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.

Venous leg ulcers (VLUs) produce wound fluid (WF), as a result of inflammatory processes within the wound. It is unclear if WF from different healing phases of VLU has a peculiar biochemical profile and how VLU microenvironment affects the wound healing mechanisms. This study was conducted to evaluate the cytokine/chemokine profiles in WF from distinct VLU phases, in WF- and LPS-stimulated monocytes and treated with glycosaminoglycan Sulodexide, a therapeutic option for VLU healing. WF and plasma were collected from patients with VLU during active inflammatory (Infl) and granulating (Gran) phases. Demographics, clinical characteristics and pain measurements were evaluated. WF, plasma, and THP-1 supernatants were analyzed for 27 inflammatory mediators by multiplex immunoassay. Our results demonstrated that: 1) pain was significantly increased in patients with Infl compared to Gran VLU; 2) cytokine profile of Infl WF was found to be statistically different from that Gran WF, as well significantly increased respect to plasma; 3) LPS- and WF-stimulation of THP-1 cells significantly increased the expression of several cytokines compared to untreated cells; 4) Sulodexide treatment of both LPS- and WF-stimulated THP-1 monocytes was able to significantly down-regulate the release of peculiar inflammatory mediators. Our study highlighted the importance to understand biomolecular processes underlying CVI when providing treatment for chronic VLU. Identification of inflammatory biomarkers in leg ulcer microenvironment, may provide useful tools for predicting healing outcome and developing targeted therapies.

Chronic venous disease (CVeD) is a debilitating condition that affects millions of individuals worldwide. The condition can result in varicose veins, or advance to severe skin changes and venous ulceration. The fundamental basis for CVeD is inflammation within the venous circulation and that it is subjected to increased hydrostatic pressure resulting in increased ambulatory venous pressure. The inflammation involves leukocytes, in particular macrophages and monocytes, inflammatory modulators and chemokines, cytokine expression, growth factors, metalloproteinase (MMP) activity, and many regulatory pathways that perpetuate inflammation. Sulodexide (SDX) is a glycosaminoglycan with pro-fibrinolytic and anti-thrombotic properties. We have previously demonstrated that SDX inhibits the secretion of pro-zymogen MMP-9 from human leukocytes without displacing high molecular complexes of MMP-9. The anti-inflammatory properties of SDX on activated leukocytes have not been well established. We hypothesized that SDX will reduce the secretion of inflammatory mediators from lipopolysaccharide (LPS)-stimulated macrophages. Therefore, we evaluated the effects of SDX on LPS-stimulated macrophage secretion of various inflammatory and anti-inflammatory cytokines, chemokines, and colony stimulating factors. We used microplatebased multiplex immunoassays. LPS-stimulated macrophages in vitro caused a substantial increase of interleukins, tumor necrosis factor, interferon, chemokines and colony stimulating factors. The addition of SDX caused both a dose-dependent and dose-independent decrease in nearly all of the inflammatory cytokines, chemokines and colony stimulating factors. These findings suggest that SDX has a significant effect on the release of inflammatory mediators from macrophages, and may be useful in the treatment of early and advanced CVeD.

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.

Chronic venous disease represents a healthcare problem due to high prevalence and recurrence rates. Studies on chronic venous ulcer wound fluid (CVUWF) have demonstrated increased inflammation and proteolysis which can cause tissue destruction and delayed healing. This review discusses: nearly all known metabolites discovered in the past 25 years in CVUWF studies; the omics approaches characterizing the microenvironment of human venous leg ulcers; and the use of biocompounds as prognostic biomarkers and as possible targets for therapeutic approaches. A biomarker is a biological compound that can be functional or non-functional, specific or non-specific in the diagnosis/prognosis to a disease state and may be quantified to determine progression or regression of disease. Omics studies in CVUWF provide the impetus for future identification of biomarkers within the intricate network in chronic venous disease and set the basis for determining the appropriate combination of molecules that are expressed with the healing status of venous leg ulcers.