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Cutaneous chronic wounds: A worldwide silent epidemic Chronic wounds develop due to the defective regulation of one or more of the complex cellular and molecular processes involved in proper healing. Here Manuela Martins-Green explores novel potential treatments for wound chronicity. When a wound does not heal within 4 weeks or once aftercare has been provided, it's classed as a chronic wound. It is reported that 1-2% of people in developed countries will experience chronic wounds at least once in their lifetime. In the US alone, they impact ~8.5M people and cost ~$28B/year, not accounting for the pain and suffering patients endure, psychologically, physically and financially. There are several types of chronic wounds: Diabetic wounds develop in diabetic patients and are usually localized to the lower limbs, primarily in the foot, and, hence, the name Diabetic Foot Ulcers (DFUs). Pressure ulcers (bed sores), commonly develop in individuals who suffer from impaired sensation, malnutrition or are confined to a wheelchair or bed. Venous and arterial ulcers develop in individuals with impaired circulation. Other wounds that do not heal may develop from a surgery, an accident, chemical exposure, etc.

The process of wound healing is critical to maintaining homeostasis after injury. Although a considerable amount has been learned about this complex process, much remains unknown. Whereas, studies with human volunteers are ideal given the unique nature of the human skin anatomy and immune system, the lack of such clinical access has made animal models prime candidates for use in preclinical studies. This review aims to discuss the strengths and limitations of the commonly used mammalian species in wound healing studies: murine, rabbit and porcine. Thereafter, a survey of models of various acute wounds such as cutaneous, ear, and implant are presented and representative studies that use them are described. This review is intended to acquaint readers with the vast spectrum of models available, each of which has a distinct utility. At the same time, it highlights the importance of utilising clinical samples to complement investigations conducted in animal models. Through this strategy, it is hoped that forthcoming research may be more reflective of the acute wound healing process as it occurs in humans.

Chronic wounds are a significant health problem worldwide. However, nothing is known about how chronic wounds initiate and develop. Here we use a chronic wound model in diabetic mice and a Systems Biology Approach using nanoString nCounter technology and weighted gene correlation network analysis (WGCNA), with tissues collected at 6, 12, 24 and 48 h post-wounding, to identify metabolic signalling pathways involved in initiation of chronicity. Normalized counts obtained from the nanoString nCounter Mouse Metabolic Panel were used for the WGCNA, which groups genes into co-expression modules to visualize the correlation network. Genes with significant module membership and gene trait significance (p < 0.05) were used to identify signalling pathways that are important for the development of chronicity. The pathway analysis using the Reactome database showed stabilization of PTEN, which down-regulates PI3K/AKT1, which in turn down-regulates Nrf2, as shown by ELISA, thus disabling antioxidant production, resulting in high oxidative stress levels. We find that pathways involved in inflammation, including those that generate pro-inflammatory lipids derived from arachidonic acid metabolism, IFNγ and catecholamines, occur. Moreover, HIF3α is over-expressed, potentially blocking Hif1α and preventing activation of growth factors and cytokines that promote granulation tissue formation. We also find that FGF1 is under-expressed, while thrombospondin-1 is over-expressed, resulting in decreased angiogenesis, a process that is critical for healing. Finally, enzymes involved in glycolysis are down-regulated, resulting in decreased production of pyruvate, a molecule critical for ATP production, leading to extensive cell death and wound paralysis. These findings offer new avenues of study that may lead to the development of novel treatments of CW to be administered right after debridement.

The context of comparing two different groups of subjects that are measured repeatedly over time is considered. Our specific focus is on highly variable count data which have a nonnegligible frequency of zeros and have time trends that are difficult to characterize. These challenges are often present when analyzing bacteria or gene expression data sets. Traditional longitudinal data analysis methods, including generalized estimating equations, can be challenged by the features present in these types of data sets. We propose a Bayesian methodology that effectively confronts these challenges. A key feature of the methodology is the use of Gaussian processes to flexibly model the time trends. Inference procedures based on both sharp and interval null hypotheses are discussed, including for the important hypotheses that test for group differences at individual time points. The proposed methodology is illustrated with next-generation sequencing (NGS) data sets corresponding to two different experimental conditions. In particular, the method is applied to a case study containing bacteria counts of mice with chronic and nonchronic wounds to identify potential wound-healing probiotics. The methodology can be applied to similar NGS data sets comparing two groups of subjects.

Tobacco-specific nitrosamines (TSNAs) are emitted during smoking and form indoors by nitrosation of nicotine. Two of them, N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), are human carcinogens with No Significant Risk Levels (NSRLs) of 500 and 14 ng day-1, respectively. Another TSNA, 4-(methylnitrosamino)-4-(3-pyridyl) butanal (NNA), shows genotoxic and mutagenic activity in vitro. Here, we present additional evidence of genotoxicity of NNA, an assessment of TSNA dermal uptake, and predicted exposure risks through different pathways. Dermal uptake was investigated by evaluating the penetration of NNK and nicotine through mice skin. Comparable mouse urine metabolite profiles suggested that both compounds were absorbed and metabolized via similar mechanisms. We then investigated the effects of skin constituents on the reaction of adsorbed nicotine with nitrous acid (epidermal chemistry). Higher TSNA concentrations were formed on cellulose and cotton substrates that were precoated with human skin oils and sweat compared to clean substrates. These results were combined with reported air, dust, and surface concentrations to assess NNK intake. Five different exposure pathways exceeded the NSRL under realistic scenarios, including inhalation, dust ingestion, direct dermal contact, gas-to-skin deposition, and epidermal nitrosation of nicotine. These results illustrate potential long-term health risks for nonsmokers in homes contaminated with thirdhand tobacco smoke.

A balanced redox state is critical for proper healing. Although human chronic wounds are characterized by high levels of oxidative stress (OS), whether OS levels are critical for chronic wound development is not known. For these studies, we used our chronic wound model in diabetic mice that has similar characteristics as human chronic wounds, including naturally developed biofilm. We hypothesize that OS levels in wound tissues are critical for chronic wound initiation and development. We show that increased OS levels in the wound correlate with increased chronicity. Moreover, without increased OS levels, biofilm taken from chronic wounds and placed in new excision wounds do not create chronic wounds. Similarly, high OS levels in the wound tissue in the absence of the skin microbiome do not lead to chronic wounds. These findings show that both high OS levels and bacteria are needed for chronic wound initiation and development. In conclusion, OS levels in the wound at time of injury are critical for biofilm formation and chronic wound development and may be a good predictor of the degree of wound chronicity. Treating such wounds might be accomplished by managing OS levels with antioxidants combined with manipulation of the skin microbiome after debridement.

Background Thirdhand smoke (THS) is the accumulation of tobacco smoke gases and particles that become embedded in materials. Previous studies concluded that THS exposure induces oxidative stress and hepatic steatosis in liver. Despite the knowledge of the increasing danger of THS exposure, the metabolic disorders caused in liver are still not well defined. Objectives The aim of this study is to investigate the metabolic disorders caused by THS exposure in liver of male mice and to evaluate the effects of an antioxidant treatment in the exposed mice. Methods We investigated liver from three mice groups: non-exposed mice, exposed to THS in conditions that mimic human exposure and THS-exposed treated with antioxidants. Liver samples were analyzed using a multiplatform untargeted metabolomics approach including nuclear magnetic resonance (1H NMR), liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) and laser desorption/ionization mass spectrometry imaging (MSI), able to map lipids in liver tissues. Results Our multiplatform approach allowed the annotation of eighty-eight metabolites altered by THS exposure, including amino acids, nucleotides and several types of lipids. The main dysregulated pathways by THS exposure were D-glutamine and D-glutamate metabolism, glycerophospholipid metabolism and oxidative phosphorylation and glutathione metabolism, being the last two related to oxidative stress. THS-exposed mice also presented higher lipid accumulation and decrease of metabolites involved in the phosphocholine synthesis, as well as choline deficiency, which is related to Non-Alcoholic Fatty Liver Disease and steatohepatitis. Interestingly, the antioxidant treatment of THS-exposed mice reduced the accumulation of some lipids, but could not revert all the metabolic alterations, including some related to the impairment of the mitochondrial function. Conclusions THS alters liver function at a molecular level, dysregulating many metabolic pathways. The molecular evidences provided here confirm that THS is a new factor for liver steatosis and provide the basis for future research in this respect.

Diabetics chronic wounds are characterized by high levels of oxidative stress (OS) and are often colonized by biofilm-forming bacteria that severely compromise healing and can result in amputation. However, little is known about the role of skin microbiota in wound healing and chronic wound development. We hypothesized that high OS levels lead to chronic wound development by promoting the colonization of biofilm-forming bacteria over commensal/beneficial bacteria. To test this hypothesis, we used our db/db -/- mouse model for chronic wounds where pathogenic biofilms develop naturally after induction of high OS immediately after wounding. We sequenced the bacterial rRNA internal transcribed spacer (ITS) gene of the wound microbiota from wound initiation to fully developed chronic wounds. Indicator species analysis, which considers a species' fidelity and specificity, was used to determine which bacterial species were strongly associated with healing wounds or chronic wounds. We found that healing wounds were colonized by a diverse and dynamic bacterial microbiome that never developed biofilms even though biofilm-forming bacteria were present. Several clinically relevant species that are present in human chronic wounds, such as Cutibacterium acnes, Achromobacter sp., Delftia sp., and Escherichia coli, were highly associated with healing wounds. These bacteria may serve as bioindicators of healing and may actively participate in the processes of wound healing and preventing pathogenic bacteria from colonizing the wound. In contrast, chronic wounds, which had high levels of OS, had low bacterial diversity and were colonized by several clinically relevant, biofilm-forming bacteria such as Pseudomonas aeruginosa, Enterobacter cloacae, Corynebacterium frankenforstense, and Acinetobacter sp. We observed unique population trends: for example, P. aeruginosa associated with aggressive biofilm development, whereas Staphylococcus xylosus was only present early after injury. These findings show that high levels of OS in the wound significantly altered the bacterial wound microbiome, decreasing diversity and promoting the colonization of bacteria from the skin microbiota to form biofilm. In conclusion, bacteria associated with non-chronic or chronic wounds could function as bioindicators of healing or non-healing (chronicity), respectively. Moreover, a better understanding of bacterial interactions between pathogenic and beneficial bacteria within an evolving chronic wound microbiota may lead to better solutions for chronic wound management.

It has been extremely difficult to study the mechanisms involved in the development of chronic wounds because they do not contain a single defect. One of the critical parameters for proper healing is the redox state of the wound. The redox state is maintained by a balance between oxidant and antioxidant molecules. Oxidative stress (OS) is present in tissues and cells when there is an imbalance between the levels of reactive oxygen species (ROS) and the ability of antioxidants in the tissues and cells to remove these species and repair the damage they cause. Low levels of ROS are important for initiation and progression of proper healing, whereas high levels of ROS derail the cell and molecular mechanisms involved in healing leading to cell death and paralyzes of the healing process. Antioxidants inactivate reactive species by donating their electrons to these species and preventing them from capturing electrons from other important molecules such as DNA, proteins, and lipids. When the levels of antioxidant molecules are not sufficient to detoxify the cells and tissues from excessive OS, damage occurs. Examples of reactive radical forms of O2 are superoxide (O2•−), hydroxyl (•OH), and peroxyl (LOO•), whereas examples of nonradical reactive forms are hydrogen peroxide (H2O2), hypochlorous acid (HClO), and peroxynitrite (ONOO). Antioxidants can work through enzymatic or nonenzymatic reactions that can occur intracellularly in the cytosol and/or in organelles such as the mitochondria or in the extracellular environment. Chronic wounds in humans have high levels of OS. This is particularly true for chronic wounds of diabetic patients. A better understanding of how wounds become chronic is critical for future success in the treatment of such wounds after debridement. Because high levels of OS are present in chronic wounds and are critical for chronic wound initiation and development, we speculate that treatment of human chronic wounds with antioxidants both systemically and locally after debridement, coupled with other treatments such as antibiotics, may be effective in resolving chronicity.

Cell–matrix interactions that occur during wound healing are extraordinarily complex, varying among cell types and changing over time owing to altered expression of matrix receptors and matrix molecules over time as healing proceeds. In this chapter, we summarize critical cell–matrix interactions associated with wound healing, discussing the matrix receptors involved in these interactions and major signaling pathways regulated by these interactions. We then compare cell–matrix interactions in normal adult scarring wound healing with fetal scarless healing. Finally, we discuss implications of cell–matrix interactions for regenerative medicine, focusing on the ways this information is used to promote regenerative wound healing.

© 2016 American Chemical Society. Thirdhand smoke (THS) is the contamination that persists after secondhand tobacco smoke has been emitted into air. It refers to the tobacco-related gases and particles that become embedded in materials, such as the carpet, walls, furniture, blankets, and toys. THS is not strictly smoke, but chemicals that adhere to surfaces from which they can be released back into the air, undergo chemical transformations and/or accumulate. Currently, the hazards of THS are not as well documented as the hazards of secondhand smoke (SHS). In this Perspective, we describe the distribution and chemical changes that occur as SHS is transformed into THS, studies of environmental contamination by THS, human exposure studies, toxicology studies using animal models and in vitro systems, possible approaches for avoiding exposure, remediation of THS contamination, and priorities for further research.

Objective: Impaired and chronic wounds occur due to defects in one or more of the overlapping stages of healing. However, problems related to the vascular system are critical for nonhealing, and chronic wounds in humans often show the presence of fibrin cuffs/clots. We hypothesized that these clots are due to alterations in platelet function; hence, we have investigated whether alterations in platelet function are present during impaired healing. Approach: Platelets were subjected to different agonists to determine the rate of aggregation and evaluate the molecules involved in adhesion and aggregation that could lead to faster thrombosis and potentially contribute to impaired wound healing. Results: We show that wounding of TNFSF14/LIGHT-/- mice, which have impaired healing, leads to an enhanced response in platelet aggregation and a faster time to blood vessel occlusion (thrombosis). In addition, after wounding, platelets from these mice have increased levels of P-selectin, integrin αIIbβ3, and phosphatidylserine, molecules that contribute to platelet adhesion. They also have more extensive open canalicular system than platelets of control mice, suggesting increased surface area for interactions upon activation. Innovation: These results show a novel function for TNFSF14/LIGHT during wound healing. Conclusion: The absence of TNFSF14/LIGHT from the cell surface of platelets causes rapid platelet aggregation and thrombus formation that may contribute to impaired healing by reducing the ability of the blood vessels to transport nutrients and oxygen and other molecules needed for proper healing.

Third-hand smoke (THS) is a recently discovered environmental health hazard that results from accumulation and aging of second-hand smoke (SHS) toxins on surfaces of environments where smoking has occurred. Our objective was to determine whether there is a dose-dependent effect of THS exposure on biological markers of harm (BMH) using an in vivo exposure system that mimics exposure of humans to THS. THS exposure generated from as low as the 10 cigarettes-smoking regimen, resulted in increased circulating inflammatory cytokines, tumor necrosis factor alpha, interleukin 1 alpha, and granulocyte macrophage colony-stimulating factor. We also found that there was an increase in adrenocorticotropic hormone and superoxide dismutase and a decrease in ATP levels in liver tissue. Many of the altered BMH that are related to oxidative stress and decrease in ATP levels, suggest mitochondrial dysfunction. THS exposure generated from the 20 and 40 cigarettes-smoking regimen resulted in further damage. Our studies are important because virtually nothing is known about the physiological damage caused by different levels of THS exposure. These studies can also serve to educate the public on the dangers of THS and the BMH we identified can potentially be used in the clinic, once verified in exposed humans.

Author(s): Burnley, Pamela; Chen, Wang-Ping; Dobrzhinetskaya, Larissa; Jin, Zhen-Min; Jung, Haemyeong; Liebermann, Robert; Martins-Green, Manuela; Schubnel, Alexandre; Wang, Yanbin; Zhang, Junfeng | Abstract: By keenly probing mantle rheology, interactions of deformations and phase transitions, and microscopic features, he made major contributions to petrology, mineralogy, and earthquake science.

Very little is known about lipid function during wound healing, and much less during impaired healing. Such understanding will help identify what roles lipid signaling plays in the development of impaired/chronic wounds. We took a lipidomics approach to study the alterations in lipid profile in the LIGHT−/− mouse model of impaired healing which has characteristics that resemble those of impaired/chronic wounds in humans, including high levels of oxidative stress, excess inflammation, increased extracellular matrix degradation and blood vessels with fibrin cuffs. The latter suggests excess coagulation and potentially increased platelet aggregation. We show here that in these impaired wounds there is an imbalance in the arachidonic acid (AA) derived eicosonoids that mediate or modulate inflammatory reactions and platelet aggregation. In the LIGHT−/− impaired wounds there is a significant increase in enzymatically derived breakdown products of AA. We found that early after injury there was a significant increase in the eicosanoids 11-, 12-, and 15-hydroxyeicosa-tetranoic acid, and the proinflammatory leukotrienes (LTD4 and LTE) and prostaglandins (PGE2 and PGF2α). Some of these eicosanoids also promote platelet aggregation. This led us to examine the levels of other eicosanoids known to be involved in the latter process. We found that thromboxane (TXA2/B2), and prostacyclins 6kPGF1α are elevated shortly after wounding and in some cases during healing. To determine whether they have an impact in platelet aggregation and hemostasis, we tested LIGHT−/− mouse wounds for these two parameters and found that, indeed, platelet aggregation and hemostasis are enhanced in these mice when compared with the control C57BL/6 mice. Understanding lipid signaling in impaired wounds can potentially lead to development of new therapeutics or in using existing nonsteroidal anti-inflammatory agents to help correct the course of healing.

Cigarette smoking is a major risk factor for acute coronary thrombosis. In fact, both active/first-hand smoke and passive/second-hand smoke exposure are known to increase the risk of coronary thrombosis. Although recently a new risk has been identified and termed third-hand smoke (THS), which is the residual tobacco smoke contaminant that remains after a cigarette is extinguished, it remains to be determined whether it can also enhance the risk of thrombogenesis, much like first-hand smoke and second-hand smoke. Therefore, the present studies investigated the impact of THS exposure in the context of platelet biology and related disease states. It was found that THS-exposed mice exhibited an enhanced platelet aggregation and secretion responses as well as enhanced integrin GPIIb-IIIa activation. Furthermore, it was found that THS exposure shortens the tail bleeding time and the occlusion time in a model of thrombosis. Thus, our data demonstrate for the first time (at least in mice) that THS exposure increases the risk of thrombosis-based disease states, which is attributed, at least in part, to their hyperactive platelets.

Wound healing is a complex process that involves sequential phases that overlap in time and space and affect each other dynamically at the gene and protein levels. We previously showed that insulin accelerates wound healing by stimulating faster and regenerative healing. One of the processes that insulin stimulates is an increase in monocyte/macrophage chemotaxis. In this study, we performed experiments in vivo and in vitro to elucidate the signaling transduction pathways that are involved in insulin-induced monocyte/macrophage chemotaxis. We found that insulin stimulates THP-1 cell chemotaxis in a dose-dependent and insulin receptor-dependent manner. We also show that the kinases PI3K-Akt, SPAK/JNK, and p38 MAPK are key molecules in the insulin-induced signaling pathways that lead to chemoattraction of the THP-1 cell. Furthermore, both PI3K-Akt and SPAK/JNK signaling involve Rac1 activation, an important molecule in regulating cell motility. Indeed, topical application of Rac1 inhibitor at an early stage during the healing process caused delayed and impaired healing even in the presence of insulin. These results delineate cell and molecular mechanisms involved in insulin-induced chemotaxis of monocyte/macrophage, cells that are critical for proper healing., Summary: Insulin regulates multiple signaling pathways leading to monocyte/macrophage chemotaxis into the wound tissue, involving -Akt, SPAK/JNK, and p38 MAPK which in turn are involved in Rac1 activation. Furthermore, these results augment our understanding of the insulin-regulated wound inflammatory response.

Third-hand smoke (THS) is a newly discovered environmental health hazard that results from accumulation and aging of second-hand smoke (SHS) toxins on surfaces where smoking has occurred. Our objective was to determine whether there is a time-dependent effect of THS exposure on health. Using an in vivo exposure mouse system that mimics exposure of humans to THS, we investigated its effects on biomarkers found in serum, and in liver and brain tissues. Mice were exposed to THS for 1, 2, 4, or 6 months and brain, liver, and serum were collected. We found that THS exposure, as early as 1 month, resulted in increased circulating inflammatory cytokines, tumor necrosis factor by an order of magnitude of 2 and granulocyte macrophage colony-stimulating factor by an order of magnitude of 1.5 and in increases in the stress hormone epinephrine and the liver damage biomarker aspartate aminotransferase (AST), increased in magnitude 1.5 and 2.5 times compared with controls, respectively. THS exposure for 2 months resulted in further damage and at 4 and 6 months, many factors related to oxidative stress were altered and caused molecular damage. We also found that the mice became hyperglycemic and hyperinsulinimic suggesting that insulin resistance (IR) may be a significant consequence of long-term exposure to THS. In conclusion, time-dependent THS exposure has a significant effect on health as early as 1 month after initiation of exposure and these alterations progressively worsen with time. Our studies are important because virtually nothing is known about the effects of increased THS exposure time, they can serve to educate the public on the dangers of THS, and the biomarkers we identified can be used in the clinic, once verified in exposed humans.

Sustained increase in microvessel permeability results in cell and tissue damage. To date, it has not been possible to safely and specifically block increased microvessel permeability in vivo. We showed that insulin stimulates angiogenesis and that the new microvessels are associated with more αSMA-producing cells, suggesting greater stability. In this study, we show that local injection of insulin under the skin of mice significantly inhibits thrombin-induced microvessel permeability and that insulin improves the barrier function of primary human endothelial cells under conditions that mimic endothelium in vivo. These findings indicate that insulin antagonizes thrombin-induced microvessel permeability. At the cell and molecular levels, we show that insulin interferes with thrombin-induced VE-cadherin signaling by decreasing the ability of thrombin to induce VE-cadherin translocation to the cytoskeleton/nuclear compartment, leading to microvessel leakage. Simultaneously, the rapid activation of Src by insulin followed by the activation of Rac1, a small GTPase involved in cytoskeletal reorganization, leads to the maintenance of endothelial barrier, short-circuiting the slower thrombin-induced Src-RhoA signaling that leads to endothelial permeability. This novel mechanism by which insulin inhibits thrombin-induced permeability provides support for the use of insulin treatment in pathological conditions that involve blood-barrier dysfunction, especially as resuscitation treatment methods for extensive burns, sepsis, and other severe pathological conditions.

Background: Hepatic steatosis results from the increase of accumulation of lipids in the liver, decrease of beta fatty acid oxidation and/or decrease in the export to peripheral tissue by apolipoproteins. Previously, we showed that third hand smoke (THS) toxins result in hepatic steatosis in mice. Objective: The goal of this paper was two-fold: (1) To determine whether THS toxins alter key molecules involved in beta fatty acid metabolism and (2) to determine whether the levels of apolipoprotein B is decreased in THS-exposed mice leading to decrease export of lipid from the liver. Methodology: Mice were exposed to THS toxins for 6 months before performing the studies shown here. THS-exposed mice were also placed on western diet (WD) for five months or treated with AICAR to determine how THS-toxins affect the lipid metabolism of these animals. Results: THS-exposed mice do not show significant difference in the levels of key fatty acid metabolism enzymes (CPT1, ACC, IDH2 and LCAD) compared to the control, suggesting THS toxins do not decrease the levels of these enzymes. THS-exposed mice have lower levels of SIRT3 and ATP. These mice also have lower IDH2 activity. THS-exposed mice also have lower levels of apolipoprotein B compared to control, suggesting the excess fatty acids, which are converted to TG in the liver, are not being transported to peripheral tissue for usage or storage. Conclusion: These results suggest that even though THS toxins do not alter the levels of fatty acid metabolism enzymes, exposure result in lower levels of SIRT3 and lower IDH2 activity resulting in lower production of ATP in THS-exposed mice. THS toxins exposure also decrease of transport of lipids out of the liver by decreasing the levels of apolipoprotein B. Consequently, THS-exposed mice have an increase in lipid accumulation in the liver resulting in hepatic steatosis.

Chronic wounds represent a major healthcare burden, costing $25 billion annually, and are associated with high mortality. We previously reported that cutaneous wound healing represented only 0.1% ($29.8 million) of the National Institutes of Health budget. This current study focuses on quantifying the contribution by federal agencies other than the National Institutes of Health for fiscal year 2012. Federal databases including USA Spending, Veterans Affairs, Tracking Accountability in Government Grants Systems, Health Services Research Projects in Progress, and Patient-Centered Outcomes Research Institute, were searched for individual projects addressing wound healing. Twenty-seven projects were identified, totaling funding of $16,588,623 (median: $349,856). Four sponsor institutions accounted for 74% of awarded funds: Department of the Army, National Science Foundation, Department of Veterans Affairs, and Agency for Healthcare Research & Quality. Research projects and cooperative agreements comprised 44% and 37% of awarded grants. New applications and continuing projects represented 52% and 37%. Wound healing represented 0.15% of total medical research funded by the non-National Institutes of Health federal sector. Compared with potential impact on US public health, federal investment in wound research is exiguous. This analysis will draw attention to a disproportionately low investment in wound research and its perils to American public health.

Chronic cutaneous wounds are a major burden on patients, healthcare providers, and the US healthcare system. This study, carried out in part by the Wound Healing Society's Government Regulatory Committee, aimed to evaluate the current state of National Institutes of Health funding of cutaneous wound healing-related research projects. National Institutes of Health Research Portfolio Online Reporting Tools Expenditures & Results system was used to identify wound healing projects funded by the National Institutes of Health in the 2012 fiscal year. Research projects focusing on cutaneous wound prevention/education, mechanisms, complications, treatment, or imaging/monitoring were included in the analysis. Ninety-one projects were identified, totaling a collective funding of $29,798,991 and median funding of $308,941. Thirteen institutes/centers from the National Institutes of Health were responsible for awarding funds; three of which (National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institute of General Medical Sciences, National Institute of Diabetes and Digestive and Kidney Diseases) accounted for 60.4% of the grant funding. The predominant funding mechanisms included R01 (48.3%), R43 (14.3%), and R21 (9.9%). New applications and pre-existing applications accounted for 39.6 and 55.0% of the awarded grants, respectively. Grants awarded to investigators affiliated with universities accounted for 68.1% of grants and 25.3% were to investigators in the private sector. This analysis of current National Institutes of Health funding may facilitate more transparency of National Institutes of Health-allocated research funds and serve as an impetus to procure additional support for the field of wound healing.

© 2016 The Author(s). Third hand smoke (THS) is the accumulation of second hand smoke (SHS) toxins on surfaces in homes, cars, clothing and hair of smokers. It is known that 88M US nonsmokers ≥3 years old living in homes of smokers are exposed to THS toxicants and show blood cotinine levels of ≥0.05 ng/ml, indicating that the toxins are circulating in their circulatory systems. The goal of the present study is to investigate the mechanisms by which THS causes impaired wound healing. We show that mice living under conditions that mimic THS exposure in humans display delayed wound closure, impaired collagen deposition, altered inflammatory response, decreased angiogenesis, microvessels with fibrin cuffs and a highly proteolytic wound environment. Moreover, THS-exposed mouse wounds have high levels of oxidative stress and significantly lower levels of antioxidant activity leading to molecular damage, including protein nitration, lipid peroxidation and DNA damage that contribute to tissue dysfunction. Furthermore, we show that elastase is elevated, suggesting that elastin is degraded and the plasticity of the wound tissue is decreased. Taken together, our results lead us to conclude that THS toxicants delay and impair wound healing by disrupting the sequential processes that lead to normal healing. In addition, the lack of elastin results in loss of wound plasticity, which may be responsible for reopening of wounds.

Objective: Impaired and chronic wounds occur due to defects in one or more of the overlapping stages of healing. However, problems related to the vascular system are critical for nonhealing, and chronic wounds in humans often show the presence of fibrin cuffs/clots. We hypothesized that these clots are due to alterations in platelet function; hence, we have investigated whether alterations in platelet function are present during impaired healing.

Translated regions distinct from annotated coding sequences have emerged as essential elements of the proteome. This includes upstream open reading frames (uORFs) present in mRNAs controlled by the integrated stress response (ISR) that show "privileged" translation despite inhibited eukaryotic initiation factor 2-guanosine triphosphate-initiator methionyl transfer RNA (eIF2·GTP·Met-tRNA(i )(Met)). We developed tracing translation by T cells to directly measure the translation products of uORFs during the ISR. We identified signature translation events from uORFs in the 5' untranslated region of binding immunoglobulin protein (BiP) mRNA (also called heat shock 70-kilodalton protein 5 mRNA) that were not initiated at the start codon AUG. BiP expression during the ISR required both the alternative initiation factor eIF2A and non-AUG-initiated uORFs. We propose that persistent uORF translation, for a variety of chaperones, shelters select mRNAs from the ISR, while simultaneously generating peptides that could serve as major histocompatibility complex class I ligands, marking cells for recognition by the adaptive immune system.

Background: Third hand smoke (THS) forms when second hand smoke (SHS) tobacco toxins accumulate on surfaces such as walls, carpets and clothing and can result in adverse health effects. Objective: This study was designed to investigate the mechanism of THS-induced hepatic steatosis. Methodology: We used an in vivo exposure system that mimics exposure of humans to THS to investigate the effects of THS on hepatic lipid metabolism. THS-exposed mice were treated either with the liver-damaging drug, Nacetyl- p-aminophenol (APAP/Tylenol) to increase oxidative stress or with the antioxidants N-acetyl-cysteine and α- Tocopherol which decrease oxidative stress. Results: THS-exposed mice have higher levels of superoxide dismutase activity and H2O2 levels. However, no significant changes in activity of the antioxidant enzymes catalase and glutathione peroxidase were found, implying the presence of high levels of hydrogen peroxide in the liver. Furthermore, THS-exposed mice also have a lower NADP+/NADPH ratio, indicating decreased ability of these mice to combat oxidative stress. THS-exposed mice show a decrease in ATP production, increase in aspartate aminotransferase (AST) activity, as well as increased molecular damage (lipid peroxidation, protein nitrosylation and DNA damage). Treating THS-exposed mice with APAP/Tylenol enhances the THS-induced damage whereas treating with antioxidants reduces the damage. THSexposed mice also have lower sirtuin 1 (SIRT1) levels compared to controls which decreased activation of 5' AMPactivated protein kinase (AMPK) and increased sterol regulatory element binding protein 1c (SREBP1c). Conclusion: THS-exposed mice on a normal diet have increased oxidative stress and damage mediated by oxidative stress, which results in alterations to the SIRT1/AMPK/SREPB1c signaling pathway. Increasing oxidative stress results in enhanced THS-induced damage whereas decreasing oxidative stress causes improvement in the THS-induced liver damage. Our results show that THS is a new risk factor contributing to the development of liver steatosis and highlight the danger of THS in general.

Proper healing of cutaneous wounds progresses through a series of overlapping phases. Nonhealing wounds are defective in one or more of these processes and represent a major clinical problem. A critical issue in developing treatments for chronic wounds is the paucity of animal models to study the mechanisms underlying the defects in healing. Here we show that deletion of tumor necrosis factor superfamily member 14 (TNFSF14/LIGHT) leads to impaired wounds in mice that have the characteristics of nonchronic and chronic ulcers. These wounds show: (1) excessive production of cytokines, in particular three chemokines (KC/CXCL8, MCP-1/CCL2, IP-10/CXCL10), that may be key to the abnormal initiation and resolution of inflammation; (2) defective basement membranes, explaining blood vessel leakage and disruption of dermal/epidermal interactions; and (3) granulation tissue that contains high levels of Coll III, whereas Coll I is virtually absent and does not form fibrils. We also see major differences between nonchronic and chronic wounds, with the latter populated by bacterial films and producing eotaxin, a chemokine that attracts leukocytes that combat multicellular organisms (which biofilms can be considered to be). This new mouse model captures many defects observed in impaired and chronic human wounds and provides a vehicle to address their underlying cell and molecular mechanisms.

Wound healing is a natural process involving several signaling molecules and cell types over a significant period of time. Although current dressings help to protect the wound from debris or infection, they do little in accelerating the healing process. Insulin has been shown to stimulate the healing of damaged skin. We have developed an alginate sponge dressing (ASD) that forms a hydrogel capable of providing a moist and protective healing environment. By incorporating insulin-loaded poly(d,l-lactide-co-glycolide) (PLGA) microparticles into ASD, we successfully stabilized and released insulin for up to 21 days. Insulin release and water absorption and transfer through the ASD were influenced by altering the levels of poly(ethylene glycol) (PEG) in the dressing matrix. Bioactivity of released insulin can be maintained for at least 10 days, demonstrated using a human keratinocyte migration assay. Results showed that insulin-loaded PLGA microparticles, embedded within PEG-ASD, functioned as an effective long-term delivery platform for bioactive insulin.

Background: There is broad consensus regarding the health impact of tobacco use and secondhand smoke exposure, yet considerable ambiguity exists about the nature and consequences of thirdhand smoke (THS). Objectives: We introduce definitions of THS and THS exposure and review recent findings about constituents, indoor sorption–desorption dynamics, and transformations of THS; distribution and persistence of THS in residential settings; implications for pathways of exposure; potential clinical significance and health effects; and behavioral and policy issues that affect and are affected by THS. Discussion: Physical and chemical transformations of tobacco smoke pollutants take place over time scales ranging from seconds to months and include the creation of secondary pollutants that in some cases are more toxic (e.g., tobacco-specific nitrosamines). THS persists in real-world residential settings in the air, dust, and surfaces and is associated with elevated levels of nicotine on hands and cotinine in urine of nonsmokers residing in homes previously occupied by smokers. Much still needs to be learned about the chemistry, exposure, toxicology, health risks, and policy implications of THS. Conclusion: The existing evidence on THS provides strong support for pursuing a programmatic research agenda to close gaps in our current understanding of the chemistry, exposure, toxicology, and health effects of THS, as well as its behavioral, economic, and sociocultural considerations and consequences. Such a research agenda is necessary to illuminate the role of THS in existing and future tobacco control efforts to decrease smoking initiation and smoking levels, to increase cessation attempts and sustained cessation, and to reduce the cumulative effects of tobacco use on morbidity and mortality.

Resolution of inflammation is critical for normal wound healing. Inflammation is prolonged and fails to resolve properly in chronic wounds. We used in vivo and in vitro approaches to show that vascular endothelial growth factor (VEGF) induces macrophage apoptosis and to delineate mechanisms involved in this process. VEGF inhibition during wound healing leads to an increased number of macrophages remaining in wounds, suggesting the involvement of VEGF in removal of these cells from the wound. If this effect has physiological relevance, it likely occurs via apoptosis. We show that VEGF increases apoptosis of macrophages in vitro using Annexin V-FITC staining and caspase activation. Microarray analysis, reverse transcription-polymerase chain reaction, and immunoblotting showed that VEGF increases the expression of tumor necrosis factor superfamily member 14 (TNFSF14/LIGHT) in macrophages. We also show that in macrophages LIGHT promotes apoptosis through the lymphotoxin beta receptor. Moreover, inhibition of LIGHT prevents VEGF-induced death, suggesting that LIGHT mediates VEGF-induced macrophage apoptosis. Taken together, our results identify a novel role for VEGF and for LIGHT in macrophage apoptosis during wound healing, an event critical in the resolution of inflammation. This finding may lead to the development of new strategies to improve resolution of inflammation in problematic wounds.

Permeability of the endothelium occurs early in the angiogenic process, resulting from the initial loss or disruption of endothelial cell-cell adhesions, which is followed by endothelial cell contraction, forming paracellular gaps. We are interested in the angiogenesis and endothelial permeability induced by inflammation; thus, we have chosen to study mechanisms involved in the endothelial permeability stimulated by the angiogenic chemokine Interleukin-8 (IL-8/CXCL8). We have found that IL-8 induces permeability in a receptor-dependent process requiring the activation of Gαi and the regulation of PKA activity. Pertussis toxin abolishes the effect of IL-8 on endothelial permeability, while a PKA inhibitor, H89, results in a similar effect. Thus, regulation of the level of PKA activity appears critical in IL-8-induced permeability, potentially due to the differential regulation of molecules downstream of PKA, such as SREBP and RhoA. PKA and cAMP are thought to inhibit the activation of SREBP, a protein involved in lipid metabolism; we have also found, using inhibitors of SREBP that this molecule is likewise necessary for the permeability stimulated by IL-8. Furthermore, SREBP inhibitors block IL-8-induced activation of RhoA, a GTPase that has been implicated in permeability induced by multiple factors. Taken together, our results indicate a possible signal transduction pathway downstream of the IL-8 receptors, in which the inhibition of cAMP production, and, thus, of PKA activation, by Gαi increases SREBP activity, resulting in increased RhoA activity, leading to endothelial cell contraction and gap formation, increasing endothelial permeability. Because IL-8 plays important roles in the permeability observed in inflammatory disorders, knowledge of the signaling mechanisms induced by this chemokine during permeability increases may be used to identify targets for drug development. This project has been funded by the American Heart Association.

Exposure to cigarette smoke has detrimental effects on the early stages of wound repair but not much is known about the effects of smoke on the development of the healing (granulation) tissue. Cell proliferation, migration, differentiation, and deposition of ECM are critical processes for normal granulation tissue (GT) formation. Here we investigate the effects of MSW (“first-hand smoke”) and SSW (the main component of “secondhand smoke”) smoke on wound healing in mice that have been smoking for 9 months. We show that both MSW and SSW smoke adversely affect wound contraction and closure. The keratinocytes accumulate at the edge of the wound and the GT is deficient in fibroblasts and ECM. Moreover, by immunolabeling for α-SMA, we found that the myofibroblasts remained at the edges of the wound rather than penetrating the GT, potentially contributing to the lack of wound contraction. To test the possibility that smoke inhibits cell migration, we plated primary human fibroblasts in between two interstitial collagen gels, treated the cultures with the smoke solutions and found that cell migration into the gels was inhibited. Furthermore, using the collagen gel contraction assay, we showed that cigarette smoke components inhibit gel contraction. To further decipher which components of the smoke contribute to delayed wound closure, we fractionated SSW smoke solutions into polar and nonpolar components using solid phase extraction cartridges. We show that both the polar and nonpolar fractions delay wound closure in vivo and that the nonpolar fraction inhibits cell migration whereas the polar faction increases cell survival. We are currently pursuing these studies by further fractionation of these two phases with the goal of identifying the specific component(s) in each fraction that cause these effects on cell migration and survival. Identification of the components in cigarette smoke that lead to delayed wound healing and eliminating them from cigarettes could help those exposed to secondhand smoke heal faster.