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.

Metabolic Reprogramming and Reliance in Human Skin Wound Healing

Impaired skin wound healing is a significant global health issue, especially among the elderly. Wound healing is a well-orchestrated process involving the sequential phases of inflammation, proliferation, and tissue remodeling. Although wound healing is a highly dynamic and energy-requiring process, the role of metabolism remains largely unexplored. By combining transcriptomics and metabolomics of human skin biopsy samples, we mapped the core bioenergetic and metabolic changes in normal acute as well as chronic wounds in elderly subjects. We found upregulation of glycolysis, the tricarboxylic acid cycle, glutaminolysis, and β-oxidation in the later stages of acute wound healing and in chronic wounds. To ascertain the role of these metabolic pathways on wound healing, we targeted each pathway in a wound healing assay as well as in a human skin explant model using metabolic inhibitors and stimulants. Enhancement or inhibition of glycolysis and, to a lesser extent, glutaminolysis had a far greater impact on wound healing than similar manipulations of oxidative phosphorylation and fatty acid β-oxidation. These findings increase the understanding of wound metabolism and identify glycolysis and glutaminolysis as potential targets for therapeutic intervention.

Multifaceted roles of mitochondria in wound healing and chronic wound pathogenesis

Mitochondria are intracellular organelles that play a critical role in numerous cellular processes including the regulation of metabolism, cellular stress response, and cell fate. Mitochondria themselves are subject to well-orchestrated regulation in order to maintain organelle and cellular homeostasis. Wound healing is a multifactorial process that involves the stringent regulation of several cell types and cellular processes. In the event of dysregulated wound healing, hard-to-heal chronic wounds form and can place a significant burden on healthcare systems. Importantly, treatment options remain limited owing to the multifactorial nature of chronic wound pathogenesis. One area that has received more attention in recent years is the role of mitochondria in wound healing. With regards to this, current literature has demonstrated an important role for mitochondria in several areas of wound healing and chronic wound pathogenesis including metabolism, apoptosis, and redox signalling. Additionally, the influence of mitochondrial dynamics and mitophagy has also been investigated. However, few studies have utilised patient tissue when studying mitochondria in wound healing, instead using various animal models. In this review we dissect the current knowledge of the role of mitochondria in wound healing and discuss how future research can potentially aid in the progression of wound healing research.

Evolution of the Chronic Venous Leg Ulcer Microenvironment and Its Impact on Medical Devices and Wound Care Therapies

Studies have reported that the constituents of the wound microenvironment are likely to have critical roles in the degradation and fate of the polymeric matrix and the compounds dissolved in the wound dressing matrix. Thus, chronic wound assessment and the design of effective medical devices and drug products for wound care partly rely on an in-depth understanding of the wound microenvironment. The main aim of this review is to identify and discuss the different stages of chronic wound progression, focusing on the changes in the biochemical composition of the wound microenvironment, with particular attention given to venous leg ulcers (VLUs), as they are one of the most prevalent chronic wound aetiologies. The pathophysiology of venous ulcers is detailed, followed by a thorough review of what is known about the VLU microenvironment and its changes as a function of the evolution of the VLU. Simulating conditions for VLU are then discussed with the view of highlighting potentially relevant simulating media as a function of VLU evolution for a better assessment of biological safety, in particular medical devices intended to be in contact with these wounds.

Drug Delivery Systems for Personal Healthcare by Smart Wearable Patch System

Smart wearable patch systems that combine biosensing and therapeutic components have emerged as promising approaches for personalized healthcare and therapeutic platforms that enable self-administered, noninvasive, user-friendly, and long-acting smart drug delivery. Sensing components can continuously monitor physiological and biochemical parameters, and the monitoring signals can be transferred to various stimuli using actuators. In therapeutic components, stimuli-responsive carrier-based drug delivery systems (DDSs) provide on-demand drug delivery in a closed-loop manner. This review provides an overview of the recent advances in smart wearable patch systems, focusing on sensing components, stimuli, and therapeutic components. Additionally, this review highlights the potential of fully integrated smart wearable patch systems for personalized medicine. Furthermore, challenges associated with the clinical applications of this system and future perspectives are discussed, including issues related to drug loading and reloading, biocompatibility, accuracy of sensing and drug delivery, and largescale fabrication.

Metabolic Profiling Reveals Changes in Serum Predictive of Venous Ulcer Healing

OBJECTIVE

The aim of this study was to identify potential biomarkers predictive of healing or failure to heal in a population with venous leg ulceration.

SUMMARY BACKGROUND DATA

Venous leg ulceration presents important physical, psychological, social and financial burdens. Compression therapy is the main treatment, but it can be painful and time-consuming, with significant recurrence rates. The identification of a reliable biochemical signature with the ability to identify nonhealing ulcers has important translational applications for disease prognostication, personalized health care and the development of novel therapies.

METHODS

Twenty-eight patients were assessed at baseline and at 20 weeks. Untargeted metabolic profiling was performed on urine, serum, and ulcer fluid, using mass spectrometry and nuclear magnetic resonance spectroscopy.

RESULTS

A differential metabolic phenotype was identified in healing (n = 15) compared to nonhealing (n = 13) venous leg ulcer patients. Analysis of the assigned metabolites found ceramide and carnitine metabolism to be relevant pathways. In this pilot study, only serum biofluids could differentiate between healing and nonhealing patients. The ratio of carnitine to ceramide was able to differentiate between healing phenotypes with 100% sensitivity, 79% specificity, and 91% accuracy.

CONCLUSIONS

This study reports a metabolic signature predictive of healing in venous leg ulceration and presents potential translational applications for disease prognostication and development of targeted therapies.

A Review of Recent Advances in Flexible Wearable Sensors for Wound Detection Based on Optical and Electrical Sensing

Chronic wounds that are difficult to heal can cause persistent physical pain and significant medical costs for millions of patients each year. However, traditional wound care methods based on passive bandages cannot accurately assess the wound and may cause secondary damage during frequent replacement. With advances in materials science and smart sensing technology, flexible wearable sensors for wound condition assessment have been developed that can accurately detect physiological markers in wounds and provide the necessary information for treatment decisions. The sensors can implement the sensing of biochemical markers and physical parameters that can reflect the infection and healing process of the wound, as well as transmit vital physiological information to the mobile device through optical or electrical signals. Most reviews focused on the applicability of flexible composites in the wound environment or drug delivery devices. This paper summarizes typical biochemical markers and physical parameters in wounds and their physiological significance, reviews recent advances in flexible wearable sensors for wound detection based on optical and electrical sensing principles in the last 5 years, and discusses the challenges faced and future development. This paper provides a comprehensive overview for researchers in the development of flexible wearable sensors for wound detection.

Wearable Sensors for the Detection of Biomarkers for Wound Infection

Infection represents a major complication that can affect wound healing in any type of wound, especially in chronic ones. There are currently certain limitations to the methods that are used for establishing a clinical diagnosis of wound infection. Thus, new, rapid and easy-to-use strategies for wound infection diagnosis need to be developed. To this aim, wearable sensors for infection diagnosis have been recently developed. These sensors are incorporated into the wound dressings that are used to treat and protect the wound, and are able to detect certain biomarkers that can be correlated with the presence of wound infection. Among these biomarkers, the most commonly used ones are pH and uric acid, but a plethora of others (lactic acid, oxygenation, inflammatory mediators, bacteria metabolites or bacteria) have also been detected using wearable sensors. In this work, an overview of the main types of wearable sensors for wound infection detection will be provided. These sensors will be divided into electrochemical, colorimetric and fluorimetric sensors and the examples will be presented and discussed comparatively.

Metabolomics: Impact of Comorbidities and Inflammation on Sickness Behaviors for Individuals with Chronic Wounds

Significance: Approximately 6.5 million people in the United States suffer from chronic wounds. The chronic wound population is typically older and is characterized by a number of comorbidities associated with inflammation. In addition to experiencing wound-related pain, individuals with chronic wounds commonly experience multiple concurrent psychoneurological symptoms such as fatigue and depression, which delay wound healing. However, these distressing symptoms have been relatively overlooked in this population, although their adverse effects on morbidity are well established in other chronic disease populations. Recent Advances: Inflammation is involved in multiple pathways, which activate brain endothelial and innate immune cells that release proinflammatory cytokines, which produce multiple symptoms known as sickness behaviors. Inflammation-based activation of the kynurenine (KYN) pathway and its metabolites is a mechanism associated with chronic illnesses. Critical Issues: Although putative humoral and neuronal routes have been identified, the specific metabolic variations involved in sickness behaviors in chronic wound patients remain unclear. To improve health outcomes in the chronic wound population, clinicians need to have better understanding of the mechanisms underlying sickness behaviors to provide appropriate treatments. Future Directions: This article presents a synthesis of studies investigating associations between inflammation, metabolic pathways, and sickness behaviors in multiple chronic diseases. The presentation of a theoretical framework proposes a mechanism underlying sickness behaviors in the chronic wound population. By mediating the immune system response, dysregulated metabolites in the KYN pathway may play an important role in sickness behaviors in chronic inflammatory conditions. This framework may guide researchers in developing new treatments to reduce the disease burden in the chronic wound population.

A flexible multiplexed immunosensor for point-of-care in situ wound monitoring

Chronic wounds arise from interruption of normal healing due to many potential pathophysiological factors. Monitoring these multivariate factors can provide personalized diagnostic information for wound management, but current sensing technologies use complex laboratory tests or track a limited number of wound parameters. We report a flexible biosensing platform for multiplexed profiling of the wound microenvironment, inflammation, and infection state at the point of care. This platform integrates a sensor array for measuring inflammatory mediators [tumor necrosis factor-α, interleukin-6 (IL-6), IL-8, and transforming growth factor-β1], microbial burden (Staphylococcus aureus), and physicochemical parameters (temperature and pH) with a microfluidic wound exudate collector and flexible electronics for wireless, smartphone-based data readout. We demonstrate in situ multiplexed monitoring in a mouse wound model and also profile wound exudates from patients with venous leg ulcers. This technology may facilitate more timely and personalized wound management to improve chronic wound healing outcomes.

Why Venous Leg Ulcers Have Difficulty Healing: Overview on Pathophysiology, Clinical Consequences, and Treatment

Venous leg ulcers (VLUs) are one of the most common ulcers of the lower extremity. VLU affects many individuals worldwide, could pose a significant socioeconomic burden to the healthcare system, and has major psychological and physical impacts on the affected individual. VLU often occurs in association with post-thrombotic syndrome, advanced chronic venous disease, varicose veins, and venous hypertension. Several demographic, genetic, and environmental factors could trigger chronic venous disease with venous dilation, incompetent valves, venous reflux, and venous hypertension. Endothelial cell injury and changes in the glycocalyx, venous shear-stress, and adhesion molecules could be initiating events in VLU. Increased endothelial cell permeability and leukocyte infiltration, and increases in inflammatory cytokines, matrix metalloproteinases (MMPs), reactive oxygen and nitrogen species, iron deposition, and tissue metabolites also contribute to the pathogenesis of VLU. Treatment of VLU includes compression therapy and endovenous ablation to occlude the axial reflux. Other interventional approaches such as subfascial endoscopic perforator surgery and iliac venous stent have shown mixed results. With good wound care and compression therapy, VLU usually heals within 6 months. VLU healing involves orchestrated processes including hemostasis, inflammation, proliferation, and remodeling and the contribution of different cells including leukocytes, platelets, fibroblasts, vascular smooth muscle cells, endothelial cells, and keratinocytes as well as the release of various biomolecules including transforming growth factor-β, cytokines, chemokines, MMPs, tissue inhibitors of MMPs (TIMPs), elastase, urokinase plasminogen activator, fibrin, collagen, and albumin. Alterations in any of these physiological wound closure processes could delay VLU healing. Also, these histological and soluble biomarkers can be used for VLU diagnosis and assessment of its progression, responsiveness to healing, and prognosis. If not treated adequately, VLU could progress to non-healed or granulating VLU, causing physical immobility, reduced quality of life, cellulitis, severe infections, osteomyelitis, and neoplastic transformation. Recalcitrant VLU shows prolonged healing time with advanced age, obesity, nutritional deficiencies, colder temperature, preexisting venous disease, deep venous thrombosis, and larger wound area. VLU also has a high, 50-70% recurrence rate, likely due to noncompliance with compression therapy, failure of surgical procedures, incorrect ulcer diagnosis, progression of venous disease, and poorly understood pathophysiology. Understanding the molecular pathways underlying VLU has led to new lines of therapy with significant promise including biologics such as bilayer living skin construct, fibroblast derivatives, and extracellular matrices and non-biologic products such as poly-N-acetyl glucosamine, human placental membranes amnion/chorion allografts, ACT1 peptide inhibitor of connexin 43, sulodexide, growth factors, silver dressings, MMP inhibitors, and modulators of reactive oxygen and nitrogen species, the immune response and tissue metabolites. Preventive measures including compression therapy and venotonics could also reduce the risk of progression to chronic venous insufficiency and VLU in susceptible individuals.

Multisensor Systems and Arrays for Medical Applications Employing Naturally-Occurring Compounds and Materials

The significant improvement of quality of life achieved over the last decades has stimulated the development of new approaches in medicine to take into account the personal needs of each patient. Precision medicine, providing healthcare customization, opens new horizons in the diagnosis, treatment and prevention of numerous diseases. As a consequence, there is a growing demand for novel analytical devices and methods capable of addressing the challenges of precision medicine. For example, various types of sensors or their arrays are highly suitable for simultaneous monitoring of multiple analytes in complex biological media in order to obtain more information about the health status of a patient or to follow the treatment process. Besides, the development of sustainable sensors based on natural chemicals allows reducing their environmental impact. This review is concerned with the application of such analytical platforms in various areas of medicine: analysis of body fluids, wearable sensors, drug manufacturing and screening. The importance and role of naturally-occurring compounds in the development of electrochemical multisensor systems and arrays are discussed.

Chronic venous ulcers: a review on treatment with fibrin sealant and prognostic advances using proteomic strategies

Venous ulcers are the main causes of chronic lower-limb ulcers. The healing difficulties encourage the research and development of new products in order to achieve better therapeutic results. Fibrin sealant is one of these alternatives. Besides being a validated scaffold and drug delivery system, it possesses excellent healing properties. This review covered the last 25 years of the literature and showed that the fibrin sealant is used in various clinical situations to promote the healing of different types of ulcers, especially chronic ones. These are mostly venous in origin and usually does not respond to conventional treatment. Commercially, only the homologous fibrin sealants obtained from human blood are available, which are highly efficient but very expensive. The heterologous fibrin sealant is a non-commercial experimental low-cost product and easily produced due to the abundance of raw material. The phase I/II clinical trial is already completed and showed that the product is safe and promisingly efficacious for the treatment of chronic venous ulcers. In addition, clinical proteomic strategies to assess disease prognosis have been increasingly used. By analyzing liquid samples from the wounds through proteomic strategies, it is possible to predict before treatment which ulcers will evolve favorably and which ones will be difficult to heal. This prognosis is only possible by evaluating the expression of isolated proteins in exudates and analysis using label-free strategies for shotgun. Multicentric clinical trials will be required to evaluate the efficacy of fibrin sealant to treat chronic ulcers, as well as to validate the proteomic strategies to assess prognosis.

Impact of omega-3 fatty acid oral therapy on healing of chronic venous leg ulcers in older adults: Study protocol for a randomized controlled single-center trial

Background

This trial addresses the global problem of chronic venous leg ulcers (CVLUs), wounds that cause significant infirmity for an estimated 9.7 million people annually, mainly older adults with comorbidities. Advanced therapies are needed because standard topical therapies are often ineffective or yield only short-term wound healing. Thus, we are testing a new oral therapy containing the bioactive elements of fish oil, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), for targeting and reducing the high numbers of activated polymorphonuclear leukocytes (PMN) in wound microenvironments that keep CVLUs “trapped” in a chronic inflammatory state.

Methods

This double-blind RCT will include 248 eligible adults ≥ 55 years of age with CVLUs receiving standard care at a large Midwest outpatient wound clinic. Participants are randomized to two groups: 12 weeks of daily oral therapy with EPA + DHA (1.87 g/day of EPA + 1.0 g/day of DHA) or daily oral therapy with placebo. At 0, 4, 8, and 12 weeks, across the two groups, we are pursuing three specific aims: Aim 1. Compare levels of EPA + DHA-derived lipid mediators, and inflammatory cytokines in blood and wound fluid; Subaim 1a. Compare inflammatory cytokine gene expression by PMNs in blood; Aim 2. Compare PMN activation in blood and wound fluid, and PMN-derived protease levels in wound fluid; Aim 3. Compare reduction in wound area, controlling for factors known to impact healing, and determine relationships with lipid mediators, cytokines, and PMN activation. Subaim 3a. Compare frequency of CVLU recurrence and levels of study variables in blood between the randomly assigned two subgroups (continuing EPA + DHA therapy versus placebo therapy beyond week 12) within the EPA + DHA group with healed CVLUs after 3 months of therapy. Subaim 3b. Compare symptoms of pain at all time points and quality of life at first and last time points across the two groups and two subgroups.

Discussion

This trial will provide new evidence about the effectiveness of EPA + DHA oral therapy to target and reduce excessive PMN activation systemically and locally in patients with CVLUs. If effective, this therapy may facilitate healing and thus be a new adjunct treatment for CVLUs in the aging population.

Trial registration

ClinicalTrials.gov, NCT03576989; Registered on 13 June 2018.

Symptoms in Dilating Venous Disease

Lower extremity venous diseases or insufficiency include clinically deteriorating conditions with morphological and functional alterations of the venous system, including venous hypertension, vascular wall structural abnormality, and venous valvar incompetency in association with an inflammatory process. In fact, the same pathophysiological processes are the main underlying mechanisms of other venous insufficiencies in different vascular territories such as Peripheral Varicose Vein (PVV), varicocele, Pelvic Varicosities or Congestion Syndrome (PCS) and Hemorrhoidal Disease (HD). Regarding the anatomical continuity of lower extremity venous system, urogenital system (pampiniform plexus in male and broad ligament and ovarian veins in female) and anorectal venous system, it is reasonable to expect common symptoms such as pain, burning sensation, pruritis, swelling, which arise directly from the involved tissue itself. High coexistence rate of PVV, varicocele/PCS and HD between each other underlines not only the same vascular wall abnormality as an underlying etiology but also the existence of common symptoms originating from the involved tissue in dilating venous disease. Accordingly, it might be reasonable to query the common symptoms of venous dilating disease in other venous vascular regions in patients with complaints of any particular venous territory.

Metabolic Phenotyping in Venous Disease: The Need for Standardization

Venous thromboembolism (VTE), chronic venous disease (CVD), and venous leg ulceration (VLU) are clinical manifestations of a poorly functioning venous system. Though common, much is unknown of the pathophysiology and progression of these conditions. Metabolic phenotyping has been employed to explore mechanistic pathways involved in venous disease. A systematic literature review was performed: full text, primary research articles on the applications of nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS) in human participants and animals were included for qualitative synthesis. Seventeen studies applying metabolic phenotyping to venous disease were identified: six on CVD, two on VLU, and nine on VTE; both animal (n = 6) and human (n = 10) experimental designs were reported, with one study including both. NMR, MS, and MS imaging were employed to characterize serum, plasma, urine, wound fluid, and tissue. Metabolites found to be upregulated in CVD included lipids, branched chain amino acids (BCAA), glutamate, taurine, lactate, and myo-inositol identified in vein tissue. Upregulated metabolites in VLU included lactate, BCAA, lysine, 3-hydroxybutyrate, and glutamate identified in wound fluid and ulcer biopsies. VTE cases were associated with reduced carnitine levels, upregulated aromatic amino acids, 3-hydroxybutyrate, BCAA, and lipids in plasma, serum, thrombus, and vein wall; kynurenine and tricarboxylic acid pathway dysfunction were reported. Future research should focus on targeted studies with internal and external validation.

Associations between miR-661, miR-1202, lncRNA-HOTAIR, lncRNA-GAS5 and MMP9 in differentiated M2-macrophages of patients with varicose veins

BACKGROUND

The venous hypertension is suggested as the main cause of varicose disease. Some mediators and growth factors are known as the responsible of cellular events for the progression of venous perturbations. The aim of this study was to investigate non-coding (nc) RNA and MMP9 expression levels in macrophages differentiated from monocytes of patients with varicose veins.

METHODS

The monocytes were isolated from the whole blood samples by RosetteSep kit and were differentiated to macrophages M2 using M-CSF factor. The based on ncRNA-gene network, lncRNA-GAS5, lncRNA-HOTAIR, miRNA-661, miRNA-1202, and MMP9 were selected. The gene expression levels were measured by RT-qPCR technique.

RESULTS

Data showed that the MMP9 gene expression increased (P=0.003) while the GAS5, miRNA-661, and miRNA-1202 expression levels reduced significantly in the differentiated macrophages of patients (P=0.035, P=0.009, and P=0.015, respectively). Furthermore, the MMP9 gene expression levels were conversely related to the GAS5, HOTAIR, miRNA-661 and miRNA-1202 expression levels.

CONCLUSIONS

The results suggested that the lncRNA-GAS5, miRNA-661, miRNA-1202 and MMP9 are involved in varicose disease.

Chronic Venous Disorders: The Dangerous, the Good, and the Diverse

Chronic venous disorders are common vascular pathology of great medical and socioeconomic impact, characterized by a wide spectrum of clinical manifestations occurring with symptoms and/or signs that vary in type and severity. The predominant pathophysiological mechanisms of chronic venous disease start from the development of venous hypertension from shear stress and reflux, leading to endothelial dysfunction and venous wall dilatation. The altered hemodynamic transduces physical signals into harmful bio-molecular pathways, creating a vicious cycle among shear stress, proteolytic remodeling, and inflammatory processes. This intricate network is further exacerbated by the degradation of protective endothelial glycocalyx. In this special issue, at least three main aspects of these interactions are highlighted: the dangerous, the good, and the diverse, which may help to focus attention on the biomolecular mechanisms and the possible targeted therapy of chronic venous disorders (CVeD).

Variability of MMP/TIMP and TGF-β1 Receptors throughout the Clinical Progression of Chronic Venous Disease

Chronic venous disease (CVeD) is a prevalent condition with a significant socioeconomic burden, yet the pathophysiology is only just beginning to be understood. Previous studies concerning the dysregulation of matrix metalloproteinases (MMPs) and their inhibitors (tissue inhibitors of metalloproteinases (TIMPs)) within the varicose vein wall are inconsistent and disregard clinical progression. Moreover, it is highly plausible that MMP and TIMP expression/activity is affected by transforming growth factor (TGF)-β1 and its signaling receptors (TGFβRs) expression/activity in the vein wall. A case–control study was undertaken to analyze genetic and immunohistochemical differences between healthy (n = 13) and CVeD (early stages: n = 19; advanced stages: n = 12) great saphenous vein samples. Samples were grouped based on anatomic harvest site and subjected to quantitative polymerase chain reaction for MMP1, MMP2, MMP8, MMP9, MMP12, MMP13, TIMP1, TIMP2, TIMP3, TIMP4, TGFβR1, TGFβR2, and TGFβR3 gene expression analysis, and then to immunohistochemistry for immunolocalization of MMP2, TIMP2, and TGFβR2. Decreased gene expression of MMP12, TIMP2, TIMP3, TIMP4, and TGFβR2 was found in varicose veins when compared to controls. Regarding CVeD clinical progression, two facts arose: results across anatomical regions were uneven; decreased gene expression of MMP9 and TGFβR3 and increased gene expression of MMP2 and TIMP3 were found in advanced clinical stages. Most immunohistochemistry results for tunica intima were coherent with qPCR results. In conclusion, decreased expression of TGFβRs might suggest a reduction in TGF-β1 participation in the MMP/TIMP imbalance throughout CVeD progression. Further studies about molecular events in the varicose vein wall are required and should take into consideration the venous anatomical region and CVeD clinical progression.

TGF-β1 in Vascular Wall Pathology: Unraveling Chronic Venous Insufficiency Pathophysiology

Chronic venous insufficiency and varicose veins occur commonly in affluent countries and are a socioeconomic burden. However, there remains a relative lack of knowledge about venous pathophysiology. Various theories have been suggested, yet the molecular sequence of events is poorly understood. Transforming growth factor-beta one (TGF-β1) is a highly complex polypeptide with multifunctional properties that has an active role during embryonic development, in adult organ physiology and in the pathophysiology of major diseases, including cancer and various autoimmune, fibrotic and cardiovascular diseases. Therefore, an emphasis on understanding its signaling pathways (and possible disruptions) will be an essential requirement for a better comprehension and management of specific diseases. This review aims at shedding more light on venous pathophysiology by describing the TGF-β1 structure, function, activation and signaling, and providing an overview of how this growth factor and disturbances in its signaling pathway may contribute to specific pathological processes concerning the vessel wall which, in turn, may have a role in chronic venous insufficiency.

Chronic Venous Insufficiency: Transforming Growth Factor-β Isoforms and Soluble Endoglin Concentration in Different States of Wound Healing

Venous leg ulcer (VLU) is a huge healthcare problem with poorly understood pathophysiology. Transforming growth factor-β (TGF-β) and endoglin (Eng), are inflammatory and wound healing mediators. Eng, co-receptor for TGF-β type-II receptors, may be cleaved forming soluble Eng (sEng), antagonizing TGF-β signaling, a crucial process in vascular pathologies. We evaluated the accumulation in wound fluid (WF) of TGF-β isoforms and sEng in healing stages, showing the effects of sulodexide treatments, a glycosaminoglycan with clinical efficacy in VLU healing. Patients with inflammatory (Infl) and granulating (Gran) VLU were recruited. WFs and THP-1 monocytes exposed to Infl and Gran WF (treated/untreated with sulodexide) were analyzed for TGF-β isoforms and sEng by multiplex immunoassay. In both Infl and Gran WF, TGF-β1 and β2 were similar; TGF-β3 was significantly increased in Infl compared to Gran WFs (p = 0.033). sEng was significantly elevated in Gran compared to Infl WFs (p = 0.002). In THP-1 monocytes there was a significant increase in sEng after co-treatment of WF and sulodexide. The increase in TGF-β3 found in Infl WF highlights its negative effect on wound healing, while the increased levels of sEng in Gran WF affects the leukocyte adhesion/transmigration through the endothelium, reducing the inflammatory response and favoring the wound healing. Glycosaminoglycan sulodexide potentiates the effects of sEng release from monocyte, representing an important therapeutic option for wound healing.

Chronic venous disease - Part II: Proteolytic biomarkers in wound healing

Venous leg ulcers (VLU) are characterized by sustained proteolytic microenvironment impairing the healing process. Wound fluid (WF) reflect the biomolecular activities occurring within the wound area; however, it is unclear if WF from different healing phases have different proteolytic profiles and how VLU microenvironment affects the wound healing mechanisms. We investigated the proteolytic network of WF from distinct VLU phases, and in WF- and LPS-stimulated THP-1 monocytes treated with glycosaminoglycan sulodexide, a well known therapeutic approach for VLU healing. WF were collected from patients with VLU during inflammatory (Infl) and granulating (Gran) phases. WF and THP-1 supernatants were analyzed for nine matrix metalloproteinases (MMP) and four tissue inhibitors of metalloproteinases (TIMP) by multiplex immunoassays. Our results demonstrated that: 1) WF from Infl VLU contained significantly increased concentrations of MMP-2, MMP-9, MMP-12, TIMP-1, and TIMP-2 compared to Gran WF; 2) WF from Gran VLU showed significantly increased levels of MMP-1, MMP-7, MMP-13, and TIMP-4 compared to Infl WF; 3) LPS- and WF-stimulation of THP-1 cells significantly increased the expression of several MMP compared to untreated cells; 4) Sulodexide treatment of both LPS- and WF-stimulated THP-1 significantly down-regulated the release of several MMPs. Our study provides evidence-based medicine during treatment of patients with VLU. WF from Infl and Gran VLU have different MMP and TIMP signatures, consistent with their clinical state. The modulation of proteolytic pathways in wound microenvironment by glycosaminoglycan sulodexide, provide insights for translating research into clinical practice during VLU therapy.

Pathophysiology of wound healing and alterations in venous leg ulcers-review

Venous leg ulcer (VLU) is one of the most common lower extremity ulcerated wound, and is a significant healthcare problem with implications that affect social, economic, and the well-being of a patient. VLU can have debilitating related problems which require weekly medical care and may take months to years to heal. The pathophysiology of VLU is complex, and healing is delayed in many patients due to a persistent inflammatory condition. Patient genetic and environmental factors predispose individuals to chronic venous diseases including VLU. Changes in shear stress affecting the glycocalyx are likely initiating events, leading to activation of adhesion molecules on endothelial cells, and leukocyte activation with attachment and migration into vein wall, microcirculation, and in the interstitial space. Multiple chemokines, cytokines, growth factors, proteases and matrix metalloproteinases are produced. The pathology of VLU involves an imbalance of inflammation, inflammatory modulators, oxidative stress, and proteinase activity. Understanding the cellular and biochemical events that lead to the progression of VLU is critical. With further understanding of inflammatory pathways and potential mechanisms, certain biomarkers could be revealed and studied as both involvement in the pathophysiology of VLU but also as therapeutic targets for VLU healing.

Histology-guided protein digestion/extraction from formalin-fixed and paraffin-embedded pressure ulcer biopsies

Herein we present a simple, reproducible and versatile approach for in situ protein digestion and identification on formalin-fixed and paraffin-embedded (FFPE) tissues. This adaptation is based on the use of an enzyme delivery platform (hydrogel discs) that can be positioned on the surface of a tissue section. By simultaneous deposition of multiple hydrogels over select regions of interest within the same tissue section, multiple peptide extracts can be obtained from discrete histological areas. After enzymatic digestion, the hydrogel extracts are submitted for LC-MS/MS analysis followed by database inquiry for protein identification. Further, imaging mass spectrometry (IMS) is used to reveal the spatial distribution of the identified peptides within a serial tissue section. Optimization was achieved using cutaneous tissue from surgically excised pressure ulcers that were subdivided into two prime regions of interest: the wound bed and the adjacent dermal area. The robust display of tryptic peptides within these spectral analyses of histologically defined tissue regions suggests that LC-MS/MS in combination with IMS can serve as useful exploratory tools.

The expression of inflammatory cytokines, TAM tyrosine kinase receptors and their ligands is upregulated in venous leg ulcer patients: a novel insight into chronic wound immunity

The systemic host defence mechanisms, especially innate immunity, in venous leg ulcer patients are poorly investigated. The aim of the current study was to measure Candida albicans killing activity and gene expressions of pro- and anti-inflammatory cytokines and innate immune response regulators, TAM receptors and ligands of peripheral blood mononuclear cells separated from 69 venous leg ulcer patients and 42 control probands. Leg ulcer patients were stratified into responder and non-responder groups on the basis of wound healing properties. No statistical differences were found in Candida killing among controls, responders and non-responders. Circulating blood mononuclear cells of patients overexpress pro-inflammatory (IL-1α, TNFα, CXCL-8) and anti-inflammatory (IL-10) cytokines as well as TAM receptors (Tyro, Axl, MerTK) and their ligands Gas6 and Protein S compared with those of control individuals. IL-1α is notably overexpressed in venous leg ulcer treatment non-responders; in contrast, Axl gene expression is robustly stronger among responders. These markers may be considered as candidates for the prediction of treatment response among venous leg ulcer patients.

Venous leg ulceration pathophysiology and evidence based treatment

Venous leg ulceration (VLU) is one of the most predominate medical disorders worldwide and in the western hemisphere it affects around 1.5% of the general population and up to 5% of the elderly population. Unfortunately, this trend will only increase given the growth of an aging population worldwide. Understanding its pathophysiology that begins with venous hemodynamic abnormalities and leads to inflammatory alterations with microcirculatory changes is critical to delivering effective curative therapy. As such, the main component to treatment is reversing the underlying venous hypertension and pro-inflammatory milieu using compression treatment along with various adjuvant therapies. Given its impact, a comprehensive multi-pronged approach to care, treatment and prevention is required to reverse the increasing trend that is observed worldwide.