurons have the ability to sense the disruption to mediate the release of neurotransmitters into the wound microenvironment. Serotonin that has long been recognised as a potential vasoconstrictor is now also being contemplated to play a role in re-epithelialisation of wounds. While the role of neuropeptides in stimulating diabetic wound healing is being increasingly emphasised, on the other hand, dopamine is being widely studied for its dual role in mediating both pro- and antiangiogenic effects at the site of the wounds. Similarly, epinephrine levels that are known to be elevated during stress is now recognised as a contributing factor towards delayed wound closure, thereby serving as an inhibitor of wound healing. Thus, each neurotransmitter regulates wound repair and their active regeneration in a typical way. Strengthening our understanding of the molecular pathways via which the neurotransmitter modulates the immune system to control wound healing can yield potential therapeutic measures. Further investigations regarding the safety, efficacy, and cost-effectiveness of these processes are a prerequisite for their possible translation into clinical trials.

The psychobiological links between chronic stress-related diseases, periodontal/peri-implant diseases, and wound healing

Chronic stress is a relevant disease to periodontal practice, encompassing 25%-28% of the US population (American Psychological Association 2015). While it is well established that chronic psychologic stress can have significant deleterious systemic effects, only in recent decades have we begun to explore the biochemical, microbial, and physiologic impacts of chronic stress diseases on oral tissues. Currently, chronic stress is classified as a "risk indicator" for periodontal disease. However, as the evidence in this field matures with additional clinically controlled trials, more homogeneous data collection methods, and a better grasp of the biologic underpinnings of stress-mediated dysbiosis, emerging evidence suggests that chronic stress and related diseases (depression, anxiety) may be significant contributing factors in periodontal/peri-implant disease progression and inconsistent wound healing following periodontal-related therapeutics. Ideal solutions for these patients include classification of the disease process and de-escalation of chronic stress conditions through coping strategies. This paper also summarizes periodontal/implant-related therapeutic approaches to ensure predictable results for this specific patient subpopulation.

Propranolol-loaded electrospun nanofibrous wound dressing: From fabrication and characterization to preliminary wound healing evaluation

OBJECTIVES

The wound healing potential of beta-blocker drugs such as propranolol (PNL) has recently attracted attention. To date, incorporation of PNL into electrospun nanofibrous wound dressing mats has not been tested as a novel topical drug delivery system. Presently, electrospun nanofibrous mats loaded with PNL were fabricated, and their physicochemical properties and wound healing activities were evaluated.

MATERIALS AND METHODS

Polyvinyl alcohol solutions containing 0, 2% or 4% (wt/vol) PNL were electrospun into mats, and the physicochemical properties and PNL release were evaluated. In vitro biocompatibility of selected PNL-loaded mats was tested in human foreskin fibroblasts and wound healing capability was evaluated in mouse skin wounds.

RESULTS

The 4% PNL mat had thin fibers (160 nm), convincing porosity (79.5%), and good hydrophilicity (swelling: 89.1%, water contact angle: 42.1°) with little degradability (14.2%). The release of PNL was not in bursts and was best explained by the Korsmeyer-Peppas equation (R2 = 0.96, n = 0.40), suggesting Fickian release. The viability of fibroblasts was 173% on day 5 of incubation with 4% PNL mats, indicating good mat biocompatibility. In vivo treatment for 14 days with 4% PNL mats resulted in wounds with a surface area of only 9% of the original wound area. These wounds had better histopathologic characteristics and were associated with less oxidative stress.

CONCLUSION

The wound dressing fabricated with 4% PNL showed good potential for wound healing because of a favorable drug release profile from the nanofiber scaffold, and can be considered eligible for further clinical research.

Alpha and beta adrenergic receptors modulate keratinocyte migration

Keratinocyte migration into skin wounds is the step of the healing process that correlates with the wound closure rate. Keratinocyte migration, and wound epithelialization are decreased when beta 2-adrenergic receptors (B2AR) are activated by 1 μM epinephrine/adrenaline, resulting in delayed wound healing in human and mouse skin. In the present study, we found paradoxically, that in a subset of keratinocyte strains exposure to low concentrations of epinephrine (0.1 nM) increased, rather than decreased, their migratory rate. We find that both the alpha- and the beta-adrenergic receptors are expressed in human keratinocytes, and expression of alpha-2 AR subtypes demonstrated for the first time. Therefore, we tested if the alpha-AR could be modulating the increased migratory response observed in these cell strains. By using specific inhibitors to alpha-AR, we demonstrated that blocking A2B-AR could reverse the rapid cell migration induced by the 0.1 nM epinephrine. Phosphorylation of ERK was elevated after 1-10 minutes of the low epinephrine treatment and the A2B-AR inhibitor blocked the ERK phosphorylation. The results suggest that both the A2B-AR and B2AR mediate keratinocyte migration, in which with a low level of epinephrine treatment, A2B-AR could alter the B2AR signals and regulate the migration rate.

The Ambivalent Role of Skin Microbiota and Adrenaline in Wound Healing and the Interplay between Them

After skin injury, wound healing sets into motion a dynamic process to repair and replace devitalized tissues. The healing process can be divided into four overlapping phases: hemostasis, inflammation, proliferation, and maturation. Skin microbiota has been reported to participate in orchestrating the wound healing both in negative and positive ways. Many studies reported that skin microbiota can impose negative and positive effects on the wound. Recent findings have shown that many bacterial species on human skin are able to convert aromatic amino acids into so-called trace amines (TAs) and convert corresponding precursors into dopamine and serotonin, which are all released into the environment. As a stress reaction, wounded epithelial cells release the hormone adrenaline (epinephrine), which activates the β2-adrenergic receptor (β2-AR), impairing the migration ability of keratinocytes and thus re-epithelization. This is where TAs come into play, as they act as antagonists of β2-AR and thus attenuate the effects of adrenaline. The result is that not only TAs but also TA-producing skin bacteria accelerate wound healing. Adrenergic receptors (ARs) play a key role in many physiological and disease-related processes and are expressed in numerous cell types. In this review, we describe the role of ARs in relation to wound healing in keratinocytes, immune cells, fibroblasts, and blood vessels and the possible role of the skin microbiota in wound healing.

The Role of the FOXO1/β2-AR/p-NF-κB p65 Pathway in the Development of Endometrial Stromal Cells in Pregnant Mice under Restraint Stress

Restraint stress causes various maternal diseases during pregnancy. β₂-Adrenergic receptor (β₂-AR) and Forkhead transcription factor class O 1 (FOXO1) are critical factors not only in stress, but also in reproduction. However, the role of FOXO1 in restraint stress, causing changes in the β₂-AR pathway in pregnant mice, has been unclear. The aim of this research was to investigate the β₂-AR pathway of restraint stress and its impact on the oxidative stress of the maternal uterus. In the study, maternal mice were treated with restraint stress by being restrained in a transparent and ventilated device before sacrifice on Pregnancy Day 5 (P5), Pregnancy Day 10 (P10), Pregnancy Day 15 (P15), and Pregnancy Day 20 (P20) as well as on Non-Pregnancy Day 5 (NP5). Restraint stress augmented blood corticosterone (CORT), norepinephrine (NE), and blood glucose levels, while oestradiol (E2) levels decreased. Moreover, restraint stress increased the mRNA levels of the FOXO family, β₂-AR, and even the protein levels of FOXO1 and β₂-AR in the uterus and ovaries. Furthermore, restraint stress increased uterine oxidative stress level. In vitro, the protein levels of FOXO1 were also obviously increased when β₂-AR was activated in endometrial stromal cells (ESCs). In addition, phosphorylated-nuclear factor kappa-B p65 (p-NF-κB p65) and its target genes decreased significantly when FOXO1 was inhibited. Overall, it can be said that the β₂-AR/FOXO1/p-NF-κB p65 pathway was activated when pregnant mice were under restraint stress. This study provides a scientific basis for the origin of psychological stress in pregnant women.

Repurposing Ophthalmologic Timolol for Dermatologic Use: Caveats and Historical Review of Adverse Events

Ophthalmic timolol solution is increasingly being repurposed as a topical therapeutic for a variety of dermatologic diseases, including pyogenic granulomas, infantile hemangiomas, and chronic wounds. There are no published guidelines or protocols for use in these indications in adults, and the dermatologic community may not be familiar with adverse events that have been extensively documented relating to its ophthalmic use. We review the evidence available relating to adverse events to topical timolol use to evaluate its safety in dermatologic applications and to alert clinicians to screening and monitoring that is needed when repurposing this drug for dermatologic use. The majority of serious adverse events associated with ophthalmic timolol were reported in the first 7 years of use, between 1978 and 1985, of which most common were cardiovascular and respiratory events, but also included 32 deaths. The available evidence suggests that ophthalmic timolol safety profiling may have been incomplete prior to widespread use. Recent clinical trials for dermatologic indications have focused on documenting efficacy and have not had rigorous monitoring for potential adverse events. Topical timolol may be safe and effective for the treatment of various dermatologic conditions in patients whose medical histories have been carefully reviewed for evidence of pre-existing cardiac or pulmonary disease and are monitored for potential adverse events. Despite the wide use of timolol in ophthalmologic practice, safe dermatologic repurposing requires recognition of the potential for facilitated systemic absorption though the skin and appreciation of its history of adverse events.

[Mechanisms of adrenergic β-antagonist for wounds and its application prospect in diabetic foot ulcers]

Objective

To review the research progress of adrenergic β-antagonists on wounds and diabetic chronic cutaneous ulcers healing in recent years, and to investigate its application prospect in diabetic foot ulcer (DFU).

Methods

The latest literature about the role of adrenergic β-antagonists in wounds and diabetic chronic cutaneous ulcers healing was extensively reviewed, and the mechanisms of adrenergic β-antagonists for wounds and its potential benefit for DFU were analyzed thoroughly.

Results

The adrenergic β-antagonists can accelerate the wound healing. The possible mechanisms include accelerating re-epithelialization, promoting angiogenesis, improving neuropathy, and regulating inflammation and growth factors, etc. At present clinical research data showed that the adrenergic β-antagonists may be an adjuvant treatment for diabetic chronic cutaneous ulcers.

Conclusion

Adrenergic β-antagonists maybe promote the healing of wounds and diabetic chronic cutaneous ulcers. However, more long-term follow-up and high-quality randomized control studies are needed to further verify their efficacy and safety for DFU.

A Rose Extract Protects the Skin against Stress Mediators: A Potential Role of Olfactory Receptors

Olfactory receptors (ORs) are expressed and active in various human tissues, including the skin. Although the sense of smell plays an important physiological role in the regulation of mood and stress, a link between olfactive compounds, ORs, and skin stress has yet to be established. This study aims to investigate the role of newly identified skin ORs and agonists in the modulation of skin stress. Screening for odorant molecules was done with cAMP functional assay to identify OR agonists. RT-qPCR and immunofluorescence microscopy were conducted to identify and quantify ORs in epidermal keratinocytes (NHEKs) and human skin explants, as well as to evaluate specific markers (G6PDH, loricrin, and γH2AX) of stress-induced skin alterations. A randomized double-blinded, split-face clinical study was performed on a panel of stressed women to measure the benefits of OR agonist treatment for skin. Three new ORs (OR10A6, OR2AG2, and OR11H4) were identified in skin. A specific Rose extract and its major constituent (phenylethyl alcohol) were found to activate these ORs. The extract composition was revealed by both GC/FID and GC/MS analyses simultaneously and showed the presence of 34 volatiles molecules. Moreover, epinephrine induces a skin stress response characterized by increased expression of G6PD, loricrin, and γH2AX biomarkers, and a decrease of OR expression. These effects were prevented in the presence of rose extract and its benefits were confirmed clinically by a decrease in the appearance of under-eye dark circles. Altogether, our findings suggest that ORs may represent a new, promising way to treat stress-associated skin disorders.

Characterization of a Topically Testable Model of Burn Injury on Human Skin Explants

Severe burn injuries remain a major health problem due to high rates of mortality, residual morbidity, and/or aesthetic damages. To find new therapies aimed at promoting a harmonious healing of skin burns, it is important to develop models which take into account the unique properties of the human skin. Based on previously described models of burn injury performed on human skin explants, we hypothesized that maintaining explants under constant tension forces would allow to more closely reproduce the pathophysiological processes of skin remodeling. We thus. Here, we set up and characterized an improved model of deep second-degree burn injury on ex vivo cultured human skin explants at air-liquid interface and maintained under conditions of constant tension forces. A spontaneous re-epithelialization of the lesion was observed 8 to 9 days post burn and was found to rely on the proliferation of basal keratinocytes at the wound edges. Collagen VII at the dermo-epidermal junction reformed along with the progression of re-epithelializatio and a synthesis of procollagen III was observed in the dermis at the wound site. These findings indicate that our model is suitable for the assessment of clinically-relevant therapies aimed at modulating the kinetics of re-epithelialization and/or the activation of fibroblasts following skin burn injuries. In this regard, we evaluated the use of a thermoreversible poloxamer hydrogel as a vehicle for topically-testable therapeutic molecules. Our data showed that, although useful for drug formulation, the p407/p188 poloxamer hydrogel induces a delay of skin re-epithelialization in humans skin explants submitted to experimental burn injury.

Catecholamines in the regulation of angiogenesis in cutaneous wound healing

Angiogenesis involves the formation of new blood vessels from preexisting ones, and it is an essential step during cutaneous wound healing, which supports cells at the wound site with nutrition and oxygen. Impaired angiogenesis in the wound tissues results in delayed wound closure and healing. Among the regulators of angiogenesis, the role of catecholamines (epinephrine, norepinephrine, and dopamine) is of interest due to their diverse roles in the process of wound healing. While both norepinephrine and epinephrine mostly inhibit the angiogenic process in cutaneous wounds, dopamine, the other member of the catecholamine family, has interesting and contradictory roles in the regulation of angiogenesis in the wound beds, depending on the type of dopamine receptor involved. The stimulation of dopamine D2 receptors negatively regulates the angiogenic process in normal dermal wounds and thereby delays healing, whereas the stimulation of dopamine D1 receptors promotes angiogenesis and expedites healing in diabetic wounds. Importantly, catecholamines also play important roles in other pathological conditions, and specific agonists and antagonists of catecholamines are available for the treatment of some disorders. Therefore, such drugs may be utilized for the management of angiogenesis to promote the healing of dermal wounds. This review provides a broad overview of the angiogenic process during cutaneous wound healing and the regulatory roles played by catecholamines during the process.

Combination product of dermal matrix, human mesenchymal stem cells, and timolol promotes diabetic wound healing in mice

Diabetic foot ulcers are a major health care concern with limited effective therapies. Mesenchymal stem cell (MSC)-based therapies are promising treatment options due to their beneficial effects of immunomodulation, angiogenesis, and other paracrine effects. We investigated whether a bioengineered scaffold device containing hypoxia-preconditioned, allogeneic human MSCs combined with the beta-adrenergic antagonist timolol could improve impaired wound healing in diabetic mice. Different iterations were tested to optimize the primary wound outcome, which was percent of wound epithelialization. MSC preconditioned in 1 μM timolol at 1% oxygen (hypoxia) seeded at a density of 2.5 × 10⁵  cells/cm² on Integra Matrix Wound Scaffold (MSC/T/H/S) applied to wounds and combined with daily topical timolol applications at 2.9 mM resulted in optimal wound epithelialization 65.6% (24.9% ± 13.0% with MSC/T/H/S vs 41.2% ± 20.1%, in control). Systemic absorption of timolol was below the HPLC limit of quantification, suggesting that with the 7-day treatment, accumulative steady-state timolol concentration is minimal. In the early inflammation stage of healing, the MSC/T/H/S treatment increased CCL2 expression, lowered the pro-inflammatory cytokines IL-1B and IL6 levels, decreased neutrophils by 44.8%, and shifted the macrophage ratio of M2/M1 to 1.9 in the wound, demonstrating an anti-inflammatory benefit. Importantly, expression of the endothelial marker CD31 was increased by 2.5-fold with this treatment. Overall, the combination device successfully improved wound healing and reduced the wound inflammatory response in the diabetic mouse model, suggesting that it could be translated to a therapy for patients with diabetic chronic wounds.

Beta-adrenergic antagonist for the healing of chronic diabetic foot ulcers: study protocol for a prospective, randomized, double-blinded, controlled and parallel-group study

Background

Diabetic foot ulcers (DFUs) are the most common cause of leg amputations and their management is extremely challenging. Despite many advances and expensive therapies, there has been little success in improving outcomes of DFUs. In prior work our laboratory has examined the effects of beta-adrenergic antagonists (βAAs) on skin and skin-derived cells. We have shown that βAAs enhance the rate of keratinocyte migration, promote angiogenesis, and hasten wound healing in scratch wounds in vitro, in animal wound models, and in anecdotally reported cases of chronic wounds that healed successfully after topical application of the βAA timolol. Thus, we propose to test timolol directly on DFUs to determine if it improves healing above the current standard of care (SOC). This study will examine the efficacy and safety of topically applied beta-antagonist Timoptic-XE® (timolol maleate ophthalmic gel forming solution) in subjects with DFUs.

Methods/design

This is a phase two, randomized, double-blinded, controlled, and parallel-group clinical trial with two treatment arms, SOC plus topical Timoptic-XE® and SOC plus a non-biologically active gel (hydrogel, as placebo drug). Study subjects with a DFU will be selected from the Veterans Affairs Northern California Health Care System (VANCHCS). Study duration is up to 31 weeks, with three phases (screening phase for two weeks, active phase for up to 12 weeks, with an additional second consecutive confirmatory visit after 2 weeks, and follow-up phase comprising monthly visits for 4 months). Subjects will apply daily either the topical study drug or the placebo on the foot ulcer for 12 weeks or until healed, whichever comes first. Measurements of wound size and other data will be collected at baseline, followed by weekly visits for 12 weeks, and then a monthly follow-up period.

Discussion

This is a clinical translation study, moving the investigators’ pre-clinical laboratory research into a translational study in which we will analyze clinical outcomes to assess for safety and estimate the efficacy of a topical beta-antagonist in healing of DFUs. The results from this trial may establish new treatment paradigms and safety profile for DFU treatment.

Trial registration

ClinicalTrials.gov, NCT03282981. Registered on June 14th, 2018.

Trace amines produced by skin bacteria accelerate wound healing in mice

Certain skin bacteria are able to convert aromatic amino acids (AAA) into trace amines (TA) that act as neuromodulators. Since the human skin and sweat contain a comparatively high content of AAA one can expect that such bacteria are able to produce TA on our skin. Here we show that TA-producing Staphylococcus epidermidis strains expressing SadA are predominant on human skin and that TA accelerate wound healing. In wounded skin, keratinocytes produce epinephrine (EPI) that leads to cell motility inhibition by β2-adrenergic receptor (β2-AR) activation thus delay wound healing. As β2-AR antagonists, TA and dopamine (DOP) abrogate the effect of EPI thus accelerating wound healing both in vitro and in a mouse model. In the mouse model, the S. epidermidis wild type strain accelerates wound healing compared to its ΔsadA mutant. Our study demonstrates that TA-producing S. epidermidis strains present on our skin might be beneficial for wound healing.

Arif Luqman et al. demonstrate that trace amines accelerate wound healing by antagonizing β2-adrenergic receptor whose activation inhibits cell motility. This study suggests that trace amine-producing Staphylococcus epidermidis strains present on human skin may play a beneficial role for wound healing.

Absorption and Safety of Topically Applied Timolol for Treatment of Chronic Cutaneous Wounds

Objective: There are no safety or absorption studies to guide topical timolol therapy for treatment of chronic wounds. This study was undertaken to address this gap. Approach: A prospective, observational, cross-sectional comparative study of timolol plasma levels in patients after topical administration to a chronic wound, compared with levels in patients after timolol ocular administration for the indication of glaucoma. Results: There was no statistically significant difference in the average plasma level of timolol in wound as compared with glaucoma patients. No bradycardia or wheezing was observed after administration. Innovation: We determined the single time point concentration of timolol in plasma 1 h after application of timolol 0.5% gel-forming solution to debrided chronic wounds, providing insight as to the safety of this emerging off-label treatment. Conclusion: The topical application of timolol for chronic wounds shares the same safety profile as the widely used application of ocular administration for glaucoma.

Stress, inflammation, and eicosanoids: an emerging perspective

Clinical and experimental studies support the notion that adrenergic stimulation and chronic stress affect inflammation, metabolism, and tumor growth. Eicosanoids are also known to heavily influence inflammation while regulating certain stress responses. However, additional work is needed to understand the full extent of interactions between the stress-related pathways and eicosanoids. Here, we review the potential influences that stress, inflammation, and metabolic pathways have on each other, in the context of eicosanoids. Understanding the intricacies of such interactions could provide insights on how systemic metabolic effects mediated by the stress pathways can be translated into therapies for cancer and other diseases.

Psychogenic stress in hospitalized veterinary patients: Causation, implications, and therapies

OBJECTIVE

To review the sources, adverse effects, diagnosis, treatment, and prevention of psychogenic stress in hospitalized human and veterinary patients.

DATA SOURCES

Data were collected by searching PubMed for veterinary and human literature from the past 10 years.

HUMAN DATA SYNTHESIS

Psychogenic stress has been linked to immune suppression; gastrointestinal, cardiovascular, and cutaneous diseases; delayed wound healing; alterations in pain perception; and neurologic impairment. Sources of psychogenic stress include environmental alterations such as excessive noise and light, social and physical factors, sleep disruption, drugs, and underlying disease. Nonpharmacologic options for stress reduction include environmental and treatment modifications, music therapy, and early mobilization. Pharmacologic options include sedation with benzodiazepines and dexmedetomidine. Trazodone and melatonin have been examined for use in sleep promotion but are not currently recommended as standard treatments in ICU.

VETERINARY DATA SYNTHESIS

Activation of the stress response in veterinary patients is largely the same as in people, as are the affected body systems. Possible sources of stress can include social, physical, and environmental factors. No gold standard currently exists for the identification and quantification of stress. A combination of physical examination findings and the results of serum biochemistry, CBC, and biomarker testing can be used to support the diagnosis. Stress scales can be implemented to identify stressed patients and assess severity. Nonpharmacologic treatment options include low-stress handling, pheromones, environmental modifications, and sleep promotion. Pharmacologic options include trazodone, benzodiazepines, dexmedetomidine, and melatonin.

CONCLUSION

The prevalence and clinical significance of psychogenic stress in hospitalized veterinary patients is unknown. Future studies are needed to specifically examine the causative factors of psychogenic stress and the effects of various therapies on stress reduction. The recognition and reduction of psychogenic stress in veterinary patients can lead to improvements in patient care and welfare.

Peritonsillar infiltration of lidocaine with adrenaline is associated with increased risk of secondary post-tonsillectomy haemorrhage. J Laryngol Otol. 2018;132:911-922. [PMID: 30296953 DOI: 10.1017/s0022215118001731]

OBJECTIVES

In order to evaluate the safety of tonsillectomy among children, we retrospectively studied the incidence of post-operative complications, adverse events and their association with peri-operative medication.

METHODS

Data were collected from the medical records of 691 patients aged 1-16 years, including details of post-operative complications (any unplanned contact with the hospital), analgesics, dexamethasone, 5-HT3 antagonists, local anaesthetic and haemostatic agents.

RESULTS

Recovery was complicated in 13.6 per cent of patients, of whom 8.4 per cent were re-admitted to the ward. The most common complication was post-tonsillectomy haemorrhage, experienced by 7.1 per cent of patients. Re-operation under general anaesthesia (for grade III post-tonsillectomy haemorrhage) was required by 4.2 per cent of patients. Peritonsillar infiltration of lidocaine with adrenaline increased the risk of post-tonsillectomy haemorrhage (odds ratio = 4.1; 95 per cent confidence interval = 2.1 to 8.3).

CONCLUSION

Every seventh paediatric patient experienced a complicated recovery after tonsillectomy, caused by post-tonsillectomy haemorrhage in most cases. Local peritonsillar infiltration of lidocaine with adrenaline was associated with an increased risk of post-tonsillectomy haemorrhage.

The humoral immune system of anadromous fish

The immune system of anadromous fish is extremely complex, a direct consequence of their diadromous nature. Hormone levels fluctuate widely throughout their life cycle, as fish move between fresh and salt water. This poses major challenges to the physiology of anadromous fish, including adaptation to very different saline environments, distinct pathogen fingerprints, and different environmental stressors. Elevated cortisol and sex hormone levels inhibit B lymphopoiesis and IgM⁺ antibody responses, while catecholamines, growth hormones and thyroid hormones are generally stimulatory and enhance the humoral immune response. Immunological memory in the form of long-lived plasma cells likely plays important roles in health and survival during the life cycle of anadromous fishes. This review discusses some of the complex immune-endocrine pathways in anadromous fish, focusing on essential roles for B lineage cells in the successful completion of their life cycle. A discussion is included on potential differences in immuno-competence between wild and hatchery-raised fish.

Optical coherence tomography for assessment of epithelialization in a human ex vivo wound model

The ex vivo human skin wound model is a widely accepted model to study wound epithelialization. Due to a lack of animal models that fully replicate human conditions, the ex vivo model is a valuable tool to study mechanisms of wound reepithelialization, as well as for preclinical testing of novel therapeutics. The current standard for assessment of wound healing in this model is histomorphometric analysis, which is labor intensive, time consuming, and requires multiple biological and technical replicates in addition to assessment of different time points. Optical coherence tomography (OCT) is an emerging noninvasive imaging technology originally developed for noninvasive retinal scans that avoids the deleterious effects of tissue processing. This study investigated OCT as a novel method for assessing reepithelialization in the human ex vivo wound model. Excisional ex vivo wounds were created, maintained at air-liquid interface, and healing progression was assessed at days 4 and 7 with OCT and histology. OCT provided adequate resolution to identify the epidermis, the papillary and reticular dermis, and importantly, migrating epithelium in the wound bed. We have deployed OCT as a noninvasive tool to produce, longitudinal "optical biopsies" of ex vivo human wound healing process, and we established an optimal quantification method of re-epithelialization based on en face OCT images of the total wound area. Pairwise statistical analysis of OCT and histology based quantifications for the rate of epithelialization have shown the feasibility and superiority of OCT technology for noninvasive monitoring of human wound epithelialization. Furthermore, we have utilized OCT to evaluate therapeutic potential of allogeneic adipose stem cells revealing their ability to promote reepithelialization in human ex vivo wounds. OCT technology is promising for its applications in wound healing and evaluation of novel therapeutics in both the laboratory and the clinical settings.

The Beta 2 Adrenergic Receptor Antagonist Timolol Improves Healing of Combined Burn and Radiation Wounds

In a scenario involving a nuclear detonation during war or a terrorist attack, acute radiation exposure combined with thermal and blast effects results in severe skin injury. Although the cutaneous injury in such a scenario may not be lethal, it may lead to inflammation, delayed wound healing and loss of the skin barrier, resulting in an increased risk of infection. In this study, we tested the potential use of timolol, a beta-adrenergic receptor antagonist, to improve epidermal wound closure after combined burn and radiation injury using an ex vivo human skin culture model. Daily application of 10 μ M timolol after combined injury (burn and 10 Gy ex vivo irradiation) increased wound epithelialization by 5-20%. In addition, exposure to 10 Gy significantly suppressed epidermal keratinocyte proliferation by 46% at 48 h postirradiation. Similar to what has been observed in a thermal burn injury, the enzyme phenylethanolamine N-methyltransferase (PNMT), which generates epinephrine, was elevated in the combined thermal burn and radiation wounds. This likely resulted in elevated tissue levels of this catecholamine, which has been shown to delay healing. Thus, with the addition of timolol to the wound to block the binding of locally generated epinephrine to the beta-adrenergic receptor, healing is improved. This work suggests that by antagonizing local epinephrine action within the wound, a beta-adrenergic receptor antagonist such as timolol may be a useful adjunctive treatment to improve healing in the combined burn and radiation injury.

The role of β-blockers in dermatological treatment: a review

Many systemic medications have been used off-label in cutaneous diseases. Use of β-adrenergic-blocking agents has risen in popularity among dermatologists since the discovery of their efficacy in treating infantile haemangioma. There has also been an increase in the interest of the applications of β-blockers in other skin disorders. Overall, β-blockers are effective in treating diseases of vascular origin and promote wound healing. They are relatively safe and inexpensive medications that could be included in the armamentarium against skin diseases.

Combination therapy of autologous adipose mesenchymal stem cell-enriched, high-density lipoaspirate and topical timolol for healing chronic wounds

Chronic venous leg ulcers are profoundly debilitating and result in billions in health care expenditure. Thus, there is a quest for engineered and innovative approaches. Herein we present a 63-year-old patient with a 30 year history of venous stasis and left lower extremity ulcers, which have been refractory to standard of care, anticoagulation and venous stripping. The medial ulcer was treated with transplantation of autologous adipose mesenchymal stem cell (AMSC)-enriched, high-density lipoaspirate (HDL) on OASIS wound matrix and compression therapy. The lateral ulcer was treated as a control with standard debridement and compression therapy. Four weeks later, both ulcers received daily topical timolol. Three months later, the test ulcer was completely epithelized and remains healed for over 15 months. However, the control showed minimal signs of improvement. In companion studies in our laboratory, human AMSC were cultured in Minimum Essential Medium Eagle Alpha Modifications (MEMα) with fetal bovine serum (FBS). Timolol was administered to AMSC prior to treatment with epinephrine and 104 bacteria/ml heat-killed Staphylococcus aureus. The MEMα with FBS devoid of AMSC served as a background control. After 24 h, cell culture supernatants and protein lysates were collected to determine cytokine production. There was a statistical significant decrease in pro-inflammatory interleukin-6 and -8 induced by the bacteria (to model the wound environment) in AMSC in the presence of timolol compared with control (p < 0.5). This is the first case of a successful combination of autologous AMSC-enriched, HDL with topical timolol for the healing of chronic venous leg ulcers. Copyright © 2016 John Wiley & Sons, Ltd.

Topical 1% propranolol cream promotes cutaneous wound healing in spontaneously diabetic mice

Diabetic foot ulcers (DFUs) are a constant threat to diabetic patients and can lead to amputations and even death. Intralesional administration of propranolol in diabetic wounds has not been reported previously. This study aimed to investigate the efficacy of propranolol cream in diabetic wounds. Fifty-six spontaneously diabetic mice were divided into the propranolol group and the control group. After preparing full-thickness wounds on the back of the mice, 1% propranolol cream was topically applied to wounds in the experimental group and 0% propranolol cream in controls. The wound sizes were measured and calculated against the original area. The wounds were analyzed up to 21 days after injury. At all evaluation time-points, the wound size (%) in the propranolol group was significantly smaller than in the controls. Epidermal growth factor (EGF) protein expression increased in the experimental vs.

CONTROL GROUP

Vascular endothelial growth factor (VEGF) expression was significantly lower in the experimental vs. control group whereas NG2 proteoglycan was increased throughout the study. However, matrix metallopeptidase (MMP)-9 expression was at first significantly higher in the experimental vs. control group then the MMP-9 protein level in the control group increased and surpassed that in the experimental group. In conclusion, intralesional administration of 1% propranolol cream promotes reepithelialization and regulates abnormal angiogenesis in diabetic wounds. Propranolol cream may become a new drug for the treatment of DFUs.

Differential Response of Dopamine Mediated by β-Adrenergic Receptors in Human Keratinocytes and Macrophages: Potential Implication in Wound Healing

OBJECTIVE

Dopamine is an immunomodulatory neurotransmitter. In the skin, keratinocytes and macrophages produce proinflammatory cytokines and metalloproteinases (MMPs) which participate in wound healing. These cells have a catecholaminergic system that modulates skin pathophysiologic processes. We have demonstrated that dopamine modulates cytokine production in keratinocytes via dopaminergic and adrenergic receptors (ARs). The aim of this study was to evaluate the effect of dopamine and its interaction with β-ARs in human HaCaT keratinocytes and THP-1 macrophages. We evaluated the production of inflammatory mediators implicated in wound healing.

METHODS

Cells were stimulated with dopamine in the absence or presence of the β-adrenergic antagonist propranolol. Wound closure, MMP activity, and the production of IL-8, IL-1β, and IκB/NFκB pathway activation were determined in stimulated cells.

RESULTS

Dopamine did not affect the wound closure in human keratinocytes, but diminished the propranolol stimulatory effect, thus delaying cell migration. Similarly, dopamine significantly decreased MMP-9 activity and the propranolol-induced MMP activity. Dopamine significantly increased the p65-NFκB subunit levels in the nuclear extracts, which were reduced in the presence of propranolol in keratinocytes. On the other hand, dopamine significantly increased MMP-9 activity in THP-1 macrophages, but did not modify the propranolol-increased enzymatic activity. Dopamine significantly increased IL-8 production in human macrophages, an effect that was partially reduced by propranolol. Dopamine did not modify the p65-NFκB levels in the nuclear extracts in THP-1 macrophages.

CONCLUSION

We suggest that the effect of dopamine via β-ARs depends on the physiological condition and the cell type involved, thus contributing to either improve or interfere with the healing process.

Blockade of glucocorticoid receptors improves cutaneous wound healing in stressed mice

Stress is an important condition of modern life. The successful wound healing requires the execution of three major overlapping phases: inflammation, proliferation, and remodeling, and stress can disturb this process. Chronic stress impairs wound healing through the activation of the hypothalamic-pituitary-adrenal axis, and the glucocorticoids (GCs) hormones have been shown to delay wound closure. Therefore, the aim of this study was to investigate the effects of a GC receptor antagonist (RU486) treatment on cutaneous healing in chronically stressed mice. Male mice were submitted to rotational stress, whereas control animals were not subjected to stress. Stressed and control animals were treated with RU486. A full-thickness excisional lesion was generated, and seven days later, lesions were recovered. The RU486 treatment improves wound healing since contraction takes place earlier in RU486-treated in comparison to non-treated mice, and the RU486 treatment also improves the angiogenesis in Stress+RU486 mice when compared to stressed animals. The Stress+RU486 group showed a decrease in inflammatory cell infiltration and in hypoxia-inducible factor-1α and inducible nitric oxide synthase expression; meanwhile, there was an increase in myofibroblasts quantity. In conclusion, blockade of GC receptors with RU486 partially ameliorates stress-impaired wound healing, suggesting that stress inhibits healing through more than one functional pathway.

Methamphetamine Alters the Antimicrobial Efficacy of Phagocytic Cells during Methicillin-Resistant Staphylococcus aureus Skin Infection

Methamphetamine (METH) is a major drug of abuse in the United States and worldwide. Furthermore, Staphylococcus aureus infections and METH use are coemerging public health problems. S. aureus is the single most important bacterial pathogen in infections among injection drug users, with skin and soft tissue infections (SSTI) being extremely common. Notably, the incidence of SSTI, especially in drug users, is difficult to estimate because such infections are often self-treated. Although there is substantial information on the behavioral and cognitive defects caused by METH in drug users, there is a dearth of knowledge regarding its impact on bacterial infections and immunity. Therefore, we hypothesized that METH exacerbates S. aureus skin infection. Using a murine model of METH administration and wound infection, we demonstrated that METH reduces wound healing and facilitates host-mediated collagen degradation by increased expression and production of matrix metalloproteinase-2 (MMP-2). Additionally, we found that METH induces S. aureus biofilm formation and leads to detrimental effects on the functions of human and murine phagocytic cells, enhancing susceptibility to S. aureus infection. Our findings provide empirical evidence of the adverse impact of METH use on the antimicrobial efficacy of the cells that comprise innate immunity, the initial host response to combat microbial infection.

METH is an extremely addictive central nervous system stimulant that is frequently administered by injection. SSTI, common problems among injection drug users, result in serious morbidity for patients and costly hospitalizations for treatment of superficial wounds and incision and drainage of abscesses; however, there has been little etiologic or preventive epidemiological research on this problem. In addition, the evasive nature of injection drug users toward medical care complicates our ability to accurately predict the prevalence of these infections. Hence, this study investigated the impact of METH use on S. aureus skin infection. Our findings demonstrate that this drug of abuse promotes biofilm formation and negatively impacts the wound healing process and innate immune function, exacerbating susceptibility to S. aureus infection. The findings may translate into new knowledge and development of therapeutic and public health strategies to deal with the devastating complications of METH abuse.